Processable and colorless fluorinated poly(ether imide)s based on an isopropylidene‐containing bis(ether anhydride) and various aromatic bis(ether amine)s bearing trifluoromethyl groups

A series of novel organosoluble and light‐colored fluorinated poly(ether imide)s (PEIs) ( IV ) having inherent viscosities of 0.43–0.59 dL/g were prepared from 4,4′‐[1,4‐phenylenbis(isopropylidene‐1,4‐phenyleneoxy)]diphthalic anhydride ( I ) and various trifluoromethyl‐substituted aromatic bis(ether amine)s by a standard two‐step process with thermal and chemical imidization of poly(amic acid) precursors. These PEIs showed excellent solubility in many organic solvents and could be solution‐cast into transparent and tough films. These films were essentially colorless, with an UV–visible absorption edge of 361–375 nm and a very low b* value (a yellowness index) of 15.3–17.0. They also showed good thermal stability with glass‐transition temperature of 191–248°C, 10% weight loss temperature in excess of 494°C, and char yields at 800°C in nitrogen more than 39%. The thermally cured PEI films showed good mechanical properties with tensile strengths of 83–96 MPa, elongations at break of 8–11%, and initial moduli of 1.7–2.0 GPa. They possessed lower dielectric constants of 3.25–3.72 (1 MHz). In comparison with the V series nonfluorinated PEIs, the IV series showed better solubility, lower color intensity, and lower dielectric constants. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 620–628, 2007     

Synthesis and properties of new aromatic polyimides containing redox‐active anthraquinone moieties

A novel anthraquinone‐containing bis(ether amine) monomer, 2,6‐bis(4‐aminophenoxy)anthraquinone, was synthesized from readily available reagents. A series of novel aromatic polyimides were prepared from the newly synthesized diamine monomer with various aromatic tetracarboxylic dianhydrides. The intermediate poly(amic acid)s had inherent viscosities of 0.67–1.12 dL g^?1, and those derived from less stiff dianhydrides could be solution‐cast and thermally cyclodehydrated into flexible and tough polyimide films. The polyimides exhibited glass transition temperatures between 270 and 297 °C, and they were fairly stable up to a temperature of 500 °C in air or nitrogen. The electrochemical and electrochromic properties of one of the polyimides were investigated. The polymer could undergo two reversible steps of electrochemical reduction, with a color change from a colorless neutral state to pink and rose‐red reduced states. © 2012 Society of Chemical Industry     

Development of a PCR assay for the detection of nifH and nifD genes in indigenous photosynthetic bacteria

Molybdenum (Mo) nitrogenases consist of two components: dinitrogenase reductase (encoded by nifH) and the dinitrogenase or MoFe protein (encoded by nifDK). Nitrogenase enzyme of photosynthetic bacteria is responsible for hydrogen production. Therefore, primers were designed for the nitrogenase gene only. In this study, two primers (ND and NH) were designed after comparative genomic analysis of nifH and nifD gene sequences from public databases. The designed primers were used for the amplification of nifH and nifD genes to detect nitrogenase genes in photosynthetic bacteria. Initial detection was done using a monoplex Polymerase Chain Reactions (PCRs) followed by optimization of the PCR protocols. Subsequently, a duplex PCR was designed for amplification and detection of nifH and nifD genes in indigenous photosynthetic bacteria. Evaluation of the duplex PCR on six samples isolated from Palm Oil Mill Effluent (POME) showed that only four isolates contained both the nifH and nifD genes, indicating that these isolates were potential hydrogen-producing bacteria. PCR detection provides a rapid and efficient pre-identification of potential photosynthetic bacterial hydrogen producers.     

Tone interference in VSAT spectrum

This paper investigates the problem of tone interference within the very small aperture terminal (VSAT) binary phase-shift keying (BPSK) signal spectrum. The degree of performance degradation of a VSAT link in the presence of a tone interference is discussed. A simple theoretical analysis is derived, and its validity is verified by experimental measurements performed using a standard commercial VSAT modem measurement setup     

Methodology for assessing adaptive cruise control behavior

This paper reports on nonintrusive methods for characterizing the longitudinal performance of vehicles equipped with adaptive cruise control (ACC) systems. It reports the experimental set-up and procedures for measuring ACC system performance, followed by the modeling and simulation of the measured ACC performance. To further assess the interaction of ACC vehicles with human-controlled traffic, microscopic simulation involving both a human-driver model and an ACC model is discussed.     

Forward-link BER analysis of asynchronous cellular DS-CDMA overNakagami-faded channels using combined PDF approach

A closed-form conditional probability density function (PDF) of the Nakagami-faded-interference-to-signal power ratio, given the exact location of the tagged mobile, is derived for integer values of Nakagami (1960) fade parameter m. The conditional PDF, whose coefficients can be computed efficiently in a recursive manner, significantly reduces the computational complexity of forward-link bit error rate (BER) evaluation of a direct-sequence code-division multiple-access (DS-CDMA) cellular system over a fading channel, BER curves reveal that the performance improvement of increasing m is not significant for m>4. Performance results for noninteger values of m can be estimated using the linear interpolation technique. With the derived BER expressions, a more realistic cellular model that takes into account the effects of nonidentical m and path-loss exponent is proposed and analyzed. By substituting appropriate values of m, the BER performance for a class of fading distributions such as Rayleigh and Ricean fading can be evaluated or approximated. In particular, the Nakagami approximation may be treated as a tight lower bound to the corresponding mathematically involved Ricean case     

The Marei Ika Daigaku (Syonan Medical College) during the Japanese occupation of Singapore (1942-1945)

During the Japanese Occupation of Singapore (1942-1945), Singapore was renamed Syonan (or Syonanto). The Japanese Military Administration established The Medical College on 27 April 2603 (1943) and it was known as The Marei Ika Daigaku or Syonan Medical College. It was sited at the Tan Tock Seng Hospital (Hakua Byoin). The Ika Daigaku relocated to the General Hospital, Malacca in February 2604 (1944) where it functioned till the end of the Japanese Occupation in September 1945. About 200 students from Singapore, Malaya, Sumatra and Java attended the Syonan Medical College; the students were taught mainly Japanese language and culture.     

Improvement of palm oil through breeding and biotechnology

The oil palm Elaeis guineensis is the highest oil-yielding crop and has the potential to become the major supplier of both edible oil and renewable industrial feedstock. The oil yield from wild groves is presently less than 0.5 t/ha/y. However, through breeding and selection, the oil yield of commercial plantations could reach as much as 8 t/ha/y. New planting materials also have the capability of better oil yields with high iodine value (IV), slow height increment, and larger kernels. The oil also contains considerable amounts of carotenoids (500–700 ppm), vitamin E (600–1000 ppm), and sterols (250–620 ppm). The oil yield of another oil palm species, E. oleifera, is approximately 0.5 t/ha/y with high contents of carotenoids (700–1500 ppm), vitamin E (700–1500 ppm), and sterols (3500–4000 ppm). The above traits could be improved through breeding and biotechnology. Biotechnological efforts at the Palm Oil Institute of Malaysia are directed toward the production of oil with high IV and high monounsaturated fatty acids for edible purposes and industrial uses. Isolation and manipulation of the genes involved in the biosynthesis of fatty acids are the main focus. The aim is to increase the efficiency of conversion of palmitate (C_16:0) to oleate (C_18:1). Levels of palmitate and oleate are controlled by the enzymes acyl-acyl carrier protein (ACP) thioesterase and β-keto acyl ACP synthase II. The chain termination reactions of C_16:0 and C_18:1 are independent, thus paving the way for the possibility of reducing palmitate levels by switching off the palmitoyl ACP thioesterase gene. Paper presented at the 88th AOCS Annual Meeting & Expo. May 11–14, 1997, Seattle, Washington, USA.     

Region-Reaching Control of Robots

In conventional setpoint control problem of robots, the desired position is specified as a point. However, it is interesting to observe from most human reaching movements that the desired targets are regions rather than points. In fact, when the desired region is specified arbitrarily small, it reduces to a point. In this paper, we propose a new control concept called region reaching control for robots. In this new control concept, the desired objective can be specified as a region instead of a point. Since the desired region can be specified arbitrarily small, the region control concept is also a generalization of setpoint control problem. Experimental results are presented to illustrate the performance of the proposed controllers.     

A 1-17-GHz InGaP-GaAs HBT MMIC analog multiplier and mixer with broad-band input-matching networks

An InGaP-GaAs heterojunction bipolar transistor (HBT) analog multiplier/mixer monolithic microwave integrated circuit (MMIC) is developed that adopts a Gilbert-cell multiplier with broad-band input-matching networks to widen the bandwidth up to 17 GHz. This MMIC was fabricated using a commercially available 6-in InGaP-GaAs HBT MMIC process. It achieved a measured sensitivity of above 1100 V/W for an analog multiplier and a conversion gain of better than 9 dB for a mixer. It also demonstrated a lower corner frequency and noise than that of an InP HBT analog multiplier. The measured low-frequency noise was 10 nV/sqrt(Hz), which is about half of that of an InP HBT analog multiplier with a similar architecture. The corner frequency of the low-frequency noise was roughly estimated to be 15 kHz. The measured performance of this MMIC chip with gain-bandwidth-product (GBP) of 47 GHz rivals that of the reported GaAs-based analog multipliers and mixers. The high GBP result achieved by this chip is attributed to the HBT device performance and the broad-band input-matching network.