Oxidation State of Titanium in CaO‐SiO2‐TiOx Slags at 1873K

Oxidation state of titanium was determined in CaO‐SiO₂‐TiO_x slags in the composition range 25‐53 percent CaO, 27‐46 percent SiO₂, 10‐55 percent TiO_x at 1873K using gas equilibration method. In the experiments, slags with different titanium oxide contents were equilibrated with a known carbon monoxide and carbon dioxide ratio. The results were used to determine the Ti³⁺ and Ti⁴⁺ contents as well as the activity coefficient ratio of corresponding oxides in the slag. The dependence of the activity coefficient ratio as a function of oxygen partial pressure was determined.     

Novel nonpeptide CCK-B antagonists: design and development of quinazolinone derivatives as potent, selective, and orally active CCK-B antagonists

We have designed a novel series of CCK-B receptor antagonists by combining key pharmacophores, an arylurea moiety of 1 and a quinazolinone ring of 3, from two known series. Our earlier studies showed that compounds with methylene linkers in our "target" produced moderate binding affinity and selectivity for CCK-B receptors, whereas its higher and lower homologues resulted in loss of affinity. Introduction of -NH- as a linker dramatically enhanced binding affinity and selectivity for CCK-B receptors, thus providing several compounds with single-digit nanomolar binding affinity and excellent selectivity. Analogous to the earlier studies of the series of quinazolinone derivatives 3, we also found 3-isopropoxyphenyl as a preferred substitution on the N-3 quinazolinone. Electron-withdrawing substitutions on the urea terminal phenyl ring enhanced the CCK-B potency. Representative compounds of this series were tested in the functional assay and showed pure antagonist profiles. Compounds 51 and 61 were orally active in the elevated rat X-maze test. These compounds were also evaluated for their pharmacokinetic profile. The absolute oral bioavailability of compound 61 was 22% in rats.     

Analysis of stepwise charging limits and its implementation for efficiency improvement in switched capacitor DC–DC converters

In this work we analysed the stepwise charging technique to find the limits from which it is beneficial in terms of load capacitance and charge–discharge frequency. We included in the analysis practical limitations such as the consumption of auxiliary logic needed to implement the technique and the minimum size of auxiliary switches imposed by the technology. We proposed an ultra-low-power logic block to push these limits and to obtain benefits from this technique in small capacitances. Finally, we proposed to use a stepwise driver in the driving of the gate capacitance of power switches in switched-capacitor (SC) DC–DC converters. We designed and manufactured, in a 130 nm process, a SC DC–DC converter and measured a 29% energy reduction in the gate-drive losses of the converter. This accounts for an improvement of 4% (from 69 to 73%) in the overall converter efficiency.

     

Design of a digital FM demodulator based on a 2nd-order all-digital phase-locked loop

Software-defined radio (SDR) is a revolution in radio design due to the ability to create radios that can self-adapt on the fly. In SDR devices, all of the signal processing is implemented in the digital domain, mainly on DSP blocks or by DSP software. By simply downloading a new program, a SDR device is able to interoperate with different wireless protocols, incorporate new services, and upgrade to new standards. Therefore, massively parallel signal processing at higher frequencies are needed to implement a realistic SDR. Thus, FPGAs have been used extensively for implementing essential functions in SDR architectures at lower frequencies. In this paper, we explore the design of a digital FM receiver using the approach of an All-Digital Phase Locked-Loop (ADPLL). The circuit is designed in VHDL, then synthesized and simulated using LeonardoSpectrum Level 3 and ModelSim SE 6, respectively. It operates at a frequency up to 150 MHz and occupies the area of roughly 15 K logic gates.     

Design of a Web Based Underwater Acoustic Communication Testbed and Simulation Platform

Wireless Personal Communications - Underwater Wireless Sensor Networks (UWSNs) are playing a vital role in exploring the unseen underwater (UW) natural resources. However, performance evaluation of...     

Polycrystalline fluorine-doped tin oxide as sensoring thin film in EGFET pH sensor

The Extended Gate Field Effect Transistor (EGFET) is a device composed of a conventional ion-sensitive electrode and a MOSFET device, which can be applied for the measurement of ion content in a solution. The EGFET is fabricated connecting the sensitive membrane to a commercial MOSFET. We investigated the use of fluorine-doped tin oxide films (FTO) as sensitive membrane to EGFET. The commercial FTO shows a low resistivity and a crystalline structure, both determined using conductivity set-up and X-ray diffraction experiments, respectively. So far, it has been known that an amorphous structure is desirable to obtain high sensitivity. Despite of the a crystalline structure, we have fabricated the FTO as EGFET for pH sensor and carried out experiments in order to obtain the response of the device inserted into solutions with pH values from 2 up to 12. In this range, we have quantified a sensitivity of 50 mV/pH, which may have large potential applications as pH and biosensors. In addition, both the film and the structure of the sensor are cheaper and easier to make than in common techniques.     

Special Issue: Technological Advancements in Wireless and Optical Communication Systems

Wireless Personal Communications -     

Acoustic Properties of Amorphous Solids at Very Low Temperatures: The Quest for Interacting Tunneling States

We discuss the strain dependence of the acoustic properties of amorphous metals in both normal and superconducting states, in the temperature range 0.1 mK<T<1 K. A crossover is found when the strain energy is of the order of the effective interaction energy between tunneling systems at the corresponding temperature. Our results provide clear evidence for the interaction between tunneling systems, whose energy is in quantitative agreement with theoretical expectations, and reveal that without the knowledge of the corresponding strain dependences, the measured temperature dependences below ～50 mK of the acoustic properties of disordered solids are rather meaningless.