Changes of clinical characteristics of asymptomatic patients with positive SARS-Cov-2 nucleic acid test during treatment cycle and related risk factors.

OBJECTIVE: This study was designed to explore the clinical characteristics, outcomes, and related influencing factors for asymptomatic patients with positive Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-Cov-2) nucleic acid test. METHODS: Clinical data of 1568 patients with positive SARS-Cov-2 nucleic acid test (SNAT) were collected retrospectively. The patients were assigned to an asymptomatic group and a symptomatic group according to the existence of clinical symptoms when they got positive result in nucleic acid test, and the clinical data of the two groups were analyzed and compared. In addition, the data of asymptomatic patients who showed clinical symptoms later and the results of two-week follow-up after cure were analyzed. RESULTS: Among all enrolled patients, there were 1489 patients with positive symptoms and 79 asymptomatic patients, including 34 patients who developed symptoms during treatment. Logistic analysis revealed that age ≤45 years (OR=2.722, P<0.001), history of diabetes mellitus (OR=0.446, P=0.007), and history of cancer (OR=0.259, P=0.008) were independent factors for asymptomatic presentation in patients with positive SNAT, and age ≥46 years (OR=1.562, P=0.012) and history of hypertension (OR=2.077, P<0.001) were risk factors for the occurrence of clinical symptoms in asymptomatic patients with positive SNAT during hospitalization. During the follow-up after cure, 8 patients got reoccurring positive SNAT result. CONCLUSION: Asymptomatic patients with positive SNAT are mostly young and middle-aged people, and old age and hypertension are risk factors for the occurrence of positive clinical characteristics in asymptomatic patients.

Controlled Synthesis, Mechanism and Degradation Property of Birnessite-MnO2 Nanoflowers and Nanoflakes.

Birnessite-MnO2 nanoflakes were synthesized via an aqueous oxidation method at 90 °C using Mn(CH3COO)2, NaOH, and KMnO4. The samples' morphology, crystalline structure, and optical property were determined by field emission scanning electron microscopy, X-ray powder diffraction and UV-Vis spectrophotometry. The birnessite-MnO2 nanoflakes were converted to KxMn8O16 and Mn suboxides following a decrease in the concentration of KMnO4 in the reaction. The amount of NaOH in the reaction determined the type of precursor. Without NaOH, the precursor was converted from Mn(OH)2 to Mn2+ (from Mn(CH3COO)2), thereby enabling the synthesis of birnessite-MnO2 nanoflowers. The formation mechanism of birnessite-MnO2 nanoflowers and nanoflakes was clarified via the corresponding simulated crystal structures. Evaluation of the synthesized samples confirmed that the birnessite-MnO2 nanoflakes and nanoflowers exhibited excellent degradation properties.

Aqueous Synthesis of Mn3O4 Nanoparticle@MnOOH Nanobelt Heterostructures.

A combined heterostructures with Mn3O4 nanoparticles attached to MnOOH nanobelts were prepared via an aqueous oxidation method at 90 °C with H2O2 as oxidant. The crystalline structures and morphologies of the as-prepared samples were detected by X-ray powder diffraction (XRD), field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM) analysis, and the forming mechanism of Mn3O4@MnOOH nanomaterials was discussed. Crystalline composition and morphologies of samples changed with reaction time and crystallinity of Mn(OH)2 precursor. ß-MnOOH nanoplates can be obtained in the initial reaction, then it transformed to γ-MnOOH nanobelts and/or Mn3O4 nanoparticles as reaction time increasing. The ratio of Mn3O4 in Mn3O4@MnOOH nanomaterials increased with the better crystallinity of Mn(OH)2 precursor. The as-prepared Mn3O4@MnOOH nanomaterials with varied compositions were used for degradation of Rhodamine B (RhB) in acid condition. The degradation reactions carried out in acid condition without stimulated light sources. The results showed that the manganese heterostructures had good activity based on synergy of Mn3O4 and MnOOH nanocrystals.

Room temperature synthesis of 2D CuO nanoleaves in aqueous solution.

A simple room temperature method was reported for the synthesis of CuO nanocrystals in aqueous solution through the sequence of Cu(2+) → Cu(OA)2 → Cu(OH)2 → Cu(OH)(2-)4 → CuO. Sodium oleate (SOA) was used as the surfactant and shape controller. The as-prepared samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectroscopy (UV-vis) and differential thermal analysis (DTA). It can be seen that 1D Cu(OH)(2) nanowires were first obtained from Cu(OA)(2) and, at room temperature, converted into 2D CuO nanoleaves (CuO NLs) in a short time under a weakly basic environment. On prolonging the reaction time, the top part of these 2D nanoleaves branched and separated along the long axis to form 1D rod-like nano-CuO because of the assistance of SOA. A possible transformation mechanism of Cu(OH)(2) to CuO nanostructures at room temperature in aqueous solution is discussed. The transformation velocity can be controlled by changing the pH value of the system. The prepared CuO NLs were used to construct an enzyme-free glucose sensor. The detecting results showed that the designed sensor exhibited good amperometric responses towards glucose with good anti-interferent ability.