How does graphene grow on complex 3D morphologies?

The growth of two-dimensional materials into three-dimensional geometries holds the promise for high performance hybrid materials and novel architectures. The synthesis of such structures, however, proceeds in fundamentally different flow regimes compared to conventional CVD where pressure differences and wall collisions are neglected. We here demonstrate the remarkable stability of graphene growth under varying fluid dynamic flow regimes. We investigate the growth process across different flow conditions using confined growth in refractory pores. Analysis of the growth rate reveals a transport-limited process which allows experimental determination of the gas diffusion coefficient. The diffusion coefficient was found to be constant for large pore dimension but scales with pore dimension as the pore size decreases below the mean free path providing clear evidence for previously predicted Knudsen molecular-flow conditions for atomic confinement. Surprisingly, changes to the flow conditions by two orders of magnitude do not cause qualitative changes of the graphene growth process. This unique behavior was attributed to rarefied flow conditions by scaling analysis and an analytical relation between growth rate and constriction could be extracted that proves accurate throughout the investigated conditions. Our results demonstrate a fundamentally different growth process compared to traditional CVD processes that is akin to atomic layer deposition and highlight the feasibility of high-quality 2D-material growth on 3D morphologies with ultra-high aspect ratios.

Potential phosphorus eutrophication mitigation strategy: Biochar carbon composition, thermal stability and pH influence phosphorus sorption.

Phosphorus (P) eutrophication is a major pollution problem globally, with unprecedented amount of P emanating from agricultural sources. But little is known about the optimization of soil-biochar P sorption capacity. The study objective was to determine how biochar feedstocks and pyrolysis conditions influences carbon (C) thermal stability, C composition and pH and in turn influence the phosphorus sorption optimization. Biochar was produced from switchgrass, kudzu and Chinese tallow at 200, 300, 400, 500, 550, 650,750 °C. Carbon thermal stability was determined by multi-element scanning thermal analysis (MESTA), C composition was determined using solid state 13C NMR. Phosphorus sorption was determined using a mixture of 10% biochar and 90% sandy soil after incubation. Results indicate increased P sorption (P < 0.0001) and decreased P availability (P < 0.0001) with increasing biochar pyrolysis temperature. However, optimum P sorption was feedstock specific with switchgrass indicating P desorption between 200 and 550 °C. Phosphorus sorption was in the order of kudzu > switchgrass > Chinese tallow. Total C, C thermal stability, aromatic C and alkalinity increased with elevated pyrolysis temperature. Biochar alkalinity favored P sorption. There was a positive relationship between high thermal stable C and P sorption for Kudzu (r = 0.62; P = 0.0346) and Chinese tallow (r = 0.73; P = 0.0138). In conclusion, biochar has potential for P eutrophication mitigation, however, optimum biochar pyrolysis temperature for P sorption is feedstock specific and in some cases might be out of 300-500 °C temperature range commonly used for agronomic application. High thermal stable C dominated by aromatic C and alkaline pH seem to favor P sorption.

Tube Feeding among Elder in Long-Term Care Facilities: A Systematic Review and Meta-Analysis.

OBJECTIVE: The use of tube feeding for elderly patients with poor nutritional intake is a ubiquitous method of feeding. This systematic review and meta-analysis were carried out to compare nutritional benefits of enteral feeding versus oral feeding in long-term care facilities. SETTING: Databases including the Cochrane Library, ProQuest, PubMed, EMBASE, EBSCO, Web of Science and Google Scholar through April 2014 using keywords including enteral feeding, tube feeding or oral feeding combined with long term care facilities or nursing home. PARTICIPANTS: Eight articles, with 841 participants were included in meta-analysis and 13 articles were included in systematic review. The elderly had to live in long-term care institutions and could not be on any mechanically assisted ventilation systems or be in any type of post-operative status. MEASUREMENTS: The three investigators extracted and appraised data using the same study design, baseline characteristics, and outcomes, independently. RESULTS: Following a systematic review, 13 articles out of 8218 original research articles were selected for this analysis. Meta-analysis of tube-fed patients found lower levels of hemoglobin (Weighted Mean Difference (WMD -0.21g/dl; 95% CI -0.42 to -0.01; p=0.04) and creatinine (WMD -0.08g/dl; 95% CI -0.17 to 0.00, p=0.05). Moreover, the results showed that there were no benefits regarding body mass index (BMI), albumin, dietary intake of proteins, total calories and fat. CONCLUSIONS: The results show that tube feeding does not increase patients' nutrients absorption to improve nutritional status. Instead, these results indicate that oral feeding is better regarding some nutritional biochemical parameters.

Thrombin Activates Latent TGFß1 via Integrin αvß1 in Gingival Fibroblasts.

Transforming growth factor ß (TGFß) regulates cell proliferation, differentiation, migration, apoptosis, and extracellular matrix production. It also plays a pivotal role in the pathogenesis of gingival overgrowth. Thrombin is a key player in tissue repair, remodeling, and fibrosis after an injury, and it exerts profibrotic effects by activating protease-activated receptors. Connective tissue growth factor (CTGF or CCN2) modulates cell adhesion, migration, proliferation, matrix production, and wound healing. It is overexpressed in many fibrotic disorders, including gingival overgrowth, and it is positively associated with the degree of fibrosis in gingival overgrowth. In human gingival fibroblasts, we previously found that TGFß1 induced CCN2 protein synthesis through c-jun N-terminal kinase and Smad3 activation. Thrombin stimulates CCN2 synthesis through protease-activated receptor 1 and c-jun N-terminal kinase signaling. Curcumin inhibited TGFß1- and thrombin-induced CCN2 synthesis. In this study, we demonstrated that thrombin and protease-activated receptor 1 agonist SFLLRN induced latent TGFß1 activation and Smad3 phosphorylation in human gingival fibroblasts. Pretreatment with a TGFß-neutralizing antibody, TGFß type I receptor inhibitor SB431542, and Smad3 inhibitor SIS3 inhibited approximately 86%, 94%, and 100% of thrombin-induced CCN2 synthesis, respectively. Furthermore, blocking integrin subunits αv and ß1 with antibodies effectively inhibited SFLLRN-induced Smad3 phosphorylation and CCN2 synthesis and increased activated TGFß1 levels; however, similar effects were not observed for integrins αvß3 and αvß5. These results suggest that protease-activated receptor 1-induced CCN2 synthesis in human gingival fibroblasts is mediated through integrin αvß1-induced latent TGFß1 activation and subsequent TGFß1 signaling. Moreover, curcumin dose dependently decreased thrombin-induced activated TGFß1 levels. Curcumin-inhibited thrombin-induced CCN2 synthesis in human gingival fibroblasts is caused by the suppression of latent TGFß1 activation.

NADPH Oxidase 4 Mediates TGFß1-induced CCN2 in Gingival Fibroblasts.

Transforming growth factor ß (TGFß) plays a central role in the pathogenesis of gingival overgrowth (GO). Connective tissue growth factor (CTGF; or CCN2) is induced by TGFß in human gingival fibroblasts (HGFs) and is overexpressed in GO tissues. CCN2 creates an environment favorable for fibrogenesis and is required for the maximal profibrotic effects of TGFß. We previously showed that Src, JNK, and Smad3 mediate TGFß1-induced CCN2 protein expression in HGFs. Moreover, Src is an upstream signaling transducer of JNK and Smad3. Recent studies suggested that NADPH oxidase (NOX)-dependent redox mechanisms are involved in mediating the profibrotic effects of TGFß. In this study, we demonstrated that TGFß1 upregulated NOX4 protein expression and increased reactive oxygen species (ROS) production in HGFs. Genetic or pharmacologic targeting of NOX4 abrogated TGFß1-induced ROS production; Src, JNK, and Smad3 activation; and CCN2 and type I collagen protein expression in HGFs. Our results indicated that NOX4-derived ROS play pivotal roles in activating Src kinase activity leading to the activation of canonical (Smad3) and noncanonical (JNK) cascades that cooperate to attain maximum CCN2 expression. Furthermore, we demonstrated that curcumin significantly inhibited the TGFß1-induced NOX4 protein expression in HGFs. Curcumin potentially qualifies as an agent to control GO by suppressing TGFß1-induced NOX4 expression in HGFs.

Raman spectroscopy study of isolated double-walled carbon nanotubes with different metallic and semiconducting configurations.

A double-walled carbon nanotube (DWNT) provides the simplest system to study the interaction between concentric layers in carbon nanotubes. The inner and outer walls of a DWNT can be metallic (M) or semiconducting (S), and each of the four possible configurations (M@M, M@S, S@S, S@M) has different electronic properties. Here we report, for the first time, detailed Raman spectroscopy experiments carried out on individual DWNTs, where both concentric tubes are measured under resonance conditions, in order to understand the dependence of their electronic and optical properties according to their configuration. Interestingly, for the three DWNTs that were studied, the inner-outer tube distance (e.g., 0.31-0.33 nm) was less than the interlayer spacing in graphite. We believe these results have important implications in the fabrication of electronic devices using different types of S and M tubular interconnects.

Electroluminescence enhancement of SiGe/Si multiple quantum wells through nanowall structures.

The enhancement of light extraction from Si(0.5)Ge(0.5)/Si multiple quantum wells (MQWs) with nanowall structures fabricated by electron cyclotron resonance (ECR) plasma etching is presented. It is shown that the ECR plasma treatment does not damage the crystalline quality. At a driving current of 5.5 × 10(6) A m(-2), the light output intensity of the MQWs with nanowall structures shows an enhancement of about 50% compared with that of the original MQWs. In addition to the enhanced light extraction, the improved optoelectronic properties are also attributed to the strain relaxation in nanowall structures.

Focal segmental glomerulosclerosis in association with Cushing's disease.

Focal segmental glomerulosclerosis (FSGS) may be idiopathic or secondary to a variety of causes. Clinical distinction between primary and secondary forms of FSGS has crucial therapeutic consequences. Whereas the former may respond to immunosuppressive therapy, treatment of secondary forms of FSGS must aim to resolve the underlying diseases. Although the combination of nephrotic syndrome and Cushing's syndrome has been described anecdotally, the causal relationship between these two diseases remains controversial. We report herein a 37-year-old man who presented with lower extremity pitting edema. Heavy proteinuria and mild renal insufficiency prompted to perform a kidney biopsy and the specimen showed FSGS. On the other hand, admission physical examination was notable for a Cushingoid appearance. After endocrinological investigations, the patient was diagnosed as having Cushing's disease caused by pituitary adrenocorticotropic hormone-producing microadenoma. Immunosuppressive therapy for the treatment of FSGS was not carried out and we treated his Cushing's disease with transsphenoidal resection of the pituitary microadenoma. Surprisingly, resolution of heavy proteinuria occurred when the patient's physical features characteristic of Cushing's disease were gradually resolved 3 months later. This case suggests a possible association of Cushing's disease with FSGS.

Strong luminescence from strain relaxed InGaN/GaN nanotips for highly efficient light emitters.

Semiconductor heterostructures represent the most important building block for current optoelectronic devices. One of the common features of semiconductor heterostructures is the existence of internal strain due to lattice mismatch. The internal strain can tilt the band alignment and significantly alter the physical properties of semiconductor heterostructures, such as reducing the internal quantum efficiency of a light emitter. Here, we provide a convenient route to release the internal strain by patterning semiconductor heterostructures into nanotip arrays. The fabrication of the nanotip arrays was achieved by self-masked dry etching technique, which is simple, low cost and compatible with current semiconductor technologies. By implementing our approach to InGaN/GaN multiple quantum wells, we demonstrate that the light emission can be enhanced by up to 10 times. Our approach renders an excellent opportunity to manipulate the internal strain, and is very useful to create highly efficient solid state emitters.

Minimal change nephrotic syndrome in association with strongyloidiasis.

Although parasitic infections have been known to be associated with immune complex-mediated glomerular lesions, strongyloidiasis-related glomerulopathy has not been well documented. We report a patient with delayed-recognized disseminated strongyloidiasis who developed nephrotic syndrome 3 months after the beginning of the manifestations related to strongyloidiasis. A kidney biopsy showed minimal change disease. We treated strongyloidiasis and hesitated to give steroid therapy for the treatment of minimal change nephrotic syndrome (MCNS) because of the risk of aggravation of Strongyloides stercoralis infection. Surprisingly, resolution of heavy proteinuria occurred after anthelmintic therapy with ivermectin. This case suggests a possible causal relationship between S. stercoralis infection and MCNS. In addition, a review of another 4 cases previously reported in the literature demonstrates the importance of detecting underlying S. stercoralis infection in patients with nephrotic syndrome since steroid therapy can cause hyperinfection or disseminated strongyloidiasis, and which may lead to fatal outcome.

Kinetics of Fe(III) reduction by ascorbic acid in aqueous solutions.

The reaction of Fe(III) and ascorbic acid (AA) in food products and digestive tracts affects the efficiency and uptake of these two nutrients. We investigated the kinetics of Fe(III) reduction by AA at pH 5 and 6 in a model system at 25 degrees C. The results indicate that the reduction of Fe(III) by AA is of zero order with respect to AA. The reaction order with respect to Fe(III) cannot be represented by a simple kinetic model at pH 5 or 6. The major stage of the reduction (about 80%, stoichiometrically), however, could be represented by a general equation of -d[Fe(III)]/dt = k[Fe(III)],(1. 811) where k is a rate constant and [Fe(III)] is the total ferric concentration. The rate constant decreased 1 order of magnitude as pH increased from 5 to 6. Aging of Fe(III) solution slows its reduction rate at pH 6 but not at pH 5.

Determination of carbon dioxide evolution rates using a novel noninstrumental microrespirometer.

A novel noninstrumental microrespirometer was developed to determine carbon dioxide evolution rates of solid or liquid samples at microL/h levels accurately and rapidly. The respirometer is based on the simple principle of acid-base titration at a steady-state of carbon dioxide absorption/evolution. The structure and operation of the microrespirometer are simple and the cost is modest in comparison to instrumental methods. The microrespirometer is suitable for laboratory studies and field routine examinations of food, agricultural, and environmental samples.

Induction of integrin-associated protein (IAP) mRNA expression during memory consolidation in rat hippocampus.

We have previously demonstrated that hippocampal integrin-associated protein (IAP) gene expression is associated with memory formation in a one-way inhibitory avoidance learning in rats. In the present study, we further investigated the role and mechanism of IAP involved in memory consolidation in rats. Because of the minute amount of IAP present in the brain, we have adopted the quantitative reverse transcription-polymerase chain reaction (RT-PCR) method. Our results revealed that hippocampal IAP mRNA expression is approximately fourfold higher in rats showing good memory retention (GM, retention score of 600 s) at 3 h, but not at other time points, after training when compared with the poor memory rats (retention score < 80 s). On the other hand, integrin alphav mRNA level was markedly increased ( approximately twofold), while integrin beta3 mRNA level was decreased ( approximately 50%) at 1 h post-training. Further, separate sets of RT-PCR analysis revealed that IAP5 and IAP6 mRNA expressions, but not that of IAP7, were markedly increased in GM rats 3 h post-training. Moreover, regional distribution studies revealed that different isoforms of the IAP gene are similarly distributed in different brain areas, while IAP7 has been the predominant form present in astrocyte cells. These results together suggest that IAP mRNA expression is indeed induced upon training, rather than that the GM rats have constitutively higher levels of IAP. The unparallel change of IAP and integrin mRNA expressions as far as time-course is concerned suggests that they are possibly involved in different forms and stages of memory processing. Further, IAP5 and IAP6 are more closely associated with memory consolidation, while IAP7 may constitute the major isotype for signal transduction in astrocyte cells.

Ultrastructural changes in pre- and post-rigor beef muscle caused by conventional and microwave cookery.

Examination of cooked pre-rigor muscle by TEM (transmission electron microscopy) and SEM (scanning electron microscopy) revealed that all cookery methods resulted in the development of supercontraction bands alternating with areas showing tissue fragmentation and tearing. Microwave cookery produced smaller and less dense supercontraction nodes in pre-rigor muscle with less tearing and fragmentation but more fibre separation. Although cold-shortened pre-rigor muscle cooked by all methods also exhibited supercontraction bands with some tearing and fragmentation in adjacent sarcomeres, the samples cooked by microwaves showed a more uniform repeating pattern of small stretched areas alternating with dense contracted areas. Cooking of muscle in full rigor resulted in myofibrillar protein coagulation and shrinkage but supercontraction nodes were absent. Cold-shortened bicarbonate treated muscle was relatively intact after cooking, exhibiting fusion of the myofibrils and an absence of intermyofibrillar spaces. Results are discussed in relation to possible effects upon tenderness.