Controlled depolymerisation, as assessed by analytical ultracentrifugation, of low molecular weight chitosan for potential use in archaeological conservation

The heterogeneity and molecular weight of a chitosan of low molecular weight (molar mass) and low degree of acetylation (0.1), for potential use as a consolidant for decayed archaeological wood, has been examined by sedimentation velocity and sedimentation equilibriumin the analytical ultracentrifuge before and after depolymerisation. Sedimentation velocity before polymerisation revealed a uniform distribution of sedimentation coefficient with little concentration dependence. SEDFIT-MSTAR analysis revealed a weight average molecular weight Mw of (14.2 + 1.2) kDa, and polydispersity index of ~ 1.2. Further analysis using MULTISIG revealed a distribution of material between 2-20 kDa and consistent with the weight average Mw. Controlled depolymerisation using hydrogen peroxide and UV in an acetic acid medium reduced this to (4.9 + 0.7) kDa, with a similar polydispersity. The depolymerised material appears to be within the range that has been predicted to fully penetrate into archaeological wood. The consequences for this and the use of the analytical ultracentrifuge in wood conservation strategies is considered

Effect of bitumen addition on the long-term permeability of sabkha soil

This study investigates the effect of bitumen addition on the long-term permeability of bitumen mixed sabkha soil. Results will be used to evaluate the effectiveness of using the bitumen mixed sabkha soil as hydraulic barriers to leachate percolation. Eight percent bitumen (by dry weight of sabkha) was selected as a mixing percentage based on density results obtained from modified Proctor tests carried out on sabkha soil samples mixed with different bitumen contents. Long-term permeability studies using distilled water were carried out on undisturbed, natural compacted and 8% bitumen mixed sabkha soil samples. The results displayed significant reduction in the initial and long term permeability values of the 8% bitumen mixed sabkha, as compared to the natural compacted sabkha soil. The reduced permeability values of the 8% bitumen sabkha soil are still higher than the recommended value for soil liners. The results also clearly show that sabkha soil compaction, which is the general practice for liners preparation in Kuwait, is not an effective process

Effect of bitumen addition on the long-term permeability of sabkha soil

This study investigates the effect of bitumen addition on the long-term permeability of bitumen mixed sabkha soil. Results will be used to evaluate the effectiveness of using the bitumen mixed sabkha soil as hydraulic barriers to leachate percolation. Eight percent bitumen (by dry weight of sabkha) was selected as a mixing percentage based on density results obtained from modified Proctor tests carried out on sabkha soil samples mixed with different bitumen contents. Long-term permeability studies using distilled water were carried out on undisturbed, natural compacted and 8% bitumen mixed sabkha soil samples. The results displayed significant reduction in the initial and long term permeability values of the 8% bitumen mixed sabkha, as compared to the natural compacted sabkha soil. The reduced permeability values of the 8% bitumen sabkha soil are still higher than the recommended value for soil liners. The results also clearly show that sabkha soil compaction, which is the general practice for liners preparation in Kuwait, is not an effective process

Commentary on “Exploring Secondary Traumatic Stress as a Post-Pandemic Challenge for Healthcare Workers Practicing in Saudi Arabia” [Response to Letter]

Heba M Ashi,1 Marwah A Afeef,2 Faris M Almutairi,3 Razin H Subahi,4 Emad A Aljohani,5 Zuhair S Natto1 1Department of Dental Public Health, Faculty of Dentistry, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia; 2Department of Research & Studies, Al-Thagher Hospital, Jeddah, Kingdom of Saudi Arabia; 3Department of Respiratory Therapy, Al-Thagher Hospital, Jeddah, Kingdom of Saudi Arabia; 4Specialty Dental Centre. Al-Thagher Hospital, Jeddah, Kingdom of Saudi Arabia; 5Department of Health Services and Hospital Management, Al-Thagher Hospital, Jeddah, Kingdom of Saudi ArabiaCorrespondence: Marwah A Afeef, Department of Research & Studies, Al-Thagher Hospital, Jeddah, Kingdom of Saudi Arabia, Tel +966535732762, Email [email protected]

Association Between Periodontal Diseases and Hypothyroidism: A Case–Control Study

Fatemah Mohammed AlAhmari,1 Hind Saleh Albahouth,2 Hadeel Ali Almalky,2 Ebtihal Saad Almutairi,2 Muzun Hamoud Alatyan,2 Lama Ali Alotaibi2 1Department of Periodontics and Community Dentistry, College of Dentistry, King Saud University, Riyadh, Saudi Arabia; 2College of Dentistry, King Saud University, Riyadh, Saudi ArabiaCorrespondence: Fatemah Mohammed AlAhmari, King Saud University, Riyadh, Saudi Arabia, Email [email protected]: Periodontal diseases are chronic inflammatory disorders influenced by systemic health of the individual. This study aimed to investigate the association between hypothyroidism and periodontal disease in a cohort of adult Saudi population.Methods: This case–control study included 201 adults with hypothyroidism on hormone replacement therapy and 188 healthy controls. The medical files of patients were reviewed to check thyroid stimulation hormone (TSH) and free thyroxine (FT4) levels. Participants completed a questionnaire on demographic and health information, followed by a comprehensive periodontal examination. Pearson chi-square and binary logistic regression analyses determined associations, with a significance set at p ≤ 0.05.Results: Gingivitis was found in 20.9% of cases and 58% of controls. Periodontitis stages I, II, III and IV were in general higher in cases compared to controls (23.4%, 27.9%, 21.9%, 6% in cases versus 13.8%, 17%, 9.6%, 1.6% in controls, respectively). Mean PPD and CAL values were higher in cases (5.54 ± 2.5 and 3.88 ± 3.1) than in controls (4.03 ± 1.6 and 1.72 ± 2.4). Significant associations between periodontal status and hypothyroidism were found (p < 0.0001). The periodontal status in hypothyroid cases correlated significantly with hormone replacement therapy dose and duration (p < 0.0001).Conclusion: The findings of the current study showed that, in a cohort of adult Saudi subjects, patients with hypothyroidism have higher prevalence and more severe periodontal disease symptoms compared to controls, suggesting significant association.Keywords: hypothyroidism, periodontal diseases, hormone replacement therapy, association, case–control stud