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This work demonstrates an enhancement mode heterojunction bipolar p-FET (HEB-PFET) structure with a AlGaN/GaN heterojunction bipolar transistor (HBT) integrated on the drain side. Such device design notably contributes to the ultra-high output current density, which is conventionally limited by the low hole mobility and concentration in the p-FETs. The HEB-PFET exhibits an output current density of 241 mA/mm, which is 134 times larger compared to the conventional p-FET (C-PFET) and 2.4 times of the homojunction bipolar p-FET (HOB-PFET). This can be attributed to a better current gain of HBT than homojunction bipolar transistor (BJT). An optimized HEB-PFET of 6 nm p-GaN layer beneath the gate is proposed, where ION/IOFF is >1011, and Vth is −0.44 V. Additionally, thermal stabilities are studied with temperature changes from 300 K to 425 K. Moreover, a semi-empirical compact model is presented to visually explain the working principle of the HEB-PFET. [ABSTRACT FROM AUTHOR]

In the recent decades of high energy physics research, it was demonstrated that strongly interacting quark-gluon plasma (sQGP) is created in ultra-relativistic nucleus–nucleus collisions. Investigation and understanding of properties of the hadronic matter is among the important goals of NA61/SHINE collaboration at CERN SPS. Mapping of the phase diagram is achieved by varying the collision energy (5GeV

We are pleased to pick up this continuing series on individuals within our community who have made significant impacts in the field of microwaves, and to the world, over the course of their careers. This issue's Microwave Pioneer article is about Mau-Chung Frank Chang, who perhaps more than anyone else, is responsible for the widespread commercial use of the heterojunction bipolar transistor (HBT). Professor Chang is also an example of a researcher who very successfully crossed over from industry to academia and from research to management and back, having spent time in charge of a large team of commercial semiconductor fabrication engineers and as President of a major academic university. Throughout his very varied career, he always emphasized two things: the first he attributes to his mother's teaching - the great power of connecting individuals together to solve problems rather than trying to lead them to a solution, and the second – which is all his own – the fortitude to take on and stick with challenges that seemed daunting to others. We think you will benefit from hearing Frank's story and in getting to know him on a more personal level.

In this study, we conduct a comprehensive examination of the influence of hydrogen (H2) carrier gas flux on the uniformity of epitaxial layers, specifically focusing on the InGaP single layer and the full structure of the InGaP/GaAs heterojunction bipolar transistor (HBT). The results show that an elevated flux of H2 carrier gas markedly facilitates the stabilization of layer uniformity. Optimal uniformity in epitaxial wafers is achievable at a suitable carrier gas flux. Furthermore, this study reveals a significant correlation between the uniformity of the InGaP single layer and the overall uniformity of HBT structures, indicating a consequential interdependence. [ABSTRACT FROM AUTHOR]

RF PAs need to be reliable enough to protect them from damage under load mismatch conditions. This paper investigated the characteristics of GaAs heterojunction bipolar transistors (HBTs) under load mismatch conditions using a novel reverse wave injection technique to realize large VSWR ruggedness measurement with the circle centered at 50 Ohm and optimal impedance separately to analyze the device in real applications. With a real-time waveform measurement system, the RF voltage and current waveform information can be acquired, which provide a more-accurate view of what is occurring at the current generator plane of the HBT device. Thereby, the potential failure mechanisms and load impedance can be identified to design the most-suitable PA circuits in communication systems. [ABSTRACT FROM AUTHOR]

Introduction. The characteristics of solid-state microwave switches are subject to different requirements depending on the application area and technical problems to be solved. No versatile solution exists that could satisfy all requirements at once. The desire to improve the parameters of switches has led to the emergence of devices based on various technologies. In order to elucidate the current trends and future prospects in the field of switch technologies, semiconductor devices that form the basis of switch circuits should be considered.Aim. To review transistor types used in solid-state switches.Materials and methods. The search and selection of literature sources for review was based on the chronological principle. The search depth for considering the parameters of finished components was no more than 10 years, for considering technologies and structural solutions – more than 10 years. This choice was explained by our desire to trace the history of development and approaches to the creation of semiconductor devices that have led to the emergence of the modern component base. The final array of sources comprised scientific publications presenting factual information on the objects under consideration.Results. The types, structures, materials, characteristics and manufacturing technologies of transistors used in switches are considered. The achievable parameters of the switches based on the considered devices are presented. Conclusion. The choice of a particular transistor type for switches depends on the requirements for the parameters and performance characteristics of the final device. At present, transistor solutions for switches are dominated by field-effect transistors (FETs) of various types: GaAs and GaN transistors with a high electron mobility (HEMT) and Si CMOS FETs implemented by standard as well as silicon-on-insulator and silicon-on-sapphire technologies. The conducted literature review has revealed prospects for the development of technologies based on BiCMOS heterojunction bipolar transistors.

A wideband amplifier up to 50 GHz has been implemented in a 0.25 μm, 200 GHz ft SiGe BiCMOS technology. Die size was 0.7×0.73 mm2. The two-stage design achieves more than 11 dB gain over the whole 20 to 50 GHz band. Gain maximum was 14.2 dB at 47.5 GHz. Noise figure was lower than 9 dB up to 34 GHz and a current of 30 mA was drawn from a 4 V supply. To the author’s best knowledge this is the highest gain bandwidth product of a monolithic SiGe HBT amplifier ever reported.

RF PAs need to be reliable enough to protect them from damage under load mismatch conditions. This paper investigated the characteristics of GaAs heterojunction bipolar transistors (HBTs) under load mismatch conditions using a novel reverse wave injection technique to realize large VSWR ruggedness measurement with the circle centered at 50 Ohm and optimal impedance separately to analyze the device in real applications. With a real-time waveform measurement system, the RF voltage and current waveform information can be acquired, which provide a more-accurate view of what is occurring at the current generator plane of the HBT device. Thereby, the potential failure mechanisms and load impedance can be identified to design the most-suitable PA circuits in communication systems.

A broadband power amplifier in a 250-nm InP HBT technology is presented, working at full $H$ -band (220–320 GHz). A cascode transistor is employed as a power cell to achieve high gain and power at $H$ -band. Two-stage cascode power amplifier is designed with input and output impedance of not 50 but 25 $\Omega $ , reducing the impedance transformation ratio and allowing the broadband matching networks. Two power-amplifier channels are power-combined using on-chip baluns which perform the impedance transformation from 25 to $50~\Omega $ . The balun operation is based on the electromagnetic field conversion between coplanar waveguide and microstrip line. It does not rely on long transmission lines with frequency-dependent length, so that it occupies a very compact area and exhibits a broadband performance. It also enables power amplifiers to operate in the balanced mode, allowing the area reduction and stable operation. Substrate modes and in-band resonances in InP substrate, which seriously degrade circuit performance and limits bandwidth, are effectively suppressed by the reduced on-chip ground and balanced operation. The fabricated power amplifier shows a measured small-signal gain of 20.8 dB at 232 GHz with a 3-dB bandwidth larger than 51 GHz (20.8%). Output power also exhibits a broadband performance of 8.0± 1.5 dBm from 220 to 295 GHz with power gain larger than 10.5 dB, corresponding to a large-signal 3-dB bandwidth larger than 75 GHz. This belongs to an excellent bandwidth in both small- and large-signal performance among the reported $H$ -band power amplifiers.

In this paper the state of the art in RF switches for mm-wave frequency range is summarized and evaluated. Several leading technologies is presented from typical semiconductor devices based on transistors and diodes on Si, SiGe or III-V semiconductor substrates to more unconventional solutions such as microelectromechanical or phase-change material switches. The most important parameters and characteristics for those technologies are gathered and compiled for comparison. Besides different technologies, also various switch topologies of mm-wave switches are presented, assessed and compared. Furthermore, new emerging technological solutions approaching mm-wave range involving two-dimensional materials are also presented. Their evaluation is focused on proposed designs and current results for experimentally evaluated prototypes. Although the performance of these devices are currently not competitive with more traditional approaches, some reported results near the mm-wave range makes them a promising solution for future mm-wave switches and an interesting topic for further research and development.

The biodiversity of Ecuadorian stingless bees is almost 200 species. Traditional pot-honey harvest in Ecuador is mostly done from nests of the three genera selected here Geotrigona Moure, 1943, Melipona Illiger, 1806, and Scaptotrigona Moure, 1942. The 20 pot-honey samples collected from cerumen pots and three ethnic honeys “abeja de tierra”, “bermejo”, and “cushillomishki” were analyzed for qualitative and quantitative targeted 1H-NMR honey profiling, and for the Honey Authenticity Test by Interphase Emulsion (HATIE). Extensive data of targeted organic compounds (41 parameters) were identified, quantified, and described. The three honey types were compared by ANOVA. Amino acids, ethanol, hydroxymethylfurfural, aliphatic organic acids, sugars, and markers of botanical origin. The number of phases observed with the HATIE were one in Scaptotrigona and three in Geotrigona and Melipona honeys. Acetic acid (19.60 ± 1.45 g/kg) and lactic acid (24.30 ± 1.65 g/kg) were particularly high in Geotrigona honey (in contrast to 1.3 g/kg acetic acid and 1.6 g/kg lactic acid in Melipona and Scaptotrigona), and with the lowest fructose + glucose (18.39 ± 1.68) g/100g honey compared to Melipona (52.87 ± 1.75) and Scaptotrigona (52.17 ± 0.60). Three local honeys were tested using PCA (Principal Component Analysis), two were assigned with a correct declared bee origin, but “bermejo” was not a Melipona and grouped with the Scaptotrigona cluster. However after HCA (Hierarchical Cluster Analysis) the three honeys were positioned in the Melipona-Scaptotrigona cluster. This research supports targeted 1H-NMR-based profiling of pot-honey metabolomics approach for multi-parameter visualization of organic compounds, as well as descriptive and pertained multivariate statistics (HCA and PCA) to discriminate the stingless bee genus in a set of Geotrigona, Melipona and Scaptotrigona honey types. The NMR characterization of Ecuadorian honey produced by stingless bees emphasizes the need for regulatory norms. A final note on stingless bee markers in pot-honey metabolites which should be screened for those that may extract phylogenetic signals from nutritional traits of honey. Scaptotrigona vitorum honey revealed biosurfactant activity in the HATIE, originating a fingerprint Honey Biosurfactant Test (HBT) for the genus in this set of pot-honeys.

This paper presents a compact GaAs HBT Doherty power amplifier (DPA) with integrated three stages for the 5G application. Different from most GaAs HBT PAs, this PA is designed in the asymmetric Doherty structure with a class‐J operation mode. The output parasitic capacitance of the carrier amplifier is extracted and absorbed into the matching network, generating a π‐type structure and realizing the impedance inverter. In addition, the phase alignment between the carrier and peaking amplifier is implemented skillfully by employing input, inter‐stage, and output matching networks. The fabricated Doherty PA achieved a high gain of 32.5–34.1 dB and P1dB of 34–34.5 dBm. The 42.8%–45.1% and 28.7%–30.1% PAE are obtained at P1dB and 7.5 dB PBO under a continuous‐wave signal test across 3.3–3.6 GHz, respectively. A 100 MHz 64‐quadratic‐amplitude modulated (QAM) signal with a 7 dB peak‐to‐average power ratio (PAPR) is also applied to the proposed DPA at 3.5 GHz. The measured adjacent channel power ratio (ACPR) is lower than −37.7 dBc without any linearization. [ABSTRACT FROM AUTHOR]

The synthesis of MMT and poly(o-anisidine) (MMT/POA) clay nanocomposites was carried out by using the chemical oxidative polymerization of POA and MMT clay with POA, respectively. By maintaining the constant concentration of POA, different percentage loads of MMT clay were used to determine the effect of MMT clay on the properties of POA. The interaction between POA and MMT clay was investigated by FTIR spectroscopy, and, to reveal the complete compactness and homogeneous distribution of MMT clay in POA, were assessed by using scanning-electron-microscope (SEM) analysis. The UV–visible spectrum was studied for the optical and absorbance properties of MMT/POA ceramic nanocomposites. Furthermore, the horizontal burning test (HBT) demonstrated that clay nanofillers inhibit POA combustion. [ABSTRACT FROM AUTHOR]

An efficient, broadband SiGe HBT cascode nonuniform distributed power amplifier (NDPA) is presented for low-cost, fully integrated Si-based phased arrays. Optimum load impedances at each SiGe HBT cascode in a four-stage NDPA core are obtained by scaling the characteristic impedance ($Z_{0}$) of the collector transmission lines (TLs) and tapering the SiGe HBT emitter area simultaneously. A novel compact, lumped-element two-section $\lambda $ /4 output impedance transformer (OIT) is proposed to lower the NDPA load impedance ($Z_{L}$) from 50 to 25 $\Omega $ over more than one decade bandwidth (BW). Each $\lambda $ /4 impedance transformer is realized by four cascaded CLC $\pi $ -networks integrated into a single three-turn symmetric inductor in order to achieve compact size, high passive efficiency, and high LC cutoff frequency ($f_{c}$). The systematic design approach of a lumped-element $\lambda $ /4 impedance transformer with an arbitrary $Z_{0}$ is described in detail. The prototype NDPA was fabricated in 0.13- $\mu \text{m}$ SiGe HBT BiCMOS technology. The proposed SiGe HBT cascode NDPA supports both high linearity (HL) and high gain (HG) modes, each suited to a specific application. The NDPA attains a peak power gain of 10.3/12.5 dB, a saturated output power ($P_{\mathrm {out}}$) of 21.3/21.5 dBm, and a power added efficiency (PAE) of 12.2%/12.5%–21.6%/22.0% for HL/HG modes, with a 3-dB BW from 1.5 to 24.0 GHz. The NDPA delivers 13.0-dBm average $P_{\mathrm {out}}$ with a PAE of 10.0% at 6-Gbit/s data rate 64 QAM modulation. [ABSTRACT FROM AUTHOR]

The manufacturing technology for heterojunction bipolar transistor (HBT) is different from the one used for bipolar silicon junction transistor (BJT). The base in case of BJT is manufactured by using diffusion and the diffusion laws determine a Gaussian type of profile in the base. HBT devices are manufactured using molecular epitaxy which gives a contact doping profile. In case of HBT, producing an internal field by using uniform doping is no more possible. This is the reason why was used in the gradation of the molar composition. The Analysis using Octave soft was made for the transit time through the base of the drift HBT transistors type GaAs/AlxGa1-xAs. [ABSTRACT FROM AUTHOR]

Microwave-induced thermoacoustic (TA) imaging, combining high microwave contrast with high ultrasonic resolution has the potential to revolutionize applications such as continuous healthcare monitoring, point-of-care imaging, and biometric authentication. However, the size, cost, and integration of a high-power microwave transmitter is a key bottleneck in making TA imaging truly portable, affordable, and ubiquitous. Toward that end, this work presents a compact 4.9-GHz pulsed power amplifier (PA) with a 4.87-mm2 active area implemented in a 55-nm BiCMOS technology, operating in a duty-cycled mode and achieving 37.3-dBm peak output power—the highest demonstrated peak power in PAs fabricated on a silicon substrate with deep submicron CMOS integration. We also reconstruct the first known high-fidelity TA images of tissue phantoms using an integrated silicon PA. [ABSTRACT FROM AUTHOR]

Although electronic word-of-mouth via social networking sites (or sWOM) greatly induced online shopping, its importance in shopping decisions during the coronavirus disease (COVID-19) pandemic has not been holistically considered. Based on the necessity of sWOM, uses and gratifications theory (UGT), and health belief theory (HBT), this study frames a consumer shopping tendency model toward sWOM in the context of the pandemic. A web-based survey was designed to collect data from 403 respondents who are inclined to patronize e-stores during the pandemic. Next, the measurement model is examined using a two-step method of structural equation modeling. The findings specify that sWOM is an influential communication mode for online shopping in the pandemic. sWOM is of primary importance to information quality. Moreover, utilitarian value, social value, perceived threat, and self-efficacy toward shopping tendency are significantly motivated by sWOM. Lastly, information quality, utilitarian value, social value, and perceived threat are major predictors of shopping tendency during Covid-19. Finally, theoretical and practical implications are discussed.

This letter presents a millimeter-wave silicon-germanium (SiGe) distributed attenuator which uses a transformer-based attenuation core. The nonlinearities of the SiGe heterojunction bipolar transistor (HBT) are managed using an RC-load, which linearizes the device impedance versus bias. In addition, a dual-resonance transformer is used to support broadband operation, while providing control over the attenuator insertion phase. Two attenuators, one using transmission line-based impedance transformers, and one using transformer-based impedance transformers, were designed and fabricated in a 180-nm SiGe bipolar and CMOS (BiCMOS) technology platform. The attenuators achieve competitive performance in terms of bandwidth and phase error, but with low insertion loss and large attenuation range. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are recognized as a toxic, mutagenic and/or carcinogenic compounds, and their pollution of soil and aquifer is of increasing environmentally risk. Laccases (E.C. 1.10.3.2) are phenoloxidases catalyze the oxidation of PAHs in the presence of a mediator compound and hyacinth plant. In this study laccase from Trametes versicolor was immobilized into chitosan, and the potential to oxidize anthracene in the presence of 1-hydroxybenzotriazole (HBT) was examined. Results indicated that the immobilization enhanced the stability of laccase against temperature, pH, inhibitors and loading time compared with the other cases. The immobilized laccase-mediator system was as efficient as the free enzyme for oxidizing the tested PAHs. After 24h. of incubation, immobilized laccase–HBT showed a system oxidization more than immobilized laccase without (HBT) of PAHs; Chitosan with hyacinth plant and (HBT) resulted better conversion than chitosan with or without HBT. These results indicate a new chance for applying the immobilized laccase in bioremediation.

Copyright of Journal of Tiangong University is the property of Journal of Tianjin Polytechnic University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, spoiled maize silage (SMS) and cattle manure were co-digested at five different mixtures by the Hohenheim Batch Yield Test unit under mesophilic conditions to explore biogas production possibilities of these wastes together. The mixtures were 100% cattle manure, 100% SMS, 85% cattle manure + 15% SMS, 70% cattle manure + 30% SMS, and 55% cattle manure + 45% SMS. Chemical properties of raw materials and mixtures, including crude fat, dry matter, organic matter, and acid detergent fiber (ADF) contents were determined. As the amount of SMS in the mixtures increased, biogas and methane production increased. The highest cumulative specific biogas and methane production were determined for 100% SMS as 0.62 Nm3 kg-1 organic matter (OM) and 0.31 Nm3 kg-1 OM, respectively, where Nm3 is the volume of biogas under normal conditions. Methane content of the mixture containing SMS (49.99% to 51.87%) was higher than that of cattle manure only (44.01%). Furthermore, the mixtures which had lower ADF content yielded more methane and biogas. In conclusion, the efficiency of biogas and methane production can be increased by applying the co-digestion technique. [ABSTRACT FROM AUTHOR]

This article presents a state-of-art review of on-wafer S-parameter characterization of THz silicon transistors for compact modelling purpose. After, a brief review of calibration/de-embedding techniques, the paper focuses on the on-wafer calibration techniques and especially on the design and dimensions of lines built on advanced silicon technologies. Other information such as the pad geometry, the ground plane and the floorplan of the devices under test are also compared. The influence of RF probe geometry on the coupling with the substrate and adjacent structures is also considered to evaluate the accuracy of the measurement, especially using EM simulation methodology. Finally, the importance of measuring above 110 GHz is demonstrated for SiGe HBT parameter extraction. The validation of the compact model is confirmed thanks to an EM-SPICE co-simulation that integrates the whole calibration cum de-embedding procedure.

This letter presents a lower phase noise voltage‐controlled oscillator (VCO) uses two differential amplifiers in cross‐coupled feedback and is named as a buffer‐reused VCO in the TSMC standard 0.18 μm SiGe BiCMOS processes. The die area is 1.1 × 1.2 mm2. The first amplifier uses HBT stacking on nMOSFET and the second amplifier uses nMOS amplifier. Its power consumption of 2.65 mW with output buffer current, the phase noise is −128.81 dBc/Hz at 1 MHz offset frequency from the center frequency 4.19 GHz. The figure of merit (FOM) is −194.08 dBc/Hz. [ABSTRACT FROM AUTHOR]

This study presents a wideband two-stage linear power amplifier, operating from 1.9 to 2.6 GHz, using a mutually coupled differential inductor based on GaAs hetero-junction bipolar transistor (HBT). A part of the two-section inter-stage matching circuit comprises a mutually coupled differential inductor, which widens the operating band of the matching circuit and reduces the circuit size. In addition, it is optimized to linearly operate in the wide frequency band using a wideband balun at the input and output stages. The fabricated linear power amplifier exhibits a maximum output power of 22.0 dBm～24.0 dBm and efficiency of 33.0 %～39.0 % in the 1.9 GHz～ 2.6 GHz frequency band. An IMD3 of −30.0 dBc at two-tone signal, with high efficiency of more than 33.0 % was achieved at the linear output power of 22 dBm. [ABSTRACT FROM AUTHOR]

Current mirrors (CMs) are essential building blocks for biasing electronic circuits. The present work demonstrates that errors in mirroring ratios increase at cryogenic temperatures, for all types of SiGe HBT and CMOS CMs. The sources of errors are attributed to the mismatch in operating conditions and a combination of process variations and layout effects. In particular, the effects of layout on device current are found to increase significantly at low temperatures, which can potentially contribute more to the CM error than process variations. Among all investigated CM configurations, the simple CM based on large geometry SiGe HBTs is the most versatile option with small errors, a large operational range, and a simple layout. [ABSTRACT FROM AUTHOR]

This letter proposes a new emitter-base-collector-base-emitter (EBCBE) SiGe HBT suited for high power RF switches. Two collector-base-emitter (CBE) SiGe HBTs are merged into a single EBCBE SiGe HBT, not only to double its maximum voltage swing, but also to decrease its active area and parasitics. To further boost its power handling, a capacitive voltage distribution and a collector floating are incorporated into the new EBCBE SiGe HBT. A X-band λ/4 shunt single-pole-double-throw (SPDT) switch using the EBCBE SiGe HBT achieves measured insertion losses and isolations of 1.2/1.3 and 29.2/23.0 dB at 10 GHz in TX/RX modes, respectively. In TX mode, measured input 1-dB power compression (P1dB) is 25.4 dBm, and it can be extended to 28.5 dBm at −0.6 V base bias of the EBCBE SiGe HBT. [ABSTRACT FROM AUTHOR]

In this paper, an emitter-length scalable noise and small signal model for InP heterojunction bipolar transistor (HBT) are presented. A set of scalable expressions for noise parameters based on hybrid-π topology in the low-frequency ranges are derived. The analytical and experimental results show that under the same bias condition, good emitter-length scaling of the noise and small signal model parameters can be achieved between 1.6μm ×10 μm, 1.6μm × 20 μm and 1.6μm × 30 μm InP HBTs.

Empirical models have been widely and successfully used in device modeling in the past few decades. However, they are becoming increasingly intricate to accurately capture the complex thermal effects in semiconductor devices. Therefore, the aim of this work is to utilize a general dimension-reduction method to quickly and accurately construct large-signal models of semiconductor devices with consideration of thermal effects. In general, the junction voltage dimension is represented by empirical functions, whereas the junction temperature dimension is described by the first-order Taylor series approximation. The final analytical current model is a combination of two independent sets of empirical functions. These functions are constructed from pulsed I-V measurements at different ambient temperatures. The percentages of different components are controlled by the thermal level. Two commercial InGaP/GaAs heterojunction bipolar transistors are investigated to verify the effectiveness of this method. The large-signal models are implemented in Advanced Design System. Excellent agreement is achieved between measurement and simulation of the I-V characteristics, S-parameters, and power sweeps. The dimension reduction method is able to effectively reduce the number of equations and parameters because the temperature dimension is expanded by using a Taylor series. In addition, this method would be applied to the thermal modeling of various devices based on new materials or process technologies. Accordingly, the dimension reduction method is powerful and useful in fast and accurate thermal modeling of microwave semiconductor devices.

In this study, biogas production efficiencies of mixtures obtained by adding corn silage (CS) to citrus industrial wastes at different ratios were determined. Orange (OJPW) and tangerine processing juice wastes (TJPW) (crusts and shells) were selected as materials in the study. 25%, 50%, 75% of CS was added to these selected wastes. Changes in the obtained mixture chemical properties (dry matter, dry organic matter, crude ash, crude protein, crude oil, Acid Detergent Fiber (ADF), Neutral Detergent Fiber (NDF)), biogas production and methane content in the biogas were investigated. The results of the study showed that the highest crude protein content was found in 100% TJPW (10%), raw fat percentage in 100% TJPW (5.14%), dry matter content in 100% CS (93.56%), ADF in 100% CS (22.74%) and the NDF in a mixture of 25% OJPW + 75% CS (45.08%). The highest methane production was determined for a mixture of 100% TJPW and 50% TJPW + 50% OJPW (0.46 m3 kg-1 ODM). Also the highest biogas production was determined in a mixture of 50% OJPW + 50% TJPW (0.90 m3 kg-1 ODM). The mixing of CS in TJPW and OJPW reduced significantly the production of methane and biogas in the mixture. As a result of the statistical analysis, significant differences (P≤0.05) were found in both methane and biogas production of agricultural wastes.

This article describes the design and performance of a 140-GHz SiGe and a 100-GHz InP triple-stacked HBT distributed amplifier with active bias terminations. The active bias network is configured to extend the practical low-frequency operation while maintaining gain flatness and linearity. Triple-stacked HBTs are used to increase the gain–bandwidth and linear output capability. The SiGe design is based on HBTs with a peak ƒT/ƒmax of 300/350 GHz and achieves 11.7 dB of gain and a bandwidth from baseband to 140 GHz. The InP HBT design is based on DHBTs with a peak ƒT/ƒmax of 250/250 GHz and obtains a gain of 10.8 dB and a bandwidth of 100 GHz. Although the SiGe design achieves 1.5 times higher gain–bandwidth, the InP DHBT design achieves ~3–4.5 dB greater IP3, P1~dB, and P3 ~dB while consuming only ~23% higher dc power. These results represent the first broadband performance comparison of near-identical (apples–apples) DA designs implemented in SiGe and InP HBT device technologies. Although there are previous reports of larger bandwidth distributed amplifiers in both InP and SiGe technologies demonstrated up through 200 GHz, the InP and SiGe monolithic microwave integrated circuits (MMICs) described in this article are believed to represent the highest bandwidths reported for HBT DAs using practical on-chip active bias terminations. [ABSTRACT FROM AUTHOR]

Copyright of Al-Mustansiriyah Journal of Science is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Hanbury Brown and Twiss (HBT) interferometer was proposed to observe intensity correlations of starlight to measure a star's angular diameter. As the intensity of light that reaches the detector from a star is very weak, one cannot usually get a workable signal-to-noise ratio. We propose an improved HBT interferometric scheme incorporating optical parametric amplifiers (OPA) into the system to amplify the correlation signal. Remarkably, for weak star light, the signal-to-noise ratio (SNR) in the new HBT interferometric scheme is much better than that of conventional HBT interferometer. Our work is valuable in measuring a star whose intensity at the detector is low and maybe also applicable in remote sensing and long-distance quantum imaging where the light passed through the object is weak after a long distance transmission. [ABSTRACT FROM AUTHOR]

The variation and stability of HBT's parameters at different temperatures are important for utilizing these devices in high-power integrated circuits. The temperature dependence of the DC current gain of bipolar transistors, as a key device parameter, has been extensively investigated. A major issue of the power HBT's is that the current gain is decreased with junction temperature due to self-heating effect.Hence, how to stabilize the DC current gain and RF performances is important issue to develop the power HBTs. This work describes the DC and high-frequency temperature dependence of InGaP/GaAs HBT's. The substrate temperature (T) was varied from 25 to 150°C. The static and dynamic performances of the HBT are degraded at high temperature, due to the reduced of carrier mobility with increasing temperature. The current gain (β) decreases at high temperatures; from 140 to 127 at 25 to 150°C, while the decreases in the peak Ft and Fmax are observed from about 110 GHz to 68 GHz and from 165 GHz to 53 GHz respectively in the temperature range of 25 to 150°C. [ABSTRACT FROM AUTHOR]

A novel ballast resistor network is proposed to achieve a better thermal management in HBT power cells without degrading the RF performances. Experiments were conducted on two HBT power amplifiers. They occupy same area. One is designed using conventional ballast network. The other uses proposed novel network. Temperature comparisons were made based on the same current density. Infrared camera images show that a more uniform temperature distribution is obtained in novel ballast network power amplifier. Our results demonstrate that the proposed novel ballast network has promising applications in high power amplifiers. (C) 2008 Wiley Periodicals, Inc.

Hydrazine (N 2 H 4), a chemical compound widely used in various industrial applications, causes significant environmental and biological hazards. Therefore, it is crucial to develop methodologies for the visualization and real time tracking of N 2 H 4. In this regard, we have constructed a novel near-infrared fluorescent probe (HBT-Cy) that can effectively detect N 2 H 4 in various samples. HBT-Cy contains 2-(2′-hydroxyphenyl)benzothiazole (HBT), cinnamoyl (Cy), and pyridinium (Py) moieties. Importantly, HBT-Cy exhibits a rapid, selective, and highly sensitive response to N 2 H 4. This response results in the release of HBT-Py and the generation of considerable colorimetric changes along with a significant NIR (near infrared) fluorescence signal, peaking at 685 nm. Advantages of this system include turn on NIR fluorescence with large Stokes shift, (approximately 171 nm), low limit of detection (LOD = 0.11 μM) and quantum yield (0.211). The probe with low cytotoxic behavior demonstrates strong NIR fluorescence imaging capabilities to visualize endogenous and exogenous N 2 H 4 in live cells. This mitochondria-targetable probe shows effective subcellular localization. These results suggest that HBT-Cy is a valuable probe for tracking and investigating the behavior of N 2 H 4 in biological systems and environmental samples. [Display omitted] • A novel NIR emissive probe (HBT-Cy) was synthesized for the detection of N 2 H 4 in vapor or solution. • The probe has low cytotoxicity, large Stokes shift with low detection limit (0.11 μM). • The probe was capable of on-site detection of N 2 H 4 in soil, water, and plant samples. • Smartphone and paper kit applications allow to determine N 2 H 4 on site. • The probe could be targeted to mitochondria in living cells to visualize N 2 H 4. [ABSTRACT FROM AUTHOR]

Within many years microelectronics developed based on p-n junctions made of germanium or silicon, namely on homojunctions (BJT). In this case the main technological difficulty was to control the level of doping concentrations. Semiconductor structures were obtained by the variation of type and concentration of the doping impurities. A new phase of the evolution of the semiconductor devices is the manufacturing and large scale using of heterojunctions. Heterojunction is the contact of two semiconductors, different according to the chemical composition, existing in a single crystal. Within this contact not only the energetic areas structure varies, but also the effective body of the carriers, their mobility and other parameters. The possibility of variation of these parameters allows the manufacture of unique devices that have record performance. Heterojunction bipolar transistors (HBT) have the following benefits: static gain in current, high cutting frequency, high speed of conversion, low temperature running. The aim of my study is transit time study through the base in case of drift transistors. [ABSTRACT FROM AUTHOR]

Abstract In this work, an ultrasensitive fluorescent turn-on probe (HBT-Phos) for rapid detection of the highly toxic phosgene is reported. This probe uses 2-(2′-hydroxyphenyl)benzothiazole (HBT), a well-known excited-state intramolecular proton transfer (ESIPT) dye as the fluorophore and an oxime moiety as the reaction site. Upon addition of various analytes, this probe specifically reacts with phosgene to release a highly fluorescent nitrile product (HBT-CN) via a dehydration process, which provides a new selective and ultrasensitive fluorescent turn-on detection method for phosgene (F / F 0 ∼1750-fold, detection limit ∼0.48 nM in solution). Furthermore, using the aggregation-induced emission (AIE) of the product in solid state, this probe was successfully applied to prepare a silica plate-based portable sensing system for detecting phosgene gas in air with a detection limit as low as ∼0.34 ppm. All the results indicate that this probe is of great value for on-site detection of phosgene. Graphical abstract Image 1 Highlights • A new fluorescent probe for selective detection of phosgene was reported. • This probe shows colorimetric and fluorescent turn-on changes for phosgene. • This probe exhibits ultrasensitivity for phosgene with a detection limit of 0.48 nM. • This probe can be embedded to silica gel plate for sensitive detection of phosgene gas in air. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A model chemodosimeter specific to Hydrazine was synthesized. • Re-assignment of Red shifted emission in deprotected HBT and protected HBT. • Ratiometry observed from HBT based chemodosimeters are reported to be due to ESIPT reappearance. • Spectroscopic analysis revealed anion of HBT is formed rather than returning of ESIPT. Abstract The -OH group protected 2-(hydroxyphenyl) benzothiazole (HBT) based ratiometric chemodosimeters have previously been reported to undergo regeneration of excited state intramolecular proton transfer (ESIPT) process upon deprotection. In the current work it is demonstrated for the first time that generation of anion of HBT leads to the optical changes in these types of chemodosimeters rather than regeneration of HBT by using a Hydrazine specific chemodosimeter based on substituted HBT. [ABSTRACT FROM AUTHOR]

The abnormality of Cys concentration in organism could lead to a series of diseases, so its effective detection is of great importance in disease diagnosis. Here we developed a novel ESIPT fluorescent probe HBT-IDAc based on the classic ESIPT fluorophore 2-(2′-hydroxyphenyl)benzothiazole (HBT) and indanone, which could selectively and sensitively detect Cys with a large Stokes shift up to 210 nm and the detection limit to 0.89 μM. In addition, the probe exhibited good anti-interference and low cytotoxicity, and has been successfully applied to monitor Cys in cells. • A novel ESIPT fluorescent probe for selective and sensitive detection of Cys was developed. • The probe has the large stokes shift (210 nm) and good LOD (0.89 μM) in aqueous environment. • The probe exhibits low cytotoxicity and has been applied for imaging Cys in cells. [ABSTRACT FROM AUTHOR]