Development of masked silica tanning system for sustainable leather production.

Amid mounting pressure on the long-term recyclability of chromium in tanned leather and the associated environmental hazards, the quest for an alternative, cleaner tanning system has gained tremendous momentum. In this context, our study explores the remarkable potential of silicates as a versatile platform for skin/hide tanning, circumventing the inherent risks and ecological threats posed by chromium exposure and leaching. We present an alternative approach of using a silica-based tanning system, employing a Taguchi model, to optimize a masked silica (MaSil) tanning product/process for achieving effective collagen stabilization. Our results demonstrate the significant advancements made in hydrothermal denaturation temperature, reaching an impressive 79 °C through precise Taguchi parameters-5% SiO2, masked with 0.3 mole of citrate salt, and a tanning process fixation pH of 4.5. Notably, the mechanical strength analysis reveals compliance with the stringent upper leather recommendation standards, validating the practicality and quality of MaSil crust leather. Moreover, our research highlights the unprecedented environmental benefits of the first reported application of Taguchi's approach to the MaSil tanning system. The developed tanning system remarkably reduces total dissolved solids (TDS), biological oxygen demand (BOD), chemical oxygen demand (COD), and overall water load by 68.4%, 25.4%, 59.5%, and 33.7%, respectively, heralding a promising era of water and environmental sustainability in the leather sector. This study holds the potential to transform leather production, wherein the envisioned future on the use of the Taguchi model and optimized MaSil tanning system could find a place in shaping a cleaner, greener, and more sustainable leather industry.

Transvaginal ultrasound-guided direct thrombin injection for the treatment of intramyometrial pseudoaneurysm in a young female with uterine hemorrhage after failed uterine artery embolization.

Uterine artery pseudoaneurysm is an uncommon but important cause of severe uterine bleeding in the postpartum or postsurgical setting. The standard treatment options are endovascular uterine artery embolization and bilateral surgical internal iliac artery ligation for uterus conservation or hysterectomy. We report the case of a young female with hemorrhage from an intramyometrial pseudoaneurysm following repeated curettage and hysteroscopic excision of retained products of conception. Uterus preservation was of priority, and the patient underwent uterine artery embolization; however, the pseudoaneurysm persisted due to ovarian artery collaterals. The pseudoaneurysm was subsequently treated with transvaginal ultrasound-guided direct thrombin injection. The case highlights the advantages and disadvantages of the treatment options in such clinically challenging cases emphasizing the seldom employed direct injection of thrombin for the treatment of pseudoaneurysms.

Induced apnea enhances image quality and visualization of cardiopulmonary anatomic during contrastenhanced cardiac computerized tomographic angiography in children.

OBJECTIVE: The purpose of our study was to determine the effect of induced apnea on quality of cardiopulmonary structures during computerized tomographic (CT) angiography images in children with congenital heart diseases. METHODS: Pediatric patients with congenital heart defects undergoing cardiac CT angiography at our facility in the past 3 years participated in this study. The earlier patients underwent cardiac CT angiography without induced apnea and while, later, apnea was induced in patients, which was followed by electrocardiogram gated cardiac CT angiography. General anesthesia was induced using sleep dose of intravenous propofol. After the initial check CT, on request by the radiologist, apnea was induced by the anesthesiologist by administering 1 mg/kg of intravenous suxamethonium. Soon after apnea ensued, the contrast was injected, and CT angiogram carried out. CT images in the "apnea group" were compared with those in "nonapnea group." After the completion of the procedure, the patients were mask ventilated with 100% oxygen till the spontaneous ventilation was restored. RESULTS: We studied 46 patients, of whom 36 with apnea and yet another 10 without. The quality of the image, visualization of structures such as cardiac wall, outflow tracts, lung field, aortopulmonary shunts, and coronary arteries were analyzed and subjected to statistical analysis (Mann-Whitney U, Fischer's exact test and Pearson's Chi-square test). In the induced apnea group, overall image quality was considered excellent in 89% (n = 33) of the studies, while in the "no apnea group," only 30% of studies were excellent. Absent or minimal motion artifacts were seen in a majority of the studies in apnea group (94%). In the nonapnea group, the respiratory and body motion artifacts were severe in 50%, moderate in 30%, and minimal in 20%, but they were significantly lesser in the apnea group. All the studied parameters were statistically significant in the apnea group in contrast to nonapnea group (P < 0.000). CONCLUSION: The image quality of cardiac CT angiography greatly improves, and motion artifact significantly decreases with the use of induced apnea in pediatrics patients being evaluated for congenital heart disease. This technique poses no additional morbidity of significance.

Polarization selective, graded-reflectivity resonance filter, using a space-varying guided-mode resonance structure.

We designed, fabricated, and tested, polarization selective, graded-reflectivity resonant filters; based on a radial-gradient spatially-distributed, guided-mode resonance device architecture. The demonstrated filters have polarized spectral-resonance responses, distributed across their aperture extent, in the range between 1535 nm and 1540 nm wavelengths. Spectral sensitivity was observed on device tests, for wavelength changes as low as 0.2 nm. Using multiple lithographic exposures and biasing exposure methods, the devices were engineered to have a sub-aperture region, with no hard boundaries or diffraction anomalies.

Spatial and spectral beam shaping with space-variant guided mode resonance filters.

Novel all-dielectric beam shaping elements were developed based on guided mode resonance (GMR) filters. This was achieved by spatially varying the duty cycle of a hexagonal-cell GMR filter, to locally detune from the resonant condition, which resulted in modified wavelength dependent reflection and transmission profiles, across the device aperture. This paper presents the design, fabrication, and characterization of the device and compares simulations to experimental results.

Design and optimization of space-variant photonic crystal filters.

A space-variant photonic crystal filter is designed and optimized that may be placed over a detector array to perform filtering functions tuned for each pixel. The photonic crystal is formed by etching arrays of holes through a multilayer stack of alternating high and low refractive index materials. Position of a narrow transmission notch within a wide reflection band is varied across the device aperture by adjusting the diameter of the holes. Numerical simulations are used to design and optimize the geometry of the photonic crystal. As a result of physics inherent in the etching process, the diameter of the holes reduces with depth, producing a taper. Optical performance was found to be sensitive to the taper, but a method for compensation was developed where film thickness is varied through the device.

Spatially polarizing autocloned elements.

A space-variant polarization converting element is introduced that utilizes an autocloning effect to produce high aspect ratio from birefringent gratings. This method utilizes a multilayer deposition process on a template to convert a linearly polarized incident beam to an azimuthally polarized output at a wavelength of 1.55 microm with more than 90% efficiency.

Micromachined arrays of cantilevered glass probes.

We describe the fabrication and characterization of cantilevered glass probe arrays. Individual probes have tapered shafts that are 175 microm square at the base and 200 nm square at the pyramidal tip. Each array contains as many as eight probes 10-20 mm long at 450-microm center-to-center spacing, fabricated from a single glass wafer by a combination of dicing and chemical etching. Optical signal losses of individual probes were measured to be of the order of 1 dB/cm. High-density data storage and page-oriented retrieval are the potential applications of the arrays.