High optical transparency, low dielectric constant and light color of novel organosoluble polyamides with bulky alicyclic pendent group

Novel optically transparent, low dielectric and highly organosoluble alicyclic polyamides derived from bulky alicyclic diamine containing trifluoromethyl group on either side, 1,1-bis[4-(2-trifluoromethyl-4-aminophenoxy)phenyl]-4-tert-butylcyclohexane (BTFAPBC), were prepared. The polyamides were obtained in almost quantitative yields and showed inherent viscosity values between 0.55 and 0.72 dL g⁻¹ in DMAc solution. Most of the polyamides showed excellent solubility in polar solvents such as N-methyl-2-pyrrolidinone (NMP), N,N′-dimethyl acetamide (DMAc), N,N′-dimethyl formamide (DMF), pyridine, cyclohexanone, γ-butyrolactone and chloroform. The cut-off wavelength for polyamides ranged from 350 to 388 nm. Polyamides with alicyclic tert-butylcyclohexyl cardo and trifluoromethyl substituents exhibited low dielectric constants ranging from 3.29 to 3.98 (at 100 Hz) compared with commercially available polyamides [Amodel^®, 4.2-5.7 at 100 Hz]. Polyamides showed glass transition temperatures in the range of 244-266 °C and possessed a coefficient of thermal expansion (CTE) of 60-75 ppm °C⁻¹. Thermogravimetric analysis data showed that the polyamides were stable up to 430 °C and the 10% weight loss temperature was found to be in the range of 437-466 °C in nitrogen atmosphere. The polyamide films had a tensile strength in the range of 66-103 MPa, elongation at break in the range of 5-8%, and tensile modulus in the range of 1.5-2.2 GPa. Due to their properties, the polyamides could be considered as engineering plastic and photoelectric materials.     

New and bioactive lignans from the fruits of Schisandra sphenanthera

Phytochemical investigation of the ethanol extract from the fruits of Schisandra sphenanthera has resulted in isolation of seven new oxygenated lignans (1–7), in addition to 11 known compounds (8–18). Their structures were determined on the basis of 2D-NMR (COSY, HMQC, HMBC and NOESY) analyses. The isolated components were evaluated with a reporter gene assay that measures their anti-liver fibrosis activity. Compounds 1, 2, 4, 11, 13, 14 and 18 exhibited significant anti-inflammatory activity on HSC-T6 test.     

Can the technological impact of academic journals be evaluated? The practice of non-patent reference (NPR) analysis

Journal rankings and journal ratings are important to governments, research institutes, and scientific research in general, and they frequently serve as the criteria for evaluating research performance to determine whether specific researchers will receive promotions and/or earn research grants. However, the only widely adopted journal assessment method is known as impact factor (IF), which focuses on citations in academic journals. However, IF disregards the technological applications and value of academic journals. In this article, we propose a method to rank academic journals that utilizes non-patent references in patent documents. We also compare the differences between journal rankings derived by using IF with those derived from the Intellectual Property Citation Index (IPCI) across different fields; moreover, some fields contain positive and significant correlations between IF and the IPCI. The results of this study offer a new perspective from which to assess the technological value of academic journals, particularly those in the technological and scientific fields. This study considers linkages among science and technology and the needs of the stakeholders in journal assessment to shed light on journal assessment and journal ranking methods.     

From driving cycle analysis to understanding battery performance in real-life electric hybrid vehicle operation

This paper proposes a methodology and approach to understand battery performance and life through driving cycle and duty cycle analyses from electric and hybrid vehicle (EHV) operation in real-world situations. Conducting driving cycle analysis with trip data collected from EHV operation in real life is very difficult and challenging. In fact, no comprehensive approach has been accepted to date, except those using standard driving cycles on a dynamometer or a track. Similarly, analyzing duty cycle performance of a battery under real-life operation faces the same challenge. A successful driving cycle analysis, however, can significantly enhance our understanding of EHV performance in real-life driving. Likewise, we also expect similar results through duty cycle analysis for batteries. Since 1995, we have been developing tools to analyze EHV and power source performance. In particular, we were able to collect data from a fleet of 15 Hyundai Santa Fe electric sports utility vehicles (e-SUVs) operated on Oahu, Hawaii; from July 2001 to June 2003 to allow driving and duty cycle analyses in order to understand battery pack performance from a variety of EHV operating conditions. We thus developed a comprehensive approach that comprises fuzzy logic pattern recognition (FL-PR) techniques to perform driving and duty cycle analyses. This approach has been successfully applied to EHV performance analysis via the creation of a compositional driving profile called “driving cycle profile” (DrCP) for each trip. The same approach was used to analyze battery performance via the construction of “duty cycle profile” (DuCP) to express battery usage under various operating conditions. The combination of the two analyses enables us to understand both the usage profile of EHV and battery performance in synergetic details and in a systematic manner using a pattern recognition technique.     

Revealing the Microstates of Body-Centered-Cubic (BCC) Equiatomic High Entropy Alloys

Attributing to the attractive mechanical properties, e.g., high yield strength and fracture toughness, the atomic and electronic basis for high entropy alloys (HEAs) are under extensive studies. In the present work, the local atomic arrangement of body-centered-cubic (BCC) equiatomic HEAs are revealed by the CN14 cluster-plus-glue-atom model and the 32 atoms special quasirandom structures. Moreover, the cluster-plus-glue-atom model is utilized to generate ordered and disordered configurations. The bonding lengths among the same and different alloying elements are comprehensively compared in term of their partial pair correlation function (PCF). According to the specific (well-defined) position of each partial PCF of the BCC structure, the order–disorder/random configurational transitions are revealed by the absence of partial PCF peaks. Here, the WMoTM₁TM₂ (TM = Ta, Nb, and V) BCC equiatomic refractory HEAs are selected as a case study. Through mixing various groups of alloying elements, the atomic-size differences not only result in the lattice mismatch/distortion but also yield the formation of weak spots. Their bonding-charge density captures the electron redistributions caused by the coupling effect of the lattice distortion and valance electron differences among various elements, which also presents the physical nature of the loosely-bonded weak spots and the tightly-bonded clusters. It is worth mentioning that both the PCF and the negative enthalpy of mixing can be utilized to characterize the clusters or the short range ordering in the HEAs. The microstates revealed by the cluster-plus-glue-atom model are in line with the novel small set of the ordered structures method reported in the literature.     

Nondestructive effect of the cusp magnetic field on the dendritic microstructure during the directional solidification of Nickel-based single crystal superalloy

The mechanical-property improvement of directionally-solidified Nickel-based single crystal(SC)superalloy with the single-direction magnetic fields is limited by their destructiveness on the dendritic microstructure.Here,the work present breaks through the bottleneck.It shows that the application of the cusp magnetic field(CMF)ensures that the dendrites are not destroyed.This feature embodies that the primary dendrite trunks arrange regularly and orderly,as well the secondary dendrite arms grow symmetrically.By contrast,both the unidirectional transverse and longitudinal magnetic field destroy the dendrite morphology,and there are a number of stray grains near the totally-re melted interface.The nondestructive effect is achieved mainly by the combined action of the thermoelectromagnetic force on the dendrites and thermoelectromagnetic convection in the melt during directional solidification.The investigation should contribute a new route for dramatically and effectively improving the crystal quality and mechanical properties of the directionally-solidified alloys.     

Microstructural Control of Ti-Al-Nb-W-B Alloys

In this work, new TiAl alloys containing W, B, and Nb have been developed. Fine uniform microstructures, with colony size smaller than 50 μm, can be conveniently obtained after hot-isostatic pressing (HIP) and homogenization treatment without any grain-refining processes using hot deformation. The effects of tungsten and boron on the microstructure of the TiAl alloys, including the colony size and lamellar spacing, were analyzed. This work shows that a small additional amount of W can refine the grain size of the Ti-Al-Nb-W-B alloys. The lamellar spacing also decreases with increasing W concentration. When the amount of W is greater than 0.4 at. pct, the β phase is stabilized and remains at room temperature, which can degrade the ductility of the alloy. Mechanical properties, such as the hardness of the alloy, can be increased by the addition of the alloying element through the solution strengthening and refinement of the grain size. This article is based on a presentation given in the symposium entitled “Deformation and Fracture from Nano to Macro: A Symposium Honoring W.W. Gerberich’s 70th Birthday,” which occurred during the TMS Annual Meeting, March 12-16, 2006 in San Antonio, Texas and was sponsored by the Mechanical Behavior of Materials and Nanomechanical Behavior Committees of TMS.     

Phase Transition and Texture Evolution in the Ni-Mn-Ga Ferromagnetic Shape-Memory Alloys Studied by a Neutron Diffraction Technique

The phase transition and influence of the applied stress on the texture evolution in the as-cast Ni-Mn-Ga ferromagnetic shape-memory alloys were studied by the time-of-flight (TOF) neutron diffraction technique. The neutron diffraction experiments were performed on the General Purpose Powder Diffractometer (Argonne National Laboratory). Inverse pole figures were determined from the neutron data for characterizing the orientation distributions and variant selections of polycrystalline Ni-Mn-Ga alloys subjected to different uniaxial compression deformations. Texture analyses reveal that the initial texture for the parent phase in the as-cast specimen was composed of , , , and , which was weakened after the compression deformation. Moreover, a strong preferred selection of martensitic-twin variants (and ) was observed in the transformed martensite after a compression stress applied on the parent phase along the cyclindrical axis of the specimens. The preferred selection of variants can be well explained by considering the grain/variant-orientation-dependent Bain-distortion energy. This article is based on a presentation given in the symposium entitled “Neutron and X-Ray Studies for Probing Materials Behavior,” which occurred during the TMS Spring Meeting in New Orleans, LA, March 9–13, 2008, under the auspices of the National Science Foundation, TMS, the TMS Structural Materials Division, and the TMS Advanced Characterization, Testing, and Simulation Committee.