Alloys of transition-metal dichalcogenide can display distinctive phase evolution because of their two-dimensional structures. Herein, we report the colloidal synthesis of Mo1–x V x Se2 alloy nanosheets with full composition tuning. Alloying led to a phase transition at x = 0.7 from the semiconducting 2H phase MoSe2 to the metallic 1T phase VSe2. It also produced significant V and Se vacancies, which became the richest in the 2H phase at x = 0.3–0.5. Extensive spin-polarized density functional theory calculations consistently predicted the 2H–1T phase transition at x = 0.7, in agreement with the experimental results. The vacancy formation energy also supports the formation of V and Se vacancies. Alloying in the 2H phase enhanced the electrocatalytic performance toward hydrogen evolution reaction (HER) at x = 0.3 (in 0.5 M H2SO4) or 0.4 (in 1 M KOH). The Gibbs free energy along the HER pathway indicates that this maximum performance is due to the highest concentration of active V and Se vacancy sites.

Earth-abundant transition metal dichalcogenide nanosheets have emerged as an excellent catalyst for electrochemical water splitting to generate H2. Alloying the nanosheets with heteroatoms is a promising strategy to enhance their catalytic performance. Herein, we synthesized hexagonal (2H) phase Mo1–x Nb x Se2 nanosheets over the whole composition range using a solvothermal reaction. Alloying results in a variety of atomic-scale crystal defects such as Se vacancies, metal vacancies, and adatoms. The defect content is maximized when x approaches 0.5. Detailed structure analysis revealed that the NbSe2 bonding structures in the alloy phase are more disordered than the MoSe2 ones. Compared to MoSe2 and NbSe2, Mo0.5Nb0.5Se2 exhibits much higher electrocatalytic performance for hydrogen evolution reaction. First-principles calculation was performed for the formation energy in the models for vacancies and adatoms, supporting that the alloy phase has more defects than either NbSe2 or MoSe2. The calculation predicted that the separated NbSe2 domain at x = 0.5 favors the concurrent formation of Nb/Se vacancies and adatoms in a highly cooperative way. Moreover, the Gibbs free energy along the reaction path suggests that the enhanced HER performance of alloy nanosheets originates from the higher concentration of defects that favor H atom adsorption.

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c Four different rapid diagnostic tests (RDTs) for malaria were evaluated by testing 82 healthy control patients, 89 Plasmodium vivax-infected patients, and 92 rheumatoid factor (RF)-positive nonmalaria patients. The false-positive rate ranged from 2.2% to 13% in RF-positive patients. High RF levels are associated with malaria RDT false positivity. M alaria remains a major global health problem in tropical and subtropical countries, with high morbidity and mortality and extensive economic loss (1). Malaria rapid diagnostic tests (RDTs) are becoming the clinical diagnostic method of choice due to their quick results and ease of use, even by inexperienced personnel (2). However, false-positive results may be observed in patients with rheumatoid factor (RF), hepatitis C, toxoplasmosis, human African trypanosomiasis, dengue, leishmaniasis, Chagas disease, and schistosomiasis (2). Iqbal et al. (3) reported that 33 of the 35 false-positive specimens were negative when the RF was absorbed in the immunochromatographic test (ICT). The goal of this study was to use four different malaria RDTs to explore the relationship between false-positive malaria RDT results and RF.Between April 2010 and August 2013, a total of 263 wholeblood samples with EDTA were collected from South Korean patients at the Korea University Guro Hospital, Republic of Korea. Of these 263 samples, 89 were infected with malaria, as confirmed by Giemsa-stained microscopic examination, 92 did not have malaria but did have RF, and 82 had neither malaria nor RF. Both microscopy and PCR were used to rule out malaria. Each patient provided informed consent under the protocol for human use, which was approved by the Human Use Ethical Committee, Korea University Guro Hospital.Thick and thin blood films were prepared when blood was drawn in accordance with standard procedures. These films were stained with Giemsa and examined by trained microscopists who did not have prior knowledge of the patients' clinical history. Plasmodium species and the parasite density were determined. The circumsporozoite protein (CSP) gene of Plasmodium vivax was amplified by PCR using previously established methods (4). Four commercial malaria RDT kits were selected based on the multiple target antigens (Ags) detected, the BinaxNOW malaria kit (Binax Inc., Scarborough, ME, USA), the OptiMAL-IT malaria kit (BioRad, Marnes la Coquette, France), the SD Bioline malaria Ag Pf/ Pan rapid test (Standard Diagnostics, Inc., Yongin, South Korea), and the Humasis malaria P.f/Pan antigen test (Humasis, Anyang, South Korea). BinaxNOW detects both histidine-rich protein 2 (HRP-2), which is specific to Plasmodium falciparum, and aldolase, which is a pan-malarial enzyme found in the five human pathogenic Plasmodium species (5). OptiMAL-IT differentiates P. falciparum-specific lactate dehydrogenase (PfLDH) and pan-Plasmodium lactate dehydrogenase (pLDH) by immunological detection (6). The SD Bioline and Humasis tests target HRP-2 for P. falciparum and pLDH for other human malaria species (7,8). All te...