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  • 2000-2004
  • 1995-1999
  • 1985-1989  (869)
  • 1890-1899
  • 1987  (869)
  • Biochemistry and Biotechnology  (560)
  • Atomic, Molecular and Optical Physics  (275)
  • breast cancer
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  • 2000-2004
  • 1995-1999
  • 1985-1989  (869)
  • 1890-1899
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  • 1
    ISSN: 1436-2813
    Keywords: breast cancer ; local recurrent lesion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract From 1975 through 1985, nine patients with a local recurrent lesion (LRL) of breast cancer to the skin flap of the chest wall were treated. Four had undergone primary mastectomies in our clinic and the other five were referred from other surgeons, following signs of recurrence. Aggressive topical therapy, such as resection or irradiation, proved effective in eradicating the LRL in all cases, thereby indicating that topical therapy is useful for improving quality of life. Adjuvant systemic chemo-immunoendocrine therapy is also required for patients with LRL, to increase longevity. Seven of the patients died of a distant metastasis within 66 months after the onset of LRL.
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  • 2
    ISSN: 1436-2813
    Keywords: extended radical mastectomy ; breast cancer ; 5-year survival rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A new operative method of extended radical mastectomy enables complete resection of the axillary and internal mammary lymph nodes. In this paper, we present the histological analysis of the internal mammary involvement, and the estimated 5 year survival rate, of 100 patients with breast cancer of Stage I, II or III, who underwent this operation. The incidences of axillary and internal mammary involvements were 41 per cent and 17 per cent, respectively. The metastases in the internal mammary lymph node chain were located from just below the supraclavicular vein to the third intercostal space along the internal mammary vessels. The types of lymphatic invasion observed in the internal mammary chain were lymph node metastases in 88 per cent, metastatic lesion in the lymphoid tissue in 29 per cent and cancer cell emboli in the lymphatic channel in 71 per cent. The overall estimated 5 year survival rate was 90.5 per cent. Where there was internal mammary involvement, the estimated 5 year survival rates for those with no axillary lymph node metastasis, those with fewer than 3 metastatic axillary lymph nodes, and those with more than 4 metastatic axillary lymph nodes were 100 per cent, 80 per cent and 31.2 per cent, respectively. Although the assumption that more aggressive surgical removal of the primary lesion and the regional lymphatic spread gives a higher cure rate has not been proved, this extended radical mastectomy with adjuvant chemoendocrine therapy seems to give a higher 5 year survival rate for patients with internal mammary involvement.
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  • 3
    ISSN: 1436-2813
    Keywords: breast cancer ; estrogen ; CEA ; immunohistochemical study ; early postoperative recurrence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this paper is to determine whether the incidence of estrogen-, progesterone-, CEA-, and ferritin-positive staining of primary tumors, by using the PAP method, is related to the prognosis of breast cancer status. A significantly higher incidence (71 per cent) of CEA-positive tumors was observed in patients who had a recurrence of breast cancer within 2 years after radical operation. Patients, whose tumors were positive in estrogen or negative in CEA, showed a relatively good prognosis, even after a recurrence of the disease. Distant metastases were seen in most of the patients positive in CEA (78 per cent). Before the recurrence of breast cancer, those patients positive in progesterone had a good prognosis. After the recurrence, however, there was no relationship between the prognosis of recurrent disease and the progesterone-staining of primary tumors. Our data suggest that the immunohistological staining of estrogen, progesterone and CEA might offer the effective prognostic indices in breast cancer patients.
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  • 4
    ISSN: 1436-2813
    Keywords: breast cancer ; mass screening ; physical examination ; interval cancer ; breast self-examination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In Tokushima prefecture, mass screening for breast cancer has been conducted using physical examination alone since 1970. Breast cancer was detected in 116 of 111,571 screened women up until 1984. The detection rate was 0.08 per cent in total examinees, 0.13 per cent in initial examinees, and 0.04 per cent in subsequent examinees. The patients with breast cancer were divided into three groups, i.e., 62 cases detected at initial screening, 28 cases detected at subsequent screenings, and 26 interval cancer cases. 510 patients with breast cancer in the outpatient clinic were serving as controls. The stage classification and nodal involvement were significantly different between the mass screening group and the control group, but not significantly different among the three groups. The interval cases were detected at an early stage. The survival rates were not significantly different between the three groups and the control group. Efforts should be doubled to educate women about the proper method of breast self-examination in order to promote the early detection of breast cancer.
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  • 5
    ISSN: 1436-2813
    Keywords: breast cancer ; mass screening ; early detection ; mobile unit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Since 1977, mass screening for breast cancer has been carried out in Miyagi prefecture, Japan. The main activities involve itinerant screening in the communities and group screening at the workplaces. The first step in this screening is the physical examination; the second step, for women with suspicious findings, is examination by mammography and ultrasonography, in a specially equipped mobile unit. The number of subjects screened over a seven-year period ending in March, 1984, was 94.953. Mammography was performed on 4,485 subjects (4.7 per cent) Breast cancer was detected in 116 subjects (0.12 per cent). Since 1980, 2,292 high risk subjects have undergone mammography as the first step screening. The detection rate (0.35 per cent) for this group was higher than for the general subjects examined. Therefore, mammography performed in a mobile unit is a suitable approach for the detecting and diagnosing of breast cancer.
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  • 6
    ISSN: 1573-2592
    Keywords: Complements ; C3 ; C4 ; oral cancer ; cervical cancer ; breast cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The total hemolytic complement activity of CH50 and its fractions C3 and C4 was determined in the sera of 196 patients with carcinoma of the oral cavity, 172 patients with carcinoma of the uterine cervix, and 166 patients with breast cancer. The values were compared with those of 18 patients with mammary dysplasia, 32 patients with mild to moderate dysplasia of the cervix, and 100 healthy, normal age- and sex-matched controls. No alterations in CH50, C3, and C4 were observed in the sera of patients with benign lesions, whereas a significant rise in the three factors was observed in all the cancer patients studied. The complement activity increased significantly with the progression of the disease up to stage III and remained persistently elevated thereafter. Patients who had a clinical cure had normal levels of CH50, C3, and C4, whereas the values remained elevated in patients who were still undergoing treatment for residual lesions.
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  • 7
    ISSN: 1573-7217
    Keywords: 5 FU infusion ; breast cancer ; fluorouracil (5 FU) ; Hickman catheter ; infusion chemotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Twenty-five patients with refractory, metastatic carcinoma of the breast were treated with continuous ambulatory 5-fluorouracil (5 FU) infusion (200 to 300 mg/m2/day) through a chronic indwelling central venous catheter. All patients had had extensive previous treatment, including hormonal therapy in 20/25 patients (80%), radiation therapy in 18/25 patients (72%), and an average of 4.6 previous chemotherapy drugs per patient (range 1–10). Twenty-three of 25 patients (92%) had had previous bolus 5 FU. Seventeen of 25 patients (68%) had two or more metastatic sites of involvement and 17/25 patients (68%) had visceral involvement. Results: complete remission −1/25 (4%), partial remission −7/25 (28%), stable disease −6/25 (24%), and progressive disease −11/25 (44%), for an overall response rate of 8/25 (32%). Median duration of response was 6 months. Toxicities included hand-foot syndrome, mucositis, diarrhea, and nausea and vomiting, and required treatment interruption and/or dose attenuation in 9/25 patients (36%). No myelosuppression or serious catheter-related problems were seen. We conclude that continuous 5 FU infusion is a potentially effective salvage treatment that may provide meaningful palliation in some patients with carcinoma of the breast, in spite of extensive previous treatment.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 10 (1987), S. 217-227 
    ISSN: 1573-7217
    Keywords: breast cancer ; chromosome translocation ; gene amplification ; growth factor receptors ; neuroblastoma ; oncogenes ; prognosis ; proto-oncogenes ; small cell lung cancer ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-7217
    Keywords: breast cancer ; oestrogen receptor ; pathological type ; screening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In view of the possible introduction of screening programmes, this study compares oestrogen receptor (ER) levels in a series of women whose primary tumour was detected by screening and an age-matched consecutive series of women whose tumours were diagnosed after symptomatic presentation. Because of missing data and other statistical considerations, the comparison was made using T1 and T2 categories of tumour only. Some differences were found: the distribution of ER levels was significantly different in the two groups, with more extreme values in the symptomatic series; the screening series, however, had more moderate/rich ER levels than the symptomatic group. Tumours of special pathological type (for example, tubular, cribriform, lobular, medullary, and mucoid) were more likely to be ER-moderate or -rich, and there were more of these tumours in the screening series. The relationship of these findings to tumour growth rate is discussed. The study highlights the difficulty of obtaining sufficient tissue for conventional DCC biochemical assays from the small non-invasive tumours found by screening, and suggests that newer alternative methods employing monoclonal antibodies may be required for such types of tumour.
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  • 10
    ISSN: 1573-7217
    Keywords: alternating regimens ; breast cancer ; endocrine effects ; hormone therapy ; medroxyprogesterone acetate ; tamoxifen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The endocrine effects of alternating tamoxifen and medroxyprogesterone acetate have been evaluated in 26 post-menopausal patients with metastatic breast cancer. Endocrine evaluations included the RIA determination of plasma levels of sex-hormone binding globulin, follicle-stimulating hormone, luteinizing hormone, estradiol, prolactin, cortisol, and testosterone. The evaluation of the study parameters at different intervals during therapy indicates that with this schedule an alternate sequential effect on the endocrine system is achievable because each drug exerts its own endocrine activity that is completely reversed when the other drug is administered. We can hypothesize that the same alternate activity as seen on the endocrine system could be obtained also on other tissues and organs including tumors.
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  • 11
    ISSN: 1573-7217
    Keywords: breast cancer ; conservative treatment ; mastectomy ; physical problems ; psychosocial outcome ; rehabilitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Breast cancer is the most common neoplasm in occidental women, yet very little information is available about the rehabilitation needs of these patients. This report reviews in detail the physical, psychological, social, and financial problems identified by fifty women during the first month after primary surgical treatment. The most frequently reported problems were physical and psychological. Patients undergoing modified radical mastectomy (MRM) are compared with patients receiving segmental mastectomy and primary radiotherapy (SM). There were few differences between the two surgical treatment groups; however, patients in the MRM group reported more difficulty with clothing and body image, while the SM group had more disruption of recreation and social activities. Information about the rehabilitation problems of patients with this common neoplasm should be helpful to patients and to the members of the health care team who are helping them recover.
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  • 12
    ISSN: 1573-7217
    Keywords: breast cancer ; cytology ; estrogen receptor ; fine needle aspiration ; immunohistochemistry ; monoclonal antibody
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A monoclonal antibody (H222) prepared against purified estrogen receptor has been demonstrated to be highly specific and sensitive in an immunohistochemical assay for the detection and quantification of estrogen receptor in human breast carcinoma biopsy specimens. To evaluate the clinical applicability of this assay in cytologic specimens, response to therapy in 12 patients with recurrent breast cancer was correlated with H222 antibody localization in specimens obtained by fine needle aspiration biopsy. All 7 patients with positive H222 responded to hormone therapy (1 complete and 3 partial remissions and 3 stable disease), while 1 of 5 patients with negative H222 responded (1 stable disease). This experience suggests a role for immunohistochemical estrogen receptor determinations in prediction of response to hormonal therapy in patients whose tumor is accessible only to aspiration biopsy. Special care in the handling and interpretation of specimens is essential to optimal application of this method.
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  • 13
    ISSN: 1573-7217
    Keywords: adjuvant therapy ; breast cancer ; estrogen receptors ; tamoxifen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The paper presents interim results of an on-going randomized trial of adjuvant tamoxifen (40 mg daily for 2 years) versus no endocrine adjuvant therapy in postmenopausal women with early breast cancer. A total of 1407 patients were included in the study between November 1976 through June 1984. Estrogen receptor (ER) data were available on 1184 patients (84%). The median follow-up was 53 months. Adjuvant tamoxifen increased the recurrence-free interval (P〈0.01) but had no significant effect on overall survival. Treatment failures were reduced by 25% (P〈0.01) and deaths by 7% (P〉0.05). Tamoxifen mainly decreased the frequency of loco-regional recurrence whereas distant metastases were less affected. The treatment effect was independent of tumor stage but was significantly related to the estrogen receptor (ER) content of the primary tumor. Tamoxifen appeared ineffective among ER negative patients, and the greatest effect was seen among those with high levels of ER. The results indicate that the main mechanism of action of adjuvant tamoxifen is similar to that suggested in advanced disease, i.e. an interaction with the estrogen receptor.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 9 (1987), S. 53-59 
    ISSN: 1573-7217
    Keywords: methylthioadenosine phosphorylase ; prognostic markers ; breast cancer ; aneuploidy ; steroid receptors ; DNA S-phase ; flow cytometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Methylthioadenosine (MTA) phosphorylase activity was measured in 47 biopsies from primary breast cancers (n = 34) and metastatic tumors (n = 13). Most specimens were also evaluated by DNA flow cytometry and determination of estrogen and progesterone receptor contents. Median MTA phosphorylase activity was 317 pmol/mg protein/min (range 50-1312 pmol/mg protein/min), but great variations were observed. Samples from four individuals had very low MTA phosphorylase activity (≤70 pmol/mg protein/min). No correlation with aneuploidy, receptor status, or the presence of metastases in the lymph nodes could be demonstrated. However, MTA phosphorylase activity showed a significant (p = 0.009) negative correlation with the fraction of cells in the S-phase of the cell cycle.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 9 (1987), S. 123-128 
    ISSN: 1573-7217
    Keywords: breast cancer ; prognostic factors ; progesterone binding cyst protein ; tumor markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Different secretory proteins have been evaluated as possible tumor markers in breast cancer. In this study progesterone binding cyst protein (PBCP) has been quantitated in breast tumor tissue. We report on a correlation of PBCP in cytosols of primary breast cancer, with known prognostic factors. A significant difference (p 〈 0.001, Chi-square) in the frequency of PBCP-negative patients in clinical Stage I and Stage II is found. This was mainly attributed to a difference between T1 and T2 tumors, with less contribution from nodal status. A biological function of PBCP in breast cancer is not known. The distribution of PBCP in our patients has a close resemblance with expected number of node positive patients, suggesting that PBCP as a tumor marker may aid in providing prognostic information in breast cancer patients.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 9 (1987), S. 135-143 
    ISSN: 1573-7217
    Keywords: breast cancer ; biological factors ; race ; social factors ; survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Longer survival for white women than black women with breast cancer has been observed even when relative survival rates are used and stage at diagnosis is controlled. This study compared prognostic factors in relation to survival for 144 white women and 67 black women with breast cancer diagnosed 1969 to 1979 and identified through the tumor registry. Data were obtained from medical records, the registry, death certificates, and pathology files. Median survival was 7.5 years for whites, vs. 5.6 years for blacks. Significant differences between races were also observed for histological type and grade of tumor, presenting symptoms, and health status at diagnosis. Although Cox multiple regression analyses showed pathological stage at diagnosis and number of positive nodes to be the best predictors of survival in both whites and blacks, the differences in histological type observed in this sample merits further research; blacks have fewer well-differentiated tumors, the type associated with positive estrogen receptors and with better survival.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 9 (1987), S. 151-154 
    ISSN: 1573-7217
    Keywords: breast cancer ; estrogens ; phenolphthalein ; progesterone receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary There is a structural similarity between phenolphthalein and the triphenylethylenes which are known to interact with the estrogen receptor of human breast tissue. Phenolphthalein (10 µM) competed with estrogen for binding to MCF-7 human breast cancer cells in tissue culture and induced the synthesis of the progesterone receptor. The antiestrogen 4-hydroxytamoxifen blocked progesterone receptor induction both by estradiol and by phenolphthalein. Both estradiol (0.1 nM) and phenolphthalein (10 µM) stimulated cell growth as measured by DNA and protein assays. This growth stimulation was blocked by 4-hydroxytamoxifen. Phenolphthalein glucuronide, the major phenolphthalein metabolite, did not inhibit estrogen binding, induce progesterone receptor synthesis, or stimulate MCF-7 cell growth in culture. Yellow phenolphthalein, an impure phenolphthalein preparation used in nonprescription laxative preparations, had similar properties to pure phenolphthalein. Physicians should be aware of the weak estrogenic action of phenolphthalein, especially when recommending laxatives for breast cancer patients with confirmed liver and mesenteric metastases.
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  • 18
    ISSN: 1573-7217
    Keywords: adjuvant chemotherapy ; breast cancer ; progesterone receptor ; prognosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The prognostic significance of progesterone receptor activity (PgR) with regard to the estimated relapse-free survival (RFS) was studied in 350 one-center patients with primary breast cancer. All receptor assays were performed in one laboratory; PgR levels 〉10 fmol/mg protein were considered positive. Univariate as well as multivariate statistical analyses were used to examine the prognostic significance of several variables. Eighty-nine of the 350 patients received adjuvant CMF chemotherapy (cyclophosphamide, methotrexate, and 5-fluorouracil). The median observation period was 69 months (range 12–125 months). In the group of 261 patients who did not receive adjuvant CMF, the PgR-status lacked prognostic significance; only the lymph node status significantly affected the RFS (p〈0.00001). In contrast, in the CMF-treated group of patients, the PgR-status was the most powerful predictor of recurrence (p〈0.0001). The menopausal and the lymph-node status increased the predictive value of PgR (p〈0.001). Premenopausal CMF-treated patients with PgR+ tumors had a significantly longer RFS than those with PgR− tumors (p〈0.02). The present data urge the need for a reappraisal of the prognostic significance of PgR and of the mechanism of action of adjuvant chemotherapy in primary breast cancer.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 9 (1987), S. 207-211 
    ISSN: 1573-7217
    Keywords: breast cancer ; labelling index ; node-negative ; prognosis ; survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The DNA labelling index (LI), representing the fraction of S-phase cells, was studied in 76 patients operated on for breast cancer from 1975 to 1979. No patient had lymph node involvement following axillary dissection (N−), and no adjuvant medical treatment was given. Patients were classified in one of two groups according to the median LI. Patient distribution by age, tumour size, and receptor status was identical in both groups. A higher frequency of grade 3 tumours was noted in the group with an LI above the median value. The cell proliferation rate was an important discriminative factor for metastatic potential. The probability of survival at 8 years for patients with a high LI was significantly lower than that of patients with low LI (36% versus 100%;p〈0.001). Relapse-free survival at 8 years was respectively 56% and 83% (p〈0.02). At 2 years, these values were 75% and 100%, indicating the early occurrence of metastases. By contrast, the LI had no prognostic value concerning loco-regional disease recurrence or survival after the appearance of metastasis. No relationship was found in this study between survival and other prognostic factors, namely tumour size, histological grade, or hormone receptor level. The LI currently appears to be the best prognostic factor for N− breast cancer. High risk patients identified by this method could thus be offered adjuvant medical treatment.
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  • 20
    ISSN: 1573-7217
    Keywords: biological markers ; breast cancer ; two-dimensional electrophoresis ; estrogen receptor ; progesterone receptor ; polypeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Postmitochondrial and cytosolic polypeptides were extracted from human breast tumors and non-malignant breast tissue and analyzed using high resolution two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Approximately 800–1000 postmitochondrial and 600–800 silver stained cytosolic polypeptides were detected over the pH range of 4.8 to 7.5 and molecular weight range of 18–120 kDa. The 2D-PAGE patterns of polypeptides from normal and malignant tissue were very similar, although both qualitative and quantitative polypeptide differences were noted. Six cytosolic polypeptides (pI/molecular weight × 10−3) 5.20/80 kDa, 5.75/43, 6.25/40, 5.43/35, 5.45/34.5, 5.50/34 and 6.15/24 were expressed only in malignant tissues. One constitutive polypeptide, 7.25/52, was not detected in any of the malignant tissue samples. Quantitatively, marked differences in spot density were noted in polypeptides localized mainly in the molecular weight ranges of 22–40 kDa and pI ranges of 5.65–7.00. A general increase in polypeptide expression was noted in malignant tissues as compared to normal. Twenty-two polypeptides were significantly and consistently increased in tumor samples while only one polypeptide was decreased. One polypeptide, p24 (6.15/24) was expressed in greatest concentrations in tumors which also expressed the greatest estrogen receptor content. Expression of p24 was markedly reduced in normal tissue and malignant tissues expressing low levels of estrogen and progesterone receptors.
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  • 21
    ISSN: 1573-7217
    Keywords: breast cancer ; estrogen ; progestin ; antiprogestin ; antiestrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have compared the effects of the progestin R5020 and the antiprogestin RU486 on the growth of the MCF-7 and T47D breast cancer cell lines. Differences between the two compounds were demonstrated in several parameters. 1. Estradiol was required for the efficient inhibition of cell growth of both lines by R5020 but not by RU486. Therefore in the total absence of estrogen (phenol-red free medium), the effects of the two drugs on cell growth were dissociated, RU486 remaining inhibitory while R5020 was inactive. 2. The proteins secreted by cells were differently affected, since R5020 induced a 48K protein and decreased the production of the estrogen-regulated 52K protein, while RU486 had no effect on these two parameters. 3. The morphology of cells treated by R5020 was more altered in the presence of estradiol than in its absence, while that of cells treated by RU486 was not affected whether or not estradiol was present. 4. There was a greater reduction of estrogen receptor sites in MCF-7 cells produced by R5020 than by RU486. Even though the two drugs appear to act through the same progesterone receptor and to inhibit total protein secretion, it is likely that they exert their antiproliferative effects on cultured breast cancer cells by different mechanisms. R5020 antagonizes the stimulation produced by estradiol. RU486 by contrast exerts a more direct progesterone receptor mediated inhibitory effect requiring no synergism by estradiol and therefore does not act through a partial progestin activity.
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  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 10 (1987), S. 133-144 
    ISSN: 1573-7217
    Keywords: breast cancer ; chemotherapy ; drug accumulation ; endocrine therapy resistance ; glutathione ; multidrug resistance ; P-glycoprotein ; radiation therapy resistance ; resistance mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Considerable insight into the problem of drug resistance has emerged in the past few years. An understanding of why tumors develop drug resistance is now at hand both from theoretical points of view and from experimental and clinical data. Experimental models of drug resistance, particularly related to the surface P-glycoprotein, have been remarkably successful in teaching us why tumor cells in culture develop resistance to common therapeutic agents. In this panel discussion, the clinical relevance of these and other proposed mechanisms will be examined, with the hope of providing an up-to-date overview on this exciting field.
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  • 23
    ISSN: 1573-7217
    Keywords: breast cancer ; DNA ; ploidy ; prognosis ; static cytometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Nuclear DNA content was measured by static cytophotometry in smears from breast carcinomas from 80 women, and the results were correlated with other prognostic variables and survival using multivariate statistical analysis. 49% of patients had diploid tumors and 51% hyperdiploid tumors. There was a strong correlation between DNA ploidy and axillary lymph node status, tumor size, ER status, and short term survival (median follow-up 40 months). Of all parameters measured, ploidy showed the strongest correlation with survival, and was a significant prognostic indicator even when other prognostic factors were taken into account.
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  • 24
    Electronic Resource
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    Breast cancer research and treatment 9 (1987), S. 111-121 
    ISSN: 1573-7217
    Keywords: breast cancer ; cloning efficiency ; karyotype ; MCF-7 cells ; nude mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary MCF-7 human breast cancer cells are used widely for studies of tumor biology and hormone mechanism of action. Conflicting results have often been obtained in studies reported from different laboratories. In this report several biological properties were studied in four MCF-7 cell lines obtained from different laboratories. MCF-7 (ATCC), MCF-7, MCF-7 (KO), and MCF-7 (S) demonstrated similar morphology in monolayer culture. Chromosome analysis revealed that three of the lines shared several structural chromosome alterations and marker chromsomes; however, MCF-7 (ATCC) was distinctly different with virtually no chromosomal alterations shared in common with the other lines. All four lines contained variable amounts of estrogen receptor (ER) and progesterone receptor (PgR). The growth rate of MCF-7 (ATCC) was 50% slower than that of the other lines, and, unlike the other three lines, cell proliferation was unaffected by estrogen or antiestrogen treatment despite the presence of receptors. Cloning efficiency of the four lines varied over a 10-fold range. Tumorigenicity in athymic nude mice also varied considerably among these lines. MCF-7 (ATCC) grew well in ovariectomized nude mice, while the other lines required estrogen supplementation. MCF-7 (S) and MCF-7 grew rapidly with estrogen supplementation; MCF-7 (KO) grew very slowly. Antiestrogen therapy inhibited growth of MCF-7, MCF-7 (S), and MCF-7 (KO) tumors, but it had no effect on MCF-7 (ATCC). These data demonstrate that MCF-7 lines from different laboratories may have unique biological properties, despite having a similar karyotype (MCF-7, MCF-7 (S), MCF-7 (KO)). The fundamental differences in karyotype and biological properties of the MCF-7 (ATCC), and the previously reported differences in DNA restriction fragment polymorphism analyses, demonstrate that this line is derived from an entirely different patient. Investigators should carefully document the source and identity of MCF-7 cells used in published experiments.
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  • 25
    ISSN: 1573-7217
    Keywords: breast cancer ; obesity ; receptor status ; recurrence ; risk factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relationship between obesity and breast cancer has been investigated in 1281 Auckland breast cancer patients. Using a definition of obesity as a Body Mass Index (BMI) of ≥ 28 kg/m2, 179 (14%) breast cancer patients were classified as obese. The heights, weights, and BMI of 822 breast cancer patients aged 35–64 compared to 518 randomly selected Auckland women of similar age showed no significant difference. Within the breast cancer patients, there was no variation in nodal status or estrogen and progesterone receptor status between obese and non-obese women. However, tumours 〉 5 cm occurred significantly more often in obese patients. Time to recurrence was reduced in obese women with tumours ≤ 5 cm, no tumour in the axillary nodes, positive estrogen or progesterone receptor, and without metastases at the time of presentation of the disease. Although obesity has not been shown to influence breast cancer incidence, an effect on tumour recurrence is seen in patients with less advanced disease. This is similar to other reports which suggest that obesity is a weak but positive risk factor for recurrence.
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  • 26
    Electronic Resource
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    Breast cancer research and treatment 9 (1987), S. 165-173 
    ISSN: 1573-7217
    Keywords: anti-ER therapy ; breast cancer ; clonogenic assay ; endocrine therapy ; growth factors ; non-breast cancer ; receptors ; resistance mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 27
    ISSN: 1573-7217
    Keywords: breast cancer ; estrogen receptor ; ovariectomy ; urinary androgens ; hormonal factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Estrogen receptor (ER) status and urinary androgen (A) concentration were simultaneously determined in 50 premenopausal patients submitted to bilateral ovariectomy for advanced carcinoma of the breast. When both the hormonal parameters were positive (ER+ A+), the response to castration was favorable in 87.5% of the cases, with a survival rate of 39% at 5 years. No patient responded to the therapy when both the parameters were negative (ER− A−); none of them was alive at 5 years. An intermediate response (more than 50%) and survival rate at 5 years (more than 20%) was obtained in the group of patients with at least one of the two parameters positive (ER+ A−, or ER− A+). These responses were independent of the topography of neoplastic localizations and the length of the disease-free interval.
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  • 28
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    Breast cancer research and treatment 9 (1987), S. 213-217 
    ISSN: 1573-7217
    Keywords: meningeal ; breast cancer ; metastasis ; site
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twenty-two patients with meningeal carcinoma due to breast cancer were restrospectively evaluated to determine what prognostic factors affected survival. Five patients survived for more than one year. The therapy in these long-term survivors was similar to that of those suffering early death. Patients with primarily brain symptoms survived a median of 21 days vs. 150 days in those with primarily spinal cord symptoms (p = 0.026). The site of involvement may be an important stratification parameter for future prospective trials.
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  • 29
    ISSN: 1573-7217
    Keywords: age ; breast cancer ; disease-free interval ; photoperiod ; receptor status ; season of recurrence ; season of detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The season of recurrence of tumour was investigated by follow-up of 1324 patients with breast cancer and compared with the season of initial tumour detection. Unlike primary tumours, where an increased incidence of detection has previously been observed in late spring and early summer, there was no significant seasonal variation in the time of recurrence. However, women with oestrogen receptor positive or progesterone receptor negative primary tumours recurred significantly more frequently in the same season that their primary cancer was initially detected. Overall there was an increased frequency of recurrence one year from diagnosis. Women 〈age 50 who initially found their tumour in winter or autumn had a significantly shorter disease-free interval before recurrence than those first detecting their tumour in summer or spring. This relationship was independent of nodal status and tumour size. Tumours initially detected in winter or autumn thus appeared to follow a more aggressive growth profile. This study indicates that the season of first detection of a breast cancer relates significantly to aspects of the future biologic behaviour of the tumour.
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  • 30
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    Breast cancer research and treatment 9 (1987), S. 219-225 
    ISSN: 1573-7217
    Keywords: breast cancer ; mammography ; screening ; interval cancer ; prognosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the interval between screening examinations, some cases of breast cancer are invariably detected clinically in patients whose mammogram was considered to be normal at the earlier screening. During the first interval in the Stockholm study, 60 interval cancers were detected, giving a rate of 1.8 cases/1000 examinations/24 months. About half of these interval cases (31/60) were true interval tumours in that no sign of them could be found on the first mammogram; the other half, non-true, were possible to trace on the first mammogram. It is mainly women under 50 who feature in the interval group, above all in the sub-group of true interval cancers (p〈0.05). The incidence of interval cancer rises, as expected, with the length of the interval (Fig. 1). In the final six months of the 2-year interval the incidence of interval cancers had risen to 88 per cent of the cancers detected in the control group in the same period of time. The cumulative incidence of interval cancers supports the hypothesis that the distribution of sojourn time in the interval 0–2 years is approximately rectangular. This means that shortening the interval by one-half would halve the number of interval cases. If mammography becomes a wide spread screening method for early detection of breast cancer, the number of non-true interval cancers could be a feed back on the effectiveness of the screening. An analysis of the malignancy of the true interval cancers, based on tumour size, axillary status, tumour stage, and estrogen receptor content, shows that these are the more malignant tumours with an unfavourable prognosis, while the control group is intermediate in this respect and the tumours detected at screening have the most favourable prognosis.
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  • 31
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    Breast cancer research and treatment 10 (1987), S. 229-242 
    ISSN: 1573-7217
    Keywords: antiestrogens ; athymic nude mice ; breast cancer ; endocrine therapy ; estrogens ; tumor kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Although there have been extensive studies of rodent breast tumor models, and of human breast cancer cell lines in culture, there is still need for a human tumor model which can be manipulated experimentally but also provides a valid expression of the tumor cells in a host environment. Athymic nude mice bearing transplanted human breast tumors have been proposed as such a model. This review therefore discusses the use of the athymic nude mouse model of the study of human breast cancer biology, and focuses on four subjects: 1. biological characteristics of heterotransplanted breast tumors; 2. endocrinology and pharmacology of hormonal agents in the nude mouse; 3. endocrine sensitivity of heterotransplanted tumors; and 4. applicability and limitations of this model for the study of human breast cancer.
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  • 32
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    Breast cancer research and treatment 10 (1987), S. 273-278 
    ISSN: 1573-7217
    Keywords: breast cancer ; estrogen receptors ; progesterone receptors ; menstrual cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study was undertaken to determine if hormone receptor activity in breast cancers changes during different phases of the menstrual cycle. Estrogen (ER) and progesterone (PgR) receptors in seventy-eight primary breast carcinomas from premenopausal women were compared with the phase of the menstrual cycle at the time of biopsy. The frequency of ER positivity did not change, but PgR positivity became significantly higher after the early follicular phase. An increase in mean ER and PgR concentration was found (p〈.05) in the late luteal phase. The results indicate that tumor ER and PgR values change during the menstrual cycle, probably in response to endogenous hormonal fluctuations, and this may account for some vicissitudes in establishing hormone dependence.
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  • 33
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    International Journal of Quantum Chemistry 31 (1987), S. 1-1 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 34
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    International Journal of Quantum Chemistry 31 (1987), S. 33-44 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theory of MCSCF and CI energy derivatives with respect to geometrical variations is briefly reviewed with special attention given to the MCSCF and MRCI energy gradients. A computational procedure is proposed for MRCI energy gradients that does not require the solution to any “coupled-perturbed MCSCF” equations, it does not require any expensive direct-CI matrix-vector products involving derivative integrals, and it does not require any derivative integrals to be transformed from the AO basis to the MO basis. An additional feature is that it does not require any changes to existing MCSCF gradient evaluation programs in order to compute MRCI gradients. The only difference in the two cases is the exact nature of the data passed to the gradient evaluation program from the previous steps in the computational procedure. The additional effort required to compute the entire MRCI energy gradient vector is approximately that required for one additional iteration of the MRCI diagonalization procedure and for one additional MCSCF iteration. For large scale MRCI wave functions, the MRCI energy gradient evaluation should only require about 10% of the effort of computing the wave function itself. This computational procedure removes a major computational botleneck of potential energy surface evaluation.
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  • 35
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    International Journal of Quantum Chemistry 31 (1987), S. 65-71 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preliminary results are presented for transition probabilities in the H + H2 system derived from an adiabatic representation in terms of surface functions on hyperspheres. Special attention is given to the resonance structure for transition probabilities in the first vibrational level.
    Additional Material: 3 Ill.
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  • 36
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    International Journal of Quantum Chemistry 31 (1987), S. 99-112 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Low-lying excitation energies from the ground state of Be were calculated using a basis set of 61 Cartesian Gaussian functions. Three approximations were employed: the time-dependent Hartree-Fock (TDHF), second-order equations-of-motion (EOM), and multiconfigurational time-dependent Hartree-Fock (MCTDHF). The TDHF excitation energies are 0.5-1.1 eV lower than experiment, and the EOM values are 0.3-1.2 eV lower than experiment, whereas the MCTDHF excitation energies deviate on the absolute average from experiment by only 0.03 eV. We found that in an MCTDHF calculation, any proper MCSCF stationary point is a good reference (i.e., initial) state, not just the ground state. Experimental values for oscillator strength are accurately known only for the 2s2X1S → 2s2p1P0 transition. The TDHF value and the MCTDHF value agree with experiment, but the EOM value does not. The agreement of the TDHF value with experiment seems to be coincidental, because for higher lying transitions the TDHF values differ by approximately a factor of two or more from the more accurate MCTDHF. Frequency independent polarizabilities, α(0), were also calculated with the TDHF, HRPA, and MCTDHF and frequency dependent polarizabilities, β(ω), were calculated with the MCTDHF. No experimental data for Be polarizabilities exist, but we expect the MCTDHF values to be among the most accurate calculations available.
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  • 37
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    International Journal of Quantum Chemistry 31 (1987), S. 941-950 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A version of the CNDO/1 method has been outlined that includes dominant relativistic effects. The method utilizes a nonempirical parametrization based on atomic Dirac-Fock calculations. The goal of this QR-CNDO/1 method lies in its applicability to molecules consisting of arbitrary atoms (z = 1-118). Applications to molecular geometries and ionization potentials for 50 molecules are presented.
    Additional Material: 2 Ill.
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  • 38
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    International Journal of Quantum Chemistry 32 (1987) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 39
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    International Journal of Quantum Chemistry 32 (1987), S. 13-18 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: According to the formulas obtained in the preceding paper, it may be used for all types of the hybridization with any set of azimuthal quantum numbers l, l = 0 through l = 5, and a complete theoretical data of bond angles and bond strengths are shown in this paper.
    Additional Material: 2 Tab.
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  • 40
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    International Journal of Quantum Chemistry 32 (1987), S. 71-86 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the unitary-group formulation of quantum chemistry, the spin-projected, configuration-state spaces of quantum chemistry are realized by the irreducible representation spaces (IRS) of the freeon unitary group U(n), where n is the number of freeon orbitals. The Pauli-allowed IRS are labeled by the partitions [λ] = [2(N/2)-s, 12S], where N and S are the particle number and the spin, respectively. The generator-state approach (GSA) to the unitary-group formulation consists of (1) the construction of the overcomplete, nonorthonormal generator basis for each IRS; (2) the Lie-algebraic computation of matrix elements over generator states; (3) the Moshinsky-Nagel construction of the complete, orthonormal Gel'fand basis in terms of the generator basis; and (4) the computation of matrix elements over Gel'fand states in terms of matrix elements over generator states.
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  • 41
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    International Journal of Quantum Chemistry 32 (1987) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 42
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    International Journal of Quantum Chemistry 32 (1987), S. 181-191 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It has been shown that an easier procedure to the study of molecular electrostatic potentials than the prevalent monopole isopotential approach is to use a dipole as the mapping device: allow the dipole to move on a geometrical surface enclosing the molecule such that the distance between the surface and the nearest atoms of the molecule (closest distance of approach) is fixed, say at 2 Å, calculate the electrostatic interaction energy between the molecule and the dipole at different points of the surface, and let the dipole orient itself along the minimum energy direction and treat these minimum energies as the desired electrostatic potentials. Thus the favorable binding sites of a given molecule for other species along with their relative orientations can be obtained. This procedure has been applied to the nucleic acid bases using the necessary input data from two independent sources. Thus success of the procedure in predicting important features of molecular electrostatic potentials has been demonstrated.
    Additional Material: 4 Ill.
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  • 43
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A systematic examination of the components of the interaction energy, obtained with the Kitaura and Morokuma method, for nine H-bonded dimers without and with counterpoise corrections (CP) is presented. The nine dimers Hn A … HBHm correspond to all the possible combinations of HF, H2O, and NH3 as electron donors and electron acceptors. The interaction energy and the corresponding components have been computed over a sizable interval of intermolecular distances with five basis sets (STO-3G, MINI-1, 3-21G, 4-31G, 6-31G**) selected among those most extensively used to study interactions in larger systems. The CP corrections to the ΔE components have been obtained with a method, implemented in our group, which permits assignment to the pertinent components of ΔE of a physically reasonable portion of the CP correction even though different CP corrections are adopted. We examine here three versions of the CP correction, namely, the full CP correction (i.e., the original version of Boys and Bernardi) and CP corrections limited to the virtual space of the partner or to the electron donor only. The resulting data are employed to assess the basis set dependence of several models of hydrogen bonding (the electrostatic model, the semiclassical model, etc.) both with and without CP corrections.
    Additional Material: 9 Ill.
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  • 44
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A detailed analysis of the ΔE(R) curves for nine hydrogen bonded dimers involving HF, H2O, and NH3 as partners, computed with five basis sets (STO-3G, MINI-1, 3-21G, 4-31G, and 6-31G**) and subjected to counterpoise (CP) corrections with three different methods is reported. Using several criteria and tests, the positive effect of full CP corrections for the description obtained with all the basis sets (with the exception of the STO-3G one) is pointed out. The CP correction at the 6-31G** levels is still sizable and improves the results with respect to the estimated Hartree-Fock limits of ΔE(Req) and Req. The results obtained with the application of the full CP correction to the MINI-I energies are of relatively good quality. The STO-3G energies at the SCF level are, on the contrary, overcorrected by the full CP correction and slightly improved by “limited” CP corrections: this basis set, however, is not recommended for calculations of geometries and stabilization energies of H-bonded dimers of this size.
    Additional Material: 7 Ill.
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  • 45
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    International Journal of Quantum Chemistry 32 (1987), S. 295-312 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An accurate analytical electron density for the beryllium atom is obtained by using a fast and systematic method recently developed and tested for the neon atom. Asymptotic conditions both at the nucleus and at large distances are obeyed. A point-by-point comparison between our density and the one obtained from an almost “exact” configuration interaction wave function shows that differences are less than 0.5% for r between 0 and 5 bohrs and less than 1 % up to 9 bohrs. The accuracy of the density is also assessed by comparing results of density moments and x-ray scattering factors.
    Additional Material: 2 Ill.
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  • 46
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    International Journal of Quantum Chemistry 32 (1987), S. 361-375 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We discuss a procedure for calculating numerical Hartree-Fock orbitals that can be applied to polyatomic systems. This approach is formulated in momentum space to avoid Coulomb singularities and uses fast Fourier transforms to solve integral convolutions. Results for a number of simple systems are presented.
    Additional Material: 5 Tab.
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  • 47
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    International Journal of Quantum Chemistry 31 (1987), S. 405-415 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Binding of Zn2+ to imidazole (Im) and methyl imidazole (MeIm) is studied by ab initio methods as a model for the effect of cation binding on tautomeric energies. Gradient energy optimized conformations were obtained for all neutral and ionic structures, including the deprotonated molecules and the ylides. The N3—H tautomer of MeIm is calculated to be more stable than N1—H by about 1 kcal/mole. However, binding of a Zn2+ cation to the available nitrogen site is found to reverse the order of binding, leaving N1—H more stable by 1 kcal/mole. Binding of Zn2+ produces a significant perturbation in the electronic structure, a smaller shift in the equilibrium conformation of the imidazole ring, and only a small absolute shift in the relative tautomer energies. Methyl substitution at C5 has a small effect on both conformation and energetics.A high-energy ylide tautomer is produced by moving the proton bound to C2 to the N1 atom. The binding of Zn2+ to the C2 site is substantially stronger than to the N1 site, yielding nearly isoenergetic ZnIm2+ conformations for binding to either N or C atoms. For the deprotonated salts the lowest energy conformation has the C2—N3 bond bridged by Zn2+.
    Additional Material: 7 Tab.
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  • 48
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    International Journal of Quantum Chemistry 31 (1987), S. 425-427 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is made clear that two different statements in the literature concerning energy derivatives are completely compatible by deriving them as two different interpretations of the same equation. Some other aspects of these results are also discussed.
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  • 49
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    International Journal of Quantum Chemistry 31 (1987), S. 435-443 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Accurate methods for computing energies and electronic properties of atoms and molecules have been derived from direct treatment of localized pairs of electrons. The conceptual development and implementation of such methods is reviewed.
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  • 50
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    International Journal of Quantum Chemistry 32 (1987), S. 473-489 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rigorous derivation of the energy density functional is proposed within the framework of the spinfree, or spin-restricted formulation of the energy density functional theory. It is shown particularly that the kinetic energy density functional is given by a sum of the Weizsacker term and the so-called “modified” Thomas-Fermi one. The variational principle is formulated for the energy density functional theory in terms of the Euler-Lagrange equation, and the virial theorem is proposed.
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  • 51
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    International Journal of Quantum Chemistry 32 (1987), S. 591-594 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The time-dependent Schrouml;dinger equation for the oscillator H = α(t)p2 + β(t)x2 + γ(t)x is exactly solved. The time evolution operator is easily obtained by means of an operator algebra and the quantum-mechanical equations of motion. The problem is reduced to solving the classical equations of motion. The method is shown to apply to multidimensional oscillators.
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  • 52
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    International Journal of Quantum Chemistry 31 (1987), S. 445-453 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A modified Bohr orbit procedure is used to calculate the energies for the 1S ground state and the 2P, 3D, and 4F excited states of the helium atom. The energies are calculated from \documentclass{article}\pagestyle{empty}\begin{document}$ {{\int\limits_0^\pi {E\left(\Phi \right)P\left(\Phi \right)d\Phi } } \mathord{\left/ {\vphantom {{\int\limits_0^\pi {E\left(\Phi \right)P\left(\Phi \right)d\Phi }} {\int\limits_0^\pi {P\left(\Phi \right)d\Phi } }}} \right. \kern-\nulldelimiterspace} {\int\limits_0^\pi {P\left(\Phi \right)d\Phi } }} $\end{document}, in which E(φ) is the Bohr orbit energy for angle φ between the position vectors \documentclass{article}\pagestyle{empty}\begin{document}$ \vec r_1 $\end{document} r1 and \documentclass{article}\pagestyle{empty}\begin{document}$ \vec r_2 $\end{document} r2, and P(φ) is a probability function for this angle. Numerical procedures are used to evaluate the integrals. Energies that range between -2.9082 and -2.9054 au are calculated for the 1S state (cf. -2.9037 au, exact). The Bohr energies for the excited states are -2.1318, -2.1240, -2.0562, -2.0555, -2.0314, and -2.0312 au, which are generally close to the exact energies of -2.1332, -2.1239, -2.0557, -2.0557, -2.0313, and -2.0313 au for the 23P, 21P, 33D, 31D, 43F and 41F states. Some relationships that exist between the Bohr theory and the Schrödinger local energies are discussed. Approximate Bohr orbit estimates for the energies of the 2P states of He, Li+,…,Ne8+ are reported.The invariance of the two-electron Bohr hamiltonian with respect to the interchange of the electron coordinates leads to two classical probability functions when the orbit quantum numbers for the two electrons differ.
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  • 53
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    International Journal of Quantum Chemistry 31 (1987), S. 463-470 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Valence-bond calculations are reported for the isoelectronic series of molecules and ions: N2, CO, BF, NO+ and CN-. The most important structures are N≡N, C=O, Bπ—F, N+=O and C=N. Hybridization of the 2s and 2p orbitals is important. Only two or three structures are required to obtain an energy lower than that obtained with the molecular orbital approximation. Structures in which the electronegative element loses a σ-orbital or gains a π-orbital are favored. π-bonds tend to be favored over σ-bonds. The bond in NO+ resembles that in CO, whereas that in CN- resembles the bonding in N2.
    Additional Material: 5 Tab.
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  • 54
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    International Journal of Quantum Chemistry 31 (1987), S. 471-487 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio SCF, CI, CEPA, and MCSCF techniques are compared and contrasted in a theoretical study of the 1s core ionized Li2 molecule from the point of view of core hole localization. In agreement with earlier studies of symmetric core ionized molecules, SCF theory is found to give a physically reasonable description of core ionization only when symmetry breaking is allowed. This results in a dramatic lowering of the energy of the core ionized state and hence of the ionization potential. By extension, CI wave functions that are developed in terms of a broken symmetry SCF reference plus its single and double excitations are found to perform significantly better than those constructed from symmetry adapted SCF orbitals. Alternatively, if the full point group symmetry is to be retained, a multiconfigurational treatment is called for and, in agreement with the conclusions of an analogous study on O2 [H. Ågren, P.S. Bagus, and B.O. Roos, Chem. Phys. Letters 82, 505(1981)], it is found that a modestly sized MCSCF wave function is capable of accounting for the energetic effects of symmetry breaking. Potential energy curves for Li2 and several states of core ionized Li2 have been calculated, allowing predictions of the adiabatic ionization potential and vibrational, satellite, and Auger structures in the photoelectron spectrum of Li2 to be made.
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  • 55
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    International Journal of Quantum Chemistry 31 (1987), S. 489-505 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A practical algorithm is described for generating a set of symmetry- and spin-adapted antisymmetrized products of molecular orbitals (SAAPs) which form an orthogonal basis for a full active configuration space. The spin-adaptation is completely general. The space-symmetry adaptation is accomplished for the groups C∞v and D∞v.
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  • 56
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    International Journal of Quantum Chemistry 32 (1987), S. 685-697 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A complete description of the rotational isomerism of monothioformic acid is presented. Ab initio results concerning the barrier heights and the energy difference between the stable isomers are in good agreement with the experimental data. A reduced potential function deduced from our calculations has been used to characterize the kinetics and thermodynamics of the rotational isomerization. The reported ab initio values of equilibrium constants are in good agreement with the experimental ones. From the analysis of the available experimental data, we have found that the free energy and enthalpy behavior are quite similar and that no noticeable entropy contributions are involved in the internal rotation, in agreement with previous studies on unimolecular isomerization processes.
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  • 57
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    International Journal of Quantum Chemistry 32 (1987), S. 723-723 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 58
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    International Journal of Quantum Chemistry 32 (1987), S. 1-1 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 59
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    International Journal of Quantum Chemistry 32 (1987), S. 85-103 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The equilibrium geometry, stabilization energy, and electric polarizability of formic acid, formamide, and the three possible cyclic hydrogen-bonded pairs are obtained by ab initio calculations using the STO-3G, 4-31G, and 6-31G** bases. These three properties are found to be very much dependent on the basis set extension. The polarizability of the dimers is found to be basically additive in contribution from the monomeric moieties.
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  • 60
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    International Journal of Quantum Chemistry 32 (1987), S. 133-147 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the course of conformational motions of molecules the changes in shapes of electronic charge distributions follow that of the nuclear framework. However, this coupling between the changes in the nuclear geometry and electron density may depend on the actual nuclear displacement; the coupling may be weak or strong for a given conformational motion. It is of some interest to analyze how faithfully the charge density variations follow the nuclear displacements in a family of conformational rearrangements. In certain cases small conformational changes may induce large changes in the shape of charge density distributions, while in other cases large and qualitatively important conformational changes may involve qualitatively inessential distortions in the shape of electron distributions. In this article we describe a new classification of conformations based on those domains of nuclear configuration space within which the „shape groups“ (symmetry independent homology groups) of the electric charge density remain invariant. Such an analysis might be valuable when seeking correlations between molecular structure and certain biological or biochemical activities.
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  • 61
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    International Journal of Quantum Chemistry 32 (1987), S. 211-219 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Practical aspects of the calculation of the proton transfer process in a model of the active site of the thiol protease papain are explored with basis sets of different sizes. Results from ab initio calculations with the STO-3G, 4-31G, 6-31G, 6-31G* basis set, and a 6-31G basis set augmented with polarization functions on the sulfur atom are compared for their performance in describing the proton transfer energy. The nature of the convergence of the calculated properties of the potential curve for proton transfer with the increase in basis set indicates the need for a split-valence basis set and for polarization functions on the sulfur in order to achieve an appropriate description of this system. Correlation corrections to the calculated energies are shown to contribute significantly to the characteristics of the proton transfer energy curve.
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  • 62
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    International Journal of Quantum Chemistry 32 (1987), S. 281-288 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The scope of multistep modeling (MSM) is expanded by adding a least-squares minimization step in the procedure to fit backbone reconstruction consistent with a set of C-alpha coordinates. The analytical solution of Phi and Psi angles, that fits a C-alpha x-ray coordinate [1] is used for tyr-tRNA synthetase. Phi and Psi angles for the region where the above mentioned method fails, are obtained by minimizing the difference in C-alpha distances between the computed model and the crystal structure in a least-squares sense. We present a stepwise application of this part of MSM to the determination of the complete backbone geometry of the 321 N terminal residues of tyrosine tRNA synthetase to a root mean square deviation of 0.47 Å from the crystallographic C-alpha coordinates.
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  • 63
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    International Journal of Quantum Chemistry 32 (1987), S. 325-330 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have examined an application of the weighted identification number in the QSAR study of the toxicity of aliphatic ethers on mice. The results obtained are superior to those achieved by the connectivity index.
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  • 64
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    International Journal of Quantum Chemistry 32 (1987) 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 65
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    International Journal of Quantum Chemistry 32 (1987), S. 13-14 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 66
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    International Journal of Quantum Chemistry 32 (1987), S. 89-97 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio self-consistent-field electronic state calculations have been carried out for an interstitial-iron-substitutional-boron impurity pair complex in silicon. The calculations do not provide support for the currently accepted microscopic ionic model for the pair. Rather, we have shown that the covalent effects play a basic role in determining the physical properties of the complex.
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  • 67
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    International Journal of Quantum Chemistry 32 (1987), S. 115-129 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By analyzing the convergence properties of the lattice sums in the exchange part of the restricted Hartree-Fock orbital energy, we isolate the source of the nonanalytic behavior of a partially occupied band at the Fermi energy. This analysis shows how an extended system behaves qualitatively differently from a finite system but also provides a possibility of following the development of nonanalyticity as the size of the system grows.
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  • 68
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    International Journal of Quantum Chemistry 32 (1987), S. 163-170 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aromatic (A) and quinoid (Q) forms of polythiophene (PT) have entirely different energy gaps: ∼0.5 eV for the quinoid form and ∼2 eV for the aromatic form, respectively. The energy gaps and stability of derivatives of PT are studied by total MNDO geometry optimization using energy band theory for the total energy calculations followed by a Hückel energy band calculations to approximate the energy band structure. Addition of fused rings to PT reverses the order of stability of the aromatic and quinoid isomers and the ordering in the size of the energy gaps. Small energy gap polymers are suggested on the basis of the calculations.
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  • 69
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    International Journal of Quantum Chemistry 32 (1987), S. 191-198 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemical reactions and conformational changes of N-atom systems can be described as displacements in a (3N-6)-dimensional metric configuration space M provided with a global metric. Although space M has a metric, it is not in general a vector space; it is a topological space. In contrast to the commonly used internal configuration spaces based on bond length/bond angle internal coordinates, and having no global metrics, within space M each internal configuration of the nuclei of the molecule corresponds to one and only one point of the space. This property of M is advantageous when analyzing chemical reactions. The global metric of M ensures that differences between any two internal configurations can be interpreted as a distance in this space that allows one to provide M with coordinate systems by turning M into a manifold with boundary. Certain formal reaction paths show some counterintuitive behavior within this space: they may undergo a formal reflection at some points of M. A condition, the tangent criterion, is used for the diagnosis of such reaction paths and for the determination of special nuclear configurations where such reflections occur.
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  • 70
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    International Journal of Quantum Chemistry 31 (1987), S. 649-662 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Energies and geometries for a number of small hydrogen bonded dimers have been calculated by semiempirical method based on a perturbation approach. Results have been compared with experimental and the best theoretical data. A quite good description of equilibrium configurations has been obtained in every case when local multipoles from sufficiently accurate wave functions have been used. Hydrogen bond lengths have not been predicted with sufficient precision. Results indicate, however, that it should be possible to achieve improvement in the framework of the applied calculation scheme by modification of the parameter values.
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  • 71
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    International Journal of Quantum Chemistry 32 (1987), S. 283-295 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We examine the photoaddition of hydroxylazoaromatic compounds and related thione analogs with olefins. By examining the properties of the lowest lying singlet and triplet states, we conclude that the product distribution is best described by the unpaired spin density of the triplet state. This suggests that absorption of light by the aromatic is followed by conversion into the triplet, and this triplet is the active precursor. Since unrestricted molecular orbital calculations are easily performed on the lowest triplet of these aromatics, prediction of possible products is straightforward.
    Additional Material: 7 Ill.
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  • 72
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    International Journal of Quantum Chemistry 32 (1987), S. 267-282 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrogen addition to acetylene has been studied by molecular orbital methods with the unrestricted Hartree-Fock (HF)approach and with Møller-Plesset (MP) perturbation theory up to fourth order using the 6-31G*, 6-31G**, and 6-311G** basis sets. For each basis set a number of points along an approximate reaction path were calculated by fixing the attacking H—C distance and optimizing all of the remaining parameters. At these geometries, single point MP4 calculations with and without spin projection were carried out, yielding the position, height, and shape of the addition barrier at the various levels of calculation with each of the three basis sets. The results of this approach were confirmed by a grid search of the region near the transition state using the 6-31G* basis set. The unprojected MP2, MP3, and MP4 barriers are too narrow and are 10-20 kcal/mol too high. With spin projection, the barriers are much lower and broader. At the PMP4SDTQ/6-311G** level, with zero point energy calculated at UHF/6-31G*, the vibrationally adiabatic barrier at 0 K is 4.0 kcal/mol, and the attacking H—C distance is 2.0 Å.
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  • 73
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    International Journal of Quantum Chemistry 32 (1987), S. 313-319 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We explore the implications of static disorder on electron transfer (ET) in a microscopically inhomogeneous polar medium, where the environment of each solute is characterized by a single dielectric relaxation time, τ, with the distribution function of τ being related to the complex dielectric susceptibility. For the interesting situation of solvent-controlled ET, the decay of the population probability is nonexponential, which can be expressed in terms of a cumulant expansion. The microscopic decay function can be related to the macroscopic step-response function of the dielectric medium.
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  • 74
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    International Journal of Quantum Chemistry 32 (1987), S. 355-362 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A self-consistent model capable of describing the interaction of a metal electrode/liquid electrolyte interface is presented. As in a real system, a capacity maximum shifted towards positive charges is obtained from the model. The metal is represented by the planar uniform background model (jellium). The solvent is described by a polar liquid whose response to charge is accounted for in terms of the local approximation. The interaction between the metal and ions is modelled by a charged plane placed near the metal surface. Charge neutrality of the whole system is preserved. The present model is a good approximation for highly concentrated solutions.
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  • 75
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    International Journal of Quantum Chemistry 31 (1987), S. 733-737 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper we outline briefly how microlocal analysis can be applied to give a general approach to the mathematical theory of resonances in the semiclassical limit. We also describe recent results about the asymptotic behavior of resonances generated by closed trajectories and stationary points in the classical flow.
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  • 76
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    International Journal of Quantum Chemistry 31 (1987), S. 739-746 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper we make explicit constructions of a family Aθ of intertwining operators between the Schrödinger operator Hv = -Δ + v(x) and H0 = -Δ. The wave operators and the scattering matrix are expressed in terms of the Aθ, and some methods of inverse scattering are described.
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  • 77
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    International Journal of Quantum Chemistry 31 (1987), S. 707-731 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Examples from music and nuclear, as well as atomic and molecular, physics are given to introduce and illustrate the resonance concept. Some fundamental concepts of scattering theory such as the differential and the total cross section are presented. The concept of the collision complex is illustrated with a light particle scattering reaction in nuclear physics. The concept of channels is introduced, and this formalism (which is so far empirical in nature) is dressed in the language of quantum mechanics. Finally I show that our descriptions of phenomena in nuclear physics can also be used in atomic and molecular physics.
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analytic energy gradient method that we have recently implemented for CCSD wave functions is applied to fully optimize the pyramidal C3v and planar D3h structures of ammonia. Using a double-zeta plus polarization basis set, results for harmonic vibrational frequencies, infrared intensities, and dipole moments have been obtained. Comparison with different levels of truncated configuration interaction suggests that CCSD values are of better than CISD quality and generally closer to CISDTQ results.
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    International Journal of Quantum Chemistry 32 (1987), S. 539-545 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Effective core potentials are utilized in conjunction with polarization propagator calculations of excited state properties. The propagator method employed is based on an antisymmetrized geminal power wave function as the reference state. Calculations are presented on the low-lying excited states of HF and NaH. All-electron and valence-electron results are compared for HF. The choice of basis set is found to be very important for obtaining good results.
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  • 80
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    International Journal of Quantum Chemistry 32 (1987), S. 569-572 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nonadiabatic energy correction term of the hydrogen molecule at large separation is discussed to determine whether or not the nuclear motion induces the inter-atomic interaction potential. Nonadiabatic vibrational motion of nuclei induces the internal charge polarization of atoms to give the novel correction term to the London R-6 force. The correction term is (4/M) (1/R3), which is important at large R despite the overwhelming magnitude of nuclear mass.
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    International Journal of Quantum Chemistry 31 (1987), S. 755-794 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As an extension of the recent atomic work of Krylstedt et al. [1, 2], we propose the synthesis of the static exchange plus polarization model within the multiple scattering Xα formalism and the exterior complex rotation method for the study of shape resonances occurring in molecular collisional systems. The bound state multiple scattering Xα method is reviewed with special attention to the form of the various wave functions for the different molecular regions. In connection with the inclusion of continuum electron exchange into the scattering model, we analyze a possible solution to the problem of asymptotical behavior caused by the local density-based free electron gas approximation used in this case. We also propose a method to fix the cutoff parameter, inherent in the polarization potential, for symmetry-related molecular participants in the scattering process, thereby obtaining a possible predictive power for the one-parameter scattering model.Titchmarsh-Weyl's theory is used to formally connect the above formulation to scattering theory. The theoretical difficulties in obtaining a unique meromorphic continuation of the S matrix are investigated in connection with the requirements on the actual potential to be exterior dilation analytic. Furthermore, the occurrence of asymptotic quantum numbers is noted and discussed in conjunction with muffin tin-like approximations and related exterior complex rotated schemes.It is found that the electron exchange part of the nonstatic one-body potential exhibits a functional form that is not exterior dilation analytic, albeit the general electron and nuclear many-body problem involving Coulomb forces are dilation analytic. Although the immediate consequences indicate a rotation angle (θ) dependence on the S matrix continuation, a uniquely defined assignment of the cutoff parameter r0 = r0(θ) makes the present nonstatic model “exterior dilation analytic” in the sense that it mimics the dilation analytic structure of the full many-body problem at the same time obeying “asymptotic” spherical symmetry via the associated constant of evolution. However, in the static exchange approximation the above difficulties are shown to be circumvented via a certain reformulation, leading to a regular analytic asymptotic form for the interaction potential.
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    International Journal of Quantum Chemistry 31 (1987) 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 83
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    International Journal of Quantum Chemistry 31 (1987), S. 841-845 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the present article we show how the bound states of the Coulomb potential may be associated with resonances that occur when this potential is perturbed by a barrier potential. The main idea is to trace the bound states on successive switching on of the barrier perturbation. It is found that those bound states that are localized inside the barrier are highly sensitive to variation with respect to the barrier height, whereas those that are localized outside are less sensitive. However, there are certain intervals for the barrier height when the role of being “a state localized inside the barrier” is shifted from one bound state to another. The result can be pictured as a “relay race,” where the “deliveries of the baton” are carried out over corresponding avoided crossings. The baton is ultimately handed over to a shape-type resonance state.
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    International Journal of Quantum Chemistry 31 (1987), S. 847-853 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl substitutents located peri to bay-region benzo rings of polycyclic aromatic hydrocarbons generally reduce or eliminate carcinogenic activity, most likely because such substituents force the hydroxyl groups of dihydrodiol intermediates to adopt preferentially pseudodiaxial, rather than pseudodiequatorial, conformations. Empirical force field calculations have been employed to examine the influences of peri and other positional substituents on hydroxyl conformation, taking naphthalene, anthracene, and phenanthrene as model compounds. For the unsubstituted naphthalene and anthracene dihydrodiols, the pseudodiequatorial conformation is preferred. This preference is reduced by adjacent methyl substitution and reversed by peri methyl substitution. Because of steric crowding the phenanthrene bay-region dihydrodiol preferentially adopts a pseudodiaxial conformation. The results are discussed in relation to recent experimental evidence.
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    International Journal of Quantum Chemistry 31 (1987), S. 855-869 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic absorption spectra of some phenylethylamine drugs, namely, d-pseudoepherine, l-pseudoephedrine, l-ephedrine, dl-ephedrine dl-norephedrine, phenylethylamine, methoxyphenamine, and l-noradrenaline were investigated in polar and nonpolar solvents. The observed transitions were interpreted, and the role of σ-π interaction was explored. Molecular orbital calculations were performed on representatives of the above group of compounds, namely, d-pseudoephedrine, l-ephedrine, and l-noradrenaline using the INDO procedures and adopting the best conformer of the molecule. The transition energy, band intensity, and dipole moments were calculated and corresponded satisfactorily with the experimental values.
    Additional Material: 5 Ill.
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  • 86
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    International Journal of Quantum Chemistry 31 (1987), S. 893-901 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analytic expressions of the integral prototypes involving both Slater and s-type Gaussian functions, explicity derived in Ref. 1, are generalized to the case of higher order modified Gaussian functions [2].
    Additional Material: 1 Tab.
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  • 87
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By expanding the wave function of a system of N particles in terms of products of functions of one and (N-1) particles, the one-particle, nonlocal operator F̂EKT (extended Koopmans' theorem) is determined. It is shown that although this operator is nonhermitian, its eigenvalues and eigenfunctions represent the ionization energies and occupied orbitals, respectively. The eigenfunctions of F̂EKT are the one-particle functions that enter into the expansion of the wave function of the system as partners of the (N-1)-particle wave functions. The eingenvalues are also one-particle energies that, multipled by the orbital occupancy probalities, enter the expression for the total N-particle energy of the system.
    Additional Material: 7 Tab.
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  • 88
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 927-939 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We apply completely transferable, strictly localized molecular orbitals for the calculation of molecular electrostatic fields. This approach, derived from our previous bond fragment method for the calculation of molecular electrostatic potentials, reduces computational efforts drastically. The fields around small molecules containing first- and second-row atoms are systematically overestimated as compared with ab initio calculations with a minimal STO-3G basis set. However, deviations can be corrected by a simple multiplicative factor, which means that the overall shape of the potential and field around the molecule is correctly reproduced. Our approximate field can be used to determine possible hydration sites around molecules as proposed earlier by Peinel and coworkers. Application of the method is illustrated on the formamide molecule.
    Additional Material: 5 Ill.
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  • 89
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    International Journal of Quantum Chemistry 32 (1987), S. 399-399 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 90
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    International Journal of Quantum Chemistry 32 (1987), S. 403-403 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 91
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    International Journal of Quantum Chemistry 32 (1987), S. 427-434 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The quality measure δ of Sordo and Pueyo is computed for 94 orbital basis sets for the atomic helium Hartree-Fock problem and compared with various information theoretic quality measures reported previously by us for this data base. δ is in error often enough that it is unlikely to be a useful general purpose measure.
    Additional Material: 2 Ill.
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  • 92
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    International Journal of Quantum Chemistry 32 (1987), S. 457-466 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Sturmian transformation is reviewed and some of its properties are discussed, in particular, its use in perturbative approaches, its connection with variational schemes, and its use for the study of resonances. One potential problem (Doolen) having no bound states is described exactly.
    Additional Material: 2 Ill.
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  • 93
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    International Journal of Quantum Chemistry 32 (1987), S. 27-35 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Basis set and correlation effects on computed hydrogen bond energies of the negative ion complexes AHn · AHn-1-1, for AHn = NH3, OH2, and FH, have been evaluated. The addition of diffuse functions on nonhydrogen atoms to valence double- and triple-split plus polarization basis sets [6-31G(d, p) and 6-311G(d, p)] significantly decreases binding energies by 9-19 kcal/mol, depending on the particular complex and the level of theory. Adding diffuse functions to hydrogens has a negligible effect, while replacing the single set of polarization functions on each atom by two sets alters energies by 1 kcal/mol or less. Electron correlation increases the hydrogen bond energies of these complexes and has a greater effect for basis sets without diffuse functions. Since the Hartee-Fock energies computed with these basis sets are already too large, correlation energy calculations should not be performed in these cases. For basis sets including diffuse functions, the correlation energy contribution to the binding energies of these complexes is significant, with the Møller-Plesset second-order term being the largest term and having a stabilizing effect of from 3-6 kcal/mol. The third and fourth order terms are smaller, and may be of opposite sign. As a result, the MP2 and MP4 energies differ by no more than 1 kcal/mol, with the MP2 stabilization energy being greater except for N2H5-1. The computed standard solvation enthalpy of OH-1 by H2O based on either MP4/6-311 + G(2d, 2p) or MP2/6-31 + G(d, p) electronic energies is -26.8 kcal/mol, in excellent agreement with a recent gas-phase experimental measurement.
    Additional Material: 1 Tab.
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  • 94
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    International Journal of Quantum Chemistry 32 (1987), S. 105-110 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new definition of molecular similarity in terms of electron density is proposed and a method for calculating similarity based on molecular electrostatic potential and molecular electric field introduced. It is applied to some simple isosteres.
    Additional Material: 3 Ill.
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  • 95
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    International Journal of Quantum Chemistry 32 (1987), S. 127-132 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Most of the important conformations of biomolecules possess only trivial symmetry. Consequently, symmetry groups have no roles in the characterization of the shapes of such conformations. However, an alternative group theoretical model, based on homology groups of algebraic topology, provides a detailed description of shapes for all conformations. These shape groups are useful for precise comparison of molecular shapes and are proposed as a computational tool for QSAR. A new computational method for the determination of various shape groups is described which is suitable for the simultaneous analysis of a pair or a family of molecular properties. In this note a general method is described and applied to the shape of electronic charge distribution along van der Waals surfaces.
    Additional Material: 1 Ill.
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  • 96
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    International Journal of Quantum Chemistry 32 (1987), S. 189-209 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies on the proton transfers in water clusters (H2O)n (n = 2, 3, 4, 5, 6), and in DNA base pairs, adenine-thymine base pair, and guanine-cytosine base pair, have been done by using the potential functions of polarization model for water and ab initio SCF method with STO-3G basis set for base pairs, respectively.
    Additional Material: 12 Ill.
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  • 97
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    International Journal of Quantum Chemistry 32 (1987), S. 261-280 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Briefly noting earlier studies on the polypentapeptide of elastin, (Val1-Pro2-Gly3-Val4-Gly5)n, and on elastin, it is emphasized that entropic elastomeric force can be exhibited by nonrandom, anisotropic polypeptide systems and therefore that entropic elastomeric force does not necessarily result from isotropic random chain networks as required by the classical theory of rubber elasticity, nor does it result from solvent entropy effects as deduced from the slow loss of elastomeric force on thermal denaturation. Instead entropic protein elasticity can be the result of internal chain dynamics, specifically of librational processes that become damped on chain extension. This new mechanism of entropic protein elasticity allows for an understanding not only of elastin but also of the passive tension of striated muscle, of the voltage-dependent interconversion between open and closed conductance states in the sodium channel of squid nerve, and of protein elastic forces producing strain in a substrate bond during enzyme catalysis. Because entropic elastomeric force develops as a result of an inverse temperature transition, it becomes possible to shift the temperature of the transition to higher or lower temperatures by decreasing or increasing, respectively, the hydrophobicity of the elastomeric polypeptide chain. In warm-blooded animals this allows for biochemical modulation of the relaxation or development of entropic elastomeric force by an enzymatically modulated decrease or increase of the hydrophobicity, as for example, by phosphorylation or dephosphorylation of the elastomeric polypeptide chain. This understanding provides a mechanism for modulating protein function, whether for example enzymatic or channel, a mechanism for the remarkable reversible structural processes that attend parturition, and a mechanism for the connective tissue anomalies of wound repair and enviromentally induced lung disease.
    Additional Material: 9 Ill.
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  • 98
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    International Journal of Quantum Chemistry 32 (1987), S. 297-315 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have recently discovered a new entirely unexpected, and highly selective protein - ligand interaction. This new kind of molecular interaction was recognized by chromatography of proteins on divinylsulfonated agarose gels which had been deactivated using mercaptoethanol. The essential structure of the interacting immobilized ligand is quite simple and nonionic. It can be generally represented by: \documentclass{article}\pagestyle{empty}\begin{document}$$\hbox{agarose-O-CH}_2 \hbox{CH}_2\hbox{-SO}_2\hbox{-CH}_2\hbox{-X-}$$\end{document} where X was first a thioether but can also be N, O(S 〉 N ≫ O) or possibly any atom with at least one lone electron pair. We have provisionally termed peptides and proteins interacting with this ligand „thiophilic,“ in recognition of their affinity for the definitive thioether sulfone constituents. The thiophilic adsorption process is promoted by water-structuring or „antichaotropic“ salts such as sulfates or phosphates and would appear to be entropically driven. The thermodynamics of such a process are discussed relative to protein recognition of the immobilized thioether-sulfone ligand. We do not yet know the precise mechanism for the interaction but we believe that salt allows the protein into close contact with the immobilized thioether-sulfone group where short-range forces are likely to be important. Evidence suggests that aromatic side chains on the protein-binding site may be involved and we therefore expect that some kind of electron-donor-acceptor or proton-acceptor mechanism is likely involved. Two important applications of thiophilic adsorption are the selective immobilization of functional antibodies as well as purification of immunoglobulins from serem, ascites fluid, and hybridoma cell culture media. Monoclonal antibodies can be purified in one step under extremely mild (structure-stabilizing) conditions. We therefore consider the further characterization of thiophilic adsorption of major significance in the fields of immunology and biotechnology and hope that this presentation will inspire attempts to explain the interaction in terms of quantum chemistry.
    Additional Material: 9 Ill.
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  • 99
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    International Journal of Quantum Chemistry 32 (1987), S. 347-349 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
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  • 100
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 15-29 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An attempt is made to analyze the present state of first-principles methods used in solid state theory to elucidate where these methods derive their strength and why they may be expected to gain even more predictive power in the near future. The latter will depend on the success of recently contemplated improvements. As regards the ground state properties of solids, there are two - in principle -  rigorous ways of treating the associated N-electron problem. One is based on the Hohenberg-KohnSham (HKS) theory, which maps the electronic pair correlation onto a strictly local, energy-independent potential that occurs in the associated one-particle equations. The alternative approach, which will not be discussed in this paper, is connected with determining quasi-particle amplitudes from the Dyson equation, where the information on the electronic pair correlation is absorbed into a nonlocal energy-dependent self-energy operator.Distinctly different from HKS theory, which only applies to ground states, the quasi-particle scheme lends itself to describe excitations (e.g., interband transitions) just as well. We shall furthermore discuss a generalization of the HKS theory that explains why naive extensions of this approach to excited states have been relatively successful in a variety of cases.
    Additional Material: 2 Ill.
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