Numerical Simulation Investigation on Natural Gas Leakage under Different Kitchen Layouts in China.

The safety of an open kitchen is a controversial topic in China. In this study, natural gas leakage and ventilation processes under an open kitchen layout and closed kitchen layout are simulated by CFD. The evolution of a hazardous gas cloud and the triggering behaviors of alarms are analyzed and discussed. For closing all windows in the leakage process, the state of the partition door is a major factor. A closed kitchen layout with a closing partition door performs best in confining a hazardous gas cloud. At this point, it is difficult for a hazardous gas cloud to appear in the living area. With the partition door open, the gas cloud develops rapidly. For opening windows in the leakage process, a large scale hazardous gas cloud is not able to form under all layouts. For alarm-triggering behaviors, a closed kitchen layout when closing the partition door also performs best. When opening the partition door, alarms cannot trigger stably under all layouts. For the ventilation process, hazardous gas cloud dissipation under an open kitchen layout is slightly faster than the closed kitchen layout. Under a weak convection effect, there is a transition stage which delays the time point for exhausting leaked gas. Based on the analysis, some recommendations for accident prevention are proposed. Residents should try to use closed kitchens and close partition doors when not cooking. If open kitchens are used, multiple alarms with lower trigger values should be installed. It is better to choose a ceiling type for gas alarms. The windows of the house are recommended to select two layers type. Higher layers can open during the ventilation process to accelerate the exhaust of leaked gas. These recommendations provide a reference for preventing fires and explosions.

Numerical Simulation Analysis of the Hydrogen-Blended Natural Gas Leakage and Ventilation Processes in a Domestic House.

The blending of hydrogen in natural gas may have effects on the safety of its usage in a domestic house. In this work, the leakage accident of hydrogen-blended natural gas (HBNG) in the kitchen of a domestic house is analyzed by CFD with a hydrogen blending ratio (HBR) ≤ 30%. The whole process is divided into the gas accumulation process and the ventilation process. In the initial leakage stage, the influence of heights and the HBR on the gas distribution is analyzed. HBNG concentration increases with increasing height. Based on the exit Froude number, the formation of a gas cloud in the kitchen is significantly influenced by the initial momentum and buoyancy, while it is more driven by the concentration gradient beyond the kitchen. In contrast to height, the variation of HBR on the HBNG distribution is not significant. In the ventilation process, the evolution of the hazardous gas cloud volume is analyzed. With windows and doors closed, the hazardous gas cloud fills the house in approximately 3600 s after the leakage occurs. When windows and doors are open for ventilation, the volume of the hazardous gas cloud first declines rapidly and then slowly. The reasons for the variation rate of hazardous gas cloud volume are analyzed according to ventilation conditions. The difference during the decline stage for different HBRs is analyzed according to the gas layering properties. Under a lack of convection condition, the ventilation process finally reaches a stagnant stage. In addition, another ventilation process has been investigated after extending the gas accumulation time. After extending the gas accumulation time, the effect of different HBRs on the ventilation process remains the same as before. However, it postpones the time point to enter the stagnation stage. As gas accumulation time extends from 3600 to 5400 and 7200 s, the ventilation time into the stagnation stage increases from about 4800 to 5400 and 6000 s, respectively. This study has implications for the establishment of a risk assessment system based on hazardous gas cloud volume.

Abdominal virtual non-contrast images derived from energy spectrum CT to evaluate chemotherapy-related fatty liver disease.

Background: Chemotherapy-related fatty liver disease (CRFLD) is an important evaluation in patients undergoing computed tomography (CT) for cancer follow-up. This study set out to explore the feasibility of using abdominal virtual non-contrast (VNC) images derived from energy spectrum CT to evaluate CRFLD and reduce the radiation dose. Methods: A total of 160 eligible consecutive patients who underwent energy spectrum CT at Lanzhou University Second Hospital between June 2020 and July 2021 were retrospectively enrolled. The average CT attenuation values of the liver and spleen and the liver-to-spleen ratio (LSR) were measured by two independent blinded radiologists on true non-contrast (TNC) images and three types of VNC image. The diagnostic performance of the LSR for CRFLD, image quality, and diagnostic confidence were compared between the two types of imaging. Results: The average CT attenuation values of the liver and spleen were significantly lower on VNC images than on TNC images (P<0.05), whereas the LSR showed good agreement between the two (P>0.05). The average CT attenuation values of the liver and the LSR measured on the TNC and three types of VNC image were significantly lower in patients with CRFLD than in those without CRFLD (P<0.001). The area under the curve (AUC) values of the LSR for the diagnosis of CRFLD calculated on TNC and three types of VNC image were 0.870 (95% CI: 0.808-0.918), 0.852 (95% CI: 0.787-0.903), 0.819 (95% CI: 0.750-0.875), and 0.851 (95% CI: 0.786-0.902), respectively. The DeLong test confirmed the consistency of TNC and VNC images of diagnostic efficacy (P>0.05). There were no significant differences in image quality or diagnostic confidence between the TNC and three types of VNC image (P>0.05). When VNC imaging was applied, the radiation dose was reduced by approximately 25.0%. Conclusions: VNC imaging could become a reliable alternative to TNC imaging for the clinical evaluation of patients with CRFLD and could reduce the radiation dose by up to 25%.

Pericoronary adipose tissue differences among plaque types: a retrospective assessment.

PURPOSE: To assess differences in pericoronary adipose tissue (PCAT) in patients with different plaque types by using several quantitative parameters of PCAT and investigate the relationship between PCAT and different plaque types. MATERIALS AND METHODS: We retrospectively recruited 488 patients diagnosed with stable coronary artery disease (CAD) via coronary computed tomographic angiography, including 279 with calcified plaques (CP), 153 with non-calcified plaques (NCP), and 56 with mixed plaques (MP). Volume, fat attenuation index (FAI), and 10th percentile, 90th percentile, median, and minimum Hounsfield unit (HU) values of PCAT surrounding plaques were quantified. Clinical features and quantitative PCAT parameters were compared between different plaque types. RESULTS: No intergroup differences were observed for age, sex, body mass index, risk factors, and plaque location. Length and PCAT volume in the NCP group were lower than those of the CP and MP groups (P < 0.001), whereas there were no significant differences between the CP and MP groups (P > 0.05). Patients with NCP and MP had a higher FAI and 10th percentile, 90th percentile, median, and minimum HU values of PCAT than CP (P < 0.001); however these values were not significantly different between the NCP and MP groups (P > 0.05). CONCLUSION: The quantitative parameters of PCAT, as a biosensor for CAD, vary among the different plaque types.

Microvascular Dysfunction Associates With Outcomes in Hypertrophic Cardiomyopathy: Insights From the Intravoxel Incoherent Motion MRI.

BACKGROUND: Although intravoxel incoherent motion (IVIM) MRI has emerged as an in vivo marker of tissue diffusion and perfusion, its prognostic value in patients with hypertrophic cardiomyopathy (HCM) remains unclear. PURPOSE: To investigate whether IVIM-MRI derived parameters are associated with outcomes in patients with HCM. STUDY TYPE: Prospective cohort. SUBJECTS: A total of 112 patients (51.72 ± 17.13 years) with suspected or known HCM. FIELD STRENGTH/SEQUENCE: Single-shot echo planar IVIM imaging, balanced steady-state free precession, and phase-sensitive inversion-recovery late gadolinium enhancement (LGE) sequences at 3 T. ASSESSMENT: All patients were followed up of 29.3 ± 12.3 months for combined major adverse cardiac events (MACE) including cardiac death, aborted sudden death, heart transplantation, and rehospitalization for heart failure. The CVI42 imaging platform was used to assess morphological and functional MRI indices and to quantify LGE. The Body Diffusion Toolbox was used to derive pseudo diffusion (D*), water molecular diffusion (D) and perfusion fraction (f). STATISTICAL TESTS: Univariable and stepwise multivariable Cox model analyses were used to investigate the association between variables and composite endpoints. Kaplan-Meier curves were constructed to assess event-free survival, and the event rates were compared by the log-rank test. RESULTS: A total of 19 patients reached endpoints. Patients with MACE showed a significantly impaired D* value, lower f value, and more extensive LGE than those without MACE (all, P < 0.05), while there was no significant difference in D value (P = 0.285). In the Cox regression models, D* value (hazard ratio [HR] 0.93; 95% CI: 0.88-0.98) and f value (HR 0.65; 95% CI: 0.45-0.92) were independent predictors for MACE. Moreover, in Kaplan-Meier survival analysis, the incidence of MACE was significantly higher in patients with decreased D* value and f value. CONCLUSIONS: Impaired D* and f values derived from IVIM-MRI are associated with adverse outcomes in patients with HCM. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 2.

[Comparative Evaluation of the Value of Quantitative Parameters of Dual-energy CT and MRI for KRAS Mutation in Rectal Cancer].

Objective To evaluate and compare the value of quantitative parameters of preoperative dual-energy CT and MRI on KRAS mutation in rectal cancer,and to explore the correlations between postoperative pathological indicators and KRAS mutation. Methods This study retrospectively analyzed 50 patients with rectal cancer confirmed by surgery and pathology and receiving KRAS genetic testing in Lanzhou University Second Hospital from August 2017 to April 2021.According to the results of genetic testing,the patients were assigned into a wild-type group (29 patients) and a mutant type group (21 patients).The preoperative baseline data included sex,age,and serum tumor markers,and the postoperative pathological data included pathological stage,lymphovascular invasion,perineural invasion,and lymph node metastasis.The quantitative parameters of three-phase energy spectral CT included iodine (water) concentration,water (iodine) concentration,effective atomic number,and normalized iodine concentration.The quantitative parameters of apparent diffusion coefficient (ADC) included minimum ADC,average ADC,and relative ADC.In addition,the width of the superior rectal vein was obtained from the CT images of the venous phase,and the tumor segmentation,the maximum axial length of tumor,and the maximum longitudinal length of tumor were obtained from the MRI images.The qualitative and quantitative data were compared by χ2 test,t-test,and Mann-Whitney U test.The diagnostic efficacy of the two detection methods for KRAS mutations in rectal cancer was compared,and the receiver operating characteristic curve was employed to evaluate the diagnostic efficacy. Results The KRAS mutation rate was higher in the carbohydrate antigen 199 abnormal group than the normal group (P=0.036) and higher in the positive group of lymphovascular invasion (P=0.034).The KRAS mutant type group had higher normalized iodine concentration in the venous phase (P=0.016) and lower average ADC and relative ADC (P=0.008, P=0.002,respectively) than the wild-type group.Among them,relative ADC had the highest diagnostic efficiency (AUC=0.755). Conclusion The quantitative parameters of dual-energy CT and ADC have similar diagnostic efficiency for KRAS mutation in rectal cancer,and relative ADC is superior to other parameters.

Differentiating atypical meningioma from anaplastic meningioma using diffusion weighted imaging.

PURPOSE: To explore the value of MRI conventional features and apparent diffusion coefficient (ADC) on the differential diagnosis of atypical meningioma (AtM) and anaplastic meningioma (AnM). MATERIALS AND METHODS: This retrospective study analyzed the preoperative clinical data, MRI conventional features, and DWI data of 55 AtM and 25 AnM confirmed by pathology in our hospital. The clinical features, MRI conventional features, ADCmean, ADCmin, and relative ADC (rADC) values were compared between the two tumors by Chi-square test or an independent sample t-test. Receiver operating characteristic curve (ROC) and binary logistic regression analysis were used to evaluate the diagnostic efficacy of each parameter to differentiate between these tumors. RESULTS: The MRI conventional features had a certain ability to distinguish AnM and AtM, with an area under the curve value (AUC) of 0.824 (95% CI, 0.723-0.900). The ADCmean, ADCmin, and rADC values were significantly higher in AtM compared to AnM (all P < 0.05). ADCmean had the best identification effect with an AUC of 0.867 (95% CI, 0.772-0.933) among them, at an cut-off of 0.817 × 10-3 mm2/s, the sensitivity and specificity of distinguishing AtM from AnM were 78.18% and 88.00%, respectively. A combination of ADCmean and MRI conventional features showed the optimum discrimination ability for the two tumors, the AUC, sensitivity, specificity, and accuracy were 0.918 (95% CI, 0.835-0.967), 80.00%, 94.55%, and 90.00%, respectively. CONCLUSION: MRI conventional features combined with ADCmean, as a non-invasive method, has potential clinical value in the preoperative diagnosis of AtM and AnM.

Comparison of Spectral and Perfusion Computed Tomography Imaging in the Differential Diagnosis of Peripheral Lung Cancer and Focal Organizing Pneumonia.

OBJECTIVE: To investigate the spectral and perfusion computed tomography (CT) findings of peripheral lung cancer (PLC) and focal organizing pneumonia (FOP) and to compare the accuracy of spectral and perfusion CT imaging in distinguishing PLC from FOP. MATERIALS AND METHODS: Patients who were suspected of having lung tumor and underwent "one-stop" chest spectral and perfusion CT, with their diagnosis confirmed pathologically, were prospectively enrolled from September 2020 to March 2021. Patients who were suspected of having lung tumor and underwent "one-stop" chest spectral and perfusion CT, with their diagnosis confirmed pathologically, were prospectively enrolled from September 2020 to March 2021. A total of 57 and 35 patients with PLC and FOP were included, respectively. Spectral parameters (CT40keV, CT70keV, CT100keV, iodine concentration [IC], water concentration [WC], and effective atomic number [Zeff]) of the lesions in the arterial and venous phases were measured in both groups. The slope of the spectral curve (K70keV) was calculated. The perfusion parameters, including blood volume (BV), blood flow (BF), mean transit time (MTT), and permeability surface (PS), were measured simultaneously in both groups. The differences in the spectral and perfusion parameters between the groups were examined. Receiver operating characteristic (ROC) curves were generated to calculate and compare the area under the curve (AUC), sensitivity, specificity, and accuracy of both sets of parameters in both groups. RESULTS: The patients' demographic and clinical characteristics were similar in both groups (P > 0.05). In the arterial and venous phases, the values of spectral parameters (CT40keV, CT70keV, spectral curve K70keV, IC, and Zeff) were greater in the FOP group than in the PLC group (P < 0.05). In contrast, the values of the perfusion parameters (BV, BF, MTT, and PS) were smaller in the FOP group than in the PLC group (P < 0.05). The AUC of the combination of the spectral parameters was larger than that of the perfusion parameters. For the former imaging method, the AUC, sensitivity, and specificity were 0.89 (95% confidence interval [CI]: 0.82-0.96), 0.86, and 0.83, respectively. For the latter imaging method, the AUC, sensitivity, and specificity were 0.80 (95% CI: 0.70-0.90), 0.71, and 0.83, respectively. There was no significant difference in AUC between the two imaging methods (P > 0.05). CONCLUSION: Spectral and perfusion CT both has the capability to differentiate PLC and FOP. However, compared to perfusion CT imaging, spectral CT imaging has higher diagnostic efficiency in distinguishing them.

The Benefit of Apparent Diffusion Coefficient in Evaluating the Invasiveness of Hepatocellular Carcinoma.

BACKGROUND: This study aimed to evaluate hepatocellular carcinoma (HCC) invasiveness using the apparent diffusion coefficient (ADC). METHODS: Eighty-one patients with HCC confirmed by pathology and examined by preoperative magnetic resonance imaging diffusion-weighted imaging from January 2015 to September 2020 were retrospectively analyzed. Clinical and pathological data were recorded. The minimum ADC (ADCmin), average ADC (ADCmean), and the ratio of ADCmean to normal-appearing hepatic parenchyma ADC (ADCnahp) were assessed. The associations between clinical information, ADC value, and HCC invasiveness (microvascular invasion [MVI], tumor differentiation, and Ki-67 expression) were evaluated statistically. Independent risk factors related to HCC invasiveness were screened using binary logistic regression, and the diagnostic efficiency was evaluated by the receiver operating characteristic curve and its area under the curve (AUC) value. RESULTS: Tumor size was related to HCC MVI and tumor differentiation (P < 0.05). HCC MVI was associated with ADCmin, ADCmean, and the ADCmean-to-ADCnahp ratio (all P < 0.05) with AUC values of 0.860, 0.860, and 0.909, respectively. If these were combined with tumor size, the AUC value increased to 0.912. The degree of tumor differentiation was associated with ADCmin, ADCmean, and the ADCmean-to-ADCnahp ratio (all P < 0.05) with AUC values of 0.719, 0.708, and 0.797, respectively. If these were combined with tumor size, the AUC value increased to 0.868. Ki-67 expression was associated with ADCmin, ADCmean, and the ADCmean-to-ADCnahp ratio (all P < 0.05) with AUC values of 0.731, 0.747, and 0.746, respectively. Combined them, the AUC value increased to 0.763. CONCLUSIONS: The findings indicated that the ADC value has significant potential for the non-invasive preoperative evaluation of HCC invasiveness.

Effects of a Portable Peritoneal Lavage Device on Dogs with Seawater-Immersed Open Abdominal Injury.

BACKGROUND: Seawater-immersed open abdominal injury is a special injury during marine activities. Effective warmed peritoneal lavage in the field early after injury is the key to treatment. This pilot study aimed at exploring the treatment effects of a self-developed portable peritoneal lavage device compared with conventional treatment model. MATERIAL AND METHODS: Beagle dogs were used to develop models of seawater-immersed open abdominal injury. A conventional lavage method or a novel peritoneal lavage device was used for lavage and rewarming. The vital signs, electrolyte, serum inflammatory cytokine expression levels, histological changes of mucosa, and microstructure variety of different groups were observed and compared before and after immersion and 2 h, 1 d, 3 d, and 5 d after lavage. RESULTS: The levels of TNF-α, IL-1ß, IL-8, IFN-γ, VEGF, and TGF-ß in the blood and the damage of tissues and cells in three groups were increased after immersion and decreased at the later points of time after lavage. The concentration of Na+, K+, Cl-, lactate, and lactate dehydrogenase in the plasma was significantly higher than that before immersion (P < 0.05), and the concentration of Ca2+ and HCO3 - and plasma pH decreased slightly (P < 0.05). The degree of tissue inflammation and mucosal injury in the delayed control group and device group was lower than the control group. CONCLUSIONS: Timely lavage and rewarming using a portable peritoneal lavage device reduced the inflammatory response of seawater-immersed open abdominal injury dogs and reduced the damage of multiple organs. The dogs recovered better and faster than the conventional treatment group.

Fabrication of Low-Cost and Ecofriendly Porous Biocarbon Using Konjaku Flour as the Raw Material for High-Performance Supercapacitor Application.

Low-cost and ecofriendly porous biocarbons were fabricated from konjaku flour via precarbonization and potassium hydroxide (KOH) activation. The obtained biocarbon ACK-5 derived from a precarbonized carbon/potassium hydroxide (KOH) mass ratio of 1:5 possessed an ultrahigh specific surface area of 1403 m2 g-1 and hierarchical porous structures with the existence of micro- to macropores. When ACK-5 was employed as a supercapacitor electrode in 6 M KOH, it showed a high specific capacitance of 216 F g-1 and excellent cycling stability with capacitance retention remaining 93.7% after 5000 cycles. Moreover, the ACK-5 sample acquired a supramaximal specific capacitance of 609 F g-1, and the high energy density of ACK-5//ACK-5 symmetrical cells reached up to 9.2 Wh kg-1 when p-phenylenediamine serving as a redox electrolyte was added into KOH electrolyte. The reported simple fabrication strategy would leverage a green biomass precursor for the preparation of supercapacitors.