Experimental Investigations on Dry Sliding Wear Behavior of Kevlar and Natural Fiber-Reinforced Hybrid Composites through an RSM–GRA Hybrid Approach

The present work aimed to investigate the dry sliding wear behaviors of hybrid polymer matrix composites made up of Kevlar, bamboo, palm, and Aloe vera as reinforcement materials of varying stacking sequences, along with epoxy as the matrix material. Three combinations of composite laminates with different stacking sequences such as AB, BC, and CA were fabricated by a vacuum-assisted compression molding process. The influence of composite laminates fabricated through various stacking sequences and dry sliding wear test variables such as load, sliding distance, and sliding velocity on the specific wear rate and co-efficient of friction were investigated. Experiments were designed and statistical validation was performed through response surface methodology-based D-optimal design and analysis of variance. The optimization was performed using grey relational analysis (GRA) to identify the optimal parameters to enhance the wear resistance of hybrid polymer composites under dry sliding conditions. The optimal parameters, such as composite combinations of CA, a load of 5 N, a sliding velocity of 3 m/s, and a sliding distance of 1500 m, were obtained. Furthermore, the morphologies of worn-out surfaces were investigated using SEM analysis.     

Corrective Effect of Verbascoside on Histomorphological Differences and Oxidative Stress in Colon Mucosa of Rats in Which Colon Ischemia–Reperfusion Injury was Induced

BackgroundThis study aims to show the corrective effect of verbascoside on histomorphological and biochemical differences in the colon mucosa of rats in which colon ischemia–reperfusion (I/R) injury was induced.Methods: Fifty Sprague Dawley male rats were divided into 5 groups, of control, sham, ischemia (I), I/R, and I/R+verbascoside.Ischemia and reperfusion were applied to the suitable groups for 30 minutes and 120 minutes respectively, and 10 mg/kg verbascoside was administered intraperitoneally. Histomorphological assessment was done in the colon tissues obtained, and the goblet cells were assessed using the Alcian blue method. Proliferating cell nuclear antigen (PCNA), TUNEL, and hypoxia-induced factor 1 (HIF-1α) assays were used to assess oxidative stress with the immunohistochemical method. Malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), and total thiol (TT) levels were checked, for a biochemical analysis of oxidative stress.Results: Compared with the I/R group, histomorphological differences were seen to be corrected in colon epithelium in the I/R+verbascoside group. The goblet cell number increased and cell proliferation was increased, as seen with the PCNA assay; and apoptosis was decreased, as seen with the TUNEL assay. HIF-1α expression also decreased in the drug group. In the drug group, SOD, GSH-Px, TAS, and TT levels increased, but TOS, OSI, and MDA levels decreased.Conclusion: It was seen that verbascoside had a corrective effect on histomorphological and biochemical differences caused by I/R injury.     

Oxygen-enriched surface modification for improving the dispersion of iron oxide on a porous carbon surface and its application as carbon molecular sieves (CMS) for CO2/CH4 separation

The separation of CO₂/CH₄ can be enhanced by impregnating porous carbon with iron oxide. Dispersion of iron oxide is one of the critical factors which supports the separation process performance. Iron oxide dispersion can be enhanced by enriching the oxygen functional groups on the carbon surface. This study investigates three distinct oxidation processes: oxidation with a 10% H₂O₂ solution, ozonation with distilled water, and ozonation with a 10% H₂O₂ solution. The research steps included the following: (i) oxidation, (ii) impregnation of iron oxide followed by calcination, (iii) material characterization, and (iv) material performance analysis. Materials were characterized using N₂ sorption analysis, X-ray diffraction analysis (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy analysis (SEM-EDX), and Fourier transform infrared analysis (FT-IR). Iron oxide was well dispersed on the carbon surface, as evidenced by the elemental mapping of materials. In addition, the oxygen functional groups increased significantly in the range of 28.6–79.7% following the oxidation process, as indicated by the elemental component using SEM-EDX analysis. The impregnation of iron oxide on oxidized carbon ozonated with distilled water (COA–Fe) obtained a maximum CO₂ uptake capacity of 3.0 mmol g⁻¹ and CO₂/CH₄ selectivity increased by up to 190% at a temperature of 30 °C and pressure of 1 atm. Furthermore, the enhancement of CO₂/CH₄ separation up to 1.45 times was the best performance achieved by COA–Fe. Thus, improving iron oxide dispersion on oxidized carbon surfaces has a potential application in CO₂/CH₄ separation.

The separation of CO₂/CH₄ can be enhanced by impregnating porous carbon with iron oxide.     

Sports Nutrition and Food Knowledge among Malaysian University Athletes

Sports nutrition and food knowledge can influence athletes’ dietary intake, potentially affecting athletic performance. Limited studies have been conducted to identify sports nutrition and food knowledge among Malaysian university athletes. This study aimed to determine Malaysian university athletes’ knowledge of sports nutrition and food, and their reference sources and preferred sports nutrition education programme. Seventy athletes (52.9% females, mean weight = 61.8 kg; height = 1.66 m) aged 18.5–22.4 years responded to an online survey administered using a Google Form. A score of ≥60% was considered as adequate knowledge. The average overall knowledge score was 58.6%. The highest knowledge score was for sports nutrition, specifically food intake periodicity (84.8%), while the lowest was for general food knowledge on fat (44.6%). An analysis of specific questions revealed a lack of understanding about the recommended daily intake of fruits and vegetables (only 14.3% answered correctly), the roles of vitamins and minerals in energy production (21.4%), and good sources of unsaturated fat (37.2%). The academician was the primary reference source (81%), while magazines were the least referred to sources (36%). The university athletes preferred sports camps (33%) over the other nutrition education programme options. More initiatives are needed to improve Malaysian university athletes’ understanding and knowledge of sports nutrition and general food.     

Combined experimental and computational study of Al2O3 catalyzed transamidation of secondary amides with amines

Amides are the most extensively used substances in both synthetic organic and bioorganic chemistry. Unfortunately, the traditional synthesis of amides suffers from some important drawbacks, including low atom efficiency, high catalyst loading, separation of products from the reaction mixture and production of byproducts. Al₂O₃ is an amphoteric catalyst that activates the carbonyl carbon of the secondary amide group and helps the C–N cleavage of the reactant amide group by attacking the N–H hydrogen. By using the concepts of amphoteric properties of Al₂O₃, amides were synthesized from secondary amides and amines in the presence of triethylamine solvent. Several aliphatic and aromatic amines were used for the transamidation of N-methylbenzamide in the presence of the Al₂O₃ catalyst. Moreover, using the Gaussian09 software at the DFT level, HUMO, LUMO and the intrinsic reaction coordinates (IRCs) have also been calculated to find out the transition state of the reaction and energy. In this study, five successful compounds were synthesized by the transamidation of secondary amides with amines using a reusable Al₂O₃ catalyst. The catalyst was reused several times with no significant loss in its catalytic activity. The products were purified by recrystallization and column chromatography techniques. This catalytic method is effective for the simultaneous activation of the carbonyl group and N–H bond by using the Al₂O₃ catalyst.

Amides are the most extensively used substances in both synthetic organic and bioorganic chemistry.     

First Indications of Omsk Haemorrhagic Fever Virus beyond Russia

Omsk haemorrhagic fever virus (OHFV) is the agent leading to Omsk haemorrhagic fever (OHF), a viral disease currently only known in Western Siberia in Russia. The symptoms include fever, headache, nausea, muscle pain, cough and haemorrhages. The transmission cycle of OHFV is complex. Tick bites or contact with infected small mammals are the main source of infection. The Republic of Kazakhstan is adjacent to the endemic areas of OHFV in Russia and febrile diseases with haemorrhages occur throughout the country—often with unclear aetiology. In this study, we examined human cerebrospinal fluid samples of patients with suspected meningitis or meningoencephalitis with unknown origins for the presence of OHFV RNA. Further, reservoir hosts such as rodents and ticks from four Kazakhstan regions were screened for OHFV RNA to clarify if this virus could be the causative agent for many undiagnosed cases of febrile diseases in humans in Kazakhstan. Out of 130 cerebrospinal fluid samples, two patients (1.53%) originating from Almaty city were positive for OHFV RNA. Screening of tick samples revealed positive pools from different areas in the Akmola region. Of the caught rodents, 1.1% out of 621 were positive for OHFV at four trapping areas from the West Kazakhstan region. In this paper, we present a broad investigation of the spread of OHFV in Kazakhstan in human cerebrospinal fluid samples, rodents and ticks. Our study shows for the first time that OHFV can not only be found in the area of Western Siberia in Russia, but can also be detected up to 1.600 km away in the Almaty region in patients and natural foci.     

Inpatient rehabilitation outcomes in neoplastic spinal cord compression vs. traumatic spinal cord injury

Objective: To compare neurological and functional outcomes, and complications of patients with neoplastic vs traumatic spinal cord injury (SCI) after in-patient rehabilitation.Design: This study is a retrospective analysis.Setting: In-patient rehabilitation unit of a tertiary research hospital.Participants: A total of 252 patients with a SCI were included; 43 with neoplastic SCI (mean age: 60.9 ± 15.7 years, 60.5% were males) and 209 with traumatic SCI (mean age: 43.1 ± 16.8 years, 71.3% were males).Outcome measures: Comparisons were made of demographic characteristics, etiology, American Spinal Injury Association (ASIA) impairment scale, functional independence measurement (FIM) and Functional Ambulation Categories (FAC) scores, length of stay (LOS), bladder independence, medical comorbidities and complications in both groups.Results: Patients with neoplastic SCI were significantly older than those with traumatic SCI (P < 0.01). No difference was present between the groups in terms of sex and lesion level (P > 0.05). Incomplete SCI was significantly higher in the neoplastic group when compared with the traumatic group (P < 0.01). The LOS was significantly shorter in the neoplastic group than traumatic group (34.8 ± 41.03 vs. 60.02 ± 53.1, P < 0.01). There were no differences in the admission FIM scores (69.3 ± 24.7 vs. 58.7 ± 18.9, P > 0.05), discharge FIM scores (82.1 ± 25.1 vs. 74.02 ± 23.3, P > 0.05) and FIM efficiencies (0.43 ± 0.72 vs. 0.36 ± 0.51, P > 0.05) for the neoplastic and traumatic groups, respectively. However, neoplastic SCI patients demonstrated lower FIM gains compared to traumatic patients (12.9 ± 11.9 vs. 15.4 ± 15.2, P < 0.05). During rehabilitation, urinary tract infection (48.4% vs. 69.4%) and decubitus ulcer (11.6% vs. 35.9%) were significantly more common in the traumatic group than the neoplastic group (P < 0.05).Conclusion: Neoplastic SCI patients who commonly present at rehabilitation units exhibit different characteristics from traumatic SCI patients but the rehabilitation results are similar. Similar functional development can be achieved in a shorter period of time with inpatient rehabilitation in the neoplastic SCI group.