University students experience high levels of stress due to university transition, academic commitments, and financial matters. Higher stress perceptions along with limited coping resources endanger mental health for a considerable number of students and may ruin their performance. The current study evaluated the psychometric properties of the Cohen Perceived Stress Scale (10 items), PSS-10, in a sample of 379 female Emeriti students. Exploratory factor analysis resulted in two factors with eigenvalues of 3.88 and 1.19, which explained 60.6% of the variance. Confirmatory factor analysis revealed good model fits of two correlated factors (Comparative Fit Index (CFI) = 0.962, Tucker–Lewis Index (TLI) = 0.950, standardized root-mean-square residual (SRMR) = 0.0479, and root mean-square error of approximation (RMSEA) = 0.067). Internal consistency of the PSS-10 and its positive and negative subscales was acceptable (coefficient α = 0.67, 0.79, and 0.86, respectively). Multigroup analysis revealed that the PSS-10 holds invariance across different groups of age, marital status, and financial status (average monthly expenditure). Convergent and concurrent validity tests signify the importance of considering scores of subscales of the PSS-10 along with its total score.

Enzymes excreted by rumen microbiome facilitate the conversion of ingested plant materials into major nutrients (e.g., volatile fatty acids (VFA) and microbial proteins) required for animal growth. Diet, animal age, and health affect the structure of the rumen microbial community. Pathogenic organisms in the rumen negatively affect fermentation processes in favor of energy loss and animal deprivation of nutrients in ingested feed. Drawing from the ban on antibiotic use during the last decade, the livestock industry has been focused on increasing rumen microbial nutrient supply to ruminants through the use of natural supplements that are capable of promoting the activity of beneficial rumen microflora. Selenium (Se) is a trace mineral commonly used as a supplement to regulate animal metabolism. However, a clear understanding of its effects on rumen microbial composition and rumen fermentation is not available. This review summarized the available literature for the effects of Se on specific rumen microorganisms along with consequences for rumen fermentation and digestibility. Some positive effects on total VFA, the molar proportion of propionate, acetate to propionate ratio, ruminal NH₃-N, pH, enzymatic activity, ruminal microbiome composition, and digestibility were recorded. Because Se nanoparticles (SeNPs) were more effective than other forms of Se, more studies are needed to compare the effectiveness of synthetic SeNPs and lactic acid bacteria enriched with sodium selenite as a biological source of SeNPs and probiotics. Future studies also need to evaluate the effect of dietary Se on methane emissions.

The Coronavirus Disease-19 (COVID-19) pandemic has provoked the development of negative emotions in almost all societies since it first broke out in late 2019. The Impact of Event Scale-Revised (IES-R) is widely used to capture emotions, thoughts, and behaviors evoked by traumatic events, including COVID-19 as a collective and persistent traumatic event. However, there is less agreement on the structure of the IES-R, signifying a need for further investigation. This study aimed to evaluate the psychometric properties of the Arabic version of the IES-R among individuals in Saudi quarantine settings, psychiatric patients, and the general public during the COVID-19 outbreak. Exploratory factor analysis revealed that the items of the IES-R present five factors with eigenvalues > 1. Examination of several competing models through confirmatory factor analysis resulted in a best fit for a six-factor structure, which comprises avoidance, intrusion, numbing, hyperarousal, sleep problems, and irritability/dysphoria. Multigroup analysis supported the configural, metric, and scalar invariance of this model across groups of gender, age, and marital status. The IES-R significantly correlated with the Depression Anxiety Stress Scale-8, perceived health status, and perceived vulnerability to COVID-19, denoting good criterion validity. HTMT ratios of all the subscales were below 0.85, denoting good discriminant validity. The values of coefficient alpha in the three samples ranged between 0.90 and 0.93. In path analysis, correlated intrusion and hyperarousal had direct positive effects on avoidance, numbing, sleep, and irritability. Numbing and irritability mediated the indirect effects of intrusion and hyperarousal on sleep and avoidance. This result signifies that cognitive activation is the main factor driving the dynamics underlying the behavioral, emotional, and sleep symptoms of collective COVID-19 trauma. The findings support the robust validity of the Arabic IES-R, indicating it as a sound measure that can be applied to a wide range of traumatic experiences.

Internet addiction (IA) is widespread, comorbid with other conditions, and commonly undetected, which may impede recovery. The Internet Addiction Test (IAT) is widely used to evaluate IA among healthy respondents, with less agreement on its dimensional structure. This study investigated the factor structure, invariance, predictive validity, criterion validity, and reliability of the IAT among Spanish women with eating disorders (EDs, N = 123), Chinese school children (N = 1072), and Malay/Chinese university students (N = 1119). In school children, four factors with eigen values > 1 explained 50.2% of the variance, with several items cross-loading on more than two factors and three items failing to load on any factor. Among 19 tested models, CFA revealed excellent fit of a unidimensional six-item IAT among ED women and university students (χ²(7) = 8.695, 35.038; p = 0.275, 0.001; CFI = 0.998, 981; TLI = 0.996, 0.960; RMSEA = 0.045, 0.060; SRMR = 0.0096, 0.0241). It was perfectly invariant across genders, academic grades, majors, internet use activities, nationalities (Malay vs. Chinese), and Malay/Chinese female university students vs. Spanish women with anorexia nervosa, albeit it was variant at the scalar level in tests involving other EDs, signifying increased tendency for IA in pathological overeating. The six-item IAT correlated with the effects of internet use on academic performance at a greater level than the original IAT (r = −0.106, p < 0.01 vs. r = −0.78, p < 0.05), indicating superior criterion validity. The six-item IAT is a robust and brief measure of IA in healthy and diseased individuals from different cultures.

The prevalence of internet gaming disorders (IGD) is considerably high among youth, especially with the social isolation imposed by the ongoing COVID-19 pandemic. IGD adversely affects mental health, quality of life, and academic performance. The Internet Gaming Disorder Scale (IGDS9-SF) is designed to detect IGD according to DSM-IV diagnostic criteria. However, inconsistent results are reported on its capacity to diagnose IGD evenly across different cultures. To ensure the suitability of the IGDS9-SF as a global measure of IGD, this study examined the psychometric properties of the IGDS9-SF in a sample of Sri Lankan university students (N = 322, mean age = 17.2 ± 0.6, range = 16–18 years, 56.5% males) and evaluated its measurement invariance across samples from Sri Lanka, Turkey, Australia, and the USA. Among Sri Lankan students, a unidimensional structure expressed good fit, invariance across different groups (e.g., gender, ethnicity, and income), adequate criterion validity (strong correlation with motives of internet gaming, daily gaming duration, and sleep quality), and good reliability (alpha = 0.81). Males and online multiplayers expressed higher IGD levels, greater time spent gaming, and more endorsement of gaming motives (e.g., Social and Coping) than females and offline players. Across countries, the IGDS9-SF was invariant at the configural, metric, and scalar levels, although strict invariance was not maintained. The lowest and highest IGD levels were reported among Turkish and American respondents, respectively. In conclusion, the IGDS9-SF can be reliably used to measure IGD among Sri Lankan youth. Because the scale holds scalar invariance across countries, its scores can be used to compare IGD levels in the studied countries.

Efforts directed toward enhancing animals’ productivity are focused on evaluating the effects of non-traditional feed additives that are safer than antibiotics, which have been banned because of their health hazards. Many studies used an amino acid that contributes to heme biosynthesis, known as 5-aminolevulinic acid (5-ALA), to promote the productivity of farm animals. However, these studies demonstrate inconsistent results. In order to develop a clear understanding of the effects of 5-ALA in farm animals, we comprehensively searched PubMed and Web of Science for studies evaluating 5-ALA effects on the performance, iron status, and immune response of different farm animals. The search retrieved 1369 publications, out of which 16 trials were relevant. The 5-ALA-relevant data and methodological attributes of these trials were extracted/evaluated by two independent researchers, based on a set of defined criteria. Samples were comprised of pigs, chickens, and dairy cows. The 5-ALA doses ranged from 2 mg to 1 g/kg of feed, and treatment duration ranged from 10 to 142 days. Overall, 5-ALA improved iron status in most studies and increased white blood cells count in 3 out of 10 studies, in addition to improving animals’ cell-mediated immune response following immune stimulation with lipopolysaccharide. Inconsistent findings were reported for growth performance and egg production; however, a combination of 10 mg/kg of 5-ALA with 500 mg/kg of vitamin C promoted the highest egg production. In addition, 5-ALA improved milk protein concentration. In conclusion, 5-ALA can enhance farm animals’ iron status and immune response; however, the heterogeneity of the reviewed studies limits the generalizability of the findings. Standard procedures and outcome measures are needed to confirm the benefits of 5-ALA. Attention should also be paid to any adverse effects.