Fabrication of ultrahigh-density nanowires by electrochemical nanolithography

An approach has been developed to produce silver nanoparticles (AgNPs) rapidly on semiconductor wafers using electrochemical deposition. The closely packed AgNPs have a density of up to 1.4 × 1011 cm-2 with good size uniformity. AgNPs retain their shape and position on the substrate when used as nanomasks for producing ultrahigh-density vertical nanowire arrays with controllable size, making it a one-step nanolithography technique. We demonstrate this method on Si/SiGe multilayer superlattices using electrochemical nanopatterning and plasma etching to obtain high-density Si/SiGe multilayer superlattice nanowires

The influence of X-factor (trunk rotation) and experience on the quality of the badminton forehand smash

Sherpa Romeo green journal. Open access article. Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License 9CC BY-NC-ND 3.0) appliesNo existing studies of badminton technique have used full-body biomechanical modeling based on three dimensional (3D) motion capture to quantify the kinematics of the sport. The purposes of the current study were to: 1) quantitatively describe kinematic characteristics of the forehand smash using a 15-segment, full-body biomechanical model, 2) examine and compare kinematic differences between novice and skilled players with a focus on trunk rotation (the X-factor), and 3) through this comparison, identify principal parameters that contributed to the quality of the skill. Together, these findings have the potential to assist coaches and players in the teaching and learning of the forehand smash. Twenty-four participants were divided into two groups (novice, n = 10 and skilled, n = 14). A 10-camera VICON MX40 motion capture system (200 frames/s) was used to quantify full-body kinematics, racket movement and the flight of the shuttlecock. Results confirmed that skilled players utilized more trunk rotation than novices. In two ways, trunk rotation (the X-factor) was shown to be vital for maximizing the release speed of the shuttlecock – an important measure of the quality of the forehand smash. First, more trunk rotation invoked greater lengthening in the pectoralis major (PM) during the preparation phase of the stroke which helped generate an explosive muscle contraction. Second, larger range of motion (ROM) induced by trunk rotation facilitated a whip-like (proximal to distal) control sequence among the body segments responsible for increasing racket speed. These results suggest that training intended to increase the efficacy of this skill needs to focus on how the X-factor is incorporated into the kinematic chain of the arm and the racket.Ye

Revealing silicon crystal defects by conductive atomic force microscope

The machining and polishing of silicon can damage its surface. Therefore, the investigation of the electric performance of the processed surface is of paramount importance for understanding and improving the utilization of silicon components with nanoscale crystal defects. In this study, conductivity of nanoscratches on the silicon surface was investigated using a conductive atomic force microscope. Compared to the original silicon surface (without any treatment), electrical breakover at low bias voltage could be detected on the mechanically scratched area of the silicon surface with crystal defects, and the current increased with the voltage. In contrast, no obvious current was found on the defect-free scratch created by tribochemical removal. The conductivity could also be observed on a friction-induced protrusive hillock created at high speed but not on a hillock created at low speed that is constructed by amorphous silicon. Further analysis showed that lattice distortions could facilitate easy electron flow and contributed significantly to the conductivity of a mechanical scratch on the silicon surface; however, the amorphous layer hardly contributed to the conductivity, which was also supported by high resolution transmission electron microscope analysis. As a result, the relationship between the electrical performance and microstructures was experimentally established. These findings shed new light on the subtle mechanism of defectdependent conductivity and also provide a rapid and nondestructive method for detecting surface defects

Effect of Functional Oligosaccharides and Ordinary Dietary Fiber on Intestinal Microbiota Diversity

Functional oligosaccharides, known as prebiotics, and ordinary dietary fiber have important roles in modulating the structure of intestinal microbiota. To investigate their effects on the intestinal microecosystem, three kinds of diets containing different prebiotics were used to feed mice for 3 weeks, as follows: GI (galacto-oligosaccharides and inulin), PF (polydextrose and insoluble dietary fiber from bran), and a GI/PF mixture (GI and PF, 1:1), 16S rRNA gene sequencing and metabolic analysis of mice feces were then conducted. Compared to the control group, the different prebiotics diets had varying effects on the structure and diversity of intestinal microbiota. GI and PF supplementation led to significant changes in intestinal microbiota, including an increase of Bacteroides and a decrease of Alloprevotella in the GI-fed, but those changes were opposite in PF fed group. Intriguing, in the GI/PF mixture-fed group, intestinal microbiota had the similar structure as the control groups, and flora diversity was upregulated. Fecal metabolic profiling showed that the diversity of intestinal microbiota was helpful in maintaining the stability of fecal metabolites. Our results showed that a single type of oligosaccharides or dietary fiber caused the reduction of bacteria species, and selectively promoted the growth of Bacteroides or Alloprevotella bacteria, resulting in an increase in diamine oxidase (DAO) and/or trimethylamine N-oxide (TMAO) values which was detrimental to health. However, the flora diversity was improved and the DAO values was significantly decreased when the addition of nutritionally balanced GI/PF mixture. Thus, we suggested that maintaining microbiota diversity and the abundance of dominant bacteria in the intestine is extremely important for the health, and that the addition of a combination of oligosaccharides and dietary fiber helps maintain the health of the intestinal microecosystem

Establishment of a novel experimental system for studying the photoperiodic response of short-day dicots using soybean ‘cotyledon-only plant’ as material

Soybean is an important model crop for photoperiodic response studies in plants and contributes significantly to the study of plant development and physiology in the past century. Because soybean plant is much bigger in size and longer in life cycle than Arabidopsis, it needs much more space for growth and time for investigation, which significantly hamper the efficiency of research. In the current study, we tested the photoperiodic response of a distinctive artificially-made cotyledon-only plant (COP) using a photoperiod-sensitive soybean variety Zigongdongdou (ZGDD) and other varieties with diverse sensitivity to photoperiod. ZGDD COPs flowered 39.4 ± 2.5 d after emergence under short-day conditions but maintained vegetative growth under long-day and night break conditions, which is similar to the case in the intact ZGDD plants. The COPs of early-maturing and medium-maturing soybean varieties also grew and flowered normally under natural day-length conditions. At the molecular level, the key genes in the photoperiodic pathway such as E1, GmFT1a, GmFT2a, and GmFT5a in the COPs also showed the same photoperiod sensitivity as in the intact plants. In addition, a simpler material of COP with only one cotyledon and root was generated and found to be sensitive to photoperiod as well. Notably, the COPs are only one-fifth the height of intact plants and one-third the maximum diameter of the intact plants grown in chambers 30 d after emergence. Based on COPs, we established a novel experimental system characterized by an entire photoperiodic response and longer longevity of cotyledons in addition to small plant size, ensuring the consistency, reliability, and stability of plant materials. COPs have the potential to be a novel model material for studies of the developmental biology of soybean and other dicots

GmFT2a, a Soybean Homolog of FLOWERING LOCUS T, Is Involved in Flowering Transition and Maintenance

BACKGROUND: Flowering reversion can be induced in soybean (Glycine max L. Merr.), a typical short-day (SD) dicot, by switching from SD to long-day (LD) photoperiods. This process may involve florigen, putatively encoded by FLOWERING LOCUS T (FT) in Arabidopsis thaliana. However, little is known about the potential function of soybean FT homologs in flowering reversion. METHODS: A photoperiod-responsive FT homologue GmFT (renamed as GmFT2a hereafter) was cloned from the photoperiod-sensitive cultivar Zigongdongdou. GmFT2a gene expression under different photoperiods was analyzed by real-time quantitative PCR. In situ hybridization showed direct evidence for its expression during flowering-related processes. GmFT2a was shown to promote flowering using transgenic studies in Arabidopsis and soybean. The effects of photoperiod and temperature on GmFT2a expression were also analyzed in two cultivars with different photoperiod-sensitivities. RESULTS: GmFT2a expression is regulated by photoperiod. Analyses of GmFT2a transcripts revealed a strong correlation between GmFT2a expression and flowering maintenance. GmFT2a transcripts were observed continuously within the vascular tissue up to the shoot apex during flowering. By contrast, transcripts decreased to undetectable levels during flowering reversion. In grafting experiments, the early-flowering, photoperiod-insensitive stock Heihe27 promotes the appearance of GmFT2a transcripts in the shoot apex of scion Zigongdongdou under noninductive LD conditions. The photothermal effects of GmFT2a expression diversity in cultivars with different photoperiod-sensitivities and a hypothesis is proposed. CONCLUSION: GmFT2a expression is associated with flowering induction and maintenance. Therefore, GmFT2a is a potential target gene for soybean breeding, with the aim of increasing geographic adaptation of this crop

Nonlinear adaptive control for multivariable chemical processes

Abstract Multivariable nonlinear models are common in chemical processes. Often many of the parameters change with time and some variables are not measured. To e ectively control these processes, an adaptive scheme is developed here. This scheme combines the generic model control algorithm (GMC), with a nonlinear observer, which is able to track changes in the process model. This control scheme is shown to be quite robust due to the rapid convergence of the nonlinear observer coupled with integral action introduced by the GMC controller. Disturbance rejection is achieved with feedforward action and the combined observer=controller is easy to tune. Two examples demonstrate the e ectiveness of this scheme. The ÿrst example is a simulation of an exothermic batch reactor where the algorithm is used for set point trajectory tracking and calorimetric estimation. The second example is a real-time application to a laboratory pressure tank, which is e ectively controlled over a wide range. Both examples illustrate the ability of this nonlinear adaptive control strategy to provide good estimation and control of these nonlinear processes.

Computational analysis of the relationship between allergenicity and digestibility of allergenic proteins in simulated gastric fluid

Abstract Background Safety assessment of genetically modified (GM) food, with regard to allergenic potential of transgene-encoded xenoproteins, typically involves several different methods, evaluation by digestibility being one thereof. However, there are still debates about whether the allergenicity of food allergens is related to their resistance to digestion by the gastric fluid. The disagreements may in part stem from classification of allergens only by their sources, which we believe is inadequate, and the difficulties in achieving identical experimental conditions for studying digestion by simulated gastric fluid (SGF) so that results can be compared. Here, we reclassify allergenic food allergens into alimentary canal-sensitized (ACS) and non-alimentary canal-sensitized (NACS) allergens and use a computational model that simulates gastric fluid digestion to analyze the digestibilities of these two types. Results The model presented in this paper is as effective as SGF digestion experiments, but more stable and reproducible. On the basis of this model, food allergens are satisfactorily classified as ACS and NACS types by their pathways for sensitization; the former are relatively resistant to gastric fluid digestion while the later are relatively labile. Conclusion The results suggest that it is better to classify allergens into ACS and NACS types when understanding the relationship between their digestibility and allergenicity and the digestibility of a target foreign protein is a parameter for evaluating its allergenicity during safety assessments of GM food.</p