Reproductive behavior and health in consanguineous marriages

In many regions of Asia and Africa, consanguineous marriages currently account for approximately 20 to 50% of all unions, and preliminary observations indicate that migrants from these areas continue to contract marriages with close relatives when resident in North America and Western Europe. Consanguinity is associated with increased gross fertility, due at least in part to younger maternal age at first livebirth. Morbidity and mortality also may be elevated, resulting in comparable numbers of surviving offspring in consanguineous and nonconsanguineous families. With advances in medicine and public health, genetic disorders will account for an increased proportion of disease worldwide. Predictably, this burden will fall more heavily on countries and communities in which consanguinity is strongly favored, as the result of the expression of deleterious recessive genes. However, studies conducted in such populations indicate that the adverse effects associated with inbreeding are experienced by a minority of families.

Nature of chemistry in the national frame curricula for upper secondary education in Finland, Norway and Sweden

The aim of this study was to discover how current chemistry syllabi in the frame curricula for up- per secondary education in three Nordic countries (Finland, Norway, and Sweden) take into account topics related to the nature of chemistry. By qualitative content analysis, the statements related to the nature of chemistry were divided into categories. Conclusions and implications for improving the frame curricula under study were made by comparing results with research into the nature of science. Chemistry syllabi from the Nordic frame curricula analyzed take into account the aims related to the nature of chemistry in a very similar manner. The ideas that should be made more explicit in all of the analyzed curricula are: i) the limits of the chemical models and theories, ii) the relationship between chemistry and other natural sciences, iii) the importance of creativity in chemical research, iv) the concepts of evidence in science texts, v) the social nature of chemical research, and vi) chemistry as a technological practice.

Molecular and serological studies on the recent seal virus epizootics in Europe and Siberia

The virus epizootics which occurred in seals in both Europe and Siberia during 1987/1988 were caused by two different morbillivirus, referred to as phocid distemper virus (PDV) 1 and 2, respectively. Molecular and serological studies have shown that the European virus is quite distinct from canine distemper virus (CDV), its closest relative in the morbillivirus group. Analysis of tissues obtained from infected seals from a wide geographical distrubution over Northern Europe showed that the infectious agent (PDV 1) was identical in all cases. Nucleotide sequence analysis of one of the virus genes suggested that this virus has evolved away from CDV over a long time period and is most probably an enzootic virus of marine mammals. In contrast, the virus (PDV 2) which caused the deaths of many Siberian seals was indistinguishable, both serologically and at the molecular level, from CDV and must have originated from a land source.

Giant magnetoresistance in transition metal oxides

Some materials exhibit large changes in electrical resistance in the presence of a magnetic field, and this change can be used in applications from sensor technology to magnetic data storage. In their Perspective, Rao and Cheetham discuss magnetoresistance in perovskite manganates, where the effect is unusually strong. Much has been learned about these materials, and this understanding is driving the search for new materials with even more impressive properties.

Scaling analysis of momentum and heat transport in gas tungsten arc weld pools

A systematic procedure is outlined for scaling analysis of momentum and heat transfer in gas tungsten arc weld pools. With suitable selections of non-dimentionalised parameters, the governing equations coupled with appropriate boundary conditions are first scaled, and the relative significance of various terms appearing in them is analysed accordingly. The analysis is then used to predict the orders of magnitude of some important quantities, such as the velocity scene lit the top surface, velocity boundary layer thickness, maximum temperature increase in the pool, and time required for initiation of melting. Some of the quantities predicted from the scaling analysis can also be used for optimised selection of appropriate grid size and time steps for full numerical simulation of the process. The scaling predictions are finally assessed by comparison with numerical results quoted in the literature, and a good qualitative agreement is observed.

Multi-physics self-consistent modeling in nanotechnological applications: quantum dots and quantum-well lasers

This paper reports a self-consistent Poisson-Schr¨odinger scheme including the effects of the piezoelectricity, the spontaneous polarization and the charge density on the electronic states and the quasi-Fermi level energy in wurtzite type semiconductor heterojunction and quantum-laser.

Anomalous X-ray scattering study of local structures in the superionic conducting glass (AgBr)0.4 (Ag2O)0.3 (GeO2)0.3

The local structural information in the near-neighbor region of superionic conducting glass (AgBr)0.4(Ag2O)0.3(GeO2)0.3 has been estimated from the anomalous X-ray scattering (AXS) measurements using Ge and Br K absorption edges. The possible atomic arrangements in the near-neighbor region of this glass were obtained by coupling the results with the least-squares variational method so as to reproduce two differential intensity profiles for Ge and Br as well as the ordinary scattering profile. The coordination number of oxygen around Ge is found to be 3.6 at a distance of 0.176 nm, suggesting the GeO4 tetrahedral unit as the probable structural entity in this glass. Moreover, the coordination number of Ag around Br is estimated as 6.3 at a distance of 0.284 nm, suggesting an arrangement similar to that in crystalline AgBr.

Phenylboronic acids in crystal engineering: Utility of the energetically unfavorable syn,syn-conformation in co-crystal design

Phenylboronic acids can exist, in principle, in three different conformers (syn,syn; syn,anti and anti,anti) with distinct energy profiles. In their native state, these compounds prefer the energetically favored syn, anti-conformation. In molecular complexes, however, the functionality exhibits conformational diversity. In this paper we report a series of co-crystals, with N-donor compounds, prepared by a design strategy involving the synthons based on the syn, syn-conformation of the boronic acid functionality. For this purpose, we employed compounds with the 1,2-diazo fragment (alprazolam, 1H-tetrazole, acetazolamide and benzotriazole), 1,10-phenanthroline and 2,2'-bipyridine for the co-crystallization experiments. However, our study shows that the mere presence of the 1,2-diazo fragment in the coformer does not guarantee the successful formation of co-crystals with a syn, syn-conformation of the boronic acid. [GRAPHICS] The -B(OH)(2) fragment makes unsymmetrical O-H center dot center dot center dot N heterosynthons with alprazolam (ALP) and 1,10-phenanthroline (PHEN). In the co-crystals of phenylboronic acids with 1H-tetrazole (TETR) and 2,2'-bipyridine (BPY), the symmetrical boronic acid dimer is the major synthon. In the BPY complex, boronic acid forms linear chains and the pyridine compound interacts with the lateral OH of boronic acid dimers that acts as a connector, thus forming a ladder structure. In the TETR complex, each heterocycle interacts with three boronic acids. While two boronic acids interact using the phenolic group, the third molecule generates O-H center dot center dot center dot N hydrogen bonds using the extra OH group, of -B(OH)(2) fragment, left after the dimer formation. Thus, although molecules were selected retrosynthetically with the 1,2-diazo fragment or with nearby hetero-atoms to induce co-crystal formation using the syn,syn-orientation of the -B(OH)(2) functionality, co-crystal formation is in fact selective and is probably driven by energy factors. Acetazolamide (ACET) contains self-complementary functional groups and hence creates stable homosynthons. Phenylboronic acids being weak competitors fail to perturb the homosynthons and hence the components crystallize separately. Therefore, besides the availability of possible hydrogen bond acceptors in the required position and orientation, the ability of the phenyl-boronic acid to perturb the existing interactions is also a prerequisite to form co-crystals. This is illustrated in the table below. In the case of ALP, PHEN and BPY, the native structures are stabilized by weak interactions and may be influenced by the boronic acid fragment. Thus phenylboronic acids can attain co-crystals with those compounds, wherein the cyclic O-H center dot center dot center dot N hydrogen bonds are stronger than the individual homo-interactions. This can lower the lattice energy of the molecular complex as compared with the individual crystals. [GRAPHICS] Phenylboronic acids show some selectivity in the formation of co-crystals with N-heterocycles. The differences in solubility of the components fall short to provide a possible reason for the selective formation of co-crystals only with certain compounds. These compounds, being weak acids, do not follow the Delta pK(a) analysis and hence fail to provide any conclusive observation. Theoretical results show that of the three conformers possible, the syn,anti conformer is the most stable. The relative stabilities of the three conformers syn,anti,syn,syn and anti,anti are 0.0, 2.18 and 3.14 kcal/mol, respectively. The theoretical calculations corroborate the fact that only energetically favorable synthons can induce the formation of heterosynthons, as in ALP and PHEN complexes. From a theoretical and structural analysis it is seen that phenylboronic acids will form interactions with those molecules wherein the heterocyclic and acidic fragments can interrupt the homosynthons. However, the energy profile is shallow and can be perturbed easily by the presence of competing functional groups (such as OH and COOH) in the vicinity. [GRAPHICS] .

Recent advances in auto exhaust catalysis

In last 30 years innovative research in the area of auto exhaust catalysis is being developed and CeO2 has been found to play a major role in this area due to its unique redox properties. In this review, auto exhaust emission and its impact on earth’s environment, global concern and recent advances in science and technology in automotive exhaust catalysis have been documented. A new preparative method of dispersing metal ions by solution combustion technique over CeO2 and TiO2 resulting mainly Ce1−xMxO2−δ, Ti1−xMxO2−δ and Ce1−x−yTixMyO2−δ (M = Pd, Rh and Pt) catalysts, structure of these materials, their catalytic properties towards auto exhaust catalysis, structure–property relation and mechanism of catalytic reactions are accounted here. In these materials, metal ions are incorporated into substrate matrix to a certain limit in the solid solution form and we have established a new direction in heterogeneous catalysis by turning to the concept of dispersed metal ions as catalytically active sites from the conventionally nurtured idea of metal particles as active centers for catalysis.

Predatory Fish Select for Coordinated Collective Motion in Virtual Prey

Movement in animal groups is highly varied and ranges from seemingly disordered motion in swarms to coordinated aligned motion in flocks and schools. These social interactions are often thought to reduce risk from predators, despite a lack of direct evidence. We investigated risk-related selection for collective motion by allowing real predators ( bluegill sunfish) to hunt mobile virtual prey. By fusing simulated and real animal behavior, we isolated predator effects while controlling for confounding factors. Prey with a tendency to be attracted toward, and to align direction of travel with, near neighbors tended to form mobile coordinated groups and were rarely attacked. These results demonstrate that collective motion could evolve as a response to predation, without prey being able to detect and respond to predators.

Interstitial Defects Induced Ferroelectricity in Undoped ZnO Nanorods at Room Temperature

A simple approach for obtaining room temperature ferroelectricity in ZnO rod structures at the nanoscale is reported. A systematic comparative study between two kinds of nanorods prepared by different processes reveals the physics behind it. It is observed that ZnO nanorods grown (in-situ) by a sol gel method on platinum substrate show ferroelectric behaviour. On the contrary, ZnO nanorods first grown by a sol gel method and then spin-coated on a platinum substrate (ex-situ) do not demonstrate this kind of feature. X-ray diffraction analysis confirms partially (002) and (100) plane oriented growth of both samples. From photoluminescence (PL) spectral analysis it is interpreted that oxygen vacancies/zinc interstitial defects, which arises from the large lattice mismatch between the Pt substrate and the ZnO nanorods grown thereon, and preferential ZnO growth along 002], can be causes of this type of phenomena. C-V characterization, P-E hysteresis loop along with piezoelectric force microscopy support this observation.

Missing (in-situ) snow cover data hampers climate change and runoff studies in the Greater Himalayas

The Himalayas are presently holding the largest ice masses outside the polar regions and thus (temporarily) store important freshwater resources. In contrast to the contemplation of glaciers, the role of runoff from snow cover has received comparably little attention in the past, although (i) its contribution is thought to be at least equally or even more important than that of ice melt in many Himalayan catchments and (ii) climate change is expected to have widespread and significant consequences on snowmelt runoff. Here, we show that change assessment of snowmelt runoff and its timing is not as straightforward as often postulated, mainly as larger partial pressure of H2O, CO2, CH4, and other greenhouse gases might increase net long-wave input for snowmelt quite significantly in a future atmosphere. In addition, changes in the short-wave energy balance such as the pollution of the snow cover through black carbon or the sensible or latent heat contribution to snowmelt are likely to alter future snowmelt and runoff characteristics as well. For the assessment of snow cover extent and depletion, but also for its monitoring over the extremely large areas of the Himalayas, remote sensing has been used in the past and is likely to become even more important in the future. However, for the calibration and validation of remotely-sensed data, and even-more so in light of possible changes in snow-cover energy balance, we strongly call for more in-situ measurements across the Himalayas, in particular for daily data on new snow and snow cover water equivalent, or the respective energy balance components. Moreover, data should be made accessible to the scientific community, so that the latter can more accurately estimate climate change impacts on Himalayan snow cover and possible consequences thereof on runoff. (C) 2013 Elsevier B.V. All rights reserved.

Impact of compost, vermicompost and biochar on soil fertility, maize yield and soil erosion in Northern Vietnam: A three year mesocosm experiment

Compost, vermicompost and biochar amendments are thought to improve soil quality and plant yield. However, little is known about their long-term impact on crop yield and the environment in tropical agro-ecosystems. In this study we investigated the effect of organic amendments (buffalo manure, compost and verrnicompost) and biochar (applied alone or with vermicompost) on plant yield, soil fertility, soil erosion and water dynamics in a degraded Acrisol in Vietnam. Maize growth and yield, as well as weed growth, were examined for three years in terrestrial mesocosms under natural rainfall. Maize yield and growth showed high inter-annual variability depending on the organic amendment. Vermicompost improved maize growth and yield but its effect was rather small and was only significant when water availability was limited (year 2). This suggests that vermicompost could be a promising substrate for improving the resistance of agrosystems to water stress. When the vermicompost biochar mixture was applied, further growth and yield improvements were recorded in some cases. When applied alone, biochar had a positive influence on maize yield and growth, thus confirming its interest for improving long-term soil productivity. All organic amendments reduced water runoff, soil detachment and NH4+ and NO3- transfer to water. These effects were more significant with vermicompost than with buffalo manure and compost, highlighting that the beneficial influence of vermicompost is not limited to its influence on plant yield. In addition, this study showed for the first time that the combination of vermicompost and biochar may not only improve plant productivity but also reduce the negative impact of agriculture on water quality. (C) 2015 Elsevier B.V. All rights reserved.