Triple cascaded current-reuse low noise amplifier

A triple cascaded current-reuse CMOS low noise amplifier for 3.5 GHz WiMAX application is presented. Three common-source amplifiers are stacked and reuse the same current. This triple cascaded topology is able to enhance power gain but needs two coupling networks which costs enormous chip size. In order to have reasonable chip size, two coupling methods are investigated. For obtaining simultaneous input and noise matching, an additional capacitor is employed to adjust quality factor and reduce the gate induced current noise. The measurement results show a maximum power gain of 21.7 dB and minimum noise figure of 3.11 dB. The chip size is 1.05 mm \(\times\) 0.93 mm including all pads and the power consumption is 5.16 mW with a supply voltage of 1.5 V. A figure-of-merit of 49.7 is reached.     

Mechanical Strength and Surface Roughness of Magnesium-Based Metallic Glasses

This work evaluated the mechanical strength and surface roughness of MgZn₃₀Ca₅ ribbon manufactured via a melt spinning technique for applications in the biomedical field. Annealing was performed at 280°C. The inner side (in contact with the wheel) and the outer side (not in contact with the wheel) of the ribbons were mechanically evaluated using nanoindentation, and its surfaces were analyzed by an optical profilometer. Differential scanning calorimeter (DSC) and X-ray diffraction (XRD) analyses were also performed to identify the structure and devitrification of the magnesium metallic glass (MgMG). The nanohardness and elastic modulus increased after annealing (p < 0.0001). No differences were seen in the strength between the two sides of the ribbons (p > 0.05). Although both sides of the ribbons showed different surface profiles (p < 0.0001), no statistical difference was detected in roughness parameters on either ribbon side before (p = 0.3094) and after (p = 0.8742) annealing. DSC curves showed disturbances in enthalpy attributed to a relaxation in the MgMG structure and free volume annihilation. The DRX diffractogram showed sharp peaks after annealing, with MgZn and Ca₂Mg₅Zn₁₃ phases being identified. Although the use of MgMG in biomedical applications is promising, the ribbons displayed limited ductility, toughness, and a relevant embrittlement after the annealing procedure. There were significant changes in the surface profile of both sides of the ribbons. Nevertheless, neither annealing nor the ribbon side had influenced surface roughness parameters.     

A differential mobility analyzer and a Faraday cup electrometer for operation at 200–930 Pa pressure

We have developed a differential mobility analyzer (DMA) based on the DMA devised by Seto et al. (1997) and a Faraday cup electrometer for measurement of nanometer-sized particles at a few hundred Pa and examined the operating characteristics of the DMA using the tandem DMA technique. The tandem DMA calibration establishes that the DMA successfully classifies particles in the 200–930 Pa pressure range. It was also found that the transfer function of the DMA follows the triangular transfer function and the resolution of the DMA is close to that given for an ideal case. As a standard of a minimum pressure that may be probed with the present DMA system, 400 Pa is estimated when the DMA operates with a 3 nlmin⁻¹ sheath flow and a 1 nlmin⁻¹ aerosol flow rate.     

Poly(3,4-ethylenedioxythiophene)/Au-nanoparticles composite as electrode coating suitable for electrocatalytic oxidation

Composite materials consisting of poly(3,4-ethylenedioxythiophene) including Au nanoparticles, encapsulated by citrate anions, have been firmly deposited on an electrode surface through a simple method, taking advantage of the interaction between Au metal and thiophene polymeric backbone. A series of similar electrode coatings, also including different amounts of nanoparticles inside, has been characterised in terms of thickness and surface morphology, through different microscopic techniques. The electrocatalytic properties have been studied with respect to the oxidation of glucose in alkaline media, which is prevented from occurring on the pure organic material.     

Multi‐jet nozzle electrospinning on textile substrates: observations on process and nanofibre mat deposition

Electrospinning is a simple and versatile process for producing small‐diameter fibres (nanofibres). However, in spite of the many potential applications of electrospun nanofibres, further process developments are still necessary to achieve a decisive productivity breakthrough for electrospinning plants. Increasing knowledge of multi‐jet electrospinning is crucial for developing industrial devices for large‐scale nanofibre production. This paper reports on the effect of a non‐conducting textile substrate placed between a jet‐emitting source (nine‐nozzle arrangement) and collector. Shielding the electric field changes the electrospinning conditions, nanofibre morphology, stability of jets and fibre deposition on the collecting surface. Various perturbation phenomena of the electrically driven jets were recorded and are described. The intensity of the perturbations increases as the weight of the non‐woven substrate increases resulting in defects in the nanofibrous mat (i.e. beaded nanofibres), production of tick fibres or failure to produce fibrous materials (e.g. films, droplets). The paper also reports an objective image‐processing procedure to enhance the evaluation of the collector after nanofibre deposition. Copyright © 2010 Society of Chemical Industry     

Role and Perspectives of Inflammation and C-Reactive Protein (CRP) in Psychosis: An Economic and Widespread Tool for Assessing the Disease

Schizophrenia is a major psychotic disorder affecting nearly 23.6 million people globally and greatly impacting the cognitive and social functioning of individuals. Multiple risk factors, including genetic, environmental, and epigenetic factors have been identified. However, the exact mechanism by which some factors aid in the development of schizophrenia is still uncertain. Acute and/or long-standing inflammation has been implicated as both a cause and effect of schizophrenia. Heightened immune responses have been documented in large cohorts of individuals with schizophrenia. While not completely known, multiple hypotheses, such as disruption of the blood–brain barrier, alterations in the kynurenine/tryptophan pathway, and increased microglial activation, have been presented to correlate inflammation with schizophrenic symptoms. Measurement of C-reactive protein (CRP) is a commonly performed and inexpensive test on patients’ serum to determine levels of systemic inflammation in the body. Multiple studies have reported an elevated CRP level in different stages of schizophrenia, indicating its potential to be used as a viable biomarker in the diagnosis and monitoring of schizophrenia along with assessing treatment response to conventional and non-conventional treatment regimens. This review aims to evaluate the role of inflammation, in general, and CRP, in particular, in the pathogenesis of schizophrenia and its potential significance in diagnostic, therapeutic, and preventative approaches towards schizophrenia and psychosis.     

Kinetic Properties and Enantioselectivity of The Lipases Produced by Four Aspergillus Species

Four high lipase-producing Aspergillus species, selected in our laboratory, were compared in terms of their stability and reactivity for enantioselective esterification between (R, S)-2-octanol with octanoic acid in n-hexane. We determined the pH and temperature reactions dependences of lipases activities, and we found that these enzymes exhibited various pH sensitivities. The optimum pH observed for Aspergillus terreus lipase was 5.5, for A. niger and A. oryzae lipases in the range of 6.0 to 6.5 and pH 7.0 for A. flavus lipase. Good stability was observed at pH ranging from 5.0 to 8.5 after 24 hours at 40° C, and the optimum activity was observed at 35–40° C for all lipases tested. The lipases from A. terreus and A. niger were highly thermostable, retaining 60% and 50% activity at 60° C after 1 hour, respectively. The lipases from A. niger and A. terreus lipases provided the best results in terms of enantioselectivity (E) in the esterification of (R, S)-2-octanol with octanoic acid in n-hexane (E = 4.9 and E = 4.5, respectively). These properties make these lipases good candidates for biocatalysis in organic media.     

Co-precipitation synthesis of SOFC electrode materials

A series of four compounds (LaMnO₃, La_0.70Sr_0.30MnO_3−δ, La_0.80Sr_0.20FeO_3−δ and La_0.75Sr_0.25Cr_0.50Mn_0.50O_3−δ) of interest as electrode materials in intermediate temperature solid oxide fuel cells have been prepared using a carbonate co-precipitation route in aqueous medium. LaMnO₃, La_0.70Sr_0.30MnO_3−δ, and La_0.75Sr_0.25Cr_0.50Mn_0.50O_3−δ have been obtained as a pure phase, while La_0.80Sr_0.20FeO_3−δ retained an impurity phase; fine microstructures with sub-micron sized particles can be obtained in all cases at the proper calcinations temperature, except for LaMnO₃. The precipitation yield of the single metal ions have been experimentally determined in the mother liquors and in the final powders; the results have been evaluated also in comparison with expected yields calculated from thermodynamics of the precipitation process using the software Medusa. pH higher than 7.5 are suggested to avoid ion losses for all cations. Structural and microstructural properties and TPO/TPR behaviour suggest that materials prepared via co-precipitation, especially LSCM, could be suited as electrode materials in solid oxide fuel cells.     

Fatty Acid Composition of Tropical Fish Depends on Reservoir Trophic Status and Fish Feeding Habit

Eutrophication results in a deficiency of n‐3 LC‐PUFA (long‐chain polyunsaturated fatty acids) in aquatic food chains, affecting fish nutrition and physiology. The trophic transfer of FA (fatty acids) to fish species of different feeding habits was investigated in two reservoirs in southeast Brazil—the mesotrophic Ponte Nova Reservoir (PN) and the hypereutrophic Billings Reservoir (Bil). Total FA profile of stomach contents and adipose tissue, triacylglycerols (TAG), and phospholipids (PL) from liver and muscle of the omnivorous Astyanax fasciatus and the carnivorous Hoplias malabaricus were analyzed by gas chromatography. A prevalence of n‐6PUFA, as 18:2n‐6 (linoleic acid) and 20:4n‐6 (arachidonic acid, ARA) was observed in the stomach contents and in the tissues of A. fasciatus from the PN reservoir. In contrast, n‐3 LC‐PUFA, as 20:5n‐3 (eicosapentaenoic acid, EPA) was accumulated in fish tissues from Bil, resulting in higher n3/n6 and EPA/ARA ratios, compared to fish from PN. This differential FA accumulation was also observed for H. malabaricus, but differences were slightly minor, and no changes were observed in the EPA/ARA ratios between fish from both reservoirs. Regardless reservoir, FA profiles of TAG resembled that of their diet, whereas FA profiles of PL were more conservative and mainly comprised by LC‐PUFA. We conclude that reservoir trophic status affected the FA composition of food resources available to these fish species, resulting in differential allocation of n‐3 and n‐6 FA. As expected, FA profile of the investigated fish species also reflected their feeding habit and physiological demands.