Free-space optical communication (FSO) is an innovative technology that uses light rays to transmit data over the air, providing a wireless alternative to traditional cables. However, the performance of this system is greatly affected by severe weather conditions such as fog, rain, humidity, and atmospheric turbulence, which degrade the quality of communication and pose challenges that require precise solutions. This paper aims to analyze the impact of these environmental factors on the performance of the FSO system using three main criteria: the bit error rate (BER) to evaluate the accuracy of data transmission, the signal-to-noise ratio (SNR) to assess the quality of communication, and the total attenuation induced by each atmospheric condition to quantify its effect on signal degradation. The On-Off Keying (OOK) modulation technique was adopted due to its simplicity and widespread use in optical communication systems. Using MATLAB, simulation models representing different weather scenarios were employed to analyze the performance of the FSO system under varying environmental conditions. The effects of atmospheric changes on system behavior are studied and evaluated to gain a deeper understanding of its operation and limitations. Also, in this paper a further enhancement is introduced to the system by integrating Multiple-Input Multiple-Output (MIMO) technology to improve its performance under challenging conditions as a solution.

This study presents a strategic synthetic approach to functionalize the traditionally unreactive C3 position of the benzothiophene core. A series of 3-chloro-N-(aryl)benzothiophene-2-carboxamides (2a–d) were synthesized in good to excellent yields (53–83%) via amidation of 3-chloro-2-chlorocarbonylbenzothiophene[b]thiophene (1).Subsequent oxidation with hydrogen peroxide in acetic acid afforded the corresponding sulfone derivatives (3a–d), a transformation that reduced aromaticity and activated the C3 position. This activation enabled anucleophilic aromatic substitution, where chlorine in sulfone 3b was replaced by ethylamine, isopropylamine, and diethylamine, yielding novel 3-aminobenzothiophene-1,1-dioxides (4a–c) in moderate yields (50–64%). All new compounds were fully characterized by IR, ¹H NMR, and ¹³C NMR spectroscopy. The synthesized derivatives were evaluated in vitro for antimicrobial activity against Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), and fungal strains (Candida albicans, Crysosporium pannical, Aspergillus niger, Rhizopus oryzae). While overall activities were slight to moderate compared with standard drugs, compounds 3a and 3b displayed a promising broad-spectrum profile. These findings establish an efficient and versatile methodology for accessing C3-functionalized benzothiophenes, providing a valuable foundation for the design of new lead structures against resistant microbes.

The approach to delivering education in Libya has undergone a significant transformation in recent years. Various tools now support the educational process, shifting it from rote learning to creativity, interaction, and skill development. This study aims to examine the feasibility of implementing e-learning in Libyan universities. A statistical analysis was conducted on approximately 400 samples to identify patterns. The findings highlight the importance of e-learning in enhancing the quality of education by outlining its benefits and limitations. Moreover, it was found that employees consider e-learning an effective alternative to traditional education. Despite this consensus, concerns remain regarding the availability of sufficient infrastructure. 

Abstract— In order to better control the 3-DOF helicopter model, this work is constructed to fulfill and satisfy high performance requirements while taking robustness, reference tracking, and actuator effort into consideration. As a result, the helicopter model dynamics were modeled and shown in a state-space for the first time utilizing the system identification technique. MATLAB was used to identify, design, and simulate the H∞ controller for the nonlinear system. This ideal controller, known as LQG (Linear Quadratic Gaussian), was created, modeled, and applied to the actual model for the nonlinear system using MATLAB. Both controllers' outcomes were displayed. An explanation of the fundamental distinctions between the H∞ controller and the LQG controller is also provided.

Keywords— H∞ controller, LQG controller, 3-DOF helicopter model, MATLAB/SIMULINK

Abstract

Complete dentures remain an essential treatment option for edentulous patients, especially in regions where implant-supported prostheses are limited. Successful prosthodontic outcomes require systematic execution of clinical steps, including patient examination, impression taking, custom tray fabrication, jaw relation recording, try-in, and post-insertion management. This study aimed to assess the knowledge of complete denture fabrication among fourth-year dental students. A descriptive cross-sectional design was employed among 37 students (94.9% response rate) enrolled in 2024 at the Department of Prosthodontics, Faculty of Oral and Dental Medicine, Gharyan University. Data were collected using a validated, self-administered questionnaire covering patient assessment, primary and final impressions, custom tray design, jaw relation records, occlusal plane orientation, articulator use, try-in procedures, and post-insertion care, and analyzed descriptively.

All students (100%) reported performing histories, oral examinations, primary impressions with alginate, and centric relation registration. Knowledge gaps were observed in advanced procedures: 75.7% selected light-cure acrylic for custom trays, awareness of spacers, stops, and relief holes was limited, polyvinylsiloxane was the most frequently used final impression material (62.2%), yet 59.5% disinfected impressions improperly with water alone. None used a face bow or semi-adjustable articulators, relying solely on non-adjustable types. Students demonstrated solid foundational knowledge of basic procedures; however, deficiencies in custom tray design, post-palatal seal determination, impression disinfection, and articulator use indicate a need for enhanced clinical teaching and practical training to meet current prosthodontic standards.

Keywords. Complete Denture, Dental Students, Prosthodontics, Impression Technique.

Abstract:

The present study concentrated on samples of Libyan dates procured from the markets in Gharyan City. A series of qualitative analyses were conducted in order to assess the content of their active ingredient, with a particular focus on antioxidants. The qualitative identification of tannins, flavonoids, glycosides, saponins, and resins (utilised as tanning agents) was conducted utilising standard reagents such as Dragendorff's, Fehling's, and Benedict's, in conjunction with date extracts. The analyses confirmed the presence of all these compounds in the samples. Furthermore, quantitative assessments of the fundamental components of the date samples were conducted. The procedure entailed the quantification of fibre, carbohydrates, protein, fat, and ash content. Furthermore, the moisture content and the ratio of pits to fruit were evaluated in all samples. The assessment employed a kiln, a Kjeldahl apparatus, and other requisite equipment to determine the caloric values of each sample. The findings indicated variations in the fundamental components and energy content among the samples, likely attributable to various factors and conditions.

Keywords: Dates, antioxidants, free radicals, plant active ingredients