Vapour growth of silicon: growth anisotropy and adsorption

The development of facets on hemispherical single crystal substrates is investigated for growth in a near-equilibrium hot-wall CVD system, in order to study the orientation dependence of silicon crystal growth as a function of gas phase parameters in the Si-H-Cl system. It is found that only faces with indices {hhk} are stable. On the basis of their different behaviour as a function of experimental conditions, these faces are divided into {hhk}h k and {hhk}h < k faces. The {111} and {001} faces have to be considered separately. From the experimental dependencies it is concluded that the adsorption of chlorine and hydrogen plays a dominant yet ambivalent role: it stabilizes the {001} and the {hhk}h k faces, but destabilizes the {hhk}h < k faces. In order to explain these effects, it has to be assumed that under CVD conditions dimer-like reconstructions are present on all silicon faces. The interplay between surface dimer reconstructions and adsorption processes also shows up in the kinetic roughening of the different faces at high supersaturations. Theoretical calculations of the probabilities of adsorption of growth species on the different faces are used to explain the differences in kinetic roughening of these faces and the observed change in orientation of growth hillocks on the {111} faces which occurs when the supersaturation is increased

Farmer Technical Knowledge of Reproductive Technology and Training Interventions

This study contributes to the improvement of knowledge of farmers based on reproductive technology training interventions in terms of knowing that signs of lust, how to administer hormones to cause uniformity of lust or estrus or prostaglandin, and to know the exterior shape of productive female beef cattle. This study uses a pre-test and post-test model approach through training interventions. Also using mixed method research is a methodology that combines qualitative and quantitative methods. This method allows researchers to present qualitative studies through descriptive explanations and also quantitatively through numbers, tables, graphs, charts and statistical data. For the measurement scale to quantify qualitative data, the measurement scale is Likert 3 levels. The results show that training interventions can improve the knowledge or skills and expertise of beef cattle farmers in terms of reproductive technology and minimize the dependence of farmers on extension workers

Farmer Technical Knowledge of Reproductive Technology and Training Interventions

This study contributes to the improvement of knowledge of farmers based on reproductive technology training interventions in terms of knowing that signs of lust, how to administer hormones to cause uniformity of lust or estrus or prostaglandin, and to know the exterior shape of productive female beef cattle. This study uses a pre-test and post-test model approach through training interventions. Also using mixed method research is a methodology that combines qualitative and quantitative methods. This method allows researchers to present qualitative studies through descriptive explanations and also quantitatively through numbers, tables, graphs, charts and statistical data. For the measurement scale to quantify qualitative data, the measurement scale is Likert 3 levels. The results show that training interventions can improve the knowledge or skills and expertise of beef cattle farmers in terms of reproductive technology and minimize the dependence of farmers on extension workers

Delving deeper: metabolic processes in the metalimnion of stratified lakes

Many lakes exhibit seasonal stratification, during which they develop strong thermal and chemical gradients. An expansion of depth-integrated monitoring programs has provided insight into the importance of organic carbon processing that occurs below the upper mixed layer. However, the chemical and physical drivers of metabolism and metabolic coupling remain unresolved, especially in the metalimnion. In this depth zone, sharp gradients in key resources such as light and temperature co-occur with dynamic physical conditions that influence metabolic processes directly and simultaneously hamper the accurate tracing of biological activity. We evaluated the drivers of metalimnetic metabolism and its associated uncertainty across 10 stratified lakes in Europe and North America. We hypothesized that the metalimnion would contribute highly to whole-lake functioning in clear oligotrophic lakes, and that metabolic rates would be highly variable in unstable polymictic lakes. Depth-integrated rates of gross primary production (GPP) and ecosystem respiration (ER) were modelled from diel dissolved oxygen curves using a Bayesian approach. Metabolic estimates were more uncertain below the epilimnion, but uncertainty was not consistently related to lake morphology or mixing regime. Metalimnetic rates exhibited high day-to-day variability in all trophic states, with the metalimnetic contribution to daily whole-lake GPP and ER ranging from 0% to 87% and<1% to 92%, respectively. Nonetheless, the metalimnion of low-nutrient lakes contributed strongly to whole-lake metabolism on average, driven by a col- linear combination of highlight, low surface-water phosphorous concentration and high metalimnetic volume. Consequently, a single-sensor approach does not necessarily reflect whole-ecosystem carbon dynamics in stratified lakes

Analytical models for growth by metal organic vapor phase epitaxy. I.Isothermal models

For a proper description of growth by metal organic vapour phase epitaxy the three-dimensional Navier-Stokes partial differential equations need to be solved which govern the following series of processes: (i) transport by diffusion and flow through the gas phase, (ii) reactions which take place in this gas phase, (iii) reactions which take place at the surface. The authors are at first interested in the medium- and higher-temperature regions, which cover the growth determined by diffusion through the gas phase (medium temperature) and the growth that is determined by the desorption of growth species (higher temperature). Using a number of well justified assumptions one can reduce the problem to a two-dimensional one. For the diffusion-limited region (i.e. medium-temperature region) the effect of different flow profiles (plug flow, parabolic flow, linear increasing velocity and combination of plug and linear profile) on the growth rate has been studied under isothermal conditions. It was found that all profiles yield the same growth rate within a few per cent, so that it suffices to use the simple plug flow profile in growth rate calculations. It is also shown that axial diffusion is an important effect only at the end of long reactors. Finally a model is derived in which surface reaction kinetics is combined with the diffusion-limited model for the isothermal case

Plant litter diversity affects invertebrate shredder activity and the quality of fine particulate organic matter in streams

Draft. Published online 06 January 2015There is evidence that loss of riparian plant diversity alters the availability and quality of resources in streams, but little is known about how such effects change with time after loss of diversity. We used a microcosm approach with leaves of alder, oak and eucalypt previously colonised by microbes in a mixed forest stream to test how loss of litter diversity and time (2 and 6 months after loss of diversity) affect leaf consumption by invertebrate shredders, the elemental composition of shredder tissues, and the quality of fine particulate organic matter (FPOM). The number and identity of leaf species affected leaf consumption and FPOM production by shredders. Effects of leaf species diversity were positive and became more frequent with time after loss of diversity. Carbon (C) and nitrogen (N) composition of invertebrate tissues changed with the leaf identity. FPOM quality (C:N ratio) was positively correlated with leaf quality. Leaf consumption by the animals decreased linearly with the increase in C:N imbalance between leaf litter and invertebrate tissues. Our results suggest that changes in plant litter diversity affect the activity of shredders (leaf consumption and FPOM production), and the quality of food resources (FPOM and shredders) to higher trophic levels in streams; such effects are likely to become stronger with time after loss of plant diversity.The European Regional Development Fund – Operational Competitiveness Program (FEDER-POFC-COMPETE) and the Portuguese Foundation for Science and Technology (FCT) supported this study (PEst-OE/BIA/UI4050/2014, PTDC/AAC-AMB/117068/2010), I. Fernandes (SFRH/BD/42215/2007) and S. Duarte (SFRH/BPD/47574/2008

Social Capital and the Sustainability of Beef Cattle Partnership

The study aimed to describe the applicative aspects of social capital related to trust, reciprocity, and satisfaction to provide management solution for improving enterprise performance through strong collaboration between the entrepreneurs and the farmers in a partnership. This study employed quantitative study. The data were collected through questionnaire and interview to 30 respondents of beef cattle farmers involved in beef cattle partnership. This study was performed in one of the Indonesian regencies. There were three variables measured in this study including trust, reciprocity, and satisfaction level according to the theory designed by Robert Bruce Shaw. The results showed that the trust aspect was categorized as high, the reciprocity aspect was on the medium category, and the satisfaction was categorized as sufficiently satisfying. This study provided a recommendation for the core of the beef cattle partnership to improve the technical field aspects and proper service by employing expert staff as the consultants aiding beef cattle farmer in handling technical field issues. It was also necessary for all of the partnership elements to agree with the collective regulation within the partnership operation. By improving these aspects, the sustainable and profitable model of beef cattle partnership could be strongly maintained