Background The dead space fraction(VD/VT)has proven to be a powerful predictor of higher mortality in acute respiratory distress syndrome(ARDS).However,its measurement relies on expired carbon dioxide,limiting its wid...Background The dead space fraction(VD/VT)has proven to be a powerful predictor of higher mortality in acute respiratory distress syndrome(ARDS).However,its measurement relies on expired carbon dioxide,limiting its widespread application in clinical practice.Several estimates employing routine variables have been found to be reliable substitutes for direct measurement of VD/VT.In this study,we evaluated the prognostic value of these dead space estimates obtained in the first 7 days following the initiation of ventilation.Methods This retrospective observational study was conducted using data from the Chinese database in intensive care(CDIC).Eligible participants were adult ARDS patients receiving invasive mechanical ventilation while in the intensive care unit between 1st January 2014 and 31st March 2021.We collected data during the first 7 days of ventilation to calculate various dead space estimates,including ventilatory ratio(VR),corrected minute ventilation(V_(Ecorr)),VD/VT(Harris–Benedict),VD/VT(Siddiki estimate),and VD/VT(Penn State estimate)longitudinally.A time-dependent Cox model was used to handle these time-varying estimates.Results A total of 392 patients(median age 66[interquartile range:55–77]years,median SOFA score 9[interquartile range:7–12])were finally included in our analysis,among whom 132(33.7%)patients died within 28 days of admission.VR(hazard ratio[HR]=1.04 per 0.1 increase,95%confidence interval[CI]:1.01 to 1.06;P=0.013),V_(Ecorr)(HR=1.08 per 1 increase,95%CI:1.04 to 1.12;P<0.001),VD/VT(Harris–Benedict)(HR=1.25 per 0.1 increase,95%CI:1.06 to 1.47;P=0.006),and VD/VT(Penn State estimate)(HR=1.22 per 0.1 increase,95%CI:1.04 to 1.44;P=0.017)remained significant after adjustment,while VD/VT(Siddiki estimate)(HR=1.10 per 0.1 increase,95%CI:1.00 to 1.20;P=0.058)did not.Given a large number of negative values,VD/VT(Siddiki estimate)and VD/VT(Penn State estimate)were not recommended as reliable substitutes.Long-term exposure to VR>1.3,V_(Ecorr)>7.53,and VD/VT(Harris–Benedict)>0.59 was independently associated with an increased risk of mortality in ARDS patients.These findings were validated in the fluid and catheter treatment trial(FACTT)database.Conclusions In cases where VD/VT cannot be measured directly,early time-varying estimates of VD/VT such as VR,,V_(Ecorr),and VD/VT(Harris–Benedict)can be considered for predicting mortality in ARDS patients,offering a rapid bedside application.展开更多
A facile, rapid and sensitive spectrophotometric method was developed for the determination of carbaryl in its formulations, water and grain （rice and wheat） samples with newly synthesised reagent. The proposed meth...A facile, rapid and sensitive spectrophotometric method was developed for the determination of carbaryl in its formulations, water and grain （rice and wheat） samples with newly synthesised reagent. The proposed method was based on the alkaline hydrolysis of carbaryl pesticide and thus resulted 1-naphthol was coupled with diazotised 4,4＇-methylene-bis-m-nitroaniline in basic medium （pH 9） to give red colored product having λmax 480 nm for diazonium method （DM） or 1-naphthol reacts with 4,4＇-methylene-bis-m-nitroaniline in the presence of oxidising agent potassium dichromate （K2Cr2O7） to give red colored product having λmax 510 nm for oxidation method （OM）. The formation of colored derivatives with the coupling agent is instantaneous and stable for 48 h （DM） and 32 h （OM） respectively. Beer＇s law was obeyed in the concentration range of 0.2--10.0 μg·mL ^-1 for DM and 0.2--0.150 μg·mL^-1 for OM. The proposed methods are sensitive, easy to operate and permitted for the determination of carbaryl with detection limits of 0.028 μg·mL^-1 for DM and 0.024 μg·mL^-1 for OM respectively. The experimental results indicate that the procedure can eliminate the fundamental interferences caused by other pesticides and non-target ions, which made the methods more sensitive and selective. The method was applicable to the determination of carbaryl residue in water and food grain samples up to μg level.展开更多
For a climate-neutral future mobility,the socalled e-fuels can play an essential part.Especially,oxygenated e-fuels containing oxygen in their chemical formula have the additional potential to burn with significantly ...For a climate-neutral future mobility,the socalled e-fuels can play an essential part.Especially,oxygenated e-fuels containing oxygen in their chemical formula have the additional potential to burn with significantly lower soot levels.In particular,polyoxymethylene dimethyl ethers or oxymethylene ethers(PODEs or OMEs)do not contain carbon-carbon bonds,prohibiting the production of soot precursors like acetylene(C_(2)H_(2)).These properties make OMEs a highly interesting candidate for future climate-neutral compression-ignition engines.However,to fully leverage their potential,the auto-ignition process,flame propagation,and mixing regimes of the combustion need to be understood.To achieve this,efficient oxidation mechanisms suitable for computational fluid dynamics(CFD)calculations must be developed and validated.The present work aims to highlight the improvements made by developing an adapted oxidation mechanism for OME1-6 and introducing it into a validated spray combustion CFD model for OMEs.The simulations were conducted for single-and multi-injection patterns,changing ambient temperatures,and oxygen contents.The results were validated against high-pressure and high-temperature constantpressure chamber experiments.OH*-chemiluminescence measurements accomplished the characterization of the auto-ignition process.Both experiments and simulations were conducted for two different injectors.Significant improvements concerning the prediction of the ignition delay time were accomplished while also retaining an excellent agreement for the flame lift-off length.The spatial zones of high-temperature reaction activity were also affected by the adaption of the reaction kinetics.They showed a greater tendency to form OH^(*) radicals within the center of the spray in accordance with the experiments.展开更多
We aim to find one highly nontrivial example of the solutions to the vortex fluid dynamical equation on the unit sphere(S^(2))and compare it with the numerical simulation.Since the rigid rotating steady solution for v...We aim to find one highly nontrivial example of the solutions to the vortex fluid dynamical equation on the unit sphere(S^(2))and compare it with the numerical simulation.Since the rigid rotating steady solution for vortex fluids on S^(2)is already known to us,we consider the perturbations above it.After decomposing the perturbation of the vortex number density and vortex charge density into spherical harmonics,we find that the perturbations are propagating waves.To be precise,the velocities for different single-mode vortex number density waves are all the same,while the velocities for single-mode vortex charge density waves depend on the degree of the spherical harmonics l,which is a signal of the existence of dispersion.Meanwhile,we find that there is a beat phenomenon for the positive(or negative)vortex density wave.Numerical simulation based on the canonical equations for the point vortex model agrees perfectly with our theoretical calculations.展开更多
Marine organic-rich marl is not only a high-quality hydrocarbon source of conventional oil and gas,but also a new type and field of unconventional oil and gas exploration.An understanding of its pore structure evoluti...Marine organic-rich marl is not only a high-quality hydrocarbon source of conventional oil and gas,but also a new type and field of unconventional oil and gas exploration.An understanding of its pore structure evolution characteristics during a hydrocarbon generation process is theoretically significant and has application prospects for the exploration and development of this special type of natural gas reservoirs.This study conducted thermal simulation of hydrocarbon generation under near-geological conditions during a whole process for cylinder samples of low mature marine organic-rich marl in the Middle Devonian of Luquan,Yunnan Province,China.During this process,hydrocarbon products at different evolution stages were quantified and corresponding geochemical properties were analyzed.Simultaneously,field emission scanning electron microscopy(FE-SEM)and low-pressure gas adsorption(CO_(2),N_(2))tests were applied to the corresponding cylinder residue samples to reveal the mechanisms of different types of pore formation and evolution,and clarify the dynamic evolution processes of their pore systems.The results show that with an increase in temperature and pressure,the total oil yield peaks at an equivalent vitrinite reflectance(VR_(o))of 1.03%and is at the maximum retention stage of liquid hydrocarbons,which are 367.51 mg/g TOC and 211.67 mg/g TOC,respectively.The hydrocarbon gas yield increases continuously with an increase in maturity.The high retained oil rate at the peak of oil generation provides an abundant material basis for gas formation at high maturity and over-maturity stage.The lower limit of VR_(o)for organic matter(OM)pore mass development is about 1.6%,and bitumen pores,organic-clay complex pores together with intergranular pores,grain edge seams and dissolution pores constitute a complicated pore-seam-network system,which is the main reservoir space for unconventional carbonate gas.Pore formation and evolution are controlled synergistically by hydrocarbon generation,diagenesis and organic-inorganic interactions,and the pattern of pore structure evolution can be divided into four stages.A pore volume(PV)and a specific surface area(SSA)are at their highest values within the maturity range of 1.9%to 2.5%,which is conducive to exploring unconventional natural gas.展开更多
Radiochemotherapy-induced oral mucositis(OM)is a common oral complication in patients with tumors following head and neck radiotherapy or chemotherapy.Erosion and ulcers are the main features of OM that seriously affe...Radiochemotherapy-induced oral mucositis(OM)is a common oral complication in patients with tumors following head and neck radiotherapy or chemotherapy.Erosion and ulcers are the main features of OM that seriously affect the quality of life of patients and even the progress of tumor treatment.To date,differences in clinical prevention and treatment plans for OM have been noted among doctors of various specialties,which has increased the uncertainty of treatment effects.On the basis of current research evidence,this expert consensus outlines risk factors,clinical manifestations,clinical grading,ancillary examinations,diagnostic basis,prevention and treatment strategies and efficacy indicators for OM.In addition to strategies such as basic oral care,antiinflammatory and analgesic agents,anti-infective agents,pro-healing agents,and photobiotherapy recommended in previous guidelines,we also emphasize the role of traditional Chinese medicine in OM prevention and treatment.This expert consensus aims to provide references and guidance for dental physicians and oncologists in formulating strategies for OM prevention,diagnosis,and treatment,standardizing clinical practice,reducing OM occurrence,promoting healing,and improving the quality of life of patients.展开更多
基金supported by the Key Technologies Research and Development Program(Grant numbers:2022YFC2504400 and 2021YFC2500804)the Jiangsu Provincial Key Research and Development Program(Grant number:BE2022854).
文摘Background The dead space fraction(VD/VT)has proven to be a powerful predictor of higher mortality in acute respiratory distress syndrome(ARDS).However,its measurement relies on expired carbon dioxide,limiting its widespread application in clinical practice.Several estimates employing routine variables have been found to be reliable substitutes for direct measurement of VD/VT.In this study,we evaluated the prognostic value of these dead space estimates obtained in the first 7 days following the initiation of ventilation.Methods This retrospective observational study was conducted using data from the Chinese database in intensive care(CDIC).Eligible participants were adult ARDS patients receiving invasive mechanical ventilation while in the intensive care unit between 1st January 2014 and 31st March 2021.We collected data during the first 7 days of ventilation to calculate various dead space estimates,including ventilatory ratio(VR),corrected minute ventilation(V_(Ecorr)),VD/VT(Harris–Benedict),VD/VT(Siddiki estimate),and VD/VT(Penn State estimate)longitudinally.A time-dependent Cox model was used to handle these time-varying estimates.Results A total of 392 patients(median age 66[interquartile range:55–77]years,median SOFA score 9[interquartile range:7–12])were finally included in our analysis,among whom 132(33.7%)patients died within 28 days of admission.VR(hazard ratio[HR]=1.04 per 0.1 increase,95%confidence interval[CI]:1.01 to 1.06;P=0.013),V_(Ecorr)(HR=1.08 per 1 increase,95%CI:1.04 to 1.12;P<0.001),VD/VT(Harris–Benedict)(HR=1.25 per 0.1 increase,95%CI:1.06 to 1.47;P=0.006),and VD/VT(Penn State estimate)(HR=1.22 per 0.1 increase,95%CI:1.04 to 1.44;P=0.017)remained significant after adjustment,while VD/VT(Siddiki estimate)(HR=1.10 per 0.1 increase,95%CI:1.00 to 1.20;P=0.058)did not.Given a large number of negative values,VD/VT(Siddiki estimate)and VD/VT(Penn State estimate)were not recommended as reliable substitutes.Long-term exposure to VR>1.3,V_(Ecorr)>7.53,and VD/VT(Harris–Benedict)>0.59 was independently associated with an increased risk of mortality in ARDS patients.These findings were validated in the fluid and catheter treatment trial(FACTT)database.Conclusions In cases where VD/VT cannot be measured directly,early time-varying estimates of VD/VT such as VR,,V_(Ecorr),and VD/VT(Harris–Benedict)can be considered for predicting mortality in ARDS patients,offering a rapid bedside application.
文摘A facile, rapid and sensitive spectrophotometric method was developed for the determination of carbaryl in its formulations, water and grain （rice and wheat） samples with newly synthesised reagent. The proposed method was based on the alkaline hydrolysis of carbaryl pesticide and thus resulted 1-naphthol was coupled with diazotised 4,4＇-methylene-bis-m-nitroaniline in basic medium （pH 9） to give red colored product having λmax 480 nm for diazonium method （DM） or 1-naphthol reacts with 4,4＇-methylene-bis-m-nitroaniline in the presence of oxidising agent potassium dichromate （K2Cr2O7） to give red colored product having λmax 510 nm for oxidation method （OM）. The formation of colored derivatives with the coupling agent is instantaneous and stable for 48 h （DM） and 32 h （OM） respectively. Beer＇s law was obeyed in the concentration range of 0.2--10.0 μg·mL ^-1 for DM and 0.2--0.150 μg·mL^-1 for OM. The proposed methods are sensitive, easy to operate and permitted for the determination of carbaryl with detection limits of 0.028 μg·mL^-1 for DM and 0.024 μg·mL^-1 for OM respectively. The experimental results indicate that the procedure can eliminate the fundamental interferences caused by other pesticides and non-target ions, which made the methods more sensitive and selective. The method was applicable to the determination of carbaryl residue in water and food grain samples up to μg level.
文摘For a climate-neutral future mobility,the socalled e-fuels can play an essential part.Especially,oxygenated e-fuels containing oxygen in their chemical formula have the additional potential to burn with significantly lower soot levels.In particular,polyoxymethylene dimethyl ethers or oxymethylene ethers(PODEs or OMEs)do not contain carbon-carbon bonds,prohibiting the production of soot precursors like acetylene(C_(2)H_(2)).These properties make OMEs a highly interesting candidate for future climate-neutral compression-ignition engines.However,to fully leverage their potential,the auto-ignition process,flame propagation,and mixing regimes of the combustion need to be understood.To achieve this,efficient oxidation mechanisms suitable for computational fluid dynamics(CFD)calculations must be developed and validated.The present work aims to highlight the improvements made by developing an adapted oxidation mechanism for OME1-6 and introducing it into a validated spray combustion CFD model for OMEs.The simulations were conducted for single-and multi-injection patterns,changing ambient temperatures,and oxygen contents.The results were validated against high-pressure and high-temperature constantpressure chamber experiments.OH*-chemiluminescence measurements accomplished the characterization of the auto-ignition process.Both experiments and simulations were conducted for two different injectors.Significant improvements concerning the prediction of the ignition delay time were accomplished while also retaining an excellent agreement for the flame lift-off length.The spatial zones of high-temperature reaction activity were also affected by the adaption of the reaction kinetics.They showed a greater tendency to form OH^(*) radicals within the center of the spray in accordance with the experiments.
基金supported by the Scientific research projects of Hunan Provincial Department of Education(Grant Nos.22A0477 and 20B273)。
文摘We aim to find one highly nontrivial example of the solutions to the vortex fluid dynamical equation on the unit sphere(S^(2))and compare it with the numerical simulation.Since the rigid rotating steady solution for vortex fluids on S^(2)is already known to us,we consider the perturbations above it.After decomposing the perturbation of the vortex number density and vortex charge density into spherical harmonics,we find that the perturbations are propagating waves.To be precise,the velocities for different single-mode vortex number density waves are all the same,while the velocities for single-mode vortex charge density waves depend on the degree of the spherical harmonics l,which is a signal of the existence of dispersion.Meanwhile,we find that there is a beat phenomenon for the positive(or negative)vortex density wave.Numerical simulation based on the canonical equations for the point vortex model agrees perfectly with our theoretical calculations.
基金supported by the National Natural Science Foundation of China(Grant No.41930426)。
文摘Marine organic-rich marl is not only a high-quality hydrocarbon source of conventional oil and gas,but also a new type and field of unconventional oil and gas exploration.An understanding of its pore structure evolution characteristics during a hydrocarbon generation process is theoretically significant and has application prospects for the exploration and development of this special type of natural gas reservoirs.This study conducted thermal simulation of hydrocarbon generation under near-geological conditions during a whole process for cylinder samples of low mature marine organic-rich marl in the Middle Devonian of Luquan,Yunnan Province,China.During this process,hydrocarbon products at different evolution stages were quantified and corresponding geochemical properties were analyzed.Simultaneously,field emission scanning electron microscopy(FE-SEM)and low-pressure gas adsorption(CO_(2),N_(2))tests were applied to the corresponding cylinder residue samples to reveal the mechanisms of different types of pore formation and evolution,and clarify the dynamic evolution processes of their pore systems.The results show that with an increase in temperature and pressure,the total oil yield peaks at an equivalent vitrinite reflectance(VR_(o))of 1.03%and is at the maximum retention stage of liquid hydrocarbons,which are 367.51 mg/g TOC and 211.67 mg/g TOC,respectively.The hydrocarbon gas yield increases continuously with an increase in maturity.The high retained oil rate at the peak of oil generation provides an abundant material basis for gas formation at high maturity and over-maturity stage.The lower limit of VR_(o)for organic matter(OM)pore mass development is about 1.6%,and bitumen pores,organic-clay complex pores together with intergranular pores,grain edge seams and dissolution pores constitute a complicated pore-seam-network system,which is the main reservoir space for unconventional carbonate gas.Pore formation and evolution are controlled synergistically by hydrocarbon generation,diagenesis and organic-inorganic interactions,and the pattern of pore structure evolution can be divided into four stages.A pore volume(PV)and a specific surface area(SSA)are at their highest values within the maturity range of 1.9%to 2.5%,which is conducive to exploring unconventional natural gas.
基金supported by the National Natural Science Foundation of China(U23A20445)the Science and Technology Program of Guangzhou(202206080009)。
文摘Radiochemotherapy-induced oral mucositis(OM)is a common oral complication in patients with tumors following head and neck radiotherapy or chemotherapy.Erosion and ulcers are the main features of OM that seriously affect the quality of life of patients and even the progress of tumor treatment.To date,differences in clinical prevention and treatment plans for OM have been noted among doctors of various specialties,which has increased the uncertainty of treatment effects.On the basis of current research evidence,this expert consensus outlines risk factors,clinical manifestations,clinical grading,ancillary examinations,diagnostic basis,prevention and treatment strategies and efficacy indicators for OM.In addition to strategies such as basic oral care,antiinflammatory and analgesic agents,anti-infective agents,pro-healing agents,and photobiotherapy recommended in previous guidelines,we also emphasize the role of traditional Chinese medicine in OM prevention and treatment.This expert consensus aims to provide references and guidance for dental physicians and oncologists in formulating strategies for OM prevention,diagnosis,and treatment,standardizing clinical practice,reducing OM occurrence,promoting healing,and improving the quality of life of patients.
