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We have developed the Rh‐catalyzed enantioselective [2+2+2] cycloaddition of homopropargyl enamides (tosylamide‐tethered 1,6‐enynes) with alkynes to construct tetrahydroindole skeletons found in natural alkaloids and pharmaceuticals. This cycloaddition proceeds at room temperature in high yields and regio‐ and enantioselectivity with a broad substrate scope. The preparative scale reaction followed by substituent conversion on the nitrogen atom and the diastereoselective [4+2] cycloaddition with singlet O2 affords hexahydroindole‐diols bearing three stereogenic centers and variable substituents on the nitrogen. Mechanistic studies have revealed that the substituents of the enynes change the ratio of intramolecular and intermolecular rhodacycle formation when using terminal alkynes, varying the ee values of the cycloadducts. [ABSTRACT FROM AUTHOR]

We have developed the Rh+/H8‐binap‐catalyzed chemo‐, regio‐, diastereo‐, and enantioselective intermolecular [2+2+2] cycloaddition of three unsymmetric 2π components. Thus, two arylacetylenes react with a cis‐enamide to yield a protected chiral cyclohexadienylamine. Moreover, replacing one arylacetylene with a silylacetylene enables the [2+2+2] cycloaddition of three distinct unsymmetric 2π components. These transformations proceed with excellent selectivity (complete regio‐ and diastereoselectivity and up to >99 % yield and >99 % ee). Mechanistic studies suggest the chemo‐ and regioselective formation of a rhodacyclopentadiene intermediate from the two terminal alkynes. [ABSTRACT FROM AUTHOR]

Primary aldosteronism (PA) is a state of renin-independent aldosterone secretion that can range from subclinical to overt. Some normotensive individuals for whom PA screening is not routinely recommended are reported to fulfill the loading test criterion used for the diagnosis of PA. Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterized by the development of various endocrine tumors. Cases of PA associated with MEN1 have been reported; however, there has been no previous report on renin-independent aldosterone secretion within a family with MEN1. Herein, we present the case of a normotensive family presenting with both MEN1 and renin-independent aldosterone secretion. A 49-year-old man was admitted to our hospital for PA evaluation owing to the plasma aldosterone concentration/plasma renin activity ratio being greater than the screening cut-off value; the patient was normotensive. The patient had a history of left nephrectomy and adrenalectomy for left renal carcinoma and adrenal tumor at the age of 39 years. Subsequently, he was diagnosed with MEN1 concurrent with primary hyperparathyroidism, insulinoma, and novel MEN1 gene mutations (c.655-5_655-4insC and c.818delC). The loading tests for PA confirmation, including saline infusion, and furosemide upright and captopril challenge tests, yielded positive findings, confirming a case of renin-independent aldosterone secretion. The patient's mother, brother, and sister were also genetically or clinically diagnosed with MEN1. All of them were also normotensive and confirmed to have renin-independent aldosterone secretion. The coexistence of renin-independent aldosterone secretion and MEN1 within this family suggests a relationship between the 2 entities. [ABSTRACT FROM AUTHOR]

An automatic method for self. calibrating six-port reflectometers is reported in this paper. It is based on the use of an active impedance synthesis system. This self-calibration method allows a completely autonomous operation, reduces measurement errors caused by the frequent connecting and disconnecting of calibration standards, and is suitable for low and high frequencies, where sliding shorts are difficult to manufacture. In addition, it simplifies operation of six-port reflectometers to nonspecialized users. The experimented impedance synthesis presented relies on an in-phase and quadrature vector modulator, and the entire system is computer controlled. Index Terms--Microwave measurement, self-calibration, six-port.

Extensive measurements of a drain breakdown current as a function of device bias are reported in this paper. To represent the measured drain breakdown currents accurately, a new modeling function and an equivalent circuit controlled by two voltages are proposed. This model, when integrated into a large-signal analysis program, improves the accuracy of the simulation. Index Terms - Breakdown, large signal, MESFET, nonlinear model.

This paper describes an improved large-signal model for predicting an intermodulation distortion (IMD) power characteristic of MESFET's in switching applications. The model is capable of modeling the voltage-dependent drain current and its derivatives, including gate-source and gate-drain capacitors. The drain current and its derivatives are described by a function of a voltage-dependent drain conductance. The model parameters are extracted from a measured drain conductance versus gate voltage characteristic of an MESFET. This paper also presents a new fully symmetric equivalent circuit for switching MESFET's. The IMD power characteristics calculated with the use of the proposed method are compared with experimental data taken from a monolithic-microwave integrated-circuit single-pole double-throw switch. Good agreements over the large gate voltages and input power levels are observed. Index Terms--Harmonic distortion, MESFET's, nonlinear model, nonlinearities.

This paper presents the design and development of highly linear, wide bandwidth mixers. We propose a linearization technique that combines the optimum drain bias condition and multiple-gated transistors for resistive mixers. An on-chip three-line edge-coupled Marchand balun is designed to have low phase and amplitude imbalance for canceling out the even order intermodulation products. Two mixer prototypes: a single-balanced (SB) mixer and a double-balanced (DB) mixer are designed to prove the concepts. The experimental results demonstrate that the SB prototype mixer has a measured conversion loss of less than 11 dB and third-order input intercept point (IIP3) range of 27–33 dBm at 15-dBm LO drive from 7 to 34 GHz. The DB mixer exhibits a conversion loss of less than 11 dB and IIP3 range of 31–35 dBm from 7–26 GHz at 17-dBm LO drive. Both prototypes achieve a high port-to-port isolation of over 30 dB within the operation bandwidth. To the best of our knowledge, the mixers have the highest linearity over the widest bandwidth ever reported. [ABSTRACT FROM PUBLISHER]

In this study, halloysite nanoclay was subjected to sulfuric acid treatment and used as a reinforcing agent in polyvinyl alcohol (PVA). Halloysite is one of the natural substances that is currently recognized as having a nanotubular structure resembling carbon nanotubes. Halloysite nanotubes are 50 nm in diameter, 0.5–1 μm in length and 15 nm in inner diameter. PVA, a synthetic polymer with characteristics such as biodegradability, water solubility, and transparency, was used as the matrix. The PVA/halloysite films were characterized by tensile test, scanning electron microscopy, and optical transmittance. The tensile strength of PVA/untreated-halloysite film was decreased, although Young’s modulus was increased compared with those of neat PVA film. Sulfuric acid treatment was performed on halloysite to improve its interfacial adhesion with PVA. PVA/halloysite films using halloysite treated for a short time (less than 2 h) had improved tensile strength, Young’s modulus and optical transmittance compared with PVA/untreated-halloysite films, however composite films using halloysite treated for longer times had reduced properties. [ABSTRACT FROM PUBLISHER]

NCN-pincer Ru-complexes containing bis(oxazolinyl)phenyl ligands serve as suitable catalysts in the direct conjugate additions of α,β-unsaturated carbonyl compounds, including ketones, esters, and amides, as well as vinylphosphonates, giving various β-alkynyl carbonyl and phosphonate compounds. A bis(oxazolinyl)phenyl (phebox)-Ru complex also catalyzes the asymmetric conjugate addition of an alkyne with a β-substituted, α,β-unsaturated ketone to produce a chiral β-alkynyl ketone. [ABSTRACT FROM AUTHOR]

This paper shows that a pulsed I-V measurement technique is the key to the extraction of large-signal model parameters for a GaAs MESFET operating at microwave frequency. It also shows that the conventional drain current models which have been developed for modeling DC I-V curves do not fit pulsed I-V measurement results accurately. In order to solve this problem, a specially designed drain current model which describes accurately pulsed I-V measurements is presented. The accuracy of the proposed drain current model is verified by comparison between measurements and the modeled characteristics of pulsed I-V data. The comparison reveals that the pulsed I-V measurements are similar to I-V characteristics in microwave operation. The proposed model applies to MMIC power amplifier analysis and verifies the accuracy of the non-linear circuit analysis. © 1998 Scripta Technica. Electron Comm Jpn Pt 2, 80(7): 27–36, 1997 [ABSTRACT FROM AUTHOR]

A chiral NCN-pincer Ru-complex serves as suitable catalyst in the conjugate addition of alkynes with α,β-unsaturated ketones, esters, and amides, as well as vinylphosphonates. [ABSTRACT FROM AUTHOR]

The fat-derived factor, adiponectin, is considered a salutary circulating factor. We recently demonstrated that native adiponectin binds T-cadherin and promotes intracellular biogenesis and secretion of the exosome. Exosomes play important roles in various aspects of homeostasis, including glucose and energy metabolism. However, it remains unclear whether and how the promotion of exosome production by adiponectin in vivo is beneficial for glucose and lipid metabolism. In the present study, overexpression of human adiponectin in mice resulted in an increased number of circulating exosomes, but it did not significantly improve glucose metabolism, change body weights, or change triglyceride clearance under a high-fat diet. Multiple small doses of streptozotocin increased blood glucose and decreased triglyceride clearance similarly in both wild-type and transgenic mice. Thus, these results indicated that human adiponectin overexpression in mice increases plasma exosomes but does not significantly influence glucose and lipid metabolism.

Hypoglycemia should be avoided when treating patients with diabetes. Repaglinide is an insulin secretagogue with a low hypoglycemic risk because of its rapid- and short-acting effects. However, its blood concentration has been reported to increase in combination with clopidogrel, an antiplatelet drug, and in patients with severe renal insufficiency. We herein report an elderly patient with type 2 diabetes mellitus and severe renal insufficiency who received repaglinide and hypoglycemia three days after starting clopidogrel. The concomitant use of repaglinide and clopidogrel can lead to hypoglycemia, especially in patients with severe renal insufficiency.

The new synthetic methodologies for perfluoroaryl-substituted (diaryl)methylphosphonates, -phosphinates via nucleophilic aromatic substitution (S N Ar) were developed. Benzylphosphonate and α-fluorobenzylphosphonate reacted with a wide variety of perfluoroarenes via S N Ar reaction. The reaction took place quickly and gave perfluoroarylated phosphonates in high yields. Highly diastereoselective S N Ar reaction with binaphthyl-based chiral phosphinates was further carried out.

Chiral C 2 -symmetric phosphinic acids were designed based on sterically demanding and helical chiral perfluoroalkyl groups at the closest α-position advancing asymmetric reaction environment and catalytic activity. The perfluoroalkyl catalysts, [(CF 3 ) 2 F 2 ] and [(C 2 F 5 ) 2 F 2 ] phosphinic acids, were synthesized via a stereoselective addition/cyclization sequence of methyl phosphinate and deoxofluorination. These new classes of Brønsted acid catalysts were applied to an asymmetric Friedel-Crafts reaction to give up to 89% yield and 82% R-enantioselectivity, which is higher than those obtained with the parent phosphoric acid (42% and 55.5% S).