الخلاصة

يمكن العثور على نفايات البوليمر، التي تستغرق وقتًا لتتحلل، في كل مكان حيث يستخدمها جميع البشر تقريبًا وفي الوقت الحاضر، تتزايد كمية النفايات المصنوعة من البوليمر يومًا بعد يوم مع زيادة عدد سكان العالم مما يؤدي إلى زيادة استهلاك هذه المنتجات. وهذه الزيادة تؤدي إلى استنفاذ الموارد الطبيعية مثل الخشب والبترول بسرعة. وإدراكًا لذلك تم تقديم فكرة إعادة التدوير كطريقة للحد من المشاكل التي تنشأ من عدم إعادة تدويرها. ومن خلال عملية إعادة التدوير، يمكن الحفاظ على الموارد الطبيعية للاستخدام المستقبلي. كما تقلل إعادة التدوير من كمية النفايات وتساعد في مواجهة مشكلة تراكم القمامة وتقلل تكلفة المنتج أيضا لأن تصنيع المنتج من المواد الخام إلى المنتج النهائي يصبح مكلفًا بمرور الوقت. فالمنتجات المعاد تدويرها أرخص دائمًا. ومع ذلك، فإن اختيار إعادة تدوير البوليمر يتطلب الأخذ بعين الاعتبار بعض المعلومات المتعلقة بخصائص مواد النفايات مثل حجمها، وموقعها، وطبيعتها، ودرجة التلوث بالملوثات، ووجود فرص السوق. بناءً على هذه المشكلة، يتم إجراء هذه الدراسة من أجل تطوير مركب من المواد المعاد تدويرها مثل البولي إثيلين منخفض الكثافة المعاد تدويره ونشارة الخشب وكذلك التحقق من ملائمة هذه المجموعة لإعادة البناء. علاوة على ذلك، تحاول هذه الدراسة التطوير والتحقيق في مدى ملائمة استخدام البولي اثيلين المعاد تدويره المملوء داخله نشارة الخشب في تصنيع الألواح الخشبية مع التركيز على الاستقرار والمتانة مع التركيبات المختلفة من خلال دراسة خصائصه من أجل تطوير وتحسين الاستخدام المحتمل لهذا المركب في المستقبل. تم إنتاج عينات من الألواح خلال زيادة نسبة المعزز من النشار بمقدار 10٪ إلى 30٪ إلى 50٪ عند 190 درجة مئوية وضغط 19 كجم / سم2 وزمن الضغط من 9 إلى 12 دقيقة. ومن خلال ذلك تم تحديد الخصائص الميكانيكية لقوة الانحناء، وقوة الشد، وخصائص قوة تأثير الألواح. حيث أظهرت النتائج أن أعلى قيمة لمقاومة الشد 7.87(ميجا باسكال) وقيمة قوة الانحناء 19.80 (ميجا باسكال) وتم الحصول عليها من لوح مكون من 30٪ نشارة الخشب المملوءة في مركب البولي إثيلين منخفض الكثافة المعاد تدويره. وسب ذلك يرجع إلى التوزيع الموحد للمعزز في مركب البولي إثيلين منخفض الكثافة المعاد تدويره هو العامل الرئيسي لتحسين الخصائص الميكانيكية.                                                                            

ABSTRACT

Polymer waste, which takes time to degrade, can be found everywhere as it is used by almost all human being. Nowadays, the amount of garbage or waste that is made of polymer is increasing day after day as the world’s population increases resulting in more consumption these products. This increase of polymer products demand causes natural resources such as wood and petroleum to deplete fast. Realizing this, recycling is introduced as a way to curb the problems that arise. Through the process of recycling, natural resources can be preserved for future use. Also, recycling reduces the amount of waste produce and can help to encounter garbage accumulation problem. It also reduces the cost since manufacturing product from raw material to finished product is getting expensive as time passes. The recycled products are always cheaper. However, the choice of recycling polymer requires taking into consideration some information regarding the characteristics of the waste materials such as scale of the deposit, its location, its nature, degree of contamination by pollutants, and the existence of market opportunities. Based on this problem, this study is done in order to develop composite from recycled material such as WSD and recycled low density polyethylene rLDPE as well as checking this combination’s suitability for refactoring. Furthermore, this study attempts to develop and investigate the suitability of using WSD filled rLDPE in wood board manufacturing with focus on stability and durability with various composite formulations through studying the properties of WSD and rLDPE in order to develop and improve the potential usage of this composite in the future. The composite board is produced by hot pressing the extruded sample by increasing the percentage of WSD from 10 wt%, 30 wt% and 50 wt% at 190°C temperatures and pressure of 19 Kg/cm2 for pressing time 9 to 12 min. The mechanical properties: flexural strength, tensile strength, impact strength properties of boards are determined. The results show that the highest value of tensile strength 7.87 (MPa), and value of flexural strength of 19.80(MPa) are obtained from board of 30 % wood saw dust filled Recycled Low Density Polyethylene composite. The uniform distribution of WSD filler in rLDPE composites is the major factor responsible for the improvement in the mechanical properties.

Keywords: Recycled Low-Density Polyethylene (rLDPE), wood saw dust WSD, Extruder, recycling, filler.

The information related to the effects of psychological stressors on the recovery of injured athletes is essential to discovering the problems the athletes face. The paper provides various information related to the impact of psychological stressors on the recovery of injured athletes from global publications. There are a total of 30 articles have been reviewed and summarized. There are also 50 references used to support the effects of psychological stressors on the recovery of injured athletes. The purpose of providing information related to psychological stressors’ impact on recovering injured papers is to show how athletes change their lives after recovering from the injuries and the effects of injuries. Many types of research conducted in the past have shown different research outcomes to measure the life of the athletes after recovering from the injury. Some studies showed that athletes continue to join the sports after being injured. Some research showed athletes stopped joining sports or changed their lifestyles after recovering from the injury. The stressors caused by the injury may result in fear and anxiety among most athletes. The psychological stressor symptoms will be discussed and reviewed in the paper to other research outcomes. At the end of the article, a common finding about psychological stressors toward the cognitive recovery of injured athletes will be shown. These common findings can reference other research on the same field of study.

In this present work, the effect of variation of parts (pulp and peel) on photochemical 

compounds such as phenolics and flavonoids content of the banana flours were 

studied. The results exhibited that different varieties did exhibit significant differences 

on TPC as well as TFC which means that different sample yielded different values of 

TPC and TFC. The TPC was determined in ethanolic extracts of banana peel and pulp 

flour. The TPC was found to be about 0.40 mg/ml in banana peel and about 0.33

mg/ml in banana pulp. Thus, it is clear that the TPC was higher in the peel than in the 

pulp, while the total flavonoids content was determined in methanolic extracts of 

banana peel and pulp flour. The results showed that TFC was higher in banana peel 

(0.37 mg/ml) than in banana pulp (0.20 mg/ml). 

Key words: banana, catechol , quercetin, total flavonoids, total phenolics.

The study area is the city of Zintan, in northwestern Libya, which has grown over the past

30 years. Its current population is roughly 30,000. Although the city is in part commercial, most

of the population engages in agriculture and primarily grows cereal crops (wheat and barley). The

demand of the growing city for agricultural products has increased, intensifying the use of fertilizers,

pesticides, and insecticides. Consequently, concentrations of potentially toxic elements (PTE) in

the soil have increased. To assess the soil quality (to provide a snapshot of the condition of the

soil), systematic sampling was undertaken across a grid of about 2 km  2 km. The main objective

was to determine the chemical and mineral composition of the area of interest, keeping in mind

the geological footprint of the terrain. The geologic framework itself is not conducive to elevated

concentrations of elements like U, Th, Mo, As, Hg, Pb, and Cr. Therefore, metal concentrations

greater than the amounts in the Earth’s crust are most likely of anthropogenic origin. A total of

143 samples were collected and chemical analyses were performed using a Thermo Fisher Scientific

Niton XL3t GOLDD+ XRF analyzer for the following elements: Mo, Zr, Sr, U, Rb, Th, Pb, Au, Se,

As, Hg, Zn, W, Cu, Ni, Co, Fe, Mn, Cr, V, Ti, Sc, Ca, K, S, Ba, Cs, Te, Sb, Sn, Cd, Pd, and Ag. This

paper provides examples of elevated concentrations, potentially harmful to the environment, such as

those of the following: sulfur of unknown origin (two to three times higher than the Earth’s crust

average); arsenic, given that there are no related natural phenomena (all the samples measured

displayed concentrations higher than those found in the Earth’s crust); mercury (concentrations much

higher than permissible levels); cesium (additional investigations required to determine the origin);

molybdenum; and uranium likely resulting from the use of superphosphates (concentrations nearly

always significantly higher than those in the Earth’s crust).

Purpose

The study aims to propose a predictive model that combines personality and demographic factors to predict student academic performance (SAP). This research study works on understanding, enhancing and applying techniques to enhance the prediction of SAP.

Design/methodology/approach

The authors gathered information from 305 university students from Al-Zintan University Libya. The study uses a survey questionnaire to collect data on essential variables. The purpose of the questionnaire is to discover variables that affect students' academic performance. The survey questionnaire has 44 closed questions with Likert scale designs that were distributed to a variety of college students at the start of the first semester of 2022. It includes questions about demographics, personality, employment and institutional aspects. The authors proposed a predictive model to identify the main fundamental components, consisting of one dependent variable (SAP) and five independent constructs. The suggested model is tested using partial least squares (PLS) and structural equation modeling (SEM), which perform better than covariance-based structural equation modeling (CB-SEM). PLS-SEM performs well with smaller sample sizes, even for complicated models.

Findings

The study results show that the proposed model accurately predicted the student's academic performance. The personality trait variables are a key factor that determines the actual student's academic performance. The student's academic performance is significantly impacted by each variable in the personality trait variables as well.

Originality/value

The process of validating research was done empirically through the accuracy and efficiency of model performance. The study differs from previous studies in that it accumulated a wide range of factors from different dimensions, including student demographics and personality trait factors. The authors developed a structural equation model to predict students' academic performance.