Impact of gamma irradiation on physico-chemical and electromagnetic interference shielding properties of Cu2O nanoparticles reinforced LDPE nanocomposite films

In the current work, cuprous oxide (Cu2O) nanoparticles coated with Tween 80 were successfully synthesized via the chemical reduction method. Nanocomposites composed of low-density polyethylene (LDPE) and different ratios of Cu2O nanoparticles were fabricated by the melt mixing process. 10% of ethyl vinyl acetate (EVA) as a compatibilizing agent was added to the molten LDPE matrix and the mixing process continued until homogenous nanocomposites were fabricated. To study the influence of ionizing radiation on the fabricated samples, the prepared species were exposed to 50 and 100 kGy of gamma rays. The synthesized Cu2O nanoparticles were investigated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). XRD and TEM analysis illustrated the successful formation of spherical Cu2O nanoparticles with an average size of 16.8 nm. The as-prepared LDPE/Cu2O nanocomposites were characterized via different techniques such as mechanical, thermal, morphological, XRD, and FTIR. Electromagnetic interference shielding (EMI) of the different nanocomposite formulations was performed as a promising application for these materials in practical life. The electromagnetic shielding effectiveness (SE) of the produced samples was measured in the X-band of the radio frequency range from 8 to 12 GHz using the vector network analyzer (VNA) and a proper waveguide. All the samples were studied before and after gamma-ray irradiation under the same conditions of pressure and temperature. The shielding effectiveness increased significantly from 25 dB for unirradiated samples to 35 dB with samples irradiated with 100 kGy, which reflects 40% enhancement in the effectiveness of the shielding.

Spectroscopic and photostability study of water-soluble hypericin encapsulated with polyvinylpyrrolidone

Hypericin has gained great attention as a powerful photosensitizing and fluorescent agent for photodynamic therapy (PDT) and fluorescence diagnosis (FD) of cancer. However, native hypericin is hydrophobic and nearly insoluble in aqueous media which hinders its photobiological activity. Herein, we demonstrate the encapsulation of hypericin and polyvinylpyrrolidone (hypericin@PVP) as an attractive class of water-soluble formula of hypericin with improved absorption and emission characteristics in water. The absorption and fluorescence properties of the water-soluble hypericin@PVP were studied at room temperature. Also, the photostability of the prepared hypericin@PVP was studied under visible light irradiation. The absorbance and emission measurements confirm the association and binding of hypericin and PVP with a binding constant (K_b) of 1.2 × 10⁵ M^-1. The interaction between hypericin and PVP in water could lead to the dissociation of aggregated hypericin into their monomeric state which is crucial for effective photobiological implementation in PDT and FD. Upon encapsulation with PVP, hypericin showed a significant increase in the fluorescence properties with an enhanced emission intensity of 300% at a PVP concentration of 1 × 10^-4 M. Moreover, water-soluble hypericin@PVP demonstrated high photostability under visible light irradiation with an irradiance of 15 mW/cm² and exposure time up to 150 min. This enhancement in the absorption, emission, and photostability of hypericin in water is related to the effects of encapsulation with PVP and the unique spectroscopic properties of the formulated hypericin@PVP.

A68 Characterization and comparative genomic analysis of two Bacillus megaterium lytic bacteriophages

Next-generation sequencing technologies provide unique possibilities for the comprehensive assessment of the environmental diversity of bacteriophages. Many Bacillus bacteriophages have been isolated, but very few Bacillus megaterium bacteriophages have been characterized. Here, we describe biological characteristics and whole-genome sequences and their annotations for two new isolates of the B. megaterium bacteriophages (BM5 and BM10), isolated from Egyptian soil samples and representing two different groups according to their host range and amplified fragment length polymorphism profiles. Both phages have been displaying different thermal inactivation points (82 and 78 °C) and pH tolerance range (5–9.2 and 5–8.4 pH) while having the same longevity in vitro (192 h). Electron microscopy observation has proved that both phages belonged to the Myoviridiae family. Furthermore, growth analyses indicated that phages BM5 and BM10 have a shorter latent period (20 and 25 min) and smaller burst size (103 and 117 PFU) than is typical for Bacillus phages. The genome sizes of phages BM5 and BM10 were 165,031 bp and 165,213 bp, respectively, with a modular organization. Bioinformatic analyses of BM5 and BM10 genomes enabled assignments of putative functions to 97 and 65 putative ORFs, respectively. Comparative analysis of BM5 and BM10 genome structures with other B. megaterium bacteriophages revealed relatively high levels of sequence and organizational identity. Both genomic comparisons and phylogenetic analyses support the conclusion that the sequenced phages (BM5 and BM10) belong to different sub-clusters (L5 and L7) within L cluster and display different lifestyles (lysogenic and lytic). Sequenced phages encode proteins associated with Bacillus pathogenesis. BM5 does not contain any tRNA sequences, while BM10 genome codes for 17 tRNAs.

Functional and comparative genome analysis of novel virulent actinophages belonging to Streptomyces flavovirens

Background

Next Generation Sequencing (NGS) technologies provide exciting possibilities for whole genome sequencing of a plethora of organisms including bacterial strains and phages, with many possible applications in research and diagnostics. No Streptomyces flavovirens phages have been sequenced to date; there is therefore a lack in available information about S. flavovirens phage genomics. We report biological and physiochemical features and use NGS to provide the complete annotated genomes for two new strains (Sf1 and Sf3) of the virulent phage Streptomyces flavovirens, isolated from Egyptian soil samples.

Results

The S. flavovirens phages (Sf1 and Sf3) examined in this study show higher adsorption rates (82 and 85%, respectively) than other actinophages, indicating a strong specificity to their host, and latent periods (15 and 30 min.), followed by rise periods of 45 and 30 min. As expected for actinophages, their burst sizes were 1.95 and 2.49 virions per mL. Both phages were stable and, as reported in previous experiments, showed a significant increase in their activity after sodium chloride (NaCl) and magnesium chloride (MgCl₂.6H₂O) treatments, whereas after zinc chloride (ZnCl2) application both phages showed a significant decrease in infection.

The sequenced phage genomes are parts of a singleton cluster with sizes of 43,150 bp and 60,934 bp, respectively. Bioinformatics analyses and functional characterizations enabled the assignment of possible functions to 19 and 28 putative identified ORFs, which included phage structural proteins, lysis components and metabolic proteins.

Thirty phams were identified in both phages, 10 (33.3%) of them with known function, which can be used in cluster prediction. Comparative genomic analysis revealed significant homology between the two phages, showing the highest hits among Sf1, Sf3 and the closest Streptomyces phage (VWB phages) in a specific 13Kb region. However, the phylogenetic analysis using the Major Capsid Protein (MCP) sequences highlighted that the isolated phages belong to the BG Streptomyces phage group but are clearly separated, representing a novel sub-cluster.

Conclusion

The results of this study provide the first physiological and genomic information for S. flavovirens phages and will be useful for pharmaceutical industries based on S. flavovirens and future phage evolution studies.

Determining nutrients degradation kinetics of chickpea (Cicer arietinum) straw using nylon bag technique in sheep

Straw a by-product from grain legume crops is produced in large quantities in Iran. Straw is constant component of ruminant diets on small holder farms; however, there is little information about its nutritive value. Accordingly experiment was conducted to determine the chemical composition and ruminal organic matter (OM) and crude protein (CP) degradability of chickpea straw using nylon bags (in situ) technique. Replicated samples were incubated at 0, 2, 4, 8, 12, 24, 48 and 72 hours in three rumen canulated Ghezel rams with 50±3 kg body weight. Dry matter (DM), CP, ether extract (EE), OM, crude fiber (CF) and nitrogen free extract (NFE) content of chickpea straws were 92.2, 6.1, 5.5, 92.0, 34.3 and 46.2%, respectively. The soluble fraction (a) of the OM and CP of chickpea straw was 17.5 and 40.8% and potential degradability (a+b) of OM and CP was 56.7 and 72.0%, respectively. Effective degradability at different passage rates (2, 5 and 8% per hours) for OM was 51.0 44.9 and 40.7% and for CP were 68.4, 64.3 and 61.3%, respectively. In conclusion, based on chemical composition and degradation characteristics, chickpea straw could have moderate nutritive value for ruminants.

Milia en plaque: a new site

A 35-year-old Kuwaiti field worker presented with a history of an asymptomatic, erythematous plaque on the right side of the nasal bridge. It soon extended to the malar area, being studded with multiple yellowish papules (Fig. 1). He denied any history of photosensitivity, drug intake, local trauma, topical applications, or ionizing radiations to that area. Examination revealed an erythematous, 1.5 x 3 cm plaque on the right nasal fold, extending to the malar area, overlain by a group of tiny yellowish papules (15-20 in number). He also had a few discrete milia on the right cheek. The histology (Fig. 2) revealed multiple keratin-filled cysts, surrounded by a dense lymphocytic infiltrate, findings consistent with milia; 0.05% tretinoin was prescribed twice daily for 1 month without improvement; minocycline, 100 mg daily, was then employed, and at 1 month of follow-up there was a significant decrease in erythema and milia count.

Effect of chlormequat and alar on some biochemical constituents in tomato plants and fruits

The field experiment was conducted to study the effect of various levels of chlormequat (CCC) and alar on the biochemical changes in tomato plants and fruits at different stages of growth. This experiment included spraying with chlormequat and alar separately in two equal doses (250, 500 and 1000 ppm CCC or alar 25 and 40 days after transplanting). The different levels of chlormequat decreased the accumulation of dry matter in tomato plants, but alar increased it. Chlorophyll a, b, total chlorophyll and carotenoids content of tomato plants increased by the application of CCC or alar. The highest increase of concentration of chlorophyll a, b and carotenoids in tomato plants were found by spraying with 500 ppm alar or CCC. The application of CCC and alar declined the percentage of carbohydrates and the highest decrease resulted by adding of 1000 ppm alar or CCC. Alar caused an increase in the percentage of total nitrogen at the different stages of growth. The concentration of P, K, Ca and Mg increased by the foliar spray of all treatments. Alar application at all used levels significantly increased the yield and also the weight of fruits. Highest plant productivity was obtained by using alar and CCC at 250 ppm, followed by 500 ppm. However, the highest concentration (1000 ppm) depressed the plant productivity. The concentration of juice, total soluble solids and vitamin C in tomato fruits increased at most of the levels added. But the percentage of total sugars and total acidity seemed to exert another trend. The highest concentration of N, P, K, Ca and Mg in fruits was obtained by foliar application of 500 ppm CCC or alar.

Chemical and biological studies on banana fruit

Chemical and biological evaluation of both the edible and nonedible portion of banana fruit was carried out. The possibility of using the nonedible portion (peel) as animal feed was also explored. The results showed a remarkable difference concerning the chemical composition of both the edible and nonedible portions. The amino acid contents were proved to vastly deficient with regard to the indispensable amino acids with exception of phenylalanine which was found in good amounts in the edible portion (pulp). The biological results demonstrated that neither the pulp nor the peel portions yielded good P.E.R. values when used at 6% protein level. The P.E.R values showed negative values which amounted to -1.75, -5.85 and -4.67 for the pulp and peel diets respectively. Incorporation of the stock diet to the peel diet resulted in a slight increase which amounted to 6% in both male and female rat groups.

Interrelationship between vitamins of the B-complex group and oestradiol

Vitamins B2 and B6 are shown to have oestrogen-like effects and to act synergistically with oestradiol, increasing its action on the uterine weight of ovariectomized rats. Vitamins B1 and pantothenic acid enhanced the action of oestradiol but had no oestrogenic action themselves. Vitamin B12 had neither an oestrogen-like effect nor an influence on the action of oestradiol.