This paper presents a novel integrated-stage light-emitting diode (LED) driver based on Flyback and resonant converters. The Flyback converter realizes power factor correction in the discontinuous conduction mode. The resonant converter is operated as a dc-dc converter to support the LED loads. Moreover, the resonant converter can clearly decrease the drain-source voltage of the active switch and exhibits zero-voltage-switch characteristics. Therefore, a cost-effective MOSFET can be chosen as the main control component that can decrease the cost of the whole system. Compared to a single-active-switch converter (such as Class-E converter), the number of passive components in the resonant converter can be limited to four. Therefore, the power density of the system can be improved drastically. In this paper, a 100-W prototype is presented under the experimental condition to validate the proposed integrated-stage LED driver.

A novel family of high-gain dc/dc converters based on Y-source impedance network is proposed in this paper providing novel solutions to high voltage gain applications, such as photovoltaic and fuel cell systems. Proposed converters combine Y-source with boost modules resulting in strong boost ability, continuous input current, and inrush current suppression. Design flexibility and joint earthing of input and source are inherited from conventional Y-source. Working principles are presented and accurate steady-state analysis is conducted by mathematical derivations, moreover, comparisons among proposed converters and other impedance networks highlight their excellent performance. Experimental results show good agreement with theoretical analysis and the high feasibility of the proposed converters.

The process development and kilogram-scale synthesis of beclabuvir (BMS-791325, 1) is described. The convergent synthesis features the use of asymmetric catalysis to generate a chiral cyclopropane fragment and coupling with an indole fragment via an alkylation. Subsequent palladium-catalyzed intramolecular direct arylation efficiently builds the central seven-membered ring. The target was prepared in 12 linear steps with five isolations in an overall yield of 8%.

A strategy to prepare compounds with multiple chirality axes, which has led to a concise total synthesis of compound 1A with complete stereocontrol, is reported.

In this paper, a high step up converter consisting of an integrated quadratic-boost converter and a voltage doubler is proposed. The integration of the quadratic-boost converter makes the system easier to lift up its voltage gain through slightly increasing the duty ratio of the single switch. The voltage doubler further increases the voltage gain of the system as the turn ratio rises. The voltage stresses on the switch and the diodes are decreased for such cascaded topology. Different operation modes are analyzed and mathematical analysis of the converter is presented in detail. The leakage inductance contributes to realizing zero current switching of the diodes in the second boost stage and the doubler and the energy can be recycled to the load. A 38-W prototype is built to work as a vehicle LED driver. Experiments are conducted to verify the advantages of the proposed converter and the efficiency is 90% at the nominal operating point.

The development of a scalable process for the Rh-catalyzed asymmetric 1,4-addition of (isopropenyl)pinacolboronate to 2-cyclohexen-1-one is reported. High-throughput ligand screening and initial optimization studies identified DTBM-SEGPHOS as an effective ligand along with a heptane/MeOH mixed solvent system. An inhibitory effect of the pinacol byproduct was identified, which could be mitigated by the addition of a 1,3-diol such as neopentyl glycol (npg). This process was demonstrated on 1 kg scale with 0.6 mol % Rh, producing (S)-1 in 82% yield and 99.6% ee, and was successfully scaled up at a vendor on 100 kg scale.

This paper presents an integrated-stage AC-DC LED driver based on Flyback and Class-E converter with high power factor. The Flyback circuit works in discontinuous conduction mode (DCM) to realize the power factor correction (PFC) function, and the Class-E circuit is used as DC-DC converter to transform the energy to the LED load. The integrated topology can decrease the cost of system. Moreover, the Class-E converter provides soft switching operation in resonant mode, which can improve the converter efficiency. The active switch is operated with constant duty radio and pulse frequency modulation (PFM). A 100W prototype is presented in experimental condition to certify the validity of the proposed integrated-stage LED driver.

Drought stress is a severe environmental factor that greatly restricts plant distribution and crop production. Recently, we have found that overexpressing AtWRKY57 enhanced drought tolerance in Arabidopsis thaliana. In this study, we further reported that the Arabidopsis WRKY57 transcription factor was able to confer drought tolerance to transgenic rice (Oryza sativa) plants. The enhanced drought tolerance of transgenic rice was resulted from the lower water loss rates, cell death, malondialdehyde contents and relative electrolyte leakage while a higher proline content and reactive oxygen species-scavenging enzyme activities was observed during stress conditions. Moreover, further investigation revealed that the expression levels of several stress-responsive genes were up-regulated in drought-tolerant transgenic rice plants, compared with those in wild-type plants. In addition to the drought tolerance, the AtWRKY57 over-expressing plants also had enhanced salt and PEG stress tolerances. Taken together, our study indicates that over-expressing AtWRKY57 in rice improved not only drought tolerance but also salt and PEG tolerance, demonstrating its potential role in crop improvement.

A tritydopropylamino acid derivative was prepared via Simmons-Smith cyclopropanation of the corresponding alkene. This transformation was plagued by inconsistent conversions, and the opportunity for the removal of the structurally similar alkene contaminant at this stage and downstream via crystallization was limited. These factors combined to make control of the alkene impurity level in the active pharmaceutical ingredient (API) difficult. A removal strategy was developed that utilized downstream, in-process aminoacetoxylation to convert the alkene impurity to structurally dissimilar compounds that purged during crystallization. Using this protocol, the alkene contaminant in the subsequent intermediates, and thus the API, could be controlled to less than 0.1 area percent.

Kinetic, spectroscopic, crystallographic, and computational studies probing a Pd-catalyzed C-H arylation reaction reveal that mono-oxidation of the bis-phosphine ligand is critical for the formation of the active catalyst. The bis-phosphine mono-oxide is shown to be a hemilabile, bidentate ligand for palladium. Isolation of the oxidative addition adduct, with structural elucidation by X-ray analysis, showed that the mono-oxide was catalytically competent, giving the same reaction rate in the productive reaction as the Pd(II)/xantphos precursor. A dual role for the carboxylate base in both catalyst activation and reaction turnover was demonstrated, along with the inhibiting effect of excess phosphine ligand. The generality of the role of phosphine mono-oxide complexes in Pd-catalyzed coupling processes is discussed.

Air- and moisture-stable nickel(II) complexes 2a-c of CNC pincer-type N-heterocyclic carbene ligands have been prepared from the corresponding imidazolium salts by carbene-transfer reaction of a silver-NHC complex with Ni(DME)Cl-2 (DME = dimethoxylethane). Pincer complexes 2a-c are characterized by mass and NMR spectroscopy. The structure of 2a is also identified by X-ray diffraction analysis. Pincer complex 2a has been shown to be active catalyst for the Suzuki coupling reactions. (C) 2015 Elsevier B.V. All rights reserved.

In a recent disclosure,1 we described the discovery of dimeric, prolinamide-based NS5A replication complex inhibitors exhibiting excellent potency towards an HCV genotype 1b replicon. That disclosure dealt with the SAR exploration of the peripheral region of our lead chemotype, and herein is described the SAR uncovered from a complementary effort that focused on the central core region. From this effort, the contribution of the core region to the overall topology of the pharmacophore, primarily vector orientation and planarity, was determined, with a set of analogs exhibiting <10 nM EC50 in a genotype 1b replicon assay.

The isoquinolinamide series of HCV NS5A inhibitors exemplified by compounds 2b and 2c provided the first dual genotype-1a/1b (GT-1a/1b) inhibitor class that demonstrated a significant improvement in potency toward GT-1a replicons compared to that of the initial program lead, stilbene 2a. Structure–activity relationship (SAR) studies that uncovered an alternate phenylglycine-based cap series that exhibit further improvements in virology profile, along with some insights into the pharmacophoric elements associated with the GT-1a potency, are described.

In a previous disclosure,1 we reported the dimerization of an iminothiazolidinone to form 1, a contributor to the observed inhibition of HCV genotype 1b replicon activity. The dimer was isolated via bioassay-guided fractionation experiments and shown to be a potent inhibitor of genotype 1b HCV replication for which resistance mapped to the NS5A protein. The elements responsible for governing HCV inhibitory activity were successfully captured in the structurally simplified stilbene prolinamide 2. We describe herein the early SAR and profiling associated with stilbene prolinamides that culminated in the identification of analogs with PK properties sufficient to warrant continued commitment to this chemotype. These studies represent the key initial steps toward the discovery of daclatasvir (BMS-790052), a compound that has demonstrated clinical proof-of-concept for inhibiting the NS5A replication complex in the treatment of HCV infection.

Pd(II)−N-heterocyclic carbene (NHC) metallacrown ether complexes have been synthesized for the first time. Reaction of bis(imidazolium) salts with a long polyether chain with Ag2O afforded silver−NHC complexes [Ag2(L)Cl2] 5, which reacted as carbene transfer reagents with palladium salts to give Pd(II)−NHC metallacrown ether complexes 6a,b. The Ag(I)−NHC complex 5b possesses a one-dimensional chain configuration by each Ag(I) center coordinated to one carbene and two bridging chlorides. Each of Pd(II)−NHC metallacrown ether complexes 6a,b contains a 25-membered macrocyclic NHC metallacrown ether formed by a bidentate chelate bis(carbene) ligand with a long flexible linkage and a Pd(II). The coordination geometry on the Pd(II) is approximately square planar. Pd(II)−NHC metallacrown ether complexes 6a and 6b have been shown to be highly effective in the Suzuki−Miyaura reactions of a variety of aryl bromides in neat water without the need of inert gas protection.

In the title compound, C19H22N3O+ center dot Br-, the imidazole ring is approximately coplanar with the pyridine ring [dihedral angle = 0.88 (13)degrees] and nearly perpendicular to the benzene ring [dihedral angle = 81.70 (13)degrees]. O - H ... Br and C - H ... Br hydrogen bonding helps to stabilize the crystal structure.

The WRKY transcriptional factor superfamily regulates diverse functions, including processes such as plant development and stress response. In this study, we have shown that the rice WRKY45 (OsWRKY45) expression is markedly induced in response to stress-related hormone abscisic acid (ABA) and various stress factors, e.g., application of NaCl, PEG, mannitol or dehydration, treatment with 0°C and 42°C as well as infection by Pyricularia oryzae Cav. and Xanthomonas oryzae pv. oryzae. Together, these results indicate that the OsWRKY45 may be involved in the signal pathways of both biotic and abiotic stress response. Further analyses of 35S:OsWRK45 Arabidopsis plants have shown that ectopic, constitutive over-expression of the OsWRKY45 transgene confers a number of properties to transgenic plants. These properties include significantly increased expression of PR genes, enhanced resistance to the bacterial pathogen Pseudomonas syringae tomato DC3000, enhanced tolerance to salt and drought stresses, decreased sensitivity toward ABA signalling during seed germination and post-germination processes, and modulation of ABA/stress-regulated genes during drought induction. In addition, higher levels of OsWRKY45 expression in transgenic plants correlate positively with the strength of the abiotic and biotic responses mentioned above. More specifically, the decreased ABA sensitivities, the enhanced disease resistance and drought tolerances may be attributed, in part, to stomatal closure and induction of stress-related genes during drought induction. The relationship between OsWRKY45 expression and ABA signalling is discussed.