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Formation damage caused by organic contaminates is one of the most important issues that undermine well injectivity and productivity. Anionic surfactants are commonly used to mobilize the organic contaminates trapped by capillary forces. The electrostatic repulsion between anionic surfactant heads reduces the surfactant density at the oil-water interface, consequently reducing the interfacial efficiency. In this paper, a novel surfactant blend of anionic-cationic surfactants (Sa/c) was designed and showed much higher efficiency than traditional ones because of the strong electrostatic attraction between anionic and cationic surfactants. The oil-water interfacial tension (IFT) was reduced to 3 × 10−4 mN/m, and the viscosity of crude oil was reduced by 92%. In addition, the freezing point of the residual oil was decreased by 20.9%. Moreover, Sa/c altered the wettability and inhibited the clay swelling. Field applications were conducted in sandstone reservoirs at temperatures of about 120 °C and permeabilities below 10 mD. The average injection pressure drops were greater than 30%. The findings of this study can help for better understanding the advantages of Sa/c with high interfacial activity and revealed that formation damage caused by the organic contaminates in high temperature and low permeability sandstone reservoirs can be effectively remediated by this novel surfactant blend. [ABSTRACT FROM AUTHOR]

1. The objective of this study was to examine the keratin composition of crop milk, the variation of epithelial thickness and keratin (K) gene expression in samples from young pigeon during incubation and chick rearing. 2. Crop milk was collected from 1-, 3- and 5-day-old squab crops for keratin content analysis. Results showed that K4 accounted for the highest proportion of all detected keratins. 3. In total, 42 pairs of adult pigeons were allocated to seven groups according to different stages to collect crop samples. Gene expression studies showed that the K3 gene expression was maximised at rearing Day 15 (15) and R1 in males and females, respectively. K6a gene level was the greatest at R15 in females, whereas it peaked at incubation Day 4 (I4) in males. The K12, K13, K23 and K80 gene levels were inhibited at the peak period of crop milk formation in comparison with I4. In females, K cochleal expression peaked at I10, whereas it was the greatest at R25 in males. K4 and K14 gene expression was the highest at I10 in females, while K4 and K14 were minimised at I17 and R7 in males, respectively. Gene expressions of K5, K8, K19 and K20 in males and K19 in females were maximised at R1. The K5, K20 and K75 gene levels in females peaked at R7. K75 and K8 expressions in males and females reached a maximum value at R25 and I17, respectively. 4. The epithelial thickness of male and female crops reached their greatest levels at R1 and had the highest correlation with K19. 5. These results emphasised the importance of keratinisation in crop milk formation, and different keratins probably play various roles during this period. The K19 was probably a marker for pigeon crop epithelium development. The sex of the parent pigeon affected keratin gene expression profiles. [ABSTRACT FROM AUTHOR]

Using a laser-heated diamond anvil cell, a powdered sample of gallium phosphide was compressed to 17.5 GPa and heated up to 1400 K. The material obtained was characterized at room temperature using synchrotron x-ray diffraction. Experimental results were compared with first-principles calculations. The polymorph observed assumes the simple cubic structure (sc16) initially reported for GaAs at high pressures. Microdiffraction mapping showed variable grain sizes of the synthesized phase, with the largest grains located in the middle of the heated spot. Structural refinements were performed on selected grains. The structure predicted based on first-principles calculations is in close agreement with the experiments. The two Ga–P bonds show similar lengths in sc16-GaP; however, the bond angles differ, resulting in a distorted tetrahedral coordination geometry. [ABSTRACT FROM AUTHOR]

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A simultaneous method for quantifying eight metabolites of organophosphate pesticides and pyrethroid pesticides in urine samples has been established. The analytes were extracted using liquid–liquid extraction coupled with WCX solid phase extraction (SPE) cartridges. Eight metabolites were chemically derivatized before analysis using gas chromatography–tandem mass spectrometry (GC–MS–MS). The separation was performed on a HP-5MS capillary column (30 m × 0.25 mm × 0.25 µm) with temperature programming. The detection was performed under electro-spray ionization (ESI) in multiple reaction monitoring (MRM) mode. An internal standard method was used. The extraction solvent, types of SPE cartridges and eluents were optimized by comparing the sample recoveries under different conditions. The results showed that the calibration curves of the five organophosphorus pesticides metabolites were linear in the range of 0.2–200 μg/L (r2≥ 0.992) and that of the three pyrethroid pesticides metabolites were linear in the range of 0.025–250 μg/L (r2≥ 0.991). The limits of detection (LODs, S/N ≥ 3) and the limits of quantification (LOQs, S/N ≥ 10) of the eight metabolites were 0.008–0.833 μg/L and 0.25–2.5 μg/L, respectively. The recoveries of the eight metabolites ranged from 54.08% to 82.49%. This efficient, stable, and cost-effective method is adequate to handle the large number of samples required for surveying the exposure level of organophosphorus and pyrethroid pesticides in the general population. [ABSTRACT FROM AUTHOR]

In this study, a series of monoclinic BiVO4 photocatalysts were successfully synthesised by the sol–gel method by varying pH and molar concentration. The structural and morphological properties of the synthesised BiVO4 photocatalysts were characterised by X-ray diffraction and scanning electron microscopy, respectively. The photocatalytic activity of the catalysts was evaluated by the degradation of RhB under visible-light irradiation. The results indicate that at pH = 7, the catalysts showed the best photocatalytic activity, reaching up to 90.9%. Furthermore, at 0.2M concentration, the catalysts showed the best photocatalytic activity, reaching up to 89.4%. The catalysts synthesised at different pH and molar concentrations exhibited different photocatalytic activities under visible-light irradiation because different conditions led to different degrees of crystallinity and grain distributions of monoclinic BiVO4. [ABSTRACT FROM AUTHOR]

Monoclinic BiVO4photocatalyst was successfully synthesised by sol–gel method under different temperatures and holding times. The structural and morphological properties of the synthesised BiVO4photocatalysts were characterised by X-ray diffraction and scanning electron microscopy respectively. The photocatalytic activity of the prepared catalysts was evaluated by the photodegradation of RhB under visible light irradiation. It is confirmed that the samples calcined under different temperatures and holding times exhibited different photocatalytic activity under visible light irradiation because calcination under different condition might lead to different purity of monoclinic bismuth vanadate and its grain distribution. [ABSTRACT FROM AUTHOR]

Gastrointestinal glutathione peroxidase (GI-GPx, GPx2) is a selenium-dependent enzyme and regarded as the first line of defense against oxidative stress caused by ingested pro-oxidants or gut microbes. As the essential part of the catalytic site of GPx2, selenocysteine (Sec) is encoded by an in-frame UGA stop codon, which makes the expression of human GPx2 (hGPx2) using traditional recombinant DNA technology difficult. In order to produce bioactive recombinant hGPx2, the gene of hGPx2 was designed with the conversion of the codons for four cysteine (Cys) residues to the codons for serine (Ser) residues and the codon for Sec-40 was changed to the codon for Cys. This recombinant seleno-hGPx2 mutant was obtained using a single protein production system in a cysteine (Cys) auxotrophic strain, in which Sec was introduced into the protein via tRNACys misleading. The activity of this mutant was in the same order of magnitude as that of hGPx4, but about one order of magnitude lower than that of hGPx1 and hGPx3. Further study showed that the mutant exhibited pH and temperature optima of 7.4 and 25°C, respectively. The results obtained from the kinetic analysis demonstrated that it followed a typical ping-pong mechanism similar to native GPx. As there was no report on the activity of purified GPx2, this research was valuable in recognizing native GPx2. In addition, a three-dimensional structure of seleno-hGPx2 mutant was constructed, which could facilitate further analysis of the role and the catalytic mechanism of native GPx2. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) are tiny molecules with multiple essential roles in plant growth and development. So far, numerous miRNA families, both highly conserved and species-specific, have been identified and functionally characterized. However, we are still far from a thorough understanding of these molecules, including their sequence characteristics. In this bioinformatics study,cis-acting regulatory elements located within plant miRNA promoters were predicted, and a comprehensive list of single nucleotide polymorphisms (SNPs) residing within thesecis-elements, designated ascis-regulatory SNPs, was identified. These SNPs potentially contribute to the distinct expression patterns of miRNA genes in various Arabidopsis (Arabidopsis thaliana) or rice (Oryza sativa) subspecies. Additionally, sequence conservation analysis was carried out for all the currently miRBase-registered pre-miRNAs (precursor miRNAs) belonging to numerous plant species. Together, these analyses provide a basis to gain deeper insights into the biological role of miRNA sequence characteristics. [ABSTRACT FROM AUTHOR]

In multiple-input multiple-output (MIMO) communications, mutual coupling is a notorious issue due to limited space available for mobile terminals. Most of theoretical analysis and simulation investigated the channel capacity and the performance of MIMO systems in the presence of antenna coupling. But in this paper, we have firstly experimentally studied the impact of the decoupling on channel capacity for MIMO radio communications. It is dem-onstrated that channel capacity can be enhanced by decoupling. [ABSTRACT FROM AUTHOR]

Freestanding, ion conducting, membranes were synthesized by incorporating triazole-containing tetracyclosiloxanes into a polyethylene glycol-tetraethyl orthosilicate (PEG-TEOS) based sol-gel matrix. These membranes show comparable or higher proton conductivities than their linear, liquid, polysiloxane analogs and fall within an order of magnitude of the target ion mobilities for use in proton exchange membrane fuel cells (PEMFC's). The absence of any unbound PEG or cyclic siloxane was confirmed by proton nuclear magnetic resonance (1H-NMR), while the chemical structure and composition of the membranes was corroborated by Fourier transform infrared (FTIR) spectroscopy. Thermogravimetric analysis (TGA) indicated that the membranes are stable up to 180°C and differential scanning calorimetry (DSC) analysis showed complete suppression of PEG crystallization after incorporation of the triazole-functionalized cyclosiloxanes. An increase in the molecular weight of the PEG chains used to create the sol-gel matrix produced membranes with increased flexibility and higher proton conductivities at temperatures below 100 °C. Pulse field gradient echo (PFG) NMR studies showed an increase in the apparent diffusion coefficient of the sol-gel threaded cyclosiloxane motifs compared to the linear polysiloxanes, indicating a significant reduction on the coupling between mechanical strength and ion transport capability. [ABSTRACT FROM AUTHOR]

This article proposes a new reinforcement learning method using the swarm intelligence-trained neural network (SWINN) to generate solutions to various real-world problems efficiently. The swarm intelligence algorithm, particle swarm optimisation (PSO), is combined with a training resource allocator (TRA) in SWINN for specific problems. TRA, as a heuristic global search method, controls the allocation of training resources to different candidate topologies of artificial neural networks (ANNs) to expedite the system convergence, while PSO is applied as a local search algorithm to adjust the ANNs connection weights. To evaluate the performance of the SWINN algorithm, two reinforcement learning case studies: the double pole balance (a.k.a. double inverted pendulum) problem and a mobile robot localisation problem are conducted. Extensive simulation results successfully demonstrate that SWINN offers performance that is competitive with modern neuroevolutionary techniques, and is viable for real-world problems. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA) being the main mineral constituent of human hard tissues is highly bioactive. Good chemical bonds can be generated between HA and natural bone. However, the low strength and inherent brittleness of HA restrict its application usually to non-load-bearing conditions. In this work, production of a new kind of HA–ZrO2 composite by hot-press sintering method is described. Bioglass which has been widely used in reconstruction of damaged or diseased tissues was added into HA–ZrO2 composites. Comparing with pure HA ceramic, this type of composite possesses better mechanical strength and retains the bioactivity of HA as well. The liquid phase generated by bioglass has been effective in improving the sintering process of HA–ZrO2 composites. The phase composition of HA composite was characterized by XRD and their fracture surfaces were observed by SEM. The XRD results show that introducing a small amount of bioglass into HA–ZrO2 composite cannot enhance decomposition of HA. The SEM images show that there were fewer pores on the fracture surfaces of HA–ZrO2–bioglass composite than in the HA–ZrO2 composite. The flexural strength and toughness of HA–ZrO2 composite containing 2 wt% bioglass were 157 MPa and 1.63 MPa·m1/2, respectively. [ABSTRACT FROM AUTHOR]

1. Compound A (3-(2-oxo-3-[3-(5,6.7,8-tetrahydro-[l,8]napthyridin-2-yl)propyl]-imidazolidin-1-yl)-3(S)-(6-methoxy-pyridin-3-yl)propionic acid), a hydrophilic zwitterion is a potent and selective αvβ3 integrin antagonist currently under clinical development for the treatment of osteoporosis. The mechanism of renal excretion of compound A was investigated using a combination of in vivo and in vitro approaches. 2. In rats, renal excretion of compound A involved tubular secretion; ratios between renal clearance, corrected for unbound fraction in plasma (CLr,u) and glomerular filtration rate (GFR) were greater than unity (2-5). The tubular secretion of compound A was saturable at high plasma levels (>26 μM), and was inhibited significantly, although modestly (about twofold) by relatively high plasma concentrations of the organic anion PAH (l60μM) and the cation cimetidine (about 400μM), but not by the P-gp inhibitor quinidine (about 50 μM). However, compound A (about 100μM) had a minimal effect on CLr/GFRs for cimetidine and PAH. 3. In rhesus monkeys, renal elimination of compound A also involved tubular secretion, with a CLr,u/GFR ratio of about 30. The renal secretion of compound A was not affected by either cimetidine (about l20μM) or PAH (about 80|μM). Similarly, compound A (about 40 μM) had a minimal effect on the renal tubular secretion of both cimetidine and PAH. 4. At the doses studied, neither rat nor monkey plasma protein binding of compound A, cimetidine or PAH was affected in the presence of each other. 5. In vitro transport studies showed that compound A was not a substrate for P-gp in the Caco-2, human MDR1 and mouse mdr1a transfected LLC-PKl cell lines. In an uptake study using rOAT1 and rOAT3 transfected HEK cell lines, compound A was shown to he a substrate for rat OAT3 (Km = 15 μM), but not rat OATl. 6. The results suggest that the tubular secretion of compound A is not mediated by P-gp, hut rather is mediated, at least in part, via the organic anion transporter OAT3, the renal transport-r shown to he capable of transporting both the organic anion PAH and the organization cimetidine. Although there is a possibility for pharmacokinetic interactions between compound A and substrates or inhibitors of OAT3, at the renal excretion level, the magnitude of interaction would likely he modest in humans at clinically relevant doses. [ABSTRACT FROM AUTHOR]

1. The disposition of 3-{2-oxo-3-[3-(5,6,7,8-tetrahydro-[1,8]naphthyridin-2-yl) propyl]-imidazolidin-1-yl}-3(S)-(6-methoxy-pyridin-3-yl)propionic acid (compound A), a potent and selective α v β 3 antagonist, was characterized in several animal species in support of its selection for preclinical safety studies and potential clinical development. 2. Compound A exhibited marked species differences in pharmacokinetics; the plasma clearances and bioavailabilities ranged from 33-47 ml min -1 kg -1 in rats and mice to 4-9 ml min -1 kg -1 in dogs and monkeys, and about 20% in rats to 70-80% in dogs and monkeys, respectively. Both the intravenous (i.v.) and oral kinetics of compound A were linear over the dose range studied in dogs (0.1-5 mg kg -1 i.v. and 0.25-20 mg kg -1 orally [p.o.]) and rats (1-30 mg kg -1 i.v. and 4-160 mg kg -1 p.o.). 3. Compound A was eliminated substantially by urinary excretion; the urinary recovery of the unchanged drug was 67% in rhesus, 48% in dogs and about 30% in rats. In these animal species, biotransformation was modest. 4. Following i.v. administration of [ 14 C]-compound A to rats, the radioactivity rapidly distributed to all tissues investigated, with high levels of the radioactivity detected in liver, kidney and intestine soon after the drug administration. The radioactivity declined rapidly, with less than 1% of the i.v. dose remaining at 30-h post-dose. 5. Compound A was moderately bound to plasma proteins, with unbound fractions of 26, 20, 14 and 5% for rats, dogs, monkeys and humans, respectively. It was bound primarily to human α 1 -acid glycoprotein (about 85% binding at 0.1% concentration), as compared with human albumin (< 50% binding at 4% concentration). 6. Using simple allometry, compound A was predicted to exhibit relatively low clearance (1-3 ml min -1 kg -1 ) and low volume of distribution (0.1-0.3 l kg -1 ) in humans. Based on the predicted values, compound A was projected to exhibit a favourable oral pharmacokinetic profile in humans, with good bioavailability (50-80%). These predicted values provided a basis for compound selection for further development. [ABSTRACT FROM AUTHOR]

1. The study investigated mechanisms underlying the pharmacokinetic differences of two zwitterionic diastereomers ((3S)-3-{( 3R or 3 S)-2-oxo-3-\[3-(5,6,7,8-tetrahydro-1,8- naphthyridin-2-yl)propyl]pyrrolidin-1-yl}-3-quinolin-3-ylpropanoic acid) with different lipophilicities using a combination of in vivo and in vitro approaches. 2. In rat, both isomers possessed comparable plasma clearances (CL). However, the more lipophilic diastereomer I exhibited a higher metabolic clearance (>2-fold higher than II), whereas the hydrophilic zwitterion II exhibited a higher biliary clearance (~5- fold higher than I). Following oral administration, the bioavailability (F) of I (17%) was much higher than that of II (1%). 3. Consistent with these in vivo observations and the expectation based on their lipophilicity differences, the metabolism in rat liver microsomes was faster and the permeability in Caco-2 and LLC-PK1 cells and in situ rat intestinal loop was better for I than for II. 4.Only the absorption of the more lipophilic diastereomer I was subjected to an efflux system in the Caco-2 and in situ rat intestinal loop models. I was a good substrate for Pglycoprotein (P-gp) in both the human MDR1 and mouse mdr1a transfected cell lines, and in the wild-type mdr1a (+/+) mouse when compared with the P-gp-deficient mdr1a (-/-) mouse. Concomitant administration of I with verapamil in rat caused significant increases in oral AUC, F and C[sub max] of I without affecting its CL, further supporting the effect of P-gp in limiting the intestinal absorption of I in vivo in this animal model. 5. Since the findings that the lipophilic diastereomer I, but not II, was a good P-gp substrate were not in line with the observations that I was excreted to bile much slower than II and that I was absorbed better than II, the results suggested that P-gp played a minor role to the observed differences in the biliary excretion and intestinal absorption of the diastereomers I and II in rat. [ABSTRACT FROM AUTHOR]