A simulation study on the effect of sodium on grain boundary passivation in CIGS thin-film solar cells

3D numerical simulations of CIGS thin-film solar cells with different grain-boundary (GB) characteristics have been carried out in order to investigate the effect of defect properties and band edge shifts at GBs on the cell performance. Simulation results are compared with experimental data taken on cells with and without NaF post deposition treatment. GBs with different energy gaps and defect properties have been analyzed. Simulations support the idea that the detrimental effect of defective GBs on the cell performance might be reduced by a treatment with Na. The results of this study can help with the interpretation of experimental findings

Insuficienţa respiratorie acută şi disfuncţia multiplă de organe la gravide cu complicatii pulmonare de etiologie virală

Catedra Anesteziologie şi Reanimatologie N2, Catedra Anesteziologie şi Reanimatologie N1 USMF „Nicolae Testemiţanu”In the study have been included 26 pregnant women and lying-in women with severe pulmonary complications associated with pandemic influenza virus a new type A (H1N1) -2009. Average age were about 28.2 ± 1.7 years, most pregnant women (84.62%) were in the second period of pregnancy, of which 65.38% in the last weeks of pregnancy. The most frequent pulmonary complications in pregnant women with influenza pandemic were viral pneumonia, bacterial pneumonia, acute lung injury/acute respiratory distress syndrome, spontaneous pneumotorax, pneumomediastinum, pleural effusion, passive regurgitation. Intensive care was complex and multi-faceted based on general principles and specific treatment, one of the main criteria is application of respiratory therapy carried out well and conduct begun on time. Pregnancy resolution in a timely manner is an important factor contributing to improved clinical outcomes in pregnant women with intensive pulmonary complications of pandemic influenza. În studiu au fost incluse 26 de gravide cu complicatii pulmonare severe pe fondal de Gripă pandemică cu virusul de tip nou A (H1N1) - 2009. Majoritatea gravidelor (84,62%) au fost în a doua perioadă a sarcinii, dintre care 65,38% în ultimele săptămâni ale gravidităţii. Cele mai frecvente complicaţii pulmonare la gravidele cu gripă pandemică au fost pneumonii virale, pneumonii bacteriene, leziune pulmonară acută /sindrom de detresa respiratorie acută, pneumotorace spontan, pneumomediastinum, pleurezie, regurgitare pasivă. Terapia intensivă efectuată a fost complexă şi multidirecţională, bazată pe principii generale şi speciale de tratament, unul din criteriile de baza fiind aplicarea unei terapii respiratorii bine conduita si începuta la momentul oportun. Rezolvare sarcinii în timp util este un factor important ce contribue la ameliorarea rezultatelor tratamentului intensiv la gravide cu complicaţii pulmonare ale Gripei Pandemice

Энтеробактерии продуцирующие бета-лактамазы расширенного спектра, выделенных при инфекциях мочевыводящих путей

National Centre of Public Health, Congresul III al Medicilor de Familie din Republica Moldova, 17–18 mai, 2012, Chişinău, Republica Moldova, Conferinţa Naţională „Maladii bronhoobstructive la copii”, consacrată profesorului universitar, doctor habilitat Victor Gheţeul, 27 aprilie, Chişinău, Republica MoldovaIntroducere. Antibioticorezistenţa microorganismelor, implicate în etiologia maladiilor infecţioase, reprezintă o prioritate pentru sistemul de sănătate publică atât la nivel naţional cât şi global. Infecţiile tractului urinar (ITU) reprezintă una dintre cele mai frecvente maladii infecţioase întâlnite la toate vârstele. Prin numărul mare al infecţiilor urinare, cu consecinţe medicale şi economice considerabile, tulpinile implicate în etiologia acestora se menţin în atenţia studiilor epidemiologice şi bacteriologice. Majoritatea infecţiilor urinare sunt cauzate de bacterii din familia Enterobacteriaceae, care reprezintă flora indigenă a tractului gastrointestinal. Cel mai frecvent germene, implicat în patologia ITU, este cu preponderenţă Escherichia coli. Utilizarea expansivă în ultimele două decenii a betalactaminelor a dus la apariţia tulpinilor secretoare de beta-lactamaze, la creşterea numerică a infecţiilor urinare şi la complicarea tabloului clinic. Presiunea de selecţie, exercitată de antibioticele betalactamice asupra unei populaţii bacteriene, favorizează persistenţa tulpinilor care au capacitatea de a rezista la acţiunea antibioticelor datorită enzimelor beta-lactamaze. Aceste populaţii bacteriene proliferează şi răspândesc genele de rezistenţă la alte tulpini iniţial sensibile, iar răspândirea rapidă a acestui tip de rezistenţă se datorează faptului că genele codante se găsesc pe plasmide transmisibile sau mobilizabile. Cele mai cunoscute variante de BLSE (beta-lactamaze cu spectru extins) sunt de tip TEM şi SHV, dar tot mai mult apar atât în comunitate, cât şi în spital BLSE tip CTX-M. Tipul exact de beta-lactamază nu poate fi detectat cu ajutorul testelor de rutină. Asocierea mai multor tipuri de beta-lactamaze la acelaşi microorganism face şi mai dificilă depistarea corectă. În ultimii ani, au fost propuse metode alternative care să înlocuiască sau să completeze metodele fenotipice tradiţionale. Cele mai utilizate dintre aceste metode sunt testele PCR şi secvenţierea de gene. Material şi metode Au fost cercetate 118 tulpini de E. coli, izolate din uroculturile semnificativ pozitive (105 UFC/ml), recoltate de la pacienţii cu ITU. Tulpinile au fost identificate pe baza proprietăţilor morfotinctoriale, culturale şi biochimice, utilizând teste API 20E (Biomerieux). Sensibilitatea tulpinilor de E. coli la preparatele antimicrobiene a fost determinată prin metode fenotipice (discdifuzimetrică Kirby-Bauer, testul de sinergie) şi de biologie moleculară (reacţia de polimerizare în lanţ: PCR multiplex, Rep – PCR, secvenţiere). Rezultate obţinute Rezultatele obţinute prin testele biochimice de screening şi de confirmare pentru Enterobacteriaceae, au pus în evidenţă faptul că din totalul de tulpini izolate de la pacienţii cu ITU, predominante au fost tulpinile de E. coli (92,9%). Determinarea antibioticogramei şi raportarea periodică a sensibilităţii diferitor bacterii la antibiotice constituie un obiectiv major în instituirea unei terapii de primă intenţie adecvată, şi în realizarea unei strategii de prevenire a rezistenţei la preparatele antibacteriene. Determinând şi evaluând sensibilitatea la antibiotice a tulpinilor de E. coli studiate, a fost semnalat fenomenul de multirezistenţă la preparatele antibacteriene. Ponderea tulpinilor rezistentela fluorochinolone (acid nalidixic) a constituit 89%, la betalactamine (ticarcilina) – 77%, aminoglicozide (gentamicina) – 72% şi sulfamide (cotrimoxazol) – 72%. Betalactamazele cu spectru extins (BLSE), identificate la tulpinile de E. coli, au fost de tip CTX-M, şi anume: o tulpină tip CTX-M-1, trei tulpini de tip CTX-M-14; alte trei tulpini sunt de tip CTX-M-15. S-a constatat că filogenetic 58,5% tulpini de E. coli BLSE aparţin grupului B2 , grupului A – 27,9%, grupului D – 12,7%, alte grupuri – 0,9%. Tipizarea tulpinilor de E. coli BLSE urinare a evidenţiat faptul că tulpinile de la diferiţi pacienţi au avut profiluri BLSE CTX-M similare. Majoritatea tulpinilor au fost de tipul BLSE-CTX-M-14, aparţinând grupului filogenetic B2 , cu excepţia a două tulpini: CTX-M-15 grup filogenetic B2 , şi CTX-M-3 grup filogenetic A. Concluzii 1. Prezenţa E. coli, producătoare de BLSE la pacienţii cu ITU, este datorată utilizării expansive a antibioticelor cu spectru larg, fiind una din cauzele principale care a generat scăderea sensibilităţii bacteriene, datorate achiziţionării unor mecanisme variate de realizare a rezistenţei printre care şi producerea de BLSE. 2. Stoparea răspândirii tulpinilor bacteriene multirezistente la acţiunea antibioticelor impune cunoaşterea detaliată a mecanismelor de rezistenţă bacteriană, în paralel cu dezvoltarea şi aplicarea unor politici intraspitaliceşti adecvate de antibioticoterapie

Fingerprints Indicating Superior Properties of Internal Interfaces in Cu(In,Ga)Se2 Thin-Film Solar Cells

Growth of Cu(In,Ga)Se2 (CIGS) absorbers under Cu-poor conditions gives rise to incorporation of numerous defects into the bulk, whereas the same absorber grown under Cu-rich conditions leads to a stoichiometric bulk with minimum defects. This suggests that CIGS absorbers grown under Cu-rich conditions are more suitable for solar cell applications. However, the CIGS solar cell devices with record efficiencies have all been fabricated under Cu-poor conditions, despite the expectations. Therefore, in the present work, both Cu-poor and Cu-rich CIGS cells are investigated, and the superior properties of the internal interfaces of the Cu-poor CIGS cells, such as the p-n junction and grain boundaries, which always makes them the record-efficiency devices, are shown. More precisely, by employing a correlative microscopy approach, the typical fingerprints for superior properties of internal interfaces necessary for maintaining a lower recombination activity in the cell is discovered. These are a Cu-depleted and Cd-enriched CIGS absorber surface, near the p-n junction, as well as a negative Cu factor (∆β) and high Na content (>1.5 at%) at the grain boundaries. Thus, this work provides key factors governing the device performance (efficiency), which can be considered in the design of next-generation solar cells

Острая диарея: проблемы и перспективы

Centrul Naţional Ştiinţifico-Practic de Medicină Preventivă, Chişinău, Conferinţa Ştiinţifico-Practică „Medicina modernă, actualităţi şi perspective”, consacrată aniversării de 40 de ani ai Spitalului Clinic al Ministerului Sănătăţii, 27-28 mai, 2010, Chişinău, Republica MoldovaIn order to determine etiologic factors of acute intestinal infections in the years 2007-2009, 7076 patients (adults and children) were examined for pathogenic flora (1518 patients), intestinal microflora (conditioned pathogenic; 5092 patients) and intestinal dismicrobism (466 patients). The study showed that acute diarrhea is caused by both pathogenic and conditioned pathogenic agents. Conditioned pathogenic agents may cause acute diarrhea in both microbial associations and as a single causative agent. Acute diarrhea can be caused by hemolylical microbial agents that need to be evaluated as pathogens. Diagnosis of “intestinal dismicrobism” can be considered as an intestinal syndrome only in cases when microbial agents are not detected in diagnosing titres.В целях определения этиологических факторов острых кишечных инфекций в 2007-2009 годах было обследовано 7076 пациентов (взрослых и детей), из них 1518 на патогенную флору, 5092 на кишечную микрофлору (условно патогенную) и 466 на кишечный дисмикробизм. Исследование показало, что острые диарейные заболевания обусловлены как патогенными, так и условно патогенными микроорганизмами. Условно патогенная флора вызывает острые диарейные заболевания, как при микробных ассоциациях, так и в случае выявления только одного возбудителя. Острая диарея может быть вызвана гемолитическими микробными агентами, которые должны быть оценены как патогенные организмы. Диагноз «кишечный дисмикробизм» может считаться кишечным синдромом только в тех случаях, когда патогенные микробы не обнаруживаются в диагностическом титре

The diversity and spread of genes encoding extended spectrum beta-lactamase enzymes in the strains of Escherichia coli

The aim of the study is to determine the mechanisms of antibiotic resistance of Escherichia coli (E. coli), the prevalence of extended spectrum betalactamase (ESBL) circulating strains of E. coli, establishing genotypes, phylogenetic groups of E. coli ESBL in the Republic of Moldova. On the basis of the data of local microbiological monitoring and using the phenotypic and molecular-genetic methods the genetic determinants (beta-lactamase), which cause the formation of resistance to beta-lactamase antibiotics have been identified. By polymerasis chaine reaction and the sequencing method the prevalence of E. coli strains producing ESBL in the urine probes has been identified. Such studies are unique for the Republic of Moldova and can serve as a basis for the establishment of the concept of causal and empirical treatment in our country. Urinary tract infections have been primarily (85%) determined by the E. coli species, followed by Enterococcus faecalis, Klebsiella pneumoniae, etc. The enzymes ESBL identified in the strains of E. coli in most of the cases have been of CTX-M type, the fact that explains the evolution and dissemination of E. coli producing ESBL. E. coli, a representative of the intestinal microflora, can serve as a reservoir of antibiotic resistance of microbic germs involved in the etiology of urinary tract infections. The detection of the type of beta-lactamase and the unification of the different subtypes of resistance to microorganisms are possible with the help of molecular biology techniques, by contrast with the phenotypic routine tests, the fact that is shown by the model of E. coli producing ESBL

Optimal microwave control pulse for nuclear spin polarization and readout in dense nitrogen-vacancy ensembles in diamond

Nitrogen-vacancy centers possessing nuclear spins are promising candidates for a novel nuclear spin gyroscope. Preparation of a nuclear spin state is a crucial step to implement a sensor that utilizes a nuclear spin. In a low magnetic field, such a preparation utilizes population transfer, from polarized electronic spin to nuclear spin, using microwave pulses. The use of the narrowband microwave pulse proposed earlier is inefficient when magnetic transitions are not well resolved, particularly when applied to diamond with a natural abundance of carbon atoms or dense ensembles of nitrogen-vacancy centers. In this study, the authors performed optimization of the pulse shape for 3 relatively easily accessible pulse shapes. The optimization was done for a range of magnetic transition linewidths, corresponding to the practically important range of nitrogen concentrations (5-50 ppm). It was found that, while at low nitrogen concentrations, optimized pulse added very little to simple square shape pulse, and in the case of dense nitrogen-vacancy ensembles, with a rather wide magnetic transition width of 1.5 MHz optimal pulses, a factor of 15% improvement in the population of the target state was observed

Discovering electron transfer driven changes in chemical bonding in lead chalcogenides (PbX, where X = Te, Se, S, O)

Understanding the nature of chemical bonding in solids is crucial to comprehend the physical and chemical properties of a given compound. To explore changes in chemical bonding in lead chalcogenides (PbX, where X = Te, Se, S, O), a combination of property-, bond breaking- and quantum-mechanical bonding descriptors have been applied. The outcome of our explorations reveals an electron transfer driven transition from metavalent bonding in PbX (X = Te, Se, S) to iono-covalent bonding in beta-PbO. Metavalent bonding is characterized by adjacent atoms being held together by sharing about a single electron and small electron transfer (ET). The transition from metavalent to iono-covalent bonding manifests itself in clear changes in these quantum-mechanical descriptors (ES and ET), as well as in property-based descriptors (i.e. Born effective charge, dielectric function, effective coordination number (ECON) and mode-specific Grueneisen parameter, and in bond breaking descriptors (PME). Metavalent bonding collapses, if significant charge localization occurs at the ion cores (ET) and/or in the interatomic region (ES). Predominantly changing the degree of electron transfer opens possibilities to tailor materials properties such as the chemical bond and electronic polarizability, optical band gap and optical interband transitions characterized by the imaginary part of the dielectric function. Hence, the insights gained from this study highlight the technological relevance of the concept of metavalent bonding and its potential for materials design

Frequency and impact of glutathione-S-transferase gene polymorphisms on lung function and bronchial asthma susceptibility in Moldovan children

Scientific Department of Pediatrics, Research Institute for Maternal and Child Health Care, Congresul III al Medicilor de Familie din Republica Moldova, 17–18 mai, 2012, Chişinău, Republica Moldova, Conferinţa Naţională „Maladii bronhoobstructive la copii”, consacrată profesorului universitar, doctor habilitat Victor Gheţeul, 27 aprilie, Chişinău, Republica MoldovaAsthma is a highly prevalent chronic inflammatory disease of the respiratory tract with genetic predisposition. However, the complex mechanisms of its inheritance, from the genetic predisposition of atopy to allergic diseases, are still not completely understood. Recent data suggest that the pathogenesis of atopic diseases is complex and might be caused by gene-gene and/or gene-environmental interactions. Polymorphisms of the glutathione-S-transferase (GST) genes are known risk factors for some environmentally related diseases. The aim of the present study was to investigate the frequency of polymorphisms in the GSTT1, GSTM1, GSTP1 and NAT2 genes in the population groups of healthy Moldovans and children with asthma, and to analyze their role on lung function. The studied population included 180 subjects – 90 children with asthma, aged 5 to 17 years (mean ± VEM age of 10,9 ± 0,4 years) and 90 healthy controls who showed no signs or history of allergic diseases (mean age 13,5 ± 0,2 years). The asthma group included 51 males and 39 females, who were randomly selected from asthmatic children referred by the Allergy Clinic of the Research Institute for Maternal and Child Healthcare, Chisinau, Moldova, during 2009-2010. Asthma was defined according to the criteria of the Global Initiative for Asthma (GINA). A complete clinical history, physical examination, and pulmonary function test (PFT) were performed for all the subjects in accordance with standards. Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were measured using a portable spirometer (Spirobank G, Mir, Italy). Genes coding for the xenobiotic-metabolizing enzymes (GSTT1, GSTM1, GSTP1 and NAT2) were evaluated by polymerase chain reaction (PCR). Analysis of the xenobiotic-metabolizing enzyme genes’ frequency in the studied population showed an equally distributed prevalence of GST genes genotypes in the patient group in comparison with the controls. However, the heterozygous genotype of the GSTP1 341 C>T Ala114Val polymorphism was found significantly more frequent in healthy subjects (14,4±9,7% in patients vs 26,7±9,0% in controls; χ2 = 3,4, gl = 1, p=0,06). The GSTM1 null genotype was overrepresented in asthmatic males in comparison with controls (54,9±9,4% vs 35,3±11,3%; χ2 = 3,21, gl=1, p=0,07). The GSTT1 null genotype was associated with a significant decrease in the FEV1/FVC% ratio when compared with the GSTT1 wild genotype (89,3±3,4 vs 95,8±1,3, respectively, p<0,05) and the homozygous GSTP1 Val105Val genotype was associated with the decrease of FEV1 (64,4±8,2 vs 87,3±2,5 in patients with GSTP1 Ile105/x genotypes, p<0,001) and the FEV1/FVC% ratio (82,6±5,7 vs 95,8±1,2 in patients with GSTP1 Ile105/x genotypes, p<0,01). However, there was no association between GSTM1 polymorphism and lung function tests. Our results suggest that GST gene polymorphisms may play an important role in asthma susceptibility in Moldovan children. Also GST gene polymorphisms may affect asthma pathogenesis as polymorphisms influence lung functioning in asthmatic children. These findings suggest a potentially raised susceptibility to negative environmental influences and predisposition to respiratory morbidity in this particular group