Transform spectrometer based on measuring the periodicity of Talbot self-images

We demonstrate a compact transform spectrometer based on measuring the periodicity of Talbot self-images. The system has no moving parts; it contains only a tilted absorption grating that is imaged onto a CCD camera. The linear architecture of the system makes it possible to use this design in imaging arrays of spectrometers. Unlike other transform spectrometers, its resolution is independent of wavelength.     

Synthesis and applications of cyano‐vinylene‐based polymers containing cyclopentadithiophene and dithienosilole units for photovoltaic cells

Two β‐cyano‐thiophenevinylene‐based polymers containing cyclopentadithiophene ( CPDT‐CN ) and dithienosilole ( DTS‐CN ) units were synthesized via Stille coupling reaction with Pd(PPh₃)₄ as a catalyst. The effects of the bridged atoms (C and Si) and cyano‐vinylene groups on their thermal, optical, electrochemical, charge transporting, and photovoltaic properties were investigated. Both polymers possessed the highest occupied molecular orbital (HOMO) levels of about ?5.30 eV and the lowest unoccupied molecular orbital (LUMO) levels of about ?3.60 eV, and covered broad absorption ranges with narrow optical band gaps (ca. 1.6 eV). The bulk heterojunction polymer solar cell (PSC) devices containing an active layer of electron‐donor polymers ( CPDT‐CN and DTS‐CN ) blended with an electron‐acceptor, that is, [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM) or [6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM), in different weight ratios were explored under 100 mW/cm² of AM 1.5 white‐light illumination. The PSC device based on DTS‐CN: PC₇₁BM (1:2 w/w) exhibited a best power conversion efficiency (PCE) value of 2.25% with V_oc = 0.74 V, J_sc = 8.39 mA/cm², and FF = 0.36. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Pyrenylamine‐functionalized aromatic polyamides as efficient blue‐emitters and multicolored electrochromic materials

A series of novel aromatic polyamides with pyrenylamine in the backbone were prepared from a newly synthesized dicarboxylic acid monomer, N,N‐di(4‐carboxyphenyl)‐1‐aminopyrene, and various aromatic diamines via the phosphorylation polyamidation technique. These polyamides were readily soluble in many organic solvents and could be solution‐cast into tough and amorphous films. They had useful levels of thermal stability with glass‐transition temperatures in the range of 276–342 °C and 10% weight loss temperatures in excess of 500 °C. The dilute N‐methyl‐2‐pyrrolidone (NMP) solutions of these polymers exhibited fluorescence maxima around 455–540 nm with quantum yields up to 56.9%. The polyamides also showed remarkable solvatochromism of the emission spectra. Their films showed reversible electrochemical oxidation and reduction accompanied by strong color changes from colorless neutral state to purple oxidized state and to yellow reduced state. The polyamide 4g containing the pyrenylamine units in both diacid and diamine sides exhibited easily accessible p‐ and n‐doped states, together with multicolored electrochromic behaviors. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

New carbazole‐based conjugated polymers containing pyridylvinyl thiophene units for polymer solar cell applications: Morphological stabilization through hydrogen bonding

We have synthesized two conjugated polymers ( P1 , P2 ) containing alternating electron‐donating and ‐accepting units, based on N‐alkyl‐2,7‐carbazole, 4,7‐di(thiophen‐5‐yl)‐2,1,3‐benzothiadiazole and 3‐[2‐(4‐pyridyl)vinyl]thiophene units. These conjugated polymers contained different contents of pyridine units, which were incorporated to form hydrogen bonds with [6,6]‐phenyl‐C₆₁‐butyric acid (PCBA). When these hydrogen bonding interactions were present in the polymer thin films, their thermal stability improved; deterioration, which occurred through aggregation of PCBA methyl ester after lengthy annealing times, was also suppressed. The power conversion efficiency of a device incorporating the film featuring hydrogen bonding interactions remained at 75% of the original value after thermal annealing for 5 h at 140 °C. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Gelation of a Highly Fluorescent Urea‐Containing Triarylmelamine Derivative: 2,4,6‐Tris(p‐N′‐Octadecylureido‐Anilino)Triazine in Organic Solvents

A new gelator of urea‐containing triazine derivatives was synthesized and tested in order to explore the gelation potential in different organic solvents. This compound has been found to form organogels with a variety of organic solvents such as decalin and other solvents. The resulting thermo‐reversible gel was characterized by using the dropping ball method and a number of other instruments. The melting temperature of the gel increased with the gel concentration. The intermolecular hydrogen bonding of gelation was demonstrated through an FT‐IR spectrometer. UV‐Vis and fluorescence analysis showed that the gel displayed various optical effects in different organic solvents. The blue fluorescence of the gel in decalin and the quenched effect of gel in CHCl³ were displayed, respectively. Morphological features in decalin and CHCl₃ were studied by applying atomic force microscopy (AFM), and the morphological features demonstrated that there were different aggregations in different solvents. In conductivity electrolyte experiments, the organogel electrolytes indicated high conductivity (σ) comparable to the corresponding NaClO₄/THF solution. The conductivity of gel electrolytes was increased with electrolyte salt.     

Saccharomyces cerevisiae oxidosqualene‐lanosterol cyclase: A chemistry–biology interdisciplinary study of the protein's structure–function–reaction mechanism relationships

The oxidosqualene cyclases (EC 5.4.99‐) constitute a family of enzymes that catalyze diverse cyclization/rearrangement reactions of (3S)‐2,3‐oxidosqualene into a distinct array of sterols and triterpenes. The relationship between the cyclization mechanism and the enzymatic structure is extremely complex and compelling. This review covers the historical achievements of biomimetic studies and current progress in structural biology, molecular genetics, and bioinformatics studies to elucidate the mechanistic and structure–function relationships of the Saccharomyces cerevisiae oxidosqualene‐lanosterol cyclase‐catalyzed cyclization/rearrangement reaction. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 302–325; 2008: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20157     

Self‐assembly of H‐bonded side‐chain and cross‐linking copolymers containing diblock‐copolymeric donors and single/double H‐bonded light‐emitting acceptors

A series of diblock‐copolymers were synthesized through anionic polymerization of styrene and tert‐butyl methacrylate (tBuA) with different monomer ratios, and analogous block‐copolymeric derivatives (PS‐b‐PAA)s with monofunctional carboxylic acid groups were obtained by further hydrolyzation as hydrogen‐bonded (H‐bonded) proton donors. Via H‐bonded interaction, these diblock‐coplymeric donors (PS‐b‐PAA)s were incorporated with luminescent mono‐pyridyl/bis‐pyridyl acceptors to form single/double H‐bonded supramolecules, that is, H‐bonded side‐chain/cross‐linking copolymers, respectively. The supramolecular architectures formed by donor polymers and light‐emitting acceptors were influenced by the ratio of acid blocks in the diblock copolymeric donors and the type of single/double H‐bonded light‐emitting acceptors. Their thermal and luminescent properties can be adjusted by H‐bonds, and more than 100 nm of red‐shifted photoluminescence (PL) emissions were observed, which depend on the degrees of the H‐bonding interactions. Self‐assembled phenomena of amphiphilic dibolck copolymers and their H‐bonded complexes were confirmed by TEM micrographs, and supramolecular microphase separation of spherical micelle‐like morphology was demonstrated to affect the photophysical properties. Polymer light‐emitting diode (PLED) devices containing H‐bonded complexes showed electroluminescence (EL) emissions of 503–560 nm under turn‐on voltages of 7.5–9.0 V, maximum power efficiencies of 0.23–0.37 cd/A (at 100 mA/cm²), and maximum luminances of 318–519 cd/m² (around 25 V). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4685–4702, 2009     

High sensitivity and high selectivity terahertz biomedical imaging

We demonstrate two distinct emerging terahertz (THz) biomedical imaging techniques.One is based on the use of a new single frequency THz quantum cascade laser and the other is based on broadband THz time domain spectrocopy.The first method is employed to derive a metastasis lung tissue imaging at 3.7 THz with clear contrast between cancerous and healthy areas.The second approach is used to study an osseous tissue under several imaging modalities and achieve full THz spectroscopic imaging based on the freque...     

A note on “Seller’s optimal credit period and cycle time in a supply chain for deteriorating items with maximum lifetime”

In 2014, Wang et al. (2014) extended the model of Lou and Wang (2012) to incorporate the credit period dependent demand and default risk for deteriorating items with maximum lifetime. However, the rates of demand, default risk and deterioration in the model of Wang et al. (2014) are assumed to be specific functions of credit period which limits the contributions. In this note, we first generalize the theoretical results of Wang et al. (2014) under some certain conditions. Furthermore, we also present some structural results instead of a numerical analysis on variation of optimal replenishment and trade credit strategies with respect to key parameters.