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A hybrid cryogenic permanent-magnet undulator (CPMU) with a 15-mm period length is being constructed for a TPS Phase-II beamline. A control system for this CPMU (CU15) is under development since 2018 and is based on the Experimental Physics and Industrial Control System (EPICS) architecture and Ethernet Control Automation Technology (EtherCAT) framework. The main control components include a motor with encoder for gap adjustment, corrector magnet power supplies, ion pumps and BA gauges for the vacuum system, resistance temperature detectors (RTD) and heaters for temperature control of the cryogenic environment and magnet arrays, motion safety interlock, cryogenic system and vibration monitor system. The design and implementation of the CU15 control system will be summarized in this paper.

Pulsed magnet power supply systems used for electron beam injection and extraction have been developed for the Taiwan Photon Source (TPS) and the Taiwan Light Source (TLS). Control systems for these supplies have been implemented with well-functioning operations interfaces. To accomplish higher reliable operation, advanced real-time diagnostic toolkits for pulsed magnet power supplies had to be developed. A SoC (System-on-Chip) embedded waveform acquisition system has been designed, implemented and applied to inspect pulsed magnet power supplies during routine operation. This waveform acquisition system not only operates at the 125 MS/s sample rate, 50 MHz bandwidth and 14 bits resolution, but supports also the EPICS software framework for complete system integration. The acquired current waveforms can be immediately extracted specific characteristics to examine the status of pulsed magnet power supplies. In this paper, we summarize the design, implementation and real-time data analysis of the SoC embedded waveform acquisition system for the pulsed magnet power supplies.

A novel quench detector and acquisition system for superconducting insertion devices has been developed. This module consists of two functional components: quench detection and output latch signals for interlock purposes, which is based on a field-programmable gate array, and a data acquisition system based on a set of simultaneously sampling ACQ425ELF (ADC) modules. The data acquisition system has two concurrent modes of operation: A fast capture mode that is triggered by coil quench event or accelerator system-wide event like beam trip with sampling rate of up to 500 kHz, and a continuous data collection mode that can monitor data at 10 Hz in real time using the same acquisition system. The system was designed in a modular structure based on commercially available hardware. This approach makes the new system easy to scale for superconducting insertion devices with coil and lead voltage tap configurations. A more detailed description of the system along with test results is presented in this paper.

An insertion device (ID) is a crucial component in a third-generation synchrotron light source, which produces highly brilliant, forward-directed, and quasi-monochromatic radiation over a broad energy range. The Taiwan Photon Source (TPS) project involves building another synchrotron light source with increased electron energy. In phase I of TPS, seven in-vacuum undulators with magnetic period 22 mm (IU22) were installed; commissioning is in process. The control system for IU22 is based on an EPICS framework. The main control components include motors with encoders for gap adjustment, trimming power supplies for corrector magnets, ion pumps and Bayard-Alpert gauges for vacuum systems, temperature sensors for ID baking, and an interlock system (limit switches, emergency button) for safety. The design and implementation of the IU22 control system are summarized in this report.

The Taiwan Photon Source (TPS) is the latest-generation 3-GeV synchrotron light source. A pulsed magnet power supply system to control injection and extraction of the electron beam has been designed and implemented. The experimental physics and industrial control system (EPICS)-embedded programmable logic controllers were developed to control the power supply for pulsed magnets. The system comprises various input/output modules and a CPU module with a built-in Ethernet interface. The control information (status of the power supply, on, off, warning, reset, read/set voltage, etc.) is remotely accessible with EPICS client tools. The TPS timing system provides trigger signals to synchronous power supply of the pulsed magnets. Ethernet-based oscilloscopes with EPICS support are employed to observe the current transformer waveforms of the pulsed magnet power supply. The implemented control system of this power supply satisfies complete system integration, rich graphical user interfaces, and useful diagnostic tools. It has been running with no downtime since mid-2014, which indicates high reliability. This paper describes the design of the control system, the synchronous trigger system, the real-time monitoring system, and the operational interfaces for the TPS pulsed magnet power supply.

The Taiwan photon source (TPS) is a 3 GeV synchrotron light source now in routine operation at the NSRRC. At the beginning of beam commissioning, significant photon flux dips could be observed at injection due to a blow-up of the beam size. To eliminate this transient effect, all four kickers were rematched. The leakage field was shielded and the induced current loops at vacuum chambers in the injection area were also eliminated. These efforts reduced the horizontal betatron oscillations and orbit distortions to around one-tenth. In order to decrease the recovery time of photon dips during injection, the operational chromaticity was reduced to improve incoherent effects. After all those improvements, the photon flux dips during injection dropped to 30 % and the recovery time to less than 1 msec., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The Taiwan Photon Source (TPS) is a newly commissioned 3-GeV, third-generation, low emittance synchrotron light source located at the NSRRC in Hsinchu, Taiwan. Commissioning and machine conditioning of the TPS occurred between December 12, 2104 and the second quarter of 2016 includes Phases-I accelerator commissioning with warm cavities without insertion devices, installation of two superconducting RF cavities and 10 sets of insertion devices, Phase-II accelerator commissioning and beamlines commissioning. Up to 520 mA of beam current were stored at the storage ring during accelerator commissioning and user service started in September 2016. The machine is equipped with two superconducting RF cavities and seven in-vacuum undulators and three sets of elliptically polarizing undulators to serve phase I beam lines. Routine operation of the TPS delivers to users photons from a 300 mA stored beam current since September 2016 and of 400 mA since last November 2017. To support more insertion devices and operating at 500 mA while improving the reliability of the RF system, a five years project to install the third SRF system was started in early 2018. Insertion devices and front-end installations continue to support Phase -II and –III beam line projects until its expected completion in 2020 and 2023, respectively. Strategic plans to explore the capabilities of the TPS and to remain competitive are addressed. Future accelerator developments are also in continued discussions. This report presents the status of the TPS accelerator system and future prospects.

To monitor the position and stability of photon beams, X-ray beam position monitors (XBPMs) are installed in beamline frontends and beamlines for which the electronics infrastructure and its graphic user interface are described. Beam intensity fluctuations are calculated within different frequency ranges in order to monitor or study the photon beam stability. The calculation results are shown in the control system and saved in the archive system thus helping to monitor and analyze beam quality in real time or off-line. These XBPMs help to distinguish sources of beam motion and provide a tool to evaluate photon beam stability. Preliminary results will be discussed in this report.

In preparation for 500 mA operation at the Taiwan Pho-ton Source (TPS), we redesigned the horizontal stripline kicker for the beam feedback system to gain a smaller loss factor with higher shunt impedance. We introduced ground fenders (see Fig. 1) to this new design which resulted in the reduction of the loss factor and substantial increase of the kicker shunt impedance. The transverse profile of the kicker electrodes was matched to the race-track beam pipe in the straight sections to minimize broadband impedance. The ground fenders can reduce the leakage of image currents through the gaps between the two strip line electrodes and also help to achieve a better impedance matching for the TEM modes in the transmission lines formed by the stripline electrodes and beam pipe in the kicker. The RF design and analysis of trapped resonant modes in the kicker were simulated by the 3-D electromagnetic code GdfidL [1]. Results of the RF design and analysis of trapped resonant modes will be discussed together with analytical estimates of coupled bunch instabilities at a beam current of 500 mA., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

An IGBT (Insulated Gate Bipolar Transistor) switch based LTB (Linac-To-Booster transfer line) kicker pulser has been satisfactory tested and put for routine operation in TPS (Taiwan Photon Source). The key features of this upgraded pulser, in comparison with the previous thyratron based PFN (Pulse-Forming-Network) pulser, concerning flat-top pulse length, flatness, fall time, pulse-to-pulse stability, and postpulse ripple have been drastically improved under the electric-noisy environment that has encountered at present field experience. The available bunch train for injection into the booster has increased by a factor of 5. This performance upgrade also provides the opportunity for a steady exploration related to booster injection characteristics.

PIN-photodiodes and RadFETs are installed in the storage ring of the Taiwan Photon Source (TPS) to study beam loss distributions and mechanisms. In the highest dose area, the radiation comes mainly from hard X-rays produced by synchrotron bending magnets. During beam cleaning and after replacing a vacuum chamber, losses due to inelastic Coulomb scattering occur mostly downstream from bending magnets while elastic scattering causes electrons to get lost mainly after an elliptically polarizing undulator which has a limited vertical aperture. During the injection period, the beam loss pattern can be changed by modifying injection conditions or lattice settings. The beam loss usually happens in the injection section and small-aperture section. The injection efficiency can be improved by minimizing the detected injection loss., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

Collective beam instabilities could limit the accelerator performance if proper countermeasures are not in place. Active beam feedback systems are commonly used to suppress beam instabilities. The resistive wall impedance including phase-II insertion devices at TPS are calculated with analytical formulas. The growth rate of transverse coupled bunch instabilities due to wall impedance is estimated by theory. The RF properties of existing stripline kickers in TPS are analyzed with a 3-D electromagnetic simulation code GdfidL. Based on the above analysis, the requirements for a beam feedback system are calculated and the results are reported., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The ionization mechanism of ultraviolet matrix-assisted laser desorption/ionization (UV-MALDI) was investigated by measuring the total cation intensity (not including sodiated and potasiated ions) as a function of analyte concentration (arginine, histidine, and glycine) in a matrix of 2,4,6-trihydroxyacetophenone (THAP). The total ion intensity increased up to 55 times near the laser fluence threshold as the arginine concentration increased from 0% to 1%. The increases were small for histidine, and a minimal increase occurred for glycine. Time-resolved fluorescence intensity was employed to investigate how analytes affected the energy pooling of the matrix. No detectable energy pooling was observed for pure THAP and THAP/analyte mixtures. The results can be described by using a thermal proton transfer model, which suggested that thermally induced proton transfer is crucial in the primary ion generation in UV-MALDI.

RATIONALE: Energy pooling has been suggested as the key process for generating the primary ions during ultraviolet matrix-assisted laser desorption/ionization (UV-MALDI). In previous studies, decreases in fluorescence quantum yields as laser fluence increased for 2-aminobenzoic acid, 2,5-dihydroxybenzoic acid (2,5-DHB), and 3-hydroxypicolinic acid were used as evidence of energy pooling. This work extends the research to other matrices and addresses whether energy pooling is a universal property in UV-MALDI. METHODS: Energy pooling was investigated in a time-resolved fluorescence experiment by using a short laser pulse (355 nm, 20 ps pulse width) for excitation and a streak camera (1 ps time resolution) for fluorescence detection. RESULTS: The excited-state lifetime of 2,5-DHB decreased with increases in laser fluence. This suggests that a reaction occurs between two excited molecules, and that energy pooling may be one of the possible reactions. However, the excited-state lifetime of 2,4,6-trihydroxyacetophenone (THAP) did not change with increases in laser fluence. The upper limit of the energy pooling rate constant for THAP is estimated to be approximately 100–500 times smaller than that of 2,5-DHB. CONCLUSIONS: The small energy pooling rate constant for THAP indicates that the potential contribution of the energy pooling mechanism to the generation of THAP matrix primary ions should be reconsidered. Copyright © 2013 John Wiley & Sons, Ltd.

Ten years ago, an elliptically polarized undulator (EPU) with a periodic length of 56 mm was constructed at the Taiwan Light Source. It was the longest EPU at that time. An electron beam of energy 1.5 GeV and current 300 mA passes through the undulator gap and radiates variously polarized light in the soft X-ray spectral domain. This EPU was extensively used in a wide range of research fields, including inelastic scattering, spin-polarized photoemission spectroscopy, photoelectron emission microscopy, and soft X-ray scattering. In response to increased demand by users with differing experimental requirements and applications, the construction of an EPU with a period of length 46 mm is under way. This investigation describes many aspects of the magnetic design, the structural engineering, and the control system. As magnetic technology is undergoing dramatic advances, advanced mechanical devices, and mechanisms have been included in the new EPU design; this design and its differences from the earlier design...

Intestinal fatty acid binding protein (IFABP) is thought to participate in the intracellular transport of fatty acids (FAs). Fatty acid transfer from IFABP to phospholipid membranes is proposed to occur during protein-membrane collisional interactions. In this study, we analyzed the participation of electrostatic and hydrophobic interactions in the collisional mechanism of FA transfer from IFABP to membranes. Using a fluorescence resonance energy transfer assay, we examined the rate and mechanism of transfer of anthroyloxy-fatty acid analogs a) from IFABP to phospholipid membranes of different composition; b) from chemically modified IFABPs, in which the acetylation of surface lysine residues eliminated positive surface charges; and c) as a function of ionic strength. The results show clearly that negative charges on the membrane surface and positive charges on the protein surface are important for establishing the "collisional complex," during which fatty acid transfer occurs. In addition, changes in the hydrophobicity of the protein surface, as well as the hydrophobic volume of the acceptor vesicles, also influenced the rate of fatty acid transfer. Thus, ionic interactions between IFABP and membranes appear to play a primary role in the process of fatty acid transfer to membranes, and hydrophobic interactions can also modulate the rates of ligand transfer., Instituto de Investigaciones Bioquímicas de La Plata

Two-photon double-resonant photoionization of Ar and Xe to their autoionizing states lying between the 2 P 3/2 and 2 P 1/2 ionic thresholds was carried out with the combination of a laser system and VUV synchrotron radiation from the storage ring at NSRRC. Tuning this radiation of narrow width to a selected Rydberg state was followed by excitation to even-parity levels of autoionization states with a tunable Ti:sapphire laser. The experimental results show two-photon ionization spectra of argon with a large ratio of signal to noise. When the intermediate state 3p 5 ( 2 P 1/2 )3d′ [3/2] 1 of argon is excited, the spectrum shows a weak continuous background and three autoionizing series 3p 5 n f′[5/2] 2 ( n = 9–20), 3p 5 n p′ [3/2] 2 and 3p 5 n p′ [1/2] 0 . The latter two series were resolved partly because of improved resolution in this work and partly because their relative intensities vary with the relative polarization of two excitation sources.

SRRC has constructed a 2-meter long quasi-periodic undulator from a conventional undulator to produce an irrational harmonics radiation spectrum. A higher peak magnetic field was employed in a quasi-periodic position by adjusting the side magnet blocks and the shims to optimize the photon energy shift range and flux suppression ratio on the third and fifth harmonics of the spectrum. The magnetic design and the results of magnetic field measurement are reported. In addition, the spectral characteristics and flux are presented according to the computed and measured magnetic fields. The photon spectra of a conventional and a quasi-periodic undulator are compared.

Energy pooling has been suggested as the key process for generating the primary ions during ultraviolet matrix-assisted laser desorption/ionization (UV-MALDI). In previous studies, decreases in fluorescence quantum yields as laser fluence increased for 2-aminobenzoic acid, 2,5-dihydroxybenzoic acid (2,5-DHB), and 3-hydroxypicolinic acid were used as evidence of energy pooling. This work extends the research to other matrices and addresses whether energy pooling is a universal property in UV-MALDI.Energy pooling was investigated in a time-resolved fluorescence experiment by using a short laser pulse (355 nm, 20 ps pulse width) for excitation and a streak camera (1 ps time resolution) for fluorescence detection.The excited-state lifetime of 2,5-DHB decreased with increases in laser fluence. This suggests that a reaction occurs between two excited molecules, and that energy pooling may be one of the possible reactions. However, the excited-state lifetime of 2,4,6-trihydroxyacetophenone (THAP) did not change with increases in laser fluence. The upper limit of the energy pooling rate constant for THAP is estimated to be approximately 100-500 times smaller than that of 2,5-DHB.The small energy pooling rate constant for THAP indicates that the potential contribution of the energy pooling mechanism to the generation of THAP matrix primary ions should be reconsidered.

Intestinal absorptive cells contain high levels of expression of two homologous fatty acid-binding proteins (FABP), liver FABP (L-FABP), and intestinal FABP (I-FABP). Both bind long chain fatty acids with relatively high affinity. The functional distinction, if any, between these two proteins remains unknown. It is often hypothesized that FABP are important in intracellular transport of fatty acids. To assess whether fatty acid transport properties might differ between the two enterocyte FABPs, we examined the rate and mechanism of transfer of fluorescent anthroyloxy fatty acids (AOFA) from these proteins to model membranes using a resonance energy transfer assay. The results show that the absolute rate of AOFA transfer from I-FABP is faster than from L-FABP. Moreover, the apparent mechanism of fatty acid transfer is different between the two proteins. The rate of AOFA transfer from I-FABP is independent of ionic strength, directly dependent on the concentration of acceptor membrane vesicles, and dramatically regulated by the lipid composition of the membranes. These data strongly suggest that fatty acid transfer from I-FABP to membranes occurs by direct collisional interaction of the protein with the phospholipid bilayer. In contrast, the characteristics of fatty acid transfer from L-FABP are consistent with an aqueous diffusion-mediated process. Thus the two enterocyte FABPs may perform different functions within the intestinal absorptive cell in the regulation of fatty acid transport and utilization. It is hypothesized that L-FABP may act as a cytosolic buffer for fatty acids, maintaining the unbound fatty acid concentration, whereas I-FABP may be involved in the uptake and/or specific targeting of fatty acid to subcellular membrane sites.

In phase I of the Taiwan Photon Source (TPS) project, three elliptically polarized undulators (two EPU48 and one EPU46) are installed in the TPS storage ring. The control system for these EPU48 and EPU46 is based on the EPICS architecture; all control functionality is coordinated by the CompactPCI EPICS IOC. The main control components include motors with an encoder for gap adjustment and phase moving, a trimming power supply for corrector magnets, temperature sensors for environmental monitoring of the insertion devices, and an interlock system (limit switches, tilt sensor, emergency button) for safety. The closed-loop control is essential for the gap and phase motion to avoid the effects of magnetic forces. All motors of the gaps must be synchronized to move without tilt. An interface for ID beamline users is included to assist with experiments, such as to control the ID gap or phase and experiments on the fly. The features and benefits of the EPU48 and EPU46 control systems are summarized in this paper.

Background The anticipated rapid growth in the number of cognitively impaired older adults, declining edentulism and increasing oral health expectations suggest a greater need for comprehensive dental care and effective ways to evaluate orofacial pain in people with compromised mental function and impaired communication skills. The authors conducted a study to evaluate facial expressions as a means of identifying orofacial pain in cognitively impaired and cognitively intact older adults, compared with other available pain assessment tools. Methods The authors conducted a prospective comparative study using three alternative pain measurement tools in a sample of 22 older adults. They divided subjects into cognitively impaired and cognitively intact groups on the basis of their mental status examination scores. The pain measurement methods evaluated were facial expressions quantified by the Facial Actions Coding System (FACS); self-reported pain via the Verbal Descriptor Scale; and physiological response to pain via changes in heart rate. The pain stimuli were local anesthetic injections in subjects who required them for routine dental procedures. Results The average FACS scores during anesthetic injections were significantly higher than those during the preinjection period (prebuccal versus buccal, P = .016; prepalatal versus palatal, P = .0002). The differences between preinjection and injection segments were even higher in cognitively impaired patients than in cognitively intact patients. There were no correlations between the three pain measurements ( P > .05). Conclusions Changes in facial expression proved to be the most useful measure overall in identifying pain in both cognitively intact and cognitively impaired older patients. This measure appeared to be more sensitive in cognitively impaired patients because they demonstrated fewer facial movements in anticipation of pain stimuli.

In order to help the operation of constant current, the optics of booster to storage ring transport line (BTS) design is reinvestigated[1]. The initial Twiss parameters are derived by measurement. The optics of the transport line is readjusted according to the measured initial beam parameters. The design of pulse width of the injection kicker is also changed from 1.2 μs to 2.0 μs. The injection scheme is reviewed and the effects of the kicker error on both injected and stored beam are investigated and shown in this report.

The mammalian fatty acid-binding proteins (FABPs) are thought to be important for the transport and metabolism of fatty acids in numerous cell types. The transfer of FA from different members of the FABP family to membranes has been shown to occur by two distinct mechanisms, an aqueous diffusion-based mechanism and a collisional mechanism, wherein the FABP interacts directly with membrane acceptors. Much of the work that underlies this concept comes from efforts using rodent FABPs. Given the increasing awareness of links between FABPs and several chronic diseases in humans, it was important to establish the mechanisms of FA transfer for human FABPs. In the present studies, we examined the rate and mechanism of fatty acid transfer from four pairs of human and rodent (rat or mouse, as specified) FABPs: hLFABP and rLFABP, hIFABP and rIFABP, hHFABP and rHFABP, and hAFABP and mAFABP. In the case of human IFABP, both the Ala54 and Thr54 forms were examined. The results show clearly that for all FABPs examined, the mechanisms of ligand transfer observed for rodent proteins hold true for their human counterparts. Moreover, it appears that the Ala to Thr substitution at residue 54 of the human IFABP does not alter the fundamental mechanism of ligand transfer to membranes, but nevertheless causes a consistent decrease in the rate of transfer.

The mammalian fatty acid-binding proteins (FABPs) are thought to be important for the transport and metabolism of fatty acids in numerous cell types. The transfer of FA from different members of the FABP family to membranes has been shown to occur by two distinct mechanisms, an aqueous diffusion-based mechanism and a collisional mechanism, wherein the FABP interacts directly with membrane acceptors. Much of the work that underlies this concept comes from efforts using rodent FABPs. Given the increasing awareness of links between FABPs and several chronic diseases in humans, it was important to establish the mechanisms of FA transfer for human FABPs. In the present studies, we examined the rate and mechanism of fatty acid transfer from four pairs of human and rodent (rat or mouse, as specified) FABPs: hLFABP and rLFABP, hIFABP and rIFABP, hHFABP and rHFABP, and hAFABP and mAFABP. In the case of human IFABP, both the Ala54 and Thr54 forms were examined. The results show clearly that for all FABPs examined, the mechanisms of ligand transfer observed for rodent proteins hold true for their human counterparts. Moreover, it appears that the Ala to Thr substitution at residue 54 of the human IFABP does not alter the fundamental mechanism of ligand transfer to membranes, but nevertheless causes a consistent decrease in the rate of transfer.

Matrix-assisted laser desorption ionization (MALDI) has been widely used in the mass analysis of biomolecules; however, there are a lot of debates about the ionization mechanisms. Previous studies have indicated that S1-S1 annihilation might be a key process in the generation of primary ions. This study investigates S1-S1 annihilation by examining the time-resolved fluorescence spectra of 12 matrices. No S1-S1 annihilation was observed in six of these matrices (3-hydroxy-picolinic acid, 6-aza-2-thiothymine, 2,4-dihydroxy-acetophenone, 2,6-dihydroxy-acetophenone, 2,4,6-trihydroxy-acetophenone, and ferulic acid). We observed two matrix molecules reacting in an electronically excited state (S1) in five of these matrices (2,5-dihydroxybenzoic acid, α-cyano-4-hydroxycinnamic acid, 2,5-dihydroxy-acetophenone, 2,3-dihydroxybenzoic acid, and 2,6-dihydroxybenzoic acid), and S1-S1 annihilation was a possible reaction. Among these five matrices, no S1-S1 annihilation was observed for 2,3-dihydroxybenzoic acid in typical peak power region of nanosecond laser pulses in MALDI, but a very small value of reaction rate constant was observed only in the high peak power region. The excited-state lifetime of sinapinic acid was too short to determine whether the molecules reacted in an electronically excited state. No correlation was observed between the ion generation efficiency of MALDI and S1-S1 annihilation. The results indicate that the proposal of S1-S1 annihilation is unnecessary in MALDI and energy pooling model for MALDI ionization mechanism has to be modified.

A photoemission plate-type photon beam monitor has been fabricated and tested using a HeI (21 eV) lamp light source. The sensitivity ΔI IΔs , obtained by using a picoammeter (Keithley Model 617), is 3.38/mm for both OFHC copper plate and tungsten plate which agrees with the theoretical value. Current-voltage converting and voltage-amplifying electronics have also been devised to measure the sensitivity directly. The degradation introduced by the offset voltage of the electronic components has been analyzed. The sensitivity of this monitor has been verified to depend on both the integral part of the spatial distribution of the light on the plate and the background current generated by the picoammeter.

A 132 pole elliptically polarizing undulator (EPU5.6) with magnetic period of 5.6 cm for production of brilliant and soft X-rays has been constructed and performed the field measurement at synchrotron radiation research center (SRRC). The "Apple-II" type device was selected for this EPU5.6 structure. The key factors in the construction and assembly process stage are described. In addition, the shimming algorithm for the magnetic field adjustment, the performance of the mechanical structure, magnetic field distribution without the field shimming are presented in this paper. Meanwhile, the control performance is also discussed.

The family of mammalian fatty acid-binding proteins (FABP) includes at least ten distinct gene products, and additional homologues continue to be reported. The FABP were first discovered in the early 1970’s as abundant cytoplasmic proteins which bound long chain fatty acids (FA) in vitro 11-3. In the ensuing years, a great deal of information has been obtained about their tissue distributions, ligand binding affinities and specificities, developmental regulation and, more recently, their tertiary structures 3-5 Their functions, however, remain largely undefined. Among the first members of the FABP family to be purified were those from intestine 1,6, liver 1,2 and heart7. In all these tissues, fatty acid flux is considerable, and thus it was proposed that the FABP are necessary for large-scale intracellular binding of fatty acids. More recently, FABP family members have been identified in other tissues that are generally considered to be lipid-active, e.g. adipose tissue 8, as well as other tissues, e.g. brain 9,10. In addition, the FABP have been suggested as modulators not only of lipid metabolism and cellular FA flux, but also of gene expression, cell growth and differentiation, etc.11-13 It is also of interest that a number of cell types, most notably intestinal enterocytes, express high and approximately equivalent levels of two separate FABP’s 14 suggesting a functional specificity for different family members. In all of these tissues and for all of these putative functions, a role for FABP in cytoplasmic transport of FA from sites of entry and/or synthesis to sites of utilization and function, is implied.

Two GaAs/AlGaAs passive semiconductor channel waveguides of the multiple quantum well structure have been made by molecular beam epitaxial growth technique. The specimens were studied by photoreflectance (PR) spectroscopy at room temperature. The micro-structures of the PR spectral energy features on the layers of the multiple quantum wells and band edge transition were observed. The optical transition energy features were fitted by the first derivative Gaussian function form (GFF) and the peak positions of the theoretical prediction for the micro-structures were calculated by using effective mass envelope function model. The energy features of the micro-structure in PR spectra were identified and interpreted. The results show that PR is a powerful tool to characterize the optical waveguides of multiple quantum well structure.

The electrolyte electroreflectance and reflectivity measurements were used to study the etching process and analyze the etching mechanism of etched anodic oxide film on HgCdTe. The observed shift of the energy peak in reflectance spectrum can be explained by the surface roughness. It was found that the oxide etched by HCl or HNO3 does not recover the original reflectivity spectra due to the surface characteristics, but lactic acid does. The multiple reflection theory was used to calculate the thickness and the etching rate of the oxide film. The etching characteristics of lactic acid have also been studied for different concentrations.

of Electrical EngineeringTaipei, Taiwan, Republic of ChinaFeng-Yuh Juang, Tin-Fung Chang and Jia-Song WuChung-Shan Institute of Science and TechnologyLung-Tan, Taiwan, Republic of ChinaABSTRACTElectrolyte electroreflectance (EER) is used to investigate the near surface properties of HgCdTe. Weused the technique of EER coupled with electrochemical etching to study the characteristics of HgCdTe.Annealing of B ion-implanted HgCdTe with ZnS encapsulation and anode sulfide film is studied. Theresults of fitting parameters show that a highly disordered surface layer exists after implantation, and anobvious recovery occurs after the sample is annealed at 2000 C It also shows that there are no obviousimprovements when the sample is annealed at 3000 C. The sample encapped with CdS film is better thanuncapped CdS film. We found that the composition of Cd at the surface changes due to the chemicalinteraction of anode sulfide film. It also shows that the sulfide active CdS film can improve the adherenceof ZnS to the MCT substrate and make the sample more stable.

The excitonic photoreflectance (PR) spectra of GaAs/A1GaAs multiple quantum wells, grown by the molecular beam epitaxial (MBE) technique, were investigated at oblique and near-normal incident angle with different polarized probe lights. The PR spectra have been measured at room temperature using He-Ne laser as a pumping beam in order to study the variations of the spectral line shapes. The experimental results show that the usefulness of the electromodulation to characterize the microstructure of the substrate may be enhanced if we take in account the polarization state of the probe light which is incident at larger oblique angle. The PR spectra were fitted by a third order derivative functional line shape, thus making it possible to determine the energy band gap, broadening parameters, amplitudes, and the phases of the spectral features precisely.

The thermal annealing properties of B+ implantation in HgCdTe are investigated by the electrolyte electroreflectance technique. The various thermal annealing conditions, such as temperature, time, and presence or absence of ZnS encapsulated passivation, are used as parameters to study the surface properties of HgCdTe and are characterized by electrolyte electroreflectance spectroscopy. We found that Hg accumulates near the surface region of an encapsulated sample, and Hg is lost at a depth of 1600 Å. The quality of the crystal is much improved when the sample is annealed at 200°C for a duration of over 30 minutes.