bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dendrimers as scaffolds for multifunctional reversible addition–fragmentation chain transfer agents: Syntheses and polymerization
Authors: Hao Xiaojuan , Nilsson Camilla , Jesberger Martin , Stenzel Martina H. , Malmström Eva , Davis Thomas P. , Östmark Emma , Barner‐Kowollik Christopher 
Published: October 2004

AbstractThe synthesis and characterization of novel first‐ and second‐generation true dendritic reversible addition–fragmentation chain transfer (RAFT) agents carrying 6 or 12 pendant 3‐benzylsulfanylthiocarbonylsulfanylpropionic acid RAFT end groups with Z‐group architecture based on 1,1,1‐hydroxyphenyl ethane and trimethylolpropane cores are described in detail. The multifunctional dendritic RAFT agents have been used to prepare star polymers of poly(butyl acrylate) (PBA) and polystyrene (PS) of narrow polydispersities (1.4 < polydispersity index < 1.1 for PBA and 1.5 < polydispersity index < 1.3 for PS) via bulk free‐radical polymerization at 60 °C. The novel dendrimer‐based multifunctional RAFT agents effect an efficient living polymerization process, as evidenced by the linear evolution of the number‐average molecular weight (Mn) with the monomer–polymer conversion, yielding star polymers with molecular weights of up to Mn = 160,000 g mol−1 for PBA (based on a linear PBA calibration) and up to Mn = 70,000 g mol−1 for PS (based on a linear PS calibration). A structural change in the chemical nature of the dendritic core (i.e., 1,1,1‐hydroxyphenyl ethane vs trimethylolpropane) has no influence on the observed molecular weight distributions. The star‐shaped structure of the generated polymers has been confirmed through the cleavage of the pendant arms off the core of the star‐shaped polymeric materials. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5877–5890, 2004
Fracture mechanism of liquid‐crystalline epoxy resin systems with different phase structures
Authors: Harada Miyuki , Aoyama Kentaro , Ochi Mitsukazu 
Published: October 2004

AbstractA liquid‐crystalline epoxy resin was cured at two different temperatures. The phases of the cured systems clearly showed isotropic and nematic polydomain structures, which depended on the curing temperature. The fracture toughness of the systems was measured, and the fracture mechanism was investigated with polarized IR measurements. The nematic polydomain structure system showed considerably higher fracture toughness than the isotropic structure. Moreover, both systems exhibited a reorientation of the network chains near the fracture surface during the fracture process, and the region of the network reorientation in the nematic polydomain structure system was larger than that in the isotropic structure system. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4044–4052, 2004
Preparation of benzoylchitosans and their chiroptical properties in dilute solutions
Authors: Wu Yusong , Seo Toshihiro , Maeda Shiro , Sasaki Takashi , Irie Satoshi , Sakurai Kensuke 
Published: October 2004

AbstractTwo benzoyl substituted chitosan derivatives, 3,6‐O‐dibenzoylchitosan (DBC) and 2‐N‐3,6‐O‐tribenzoylchitosan (TBC), were prepared, and their optical activities in organic solvent were investigated by circular dichroism (CD). For TBC, two splitting bands (a negative one at 288 nm and a positive one at 274 nm) corresponding to the 1Lb transition of the benzoyl group were observed in chloroform and dichloromethane, while only a negative CD band was recorded in N, N‐dimethylformamide (DMF). These results indicated that the transition moments of benzoyl groups were orderly arranged along the helical polymer chain when TBC was dissolved in a solvent with low polarity, but the same ordered structure did not appear in a polar solvent of DMF. For DBC, only negative CD signals corresponding to the 1Lb transition of the benzoyl group were observed, regardless of the solvent property, which indicated that the chromophores were not arranged in an ordered fashion with appropriate geometry to interact with one another to induce bi‐signate CD signals. Adding methanol or DMF to the solution of TBC/chloroform resulted in a progressive decrease of the intensity of the positive split band at 274 nm. The intensity of the positive band was weakened upon heating a solution of TBC/chloroform from 20 to 60 °C. The results suggested that the ordered arrangement of the chromophores in the TBC system was dependent on solvent and sensitive to temperature. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4107–4115, 2004
Weakly bound triatomic 4He23He and 3He24He molecules
Authors: Gou Bingcong , Wang Fei 
Published: October 2004

AbstractThe bound rotational excited states of weakly bound 4He23He and 3He24He molecules have been searched for. Including pair interaction between helium atoms, we solved the Schrödinger equation for the triatomic systems with hyperspherical coordinates in the adiabatic approximation. The resulting potential curves are mostly repulsive for nonzero angular momenta. We conclude that no bound rotational excited states exist in both 4He23He and 3He24He molecules. The stability of the systems depends sensitively on the quantum symmetry and the masses of the particles. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Theoretical study of structure and stability of fullerene derivative: C50O
Authors: Xu Xiufang , Xing Yumei , Yang Xia , Wang Guichang , Cai Zunsheng , Shang Zhenfeng , Pan Yinming , Zhao Xuezhuang 
Published: October 2004

AbstractA total of eight possible isomers of C50O, an oxide of fullerene C50 (D5h), have been investigated by B3LYP/3‐21G calculations. The isomer, which has an annulene‐like structure with oxygen bridging across a [5,6] type CC bond at the site between the pole and the equatorial belt, is found being the ground state of C50O. Four isomers are relatively more stable and the energy differences between them are not large. This result indicates that more than one C50O isomer will coexist once C50O is synthesized. The relative stabilities of the C50O isomers may be determined mainly by the strain release and by the formation of the cyclic phenylene substructure at the equatorial belt of the cage. The calculated nucleus independent chemical shifts (NICS) of the C50O isomers will be useful because from them one can expect outstanding NMR properties that can lead to their identification and characterization. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
A gauge‐origin independent expression for the Verdet constant within the time‐dependent density functional theory
Authors: Banerjee Arup , Autschbach Jochen , Ziegler Tom 
Published: October 2004

AbstractThe analytical expression for the Verdet constant of magneto‐optical rotation is presented within the time‐dependent density functional theory formalism. Use has been made of gauge, including atomic orbitals, to circumvent the problem of gauge dependence often associated with the calculation of magnetic properties. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Avoiding asymptotic divergence of the potential from orbital‐ and energy‐dependent exchange‐correlation functionals
Authors: Niquet Y. M. , Fuchs M. , Gonze X. 
Published: October 2004

AbstractWe investigate the asymptotic behavior of the exchange‐correlation potentials deriving from orbital‐ and energy‐dependent (OED) functionals potentially able to describe van der Waals interactions. We take some simple functionals based on the adiabatic connection fluctuation‐dissipation (ACFD) theorem as examples. Although the potentials deriving from arbitrary OED functionals can be expected to diverge asymptotically, we find that these ACFD potentials are in fact well behaved. They indeed depend on Kohn–Sham orbitals and energies only through the Kohn–Sham Green function, allowing for complete analytical treatment. However, the dependence on the empty Kohn–Sham orbitals and energies must be treated with care. We discuss some precautions to be taken for practical calculation of these potentials. Last, we introduce approximate potentials, which are much simpler to compute than the exact ones, but are still quite accurate. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Effect of neonatal isolation on the noradrenergic transduction system in the rat hippocampal slice
Authors: Kusaka Kouji , Morinobu Shigeru , Kawano Ki‐Ichiro , Yamawaki Shigeto 
Published: October 2004

AbstractNumerous studies suggest that early adverse experiences induce neurochemical, morphological, and functional changes in the hippocampus in adolescence and adulthood. The aim of this study was to identify the influence of neonatal isolation (NI) on noradrenaline (NA)‐mediated intracellular calcium ([Ca2+]i) mobilization. To measure [Ca2+]i, we used the Ca2+‐sensitive dye fura‐2 and analysis by fluorescence microscopy. First, we examined the contributions of adrenergic receptor subtypes to the NA‐stimulated increase in [Ca2+]i in the granule cell layers of the dentate gyrus (DG) and in the pyramidal cell layers of the CA3 in the hippocampus. Second, we found that the NA‐stimulated [Ca2+]i increment was significantly decreased in response to NI in these hippocampal regions. In addition, we examined the influence of environmental enrichment (EE) after weaning on the decrease in the NA‐stimulated [Ca2+]i increment induced by NI. The administration of EE reversed the influence of NI on the NA‐stimulated [Ca2+]i increment in the CA3 pyramidal cell layer but not in the DG granular cell layer in the hippocampus. These findings suggest that NI and EE after weaning may modulate hippocampal function by altering adrenergic receptor‐mediated signal transduction during adolescence. Synapse 54:223–232, 2004. © 2004 Wiley‐Liss, Inc.
Mycosporine‐glutaminol‐glucoside, a UV‐absorbing compound of two Rhodotorula yeast species
Authors: Sommaruga Ruben , Libkind Diego , van Broock Maria , Whitehead Kenia 
Published: October 2004

AbstractHigh‐performance liquid chromatography (HPLC), alone or in combination with mass spectrometry (MS), was used to screen the basidiomycetous yeasts Rhodotorula minuta and R. slooffiae isolated from lakes for the presence of UV‐absorbing compounds. Mycosporine‐glutaminol‐glucoside (maximum absorption, 310 nm), a UV‐photoprotective mycosporine known in terrestrial fungi, was the major UV‐absorbing compound found in these species. This is the first identification of a mycosporine in yeasts. The presence of this compound seems to be a promising chemotaxonomical marker for yeast systematics. Copyright © 2004 John Wiley & Sons, Ltd.
Limitations of codon adaptation index and other coding DNA‐based features for prediction of protein expression in Saccharomyces cerevisiae
Authors: Friberg Markus , von Rohr Peter , Gonnet Gaston 
Published: October 2004

AbstractThe relationship between codon usage and protein/mRNA expression in S. cerevisiae has been extensively studied. Recently, protein expression data for the whole yeast genome was published. We investigate which properties of coding DNA sequences can be used to predict expression levels. The new algorithm by Carbone et al. for computing dominating codon bias in a genome is evaluated. It is concluded that it works at least as well as existing methods, and eliminates the need to arbitrarily choose a set of highly expressed genes. Also, the hypothesis that information on codon pair frequencies can be used to predict expression is investigated. Our conclusion is that codon pairs do not contribute more information than do single codon frequencies. Overall correlation between predicted and actual expression data using properties of coding DNA sequences is around 0.65. Hence, while being a useful source of information, the expression levels predicted by these methods should only be used as a rule of thumb. Copyright © 2004 John Wiley & Sons, Ltd.
Mating‐induced mating‐type cassette conversion in Saccharomyces cerevisiae
Authors: Nishida Yuri , Katoh Hiroyuki , Andoh Masahiko , Ono Bun‐ichiro 
Published: October 2004

AbstractWe have previously reported that the HMRa‐bearing restriction fragment of a ρ° sir4‐11 strain (HMLα‐MATα‐HMRa), which acts as an α‐mater because of being ρ°, changes its electrophoretic mobility when the strain mates with a certain group of a‐mating strains (HMLα‐MATa‐HMRa). In this study, we found that the sir4‐11 strain being ρ° was not essential for this phenomenon and also that the altered form of the fragment contained HMRα in place of HMRa. Furthermore, we observed conversion of HMLa to HMLα in the cross in which a sir4‐11 HMLa‐MATα‐HMRα strain was mated with a representative of the above‐mentioned a‐mating strain. In addition, when this a‐mating strain was mated with a SIR+ HMLα‐MATa‐HMRα strain, the resultant diploid was found to be HMLα/HMLα MATa/MATαHMRa/HMRα, indicating that conversion of MATa to MATα had taken place in the course of mating. From all these observations, we conclude that there is a group of S. cerevisiae strains that carries factor(s) that induces conversion of a mating‐type cassette of the mating partner to α mating‐type cassette and that this mating type cassette conversion takes place in all three mating type loci, HML, MAT and HMR, if the loci are in the non‐silenced condition. Copyright © 2004 John Wiley & Sons, Ltd.
Surgical training in a statutory health insurance system: Belgian experience
Authors: Hubens A. , Van Hee R. 
Published: October 2004

AbstractHealth care delivery in Belgium is based on a compulsory insurance system, installed and controlled by the government since 1945 for employees; in 1963 the system was expanded to include self‐employed citizens. Mutual benefit organizations act as insurance carriers for all patients, whether cared for in the office or hospital. The cost of statefinanced medical care has grown to such an extent during the last few decades that cost‐sharing in ambulatory practice is being extended to in‐clinic services. The free choice of practitioners as well as free access to medical and specialist education have always been keystones of the Belgian medical care system. A well regulated scheme of surgical training combined with strict rules imposed on instructors, hospitals, and trainees guarantee high quality and state‐controlled surgical education. Developments in the Belgian political landscape may considerably affect health care delivery and surgical education. A constant rise in the number of medical practitioners and the sociopolitical discrepancies between the Flemish and French speaking parts of the federalized kingdom have paralleled burgeoning medical health care costs and have induced rationalization and possibly federalization of health care dilivery as well as ongoing debates concerning the limitation of medical and surgical practitioners.
Health care delivery systems: Effects on surgical education in Italy
Authors: Stipa Sergio , Ziparo Vincenzo , Castorina Silvia 
Published: October 2004

AbstractSince 1989 a national health system (NHS) has been in effect in Italy based on the constitutional principle that health care is a right of all citizens. Until 1992 the NHS had a secondary role in medical education, as the 33 medical schools for postgraduate training are under the control of the Ministry of University. The European Community legislation allowing free movement of M.D.s and specialists between member countries has resulted in standardization of teaching programs and formative curricula in the European Community. Therefore beginning in 1992, every 3 years the Ministry of Health and University establishes the number of specialists that can meet the needs of the NHS and allocates funds to each school for the salary obligations. The actual number of paid residents for surgical specialities is 941 per year (192 for general surgery). Until recently surgical training in Italy was mainly theoretic, as no legislation guaranteed that physicians in training would perform surgery. New legislation, increased exchanges with European hospitals, and improved and loyal cooperation between universities and the NHS will certainly improve the situation in coming years.
Health care delivery system. Effects on surgical education: The Mexican panorama
Authors: Cervantes Jorge , Cervantes Arturo 
Published: October 2004

AbstractHealth care delivery in Mexico is divided in three groups: a social sector that covers approximately 53% of the population and is financed by the labor force, the state and the employer; a public, or open, sector that covers 33% of the population and is financed by federal and state funds; and a private sector that covers about 5% of the population and has two categories, the not‐for‐profit hospitals and the profit‐oriented institutions. Most medical practitioners can work in any of the three groups or in several. Nine percent of Mexico's population, because of extreme ignorance, poverty, or isolation, have no or limited access to medical care. Mexico has 58 medical schools, which graduate about 7800 new physicians annually, awarding them the title Medico cirujano (Physician Surgeon). There are more than 160,000 physicians in Mexico, 20,000 of whom are unemployed. Each year, approximately 12,000 physicians compete for the 4306 places in the official residency training programs for all specialties. Of those taking the examination, 2000 try to get one of the 625 slots available for training in general surgery. Most of the surgical training programs in Mexico have a 3‐year duration. The Mexican Academy of Surgery, the Mexican Society of General Surgery, and the Mexican Board of Surgery, as well as private individuals and organizations, are working to improve the quality of medical education and trying to establish a 5‐year training program in surgery. The rapid movement toward modernization that is sweeping the country must include the improvement of surgical education as well.
Health care provision and surgical education in South Africa
Authors: Thomson Sandie R. , Baker Lynne W. 
Published: October 2004

AbstractApartheid policies have led to inequalities in the delivery of health care and the training of surgeons in South Africa. The nation's population of 33 million is comprised of 73.6% Blacks, 14.8% Whites, 8.8% Coloureds, and 2.7% Asians. Only 17% of the population are covered by medical insurance (78% of Whites, 28% of Asians, 26% of Coloureds, 4% of Blacks) that funds the private sector which accounts for 46% of the nation's total health care expenditure of 9.2156 million rand. The remainder receive care from curative state hospital based services, which consume 77% of the public expenditure on health. Preventive and promotive health services account for 23%. only 3.2% of South Africa's gross national product is spent on health care provision for 80% of the population‐well short of the World Health Organization's recommendation of 5.8%. This figure translates into a per capita expenditure of 138, 340, 356, and 597 rands for Blacks, Coloureds, Asians, and Whites, respectively. Eight medical schools produce just over 900 graduates per year, 80% of whom are white. The medium of instruction is English at five (Cape Town, Witwatersrand, Natal, MEDUNSA, and Transkei) and Afrikaans at three (Pretoria, Stellenbosch, and Bloemfontein). Natal and MEDUNSA are creations of apartheid and have graduated almost all the Black South African doctors, of whom only 15 are practicing surgeons. Many universities are cognizant that dramatic change is needed to redress such imbalances, and admission policies are changing. Schools are addressing the implications of admitting many more Black African students from less privileged educational backgrounds into their medical faculties. Only then will more nonwhite graduates emerge with excellent, well monitored specialist training in surgery, which until now has been the domain of mainly white doctors.
Swedish health care delivery system and its effects on surgical education
Authors: Bengmark Stig , Jeppson Bengt 
Published: October 2004

AbstractSweden, with a small, decentralized population, has a similarly decentralized network of hospitals that comprise the national health care system, which is nonetheless highly regulated by the national government. Medical education and graduate training in surgery are likewise regulated. Reforms implemented in 1992 made a 21‐month general rotating internship mandatory for all medical graduates, after which they enter specialty training. That training, which lasts a minimum of 5 years, is done under the tutelage of a Board‐certified practitioner in the field. During the trainee and program contract for the amount of time spent in clinical and didactic experiences, the trainee is personally responsible for ensuring that much of his or her individual programs is accomplished. Rising health care costs have spurred increased rationalization of resources and are expected to constrict training opportunities for future surgeons.
Changing surgical education strategies in an environment of changing health care delivery systems
Authors: Dunnington Gary L. , DaRosa Debra A. 
Published: October 2004

AbstractEmerging changes in health care delivery will have a significant impact on the structure of surgical education in academic departments of surgery. Based on some assumptions as to the probable nature of the final product of this reform, this article encourages a proactive stance by surgical educators to anticipate changes and move toward restructuring in areas of curricular content, the teaching process, performance evaluation strategies, and faculty infrastructure of the academic department. Curriculum changes must bridge the gap between public health and medicine and continue the aggressive trend toward teaching in the outpatient setting. Surgical educators must adapt to evolving computer and instructional technology that will make multimedia presentations, distance education, teleconferencing, hypermedia, and virtual reality commonplace in the teaching setting. Increased emphasis on accountability and accreditation will require stringent criteria in performance and program evaluation methodology. The academic infrastructure will need to adapt to the changing goal of training more general surgeons and fewer specialists and yet maintain the fundamental responsibility of an academic surgeon for mentoring the medical student and surgical resident.
U.S. health care reform: Will it change postgraduate surgical education?
Authors: Pories Walter J. , Smout Jay C. , Morris Alva , Lewkow Victoria E. 
Published: October 2004

AbstractThe principal goals of the pending health care reform initiatives in the United States are improving access to health care and controlling its costs. There are multiple proposals designed to reach these goals. Regardless of the final result, health care reform is likely to have significant implications for postgraduate surgical education. The teaching environment is already rapidly changing. Present environmental influences include the explosion of surgical knowledge, demographic changes, expansion of regulatory requirements from within the health care delivery system and within surgery as a discipline, societal and cultural changes, and economic pressures. Current and pending concerns prompt several questions: What should we teach? Where do we teach? How long should it take? Who are our learners? How do we evaluate our educational programs? Who should pay? A number of predictable changes affecting surgical education are proposed. New, more complex technologies will result in increased surgical specialization. Demands on surgical education will require that it be shorter, more relevant, more efficient, more effective, and more accountable. Surgical manpower requirements must be more clearly defined. Better and more relevant measures of clinical outcomes will be developed. Use of improved informational technology to manage clinical activity will expand. Solutions to the problem of foreign medical graduates will be clarified. The issue of who pays for surgical education will require resolution with some new and creative results. A proposal for shorter and more effective surgical residency is advocated.