المستودع الرقمي لـجامعة طرابلس

أتاحت طريقة البوتستراب ( Bootstrap) التي قدمها العالم إيفرون (Efron, 1979) إجراء العديد من الأبحاث في مجال الاحصاء وغيرها من المجالات , والتي كانت لولا ذلك ستكون صعبة إن لم تكن مستحيلة. لقد أصبحت طريقة البوتستراب تأخذ جانباً مهماً في أغلب البحوث الإحصائية خاصة فيما يتعلق بالبحوث الطبية. تم في هذه الورقة تزويد الباحث بمقدمة مختصرة عن طريقة البوتستراب, كما تم تقديم شرح مبسط لكيفية استخدام الوتستراب لحساب الخطأ المعياري لمتوسط العينة, والخطأ المعياري لوسيط العينة, بالإضافة إلى كيفية استخدام طريقة الوتستراب في تكوين فترات ثقة لكل من المتوسط الحسابي والوسيط بمستوى ثقة معين باستخدام طريقة فترة بوتستراب المئوية (percentile Bootstrap Interval). لتمكين الباحث من تطبيق طريقة البوتستراب بكل سهولة ويسر فقد تم في هذه الورقة تقديم شرح وافي وواضح لكيفية تطبيق طريفة البونسراب باستخدام برنامج ماتلاب (MATLAB Software), وفي نهاية الورقة تم تقديم دالة ماتلاب, تحمل اسم Bootstrap_ci , وظيفتها الأساسية هي ايجاد فترات ثقة لمتوسط ووسيط المجتمع باستخدام طريقة البوتستراب المئوية.
سعاد محمد احمد البرقاوي, البهلول عمر شلابي(12-2021)

منذ أن قام كل من بوكس وكوكس بكتابة ورقتهما الأصلية خلال سنة 1964والتي عرضت نوع من التحويلات القوة التي تهدف إلى تحويل البيانات التي لا تتبع التوزيع الطبيعي إلى بيانات تتبع التوزيع الطبيعي , هذا النوع من تحويلات القوة كان ذو أهمية كبيرة لدى الباحثين, سواء في البحوث النظرية أو في التطبيقات العملية (BOX and COX 1964) . هذه الورقة تطرقت إالى الموضوعات التالية المتعلقة بتحويلة القوة لبوكس - كوكس: * التعريف بتحويلة القوة لبوكس- كوكس *أستعراض مختصر لبعض الدراسات السابقة حول التحويلة. *شرح لكيفية تقدير معلمة تحويلة القوة لبوكس- كوكس بطريقتين مختلفتين وذلك بالإستعانة بالبرمجة ماتلاب (MATLAB Software) . عرض لبعض طرق الكشف عن مدى نجاح تحويلة القوة لبوكس- كوكس في تحويل البيانات التي لا تتبع إلى بيانات التوزيع الطبيعي.
سعاد محمد احمد البرقاوي, د البهلول عمر شلابي(12-2021)

This study was conducted to investigate the presence of Enterococcus spp. in meat, meat products and seafood. A hundred and four samples were randomly collected from different geographic localities in Libya. The samples were subjected to microbiological analysis for enumeration and isolation of Enterococcus spp. by conventional cultural and molecular identification using PCR and partial sequencing of 16S rDNA techniques. Out of 104 samples, 73 (70.2%) isolates were found to be enterococci based on their cultural characteristics on ESD medium. However, out of 36 samples subjected to molecular identification, only six isolates were confirmed to be Enterococcus spp. using PCR and partial sequencing of 16S rDNA technique. All enterococci strains tested for their antibiotic sensitivity profiles showed high percentage of multi-resistance phenotype. These results can be used for further studies on enterococci as an emerging food borne pathogen and its role in human infection in Libya and would suggest that meat, meat products and seafood might play a role in the spreading of enterococci through the food chain with antimicrobial resistance characteristics.
Salah M. Azwai(1-2017)

Background: Cronobacter sakazakii is associated with illness in infants from contaminated powdered infant formula (PIF) and it is frequently recovered from PIF factory environment. Limited information is available on contamination of other food such as dairy and meat products in Libya. Methods and Findings: A total of 261 samples of milk, dairy products and coarse ground meat products were collected from different localities in Libya. Samples were examined for Cronobacter spp. with an adapted ISO /DTS 22964 cultural protocol using HiChrome™ Enterobacter sakazakii modified agar coupled with 16S rDNA partial sequencing to identify the organism. The identified isolates were biochemically characterized and tested for their ability to produce yellow pigment. Out of the 261 analyzed samples, only two beef burgers, one fermented milk “Laban”, one she-camel’s milk, two raw cow’s milk, two cereal baby food, one Maassora cheese and one ready to feed baby milk were contaminated with Cronobacter spp. at a total rate of 3.8%. Accuracy of HiChrome Ent. sakazakii modified agar reach 100% as all of blue-green presumptive colonies were confirmed Cronobacter spp. while other colorless, greenish or with blue center colonies which competed growth with Cronobacter spp. were predominantly Escherichia coli followed by Klebsiella spp. and to less extent Pseudomonas luteola, Citrobacter freundii and Acinetobacter baumanii. Moreover, the isolated strains of Cronobacter were resistant to Amoxicillin, Erythromycin, Vancomycin and Streptomycin, and sensitive to Doxycycline, Enrofloxacin and Gentamycin. Conclusion: This study documents for the first time the occurrence of Cronobacter spp. in beef burger, raw cow’s m​i​ …
Salah M. Azwai(1-2018)

Background: This study was conducted to investigate the presence of Bacillus cereus in meat, meat products and some seafood in Libya. Materials and Methods: A hundred and thirty one samples were collected from different geographic localities in Libya. The samples were subjected to microbiological analysis for enumeration and isolation of B. cereus by conventional cultural, biochemical and molecular identification by using PCR and partial sequencing of 16S rDNA techniques. Results: Out of 131 samples, only 38 (29%) isolates were found to be B. cereus based on their cultural characteristics on MYP medium, that included 30% beef, 38.2% beef products (minced, burger, kabab and sausage), 31.8% camel meat and 48% chicken products (burger, sausage, kabab and liver). However, B. cereus was not detected from mutton and seafood samples. Seventeen isolates were subjected to molecular identification by using PCR and partial sequencing of 16S rDNA technique and confirmed to be B. cereus. The confirmed B. cereus strains tested for their antibiotic sensitivity profiles and showed high percentage of multi-resistance phenotype. Conclusions: The results provide better understanding of B. cereus isolated from food of animal origin in Libya and suggest that meat and meat products might play an important role in the spreading of B. cereus through the food chain with antimicrobial resistance characteristics.
Salah M.Azwai(1-2018)

Aim: The aim of the current investigation was to screen the presence of Staphylococci spp., especially S. aureus in meat, meat products of different animal species, and some seafood sold in some retail markets in Libya using cultural and molecular techniques, and to study their antibiotics resistance profiles. Materials and Methods: A total of 139 samples from red meat, meat products, and seafood were collected from many areas in Libya. Enumeration and isolation of Staphylococci spp. and S. aureus by normal cultural methods followed by molecular identification using molecular techniques by bacterial DNA extraction and partial sequencing of 16S rDNA. Results: Out of 139 samples, 112 (80.6%) were contaminated with different species of Staphylococci based on cultural characteristics of Staphylococci on Baird-Parker medium, for which S. aureus was detected in only 32 samples (23%). However, only six out of 18 (33.3%) isolates sent for sequencing were confirmed to be S. aureus using the molecular technique. The six identified isolates of S. aureus were tested for antimicrobial resistance against 24 most commonly used antibiotics. All isolates were resistant to only two antibiotics (cefotaxime and clindamycin). Among these six isolates, only one confirmed to be Methicillin-resistant Staphylococcus aureus. Conclusion: Results of this study suggest that food of animal origin could be a source of S. aureus with antimicrobial resistance characteristics that can be spread through the food chain, and raise the importance of these results for public health.
Salah M. Azwai(1-2019)

Natural products including alkaloids from algae may provide alternative source for new natural antioxidants due to their novel structure. In the present study the antioxidant properties of alkaloids extracted from Sargassum hornschuchii and Cystoseira compressa were assessed using various in vitro systems including 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide, hydroxyl radicals, nitric oxide (NO) scavenging, phosphomolybdenum reduction and reducing power activity at different concentrations (6.25 to 100 mg/ml). The results showed that alkaloids rich extracts exhibit antiradical activity and reduction ability in concentration dependent. Extracts exhibit significant low scavenging activity on DPPH and nitric oxide radical activity Investigation … Rabia Alghazeer et al. compared to standard, ascorbic acid and butylated hydroxyanisole (BHA). Reducing power and total antioxidant of extracts showed less effect compared to standard, ascorbic acid and butylated hydroxyanisole (BHA). Superoxide, and hydroxyl radical assays showed a comparable scavenging activity compared to its standard. Therefore, new separation, purification techniques, and powerful identification methods are recommended to improve their antioxidant activity.
Salah M. Azwai(1-2019)

Background: Whole muscle meat, meat products, and seafood contain different nutrients in adequate quantity providing a better environment for presence and replication of different microorganisms. There are underreported and inaccurate estimations of foodborne diseases due to the lack of effective surveillance systems in Libya. Aim: To determine the extent of microbiological contamination of whole muscle meat, meat products, and seafood. Methods: A total number of 731 samples of retail meat were collected from different stores in four cities in Libya. Samples were analyzed for aerobic plate count and subjected to microbiological enumeration and isolation techniques, followed by molecular identification by PCR and partial sequencing of 16S rDNA. Results: The results showed contamination of samples with enteric and spoilage bacteria. Fifteen genera of spoilage bacteria yielded 149 isolates which were detected and identified by PCR and partial sequencing of 16S rDNA as: Proteus spp., Provedencia spp., Raouttella ornithinolytical, Citrobacter spp., Enterobacter spp., Morganella morgi, Shewanella algea, Rhodobacter capsulatus, Listonella pelagia, Kluyvera spp., Pectobacterium spp., Brenneria spp., Klebsiella spp., Acintobacter radioresistens, and Pantoea spp. While for pathogenic bacteria, 143 isolates distributed among nine genera were identified by PCR and partial sequencing of 16S rDNA as: Bacillus spp., Escherichia spp., Shigella spp., Enterococci spp., Cronobacter spp., Staphylococci spp., Salmonella spp., Aeromonas spp., and Vibrio spp.. Many isolated bacteria are zoonotic bacteria with high importance for public health. Conclusion: Excessive handling and processing of meat and meat products seems to be one of the poorest microbiological qualities. These findings ought to be helpful in risk assessments and quality assurance of meat in order to improve food safety.
Salah M. Azwai(1-2020)