23 research outputs found
Copper-catalyzed enantioselective conjugate reduction of alpha,beta-unsaturated esters with chiral phenol-carbene ligands
A chiral phenol-NHC ligand enabled the copper-catalyzed enantioselective conjugate reduction of alpha,beta-unsaturated esters. The phenol moiety of the chiral NHC ligand played a critical role in producing the enantiomerically enriched products. The catalyst worked well for various (Z)-isomer substrates. Opposite enantiomers were obtained from (Z)- and (E)-isomers, with a higher enantiomeric excess from the (Z)-isomer
Low-Temperature Direct Synthesis of Multilayered h‑BN without Catalysts by Inductively Coupled Plasma-Enhanced Chemical Vapor Deposition
Low-temperature direct
synthesis of thick multilayered
hexagonal-boron
nitride (h-BN) on semiconducting and insulating substrates is required
to produce high-performance electronic devices based on two-dimensional
(2D) materials. In this study, multilayered h-BN with a thickness
exceeding 5 nm was directly synthesized on quartz and Si at low temperatures,
between 400 and 500 °C, by inductively coupled plasma-enhanced
chemical vapor deposition using borazine as the precursor material.
The quality and thickness of the h-BN crystals were investigated with
respect to synthesis parameters, namely, temperature, radio frequency
power, N2 flow rate, and H2 flow rate. Introducing
N2 and H2 carrier gases critically affected
the deposition rate, and increasing the carrier gas flow rate enhanced
the h-BN crystal quality. The typical optical band gap of synthesized
h-BN was approximately 5.8 eV, consistent with that of previous studies.
The full width at half-maximum of the h-BN Raman peak was 32–33
cm–1, comparable to that of commercially available
multilayered h-BN on Cu foil. These results are expected to facilitate
the development of 2D materials for electronics applications
Interactions between serum vitamin D levels and vitamin D receptor gene FokI polymorphisms for renal function in patients with type 2 diabetes.
We aimed to examine associations among serum 25-hydroxyvitamin D (25OHD) levels, 1,25-dihyroxyvitamin D (1,25OHD) levels, vitamin D receptor (VDR) polymorphisms, and renal function based on estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes.In a cross-sectional study of 410 patients, chronic kidney disease (CKD) stage assessed by eGFR was compared with 25OHD, 1,25OHD, and VDR FokI (rs10735810) polymorphisms by an ordered logistic regression model adjusted for the following confounders: disease duration, calendar month, use of angiotensin converting enzyme inhibitors/angiotensin receptor blockers or statins, and serum calcium, phosphate, and intact parathyroid hormone levels.1,25OHD levels, rather than 25OHD levels, showed seasonal oscillations; peak levels were seen from May to October and the lowest levels were seen from December to February. These findings were evident in patients with CKD stage 3 ~ 5 but not stage 1 ~ 2. eGFR was in direct proportion to both 25OHD and 1,25OHD levels (P<0.0001), but it had stronger linearity with 1,25OHD (r = 0.73) than 25OHD (r = 0.22) levels. Using multivariate analysis, 1,25OHD levels (P<0.001), but not 25OHD levels, were negatively associated with CKD stage. Although FokI polymorphisms by themselves showed no significant associations with CKD stage, a significant interaction between 1,25OHD and FokITT was observed (P = 0.008). The positive association between 1,25OHD and eGFR was steeper in FokICT and CC polymorphisms (r = 0.74) than FokITT polymorphisms (r = 0.65).These results suggest that higher 1,25OHD levels may be associated with better CKD stages in patients with type 2 diabetes and that this association was modified by FokI polymorphisms