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Abstract Whilst most patients infected with COVID-19 make a full recovery, around 1 in 33 patients in the UK report ongoing symptoms post-infection, termed ‘long COVID’. Studies have demonstrated that infection with early COVID-19 variants increases postoperative mortality and pulmonary complications for around 7 weeks after acute infection. Furthermore, this increased risk persists for those with ongoing symptoms beyond 7 weeks. Patients with long COVID may therefore also be at increased postoperative risk, and despite the significant prevalence of long COVID, there are minimal guidelines on how best to assess and manage these patients perioperatively. Long COVID shares several clinical and pathophysiological similarities with conditions such as myalgic encephalitis/chronic fatigue syndrome and postural tachycardia syndrome; however, there are no current guidelines for the preoperative management of these patients to help develop something similar for long COVID patients. Developing guidelines for long COVID patients is further complicated by its heterogenous presentation and pathology. These patients can have persistent abnormalities on pulmonary function tests and echocardiography 3 months after acute infection, correlating with a reduced functional capacity. Conversely, some long COVID patients can continue to experience symptoms of dyspnoea and fatigue despite normal pulmonary function tests and echocardiography, yet demonstrating significantly reduced aerobic capacity on cardiopulmonary exercise testing even a year after initial infection. How to comprehensively risk assess these patients is therefore challenging. Existing preoperative guidelines for elective patients with recent COVID-19 generally focus on the timing of surgery and recommendations for pre-assessment if surgery is required before this time interval has elapsed. How long to delay surgery in those with ongoing symptoms and how to manage them perioperatively are less clear. We suggest that multidisciplinary decision-making is required for these patients, using a systems-based approach to guide discussion with specialists and the need for further preoperative investigations. However, without a better understanding of the postoperative risks for long COVID patients, it is difficult to obtain a multidisciplinary consensus and obtain informed patient consent. Prospective studies of long COVID patients undergoing elective surgery are urgently required to help quantify their postoperative risk and develop comprehensive perioperative guidelines for this complex patient group.

This work experimentally examines the effect of methane (a natural gas surrogate) substitution on early injection dual fuel combustion at representative low loads of 3.3 and 5.0 bar BMEPs in a single-cylinder compression ignition engine. Gaseous methane fumigated into the intake manifold at various methane energy fractions was ignited using a high-pressure diesel pilot injection at 310 °CA. For the 3.3 bar BMEP, methane energy fraction sweeps from 50% to 90% were performed; while at 5.0 bar BMEP, methane energy fraction sweeps from 70% to 90% were performed. It is observed that minimum methane energy fraction is limited by maximum pressure rise rate leading to knock and maximum methane energy fraction is limited by a high coefficient of variation in netIMEP, which leads to high cyclic variations. For 3.3 bar BMEP, maximum pressure rise rate is 8 bar/°CA at 50% methane energy fraction while at 5 bar BMEP, it is 12 bar/°CA at 70% methane energy fraction. For 3.3 bar BMEP, engine-out NOx emissions decrease by 43 times when methane energy fraction increases from 50% to 90%, and it decreases by nearly 46 times when methane energy fraction increases from 70% to 90% at 5 bar BMEP. Engine-out unburned hydrocarbon emissions increase by nearly 9 times when methane energy fraction increases from 50% to 90% at 3.3 bar BMEP, and it increases by nearly 5 times when methane energy fraction increases from 70% to 90% at 5.0 bar BMEP. Engine-out carbon monoxide emissions increase by nearly 7 times when methane energy fraction increases from 50% to 90% at 3.3 bar BMEP and by nearly 5 times when methane energy fraction increases from 70% to 90% at 5.0 bar BMEP. In addition, cyclic combustion variations at both loads were analyzed to obtain further insights into the combustion process and identify opportunities to further improve fuel conversion efficiencies at low load operation. [ABSTRACT FROM AUTHOR]

This article discusses the surgical management of penoscrotal lymphedema, a condition characterized by swelling of the penis and scrotum due to reduced lymphatic flow. The case study focuses on a 38-year-old male patient who experienced swelling for four years, leading to discomfort, mobility issues, and recurring infections. The surgical procedure involved removing the edematous penile and scrotal skin, preserving unaffected skin, and using split skin grafts for reconstruction. The patient had a successful recovery with no reported complications. The article emphasizes the importance of early diagnosis and intervention to prevent irreversible skin changes and highlights the impact of genital lymphedema on physical and emotional well-being. [Extracted from the article]

Dual-fuel low-temperature combustion is a possible solution for alleviating the tradeoff between oxides of nitrogen and soot emissions in conventional diesel combustion, albeit with poor combustion stability, high carbon monoxide, and unburned hydrocarbon emissions at low engine loads. The present work compares emissions and combustion (heat release and other metrics) of both diesel and poly-oxy methylene dimethyl ether as high-reactivity fuels to ignite natural gas while leveraging spray-targeted reactivity stratification, which involved multiple injections of the high-reactivity fuels. The experiments included six parametric sweeps of: (1) start of first injection, (2) start of second injection, (3) percentage of energy substitution of natural gas, (4) commanded injection duration ratio, (5) rail pressure, and (6) intake pressure. The experiments were performed on a 1.8 L heavy-duty single-cylinder research engine operating at a medium speed of 1339 rev/min. Not-to-exceed limits for the indicated oxides of nitrogen emissions, maximum pressure rise rate, and the coefficient of variation of the indicated mean effective pressure were set to 1 g/kWh, 10 bar/CAD, and 10%, respectively. The indicated emissions decreased and combustion improved significantly for both fueling combinations when the experimental procedure was applied.

In light of global warming and the rising urban population across the world, freshwater is becoming a scarce commodity. Freshwater consumption in the production of concrete makes up a significant (9%) share of total freshwater withdrawal for industrial purposes. Among the alternative sources of water for concrete production, seawater involves minimal processing, besides screening debris with filters. Other options, such as the use of wastewater from industrial effluent or desalination of hard waters, require a significant amount of energy, which add to overall concrete production emissions. Many efforts have been made by researchers in the last decades to understand the behaviour of seawater-mixed and sea sand concretes (SW-SS). The present work evaluates the early-age hydration, fresh, mechanical, and durability performance of SW-SS concretes and the corrosion characteristics of embedded reinforcement in them. The authors also summarize mitigation measures recommended in the literature for improving the anti-corrosion performance of SW-SS concretes, by partial substitution of supplementary cementitious materials (SCMs), the inclusion of alternative reinforcements (such as stainless steel and fibre reinforced polymer bars), the incorporation of corrosion inhibitors, and the adaptation of cathodic prevention measures. Finally, the article highlights the possible challenges to, opportunities for and potential applications of SW-SS concretes in the near future, so as to combat the freshwater crisis in nations suffering severe water stress.

Computational fluid dynamics simulations are performed to investigate the combustion and emission characteristics of a diesel/natural gas dual-fuel engine. The computational fluid dynamics model is validated against experimental measurements of cylinder pressure, heat release rate, and exhaust emissions from a single-cylinder research engine. The model predictions of in-cylinder diesel spray distribution and location of diesel ignition sites are related to the behavior observed in measured and predicted heat release rate and emissions. Various distributions of diesel fuel inside the combustion chamber are obtained by modifying the diesel injection timing and the spray included angle. Model predictions suggest that the distribution of diesel fuel in the combustion chamber has a significant impact on the characteristics of heat release rate, explaining experimental observations. Regimes of combustion in the dual-fuel engine are identified. Turbulent flame speed calculations, premixed turbulent combustion regime diagram analysis, and high-temperature front propagation speed estimation indicated that the dual-fuel combustion in this engine was supported by successive local auto-ignition and not by turbulent flame propagation. [ABSTRACT FROM AUTHOR]