Formamidinium Lead Halide Perovskite Nanocomposite Scintillators.

While there is great demand for effective, affordable radiation detectors in various applications, many commonly used scintillators have major drawbacks. Conventional inorganic scintillators have a fixed emission wavelength and require expensive, high-temperature synthesis; plastic scintillators, while fast, inexpensive, and robust, have low atomic numbers, limiting their X-ray stopping power. Formamidinium lead halide perovskite nanocrystals show promise as scintillators due to their high X-ray attenuation coefficient and bright luminescence. Here, we used a room-temperature, solution-growth method to produce mixed-halide FAPbX3 (X = Cl, Br) nanocrystals with emission wavelengths that can be varied between 403 and 531 nm via adjustments to the halide ratio. The substitution of bromine for increasing amounts of chlorine resulted in violet emission with faster lifetimes, while larger proportions of bromine resulted in green emission with increased luminescence intensity. By loading FAPbBr3 nanocrystals into a PVT-based plastic scintillator matrix, we produced 1 mm-thick nanocomposite scintillators, which have brighter luminescence than the PVT-based plastic scintillator alone. While nanocomposites such as these are often opaque due to optical scattering from aggregates of the nanoparticles, we used a surface modification technique to improve transmission through the composites. A composite of FAPbBr3 nanocrystals encapsulated in inert PMMA produced even stronger luminescence, with intensity 3.8× greater than a comparative FAPbBr3/plastic scintillator composite. However, the luminescence decay time of the FAPbBr3/PMMA composite was more than 3× slower than that of the FAPbBr3/plastic scintillator composite. We also demonstrate the potential of these lead halide perovskite nanocomposite scintillators for low-cost X-ray imaging applications.

Bullying victimization: Associated contextual factors in a Greek sample of children and adolescents.

School bullying is increasingly recognized as an important factor affecting both individual's wellbeing and social functioning. Several studies provide evidence for the potential role of contextual factors that relate to bullying victimization such as the socioeconomic status of the parents/ family, the quality of family and home environment, the school climate, structure and ethos, and also various community characteristics. The objectives of this school-based, cross-sectional study were to report the prevalence of the perception of being bullied in a sample of Greek children and adolescents from 6 to 17 years of age and to investigate the relations among the subjective impression of bullying victimization and several sociodemographic and socioeconomic factors. We hypothesized that influences external to individual children and adolescents play a decisive role to their perception of being victimized. Bullying victimization was measured through a simple "yes/no" question, which confirmed or rejected respectively the fact that the child or adolescent has been at some time victimized in the school environment. Also, demographic and socioeconomic data about the families of children and adolescents were collected. A total of 1,588 children (51.8% females, mean age ± SD: 12.9±2.8 years) were assessed. The overall prevalence of victimization was 10.4%. Multiple logistic regression analysis on the probability of being victimized identified that living at a main urban center (Odds Ratio[OR]: 2.63, CI: 1.78-3.87, p<0.001), presence of a person with a chronic illness at home (OR: 1.90, CI: 1.12-3.20, p=0.016), poor family economic status (OR: 1.83, CI: 1.05-3.20, p=0.032),and increased number of adults at home (OR: 2.00, CI: 1.00-3.77, p=0,041) had a positive correlation with the prevalence of reported bullying victimization. Moreover, higher parental educational level related to lower probability of victimization (OR: 0.88, CI: 0.78-0.99, p=0.05). These findings demonstrate that several demographic and socioeconomic factors play a potential role in bullying victimization among schoolchildren. Our results also highlight the need to consider the influence of contextual factors in the design of targeting efforts countering and/or preventing bullying victimization.

[Antimicrobial stewardship programme implementation in a medical ward]. / Implantación de un programa de optimización y uso racional de antimicrobianos en un modelo de área clínica médica.

OBJECTIVE: Antimicrobial stewardship programmes (ASP) have proven to be effective tools for reducing the use of antimicrobials. The purpose of the study is to evaluate the effect of an ASP implantation in a medical Ward. METHODS: Prospective intervention study in a medical ward with a heterogeneous composition. In September 2014, an ASP based on prospective audits was implemented. Antimicrobial consumption and the length of stay and mortality in all patients admitted, as well as in the main infections present in the unit, were compared before and after two years of the ASP implementation. RESULTS: A total of 378 infectious episodes of 335 pa-tients were evaluated in 168 meetings. The prescriber ac-cepted 92.3% of the suggestions. The consumption of an-timicrobials reviewed was reduced from 31.3 to 17.6 DDD / 100-stays (ß =-0.40, P = 0.015). The average cost per income was reduced from € 161.4 to € 123.3 (-23.6%). No differences were found in total length of stay or mortality. There were no changes in the incidence of Clostridium difficile infection or candidemia between the two periods. There were no significant differences in length of stay or mortality in total bacteremia, candidemia, and urinary tract infections caused by multiresistant bacteria. CONCLUSIONS: The implementation of an ASP in a heterogeneous medical ward significantly reduces the use of antimicrobials in a short time horizon without adversely affecting the evolution of the patients..

Functional gastrointestinal disorders in Greek Children based on ROME III criteria: identifying the child at risk.

BACKGROUND: Functional gastrointestinal disorders (FGIDs) are a common, diverse group of disorders of unknown etiology, resulting in significant socieconomic burden. In this study, we aimed to assess the prevalence of FGIDs in children aged 6-18 years and examine their association with various demographic and socioeconomic parameters. METHODS: This was a school-based, cross-sectional study approved by the relevant government authorities. Informed consent was obtained by the legal representatives of all children who participated. Diagnoses of FGIDs were based on the Greek official translation of the ROME-III questionnaire. Demographic and socioeconomic information were also collected. KEY RESULTS: A total of 1588 children (51.8% females, mean age: 12.9±2.8 years) were included. The overall prevalence of any-FGID was 23.1% (95% CI: 21.1-25.2). The most common FGIDs were functional constipation, n=231 (13.9%), abdominal migraine, n=84 (5.6%), aerophagia, n=58 (3.5%), and irritable bowel syndrome, n=48 (3.0%). Multiple logistic regression analysis on the probability of any-FGID identified physical exercise, TV-exposure, victimization, gender, parental educational level, number of children at home and number of adults at home as significant covariates for any-FGID in the final model. CONCLUSIONS AND INFERENCES: FGIDs affect approximately 1 in 4 school-aged children in Greece. The following characteristics are associated with a higher probability of any-FGID: female gender, living in a non-nuclear household, victimization, lower parental education level, infrequent physical activity, and high television exposure.

First-trimester screening with specific algorithms for early- and late-onset fetal growth restriction.

OBJECTIVE: To develop optimal first-trimester algorithms for the prediction of early and late fetal growth restriction (FGR). METHODS: This was a prospective cohort study of singleton pregnancies undergoing first-trimester screening. FGR was defined as an ultrasound estimated fetal weight < 10(th) percentile plus Doppler abnormalities or a birth weight < 3(rd) percentile. Logistic regression-based predictive models were developed for predicting early and late FGR (cut-off: delivery at 34 weeks). The model included the a-priori risk (maternal characteristics), mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1). RESULTS: Of the 9150 pregnancies included, 462 (5%) fetuses were growth restricted: 59 (0.6%) early and 403 (4.4%) late. Significant contributions to the prediction of early FGR were provided by black ethnicity, chronic hypertension, previous FGR, MAP, UtA-PI, PlGF and sFlt-1. The model achieved an overall detection rate (DR) of 86.4% for a 10% false-positive rate (area under the receiver-operating characteristics curve (AUC): 0.93 (95% CI, 0.87-0.98)). The DR was 94.7% for FGR with pre-eclampsia (PE) (64% of cases) and 71.4% for FGR without PE (36% of cases). For late FGR, significant contributions were provided by chronic hypertension, autoimmune disease, previous FGR, smoking status, nulliparity, MAP, UtA-PI, PlGF and sFlt-1. The model achieved a DR of 65.8% for a 10% false-positive rate (AUC: 0.76 (95% CI, 0.73-0.80)). The DR was 70.2% for FGR with PE (12% of cases) and 63.5% for FGR without PE (88% of cases). CONCLUSIONS: The optimal screening algorithm was different for early vs late FGR, supporting the concept that screening for FGR is better performed separately for the two clinical forms. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Cost-effectiveness of three echinocandins and fluconazole in the treatment of candidemia and/or invasive candidiasis in nonneutropenic adult patients.

OBJECTIVE: To estimate the cost-effectiveness of three echinocandins (anidulafungin, caspofungin, and micafungin) and generic fluconazole in the treatment of nonneutropenic adult patients with candidemia and/or invasive candidiasis in intensive care units in Spain. MATERIALS AND METHODS: A decision-tree model was applied. The success and safety (hepatic and renal adverse effects) of first-line treatments were obtained from meta-analyses and systematic reviews of clinical trials. In the case of failure, a second-line treatment (liposomal amphotericin B after the echinocandins, or one of the echinocandins after fluconazole) was administered. The duration of the treatments (14 days total) was established by a panel of clinical experts using the Delphi method and according to Infectious Diseases Society of America guidelines. The cost of the medications and renal toxicity were considered. Deterministic and probabilistic sensitivity analysis using Monte Carlo simulations were carried out. RESULTS: The total cost of the treatment of candidemia and/or invasive candidiasis with anidulafungin, caspofungin, micafungin, and fluconazole was €5,483, €5,968, €6,231, and €2,088, respectively. Anidulafungin was the dominant treatment (more effective, less expensive) compared to micafungin and caspofungin. The cost of achieving one more patient successfully treated with anidulafungin, caspofungin, and micafungin compared to fluconazole was €17,199, €23,962, and €27,339, respectively. The result remained stable, despite modification of the duration of the first-line and second-line treatments, as well as most of the dosing regimens. The probabilistic analysis also remained stable. CONCLUSION: In accordance with this economic study, anidulafungin would produce savings and would be the dominant treatment compared with micafungin and caspofungin in nonneutropenic adult patients with candidemia and/or invasive candidiasis in intensive care units in Spain.

Ultrasound screening for fetal growth restriction at 36 vs 32 weeks' gestation: a randomized trial (ROUTE).

OBJECTIVE: To compare the utility of routine third-trimester ultrasound examination at 36 weeks' gestation with that at 32 weeks in detecting fetal growth restriction (FGR). METHODS: This was an open-label parallel randomized trial (ROUTE study) conducted at a single general hospital serving a geographically well-defined catchment area in Barcelona, Spain, between May 2011 and April 2014. Women with no adverse medical or obstetric history and a singleton pregnancy without fetal abnormalities at routine second-trimester scan were assigned randomly to undergo a scan at 32 weeks' gestation (n = 1272) or at 36 weeks' gestation (n = 1314). Primary outcome measures were detection rates of FGR (customized birth weight < 10(th) centile) and severe FGR (customized birth weight < 3(rd) centile). RESULTS: There were no significant differences in perinatal outcome between those who underwent a scan at 32 weeks' gestation and those who underwent a scan at 36 weeks' gestation. Severe FGR at birth was associated significantly with emergency Cesarean delivery for fetal distress (odds ratio (OR), 3.4 (95% CI, 1.8-6.7)), neonatal admission (OR, 2.23 (95% CI, 1.23-4.05)), hypoglycemia (OR, 9.5 (95% CI, 1.8-49.8)) and hyperbilirubinemia (OR, 9.0 (95% CI, 4.6-17.6)). Despite similar false-positive rates (FPRs) (6.4% vs 8.2%), FGR detection rates were superior at 36 vs 32 weeks' gestation (sensitivity, 38.8% vs 22.5%; P = 0.006), with positive and negative likelihood ratios of 6.1 vs 2.7 and 0.65 vs 0.84, respectively. In cases of severe FGR, FPRs for both scans were also similar (8.5% vs 8.7%), but detection rates were superior at 36 vs 32 weeks' gestation (61.4% vs 32.5%; P = 0.008). Positive and negative likelihood ratios were 7.2 vs 3.7 and 0.4 vs 0.74, respectively. CONCLUSION: In low-risk pregnancies, routine ultrasound examination at 36 weeks' gestation was more effective than that at 32 weeks' gestation in detecting FGR and related adverse perinatal and neonatal outcomes.

Factors involved in sustained use of point-of-use water disinfection methods: a field study from Flores Island, Indonesia.

Many scientific studies have suggested that point-of-use water treatment can improve water quality and reduce the risk of infectious diseases. Despite the ease of use and relatively low cost of such methods, experience shows the potential benefits derived from provision of such systems depend on recipients' acceptance of the technology and its sustained use. To date, few contributions have addressed the problem of user experience in the post-implementation phase. This can diagnose challenges, which undermine system longevity and its sustained use. A qualitative evaluation of two household water treatment systems, solar disinfection (SODIS) and chlorine tablets (Aquatabs), in three villages was conducted by using a diagnostic tool focusing on technology performance and experience. Cross-sectional surveys and in-depth interviews were used to investigate perceptions of involved stakeholders (users, implementers and local government). Results prove that economic and functional factors were significant in using SODIS, whilst perceptions of economic, taste and odour components were important in Aquatabs use. Conclusions relate to closing the gap between factors that technology implementers and users perceive as key to the sustained deployment of point-of-use disinfection technologies.

Determinants of adherence to gluten-free diet in Greek children with coeliac disease: a cross-sectional study.

BACKGROUND/OBJECTIVE: A strict and lifelong commitment to a gluten-free diet (GFD) remains one of the most challenging issues in children with coeliac disease. The present study aimed to record compliance rates and investigate the connection between dietary compliance and demographics, disease-related factors and parental knowledge. SUBJECTS/METHODS: Parents of 90 Greek children diagnosed with coeliac disease were recruited from the outpatient gastroenterology clinic of a children's hospital in Athens, Greece. Dietary compliance and a range of demographic and clinical data were obtained from parents through a specially constructed questionnaire. Further data included parental perceived and actual knowledge about coeliac disease and GFD. Compliant and noncompliant groups were compared for measured factors and a multivariate approach was followed to elicit independent effects of compliance determinants. RESULTS: Overall, 44.4% of children with coeliac disease were reported to be compliant to a strict GFD. A 1-year increase in the age of the child was associated with 15% lower odds of adhering to a strict diet after adjusting for other variables (odds ratio (OR)=0.85, 95% CI: 0.75-0.96). Parental perceived knowledge was also independently and significantly associated with dietary compliance (OR=3.3, 95% CI=1.1-9.8). No statistically significant correlation emerged between dietary compliance and other clinical or demographic variables. DISCUSSION: Low compliance rates to GFD were observed in children with coeliac disease. Information based on children's age and perceived parental knowledge can be used to develop risk profiles that health care professionals can utilise to identify children likely to be noncompliant and thus adjust their counselling strategy accordingly.

Ancient water and sanitation systems - applicability for the contemporary urban developing world.

The idea of implementing ancient water and wastewater technologies in the developing world is a persuasive one, since ancient systems had many features which would constitute sustainable and decentralised water and sanitation (WATSAN) provision in contemporary terminology. Latest figures indicate 2.6 billion people do not use improved sanitation and 1.1 billion practise open defecation, thus there is a huge need for sustainable and cost-effective WATSAN facilities, particularly in cities of the developing world. The objective of this study was to discuss and evaluate the applicability of selected ancient WATSAN systems for the contemporary developing world. Selected WATSAN systems in ancient Mesopotamia, the Indus Valley, Egypt, Greece, Rome and the Yucatan peninsula are briefly introduced and then discussed in the context of the developing world. One relevant aspect is that public latrines and baths were not only a part of daily life in ancient Rome but also a focal point for socialising. As such they would appear to represent a model of how to promote use and acceptance of modern community toilets and ablution blocks. Although public or community toilets are not classified as improved sanitation by WHO/UNICEF, this is a debatable premise since examples such as Durban, South Africa, illustrate how community toilets continue to represent a WATSAN solution for urban areas with high population density. Meanwhile, given the need for dry sanitation technologies, toilets based on the production of enriched Terra Preta soil have potential applications in urban and rural agriculture and warrant further investigation.

Retinol Binding Protein 4 in children with Inflammatory Bowel Disease: a negative correlation with the disease activity.

OBJECTIVES: Retinol Binding Protein-4 (RBP-4), the action of which was initially thought to be only the transport of vitamin A, is a major circulating adipocytokine involved in the inflammation. We evaluated the serum RBP-4 levels in children with inflammatory bowel disease (IBD) and correlated them with transthyretin (TTR), inflammation markers, disease activity, and body mass index (BMI). DESIGN: In 41 children of mean age 11.9 ± 3.6 years (range 5-17.7 y) with IBD (19 with Crohn's disease (CD) and 22 with Ulcerative colitis (UC) serum RBP-4, TTR, Amyloid A (SAA), C-Reactive Protein (CRP), Erythrocyte Sedimentation Rate (ESR), disease activity and BMI were prospectively determined and compared with those of 42 matched controls. RESULTS: No difference in the RBP-4 and TTR serum levels, between patients and controls as well as between active and remission state of the disease was noticed. A negative correlation of serum RBP-4 with the disease activity, SAA and ESR and a positive correlation with TTR was found, but no significant correlation with CRP or BMI was found. Inflammation markers were significantly increased in patients compared to controls and had a positive correlation with the disease activity. CONCLUSIONS: RBP-4 negatively correlated with disease activity of children with IBD probably indicating a protective anti-inflammatory mechanism of action in addition to transport of vitamin A.

Atypical hemolytic-uremic syndrome (HUS) with recovery after a long-lasting anuria: a case report.

We report a case of a seven-year-old girl who suffered from atypical Hemolytic Uremic Syndrome (aHUS) complicated by septicaemia, central nervous system involvement, and cholangiitis. She remained anuric requiring treatment with peritoneal dialysis (PD) for a five-month period. In addition to conventional therapeutic measures including fresh frozen plasma (FFP) and blood cells transfusions she also underwent to plasma exchange (PE) treatment. Following a stormy hospitalization period of 17 weeks, the patient finally regained renal function and three years later she remains well on antihypertensive treatment and free of dialysis.

Dietary compliance and life style of children with coeliac disease.

BACKGROUND: Coeliac disease (CD) is common and requires a permanent strict gluten-free diet (GFD). However, data concerning how the situation is experienced by children are limited. The present study aimed to investigate the compliance with a GFD and the impact of CD and GFD on the lifestyle of patients and their families, together with proposed recommendations for improvement of quality of life. METHODS: Children with biopsy confirmed CD were recruited consecutively from the outpatient gastroenterology clinic. Participants were evaluated by a special questionnaire for compliance with the GFD, patients' knowledge about CD, and the well-being and lifestyle of children and their families. Comparisons between discrete variables were performed by a chi-square test. RESULTS: Seventy-three children of median age 9.4 (interquartile range = 5-14.5) years were evaluated. Compliance to diet was reported by 58%. Reasons for noncompliance were: poor palatability (32%), dining outside home (17%), poor availability of products (11%), and asymptomatic disease diagnosed by screening (11%). The acceptance of the GFD was reported as good in 65%, whereas avoidance of travelling and restaurants was stated by 17% and 46% of families, respectively. Most families experienced difficulties detecting gluten from the food label. Proposed factors for improvement of quality of life were: better labelling of gluten-containing ingredients (76%) and more gluten-free (GF) foods in supermarkets (58%) and restaurants (42%). CONCLUSIONS: Children with CD have low compliance with the GFD. Better education about the disease, the availability of GF products, and appropriate food labelling could improve compliance and quality of life.

[Towards a multi-step informed consent: considerations and proposals for a good practice]. / Verso un consenso informato a più fasi: considerazioni e proposte per una buona prassi.

Any therapeutic intervention needs consent from the patient, after have received information from the physician. This is often seen as a bureaucratic accomplishment but it could enhance therapeutic alliance. We propose to divide consent from information, offering a place in which doubts and emotions can be explored, with the assistance of a psychological interview. We believe that this new approach can enhance physician-patient relationship, with an improvement in patient satisfaction and a decrease of claims and complaints.

10 years' experience in fragile X testing among mentally retarded individuals in Greece: a molecular and epidemiological approach.

Fragile X syndrome, the second most common genetic cause of mental retardation, is due to the expansion of a trinucleotide repeat (CGG)n within the first exon of the FMR-1 gene. Molecular genetic analysis provides accurate diagnosis and facilitates genetic counselling and prenatal testing. Screening for the fragile X mutation in a sample of 3,888 individuals in Greece is reported: 1,755 children with non-specific mental retardation, 1,733 parents and other family members and 400 normal individuals. Molecular analysis allowed for the identification and characterization of 52 fragile X families confirming the clinical diagnosis in 57 males and 4 females. Sixty-six female carriers (6 mentally retarded) and 4 normal transmitting males were also identified. Four severely retarded males and their mothers carried unmethylated premutations, while a moderately retarded girl had a deletion of approximately equal to 150 bp. Overall sizing of the CGG repeat produced an allele distribution of 6-58 CGG repeats (mean 28-30), similar to that in other Caucasian populations.

[Cefditoren pivoxil: A new oral cephalosporin for skin, soft tissue and respiratory tract infections]. / Cefditoren pivoxilo: una nueva cefalosporina oral para infecciones de vias respiratorias y de piel y tejidos blandos.

Cefditoren pivoxil, a new-third generation cephalosporin antibiotic that has recently been granted approval in Spain, shows important activity over a large part of the pathogens causing skin, soft tissue and respiratory tract infections, including Gram-negative and Gram-positive bacteria. Cefditoren has also been shown to be stable against hydrolysis by many common beta-lactamases. Data from in vitro studies and clinical trials show this antibiotic as an oral formulation with an intrinsic activity against Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae equivalent to that of other third-generation cephalosporins administered via parenteral, like cefotaxime or ceftriaxone, thereby placing its maximal benefits mainly in the treatment of ambulatory infections. This paper reviews the main characteristics of cefditoren pivoxil (spectrum of activity, chemical structure, mechanism of action, pharmacokinetics, adverse effects and clinical efficacy) and attempts to find its place in current antibiotic therapeutics.

Serum CA125 level modifications in women undergoing repeated IVF cycles.

In the present paper, serum CA125 modifications in patients undergoing their first IVF cycle were compared with those of patients in their second attempt. A significant increase of this marker was detected in each group of patients at day 14 after embryo transfer. However, the level of CA125 monitored in the patients in their second attempt was significantly higher than that determined in patients undergoing their first ovarian stimulation. This condition does not influence either ovarian response or oocyte and embryo quality. Moreover similar IVF outcome was obtained. Therefore we propose that patients undergoing repeated assisted reproductive technology (ART) cycles may suffer from ovarian surface epithelial damage and/or altered cellular growth rate.

Cefditoren pivoxilo: una nueva cefalosporina oral para infecciones de vías respiratorias y de piel y tejidos blandos / Cefditoren pivoxil: A new oral cephalosporin for skin, soft tissue and respiratory tract infections

Recientemente se ha aprobado en España cefditoren pivoxilo, una nueva cefalosporina oral de tercera generación con importante actividadsobre gran parte de los patógenos causantes de infecciones de vías respiratorias, de piel y tejidos blandos, entre ellos bacterias grampositivasy gramnegativas, y que además es estable frente a la hidrólisis por muchas de las betalactamasas habituales. Teniendo en cuenta los datosin vitro y la eficacia mostrada en los ensayos clínicos, parece ser una alternativa equivalente a la cefotaxima o la ceftriaxona, pero de administraciónoral, por su actividad intrínseca equiparable frente a Haemophilus influenzae, Moraxella catarrhalis y Streptococcus pneumoniae,y cuyo lugar principal se sitúa fundamentalmente en el ámbito extrahospitalario. El objetivo de este trabajo es realizar una revisión delas principales características de cefditoren pivoxilo (espectro de actividad, estructura, mecanismo de acción, farmacocinética, reacciones adversasy eficacia clínica) con objeto de orientar su lugar en la terapéutica antimicrobiana

Cefditoren pivoxil, a new-third generation cephalosporin antibiotic that has recently been granted approval in Spain, shows important activityover a large part of the pathogens causing skin, soft tissue and respiratory tract infections, including Gram-negative and Gram-positivebacteria. Cefditoren has also been shown to be stable against hydrolysis by many common beta-lactamases. Data from in vitro studiesand clinical trials show this antibiotic as an oral formulation with an intrinsic activity against Haemophilus influenzae, Moraxella catarrhalisand Streptococcus pneumoniae equivalent to that of other third-generation cephalosporins administered via parenteral, like cefotaxime orceftriaxone, thereby placing its maximal benefits mainly in the treatment of ambulatory infections. This paper reviews the main characteristicsof cefditoren pivoxil (spectrum of activity, chemical structure, mechanism of action, pharmacokinetics, adverse effects and clinical efficacy)and attempts to find its place in current antibiotic therapeutics

Reduced-size polarized basis sets for calculations of molecular electric properties. II. Simulation of the Raman spectra.

The accuracies of the calculated vibrational frequencies and Raman intensities given by two new, highly compact Pol-type basis sets, Z2PolX and Z3PolX, have been determined and compared to the 6-31G(d), PolX, and aug-cc-pVTZ basis sets. Calculation of accurate Raman intensities has previously required large basis sets, but the ZmPolX basis sets are smaller even than PolX, which are the most compact basis sets able to calculate accurate Raman intensities. For the largest compound studied, C5H10O2, Z3PolX required more than an order of magnitude less CPU time than PolX, which has been shown to be 10 times faster than aug-cc-pVTZ. Two sets of test molecules were studied: one was a series of small molecules for which experimental values for absolute Raman activities were available; the second was a series of medium-sized molecules (mainly common organic solvents) where only relative Raman band intensities were available. The accuracies of the Raman intensities given by both of the ZmPolX basis sets were good compared to those of the PolX and aug-cc-pVTZ sets, and much better than the 6-31G(d) values. The errors in even unscaled frequency values <2000 cm(-1) were also acceptable and were slightly lower for Z3PolX than Z2PolX (30 cm(-1) vs. 48 cm(-1)). The combination of good intensity and frequency data meant that for the medium-sized organic molecules there was a close correspondence between the simulated Raman spectra and experimental data, and that the observed bands could easily be assigned on the basis of these calculations. Achieving this level of accuracy in the simulations at modest computational cost should now allow computational methods to be combined with experimental Raman studies much more widely than is currently the case.

Reduced-size polarized basis sets for calculations of molecular electric properties. I. The basis set generation.

Following the recent studies of basis sets explicitly dependent on oscillatory external electric field we have investigated the possibility of some further truncation of the so-called polarized basis sets without any major deterioration of the computed data for molecular dipole moments, dipole polarizabilities, and related electric properties of molecules. It has been found that basis sets of contracted Gaussian functions of the form [3s1p] for H and [4s3p1d] for the first-row atoms can satisfy this requirement with particular choice of contractions in their polarization part. With m denoting the number of primitive GTOs in the contracted polarization function, the basis sets devised in this article will be referred to as the ZmPol sets. In comparison with earlier, medium-size polarized basis sets (PolX), these new ZmPol basis sets are reduced by 2/3 in their size and lead to the order of magnitude computing time savings for large molecules. Simultaneously, the dipole moment and polarizability data remain at almost the same level of accuracy as in the case of the PolX sets. Among a variety of possible applications in computational chemistry, the ZmPolX are also to be used for calculations of frequencies and intensities in the Raman spectra of large organic molecules (see Part II, this issue).