Topographic and biomechanical evaluation of cornea in patients with ichthyosis vulgaris

PurposeTo compare the topographic and biomechanical properties of corneas in eyes of patients with ichthyosis vulgaris (IV) and eyes of healthy individuals.MethodsThirty healthy individuals (control group) and 30 patients with IV (study group) were enrolled in this prospective study. Topographic measurements, including keratometry values, irregularity, and surface asymmetry index in the right eye of each participant were obtained using Scheimpflug camera with a Placido disc topographer (Sirius). Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc) and Goldman-related intraocular pressure (IOPg) were measured using the Reichert Ocular Response Analyzer (ORA). Central corneal thickness (CCT) was also measured with ultrasonic pachymetry and the Sirius corneal topography system.ResultsTopographic parameters were not significantly different between both groups (p > 0.05). Although mean CH was not significantly different between the groups, the CRF was significantly lower in patients with IV (p = 0.249 and p = 0.005, respectively). The CCT was significantly lower in patients with IV compared to healthy controls (p < 0.001). The IOPg and IOPcc were significantly lower in the patients with ichthyosis than in healthy controls (p = 0.001 and p = 0.004, respectively).ConclusionsThe study demonstrated that while the eyes of patients with IV had corneal topographic findings and corneal hysteresis similar to those of healthy controls, some of corneal biomechanical properties such CRF and CCT and IOP values such as IOPg and IOPcc were significantly lower in patients with IV. These results should be taken into account when planning a corneal refractive surgery and glaucoma screening for patients with IV.     

Analog circuit sizing via swarm intelligence

Together with the increase in electronic circuit complexity, the design and optimization processes have to be automated with high accuracy. Predicting and improving the design quality in terms of performance, robustness and cost is the central concern of electronic design automation. Generally, optimization is a very difficult and time consuming task including many conflicting criteria and a wide range of design parameters. Particle swarm optimization (PSO) was introduced as an efficient method for exploring the search space and handling constrained optimization problems. In this work, PSO has been utilized for accommodating required functionalities and performance specifications considering optimal sizing of analog integrated circuits with high optimization ability in short computational time. PSO based design results are verified with SPICE simulations and compared to previous studies.     

Amine-terminated aromatic and semi-aromatic hyperbranched polyamides: synthesis and characterization

A facile synthetic approach to aromatic and semiaromatic amine-terminated hyperbranched polyamides via direct polymerization of triamine (B₃) with different diacid chlorides (A₂) was explored. An aromatic triamine, 1,3,5-tris(4′-aminophenylcarbamoyl)benzene (TAPCB), was synthesized and monomers were characterized by elemental analysis, FTIR, ¹H and ¹³C NMR spectroscopy. Finally, the polycondensation reaction of TAPCB with terephthaloyl chloride (TPC), isophthaloyl chloride (IPC), sebacoyl chloride (SC) and adipoyl chloride (AC) resulted in the preparation of four hyperbranched polyamides i.e., HBPA 1, 2, 3 and 4, respectively. FTIR and ¹H NMR analyses confirmed the structures of the ensuing polymers and DB was found between 0.51–0.55. These thermally stable amorphous HBPAs were soluble in polar aprotic solvents at room temperature having glass transition temperatures (T_g) between 138–198 °C. Inherent viscosities (η_inh) and weight average molecular weights (M_w) were in the range of 0.27–0.35 dL/g and 1.3 × 10⁴–2.7 × 10⁴, respectively. Future prospects are envisaged.     

Experimental investigation on transverse low-speed impact behavior of adhesively bonded similar and dissimilar clamped plates

This experimental study investigates the low-speed impact behavior of adhesively bonded similar (Al–Al, St–St) and dissimilar (Al–St, St–Al) plates. The after-impact geometries of the front and back faces of the bonded plates, which were visualized by measuring the displacements, were in good agreement with the simulated surface geometries obtained by using explicit finite element method. The plate stiffness was affective on the deflections of the bonded plates; thus, the bonded Al–Al plates exhibited maximum deflections, contact durations, and minimal contact force levels, whereas the bonded St–St plates had minimum deflections, contact durations, and maximum contact force levels. As the impact energy is increased, the impact forces, durations, and deflections increased naturally; however, the impact force-time histories were not affected evidently. The bonded Al–Al plates can dissipate the impact energy more effectively than the bonded St–St plates. The experimental and simulated contact force-time histories were generally in good agreement. Based on the cross-section photographs of the damaged impact regions the bonded Al–Al plates with low stiffness can deform plastically and dissipate most of the impact energy, and the adhesive layer remains compatible with the deformation of the plates. The interfacial fractures appear along the back plate–adhesive interface for the low impact energy but along both front and back plate–adhesive interfaces and cracks propagated to the back interface to lower interface through the adhesive thickness near the boundaries of the impactor trace. The bonded St–St plates behave more rigid, transmit the impact energy directly to the adhesive layer and the high impact force distributions result severe fractures not only interfacially but also through the adhesive thickness. The color transformations, which are indications of fracture formation and propagation speed in some way, were observed around the adhesive fractures. Although the bonded St–Al and Al–St plates had a fracture mechanism similar to those of the bonded Al–Al plates but the color transformation near the fractures and the crack opening displacement levels were more evident. The existence of a stiffer plate affects considerably the damage formation in the adhesive layer and in the plates, whereas the less stiff plates can dissipate the impact energy by deforming plastically and the adhesive layer experiences less local damages.     

Drift estimation using pairwise slope with minimum variance in wireless sensor networks

Time synchronization is mandatory for applications and services in wireless sensor networks which demand common notion of time. If synchronization to stable time sources such as Coordinated Universal Time (UTC) is required, employing the method of flooding in order to provide time synchronization becomes crucial. In flooding based time synchronization protocols, current time information of a reference node is periodically flooded into the network. Sensor nodes collect the time information of the reference node and perform least-squares regression in order to estimate the reference time. However, least-squares regression exhibits a poor performance since sensor nodes far away from the reference node collect the time information with large deviations. Due to this fact, the slopes of their least-squares line exhibit large errors and instabilities. As a consequence, the reference time estimates of these nodes also exhibit large errors.This paper proposes a new slope estimation strategy for linear regression to be used by flooding based time synchronization protocols. The proposed method, namely Pairwise Slope With Minimum Variance (PSMV), calculates the slope of the estimated regression line by considering the pairwise slope between the earliest and the most recently collected data points. The PSMV slope is less affected by the large errors on the received data, i.e. it is more stable, and it is more computationally efficient when compared to the slope of the least-squares line. We incorporated PSMV into two flooding based time synchronization protocols, namely Flooding Time Synchronization Protocol (FTSP) and PulseSync. Experimental results collected from a testbed setup including 20 sensor nodes show that PSMV strategy improves the performance of FTSP by a factor of 4 and preserves the performance of PulseSync in terms of synchronization error with 40% less CPU overhead for linear regression. Our simulations show that these results also hold for networks with larger diameters and densities.     

rGO/CuO/PEDOT nanocomposite formation,its characterisation and electrochemical performances for supercapacitors

ABSTRACT

Supercapacitor properties of rGO, CuO, PEDOT and rGO/CuO at [rGO]_o/[CuO]_o?=?1:1; 1:1.5; 1:2 and rGO/CuO/PEDOT nanocomposite at [rGO]_o/[CuO]_o/[EDOT]_o?=?1:1:1; 1:1:3; 1:1:5 were investigated using chemical reduction of GO and in-situ polymerisation process. SEM-EDX, HRTEM, BET surface area analysis confirm the nanocomposite formations. Nanocomposite materials are also analysed through FTIR-ATR, Raman, TGA-DTA, GCD, CV and EIS. The highest specific capacitance of C _sp?=?156.7 F/g at 2?mV/s is determined as rGO/CuO/PEDOT at [rGO]_o/[CuO]_o/[EDOT]_o?=?1:1:5. In addition, two-electrode supercapacitor device for rGO/CuO/PEDOT at [rGO]_o/[CuO]_o/[EDOT]_o?=?1:1:5 are found to provide a maximum specific energy (E?=?14.15 Wh/kg at 20?mA) and specific power (P?=?24730 W/kg at 50?mA), electrical serial resistance (ESR?=?13.33 Ω) with good capacity retention after 3000 cycles. An equivalent circuit model of LR1(CR2)(QR3) is proposed to interpret the EIS data. The supercapacitor performance of the rGO/CuO/PEDOT nanocomposite electrode indicates the synergistic effect of hybrid supercapacitors.     

Assessment of the Axial Load Response of an H Pile Driven in Multilayered Soil

Most of the current design methods for driven piles were developed for closed-ended pipe piles driven in either pure clay or clean sand. These methods are sometimes used for H piles as well, even though the axial load response of H piles is different from that of pipe piles. Furthermore, in reality, soil profiles often consist of multiple layers of soils that may contain sand, clay, silt or a mixture of these three particle sizes. Therefore, accurate prediction of the ultimate bearing capacity of H piles driven in a mixed soil is very challenging. In addition, although results of well documented load tests on pipe piles are available, the literature contains limited information on the design of H piles. Most of the current design methods for driven piles do not provide specific recommendations for H piles. In order to evaluate the static load response of an H pile, fully instrumented axial load tests were performed on an H pile (HP?310×110) driven into a multilayered soil profile consisting of soils composed of various amounts of clay, silt and sand. The base of the H pile was embedded in a very dense nonplastic silt layer overlying a clay layer. This paper presents the results of the laboratory tests performed to characterize the soil profile and of the pile load tests. It also compares the measured pile resistances with those predicted with soil property- and in situ test-based methods.     

Achieving compatibility in blends of low‐density polyethylene/polyamide‐6 with addition of ethylene vinyl acetate

Polymer alloys and blends, whose major advantage is the potential of achieving a range of physical and mechanical properties, have continued to be a subject of interest over recent years. Addition of a block or graft copolymer, with chemically similar segments to those involved in the polymer blend considered, led to a variety of desirable properties. The copolymer added to the blend functioned to promote a homogeneous dispersion of the constituent phases and to enhance their mutual adhesion. Such agents that enable better dispersion in polymer blends are known as compatibilizers. In this study an attempt has been made to improve the compatibility in a polymer blend composed of two normally incompatible constituents, LDPE and PA₆, by addition of a compatibilizer. The compatibilizer agent, ethylene vinyl acetate (EVA), was added to the polymer blend in ratios of 1, 5, and 10% by using a twin‐screw extruder. The effect of EVA on the crystallization of the polymer constituents was observed through DSC examinations. Furthermore, the control sample and all three blends of LDPE/PA₆/EVA were subjected to examinations to obtain their yield and tensile strengths, elasticity modulus, percentage elongation, izod impact strength, hardness, and melt flow index. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1748–1754, 2001     

Performance of cryogenically treated M35 HSS drills in drilling of austenitic stainless steels

In this study, performance of cryogenically treated M35 high speed steel (HSS) twist drills in drilling of AISI 304 and 316 stainless steels was evaluated in terms of thrust force, surface roughness, tool wear, tool life, and chip formation. To present the differences in tool performance between untreated and treated drills, and machinability between AISI 304 SS and AISI 316 SS, a number of experiments were performed at different combinations of cutting speed, and feed rate. As the results of the conducted experiments, the treated drills showed better performance than untreated drills in terms of thrust force, surface roughness, and tool wear and tool life for both types of stainless steels. Tool lives of treated HSS drills in drilling of AISI 304 SS and AISI 316 SS improved 32% and 14%, respectively, when compared with untreated drills. Experimental results also showed that machinability of AISI 304 SS was harder than the machinability of AISI 316 SS.     

Coal consumption and industrial production nexus in USA: Cointegration with two unknown structural breaks and causality approaches

The paper investigates the causality relationships among industrial production index, coal consumption and employment in industrial sector for the period of 1973:1–2011:10 in USA. After noticing that there are breaks in the regression model, the Hatemi-J test for cointegration is employed to the cases that take into account two possible regime shifts. It is concluded that there is a long run relationship between industrial production and industrial coal consumption with the breaks at 1983:4 and 1998:4. We found a negative relationship between coal consumption and industrial production for the period of 1973:1–1983:4 and positive relationship for 1983:5–1998:4 period. For the last period that covers 1983:5–2011:10, the cointegration relationship turned to negative. In addition, the results show that causal relationship between coal consumption and industrial production changes over time.