A three‐dimensional network of cadmium

The title complex, poly­[bis­[N‐(2‐amino­ethyl)‐N‐methyl‐1,2‐ethane­di­amine]­hexa‐μ‐thio­cyanato‐tricadmium(II) monohydrate], [Cd₃(NCS)₆(medien)₂]_n·nH₂O [medien is N,N‐bis(2‐amino­ethyl)­methyl­amine, C₅H₁₆N₃], adopts a three‐dimensional inorganic polymeric network structure. Two cadmium centres (Cd1 and Cd2) are linked to each other via thio­cyanate bridges. The environment of the Cd1 atom involves only S atoms, making it soft, whereas the environment of the Cd2 atom involves only N atoms, making it hard.     

Preparation and Characterization of Half‐Sandwich (Pentamethylcyclopentadienyl)(triflato)titanium(IV) Complexes: Solid‐State Structural Motifs and Catalysis Studies

Half‐sandwich (pentamethylcyclopentadienyl)(triflato)titanium(IV) complexes of the type [Ti(Cp*)(TfO)₂X] (X=MeO ( 1 ), Me ( 2 ), 2,4,6‐Me₃C₆H₂O ( 5 )) or [Ti(Cp*)(o‐OC₆H₄O)(TfO)] ( 7 ) were readily synthesized via methathesis of the corresponding chloride complexes with silver triflate (Cp*=(η⁵‐1,2,3,4,5‐pentamethylcyclopenta‐2,4‐dien‐1‐yl)). In addition, the complex 3 with X=OH was prepared by controlled hydrolysis of 2 . The solid‐state structures of these new complexes were determined by single‐crystal X‐ray‐diffraction techniques. Three different structural motifs were identified; 1, 2, 3 , and 7 are dimeric, while 5 is monomeric. The complexes were screened for their ability to stereospecifically polymerize styrene under homogeneous conditions. In the absence of activators, such as MAO (methylaluminoxane), 1 and 2 readily catalyzed the formation of atactic polystyrene; a strong dependence on the steric size of X was noted. In the presence of MAO, all of the complexes showed high activity and strong preference for the synthesis of syndiotactic polystyrene that was superior to that of [TiCl₃(Cp*)]/MAO.     

New chiral crown ether stationary phase for the liquid chromatographic resolution of α-amino acid enantiomers

A new chiral stationary phase (CSP) for the liquid chromatographic separation of enantiomers was prepared by bonding a novel enantiopure (diphenyl-substituted 1,1′-binaphthyl) crown ether to 5 μm silica gel. The resulting CSP was applied to the separation of the enantiomers of various natural and unnatural α-amino acids. All α-amino acids tested were resolved very well on the new CSP, with the exception of proline, which does not contain a primary amino group. The resolution of α-amino acid enantiomers on this new CSP was found to be dependent on the type and amounts of organic and acidic modifiers, and on column temperature.     

AC floating body effects and the resultant analog circuit issues insubmicron floating body and body-grounded SOI MOSFET's

We report the extensive study on ac floating body effects of different SOI MOSFET technologies. Besides the severe kink and resultant noise overshoot and degraded-distortion in partially depleted (PD) floating body SOI MOSFET's, we have investigated the residue ac floating body effects in fully depleted (FD) floating body SOI MOSFET's, and the different body contacts on PD SOI technologies. It is important to note that there is a universal correlation between ac kink effect and Lorentzian-like noise overshoot regardless of whether the body is floating or grounded. In addition, it was found that third-order harmonic distortion is very sensitive to floating body induced kink or deviation on output conductance due to the finite voltage drop of body resistance. These results provide device design guidelines for SOI MOSFET technologies to achieve comparable low-frequency noise and linearity with Bulk MOSFET's     

Synthetic Studies Toward Bryostatin 1: Preparation of a C(1)-C(16) Fragment by Pyran Annulation

An expeditious assembly of a C₁-C₁₆ subunit of bryostatin 1 is described. A pyran annulation reaction was utilized to form the B-ring by reaction of a hydroxy-allylsilane with a fully elaborated A-ring subunit. This annulation process proceeded with complete diastereoselectivity and in excellent isolated yield despite the presence of potentially sensitive functionality in the A-ring segment.     

Ultrahigh-efficiency power amplifier for space radar applications

This paper describes a broad-band switch mode power amplifier based on the indium phosphide (InP) double heterojunction bipolar transistor (DHBT) technology. The amplifier combines the alternative Class-E mode of operation with a harmonic termination technique that minimizes the insertion loss of matching circuitry to obtain ultrahigh-efficiency operation at X-band. For broad-band Class-E performance, the amplifiers output network employs a transmission line topology to achieve broad-band harmonic terminations while providing the optimal fundamental impedance to shape the output current and voltage waveforms of the device for maximum efficiency performance. As a result, 65% power-added efficiency (PAE) was achieved at 10 GHz. Over the frequency band of 9-11 GHz, the power amplifier achieved 49%-65% PAE, 18-22 dBm of output power, and 8-11 dB gain at 4 V supply. The reported power amplifier achieved what is believed to be the best PAE performance at 10 GHz and the widest bandwidth for a switch-mode design at X-band.     

Visualizing iron in multiple sclerosis

Magnetic resonance imaging (MRI) protocols that are designed to be sensitive to iron typically take advantage of (1) iron effects on the relaxation of water protons and/or (2) iron-induced local magnetic field susceptibility changes. Increasing evidence sustains the notion that imaging iron in brain of patients with multiple sclerosis (MS) may add some specificity toward the identification of the disease pathology. The present review summarizes currently reported in vivo and post mortem MRI evidence of (1) iron detection in white matter and gray matter of MS brains, (2) pathological and physiological correlates of iron as disclosed by imaging and (3) relations between iron accumulation and disease progression as measured by clinical metrics.