Structural, FTIR spectra and optical properties of pure and co-doped Zn1-x-y Fe x M y O ceramics with (M = Cu, Ni) for plastic deformation and optoelectronic applications

We report here a considered novel study on the structural, FTIR spectra and optical properties of pure and co-doped Zn0.90-x Fe0.1M x O with ((M = Cu, Ni and (x = 0.00, 0.10) and (0.00 < y < 0.20)) at different sintering temperatures T s (T s  = 850 °C for series I and 1000 °C series II). Although the ZnO wurtzite structure is conformed for all samples, some secondary lines with little intensity are formed. But the number of these lines is higher for series I than for series II. The (c/a) value and U-parameter are almost constant for all samples, while Zn-O bond length L is slightly increased. The porosity and crystallite size are decreased by Fe, and also for (Fe + Cu) samples, and their values for series I are lower than for series II. The residual stress is tensile for most samples. Interestingly, the Young's, rigid and bulk modulus, Poisson's ratio and Debye temperature, obtained from FTIR analysis, are increased by Fe addition with a further increase for Fe + Ni) samples for both series. A ductile nature is obtained for pure, Fe and (Fe + Cu) samples; whereas a brittle nature is approved for (Fe + Ni) samples. On the other hand, the energy gap (E g ), residual lattice dielectric constant (ε L ) and carrier density N are increased by Fe addition, followed by a further increase for (Fe + Cu) samples, while the vice is versa for the inter-atomic distance R. For example, E g was increased from 3.153 eV for pure ZnO to 3.974 eV for (Fe + Cu) samples (i.e., 0.821 eV more), while it was decreased to 2.851 eV for (Fe + Ni) samples (i.e., 0.302 eV less). A direct behavior is obtained between E g and both elastic modulus (Y, β), lattice and micro strains (ε L , ε m ), dislocation density (δ), residual stress (σ) and carrier density N, whereas a reverse behavior is obtained between E g and both crystallite size (D), porosity (PS) and inter-atomic distance (R) . These results are explained in terms of the generated blocked states of the conduction band as indicated by the Burstein Moss effect. These novel findings reveal that the co-doping has intense ZnO and moderate metal oxide modes in the ZnO matrix structure, which makes ZnO co-doped with (Fe + Cu) more suitable for gas sensors and optoelectronic devices. In contrast, ZnO co-doped with (Fe + Ni) samples is strongly recommended for altering plastic deformation. To our knowledge, the present investigation can be considered the first study and probably has never been discussed elsewhere, which highlights the present investigation.

Structural morphology and nonlinear behavior of pure and co-doped Zn1-x-yFexMyO varistors with (M = Cu, Ni)

We report here structural morphology and nonlinear behavior of pure and co-doped Zn_0.90-xFe_0.1M_xO with (M = Cu, Ni and (x = 0.00, 0.10) and (0.00 ≤ y ≤ 0.20)) at different sintering temperatures (T _s = 850 and 1000 °C). It is found that the co-doping of ZnO by (Fe + Cu) or (Fe + Ni) up to 0.30 does not deform the well-known wurtzite structure of ZnO, as well as pure and 0.1 of Fe-doped ZnO. The SEM micrographs did not show any secondary phases at the boundaries of grains as compared to ZnO, the average grain size is decreased for Fe and (Fe + Cu) samples, while it is increased for (Fe + Ni) samples. The nonlinear coefficient α and breakdown field E _B are generally increased by 0.1 of Fe addition, but they are shifted to lower values as T _s increases for all samples. Furthermore, they are gradually increased/decreased to higher/lower values for (Fe + Cu/Fe + Ni) samples up to 0.30 of co-doping content. The values of α and E _B are increased from 30.06, 2115.38 V/cm for ZnO at 850 °C to 50.07, 5012 V/cm by (0.1Fe + 0.2Cu) co-doping, and from 23.53, 1956.52 V/cm to 45.58, 4750 V/cm at 1000 °C, while they are, respectively, decreased by (0.1Fe + 0.2Ni) to 13.19, 312 V/cm and 11.85, 172.42 V/cm. Similar behavior was generally obtained for nonlinear conductivity σ _L and height of potential barrier φ_B, whereas the vice is versa for the behavior of leakage current J _k and residual voltage K _r. Our results are discussed in terms of the comparative participation between the effects of co-doping of (Fe + Cu) and (Fe + Ni) to ZnO for supporting the potential barrier as compared to individual doping by Fe, Cu and Ni. This study perhaps recommended these samples for optoelectronic and ferromagnetic investigation after COVID-19 is over.

Numerical Evaluation of Combustion Regimes in a GDI Engine

There is significant interest in the gasoline direct-injection engine due to its potential for improvements in fuel consumption but it still remains an area of active research due to a number of challenges including the effect of cycle-by-cycle variations. The current paper presents the use of a 3D-CFD model using both the RANS and LES turbulence modelling approaches, and a Lagrangian DDM to model an early fuel injection event, to evaluate the regimes of combustion in a gasoline direct-injection engine. The velocity fluctuations were investigated as an average value across the cylinder and in the region between the spark plug electrodes. The velocity fluctuations near the spark plug electrodes were seen to be of lower magnitude than the globally averaged fluctuations but exhibited higher levels of cyclic variation due to the influence of the spark plug electrode and the pent-roof geometry on the in-cylinder flow field. Differences in the predicted flame structure due to differences in the predicted velocity fluctuations between RANS and LES modelling approaches were seen as a consequence of the inherently higher dissipation levels present in the RANS methodology. The increased cyclic variation in velocity fluctuations near the spark plug electrodes in the LES predictions suggested significant variation in the relative strength of the in-cylinder turbulence and that may subsequently result in a thickening of the propagating flame front from cycle-to-cycle in this region. Throughout this paper, the numerical results were validated against published experimental data of the same engine geometry under investigation.

Pharmacokinetics of 3′-azido-2′,3′-dideoxy-5-methylcytidine in Rats

3′-Azido-2′,3′-dideoxy-5-methylcytidine (AzddMeC) has been shown to have potent activity against human immunodeficiency virus (HIV) in vitro. The purpose of this study was to characterize the pharmacokinetics of AzddMeC in rats. AzddMeC was administered intravenously at doses of 10, 50 and 100 mg kg−1. Plasma and urine AzddMeC concentrations were determined by HPLC. Pharmacokinetic parameters were generated by area/moment analysis. Plasma AzddMeC concentrations after 10mg kg−1 were too low to accurately calculate pharmacokinetic parameters. Following 50 and 100mg kg−1 AzddMeC, plasma drug concentrations declined rapidly with a terminal half-life of approximately 2.5 h. No statistically significant differences were noted in pharmacokinetic parameters between the two higher doses. Total clearance was 1.57 ± 0.33 (mean ± SD) and 1.76 ± 0.32I h−1 kg−1 after 50 and 100 mg kg−1 AzddMeC, respectively. Renal excretion accounted for approximately half of total clearance with 55 ± 11% of the dose recovered as unchanged drug in urine. AzddMeC was not metabolized by deamination to AZT in the rat. No glucuronide metabolite was found in urine. Steady-state volume of distribution of AzddMeC averaged 1.73 ± 0.78 and 1.46 ± 0.441 kg−1 following 50 and 100 mg kg−1, respectively. Thus, the disposition of AzddMeC in rats is independent of dose over the range of 50–100 mg kg−1. The pharmacokinetics of AzddMeC in rats are similar to those of 2′,3′-dideoxycytidine, while the clearance of AzddMeC is 40% less than that of 3′-azido-3′-deoxythymidine.

Positional cloning of rp2 QTL associates the P450 genes CYP6Z1, CYP6Z3 and CYP6M7 with pyrethroid resistance in the malaria vector Anopheles funestus

Pyrethroid resistance in Anopheles funestus is threatening malaria control in Africa. Elucidation of underlying resistance mechanisms is crucial to improve the success of future control programs. A positional cloning approach was used to identify genes conferring resistance in the uncharacterised rp2 quantitative trait locus (QTL) previously detected in this vector using F6 advanced intercross lines (AIL). A 113 kb BAC clone spanning rp2 was identified and sequenced revealing a cluster of 15 P450 genes and one salivary protein gene (SG7-2). Contrary to A. gambiae, AfCYP6M1 is triplicated in A. funestus, while AgCYP6Z2 orthologue is absent. Five hundred and sixty-five new single nucleotide polymorphisms (SNPs) were identified for genetic mapping from rp2 P450s and other genes revealing high genetic polymorphisms with one SNP every 36 bp. A significant genotype/phenotype association was detected for rp2 P450s but not for a cluster of cuticular protein genes previously associated with resistance in A. gambiae. QTL mapping using F6 AIL confirms the rp2 QTL with an increase logarithm of odds score of 5. Multiplex gene expression profiling of 15 P450s and other genes around rp2 followed by individual validation using qRT–PCR indicated a significant overexpression in the resistant FUMOZ-R strain of the P450s AfCYP6Z1, AfCYP6Z3, AfCYP6M7 and the glutathione-s-transferase GSTe2 with respective fold change of 11.2, 6.3, 5.5 and 2.8. Polymorphisms analysis of AfCYP6Z1 and AfCYP6Z3 identified amino acid changes potentially associated with resistance further indicating that these genes are controlling the pyrethroid resistance explained by the rp2 QTL. The characterisation of this rp2 QTL significantly improves our understanding of resistance mechanisms in A. funestus.

Effect of soaking, germination, cooking and fermentation on antinutritional factors in cowpeas

The present work deals with the study of efficacy of some treatments, namely soaking (in water and bicarbonate solution), ordinary and pressure cooking, germination and fermentation in reducing or removal of antinutritional factors usually present in cowpeas (protease inhibitors, tannins, phytic acid and flatus-producing oligosaccharides (raffinose and stachyose). The results showed that long-time soaking (16 h) in bicarbonate solution caused remarkable reduction in the antinutritional factors. Pressure cooking was more effective than ordinary. Cooking pregerminated cowpeas was most effective. Fermentation completely removed trypsin inhibitor, oligosaccharides and reduced remarkably phytic acid. However, tannins noticeably increased.

Requirement for three novel protein complexes in the absence of the Sgs1 DNA helicase in Saccharomyces cerevisiae

The Saccharomyces cerevisiae Sgs1 protein is a member of the RecQ family of DNA helicases and is required for genome stability, but not cell viability. To identify proteins that function in the absence of Sgs1, a synthetic-lethal screen was performed. We obtained mutations in six complementation groups that we refer to as SLX genes. Most of the SLX genes encode uncharacterized open reading frames that are conserved in other species. None of these genes is required for viability and all SLX null mutations are synthetically lethal with mutations in TOP3, encoding the SGS1-interacting DNA topoisomerase. Analysis of the null mutants identified a pair of genes in each of three phenotypic classes. Mutations in MMS4 (SLX2) and SLX3 generate identical phenotypes, including weak UV and strong MMS hypersensitivity, complete loss of sporulation, and synthetic growth defects with mutations in TOP1. Mms4 and Slx3 proteins coimmunoprecipitate from cell extracts, suggesting that they function in a complex. Mutations in SLX5 and SLX8 generate hydroxyurea sensitivity, reduced sporulation efficiency, and a slow-growth phenotype characterized by heterogeneous colony morphology. The Slx5 and Slx8 proteins contain RING finger domains and coimmunoprecipitate from cell extracts. The SLX1 and SLX4 genes are required for viability in the presence of an sgs1 temperature-sensitive allele at the restrictive temperature and Slx1 and Slx4 proteins are similarly associated in cell extracts. We propose that the MMS4/SLX3, SLX5/8, and SLX1/4 gene pairs encode heterodimeric complexes and speculate that these complexes are required to resolve recombination intermediates that arise in response to DNA damage, during meiosis, and in the absence of SGS1/TOP3.

Pharmacokinetics and metabolism of racemic 2',3'-dideoxy-5-fluoro-3'-thiacytidine in rhesus monkeys

2',3'-Dideoxy-5-fluoro-3'-thiacytidine (FTC) is a nucleoside analog that selectively inhibits human immunodeficiency and hepatitis B viruses in vitro. In this study, the preclinical pharmacokinetics of racemic FTC in rhesus monkeys following intravenous and oral administration were characterized. The terminal half-life of FTC was independent of the route of administration and averaged 1.34 +/- 0.18 h (mean +/- standard deviation). Total clearance of FTC was moderate to high, averaging 1.49 +/- 0.24 liters/h/kg. Qualitative assessment of urine samples suggests that renal excretion of unchanged FTC was the major route of elimination of the nucleoside. The compound was also eliminated by metabolism and the deaminated biotransformation product 2,3'-dideoxy-5-fluoro-3'-thiauridine (FTU) was detected in serum and urine. This metabolite has no antiviral activity in human lymphocytes and liver cells. FTC and the metabolite FTU were conjugated, to a minor extent yielding the corresponding glucuronides. No 5-fluorouracil was detected in serum or urine. This is consistent with chromatographic studies using a chiral column that indicated that when racemic FTC is treated with cellular cytidine-deoxycytidine deaminase, the D-(+)-enantiomer of FTC is slowly deaminated to D-(+)-FTU, whereas the L-(-)-enantiomer is essentially resistant to this enzyme. The steady-state volume of distribution of FTC in serum averaged 2.23 +/- 0.42 liters/kg, and the nucleoside analog was distributed into the cerebrospinal fluid, which suggests that this drug penetrated the blood-brain barrier. Absorption of FTC after oral administration was rapid, with bioavailability averaging 73 +/- 6%. Taken together, the results indicate that the unusual L-(-)-enantiomer of FTC should be evaluated further in rhesus monkeys prior to determination of whether this compound is useful for treatment of human immunodeficiency and hepatitis B virus infections.

Pharmacokinetic evaluation of (-)-6-aminocarbovir as a prodrug for (-)-carbovir in rats

The recently synthesized carbocyclic 2',3'-didehydro-2',3'-dideoxy-6-deoxy-6-amino-guanosine [(-)6AC] was evaluated as a prodrug for carbovir, carbocyclic 2',3'-didehydro-2',3'-dideoxyguanosine [(-)CBV] in seven male Sprague-Dawley rats. A randomized three-way cross-over design was used. Rats were assigned to receive the following treatments: a 20 mg/kg (-)6AC infusion, 40 mg/kg (-)6AC orally, and a 20 mg/kg (-)CBV infusion. Blood samples were collected over 480 min, and urine was collected for up to 48 hr. A 2- to 3-day washout period was observed between treatments. Following i.v. infusion, (-)6AC concentrations in the blood declined rapidly in a monoexponential pattern with an elimination half-life of 11.3 +/- 3.3 min (mean +/- SD, n = 7). The time-averaged total body clearance was 115.7 +/- 32.6 ml/min/kg. The fraction of the dose excreted unchanged in urine was 0.28 +/- 0.06. The fraction of the (-)6AC dose metabolized to (-)CBV was 0.48 +/- 0.14. Following oral administration of (-)6AC, the bioavailability of (-)CBV was 46.2 +/- 9.9% (n = 6) in comparison with the bioavailability of approximately 20% previously obtained after an oral dose of (-)CBV. The Cmax of (-)CBV after a 40 mg/kg oral dose of (-)6AC was 1.65 +/- 0.7 micrograms/ml as compared with the previously reported Cmax of 1.00 microgram/ml obtained after a 60 mg/kg oral dose of (-)CBV. (-)6AC has considerable potential for the improvement of the extent of absorption of (-)CBV from oral dosing.

Pharmacokinetics of 2',3'-dideoxycytidine after high-dose administration to rats

The pharmacokinetics of 2',3'-dideoxycytidine (DDC) was characterized after iv administration of a high dose (500 mg/kg) of DDC to rats. The high dose was administered to optimally characterize plasma DDC concentration and urinary excretion rate versus time profiles. Drug concentrations in plasma and urine were determined by HPLC. Plasma DDC concentrations and DDC urinary excretion rates as a function of time were fitted simultaneously to a two-compartment model. Drug concentrations in plasma and urinary excretion rates declined in parallel with a terminal half-life of 1.29 +/- 0.07 h (mean +/- SD). Total, renal, and nonrenal clearances were 1.48 +/- 0.15, 0.73 +/- 0.38, and 0.75 +/- 0.36 L/h/kg, respectively. Renal clearance exceeds glomerular filtration rate in the rat, indicating that DDC undergoes active renal tubular secretion. The unbound secretory intrinsic clearance for DDC renal excretion was moderate, with a value of 0.4 L/h. The steady-state volume of distribution of DDC was 1.25 +/- 0.13 L/kg. Pharmacokinetic parameters after iv administration of 500 mg/kg of DDC were virtually identical to those reported previously after administration of 10-200 mg/kg of the nucleoside to rats. Thus, the disposition of DDC in the rat is independent of dose over a range of 10 to 500 mg/kg. High doses of DDC can be administered to rats to allow for complete characterization of the disposition pattern of the drug without complexities due to any nonlinearity.

Pharmacokinetics of 2',3'-dideoxycytidine in rats: application to interspecies scale-up

The effects of dose on the pharmacokinetics of 2',3'-dideoxycytidine (DDC), a potent inhibitor of HIV replication, have been studied in rats. DDC was administered intravenously at doses of 10, 50, 100 and 200 mg kg-1. Plasma and urine drug concentrations were determined by HPLC. Non-compartmental pharmacokinetic parameters were calculated by area/moment analysis. DDC plasma concentrations declined rapidly with a terminal half-life of 0.98 +/- 0.18 h (mean +/- s.d.). No statistically significant differences were observed in pharmacokinetic parameters between the four doses. Total, renal and non-renal clearance values were independent of dose and averaged 1.67 +/- 0.24, 0.78 +/- 0.11, and 0.89 +/- 0.27 L h-1 kg-1, respectively. Approximately 50% of the dose was excreted unchanged in urine. Steady state volume of distribution was also independent of dose and averaged 1.2 +/- 0.21 L kg-1. Protein binding of DDC to rat serum proteins was independent of drug concentration with the fraction of drug bound averaging 0.45 +/- 0.12. Thus, the disposition pattern of DDC in the rat is independent of the administered dose even at high doses. Significant interspecies correlations were found for total, renal and non-renal clearance and steady state volume of distribution. Interspecies scaling resulted in superimposable plasma DDC concentration-time profiles from four laboratory animal species and man. Thus, plasma DDC concentrations in humans can be predicted from pharmacokinetic parameters obtained in laboratory animals.

Poliomyelitis in Egypt: efficacy of mass campaigns

Vaccination against poliomyelitis in Egypt is described, including a historical perspective. Mass vaccination programmes have significantly reduced the incidence of the diseases, although it is far from being eradicated. Much disability has been prevented, though more work is needed to verify seroconversion rates in children after vaccination and to clarify the effect of environmental factors on success.

Effect of chloropheniramine maleate on liver and kidney functions as well as blood count of guinea pigs

The present study aimed at exploring the effect of antihistamine chloropheniramine maleate (H1-blocker) on liver and kidney functions as well as on blood count. 60 mature guinea pigs were used. Histamine or chloropheniramine maleate was given, either alone or together, intramuscularly for 7 successive days. At the end of the experimental period, blood samples were collected for determination of blood counts and of the levels of urea, creatinine, GOT, GPT, and alkaline phosphatase in the sera of different groups. The results showed significant groupwise variations in blood count, liver function as well as kidney function.