Background: When applied to trabecular bone X-ray images, the anisotropic properties of trabeculae located at ultra-distal radius were investigated by using the trabecular bone scores (TBS) calculated along directions...Background: When applied to trabecular bone X-ray images, the anisotropic properties of trabeculae located at ultra-distal radius were investigated by using the trabecular bone scores (TBS) calculated along directions parallel and perpendicular to the forearm. Methodology: Data from more than two hundred subjects were studied retrospectively. A DXA (GE Lunar Prodigy) scan of the forearm was performed on each subject to measure the bone mineral density (BMD) value at the location of ultra-distal radius, and an X-ray digital image of the same forearm was taken on the same day. The values of trabecular bone score along the direction perpendicular to the forearm, TBS<sub>x</sub>, and along the direction parallel to the forearm, TBS<sub>y</sub>, were calculated respectively. The statistics of TBS<sub>x</sub> and TBS<sub>y</sub> were calculated, and the anisotropy of the trabecular bone, which was defined as the ratio of TBS<sub>y</sub> to TBS<sub>x</sub> and changed with subjects’ BMD and age, was reported and analyzed. Results: The results show that the correlation coefficient between TBS<sub>x</sub> and TBS<sub>y</sub> was 0.72 (p BMD and age was reported. The results showed that decreased trabecular bone anisotropy was associated with deceased BMD and increased age in the subject group. Conclusions: This study shows that decreased trabecular bone anisotropy was associated with decreased BMD and increased age.展开更多
BACKGROUND Retinopathy is the most common microvascular disease of type 2 diabetes,and seriously threatens the life,health and quality of life of patients.It is worth noting that the development of diabetic retinopath...BACKGROUND Retinopathy is the most common microvascular disease of type 2 diabetes,and seriously threatens the life,health and quality of life of patients.It is worth noting that the development of diabetic retinopathy(DR)can be hidden,with few symptoms.Therefore,the preliminary screening of diabetic patients should identify DR as soon as possible,delay disease progression,and play a vital role in its diagnosis and treatment.AIM To investigate the correlation between glycated hemoglobin A1c(HbA1c),urinary microalbumin(U-mALB),urinary creatinine(U-CR),mALB/U-CR ratio,β2 microglobulin(β2MG),retinol binding protein(RBP)and DR.METHODS A total of 180 patients with type 2 diabetes mellitus attending the Second People’s Hospital of Hefei from January 2022 to August 2022 were retrospectively enrolled by ophthalmologists.Based on whether they had combined retinopathy and its degree,68 patients with diabetes mellitus without retinopathy(NDR)were assigned to the NDR group,54 patients with non-proliferative DR(NPDR)to the NPDR group,and 58 patients with proliferative DR to the PDR group.General data,and HbA1c,mALB,β2MG,RBP,mALB/U-CR and U-CR results were collected from the patients and compared among the groups.Pearson's correlation method was used to analyze the correlation between HbA1c,mALB,β2MG,RBP,mALB/U-CR and U-CR indices,and multiple linear regression was applied to identify the risk factors for DR.Receiver operator characteristic(ROC)curves were also drawn.RESULTS The differences in age,gender,systolic and diastolic blood pressure between the groups were not statistically significantly(P>0.05),but the difference in disease duration was statistically significant(P<0.05).The differences in fasting blood glucose,high-density lipoprotein cholesterol,low-density lipoprotein cholesterol,total cholesterol,and triglyceride between the groups were not statistically significant(P>0.05).HbA1c in the PDR group was higher than that in the NPDR and NDR groups(P<0.05).The levels of mALB,β2MG,RBP,mALB/U-CR and UCR in the PDR group were higher than those in the NPDR and NDR groups(P<0.05).Multiple linear regression analysis showed that disease duration,HbA1c,mALB,β2MG,RBP,mALB/U-CR and U-CR were risk factors for the development of DR.The ROC curve showed that the area under the curve(AUC)for the combination of indices(HbA1c+mALB+mALB/U-CR+U-CR+β2MG+RBP)was 0.958,with a sensitivity of 94.83%and specificity of 96.72%,which was higher than the AUC for single index prediction(P<0.05).CONCLUSION HbA1c,mALB,mALB/U-CR,U-CR,β2MG and RBP can reflect the development of DR and are risk factors affecting PDR,and the combination of these six indices has predictive value for PDR.展开更多
Because of its excellent dose distribution,proton therapy is becoming increasingly popular in the medical application of cancer treatment.A synchrotron-based proton therapy facility was designed and constructed in Sha...Because of its excellent dose distribution,proton therapy is becoming increasingly popular in the medical application of cancer treatment.A synchrotron-based proton therapy facility was designed and constructed in Shanghai.The synchrotron,beam delivery system,and other technical systems were commissioned and reached their expected performances.After a clinical trial of 47 patients was finished,the proton therapy facility obtained a registration certificate from the National Medical Products Administration.The characteristics of the accelerator and treatment systems are described in this article.展开更多
Engineering benefits humanity,and technology creates the future.Linking scientific discoveries,technological inventions,and industrial innovation,engineering technology is an important driving force for economic and s...Engineering benefits humanity,and technology creates the future.Linking scientific discoveries,technological inventions,and industrial innovation,engineering technology is an important driving force for economic and social development and a key support for addressing global risks and challenges.Today,in the early 21st century,a new round of technological revolution and industrial transformation is continuing to evolve,and engineering technology innovation has entered a dense and active cycle,especially in fields such as information technology,energy technology,biotechnology,advanced manufacturing,and space exploration.Groundbreaking achievements in engineering innovation are constantly emerging.展开更多
Background:Until January 18,2021,coronavirus disease-2019(COVID-19)has infected more than 93 million individuals and has caused a certain degree of panic.Viral pneumonia caused by common viruses such as respiratory sy...Background:Until January 18,2021,coronavirus disease-2019(COVID-19)has infected more than 93 million individuals and has caused a certain degree of panic.Viral pneumonia caused by common viruses such as respiratory syncytial virus,rhinovirus,human metapneumovirus,human bocavirus,and parainfluenza viruses have been more common in children.However,the incidence of COVID-19 in children was significantly lower than that in adults.The purpose of this study was to describe the clinical manifestations,treatment and outcomes of COVID-19 in children compared with those of other sources of viral pneumonia diagnosed during the COVID-19 outbreak.Methods:Children with COVID-19 and viral pneumonia admitted to 20 hospitals were enrolled in this retrospective multi-center cohort study.A total of 64 children with COVID-19 were defined as the COVID-19 cohort,of which 40 children who developed pneumonia were defined as the COVID-19 pneumonia cohort.Another 284 children with pneumonia caused by other viruses were defined as the viral pneumonia cohort.The epidemiologic,clinical,and laboratory findings were compared by Kolmogorov-Smirnov test,t-test,Mann-Whitney U test and Contingency table method.Drug usage,immunotherapy,blood transfusion,and need for oxygen support were collected as the treatment indexes.Mortality,intensive care needs and symptomatic duration were collected as the outcome indicators.Results:Compared with the viral pneumonia cohort,children in the COVID-19 cohort were mostly exposed to family members confirmed to have COVID-19(53/64 vs.23/284),were of older median age(6.3 years vs.3.2 years),and had a higher proportion of ground-glass opacity(GGO)on computed tomography(18/40 vs.0/38,P<0.001).Children in the COVID-19 pneumonia cohort had a lower proportion of severe cases(1/40 vs.38/284,P=0.048),and lower cases with high fever(3/40 vs.167/284,P<0.001),requiring intensive care(1/40 vs.32/284,P<0.047)and with shorter symptomatic duration(median 5d vs.8d,P<0.001).The proportion of cases with evaluated inflammatory indicators,biochemical indicators related to organ or tissue damage,D-dimer and secondary bacterial infection were lower in the COVID-19 pneumonia cohort than those in the viral pneumonia cohort(P<0.05).No statistical differences were found in the duration of positive PCR results from pharyngeal swabs in 25 children with COVID-19 who received antiviral drugs(lopinavir-ritonavir,ribavirin,and arbidol)as compared with duration in 39 children without antiviral therapy(median 10d vs.9d,P=0.885).Conclusions:The symptoms and severity of COVID-19 pneumonia in children were no more severe than those in children with other viral pneumonia.Lopinavir-ritonavir,ribavirin and arbidol do not shorten the duration of positive PCR results from pharyngeal swabs in children with COVID-19.During the COVID-19 outbreak,attention also must be given to children with infection by other pathogens infection.展开更多
1.Introduction China has announced that it will adopt forceful policies and measures and strive to achieve peak carbon dioxide(CO_(2))emissions before 2030 and carbon neutrality before 2060—aims that are largely cons...1.Introduction China has announced that it will adopt forceful policies and measures and strive to achieve peak carbon dioxide(CO_(2))emissions before 2030 and carbon neutrality before 2060—aims that are largely consistent with the goal to limit warming to 1.5C[1].Achieving this target requires the deep decarbonization of China’s entire economy,with a particular focus on coal-fired power plants(CFPPs).展开更多
The rotating packed bed(RPB)has been widely used in gas-liquid flow systems as a process intensification device,exhibiting excellent mass transfer enhancement characteristics.However,the complex internal structure and...The rotating packed bed(RPB)has been widely used in gas-liquid flow systems as a process intensification device,exhibiting excellent mass transfer enhancement characteristics.However,the complex internal structure and the high-speed rotation of the rotor in RPB bring significant challenges to study the intensification mechanism by experiment methods.In the past two decades,Computational fluid dynamics(CFD)has been gradually applied to simulate the hydrodynamics and mass transfer characteristics in RPB and instruct the reactor design.This article covers the development of the CFD simulation of gasliquid flow in RPB.Firstly,the improvement of the simulation method in the aspect of mathematical models,geometric models,and solving methods is introduced.Secondly,new progress of CFD simulation about hydrodynamic and mass transfer characteristics in RPB is reviewed,including pressure drop,velocity distribution,flow pattern,and concentration distribution,etc.Some new phenomena such as the end effect area with the maximum turbulent have been revealed by this works.In addition,the exploration of developing new reactor structures by CFD simulation is introduced and it is proved that such new structures are competitive to different applications.The defects of current research and future development directions are also discussed at last.展开更多
Pollution involving pharmaceutical components in bodies of water is an increasingly serious environmental issue.Plasma discharge for the degradation of antibiotics is an emerging technology that may be relevant toward...Pollution involving pharmaceutical components in bodies of water is an increasingly serious environmental issue.Plasma discharge for the degradation of antibiotics is an emerging technology that may be relevant toward addressing this issue.In this work,a plasma-assisted rotating disk reactor(plasma-RDR)and a photocatalyst—namely,titanium dioxide(TiO_(2))—were coupled for the treatment of metronidazole(MNZ).Discharge uniformity was improved by the use of a rotating electrode in the plasma-RDR,which contributed to the utilization of ultraviolet(UV)light radiation in the presence of TiO_(2).The experimental results showed that the degradation efficiency of MNZ and the concentration of generated hydroxyl radicals respectively increased by 41%and 2.954 mg∙L^(-1) as the rotational speed increased from 0 to 500 r∙min^(-1).The synergistic effect of plasma-RDR plus TiO_(2) on the generation of hydroxyl radicals was evaluated.Major intermediate products were identified using three-dimensional(3D)excitation emission fluorescence matrices(EEFMs)and liquid chromatography-mass spectrometry(LC-MS),and a possible degradation pathway is proposed herein.This plasma-catalytic process has bright prospects in the field of antibiotics degradation.展开更多
Herein,we report on the effect of a high gravity field on metal-free catalytic reduction,taking the nitrobenzene(NB)reduction and methylene blue(MB)degradation as model reactions in a highgravity rotating tube reactor...Herein,we report on the effect of a high gravity field on metal-free catalytic reduction,taking the nitrobenzene(NB)reduction and methylene blue(MB)degradation as model reactions in a highgravity rotating tube reactor packed with three-dimensional(3D)nitrogen-doped graphene foam(NGF)as a metal-free catalyst.The apparent rate constant(kapp)of the metal-free catalytic reduction of NB in the rotating tube reactor under a high gravity level of 6484g(g=9.81 m s-2)was six times greater than that in a conventional stirred reactor(STR)under gravity.Computational fluid dynamics(CFD)simulations indicated that the improvement of the catalytic efficiency was attributed to the much higher turbulent kinetic energy and faster surface renewal rate in the high-gravity tube reactor in comparison w让h those in a conventional STR.The structure of the 3D metal-free catalysts was stable during the reaction process under a high gravity field,as confirmed by X-ray photoelectron spectroscopy(XPS)and Raman spectra.In the other model reaction,the rate of MB degradation also increased as the high gravity level in creased gradually,which aligns with the result for the NB catalytic reduction system.These results demonstrate the potential to use a high-gravity rotating packed tube reactor for the process intensification of metal-free catalytic reduction reactions.展开更多
Engineering is an integrated activity in which humans create or change the characters of things by using science and technology and employing resources in an organized manner in order to survive,develop,and achieve sp...Engineering is an integrated activity in which humans create or change the characters of things by using science and technology and employing resources in an organized manner in order to survive,develop,and achieve specific purposes[1].From the pyramids in ancient Egypt to the Eiffel Tower in modern Paris,and from the Apollo Manned Lunar Landing Project in the United States to the Three Gorges Key Water Conservancy Project in China,human engineering practices profoundly change the planet we live on and are constantly enriching and expanding our world.展开更多
Graphitic carbon nitride(g-C_(3)N_(4)) with transition metal phosphides has been studied extensively as potential photocatalysts for hydrogen evolution.However,in-situ approaches to realize intimate interfacial contac...Graphitic carbon nitride(g-C_(3)N_(4)) with transition metal phosphides has been studied extensively as potential photocatalysts for hydrogen evolution.However,in-situ approaches to realize intimate interfacial contacts have rarely been reported.In this study,Ni_(2)P nanoparticlesdecorated g-C_(3)N_(4)photocatalysts were prepared via liquid exfoliation of g-C_(3)N_(4) followed by in-situ loading of Ni_(2)P nanoparticles in a rotating packed bed(RPB) reactor.The optimized Ni_(2)P/g-C_(3)N_(4) exhibits high performance in visible-light-driven(λ > 420 nm) hydrogen evolution(~561 μmol g-1h-1),which is 103 times higher than that of pristine g-C_(3)N_(4).The superior photocatalytic performance and durability originate from the robust interfacial structure.Therefore,a Z-scheme route with enhanced transfer of photoinduced electron was proposed,and Ni_(2)P/gC_(3)N_(4) composites with smaller bandgaps than those of g-C_(3)N_(4) were realized.Due to the intensified mass transfer and mixing of RPB reactor,the adsorption and nucleation processes of Ni_(2)P on g-C_(3)N_(4) were enhanced,enabling scalable solar light-driven H_(2) production.展开更多
Microdroplets and their dispersion,with a large specific surface area and a short diffusion distance,have been applied in various unit operations and reaction processes.However,it is still a challenge to control the s...Microdroplets and their dispersion,with a large specific surface area and a short diffusion distance,have been applied in various unit operations and reaction processes.However,it is still a challenge to control the size and size distribution of microdroplets,especially for high-throughput generation.In this work,a novel ultra-high speed rotating packed bed(UHS-RPB)was invented,in which rotating foam packing with a speed of 4000-12000 r·min^(-1) provides microfluidic channels to disperse liquid into microdroplets with high throughput.Then generated microdroplets can be directly dispersed into a continuous falling film for obtaining a mixture of microdroplet dispersion.In this UHS-RPB,the effects of rotational speed,liquid initial velocity,liquid viscosity,liquid surface tension and packing pore size on the average size(d_(32))and size distribution of microdroplets were systematically investigated.Results showed that the UHS-RPB could produce microdroplets with a d_(32) of 25-63μm at a liquid flow rate of 1025 L·h^(-1),and the size distribution of the microdroplets accords well with Rosin-Rammler distribution model.In addi-tion,a correlation was established for the prediction of d_(32),and the predicted d_(32) was in good agreement with the experimental data with a deviation within±15%.These results demonstrated that UHS-RPB could be a promising candidate for controllable preparation of uniform microdroplets.展开更多
Selective hydrogenation plays an important role in chemical industries,yet its selectivity is usually limited by the mass transfer.In this work,the enhanced hydrogenation selectivity was achieved in a rotating packed ...Selective hydrogenation plays an important role in chemical industries,yet its selectivity is usually limited by the mass transfer.In this work,the enhanced hydrogenation selectivity was achieved in a rotating packed bed(RPB)reactor with excellent mass transfer efficiency.Aiming to be used under the centrifugal filed,a monolithic catalyst Pd/c-Al_(2)O_(3)/nickel foam suiting for the shape and size of the rotor of RPB reactor was prepared by the electrophoretic deposition method.The mechanical strength of the catalyst can meet the requirement of high centrifugal force in the RPB.The hydrogenation selectivity in the RPB reactor using the 3-methyl-1-pentyn-3-ol hydrogenation system was 3–8 times higher than that in a stirred tank reactor under similar conditions.This work proves the feasibility of intensifying the selectivity of hydrogenation process in the RPB reactor.展开更多
Soft matter refers to a class of materials that can be easily deformed,either by small forces or by thermal energy.These materials generally have both solid-like and liquid-like behaviors.They are typically characteri...Soft matter refers to a class of materials that can be easily deformed,either by small forces or by thermal energy.These materials generally have both solid-like and liquid-like behaviors.They are typically characterized by some elastic coefficient whose value is many orders of magnitude less than most solids.The unit of an elastic constant is pressure or energy density.The energies that characterize materials can vary by a few orders of magnitude,from thermal energies to several electron volts,the latter of which characterize a strong covalent bond.However,the elastic coefficients of soft materials can be as much as ten orders of magnitude less than those of solids.This range must reflect a change in the length scale or the density term.Thus,the fundamental physics of soft matter always occurs at larger length scales,and it is the study of these larger length scales that gives the field its great fascination.展开更多
Objective:To explore the effect of sodium valproate retard tablet on the oxidative stress system, cognitive function, and thyroid hormone level in patients with epilepsy.Methods:A total of 68 patients with epilepsy we...Objective:To explore the effect of sodium valproate retard tablet on the oxidative stress system, cognitive function, and thyroid hormone level in patients with epilepsy.Methods:A total of 68 patients with epilepsy were included in the study and randomized into the treatment group and the control group with 34 cases in each group. The patients in the treatment group were given sodium valproate retard tablets, while the patients in the control group were given carbamazepine. The patients in the two groups were treated continuously for 6 months. The oxidative stress indicators and thyroid hormone level before and after treatment in the two groups were detected and compared. MMSE was used to evaluate the cognitive function in the two groups.Results: MPO, SOD, CAT, and GSH-Px levels after treatment in the two groups were significantly reduced when compared with before treatment, while MDA level was significantly elevated. The improvement of the above indicators after treatment in the treatment group was significantly superior to that in the control group. FT3 and FT4 levels after treatment in the control group were significantly reduced when compared with before treatment, but were significantly lower than those in the treatment group. MMSE score 3 and 6 months after treatment in the two groups was significantly elevated when compared with before treatment. MMSE score at each timing point after treatment in the treatment group was significantly higher than that in the control group.Conclusions: The sodium valproate has a small effect on the balance of oxidation and anti-oxidation in patients with epilepsy, and can significantly improve the cognitive function.展开更多
Abrasive waterjet(AWJ)is widely applied in 2D machining as it offers high machining efficiency and low machining cost.However,machining a 3D surface,especially for a small curvature radius freeform surface(SCRFS),resu...Abrasive waterjet(AWJ)is widely applied in 2D machining as it offers high machining efficiency and low machining cost.However,machining a 3D surface,especially for a small curvature radius freeform surface(SCRFS),results in over-erosion of the corner,and has been one of the greatest issues of AWJ.To solve this problem,a local smoothing algorithm for SCRFS is developed by the junction of two linear segments at the corner by inserting cubic second-order B-spline to smooth the nozzle path and posture under the setting tolerance error,which is aimed to avoid over-erosion due to the change in dwell time.Analytical solutions of the smooth corner position and orientation of the nozzle path are obtained by evaluating a synchronization algorithm.According to the set tolerance error of the nozzle position and orientation,the interpolation of the smooth path of the corner meets the constraint conditions of the linear feed drive.Path simulation and experimental results show that the proposed method is validated by the experimental results and has been applied to the integral blisk machining of an aero-engine.展开更多
文摘Background: When applied to trabecular bone X-ray images, the anisotropic properties of trabeculae located at ultra-distal radius were investigated by using the trabecular bone scores (TBS) calculated along directions parallel and perpendicular to the forearm. Methodology: Data from more than two hundred subjects were studied retrospectively. A DXA (GE Lunar Prodigy) scan of the forearm was performed on each subject to measure the bone mineral density (BMD) value at the location of ultra-distal radius, and an X-ray digital image of the same forearm was taken on the same day. The values of trabecular bone score along the direction perpendicular to the forearm, TBS<sub>x</sub>, and along the direction parallel to the forearm, TBS<sub>y</sub>, were calculated respectively. The statistics of TBS<sub>x</sub> and TBS<sub>y</sub> were calculated, and the anisotropy of the trabecular bone, which was defined as the ratio of TBS<sub>y</sub> to TBS<sub>x</sub> and changed with subjects’ BMD and age, was reported and analyzed. Results: The results show that the correlation coefficient between TBS<sub>x</sub> and TBS<sub>y</sub> was 0.72 (p BMD and age was reported. The results showed that decreased trabecular bone anisotropy was associated with deceased BMD and increased age in the subject group. Conclusions: This study shows that decreased trabecular bone anisotropy was associated with decreased BMD and increased age.
文摘BACKGROUND Retinopathy is the most common microvascular disease of type 2 diabetes,and seriously threatens the life,health and quality of life of patients.It is worth noting that the development of diabetic retinopathy(DR)can be hidden,with few symptoms.Therefore,the preliminary screening of diabetic patients should identify DR as soon as possible,delay disease progression,and play a vital role in its diagnosis and treatment.AIM To investigate the correlation between glycated hemoglobin A1c(HbA1c),urinary microalbumin(U-mALB),urinary creatinine(U-CR),mALB/U-CR ratio,β2 microglobulin(β2MG),retinol binding protein(RBP)and DR.METHODS A total of 180 patients with type 2 diabetes mellitus attending the Second People’s Hospital of Hefei from January 2022 to August 2022 were retrospectively enrolled by ophthalmologists.Based on whether they had combined retinopathy and its degree,68 patients with diabetes mellitus without retinopathy(NDR)were assigned to the NDR group,54 patients with non-proliferative DR(NPDR)to the NPDR group,and 58 patients with proliferative DR to the PDR group.General data,and HbA1c,mALB,β2MG,RBP,mALB/U-CR and U-CR results were collected from the patients and compared among the groups.Pearson's correlation method was used to analyze the correlation between HbA1c,mALB,β2MG,RBP,mALB/U-CR and U-CR indices,and multiple linear regression was applied to identify the risk factors for DR.Receiver operator characteristic(ROC)curves were also drawn.RESULTS The differences in age,gender,systolic and diastolic blood pressure between the groups were not statistically significantly(P>0.05),but the difference in disease duration was statistically significant(P<0.05).The differences in fasting blood glucose,high-density lipoprotein cholesterol,low-density lipoprotein cholesterol,total cholesterol,and triglyceride between the groups were not statistically significant(P>0.05).HbA1c in the PDR group was higher than that in the NPDR and NDR groups(P<0.05).The levels of mALB,β2MG,RBP,mALB/U-CR and UCR in the PDR group were higher than those in the NPDR and NDR groups(P<0.05).Multiple linear regression analysis showed that disease duration,HbA1c,mALB,β2MG,RBP,mALB/U-CR and U-CR were risk factors for the development of DR.The ROC curve showed that the area under the curve(AUC)for the combination of indices(HbA1c+mALB+mALB/U-CR+U-CR+β2MG+RBP)was 0.958,with a sensitivity of 94.83%and specificity of 96.72%,which was higher than the AUC for single index prediction(P<0.05).CONCLUSION HbA1c,mALB,mALB/U-CR,U-CR,β2MG and RBP can reflect the development of DR and are risk factors affecting PDR,and the combination of these six indices has predictive value for PDR.
文摘Because of its excellent dose distribution,proton therapy is becoming increasingly popular in the medical application of cancer treatment.A synchrotron-based proton therapy facility was designed and constructed in Shanghai.The synchrotron,beam delivery system,and other technical systems were commissioned and reached their expected performances.After a clinical trial of 47 patients was finished,the proton therapy facility obtained a registration certificate from the National Medical Products Administration.The characteristics of the accelerator and treatment systems are described in this article.
文摘Engineering benefits humanity,and technology creates the future.Linking scientific discoveries,technological inventions,and industrial innovation,engineering technology is an important driving force for economic and social development and a key support for addressing global risks and challenges.Today,in the early 21st century,a new round of technological revolution and industrial transformation is continuing to evolve,and engineering technology innovation has entered a dense and active cycle,especially in fields such as information technology,energy technology,biotechnology,advanced manufacturing,and space exploration.Groundbreaking achievements in engineering innovation are constantly emerging.
基金Scientific Research Project of Military Logistics Department,Grant Award Number:CLB20J032。
文摘Background:Until January 18,2021,coronavirus disease-2019(COVID-19)has infected more than 93 million individuals and has caused a certain degree of panic.Viral pneumonia caused by common viruses such as respiratory syncytial virus,rhinovirus,human metapneumovirus,human bocavirus,and parainfluenza viruses have been more common in children.However,the incidence of COVID-19 in children was significantly lower than that in adults.The purpose of this study was to describe the clinical manifestations,treatment and outcomes of COVID-19 in children compared with those of other sources of viral pneumonia diagnosed during the COVID-19 outbreak.Methods:Children with COVID-19 and viral pneumonia admitted to 20 hospitals were enrolled in this retrospective multi-center cohort study.A total of 64 children with COVID-19 were defined as the COVID-19 cohort,of which 40 children who developed pneumonia were defined as the COVID-19 pneumonia cohort.Another 284 children with pneumonia caused by other viruses were defined as the viral pneumonia cohort.The epidemiologic,clinical,and laboratory findings were compared by Kolmogorov-Smirnov test,t-test,Mann-Whitney U test and Contingency table method.Drug usage,immunotherapy,blood transfusion,and need for oxygen support were collected as the treatment indexes.Mortality,intensive care needs and symptomatic duration were collected as the outcome indicators.Results:Compared with the viral pneumonia cohort,children in the COVID-19 cohort were mostly exposed to family members confirmed to have COVID-19(53/64 vs.23/284),were of older median age(6.3 years vs.3.2 years),and had a higher proportion of ground-glass opacity(GGO)on computed tomography(18/40 vs.0/38,P<0.001).Children in the COVID-19 pneumonia cohort had a lower proportion of severe cases(1/40 vs.38/284,P=0.048),and lower cases with high fever(3/40 vs.167/284,P<0.001),requiring intensive care(1/40 vs.32/284,P<0.047)and with shorter symptomatic duration(median 5d vs.8d,P<0.001).The proportion of cases with evaluated inflammatory indicators,biochemical indicators related to organ or tissue damage,D-dimer and secondary bacterial infection were lower in the COVID-19 pneumonia cohort than those in the viral pneumonia cohort(P<0.05).No statistical differences were found in the duration of positive PCR results from pharyngeal swabs in 25 children with COVID-19 who received antiviral drugs(lopinavir-ritonavir,ribavirin,and arbidol)as compared with duration in 39 children without antiviral therapy(median 10d vs.9d,P=0.885).Conclusions:The symptoms and severity of COVID-19 pneumonia in children were no more severe than those in children with other viral pneumonia.Lopinavir-ritonavir,ribavirin and arbidol do not shorten the duration of positive PCR results from pharyngeal swabs in children with COVID-19.During the COVID-19 outbreak,attention also must be given to children with infection by other pathogens infection.
基金This work was supported by the major consulting research projects of the Chinese Academy of Engineering“Research on the Strategy of Carbon Sequestration and Resource Utilization,”the Ministry of Education of Humanities and Social Science project(21YJC630009)the National Natural Science Foundation of China(72104116,72025401,71974108,and 71690244)the Tsinghua University-INDITEX Sustainable Development Fund.
文摘1.Introduction China has announced that it will adopt forceful policies and measures and strive to achieve peak carbon dioxide(CO_(2))emissions before 2030 and carbon neutrality before 2060—aims that are largely consistent with the goal to limit warming to 1.5C[1].Achieving this target requires the deep decarbonization of China’s entire economy,with a particular focus on coal-fired power plants(CFPPs).
基金supported by the National Natural Science Foundation of China(21978011 and 21725601).
文摘The rotating packed bed(RPB)has been widely used in gas-liquid flow systems as a process intensification device,exhibiting excellent mass transfer enhancement characteristics.However,the complex internal structure and the high-speed rotation of the rotor in RPB bring significant challenges to study the intensification mechanism by experiment methods.In the past two decades,Computational fluid dynamics(CFD)has been gradually applied to simulate the hydrodynamics and mass transfer characteristics in RPB and instruct the reactor design.This article covers the development of the CFD simulation of gasliquid flow in RPB.Firstly,the improvement of the simulation method in the aspect of mathematical models,geometric models,and solving methods is introduced.Secondly,new progress of CFD simulation about hydrodynamic and mass transfer characteristics in RPB is reviewed,including pressure drop,velocity distribution,flow pattern,and concentration distribution,etc.Some new phenomena such as the end effect area with the maximum turbulent have been revealed by this works.In addition,the exploration of developing new reactor structures by CFD simulation is introduced and it is proved that such new structures are competitive to different applications.The defects of current research and future development directions are also discussed at last.
基金This work was supported by the National Natural Science Foundation of China(21725601).
文摘Pollution involving pharmaceutical components in bodies of water is an increasingly serious environmental issue.Plasma discharge for the degradation of antibiotics is an emerging technology that may be relevant toward addressing this issue.In this work,a plasma-assisted rotating disk reactor(plasma-RDR)and a photocatalyst—namely,titanium dioxide(TiO_(2))—were coupled for the treatment of metronidazole(MNZ).Discharge uniformity was improved by the use of a rotating electrode in the plasma-RDR,which contributed to the utilization of ultraviolet(UV)light radiation in the presence of TiO_(2).The experimental results showed that the degradation efficiency of MNZ and the concentration of generated hydroxyl radicals respectively increased by 41%and 2.954 mg∙L^(-1) as the rotational speed increased from 0 to 500 r∙min^(-1).The synergistic effect of plasma-RDR plus TiO_(2) on the generation of hydroxyl radicals was evaluated.Major intermediate products were identified using three-dimensional(3D)excitation emission fluorescence matrices(EEFMs)and liquid chromatography-mass spectrometry(LC-MS),and a possible degradation pathway is proposed herein.This plasma-catalytic process has bright prospects in the field of antibiotics degradation.
基金We are grateful for financial support from National Natural Science Foundation of China(21620102007)the Fundamental Research Funds for the Central Universities of China(JD2002).
文摘Herein,we report on the effect of a high gravity field on metal-free catalytic reduction,taking the nitrobenzene(NB)reduction and methylene blue(MB)degradation as model reactions in a highgravity rotating tube reactor packed with three-dimensional(3D)nitrogen-doped graphene foam(NGF)as a metal-free catalyst.The apparent rate constant(kapp)of the metal-free catalytic reduction of NB in the rotating tube reactor under a high gravity level of 6484g(g=9.81 m s-2)was six times greater than that in a conventional stirred reactor(STR)under gravity.Computational fluid dynamics(CFD)simulations indicated that the improvement of the catalytic efficiency was attributed to the much higher turbulent kinetic energy and faster surface renewal rate in the high-gravity tube reactor in comparison w让h those in a conventional STR.The structure of the 3D metal-free catalysts was stable during the reaction process under a high gravity field,as confirmed by X-ray photoelectron spectroscopy(XPS)and Raman spectra.In the other model reaction,the rate of MB degradation also increased as the high gravity level in creased gradually,which aligns with the result for the NB catalytic reduction system.These results demonstrate the potential to use a high-gravity rotating packed tube reactor for the process intensification of metal-free catalytic reduction reactions.
文摘Engineering is an integrated activity in which humans create or change the characters of things by using science and technology and employing resources in an organized manner in order to survive,develop,and achieve specific purposes[1].From the pyramids in ancient Egypt to the Eiffel Tower in modern Paris,and from the Apollo Manned Lunar Landing Project in the United States to the Three Gorges Key Water Conservancy Project in China,human engineering practices profoundly change the planet we live on and are constantly enriching and expanding our world.
基金supported by National Natural Science Foundation of China(21620102007)the Fundamental Research Funds for the Central Universities of China(JD2002)。
文摘Graphitic carbon nitride(g-C_(3)N_(4)) with transition metal phosphides has been studied extensively as potential photocatalysts for hydrogen evolution.However,in-situ approaches to realize intimate interfacial contacts have rarely been reported.In this study,Ni_(2)P nanoparticlesdecorated g-C_(3)N_(4)photocatalysts were prepared via liquid exfoliation of g-C_(3)N_(4) followed by in-situ loading of Ni_(2)P nanoparticles in a rotating packed bed(RPB) reactor.The optimized Ni_(2)P/g-C_(3)N_(4) exhibits high performance in visible-light-driven(λ > 420 nm) hydrogen evolution(~561 μmol g-1h-1),which is 103 times higher than that of pristine g-C_(3)N_(4).The superior photocatalytic performance and durability originate from the robust interfacial structure.Therefore,a Z-scheme route with enhanced transfer of photoinduced electron was proposed,and Ni_(2)P/gC_(3)N_(4) composites with smaller bandgaps than those of g-C_(3)N_(4) were realized.Due to the intensified mass transfer and mixing of RPB reactor,the adsorption and nucleation processes of Ni_(2)P on g-C_(3)N_(4) were enhanced,enabling scalable solar light-driven H_(2) production.
基金supported by National Natural Science Foundation of China(21725601)。
文摘Microdroplets and their dispersion,with a large specific surface area and a short diffusion distance,have been applied in various unit operations and reaction processes.However,it is still a challenge to control the size and size distribution of microdroplets,especially for high-throughput generation.In this work,a novel ultra-high speed rotating packed bed(UHS-RPB)was invented,in which rotating foam packing with a speed of 4000-12000 r·min^(-1) provides microfluidic channels to disperse liquid into microdroplets with high throughput.Then generated microdroplets can be directly dispersed into a continuous falling film for obtaining a mixture of microdroplet dispersion.In this UHS-RPB,the effects of rotational speed,liquid initial velocity,liquid viscosity,liquid surface tension and packing pore size on the average size(d_(32))and size distribution of microdroplets were systematically investigated.Results showed that the UHS-RPB could produce microdroplets with a d_(32) of 25-63μm at a liquid flow rate of 1025 L·h^(-1),and the size distribution of the microdroplets accords well with Rosin-Rammler distribution model.In addi-tion,a correlation was established for the prediction of d_(32),and the predicted d_(32) was in good agreement with the experimental data with a deviation within±15%.These results demonstrated that UHS-RPB could be a promising candidate for controllable preparation of uniform microdroplets.
基金supported by the National Natural Science Foundation of China(22022802 and 91934303).
文摘Selective hydrogenation plays an important role in chemical industries,yet its selectivity is usually limited by the mass transfer.In this work,the enhanced hydrogenation selectivity was achieved in a rotating packed bed(RPB)reactor with excellent mass transfer efficiency.Aiming to be used under the centrifugal filed,a monolithic catalyst Pd/c-Al_(2)O_(3)/nickel foam suiting for the shape and size of the rotor of RPB reactor was prepared by the electrophoretic deposition method.The mechanical strength of the catalyst can meet the requirement of high centrifugal force in the RPB.The hydrogenation selectivity in the RPB reactor using the 3-methyl-1-pentyn-3-ol hydrogenation system was 3–8 times higher than that in a stirred tank reactor under similar conditions.This work proves the feasibility of intensifying the selectivity of hydrogenation process in the RPB reactor.
文摘Soft matter refers to a class of materials that can be easily deformed,either by small forces or by thermal energy.These materials generally have both solid-like and liquid-like behaviors.They are typically characterized by some elastic coefficient whose value is many orders of magnitude less than most solids.The unit of an elastic constant is pressure or energy density.The energies that characterize materials can vary by a few orders of magnitude,from thermal energies to several electron volts,the latter of which characterize a strong covalent bond.However,the elastic coefficients of soft materials can be as much as ten orders of magnitude less than those of solids.This range must reflect a change in the length scale or the density term.Thus,the fundamental physics of soft matter always occurs at larger length scales,and it is the study of these larger length scales that gives the field its great fascination.
文摘Objective:To explore the effect of sodium valproate retard tablet on the oxidative stress system, cognitive function, and thyroid hormone level in patients with epilepsy.Methods:A total of 68 patients with epilepsy were included in the study and randomized into the treatment group and the control group with 34 cases in each group. The patients in the treatment group were given sodium valproate retard tablets, while the patients in the control group were given carbamazepine. The patients in the two groups were treated continuously for 6 months. The oxidative stress indicators and thyroid hormone level before and after treatment in the two groups were detected and compared. MMSE was used to evaluate the cognitive function in the two groups.Results: MPO, SOD, CAT, and GSH-Px levels after treatment in the two groups were significantly reduced when compared with before treatment, while MDA level was significantly elevated. The improvement of the above indicators after treatment in the treatment group was significantly superior to that in the control group. FT3 and FT4 levels after treatment in the control group were significantly reduced when compared with before treatment, but were significantly lower than those in the treatment group. MMSE score 3 and 6 months after treatment in the two groups was significantly elevated when compared with before treatment. MMSE score at each timing point after treatment in the treatment group was significantly higher than that in the control group.Conclusions: The sodium valproate has a small effect on the balance of oxidation and anti-oxidation in patients with epilepsy, and can significantly improve the cognitive function.
基金supported by NSFC-Liaoning Joint Fund(Grant Nos.U1708256,U1908232)Fundamental Research Funds for the Central Universities(Grant No.DUT18GF104)Joint Fund of MOE and GAD(Grant No.6141A02022133).
文摘Abrasive waterjet(AWJ)is widely applied in 2D machining as it offers high machining efficiency and low machining cost.However,machining a 3D surface,especially for a small curvature radius freeform surface(SCRFS),results in over-erosion of the corner,and has been one of the greatest issues of AWJ.To solve this problem,a local smoothing algorithm for SCRFS is developed by the junction of two linear segments at the corner by inserting cubic second-order B-spline to smooth the nozzle path and posture under the setting tolerance error,which is aimed to avoid over-erosion due to the change in dwell time.Analytical solutions of the smooth corner position and orientation of the nozzle path are obtained by evaluating a synchronization algorithm.According to the set tolerance error of the nozzle position and orientation,the interpolation of the smooth path of the corner meets the constraint conditions of the linear feed drive.Path simulation and experimental results show that the proposed method is validated by the experimental results and has been applied to the integral blisk machining of an aero-engine.
