The purpose of this study was to evaluate the effects of retention ponds on the environment and population health by analyzing water samples from various ponds in Mogadishu, to determine the prevalence of waterborne i...The purpose of this study was to evaluate the effects of retention ponds on the environment and population health by analyzing water samples from various ponds in Mogadishu, to determine the prevalence of waterborne illnesses that occur during the rainy season in Mogadishu, and to find out what experts thought about the effects of retention ponds on the environment as well as population health in Mogadishu. Methods: Mixed designs were used in the study. The first design is an exploratory study where samples are taken from different retention ponds in Mogadishu. The second design involves gathering secondary data from the online FSNAU Dashboard regarding the incidence of rainfall and waterborne illnesses including malaria and cholera. Additionally, a cross-sectional survey of expert opinions using questionnaires was the third design. The 10 water samples were taken from retention ponds in Mogadishu as part of the sample size. Data on the fourth month was also gathered using the FNSAU dashboard, and seventy sample sizes were used for the expert self-administered questionnaire for the third design. Excel was used for data analysis in the initial design. While BMI SPSS versions 22 were used to analyze the data from the Self-administered Questionnaire, additional methods were utilized to compute descriptive statistics, such as mean and standard deviation, and to analyze demographic data in a frequency table. Findings: The results show that three samples had unsatisfactory scores (Grade D): Yaqshid (Warshadda Bastada) had a WQI of 80.85, Boondheer (Bondher Pond) had a WQI of 80.64, and Wartanabad (Xamar Jadiid Pond) had a WQI of 80.89. The remaining samples were all rated as fair (grade), which indicates that they ranged from 50 to 75. The months with the largest rainfall already occurred in December, November, and October, when the prevalence of diseases during the rainy season was highest for cholera cases. Although October and December saw a significant number of malaria cases, November did not. Retention ponds’ overall effects on residential environments were evaluated, and the results showed that the standard deviation was 0.802 and the cumulative average mean scores were 4.41 overall. This indicates that the respondents were in agreement that retention ponds in Mogadishu, Somalia, had an effect on residential areas. Recommendation: The study suggested that in order to identify retention pond contamination and create treatment units for its management, the Ministry of Health forms a district-level public health committee. All districts must have a sewer system installed by the local government, and retention ponds must be made easier in order to move waste outside of the city.展开更多
Purpose: High urinary retention (HUR) can negatively impact renal function. Our study aimed to present the epidemiological, diagnostic, and therapeutic aspects of HUR in a Senegalese academic hospital. Patients and Me...Purpose: High urinary retention (HUR) can negatively impact renal function. Our study aimed to present the epidemiological, diagnostic, and therapeutic aspects of HUR in a Senegalese academic hospital. Patients and Methods: We conducted a retrospective study of 70 patients with HUR associated with renal failure from January 2017 to December 2020. Parameters examined included: age, sex, coexisting conditions affecting renal function, clinical symptoms, diagnostic tests, causes of HUR, urinary diversion, and patient outcomes. Results: The average age was 66, with a majority of male patients (87%). Twenty-three patients had pre-existing medical conditions. Oligo-anuria was the most common reason for detecting HUR (70%). Half of the patients had an ECOG score ≥ 2. The mean creatinine level was 50.7 mg/l. Nineteen patients exhibited hydroelectrolytic disorders. Bacterial colonization was observed in 25 patients. Ultrasound and computed tomography were the most frequently performed imaging tests (100% and 62.8%, respectively). Sixty-seven patients had ureterohydronephrosis (UHN), with bilateral UHN in 88.6% of cases. Pelvic cancers (47.1%) were the primary cause of HUR, primarily bladder cancers (27.1%). Nephrostomy was the most common urinary drainage method (50%), particularly for obstructions due to pelvic cancer (88.6%). The majority of patients (52.8%) regained normal renal function after drainage. Nineteen deaths occurred among elderly patients with compromised general health. Conclusion: Urinary drainage significantly improved renal function for most patients. Pelvic cancer emerged as the leading cause of HUR. Nephrostomy was the predominant drainage method.展开更多
In this study,organic geochemical and petrological analyses were conducted on 111 shale samples from a well to understand the retention,intraformational migration and segmented accumulation(shale oil enrichment in dif...In this study,organic geochemical and petrological analyses were conducted on 111 shale samples from a well to understand the retention,intraformational migration and segmented accumulation(shale oil enrichment in different intervals is unconnected)features of shale oil within the organic-rich shale in the Qingshankou Formation of the Gulong Sag.Our study shows that retained petroleum characteristics in the investigated succession are mainly influenced by three factors:organic richness,intraformational migration and segmented accumulation.Organic matter richness primarily controls the amount of retained petroleum,especially the‘live’component indicated by the S_(2)value rather than the total organic carbon(TOC)figure alone.The negative expulsion efficiencies determined by mass-balance calculations of hydrocarbons reveal that petroleum from adjacent organic-rich intervals migrates into the interval of about 2386-2408 m,which is characterized by high free hydrocarbon(S_(1)),OSI and saturated hydrocarbons content,along with a greater difference inδ^(13)C values between polar compounds(including resins and asphaltenes)and saturated hydrocarbons.The depth-dependent heterogeneity of carbon isotope ratios(δ^(13)C)of mud methane gas,δ^(13)C of extracts gross composition(SARA),δ^(13)C of kerogen and SARA content of extracts suggest that the studied succession can be subdivided into four intervals.The shale oil sealing enrichment character in each interval is further corroborated by the distinctδ^(13)C values of mud methane gas in different intervals.Due to the migration of petroleum into the 2386-2408 m interval,the S_(1),OSI and saturated hydrocarbons content of the interval show higher relative values.The maturity of organic matter in the 2471-2500 m interval is at the highest with the smaller size molecular components of the retained petroleum.Thus,favorable‘sweet spots’may be found in the 2386-2408 m interval and the 2471-2500 m interval,according to the experiment results in this study.展开更多
OsPLS4 encodes aβ-ketoacyl carrier protein reductase(KAR).The role of OsPLS4 in rice sheath blight(Rhizoctonia solani)remains unclear.Our preliminary studies showed that premature leaf senescence mutants(pls4)were hi...OsPLS4 encodes aβ-ketoacyl carrier protein reductase(KAR).The role of OsPLS4 in rice sheath blight(Rhizoctonia solani)remains unclear.Our preliminary studies showed that premature leaf senescence mutants(pls4)were highly susceptive to sheath blight in the early stage of rice development.To explore the role of this gene in the development of rice sheath blight,the transcriptome profiles of the rice pls4 mutant and wild type were compared by RNA-seq.The results revealed 2,569 differentially expressed genes(DEGs).The down-regulated genes were significantly enriched in the defense response-related biological processes.These down-regulated genes included the chitinase genes and WRKY genes,which were significantly changed in pls4 mutants.Furthermore,467 genes induced significant alternative splicing(AS)events.Among them,intron retention(IR)affected gene expression levels and functions of the vitamin B6(VB6)metabolism pathway related to sheath blight.This result suggests that IR plays an important role in the sheath blight resistance of mutant pls4.Together,these results indicate that pls4 could be involved in the biological process of sheath blight via DEGs and the fine-tuning of IR.The present study provides a molecular basis for further investigation of the resistance of rice to sheath blight.展开更多
The persistent challenges in attracting and retaining a diverse healthcare workforce, with a specific focus on nurses, have become increasingly pronounced in recent years. These hurdles have been exacerbated by a grow...The persistent challenges in attracting and retaining a diverse healthcare workforce, with a specific focus on nurses, have become increasingly pronounced in recent years. These hurdles have been exacerbated by a growing difficulty in retaining young nurses, thereby exacerbating labor shortages driven by demographic shifts and the retirement of experienced nursing professionals. While most research efforts have concentrated on the broader issue of nurse retention, our study is centered on a specific demographic—young nurses. Our research endeavors to shed light on the unique challenges faced by young nurses through a qualitative survey involving nursing students who are simultaneously employed. We seek to discern the multifaceted obstacles they encounter in both their academic environment and the healthcare organizations where they work. While certain challenges are linked to course organization, examinations, and the time required for studying, our respondents overwhelmingly emphasize the pivotal role of the work environment in facilitating the harmonization of work, family, and educational commitments. This reconciliation is achieved through measures such as flexible working arrangements and the efficient organization of nursing duties. The primary objective of our research is to provide insights into how these diverse challenges can be effectively addressed and how a range of measures can significantly contribute to the attraction and retention of nursing students, as well as the long-term retention of nurses within the healthcare system. Our recommendations are intended to be of practical use to a wide array of stakeholders, including academic institutions, particularly colleges and universities offering nursing programs, as well as hospitals, clinics, and other healthcare institutions that hire nurses. By collaboratively addressing these challenges and implementing the recommended measures, we aim to fortify the healthcare workforce and ensure the continued provision of quality care to patients. .展开更多
This article has been directed to Environment Protection Technology with the purpose of providing a new instrument designed and developed to measure filtration efficiency through the relationship between clean cloth f...This article has been directed to Environment Protection Technology with the purpose of providing a new instrument designed and developed to measure filtration efficiency through the relationship between clean cloth fabric structural parameters, dust parameters, and test measuring variables. Fabric samples used throughout the present study were woven cotton 100%, polyester 100% and cotton/polyester 50/50%. The warp count: 30/2 for all fabric samples, the weft count is 9/1;12/1;and 20/1. The weave of satin, basket, and twill is 3/1 with four different picks/cm to produce the fabrics with the same cover factor. For dust separation fabrics range in weight from “300 - 450 g/m<sup>2</sup>” with an air permeability of “100 - 300 l/d m<sup>2</sup>·min” at “196.2 Pa” (20 mm WG) as specified in DIN 53887. Air permeability through fabrics depends entirely on the sieving percent of the surface of the fabric, which is partly the pores and partly the permeability through the yarns, which are the basic elements of a fabric. The results showed that dust capturing depends entirely on air permeability, which is related to fabric weave structure and fabric material at specified testing and measuring variables.展开更多
It is well known that air in industrial cities contains a significant amount of dust particles, smoke, and toxic gases. The increased number of vehicles has a direct impact on air quality resulting in the emission of ...It is well known that air in industrial cities contains a significant amount of dust particles, smoke, and toxic gases. The increased number of vehicles has a direct impact on air quality resulting in the emission of exhaust gases, and the increase of dust concentration in air. In this article, we are describing the dust retention ability of plants depending on their leaf structure. Plant species were classified into three groups according to their dust-holding capacities. Dust retaining ability of plant species in conditions of high, average and low dust conditions described.展开更多
Background:Many fire-dependent forests have experienced significant declines in species,structural,and functional diversity.These changes are attributed in part to traditional management approaches that were dominated...Background:Many fire-dependent forests have experienced significant declines in species,structural,and functional diversity.These changes are attributed in part to traditional management approaches that were dominated by even-aged regeneration methods such as clearcutting.Variable retention harvesting(VRH)is an ecologically based forestry practice that involves retention of some mature overstory trees and other biological structures in the postharvest stand to emulate the effects of natural disturbance events.In this study,we examined the effect of a VRH treatment on recruitment of historically dominant pine species and understory vegetation twoand six years after its implementation in a naturally regenerated mixed pine forest in the Upper Peninsula of Michigan,USA.Results:We found greater regeneration of red pine(Pinus resinosa L.)and eastern white pine(Pinus strobus L.)in VRH stands compared to the unharvested controls.Although red pine recruitment was very low during the first 2 years,both species increased significantly from year two to year six.Recruitment responses for the two species did not differ significantly between the aggregated and dispersed retention treatments.We also found high recruitment of deciduous tree species,consisting primarily of sprouts,and red pine exhibited a negative correlation with these sprouts.Treatment,time,and the interaction of treatment and time were significant factors in red pine recruitment.Time had a strong effect on the understory vegetation,with significant decreases in shrubs and ferns over time.Conclusions:The results suggest that VRH enhanced recruitment of red pine and eastern white pine and that this recruitment increased with time.We identify competition from sprouts and unfavorable seedbed conditions as the main factors that limited recruitment of red pine during the first 2 years.To reduce competing vegetation and improve seedbed conditions,we suggest following the VRH with a prescribed fire,mechanically removing sprouts,and implementing herbicide treatments.At a time when changes in global climate exacerbates the effects of traditional drivers of forest degradation,and with the need to maintain biodiversity,new ecologically based forest practices such VRH have the potential to facilitate regeneration of native trees and enhance the resilience of many fire-dependent forests.展开更多
The purpose of the paper is to study retention of vocabulary acquired incidentally on task-induced involvement by senior middle school students. Grade two of senior middle students participated in the experiments, tes...The purpose of the paper is to study retention of vocabulary acquired incidentally on task-induced involvement by senior middle school students. Grade two of senior middle students participated in the experiments, testing whether retention of vocabulary acquired incidentally is contingent on amount of task-induced involvement.Using short-and long term, namely immediate posttest and delayed posttest, retention of twelve unfamiliar words was investigated in three learning tasks (reading, reading plus fill-in and writing) with varying degrees of “involvement load”- various combinations of need, search and evaluation. The results of the experiment partially support the Involvement Load Hypothesis: retention in the writing group was higher than that in the reading plus fill-in group; retention in the reading plus fill-in group was higher than that in the reading group. The results are discussed in light of the construct of task-induced involvement.展开更多
Objective:Gastrointestinal heat retention syndrome(GHRS)is associated with lung-heat syndrome and is related to recurrent respiratory infection.Upper respiratory tract infection(URTI)lung heat syndrome is common in ch...Objective:Gastrointestinal heat retention syndrome(GHRS)is associated with lung-heat syndrome and is related to recurrent respiratory infection.Upper respiratory tract infection(URTI)lung heat syndrome is common in children.The study will explore the effect of GHRS on the structure and function of gut microbiota in children with URTI lung-heat syndrome.Methods:Participants were divided into both groups using the self-developed URTI scale and the“GHRS Diagnostic Scale$Pediatric Part”:GHRS-positive children(LS group)and GHRS-negative children(L group).General information,clinical symptoms,and stool were collected.We used 16S rRNA amplicon sequencing technology to determine the gene sequence of the V3eV4 region in feces and measure the gut microbiota of the both groups at the genus level.Results:A total of 23 children were included in the both groups.There were 12 cases in the LS group and 11 cases in the L group.There was no statistical difference between the both groups in age,gender,height,weight,and body mass index.The effective sequences shared by the both groups accounted for 85.66%of the total.In the gut microbiota,there was no difference in the a diversity and the b diversity between the both groups.Compared with the L group,the LS group had a significant increase in the relative abundance of the Ruminococcus gnavus group,Prevotella-9,Staphylococcus,and Actinomyces(P<.05).The functions of the both groups of microbiota primarily concentrate on metabolism,genetic information processing,and environmental information processing.The relative abundance of signaling molecules and interactions in the LS group were higher than that in the L group(P<.05).The redundancy analysis(RDA)showed that the URTI score had the greatest impact on the distribution of microbiota.Conclusion:GHRS may affect the development of URTI lung-heat syndrome by changing the relative abundances of gut microbiota.展开更多
Polychlorinated dibenzothiophenes(PCDTs) are a group of important persistent organic pollutants.In the present study,geometrical optimization and electrostatic potential calculations have been performed for all 135 PC...Polychlorinated dibenzothiophenes(PCDTs) are a group of important persistent organic pollutants.In the present study,geometrical optimization and electrostatic potential calculations have been performed for all 135 PCDTs congeners at the B3LYP/6-31G* level of theory.By means of the VSMP(variable selection and modeling based on prediction) program,one optimal descriptor(molecular polarizability,α) was selected to develop a QSRR model for the prediction of gas chromatographic retention indices(GC-RI) of PCDTs.The estimated correlation coefficients(r2) and LOO-validated correlation coefficients(q2),all more than 0.99,were built by multiple linear regression,which shows a good estimation ability and stability of the models.A prediction power for the external samples was validated by the model built from the training set with 17 polychlorinated dibenzothiophenes.展开更多
Overwhelming water-deficiency conditions and an unbalanced water supply and demand have been major concerns of both the Chinese government and the general public during recent decades. Studying the spatial-temporal pa...Overwhelming water-deficiency conditions and an unbalanced water supply and demand have been major concerns of both the Chinese government and the general public during recent decades. Studying the spatial-temporal patterns and impact factors that influence water retention in China is important to enhance the management of water resources in China and other similar countries. We employed a revised Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST) model and regression analyses to investigate the water retention service in China. The results showed that the southeastern China generally performed much better than Northwest China in terms of the spatial distribution of water retention. In general, the efficacy of the water retention service in China increased from 2000 to 2014; although some areas still had a downward trend. Water retention service increased significantly(P < 0.05) in aggregate in the Qinghai-Tibet Plateau, and the Da Hinggan Mountains and Xiao Hinggan Mountains. However, the service in southwestern China showed a decreasing trend(P < 0.05), which would have significant negative impact on the downstream population. This study also showed that in China the changes in water retention service were primarily due to climate change(which could explain 83.49% of the total variance), with anthropogenic impact as a secondary influence(likewise the ecological programs and socioeconomic development could explain 9.47% and 1.06%, respectively). Moreover, the identification of water retention importance indicated that important areas conservation and selection based on downstream beneficiaries is vital for optimization protection of ecosystem services, and has practical significance for natural resources and ecosystem management.展开更多
Periprosthetic joint infection(PJI) is a devastating complication after total joint arthroplasty, occurring in approximately 1%-2% of all cases. With growing populations and increasing age, PJI will have a growing eff...Periprosthetic joint infection(PJI) is a devastating complication after total joint arthroplasty, occurring in approximately 1%-2% of all cases. With growing populations and increasing age, PJI will have a growing effect on health care costs. Many risk factors have been identified that increase the risk of developing PJI, including obesity, immune system deficiencies, malignancy, previous surgery of the same joint and longer operating time. Acute PJI occurs either postoperatively(4 wk to 3 mo after initial arthroplasty, depending on the classification system), or via hematogenous spreading after a period in which the prosthesis had functioned properly. Diagnosis and the choice of treatment are the cornerstones to success. Although different definitions for PJI have been used in the past, most are more or less similar and include the presence of a sinus tract, blood infection values, synovial white blood cell count, signs of infection on histopathological analysis and one ormore positive culture results. Debridement, antibiotics and implant retention(DAIR) is the primary treatment for acute PJI, and should be performed as soon as possible after the development of symptoms. Success rates differ, but most studies report success rates of around 60%-80%. Whether single or multiple debridement procedures are more successful remains unclear. The use of local antibiotics in addition to the administration of systemic antibiotic agents is also subject to debate, and its pro's and con's should be carefully considered. Systemic treatment, based on culture results, is of importance for all PJI treatments. Additionally, rifampin should be given in Staphylococcal PJIs, unless all foreign material is removed. The most important factors contributing to treatment failure are longer duration of symptoms, a longer time after initial arthroplasty, the need for more debridement procedures, the retention of exchangeable components, and PJI caused by Staphylococcus(aureus or coagulase negative). If DAIR treatment is unsuccessful, the following treatment option should be based on the patient health status and his or her expectations. For the best functional outcome, one- or two-stage revision should be performed after DAIR failure. In conclusion, DAIR is the obvious choice for treatment of acute PJI, with good success rates in selected patients.展开更多
The soil moisture retention capability of Chao soil and coastal saline Chao soil in Shandong and Zhejiang provinces were measured by pressure membrane method. The main factors influencing soil moisture retention capab...The soil moisture retention capability of Chao soil and coastal saline Chao soil in Shandong and Zhejiang provinces were measured by pressure membrane method. The main factors influencing soil moisture retention capability were studied by the methods of correlation and path analyses. The results indicated that < 0.02mm physical clay and soil salt content were the main factors influencing soil moisture retention capability. At soil suction of 30-50 kpa, the soil salt content would be the dominant factor.展开更多
Video capsule endoscopy (VCE) is a safe innovative tool for investigating obscure gastrointestinal bleeding, Crohn's disease and other small bowel pathologies. The capsule is usually excreted with faeces within 24...Video capsule endoscopy (VCE) is a safe innovative tool for investigating obscure gastrointestinal bleeding, Crohn's disease and other small bowel pathologies. The capsule is usually excreted with faeces within 24-48 h. Retention of capsule rarely occurs, and it usually depends on the indication of VCE. The longest reported case of capsule retention in the literature is 2.5 years. Surgical approach is considered effective to retrieve the retained capsule. We present a case of asymptomatic retention of capsule for four and half years in a 49-year-old man who underwent VCE to explore the cause of obscure gastrointestinal bleeding. It was successfully retrieved endoscopically. We will also briefly review the literature regarding the causes, different presentations and management of capsule retention.展开更多
Periprosthetic joint infections(PJI) of the hip and the knee are grossly classified as early post-operative, acute hematogenous and late chronic infections. Whereas two-stage exchange arthroplasty is the standard of c...Periprosthetic joint infections(PJI) of the hip and the knee are grossly classified as early post-operative, acute hematogenous and late chronic infections. Whereas two-stage exchange arthroplasty is the standard of care in North America for treating chronic infections, irrigation and debridement(I and D) with retention of implants has been used in an attempt to treat the other two types of PJIs. The rationale of this approach is that a PJI may be eradicated without the need of explanting the prostheses, as long as it has not transitioned into a chronic state. With the present paper, we review current evidence regarding the role of I and D with implant retention for treating PJIs of the hip and the knee. While a very wide range of success rates is reported in different studies, a short period of time between initiation of symptoms and intervention seems to play a prominent role with regards to a successful outcome. Moreover, pathogens of higher virulence and resistance to antibiotics are associated with a poorer result. Specific comorbidities have been also correlated with a less favorable outcome. Finally, one should proceed with serial I and Ds only under the condition that a predefined,aggressive protocol is applied. In conclusion,when treating a PJI of the hip or the knee, all the above factors should be considered in order to decide whether the patient is likely to benefit from this approach.展开更多
The effect of hydraulic retention time (HRT) and pH on the biooxidation of ferrous iron during simulated acid mine drainage (AMD) treatment was investigated.The simulated AMD was highly acidic (pH 2.5), rich in iron (...The effect of hydraulic retention time (HRT) and pH on the biooxidation of ferrous iron during simulated acid mine drainage (AMD) treatment was investigated.The simulated AMD was highly acidic (pH 2.5), rich in iron (about 1700 mg/L) and copper (about 200 mg/L), and contained high concentrations of sulfate (about 4700 mg/L).The biooxidation of ferrous iron was studied in a laboratory-scale upflow packed bed bioreactor (PBR).The HRT was shortened stepwise from 40 h to 20 h, 13 h, and 8 h under the acidic environment at a pH value of 2.2.Then, the influent pH value was changed from 2.2 to 1.2 at a constant suitable HRT.Physiochemical and microbial community structure analyses were performed on water samples and stuffing collected from the bioreactor under different conditions.The results indicate that the efficiency of ferrous iron oxidation gradually decreased with the decrease of HRT, and when the HRT exceeded 13 h, ferrous iron in AMD was almost completely oxidized.In addition, the best efficiency of ferrous iron oxidation was achieved at the influent pH value of 1.8.Microbial community structure analyses show that Leptospirillum is the predominant genus attached in the bioreactor, and low influent pH values are suitable for the growth of Leptospirillum.展开更多
Based on six thermodynamic equilibria,a unified retention model of solute in liquidchromatography(LC)is first proposed.The unified model was tested and proved to be valid for a LC sys-tem with mobile phase consisting ...Based on six thermodynamic equilibria,a unified retention model of solute in liquidchromatography(LC)is first proposed.The unified model was tested and proved to be valid for a LC sys-tem with mobile phase consisting of a complete range of multiple,ternary or binary components and eachkind of LC except size exclusion chromatography.In addition,so long as making some assumptions andmathematical conversions,the expressions of various popular models in LC can be derived by using theunified model.展开更多
To ascertain the effects of long-term conservation tillage and residue retention on soil organic carbon(SOC) content and aggregate distribution in a deep soil(>20-cm depth) in a dryland environment,this paper analy...To ascertain the effects of long-term conservation tillage and residue retention on soil organic carbon(SOC) content and aggregate distribution in a deep soil(>20-cm depth) in a dryland environment,this paper analyzed the SOC and aggregate distribution in soil, and the aggregate-associated organic carbon(OC) and SOC physical fractions. Conservation tillage(reduced tillage with residue incorporated(RT) and no-tillage with residue mulch(NT)) significantly increased SOC sequestration and soil aggregation in deep soil compared with conventional tillage with residue removal(CT). Compared with CT, RT significantly increased the proportion of small macroaggregates by 23%–81% in the 10–80 cm layer, and the OC content in small macroaggregates by 1%–58% in the 0–80 cm layer. RT significantly increased(by 24%–90%) the OC content in mineral-SOC within small macroaggregates in the 0–60 cm layer, while there was a 23%–80% increase in the 0–40 cm layer with NT. These results indicated that:(1) conservation tillage treatments are beneficial for soil aggregation and SOC sequestration in a deep soil in a dryland environment; and(2)the SOC in mineral-associated OC plays important roles in soil aggregation and SOC sequestration. In conclusion, RT with NT is recommended as an agricultural management tool in dryland soils because of its role in improving soil aggregation and SOC sequestration.展开更多
Halogenated methyl-phenyl ethers (anisoles) are ubiquitous organic compounds in the environment. In the present study, geometrical optimization and electrostatic potential calcu- lations have been performed for 42 hal...Halogenated methyl-phenyl ethers (anisoles) are ubiquitous organic compounds in the environment. In the present study, geometrical optimization and electrostatic potential calcu- lations have been performed for 42 halogenated anisoles at the HF/6-31G* level. A number of sta- tistically based parameters have been obtained. By multiple regression method, linear relationships between the gas-chromatographic relative retention time (RRT) and structural descriptors have been established for the training set of 32 halogenated anisoles. The result showed that the parameters derived from electrostatic potentials (ESPs) together with the molecular volume (Vmc) could be well used to express the quantitative structure-RRT relationships of halogenated anisoles. The best two-variable regression model gives a correlation coefficient of 0.980 and a standard deviation of 0.07, and the leave-one-out cross-validated correlation coefficient is 0.975. The goodness of the model has been further validated through exploring the predictive power for the testing set of 10 halogenated anisoles.展开更多
文摘The purpose of this study was to evaluate the effects of retention ponds on the environment and population health by analyzing water samples from various ponds in Mogadishu, to determine the prevalence of waterborne illnesses that occur during the rainy season in Mogadishu, and to find out what experts thought about the effects of retention ponds on the environment as well as population health in Mogadishu. Methods: Mixed designs were used in the study. The first design is an exploratory study where samples are taken from different retention ponds in Mogadishu. The second design involves gathering secondary data from the online FSNAU Dashboard regarding the incidence of rainfall and waterborne illnesses including malaria and cholera. Additionally, a cross-sectional survey of expert opinions using questionnaires was the third design. The 10 water samples were taken from retention ponds in Mogadishu as part of the sample size. Data on the fourth month was also gathered using the FNSAU dashboard, and seventy sample sizes were used for the expert self-administered questionnaire for the third design. Excel was used for data analysis in the initial design. While BMI SPSS versions 22 were used to analyze the data from the Self-administered Questionnaire, additional methods were utilized to compute descriptive statistics, such as mean and standard deviation, and to analyze demographic data in a frequency table. Findings: The results show that three samples had unsatisfactory scores (Grade D): Yaqshid (Warshadda Bastada) had a WQI of 80.85, Boondheer (Bondher Pond) had a WQI of 80.64, and Wartanabad (Xamar Jadiid Pond) had a WQI of 80.89. The remaining samples were all rated as fair (grade), which indicates that they ranged from 50 to 75. The months with the largest rainfall already occurred in December, November, and October, when the prevalence of diseases during the rainy season was highest for cholera cases. Although October and December saw a significant number of malaria cases, November did not. Retention ponds’ overall effects on residential environments were evaluated, and the results showed that the standard deviation was 0.802 and the cumulative average mean scores were 4.41 overall. This indicates that the respondents were in agreement that retention ponds in Mogadishu, Somalia, had an effect on residential areas. Recommendation: The study suggested that in order to identify retention pond contamination and create treatment units for its management, the Ministry of Health forms a district-level public health committee. All districts must have a sewer system installed by the local government, and retention ponds must be made easier in order to move waste outside of the city.
文摘Purpose: High urinary retention (HUR) can negatively impact renal function. Our study aimed to present the epidemiological, diagnostic, and therapeutic aspects of HUR in a Senegalese academic hospital. Patients and Methods: We conducted a retrospective study of 70 patients with HUR associated with renal failure from January 2017 to December 2020. Parameters examined included: age, sex, coexisting conditions affecting renal function, clinical symptoms, diagnostic tests, causes of HUR, urinary diversion, and patient outcomes. Results: The average age was 66, with a majority of male patients (87%). Twenty-three patients had pre-existing medical conditions. Oligo-anuria was the most common reason for detecting HUR (70%). Half of the patients had an ECOG score ≥ 2. The mean creatinine level was 50.7 mg/l. Nineteen patients exhibited hydroelectrolytic disorders. Bacterial colonization was observed in 25 patients. Ultrasound and computed tomography were the most frequently performed imaging tests (100% and 62.8%, respectively). Sixty-seven patients had ureterohydronephrosis (UHN), with bilateral UHN in 88.6% of cases. Pelvic cancers (47.1%) were the primary cause of HUR, primarily bladder cancers (27.1%). Nephrostomy was the most common urinary drainage method (50%), particularly for obstructions due to pelvic cancer (88.6%). The majority of patients (52.8%) regained normal renal function after drainage. Nineteen deaths occurred among elderly patients with compromised general health. Conclusion: Urinary drainage significantly improved renal function for most patients. Pelvic cancer emerged as the leading cause of HUR. Nephrostomy was the predominant drainage method.
基金the support from the Scientific Research Project from RIPED(2021ycq01)the Scientific Research and Technological Development Project of CNPC(2021DJ0107)the Basic Research and Strategic Reserve Technology Research Project of CNPC(2020D-5008-01)。
文摘In this study,organic geochemical and petrological analyses were conducted on 111 shale samples from a well to understand the retention,intraformational migration and segmented accumulation(shale oil enrichment in different intervals is unconnected)features of shale oil within the organic-rich shale in the Qingshankou Formation of the Gulong Sag.Our study shows that retained petroleum characteristics in the investigated succession are mainly influenced by three factors:organic richness,intraformational migration and segmented accumulation.Organic matter richness primarily controls the amount of retained petroleum,especially the‘live’component indicated by the S_(2)value rather than the total organic carbon(TOC)figure alone.The negative expulsion efficiencies determined by mass-balance calculations of hydrocarbons reveal that petroleum from adjacent organic-rich intervals migrates into the interval of about 2386-2408 m,which is characterized by high free hydrocarbon(S_(1)),OSI and saturated hydrocarbons content,along with a greater difference inδ^(13)C values between polar compounds(including resins and asphaltenes)and saturated hydrocarbons.The depth-dependent heterogeneity of carbon isotope ratios(δ^(13)C)of mud methane gas,δ^(13)C of extracts gross composition(SARA),δ^(13)C of kerogen and SARA content of extracts suggest that the studied succession can be subdivided into four intervals.The shale oil sealing enrichment character in each interval is further corroborated by the distinctδ^(13)C values of mud methane gas in different intervals.Due to the migration of petroleum into the 2386-2408 m interval,the S_(1),OSI and saturated hydrocarbons content of the interval show higher relative values.The maturity of organic matter in the 2471-2500 m interval is at the highest with the smaller size molecular components of the retained petroleum.Thus,favorable‘sweet spots’may be found in the 2386-2408 m interval and the 2471-2500 m interval,according to the experiment results in this study.
基金supported by a grant from the Double Thousand Plan of Jiangxi Province(No.jxsq2019101057)the National Natural Science Foundation of China(No.3196150349)to Haihui Fu and Xu Jie,respectively.
文摘OsPLS4 encodes aβ-ketoacyl carrier protein reductase(KAR).The role of OsPLS4 in rice sheath blight(Rhizoctonia solani)remains unclear.Our preliminary studies showed that premature leaf senescence mutants(pls4)were highly susceptive to sheath blight in the early stage of rice development.To explore the role of this gene in the development of rice sheath blight,the transcriptome profiles of the rice pls4 mutant and wild type were compared by RNA-seq.The results revealed 2,569 differentially expressed genes(DEGs).The down-regulated genes were significantly enriched in the defense response-related biological processes.These down-regulated genes included the chitinase genes and WRKY genes,which were significantly changed in pls4 mutants.Furthermore,467 genes induced significant alternative splicing(AS)events.Among them,intron retention(IR)affected gene expression levels and functions of the vitamin B6(VB6)metabolism pathway related to sheath blight.This result suggests that IR plays an important role in the sheath blight resistance of mutant pls4.Together,these results indicate that pls4 could be involved in the biological process of sheath blight via DEGs and the fine-tuning of IR.The present study provides a molecular basis for further investigation of the resistance of rice to sheath blight.
文摘The persistent challenges in attracting and retaining a diverse healthcare workforce, with a specific focus on nurses, have become increasingly pronounced in recent years. These hurdles have been exacerbated by a growing difficulty in retaining young nurses, thereby exacerbating labor shortages driven by demographic shifts and the retirement of experienced nursing professionals. While most research efforts have concentrated on the broader issue of nurse retention, our study is centered on a specific demographic—young nurses. Our research endeavors to shed light on the unique challenges faced by young nurses through a qualitative survey involving nursing students who are simultaneously employed. We seek to discern the multifaceted obstacles they encounter in both their academic environment and the healthcare organizations where they work. While certain challenges are linked to course organization, examinations, and the time required for studying, our respondents overwhelmingly emphasize the pivotal role of the work environment in facilitating the harmonization of work, family, and educational commitments. This reconciliation is achieved through measures such as flexible working arrangements and the efficient organization of nursing duties. The primary objective of our research is to provide insights into how these diverse challenges can be effectively addressed and how a range of measures can significantly contribute to the attraction and retention of nursing students, as well as the long-term retention of nurses within the healthcare system. Our recommendations are intended to be of practical use to a wide array of stakeholders, including academic institutions, particularly colleges and universities offering nursing programs, as well as hospitals, clinics, and other healthcare institutions that hire nurses. By collaboratively addressing these challenges and implementing the recommended measures, we aim to fortify the healthcare workforce and ensure the continued provision of quality care to patients. .
文摘This article has been directed to Environment Protection Technology with the purpose of providing a new instrument designed and developed to measure filtration efficiency through the relationship between clean cloth fabric structural parameters, dust parameters, and test measuring variables. Fabric samples used throughout the present study were woven cotton 100%, polyester 100% and cotton/polyester 50/50%. The warp count: 30/2 for all fabric samples, the weft count is 9/1;12/1;and 20/1. The weave of satin, basket, and twill is 3/1 with four different picks/cm to produce the fabrics with the same cover factor. For dust separation fabrics range in weight from “300 - 450 g/m<sup>2</sup>” with an air permeability of “100 - 300 l/d m<sup>2</sup>·min” at “196.2 Pa” (20 mm WG) as specified in DIN 53887. Air permeability through fabrics depends entirely on the sieving percent of the surface of the fabric, which is partly the pores and partly the permeability through the yarns, which are the basic elements of a fabric. The results showed that dust capturing depends entirely on air permeability, which is related to fabric weave structure and fabric material at specified testing and measuring variables.
文摘It is well known that air in industrial cities contains a significant amount of dust particles, smoke, and toxic gases. The increased number of vehicles has a direct impact on air quality resulting in the emission of exhaust gases, and the increase of dust concentration in air. In this article, we are describing the dust retention ability of plants depending on their leaf structure. Plant species were classified into three groups according to their dust-holding capacities. Dust retaining ability of plant species in conditions of high, average and low dust conditions described.
基金the Joint Fire Science Program(JFSP),The Ohio State University,Seney National Wildlife Refuge(SNWR)Seney Natural History Association.
文摘Background:Many fire-dependent forests have experienced significant declines in species,structural,and functional diversity.These changes are attributed in part to traditional management approaches that were dominated by even-aged regeneration methods such as clearcutting.Variable retention harvesting(VRH)is an ecologically based forestry practice that involves retention of some mature overstory trees and other biological structures in the postharvest stand to emulate the effects of natural disturbance events.In this study,we examined the effect of a VRH treatment on recruitment of historically dominant pine species and understory vegetation twoand six years after its implementation in a naturally regenerated mixed pine forest in the Upper Peninsula of Michigan,USA.Results:We found greater regeneration of red pine(Pinus resinosa L.)and eastern white pine(Pinus strobus L.)in VRH stands compared to the unharvested controls.Although red pine recruitment was very low during the first 2 years,both species increased significantly from year two to year six.Recruitment responses for the two species did not differ significantly between the aggregated and dispersed retention treatments.We also found high recruitment of deciduous tree species,consisting primarily of sprouts,and red pine exhibited a negative correlation with these sprouts.Treatment,time,and the interaction of treatment and time were significant factors in red pine recruitment.Time had a strong effect on the understory vegetation,with significant decreases in shrubs and ferns over time.Conclusions:The results suggest that VRH enhanced recruitment of red pine and eastern white pine and that this recruitment increased with time.We identify competition from sprouts and unfavorable seedbed conditions as the main factors that limited recruitment of red pine during the first 2 years.To reduce competing vegetation and improve seedbed conditions,we suggest following the VRH with a prescribed fire,mechanically removing sprouts,and implementing herbicide treatments.At a time when changes in global climate exacerbates the effects of traditional drivers of forest degradation,and with the need to maintain biodiversity,new ecologically based forest practices such VRH have the potential to facilitate regeneration of native trees and enhance the resilience of many fire-dependent forests.
文摘The purpose of the paper is to study retention of vocabulary acquired incidentally on task-induced involvement by senior middle school students. Grade two of senior middle students participated in the experiments, testing whether retention of vocabulary acquired incidentally is contingent on amount of task-induced involvement.Using short-and long term, namely immediate posttest and delayed posttest, retention of twelve unfamiliar words was investigated in three learning tasks (reading, reading plus fill-in and writing) with varying degrees of “involvement load”- various combinations of need, search and evaluation. The results of the experiment partially support the Involvement Load Hypothesis: retention in the writing group was higher than that in the reading plus fill-in group; retention in the reading plus fill-in group was higher than that in the reading group. The results are discussed in light of the construct of task-induced involvement.
基金This study was financially supported by the National Key R&D Program of China(2018YFC1704100 and 2018YFC1704101)Beijing Municipal Natural Science Foundation(7172131).
文摘Objective:Gastrointestinal heat retention syndrome(GHRS)is associated with lung-heat syndrome and is related to recurrent respiratory infection.Upper respiratory tract infection(URTI)lung heat syndrome is common in children.The study will explore the effect of GHRS on the structure and function of gut microbiota in children with URTI lung-heat syndrome.Methods:Participants were divided into both groups using the self-developed URTI scale and the“GHRS Diagnostic Scale$Pediatric Part”:GHRS-positive children(LS group)and GHRS-negative children(L group).General information,clinical symptoms,and stool were collected.We used 16S rRNA amplicon sequencing technology to determine the gene sequence of the V3eV4 region in feces and measure the gut microbiota of the both groups at the genus level.Results:A total of 23 children were included in the both groups.There were 12 cases in the LS group and 11 cases in the L group.There was no statistical difference between the both groups in age,gender,height,weight,and body mass index.The effective sequences shared by the both groups accounted for 85.66%of the total.In the gut microbiota,there was no difference in the a diversity and the b diversity between the both groups.Compared with the L group,the LS group had a significant increase in the relative abundance of the Ruminococcus gnavus group,Prevotella-9,Staphylococcus,and Actinomyces(P<.05).The functions of the both groups of microbiota primarily concentrate on metabolism,genetic information processing,and environmental information processing.The relative abundance of signaling molecules and interactions in the LS group were higher than that in the L group(P<.05).The redundancy analysis(RDA)showed that the URTI score had the greatest impact on the distribution of microbiota.Conclusion:GHRS may affect the development of URTI lung-heat syndrome by changing the relative abundances of gut microbiota.
基金Sponsored by the NSF of Guangxi Province (No. 2011XNSFA018059)Guangxi Key Laboratory Research Fund of Environmental Engineering and Protection Assessment (No. 0801Z026)+1 种基金Major Science of Water Pollution Control and Management (No. 2008ZX07317-02)the Guangxi Zhuang Autonomous Region Department of Education Research (No. 201010LX174) Funding
文摘Polychlorinated dibenzothiophenes(PCDTs) are a group of important persistent organic pollutants.In the present study,geometrical optimization and electrostatic potential calculations have been performed for all 135 PCDTs congeners at the B3LYP/6-31G* level of theory.By means of the VSMP(variable selection and modeling based on prediction) program,one optimal descriptor(molecular polarizability,α) was selected to develop a QSRR model for the prediction of gas chromatographic retention indices(GC-RI) of PCDTs.The estimated correlation coefficients(r2) and LOO-validated correlation coefficients(q2),all more than 0.99,were built by multiple linear regression,which shows a good estimation ability and stability of the models.A prediction power for the external samples was validated by the model built from the training set with 17 polychlorinated dibenzothiophenes.
基金National Key Technology Research and Development Program of China(No.2011BAC09B08)Special Issue of National Remote Sensing Survey and Assessment of Eco-Environment Change between 2000 and 2010(No.STSN-04-01)
文摘Overwhelming water-deficiency conditions and an unbalanced water supply and demand have been major concerns of both the Chinese government and the general public during recent decades. Studying the spatial-temporal patterns and impact factors that influence water retention in China is important to enhance the management of water resources in China and other similar countries. We employed a revised Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST) model and regression analyses to investigate the water retention service in China. The results showed that the southeastern China generally performed much better than Northwest China in terms of the spatial distribution of water retention. In general, the efficacy of the water retention service in China increased from 2000 to 2014; although some areas still had a downward trend. Water retention service increased significantly(P < 0.05) in aggregate in the Qinghai-Tibet Plateau, and the Da Hinggan Mountains and Xiao Hinggan Mountains. However, the service in southwestern China showed a decreasing trend(P < 0.05), which would have significant negative impact on the downstream population. This study also showed that in China the changes in water retention service were primarily due to climate change(which could explain 83.49% of the total variance), with anthropogenic impact as a secondary influence(likewise the ecological programs and socioeconomic development could explain 9.47% and 1.06%, respectively). Moreover, the identification of water retention importance indicated that important areas conservation and selection based on downstream beneficiaries is vital for optimization protection of ecosystem services, and has practical significance for natural resources and ecosystem management.
文摘Periprosthetic joint infection(PJI) is a devastating complication after total joint arthroplasty, occurring in approximately 1%-2% of all cases. With growing populations and increasing age, PJI will have a growing effect on health care costs. Many risk factors have been identified that increase the risk of developing PJI, including obesity, immune system deficiencies, malignancy, previous surgery of the same joint and longer operating time. Acute PJI occurs either postoperatively(4 wk to 3 mo after initial arthroplasty, depending on the classification system), or via hematogenous spreading after a period in which the prosthesis had functioned properly. Diagnosis and the choice of treatment are the cornerstones to success. Although different definitions for PJI have been used in the past, most are more or less similar and include the presence of a sinus tract, blood infection values, synovial white blood cell count, signs of infection on histopathological analysis and one ormore positive culture results. Debridement, antibiotics and implant retention(DAIR) is the primary treatment for acute PJI, and should be performed as soon as possible after the development of symptoms. Success rates differ, but most studies report success rates of around 60%-80%. Whether single or multiple debridement procedures are more successful remains unclear. The use of local antibiotics in addition to the administration of systemic antibiotic agents is also subject to debate, and its pro's and con's should be carefully considered. Systemic treatment, based on culture results, is of importance for all PJI treatments. Additionally, rifampin should be given in Staphylococcal PJIs, unless all foreign material is removed. The most important factors contributing to treatment failure are longer duration of symptoms, a longer time after initial arthroplasty, the need for more debridement procedures, the retention of exchangeable components, and PJI caused by Staphylococcus(aureus or coagulase negative). If DAIR treatment is unsuccessful, the following treatment option should be based on the patient health status and his or her expectations. For the best functional outcome, one- or two-stage revision should be performed after DAIR failure. In conclusion, DAIR is the obvious choice for treatment of acute PJI, with good success rates in selected patients.
文摘The soil moisture retention capability of Chao soil and coastal saline Chao soil in Shandong and Zhejiang provinces were measured by pressure membrane method. The main factors influencing soil moisture retention capability were studied by the methods of correlation and path analyses. The results indicated that < 0.02mm physical clay and soil salt content were the main factors influencing soil moisture retention capability. At soil suction of 30-50 kpa, the soil salt content would be the dominant factor.
文摘Video capsule endoscopy (VCE) is a safe innovative tool for investigating obscure gastrointestinal bleeding, Crohn's disease and other small bowel pathologies. The capsule is usually excreted with faeces within 24-48 h. Retention of capsule rarely occurs, and it usually depends on the indication of VCE. The longest reported case of capsule retention in the literature is 2.5 years. Surgical approach is considered effective to retrieve the retained capsule. We present a case of asymptomatic retention of capsule for four and half years in a 49-year-old man who underwent VCE to explore the cause of obscure gastrointestinal bleeding. It was successfully retrieved endoscopically. We will also briefly review the literature regarding the causes, different presentations and management of capsule retention.
文摘Periprosthetic joint infections(PJI) of the hip and the knee are grossly classified as early post-operative, acute hematogenous and late chronic infections. Whereas two-stage exchange arthroplasty is the standard of care in North America for treating chronic infections, irrigation and debridement(I and D) with retention of implants has been used in an attempt to treat the other two types of PJIs. The rationale of this approach is that a PJI may be eradicated without the need of explanting the prostheses, as long as it has not transitioned into a chronic state. With the present paper, we review current evidence regarding the role of I and D with implant retention for treating PJIs of the hip and the knee. While a very wide range of success rates is reported in different studies, a short period of time between initiation of symptoms and intervention seems to play a prominent role with regards to a successful outcome. Moreover, pathogens of higher virulence and resistance to antibiotics are associated with a poorer result. Specific comorbidities have been also correlated with a less favorable outcome. Finally, one should proceed with serial I and Ds only under the condition that a predefined,aggressive protocol is applied. In conclusion,when treating a PJI of the hip or the knee, all the above factors should be considered in order to decide whether the patient is likely to benefit from this approach.
基金supported by the National Natural Science Foundation of China(Grant No.U1402234)the Guangxi Scientific Research and Technology Development Plan(Grants No.GuikeAB16380287 and GuikeAB17129025)+2 种基金the Public Welfare Fund of the Ministry of Environmental Protection of China(Grant No.201509049)the Program of International S & T Cooperation(Grant No.2016YFE0130700)the Fund of the General Research Institute for Nonferrous Metals(Grants No.53321 and 53348)
文摘The effect of hydraulic retention time (HRT) and pH on the biooxidation of ferrous iron during simulated acid mine drainage (AMD) treatment was investigated.The simulated AMD was highly acidic (pH 2.5), rich in iron (about 1700 mg/L) and copper (about 200 mg/L), and contained high concentrations of sulfate (about 4700 mg/L).The biooxidation of ferrous iron was studied in a laboratory-scale upflow packed bed bioreactor (PBR).The HRT was shortened stepwise from 40 h to 20 h, 13 h, and 8 h under the acidic environment at a pH value of 2.2.Then, the influent pH value was changed from 2.2 to 1.2 at a constant suitable HRT.Physiochemical and microbial community structure analyses were performed on water samples and stuffing collected from the bioreactor under different conditions.The results indicate that the efficiency of ferrous iron oxidation gradually decreased with the decrease of HRT, and when the HRT exceeded 13 h, ferrous iron in AMD was almost completely oxidized.In addition, the best efficiency of ferrous iron oxidation was achieved at the influent pH value of 1.8.Microbial community structure analyses show that Leptospirillum is the predominant genus attached in the bioreactor, and low influent pH values are suitable for the growth of Leptospirillum.
基金This work was supported by the Excellent Young Faculty Foundation of the State Education Committee of China
文摘Based on six thermodynamic equilibria,a unified retention model of solute in liquidchromatography(LC)is first proposed.The unified model was tested and proved to be valid for a LC sys-tem with mobile phase consisting of a complete range of multiple,ternary or binary components and eachkind of LC except size exclusion chromatography.In addition,so long as making some assumptions andmathematical conversions,the expressions of various popular models in LC can be derived by using theunified model.
基金supported jointly by the National Key Research and Development Program of China (2018YFD0200408, 2016YFD0300804)the Science and Technology Project (2015BAD22B03)the Basic Scientific Research Business Expenses of the Chinese Academy of Agricultural Sciences (1610132018024)
文摘To ascertain the effects of long-term conservation tillage and residue retention on soil organic carbon(SOC) content and aggregate distribution in a deep soil(>20-cm depth) in a dryland environment,this paper analyzed the SOC and aggregate distribution in soil, and the aggregate-associated organic carbon(OC) and SOC physical fractions. Conservation tillage(reduced tillage with residue incorporated(RT) and no-tillage with residue mulch(NT)) significantly increased SOC sequestration and soil aggregation in deep soil compared with conventional tillage with residue removal(CT). Compared with CT, RT significantly increased the proportion of small macroaggregates by 23%–81% in the 10–80 cm layer, and the OC content in small macroaggregates by 1%–58% in the 0–80 cm layer. RT significantly increased(by 24%–90%) the OC content in mineral-SOC within small macroaggregates in the 0–60 cm layer, while there was a 23%–80% increase in the 0–40 cm layer with NT. These results indicated that:(1) conservation tillage treatments are beneficial for soil aggregation and SOC sequestration in a deep soil in a dryland environment; and(2)the SOC in mineral-associated OC plays important roles in soil aggregation and SOC sequestration. In conclusion, RT with NT is recommended as an agricultural management tool in dryland soils because of its role in improving soil aggregation and SOC sequestration.
基金This work was supported by the National Natural Science Foundation of China (No. 20502022) and the Ph.D. Fund of Ningbo ( No. 2004A610010)
文摘Halogenated methyl-phenyl ethers (anisoles) are ubiquitous organic compounds in the environment. In the present study, geometrical optimization and electrostatic potential calcu- lations have been performed for 42 halogenated anisoles at the HF/6-31G* level. A number of sta- tistically based parameters have been obtained. By multiple regression method, linear relationships between the gas-chromatographic relative retention time (RRT) and structural descriptors have been established for the training set of 32 halogenated anisoles. The result showed that the parameters derived from electrostatic potentials (ESPs) together with the molecular volume (Vmc) could be well used to express the quantitative structure-RRT relationships of halogenated anisoles. The best two-variable regression model gives a correlation coefficient of 0.980 and a standard deviation of 0.07, and the leave-one-out cross-validated correlation coefficient is 0.975. The goodness of the model has been further validated through exploring the predictive power for the testing set of 10 halogenated anisoles.
