High-Performance Dye-Sensitized Solar Cells Based on Morphology-Controllable Synthesis of ZnO–ZnS Heterostructure Nanocone Photoanodes

High-density and well-aligned ZnO–ZnS core–shell nanocone arrays were synthesized on fluorine-doped tin oxide glass substrate using a facile and cost-effective two-step approach. In this synthetic process, the ZnO nanocones act as the template and provide Zn²⁺ ions for the ZnS shell formation. The photoluminescence spectrum indicates remarkably enhanced luminescence intensity and a small redshift in the UV region, which can be associated with the strain caused by the lattice mismatch between ZnO and ZnS. The obtained diffuse reflectance spectra show that the nanocone-based heterostructure reduces the light reflection in a broad spectral range and is much more effective than the bare ZnO nanocone and nanorod structures. Dye-sensitized solar cells based on the heterostructure ZnO–ZnS nanocones are assembled, and high conversion efficiency (η) of approximately 4.07% is obtained. The η improvement can be attributed primarily to the morphology effect of ZnO nanocones on light-trapping and effectively passivating the interface surface recombination sites of ZnO nanocones by coating with a ZnS shell layer.     

Detection of Hepatitis E Virus Antibodies in Dogs in the United Kingdom

Hepatitis E virus (HEV) genotypes 3 and 4 are zoonotic pathogens, with pigs predominantly implicated in disease transmission. The rapid rise in human cases in developed countries over the past decade indicates a change in epidemiology of HEV, and it has been suggested that additional animal species may be involved in transmission of infection. Multiple studies have identified contact with dogs as a risk factor for HEV infection in industrialised nations, and a low seroprevalence to HEV has previously been reported in dogs in low-income countries. In this study we aimed to evaluate the possibility that dogs are susceptible to HEV, and determine the frequency with which this occurs. Serum samples from UK dogs with and without hepatitis were screened for HEV-specific antibodies, and canine liver and stool samples were analysed by qPCR for the presence of HEV RNA. We describe evidence to show HEV infection occurs at low levels in dogs in the UK, but the strain of origin is undetermined. The low seroprevalence level of HEV in dogs implies the risk of zoonotic disease transmission is likely to be limited, but further investigations will be required to determine if HEV-infected dogs can transmit HEV to man.     

Functional analysis of the venom of mealybug parasitoid Aenasius bambawalei (Hymenoptera: Encyrtidae)

Aenasius bambawalei (Hymenoptera: Encyrtidae) is a koinobiont nymphal endoparasitoid of cotton mealybug, Phenacoccus solenopsis (Hemiptera: Pseudocccidae). Functional analysis of the venom of the wasp was performed by artificial microinjections of both crude and treated venom (heat and proteinase) of the wasp containing 0.3 and 0.5 μl in non-parasitized and synchronized adult hosts (mealybugs) and the mortality data were recorded 24, 48, 72 and 96 hours post injecton while mealybugs receiving saline injections were acted as control. The main effects for artificially envenomated mealybugs were observed on their mortality and survival. The biological activity of crude venom was also evaluated by heat and protease treatment. Here, we demonstrate that maximum mortality (82 ± 2.0%) was achieved by microinjections containing higher volume (0.5 μl) of crude venom while lower mortality (68 ± 4.0%) was achieved with lower volume of venom (0.3 μl). On the other hand, heat and proteinase K treated venom did not show any significant effect on mortality of the host insect. Our findings suggest that bioactive components of the crude venom are proteins which lost their activity upon heat and protease treatment. This basic information regarding the functional role of the venom of A. bambawalei serves as a starting point for comprehensive analysis of the role of the venom of the parasitoid on the regulation processes in its host.     

Biology and demography of Glyphodes pyloalis Walker (Lepidoptera: Pyralidae) on mulberry

Lesser mulberry pyralid, Glyphodes pyloalis Walker, is a monophagous pest of mulberry and has recently been reported in northern Iran. The biology and life table of this pest were studied in controlled conditions (24 ± 1 °C, 75 ± 5% RH and 16:8 LD). Mortality rate, metamorphosis, appearance of adult insects and adult sex ratio were recorded daily. Data were analyzed based on an age-stage, two-sex life table. Developmental rate among individuals and between sexes were also considered. The developmental periods for the egg, first through fifth instar larvae, prepupae and pupae were 4.06 ± 0.03, 2.93 ± 0.03, 2.03 ± 0.02, 2.01 ± 0.01, 2.10 ± 0.03, 4.09 ± 0.03, 2.04 ± 0.02 and 9.7 ± 0.09 days, respectively. The mean total developmental period from egg to adult was 35.40 ± 0.37 days. The maximum adult longevity was 7 and 11 days for males and females, respectively. The pre-oviposition period lasted 2.14 ± 0.04 days. Laboratory observation showed that adults are nocturnal and female lay eggs at night. The intrinsic rate of increase (r_m) and the finite rate of increase (λ) were 0.14 ± 0.005 d^? 1 and 1.15 ± 0.01 d^? 1. The net reproductive rate (R₀), gross reproductive rate (GRR) and mean generation time (T) were 134.67 ± 20.6 female offspring, 294.71 ± 4.07 eggs/female and 34.44 ± 0.2 days, respectively. Life expectancy of freshly laid egg was 32.15 days.     

Critical biophysical properties in the Pseudomonas aeruginosa efflux gene regulator MexR are targeted by mutations conferring multidrug resistance

The self‐assembling MexA‐MexB‐OprM efflux pump system, encoded by the mexO operon, contributes to facile resistance of Pseudomonas aeruginosa by actively extruding multiple antimicrobials. MexR negatively regulates the mexO operon, comprising two adjacent MexR binding sites, and is as such highly targeted by mutations that confer multidrug resistance (MDR). To understand how MDR mutations impair MexR function, we studied MexR‐wt as well as a selected set of MDR single mutants distant from the proposed DNA‐binding helix. Although DNA affinity and MexA‐MexB‐OprM repression were both drastically impaired in the selected MexR‐MDR mutants, MexR‐wt bound its two binding sites in the mexO with high affinity as a dimer. In the MexR‐MDR mutants, secondary structure content and oligomerization properties were very similar to MexR‐wt despite their lack of DNA binding. Despite this, the MexR‐MDR mutants showed highly varying stabilities compared with MexR‐wt, suggesting disturbed critical interdomain contacts, because mutations in the DNA‐binding domains affected the stability of the dimer region and vice versa. Furthermore, significant ANS binding to MexR‐wt in both free and DNA‐bound states, together with increased ANS binding in all studied mutants, suggest that a hydrophobic cavity in the dimer region already shown to be involved in regulatory binding is enlarged by MDR mutations. Taken together, we propose that the biophysical MexR properties that are targeted by MDR mutations—stability, domain interactions, and internal hydrophobic surfaces—are also critical for the regulation of MexR DNA binding.     

Phylodynamics and human-mediated dispersal of a zoonotic virus

Understanding the role of humans in the dispersal of predominantly animal pathogens is essential for their control. We used newly developed Bayesian phylogeographic methods to unravel the dynamics and determinants of the spread of dog rabies virus (RABV) in North Africa. Each of the countries studied exhibited largely disconnected spatial dynamics with major geopolitical boundaries acting as barriers to gene flow. Road distances proved to be better predictors of the movement of dog RABV than accessibility or raw geographical distance, with occasional long distance and rapid spread within each of these countries. Using simulations that bridge phylodynamics and spatial epidemiology, we demonstrate that the contemporary viral distribution extends beyond that expected for RABV transmission in African dog populations. These results are strongly supportive of human-mediated dispersal, and demonstrate how an integrated phylogeographic approach will turn viral genetic data into a powerful asset for characterizing, predicting, and potentially controlling the spatial spread of pathogens.     

Redundant role of DEAD box proteins p68 (Ddx5) and p72/p82 (Ddx17) in ribosome biogenesis and cell proliferation

The DEAD box proteins encoded by the genes ddx5 (p68) and ddx17 (isoforms p72 and p82) are more closely related to each other than to any other member of their family. We found that p68 negatively controls p72/p82 gene expression but not vice versa. Knocking down of either gene does not affect cell proliferation, in case of p68 suppression, however, only on condition that p72/p82 overexpression was granted. In contrast, co-silencing of both genes causes perturbation of nucleolar structure and cell death. In mutant studies, the apparently redundant role(s) of p68 and p72/p82 correspond to their ability to catalyze RNA rearrangement rather than RNA unwinding reactions. In search for possible physiological targets of this RNA rearrangement activity it is shown that the nucleolytic cleavage of 32S pre-rRNA is reduced after p68 subfamily knock-down, most probably due to a failure in the structural rearrangement process within the pre-60S ribosomal subunit preceding the processing of 32S pre-rRNA.     

Phylogeographical patterns in Coenosia attenuata (Diptera: Muscidae): a widespread predator of insect species associated with greenhouse crops

The tiger‐fly Coenosia attenuata is a globally widespread predatory fly which is not only associated with greenhouse crops, but also occurs in open fields. It is a potential control agent against some of the more common pests in these crops. Assessing the genetic structure and gene flow patterns may be important for planning crop protection strategies and for understanding the historical processes that led to the present distribution of genetic lineages within this species. In the present study, the phylogeographical patterns of this species, based on mitochondrial cytochrome oxidase I and nuclear white and elongation factor‐1α genes, are described, revealing relatively low genetic diversity and weak genetic structure associated with a recent and sudden population expansion of the species. The geographical distribution of mitochondrial haplotypes indicates the Mediterranean as the most likely region of origin of the species. Some dispersal patterns of the species are also revaled, including at least three independent colonizations of North and South America: one from Middle East to North America with a strong bottleneck event, another from Europe to South America (Chile), with both likely to be a result of unintentional introduction, and a third one of still undetermined origin to South America (Ecuador). © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 308–326.     

Toward "strong" green nanocomposites: polyvinyl alcohol reinforced with extremely oriented cellulose whiskers

To exploit the maximum potential of cellulose whiskers (CWs), we report here for the first time the successful fabrication of nanocomposites reinforced with highly oriented CWs in a polymer matrix. The nanocomposites were prepared using polyvinyl alcohol (PVA) and a colloidal suspension of cotton-derived CWs. The macroscopically homogeneous PVA-CW suspensions were extruded into cold methanol to form gel fibers followed by a hot drawing. Compared to the neat PVA fiber, the as-spun fiber containing a small amount of CWs (5 wt % of solid PVA) showed higher drawability, leading to an extremely high orientation of CWs with the matrix PVA. The stress-transfer mechanism, a prime determining factor for high mechanical properties of nanocomposites, was studied by X-ray diffraction. The stress on the incorporated CWs was monitored by applying an in situ nondestructive load to the composite fibers. The applied stress to the whole sample was found to be effectively transferred to the CWs inside the composites, suggesting strong interfacial bonding between the filler and the matrix. Effective stress transfer to the oriented whiskers resulted in outstanding enhancement in mechanical properties of the nanocomposites.