Photophysical studies on axially substituted indium and gallium phthalocyanines upon UV-Vis laser irradiation

A series of results from different photophysical experiments on indium and gallium phthalocyanine (Pc) compounds is reported. Gallium Pc's have much longer singlet and triplet excited state lifetimes in comparison with indium Pc's. The strong reverse saturable absorption observed at 532 nm excitation is a consequence of the increase in absorbance of Pc's in the triplet excited state in the optical window comprised between Q- and B-bands, as verified upon laser irradiation with ns pulses at 355 nm. Using C₆₀ as a reference, the intersystem cross quantum yields of tBu₄PcInCl and tBu₄PcGaCl are 0.70 and 0.36, respectively.     

New solvent for polyrotaxane. I. Dimethylacetamide/lithium chloride (DMAc/LiCl) system for modification of polyrotaxane

Dimethylacetamide (DMAc) containing 8–9% (w/w) of lithium chloride (LiCl) or lithium bromide (LiBr) was found to be a good solvent for a polyrotaxane consisting of poly (ethylene glycol) (PEG) and α‐cyclodextrin (CD). In the new DMAc/LiCl solvent system, various modification reactions such as acetylation, direct dansylation, and reaction with acid chloride could be performed, which was unattainable in the previously reported solvents, i.e., dimethylsulfoxide (DMSO) and aqueous sodium hydroxide solution. Acetylation with acetic anhydride and direct dansylation of the polyrotaxane were investigated in detail in comparison with reactions in DMSO. The dissolution of the polyrotaxane in DMAc/LiCl suggested that the solubility and insolubility of the polyrotaxane is strongly in relation to the inter‐ and intramolecular hydrogen bonding of the polyrotaxane. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 532–538, 2006     

Long Si nanowires with millimeter-scale length by modified thermal evaporation from Si powder

A modified thermal evaporation processing is reported to fabricate silicon nanowires starting from Si powder under normal pressure. In a temperature range of 1250–1290 °C, long single-crystal Si nanowires with an amorphous layer were grown in relative large quantity, and they had a millimeter-scale length and a uniform diameter of about 100 nm. A high-resolution transmission electron microscopy image indicated that the growing direction of the long Si nanowires is [111]. PACS 81.07.Bc     

New Test Light Spectrum Design for L/U-Band Extended Optical Fiber Line Testing System

This paper describes a new design for the test light source of an L/U-band extended optical fiber line testing system and the side-band suppresser ratio of the test light should be more than 70 dB.     

Stereodivergent Synthesis of Arylcyclopropylamines by Sequential C?H Borylation and Suzuki–Miyaura Coupling

A step‐economical and stereodivergent synthesis of privileged 2‐arylcyclopropylamines (ACPAs) through a C(sp³) H borylation and Suzuki–Miyaura coupling sequence has been developed. The iridium‐catalyzed C H borylation of N‐cyclopropylpivalamide proceeds with cis selectivity. The subsequent B‐cyclopropyl Suzuki–Miyaura coupling catalyzed by [PdCl₂(dppf)]/Ag₂O proceeds with retention of configuration at the carbon center bearing the Bpin group, while epimerization at the nitrogen‐bound carbon atoms of both the starting materials and products is observed under the reaction conditions. This epimerization is, however, suppressed in the presence of O₂. The present new ACPA synthesis results in not only a significant reduction in the steps required for making ACPA derivatives, but also the ability to access either isomer (cis or trans) by simply changing the atmosphere (N₂ or O₂) in the coupling stage.     

Hetero‐Selective DNA‐Like Duplex Stabilized by Donor–Acceptor Interactions

We report on the characterization of a novel hetero‐selective DNA‐like duplex of pyrene and anthraquinone pseudo base pairs. The pyrene/anthraquinone pairs showed excellent selectivity in hetero‐recognition and even trimers were found to form a hetero‐duplex. Pyrene and anthraquinone moieties were tethered on acyclic D ‐threoninol linkers and linked to adjacent residues by using standard phosphoramidite chemistry. When pyrene and anthraquinone were incorporated at pairing positions in complementary strands of natural DNA oligonucleotides, the duplex was stabilized significantly. Moreover, a pyrene hexamer and an anthraquinone hexamer formed a stable artificial hetero‐duplex without the assistance of natural base pairs. The pyrene/anthraquinone pair was so stable that even trimers formed a hetero‐duplex under conditions in which natural DNA strands of three residues do not.     

Analytical solution of non-fourier temperature response in a finite medium under laser-pulse heating

A temperature wave solution predicted by the hyperbolic heat equation is developed for a finite medium exposed to a surface heat flux of laser with an actual temporal profile. By using the analytical solution, the temperature response, the propagation and the reflection of the temperature wave due to such heat pulse are investigated for different pulse duration, thickness of the medium, and energy absorption depth.     

Electrooxidative Cleavage of Carbon-Carbon Bonds. III. Preparation of Alkanediones from Cycloalkanones Through 2-Phenylthio-1-Cycloalkanols

The tittle electrochemical procedures have been carried out either in a divided cell, giving keto acetals 3 from 2 (R¹ = H, R² = alkyl), or in an undivided cell, affording diketones 4 from 2 (R¹ = R² = alkyl), in moderate to good yields.     

Experimental heat and mass transfer of the separated and coupled rotating desiccant wheel and heat wheel

The experimental evaluation of the separated and coupled rotating desiccant wheel and heat wheel is reported. The study aims to investigate the performance of the desiccant wheel and of the heat wheel both when operated separately and jointly. The performance evaluation of the desiccant wheel is based on its moisture removal capacity (MRC), moisture removal regeneration (MRR), and moisture mass balance (MMB). In addition, the study used the total energy balance (TEB), sensible coefficient of performance (COP_Sensible), latent coefficient of performance (COP_Latent) and, total coefficient of performance (COP_Total). The performance of the heat wheel is based on its effectiveness. The COP_Sensible, COP_Latent and, COP_Total are used in the performance evaluation of the coupled desiccant wheel and heat wheel. The general results of the study show that the MRC, MRR and MMB coupled with the TEB, COP_Latent, COP_Sensible and COP_Total predict adequately the performance of the desiccant wheel. In addition, the coupled operation of the desiccant wheel and heat wheel, contributed to the reduction of the external thermal energy requirement for the regeneration of the desiccant wheel. This study can be applied in other researches seeking evaluation of the desiccant wheel, heat wheel, and their combined operation. Moreover, the data presented here are significant for the desiccant wheel benchmarking and for evaluation of the desiccant wheel models.