Display omitted
•Molecular dynamics is used to study the mechanical characterization of Gr/WSe2 vertical heterostructures.•Mechanical properties and fracture mechanisms of the Gr/WSe2 are strongly ...direction-dependent.•Fracture initiates from the graphene and WSe2 layers for armchair and zigzag loading, respectively.•The WSe2 sheet undergoes a phase transformation from h-WSe2 to t-WSe2 during zigzag loading.
Assembling layered materials in the form of vertically stacked heterostructures has emerged as a facile way to leverage the properties of each component and fabricate novel highly-tailored architectures with advanced functionalities. In this study, we employ molecular dynamics (MD) simulations to characterize the temperature-dependent tensile mechanical properties of graphene/WSe2 vertical heterostructure along both the armchair and the zigzag directions utilizing a hybrid scheme of various interatomic potentials. It is found that the tensile strength of the WSe2 monolayer can be significantly improved when supported by graphene benefiting from the synergistic effects of their individual strengths. The comparisons of the predicted tensile properties of the heterostructure with that of the mixing rule exhibit excellent conformity. We found that while the bare WSe2 is more resilient to fracture along the armchair direction, the graphene supported WSe2 layer endures larger tensile stress and strain for zigzag loading. This study further reveals fascinating chirality in mechanical properties and failure mechanism of the heterostructure. Fracture initiates from the graphene layer for armchair loading, whereas the WSe2 sheet becomes more prone to fracture under zigzag loading. Crack propagates along the zigzag direction and results in the complete tearing of the specimen for armchair loading, while the crack propagation is confined in a random small region for the zigzag loading. The WSe2 nanosheet experiences major atomic rearrangements and undergoes a phase transformation from trigonal (h-WSe2) to the distorted octahedral phase (t-WSe2) during zigzag loading. Increasing temperature is found to play a crucial role in deteriorating the mechanical properties of the heterostructure. This study offers a comprehensive characterization of the tensile properties of Gr/WSe2 vertical heterostructure and discloses important deformation mechanisms that will enable the efficient utilization of this material.
Background: Cesarean section (CS) stands as the foremost major surgical procedure in contemporary obstetrics. Initially developed primarily to safeguard maternal life during challenging childbirth ...scenarios, its prevalence has shown a concerning upward trajectory in recent times. The aim of this study was to investigate the prevalence and determinants of Cesarean section deliveries in a rural tertiary care hospital. Methods: This was a retrospective observational study and was conducted in the Department of Obstetrics and Gynaecology of Khwaja Yunus Ali Medical College & Hospital, Sirajganj, Bangladesh during the period from January 2018 to December 2019. Results: Out of a total of 1600 deliveries, 390 (24.4%) were vaginal deliveries, while 1210 (75.6%) were cesarean sections respectively. Majority 94.8% patients were 20-34 years old, 1.8% were less than or equal to 19 years and 3.4% were great than or equal to 35 years old respectively. The majority of cesarean sections, 814 (67.3%), were performed as elective procedures and 396 (32.7%) were performed as emergency procedures respectively. Majority 512 (42.3%) were performed on women who had a history of previous cesarean deliveries, 34 (2.8%) were performed due to non-progression or prolonged labor, 99 (8.2%) were performed due to malpresentation of the baby and 308 (25.5%) were performed at the request of the mother respectively. Conclusions: In conclusion, this retrospective observational study provides valuable insights into the prevalence and determinants of caesarean sections in a rural tertiary care hospital. Keywords: Caesarean section rate, Determinants, Indications, Prevalence, Repeat cesarean section
Background: Elevated BP is an important risk factor of cardiovascular diseases; undiagnosed and uncontrolled hypertension is a dangerous situation where target organ damage can occur leading ...morbidity and mortality in apparently healthy individuals. Therefore, with an aim to study the burden of undiagnosed and uncontrolled hypertension, this study with a cross sectional study design is undertaken in rural areas of South Andaman Islands. Methods: A community based cross sectional study. A total of 405 participants (Men: 175, Women: 230) were involved, mean age 48.36±15.16 years (Men: 50.69±16.01 years, Women: 46.58±14.26 years). Results: 30.4% of the participants reported that they are known hypertensives, and out of them only 63.41% were on regular treatment. 17.8% of the participants were first time diagnosed with hypertension during this study. Overall, 48.1% of participants are having hypertension (known hypertensives±newly diagnosed hypertensives), and only 63.20% of them know their status on hypertension. A large proportion are in Pre-hypertension status (52.04%). Conclusions: Almost half of the population are having burden of hypertension, and nearly 1/3rd of them do not know that they have hypertension; and among those who know the status, only 2/3rd of them are on regular treatment; and a large proportion of population is in pre-hypertension. We need to undertake rigorous efforts to unmask, diagnose and treat hypertension in the community.
