Risk factors and clinical outcomes in patients undergoing cytoreductive surgery with concomitant ureteric reimplantation

Objectives There are currently scarce data exploring ureteric reimplantation (UR) during cytoreductive surgery (CRS). Methods We identified patients undergoing CRS for peritoneal surface malignancies (PSM) of any origin at a single high-volume unit. UR was defined as ureteroureterostomy, transureterouretostomy, ureteroneocystostomy, ureterosigmoidostomy or ileal conduit performed during CRS. Peri-operative outcomes, long-term survival and risk factors for requiring UR were analysed. Results Seven hundred and sixty-seven CRSs were identified. Twenty-three (3.0%) procedures involved UR. Bladder resection and colorectal cancer (CRC) were associated with increased risk of UR (bladder resection: OR 12.90, 95% CI 4.91–33.90, p<0.001; CRC: OR 2.51, 95% CI 1.05–6.01, p=0.038). UR did not increase the risk of Grade III–IV morbidity or mortality. The rate of ureteric leak was 3/23 (13.0%) in the UR group. Mean survival was equivocal in patients with CRC (58.14 vs. 34.25 months, p=0.441) but significantly lower in those with high-grade appendiceal mucinous neoplasm (HAMN) undergoing UR (73.98 vs. 30.90 months, p=0.029). Conclusions UR during CRS does not increase major morbidity or mortality for carefully selected patients, and is associated with low rates of urologic complications. Whilst decreased survival was apparent in patients with HAMN undergoing UR, it is unclear whether this relationship is causal.

The amount of heat input to the weld per unit length and per unit volume

This paper presents a comparative analysis of heat input per unit length and per unit volume for selected methods of welding. The purpose of the analysis is to assess the usability of calculating heat input per volume unit. The interpretation of heat input per unit length according to the standards: QW-409.1 of ASME IX, EN ISO 1011-1 is discussed. The concept of calculating heat input per unit volume is described. For exemplary padded welds and spot welded joints, the heat input values were calculated in accordance with the above-mentioned standards and based on the concept of heat input per unit volume. The study showed a lack of consistency between the individual standards in the interpretation of the heat input. In addition, the practical application of the heat input per unit volume method in calculating the actual amount of heat introduced into the weld was justified.

A Standardised Approach to the Biomechanical Evaluation of Tracheal Grafts

The ideal tracheal substitute must have biomechanical properties comparable to the native trachea, but currently there is no standardised approach to evaluating these properties. Here we propose a novel method for evaluating and comparing the properties of tracheal substitutes, thus systematising both measurement and data curation. This system was tested by comparing native rabbit tracheas to frozen and decellularised specimens and determining the histological characteristics of those specimens. We performed radial compression tests on the anteroposterior tracheal axis and longitudinal axial tensile tests with the specimens anastomosed to the jaw connected to a measuring system. All calculations and results were adjusted according to tracheal size, always using variables relative to the tracheal dimensions, thus permitting comparison of different sized organs. The biomechanical properties of the decellularised specimens were only slightly reduced compared to controls and significant in regard to the maximum stress withstood in the longitudinal axis (−0.246 MPa CI [−0.248, −0.145] MPa) and the energy stored per volume unit (−0.124 mJ·mm−3 CI [−0.195, −0.055] mJ·mm−3). The proposed method is suitable for the systematic characterisation of the biomechanical properties of different tracheal substitutes, regardless of the size or nature of the substitute, thus allowing for direct comparisons.

Distribution of Various Types of Educational Information in the School Physics Course

The modern physics course appeared as a result of a long-term evolution of the physics teaching methods. The model of the school course is textbooks; they reflect the fundamental laws of cognition of the surrounding world and methodological ideas, therefore the problem of studying the distribution of various types of training material in the physics course is relevant. The article uses previously obtained estimates of the differential complexity of various topics of the school physics course. This takes into account: 1) the differential complexity of the text, depending on the information amount in the volume unit, on which the difficulty of understanding it by the student depends; 2) the integral complexity (general informativeness), which characterizes the total amount of information in the text; the amount of time and effort required to study training material depends on it; 3) the share of educational information related to mechanics, molecular physics and thermodynamics, electrodynamics, optics and quantum physics. It also took into account the fact that physical and mathematical complexity are independent characteristics of the physics textbooks. The carried out content analysis of standard school textbooks made it possible to determine the integral complexity of each topic and build a graph with an accumulation that shows the dynamics of changes in the contribution of each physics section to the total information amount over time. In particular, it follows from the graph that: 1) the speed of transmission of educational information in the 10-11th grades is 5 times higher than in the 7-9th grades; 2) the amount of information on physics reported to a student by the end of the 11th grade is 4,4 times more than the amount of information reported in the 7th, 8th and 9th grades.

Structural Design of Vascular Stents: A Review

Percutaneous Coronary Intervention (PCI) is currently the most conventional and effective method for clinically treating cardiovascular diseases such as atherosclerosis. Stent implantation, as one of the ways of PCI in the treatment of coronary artery diseases, has become a hot spot in scientific research with more and more patients suffering from cardiovascular diseases. However, vascular stent implanted into vessels of patients often causes complications such as In-Stent Restenosis (ISR). The vascular stent is one of the sophisticated medical devices, a reasonable structure of stent can effectively reduce the complications. In this paper, we introduce the evolution, performance evaluation standards, delivery and deployment, and manufacturing methods of vascular stents. Based on a large number of literature pieces, this paper focuses on designing structures of vascular stents in terms of “bridge (or link)” type, representative volume unit (RVE)/representative unit cell (RUC), and patient-specific stent. Finally, this paper gives an outlook on the future development of designing vascular stents.

Title: Initial results of reoperative bariatric surgery: a retrospective feasibility and safety study at a low-volume unit

Background This study assessed the feasibility and results of revisional bariatric surgery at a low-volume unit.Methods This retrospective study was conducted from January 2017 to August 2020; the revision group comprised patients treated for weight regain (WR, n = 6), insufficient weight loss (IWL, n =3), and various complications (n=6). Clinical characteristics and 30-day outcomes were assessed and compared with those of primary bariatric procedures (control, n=173). Results A total of 8.0% (15/188) of patients underwent revisional procedures and tended to be elderly (40.1 vs. 38.2 years), be female (73.3% vs. 54.9%), and have a significantly lower body mass index (33.1 vs. 39.9 kg/m2) and fewer comorbidities than controls. Gastric bypass was the most prevalent revisional procedure. A significantly longer operative duration (155 and 96 min; p < 0.001), longer length of stay (3.7 and 2.4 days) and higher 30-day complication rate (20.0% vs. 4.6%) were found in the revision group, including one case of leakage and another of jejunojejunostomy obstruction. There were no cases of conversion to open surgery or mortality. A total of 5/6 WR patients achieved excessive weight loss >50%, versus only one IWL patient who reached this goal. Complications, including marginal ulcer, fistula and post-sleeve gastrectomy stenosis, were alleviated after revision.Conclusion Revisional surgery appears to be feasible and effective in a low-volume practice in patients with WR and complications after primary bariatric procedures; however, the benefits should be weighed against the risks. More robust evidence is required to support ongoing practice.

The Role of Iron Carbide in the Abyssal Formation of Hydrocarbons in the Upper Mantle

The existence of iron carbide in the upper mantle allows an assumption to be made about its possible involvement in the abyssal abiogenic synthesis of hydrocarbons as a carbon donor. Interacting with hydrogen donors of the mantle, iron carbide can form hydrocarbon fluid. In order to investigate the role of iron carbide in the abiogenic synthesis of hydrocarbons, the chemical reaction between cementite Fe3C and water was modeled under thermobaric conditions, corresponding to the upper mantle. A series of experiments were conducted using a high-pressure high-temperature Toroid-type large reactive volume unit with further analysis by means of gas chromatography. The results demonstrated the formation of hydrocarbon fluid in a wide range of thermobaric conditions (873–1223 K, 2.5–6.0 GPa) corresponding to the upper mantle. A strong correlation between the composition of the fluid and the pT conditions of the synthesis was illustrated in the investigation. The higher temperature of the synthesis resulted in the formation of a “poor” hydrocarbon mixture, primarily comprising methane, while a higher pressure yielded the opposite effect, converting iron carbide into a complex hydrocarbon system, containing normal and iso-alkanes up to C7 and benzene. This correlation explains the diversity of hydrocarbon systems produced experimentally, thus expanding the thermobaric range of the possible existence of complex hydrocarbon systems in the upper mantle. The results support the suggestion that the carbide—water reaction can be a source of both the carbon and hydrogen required for the abyssal abiogenic synthesis of hydrocarbons.