Experimental development of clay liners for waste containment in arid and semi arid regions

ABSTRACT

The leachate from municipal solid waste, during or after rainfall, through desiccation cracks may contaminate underground aquifers in arid and semiarid regions. This experimental study proposes modified clay liners to control leachate contamination from waste. The test specimens of clay liners were prepared using a mixture of locally available clay, sand, cement and polyethylene chips to reduce the shrinkage potential. Microstructural analysis was also conducted by using Energy Dispersive X-Ray and X-Ray Diffraction. Scanning Electronic Microscopy tests were conducted to find chemical composition and microstructure of unmodified and modified soil specimens. These tests confirmed the presence of montmorillonite clay minerals that have high potential for swelling and thus volumetric shrinkage. The study proposes a combination of 15% sand, 4% cement and 0.5% polyethylene chips to reduce shrinkage potential from 17% to less than 4%. However, the effect of modification on hydraulic conductivity with water and leachate was not very significant. Based on statistical analysis, fair correlations were found between mixture composition and volumetric shrinkage.     

Comparative lyophilized platelet-rich plasma wafer and powder for wound-healing enhancement: formulation,in vitro and in vivo studies

Platelet-rich plasma (PRP) accelerates wound healing, as it is an excellent source of growth factors. PRP was separated from whole human blood by centrifugation. PRP powder and wafers were prepared by lyophilization, with the wafers prepared using sodium carboxymethylcellulose (Na CMC). The PRP wafers showed porous structures, as indicated by scanning electron microscopy (SEM) images, and the ability of the wafer to absorb exudates and thus promote wound healing was tested with the hydration capacity test. The platelet count was tested and indicated that the presence of PRP in the wafers had no effect on the platelet count. An antimicrobial activity test was carried out, showing that PRP had antibacterial activity against Gram-negative bacteria. Compared with lyophilized PRP powder and PRP-free wafers, PRP wafers showed the highest percent of wound size reduction on induced wounds in rats. Histopathological examination of rat skin showed that the PRP wafers achieved the shortest healing time, followed by the lyophilized PRP powder and finally the PRP-free wafers. The present study revealed that PRP can be formulated as a wafer, which is a promising pharmaceutical delivery system that can be used for enhanced wound-healing activity and improved the ease of application compared to lyophilized PRP powder.     

SAR by oxime-containing peptide libraries: application to Tsg101 ligand optimization

HIV-1 viral assembly requires a direct interaction between a Pro-Thr-Ala-Pro ("PTAP") motif in the viral protein Gag-p6 and the cellular endosomal sorting factor Tsg101. In an effort to develop competitive inhibitors of this interaction, an SAR study was conducted based on the application of post solid-phase oxime formation involving the sequential insertion of aminooxy-containing residues within a nonamer parent peptide followed by reaction with libraries of aldehydes. Approximately 15-20-fold enhancement in binding affinity was achieved by this approach.     

MHD flow and heat transfer of a micropolar fluid over a nonlinear stretching surface with variable surface heat flux and heat generation

An analysis has been carried out to study magnetohydrodynamic boundary layer flow and heat transfer of an electrically conducting micropolar fluid over a nonlinear stretching surface with variable wall heat flux in the presence of heat generation/absorption and a non‐uniform transverse magnetic field. The governing system of partial differential equations is first transformed into a system of ordinary differential equations using similarity transformation. The transformed equations are solved numerically. Results for the dimensionless velocity, micro‐rotation, and temperature profiles are displayed graphically delineating the effects of various parameters characterising the flow. The results show that the velocity profile decreases as the magnetic parameter and the velocity exponent increase, while it increases as the material parameter increases. The results show also that the temperature profile increases as the magnetic parameter, the velocity exponent, and the heat generation parameter increase. Furthermore, the temperature profile decreases as the material parameter, the heat absorption parameter, and the Prandtl number increase.     

Metal-assisted etching of p-silicon—Pore formation and characterization

Etching of silicon and formation of definite porous surfaces can be carried out by different methods. Metal-assisted etching represents a convenient method for the application of induced etching for beneficial applications. Porous silicon layers (PSL) on Si are useful and important in solar energy conversion and optoelectronics. Porous silicon on silicon increases the effective area and thus higher optical absorption as well as solar conversion efficiency can be achieved. The effective optical properties of PSL have found great interest in optoelectronics. In the last few years PSL of definite pore structures have been prepared by metal-assisted etching of p-Si in aqueous hydrofluoric acid solutions containing different oxidizing agents. Potassium dichromate, at definite concentration and after optimum etching time of p-Si on which Pt nuclei were electroless deposited, has shown promising effects. The effect of etching time, K₂Cr₂O₇ concentration and HF concentration on the main characteristics of the porous structure was investigated and discussed. In this respect electrochemical impedance spectroscopy (EIS) was used. The experimental data were fitted to theoretical data according to a proposed electrical equivalent circuit model. The morphology of the formed layers and surface contaminations were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques.The results have shown that PSL with nano and micro pores were formed on p-Si when etched in HF-K₂Cr₂O₇ aqueous solutions. At 22.0 mol L⁻¹ HF and relatively high concentration of K₂Cr₂O₇ [>0.05 mol L⁻¹] a passive K₂SiF₆ layer was formed on the Si surface with a thickness that is affected by the concentrations of both HF and K₂Cr₂O₇. The passive K₂SiF₆ layer reduces the effectiveness of the PSL in both the solar conversion process and also its electrical and optical characteristics.     

Detection of Porphyrins in Hair Using Capillary Liquid Chromatography-Mass Spectrometry

Unlike humans, some animals have evolved a physiological ability to deposit porphyrins, which are pigments produced during heme synthesis in cells, in the skin and associated integument such as hair. Given the inert nature and easiness of collection of hair, animals that present porphyrin-based pigmentation constitute unique models for porphyrin analysis in biological samples. Here we present the development of a simple, rapid, and efficient analytical method for four natural porphyrins (uroporphyrin I, coproporphyrin I, coproporphyrin III and protoporphyrin IX) in the Southern flying squirrel Glaucomys volans, a mammal with hair that fluoresces and that we suspected has porphyrin-based pigmentation. The method is based on capillary liquid chromatography-mass spectrometry (CLC-MS), after an extraction procedure with formic acid and acetonitrile. The resulting limits of detection (LOD) and quantification (LOQ) were 0.006–0.199 and 0.021–0.665 µg mL⁻¹, respectively. This approach enabled us to quantify porphyrins in flying squirrel hairs at concentrations of 3.6–353.2 µg g⁻¹ with 86.4–98.6% extraction yields. This method provides higher simplicity, precision, selectivity, and sensitivity than other methods used to date, presenting the potential to become the standard technique for porphyrin analysis.     

Cytotoxic T Cell Expression of Leukocyte-Associated Immunoglobulin-Like Receptor-1 (LAIR-1) in Viral Hepatitis C-Mediated Hepatocellular Carcinoma

Virus-related hepatocellular carcinoma (HCC) pathogenesis involves liver inflammation, therefore, despite successful treatment, hepatitis C virus (HCV) may progress to HCC from initiated liver cirrhosis. Cytotoxic T cells (Tcs) are known to be involved in HCV-related cirrhotic complications and HCC pathogenesis. The inhibitory checkpoint leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1) is expressed on Tcs. Therefore, we aimed to determine whether the Tc expression level of LAIR-1 is associated with HCC progression and to evaluate LAIR-1 expression as a noninvasive biomarker for HCC progression in the context of liver cirrhosis related to HCV genotype 4 (G4) in Egyptian patients’ peripheral venous blood liquid biopsy. A total of 64 patients with HCC and 37 patients with liver cirrhosis were enrolled in this case-controlled study, and their LAIR-1 expression on Tc related to the progression of liver cirrhosis was examined and compared to that of the apparently healthy control group (n = 20). LAIR-1 expression was analyzed using flow cytometry. Results: The HCC group had significantly higher LAIR-1 expression on Tc and percentage of Tc positive for LAIR-1 (LAIR-1+Tc%) than the HCV G4-related liver cirrhosis group. LAIR-1+Tc% was correlated with the HCC surrogate tumor marker AFP (r = 0.367, p = 0.001) and insulin resistance and inflammation prognostic ratios/indices. A receiver operating characteristic (ROC) curve revealed that adding LAIR-1+Tc% to AFP can distinguish HCC transformation in the Egyptian patients’ cohort. Upregulated LAIR-1 expression on Tc could be a potential screening noninvasive molecular marker for chronic inflammatory HCV G4 related liver cirrhosis. Moreover, LAIR-1 expression on Tc may be one of the players involved in the progression of liver cirrhosis to HCC.     

High-Throughput Sequencing Reveals Novel microRNAs Involved in the Continuous Flowering Trait of Longan (Dimocarpus longan Lour.)

A major determinant of fruit production in longan (Dimocarpus longan Lour.) is the difficulty of blossoming. In this study, high-throughput microRNA sequencing (miRNA-Seq) was carried out to compare differentially expressed miRNAs (DEmiRNAs) and their target genes between a continuous flowering cultivar ‘Sijimi’ (SJ), and a unique cultivar ‘Lidongben’ (LD), which blossoms only once in the season. Over the course of our study, 1662 known miRNAs and 235 novel miRNAs were identified and 13,334 genes were predicted to be the target of 1868 miRNAs. One conserved miRNA and 29 new novel miRNAs were identified as differently expressed; among them, 16 were upregulated and 14 were downregulated. Through the KEGG pathway and cluster analysis of DEmiRNA target genes, three critical regulatory pathways, plant–pathogen interaction, plant hormone signal transduction, and photosynthesis-antenna protein, were discovered to be strongly associated with the continuous flowering trait of the SJ. The integrated correlation analysis of DEmiRNAs and their target mRNAs revealed fourteen important flowering-related genes, including COP1-like, Casein kinase II, and TCP20. These fourteen flowering-related genes were targeted by five miRNAs, which were novel-miR137, novel-miR76, novel-miR101, novel-miR37, and csi-miR3954, suggesting these miRNAs might play vital regulatory roles in flower regulation in longan. Furthermore, novel-miR137 was cloned based on small RNA sequencing data analysis. The pSAK277-miR137 transgenic Arabidopsis plants showed delayed flowering phenotypes. This study provides new insight into molecular regulation mechanisms of longan flowering.     

Production of butanol and polyhydroxyalkanoate from industrial waste by Clostridium beijerinckii ASU10

This study demonstrated a biotechnological approach for simultaneous production of low‐cost H₂, liquid biofuels, and polyhydroxyalkanoates (PHAs) by solventogenic bacterium (Clostridium beijerinckii) from renewable industrial wastes such as molasses and crude glycerol. C beijerinckii ASU10 (KF372577) exhibited considerable performance for hydrogen production of 5.1 ± 0.84 and 11 ± 0.44 mL H₂ h^?1 on glycerol and sugarcane molasses, respectively. The total acetone‐butanol‐ethanol (ABE) generation from glycerol and molasses was 9.334 ± 2.98 and 10.831 ± 4.1 g L^?1, respectively. ABE productivity (g L^?1 h^?1) was 0.0486 and 0.0564 with a yield rate (g g^?1) up to 0.508 and 0.493 from glycerol and molasses fermentation, respectively. The PHA yields from glycerol and sugarcane molasses were 84.37% and 37.97% of the dried bacterial biomass, respectively. Additionally, the ultrathin section of C beijerinckii ASU10 showed that PHA granules were accumulated more densely on glycerol than molasses. Gas chromatography–mass spectrometry (GC‐MS) analysis confirmed that the PHAs obtained from molasses fermentation included 3‐hydroxybutyrate (47.3%) and 3‐hydroxyoctanoate (52.7%) as the main constituents. Meanwhile, 3‐hydroxybutyrate represented the sole monomer of PHA produced from glycerol fermentation. This study demonstrated that C beijerinckii ASU10 (KF372577) is a potent strain for low‐cost PHA production depending on its high potential to produce high‐energy biofuel and other valuable compounds from utilization of organic waste materials.