Thamar University

In this study, three novel organophosphorus Schiff base derivatives (OPC1–OPC3) were successfully synthesized by condensing chlorodiphenylphosphine with different Schiff bases derived from various aldehydes and hydrazine derivatives. The structural elucidation of the synthesized compounds was achieved using comprehensive spectroscopic analyses, including FTIR, UV-Vis, and both 1H and 13C NMR spectroscopy. Elemental analysis and physical property measurements further confirmed the proposed molecular structures. Spectroscopic data revealed characteristic azomethine (C=N), phosphorus–carbon (P–C), and phosphorus oxygen (P–O–C) stretching bands, confirming the successful formation of the organophosphorus Schiff base framework. The synthesized compounds were tested for antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus using the agar well diffusion method. The results demonstrated that all compounds exhibited moderate to significant antibacterial activity, with OPC2 and OPC3 showing notable inhibition zones compared to OPC1. These findings suggest that the incorporation of organophosphorus moieties into Schiff base ligands enhances their biological potency and provides a promising route for developing new bioactive organophosphorus materials.

Temporomandibular disorders (TMDs) are common chronic conditions that significantly impact patients’ quality of life. This systematic review and meta-analysis evaluated the potential association between khat chewing and TMDs. A comprehensive literature search of PubMed, Scopus, Web of Science, and Google Scholar was conducted by two independent investigators on May 26, 2025, to identify all relevant studies. Statistical analyses were performed using Stata/MP v17 (StataCorp, TX, USA). Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. The methodological quality of the included studies was assessed using the Newcastle–Ottawa Scale (NOS). Additionally, GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) system was used to assess the certainty of evidence. Thirteen studies, comprising 3526 subjects, met the inclusion criteria. Of these, only six studies were included in the meta-analysis. Qualitative findings indicated a significant association between khat chewing and the clinical and radiographic signs of TMDs. The pooled analysis demonstrated a significant association between khat chewing and TMDs (OR = 2.48; 95% CI: 1.20–5.09; p = 0.01; heterogeneity: I² = 84.68%). According to GRADE analysis, the overall quality of evidence was very low. The available evidence indicates a possible association between long-term khat chewing and TMDs. However, given the low quality of evidence and the considerable heterogeneity among the studies, these findings should be interpreted with caution. Further well-designed longitudinal studies are strongly recommended to clarify the potential detrimental effects of khat chewing on the temporomandibular joint and the masticatory system.

Seonamhaeicola marinus, a marine bacterium from the family Flavobacteriaceae, was genomically analyzed. Approximately 23% of its predicted CDSs were linked to subsystems, with amino acid and protein metabolism being the most abundant. Four biosynthetic gene clusters (BGCs) were identified, including those for flexirubin and carotenoid. CAZyme analysis via dbCAN3 revealed 178 CAZymes, representing 3.87% of the genome, with glycosyl hydrolases, particularly GH2, being the most prevalent group. Polysaccharide-producing organisms, such as those yielding carrageenan from red algae, find applications in food, cosmetics, and pharmacology. ι-Carrageenan, characterized by its double sulfate groups, holds significant potential in pharmaceutical systems. ι-Carrageenase A2 from S. marinus has desirable properties for carrageenan processing, supporting the investigation of such novel enzymes for biotechnological uses. This study aimed to comprehensively analyze S. marinus ι-carrageenase A2 through various computational modeling methods. A comparative analysis of the enzyme’s physicochemical properties, binding site locations, and structural features was conducted with other enzymes from the same family. Multiple computer modeling software programs were employed for three-dimensional structure prediction and modeling. Molecular docking identified potential ligands, with neo-ι-carratetraose demonstrating strong binding affinity. Molecular dynamics simulations assessed the stability and flexibility of the ligand-enzyme complex, offering insights into key residues involved in substrate interactions.

Dental implantology is increasingly essential in contemporary dental practice, yet its integration into undergraduate curricula remains inconsistent-particularly in low-resource settings. This is the first multicenter study in Yemen to evaluate dental implant-related education among undergraduate dental students across five universities. The aim was to assess students' knowledge, attitudes, and practices regarding dental implants and to identify gaps in theoretical instruction and clinical training. A cross-sectional questionnaire survey was conducted among 721 third-, fourth-, and fifth-year dental students from five Yemeni universities. A validated 33-item close-ended questionnaire collected data on demographics, implant-related education and awareness, knowledge of materials and techniques, attitudes toward treatment choices, cost perception, oral hygiene, complication awareness, and implant practices. Data were analyzed using SPSS version 20.0, applying chi-square and logistic regression analyses to determine associations, reported as odds ratios (ORs) with 95% confidence intervals (CIs), with statistical significance set at p < 0.05. Awareness of dental implants was high (97.4%), yet 63.1% had not studied implantology formally and only 7.4% attended implant courses. Knowledge of key concepts was limited but improved with educational level (p < 0.001), while practical exposure was minimal (9%). Self-perceived (not objectively assessed) competence to place implants was 62.6%, and 87.4% sought further training. Educational level was significantly associated with learning methods, implantation methods, and number of implants placed, but not with gender or awareness of complications. This multicenter survey revealed high awareness but insufficient theoretical and clinical training in implant dentistry among Yemeni undergraduates. Integrating competency-based modules with early simulation, structured supervision, and faculty development is recommended to align education with international standards in resource-limited settings.

Abstract Agriculture in Najran City plays a crucial role in supporting the local economy. Nevertheless, the region faces sustainability, resource management, and environmental degradation challenges. Descriptive and somewhat manual techniques for assessing land-use scenarios and classifying agricultural land changes can be tedious and prone to human error, and they remain inefficient when analyzing rapidly changing terrains. AI techniques offer promising solutions to overcoming such shortcomings, enabling automated, accurate, and scalable analyses of highly intricate satellite imagery datasets. This study proposes a hybrid artificial intelligence-based topographic analysis model to improve agricultural development in Najran. Spatial features extraction from the images of those two models through spatial information fusion would, in the post-fusion, mean an increase in redundancy and irrelevant features and an increase in computational complexity. Therefore, the next step was using a PCA algorithm to remove unessential features before feeding essential features into the artificial neural network (ANN) algorithm. The resulting important features are then classified using an ANN. The system was then implemented using Landsat 8 satellite imagery for 2013–2023. The results indicated that the developed hybrid EfficientNetB7–ShuffleNet with ANN system achieved an accuracy of 97.11% in 2013 and 97.01% in 2023. It also achieved a Recall rate of 97.66 and 97.54% during the period 2023 and 2023, respectively, and an F 1-score of 96.77 and 97.53% during the period 2023 and 2023.

Abstract Sustainable agriculture depends heavily on precise LULC classification to support soil conservation, water resource planning, and environmentally conscious land use. This study proposes a hybrid deep learning system integrating VGG16 and EfficientNetB7 models with a Random Forest (RF) classifier to classify agricultural and other LULC types in Najran, Saudi Arabia, utilizing digital elevation models (DEMs) and Indian Remote Sensing Advanced Wide Field Sensor satellite data from 2020. A stereo-derived DEM was used to extract topographical features, which, combined with multi-temporal imagery, were processed through VGG16 and EfficientNetB7 for spatial feature extraction. The Grasshopper Optimization Algorithm was applied to select the most essential features and remove the unimportant and redundant ones. The features were then fed into an RF classifier to classify the Najran terrain map efficiently. Evaluation of the hybrid system showed promising results for classifying the Najran terrain map, achieving an accuracy of 94.2%, precision of 79.88%, recall of 79.22%, F 1-score of 79.53%, and specificity of 96.01%. The system demonstrated robust performance in differentiating agricultural lands from urban and natural terrains, enabling efficient monitoring of land use patterns. This approach supports sustainable agricultural practices and environmental stewardship by providing decision-makers with high-resolution, automatically classified land maps for strategic planning in arid regions, such as Najran.

We report a highly efficient method for synthesizing carbamatoalkyl naphthols via one-pot, three-component condensation involving 2-naphthol, aldehydes, and butyl carbamates. This reaction, facilitated by cerium ammonium nitrate, can be performed under solvent-free conditions at 80°C and generally occurs within a short time frame. The resulting compounds were thoroughly characterized by FT-IR, 1H NMR, 13C NMR, and mass spectrometry. Additionally, the antimicrobial properties and biocompatibility of the newly synthesized compounds were evaluated using laboratory tests. The findings indicated that these compounds exhibited significant biological activity compared to standard antibiotics, and their hemocompatibility was confirmed.

During the 2023 - 2024 spring season, this experiment was conducted in the Government Thamar Special Farm. There are no appreciable differences between the various irrigation levels in the tomato fruit length; the highest value in the length recipe was obtained at the 100% ETc, with an average length of 21.949 mm, and the lowest value was obtained at the 60% ETc, with an average length of 19.836 mm. Consequently. The tomato crop's diameter measured at the 100% irrigation yielded the maximum average fruit diameter of 37.926 mm, while the lowest average fruit diameter measured at the 60% under-irrigation was 30.893 mm. At a significance threshold of P < 0.05, there were significant variations between the amounts of deficit irrigation for the tomato fruit diameter (4.1610). In addition, the 100% ETc the highest value for the efficiency of fertilizer use to produce the tomato crop, with an average of 35.248 kg of tomatoes per kilogram of fertilizer; the 60% deficit ETc the lowest value, with an average of 5.193 kg of tomatoes per kilogram of fertilizer.

This study aims to investigate the mediating role of administrative empowerment in the relationship between ethical leadership and job performance within Yemeni public joint-stock companies, which play a vital role in supporting the national economy. Employing a descriptive quantitative approach, the research utilized Structural Equation Modeling (SEM) to analyze data from 433 employees across eight companies. The measurement model demonstrated strong psychometric properties, with outer loadings ≥ 0.70, composite reliability ≥ 0.86, and Average Variance Extracted (AVE) ≥ 0.56. The structural model revealed a significant impact of ethical leadership on administrative empowerment (β = 0.83) and of administrative empowerment on job performance (β = 0.86), while no direct effect was found between ethical leadership and job performance (β = 0.070). However, administrative empowerment showed a strong mediating effect (β = 0.717), explaining 69% of the variance in administrative empowerment and 85% in job performance, indicating high predictive power. The findings underscore the importance of administrative empowerment as a mechanism through which ethical leadership enhances job performance, offering a practical framework for evaluating and improving performance in Yemen’s public companies.