Operating Characteristics Research Articles

Use of a low-cost phase change material emulsion in de-centralized thermal energy storage for district heating network enlargement

A detailed heat transfer model of a storage tank was developed to assess the performance of a district heating system with de-centralized storage solutions. The performance of two cases, with water and a low-cost phase change material emulsion as storage medium was analysed for 40 residential buildings in Zaragoza (Spain). The chosen configuration is a typical cylindrical tank with internal coils through which the district heating water flows for the charge and discharge. This decentralized thermal energy storage unit reduced peak demand and mass flow in the network, allowing additional buildings to connect to a saturated grid. Four configurations were examined: (1) A 180 m3 water tank reduced district heating power demand by 36.6 %. (2) The same 180 m3 tank using the emulsion required fewer coils, lowering costs, stabilizing TES temperature, and increasing water supply temperature, thus extending system lifespan. (3) A 130 m³ tank with the emulsion offered operational characteristics similar to the water tank, with economic and structural benefits from reduced size. (4) An 180 m³ optimised tank with the emulsion achieved a 38.8 % reduction in district heating power demand. These configurations demonstrate the efficiency and cost-effectiveness of using phase change material emulsion in thermal energy storage systems.

Novel deuterium-tritium (DT) neutron activation diagnostics for increased neutron yield operations at Sandia's Z-facility (invited).

As inertial confinement fusion experiments at Sandia National Laboratories' Z-facility begin using deuterium-tritium (DT) fuels, the expected DT-neutron yields are expected to increase many orders of magnitude. This brings about the need for diagnostics that have a significantly higher dynamic range of operation and ability to obtain yields where there will be significant radiation holds. Using the current activation diagnostic infrastructure at the Z-facility, a pair of activation diagnostics are being developed. The first is fluorine activation, which will be used in a similar manner to current copper activation diagnostics that are fielded in a rabbit for quick removal from the experiments without opening the vacuum experiment containment. The second is a prompt DT-neutron detector that exploits the activation of oxygen with similar operation characteristics as the current Be-probes fielded at Z. We will discuss the design of this pair of instruments, along with calibration work performed at Sandia's Ion Beam Laboratory in support of the development and anticipated instrument performance.

Clinical applicability of signal heterogeneity and tumor border assessment on T2-weighted MR images to distinguish astrocytic from oligodendroglial origin of gliomas

Background and purposeRadiological features on magnetic resonance imaging (MRI) were attributed to oligodendroglioma, although the diagnostic accuracy in a real-world clinical setting remains partially elusive. This study investigated the accuracy and robustness of tumor heterogeneity and tumor border delineation on T2-weighted MRI to distinguish oligodendroglioma from astrocytoma. Materials and methodsEight readers from three different specialties (radiology, neurology, neurosurgery) with varying levels of experience blindly rated 79 T2-weighted MR images of patients with either oligodendroglioma or astrocytoma. After the first reading session, all readers were re-invited for a second reading session within three weeks. Diagnostic accuracy, including area under the receiver operator characteristics curve (AUC), and intra-observer variability and inter-observer variability were used as outcome measures. ResultsPooled sensitivity and specificity to distinguish oligodendroglioma from astrocytoma for the use of tumor heterogeneity were 59.9 % respectively 74.5 %, and 85.7 % respectively 40.1 % for tumor border. A second reading session did not result in a significant change in sensitivity or specificity for tumor heterogeneity (P = 0.752 and P = 0.733, respectively) or tumor border (P = 0.309 and P = 0.271, respectively). An AUC of 0.825 was achieved with regard to predicting oligodendroglial origin of gliomas. Intra-observer agreement ranged from moderate to very good for tumor heterogeneity (kappa-value 0.43–0.87) and tumor border (0.40–0.84). A moderate inter-oberserver agreement was achieved for tumor heterogeneity and tumor border (kappa-value of 0.50 and 0.45, respectively). ConclusionThis study demonstrates that tumor heterogeneity and tumor borders on T2-weighted MRI could be used with moderate Finter-observer agreement to non-invasively distinguish oligodendroglioma from astrocytoma.

The Relationship Between the Endoscopic Healing Index, Fecal Calprotectin, and Magnetic Resonance Enterography in Crohn's Disease.

The serum-based endoscopic healing index (EHI) test identifies endoscopic Crohn's disease (CD) activity. Data are lacking on the relationship between EHI with other endpoints. We assessed the relationship between EHI and the simplified Magnetic Resonance Index of Activity. Data were prospectively collected on patients with CD with either an EHI or fecal calprotectin (FCAL) within 90 days of magnetic resonance enterography (MRE). Diagnostic accuracy was assessed using area under the receiver operator characteristics. Proportions with any, severe, and terminal ileum MR inflammation were compared above/below identified thresholds for both EHI and FCAL. A total of 241 MREs paired to either EHI or FCAL from 155 patients were included. Both EHI and FCAL had similar accuracy to diagnose inflammation (area under the receiver operator characteristics: EHI: 0.635 to 0.651, FCAL: 0.680 to 0.708). Optimal EHI values were 42 and 26 for inflammation on MRE and endoscopy, respectively. Patients with EHI ≥42 (100% vs. 63%, P =0.002), FCAL >50µg/g (87% vs. 64%, P <0.001) and FCAL >250µg/g (90% vs. 75%, P =0.02) had higher rates of simplified Magnetic Resonance Index of Activity ≥1 compared with lower values. EHI differentiated ileitis numerically more than FCAL (delta: 24% to 25% vs. 11% to 21%). Patients with FCAL ≥50µg/g had higher rates of severe inflammation compared with FCAL <50µg/g (75% vs. 47%, P <0.001), whereas smaller differentiation existed for EHI threshold of 42 (63% vs. 49%, P =0.35). Both EHI and FCAL were specific in their confirmation of inflammation and disease activity on MRE in patients with CD. However, MRE-detected inflammation was frequently present in the presence of low EHI and FCAL in similar proportions.

Self-rectifying NiOX/WOX heterojunction synaptic memristor for crossbar architectured reservoir computing system

In this study, we examine an ITO/NiOX/WOX/Pt p-n heterojunction memristor for neuromorphic applications as a synaptic crossbar array. The transition in the depletion region at the interface between p-type NiOX and n-type WOX crucially influences the self-rectifying characteristics of the device depending on the voltage polarity. Furthermore, long- and short-term memory coexist depending on the switching voltage condition, thus enabling various neuromorphic applications, such as reservoir computing and the use of the synaptic device at the off-chip trained network. The reliable operational characteristics are confirmed by obtaining an average memory window (>9) and rectification ratio (>58) between device-to-device and cycle-to-cycle. Furthermore, synaptic functions were successfully implemented, such as spike-rate-dependent plasticity, spike-number-dependent plasticity, paired-pulse facilitation, post-tetanic potentiation, paired-pulse depression, and post-tetanic depression, in conjunction with repeatability. Ultimately, reservoir computing is accomplished based on the I–V nonlinearity and short-term memory characteristics. A high pattern recognition rate (>96.2%) is achieved in MNIST tasks using 16 reservoir states, thus affirming the trustworthiness of the reservoir computing system. With its comprehensive approach to synaptic applications for neuromorphic computing systems, the heterojunction device highlights its considerable potential to advance artificial neural networks in conjunction with novel memristor technology directions.

Landslide susceptibility assessment in Addi Arkay, Ethiopia using GIS, remote sensing, and AHP

Landslides account for the breakdown of natural topographies, impacting many mountainous areas and leading to loss of lives and damaged infrastructure. This research aims to generate a reliable landslide susceptibility zonation map employing geospatial and Analytical Hierarchy Processes (AHP) in Addi Arkay Woreda, North Gondar Zone, Amhara Regional State, northern Ethiopia. The present study uses remote sensing data, geographic information system (GIS) tools, AHP, and weighted linear combination (WLC) models to analyze multiple environmental variables, including slope, aspect, curvature, lithology, soil texture, topographic wetness index (TWI), and rainfall. As per the results, around 186.12 km2 (13.26%) of the total study area is under very high landslide susceptibility and 140.85 km2 (10.05%) under very low susceptibility. Using Google Earth images for inaccessible areas, 121 landslide inventories were identified through fieldwork. Of these inventories, 85 were used to train the model and 36 for testing. The performance of the AHP model was validated by the Receiver Operating Characteristics (ROC) curve (0.75), which indicates good predictive accuracy for identifying landslide-prone areas. These findings are essential to regional land use planning, hazard mitigation, and landslide prevention efforts. Additionally, this study contributes to the scientific understanding of landslide dynamics in the Northwestern highlands of Ethiopia and offers a methodological framework that can be applied to other regions with similar geological and climatic conditions.

Serum Levels of Arachidonic Acid, Interleukin-6, and C-Reactive Protein as Potential Indicators of Pulmonary Viral Infections: Comparative Analysis of Influenza A, Respiratory Syncytial Virus Infection, and COVID-19.

Acute respiratory tract infections, including influenza A (FluA), respiratory syncytial virus (RSV) infection, and COVID-19, can aggravate to levels requiring hospitalization, increasing morbidity and mortality. Identifying biomarkers for an accurate diagnosis and prognosis of these infections is a clinical need. We performed a cross-sectional study aimed to investigate the changes in circulating levels of arachidonic acid, interleukin 6 (IL-6), and C-reactive protein (CRP) in patients with FluA, RSV, or COVID-19, and to analyze the potential of these parameters as diagnosis or prognosis biomarkers. We analyzed serum samples from 172 FluA, 80 RSV, and 217 COVID-19 patients, and 104 healthy volunteers. Individuals with lung viral diseases showed reduced arachidonic acid concentrations compared to healthy people, with these differences being most pronounced in the order COVID-19 > RSV > FluA. Conversely, IL-6 and CRP levels were elevated across diseases, with IL-6 emerging as the most promising diagnostic biomarker, with areas under the curve (AUC) of the receiver operating characteristics plot higher than 0.85 and surpassing arachidonic acid and CRP. Moreover, IL-6 displayed notable efficacy in distinguishing between FluA patients who survived and those who did not (AUC = 0.80). These findings may provide useful tools for diagnosing and monitoring the severity of acute viral respiratory tract infections, ultimately improving patient outcomes.

Influences of ultra-low load operation strategies on performance of a 300 MW subcritical bituminous coal boiler

To reveal the operational characteristics of subcritical boilers under ultra-low loads, numerical simulations were conducted based on a 300 MW subcritical bituminous coal boiler. The impacts of boiler load and low-load operation strategies on coal combustion behavior, heat transfer process, and NOx emission were thoroughly examined. Results indicate that acceptable aerodynamic and temperature fields can still be formed at 25 % ultra-low load, but the boiler performance is significantly reduced, with the maximum cross-sectional average combustion temperature being reduced by 225.98 K compared with the full-load condition. At 25 % load, the use of only two layers of burners results in a substantial increase in NOx emission from 290.32 mg/m3 to 445.56 mg/m3. The position of in-service burners affects the region where the intense coal combustion and heat release process occurs, and using the middle three layers of burners helps to maintain heat absorption by the suspended heating surfaces and to minimize NOx emissions. Furthermore, increasing primary air velocity at ultra-low loads can promote coal combustion and heat transfer processes in the lower furnace, but increase NOx emission by 14.23 % when primary air velocity is increased from 14.90 m/s to 23.00 m/s at 25 % load. These findings provide valuable insights for optimizing the ultra-low load operation of subcritical boilers engaged in deep peak-shaving processes under the carbon neutrality goal.

Research on the operation characteristics of natural draft dry cooling tower group under crosswind conditions

Research on the operation characteristics of natural draft dry cooling tower group under crosswind conditions

Expression and Significance of PKM1 in Acute Myeloid Leukaemia.

To investigate the expression level of pyruvate kinase M1 (PKM1) in patients with acute myeloid leukaemia (AML) as well as its clinical significance. A case-control study. Place and Duration of the Study: Department of Haematology, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China, from January 2013 to 2023. The expression levels of PKM1 and pyruvate kinase m2 (PKM2) in the bone marrow of 65 AML patients (excluding M3) and 31 healthy volunteers were determined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), a method that measures fluorescence in real-time. The associations between PKM1, PKM2 expressions, clinical parameters, and the survival and prognosis of AML patients were analysed. AML patients showed higher PKM1 expression compared to controls. The area under the curve (AUC) of the receiver operating characteristics (ROC) was 0.65 (p = 0.017). PKM1 expression was correlated with peripheral blood leukocyte count (r = -0.276, p = 0.026), CCAAT enhancer-binding protein alpha CEBPA mutation (r = -0.306, p = 0.014), and chemotherapy-induced response (r = -0.292, p = 0.018). Patients with high PKM1 expression had a lower remission rate (p = 0.019) and long-term survival rate (p = 0.034) than those with low PKM1 expression. Patients with AML showed a rise in PKM2 levels; however, the variation was not statistically significant (p >0.05). PKM1 expression is upregulated in AML and patients with high PKM1 expression have a lower survival rate. PKM1, Acute myeloid leukaemia, Clinical prognosis.

Flood susceptibility assessment of Jhelum River Basin: A comparative study of TOPSIS, VIKOR and EDAS methods

Floods are frequent natural hazards that cause widespread destruction, particularly in low-elevated areas. This study focuses on identifying flood susceptible zones in the Kashmir Valley, known for historical flooding attributed to the overflow of the Jhelum River. Various Multi-Criteria Decision Making (MCDM) techniques, including Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), Vise Kriterijumska Optimizacijai Compromission Resenje (VIKOR), and Evaluation Based on Distance from Average Solution (EDAS), were employed in this research. A total of 17 multidimensional factors were considered, and multicollinearity tests revealed no correlation among these factors. The results of the MCDM models indicate that areas along the Jhelum River are classified under very high flood susceptible zone. Specifically, Srinagar city is consistently classified under very high flood susceptible zone by all three models. Approximately 4.27%, 9.67%, and 5.39% of the total area were identified as very high susceptible areas by TOPSIS, VIKOR, and EDAS, respectively. The models exhibited robust performance, as evidenced by the Area Under the Curve of the Receiver Operating Characteristics curve (AUC-ROC). Notably, VIKOR demonstrated excellent performance among the three models in generating flood susceptible maps. The favorable outcomes of these models underscore their potential application in similar regions facing comparable challenges. This study carries significant implications for policymakers, administrators, and local authorities involved in flood management within the Kashmir Valley. The insights provided can inform proactive measures and strategies to mitigate the impact of floods and enhance the overall resilience of the region.

Deltoid Tuberosity Index for Proximal Humerus Fracture: Reliability and A Predictor of Systemic Osteoporosis in an Asian Population

Our study investigates the reliability of deltoid tuberosity index (DTI) and DTI as a predictor of systemic osteoporosis. The proximal humerus is a common fragility fracture. Current literature suggests that poor local bone density is a significant predictor for surgical fixation failure. The DTI is a simple radiographical tool that is strongly correlates with local humeral BMD aiding surgical planning to consider adjuncts or arthroplasty. However, there is a lack of data in the reliability of assessment of DTI, as well as its correlation to systemic osteoporosis. Respective cohort of patients with PHF treated at a trauma center in Singapore from August 2017 to July 2018 were recruited. Four raters at different levels of varying clinical seniority measured DTI using shoulder radiographs. The dual energy X-ray Absorptiometry (DEXA) bone mineral density (BMD) scan of the hip and lumbar spine was used to diagnose osteoporosis. Area under receiver operating characteristics (AUROC) analysis was conducted to study the diagnostic utility of DTI to predict the risk of osteoporosis. Our study had 87 patients consisting 18 males and 69 females, mainly of Chinese ethnicity (84%) and mean age of 69.7 years (SD 9.52, range 39-92yrs). For assessment of DTI, there was good intra-rater reliability amongst four raters (correlation coefficient range 0.805- 0.843) and excellent inter-rater reliability between al raters (intraclass correlation coefficient = 0.898; 95% CI 0.784-0.950, p-value <0.001). Based on BMD, 55.2% (n=48) were osteoporotic using T-score <-2.5. The highest correlation of DTI to BMD was with femoral neck density at 0.580. The DTI cut-off of 1.6 had the highest combined sensitivity and false positive rate, with area under curve (AUC) = 0.682 (95% CI, 0.564-0.799) for the overall population and AUC =0.706 (95% CI, 0.569-0.842) for patients <75 years. The DTI is a simple and reliable tool, strengthening its applicability in clinical practice to enhance preoperative planning in the surgical fixation of PHF. DTI with a cut off of 1.6 may be helpful tool prompting clinicians to workup and manage underlying osteoporosis.

STUDY OF THE PROPERTIES OF MODIFIED BINDER OBTAINED ON THE BASIS OF BENEFICIATION WASTE OF THE MINING AND PROCESSING PLANT

The introduction of active mineral additives into cement makes it possible to obtain concrete with high physical, mechanical and operational characteristics, namely, they increase the density, water resistance, frost, sulfate, alkali resistance and salt resistance of concretes and mortars, while reducing the consumption of clinker cement. The scale of construction of facilities using cement concrete is growing every year, which raises the question of reducing the consumption of clinker cement, due to the high energy intensity of production using active mineral additives. The use of active mineral additives in the form of waste from enrichment has high economic and environmental significance. The article examines the ways of using waste tailings of polymetallic ore enrichment in cement as a complex modified binder with an active mineral additive. To select the optimal ratio of silica and Balkhash GOK enrichment waste, their pozzolan activity was determined, which is 3.8-4 times higher for silica than for BGOK waste. The pozzolan activity of Balkhash GOK enrichment waste 16 hours after mixing with lime solution is 24 mg/g, and microsilicon is 114 mg/g. The pozzolan activity of a complex mineral additive for cements consisting of 60% of Balkhash GOK enrichment waste and 40% of microsilicon is 48 mg/g. The introduction of 40% silica into the Balkhash GOK enrichment waste increases the pozzolan activity of the complex additive by 2 times. This made it possible to obtain a modified binder using a complex mineral additive of up to 20%.

CONSTRUCTION AND OPERATIONAL PROPERTIES OF CONCRETE ON MODIFIED BINDER

The most important tasks of science in the field of construction: facilitating reinforced concrete structures, accelerating and reducing the cost of technological processes, in particular, abandoning heat treatment of products, increasing the durability of concrete can only be solved by giving special properties to binders. The way to solve this problem lies through the expansion of the range of complex mineral additives. Natural and man-made substances in a dispersed state, insoluble in water and characterized by grain size less than 0.16 mm, are used as mineral additives for binders and concretes. Despite the different effectiveness, mineral additives have a similar qualitative chemical composition (oxides of silicon, aluminum and others). The differences are in their mineralogical composition, the ratio of components and the degree of dispersion, which determine the predominant mechanism of their action in cement systems. Depending on the properties of the mineral additive, it is possible to obtain multicomponent binders for concretes with special properties: fast-hardening, high-strength, sulfate-resistant and others with significant savings in the cement component. The effectiveness of superplasticizers in dispersed systems can be increased due to a different procedure for their introduction or by combining them with finely ground mineral fillers of various chemical nature. The article presents the possibility of obtaining heavy concretes with specified construction and operational characteristics using a complex mineral additive, which includes waste from the tailings of the Balkhash mining and Processing plant and silica, as well as superplasticizers of various natures: MasterGlenium 305, Master Rheobuild 1000K and Master Air 200.

A Systematic Literature Review: Performance Comparison of Edge Detection Operators in Medical Images

Medical images play a crucial role in the diagnosis of diseases. To make the diagnosis more accurate, the image should usually be enhanced first using image processing methods such as segmentation and edge detection stages. However, the complexity and noise that may arise in these images pose challenges in edge detection. Therefore, to portray the characteristics of edge detection operators, this research presents a systematic literature review of the performance of various edge detection operators in medical images, focusing on literature published between 2019 and 2023. After the selection process, 41 papers out of the initial 112 collected papers were chosen for further review. The study evaluates edge detection operators e.g., Canny, Sobel, Prewitt, Roberts, and Laplacian of Gaussian (LOG) on medical images such as X-rays, MRI, CT scans, ultrasound, Pap smears, and others. In the analysis, the accuracy, computational time, and response to noise of each operator are compared. The results indicate that despite longer computational times, Canny emerges as the most accurate operator, especially in Pap smear and CT scan images. The LOG operator offers high accuracy in MRI images with more efficient computational time. Evaluation of operator reliability against noise confirms the superiority of Canny. Furthermore, the future potential of edge detection in medical services is also reviewed. For instance, Canny, known for accurate and noise-resistant edges, enhances detection in complex CT-Scan and X-ray images. Meanwhile, LOG, handling artifacts with lower computational time, improves edge clarity in medical images. Potential applications include enhanced diagnosis, efficient patient monitoring, and improved image clarity in future medical services.

The different doses of sufentanil combined with nalmefene in bronchoscopy: a systematic review and meta-analysis.

Bronchoscopy examination is a common clinical diagnostic method. However, due to its unique operational characteristics, the procedure often induces discomfort and pain in patients. The combined use of sufentanil and nalmefene offers advantages in effectively reversing opioid-induced respiratory depression without compromising analgesic effects. However, a comprehensive analysis report on the combined use of different doses of sufentanil and nalmefene in bronchoscopy examinations has not been reported. The aim of this subject is to investigate the application effects of different doses of sufentanil combined with nalmefene in bronchoscopy. Using computer-based and manual methods to retrieve relevant keywords, we searched the databases of PubMed, Embase, Web of Science, Cochrane Library, China National Knowledge Infrastructure (CNKI), and Wanfang from inception to the present to find studies evaluating the application effects of different doses of sufentanil combined with nalmefene in bronchoscopy examinations. The quality of the included studies was assessed, and meta-analysis was conducted using RevMan 5.3 software. A total of six English-language articles, involving randomized controlled trials and reviews, and comprising 774 participants, were finally included. The control group used conventional therapy, whereas the intervention group used different doses of sufentanil combined with nalmefene. Meta-analysis results indicated that compared to conventional therapy, this approach significantly improved vital signs such as systolic blood pressure [SBP; mean difference (MD) =21.44, P<1×10-5] and diastolic blood pressure (DBP; MD =22.52, P<1×10-5), heart rate (HR; MD =25.16, P<1×10-5), and oxygen saturation (SpO2; MD =30.16, P<1×10-5). A total of 4 studies focused on sedative effects, and that of sufentanil combined with nalmefene was significantly superior to conventional therapy (P<1×10-5). Analysis of adverse events showed that the combined therapy had better outcomes in terms of hypertension and tachycardia incidence compared to the control group (P<0.001, P<1×10-5), and Riker sedation-agitation scale (SAS score) was significantly reduced (P<0.05). However, there were no significant differences in other adverse events (P>0.05). Subgroup analysis showed fewer adverse reactions at 0.4 µg/kg sufentanil concentration compared to 0.2 and 0.8 µg/kg, with only hypertension differing significantly. In clinical practice, considering the use of sufentanil combined with nalmefene can improve patients' experience during bronchoscopy examinations. However, it should be noted that this approach may not be suitable for all patients, and clinicians need to choose appropriate analgesic and sedative methods for bronchoscopy examinations based on patients' conditions and individual differences. Furthermore, it is important to recognize that this study has some limitations and further research is needed to evaluate the efficacy and safety of this approach in other types of endoscopic examinations, as well as to compare the effects and safety of different drug combinations.

The Prediction of Failure in the Gas Filtration System in Low-Pressure Carburising Furnaces

Predictive maintenance is one of the key aspects of Industry 4.0. The article presents the results of experimental tests of nitrogen purification filters in the installation of a low-pressure, metal processing device. The aim of the research was to develop a predictive algorithm for making decisions regarding the replacement of used filters, based on flow analysis and measurement of the pressure difference in front of and behind the tested filter. For the purposes of the research, a special test stand was constructed, which made it possible to determine the operating characteristics of three selected filters. Based on the tests carried out, the limit characteristics of the parameters measured were determined, identifying the need to replace filters in the gas installation.

Vaginal fluid creatinine in diagnosing pre-labor rupture of membranes in Vietnam

Pre-labor rupture of membranes (PROM) is a common issue in obstetrics that can lead to serious complications. Timely diagnosis is crucial for proper management of PROM. Creatinine concentration in vaginal fluid is a potential candidate for diagnosing PROM in resource constrained environment. This study aims to investigate the usability of creatinine concentration and its optimal cutoff value for diagnosing PROM. We conducted a case-control diagnostic test study at Hung Vuong Maternity Hospital, Vietnam. Pregnant women between 24–42 weeks were enrolled into case and control groups, with a ratio of 1:2. We used sterile speculum examination for fluid leak from cervix, nitrazine test and ferning test are used to determine membrane’s status. Vaginal fluid was collected by injecting sterile saline and later withdrawing. Data was summarized using descriptive statistics, difference between groups was tested using Mann Whitney U test. The cutoff value was determined by receiver operating characteristics (ROC) curve and Youden’s J statistic. Ethics approval was obtained from the local ethics committee, all participants gave written informed consent. We recruited a total of 693 pregnant women into the study – 231 participants in the study group and 462 participants in the control group. The median vaginal fluid creatinine concentration in the study group is significantly higher than those in the control group (0.84 mg/dL versus 0.09 mg/dL, p&lt;0.01). The optimal cutoff for diagnosing PROM was 0.29 mg/dL, providing 93% sensitivity, 97% specificity and 95% accuracy. Vaginal fluid creatinine concentration is a credible indicator for PROM, providing great diagnostic power and high-quality information.

New mathematical models for the load factor of slip pairs of the ship propulsion complex for non-Newtonian lubricants

The method of boundary variation was applied to the solution of the boundary value problem with respect to the Reynolds differential equation for the lubricating layer in the sliding bearings of ship power plants and auxiliary ship equipment, which made it possible to obtain analytical representations for the hydrodynamic pressure, shear stresses, as well as the integral characteristics of the lubricating layer. This made it possible to build new, easy-to-use mathematical models for the load factor (carrying force factor) of the sliding pairs of the ship propulsion complex, considering the non-Newtonian properties of lubricants, i.e. in the case of the dependence of dynamic viscosity on pressure and temperature. Mathematical models take into account geometric parameters of bearings, operational parameters: relative radial clearance and relative eccentricity, angular velocity; as well as viscosity characteristics of lubricants, in particular, dynamic viscosity and piezo coefficient of viscosity of lubricants. A criterion for the applicability of lubricants for given operating characteristics and bearing parameters has been developed, which uses the viscosity characteristics of lubricants. The research results are illustrated in the form of tables and graphs.

Usefulness of Preoperative Prognostic Nutritional Index in Secondary Spontaneous Pneumothorax

BackgroundThe prognostic nutritional index has been identified as a predictor of postoperative outcomes in various fields. We investigated the usefulness of the prognostic nutritional index as a risk factor for postoperative complications in secondary spontaneous pneumothorax. MethodsIn this retrospective study, patients who underwent surgery for secondary spontaneous pneumothorax were reviewed. The associations among the prognostic nutritional index, body mass index, and performance status were examined, and risk factors for postoperative complications were investigated in a multivariate analysis. In the subgroup analysis, on the basis of the receiver operating characteristics, we divided patients into high– and low–prognostic nutritional index groups and investigated the utility of the prognostic nutritional index for postoperative complications. ResultsOf 91 patients who underwent surgery for secondary spontaneous pneumothorax, 34 patients with postoperative complications were included. The prognostic nutritional index was significantly positively and negatively correlated with body mass index (P < .001) and performance status (P < .001), respectively. Multivariate analysis revealed that a decreased prognostic nutritional index was an independent risk factor for postoperative complications (P = .0048). In the subgroup analysis, the postoperative outcomes, including the duration of chest tube placement (P = .042), hospital stay (P = .0014), complications (P = .0089), and mortality (P = .044), were significantly worse in the low– than in the high–prognostic nutritional index group. ConclusionsThe prognostic nutritional index may be useful for evaluating the severity of secondary spontaneous pneumothorax in preoperative patients and may be a risk for postoperative complications.