Novel Method for Assessing Moisture Damage in Asphalt Mixtures

Moisture damage is a major cause of early pavement deterioration and often accelerates other distresses such as rutting, fatigue cracking, and raveling. Water infiltrates into the pavement structure through the cracks and air voids and weakens the adhesive bond between the binder and the aggregates as well as the cohesive bond between the binder particles. Several tests have been adopted to test for moisture susceptibility, most commonly the Modified Lottman (AASHTO, T283) and the Hamburg Wheel Tracking Device (AASHTO, T32404), however, these tests correlate poorly with field results and do not properly replicate the conditions which a pavement structure experiences in the field. Also, the mechanism which determines the mode of failure due to moisture damage, being either adhesive or cohesive, remains largely not understood, and the research tackling this issue is very scarce. The objective of this study is to introduce a new testing procedure based on the pull-off approach and study the factors which influence the mode of failure of the samples, such as the asphalt film thickness and loading rate

Synthesis of nanoporous carbohydrate metal-organic framework and encapsulation of acetaldehyde

Gamma cyclodextrin (γ-CD) metal organic frameworks (CDMOFs) were synthesized by coordinating γ-CDs with potassium hydroxide (KOH), referred hereafter as CDMOF-a, and potassium benzoate (C7H5KO2), denoted as CDMOF-b. The obtained CDMOF structures were characterized using nitrogen sorption isotherm, thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). High surface areas were achieved by the γ-CD based MOF structures where the Langmuir specific surface areas (SSA) of CDMOF-a and CDMOF-b were determined as 1376 m2 g−1 and 607 m2 g−1; respectively. The dehydrated CDMOF structures demonstrated good thermal stability up to 250 °C as observed by the TGA studies. XRD results for CDMOF-a and CDMOF-b reveal a body centered-cubic (BCC) and trigonal crystal system; respectively. Due to its accessible porous structure and high surface area, acetaldehyde was successfully encapsulated in CDMOF-b. During the release kinetic studies, we observed peak release of 53 μg of acetaldehyde per g of CDMOF-b, which was 100 times greater than previously reported encapsulation in β-CD. However, aldol condensation reaction occurred during encapsulation of acetaldehyde into CDMOF-a. This research work demonstrates the potential to encapsulate volatile organic compounds in CDMOF-b, and their associated release for applications including food, pharmaceuticals and packaging

A Retrospective Study of Non-Communicable Diseases amongst Blue-Collar Migrant Workers in Qatar

BACKGROUND: South Asian workers have a greater predisposition to non-communicable diseases (NCDs) that is exacerbated by migration and length of residence in host countries. Aims: To examine the association between length of residence in Qatar with diagnosis of NCDs in male blue-collar workers. METHODS: A retrospective investigation of the electronic health records (EHRs) of 119,581 clinical visits by 58,342 patients was conducted. Data included age, nationality and confirmed ICD-10 diagnosis. Based on duration of residence, the population was divided into groups: ≤6 months, 6–12 months, 1–≤2 years, 2–≤5 years, 5–≤6 years, >6 years. It was assumed that the group that had been resident in Qatar for ≤6 months represented diseases that had been acquired in their countries of origin. Results: South Asian (90%) patients presented with NCDs at a younger (mean ± SD age of 34.8 ± 9.0 years) age. Diabetes and hypertension were higher in those who had just arrived (<6 months’ group), compared to the other durations of residence groups. Conversely, acute respiratory infections, as well as dermatitis and eczema, all increased, perhaps a consequence of shared living/working facilities. Only patients with diabetes and hypertension visited the clinic multiple times, and the cost of medication for these NCDs was affordable, relative to earnings. DISCUSSION/CONCLUSIONS: Blue-collar workers were predominantly South Asian, from lower socioeconomic classes, with early onset chronic NCDs. Notably, residence in Qatar gave them better access to affordable, significantly subsidized healthcare, leading to effective management of these chronic conditions