Polyvinylpyrrolidone (PVP) is a widely utilized polymer in pharmaceutical formulations, nanocomposites, biomedical devices, and membrane fabrication. Despite numerous thermogravimetric studies, detailed mechanistic insight into its volatile degradation products remains limited. This study aims to investigate the thermal decomposition mechanism of PVP using thermogravimetric analysis coupled with Fourier-transform infrared spectroscopy (TG–FTIR) under inert and oxidative atmospheres. Degradation stages, evolved gaseous species, and structural transformations were systematically analyzed between 30–800 °C. Results are expected to reveal multi-step degradation involving dehydration, pyrrolidone ring opening, backbone scission, and carbonaceous residue formation. Identification of CO₂, CO, amide fragments, vinylpyrrolidone monomers, and nitrogen-containing volatiles will clarify the degradation pathway. The study provides mechanistic confirmation complementary to kinetic models and enhances predictive understanding of PVP behavior during sterilization, extrusion, pyrolysis, and composite processing.

This paper presents a comprehensive analysis of load expansion planning through the integration of photovoltaic systems at the Bir Alganame 220/30 kV substation. An electrical planning system serves as a crucial tool for designing electrical systems that effectively meet evolving energy demands. The study investigates the impact of load expansion on hybrid photovoltaic system design, focusing on system reliability and total project cost as primary design objectives. The research methodology encompasses a detailed load flow study conducted in 2024, coupled with load forecasting for 5 and 10-year horizons at an 8% load increase rate. The investigation includes analyzing the optimal parameters of the PV system integration with the existing grid to ensure proper functionality. Additionally, the study addresses the probabilistic scenario set of load demand and natural characteristics of renewable energy, which is crucial for power system planning studies. The research emphasizes the importance of proper transmission system network development to reliably and securely evacuate the generated power to meet future domestic load demand. Through simulation and analysis, this study demonstrates an integrated approach to improving power system performance while considering geographical and environmental factors affecting PV output. The findings provide valuable insights into optimal electrical network planning procedures, incorporating both long and short-term perspectives through PV system integration.

Boerhavia erecta has been recorded for the first time in the flora of Libya. This widespread wild

weed was collected in 2023 and 2024 from multiple locations, all included in the regions Sabha and Ariggiba,

and situated approximately 110 km southwest of Sabha city. This species, known for its adaptability to

disturbed habitats and arid conditions, holds ecological significance in its native and introduced ranges. To

facilitate its accurate identification and support future research efforts, a comprehensive description of the

species is provided, along with data about the habitat and a distribution map. These findings offer valuable

insights into the plant’s occurrence, ecological preferences, and adaptability within Libya's unique climatic

conditions. Additionally, the study discusses the potential threats posed by Boerhavia erecta to native plant

flora and vegetation. Emphasis is placed on the importance of monitoring the spread of B. erecta and

conducting further studies to assess its ecological impact in Libya. This record not only highlights the plant's

expansion but also underscores the need for continued floristic surveys to document and preserve the

country's rich biodiversity.

Abstract

Vocabulary acquisition is a cornerstone of foreign language development, yet traditional instructional methods often fail to engage young learners or support long-term retention. This study investigates the effectiveness of using songs as a pedagogical tool for teaching English vocabulary to young English as a Foreign Language (EFL) learners. Employing a quasi-experimental quantitative design, the research compares the vocabulary acquisition of a group of primary school students (aged 6–10) instructed through songs with a control group receiving conventional instruction. Data were collected through pre- and post-tests, classroom observations and teacher feedback. The findings reveal that the experimental group demonstrated significantly greater improvement in vocabulary retention and recall compared to the control group. Furthermore, students in the song-based group exhibited higher levels of motivation, engagement and improved pronunciation. The study concludes that integrating songs into EFL instruction creates an interactive, stimulating and low-anxiety learning environment, making it a highly effective strategy for enhancing vocabulary acquisition among young learners.

Keywords: vocabulary acquisition, songs, young EFL learners, music-based instruction, vocabulary retention

Polyvinylpyrrolidone (PVP; poly(N-vinylpyrrolidone)) is a versatile water-soluble polymer widely used in pharmaceuticals, coatings, and nanocomposites due to its solubility, biocompatibility, and film-forming properties. Despite its extensive applications, systematic kinetic data describing its thermal degradation remain limited. In this study, non-isothermal thermogravimetric analysis (TGA) of PVP was performed under nitrogen and air atmospheres at heating rates of 5, 10, 20, and 40 °C min⁻¹. Thermal profiles revealed three degradation stages: moisture loss (30–150 °C), main-chain scission and depolymerization (150–450 °C), and carbonaceous residue formation (>450 °C), with the principal decomposition peak at 370–410 °C. Activation energies (Eₐ) determined using Kissinger, Flynn–Wall–Ozawa (FWO), and Kissinger–Akahira–Sunose (KAS) methods ranged from 179 to 186 kJ mol⁻¹ and were validated using the Coats–Redfern model-fitting approach. Reaction orders (n ≈ 1.1–1.3) indicate random chain scission as the dominant mechanism. The resulting kinetic dataset provides reliable insight into PVP thermal stability and supports optimization of processing, recycling, and composite fabrication.

Abstract:

This study aimed to evaluate stress distribution around two and four implants supporting maxillary implant overdentures retained by locator attachments, comparing full and partial palatal coverage designs. Four identical acrylic models representing completely edentulous maxillary arches were fabricated and covered with polyvinyl siloxane impression material to simulate the oral mucosa overlying the residual ridge. The models were divided into two main groups according to the number of installed implants (two or four), and each group was further subdivided based on palatal design (full or partial palatal coverage). Locator abutments (female components) were secured to the implants using an abutment driver, after which the prosthetic frameworks were constructed. Four strain gauges were bonded to each implant fixture using strain gauge cement to record strain values. A LLOYD digital loading device was employed to apply controlled compressive loads, and the resulting stresses around the implants were measured for each configuration.

Statistical analysis revealed a significant difference in stress values between two-implant overdentures with full palatal coverage (30.64 ± 17.47 N/m × 10²) and those with partial palatal coverage (49.72 ± 23.17 N/m × 10²), with higher stresses observed in the partial coverage design. In contrast, although four-implant overdentures with partial palatal coverage (8.77 ± 4.54 N/m × 10²) demonstrated higher mean stress values than those with full palatal coverage (5.51 ± 3.83 N/m × 10²), this difference was not statistically significant.

Within the limitations of this in vitro study, full palatal coverage design resulted in lower stress values compared to partial palatal coverage in two-implant-supported maxillary overdentures. For four-implant-supported overdentures, full palatal coverage also showed lower stress values; however, the difference was not statistically significant.

This study compared the retention of polyamide clasps engaging porcelain-fused-to-metal and zirconia retainers with identical 0.50 mm undercuts in posterior free-end saddle maxillary removable partial dentures. Four standardized acrylic resin models simulating maxillary bilateral posterior edentulous with first premolar abutments were prepared to receive either porcelain-fused-to-metal or zirconia crowns incorporating mesial occlusal rest seats. Polyamide RPA clasps were fabricated using an injection molding technique and tested for retention using a universal testing machine at a crosshead speed of 5 mm/min. The mean retention force of polyamide clasps was 6.68 ± 2.59 N for zirconia crowns and 5.47 ± 2.27 N for porcelain-fused-to-metal crowns. The results demonstrated minimal loss of retention for polyamide clasps against both ceramic materials, with no significant difference in retention related to the type of ceramic retainer.

Abstract:

This study aimed to compare the amount of stress generated on two versus four implants with equator attachments in maxillary implant overdentures with palatal coverage and palateless designs. Four standardized educational edentulous maxillary models simulating bone type II were used. The models were divided into two main groups according to palatal design (palatal coverage and palateless), and each group was further subdivided based on the number of implants (two or four implants). In the two-implant subgroup, implants were placed bilaterally in the canine regions perpendicular to the residual ridge using a surgical stent, whereas in the four-implant subgroup, implants were installed bilaterally in the canine and second premolar regions. Equator attachments with appropriate cuff heights were selected, and framework patterns were constructed. Four strain gauges were cemented to each fixture using strain gauge cement. A LLOYD digital loading device was used to apply compressive loads to measure the resulting stresses around the implants for each attachment configuration. The results demonstrated a statistically significant difference between stresses on two implants with equator attachments (74.53 ± 35.9 N/m × 10²) and four implants with equator attachments (10.85 ± 10.81 N/m × 10²) within the same palatal coverage design. Similarly, a statistically significant difference was found between stresses on two implants with equator attachments (123.75 ± 44.60 N/m × 10²) and four implants with equator attachments (14.51 ± 14.60 N/m × 10²) within the same palateless design. It was concluded that stress on two implants with equator attachments was markedly greater in the palateless design compared with the palatal coverage design, whereas stress on four implants with equator attachments was slightly greater in the palateless design than in the palatal coverage design, with no statistically significant difference.