Synthesis of cyclic carbonate from allyl glycidyl ether and CO2 over silica-supported ionic liquid catalysts prepared by sol-gel method

A silica-supported ionic liquid (Im-IL) was proven to be an effective heterogeneous catalyst for solventless synthesis of cyclic carbonate from allyl glycidyl ether (AGE) and carbon dioxide. Im-IL catalysts were prepared by sol-gel method. The synthesis of cyclic carbonate from AGE and CO₂ was carried out in a batch autoclave reactor. Im-IL with shorter alkyl chain length showed the highest conversion of AGE, probably due to the steric hindrance for the formation of intermediate from the catalyst prepared by using longer alkyl chains and AGE. High temperature and high pressure were favorable for the conversion of AGE. Im-IL can be reused for the reaction up to two consecutive runs without any considerable loss of its catalytic activity.     

An 8b 250MS/s 0.13μm CMOS ADC using variable references for VGA-to-WUXGA scaler chips

This work proposes an 8b 250MS/s 0.13??m CMOS two-step pipeline ADC using variable references for VGA-to-WUXGA scaler chip applications. The input sample-and-hold amplifier employs MOS capacitor-based gate-bootstrapping circuits to keep the on-resistance of sampling switches constant and to sample wide-band wide-range variable inputs with least distortion. The capacitors of the proposed multiplying D/A converter are laid out in a high matching one-dimensional symmetric shape rather than the conventional common-centroid topology to save chip area. The proposed on-chip current and voltage reference circuits generate variable bottom-side reference voltages with a fixed top-side reference using a single external voltage for processing wide-range variable analog inputs. The two-step reference selection scheme reduces considerably power and area in the last-stage 5b flash ADC. The prototype ADC in a 0.13??m CMOS demonstrates measured differential and integral non-linearities within 0.35 and 0.54 LSB, respectively. The ADC shows a maximum SNDR and SFDR of 44.4 and 56.1?dB at 250?MS/s, respectively. The ADC with an active die area of 0.72?mm² consumes 58.8?C62.4?mW depending on input modes at 250?MS/s and 1.2?V.     

Protective effects of chebulic acid from Terminalia chebula Retz. against t-BHP-induced oxidative stress by modulations of Nrf2 and its related enzymes in HepG2 cells

Food Science and Biotechnology - Although chebulic acid isolated from Terminalia chebular has diverse biological effects, its effects on the expression of nuclear factor erythroid 2-related factor...     

Effect of cocatalyst and carbon dioxide pressure on the synthesis of polycarbonate from phenyl glycidyl ether and carbon dioxide

The copolymerization of phenyl glycidyl ether (PGE) and carbon dioxide was performed in the presence of ionic liquid catalyst. 1-Butyl-3-methyl imidazolium chloride, tetrabutylamouim chloride and 1-n-butylpyridinium chloride were used as catalyst for this reaction carried out in a batch reactor. All the ionic liquid catalysts showed good catalytic activity for the synthesis of polycarbonates with very low polydispersity, close to 1. The carbonate content, turnover number (TON), and average molecular weight of the copolymer were affected by the structure of the ionic liquid. High carbon dioxide pressure enhanced TON and carbonate content because of the increase of carbon dioxide absorption in PGE solution. ZnBr₂ and a Zn-Co cyanide complex were also tested as a catalyst and/or cocatalyst for this reaction to compare their catalytic performance with the imidazolium salt ionic liquids.     

Differentiation of lactic acid bacteria based on RFLP analysis of the tuf gene

The tuf gene, which encodes the elongation factor Tu, is universally distributed in Gram-positive bacteria. A small region of the tuf gene was evaluated for the differentiation of Lactobacillus strains using restriction fragment length polymorphism (RFLP) analysis. The 803 bp portion of tuf genes from 9 closely-related Lactobacillus reference strains were successfully amplified by polymerase chain reaction (PCR), and restriction patterns of each were evaluated with a set of restriction enzymes, which included AluI, HaeIII, and Sau3AI. The results implied that restriction patterns obtained from 2 of these restriction enzymes (AluI and HaeIII) could effectively differentiate closely-related Lactobacillus species.     

Caffeic Acid Phenethyl Ester-Incorporated Radio-Sensitive Nanoparticles of Phenylboronic Acid Pinacol Ester-Conjugated Hyaluronic Acid for Application in Radioprotection

We synthesized phenylboronic acid pinacol ester (PBPE)-conjugated hyaluronic acid (HA) via thiobis(ethylamine) (TbEA) linkage (abbreviated as HAsPBPE conjugates) to fabricate the radiosensitive delivery of caffeic acid phenetyl ester (CAPE) and for application in radioprotection. PBPE was primarily conjugated with TbEA and then PBPE-TbEA conjugates were conjugated again with hyaluronic acid using carbodiimide chemistry. CAPE-incorporated nanoparticles of HAsPBPE were fabricated by the nanoprecipitation method and then the organic solvent was removed by dialysis. CAPE-incorporated HAsPBPE nanoparticles have a small particle size of about 80 or 100 nm and they have a spherical shape. When CAPE-incorporated HAsPBPE nanoparticles were irradiated, nanoparticles became swelled or disintegrated and their morphologies were changed. Furthermore, the CAPE release rate from HAsPBPE nanoparticles were increased according to the radiation dose, indicating that CAPE-incorporated HAsPBPE nanoparticles have radio-sensitivity. CAPE and CAPE-incorporated HAsPBPE nanoparticles appropriately prevented radiation-induced cell death and suppressed intracellular accumulation of reactive oxygen species (ROS). CAPE and CAPE-incorporated HAsPBPE nanoparticles efficiently improved survivability of mice from radiation-induced death and reduced apoptotic cell death. We suggest that HAsPBPE nanoparticles are promising candidates for the radio-sensitive delivery of CAPE.     

A mismatch-error minimized four-channel time-interleaved 11 b 150 MS/s pipelined SAR ADC

This work proposes a four-channel time-interleaved 11 b 150 MS/s pipelined SAR ADC based on various analog techniques to minimize mismatches between channels without any calibration scheme. The proposed ADC eliminates an input SHA to reduce offset mismatches, while the pipelined SAR architecture solves the problem of limited input bandwidth as observed in conventional SHA-free ADCs. In addition, a shared residue amplifier between four channels minimizes various mismatches caused by amplifiers in the first-stage MDACs. Two types of references for the residue amplifier and the SAR ADCs isolate the reference instability problem due to different functional requirements, while the shared residue amplifier uses only a single reference during the amplifying mode of each channel to reduce a gain mismatch. For high performance of the SAR ADC, high-frequency clocks with a controllable duty cycle are generated on chip without external, complicated, high-speed multi-phase clocks. The prototype 11 b ADC in a 0.13 μm CMOS shows a measured DNL and INL of 0.31 LSB and 1.18 LSB, respectively, with an SNDR of 59.3 dB and an SFDR of 67.7 dB at 100 MS/s, and an SNDR of 54.5 dB and an SFDR of 65.5 dB at 150 MS/s. The ADC with an active die area of 2.42 mm² consumes 46.8 mW at 1.2 V and 150 MS/s.     

Changes in the phenolic compounds and antioxidant activities of mustard leaf (<Emphasis Type="Italic">Brassica juncea</Emphasis>) kimchi extracts during different fermentation periods

This study was conducted to investigate the changes in the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities of 80% methanol and water extracts from mustard leaf kimchi during different fermentation periods. The methanol extract exhibited higher TPC and TFC than the water extract. Both extracts from kimchi fermented for two months showed the highest antioxidant effects against the scavenging activities of 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radicals and 2,2-azino-bis diammonium salt (ABTS) radicals. Moreover, the methanol extract from kimchi fermented for two months showed the highest nitrite scavenging activity. The highest metal (Fe²⁺) chelating effect of the methanol extract and water extract was observed after three months and one month, respectively. Caffeic acid showed the highest increase with fermentation. These findings suggest that the antioxidant activities of kimchi depend on the fermentation period. Accordingly, this study provides basic data for improving the antioxidant activity of mustard leaf kimchi through the establishment of their fermentation period.