Malignant tumor has become a major threat affecting human health,and is one of the main causes of human death.Recent studies have shown that many traditional Chinese medicines(TCM)have good anti-tumor activity,which m...Malignant tumor has become a major threat affecting human health,and is one of the main causes of human death.Recent studies have shown that many traditional Chinese medicines(TCM)have good anti-tumor activity,which may improve the therapeutic effect of routine treatment and quality of life with lower toxicity.However,the efficacy of TCM alone for the treatment of tumors is limited.Metal ions are essential substances for maintaining normal physiological activities.This article summarized the multiple mechanisms in which metal ions are involved in the prevention and treatment of tumors in TCM.展开更多
Dear Editor,Fungicide treatment has a profound effect on controlling plant pathogens in modern agriculture,however,it also carries the risk of undesirable outcomes.For decades,scientists have been concerned about the ...Dear Editor,Fungicide treatment has a profound effect on controlling plant pathogens in modern agriculture,however,it also carries the risk of undesirable outcomes.For decades,scientists have been concerned about the harmful impacts of heavy metals like copper(Cu)on crop performance and soil microorganisms.Use of various copper fungicides,like Bordeaux mixture,have been a component of conventional agricultural practices to control fungal and bacterial pathogens,especially in vineyards,tea gardens,or fruit tree orchards[9,10].This treatment increases the accumulation of high levels of Cu in surface soils,and despite the critical role of Cu as an essential trace element in wide biological and metabolic processes,it becomes toxic to plants when applied at high levels[4].The regular application of copper fungicides has also been linked to affecting microbial communities at the levels of diversity[8],population structure[2],abundance,and growth[1,3].Understanding the undesired effects of fungicides on microorganisms’beneficial activities is therefore important for evaluating the hazards associated with the fungicide used in agriculture.Yet,the effects of copper fungicide on full microbial communities remains relatively understudied,especially in tea plants.Thus,we herein explored the inf luence of Bordeaux mixture under different management regimes(raking or without raking leaf litter)on microbial communities of root,bulk soil,and rhizosphere compartments of tea plants planted in a ten-year-old tea garden.We provided insights into the ecological consequences of tea management practices that might help to identify specific fungicide treatment regimens,environmental characteristics,and microbial community members to minimize the negative environmental outcomes and optimize the positive anti-pathogen aspects of fungicide treatment.展开更多
Weakly consolidated reservoirs are prone to sand production problem,which can lead to equipment damages and environmental issues.The conditions for sand production depend on stresses and properties of rock and fluid.A...Weakly consolidated reservoirs are prone to sand production problem,which can lead to equipment damages and environmental issues.The conditions for sand production depend on stresses and properties of rock and fluid.Accurate sand volume estimation is,however,still a challenging issue,especially for reservoirs in weak formations.The weak reservoirs containing viscous or heavy oil are mainly discovered in shallow depths in Kazakhstan,with moderate temperature and pressure.Many prediction models developed for open-hole completions where the reservoir materials usually possess certain strength are not applicable for the local reservoirs where the materials are significantly weaker even if casing is used to support the wellbore with oil produced through the perforation tunnels.In this context,a prediction model was proposed where the volume of the produced sand was estimated as the volume of the plastic zone of the failed materials surrounding the perforation tunnels.The model assumes an evolving truncated conical shape for the damage zone and takes into account stress distributions and shear failure in this zone.Then,the proposed model was used to estimate sand volumes in 20 wells during oil production with sequential increase of flow rates.The predictions match well with the measured sand volumes in a local oil field.Finally,a sensitivity analysis was conducted on the model performance.It shows that the permeability of the plastic zone was the most significant controlling factor in the prediction results.展开更多
This study aims to develop several optimization techniques for predicting advance rate of tunnel boring machine(TBM)in different weathered zones of granite.For this purpose,extensive field and laboratory studies have ...This study aims to develop several optimization techniques for predicting advance rate of tunnel boring machine(TBM)in different weathered zones of granite.For this purpose,extensive field and laboratory studies have been conducted along the 12,649 m of the Pahang-Selangor raw water transfer tunnel in Malaysia.Rock properties consisting of uniaxial compressive strength(UCS),Brazilian tensile strength(BTS),rock mass rating(RMR),rock quality designation(RQD),quartz content(q)and weathered zone as well as machine specifications including thrust force and revolution per minute(RPM)were measured to establish comprehensive datasets for optimization.Accordingly,to estimate the advance rate of TBM,two new hybrid optimization techniques,i.e.an artificial neural network(ANN)combined with both imperialist competitive algorithm(ICA)and particle swarm optimization(PSO),were developed for mechanical tunneling in granitic rocks.Further,the new hybrid optimization techniques were compared and the best one was chosen among them to be used for practice.To evaluate the accuracy of the proposed models for both testing and training datasets,various statistical indices including coefficient of determination(R^2),root mean square error(RMSE)and variance account for(VAF)were utilized herein.The values of R^2,RMSE,and VAF ranged in 0.939-0.961,0.022-0.036,and 93.899-96.145,respectively,with the PSO-ANN hybrid technique demonstrating the best performance.It is concluded that both the optimization techniques,i.e.PSO-ANN and ICA-ANN,could be utilized for predicting the advance rate of TBMs;however,the PSO-ANN technique is superior.展开更多
The high-energy lithium/sulfur(Li/S) battery has become a very popular topic of research in recent years due to its high theoretical capacity of 1672 m Ah/g. However, the polysulfide shuttle effect remains of great co...The high-energy lithium/sulfur(Li/S) battery has become a very popular topic of research in recent years due to its high theoretical capacity of 1672 m Ah/g. However, the polysulfide shuttle effect remains of great concern with a great number of publications dedicated to its mitigation. In this contribution, a three-dimensional(3D) reduced graphene oxide/activated carbon(RGO/AC) film, synthesized by a simple hydrothermal method and convenient mechanical pressing, is sandwiched between the separator and the sulfur-based cathode, acting as a functional interlayer to capture and trap polysulfide species. Consequently, the Li/S cell with this interlayer shows an impressive initial discharge capacity of 1078 m Ah/g and a reversible capacity of 655 m Ah/g even after 100 cycles. The RGO/AC interlayer impedes the movement of polysulfide while providing unimpeded channels for lithium ion mass transfer. Therefore, the RGO/AC interlayer with a well-designed structure represents strong potential for high-performance Li/S batteries.展开更多
Background:Measurements of tree heights and diameters are essential in forest assessment and modelling.Tree heights are used for estimating timber volume,site index and other important variables related to forest grow...Background:Measurements of tree heights and diameters are essential in forest assessment and modelling.Tree heights are used for estimating timber volume,site index and other important variables related to forest growth and yield,succession and carbon budget models.However,the diameter at breast height(dbh) can be more accurately obtained and at lower cost,than total tree height.Hence,generalized height-diameter(h-d) models that predict tree height from dbh,age and other covariates are needed.For a more flexible but biologically plausible estimation of covariate effects we use shape constrained generalized additive models as an extension of existing h-d model approaches.We use causal site parameters such as index of aridity to enhance the generality and causality of the models and to enable predictions under projected changeable climatic conditions.Methods:We develop unconstrained generalized additive models(GAM) and shape constrained generalized additive models(SCAM) for investigating the possible effects of tree-specific parameters such as tree age,relative diameter at breast height,and site-specific parameters such as index of aridity and sum of daily mean temperature during vegetation period,on the h-d relationship of forests in Lower Saxony,Germany.Results:Some of the derived effects,e.g.effects of age,index of aridity and sum of daily mean temperature have significantly non-linear pattern.The need for using SCAM results from the fact that some of the model effects show partially implausible patterns especially at the boundaries of data ranges.The derived model predicts monotonically increasing levels of tree height with increasing age and temperature sum and decreasing aridity and social rank of a tree within a stand.The definition of constraints leads only to marginal or minor decline in the model statistics like AlC.An observed structured spatial trend in tree height is modelled via 2-dimensional surface fitting.Conclusions:We demonstrate that the SCAM approach allows optimal regression modelling flexibility similar to the standard GAM but with the additional possibility of defining specific constraints for the model effects.The longitudinal character of the model allows for tree height imputation for the current status of forests but also for future tree height prediction.展开更多
BACKGROUND Celiac Disease(CD)is an immune-mediated disorder,in which the HLA immunogenetic background(DQ2 and DQ8 heterodimers)and environmental trigger(gluten)are well established.Indeed,both factors are necessary–b...BACKGROUND Celiac Disease(CD)is an immune-mediated disorder,in which the HLA immunogenetic background(DQ2 and DQ8 heterodimers)and environmental trigger(gluten)are well established.Indeed,both factors are necessary–but not sufficient–to develop CD.However,it is very likely that CD is underdiagnosed in both developing and developed countries,due to several aspects,including the fact that a lot of patients present mild and/or atypical symptoms,without the presence of any recognized risk factors.Therefore,the possibility and feasibility of widened screening strategies to identify CD patients are debated.AIM To provide further evidence of the main epidemiological importance of HLADQB1*02 allele in the population of CD patients.METHODS We performed a systematic search in PubMed,EMBASE,Cochrane,Web of Science and Scopus databases,in order to produce a systematic review assessing the carrier frequency of HLA-DQB1*02 allele in the celiac population.Following the PRISMA guidelines,we retrieved all the original articles describing CD patients’HLA-DQB1 genotype in such a way that could allow to assess the HLADQB1*02 carrier frequency among CD patients,along with the evidence of the appropriate diagnostic work-up to achieve a correct and final diagnosis of CD.RESULTS The final output of this systematic search in the medical literature consisted of 38 studies providing the appropriate HLA-DQB1 genotype information of the respective CD population.According to this systematic review,including a pool of 4945 HLA-DQ genotyped CD patients,the HLA-DQB1*02 carrier frequency was 94.94%,meaning that only 5.06%of CD patients were completely lacking this allelic variant.Interestingly,if we consider only the studies whereby the prevalence of CD patients affected with type 1 diabetes mellitus was supposed or clearly established to be very low,the frequency of non-HLA-DQB1*02 carriers among CD patients dropped to 3.65%.CONCLUSION Such a high carrier frequency of the HLA-DQB1*02 allelic variant(which is>95%-96%in CD patients without risk factors,like type 1 diabetes mellitus comorbidity)might be exploited to consider a cost-effective and widened screening approach.If a sustainable strategy could be implemented through a low-cost targeted genetic test to detect the individual presence of HLA-DQB1*02 allele,an appropriate algorithm for serological screening in individuals resulting to be genetically predisposed to CD,might be considered.展开更多
Celiac Disease(CD)had been considered uncommon in Asia for a long time.However,several studies suggested that,in the Indian subcontinent and Middle East countries,CD is present and as prevalent as in Western countries...Celiac Disease(CD)had been considered uncommon in Asia for a long time.However,several studies suggested that,in the Indian subcontinent and Middle East countries,CD is present and as prevalent as in Western countries.Outside these Asian regions,the information about the epidemiology of CD is still lacking or largely incomplete for different and variable reasons.Here,we discuss the epidemiological aspects and the diagnostic barriers in several Asian regions including China,Japan,Southeast Asia and Russia/Central Asia.In some of those regions,especially Russia and Central Asia,the prevalence of CD is very likely to be underestimated.Several factors may,to a different extent,contribute to CD underdiagnosis(and,thus,underestimation of its epidemiological burden),including the poor disease awareness among physicians and/or patients,limited access to diagnostic resources,inappropriate use or interpretation of the serological tests,absence of standardized diagnostic and endoscopic protocols,and insufficient expertise in histopathological interpretation.展开更多
The flow of blasted ore during mining of moderately dipping medium-thick orebodies is a challenge.Selecting a suitable mining system for such ore bodies is difficult.This paper proposes a diamond layout sublevel open ...The flow of blasted ore during mining of moderately dipping medium-thick orebodies is a challenge.Selecting a suitable mining system for such ore bodies is difficult.This paper proposes a diamond layout sublevel open stoping system using fan blastholes with backfilling to mine such orebodies.To evaluate the performance of system the relationships between ore recovery and stope footwall dip angle,footwall surface roughness,drawpoint spacing and production blast ring burden were investigated.An ore recovery data set from 81 laboratory physical model experiments was established from combinations of the listed factors.Various modules in a back propagation neural network structure were compared,and an optimal network structure identified.An ore recovery backpropagation neural network(BPNN)forecast model was developed.Using the model and sensitivity analysis of the factors affecting the proposed open stope mining system,the significance of each factor on ore recovery was studied.The study results were applied to a case study at the Shandong Gold Group Jiaojia Gold Mine.The results showed that the application of a BPNN and sensitivity analysis models for ore recovery prediction in the proposed mining system and field experimental results confirm that the suggested mining method is feasible.展开更多
Acute acalculous cholecystitis(AAC) is the inflammatory disease of the gallbladder in the absence of gallstones. AAC is estimated to represent at least 50% to 70% of all cases of acute cholecystitis during childhood. ...Acute acalculous cholecystitis(AAC) is the inflammatory disease of the gallbladder in the absence of gallstones. AAC is estimated to represent at least 50% to 70% of all cases of acute cholecystitis during childhood. Although this pathology was originally described in critically ill or post-surgical patients, most pediatric cases have been observed during several infectious diseases. In addition to cases caused by bacterial and parasitic infections, most pediatric reports after 2000 described children developing AAC during viral illnesses(such as Epstein-Barr virus and hepatitis A virus infections). Moreover, some pediatric cases have been associated with several underlying chronic diseases and, in particular, with immune-mediated disorders. Here, we review the epidemiological aspects of pediatric AAC, and we discuss etiology, pathophysiology and clinical management, according to the cases reported in the medical literature.展开更多
Ordinary chronic pancreatitis is a well-known risk factor for pancreatic cancer,whereas such an association with autoimmune pancreatitis(AIP)is widely debated.Due to the rarity of the latter disorder,there are few spe...Ordinary chronic pancreatitis is a well-known risk factor for pancreatic cancer,whereas such an association with autoimmune pancreatitis(AIP)is widely debated.Due to the rarity of the latter disorder,there are few specific clinical and epidemiological studies investigating the relation between AIP and pancreatic cancer,which do not seem to support it.However,these studies are affected by several limitations and,therefore,a link between AIP(and,specifically,type 1 AIP)and pancreatic cancer cannot be ruled out definitively on this basis.Moreover,several immunopathological aspects of type 1 AIP and,in general,immunoglobulin G4-related disease can create an immunological context that may impair the tumoral immunosurveillance and promote the pancreatic carcinogenesis and its progression.In detail,Th2 immunological dominance,type 2 macrophage polarization and basophil infiltration observed in type 1 AIP,may play a permissive role in creating a favorable immunological environment for pancreatic carcinogenesis,in addition to the immunosuppressive therapies that can be used in these patients.展开更多
Static cracking agent(SCA)is actively investigated as an alternative to explosive blasting for rock breakage due to its immense expansion property.SCA can eliminate the negative effects of shock,noise and harmful gase...Static cracking agent(SCA)is actively investigated as an alternative to explosive blasting for rock breakage due to its immense expansion property.SCA can eliminate the negative effects of shock,noise and harmful gases encountered in explosive blasting processes.Accurate measurement and deep understanding of the expansive properties of SCAs are important in their industrial application.An improved outer pipe method(OPM),termed the upper end surface method(UESM),is proposed in this paper to overcome the shortcomings of the OPM in the expansive pressure measurement of SCAs.Numerical simulation is used to proof the concept and a mathematical model established to relate the internal pressure and the radial strains at different positions in the upper end surface method test equipment.The new equipment is calibrated using oil pressure and strain measurements.The calibrated equipment is then used to measure the expansion pressure of SCA at three different water contents to proof its potential.The differences in the measurements with OPM and UESM at three different moisture contents are less than 4%.The experimental results confirm the accuracy and applicability of the more user friendly and less expensive UESM in the measurement of the expansive pressures of SCAs.展开更多
Aqueous rechargeable zinc batteries are getting increasing attention for large-scale energy storage owing to their advantages in terms of cost,environmental friendliness and safety.Here,the layered puckeredγ’-V_(2)O...Aqueous rechargeable zinc batteries are getting increasing attention for large-scale energy storage owing to their advantages in terms of cost,environmental friendliness and safety.Here,the layered puckeredγ’-V_(2)O_(5) polymorph with a porous morphology is firstly introduced as cathode for an aqueous zinc battery system in a binary Zn^(2+)/Li^(+)electrolyte.The Zn‖γ’-V_(2)O_(5) cell delivers high capacities of 240 and190 mAh g^(-1) at current densities of 29 and 147 mA g^(-1),respectively,and remarkable cycling stability in the 1.6 V-0.7 V voltage window(97%retention after 100 cycles at 0.15 A g^(-1)).The detailed structural evolution during first discharge-charge and subsequent cycling is investigated using X-ray diffraction and Raman spectroscopy.We demonstrate a reaction mechanism based on a selective Li insertion in the1.6 V-1.0 V voltage range.It involves a reversible exchange of 0.8 Li^(+)in γ’-V_(2)O_(5) and the same structural response as the one reported in lithiated organic electrolyte.However,in the extended 1.6 V-0.7 V voltage range,this work puts forward a concomitant and gradual phase transformation from γ’-V_(2)O_(5) to zinc pyrovanadate Zn_(3)V_(2)O_(7)(OH)2.2 H_(2)O(ZVO)during cycling.Such mechanism involving the in-situ formation of ZVO,known as an efficient Zn and Li intercalation material,explains the high electrochemical performance here reported for the Zn‖γ’-V_(2)O_(5) cell.This work highlights the peculiar layered-puckeredγ’-V_(2)O_(5) polymorph outperforms the conventionalα-V_(2)O_(5) with a huge improvement of capacity of 240 mAh g^(-1)vs 80 mAh g^(-1) in the same electrolyte and voltage window.展开更多
Hybrid organic-inorganic perovskite solar cells(PSCs) are considered to be the most promising thirdgeneration photovoltaic(PV) technology with the most rapid rate of increase in the power conversion efficiency(PCE). T...Hybrid organic-inorganic perovskite solar cells(PSCs) are considered to be the most promising thirdgeneration photovoltaic(PV) technology with the most rapid rate of increase in the power conversion efficiency(PCE). To date, their PCE values are comparable to the established photovoltaic technologies such as crystalline silicon. Intensive research activities associated with PSCs have been being performed,since 2009, aiming to further boost the device performance in terms of efficiency and stability via different strategies in order to accelerate the progress of commercialization. The emerging 2 D black phosphorus(BP) is a novel class of semiconducting material owing to its unique characteristics, allowing them to become attractive materials for applications in a variety of optical and electronic devices, which have been comprehensively reviewed in the literature. However, comprehensive reviews focusing on the application of BP in PSCs are scarce in the community. This review discusses the research works with the incorporation of BP as a functional material in PSCs. The methodology as well as the effects of employing BP in different regions of PSCs are summarized. Further challenges and potential research directions are also highlighted.展开更多
Objectives:The unrelenting migration trend of Filipino nurses to other countries has threatened the quality of patient care services in the country.This study explored the extent of nurses'organizational commitmen...Objectives:The unrelenting migration trend of Filipino nurses to other countries has threatened the quality of patient care services in the country.This study explored the extent of nurses'organizational commitment and turnover intention in the Philippines.Furthermore,predictors of nurses'organizational commitment and turnover intention were identified.Methods:A cross-sectional research design was adopted for this study.Two hundred nurses from nine rural hospitals in the Central Philippines were asked to participate in the study and 166 nurses responded(an 83%response rate).Two standardized instruments were used:the Organizational Commitment Questionnaire and the Six-item Turnover Intention Inventory Scale.Results:Findings revealed that Philippine nurses were moderately committed(3.13±0.24)to and were undecided(2.42±0.67)whether or not to leave their organization.Nurses'age(P=0.006),gender,(t=-2.25,P=0.026),education(t=2.38,P<0.001),rank(t=4.38,P<0.001),and work experience(t=2.18,P=0.031)correlated significantly with organizational commitment,while nurses'age(P=0.028)and education(t=1.99,P=0.048)correlated significantly with turnover intention.An inverse relationship was identified between the organizational commitment and turnover intention(r=-0.22,P=0.005).Conclusion:The findings of this study highlight the need for formulation and implementation of interventions to promote life-long commitment in nurses and to reduce turnover rates.展开更多
This paper aims to establish an intelligent procedure that combines the observational method with the existing deep learning technique for updating deformation of braced excavation in clay.The gated recurrent unit(GRU...This paper aims to establish an intelligent procedure that combines the observational method with the existing deep learning technique for updating deformation of braced excavation in clay.The gated recurrent unit(GRU) neural network is adopted to formulate the forecast model and learn the potential rules in the field observations using the Nesterov-accelerated Adam(Nadam) algorithm.In the proposed procedure,the GRU-based forecast model is first trained based on the field data of previous and current stages.Then,the field data of the current stage are used as input to predict the deformation response of the next stage via the previously trained GRU-based forecast model.This updating process will loop up till the end of the excavation.This procedure has the advantage of directly predicting the deformation response of unexcavated stages based on the monitoring data.The proposed intelligent procedure is verified on two well-documented cases in terms of accuracy and reliability.The results indicate that both wall deflection and ground settlement are accurately predicted as the excavation proceeds.Furthermore,the advantages of the proposed intelligent procedure compared with the Bayesian/o ptimization updating are illustrated.展开更多
To examine the effect of pressure on pore structure and petrophysical properties of carbonate rock, the porosity, permeability, CT scanning, SEM and elastic wave velocity of two carbonate core plug samples from an oil...To examine the effect of pressure on pore structure and petrophysical properties of carbonate rock, the porosity, permeability, CT scanning, SEM and elastic wave velocity of two carbonate core plug samples from an oilfield in Southwest Iran were analyzed under cyclic pressure. One of the plugs was calcite and the other was dolomite with anhydrite nodules. The cyclic pressure exerted on the samples increased from 13.79 MPa to 27.58 MPa in six steps, and the variations in petrophysical properties of the two samples at different pressure loading and unloading steps were counted and analyzed. The results show that the calcite sample decreases in porosity and permeability with the increase of pressure, which is consistent with the results from compression and shear wave velocity tests. In the dolomite sample, the decreasing trend was not observed;fluctuations of compressive and shear velocities were observed during the loading stage, which may be due to different geometries of the pores and the porosity variation in the sample. Understanding the variation of carbonate petrophysical properties with pressure is helpful for optimizing reservoir development scheme.展开更多
文摘Malignant tumor has become a major threat affecting human health,and is one of the main causes of human death.Recent studies have shown that many traditional Chinese medicines(TCM)have good anti-tumor activity,which may improve the therapeutic effect of routine treatment and quality of life with lower toxicity.However,the efficacy of TCM alone for the treatment of tumors is limited.Metal ions are essential substances for maintaining normal physiological activities.This article summarized the multiple mechanisms in which metal ions are involved in the prevention and treatment of tumors in TCM.
基金supported by the National Natural Science Founda-tion of China(No.32002086)the Natural Science Research Project of University in Anhui Province(No.202244)+1 种基金the Top Talent Team Project of Anhui Agriculture University(No.03082021)Key Program in the Joint Funds of National Natural Science Founda-tion of China(No U19A2034).
文摘Dear Editor,Fungicide treatment has a profound effect on controlling plant pathogens in modern agriculture,however,it also carries the risk of undesirable outcomes.For decades,scientists have been concerned about the harmful impacts of heavy metals like copper(Cu)on crop performance and soil microorganisms.Use of various copper fungicides,like Bordeaux mixture,have been a component of conventional agricultural practices to control fungal and bacterial pathogens,especially in vineyards,tea gardens,or fruit tree orchards[9,10].This treatment increases the accumulation of high levels of Cu in surface soils,and despite the critical role of Cu as an essential trace element in wide biological and metabolic processes,it becomes toxic to plants when applied at high levels[4].The regular application of copper fungicides has also been linked to affecting microbial communities at the levels of diversity[8],population structure[2],abundance,and growth[1,3].Understanding the undesired effects of fungicides on microorganisms’beneficial activities is therefore important for evaluating the hazards associated with the fungicide used in agriculture.Yet,the effects of copper fungicide on full microbial communities remains relatively understudied,especially in tea plants.Thus,we herein explored the inf luence of Bordeaux mixture under different management regimes(raking or without raking leaf litter)on microbial communities of root,bulk soil,and rhizosphere compartments of tea plants planted in a ten-year-old tea garden.We provided insights into the ecological consequences of tea management practices that might help to identify specific fungicide treatment regimens,environmental characteristics,and microbial community members to minimize the negative environmental outcomes and optimize the positive anti-pathogen aspects of fungicide treatment.
基金sponsored by a Nazarbayev University research grant
文摘Weakly consolidated reservoirs are prone to sand production problem,which can lead to equipment damages and environmental issues.The conditions for sand production depend on stresses and properties of rock and fluid.Accurate sand volume estimation is,however,still a challenging issue,especially for reservoirs in weak formations.The weak reservoirs containing viscous or heavy oil are mainly discovered in shallow depths in Kazakhstan,with moderate temperature and pressure.Many prediction models developed for open-hole completions where the reservoir materials usually possess certain strength are not applicable for the local reservoirs where the materials are significantly weaker even if casing is used to support the wellbore with oil produced through the perforation tunnels.In this context,a prediction model was proposed where the volume of the produced sand was estimated as the volume of the plastic zone of the failed materials surrounding the perforation tunnels.The model assumes an evolving truncated conical shape for the damage zone and takes into account stress distributions and shear failure in this zone.Then,the proposed model was used to estimate sand volumes in 20 wells during oil production with sequential increase of flow rates.The predictions match well with the measured sand volumes in a local oil field.Finally,a sensitivity analysis was conducted on the model performance.It shows that the permeability of the plastic zone was the most significant controlling factor in the prediction results.
文摘This study aims to develop several optimization techniques for predicting advance rate of tunnel boring machine(TBM)in different weathered zones of granite.For this purpose,extensive field and laboratory studies have been conducted along the 12,649 m of the Pahang-Selangor raw water transfer tunnel in Malaysia.Rock properties consisting of uniaxial compressive strength(UCS),Brazilian tensile strength(BTS),rock mass rating(RMR),rock quality designation(RQD),quartz content(q)and weathered zone as well as machine specifications including thrust force and revolution per minute(RPM)were measured to establish comprehensive datasets for optimization.Accordingly,to estimate the advance rate of TBM,two new hybrid optimization techniques,i.e.an artificial neural network(ANN)combined with both imperialist competitive algorithm(ICA)and particle swarm optimization(PSO),were developed for mechanical tunneling in granitic rocks.Further,the new hybrid optimization techniques were compared and the best one was chosen among them to be used for practice.To evaluate the accuracy of the proposed models for both testing and training datasets,various statistical indices including coefficient of determination(R^2),root mean square error(RMSE)and variance account for(VAF)were utilized herein.The values of R^2,RMSE,and VAF ranged in 0.939-0.961,0.022-0.036,and 93.899-96.145,respectively,with the PSO-ANN hybrid technique demonstrating the best performance.It is concluded that both the optimization techniques,i.e.PSO-ANN and ICA-ANN,could be utilized for predicting the advance rate of TBMs;however,the PSO-ANN technique is superior.
基金financial support from the National Natural Science Foundation of China(grant no.21406052the Program for the Outstanding Young Talents of Hebei Province(grant no.BJ2014010)the Scientific Research Foundation for Selected Overseas Chinese Scholars,Ministry of Human Resources and Social Security of China(grant no.CG2015003002)
文摘The high-energy lithium/sulfur(Li/S) battery has become a very popular topic of research in recent years due to its high theoretical capacity of 1672 m Ah/g. However, the polysulfide shuttle effect remains of great concern with a great number of publications dedicated to its mitigation. In this contribution, a three-dimensional(3D) reduced graphene oxide/activated carbon(RGO/AC) film, synthesized by a simple hydrothermal method and convenient mechanical pressing, is sandwiched between the separator and the sulfur-based cathode, acting as a functional interlayer to capture and trap polysulfide species. Consequently, the Li/S cell with this interlayer shows an impressive initial discharge capacity of 1078 m Ah/g and a reversible capacity of 655 m Ah/g even after 100 cycles. The RGO/AC interlayer impedes the movement of polysulfide while providing unimpeded channels for lithium ion mass transfer. Therefore, the RGO/AC interlayer with a well-designed structure represents strong potential for high-performance Li/S batteries.
文摘Background:Measurements of tree heights and diameters are essential in forest assessment and modelling.Tree heights are used for estimating timber volume,site index and other important variables related to forest growth and yield,succession and carbon budget models.However,the diameter at breast height(dbh) can be more accurately obtained and at lower cost,than total tree height.Hence,generalized height-diameter(h-d) models that predict tree height from dbh,age and other covariates are needed.For a more flexible but biologically plausible estimation of covariate effects we use shape constrained generalized additive models as an extension of existing h-d model approaches.We use causal site parameters such as index of aridity to enhance the generality and causality of the models and to enable predictions under projected changeable climatic conditions.Methods:We develop unconstrained generalized additive models(GAM) and shape constrained generalized additive models(SCAM) for investigating the possible effects of tree-specific parameters such as tree age,relative diameter at breast height,and site-specific parameters such as index of aridity and sum of daily mean temperature during vegetation period,on the h-d relationship of forests in Lower Saxony,Germany.Results:Some of the derived effects,e.g.effects of age,index of aridity and sum of daily mean temperature have significantly non-linear pattern.The need for using SCAM results from the fact that some of the model effects show partially implausible patterns especially at the boundaries of data ranges.The derived model predicts monotonically increasing levels of tree height with increasing age and temperature sum and decreasing aridity and social rank of a tree within a stand.The definition of constraints leads only to marginal or minor decline in the model statistics like AlC.An observed structured spatial trend in tree height is modelled via 2-dimensional surface fitting.Conclusions:We demonstrate that the SCAM approach allows optimal regression modelling flexibility similar to the standard GAM but with the additional possibility of defining specific constraints for the model effects.The longitudinal character of the model allows for tree height imputation for the current status of forests but also for future tree height prediction.
基金the Nazarbayev University Faculty Development Competitive Research Grant 2020-2022,No.240919FD3912.
文摘BACKGROUND Celiac Disease(CD)is an immune-mediated disorder,in which the HLA immunogenetic background(DQ2 and DQ8 heterodimers)and environmental trigger(gluten)are well established.Indeed,both factors are necessary–but not sufficient–to develop CD.However,it is very likely that CD is underdiagnosed in both developing and developed countries,due to several aspects,including the fact that a lot of patients present mild and/or atypical symptoms,without the presence of any recognized risk factors.Therefore,the possibility and feasibility of widened screening strategies to identify CD patients are debated.AIM To provide further evidence of the main epidemiological importance of HLADQB1*02 allele in the population of CD patients.METHODS We performed a systematic search in PubMed,EMBASE,Cochrane,Web of Science and Scopus databases,in order to produce a systematic review assessing the carrier frequency of HLA-DQB1*02 allele in the celiac population.Following the PRISMA guidelines,we retrieved all the original articles describing CD patients’HLA-DQB1 genotype in such a way that could allow to assess the HLADQB1*02 carrier frequency among CD patients,along with the evidence of the appropriate diagnostic work-up to achieve a correct and final diagnosis of CD.RESULTS The final output of this systematic search in the medical literature consisted of 38 studies providing the appropriate HLA-DQB1 genotype information of the respective CD population.According to this systematic review,including a pool of 4945 HLA-DQ genotyped CD patients,the HLA-DQB1*02 carrier frequency was 94.94%,meaning that only 5.06%of CD patients were completely lacking this allelic variant.Interestingly,if we consider only the studies whereby the prevalence of CD patients affected with type 1 diabetes mellitus was supposed or clearly established to be very low,the frequency of non-HLA-DQB1*02 carriers among CD patients dropped to 3.65%.CONCLUSION Such a high carrier frequency of the HLA-DQB1*02 allelic variant(which is>95%-96%in CD patients without risk factors,like type 1 diabetes mellitus comorbidity)might be exploited to consider a cost-effective and widened screening approach.If a sustainable strategy could be implemented through a low-cost targeted genetic test to detect the individual presence of HLA-DQB1*02 allele,an appropriate algorithm for serological screening in individuals resulting to be genetically predisposed to CD,might be considered.
基金Nazarbayev University Faculty Development Competitive Research Grant 2020-2022,No.240919FD3912.
文摘Celiac Disease(CD)had been considered uncommon in Asia for a long time.However,several studies suggested that,in the Indian subcontinent and Middle East countries,CD is present and as prevalent as in Western countries.Outside these Asian regions,the information about the epidemiology of CD is still lacking or largely incomplete for different and variable reasons.Here,we discuss the epidemiological aspects and the diagnostic barriers in several Asian regions including China,Japan,Southeast Asia and Russia/Central Asia.In some of those regions,especially Russia and Central Asia,the prevalence of CD is very likely to be underestimated.Several factors may,to a different extent,contribute to CD underdiagnosis(and,thus,underestimation of its epidemiological burden),including the poor disease awareness among physicians and/or patients,limited access to diagnostic resources,inappropriate use or interpretation of the serological tests,absence of standardized diagnostic and endoscopic protocols,and insufficient expertise in histopathological interpretation.
基金funded by the State Key Research Development Program of China(2018YFC0604400)the National Science Foundation of China(No.51874068)+2 种基金the Fundamental Research Funds for the Central Universities(N160107001,N180701016)the 111 Project(B17009)Nazarbayev University for the Faculty Development Competitive Research Grant(240919FD3920)。
文摘The flow of blasted ore during mining of moderately dipping medium-thick orebodies is a challenge.Selecting a suitable mining system for such ore bodies is difficult.This paper proposes a diamond layout sublevel open stoping system using fan blastholes with backfilling to mine such orebodies.To evaluate the performance of system the relationships between ore recovery and stope footwall dip angle,footwall surface roughness,drawpoint spacing and production blast ring burden were investigated.An ore recovery data set from 81 laboratory physical model experiments was established from combinations of the listed factors.Various modules in a back propagation neural network structure were compared,and an optimal network structure identified.An ore recovery backpropagation neural network(BPNN)forecast model was developed.Using the model and sensitivity analysis of the factors affecting the proposed open stope mining system,the significance of each factor on ore recovery was studied.The study results were applied to a case study at the Shandong Gold Group Jiaojia Gold Mine.The results showed that the application of a BPNN and sensitivity analysis models for ore recovery prediction in the proposed mining system and field experimental results confirm that the suggested mining method is feasible.
文摘Acute acalculous cholecystitis(AAC) is the inflammatory disease of the gallbladder in the absence of gallstones. AAC is estimated to represent at least 50% to 70% of all cases of acute cholecystitis during childhood. Although this pathology was originally described in critically ill or post-surgical patients, most pediatric cases have been observed during several infectious diseases. In addition to cases caused by bacterial and parasitic infections, most pediatric reports after 2000 described children developing AAC during viral illnesses(such as Epstein-Barr virus and hepatitis A virus infections). Moreover, some pediatric cases have been associated with several underlying chronic diseases and, in particular, with immune-mediated disorders. Here, we review the epidemiological aspects of pediatric AAC, and we discuss etiology, pathophysiology and clinical management, according to the cases reported in the medical literature.
文摘Ordinary chronic pancreatitis is a well-known risk factor for pancreatic cancer,whereas such an association with autoimmune pancreatitis(AIP)is widely debated.Due to the rarity of the latter disorder,there are few specific clinical and epidemiological studies investigating the relation between AIP and pancreatic cancer,which do not seem to support it.However,these studies are affected by several limitations and,therefore,a link between AIP(and,specifically,type 1 AIP)and pancreatic cancer cannot be ruled out definitively on this basis.Moreover,several immunopathological aspects of type 1 AIP and,in general,immunoglobulin G4-related disease can create an immunological context that may impair the tumoral immunosurveillance and promote the pancreatic carcinogenesis and its progression.In detail,Th2 immunological dominance,type 2 macrophage polarization and basophil infiltration observed in type 1 AIP,may play a permissive role in creating a favorable immunological environment for pancreatic carcinogenesis,in addition to the immunosuppressive therapies that can be used in these patients.
基金funded by the State Key Research Development Program of China(No.2018YFC0604400)the National Science Foundation of China(Nos.51874068,52074062)+2 种基金the Fundamental Research Funds for the Central Universities(Nos.N2001003,N160107001,N180701016,N182608003,N2001001)the 111 Project(No.B17009)The authors also acknowledge Nazarbayev University for funding the research through its Collaborative Research Program(No.OPCRP2020014).
文摘Static cracking agent(SCA)is actively investigated as an alternative to explosive blasting for rock breakage due to its immense expansion property.SCA can eliminate the negative effects of shock,noise and harmful gases encountered in explosive blasting processes.Accurate measurement and deep understanding of the expansive properties of SCAs are important in their industrial application.An improved outer pipe method(OPM),termed the upper end surface method(UESM),is proposed in this paper to overcome the shortcomings of the OPM in the expansive pressure measurement of SCAs.Numerical simulation is used to proof the concept and a mathematical model established to relate the internal pressure and the radial strains at different positions in the upper end surface method test equipment.The new equipment is calibrated using oil pressure and strain measurements.The calibrated equipment is then used to measure the expansion pressure of SCA at three different water contents to proof its potential.The differences in the measurements with OPM and UESM at three different moisture contents are less than 4%.The experimental results confirm the accuracy and applicability of the more user friendly and less expensive UESM in the measurement of the expansive pressures of SCAs.
基金the Ministry of Education and Science of Kazakhstan(grant number AP05136016-ZRABS)French Embassy in Astana,Kazakhstan and Campus France for financial support。
文摘Aqueous rechargeable zinc batteries are getting increasing attention for large-scale energy storage owing to their advantages in terms of cost,environmental friendliness and safety.Here,the layered puckeredγ’-V_(2)O_(5) polymorph with a porous morphology is firstly introduced as cathode for an aqueous zinc battery system in a binary Zn^(2+)/Li^(+)electrolyte.The Zn‖γ’-V_(2)O_(5) cell delivers high capacities of 240 and190 mAh g^(-1) at current densities of 29 and 147 mA g^(-1),respectively,and remarkable cycling stability in the 1.6 V-0.7 V voltage window(97%retention after 100 cycles at 0.15 A g^(-1)).The detailed structural evolution during first discharge-charge and subsequent cycling is investigated using X-ray diffraction and Raman spectroscopy.We demonstrate a reaction mechanism based on a selective Li insertion in the1.6 V-1.0 V voltage range.It involves a reversible exchange of 0.8 Li^(+)in γ’-V_(2)O_(5) and the same structural response as the one reported in lithiated organic electrolyte.However,in the extended 1.6 V-0.7 V voltage range,this work puts forward a concomitant and gradual phase transformation from γ’-V_(2)O_(5) to zinc pyrovanadate Zn_(3)V_(2)O_(7)(OH)2.2 H_(2)O(ZVO)during cycling.Such mechanism involving the in-situ formation of ZVO,known as an efficient Zn and Li intercalation material,explains the high electrochemical performance here reported for the Zn‖γ’-V_(2)O_(5) cell.This work highlights the peculiar layered-puckeredγ’-V_(2)O_(5) polymorph outperforms the conventionalα-V_(2)O_(5) with a huge improvement of capacity of 240 mAh g^(-1)vs 80 mAh g^(-1) in the same electrolyte and voltage window.
基金the Scientific Research Grant from Ministry of Education and Science of the Republic of Kazakhstan(AP08856931)the Nazarbayev University(110119FD4506,021220CRP0422)。
文摘Hybrid organic-inorganic perovskite solar cells(PSCs) are considered to be the most promising thirdgeneration photovoltaic(PV) technology with the most rapid rate of increase in the power conversion efficiency(PCE). To date, their PCE values are comparable to the established photovoltaic technologies such as crystalline silicon. Intensive research activities associated with PSCs have been being performed,since 2009, aiming to further boost the device performance in terms of efficiency and stability via different strategies in order to accelerate the progress of commercialization. The emerging 2 D black phosphorus(BP) is a novel class of semiconducting material owing to its unique characteristics, allowing them to become attractive materials for applications in a variety of optical and electronic devices, which have been comprehensively reviewed in the literature. However, comprehensive reviews focusing on the application of BP in PSCs are scarce in the community. This review discusses the research works with the incorporation of BP as a functional material in PSCs. The methodology as well as the effects of employing BP in different regions of PSCs are summarized. Further challenges and potential research directions are also highlighted.
文摘Objectives:The unrelenting migration trend of Filipino nurses to other countries has threatened the quality of patient care services in the country.This study explored the extent of nurses'organizational commitment and turnover intention in the Philippines.Furthermore,predictors of nurses'organizational commitment and turnover intention were identified.Methods:A cross-sectional research design was adopted for this study.Two hundred nurses from nine rural hospitals in the Central Philippines were asked to participate in the study and 166 nurses responded(an 83%response rate).Two standardized instruments were used:the Organizational Commitment Questionnaire and the Six-item Turnover Intention Inventory Scale.Results:Findings revealed that Philippine nurses were moderately committed(3.13±0.24)to and were undecided(2.42±0.67)whether or not to leave their organization.Nurses'age(P=0.006),gender,(t=-2.25,P=0.026),education(t=2.38,P<0.001),rank(t=4.38,P<0.001),and work experience(t=2.18,P=0.031)correlated significantly with organizational commitment,while nurses'age(P=0.028)and education(t=1.99,P=0.048)correlated significantly with turnover intention.An inverse relationship was identified between the organizational commitment and turnover intention(r=-0.22,P=0.005).Conclusion:The findings of this study highlight the need for formulation and implementation of interventions to promote life-long commitment in nurses and to reduce turnover rates.
基金The financial supports provided by the Research Grants Council(RGC)of Hong Kong Special Administrative Region Government(HKSARG)of China(Grant Nos.15209119 and PolyU R5037-18F)Zhongtian Construction Group Co.Ltd.(Grant No.ZTCG-GDJTYJSJSFW-2020002)。
文摘This paper aims to establish an intelligent procedure that combines the observational method with the existing deep learning technique for updating deformation of braced excavation in clay.The gated recurrent unit(GRU) neural network is adopted to formulate the forecast model and learn the potential rules in the field observations using the Nesterov-accelerated Adam(Nadam) algorithm.In the proposed procedure,the GRU-based forecast model is first trained based on the field data of previous and current stages.Then,the field data of the current stage are used as input to predict the deformation response of the next stage via the previously trained GRU-based forecast model.This updating process will loop up till the end of the excavation.This procedure has the advantage of directly predicting the deformation response of unexcavated stages based on the monitoring data.The proposed intelligent procedure is verified on two well-documented cases in terms of accuracy and reliability.The results indicate that both wall deflection and ground settlement are accurately predicted as the excavation proceeds.Furthermore,the advantages of the proposed intelligent procedure compared with the Bayesian/o ptimization updating are illustrated.
文摘To examine the effect of pressure on pore structure and petrophysical properties of carbonate rock, the porosity, permeability, CT scanning, SEM and elastic wave velocity of two carbonate core plug samples from an oilfield in Southwest Iran were analyzed under cyclic pressure. One of the plugs was calcite and the other was dolomite with anhydrite nodules. The cyclic pressure exerted on the samples increased from 13.79 MPa to 27.58 MPa in six steps, and the variations in petrophysical properties of the two samples at different pressure loading and unloading steps were counted and analyzed. The results show that the calcite sample decreases in porosity and permeability with the increase of pressure, which is consistent with the results from compression and shear wave velocity tests. In the dolomite sample, the decreasing trend was not observed;fluctuations of compressive and shear velocities were observed during the loading stage, which may be due to different geometries of the pores and the porosity variation in the sample. Understanding the variation of carbonate petrophysical properties with pressure is helpful for optimizing reservoir development scheme.
