Bottom-up Design of Three-Dimensional Carbon-Honeycomb with Superb Specific Strength and High Thermal Conductivity

Low-dimensional carbon allotropes, from fullerenes, carbon nanotubes, to graphene, have been broadly explored due to their outstanding and special properties. However, there exist significant challenges in retaining such properties of basic building blocks when scaling them up to three-dimensional materials and structures for many technological applications. Here we show theoretically the atomistic structure of a stable three-dimensional carbon honeycomb (C-honeycomb) structure with superb mechanical and thermal properties. A combination of sp(2) bonding in the wall and sp(3) bonding in the triple junction of C-honeycomb is the key to retain stability of C-honeycomb. The specific strength could be the best in structural carbon materials, and this strength remains at,a high level but tunable with different cell sizes. C-honeycomb is also found to have a very high thermal conductivity, for example, &gt;100 W/mK along the axis of the hexagonal cell with a density only similar to 0.4 g/cm(3). Because of the low density and high thermal conductivity, the specific thermal conductivity of C-honeycoMbs is larger than most engineering materials, including metals and high thermal conductivity semiconductors, as well as lightweight CNT arrays and graphene-based nanocomposites. Such high specific strength, high thermal conductivity, and anomalous Poisson&#39;s effect in C-honeycomb render it appealing for the use in various engineering practices.</p

Estimation of HIV-1 incidence among five focal populations in Dehong, Yunnan: a hard hit area along a major drug trafficking route

<p>Abstract</p> <p>Background</p> <p>Since 1989 when the first 146 HIV positives in China were identified, Dehong Prefecture had been one of the areas hardest-hit by HIV in China. The local and national governments have put substantial financial resources into tackling the HIV epidemic in Dehong from 2004. The objective of this study was to track dynamic changes in HIV-1 prevalence and incidence among five focal populations in Dehong and to assess the impact of HIV prevention and control efforts.</p> <p>Methods</p> <p>Consecutive cross-sectional surveys conducted in five focal populations between 2004 and 2008. Specimens seropositive for HIV were tested with the BED IgG capture enzyme immunoassay to identify recent seroconversions (median, 155 days) using normalized optical density of 0.8 and adjustments.</p> <p>Results</p> <p>From 2004 to 2008, estimated annual HIV incidence among injecting drug users (IDUs) decreased significantly [from 15.0% (95% CI = 11.4%-18.5%) in 2004 to 4.3% (95% CI = 2.4%-6.2%) in 2008; trend test P < 0.0001]. The incidence among other focal populations, such as HIV discordant couples (varying from 5.5% to 4.7%), female sex workers (varying from 1.4% to 1.3%), pregnant women (0.1%), and pre-marital couples (0.2 to 0.1%) remained stable. Overall, the proportion of recent HIV-1 infections was higher among females than males (P < 0.0001).</p> <p>Conclusions</p> <p>The HIV epidemic in Dehong continued to expand during a five-year period but at a slowing rate among IDUs, and HIV incidence remains high among IDUs and discordant couples. Intensive prevention measures should target sub-groups at highest risk to further slow the epidemic and control the migration of HIV to other areas of China, and multivariate analysis is needed to explore which measures are more effective for different populations.</p

Association of plasma microRNA expression with age, genetic background and functional traits in dairy cattle

Abstract A number of blood circulating microRNAs (miRNAs) are proven disease biomarkers and have been associated with ageing and longevity in multiple species. However, the role of circulating miRNAs in livestock species has not been fully studied. We hypothesise that plasma miRNA expression profiles are affected by age and genetic background, and associated with health and production traits in dairy cattle. Using PCR arrays, we assessed 306 plasma miRNAs for effects of age (calves vs mature cows) and genetic background (control vs select lines) in 18 animals. We identified miRNAs which were significantly affected by age (26 miRNAs) and genetic line (5 miRNAs). Using RT-qPCR in a larger cow population (n = 73) we successfully validated array data for 12 age-related miRNAs, one genetic line-related miRNA, and utilised expression data to associate their levels in circulation with functional traits in these animals. Plasma miRNA levels were associated with telomere length (ageing/longevity indicator), milk production and composition, milk somatic cell count (mastitis indicator), fertility, lameness, and blood metabolites linked with body energy balance and metabolic stress. In conclusion, circulating miRNAs could provide useful selection markers for dairy cows to help improve health, welfare and production performance

Overexpression of a Common Wheat Gene TaSnRK2.8 Enhances Tolerance to Drought, Salt and Low Temperature in Arabidopsis

Drought, salinity and low temperatures are major factors limiting crop productivity and quality. Sucrose non-fermenting1-related protein kinase 2 (SnRK2) plays a key role in abiotic stress signaling in plants. In this study, TaSnRK2.8, a SnRK2 member in wheat, was cloned and its functions under multi-stress conditions were characterized. Subcellular localization showed the presence of TaSnRK2.8 in the cell membrane, cytoplasm and nucleus. Expression pattern analyses in wheat revealed that TaSnRK2.8 was involved in response to PEG, NaCl and cold stresses, and possibly participates in ABA-dependent signal transduction pathways. To investigate its role under various environmental stresses, TaSnRK2.8 was transferred to Arabidopsis under control of the CaMV-35S promoter. Overexpression of TaSnRK2.8 resulted in enhanced tolerance to drought, salt and cold stresses, further confirmed by longer primary roots and various physiological characteristics, including higher relative water content, strengthened cell membrane stability, significantly lower osmotic potential, more chlorophyll content, and enhanced PSII activity. Meanwhile, TaSnRK2.8 plants had significantly lower total soluble sugar levels under normal growing conditions, suggesting that TaSnRK2.8 might be involved in carbohydrate metabolism. Moreover, the transcript levels of ABA biosynthesis (ABA1, ABA2), ABA signaling (ABI3, ABI4, ABI5), stress-responsive genes, including two ABA-dependent genes (RD20A, RD29B) and three ABA-independent genes (CBF1, CBF2, CBF3), were generally higher in TaSnRK2.8 plants than in WT/GFP controls under normal/stress conditions. Our results suggest that TaSnRK2.8 may act as a regulatory factor involved in a multiple stress response pathways

Protective Effects of a Rhodiola Crenulata Extract and Salidroside on Hippocampal Neurogenesis against Streptozotocin-Induced Neural Injury in the Rat

Previously we have demonstrated that a Rhodiola crenulata extract (RCE), containing a potent antioxidant salidroside, promotes neurogenesis in the hippocampus of depressive rats. The current study was designed to further investigate the protective effect of the RCE on neurogenesis in a rat model of Alzheimer's disease (AD) induced by an intracerebroventricular injection of streptozotocin (STZ), and to determine whether this neuroprotective effect is induced by the antioxidative activity of salidroside. Our results showed that pretreatment with the RCE significantly improved the impaired neurogenesis and simultaneously reduced the oxidative stress in the hippocampus of AD rats. In vitro studies revealed that (1) exposure of neural stem cells (NSCs) from the hippocampus to STZ strikingly increased intracellular reactive oxygen species (ROS) levels, induced cell death and perturbed cell proliferation and differentiation, (2) hydrogen peroxide induced similar cellular activities as STZ, (3) pre-incubation of STZ-treated NSCs with catalase, an antioxidant, suppressed all these cellular activities induced by STZ, and (4) likewise, pre-incubation of STZ-treated NSCs with salidroside, also an antioxidant, suppressed all these activities as catalase: reduction of ROS levels and NSC death with simultaneous increases in proliferation and differentiation. Our findings indicated that the RCE improved the impaired hippocampal neurogenesis in the rat model of AD through protecting NSCs by its main ingredient salidroside which scavenged intracellular ROS

Optical Environmental Sensing in Wireless Smart Meter Network

In recent years, the traditional power grid is undergoing a profound revolution due to the advent and development of smart grid. Many hard and challenging issues of the traditional grid such as high maintenance costs, poor scalability, low efficiency, and stability can be effectively handled and solve in the wireless smart grid (WSG) by utilizing the modern wireless sensor technology. In a WSG, data are collected by sensors at first and then transmitted to the base station through the wireless network. The control centre is responsible for taking actions based on this received data. Traditional sensors are failing to provide accurate and reliable data in WSG, and optical fiber based sensor are emerging as an obvious choice due to the advancement of optical fiber sensing technology, accuracy, and reliability. This paper presents a WSG platform integrated with optic fiber-based sensors for real-time monitoring. To demonstrate the validity of the concept, fresh water sensing of refractive index (RI) was first experimented with an optical fiber sensor. The sensing mechanism functions with the reflectance at the fiber’s interface where reflected spectra’s intensity is registered corresponding to the change of RI in the ambient environment. The achieved sensitivity of the fabricated fiber sensor is 29.3 dB/RIU within the 1.33–1.46 RI range. An interface between the measured optical spectra and the WSG is proposed and demonstrated, and the data acquired is transmitted through a network of wireless smart meters

Discussion on significant cost implications in using janbu's simplified or morgenstern-price slice methods for soil nail design of cut slopes

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Novel Amphiphilic Multi-Arm, Star-Like Block Copolymers as Unimolecular Micelles

A series of novel amphiphilic multiarm, star-like block copolymers, poly(acrylic acid)-b-polystyrene (PAA-b-PS) based on beta-cyclodextrin (beta-CD) with well-defined molecular architectures, molecular weight, and ratio of two dissimilar blocks were prepared by sequential atom transfer radical polymerization (ATRP). beta-CD with 21 hydroxyl groups was esterified by the reaction of its hydroxyl end groups with 2-bromoisobutyryl bromide, producing star-like heptakis[2,3,6-tri-O-(2-bromo-2-methylpropionyl]-beta-cyclodextrin) (denoted 21-Br-beta-CD). Subsequently, 21-Br-beta-CD was utilized to initiate sequential ATRP of tert-butyl acrylate (tBA) and styrene (St). A series of 21-arm, star-like diblock copolymers, poly(tert-butyl acrylate)-b-polystyrene (PtBA-b-PS) were thus obtained. Finally, the ester groups of tBA in star-like PrBA-b-PS were selectively hydrolyzed by trifluoroacetic acid (TFA), thereby yielding amphiphilic 21-arm, star-like diblock copolymer PAA-b-PS with narrow molecular weight distribution (polydispersity index, PDI < 1.2). The intermediate and final products were systematically characterized and confirmed by GPC, (1)H NMR and FT-IR. The unimolecular micelles (i.e., composed of single copolymer molecule) formed from amphiphilic star-like PAA-b-PS were analyzed by dynamic light scattering, TEM, and AFM.X11106101sciescopu