The objective of this multicentric study was to assess the prevalence of Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma génitalium and Trichomonas vaginalis infections in Brazzaville, in the Republic of...The objective of this multicentric study was to assess the prevalence of Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma génitalium and Trichomonas vaginalis infections in Brazzaville, in the Republic of Congo, using molecular methods. From January to December 2021, the sexually transmitted disease risk participants were recruited from six centers: The Association of Young HIV-Positive People of Congo, The Congolese Association for Family Welfare, The Association for Support to Vulnerable Groups, Talangaï hospital, Brazzaville university hospital (outpatient service) and the private clinic COGEMO (outpatient service). The real-time multiplex PCR was carried out to detect these pathogens. Each patient had at least one specimen (urine, urethral, anal and/or vaginal samples). The patients were considered infected when one of their samples was positive. 287 participants made of 227 women and 60 men were tested. The general prevalence of these infections was: Chlamydia trachomatis 2.79%, Neisseria gonorrhoeae 3.14%, Mycoplasma génitalium 3.45% and Trichomonas vaginalis 2.97. The prevalence rates according to sex were: C. trachomatis, M. génitalium, N. gonorrhea and T. vaginalis were 1.32%, 2.05%, 1.32% and 3.42% in women and 8.33%, 7.02%, 10% and 1.75% in men, respectively. Most infected patients were asymptomatic. Prevalence rates were higher in bisexual individuals, with the exception of T. vaginalis which showed higher prevalence in heterosexual patients. The bisexual and homosexual individuals represent a major public health problem in sexually active young adults, particularly among men having sex with men. These sexually transmitted infections are mainly asymptomatic, their diagnosis and management remain difficult in developing countries.展开更多
Specimens of the forest species such as Pentaclethra macrophylla, Petersianthus macrocarpus, Pycnanthus angolensis and Terminalia superba have been sampled from LUKI Biosphere reserve in the Democratic Republic of the...Specimens of the forest species such as Pentaclethra macrophylla, Petersianthus macrocarpus, Pycnanthus angolensis and Terminalia superba have been sampled from LUKI Biosphere reserve in the Democratic Republic of the Congo in order to determine their wood density with the perspective to decarbonisation. These parameters have been found out experimentally utilizing a drying technique in an oven including techniques of immersion in an Erlenmeyer full of water. The corresponding results indicated that the four species wood density is respectively 0.85, 0.80, 0.77 and 0.51. These preliminary results will be useful in our ongoing project on carbon dioxide absorption capacity of Congo rainforest tree species.展开更多
Microplastics(MPs)have been recognized as a new class of emerging contaminants in recent years.They not only directly impact aquatic organisms,but also indirectly impact these organisms by interacting with background ...Microplastics(MPs)have been recognized as a new class of emerging contaminants in recent years.They not only directly impact aquatic organisms,but also indirectly impact these organisms by interacting with background toxins in the environment.Moreover,under realistic environmental conditions,algae,a natural food for aquatic organisms,may alter the toxicity pattern related to MPs.In this research,we first examined the toxicity of MPs alone,and their effect on the toxicity of lead(Pb)on Ceriodaphnia dubia(C.dubia),a model aquatic organism for toxicity survey.Then,we investigated the effect of algae on the combined toxicity of MPs and Pb.We observed that,MPs significantly increased Pb toxicity,which was related to the increase in soluble Pb concentration and the intake of Pb-loaded MPs,both of which increased the accumulation of Pb in C.dubia.The presence of algae mitigated the combined toxicity of MPs and Pb,although algae alone increased Pb accumulation.Therefore,the toxicity mitigation through algae uptake came from mechanisms other than Pb accumulation,which will need further investigation.展开更多
The structures of tungsten and tungsten carbide scaffolds play a key role in determining the properties of their infiltrated composites for multifunctional applications.However,it is challenging to construct and contr...The structures of tungsten and tungsten carbide scaffolds play a key role in determining the properties of their infiltrated composites for multifunctional applications.However,it is challenging to construct and control the architectures by means of self-assembly in W/WC systems because of their large densities.Here we present the development of unidirectionally porous architectures,with high porosities exceeding 65 vol.%,for W and WC scaffolds which in many respects reproduce the design motif of natural wood using a direct ice-templating technique.This was achieved by adjusting the viscosities of suspensions to retard sedimentation during freezing.The processing,structural characteristics and mechanical properties of the resulting scaffolds were investigated with the correlations between them explored.Quantitative relationships were established to describe their strengths based on the mechanics of cellular solids by taking into account both inter-and intra-lamellar pores.The fracture mechanisms were also identified,especially in light of the porosity.This study extends the effectiveness of the ice-templating technique for systems with large densities or particle sizes.It further provides preforms for developing new natureinspired multifunctional materials,as represented by W/WC-Cu composites.展开更多
Nano-TiO_(2) can remarkably increase lead(Pb)toxicity in aquatic organisms.However,the mechanism of this toxicity,additive or synergistic,is not well understood.To explore this mechanism,we inspected the role of nano-...Nano-TiO_(2) can remarkably increase lead(Pb)toxicity in aquatic organisms.However,the mechanism of this toxicity,additive or synergistic,is not well understood.To explore this mechanism,we inspected the role of nano-TiO_(2) in the toxicity of Pb on Ceriodaphnia dubia(C.dubia),a model water flea species typically used for ecotoxicity studies.The effect of algae,a diet for aquatic organisms,on the effect of this binary mixture was also investigated.A two-compartment toxicokinetic(TK)-toxicodynamic(TD)modeling approach was used to quantify the Pb toxicity under these complex conditions and to develop critical parameters for understanding the mechanism of toxicity.This twocompartment modeling approach adequately described the Pb accumulation in the gut and in the rest of the body tissue under different nano-TiO_(2) concentrations,with and without algae,and predicted the toxicity response of C.dubia.It indicated that increasing the nano-TiO_(2) concentration reduced the Pb tolerance level and concurrently increased the killing rate constant of C.dubia.Therefore,nano-TiO_(2) synergistically enhanced Pb toxicity.Algae remarkably reduced the toxicity of this binary mixture through reducing the Pb transfer rate to the body tissue and the killing rate,although it did not affect the Pb tolerance level.This two-compartment modeling approach is useful in understanding the role of nanoparticles when assessing the overall toxicity of nanoparticles and other toxic elements in the environment.展开更多
This paper is extensions of the Tesfay(2014) paper on the Bullwhip effects and Tesfay(2015) paper on the foundations of the Bullwhip effect and its implications on the theory of organizational coordination.The major o...This paper is extensions of the Tesfay(2014) paper on the Bullwhip effects and Tesfay(2015) paper on the foundations of the Bullwhip effect and its implications on the theory of organizational coordination.The major outcome of the Tesfay(2014) paper suggests that one way or another Bullwhip effect attacks all the business collaborates in supply chain.The major outcome of the Tesfay(2015) paper suggests that the solutions from the transaction cost economics are still insufficient to produce the most efficient organizational coordination.This paper extends stochastic analysis by applying various panel data regression models and structural equations of seemingly unrelated regression(SUR)models on the experimental data from Beer game.Recursive autoregressive-SUR model estimation result confirmed that the Bullwhip effects can be cause by both intra-organizational coordination and inter-organizational coordination of the business collaborates of supply chain.In order to control the effect of intra-organizational coordination on the Bullwhip effects,the author outline a new coordination type known as the hyper-hybrid coordination.As a final point,the author has shown important applications of the hyperhybrid coordination in the airline industry.展开更多
文摘The objective of this multicentric study was to assess the prevalence of Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma génitalium and Trichomonas vaginalis infections in Brazzaville, in the Republic of Congo, using molecular methods. From January to December 2021, the sexually transmitted disease risk participants were recruited from six centers: The Association of Young HIV-Positive People of Congo, The Congolese Association for Family Welfare, The Association for Support to Vulnerable Groups, Talangaï hospital, Brazzaville university hospital (outpatient service) and the private clinic COGEMO (outpatient service). The real-time multiplex PCR was carried out to detect these pathogens. Each patient had at least one specimen (urine, urethral, anal and/or vaginal samples). The patients were considered infected when one of their samples was positive. 287 participants made of 227 women and 60 men were tested. The general prevalence of these infections was: Chlamydia trachomatis 2.79%, Neisseria gonorrhoeae 3.14%, Mycoplasma génitalium 3.45% and Trichomonas vaginalis 2.97. The prevalence rates according to sex were: C. trachomatis, M. génitalium, N. gonorrhea and T. vaginalis were 1.32%, 2.05%, 1.32% and 3.42% in women and 8.33%, 7.02%, 10% and 1.75% in men, respectively. Most infected patients were asymptomatic. Prevalence rates were higher in bisexual individuals, with the exception of T. vaginalis which showed higher prevalence in heterosexual patients. The bisexual and homosexual individuals represent a major public health problem in sexually active young adults, particularly among men having sex with men. These sexually transmitted infections are mainly asymptomatic, their diagnosis and management remain difficult in developing countries.
文摘Specimens of the forest species such as Pentaclethra macrophylla, Petersianthus macrocarpus, Pycnanthus angolensis and Terminalia superba have been sampled from LUKI Biosphere reserve in the Democratic Republic of the Congo in order to determine their wood density with the perspective to decarbonisation. These parameters have been found out experimentally utilizing a drying technique in an oven including techniques of immersion in an Erlenmeyer full of water. The corresponding results indicated that the four species wood density is respectively 0.85, 0.80, 0.77 and 0.51. These preliminary results will be useful in our ongoing project on carbon dioxide absorption capacity of Congo rainforest tree species.
基金Authors appreciate the facility support from the Center for Research in Energy and Environment(CREE)at Missouri S&Tthe help from Xiaolong He and Shuo Yang from the Chemistry Department at Missouri S&T,for TOC analysis and SEM image.
文摘Microplastics(MPs)have been recognized as a new class of emerging contaminants in recent years.They not only directly impact aquatic organisms,but also indirectly impact these organisms by interacting with background toxins in the environment.Moreover,under realistic environmental conditions,algae,a natural food for aquatic organisms,may alter the toxicity pattern related to MPs.In this research,we first examined the toxicity of MPs alone,and their effect on the toxicity of lead(Pb)on Ceriodaphnia dubia(C.dubia),a model aquatic organism for toxicity survey.Then,we investigated the effect of algae on the combined toxicity of MPs and Pb.We observed that,MPs significantly increased Pb toxicity,which was related to the increase in soluble Pb concentration and the intake of Pb-loaded MPs,both of which increased the accumulation of Pb in C.dubia.The presence of algae mitigated the combined toxicity of MPs and Pb,although algae alone increased Pb accumulation.Therefore,the toxicity mitigation through algae uptake came from mechanisms other than Pb accumulation,which will need further investigation.
基金the National Natural Science Foundation of China(Grant Nos.51871216 and 51501190)the Opening Project of Jiangsu Province Key Laboratory of High-end Structural Materials(Grant No.hsm1801)provided by the U.S.Air Force Office of Scientific Research,under MURI grant AFSOR-FA9550-15-1-0009 to the University of California Riverside through a subcontract to the University of California Berkeley。
文摘The structures of tungsten and tungsten carbide scaffolds play a key role in determining the properties of their infiltrated composites for multifunctional applications.However,it is challenging to construct and control the architectures by means of self-assembly in W/WC systems because of their large densities.Here we present the development of unidirectionally porous architectures,with high porosities exceeding 65 vol.%,for W and WC scaffolds which in many respects reproduce the design motif of natural wood using a direct ice-templating technique.This was achieved by adjusting the viscosities of suspensions to retard sedimentation during freezing.The processing,structural characteristics and mechanical properties of the resulting scaffolds were investigated with the correlations between them explored.Quantitative relationships were established to describe their strengths based on the mechanics of cellular solids by taking into account both inter-and intra-lamellar pores.The fracture mechanisms were also identified,especially in light of the porosity.This study extends the effectiveness of the ice-templating technique for systems with large densities or particle sizes.It further provides preforms for developing new natureinspired multifunctional materials,as represented by W/WC-Cu composites.
文摘Nano-TiO_(2) can remarkably increase lead(Pb)toxicity in aquatic organisms.However,the mechanism of this toxicity,additive or synergistic,is not well understood.To explore this mechanism,we inspected the role of nano-TiO_(2) in the toxicity of Pb on Ceriodaphnia dubia(C.dubia),a model water flea species typically used for ecotoxicity studies.The effect of algae,a diet for aquatic organisms,on the effect of this binary mixture was also investigated.A two-compartment toxicokinetic(TK)-toxicodynamic(TD)modeling approach was used to quantify the Pb toxicity under these complex conditions and to develop critical parameters for understanding the mechanism of toxicity.This twocompartment modeling approach adequately described the Pb accumulation in the gut and in the rest of the body tissue under different nano-TiO_(2) concentrations,with and without algae,and predicted the toxicity response of C.dubia.It indicated that increasing the nano-TiO_(2) concentration reduced the Pb tolerance level and concurrently increased the killing rate constant of C.dubia.Therefore,nano-TiO_(2) synergistically enhanced Pb toxicity.Algae remarkably reduced the toxicity of this binary mixture through reducing the Pb transfer rate to the body tissue and the killing rate,although it did not affect the Pb tolerance level.This two-compartment modeling approach is useful in understanding the role of nanoparticles when assessing the overall toxicity of nanoparticles and other toxic elements in the environment.
文摘This paper is extensions of the Tesfay(2014) paper on the Bullwhip effects and Tesfay(2015) paper on the foundations of the Bullwhip effect and its implications on the theory of organizational coordination.The major outcome of the Tesfay(2014) paper suggests that one way or another Bullwhip effect attacks all the business collaborates in supply chain.The major outcome of the Tesfay(2015) paper suggests that the solutions from the transaction cost economics are still insufficient to produce the most efficient organizational coordination.This paper extends stochastic analysis by applying various panel data regression models and structural equations of seemingly unrelated regression(SUR)models on the experimental data from Beer game.Recursive autoregressive-SUR model estimation result confirmed that the Bullwhip effects can be cause by both intra-organizational coordination and inter-organizational coordination of the business collaborates of supply chain.In order to control the effect of intra-organizational coordination on the Bullwhip effects,the author outline a new coordination type known as the hyper-hybrid coordination.As a final point,the author has shown important applications of the hyperhybrid coordination in the airline industry.
