Direct Observation of Carrier Transportation Process in InGaAs/GaAs Multiple Quantum Wells Used for Solar Cells and Photodetectors

The resonant excitation is used to generate photo-excited carriers in quantum wells to observe the process of the carriers transportation by comparing the photoluminescence results between quantum wells with and without a p-n junction. It is observed directly in experiment that most of the photo-excited carriers in quantum wells with a p-n junction escape from quantum wells and form photoeurrent rather than relax to the ground state of the quantum wells. The photo absorption coei^cient of multiple quantum wells is also enhanced by a p-n junction. The results pave a novel way for solar cells and photodetectors making use of low-dimensional structure.

Direct observation of oxygen vacancy formation and migration over ceria surface by in situ environmental transmission electron microscopy

The extremely high structural tolerance of ceria to oxygen vacancies(Ov)has made it a desirable catalytic material for the hydrocarbon oxidation to chemicals and pharmaceuticals and the reduction of gaseous pollutants.It is proposed that the formation and diffusion of Ov originate from its outstanding reduction property.However,the formation and diffusion process of Ov over the surface of ceria at the atomic level is still unknown.Herein,the structural and valence evolution of CeO_(2)(111)surfaces in reductive,oxidative and vacuum environments from room temperature up to 700℃was studied with in situ aberration-corrected environmental transmission electron microscopy(ETEM)experiments.Ov is found to form under a high vacuum at elevated temperatures;however,the surface can recover to the initial state through the adsorption of oxygen atoms in an oxygen-contained environment.Furthermore,in hydrogen environment,the step-CeO_(2)(111)surface is not stable at elevated temperatures;thus,the steps tend to be eliminated with increasing temperature.Combined with first-principles density function calculations(DFT),it is proposed that O-terminated surfaces would develop in a hypoxic environment due to the dynamic diffusion of Ov from the outer surface to the subsurface.Furthermore,in a reductive environment,H2 facilitates the formation and diffusion of Ov while Ce-terminated surfaces develope.These results reveal dynamic atomic-scale interplay between the nanoceria surface and gas,thereby providing fundamental insights into the Ov-dependent reaction of nano-CeO_(2) during catalytic processes.

The Impact of Directly Observed Therapy on Preventive Treatment for Latent Tuberculosis Infection among Students in Dalian, China

Preventive treatment has an essential effect on latent tuberculosis infection(LTBI)[purified protein derivative(PPD)induration≥15 mm].Between2010 and 2013,there were 6 tuberculosis(TB)outbreaks in the universities in Dalian,China.So far,in Dalian,the directly observed therapy(DOT)and

定向空间的下幂结构

定向空间范畴推广了domain理论.该推广过程为函数式程序提供了非确定性指称语义的幂domain结构.本文以自由代数的方式定义了定向空间的下幂空间,证明了每个定向空间的下幂空间存在并给出其具体构造.一般情况下,定向空间的定向下幂空间既不同于赋予Scott拓扑的定向完备偏序集的下幂domain,也不同于Battenfeld和Sch?der定义的普通拓扑空间上观察诱导的下幂空间.

Host selection by the autoparasitoid Encarsia pergandiella on primary （Bemisia tabacl） and secondary （Eretmocerus mundus） hosts

In autoparasitoids, females are generally primary endoparasitoids of Hemiptera, while males are hyperparasitoids developing in or on conspecific females or other primary parasitoids. Female-host acceptance can be influenced by extrinsic and/or intrinsic factors. In this paper, we are concerned with intrinsic factors such as nutritional status, mating status, etc. We observed the behavior of Encarsia pergandiella Howard （Hymenoptera： Aphelinidae） females when parasitizing primary （3rd instar larvae ofBemisia tabaci Gen- nadius [Homoptera： Aleyrodidae]） and secondary hosts （3rd instar larvae and pupae of Eretmocerus rnundus Mercet [Hymenoptera： Aphelinidae]） for a period of 1 h. Females had different reproductive （virgin or mated younger） and physiological （fed elder or mated elder） status. Virgin females killed a large number of secondary hosts while investing a long time per host. However, they did not feed upon them. Mated females killed a lower number of secondary hosts and host feeding was observed in both consuming primary and secondary hosts. It was common to observe host examining females of all physiological statues tested repeatedly stinging the same hosts when parasitizing, killing or rejecting them. Fed elder females parasitized more B. tabaci larvae than E. mundus larvae or pupae, while investing less time on the primary host than on the secondary host. They also para- sitized more B. tabaci larvae than mated elder females, while investing less time per host. The access of females to honey allowed them to lay more eggs.

Achievements and challenges of the World Bank Loan/Department for International Development grant-assisted Tuberculosis Control Project in China

In March 2002,the government of China launched the World Bank Loan/ Department for International Development-supported Tuberculosis （TB） Control Project to reduce the prevalence and mortality of TB. The project generated promising results in policy development, strengthening of TB control systems, patient treatment success,funds management, and the introduction of legislation. In light of the global TB epidemic and control environment, it is useful to review the TB control priorities of the project, summarize the achievements and experiences around its implementation.

Tuberculosis care strategies and their economic consequences for patients: the missing link to end tuberculosis

Background:While investment in the development of Tuberculosis(TB)treatment strategies is essential,it cannot be assumed that the strategies are affordable for TB patients living in countries with high economic constraints.This study aimed to determine the economic consequences of directly observed therapy for TB patients.Methods:A cross-sectional cost-of-illness analysis was conducted between September to November 2015 among 576 randomly selected adult TB patients who were on directly observed treatment in 27 public health facilities in Addis Ababa,Ethiopia.Data were collected using interviewer-administered questionnaire adapted from the Tool to Estimate Patients’Costs.Mean and median costs,reduction of productivity,and household expenditure of TB patients were calculated and ways of coping costs captured.Eta(η),Odds ratio and p values were used to measure association between variables.Results:Of the total 576 TB patients enrolled,43%were smear-positive pulmonary TB(PTB),17%smear-negative PTB,37%Extra-PTB and 3%multi-drug resistant TB cases.Direct(Out-of-Pocket)mean and median costs of TB illness to patients were$123.0(SD=58.8)and$125.78(R=338.12),respectively,and indirect(loss income)mean and median costs were$54.26(SD=43.5)and$44.61(R=215.6),respectively.Mean and median total cost of TB illness to patient were$177.3(SD=78.7)and$177.1(R=461.8),respectively.The total cost had significant association with patient’s household income,residence,need for additional food,and primary income(P<0.05).Direct costs were catastrophic for 63%of TB patients,regardless of significant difference between gender(P=0.92)and type of TB cases(P=0.37).TB patients mean productivity and income reduced by 37 and 10%,respectively,compared with pre-treatment level,while mean household expenditure increased by 33%and working hours reduced by 78%due to TB illness.Income quartile categories were directly correlated with catastrophic costs(η=0.684).Conclusion:Despite the availability of free-of-charge anti-TB drugs,TB patients were suffering from out-of-pocket payments with catastrophic consequences,which in turn were hampering the efforts to end TB.TB patients in resource-limited countries deserve integrated patient-centered care with comprehensive health insurance coverage,financial incentives,and nutrition support to reduce catastrophic costs and retain them in care.Such countries should induce home-based directly observed therapy programs to reduce costs due to attending health facilities,intensify home treatment of critically-ill patients with impaired mobility,and reduce the spread of TB due to patients traveling to seek care.

The impact of pastoralist mobility on tuberculosis control in Ethiopia:a systematic review and meta-synthesis

Background:Directly observed treatment,short-course(DOTS)is the current mainstay to control tuberculosis(TB)worldwide.Context-specific adaptations of DOTS have impending implications in the fight against TB.In Ethiopia,there is a national TB control programme with the goal to eliminate TB,but uneven distribution across lifestyle gradients remains a challenge.Notably,the mobile pastoralist communities in the country are disproportionately left uncovered.The aim of this study was to summarize the evidence base from published literature to guide TB control strategy for mobile pastoralist communities in Ethiopia.Main text:We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)guidelines and systematically reviewed articles in seven electronic databases:Excerptra Medical Database,African Journal Online,PubMed,Google Scholar,Centre for Agriculture and Bioscience International Direct,Cochrane Library and Web of Science.The databases were searched from inception to December 31,2018,with no language restriction.We screened 692 items of which 19 met our inclusion criteria.Using a meta-ethnographic method,we identified six themes:(i)pastoralism in Ethiopia;(ii)pastoralists’livelihood profile;(iii)pastoralists’service utilisation;(iv)pastoralists’knowledge and awareness on TB control services;(v)challenges of TB control in pastoral settings;and(vi)equity disparities affecting pastoralists.Our interpretation triangulates the results across all included studies and shows that TB control activities observed in pastoralist regions of Ethiopia are far fewer than elsewhere in the country.Conclusions:This systematic review and meta-synthesis shows that TB control in Ethiopia does not align well with the pastoralist lifestyle.Inaccessibility and lack of acceptability of TB care are the key bottlenecks to pastoralist TB service provision.Targeting these two parameters holds promise to enhance effectiveness of an intervention.

Effects of CaO on Precipitation Morphology of Metallic Iron in Reduction of Iron Oxides Under CO Atmosphere

Growth process of iron whiskers and mechanism of CaO influence on precipitation morphology of metallic iron at the gas-solid interfaces was studied. Analytical reagents of Fe（NO3）3 and Ca（NO3）2 aqueous solution were used to prepare sheet film sample of Fe2 O3-CAO by thermal decomposition at high temperature. In-situ observation was con-ducted using a stereo optical microscope and a hot-stage. And reduction kinetics of samples was studied by thermo gravimetrie （TG） method. Some samples after reduction were analyzed by using the scanning electron microscope （SEM）, energy dispersive spectrometer （EDS） and fourier transform infrared （FT-IR） spectrometer. Results indi-cate that during the reduction of iron oxides with CO, metallic iron is mostly precipitated as whisker and the precipi- tation behavior mainly depends on reduction rate. Doping CaO can significantly increase the reduction rate and effec-tively change the precipitation morphology of metallic iron after the reduction. When CaO doping concentration is less than 4% （mass percent）, CaO can promote whisker formation of reduced iron; as it reaches 6% （mass per- cent）, CaO inhibits iron whiskers growth; as it is more than 8% （mass percent）, no whiskers could be observed. Therefore, controlling the quantity of Ca^2＋ is effective to control the formation and growth of iron whiskers during gaseous reduction and thus eliminating ore grain sticking caused by intertexture of iron whiskers.

New adaptive vector control methods for induction motors with simpler structure and better performance

This paper deals with the vector control, including both the direct vector control(DVC) and the indirect vector control(Id VC),of induction motors. It is well known that the estimation of rotor flux plays a fundamental role in the DVC and the estimation of rotor resistance is vital in the slip compensation of the Id VC. In these estimations, the precision is significantly affected by the motor resistances. Therefore, online estimation of motor resistances is indispensable in practice.For a fast estimation of motor resistances, it is necessary to slow down the convergence rate of the current estimate. On the other hand, for a fast estimation of the rotor flux, it is necessary to speed up its convergence rate. It is very difficult to realize such a trade-off in convergence rates in a full order observer.In this paper, we propose to decouple the current observer from the flux observer so as to realize independent convergence rates. Then, the resistance estimation algorithm is applied to both DVC and Id VC. In particular, in the application to Id VC the flux observer needs not be used, which leads to a simpler structure. Meanwhile, independent convergence rates of current observer and flux observer yield an improved performance. A superior performance in the torque and flux responses in both cases is verified by numerous simulations.