Radial Growth of Qilian Juniper on the Northeast Tibetan Plateau and Potential Climate Associations

There is controversy regarding the limiting climatic factor for tree radial growth at the alpine treeline on the northeastern Tibetan Plateau. In this study, we collected 594 increment cores from 331 trees, grouped within four altitude belts spanning the range 3550 to 4020 m.a.s.l. on a single hillside. We have developed four equivalent ring-width chronologies and shown that there are no significant differences in their growth-climate responses during 1956 to 2011 or in their longer-term growth patterns during the period AD 1110–2011. The main climate influence on radial growth is shown to be precipitation variability. Missing ring analysis shows that tree radial growth at the uppermost treeline location is more sensitive to climate variation than that at other elevations, and poor tree radial growth is particularly linked to the occurrence of serious drought events. Hence water limitation, rather than temperature stress, plays the pivotal role in controlling the radial growth of Sabina przewalskii Kom. at the treeline in this region. This finding contradicts any generalisation that tree-ring chronologies from high-elevation treeline environments are mostly indicators of temperature changes

Influence of adding multiwalled carbon nanotubes on the adhesive strength of composite epoxy/sol–gel materials

The tensile shear strength of a composite epoxy/sol–gel system modified with different ratios of multiwall carbon nanotubes (MWCNTs) was evaluated using a mechanical testing machine. The experimental results showed that the shear strength increased when lower than ~0.07 wt% of MWCNTs were added in the composite solution. The increase of the shear strength was attributed to both the mechanical load transfer from the matrix to the MWCNTs and the high specific surface area of this material that increased the degree of crosslinking with other inorganic fillers in the formulation. However, a decrease in the adhesive shear strength was observed after more than ~0.07 wt% MWCNTs were added to the composite. The reason for this may be related to the high concentration of MWCNTs within the matrix leading to excessively high viscosity, dewetting of the substrate surfaces, and reduced bonding of MWCNTs with the matrix, thereby limiting the strength. SEM observation of the fracture surfaces for composite epoxy/sol–gel adhesive materials with 0.01 wt% MWCNTs showed a mixed interfacial/cohesive fracture mode. This fracture mode indicated strong links at the adhesive/substrate interface, and interaction between CNTs and the matrix was achieved; therefore, adhesion performance of the composite epoxy/sol–gel material to the substrate was improved. An increase of a strong peak related to the C–O bond at ~1733 cm-1 in the FTIR spectra was observed. This peak represented crosslinking between the CNT surface and the organosilica nanoparticles in the MWCNTs-doped composite adhesive. Raman spectroscopy was also used to identify MWCNTs within the adhesive material. The Raman spectra exhibit peaks at ~1275 cm-1 and in the range of ~1549–1590 cm-1. The former is the graphite G-band, while the latter is the diamond D-band. The D-band and G-band represent the C–C single bond and C=C double bond in carbon nanotubes, respectively

Liquid marble-derived solid-liquid hybrid superparticles for CO2 capture.

The design of effective CO2 capture materials is an ongoing challenge. Here we report a concept to overcome current limitations associated with both liquid and solid CO2 capture materials by exploiting a solid-liquid hybrid superparticle (SLHSP). The fabrication of SLHSP involves assembly of hydrophobic silica nanoparticles on the liquid marble surface, and co-assembly of hydrophilic silica nanoparticles and tetraethylenepentamine within the interior of the liquid marble. The strong interfacial adsorption force and the strong interactions between amine and silica are identified to be key elements for high robustness. The developed SLHSPs exhibit excellent CO2 sorption capacity, high sorption rate, long-term stability and reduced amine loss in industrially preferred fixed bed setups. The outstanding performances are attributed to the unique structure which hierarchically organizes the liquid and solid at microscales

Epidermal growth factor mediates spermatogonial proliferation in newt testis

The complex processes of spermatogenesis are regulated by various factors. The aim of the current study is to determine the effect of epidermal growth factor (EGF) on spermatogonial proliferation and clarify the mechanism causing the proliferation in newt testis. In the organ culture, EGF stimulated spermatogonial proliferation, but not their differentiation into spermatocytes. cDNA cloning identified 3 members of the EGF receptors, ErbB1, ErbB2, and ErbB4, in the testis. RT-PCR showed that all the receptors cloned were expressed in both Sertoli and germ cells at the spermatogonial stage. In the organ cultures with inhibitors for the EGF receptors, mitogen-activated protein kinase (MAPK), and phosphoinositide 3-kinase (PI3K), the EGF-induced spermatogonial proliferation was suppressed. Furthermore, when the organ culture was exposed to EGF, the expressions of stem cell factor (SCF), immunoglobulin-like domain containing neuregulin1 (Ig-NRG1), and ErbB4 mRNA were increased. These results suggested that, since the spermatogonia are sequestered within cysts by the blood-testis barrier consisted of Sertoli cells, EGF possibly mediates spermatogonial proliferation in an endocrine manner through the receptors including ErbB1, ErbB2, and ErbB4 expressed on Sertoli cells via activation of MAPK cascade or/and PI3K cascade by elevating the expressions of SCF, Ig-NRG1, and ErbB4

Control of electronic conduction at an oxide heterointerface using surface polar adsorbates

The transfer of electrons between a solid surface and adsorbed atomic or molecular species is fundamental in natural and synthetic processes, being at the heart of most catalytic reactions and many sensors. In special cases, metallic conduction can be induced at the surface of, for example, Si-terminated SiC1, or mixed-terminated ZnO2, in the presence of a hydrogen adlayer. Generally, only the surface atoms are significantly affected by adsorbates. However, remotely changing electronic states far from the adsorbed layer is possible if these states are electrostatically coupled to the surface. Here we show that the surface adsorption of common solvents such as acetone, ethanol, and water can induce a large change (factor of three) in the conductivity at the buried interface between SrTiO3 substrates and LaAlO3 thin films3-8. This phenomenon is observed only for polar solvents. Our result provides experimental evidence that adsorbates at the LaAlO3 surface induce accumulation of electrons at the LaAlO3/SrTiO3 interface, suggesting a general polarization-facilitated electronic transfer mechanism, which can be used for sensor applications.Comment: 14 pages, 4 figure

Expression profile of genes regulated by activity of the Na-H exchanger NHE1

BACKGROUND: In mammalian cells changes in intracellular pH (pH(i)), which are predominantly controlled by activity of plasma membrane ion exchangers, regulate a diverse range of normal and pathological cellular processes. How changes in pH(i )affect distinct cellular processes has primarily been determined by evaluating protein activities and we know little about how pH(i )regulates gene expression. RESULTS: A global profile of genes regulated in mammalian fibroblasts by decreased pH(i )induced by impaired activity of the plasma membrane Na-H exchanger NHE1 was characterized by using cDNA microarrays. Analysis of selected genes by quantitative RT-PCR, TaqMan, and immunoblot analyses confirmed results obtained from cDNA arrays. Consistent with established roles of pH(i )and NHE1 activity in cell proliferation and oncogenic transformation, grouping regulated genes into functional categories and biological pathways indicated a predominant number of genes with altered expression were associated with growth factor signaling, oncogenesis, and cell cycle progression. CONCLUSION: A comprehensive analysis of genes selectively regulated by pH(i )provides insight on candidate targets that might mediate established effects of pH(i )on a number of normal and pathological cell functions

Photodynamic therapy augments the efficacy of oncolytic vaccinia virus against primary and metastatic tumours in mice

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MiR-339-5p inhibits breast cancer cell migration and invasion in vitro and may be a potential biomarker for breast cancer prognosis

<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) play an important role in the regulation of cell growth, differentiation, apoptosis, and carcinogenesis. Detection of their expression may lead to identifying novel markers for breast cancer.</p> <p>Methods</p> <p>We profiled miRNA expression in three breast cancer cell lines (MCF-7, MDA-MB-231, and MDA-MB-468) and then focused on one miRNA, miR-339-5p, for its role in regulation of tumor cell growth, migration, and invasion and target gene expression. We then analyzed miR-339-5p expression in benign and cancerous breast tissue specimens.</p> <p>Results</p> <p>A number of miRNAs were differentially expressed in these cancer cell lines. Real-time PCR indicated that miR-339-5p expression was downregulated in the aggressive cell lines MDA-MB-468 and MDA-MB-231 and in breast cancer tissues compared with benign tissues. Transfection of miR-339-5p oligonucleotides reduced cancer cell growth only slightly but significantly decreased tumor cell migration and invasion capacity compared with controls. Real-time PCR analysis showed that BCL-6, a potential target gene of miR-339-5p, was downregulated in MDA-MB-231 cells by miR-339-5p transfection. Furthermore, the reduced miR-339-5p expression was associated with an increase in metastasis to lymph nodes and with high clinical stages. Kaplan-Meier analyses found that the patients with miR-339-5p expression had better overall and relapse-free survivals compared with those without miR-339-5p expression. Cox proportional hazards analyses showed that miR-339-5p expression was an independent prognostic factor for breast cancer patients.</p> <p>Conclusions</p> <p>MiR-339-5p may play an important role in breast cancer progression, suggesting that miR-339-5p should be further evaluated as a biomarker for predicting the survival of breast cancer patients.</p