Microstructure and Hardness Properties Investigation of Ti and Nb Added FeNiAlCuCrTi x Nb y High Entropy Alloys

Properties of pure metals can be enhanced by alloying with other metallic or non-metallic elements according to the need. However, as multiple alloying elements in an alloy may lead to the formation of many intermetallic compounds with complex microstructures and poor mechanical properties, new types of metallic alloys called high entropy alloys with at least five elements with equimolar ratios were developed. In this study, FeNiAlCuCrTi _x Nb _y (x, y = 0, 0.5, 1.0, 1.5) alloys have been prepared using Ar arc melting technique. Microstructural studies using scanning electron microscope and XRD showed that Ti addition promoted secondary BCC₂ phase whereas, Nb acted as FCC stabilizer. Samples with combined Nb and Ti addition showed FCC₁ and FCC₂ structure with Nb-rich FCC₂ dendritic phase as dominant phase. Though, individual Nb and Ti additions have resulted in increased hardness, combined additions have resulted in highest hardness of 797 HV under 1 kg load.     

Thermally stable phosphonium-montmorillonite organoclays

Sodium montmorillonite (MMT) was modified with several organic phosphonium salts. Organoclays with water soluble surfactants were prepared by the traditional cation exchange reaction. An alternative procedure was used to prepare organoclays with water insoluble salts. The effect of chemical composition and molecular weight of the salts on the thermal stability and basal spacing were evaluated. The phosphonium montmorillonites exhibit higher thermal stability than conventional ammonium organoclays. The basal spacing is generally larger for the phosphonium montmorillonites. These properties provide a good potential for the use of phosphonium organoclays for the synthesis of polymer/clay nanocomposites by melt processing.     

Myth and reality of the hybrid desalination process

The paper discusses some misconceptions that have contributed to the continued use of thermal desalination processes and promotion of the hybrid desalination process for new plants being built or considered at Middle East locations. The misconceptions are examined both on the basis of fundamental thermodynamic principles and in terms of practical engineering parameters. The analysis shows that there is no economic or performance advantage in the installation of greenfield hybrid power/thermal desalination/ seawater reverse osmosis (SWRO) plants in preference to power/SWRO plants, because the latter would produce water more cheaply under all conditions and at all fuel costs, and would provide more operational flexibility than the former. The paper identifies situations where the hybrid desalination process can be fully justified: in existing power/desalination plants, where aging boilers and multistage flash (MSF) units need to be repaired or replaced, through retrofitting and repowering. In such situations, abandonment of the MSF process would result in a reduction in the power output of the plant. The paper refers to previous work which showed that the repowering of a typical existing power/desalination station with refurbishment/replacement of the MSF units, together with the addition of SWRO units, would result in a several-fold increase in the water and power output and a dramatic improvement in the fuel efficiency, without any additions to the existing seawater intake system. The paper emphasizes the importance of test stations/demonstration plants at existing power/desalination stations in the Middle East in order to obtain data and make improvements in the technology of higher temperature SWRO, with the feed obtained from the cooling water returning from the power plant condenser and the thermal desalination plant. The paper shows that the potential benefits would easily justify the investment in research and development required to validate this concept.     

Anthranilamide-pyrazolo[1,5-a]pyrimidine conjugates as p53 activators in cervical cancer cells

A library of new anthranilamide-pyrazolo[1,5-a]pyrimidine conjugates were designed, synthesized, and evaluated for their anticancer activity in cervical cancer cells such as HeLa and SiHa that possess low levels of p53. All 24 conjugates showed antiproliferative activity, while some of them exhibit significant cytotoxicity. In assays related to cell-cycle distribution, these conjugates induced G(2) /M arrest in HeLa cells and G(1) cell-cycle arrest in SiHa cells. Immunocytochemistry assays revealed that these compounds cause nuclear translocation of p53, thereby indicating the activation of p53. In cervical cancer cells, the p53 protein is degraded by E6 oncoprotein. Immunoblot and RT-PCR analyses proved the presence of mitochondria-mediated apoptosis with involvement p53 target genes such as BAX, Bcl2, and p21 (CDKI). Moreover, these compounds increased the phosphorylated forms of p53 and provide signals for apoptosis induction. Interestingly, one of the conjugates, (2-phenyl-7-(3,4,5-trimethoxyphenyl)pyrazolo[1,5-a]pyrimidin-5-yl)(4-(2-(thiophen-2-ylmethylamino)benzoyl)piperazin-1-yl)methanone, is the most promising candidate in this series and has the potential to be taken up for further detailed studies.     

Assessment of a regulatory sanitization process in Egyptian dairy plants in regard to the adherence of some food-borne pathogens and their biofilms

Food-borne pathogens may develop certain strategies that enable them to defy harsh conditions such as chemical sanitization. Biofilm formation represents a prominent one among those adopted strategies, by which food-borne pathogens protect themselves against external threats. Thus, bacterial biofilm is considered as a major hazard for safe food production. This study was designed to investigate the adherence and the biofilm formation ability of some food-borne pathogens on stainless steel and polypropylene surfaces using chip assay, and to validate regular sanitizing process (sodium hypochlorite 250mg/L) for effective elimination of those pathogens. Sixteen pathogenic bacterial strains, previously isolated from raw milk and dairy products at Zagazig city, Egypt (9 Staphylococcus aureus, 4 Cronobacter sakazakii and 3 Salmonella enterica serovar Typhimurium), were chosen for this study. Strains showed different patterns of adherence and biofilm formation on tested surfaces with minor significance between surfaces. The ability of sodium hypochlorite to completely eradicate either adhered or biofilm-embedded pathogens varied significantly depending on the strain and type of surface used. Whilst, sodium hypochlorite reduced tested pathogens counts per cm(2) of produced biofilms, but it was not able to entirely eliminate neither them nor adherent Cronobacter sakazakii to stainless steel surface. This study revealed that biofilm is considered as a sustainable source of contamination of dairy products with these pathogens, and also emphasized the need of paying more attention to the cleaning and sanitizing processes of food contact surfaces.     

Unraveling a mechanism of honey antibacterial action: Polyphenol/H2O2-induced oxidative effect on bacterial cell growth and on DNA degradation

Several compounds with antibacterial activities were identified in honey however, a mechanism by which they lead to bacterial growth inhibition and bacterial death remains still unknown. We recently found that honeys possess DNA degrading activity mediated by honey hydrogen peroxide and an unknown honey component(s). Here we provide evidence that active honeys (MIC₉₀ of 6.25–12.5% v/v) possessed significantly higher levels of phenolics (p < 0.02) of higher radical scavenging activities (p < 0.005) than honeys of average activity. Removal of H₂O₂ by catalase eliminated bacteriostatic activities caused by both phenolics and H₂O₂ suggesting that the growth inhibition resulted from the coupling chemistry between these compounds. Both phenolics and H₂O₂ were involved in DNA degradation by honeys. Treatment of plasmid DNA with H₂O₂ alone did not affect the DNA integrity but H₂O₂ removal from honey by catalase prevented DNA degradation. Polyphenols extracted from honeys degraded plasmid DNA in the presence of H₂O₂ and Cu(II) in the Fenton-type reaction. The extent of DNA degradation was inversely related to the polyphenol concentration in this system as well as in honeys. At low content, honey polyphenols exerted pro-oxidant activity damaging to DNA. In conclusion, honey phenolics with pro-oxidant activities were necessary intermediates that conferred oxidative action of H₂O₂. Phenolic/H₂O₂-induced oxidative stress constituted the mechanism of honey bacteriostatic and DNA damaging activities.     

Breakthrough studies with mono- and binary-metal ion systems comprising of Fe(II) and As(III) using community prepared wooden charcoal packed columns

Groundwater of Assam (India) contains excessive amounts of As(III) and Fe(II). The rural and semi-urban population of Assam uses indigenous household iron filters fabricated using community prepared wooden charcoal (CPWC) to reduce Fe(II) concentration, however no efforts are made to reduce As(III) concentrations before use. The present work is directed toward assessing the potential of CPWC for metal removal from mono- and binary-metal ion systems comprising of Fe(II) and As(III) through continuous mode column studies. A decrease in breakthrough throughput volumes (V_B) from mono- and binary-metal ion systems is observed with increase in flow rates and decrease in bed depths. The order of breakthrough of metal ions observed as As(III) followed by Fe(II) from binary-metal ion system and hence the V_B for As(III) is termed as critical V_B as Fe(II) is yet to breakthrough through the beds. An early breakthrough for Fe(II) and As(III) from binary-metal ion system compared to respective mono-metal ion systems is observed for all the cases of flow rates and bed depths. It indicates impact on the uptake of a selected metal ion [either Fe(II) or As(III)] by the presence of the other metal ion [either As(III) or Fe(II)] present in the binary-metal ion system. The minimum and maximum errors involved between the predicted and experimental BDST curves for As(III) uptake till critical V_B from the binary-metal ion system varied between 1.0% and 24.8%.     

Manual small incision cataract surgery for subluxated cataract with lens coloboma

Introduction

The lens coloboma results from a segmental defective or absent development of the zonules. It is usually unilateral and bilateral cases are rare. These eyes are at greater risk of complications during cataract surgery due to ocular malformations. In addition the capsular bag requires stabilization using modified capsule tension ring, capsular tension segment or capsular anchor.

Methods

Lens extraction is indicated for cataract or subluxation if visual function is sufficiently compromised. We report our surgical experience in a patient with bilateral isolated lens coloboma by performing manual small incision cataract surgery (MSICS) in left eye and phacoemulsification in right eye.

Results

The nuclear rotation was hampered because of the lack of zonules and presence of lens coloboma. MSICS was converted to the intracapsular technique in left eye, though breaking the nucleus into pieces during phacoemulsification in right eye enabled its mobilization and successful completion with implantation of modified capsule tension ring.

Conclusions

A patient with lens subluxation and lens coloboma is better managed by phacoemulsification as compared to the MSICS.     

The operational mechanism of ferroelectric-driven organic resistive switches

The availability of a reliable memory element is crucial for the fabrication of ‘plastic’ logic circuits. We use numerical simulations to show that the switching mechanism of ferroelectric-driven organic resistive switches is the stray field of the polarized ferroelectric phase. The stray field modulates the charge injection from a metallic electrode into the organic semiconductor, switching the diode from injection limited to space charge limited. The modeling rationalizes the previously observed exponential dependence of the on/off ratio on injection barrier height. We find a lower limit of about 50 nm for the feature size that can be used in a crossbar array, translating into a rewritable memory with an information density of the order of 1 Gb/cm².     

Identification and characterization of novel α-amylase and α-glucosidase inhibitory peptides from camel whey proteins

This study explores the inhibitory properties of camel whey protein hydrolysates (CWPH) toward α-amylase (AAM) and α-glucosidase (AG). A general full factorial design (3 × 3) was applied to study the effect of temperature (30, 37, and 45°C), time (120, 240, and 360 min), and enzyme (pepsin) concentration (E%; 0.5, 1, and 2%). The results showed that maximum degree of hydrolysis was obtained when hydrolysis was carried out at higher temperature (45°C; P < 0.05), compared with lower temperatures of 30 and 37°C. Electrophoretic pattern displays degradation of all protein bands upon hydrolysis by pepsin at various hydrolysis conditions applied. All the 27 CWPH generated showed significant AAM and AG inhibitory potential as indicated by their lower IC₅₀ values (mg/mL) compared with intact whey proteins. In total 196 peptides were identified from selected hydrolysates and 15 potential peptides (PepSite score > 0.8; http://pepsite2.russelllab.org/) were explored via in silico approach. Novel peptides PAGNFLMNGLMHR, PAVACCLPPLPCHM, MLPLMLPFTMGY, and PAGNFLPPVAAAPVM were identified as potential inhibitors for both AAM and AG due to their high number of binding sites and highest binding probability toward the target enzymes. CCGM and MFE, as well as FCCLGPVPP were identified as AG and AAM inhibitory peptides, respectively. This is the first study that reports novel AG and AAM inhibitory peptides from camel whey proteins. The future direction for this research involves synthesis of these potential AG and AAM inhibitory peptides in a pure form and investigate their antidiabetic properties in the in vitro, as well as in vivo models. Thus, CWPH can be considered for potential applications in glycaemic regulation.