Background: Retention in clinical trials is critical for the accumulation of data over time and retaining enough power for comprehensive analysis. We document for the first time the retention rates and factors associa...Background: Retention in clinical trials is critical for the accumulation of data over time and retaining enough power for comprehensive analysis. We document for the first time the retention rates and factors associated with retention among a cohort of HIV exposed seronegative (HESN) person in a discordant relationship. Understanding these factors will provide valuable cues for maintaining high retention rates in future HIV biomedical prevention studies in this cohort. Aim: We aimed to document retention rates and associated factors relevant in conducting future HIV prevention studies using a cohort of HIV exposed sero-negative individuals. Method: We conducted a prospective cohort study to enroll HESN persons in discordant relationship based on established inclusion criteria that includes: Established sero-discordance with at least 3 months in the relationship;above 18 years and willingness to be followed up. Relevant ethical approvals were obtained. Following informed consent at enrollment, standardized questionnaires on risk behavior and factors that may affect retention were administered at enrollment and during the 2 years follow-up. This was spread over 10 follow-up visits to mimic phase a 2b HIV vaccine clinical trial follow up and duration. In addition, clinical examinations were done and samples collected for safety lab during the follow up visits. Estimation of CD4 and viral load was also done for the HIV+ partners of HESN study participants. Results: Six hundred and sixty HESN persons were screened and 534 (81%) enrolled (i.e. month 0) and followed up. There was a decline in retention from 96% at month 1 (visit 1) to 78% at month 24 (Visit 10). Sharpest drop out from the study occurred at month 1 (20%) and month 15 (14%) follow-up visits. Inability to reach study participants, unwillingness of study participants to continue study, and mortality of the HIV+ partners of HESN participants were the commonest reasons for participant study termination. Furthermore, no or low level of formal education, (AOR 2.79;95% CI 1.29 - 6.02, p = 0.06), being unemployed (AOR 1.96;95% CI 1.18 - 3.29, p < 0.01) and inconsistent use of condoms (AOR 1.83;95% CI 1.16 - 2.91, p Conclusion: Retention rates decline especially during month 1 (visit 1) and month 15 (visit 7) mainly due to participants’ inability to locate study participants and death of HIV+ partners of HESN enrollees. One unexpected finding from our study is that those who were more consistent in their use of condom were more likely to stay in the study. This is a possible indication of commitment or an incentive for giving free condoms at study visits. This is encouraging for combined biomedical prevention strategies where consistent condoms use is desired. On the other hand, factors such as unemployment, poor formal education and never/occasional condom use were predictors of study drop out. Retention strategies should consider these barriers and predictors of drop out as exclusion criteria in preparation for future HIV biomedical prevention trial.展开更多
Potential’s fluctuation of rust preventing oil film during its degradation was studied using wirebeam electrode. Being non-destructive and simple, potential measurement is a very repetitive method. Otherelectrochemic...Potential’s fluctuation of rust preventing oil film during its degradation was studied using wirebeam electrode. Being non-destructive and simple, potential measurement is a very repetitive method. Otherelectrochemical testing method, e. g., polarization resistance, can breakdown the integrity of oil coating byDC current; EIS is time consuming. As a special electrochemical sensor, wire beam electrode contains 101wires of mild steel wires, and it is helpful to improve the reproducibility of electrochemical test evidently.Using this electrode, the electrochemical parameters and their distribution which was related to under filmcorrosion process are measured directly so as to describe potential’s fluctuation of rust preventing oil film. Itis pointed out that there is potential’s fluctuation on rust preventing oil film during its degradation, and thischaracteristic has direct effect on the self-repairing ability of rust preventing oil film. However, for the uncoated metal electrode and base oil film, there is no such behavior. It is also pointed out that inhibitors in theoil film have direct effect on its self-repairing ability.展开更多
As one of the important categories of hot-rolled products, hot-rolled steel plates for automobile applications generally undergo uniform corrosion or localized corrosion according to different environments of manufact...As one of the important categories of hot-rolled products, hot-rolled steel plates for automobile applications generally undergo uniform corrosion or localized corrosion according to different environments of manufacturing, transportation and/or storage of the plates. General corrosion often takes place on the surface of a plate in the exterior part of a package, and only reduces the thickness of the plate and slightly increases the roughness of the surface; however, localized corrosion on the surface of a plate inside the package is likely to result in the formation of pit-like defects on the substrate of the plate, which cannot be removed thoroughly by normal acid pickling or sand blasting, and affects the application of the plate. This research report analyzes the phenomena and characteristics of the rusting behavior of hot- rolled steel plates for automobile applications, and the influencing factors are summaried. The corresponding preventative measures are proposed.展开更多
In recent decades, the demand for cold-rolled steel sheets has remarkably increased. To prevent the sheets from rusting before the manufacturing process, a layer of rust-preventive oil has to be coated on the sheets. ...In recent decades, the demand for cold-rolled steel sheets has remarkably increased. To prevent the sheets from rusting before the manufacturing process, a layer of rust-preventive oil has to be coated on the sheets. In this study, the shipment and storage environments were simulated through a salt spray test and a damp-heat experiment, respectively, and the packaging status of the sheets was imitated by a laminated sheet test. The protection effect of oil on the steel sheet was investigated under the different environmental conditions and oil weights by using electrochemical approaches, scanning electron microscopy （ SEM）, and X-ray diffraction （XRD） techniques. It was found that chloride ions had more severe effects on the corrosion resistance of the oils than hydrothermal conditions did. This was shown in the sheets with oil weights of 0.4,0.9 ,and 1.2 g · m^-2 ,which were too severely corroded after a four-hour salt spraying test to meet the demands of subsequent processing. However, the sheets showed satisfactory corrosion resistance after a three-week damp-heat experiment with a temperature of 49 ℃ and 95 % RH. In addition, it was disclosed that the penetration of the chloride ions determined the protection mechanism of the oil, i. e.,the corrosion resistance was initially enhanced by the increase in the oil content. As long as the chloride ion reached the interface between the oil film and the sheet, the oil distribution became the predominant factor in the protection of the sheet. The corrosion mechanism of the steel sheet was dependent on the stacking style of the sample. When exposed to air, the corrosion product of the sample was rust red with a composition of Fe2O3, whereas the black product that is mainly composed of Fe3O4 was found on the edge of the laminated sheets, which resulted from the oxygen concentration cell.展开更多
The aim of this paper is to highlight the current development in the research field for helping people just exposed to Ebola virus survive(treatment) and to prevent the disease when given at various times after exposu...The aim of this paper is to highlight the current development in the research field for helping people just exposed to Ebola virus survive(treatment) and to prevent the disease when given at various times after exposure(vaccine).Concerning the treatment,recombinant anti-Ebola monoclonal antibodies and small interfering RNAs that block the expression of essential viral proteins,are the most promising way in stopping the disease when it has already reached the humans.As far as concerns the prevention field,two candidate vaccines have clinical-grade vials available for phase 1 pre-licensure clinical trials,and demonstrated to have a 100%efficacy in studies on non human primates.Well-informed communities can reduce the main ways of spread the infection,by avoiding unprotected home-based care of people who are infected and also by completely modifying traditional burial practices that are way of diffusion of the contagion.展开更多
In recent years, pear rust sometimes occurs in eastern Hebei area, resulting in early defoliation, fruit abscission and loss of fruit commodity value. In this paper, the incidence symptoms, regularity and causes of pe...In recent years, pear rust sometimes occurs in eastern Hebei area, resulting in early defoliation, fruit abscission and loss of fruit commodity value. In this paper, the incidence symptoms, regularity and causes of pear rust are summarized, and the comprehensive prevention and control measures of pear rust in eastern Hebei are put forward.展开更多
文摘Background: Retention in clinical trials is critical for the accumulation of data over time and retaining enough power for comprehensive analysis. We document for the first time the retention rates and factors associated with retention among a cohort of HIV exposed seronegative (HESN) person in a discordant relationship. Understanding these factors will provide valuable cues for maintaining high retention rates in future HIV biomedical prevention studies in this cohort. Aim: We aimed to document retention rates and associated factors relevant in conducting future HIV prevention studies using a cohort of HIV exposed sero-negative individuals. Method: We conducted a prospective cohort study to enroll HESN persons in discordant relationship based on established inclusion criteria that includes: Established sero-discordance with at least 3 months in the relationship;above 18 years and willingness to be followed up. Relevant ethical approvals were obtained. Following informed consent at enrollment, standardized questionnaires on risk behavior and factors that may affect retention were administered at enrollment and during the 2 years follow-up. This was spread over 10 follow-up visits to mimic phase a 2b HIV vaccine clinical trial follow up and duration. In addition, clinical examinations were done and samples collected for safety lab during the follow up visits. Estimation of CD4 and viral load was also done for the HIV+ partners of HESN study participants. Results: Six hundred and sixty HESN persons were screened and 534 (81%) enrolled (i.e. month 0) and followed up. There was a decline in retention from 96% at month 1 (visit 1) to 78% at month 24 (Visit 10). Sharpest drop out from the study occurred at month 1 (20%) and month 15 (14%) follow-up visits. Inability to reach study participants, unwillingness of study participants to continue study, and mortality of the HIV+ partners of HESN participants were the commonest reasons for participant study termination. Furthermore, no or low level of formal education, (AOR 2.79;95% CI 1.29 - 6.02, p = 0.06), being unemployed (AOR 1.96;95% CI 1.18 - 3.29, p < 0.01) and inconsistent use of condoms (AOR 1.83;95% CI 1.16 - 2.91, p Conclusion: Retention rates decline especially during month 1 (visit 1) and month 15 (visit 7) mainly due to participants’ inability to locate study participants and death of HIV+ partners of HESN enrollees. One unexpected finding from our study is that those who were more consistent in their use of condom were more likely to stay in the study. This is a possible indication of commitment or an incentive for giving free condoms at study visits. This is encouraging for combined biomedical prevention strategies where consistent condoms use is desired. On the other hand, factors such as unemployment, poor formal education and never/occasional condom use were predictors of study drop out. Retention strategies should consider these barriers and predictors of drop out as exclusion criteria in preparation for future HIV biomedical prevention trial.
文摘Potential’s fluctuation of rust preventing oil film during its degradation was studied using wirebeam electrode. Being non-destructive and simple, potential measurement is a very repetitive method. Otherelectrochemical testing method, e. g., polarization resistance, can breakdown the integrity of oil coating byDC current; EIS is time consuming. As a special electrochemical sensor, wire beam electrode contains 101wires of mild steel wires, and it is helpful to improve the reproducibility of electrochemical test evidently.Using this electrode, the electrochemical parameters and their distribution which was related to under filmcorrosion process are measured directly so as to describe potential’s fluctuation of rust preventing oil film. Itis pointed out that there is potential’s fluctuation on rust preventing oil film during its degradation, and thischaracteristic has direct effect on the self-repairing ability of rust preventing oil film. However, for the uncoated metal electrode and base oil film, there is no such behavior. It is also pointed out that inhibitors in theoil film have direct effect on its self-repairing ability.
文摘As one of the important categories of hot-rolled products, hot-rolled steel plates for automobile applications generally undergo uniform corrosion or localized corrosion according to different environments of manufacturing, transportation and/or storage of the plates. General corrosion often takes place on the surface of a plate in the exterior part of a package, and only reduces the thickness of the plate and slightly increases the roughness of the surface; however, localized corrosion on the surface of a plate inside the package is likely to result in the formation of pit-like defects on the substrate of the plate, which cannot be removed thoroughly by normal acid pickling or sand blasting, and affects the application of the plate. This research report analyzes the phenomena and characteristics of the rusting behavior of hot- rolled steel plates for automobile applications, and the influencing factors are summaried. The corresponding preventative measures are proposed.
文摘In recent decades, the demand for cold-rolled steel sheets has remarkably increased. To prevent the sheets from rusting before the manufacturing process, a layer of rust-preventive oil has to be coated on the sheets. In this study, the shipment and storage environments were simulated through a salt spray test and a damp-heat experiment, respectively, and the packaging status of the sheets was imitated by a laminated sheet test. The protection effect of oil on the steel sheet was investigated under the different environmental conditions and oil weights by using electrochemical approaches, scanning electron microscopy （ SEM）, and X-ray diffraction （XRD） techniques. It was found that chloride ions had more severe effects on the corrosion resistance of the oils than hydrothermal conditions did. This was shown in the sheets with oil weights of 0.4,0.9 ,and 1.2 g · m^-2 ,which were too severely corroded after a four-hour salt spraying test to meet the demands of subsequent processing. However, the sheets showed satisfactory corrosion resistance after a three-week damp-heat experiment with a temperature of 49 ℃ and 95 % RH. In addition, it was disclosed that the penetration of the chloride ions determined the protection mechanism of the oil, i. e.,the corrosion resistance was initially enhanced by the increase in the oil content. As long as the chloride ion reached the interface between the oil film and the sheet, the oil distribution became the predominant factor in the protection of the sheet. The corrosion mechanism of the steel sheet was dependent on the stacking style of the sample. When exposed to air, the corrosion product of the sample was rust red with a composition of Fe2O3, whereas the black product that is mainly composed of Fe3O4 was found on the edge of the laminated sheets, which resulted from the oxygen concentration cell.
文摘The aim of this paper is to highlight the current development in the research field for helping people just exposed to Ebola virus survive(treatment) and to prevent the disease when given at various times after exposure(vaccine).Concerning the treatment,recombinant anti-Ebola monoclonal antibodies and small interfering RNAs that block the expression of essential viral proteins,are the most promising way in stopping the disease when it has already reached the humans.As far as concerns the prevention field,two candidate vaccines have clinical-grade vials available for phase 1 pre-licensure clinical trials,and demonstrated to have a 100%efficacy in studies on non human primates.Well-informed communities can reduce the main ways of spread the infection,by avoiding unprotected home-based care of people who are infected and also by completely modifying traditional burial practices that are way of diffusion of the contagion.
基金Supported by Key Research and Development Program of Hebei Province(21326308D-1-2)Innovation Project of Hebei Academy of Agriculture and Forestry Sciences(2019-3-4-4,2020-3-4-6)Innovation Team Project of Hebei Academy of Agriculture and Forestry Sciences(F21E06-7)。
文摘In recent years, pear rust sometimes occurs in eastern Hebei area, resulting in early defoliation, fruit abscission and loss of fruit commodity value. In this paper, the incidence symptoms, regularity and causes of pear rust are summarized, and the comprehensive prevention and control measures of pear rust in eastern Hebei are put forward.
