In Situ Preparation of High-Performance Silicon-Based Integrated Electrodes Using Cross-Linked Cyclodextrins.

The strategy of material modification for improving the stability of silicon electrodes is laborious and costly, while the conventional binders cannot withstand the repeated massive volume variability of silicon-based materials. Hence, there is a demand to settle the silicon-based materials' problems with green and straightforward solutions. This paper presents a high-performance silicon anode with a binder obtained by in situ thermal cross-linking of citric acid (CA) and ß-cyclodextrin (ß-CD) during the electrode preparation process. The Si electrode with a binder synthesized by the one-pot method shows excellent cycling performance. It maintains a specific capacity of 1696 mAh·g-1 after 200 cycles at a high current of 0.5 C. Furthermore, the carbonylation of ß-CD to carbonyl-ß-CD (c-ß-CD) introduced better water solubility, and the c-ß-CD can generate multidimensional connections with CA and Si, which significantly enhances the specific capacity to 1941 mAh·g-1 at 0.5 C. The results demonstrate that the prepared integrated electrode facilitates the formation of a stable and controllable solid electrolyte interface layer of Si and accommodates Si's repeated giant volume variations.

Cross-linked ß-CD-CMC as an effective aqueous binder for silicon-based anodes in rechargeable lithium-ion batteries.

As a non-active material component, the binder can effectively maintain the integrity of battery electrodes. In this work, based on the inspired structure of fishing nets, a three-dimensional mesh adhesive using widely sourced raw materials CMC and ß-CD was designed. These cross-linked cyclodextrins have the advantage of dispersing the stress at the anchor point and moderating the significant volume changes of the Si anode. The Si/ß-CD-CMC electrode maintains a reversible capacity of 1702 mA h g-1 even after 200 cycles at a high current of 0.5C. This work represents a significant step forward in Si anode binders and enables the cross-linked cyclodextrins to have potential applications in energy storage systems.

Clinical features and risk factors of severely and critically ill patients with COVID-19.

BACKGROUND: As of June 1, 2020, over 370000 coronavirus disease 2019 (COVID-19) deaths have been reported to the World Health Organization. However, the risk factors for patients with moderate-to-severe or severe-to-critical COVID-19 remain unclear. AIM: To explore the characteristics and predictive markers of severely and critically ill patients with COVID-19. METHODS: A retrospective study was conducted at the B11 Zhongfaxincheng campus and E1-3 Guanggu campus of Tongji Hospital affiliated with Huazhong University of Science and Technology in Wuhan. Patients with COVID-19 admitted from 1st February 2020 to 8th March 2020 were enrolled and categorized into 3 groups: The moderate group, severe group and critically ill group. Epidemiological data, demographic data, clinical symptoms and outcomes, complications, laboratory tests and radiographic examinations were collected retrospectively from the hospital information system and then compared between groups. RESULTS: A total of 126 patients were enrolled. There were 59 in the moderate group, 49 in the severe group, and 18 in the critically ill group. Multivariate logistic regression analysis showed that age [odd ratio (OR) = 1.055, 95% (confidence interval) CI: 1.099-1.104], elevated neutrophil-to-lymphocyte ratios (OR = 4.019, 95%CI: 1.045-15.467) and elevated high-sensitivity cardiac troponin I (OR = 10.126, 95%CI: 1.088 -94.247) were high-risk factors. CONCLUSION: The following indicators can help clinicians identify patients with severe COVID-19 at an early stage: age, an elevated neutrophil-to-lymphocyte ratio and high sensitivity cardiac troponin I.

Simple Preparation of Carbon Dots and Application in Cephalosporin Detection.

Carbon dots have good biocompatibility, low toxicity, excellent photoluminescence properties, and good light stability, endowing them good application prospects in drug detection, chemical analysis, drug delivery, and other fields. In this study, p-phenylenediamine was used as the carbon source, and carbon dots were synthesized in hydrochloric acid medium using microwave method. When the excitation wavelength is about 300 nm, a strong emission peak of 689 nm is detected for the synthesized carbon dots. Carbon dots' size is about 4.0±0.2 nm, and the carbon dots with spherical shape are uniformly distributed. The quantum yield of carbon dots is 8.07%. In addition, cephalosporins. were detected and analyzed using synthetic carbon dots. The results show that the presence of cephalosporins reduced the fluorescence intensity of carbon dots, and the reduced fluorescence intensity of the synthesized carbon dots showed a linear correlation with the cephalosporins' concentration. Cephalosporins' detection scope is 0.2 µmol/L to 80 µ mol/L, and the detection limit is 0.084 µ mol/L. A mechanism study shows that the effect of cephalosporins on carbon dot's fluorescence intensity can be attributed to the inner filter effect of cephalosporins. On this basis, a sensitive and 0selective cephalosporins detection method was established. Furthermore, this established method for cephalosporins detection was applied to real samples, resulting in a low relative standard deviation (RSD) and good recoveries.

Proton solvent-controllable synthesis of manganese oxalate anode material for lithium-ion batteries.

Manganese oxalates with different structures and morphologies were prepared by the precipitation method in a mixture of dimethyl sulfoxide (DMSO) and proton solvents. The proton solvents play a key role in determining the structures and morphologies of manganese oxalate. Monoclinic MnC2O4·2H2O microrods are prepared in H2O-DMSO, while MnC2O4·H2O nanorods and nanosheets with low crystallinity are synthesized in ethylene glycol-DMSO and ethanol-DMSO, respectively. The corresponding dehydrated products are mesoporous MnC2O4 microrods, nanorods, and nanosheets, respectively. When used as anode material for Li-ion batteries, mesoporous MnC2O4 microrods, nanorods, and nanosheets deliver a capacity of 800, 838, and 548 mA h g-1 after 120 cycles at 8C, respectively. Even when charged/discharged at 20C, mesoporous MnC2O4 nanorods still provide a reversible capacity of 647 mA h g-1 after 600 cycles, exhibiting better rater performance and cycling stability. The electrochemical performance is greatly influenced by the synergistic effect of surface area, morphology, and size. Therefore, the mesoporous MnC2O4 nanorods are a promising anode material for Li-ion batteries due to their good cycle stability and rate performance.

Deep Eutectic Solvent Synthesis of LiMnPO4/C Nanorods as a Cathode Material for Lithium Ion Batteries.

Olivine-type LiMnPO4/C nanorods were successfully synthesized in a chloride/ethylene glycol-based deep eutectic solvent (DES) at 130 °C for 4 h under atmospheric pressure. As-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and electrochemical tests. The prepared LiMnPO4/C nanorods were coated with a thin carbon layer (approximately 3 nm thick) on the surface and had a length of 100-150 nm and a diameter of 40-55 nm. The prepared rod-like LiMnPO4/C delivered a discharge capacity of 128 mAh·g-1 with a capacity retention ratio of approximately 93% after 100 cycles at 1 C. Even at 5 C, it still had a discharge capacity of 106 mAh·g-1, thus exhibiting good rate performance and cycle stability. These results demonstrate that the chloride/ethylene glycol-based deep eutectic solvents (DES) can act as a new crystal-face inhibitor to adjust the oriented growth and morphology of LiMnPO4. Furthermore, deep eutectic solvents provide a new approach in which to control the size and morphology of the particles, which has a wide application in the synthesis of electrode materials with special morphology.

Fast Preparation of Porous MnO/C Microspheres as Anode Materials for Lithium-Ion Batteries.

Porous MnO/C microspheres have been successfully fabricated by a fast co-precipitation method in a T-shaped microchannel reactor. The structures, compositions, and electrochemical performances of the obtained MnO/C microspheres are characterized by X-ray diffraction, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller analysis, charge-discharge testing, cyclic voltammograms, and electrochemical impedance spectra. Experimental results reveal that the as-prepared MnO/C, with a specific surface area of 96.66 m²·g-1 and average pore size of 24.37 nm, exhibits excellent electrochemical performance, with a discharge capacity of 655.4 mAh·g-1 after cycling 50 times at 1 C and capacities of 808.3, 743.7, 642.6, 450.1, and 803.1 mAh·g-1 at 0.2, 0.5, 1, 2, and 0.2 C, respectively. Moreover, the controlled method of using a microchannel reactor, which can produce larger specific surface area porous MnO/C with improved cycling performance by shortening lithium-ion diffusion distances, can be easily applied in real production on a large scale.

Highly sensitive detection of bovine serum albumin based on the aggregation of triangular silver nanoplates.

A simple, fast and highly sensitive spectrophotometric method for the determination of bovine serum albumin (BSA) has been developed based on the interactions between triangular silver nanoplates (TAgNPs) and BSA in the presence of Britton-Robison buffer solution (BR). Particularly, the wavelength of absorption maximum (λ(max)) of TAgNPs is red shifted in the presence of BSA together with Britton-Robinson buffer solution (BR, pH=2.56), and the color of the solution changed from blue to light blue. This may be due to the interactions between BSA molecules on the surface of TAgNPs through electrostatic forces, hydrogen bonds, hydrophobic effects and van der Waals forces at pH2.56, which leads to the aggregation of TAgNPs. The determination of BSA was achieved by measuring the change of λ(max) corresponding to localized surface plasmon resonance (LSPR) from UV-visible spectrophotometry. It was found that the shift value in the wavelength of absorption maximum (Δλ, the difference in absorption maxima of the TAgNPs/BSA/BR mixture and the TAgNPs/BR mixture) was proportionate to the concentration of BSA in the range of 1.0 ng mL(-1) to 100.0 ng mL(-1) with the correlation coefficient of r=0.9969. The detection limit (3 σ/k) for BSA was found to be as low as 0.5 ng mL(-1).

Visual detection of trace copper ions based on copper-catalyzed reaction of ascorbic acid with oxygen.

A visual detection method for trace Cu(2+) in aqueous solutions using triangular silver nanoplates (abbreviated as TAgNPs) as the probe was developed. The method is based on that TAgNPs could be corroded in sodium thiosulfate (Na2S2O3) solutions. The absorption spectrum of TAgNPs solution changed when it is corroded by Na2S2O3. The reaction of oxygen with ascorbic acid (Vc) in the presence of a low concentration of Cu(2+) generates hydrogen peroxide that reacts with Na2S2O3, which leads the concentration of Na2S2O3 in the solution to be decreased. Therefore, the reaction between TAgNPs and the reacted mixture of Na2S2O3/Vc/Cu(2+) was prevented efficiently. When the Na2S2O3 concentration and reaction time are constant, the decrease in the concentration of Na2S2O3 is directly proportional to the Cu(2+) concentration. Thus, morphology, color, and maximum absorption wavelength of TAgNPs changed with the change of Cu(2+) concentration. The changed maximum absorption wavelength of TAgNPs (Δλ) is proportional to Cu(2+) concentration in the range from 7.5×10(-9) to 5.0×10(-7) M with a correlation coefficient of r=0.9956. Moreover, color change of TAgNP solution was observed clearly over a Cu(2+) concentration range from 7.5×10(-8) to 5.0×10(-7) M. This method has been used to detect the Cu(2+) content of a human hair sample, and the result is in agreement with that obtained by the atomic absorption spectroscopy (AAS) method.

Visual determination of trace cysteine based on promoted corrosion of triangular silver nanoplates by sodium thiosulfate.

In this study, triangular silver nanoplates (TAg-NPs) were used to detect trace Cysteine concentration in the presence of sodium thiosulfate (Na2S2O3). Study showed that the TAg-NPs could be gently etched by Cysteine with the concentration of 1.0×10(-7) mol L(-1) through forming Ag-S covalent bond at the three corners. However, in the presence of Na2S2O3 (only 3.0×10(-6) mol L(-1)), the corrosion of Cysteine on TAg-NPs can be promoted significantly. It was also found that the color, morphology, and the maximum absorption wavelength of TAg-NPs change clearly with the concentrations of Cysteine as low as 2.5×10(-8) mol L(-1). Furthermore, the wavelength shift values (Δλ) of TAg-NPs solution were proportional to the concentrations of Cysteine in the range of 1.0×10(-9)-1.0×10(-7) mol L(-1), and the linear regression equation is Δλ=-0.89+319.94 c (c, µM, n=5) with the correlation coefficient of 0.990. At the same time, the color change of the TAg-NPs solution could be observed clearly by the naked eyes with increasing Cysteine concentrations in the range of 2.5×10(-8)-1.0×10(-7) mol L(-1). Thus, a novel method for the detection of Cysteine by either UV-vis spectrophotometry detection or naked eyes observation is established. It allows determination of Cysteine content in compound amino acid injection sample of 18AA-V.

Observable temperature-dependent compaction-decompaction of cationic polythiophene in the presence of iodide.

Investigation on compaction and decompaction of polymers is very important since it is a fundamental problem in polymer physics. With the aids of atomic force microscope (AFM) and dynamic light scattering (DLS) measurements in this contribution, the temperature-dependent compaction/decompaction transition process of water-soluble cationic polythiophene (PT) was investigated in the presence of KI. The above process is characterized by the red-to-yellow color change and fluorescence recovery and is reversible during the heating-cooling cycles in the range from 25 to 55 °C, indicating that the compaction and decompaction of polymer can be employed as a temperature indicator.

A sensitive resonance light scattering spectrometry of trace Hg2+ with sulfur ion modified gold nanoparticles.

A new resonance light scattering (RLS) spectrometric method for mercury ions (Hg(2+)) in aqueous solutions with sulfur ion (S(2-)) modified gold nanoparticles (Au-NPs-S) has been developed in this contribution. It was found that S(2-) at the surface of Au-NPs resulting from the surface modification can interact with Hg(2+) to form very stable S-Hg-S bonds when Hg(2+) concentration is lower than that of S(2-), resulting in the aggregation of Au-NPs-S and causing enhanced RLS signals. The enhanced RLS intensities (DeltaI(RLS)) characterized at 392 nm were found to be proportional to the concentration of Hg(2+) in the range of 0.025-0.25 micromol L(-1) with a detection limit (3sigma) of 0.013 micromol L(-1). Our results showed that this approach has excellent selectivity for Hg(2+) over other substances in aqueous solutions.

A visual test paper for extremely strong concentrated acidity with a new synthesized isoindole reagent.

A visual test paper by taking common filter paper as solid support for extremely strong concentrated acidity has been developed in this contribution with a new synthesized isoindole compound starting from p-phenylenediamine and the coupled fluorogenic reagent of o-phthaldialdehyde-beta-mercaptoethanol. It was very easy for semiquantitative detection of acidity in the range of 0.2-18 M ([H(+)]) in extreme acidic solution based on the color changes of the solution or the visual test paper prepared by immerging filter paper slides into the solution of the new synthesized reagent. Quantitative detection of concentrated strong acids could be successfully constructed through the linear relationship exists between the absorbance of the chromogenic reagent at 510 nm and the acid concentrations.

Selectively light scattering spectrometric detection of copper (II) based on a new synthesized oxamide ligand.

Light scattering (LS) signals have been applied for analytical detections, but the selectivity is poor. In order to improve the selectivity, pre-separation or new machines are generally considered. Differing from these methods, we synthesized a highly selective oxamide ligand, N',N'-bis (2-aminophenyl) oxamide (NAPO). It was found that the LS signals of NAPO, measured with a common spectrofluorometer, could be selectively enhanced by copper ion in neutral medium. Thus, a new highly selective detection method for copper ion could be developed over the range of 0.9-31.0 microM with the limit of determination of 97.6 nM (3sigma). Foreign ions including Cd(II), Al(III) could be allowed even if present at the level of 7-fold more than that of Cu(2+), avoiding pre-separation procedures from complicated samples such as real wastewater samples. Mechanism studies showed that the reaction between NAPO and copper ion could form some kinds of clusters and induce the enhanced LS signals.

Tryptophan-contained peptide-functional nanomaterials as general spectrofluorometric reagents for enzyme.

By designing and coupling a functional peptide, Gly-Leu-Ala-Cys-Ser-Gly-Phe-Pro-Arg-Gly-Arg-Trp, which could be cleaved by thrombin at the site of Arg-Gly (R-G), to the surface of gold nanoparticles (Au-NPs), we propose a simple spectrofluorometry for thrombin (TRB) in this contribution. Experiments showed that the peptide coupled to the surface of Au-NPs in a Tris-HCl buffer at 37 degrees C could be cleaved, leaving the fluorescent fragment of Gly-Arg-Trp in the Au-NPs suspension. By centrifuging the suspension and measuring the fluorescence signals resulting from the Trp residue of Gly-Arg-Trp fragment in the supernatant, we found that the fluorescence intensity is proportional to thrombin concentrations in the range of 1-100 nM with the limit of the detection of 0.1 nM. Since there are a lot of enzymes that can hydrolyze peptide with special sequence, and novel nanomaterials that can bind with the tryptophan-contained peptide and understand centrifugation, this spectrofluorometric method is general and it is possible to develop a variety of detection method for target enzymes.

Conformational change detection of DNA with the fluorogenic reagent of o-phthalaldehyde-beta-mercaptoethanol.

o-Phthalaldehyde-beta-mercaptoethanol (OPAME) as a fluorogenic reagent has been found wide applications in the detection of amino acids based on its reaction with primary amino groups. In this contribution, we report our new findings concerning the reactions of OPAME with single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA), respectively. It has been found that ssDNA can react with OPAME easily as a result of giving rise to strong fluorescence emissions, while dsDNA, prepared by hybridizing ssDNA with its complementary target prior to the reaction, displays inert chemical activity and gives out weak fluorescence emission. Mechanism investigations have shown that the reaction activity between OPAME and DNA depends on the amino groups that are related to the conformation of uncoiled and exposed extent of DNA structure, and thus the inert chemical activity of dsDNA results from screening of the dsDNA bases in the interior of the double strands. Therefore, we could design a way to detect conformation change of DNA with OPAME and further develop a novel, simple label-free sequence detection method for complementary and single-base mismatched ssDNA in the hybridization of DNA.

Hybridization detection of DNA by measuring organic small molecule amplified resonance light scattering signals.

The interaction of organic small molecules (OSMs) with a biological molecule is very important. In this contribution, quinone-imine dyes including Acridine Yellow (AY), Neutral Red (NR), Acridine Orange (AO), Brilliant Cresyl Blue (BCB), Thionin (TN), Azur A (AA), Azur B (AB), and Methylene Blue (MB) respectively with double strand DNA (dsDNA) and single strand DNA (ssDNA) were investigated based on the measurements of enhanced resonance light scattering (RLS) and TEM. Mechanism investigations have shown that groove binding occurs between dsDNA and these OSMs, which depends on G-C sequences of dsDNA and the volumes of OSMs. With the amplified RLS signals resulting from the interactions of OSMs with DNA, a new technique has been proposed to detect the hybridization and mismatch of DNA labeling neither the target nor the probe DNA. The results have suggested that the extent of the amplified RLS signals of dsDNA by AY is the maximum among these eight OSMs, and therefore, it has been selected as a typical model system for further discussions.

Spectral studies on the interaction of Amido black 10B with DNA in the presence of cetyltrimethylammonium bromide.

The interaction of Amido black 10B (AB) with DNA in basic medium was studied in the presence of cetyltrimethylammonium bromide (CTMAB) based on the measurements of resonance light scattering (RLS), UV-vis, CD spectra, and RLS imaging. The interaction has been proved to give a ternary complex of CTMAB-DNA-AB in Britton-Robinson buffer of pH 11.55, which exhibits strong negative Cotton effect at 233.3nm and 642.8nm, and strong RLS signals characterized at 469nm. Experiments showed that the enhanced RLS intensities (DeltaI(RLS)) against the mixture of AB and CTMAB are proportional to the concentration of fish sperm DNA (fsDNA) and calf thymus DNA (ctDNA), respectively over the range of 0.03-1.0 and 0.05-1.5microg ml(-1), with the limits of determination (3sigma) of 7.3ng ml(-1) for fsDNA and 7.0ng ml(-1) for ctDNA.

Enhanced plasmon resonance light scattering signals of colloidal gold resulted from its interactions with organic small molecules using captopril as an example.

Gold nanoparticles are known for their plasmon resonance absorption (PRA) depending on their size. Our this investigation shows that plasma resonance light scattering (PRLS) signals in the corresponding PRA region could be measured using a common spectrofluorometer, and be enhanced when aggregation of gold nanoparticles occurs due to their interaction with organic small molecules (OSMs). Using captopril (Cap) as an example, we investigated the interactions of gold nanoparticles with OSMs in order to propose a general method of OSMs such as typical clinic organic drugs. In aqueous medium of pH 2.09, there are about 2.2 x 10(3) Cap molecules covalently binding to the surface of a 10-nm diameter gold nanoparticle through the thiol functional group of Cap, and thus forms a core-shell assembly of [(Au)(31000)]@[(Cap)(2200)], displaying strong enhanced PRLS signals in the PRA region of gold colloid. The PRLS intensities characterized at 553.0 nm were found to be proportional to the concentration of Cap over the range of 0.1-1.7 mg L(-1) with the determination limit (3sigma) of 32.0 microg L(-1). With that, Cap in pharmaceutical preparations could be determined with the recovery of 97.0-104.5% and R.S.D. of less than 2.4%.

A dual-wavelength resonance light scattering ratiometry of biopolymer by its electrostatic interaction with surfactant.

A dual-wavelength resonance lighting scattering (DW-RLS) ratiometry is developed to detect anion biopolymer based on their bindings with cation surfactant. Using the interaction of Hyamine 1622 (HM) with fish sperm DNA (fsDNA) as an example, a dual-wavelength resonance light scattering (DW-RLS) ratiometric method of DNA was constructed. In Britton-Robinson buffer controlled medium, fish sperm DNA (fsDNA) could interact with Hyamine 1622 (HM), displaying significantly enhanced RLS signals. By measuring the RLS signals characterized at 300.0nm (I(300.0)) and the RLS intensity ratio (I(276.0)/I(294.0)), respectively, fsDNA over a wide dynamic range of content could be detected. Typically, when HM concentration is kept at 6.0x10(-5)moll(-1), using I(300.0) could detect fsDNA over the range of 50-2000ngml(-1) with the limit of 3.0ngml(-1), while using I(276.0)/I(294.0) could detect fsDNA over the range of 0.5-2500ngml(-1) with the limit of 0.05ngml(-1). Thus the latter so-called DW-RLS ratiometry is obviously superior to the former one. Based on the measurements of I(300.0) and I(276.0)/I(294.0) data, a Scatchard plot concerning the interaction between HM and fsDNA could be constructed and thus the binding number (n) and binding constant (K) could be available with the values of 13.5 and 1.35x10(5)mol(-1)l, and 11.9 and 1.65x10(5)mol(-1)l, respectively.