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We report the first example of copper-catalyzed α-alkylation of acetamides with alcohols via a borrowing hydrogen strategy. Catalyzed by the in situ-generated copper particles, acetamides and various substituted benzyl or alkyl alcohols were transformed into functionalized amides in good yields with excellent selectivity. Compared with previous work, this process is simple using commercially available Cu(OAc)2 as a precatalyst, without an additional ligand or a metal complex, and easier. Mechanistic studies revealed that aldehyde and α,ß-unsaturated amides were the intermediates of this reaction and also disclosed the role of copper in alcohol dehydrogenation and CâC bond hydrogenation.
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BACKGROUND: Cooperation between China and Africa is deepening, and business, trade, and people-to-people exchanges are growing closer together, especially in the infrastructure construction field. At the same time, malaria has become a serious health concern for Chinese construction workers in Africa, who are at increased risk of infection and complications due to lack of immunity and exposure to high-transmission environments. One of the biggest challenges in fighting malaria is their lack of knowledge and misinterpretations about the disease, which can impact their need for interventions, adherence to treatments, and health services. This study aims to determine the perception and interpretation of malaria among Chinese construction workers in sub-Saharan Africa. METHODS: Semi-structured interviews were conducted with 20 Chinese construction workers in sub-Saharan Africa. Some early respondents initially made contact through two Chinese construction companies in Africa, while the rest of the participants were engaged via a snowball method by the early participants. NVivo10, a qualitative research data management software and a thematic approach, was used to analyze the data and create themes. In order to achieve the general study goals, an inductive content analysis was applied. RESULTS: The study classified participants' perceptions and interpretations of malaria into four categories: flu-like malaria, the rumors of malaria, the hard-to-explain confusion about malaria, and the special interpretation of malaria. CONCLUSION: Malaria poses major health issues to Chinese construction workers in sub-Saharan Africa who lack immunity and live in an environment of high transmission. Their dearth of awareness and misunderstanding of malaria impacts their prevention and treatment behaviors and health outcomes. This study adopts qualitative methods to examine their perceptions and interpretations of malaria, which can serve as a source for future health management strategies.
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Indústria da Construção , Malária , Humanos , População do Leste Asiático , África Subsaariana , Malária/prevenção & controle , Pesquisa Qualitativa , PercepçãoRESUMO
Herein, using a single-electron-transfer reduction-based radical-polar crossover process as a strategy, protocols dealing with the preparation of functionalized alkynylcyclopropanes have been successfully developed via the reactions of 1,3-enynes with alkyl radicals. In addition to redox-neutral photocatalysis, nickel catalysis with zinc as the reductant is also an alternative to enable reactions of 1,3-enynes with redox-active N-hydroxyphthalimide esters. The synthetic application of alkynylcyclopropane has also been demonstrated.
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BACKGROUND: As malaria continues to be a significant global public health concern, especially in Sub-Saharan Africa, Chinese workers in Africa are at increased risk of malaria. The effectiveness of malaria prevention measures implemented by Chinese companies and workers is a question that may correlate with the malaria infection rate in this population. This study explored the use and effectiveness of malaria prevention measures for Chinese employees in West Africa to provide a reference for companies and individuals on improving malaria prevention and control. METHODS: Using a cross-sectional approach, we surveyed 256 participants in 2021, mainly from Nigeria, Mali, Côte d'Ivoire, Ghana, Guinea, Sierra Leone, and Senegal in West Africa. The survey duration is from July to the end of September 2021. We selected two companies from the 2020 ENR "World's Largest 250 International Contractors" list, which featured 6 Chinese companies, all of which are state-owned and have a 61.9% market share in Africa. The participants were Chinese workers with more than a year of work experience in construction companies in Africa. A 20-minute WeChat-based structured online questionnaire was used to obtain information on malaria infection status and malaria prevention measures. Descriptive statistical analysis, chi-square test, principal components analysis, and ordinal logistic regression analysis are used to analyze the data obtained. The difference in Statistical significance was set at P < 0.05. RESULTS: Ninety six (37.5%) participants contracted malaria more than once within a year. The principal components analysis found a low correlation between public and individual preventive measures. No significant correlation was found between public preventive measures and malaria infection (p > 0.05), while standardized use of mosquito nets (P = 0.016) and pesticide spraying (P = 0.047) contributed significantly to fewer malaria infections at the individual level, but the removal of vegetation around houses (P = 0.028) at the individual level related to higher malaria infection. CONCLUSIONS: In our sample of Chinese construction workers going to Africa, some individual preventive measures had a stronger association with malaria prevention than a variety of public environmental measures. Furthermore, individual and public preventive measures were not associated with each other. Both of these findings are surprising and require further investigation in larger and more diverse samples. This- study provides important clues about the challenges that risk reduction programs face for migrant workers from China and elsewhere.
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Indústria da Construção , Malária , Humanos , População do Leste Asiático , Malária/epidemiologia , Malária/prevenção & controle , Côte d'Ivoire/epidemiologia , GanaRESUMO
Rice false smut caused by the filamentous fungus Ustilaginoidea virens is a devastating grain disease in rice. Fungicides have been an important measure for the control of this disease. In this study, baseline sensitivities of 179 isolates of U. virens to the quinone outside inhibitor (QoI) fungicides azoxystrobin and pyraclostrobin were established. The distribution of the 50% effective concentration (EC50) values of each fungicide was unimodal. The frequency distribution of logarithmically transformed EC50 values fit or fit closer to a normal distribution. The ranges of EC50 values for azoxystrobin and pyraclostrobin were 0.001 to 0.864 and 0.001 to 0.569 µg/ml, with means and standard errors of the mean values of 0.203 ± 0.012 and 0.079 ± 0.006 µg/ml, respectively. There was a statistically significant and moderately positive correlation (n = 100, r = 0.469, P = 0.001) in sensitivity between these two fungicides. No cross-resistance was found between azoxystrobin, pyraclostrobin, and carbendazim or sterol demethylation inhibitor fungicides. Each fungicide had a significantly higher mean preventive efficacy compared with its curative efficacy. Field assays showed that the control efficacy of pyraclostrobin against rice false smut was greater than that of azoxystrobin. Pyraclostrobin had the best control of rice false smut in three rice varieties, with the control efficacy ranging from 81.5 to 95.5%, whereas azoxystrobin decreased the disease index by 64.1 to 69.2% under the same conditions. These results provide us a reference point in the management of U. virens and future QoI fungicide resistance monitoring programs.
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Fungicidas Industriais , Oryza , Fungicidas Industriais/farmacologia , Oryza/microbiologia , QuinonasRESUMO
BACKGROUND: There are increasing Chinese migrants in sub-Saharan Africa currently. Most of them are engaged in infrastructure construction. Research has shown that they stay at particular risk of HIV and are recommended for HIV testing. However, their HIV testing behavior, and its relevant factors, have not been researched among them by now. This study describes the recent HIV testing behavior and relevant factors among Chinese migrant workers in Kenya. METHODS: A cross-sectional survey was conducted among 110 male Chinese workers from six different Chinese infrastructure construction enterprises in Kenya. Furthermore, a two-stage cluster random sampling method was used to select participants. We used a questionnaire that included HIV testing history, demographic characteristics, and putative multilevel facilitators of HIV testing. Logistic regression was used to explore the predictors of recent HIV testing behavior among Chinese migrant workers in Kenya. RESULT: Of the 110 participants, 30 (27.27%) were tested for HIV in the recent year. All participants were male, and the majority were married (73.2%). The mean age was 37.49 years (SD = 9.73; range: 23 to 63), and a considerable proportion refused to answer questions about transactional sexual behaviors in the last year. Most were able to obtain HIV-related information (91.8%) and were exposed to HIV-related information in the last year (68.2%), but only 47.6% had sufficient HIV knowledge. Nearly one-fifth of them believed that selling sex and paying for sex is acceptable. Multiple logistic regression analysis indicated that participants who could accept the 'pay for sex' (OR: 2.74; 95% CI: 1.02, 7.36) and exposed to HIV related information (OR: 4.75; 95% CI: 1.29, 17.44) were more likely to test for HIV in the recent 1 year. CONCLUSION: Higher current HIV test rates were associated with a more open sexual attitude towards paying for sex and being exposed to HIV-related information in the last year among Chinese workers in Kenya. More specific attention to HIV should be attached to this population to increase the rate of HIV testing among them.
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Povo Asiático , Indústria da Construção , Teste de HIV , Migrantes , Adulto , Povo Asiático/psicologia , Povo Asiático/estatística & dados numéricos , China/etnologia , Estudos Transversais , Infecções por HIV/diagnóstico , Infecções por HIV/etnologia , Teste de HIV/estatística & dados numéricos , Humanos , Quênia/epidemiologia , Masculino , Pessoa de Meia-Idade , Comportamento Sexual/etnologia , Migrantes/psicologia , Migrantes/estatística & dados numéricos , Adulto JovemRESUMO
A convenient and efficient method for the ortho-carboxylation of phenols under atmospheric CO2 pressure has been developed. This method provides an alternative to the previously reported Kolbe-Schmitt method, which requires very high pressures of CO2 . The addition of a trisubstituted phenol has proved essential for the successful carboxylation of phenols with CO2 at standard atmospheric pressure, allowing the efficient preparation of a broad variety of salicylic acids.
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Dióxido de Carbono/química , Ácidos Carboxílicos/síntese química , Fenóis/química , Salicilatos/síntese química , Pressão Atmosférica , Cresóis/química , Fenômenos de Química Orgânica , Compostos de Sódio/química , TemperaturaRESUMO
The direct functionalization of phenols at the ortho and para position is generally facilitated by the electron-donating nature of the hydroxyl group. Accessing meta-functionalized phenols from the parent phenols, on the other hand, generally requires lengthy synthetic sequences. Here, we report the first methodology for the one-pot direct meta-selective arylation of phenols. This methodology is based on a traceless directing group relay strategy. In this process carbon dioxide is used as a transient directing group which facilitates a palladium catalyzed arylation meta to the phenol hydroxyl group with iodoarenes. This transformation proceeds with complete meta-selectivity and is compatible with a variety of functional groups both in the phenol and in the iodoarene coupling partner.
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Fenóis/química , Dióxido de Carbono/química , Catálise , Estrutura Molecular , Paládio/química , EstereoisomerismoRESUMO
Here, we report the development and application of a novel class of spirosilacycle-based diphosphine ligands (SPOSiPs). This type of diphosphine ligand could be readily prepared in two steps with high efficiency starting from enantiopure spirobiphenoxasilin-diol (SPOSiOL). According to the structural analysis of SPOSiP and its PdCl2 complex, SPOSiPs possess a flexible chiral pocket and feature a rigid configuration, a large dihedral angle, a long P-P distance, and a large P-M-P bite angle in their metal complexes. The potentials of SPOSiPs in asymmetric catalysis have also been preliminarily disclosed.
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A new strategy for the synthesis of fluorinated anilides in the absence of metals and oxidants has been developed. This deoxyfluorination of N-arylhydroxylamines with diethylaminosulfur trifluoride (DAST) proceeded smoothly under mild conditions, and the ortho- or para-fluorinated aromatic amine products were prepared in moderate to good yields. Structurally diverse fluorinated anilides, including heterocyclic and pharmaceutically relevant molecules, can be efficiently constructed by this protocol.
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Facile detection of malachite green (MG), a toxic dye, in aquaculture is urgently demanded for environment and food safety. Herein, we design a novel fluorescent probe, namely red emissive Se,N,Cl-doped carbon dots (CDs), to accurately determinate MG. CDs are prepared by hydrothermal treatment of selenourea and o-phenylenediamine in HCl solution. This material exhibits excitation-independent dual emissions at 625 and 679 nm, with a high quantum yield of 23.6%. A selective and sensitive fluorescent sensor toward MG is established based on inner filter effect, because both the excitation and emission light of CDs can be strongly absorbed by MG. The fluorescence quenching of CDs is linear to the MG concentration over the range of 0.07-2.50 µM with a low detection limit of 21 nM. Trace-level analysis of MG in fish tissue is successfully explored, demonstrating the great potential of the proposed sensor for MG monitoring in aquatic products.
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Produtos Pesqueiros/análise , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Pontos Quânticos/química , Corantes de Rosanilina/análise , Animais , Carbono/química , Cloro/química , Fluorescência , Corantes Fluorescentes/química , Análise de Alimentos/instrumentação , Nitrogênio/química , Compostos Organosselênicos/química , Selênio/química , Espectrometria de Fluorescência , Ureia/análogos & derivados , Ureia/químicaRESUMO
Strategies that exploit directing groups to control the site selectivity in the C-H activation of arenes have received much attention during the past two decades. In light of the importance of phenol derivatives in the areas of pharmaceuticals, agrochemicals, and materials science, transition-metal-catalyzed C-H activation of phenols has proven to be an extremely useful tool in organic synthesis. This Minireview summarizes the current state-of-the-art direct C-H activation of phenol derivatives under transition-metal catalysis.
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BACKGROUND AND PURPOSE: Self-monitoring of blood glucose (SMBG) is important to the management of diabetes mellitus, yet most patients with type 2 diabetes mellitus (T2DM) do not perform SMBG as recommended. The current status and influential factors of SMBG in China have not been well investigated. This study aimed to describe the present status of SMBG adherence in China and investigate the influential factors based on electronic questionnaires. PATIENTS AND METHODS: A cross-sectional study was conducted from June to July of 2017 at hospitals in Changsha, China. Seven hundred and twenty-one patients with T2DM completed the informationmotivationbehavioral (IMB) skills questionnaire and other electronic questionnaires composed of demographic and clinical characteristics as well as diabetes-related and psychological scales. Univariate comparisons and multivariate logistic regression were used to explore the relationships among SMBG adherence and related factors. RESULTS: Seven hundred and twenty-one patients with valid questionnaires were included. Only 27.5% (198/721) of the patients with T2DM were SMBG adherent based on the guideline of the Chinese Diabetes Society (CDS) in 2017. Among all groups of treatment regimens, the rate of SMBG adherence was highest at 36.6% (82/224) in patients on oral hypoglycaemic drugs (OHAs). In multivariable analysis, the treatment of OHAs (OR =3.731, CI 2.162-6.437) and diet/exercise (OR =3.534, CI 1.841-6.783), the patient having their own blood glucose meter (OR =6.916, CI 4.054-11.800) and a higher education level (OR =3.780, CI 1.688-8.466) were significantly associated with SMBG adherence. CONCLUSION: Most Chinese patients with T2DM did not perform SMBG as recommended. The treatment of OHAs and diet/exercise, the patient having their own blood glucose meter, a higher education level and other factors were correlates of SMBG adherence. There is clearly a need for prospective, multicenter, large-scale studies to explore the reasons for patients' failure to practice SMBG adherence.
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A catalytic asymmetric direct C-H arylation of (η6-arene)chromium complexes to obtain planar-chiral compounds is reported. The use of the hemilabile ligand H8-BINAP(O) is key to providing high enantioselectivity in this transformation. We show that this methodology opens the door to the synthesis of a variety of planar-chiral chromium derivatives which can be easily transformed into planar chiral mono- or diphosphines. Mechanistic studies, including synthesis and characterization of Pd and Ag complexes and their detection in the reaction mixture, suggest a Pd-catalyzed/Ag-promoted catalytic system where Ag carries out the C-H activation step.
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Carbon dioxide (CO2 ) represents the most abundant and accessible carbon source on Earth. Thus the ability to transform CO2 into valuable commodity chemicals through the construction of C-C bonds is an invaluable strategy. Carboxylic acids and derivatives, the main products obtained by carboxylation of carbon nucleophiles by reaction of CO2 , have wide application in pharmaceuticals and advanced materials. Among the variety of carboxylation methods currently available, the direct carboxylation of C-H bonds with CO2 has attracted much attention owing to advantages from a step- and atom-economical point of view. In particular, the prevalence of (hetero)aromatic carboxylic acids and derivatives among biologically active compounds has led to significant interest in the development of methods for their direct carboxylation from CO2 . Herein, the latest achievements in the area of direct C-H carboxylation of (hetero)aromatic compounds with CO2 will be discussed.
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Dióxido de Carbono/química , Carbono/química , Ácidos Carboxílicos/química , Hidrogênio/química , Catálise , Elementos de Transição/químicaRESUMO
A method that allows salicylaldehydes to be efficiently transformed into meta-arylated phenol derivatives through a cascade oxidation/arylation/protodecarboxylation sequence is presented. We demonstrate that the aldehyde functional group can be used as a convenient removable directing group to control site selectivity in C-H activation. Aldehydes are easily introduced into the starting materials and the group is readily cleaved after the C-H functionalization event.
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Aldeídos/química , Fenóis/química , Elementos de Transição/química , Carbono/química , Catálise , Hidrogênio/química , Oxirredução , Raios UltravioletaRESUMO
Salicylic acids are shown to be readily available and versatile starting materials that easily undergo a tandem arylation-protodecarboxylation process under Pd-catalysis. The corresponding meta-arylphenols can subsequently be easily transformed into a variety of meta-functionalized biaryls, highlighting the versatility of this approach to access this structural motif.