Growth of Thin Oxidation-Resistive Crystalline Si Nanostructures on Graphene

We report the growth of Si nanostructures, either as thin films or nanoparticles, on graphene substrates. The Si nanostructures are shown to be single crystalline, air stable and oxidation resistive, as indicated by the observation of a single crystalline Si Raman mode at around 520 cm-1, a STM image of an ordered surface structure under ambient condition, and a Schottky junction with graphite. Ultra-thin silicon regions exhibit silicene-like behavior, including a Raman mode at around 550 cm-1, a triangular lattice structure in STM that has distinctly different lattice spacing from that of either graphene or thicker Si, and metallic conductivity of up to 500 times higher than that of graphite. This work suggests a bottom-up approach to forming a Si nanostructure array on a large scale patterned graphene substrate for fabricating nanoscale Si electronic devices

Comparisons between ground and air source heat pumps in hot/dry climates : Saudi Arabia as a case study

The use of ground source heat pump (GSHP) systems in cold climates, such as those in parts of North America, Scandinavian countries and China has been discussed for decades. However, hot and dry climates are encountered in vast regions across the globe but, unfortunately, not much data exists in terms of the GSHP systems. This paper aims to investigate the feasibility of using GSHP systems in hot and dry regions and Saudi Arabia is a case study by comparison between using a ground source heat pump and the conventional air source heat pump (ASHP) systems based on Saudi Arabia climates conditions. In order to compare the economics of geothermal heat pump systems to other HVAC alternatives, a direct capital costs comparison is made between GSHP and ASHP. Based on the length of the ground loop, which was calculated using the ASHRAE method, the initial installation cost for GSHP leads to an increase in the investment costs of GSHP because of the extra expensive drilling costs for the ground loop heat exchanger and piping. However, over the period of approximately 22 years there is a 19.6% total cost savings using GSHP compared to ASHP and the GSHP is more feasible with a long payback period. Also, the CO2 emission decrease by about 34%

Tree species and genetic diversity increase productivity via functional diversity and trophic feedbacks

Addressing global biodiversity loss requires an expanded focus on multiple dimensions of biodiversity. While most studies have focused on the consequences of plant interspecific diversity, our mechanistic understanding of how genetic diversity within plant species affects plant productivity remains limited. Here, we use a tree species × genetic diversity experiment to disentangle the effects of species diversity and genetic diversity on tree productivity, and how they are related to tree functional diversity and trophic feedbacks. We found that tree species diversity increased tree productivity via increased tree functional diversity, reduced soil fungal diversity, and marginally reduced herbivory. The effects of tree genetic diversity on productivity via functional diversity and soil fungal diversity were negative in monocultures but positive in the mixture of the four tree species tested. Given the complexity of interactions between species and genetic diversity, tree functional diversity and trophic feedbacks on productivity, we suggest that both tree species and genetic diversity should be considered in afforestation

Anisotropic diffusion of water molecules in hydroxyapatite nanopores

Funded by EPSRC Grant EP/K000128/1

Dystrophin-deficient dogs with reduced myostatin have unequal muscle growth and greater joint contractures

Abstract Background Myostatin (Mstn) is a negative regulator of muscle growth whose inhibition promotes muscle growth and regeneration. Dystrophin-deficient mdx mice in which myostatin is knocked out or inhibited postnatally have a less severe phenotype with greater total mass and strength and less fibrosis and fatty replacement of muscles than mdx mice with wild-type myostatin expression. Dogs with golden retriever muscular dystrophy (GRMD) have previously been noted to have increased muscle mass and reduced fibrosis after systemic postnatal myostatin inhibition. Based partly on these results, myostatin inhibitors are in development for use in human muscular dystrophies. However, persisting concerns regarding the effects of long-term and profound myostatin inhibition will not be easily or imminently answered in clinical trials. Methods To address these concerns, we developed a canine (GRippet) model by crossbreeding dystrophin-deficient GRMD dogs with Mstn-heterozygous (Mstn +/−) whippets. A total of four GRippets (dystrophic and Mstn +/−), three GRMD (dystrophic and Mstn wild-type) dogs, and three non-dystrophic controls from two litters were evaluated. Results Myostatin messenger ribonucleic acid (mRNA) and protein levels were downregulated in both GRMD and GRippet dogs. GRippets had more severe postural changes and larger (more restricted) maximal joint flexion angles, apparently due to further exaggeration of disproportionate effects on muscle size. Flexors such as the cranial sartorius were more hypertrophied on magnetic resonance imaging (MRI) in the GRippets, while extensors, including the quadriceps femoris, underwent greater atrophy. Myostatin protein levels negatively correlated with relative cranial sartorius muscle cross-sectional area on MRI, supporting a role in disproportionate muscle size. Activin receptor type IIB (ActRIIB) expression was higher in dystrophic versus control dogs, consistent with physiologic feedback between myostatin and ActRIIB. However, there was no differential expression between GRMD and GRippet dogs. Satellite cell exhaustion was not observed in GRippets up to 3 years of age. Conclusions Partial myostatin loss may exaggerate selective muscle hypertrophy or atrophy/hypoplasia in GRMD dogs and worsen contractures. While muscle imbalance is not a feature of myostatin inhibition in mdx mice, findings in a larger animal model could translate to human experience with myostatin inhibitors

Tyrosine Sulfation in A431 Cells

In this thesis research I have identified and characterized a unique tyrosine sulfotransferase and its substrate in A431 cells. I also established an in vitro assay method for tyrosine sulfotransferase activity, which opened a door towards enzyme purification Sulfation of proteins on tyrosine residues has recently been shown as a widespread occurrence. Most of the known tyrosine sulfated proteins are secretory proteins. The tyrosine sulfotransferase activity was suggested to be localized to the Golgi apparatus. In an effort to understand more about this modification I examined A431 cells and found a protein of Mr 61,000 which could be tyrosine sulfated by cells (in vivo) and by a cell-free sulfation system (in vitro). The sulfated P61 was not detected in the cell medium. Treatment of membranes with high salt, high EDTA, high pH buffer prior to or after cell-free sulfation could not release P61 or its sulfotransferase, suggesting that both substrate and enzyme are integral membrane proteins. Further, I developed a subcellular fractionation method for A431 cells and employed enzyme marker assay and electron microscopy examination to characterize the subcellular fractions. The sulfated P61 and its sulfotransferase were localized to the rough endoplasmic reticulum. A431 cells also have the capacity to sulfate proteoglycans and pNp-GalNAc. The sulfation of carbohydrates occurs in Golgi which is distinct from the site where sulfation of P61 take place. Therefore the tyrosine sulfation activity not only is confined to Golgi but also can occur in RER. And, instead of a secretory protein this RER sulfotransferase is responsible for sulfation of an integral membrane protein. In order to characterize this RER enzyme and for the future to purify enzymes I established an in vitro assay method for tyrosine sulfotransferase activity by using a synthetic peptide with sequence derived from the fourth component of human complement as an accepter. Experimental results showed that the C4 peptide shares the same RER enzyme with P61. The catalytic domain of the enzyme was facing the lumen of the ER. The apparent Km for the peptide was 0.12 mM, and for the sulfate donor, PAPS, was 0.45 uM. In addition, I also examined the tyrosine sulfotransferase activities from rat liver RER and Golgi fractions with the C4 peptide

Research of Improved Apriori Algorithm Based on Itemset Array

Abstract: Mining frequent item sets is a major key process in data mining research. Apriori and many improved algorithms are lowly efficient because they need scan database many times and storage transaction ID in memory, so time and space overhead is very high. Especially, they are lower efficient when they process large scale database. The main task of the improved algorithm is to reduce time and space overhead for mining frequent item sets. Because, it scans database only once to generate binary item set array, it adopts binary instead of transaction ID when it storages transaction flag, it adopts logic AND operation to judge whether an item set is frequent item set. Moreover, the improved algorithm is more suitable for large scale database. Experimental results show that the improved algorithm has better efficiency than classic Apriori algorithm. Copyright © 2013 IFSA

Efficacy and safety of oral compared with intravenous tranexamic acid in reducing blood loss after primary total knee and hip arthroplasty: a meta-analysis

Abstract Background Tranexamic acid (TXA) is an anti-fibrinolytic agent successfully preventing blood loss when using intravenously (IV) in total hip arthroplasty (THA) and total knee arthroplasty (TKA). An oral administration, which is available on blood sparing, has been reported exhibit profound cost-saving benefits. The aim of this meta-analysis is to investigate whether the administration of oral and intravenous tranexamic acid postoperatively has equivalent blood-sparing properties in these patients. Methods The online electronic databases were searched for eligible literatures updated on September 2018. Studies assessing the effect between oral TXA and intravenous TXA (IV-TXA) in those undergoing TKA or THA were included. All the data were pooled with the corresponding 95% confidence interval (CI) using RevMan software. Based on the heterogeneity, we performed a systematic analysis to explore the overall results across the included studies. Results Nine studies met our inclusion criteria. No significant differences were identified with regard to the Hb drop (SMD = − 0.03,95%CI = − 0.18–0.12, P = 0.67), total Hb loss (SMD = 0.10,95%CI = − 0.06–0.26, P = 0.24), total blood loss (SMD = − 0.00,95%CI = − 0.20–0.20, P = 1.00), transfusion rate (OR = 0.77,95%CI = 0.54–1.10, P = 0.14), DVT rate (OR = 0.58,95%CI = 0.19–1.75, P = 0.33), and length of hospital stay (SMD = − 0.05,95%CI = − 0.28–0.17, P = 0.63) between the oral groups and intravenous group. Conclusion The blood-sparing efficacy of oral TXA is similar to that of the intravenous forms in the setting of THA and TKA. Considering the cost-benefit superiority and ease of administration of oral TXA, further studies and clinical trials are required to further identify the optimal administration for THA and TKA