Silicon@porous nitrogen-doped carbon spheres through a bottom-up approach are highly robust lithium-ion battery anodes

Due to its excellent capacity, around 4000 mA h g(-1), silicon has been recognized as one of the most promising lithium-ion battery anodes, especially for future large-scale applications including electrical vehicles and utility power grids. Nevertheless, Si suffers from a short cycle life as well as limitations for scalable electrode fabrication. Herein, we report a novel design for highly robust and scalable Si anodes: Si nanoparticles embedded in porous nitrogen-doped carbon spheres (NCSs). The porous nature of NCSs buffers the volume changes of Si nanoparticles and thus resolves critical issues of Si anode operations, such as pulverization, vulnerable contacts between Si and carbon conductors, and an unstable solid-electrolyte interphase. The unique electrode structure exhibits outstanding performance with a gravimetric capacity as high as 1579 mA h g(-1) at a C/10 rate based on the mass of both Si and C, a cycle life of 300 cycles with 94% capacity retention, as well as a discharge rate capability of 6 min while retaining a capacity of 702 mA h g(-1). Significantly, the coulombic efficiencies of this structure reach 99.99%. The assembled structure suggests a design principle for high capacity alloying electrodes that suffer from volume changes during battery operations.

Selection of Small Synthetic Antimicrobial Peptides Inhibiting Xanthomonas citri subsp. citri Causing Citrus Canker

Citrus canker disease decreases the fruit quality and yield significantly, furthermore, emerging of streptomycin-resistant pathogens threatens the citrus industry seriously because of a lack of proper control agents. Small synthetic antimicrobial peptides (AMPs) could be a promising alternative. Fourteen hexapeptides were selected by using positional scanning of synthetic peptide combinatorial libraries. Each hexapeptide showed different antimicrobial spectrum against Bacillus, Pseudomonas, Xanthomonas, and Candida species. Intriguingly, BHC10 showed bactericidal activity exclusively on Xanthomonas citri subsp. citri (Xcc), while BHC7 was none-active exclusively against two Pseudomonas spp. at concentration of 100 μg/ml suggesting potential selectivity constrained in hexapeptide frame. Three hexapeptides, BHC02, 06 and 11, showed bactericidal activities against various Xcc strains at concentration of 10 μg/ml. When they were co-infiltrated with pathogens into citrus leaves the disease progress was suppressed significantly. Further study would be needed to confirm the actual disease control capacity of the selected hexapeptides

Improvement of lignin oil properties by combination of organic solvents and formic acid during supercritical depolymerization

Supercritical treatment of ethanol organosolv lignin was conducted to produce lignin-derived bio-oil. The reaction was performed at 350 °C for 40 min with 3 MPa hydrogen gas pressure. To improve the yield of lignin oil and inhibit repolymerization during supercritical treatment, formic acid was added to the solvent. The effect of formic acid was examined by gas chromatography mass spectrometry (GC/MS), gel permeation chromatography (GPC), and elemental analysis. The maximum yield of lignin oils was shown to reach up to 70 wt% with the addition of formic acid. When 7% formic acid was used, the resulting lignin oil exhibited the highest monomer content at approximately 56 mg/g and the lowest oxygen/carbon molar ratio (O/C) of 0.26. The main degradation products in the lignin oil were syringol, 4-methylsyringol, and p-cresol. The lignin oil contained a larger proportion of syringyl unit monomers than guaiacyl because yellow poplar is hardwood, consisting primarily of syringyls. The molecular weight of lignin oils increased with the addition of formic acid since lignin-derived oligomers were also produced. Meanwhile, experiments were performed using methanol and isopropanol to investigate the relationship between the solvent type and lignin depolymerization. Isopropanol led to a higher yield of lignin oil compared to ethanol, but amounts of monomeric products were much lower. Therefore, supercritical ethanol treatment with 7% formic acid under pressure from hydrogen gas is considered to be more effective when compared to other conditions, and this procedure demonstrated the possibility for better production of lignin-derived products during thermal decomposition reactions.This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (NRF-2012R1A1A2008592).OAIID:RECH_ACHV_DSTSH_NO:T201623481RECH_ACHV_FG:RR00200001ADJUST_YN:EMP_ID:A079993CITE_RATE:3.652DEPT_NM:국제농업기술학과EMAIL:[email protected]_YN:YCONFIRM:

Study on Improvement of Surface Properties of Low Carbon Steel Using Laser Cladding

Laser cladding is a method that can be applied to repair the crack and break on the mold and die surfaces, as well as generate new attributes on the surface to improve toughness, hardness, and corrosion resistance. It is used to extend the life of the mold. It also has the advantages of superior bonding strength and precision coating on a local area compared with the conventional thermal spraying technology. In this study, we investigated the effect of cladding on low carbon alloy steel using 18%Cr-2.5%Ni-Fe powder (Rockit404), which showed high hardness on the die surface. The process conditions were performed in an argon atmosphere using a diode laser source specialized for 900-1070 nm, and the output conditions were 5, 6, and 10 kW, respectively. After the cladding was completed, the surface coating layer’s shape, the hardness according to the cross-section’s thickness, and the microstructure were analyzed

Influence of the Precipitation of Secondary Phase on the Thermal Diffusivity Change of Al-Mg₂Si Alloys

Al-Si-Mg alloys are investigated to determine the relationship between changes in the thermal diffusivity and precipitation behavior of the Mg2Si phase with various contents of Mg2Si and aging treatment conditions. The samples were solid solution-treated and then quenched with water (80 °C). Aging treatments were implemented at temperatures ranging from 180 to 240 °C for 5 h. The precipitation behavior of Mg2Si was observed using a heat flow curve using differential scanning calorimetry analysis. The thermal diffusivity of Al-Mg2Si alloy was affected by the precipitation of the Mg2Si phase, particularly in the meta-stable β phase. In the temperature range of precipitation occurrence, the thermal diffusivity of the alloy increased with the temperature when the precipitation of the meta-stable β phase of the sample was incomplete. However, at the same temperature, the samples in which precipitation had completed did not have any increased thermal diffusivity. The thermal diffusivity of the samples decreased when the meta-stable Mg2Si phase had dissolved in the matrix. The precipitation and dissolution of Mg2Si mainly affected the variation of thermal diffusivity in Al-Si-Mg. In contrast, the stable Mg2Si phase was not affected by changes in thermal diffusivity at a high temperature

Serum glycated albumin as a new glycemic marker in pediatric diabetes

PurposeSerum glycated albumin (GA) has been recently used as another glycemic marker that reflects shorter term glycemic control than glycated hemoglobin (HbA1c). Insulin secretory function and glycemic fluctuation might be correlated with the ratio of GA to HbA1c (GA/HbA1c) in diabetic adult patients. This study investigated the association of GA and GA/HbA1c ratio with the levels of fasting C-peptide, fasting plasma glucose in type 1 and type 2 pediatric diabetes.MethodsTotal 50 cases from 42 patients were included. The subjects were classified into type 1 diabetes mellitus (T1DM) (n=30) and type 2 diabetes mellitus (T2DM) (n=20) group. The associations among HbA1c, GA, and GA/HbA1c ratio were examined. The relationship between the three glycemic indices and fasting glucose, fasting C-peptide were analyzed.ResultsMean values of GA, the GA/HbA1c ratio were significantly higher in T1DM than T2DM. GA (r=0.532, P=0.001), HbA1c (r=0.519, P=0.002) and the GA/HbA1c ratio (r=0.409, P=0.016) were correlated with the fasting plasma glucose. Fasting C-peptide level arranged 4.22±3.22 ng/mL in T2DM, which was significantly above the values in T1DM (0.26±0.49 ng/mL). There were no significant correlation between HbA1c and fasting C-peptide level. However, GA and the GA/HbA1c ratio exhibited inverse correlations with fasting C-peptide level (r=-0.214, P=0.002; r=-0.516, P<0.001).ConclusionGA seems to more accurately reflects fasting plasma glucose level than HbA1c. GA, GA/HbA1c ratio appear to reflect insulin secretory function