Lithium ferrite (LiFe5O8)/polymethyl methacrylate (PMMA) nano-composite used in high dielectric constant capacitor and electromagnetic applications

Poly methyl methacrylate/ Lithium ferrite nano-composites have been prepared by solution mixing process. The electrical conductivity and dielectric properties of these prepared nano-composite have been investigated in the frequency range 10²–10⁶ Hz at different LiFe₅O₈ concentrations from 0 vol% to 25 vol%. The prepared samples are studied by thermal gravimetric analysis (TGA) and X-ray diffraction (XRD). Moreover, the magnetic properties of these nano-composites are investigated through vibrating sample magnetometer studies. XRD spectral investigation revealed that the structural of PMMA and its chemical characterization are appreciably affected by mixed lithium ferrite filler. The thermal stability of the PMMA matrix was found to increase appreciably by LiFe₅O₈ loading. The (I-V) characteristic of these nano-composites are in very good agreement with the non-linearity predicted by Kaiser et al. model. The effective dielectric constant is studied through different proposed models. Saturation magnetization of 10.05 emu/g is achieved for PMMA sample loaded with 25 vol% of LiFe₅O₈ particles.     

First unseeded hydrothermal synthesis of microporous vanadosilicate AM-6

Microporous vanadosilicate AM-6 has been hydrothermally synthesized for the first time in the absence of titanosilicate ETS-10 seeds. High purity (95–100% AM-6) products were crystallized under static conditions at 430–503 K using tetramethylammonium hydroxide (TMAOH) or tetramethylammonium bromide (TMABr) as a structure-directing agent in mixtures with molar compositions xNa₂O:1.3K₂O:ySiO₂:0.5V₂O₅:wTMA:zH₂O, where x = 4.5 or 5.6, y = 4.3–5.5, w = 2.0–3.0, and z = 206–214. The size (250 nm to 9 μm range), truncated square bipyramidal morphology (varied from square cuboid to thin (thickness <100–200 nm) tetragonal platy), and surface irregularities/faulting of AM-6 crystals (Si/V = 5.0 ± 0.5) can be controlled by varying the molar composition or initial pH of synthesis mixture, and crystallization temperature. Structure-directing agent can be removed from the pores with little or no adverse effects on crystallinity of AM-6 by treatment with gaseous ammonia at elevated temperatures. UV–vis and FTIR analyses suggest two (V⁴⁺, V⁵⁺) oxidation states of vanadium in the AM-6 framework.     

Effect of selection for growth rate on the ageing of myofibrils, meat texture properties and the muscle proteolytic potential of m. longissimus in rabbits

The effect of selection for growth rate on the degradation of the myofibrillar proteins and on meat texture properties of rabbit longissimus muscle at two ageing times (1 and 7 days) was studied as well as its effect on the proteolytic potential of the muscle. Two groups of contemporary animals (20 rabbits per group), one selected for growth rate (S) for 14 generations and the other unselected control group (C) were compared. The control group was formed from the offspring of the embryos belonging to the 7th generation and was compared with selected animals belonging to 21st generation. Myofibrillar protein degradation was studied by SDS-PAGE electrophoresis (12.5% and 4-15% polyacrylamide gels) followed by densitometric analysis of the pherograms. Texture properties were evaluated by Warner-Bratzler (WB) test and Texture profile analysis (TPA). The activities of proteolytic enzymes calpains and cathepsins and of their inhibitors were determined in the muscle at 24h. Densitometric analysis of the pherograms of samples aged 7 days showed an extra 30kDa band and the disappearance of a band with higher molecular weight than the myosin heavy chain with respect to samples aged 24h in both groups of rabbits. TPA results showed that cohesiveness was significantly lower in meat at 7 days than at 24h (P<0.0001), whereas springiness and chewiness presented a clear tendency to be lower at 7 days than at 24h (P=0.0646 and P=0.0764, respectively). Regarding the genetic type, S animals presented higher hardness and chewiness than C rabbits. Shear firmness (WB test) was significantly (P<0.0001) higher for S group, whereas no significant differences in shear force and area were found. No significant effect (P>0.05) of ageing time was detected using WB test. Selection for growth rate did not affect the activities of proteolytic enzymes or their inhibitors.     

Role of TiO2 and carbon nanotubes on polyethylene,and effect of accelerated weathering on photo oxidation and mechanical properties

In this work, LLDPE‐based composite films were prepared by melt mixing followed by compression molding to investigate the role of titanium oxide nanoparticles (TONPs) and/or multiwalled carbon nanotubes (CNTs) on the accelerated weathering samples (maximum of 39 days). Accelerating weathering caused the emerging of oxidation peaks in the FT‐IR spectra for LLDPE and LLDPE/TONPs. These peaks were not pronounced in the LLDPE/CNTs samples. The same prevention of oxidation peaks were noticed for the hybrid additives samples. Tensile properties decreased by exposing the composite samples to accelerating weathering. TONPs increased the tensile strength of the samples by 11.5% but deterioration of this property is the same as the pristine sample after accelerated weathering for 39 days. Addition of CNTs had negligible effect on the tensile strength but it kept the same approximate value of the original before the accelerated weathering (e.g., 23.2 MPa for 1 wt% of CNTs). CNTs also protected the samples even with the presence of TONPs because of the absorbance and antioxidants effects. The addition of CNTs into LLDPE network have not only retarded decomposition of LLDPE but also decreased catalytic activity of TONPs to activate degradation due to accelerated weathering. J. VINYL ADDIT. TECHNOL., 25:19–25, 2019. © 2018 Society of Plastics Engineers     

Rep-PCR characterization and biochemical selection of lactic acid bacteria isolated from the Delta area of Egypt

Samples of raw milk and traditional dairy products were collected from different rural areas in the Delta region. 170 isolates from these products were identified using repetitive genomic element-PCR (Rep-PCR) fingerprinting. The identified isolates were tested for efficiency of biomass production and separation, acidifying activity, autolytic and aminopeptidase properties, antagonistic activities and exopolysaccharide production. The obtained results revealed that the Lactobacillus delbrueckii subsp. lactis, Lactobacillus fermentum, Enterococcus faecium Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus paracasei subsp. paracasei, Lactobacillus plantarum and Lactococcus lactis subsp. lactis were the predominant species in Egyptian dairy products. Two percent of Lactococcus, 10% of Lactobacillus and 1% of Enterococcus isolates showed fast acidifying activity. Aminopeptidase and autolytic properties were generally higher for most Lactobacillus strains when compared to other strains. Among these species, lactobacillus paracasei subsp. paracasei was the highest in Aminopeptidase activity and autolytic properties. Antagonistic activity was detected in 40% of Lactococcus, 70% of Lactobacillus and 50% of Enterococcus isolates. Some isolates produced exopolysaccharides in milk and dairy products.     

Elevated Levels of Endocannabinoids in Chronic Hepatitis C May Modulate Cellular Immune Response and Hepatic Stellate Cell Activation

The endocannabinoid (EC) system is implicated in many chronic liver diseases, including hepatitis C viral (HCV) infection. Cannabis consumption is associated with fibrosis progression in patients with chronic hepatitis C (CHC), however, the role of ECs in the development of CHC has never been explored. To study this question, anandamide (AEA) and 2-arachidonoyl glycerol (2-AG) were quantified in samples of HCV patients and healthy controls by gas and liquid chromatography mass spectrometry. Fatty acid amide hydrolase (FAAH) and monoaclyglycerol lipase (MAGL) activity was assessed by [³H]AEA and [³H]2-AG hydrolysis, respectively. Gene expression and cytokine release were assayed by TaqMan PCR and ELISpot, respectively. AEA and 2-AG levels were increased in plasma of HCV patients, but not in liver tissues. Hepatic FAAH and MAGL activity was not changed. In peripheral blood mononuclear cells (PBMC), ECs inhibited IFN-γ, TNF-α, and IL-2 secretion. Inhibition of IL-2 by endogenous AEA was stronger in PBMC from HCV patients. In hepatocytes, 2-AG induced the expression of IL-6, -17A, -32 and COX-2, and enhanced activation of hepatic stellate cells (HSC) co-cultivated with PBMC from subjects with CHC. In conclusion, ECs are increased in plasma of patients with CHC and might reveal immunosuppressive and profibrogenic effects.     

The exponentiated power Lomax distribution and its applications

In this paper, a new extension of Lomax distribution called the exponentiated power Lomax (EPOLO) distribution is proposed. The proposed model accommodates monotonically increasing, decreasing, and unimodal hazard rates. A full study of the proposed model parameters using four techniques is introduced and a simulation study is performed to examine the performance of the four methods of estimation for both complete and censored data. EPOLO distribution is utilized to fit the number of revolutions of ball bearings, the tumor size of lung cancer patients, and the confirmed total deaths of the COVID-19 in Egypt and it provides better fits than some well-known distributions.     

Resistance towards wiki: implications for designing successful wiki-supported collaborative learning experiences

Universal Access in the Information Society - Wikis are online tools best used to support collaborative learning experiences of students. Not all students, however, are sufficiently comfortable in...