Ethylene polymerization behavior of Cr(III)‐containing montmorillonite: Influence of chromium compounds

Montmorillonite was treated with Cr(NO₃)₃, Cr(acetate)₃, and Cr(acac)₃ to give three catalyst precursors, Cr‐MMT‐1 , Cr‐MMT‐2 , and Cr‐MMT‐3 , respectively. Application of these catalysts to the ethylene polymerization reaction revealed Cr‐MMT‐1 to be much more reactive than the other two while the molecular weight distributions of the polymers were practically the same. Elemental analysis, XRD, and TEM measurements suggested that chromium occupied the interlayer section in Cr‐MMT‐1 and mostly the outer surface region for the other two catalysts. Aluminosilicate‐supported Cr catalysts exhibited reactivity similar to that of Cr‐MMT‐2 and Cr‐MMT‐3 . However, more of the low‐molecular‐weight polymer was formed. These data suggested that there is a relationship between the sites of the Cr ions and catalytic reactivity, and between supporting solid identity and molecular weight distribution of the polymer. The use of n‐Bu₂Mg and Et₂Zn in the place of Et₃Al led to lower activity but gave polymers of narrower molecular weight distribution, with more of the high‐molecular‐weight material. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2272–2280, 2009     

Determination of paroxetine in serum treated with simple pretreatment by pre‐column high‐performance liquid chromatography using 4‐(5,6‐dimethoxy‐2‐phthalimidinyl)‐2‐methoxyphenylsulfonyl chloride as a fluorescent labeling reagent

The therapeutic drug monitoring of paroxetine could be used to optimize the pharmacological treatment of depressed patients. A simple and sensitive high‐performance liquid chromatography procedure was developed for the determination of paroxetine in serum. After simple pretreatment of serum (50 μL) with acetonitrile and o‐phthalaldehyde, paroxetine was derivatized with 4‐(5,6‐dimethoxy‐2‐phthalimidinyl)‐2‐methoxyphenylsulfonyl chloride at 70°C for 20 min in borate buffer (0.1 mol/L, pH 8.0) to produce a fluorescent product. The derivative was separated on a reversed‐phase column at 40°C for stepwise elution with (A) acetic acid (10 mmol/L) and (B) acetonitrile. The flow rate was 1.0 mL/min. The fluorescence intensity was monitored at excitation and emission wavelengths of 320 and 400 nm, respectively. The within‐day and day‐to‐day relative standard deviations were 3.0–3.4 and 2.7–8.3%, respectively. The detection limit of paroxetine was 8.3 fmol at a signal‐to‐noise ratio of 3. As the proposed method that only requires a small quantity of serum (50 μL) is simple, sensitive and reproducible, it would be useful for clinical and biochemical research as well as drug monitoring. Copyright © 2013 John Wiley & Sons, Ltd.     

Micro machined tactile sensor for soft tissue compliance detection

A micro-machined piezoresistive type tactile sensor (5mm x 6mm), composed of two zigzag structures which act as spring, with 500μm cubic contact mesas at their tips, has been fabricated for detecting compliance of soft tissue. The concept of applying two springs, with considerably different stiffnesses, to soft tissue for compliance detection has been chosen to get output reading independent of the applied pushing distance between the sensor and the tissue. The testing process is done by three ways; by subjecting the sensor to 1-specimen chips with known stiffness, 2-silicone rubber, 3-chicken organs; namely heart, liver and leg.     

Direct Electrochemical Oxidation of Cellulose: A Cellulose‐Based Fuel Cell System

Direct electricity generation from cellulose without saccharification and fermentation processes was achieved on gold electrode under the alkaline conditions. We (i) overcame problems with the insolubility of cellulose, and captured its electrochemical potential, and (ii) showed that cellulose was converted to cellulose derivatives due to electrochemical oxidation. In addition, we (iii) constructed a cellulose‐based fuel cell, demonstrating that cellulose can be direct electrical based fuel source. The presented fuel cell system overcomes the enormous distribution challenges encountered with other alternative bioenergy sources such as hydrogen.     

Orlicz–Morrey Spaces and Fractional Operators

By taking an interest in a natural extension to the small parameters of the trace inequality for Morrey spaces, Orlicz–Morrey spaces are introduced and some inequalities for generalized fractional integral operators on Orlicz–Morrey spaces are established. The local boundedness property of the Orlicz maximal operators is investigated and some Morrey-norm equivalences are also verified. The result obtained here sharpens the one in our earlier papers.     

Charge-order driven proton arrangement in a hydrogen-bonded charge-transfer complex based on a pyridyl-substituted TTF derivative

A unique N(+)-HN hydrogen-bonded (H-bonded) dimer motif based on partially oxidized pyridyl-substituted TTF was constructed in the charge-transfer complex. The charge ordering in the TTF column by the charge disproportionation in the dimer regulates the arrangement of the H-bonded proton, evidencing the proton-electron coupled state.     

Structure–Property Relationship of Supramolecular Ferroelectric [H‐66dmbp][Hca] Accompanied by High Polarization,Competing Structural Phases,and Polymorphs

Three polymorphic forms of 6,6′‐dimethyl‐2,2′‐bipyridinium chloranilate crystals were characterized to understand the origin of polarization properties and the thermal stability of ferroelectricity. According to the temperature‐dependent permittivity, differential scanning calorimetry, and X‐ray diffraction, structural phase transitions were found in all polymorphs. Notably, the ferroelectric α‐form crystal, which has the longest hydrogen bond (2.95 Å) among the organic acid/base‐type supramolecular ferroelectrics, transformed from a polar structure (space group, P2₁) into an anti‐polar structure (space group, P2₁/c) at 378 K. The non‐ferroelectric β‐ and γ‐form crystals also exhibited structural rearrangements around hydrogen bonds. The hydrogen‐bonded geometry and ferroelectric properties were compared with other supramolecular ferroelectrics. A positive relationship between the phase‐transition temperature (T_C) and hydrogen‐bond length (<d>) was observed, and was attributed to the potential barrier height for proton off‐centering or order/disorder phenomena. The optimized spontaneous polarization (P_s) agreed well with the results of the first‐principles calculations, and could be amplified by separating the two equilibrium positions of protons with increasing <d>. These data consistently demonstrated that stretching <d> is a promising way to enhance the polarization performance and thermal stability of hydrogen‐bonded organic ferroelectrics.     

Optical properties of semiconductor quantum dots in magnetic fields

Optical properties of semiconductor quantum dots in magnetic fields are reviewed. A theory is described based on a multi-band effective-mass approximation with a nonparabolic conduction electron dispersion, the direct Coulomb interaction, and the electron-hole exchange interaction taken into account. The transition from the quantum-confined Zeeman effect for a weak magnetic field to the quantum-confined Paschen-Back effect to a strong magnetic field is discussed in comparison with atomic spectra in magnetic fields. Experimental results of the optical properties of isolated CuCl, CdSSe, and Si quantum dots in magnetic fields are also discussed in conjunction with the theoretical results.     

Highly efficient photocatalytic dehalogenation of organic halides on TiO2 loaded with bimetallic Pd-Pt alloy nanoparticles

UV irradiation of TiO(2) loaded with bimetallic Pd-Pt alloy particles promotes highly efficient dehalogenation of organic halides with alcohol as a hydrogen source.