A preliminary study on the feasibility of friction stir back extrusion

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Redox thermodynamics, conductivity and Raman spectroscopy of electropolymerized furan-thiophene copolymers

Electrochemical copolymerization of furan and thiophene was performed at constant electrode potential in a binary solvent system consisting of boron trifluoride-ethyl ether and an additional amount of ethyl ether (mole ratio 1:2). The homopolymers and copolymers obtained were studied with in situ resonance Raman spectroscopy and in situ conductivity measurements. In situ resonance Raman spectroscopy of the copolymers shows spectroscopic properties intermediate between polyfuran and polythiophene. The conductivity of homo- and copolymer films is almost restored when the potential shift direction is reversed.The redox thermodynamics of homo- and copolymer films were also determined using the Nernst plots constructed from absorbance measurements performed in situ at various doping levels.     

Phthalimide based polymers of intrinsic microporosity

A series of phthalimide based microporous polymers were successfully prepared by conventional nucleophilic substitution reaction of several newly synthesized fluoro-monomers with commercially available 5,5′,6,6′-tetrahydroxy-3,3,3′,3′-tetramethylspirobisindane. FTIR, ¹H NMR, and elemental analyses were used to identify the proposed structures of the polymers. The synthesized polymers are of high molecular weight as demonstrated by Gel Permeation Chromatography (GPC). Thermogravimetric analysis shows that the prepared polymers were stable up to 300 °C. From the porosity analysis it is clear that the prepared polymers are analogous to polymers of intrinsic microporosity (PIMs) with high surface area (500–900 m²/g). The t-plot analysis shown that the major contribution to the specific surface area is arising from the micropore surface area with narrow size distribution of ultramicropores as confirmed by the Horvath-Kawazoe (H-K) analysis. The hydrogen storage capacity of the prepared PIM-R(1–7) and CO-PIM(3,4,6,7) were promising (up to 1.26 wt%, 77 K, at 1.13 bar) with high isoteric heats of H₂ adsorption (8.5 kJ/mol).The results of this study demonstrate that controlling the appropriate monomer content via the three-dimensional structure can provide a uniform microporous morphology in the target polymers.     

Clinical Phenotype of PDE6B-Associated Retinitis Pigmentosa

In this retrospective, longitudinal, observational cohort study, we investigated the phenotypic and genotypic features of retinitis pigmentosa associated with variants in the PDE6B gene. Patients underwent clinical examination and genetic testing at a single tertiary referral center, including best-corrected visual acuity (BCVA), kinetic visual field (VF), full-field electroretinography, full-field stimulus threshold, spectral domain optical coherence tomography, and fundus autofluorescence imaging. The genetic testing comprised candidate gene sequencing, inherited retinal disease gene panel sequencing, whole-genome sequencing, and testing for familial variants by Sanger sequencing. Twenty-four patients with mutations in PDE6B from 21 families were included in the study (mean age at the first visit: 32.1 ± 13.5 years). The majority of variants were putative splicing defects (8/23) and missense (7/23) mutations. Seventy-nine percent (38/48) of eyes had no visual acuity impairment at the first visit. Visual acuity impairment was mild in 4% (2/48), moderate in 13% (6/48), and severe in 4% (2/48). BCVA was symmetrical in the right and left eyes. The kinetic VF measurements were highly symmetrical in the right and left eyes, as was the horizontal ellipsoid zone (EZ) width. Regarding the genetic findings, 43% of the PDE6B variants found in our patients were novel. Thus, this study contributed substantially to the PDE6B mutation spectrum. The visual acuity impairment was mild in 83% of eyes, providing a window of opportunity for investigational new drugs. The EZ width was reduced in all patients and was highly symmetric between the eyes, making it a promising outcome measure. We expect these findings to have implications on the design of future PDE6B-related retinitis pigmentosa (RP) clinical trials.     

Creation of Liquid-Air Dispersions in Oil and Water: Comparison of Calculations and Measurements

The creation of liquid-gas dispersions places very high demands on the process technology, which requires knowledge of bubble formation mechanisms. To extend the range of validity of the current calculation models to larger viscosity differences, the bubble formation mechanisms for the media combination oil/air are investigated. Compared to the media combination water/air, significant differences occur. The results obtained here will make it possible to design bubble columns in a more targeted manner in the future, which will lead to savings in resources and energy of industrial test stands.     

Decision Based Model for Real-Time IoT Analysis Using Big Data and Machine Learning

Use of internet of things (IoT) in different fields including smart cities, health care, manufacturing, and surveillance is growing rapidly, which results in massive amount of data generated by IoT devices. Real-time processing of large-scale data streams is one of the main challenges of IoT systems. Analyzing IoT data can help in providing better services, predicting trends and timely decision making for industries. The systematic structure of IoT data follows the pattern of big data. In this paper, a novel approach is proposed in which big data tools are used to perform real-time stream processing and analysis on IoT data. We have also applied Spark’s built-in support of the machine learning library in order to make real-time predictions. The efficiency of the proposed system is evaluated by conducting experiments and reporting results on the case scenario of IoT based weather station.

     

Low-noise sub-harmonic injection locked multiloop ring oscillator

A three-stage differential voltage-controlled ring oscillator is presented for wide-tuning and low-phase noise requirement of clock and data recovery circuit in ultra wideband (UWB) wireless body area network. To improve the performance of phase noise of delay cell with coarse and fine frequency tuning, injection locked technology together with pseudo differential architecture are adopted. In addition, a multiloop is employed for frequency boosting. Two RVCOs, the standard RVCO without the IL block and the proposed IL RVCO, were fabricated in SMIC 0.18 μm 1P6M Salicide CMOS process. The proposed IL RVCO exhibits a measured phase noise of -112.37 dBc/Hz at 1 MHz offset from the center frequency of 1 GHz, while dissipating a current of 8 mA excluding the buffer from a 1.8-V supply voltage. It shows a 16.07 dB phase noise improvement at 1 MHz offset compared to the standard topology.     

Symmetrically coated pellicle beam splitters for dual quarter-wave retardation in reflection and transmission

A trilayer pellicle that consists of a high-index center layer that is symmetrically coated on both sides by a low-index film can be designed to produce differential reflection and transmission phase shifts of +/- 90 degrees at oblique incidence and equal throughput for the p and the s polarizations. Such a device splits a beam of incident linearly polarized light into two orthogonal circularly polarized components that travel in well-separated angular directions. Examples of infrared dual quarter-wave retarders that use a symmetrically coated Ge pellicle at 77 degrees angle of incidence are presented. A 50-50% splitter requires a symmetric pellicle with at least five layers. Error analysis shows that the thicknesses of the high-index layers must be tightly controlled. These circular polarization beam splitters are intended for operation with a well-collimated light source and can be used as the basis of a novel circular polarization Michelson interferometer.     

Self-mode-locking effects in heavily doped single-clad Tm3+-doped silica fibre lasers

Self-mode-locking in single-clad Tm-doped silica fibre lasers operating at 1.92?µm is reported with 100% modulated mode-locked pulses observed for longer fibre lengths up to 6?m. The self-mode-locking was accompanied by self Q-switching. A mode-locked pulse duration of 191?ps has been measured using an autocorrelator based on a two-photon absorption detector for operation at 2?µm assembled for the purpose of this experiment. The experimental pulse train characteristics are found to be consistent with mode-locking theoretical analysis. The origin and properties of self-mode-locking in heavily Tm-doped fibre lasers are discussed.