Two-dimensional (2D) material-based heterostructures gain increasing interest due to their extraordinary properties and excellent potential for the optoelectronic devices. This study deals with modulation of electronic and optical properties of the ZrS 2 /PtS 2 van der Waals heterostructure under vertical strain and an external electric field based on first principles calculation. Different stacking of ZrS 2 and PtS 2 layers are considered for the heterostructure formation and the most stable structure with lowest binding energy is selected for further calculations. The stable ZrS 2 /PtS 2 heterostructure shows an indirect band gap of 0.74 eV, which is smaller than that of both ZrS 2 and PtS 2 monolayers. With the applied external electric field, the band gap value of the ZrS 2 /PtS 2 heterostructure increases with the negative electric field and decreases with the positive electric field. It is observed that the indirect-to-direct band gap transition occurs when the highest negative value of the electric field is applied. In the case of vertical strain applied to the heterostructure, with an increase in compressive strain, the band gap decreases and vice versa for tensile strain. Optical absorption spectra show significant absorption in the visible light region to the ultraviolet light region. This study shows that the electronic and optical properties of ZrS 2 /PtS 2 heterostructures can be modulated by using vertical strains and an external electric field.

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Background Acute bowel obstruction (ABO) is a common surgical emergency and is associated with significant morbidity and mortality. Currently there is no national guidance for the management of ABO and an NCEPOD study highlighted the resulting variance in care nationwide. This study recommended several standards of care for the management of ABO and we aimed to review our practice against this guidance. Method A retrospective review identified all adult patients admitted with a radiologically confirmed diagnosis of ABO, over an 8 month period. 8 key performance indicators (KPIs) were adapted from the NCEPOD recommendations and data was collected from patient notes, drug charts and computer records. A total of 22 patients are included in this study to date. Results The median length of time from referral to surgical review and from surgical review to CT scan was 112 mins and 134 mins respectively. 31.8% of patients underwent emergency surgery. Pain documentation was the only KPI that met 100% target compliance. A MUST score was completed in 72.7% of cases, a treatment escalation plan in 36.4% of cases, hydration status was documented in 4.5% of cases and no patients had a frailty score documented. Conclusion Our results demonstrate that significant improvements can be made in the management of ABO and the recognition of aspects known to impact patient morbidity and mortality. In keeping with NCEPOD recommendations we suggest the implementation of an ABO pathway. We hope this will assist clinicians in caring for patients with ABO, promote MDT collaboration and highlight clinical concerns early.