Study on functional outcome of intra articular fractures of distal humerus managed by locking compression plate

Background: The primary goal in management of intra articular fractures of distal humerus is to achieve stable and mobile elbow. Type C fracture of distal humerus is a relatively uncommon fracture. Internal fixation is difficult but anatomical reduction is needed to prevent poor functional outcome and degenerative changes.Methods: Functional outcome of patients who underwent open reduction internal fixation with locking compression plates for intra articular fractures of distal humerus at the department of orthopedics, Government medical college Kottayam, from December 2017 to July 2019, were assessed using Mayo elbow performance index. A total of 30 patients were studied.Results: Excellent and good results were found in 25 cases, 3 patients had fair outcome and 2 patients had poor result. Complications encountered in our study were, infection (superficial treated with antibiotics-3 cases), heterotopic ossification (3 cases), hard ware prominence (2 cases) and non-union (1 case).Conclusions: Complications were minimal and outcomes were good in patients with type C distal humerus fractures who underwent bicolumn locking compression plates fixation by posterior approach.

Vascular injuries associated with total knee arthroplasty

Iatrogenic vascular injuries are rare but potentially devastating complications of total knee arthroplasty (TKA). This retrospective study analyzes vascular injuries associated with total knee arthroplasties in an urban, tertiary level referral hospital between 01 April 2010 to 31 March 2020 consisting of 6548 TKAs. Six patients sustained vascular injuries which included five primary, and one revision TKAs. Three patients were bilateral, and two were unilateral primary TKAs. The mean age-adjusted Charlson’s comorbidity index was two (range 1-3). Only two injuries were recognized intraoperatively. They underwent successful vascular repair. The third patient was diagnosed and underwent a vascular repair on the first postoperative day but experienced a permanent foot drop. Two other patients underwent thrombectomy on the fifth postoperative day; one required above-knee amputation, and the other continued to suffer from vascular claudication and paraesthesia. Another patient developed a pseudoaneurysm, which was identified and repaired five months after the primary TKA. The site of vascular injury was popliteal artery in five and superficial femoral artery in one patient. The mechanism of injury was a direct laceration in three, posterior Hohman's retractor in one, the effect of tourniquet on calcified vessels in one, and unknown in one patient. Early recognition was the only factor that significantly altered the functional outcome and limb salvage. Bilateral simultaneous total knee arthroplasties had no higher risks. A mandatory institutional protocol to recognize the early signs of vascular injuries is necessary for successful vascular repair

Engineering Economical and Sustainable Solutions for the Abatement of Volatile Organic Compounds

Over the last three decades, combined efforts of industries, the EPA, and automakers have helped reduce the emission of many harmful molecules such as carbon monoxide, sulfur dioxide, and particulate matter to improve air quality. However, rapid industrialization and urbanization have contributed to a significant rise in volatile organic compounds (VOCs), one of the primary air pollutants. Prolonged exposure to certain VOCs, even at concentrations as low as 0.25 ppm, is known to be carcinogenic. Therefore, the detrimental health impacts of VOCs and their increasingly stringent environmental regulations warrant continuous research to develop more effective, economical, and sustainable technologies to mitigate their emissions. In most industries, the VOCs are curtailed by combining an adsorption-desorption process using beaded activated carbon (BAC) with subsequent thermal incineration. This hybrid VOC abatement system suffers from two major limitations. First, the occurrence of strongly, or irreversibly adsorbed species in BAC, referred to as “heel”, prevents complete regeneration of the sorbent, decreasing its capacity and lifetime. Second, the massive energy requirement of the thermal incinerator increases the carbon footprint of the operation and overall operational cost. The research presented in this dissertation provides economical and sustainable strategies to address the limitations of the hybrid abatement process described above. Using spectroscopic and thermogravimetric techniques, we aimed at understanding the factors responsible for the heel accumulation in BAC during gas-phase adsorption-desorption operation. Addressing this, the dissertation provides a facile methodology to modify the surface of the BAC through a chemical treatment to impede heel formation. This modification protocol increases the porosity of BAC by up-to 55% without altering its structural integrity. Consequently, the adsorption capacity of the BAC increased by nearly 38% while decreasing the peak desorption temperature by as much as 50°C due to lowered adsorption strength. Furthermore, this thesis explored feasible methods of regenerating the spent BAC to improve the efficacy of the industrial VOC abatement technique. This effort resulted in the invention of a unique vapor-phase regeneration technique. The lab-scale studies demonstrated that dimethyl sulfoxide vapors could be effectively used to recover nearly 82% of the adsorption capacity of the spent BAC without compromising its structural integrity. The second phase of this research investigated the feasibility of using energy-efficient catalytic oxidation to decompose or destroy VOCs into H2O and CO2 at low temperatures. As such, the dissertation provides a roadmap to the synthesis of a novel catalyst architecture of encapsulating catalytically active noble metals in porous TiO2 support. Electron microscopic studies indicated that encapsulation helps maintain a uniform metal particle distribution (2-5 nm) and promotes metal-support interactions by maximizing interfacial sites, thereby improving catalytic activity. In addition, we discovered that subjecting the encapsulated catalyst to a post-synthesis solvothermal treatment step anchors the active metal more strongly to the support, which helps maintain superior activity under repeated uses. Finally, the thesis attempts to push the boundaries of catalytic VOC oxidation reactions via concurrent utilization of thermal energy and visible light to bring down the overall energy requirement of the VOC abatement. By encapsulating plasmonic silver nanostructures in a porous TiO2 shell resembling a core@shell morphology, we created a multifunctional material capable of generating energetic electrons upon visible light illumination. These electrons can be used in tandem with thermal energy to decompose n-butanol at viable rates at significantly reduced temperatures as low as 200°C.PHDChemical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/170068/1/bhatada_1.pd

Insight into hydrothermal aging effect on deactivation of Pd/SSZ-13 as low-temperature NO adsorption catalyst: Effect of dealumination and Pd mobility

Pd/SSZ-13 samples with the same Pd loading (1 wt.%) but different Si/Al ratio (6 and 13) were hydrothermally aged at 800, 850, and 900 ºC, respectively. The Pd/SSZ-13 with a lower Si/Al ratio suffers a more severe deactivation. The Pd/SSZ-13 with a Si/Al ratio of 6 experiences structural damage due to dealumination, while the structure of the sample with a Si/Al ratio of 13 remains intact. The agglomeration of Pd 2+ ions to large PdO particles on the external surface of zeolite causes the deactivation. The Pd cations are mobile during aging. Besides dealumination, the Pd 2+ ions might be hydrolyzed and have a high mobility, which also results in the Pd 2+ ions agglomeration. The severe dealumination causes the deactivation after aging at 900 ºC. However, the Pd mobility might be the primary reason for the decline of NO adsorption capacity of Pd/SSZ-13 after aging at 800 and 850 °C.Peer reviewe

Understanding the chemistry during the preparation of Pd/SSZ-13 for the low-temperature NO adsorption: The role of NH4-SSZ-13 support

The chemistry during the preparation of Pd/SSZ-13, including impregnation and calcination process, was investigated, using Pd(NO3)2 as precursor and NH4-SSZ-13 as the support. Special attention was paid on analyzing the improvement effect of NH4-SSZ-13 support on Pd2+ ions dispersion. The Pd(NO3)2 precursor remained intact after impregnation and transformed to Pd(NH3)x2+ during calcination at 200−290 °C, and then converted to Pd2+ ions occupying the ion-exchange sites by oxidizing the NH3 ligands to N2 at 290−450 °C. The formation of Pd(NH3)x2+ intermediates is a critical factor for achieving high Pd2+ dispersion, probably due to the fact that NH3 ligands give the intermediates high mobility, facilitating their movement to the ion-exchange sites. The PdO formation might be related to the excessive reduction of Pd2+ sites to metallic Pd, when catalyzing the oxidation of NH3 ligands and the NH4+ on the Brønsted acid sites.Peer reviewe

Stabilizing Highly Dispersed Halo Sites in Thermally Restructured Palladium Core@shell Nanoparticles for Improved Catalyst Activity and Durability

Stabilizing high dispersions of catalytically active metals is integral to improving the lifetime, activity, and material utilization of catalysts that are periodically exposed to high temperatures during operation or maintenance. We have found that annealing palladium-based core@shell catalysts in air at elevated temperature (800°C) promotes the redispersion of active metal into highly dispersed sites, which we refer to as halo sites. Here, we examine the restructuring of Pd@SiO2 and Pd@CeO2 core@shell catalysts over successive 800°C aging cycles to understand the formation, activity, nanoscale structure and stability of these palladium halo sites. While encapsulation generally improves metal utilization by providing a physical barrier that promotes redispersion over agglomeration, our cycled aging experiments demonstrate that halo sites are not stable in all catalysts. Halo sites continue to migrate in Pd@SiO2 due to poor metal-support bonding, which leads to palladium agglomeration. In contrast, halo sites formed in Pd@CeO2 remain stable. The dispersed palladium also synergistically stabilizes the ceria from agglomerating. We attribute this stability, in addition to an observed improvement in catalytic activity, to the coordination between palladium and reducible ceria that arises during the formation of halo sites. We probe the importance of ceria oxidation state on the stability of halo sites by aging Pd@CeO2 after it has been reduced. While some halo sites agglomerate, we find that returning to air aging mitigates the loss of these sites and catalytic activity. Our findings illustrate how nanoscale catalyst structures can be designed to promote the formation of highly stable and dispersed metal sites

Effect of self-heating on electrical characteristics of AlGaN/ GaN HEMT on Si (111) substrate

In order to study the effect of self-heating of AlGaN/ GaN high electron mobility transistors (HEMTs) characteristics fabricated on Si(111) substrate, simulations of 2DEG temperature on different drain voltages have been carried out by Sentaurus TCAD simulator tool. Prior to the electrical direct-current (DC) characteristics studies, structural properties of the HEMT structures were examined by scanning transmission electron microscopy. The comparative analysis of simulation and experimental data provided sheet carrier concentration, mobility, surface traps, electron density at 2DEG by considering factors such as high field saturation, tunneling and recombination models. Mobility, surface trap concentration and contact resistance were obtained by TCAD simulation and found out to be ∼1270cm2/Vs, ∼2×1013 cm-2 and ∼0.2 Ω.mm, respectively, which are in agreement with the experimental results. Consequently, simulated current-voltage characteristics of HEMTs are in good agreement with experimental results. The present simulator tool can be used to design new device structures for III-nitride technology