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Defect passivation inside the crystal lattice and the grain‐boundary (GB) surface of the perovskite films has become the most effective strategy to suppress the negative impact of the nonradiative recombination in perovskite solar cell. In this study, a unique approach to effectively passivate the defect states of MAPbI3 perovskite thin film using thionicotinamide (TNM) as a multifunctional Lewis base additive is demonstrated. TNM as an additive with three different types of Lewis base sites, i.e., pyridine, amino, and CS functional groups, is introduced to mitigate the trap states in the TNM‐modified perovskite films and thoroughly investigate the passivation defects. The nonbonded electron of the three different Lewis base sites can synergistically passivate the antisite lead (Pb) defects and improve the stability of the device. In addition, the NH2 group can form ionic bonds with negatively charged I– ions and inhibit ion migration caused by them. It is found that such passivation effect of TNM reduces the GB defects and improves the crystallinity significantly. As a result, a champion TNM‐modified device shows an improved power conversion efficiency of 19.26% from 16.86% along with enhanced open‐circuit voltage, fill factor, and negligible hysteresis. [ABSTRACT FROM AUTHOR]

State‐of‐the‐art photoelectrodes in highly efficient photoelectrochemical (PEC) systems often comprise multilayer architectures where lattice mismatch‐imposed strain at the interfaces can perturb the material's crystalline lattice and electronic structure. Despite its inevitable presence, understanding of strain effects in semiconductor photoelectrodes is lacking, preventing rational exploitation of strain engineering to improve photoelectrode performance. In this work, we combine X‐ray structural characterization with strain tensor decomposition analysis as well as optical/photocurrent spectroscopic methods to demonstrate how volumetric lattice deformations caused by substrate‐imposed hydrostatic strain impact the optoelectronic and PEC properties of BiVO4. Utilizing single‐crystalline, epitaxial BiVO4/indium tin oxide (ITO)/yttrium‐stabilized zirconia (YSZx, x = 8% and 13% mol Y2O3) photoelectrodes as a model platform, we find that tensile hydrostatic strain that causes volumetric lattice dilation in BiVO4 results in slightly enhanced optical absorption, but it is detrimental to the internal quantum efficiencies in BiVO4. We attribute this to localization of photogenerated charge carriers, thereby leading to poor charge separation in the bulk of BiVO4 and increased recombination losses. Finally, we highlight the beneficial effects of compressive hydrostatic strain on enhancing the internal quantum efficiencies in BiVO4. Our results provide a basis for exploiting epitaxial strain engineering to optimize the performance of multilayer photoelectrodes in PEC systems. [ABSTRACT FROM AUTHOR]

Knowledge regarding the temperature dependence of the surface recombination at the interface between silicon and various dielectrics is critically important as it 1) provides fundamental information regarding the interfaces and 2) improves the modeling of solar cell performance under actual operating conditions. Herein, the temperature‐ and carrier‐dependent surface recombination at the silicon–oxide/silicon and aluminum–oxide/silicon interfaces in the temperature range of 25−90 °C using an advanced technique is investigated. This method enables to control the surface carrier population from heavy accumulation to heavy inversion via an external bias voltage, allowing for the decoupling of the bulk and surface contributions to the effective lifetime. Thus, it offers a simple and versatile manner to separate the chemical passivation from the charge‐assisted population control at the silicon/dielectric interface. A model is established to obtain the temperature dependence of the capture cross sections, a critical capability for the optimization of the dielectric layers and the investigation of the fundamental properties of the passivation under field operating conditions. [ABSTRACT FROM AUTHOR]

Bias‐assisted charge extraction (BACE) is a powerful technique for measuring the carrier density in organic solar cells under operational conditions and to deduce information on the charge recombination properties. Hereby, the carrier density in the active layer device is determined by integrating the transient extraction current, while nongeminate recombination during the charge extraction processes is generally neglected. This assumption becomes questionable for low mobilities, for example, at low temperatures and in case of high energetic disorder. Herein, the extraction process in BACE measurement is investigated by incorporating both drift and bimolecular recombination of charges during charge extraction into a unified framework. An explicit analytical model is proposed to describe the time dependence of the transient photocurrent in BACE measurement and excellent agreement is found with drift‐diffusion simulations. It is shown that global fitting of transient photocurrents measured at various collection biases with this analytical model allows to determine the carrier density in the device with high accuracy. Furthermore, the analytical model is demonstrated to provide accurate mobilities for both the fast and slow carriers within the device, rendering it a valuable supplement to other mobility measurement techniques such as resistance‐dependent photovoltage and space–charge‐limited current. [ABSTRACT FROM AUTHOR]

State‐of‐the‐art photoelectrodes in highly efficient photoelectrochemical (PEC) systems often comprise multilayer architectures where lattice mismatch‐imposed strain at the interfaces can perturb the material's crystalline lattice and electronic structure. Despite its inevitable presence, understanding of strain effects in semiconductor photoelectrodes is lacking, preventing rational exploitation of strain engineering to improve photoelectrode performance. In this work, we combine X‐ray structural characterization with strain tensor decomposition analysis as well as optical/photocurrent spectroscopic methods to demonstrate how volumetric lattice deformations caused by substrate‐imposed hydrostatic strain impact the optoelectronic and PEC properties of BiVO4. Utilizing single‐crystalline, epitaxial BiVO4/indium tin oxide (ITO)/yttrium‐stabilized zirconia (YSZx, x = 8% and 13% mol Y2O3) photoelectrodes as a model platform, we find that tensile hydrostatic strain that causes volumetric lattice dilation in BiVO4 results in slightly enhanced optical absorption, but it is detrimental to the internal quantum efficiencies in BiVO4. We attribute this to localization of photogenerated charge carriers, thereby leading to poor charge separation in the bulk of BiVO4 and increased recombination losses. Finally, we highlight the beneficial effects of compressive hydrostatic strain on enhancing the internal quantum efficiencies in BiVO4. Our results provide a basis for exploiting epitaxial strain engineering to optimize the performance of multilayer photoelectrodes in PEC systems.

Animal husbandry is one of the main agricultural industries in most countries over the world as well as in the Russian Federation, and its profitability is determined by three main factors: the animal genetic potential, complete diet and freedom from infectious, invasive and mass non-infectious diseases. One of the most significant and difficult tasks is to generate and rear healthy young cattle. Digestive disorders clinically manifested by diarrhea resulting in apparent dehydration, toxemia, enophthalmos, membrane pathology, immunodeficiency and metabolic disorders are prevalent among neonatal calf diseases in early postnatal period. Massive diarrhea in neonatal calves is characterized by significant polymorphism, involving a wide range of various factors including genetic, physiological, sanitary and hygienic as well as infectious factors. Infectious agents are the main causes of massive gastroenteritis in neonatal calves. In most cases viruses serve as triggers for gastrointestinal pathology development and bacteria play the secondary role. For a long time, rotaviruses, coronaviruses and pestiviruses have been believed to play the main role in etiology of massive neonatal calf diarrhea. In recent years, a number of new and understudied viruses, including kobuvirus, nebovirus, norovirus, torovirus and astrovirus, have been detected in fecal samples from diarrheic calves and their role in diarrhea development has not been definitively determined. Their role as primary pathogens, coinfection agents or commensals remains unclear. Recently these animal pathogens have widely spread in different countries of the world. At the end of the XX century – beginning of the XXI century, large numbers of cattle were imported to the Russian Federation, including cattle from the nebovirus-infected countries. Data on nebovirus infection (occurrence, pathogen characteristics, disease clinical signs and epizootological features) are given in the paper.

As a kind new photovoltaic material, antimony sulfide–selenide (Sb2(S,Se)3) thin films have been considered a promising low‐cost solar cell absorption layer material due to their excellent photoelectric performance and stability. Continued research and development efforts have significantly increased the power conversion efficiency of Sb2(S,Se)3 solar cells over the past few years, which now exceeds 10%. High device performance requires efficient carrier collection and transport. A deeper understanding of the carrier‐transport process can guide the optimization of solar cell designs and materials. Herein, the factors affecting carrier transport combined with the crystal structure in Sb2(S,Se)3 solar cells are discussed. Recent advances in carrier management strategies to overcome the recombination losses are also discussed, broadly categorized into two main approaches: regulation of the absorption layer and optimization of the device interface contacts. Furthermore, the possible future research directions of Sb2(S,Se)3 solar cells are prospected. [ABSTRACT FROM AUTHOR]

To investigate the molecular epidemiological characteristics and genetic variations of human adenovirus (HAdV) in acute respiratory tract infections in Beijing. Whole‐genome sequencing and phylogenetic analyses were performed for 83 strains of HAdV with different types in Beijing from 2014 to 2019. The clinical characteristics of HAdV infection were analyzed statistically. HAdV‐B was divided into four genotypes, including B3 (n = 11), B7 (n = 13), B14 (n = 4), and B55 (n = 2). HAdV‐C was divided into three genotypes, including C1 (n = 14), C2 (n = 13), and C5 (n = 10). In HAdV‐C, nine recombinant adenovirus strains were identified in type 1, and seven recombinant strains were found in type 2. In type 1, we found three newly emerged intraspecific recombinant strains (A47, A48, and A52) collected in 2017, 2018, and 2019, respectively. In addition, the previously reported recombinant strains of HAdV‐C1 showed more severe disease than other strains of HAdV‐C, causing severe community‐acquired pneumonia in both the elderly and children. Continuous population‐wide molecular epidemiological surveillance of HAdV is essential for the prevention and control of respiratory infectious diseases. [ABSTRACT FROM AUTHOR]

The analysis of the photoluminescence of polar light emitting diode (LED) structures with a 25 nm In0.17Ga0.83N quantum well is reported. The observed emission most likely originates from a set of energetically close excited states (ES), while the ground state decays only extremely slowly on a μs‐to‐ms timescale, that is, long‐living charge accumulates there. However, this population can also be quantified spectroscopically by applying short reverse voltage pulses. The emission from ES is effective and nearly exponential with decay time constants of 1.5 and 8 ns at 6 and 300 K, respectively, and is likely dominated by radiative processes. These findings point to a possible route to improved polar device architectures. [ABSTRACT FROM AUTHOR]

The small perturbation frequency‐resolved techniques have been powerful tools in unraveling the kinetic processes governing the operation of perovskite solar cells (PSCs). One such technique is electrochemical impedance spectroscopy (EIS). However, a thorough interpretation of the EIS response of PSCs is still lacking owing to the absence of a uniform electrical equivalent circuit. In this context, intensity‐modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) can be the link between the optical and electrical responses of PSCs and complement the IS technique. In this review, the progress made in interpreting the IMPS/IMVS response of various types of PSCs is summarized and diverse prospects are discussed. First, the basic theory and models present in the literature are discussed. Next, the IMPS/IMVS response of mesoporous and planar PSCs based on various physical parameters is discussed. At last, proposed future prospects for the development of this field are discussed. [ABSTRACT FROM AUTHOR]

Improving efficiency and stability has become an urgent issue in the application of perovskite solar cells (PSCs). Herein, a kind of long‐chain polymer or polymethylmethacrylate (PMMA) is added into the spiro‐OMeTAD matrix to improve the film formation process and hence the device performance. It is observed that, after modification, the spiro‐OMeTAD‐based hole‐transporting layer becomes uniform, continuous, and condensed. Meanwhile, the power conversion efficiency of the devices is upgraded. Compared with the control device, open‐circuit voltage of the modified one (with moderate doping) increases from 1.06 (±0.03) to 1.10 (±0.02) V, fill factor increases from 72.20 (±3.44)% to 75.59 (±3.35)%, and the power conversion efficiency increases from 18.82 (±1.06)% to 20.51 (±0.82)% (highest at 21.78%) under standard test condition (AM 1.5G, 100 mW cm−2). Transient photocurrent/photovoltage decay curves, time‐resolved photoluminance, and impedance spectroscopy studies show that the modification could accelerate charge transfer and retard interfacial recombination. In addition, the modification improves device stability. Due to the strengthened barrier against penetration of "H2O/O2/Ag," the efficiency of the unsealed device could retain 91.49% (by average) of the initial one after 100 days storage in the dark [relative humidity = 30(±5)%]. This work shows that long‐chain polymer doping could simultaneously improve efficiency and stability of spiro‐OMeTAD‐based PSCs. [ABSTRACT FROM AUTHOR]

A bandgap gradient at the front surface of solar absorbers can effectively suppress surface recombination while not affecting photocurrent. Herein, it is demonstrated that a front‐surface gradient can be formed in an inverted perovskite cell by introducing perovskite quantum dots (QDs) between the hole‐transporting layer (HTL) and the remaining absorber. Ultraviolet photoelectron spectroscopy reveals that, with the addition of CsPbBr3 QDs onto the HTL substrate, the subsequently deposited MAPbI3 is converted from mild p‐type to n‐type, and the resultant band alignment can effectively reduce the electron concentration at the front surface without significantly affecting hole extraction. Multiple independent characterizations further confirm the reduction of surface recombination. As a result, the inverted MAPbI3 cells exhibit an open‐circuit voltage of 1.154 V, which translates to a nonradiative recombination loss of 0.15 V and a power conversion efficiency of 20.51%. [ABSTRACT FROM AUTHOR]

Objective of the study: To explain the characteristics and dynamics of resources and recombinations associated with developing products with low and high novelty. Methodology/Approach: The method was an integrative review of the literature on recombinant innovation. It included a creative synthesis that resulted in a theoretical model. Originality/Relevance: The research addresses topics the literature neglects, like explaining which resources and recombinations and why could relate to high or low product novelty. Main results: Certain features of resources (i.e., heterogeneity, specificity, accessibility) with high and low levels may differently influence costs, variety, and frequency of recombinations and, in turn, product novelty. To develop highly novel products, tangible resources, and internally produced new resources may be essential, as knowledge by itself may not be sufficient. Theoretical contributions: Different resource characteristics and their influence on recombinations may help explain whether a product will have low or high novelty. By going beyond the novel recombinations, the research expands the literature's understanding of recombinations and product novelty. Managerial contributions: Companies could assess ex ante which degree of product novelty besides types and costs of recombinations would result from their pools of resources. This assessment would make innovation more efficient for companies with fewer resources, like may occur in emerging markets. [ABSTRACT FROM AUTHOR]

Begomoviruses (the Geminiviridae family) is observed to infect valuable economic yield including medicinal plants. In the last two decades, the issue of begomoviruses has been compounded by the proliferation of various variants of viruses due to recombination and genome mutations, the introduction of susceptible plant varieties, as well as changes in climatic conditions. The latest research work on Begomoviruses impacting medicinal plants has been focused in this study. [ABSTRACT FROM AUTHOR]

Here, we performed a comparative genomic analysis of all available genomes of E. faecalis (n = 1591) and E. faecium (n = 1981) and investigated the association between the presence or absence of CRISPR-Cas systems, endonuclease/anti-endonuclease systems and the acquisition of antimicrobial resistance, especially vancomycin resistance genes. Most of the analysed Enterococci were isolated from humans and less than 14% of them were from foods and animals. We analysed and detected CRISPR–Cas systems in 75.36% of E. faecalis genomes and only 4.89% of E. faecium genomes with a significant difference (p-value < 10−5). We found a negative correlation between the number of CRISPR–Cas systems and genome size (r = −0.397, p-value < 10−5) and a positive correlation between the genome %GC content and the number of CRISPR–Cas systems (r = 0.215, p-value < 10−5). Our findings showed that the presence of the anti-endonuclease ardA gene may explain the decrease in the number of CRISPR–Cas systems in E. faecium, known to deactivate the endonucleases’ protective activities and enable the E. faecium genome to be versatile in acquiring mobile genetic elements, including carriers of antimicrobial resistance genes, especially vanB. Most importantly, we observed that there was a direct association between the absence of CRISPR–Cas, the presence of the anti-CRISPR ardA gene and the acquisition of vancomycin resistance genes.

Silicon solar cells with non-uniform and heavily doped emitter region have been investigated. The results show that non-uniform doped solar cells have significantly higher conversion efficiency as compared to the uniformly-doped Si-solar cells. These results were obtained from simulation with the PC1D software. By introducing non-uniform doping profile in the emitter region of a Si solar cell, better performance parameters like improved current-voltage characteristics and higher quantum efficiency was achieved. However, a number of non-ideal effects have been also observed as the doping level increased from certain level. This results into dead layer formation at the front surface of emitter region. The recombinations become significant in which Auger recombination especially reduce lifetime, carrier mobility and tend to decrease the efficiency of solar cell. From the simulations results optimum surface doping level of 1019cm-³ and 1017 cm-3 have been achieved for emitter and base regions, respectively. [ABSTRACT FROM AUTHOR]

Background: A biotooth is defined as a complete living tooth, made in laboratory cultures from a spontaneous interplay between epithelial and mesenchymal cell‐based frontal systems. A good solution to these problems is to use induced pluripotent stem cells (iPSCs). However, no one has yet formulated culture conditions that effectively differentiate iPSCs into dental epithelial and dental mesenchymal cells phenotypes analogous to those present in tooth development. Results: Here, we tried to induce differentiation methods for dental epithelial cells (DEC) and dental mesenchymal cells from iPSCs. For the DEC differentiation, the conditional media of SF2 DEC was adjusted to embryoid body. Moreover, we now report on a new cultivation protocol, supported by transwell membrane cell culture that make it possible to differentiate iPSCs into dental epithelial and mesenchymal cells with abilities to initiate the first stages in de novo tooth formation. Conclusions: Implementation of technical modifications to the protocol that maximize the number and rate of iPSC differentiation, into mesenchymal and epithelial cell layers, will be the next step toward growing an anatomically accurate biomimetic tooth organ. Developmental Dynamics 248:129–139, 2019. © 2018 Wiley Periodicals, Inc. Key Findings: Differentiation methods for dental epithelial cells from iPSCs.Differentiation methods for dental mesenchymal cells from iPSCs.A new cultivation protocol, supported by transwell membrane cell culture to differentiate iPSCs into dental epithelial and mesenchymal cells. [ABSTRACT FROM AUTHOR]

Abstract: Significant work has been directed at measuring the exciton diffusion length (LD) in organic semiconductors due to its significance in determining the performance of photovoltaic cells. Several techniques have been developed to measure LD, often probing photoluminescence or charge carrier generation. Interestingly, in this study it is shown that when different techniques are compared, both the diffusive behavior of the exciton and active carrier recombination loss pathways can be decoupled. Here, a planar heterojunction device based on the donor–acceptor pairing of boron subphthalocyanine chloride‐C60 is examined using photoluminescence quenching, photovoltage‐, and photocurrent‐based LD measurement techniques. Photovoltage yields the device relevant LD of both active materials as a function of forward bias subject to geminate recombination losses. These values are used to accurately predict the photocurrent as a function of voltage, suggesting geminate recombination is the dominant mechanism responsible for photocurrent loss. By combining these measurements with photocurrent and photoluminescence quenching, the intrinsic LD, as well as the voltage‐dependent charge transfer state dissociation and charge collection efficiencies are quantitatively determined. The results of this work provide a method to decouple all relevant loss pathways during photoconversion, and establish the factors that can limit the performance of excitonic photovoltaic cells. [ABSTRACT FROM AUTHOR]

Mutations include the changes of the inherited material and they occur naturally, but very rarely. This paper presents the spontaneous and induced mutations, their frequency of occurrence and applicability for the needs of plant production in forestry. The initial material includes the trees and shrubs of Serbia, and the methods are the comparative morpho-physiological analysis, ionising radiation and chemical half-sib tests Spontaneous mutations in our country have been recorded more frequently since the sixties and the study of intra-variability of trees and shrubs in Serbia has been intensified. They include the changes of growth habit, character of increment, abnormalities in the structure of vegetative and generative organs. By selection and vegetative propagation, numerous ornamental tree and shrub varieties have been synthesised over a more or less long period. After the discovery of the vigour of triploid mutants trees, their mass production has been elaborated: by crossing triploid and diploid trees By the treatment of the reproductive material by ionising radiation (UV, gamma rays, terminal neutrons), and chemical materials, the frequency of mutations increased drastically, especially with higher doses up to 100% in the treated organisms. The mutants have, as a rule, reduced growth elements, reduced adaptation, and when selected and propagated vegetatively, they ensure a rich initial material for the synthesis of numerous ornamental cultivars of trees and shrubs. The method of radiation breeding is the most promising for the improvement of ornamental plants, while mass production of triploid mutants is the only method used in the improvement of forest trees.

Despite the apparent success of silicon technology, further development of the modern electronics industry will heavily depend on the development of new materials interfaces, in particular, gallium arsenide (semiconductor structures based on compounds AIIIBV). Some characteristics of devices made from these materials have great advantages (e.g. high-speed performance and compatibility with light and laser diodes), but the technology of forming the structures is very sensitive to the properties of the semiconductor interface. These interface properties at the atomic level can determine the types of the microelectronic and optoelectronic devices and circuitry based on them, which can be made on the basis of such semiconductor materials. Electrical properties are one of the most important aspects of the interface. Electrical characteristics of the interface are defined by the relative placement of electronic levels on both sides of the interface, the electronic states at the interface itself and the interface behavior under the action of the applied voltage, current and temperature. For example, in the metal-semiconductor contact systems (MSC) the position of the Fermi level in metal towards the edge of the conduction band and valence band of the semiconductor is an important parameter that determines the height of the Schottky barrier and the volt-ampere characteristic (VAC). At the same time, for the ohmic contacts the voltage loss at the metalsemiconductor interface at high-level current injection must be very small. [ABSTRACT FROM AUTHOR]

Pedigrees are directed acyclic graphs that represent ancestral relationships between individuals in a population. Based on a schematic recombination process, we describe two simple Markov models for sequences evolving on pedigrees-Model R (recombinations without mutations) and Model RM (recombinations with mutations). For these models, we ask an identifiability question: is it possible to construct a pedigree from the joint probability distribution of extant sequences? We present partial identifiability results for general pedigrees: we show that when the crossover probabilities are sufficiently small, certain spanning subgraph sequences can be counted from the joint distribution of extant sequences. We demonstrate how pedigrees that earlier seemed difficult to distinguish are distinguished by counting their spanning subgraph sequences. [ABSTRACT FROM AUTHOR]

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Abstract: In this paper, we present a study on cadmium selenide (CdSe) quantum-dot-sensitized solar cells (QDSSCs) in terms of the evaluation of carrier transport and recombinations using intensity-modulated photovoltage spectroscopy (IMVS) and intensity-modulated photocurrent spectroscopy (IMPS). Using the obtained data through this evaluation, we calculated the electron transport time (τ sc ), electron recombination lifetimes (τ oc ), effective diffusion constants (D eff ), and diffusion lengths (L n ). The QDSSC used in this study show improved fill factors (FF) of ∼60% with a polysulfide (S2−/S x 2−) redox mediator and Pt counter electrode. This result is ascribed to the low series resistances (R s ) of QDSSC that are accessed by electrochemical impedance spectroscopy. In addition, the present study provides information on the sensitization mode of CdSe QDs on TiO2 electrodes, achieved by scanning transmission electron microscopy (STEM) combined with EDS imaging. [Copyright &y& Elsevier]

The HLA-related hemochromatosis mutation C282Y is thought to have originated in Ireland in a person with HLA-A3-B14 and was spread by Vikings. Irish people with two HLA-A3 alleles had a high risk of hemochromatosis. In this study, from west Sweden, we wanted to test these hypotheses. HFE mutations in controls, bone marrow donors with HLA-A3/A3 and patients with hemochromatosis. HLA haplotypes, extended haplotype analysis and pedigree studies. The allelic C282Y frequency 0.04, (CI 0.01-0.07) was lower ( P < 0.001) in Sweden than in Ireland 0.10 (CI 0.08-0.11), and Swedish bone marrow donors with HLA-A3/A3 ( n = 77) had a low risk of hemochromatosis. HLA haplotypes available from 239/262 (91.5%) proband patients homozygous for C282Y showed a dominance of A3-B7 and A3-B14 both in linkage disequilibrium with controls ( P < 0.001). Pedigree studies extended into the 17th century supported a local founder effect of A3-B14 in the county of Bohuslän. The A3-B14 haplotype may well be the original and A3-B7 the result of centromeric recombinations. The haplotype diversity and recombination events were not different from a Celtic series. These findings do not support the hypothesis of the C282Y mutation being of an Irish Celtic origin. Conclusions: The C282Y frequency shows a west to east decline from Ireland through the north of Europe. Vikings may have been involved in the spread of C282Y, but the mutation is probably older and may have been spread in Europe by earlier seafarers. [ABSTRACT FROM AUTHOR]

Background: The haemochromatosis mutation C282Y occurred once in a person who lived in Ireland or Scandinavia and carried either human leucocyte antigen (HLA)-A3-B7 or A3-B14. With time, recombinations are believed to have taken place introducing new HLA haplotypes. This evolution is mainly unknown. In this study, we tried to find a founder, possible recombination events and effect on the phenotype in descendants. Setting: A Swedish mountain population close to Norway, n = 3529, population density <1/km2. Methods: Retrospective genealogy study of HLA haplotypes followed by extended haplotype studies. Results: There were 34 probands (22 men, 12 women) where 31 (91%) shared a common founder origin 12 generations ago. The A3-B14 haplotype was the most common, 39%, in strong linkage disequilibrium ( P < 0.0005) with controls, followed by A3-B7, 20% ( P < 0.005), probably resulting from a centromeric recombination replacing the B14 allele with the common B7. Possible telomeric recombinations took place close to HLA-A and introduced the haplotypes AW19-B7 ( n = 4), AW19-B27 (2), A1-B17 (5) and A2-B12 (4) supported by pedigree studies. Male homozygotes with two copies of HLA-A3 had significantly ( P 0.001) higher mean serum ferritin values than those with one, and liver damage (fibrosis and cirrhosis) was also more common ( P < 0.001) than in a population with a recombinant (A1-B8) haplotype. Conclusions: A3-B14 may well be the ancestral haplotype with A3B7, the result of centromeric recombinations introducing the common B7 allele. Telomeric recombinations were more common than expected. The ancestral HLA-A3 haplotype may be associated with a more severe phenotypic expression. [ABSTRACT FROM AUTHOR]

Abstract: Inter-individual gene copy-number variations (CNVs) probably afford human populations the flexibility to respond to a variety of environmental challenges, but also lead to differential disease predispositions. We investigated gene CNVs for complement component C4 and steroid 21-hydroxylase from the RP-C4-CYP21-TNX (RCCX) modules located in the major histocompatibility complex among healthy Asian-Indian Americans (AIA) and compared them to European Americans. A combination of definitive techniques that yielded cross-confirmatory results was used. The medium gene copy-numbers for C4 and its isotypes, acidic C4A and basic C4B, were 4, 2 and 2, respectively, but their frequencies were only 53–56%. The distribution patterns for total C4 and C4A are skewed towards the high copy-number side. For example, the frequency of AIA-subjects with three copies of C4A (30.7%) was 3.92-fold of those with a single copy (7.83%). The monomodular-short haplotype with a single C4B gene and the absence of C4A, which is in linkage-disequilibrium with HLA DRB1*0301 in Europeans and a strong risk factor for autoimmune diseases, has a frequency of 0.012 in AIA but 0.106 among healthy European Americans (p =6.6×10−8). The copy-number and the size of C4 genes strongly determine the plasma C4 protein concentrations. Parallel variations in copy-numbers of CYP21A (CYP21A1P) and TNXA with total C4 were also observed. Notably, 13.1% of AIA-subjects had three copies of the functional CYP21B, which were likely generated by recombinations between monomodular and bimodular RCCX haplotypes. The high copy-numbers of C4 and the high frequency of RCCX recombinants offer important insights to the prevalence of autoimmune and genetic diseases. [Copyright &y& Elsevier]

Begomoviruses are plant pathogens that caused important losses to crops of economic interest in tropical and subtropical regions in the last decade. In Cuba, nine begomoviruses have been identified affecting tomato, beans, tobacco, pepper, squash, potato and weeds of different botanical families. The intergenic sequence (IR) and the N-terminal regions of the replication associated protein (Rep) of begomoviruses identified in Cuba were analysed using sequence data of gene collections (GeneBank). Statistical programs were used for the alignments, phylogenetic analysis and searching of significant recombination fragments. The detection of possible recombination events was carried out for p=0.05, based on 10000 permutations. Eleven IR recombination event sites between Macroptilium Yellow Mosaic Virus (MaYMV) and Tobacco Leaf Rugose Virus (TLRV), and 15 between Tomato Mottle Taino Virus (TMoTV) and Dicliptera Yellow Mosaic Virus (DiYMoV) were found. Sixteen recombination event sites between MaYMV and Sida Golden Yellow Vein Virus (SiGYVV) were also found in the Rep region. Jatropha Mosaic Virus (JMV) from Jatropha gossipifolia and Tomato Yellow Leaf Curl Virus TYLCV-IL(CU) from tomato and pepper showed base sequences in the alignments that were present in all the polymorphic sites detected and homologous to monomorphic sites. TMoTV and DiYMoV showed 3 and 4 polymorphic sites in the Rep N-terminal region, respectively. All these sites constitute evidences of old recombination events destroyed during the evolution, and they may define the characteristics of the begomovirus species identified. [ABSTRACT FROM AUTHOR]

Abstract: It is known that in the three-dimensional structure of a protein, certain amino acids can interact with each other in order to provide structural integrity or aid in its catalytic function. If these positions are mutated the loss of this interaction usually leads to a non-functional protein. Directed evolution experiments, which probe the sequence space of a protein through mutations in search for an improved variant, frequently result in such inactive sequences. In this work, we address the use of machine learning algorithms, Boolean learning and support vector machines (SVMs), to find such pairs of amino acid positions. The recombination method of imparting mutations was simulated to create in silico sequences that were used as training data for the algorithms. The two algorithms were combined together to develop an approach that weighs the structural risk as well as the empirical risk to solve the problem. This strategy was adapted to a multi-round framework of experiments where the data generated in the present round is used to design experiments for the next round to improve the generated library, as well as the estimation of the interacting positions. It is observed that this strategy can greatly improve the number of functional variants that are generated as well as the average number of mutations that can be made in the library. [Copyright &y& Elsevier]

Expressing two genes in the progeny of stem and progenitor cells that are transduced with a unique viral vector is desirable in certain situations. We tested the ability of two lentiviral vectors to transduce human cells of hematopoietic origin and concomitantly express two reporter genes, either EGFP (enhanced green fluorescent protein) and DsRed2 , or EGFP and EYFP (enhanced yellow fluorescent protein), from two internal promoters. The vectors were generated from the pTRIP deltaU3 EF1alpha EGFP lentiviral vector. Following transduction of hematopoietic and non-hematopoietic cell lines, we performed FACS, PCR and Southern blot analyzes to quantify transduction, integration efficiencies and size of integrated lentiviral vectors, respectively. The detection of DsRed2 fluorescence appeared unexpectedly low in human cells of hematopoietic origin. Alternatively, a modification in the flow cytometry assay allowed us to distinguish between the two overlapping fluorescence signals emitted by EGFP and EYFP, when transduced cells were excited with a 488-nm laser beam. However, the low frequency of double-positive EGFP + EYFP + cells, and the existence of single-positive, mostly EGFP - EYFP + , cells, prompted us to search for recombinations in the vector sequence. Southern blotting of DNA obtained from transduced cells indeed demonstrated that recombination had occurred between the two closely related EGFP and EYFP sequences. These observations suggest that recombination occurred within the EGFP and EYFP genes, which differ by only four amino acids. We conclude that the insertion of two highly homologous sequences into a lentiviral backbone can favor recombination. [ABSTRACT FROM AUTHOR]

This study determines the effects of a water disinfection by-product, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (also known as mutagen X or MX) and chlorinated tap water on genomic instability in the yeast Saccharomyces cerevisiae. Tap water samples collected from Cherepovets (Russia) and Boston (MA, USA), were extracted using XAD absorption and ethyl acetate elution. MX and these water extracts were then tested for their ability to induce intrachromosomal recombination (deletions or DEL events), interchromosomal recombination (ICR) and aneuploidy (ANEU) using the yeast DEL assay. MX strongly induced DEL, ICR and ANEU events with a positive dose response and no threshold. Cherepovets tap water induced DEL and ICR events while evidence of ANEU induction was weak. The DEL induction potencies were stronger at higher concentrations. The estimated contribution of MX to DEL induction varied from over 50% at low concentrations (which is comparable to a typical contribution of MX to Ames mutagenicity of tap water) to between 2 and 10% at highest concentrations. For Boston tap water, there was only weak evidence of DEL induction and no evidence of ICR and ANEU induction. This is consistent with the results of other studies, which reported much higher concentrations of MX and stronger Ames mutagenicity in Cherepovets tap water than in Boston tap water. [Copyright &y& Elsevier]

Nanocrystalline films of cadmium sulfide sensitized with ruthenium N3 dye show only a feeble photoresponse either in the absorption region of the dye or the band gap excitation of cadmium sulfide. However, when an ultrathin outer shell of magnesium oxide is deposited on the cadmium sulfide crystallites in the film, the photoresponse in both the above regions of the spectrum are greatly enhanced. The result is explained as electron injection from excited dye molecules on the outer magnesium oxide shell to the conduction band of cadmium sulfide and suppression of the leakage of the relaxed electrons to the interface by the magnesium oxide barrier, where they undergo recombinations. Possible applications of this effect in dye-sensitized solar cells are discussed. [Copyright &y& Elsevier]

Thin-film samples have been prepared by evaporating a commercial fullerene C powder from a tungsten crucible, at a pressure of 10 Pa on to quartz or Corning glass substrates. Samples were equipped with coplanar Cr-Au electrodes evaporated onto the surface of the film. Dark-conductivity measurements in the range 300-600 K evidence the existence of hysteresis phenomena. Thermal annealing influences photoconductivity and changes the power coefficient in the power law illumination-intensity dependence of photoconductivity. The influence of oxygen adsorbed in the film matrix on the electrical properties and on the density of states is discussed. A tentative for explaining the photoconductivity-light-intensity dependence has been done assuming a continuous density-of-state distribution in the energy gap of the semiconductor. [ABSTRACT FROM AUTHOR]

Autotetraploids were established from 8 diploid wild species of section Arachis. In all the autotetraploids the chromosomes paired largely as bivalents even though they possess the ability to pair as multivalents. Pollen and pod fertility in the C generation were not directly associated with chromosome pairing. The C generation autotetraploids showed a gradual increase in bivalent associations and pollen and pod fertility. The identification of two genomes, A and B, in the diploid species and in the tetraploid, A. hypogaea, of the section Arachis, a fairly good crossability, and the type of chromosome associations observed in hybrids between A. hypogaea and the autotetraploids of wild Arachis species indicated good prospects of utilizing autotetraploids as genetic bridges in transferring desired traits from these taxa into groundnut. [ABSTRACT FROM AUTHOR]

Se realizó una revisión de los conceptos más importantes relacionados con la evolución de los virus ARN. Los virus con genoma ARN son los parásitos intracelulares más abundantes en la biosfera. Además se resumió el estado actual de conocimientos sobre la estructura de las cuasiespecies virales y sus implicaciones biológicas, lo que permitirá a todos los profesionales, relacionados de una forma u otra con las enfermedades infecciosas, comprender mejor la adaptabilidad de los virus, su poder patogénico y de persistencia, así como el diseño actual y futuro de estrategia para la prevención y el control de las enfermedades que ocasionan.A review of the most important concepts related to the evolution of the RNA virus was made. The viruses with RNA genome are the most abundant intracellular parasites in the biosphere. The current state of the knowledge about the structure of the viral quasispecies and their biological implications was also summarized, allowing all the professionals connected in one way or another with the infectious diseases to understand better the adaptability of the viruses, their pathogenic and persistence power, as well as the present and future design of the strategy for the prevention and control of the diseases they cause.

An improved formulation of the frequency-dependent impedance for p-i-n diodes from physical and geometrical parameters is presented. This work is addressed to diode designers and allows them to evaluate quickly and accurately the diode impedance. It comes in parallel with existing SPICE p-i-n diode model used in CAD software. Under forward bias conditions, important recombinations occur in the heavily doped end regions of thin p-i-n diodes that seriously affects the diode impedance. This effect is taken into account to increase the accuracy of existing numerical models and to extend their validity domain to any I-region thicknesses. This improvement has been validated by measurement results on a 5-mum I-region width silicon p-i-n diode [ABSTRACT FROM PUBLISHER]

Here, we performed a comparative genomic analysis of all available genomes of E. faecalis ( n = 1591) and E. faecium ( n = 1981) and investigated the association between the presence or absence of CRISPR-Cas systems, endonuclease/anti-endonuclease systems and the acquisition of antimicrobial resistance, especially vancomycin resistance genes. Most of the analysed Enterococci were isolated from humans and less than 14% of them were from foods and animals. We analysed and detected CRISPR-Cas systems in 75.36% of E. faecalis genomes and only 4.89% of E. faecium genomes with a significant difference ( p -value < 10 -5 ). We found a negative correlation between the number of CRISPR-Cas systems and genome size (r = -0.397, p -value < 10 -5 ) and a positive correlation between the genome %GC content and the number of CRISPR-Cas systems (r = 0.215, p -value < 10 -5 ). Our findings showed that the presence of the anti-endonuclease ardA gene may explain the decrease in the number of CRISPR-Cas systems in E. faecium , known to deactivate the endonucleases' protective activities and enable the E. faecium genome to be versatile in acquiring mobile genetic elements, including carriers of antimicrobial resistance genes, especially vanB . Most importantly, we observed that there was a direct association between the absence of CRISPR-Cas, the presence of the anti-CRISPR ardA gene and the acquisition of vancomycin resistance genes.