PROSE treatment of corneal ectasia

PurposeProsthetic replacement of the ocular surface ecosystem (PROSE) uses custom designed and fabricated prosthetic devices in a treatment that restores vision, supports healing, reduces symptoms and improves quality of life in patients with complex corneal disease. We report the success rate for PROSE treatment of corneal ectasia.MethodsRecords of 59 patients with corneal ectasia seen in consultation over 6 months were reviewed. Candidacy for treatment, topographic indices, change in visual acuity, achievement of satisfactory fit, device wear status and change in visual function at 6 months were recorded.ResultsSixteen eyes were non-candidates because conventional correction was adequate. Trial devices were inserted but not dispensed for 13 eyes. No eyes were excluded for severity of ectasia. In the remaining 89 eyes, satisfactory fit was achieved and a device was dispensed. Twenty-one eyes (15 patients) had undergone penetrating keratoplasty. Device wear at 6 months was documented in 78/89 eyes (88%). NEI VFQ-25 score improved 27.6 points (p < 0.001) on a 100 point scale in patients wearing a device at 6 months.ConclusionAll candidate eyes with corneal ectasia could be fitted with a PROSE device. PROSE treatment has a high success rate when measured by ability to achieve satisfactory fit, impact on visual acuity and 6 month data on both rate of continued wear and impact on visual function. PROSE treatment is an alternative to penetrating keratoplasty for patients with corneal ectasia who are contact lens intolerant.     

Novel polyfuran/functionalized multiwalled carbon nanotubes composites with improved conductivity: Chemical synthesis,characterization, and antioxidant activity

Novel composites containing very small quantities of functionalized multiwalled carbon nanotubes (MWCNTs‐COOH; 0.025, 0.050, and 0.075 g), and furan were synthesized via in situ chemical oxidative polymerization. The polymerization was carried out in nitromethane at room temperature using anhydrous iron (III) chloride (FeCl₃) as an oxidant. The nanocomposites were characterized by Fourier transform infrared, ultraviolet–visible, X‐ray diffraction, differential scanning calorimetry, and field emission scanning electron microscopy. All synthesized composites were crystalline and showed good solubility in dimethyl sulfoxide and N‐methyl 2‐pyrrolidone. The conductivity of composites was measured with a four‐probe method, and it was found that the electrical conductivity increased by increasing the amount of MWCNTs‐COOH. The maximum electrical conductivity value (6.68 × 10⁻⁴ S cm⁻¹) was obtained for polyfuran/MWCNTs‐COOH (1:0.075, v/w). The resulting composites were analyzed for their antioxidant activity using 2,2‐diphenyl‐1‐picrylhydrazyl assay. The results showed that the antioxidant activity of the composites increased by increasing the amount of MWCNTs‐COOH in nanocomposite. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Designing Lubricant‐Impregnated Textured Surfaces to Resist Scale Formation

Scale formation is a widespread problem in industries and households—from scaling of cooking pots in ancient times to the plugging of pipelines in the modern age. Developing surfaces that have a low affinity to scale has been an area of great interest in the last decade. In this work, we demonstrate the anti‐scaling properties of textured surfaces impregnated with a lubricant. Since scale deposition can be reduced by lowering the nucleation rate, which depends on the properties of the substrate, we optimize the design of the lubricant‐impregnated surfaces (LIS) based on the surface tension of the lubricant and its spreading coefficient on the solid. Scale deposition experiments show that the nucleation rate on optimized LIS is reduced owing to their low surface energy and low density of nucleation sites. Mass gain measurements indicate that the optimized LIS perform 10 times better than uncoated smooth surfaces. This idea is extended to an engineering material like stainless steel and, along with low scale deposition, low adhesion of scale to LIS is also achieved.     

Solvothermal synthesis of vanadium phosphate catalysts for n-butane oxidation

In this paper, we have developed a simple, low-cost, template-free and surfactant-free solvothermal process for synthesis of vanadyl hydrogen phosphate hemihydrate (VOHPO₄·0.5H₂O) with well defined crystal size. The synthesis was performed by reaction of VPO₄·2H₂O with an aliphatic alcohol (isobutyl alcohol, 1-pentanol, 1-hexanol, 1-heptanol or 1-decanol). This afforded well crystallized VOHPO₄·0.5H₂O by solvothermal methods at 120 °C temperature. This new method significantly reduced the preparation time and lowered production temperature (50%) of catalyst precursor (VOHPO₄·0.5H₂O) when compared to conventional hydrothermal synthesis methods. By varying the reducing agent, the solvothermal evolution process from layered tetragonal phase VOPO₄·2H₂O to orthorhombic phase VOHPO₄·0.5H₂O was observed. It was found that the length of carbon chain in an alcohol in the solvothermal condition had a great impact on chemical and physical properties of resulting catalysts. Interestingly, there was no trace of VO(H₂PO₄)₂ an impurity noted to be readily formed under solvothermal preparation condition. Therefore, this study introduces a more facile synthetic pathway to V(III) compounds. In addition, the microwave-synthesized catalysts exhibited some properties superior to those of conventionally synthesized catalyst such as better stability, crystallinity, and catalytic activity in the production of maleic anhydride. The characterization of both precursors and calcined catalysts was carried out using X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES), N₂ physisorption, temperature programmed reduction (H₂-TPR) and scanning electron microscopy (SEM). The XRD pattern of the active catalyst prepared by this solvothermal method confirmed the presence of smaller crystal size (between 6 and 13 nm along 0 2 0 planes) of vanadium phosphate catalyst with higher specific surface area. Finally, the yield of maleic anhydride was significantly increased from 29% for conventional catalyst to 44% for the new solvothermal catalyst.     

Half-symmetric cavity tunable microelectromechanical VCSEL withsingle spatial mode

A new class of microelectromechanically tunable vertical-cavity surface-emitting lasers with a half-symmetric cavity structure is described. The cavity is realized by inducing a curvature (R~320 μm) in the top movable dielectric mirror. The microcavity forces lasing oscillations in a single fundamental spatial mode of approximately 6 μm despite the 20 μm electrical aperture of the device. The device wavelength was tunable from 863 to 833 nm under a 13-V voltage swing. The device operates in a single fundamental mode with sidemode supression ratio of >20 dB throughout the tuning range     

Coating of Sol–Gel Film on Silver Nanodendrite as a Novel Solid-Phase Microextraction Fiber for Determination of Volatile Aldehydes in Edible Oils

In this work, a novel solid-phase microextraction fiber was fabricated by a new substrate applied for quantitative analysis of trace volatile aldehydes emitted during thermal oxidation of edible oils, analyzed by GC–MS. Ag nanodendrites as a porous substrate, spontaneously coated on a Cu wire, and polydimethylsiloxane/polyethylene glycol (PDMS/PEG) were deposited onto the substrate by sol–gel dip-coating. Parameters affecting the extraction efficiency, such as the substrate porosity, extraction time and temperature, and desorption time and temperature were investigated and optimized. The desorption temperature was chosen as 260 °C, and desorption time was set at 3 min. Results shows that extraction efficiency of sol–gel coating deposited on Ag nanodendrite substrate is meaningfully higher than that of deposited on bare Cu wire. Under the optimum conditions, the limits of detection (LODs) ranged between 0.5 to 0.2 μg/L. The relative standard deviations including repeatability (within fibers) and reproducibility (between fibers) varied between 7.5–11.2 and 9.3–16.2%, respectively.     

Application of resins and crosslinking agents on fiber blend fabric to reduce pilling performance,optimized by response surface methodology

Resins and crosslinking agents have been used on textiles for a long time for various purposes. Fiber blend fabrics have a propensity to pill, thereby giving garments a spoiled surface appearance. The pilling should be reduced or prevented by application of an appropriate finishing method. Surface modification by using different chemicals is the most useful method. Here, various resins and crosslinking agents were used to reduce the pilling of viscose/polyester (35/65) fabric. A viscose/polyester knitted fabric was treated with different blends of aminoplast resins and crosslinking agents in order to obtain a fabric with permanent anti‐pilling performance. The concentrations of the resins were determined with a central composite design, and then different characteristics of the fabrics such as pilling rate, water absorption, air permeability, water vapor transmission, bending, tensile strength, whiteness, and washing durability were examined. The results showed that application of aminoplast resins along with a crosslinking agent helped to reduce pilling. Also, the amounts of different variables were optimized with response surface methodology, and their statistical models were obtained. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

Kinematic and dynamic modeling of viscoelastic robotic manipulators using Timoshenko beam theory: theory and experiment

This paper presents an investigation into the development of modeling of n-viscoelastic robotic manipulators. The dynamic model of the system is derived using Gibbs-Appell formulation and assumed mode method. When the beam is short in length direction, shear deformation is a factor that may have significant effects on system dynamic. So, in modeling, the assumption of Timoshenko beam theory and associated mode shapes has been considered. Although including the effect of damping in continuous systems makes the formulations more complicated, two important damping mechanisms, namely, Kelvin-Voigt damping as internal damping and the viscous air damping as external damping have been considered. Based on derived formulation, a non-linear recursive algorithm is developed for deriving the inverse dynamic equation of motion, systematically. The performance of the proposed algorithm was assessed in terms of the required mathematical operations for deriving the kinematic and dynamic equations of the mechanical system. Finally, to validate the proposed formulation, a comparative assessment between the results achieved from experiment and simulation is presented in time and frequency domains.