Detection of Thermoluminescence in Polyether Ether Ketone (PEEK)

Sterilization is a mandatory process for materials used in medical applications. Sterilization procedures commonly used are steam sterilization, ethylene oxide (EtO) sterilization and sterilization by radiation. The high energy photons incident upon a polymer can cause chain scission, crosslinking, defects (trapped electrons) within the polymer matrix, and the formation of free radicals. In this research work, we used thermally stimulated luminescence (TSL) and differential scanning calorimeter (DSC) to study the effects of X- and UV-irradiation on different grades of PEEK. We have observed a major sharp glow peak at temperature of about 150°C (with other five minor peaks), at the glass transition temperature of PEEK, similar to previous researchers. After X- and UV- irradiation the peak at about 100°C is much more affected by radiation. Initially, its intensity increases rapidly with the time of exposure to radiation and then increases slowly. Also, the observation showed that, after irradiation the intensity of peak at 100ºC decreases rapidly as the time passes and the effect of radiation persists for only about 24 hours after irradiation. The PEEK polymer is affected more by X-ray in comparison with UV-radiation. TSL of preheated samples of PEEK shows glow peak at about 75ºC and its intensity is found to increase with increase in preheat temperature. Moreover, the initial major TSL peak at about 150ºC completely disappear when the PEEK (film) is preheated at 250ºC for one hour in air and it reappears again as the sample is stored for longer time (within one day) at room temperature. DSC measurement shows a large exothermic crystallization peak at temperature 180 for PEEK film. This indicates that material has a strong tendency to crystallize. We observed that the glass transition temperature (Tg) increases and melting temperature (Tm) decreases slightly as a result of X-irradiation for all types of PEEK. Similar observations were made by past researcher in PEEK for γ- and e-beam irradiation. The shift of Tg to higher temperature and Tm to lower temperature with irradiation suggest that both cross-linking as well as chain scission mechanisms take place due to X-irradiation

Detection of Thermoluminescence in Polyether Ether Ketone (PEEK)

Sterilization is a mandatory process for materials used in medical applications. Sterilization procedures commonly used are steam sterilization, ethylene oxide (EtO) sterilization and sterilization by radiation. The high energy photons incident upon a polymer can cause chain scission, crosslinking, defects (trapped electrons) within the polymer matrix, and the formation of free radicals. In this research work, we used thermally stimulated luminescence (TSL) and differential scanning calorimeter (DSC) to study the effects of X- and UV-irradiation on different grades of PEEK. We have observed a major sharp glow peak at temperature of about 150°C (with other five minor peaks), at the glass transition temperature of PEEK, similar to previous researchers. After X- and UV- irradiation the peak at about 100°C is much more affected by radiation. Initially, its intensity increases rapidly with the time of exposure to radiation and then increases slowly. Also, the observation showed that, after irradiation the intensity of peak at 100ºC decreases rapidly as the time passes and the effect of radiation persists for only about 24 hours after irradiation. The PEEK polymer is affected more by X-ray in comparison with UV-radiation. TSL of preheated samples of PEEK shows glow peak at about 75ºC and its intensity is found to increase with increase in preheat temperature. Moreover, the initial major TSL peak at about 150ºC completely disappear when the PEEK (film) is preheated at 250ºC for one hour in air and it reappears again as the sample is stored for longer time (within one day) at room temperature. DSC measurement shows a large exothermic crystallization peak at temperature 180 for PEEK film. This indicates that material has a strong tendency to crystallize. We observed that the glass transition temperature (Tg) increases and melting temperature (Tm) decreases slightly as a result of X-irradiation for all types of PEEK. Similar observations were made by past researcher in PEEK for γ- and e-beam irradiation. The shift of Tg to higher temperature and Tm to lower temperature with irradiation suggest that both cross-linking as well as chain scission mechanisms take place due to X-irradiation

General Overview of Wastewater Treatment Process with Special Focus on Secondary Treatment Method

Wastewater is used water that comes down the drains from buildings such as household, factory, school, or offices and includes sources like showers, sinks, dishwasher, toilet, etc. It contains substances from various sources including organics, medicine, and several other substances like toilet paper, cleaning & personal products that are harmful to the environment. It also contains diverse trophic level of microorganisms such as protozoans, fungi, and varieties of bacteria (aerobic, anaerobic, and facultative). Therefore, a treatment facility needs to be equipped with several processes and unit operations so that a complete decontamination can take place before water is released to the natural environment. Each unit operation in a wastewater treatment plant (WWTP) is associated with mechanical, physical, biological, and chemical aspects of cleaning.This contribution is focused on reviewing these general cleaning processes and operations and identifying connections with fundamental principles in engineering. Thus, we are looking for appropriateness of employing more effective and efficient variations associated with the biological processes (activated sludge). The aim is to develop an environment to mimic the naturally occurring microbiology and biochemistry in the human system during the metabolic breakdown of these chemicals and biopharmaceuticals. The secondary treatment is identical to a metabolic type of biological reactor that can be modelled and optimized. The targeted outcome is to identify the key factors controlling the metabolic degradation and make potential observations helpful to increase the degradation efficiency. Our study could be potentially useful for the design of a more efficient and better maintained treatment

Nanostructure Evolution of Magnetron Sputtered Hydrogenated Silicon Thin Films

Hydrogenated silicon (Si:H) thin films have been prepared by radio frequency (RF) magnetron sputtering. The effect of hydrogen gas concentration during sputtering on the resultant film structural and optical properties has been investigated by real time spectroscopic ellipsometry (RTSE) and grazing incidence x-ray diffraction (GIXRD). The analysis of in-situ RTSE data collected during sputter deposition tracks the evolution of surface roughness and film bulk layer thickness with time. Growth evolution diagrams depicting amorphous, nanocrystalline and mixed-phase regions for low and high deposition rate Si:H are constructed and the effects of process parameter (hydrogen gas concentration, total pressure and RF power) variations on the deposition rate have been qualified. Virtual interface analysis of RTSE data provides nanocrystalline volume fraction depth profiles in the mixed-phase growth regime. GIXRD measurements show the presence of (111) and (220) oriented crystallites. Vibrational mode absorption features from Si-Hn bonding configurations at 590, 640, 2000 and 2090 cm-1 are obtained by ex-situ infrared spectroscopic ellipsometry. Hydrogen incorporation decreases as films transition from amorphous to nanocrystalline phases with increasing hydrogen gas concentration during sputtering. Published by AIP Publishing

n-i-p Nanocrystalline Hydrogenated Silicon Solar Cells with RF-Magnetron Sputtered Absorbers

Nanocrystalline hydrogenated silicon (nc-Si:H) substrate configuration n-i-p solar cells have been fabricated on soda lime glass substrates with active absorber layers prepared by plasma enhanced chemical vapor deposition (PECVD) and radio frequency magnetron sputtering. The cells with nanocrystalline PECVD absorbers and an untextured back reflector serve as a baseline for comparison and have power conversion efficiency near 6%. By comparison, cells with sputtered absorbers achieved efficiencies of about 1%. Simulations of external quantum efficiency (EQE) are compared to experimental EQE to determine a carrier collection probability gradient with depth for the device with the sputtered i-layer absorber. This incomplete collection of carriers generated in the absorber is most pronounced in material near the n/i interface and is attributed to breaking vacuum between deposition of layers for the sputtered absorbers, possible low electronic quality of the nc-Si:H sputtered absorber, and damage at the n/i interface by over-deposition of the sputtered i-layer during device fabrication

Foodborne Outbreak Investigation in a Festival at Panchkhal Municipality of Kavrepalanchok District in Central Nepal

Background: On September 2018, cluster of gastrointestinal cases following feast of Teej Festival was reported in Panchkhal Municipality of Kavrepalanchok, Nepal. The outbreak was investigated to identify the possible source of infection, causative agent and guide local control measures for prevention and control of the outbreak. Methods: Demographic and clinical details were collected from the cases, and the outbreak was described by time, place and person. Fourteen key informant interviews were conducted to assess the probable cause of infection, practice of food handling and preparation, source of drinking water. Semi-structured questionnaires were used to collect data from the cases. Blood examination, stool examination and culture and hepatitis serological test were done. Samples from wells and ponds were collected and microbiological tests were done in National Public Health Laboratory. Results: A total of 452 cases were identified with gastrointestinal illness and no reported deaths. All the affected population had taken food from the same place during the festival where children being more affected. Two stool samples detected Entamoeba Histolytica and some showed pus cells with no cyst or ova of organisms. Stool culture was negative. No definitive source of infection detected but was suspected to be due to improper food handling. Conclusion: This investigations confirmed the food borne outbreak in Panchkhal Municipality. The definitive causative agent of the foodborne outbreak was not identified. Proper and timely response to the outbreak is of utmost important, and can reduce the severity of the illness and halt further spread of the epidemics

Assessing the prospects of transboundary multihazard dynamics:The case of Bhotekoshi—Sunkoshi watershed in Sino—Nepal border region

The impacts of multihazards have become more pronounced over the past few decades globally. Multiple hazards and their cascading impacts claim enormous losses of lives, livelihoods, and built environment. This paradigm prompts integrated and multidisciplinary perspectives to identify, characterize, and assess the occurrence of multihazards and subsequently design counter-measures considering impending multihazard scenarios at the local level. To this end, we considered one of the most egregious transboundary watersheds, which is regarded as a multihazard hotspot of Nepal, to analyze the underlying causes and cascade scenarios of multihazards, and their associated impacts. In this paper, geophysical, hydrometeorological, and socioeconomic perspectives are formulated to characterize the watershed from the dimension of susceptibility to multihaz-ard occurrence. To characterize the complex dynamics of transboundary multihazard occurrence, insights have been presented from both the Nepali and the Chinese sides. Individual case studies and the interrelation matrix between various natural hazards are also presented so as to depict mul-tihazard consequences in the transboundary region. The sum of the observations highlights that the watershed is highly vulnerable to a single as well as multiple natural hazards that often switch to disasters

Multi-Hazard Risk Assessment of Kathmandu Valley, Nepal

Natural hazards are complex phenomena that can occur independently, simultaneously, or in a series as cascading events. For any particular region, numerous single hazard maps may not necessarily provide all information regarding impending hazards to the stakeholders for preparedness and planning. A multi-hazard map furnishes composite illustration of the natural hazards of varying magnitude, frequency, and spatial distribution. Thus, multi-hazard risk assessment is performed to depict the holistic natural hazards scenario of any particular region. To the best of the authors’ knowledge, multi-hazard risk assessments are rarely conducted in Nepal although multiple natural hazards strike the country almost every year. In this study, floods, landslides, earthquakes, and urban fire hazards are used to assess multi-hazard risk in Kathmandu Valley, Nepal, using the Analytical Hierarchy Process (AHP), which is then integrated with the Geographical Information System (GIS). First, flood, landslide, earthquake, and urban fire hazard assessments are performed individually and then superimposed to obtain multi-hazard risk. Multi-hazard risk assessment of Kathmandu Valley is performed by pair-wise comparison of the four natural hazards. The sum of observations concludes that densely populated areas, old settlements, and the central valley have high to very high level of multi-hazard risk

Unzipping flood vulnerability and functionality loss:tale of struggle for existence of riparian buildings

Floods pose significant risk to riparian buildings as evidenced during many historical events. Although structural resilience to tsunami flooding is well studied in the literature, high-velocity and debris-laden floods in steep terrains are not considered adequately so far. Historical floods in steep terrains necessitate the need for flood vulnerability analysis of buildings. To this end, we report vulnerability of riparian-reinforced concrete buildings using forensic damage interpretations and empirical/analytical vulnerability analyses. Furthermore, we propose the concept and implications of functionality loss due to flooding in residential reinforced concrete (RC) buildings using empirical data. Fragility functions using inundation depth and momentum flux are presented for RC buildings considering a recent flooding event in Nepal. The results show that flow velocity and sediment load, rather than hydrostatic load, govern the damages in riparian RC buildings. However, at larger inundation depth, hydrostatic force alone may collapse some of the RC buildings