Search results for: deposition dose
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 2203

Search results for: deposition dose

1963 Safe Disposal of Processed Industrial Biomass as Alternative Organic Manure in Agriculture

Authors: V. P. Ramani, K. P. Patel, S. B. Patel

Abstract:

It is necessary to dispose of generated industrial wastes in the proper way to overcome the further pollution for a safe environment. Waste can be used in agriculture for good quality higher food production. In order to evaluate the effect and rate of processed industrial biomass on yield, contents, uptake and soil status in maize, a field experiment was conducted during 2009 - 2011 at Anand on loamy sand soil for two years. The treatments of different levels of NPK i.e. 100% RD, 75% RD and 50% RD were kept to study the possibility of reduction in fertilizer application with the use of processed biomass (BM) in different proportion with FYM. (Where, RD= Recommended dose, FYM= Farm Yard Manure, BM= Processed Biomass.) The significantly highest grain yield of maize was recorded under the treatment of 75% NPK + BM application @ 10t ha-1. The higher (10t ha-1) and lower (5t ha-1) application rate of BM with full dose of NPK was found beneficial being at par with the treatment 75% NPK along with BM application @ 10t ha-1. There is saving of 25% recommended dose of NPK when combined with BM application @ 10.0t ha-1 or 50% saving of organics when applied with full dose (100%) of NPK. The highest straw yield (7734 kg ha-1) of maize on pooled basis was observed under the treatment of recommended dose of NPK along with FYM application at 7.5t ha-1 coupled with BM application at 2.5t ha-1. It was also observed that highest straw yield was at par under all the treatments except control and application of 100% recommended dose of NPK coupled with BM application at 7.5t ha-1. The Fe content of maize straw were found altered significantly due to different treatments on pooled basis and it was noticed that biomass application at 7.5t ha-1 along with recommended dose of NPK showed significant enhancement in Fe content of straw over other treatments. Among heavy metals, Co, Pb and Cr contents of grain were found significantly altered due to application of different treatments variably during the pooled. While, Ni content of maize grain was not altered significantly due to application of different organics. However, at higher rate of BM application i.e. of 10t ha-1, there was slight increase in heavy metal content of grain/ straw as well as DTPA heavy metals in soil; although the increase was not alarming Thus, the overall results indicated that the application of BM at 5t ha-1 along with full dose of NPK is beneficial to get higher yield of maize without affecting soil / plant health adversely. It also indicated that the 5t BM ha-1 could be utilized in place of 10t FYM ha-1 where FYM availability is scarce. The 10t BM ha-1 helps to reduce a load of chemical fertilizer up to 25 percent in agriculture. The lower use of agro-chemicals always favors safe environment. However, the continuous use of biomass needs periodical monitoring to check any buildup of heavy metals in soil/ plant over the years.

Keywords: alternate use of industrial waste, heavy metals, maize, processed industrial biomass

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1962 Activities for Increasing Childhood Vaccination Coverage of the Refugee and Migrant Population, Greece, European Program PHILOS, 2017

Authors: C. Silvestros, K. Mellou, T. Georgakopoulou, A. Koustenis, E. Kokkinou, C. Botsi, A. Terzidis

Abstract:

'PHILOS – Emergency health response to refugee crisis' is a programme of the Greek Ministry of Health, implemented by the Hellenic Center for Disease Control and Prevention (HCDCP) funded by the Asylum, Migration and Integration Fund (AMIF) of EU’s DG Migration and Home Affairs. One of the main objectives of the program is the immunization coverage of the target – population to assure the prevention of vaccine-preventable diseases. The program foresees vaccination needs assessment of children hosted at camps at the mainland and implementation of interventions to cover the vaccination gaps in co-operation with the Ministry of Health. The National Immunization Advisory Committee in Greece recommended that MMR (Measles, Mumps, and Rubella), PCV (Pneumococcal conjugate vaccine) and HEXA (diphtheria, tetanus, pertussis, polio, hepatitis B and Haemophilus influenzae type b) vaccines should be performed in priority. Recording was completed at 24 camps (May - June 2017); 3381 children (0-18 years) were recorded. The median number of children hosted at each camp was 95 (range: 5-553). For 68% of the children, the WHO vaccination booklet was available. 44%, 48.5% and 61% of the children were vaccinated with at least one dose of PCV, HEXA, and MMR, respectively. The proportion of vaccinated children for the three vaccines mentioned above is significantly lower for the remaining doses; PCV (second dose 8%, third dose 1.3%), HEXA (second dose 13%, third dose 2.7%, forth dose 0.1%) and MMR (second dose 23%). None of the 37 (10 from Afghanistan, 3 from Bangladesh, 23 from Pakistan, 1 from Syria) recorded unaccompanied children did not have a WHO vaccination booklet and were considered unvaccinated. There is no differentiation in vaccination coverage among different ethnicities. Massive catch up vaccination was performed at 4 camps, and 671 vaccinations were performed (245 PCV, 307 HEXA, and 119 MMR). Similar interventions are planned for all camps of the country. Recording reveled gaps in vaccination coverage of the population, mainly because of the mobility of the population, the influx of refugees- which is still ongoing- and new births. Mass vaccination campaigns are considered vital in order to increase vaccination coverage, and continuous efforts are needed in order all children living at the camps to have full access to the National Childhood Immunization Program.

Keywords: vaccine preventable, refugee–migrants camps, vaccination coverage, PCV, MMR, HEXA

Procedia PDF Downloads 157
1961 Dosimetric Comparison of Conventional Plans versus Three Dimensional Conformal Simultaneously Integrated Boost Plans

Authors: Shoukat Ali, Amjad Hussain, Latif-ur-Rehman, Sehrish Inam

Abstract:

Radiotherapy plays an important role in the management of cancer patients. Approximately 50% of the cancer patients receive radiotherapy at one point or another during the course of treatment. The entire radiotherapy treatment of curative intent is divided into different phases, depending on the histology of the tumor. The established protocols are useful in deciding the total dose, fraction size, and numbers of phases. The objective of this study was to evaluate the dosimetric differences between the conventional treatment protocols and the three-dimensional conformal simultaneously integrated boost (SIB) plans for three different tumors sites (i.e. bladder, breast, and brain). A total of 30 patients with brain, breast and bladder cancers were selected in this retrospective study. All the patients were CT simulated initially. The primary physician contoured PTV1 and PTV2 in the axial slices. The conventional doses prescribed for brain and breast is 60Gy/30 fractions, and 64.8Gy/36 fractions for bladder treatment. For the SIB plans biological effective doses (BED) were calculated for 25 fractions. The two conventional (Phase I and Phase II) and a single SIB plan for each patient were generated on Eclipse™ treatment planning system. Treatment plans were compared and analyzed for coverage index, conformity index, homogeneity index, dose gradient and organs at risk doses.In both plans 95% of PTV volume received a minimum of 95% of the prescribe dose. Dose deviation in the optic chiasm was found to be less than 0.5%. There is no significant difference in lung V20 and heart V30 in the breast plans. In the rectum plans V75%, V50% and V25% were found to be less than 1.2% different. Deviation in the tumor coverage, conformity and homogeneity indices were found to be less than 1%. SIB plans with three dimensional conformal radiotherapy technique reduce the overall treatment time without compromising the target coverage and without increasing dose to the organs at risk. The higher dose per fraction may increase the late effects to some extent. Further studies are required to evaluate the late effects with the intention of standardizing the SIB technique for practical implementation.

Keywords: coverage index, conformity index, dose gradient, homogeneity index, simultaneously integrated boost

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1960 Standardization Of Miniature Neutron Research Reactor And Occupational Safety Analysis

Authors: Raymond Limen Njinga

Abstract:

The comparator factors (Fc) for miniature research reactors are of great importance in the field of nuclear physics as it provide accurate bases for the evaluation of elements in all form of samples via ko-NAA techniques. The Fc was initially simulated theoretically thereafter, series of experiments were performed to validate the results. In this situation, the experimental values were obtained using the alloy of Au(0.1%) - Al monitor foil and a neutron flux setting of 5.00E+11 cm-2.s-1. As was observed in the inner irradiation position, the average experimental value of 7.120E+05 was reported against the theoretical value of 7.330E+05. In comparison, a percentage deviation of 2.86 (from theoretical value) was observed. In the large case of the outer irradiation position, the experimental value of 1.170E+06 was recorded against the theoretical value of 1.210E+06 with a percentage deviation of 3.310 (from the theoretical value). The estimation of equivalent dose rate at 5m from neutron flux of 5.00E+11 cm-2.s-1 within the neutron energies of 1KeV, 10KeV, 100KeV, 500KeV, 1MeV, 5MeV and 10MeV were calculated to be 0.01 Sv/h, 0.01 Sv/h, 0.03 Sv/h, 0.15 Sv/h, 0.21Sv/h and 0.25 Sv/h respectively with a total dose within a period of an hour was obtained to be 0.66 Sv.

Keywords: neutron flux, comparator factor, NAA techniques, neutron energy, equivalent dose

Procedia PDF Downloads 151
1959 Process Optimization for 2205 Duplex Stainless Steel by Laser Metal Deposition

Authors: Siri Marthe Arbo, Afaf Saai, Sture Sørli, Mette Nedreberg

Abstract:

This work aims to establish a reliable approach for optimizing a Laser Metal Deposition (LMD) process for a critical maritime component, based on the material properties and structural performance required by the maritime industry. The component of interest is a water jet impeller, for which specific requirements for material properties are defined. The developed approach is based on the assessment of the effects of LMD process parameters on microstructure and material performance of standard AM 2205 duplex stainless steel powder. Duplex stainless steel offers attractive properties for maritime applications, combining high strength, enhanced ductility and excellent corrosion resistance due to the specific amounts of ferrite and austenite. These properties are strongly affected by the microstructural characteristics in addition to microstructural defects such as porosity and welding defects, all strongly influenced by the chosen LMD process parameters. In this study, the influence of deposition speed and heat input was evaluated. First, the influences of deposition speed and heat input on the microstructure characteristics, including ferrite/austenite fraction, amount of porosity and welding defects, were evaluated. Then, the achieved mechanical properties were evaluated by standard testing methods, measuring the hardness, tensile strength and elongation, bending force and impact energy. The measured properties were compared to the requirements of the water jet impeller. The results show that the required amounts of ferrite and austenite can be achieved directly by the LMD process without post-weld heat treatments. No intermetallic phases were observed in the material produced by the investigated process parameters. A high deposition speed was found to reduce the ductility due to the formation of welding defects. An increased heat input was associated with reduced strength due to the coarsening of the ferrite/austenite microstructure. The microstructure characterizations and measured mechanical performance demonstrate the great potential of the LMD process and generate a valuable database for the optimization of the LMD process for duplex stainless steels.

Keywords: duplex stainless steel, laser metal deposition, process optimization, microstructure, mechanical properties

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1958 Characteristics of the Particle Size Distribution and Exposure Concentrations of Nanoparticles Generated from the Laser Metal Deposition Process

Authors: Yu-Hsuan Liu, Ying-Fang Wang

Abstract:

The objectives of the present study are to characterize nanoparticles generated from the laser metal deposition (LMD) process and to estimate particle concentrations deposited in the head (H), that the tracheobronchial (TB) and alveolar (A) regions, respectively. The studied LMD chamber (3.6m × 3.8m × 2.9m) is installed with a robot laser metal deposition machine. Direct-reading instrument of a scanning mobility particle sizer (SMPS, Model 3082, TSI Inc., St. Paul, MN, USA) was used to conduct static sampling inside the chamber for nanoparticle number concentration and particle size distribution measurements. The SMPS obtained particle number concentration at every 3 minutes, the diameter of the SMPS ranged from 11~372 nm when the aerosol and sheath flow rates were set at 0.6 and 6 L / min, respectively. The resultant size distributions were used to predict depositions of nanoparticles at the H, TB, and A regions of the respiratory tract using the UK National Radiological Protection Board’s (NRPB’s) LUDEP Software. Result that the number concentrations of nanoparticles in indoor background and LMD chamber were 4.8×10³ and 4.3×10⁵ # / cm³, respectively. However, the nanoparticles emitted from the LMD process was in the form of the uni-modal with number median diameter (NMD) and geometric standard deviation (GSD) as 142nm and 1.86, respectively. The fractions of the nanoparticles deposited on the alveolar region (A: 69.8%) were higher than the other two regions of the head region (H: 10.9%), tracheobronchial region (TB: 19.3%). This study conducted static sampling to measure the nanoparticles in the LMD process, and the results show that the fraction of particles deposited on the A region was higher than the other two regions. Therefore, applying the characteristics of nanoparticles emitted from LMD process could be provided valuable scientific-based evidence for exposure assessments in the future.

Keywords: exposure assessment, laser metal deposition process, nanoparticle, respiratory region

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1957 Molecular Dynamic Simulation of Cold Spray Process

Authors: Aneesh Joshi, Sagil James

Abstract:

Cold Spray (CS) process is deposition of solid particles over a substrate above a certain critical impact velocity. Unlike thermal spray processes, CS process does not melt the particles thus retaining their original physical and chemical properties. These characteristics make CS process ideal for various engineering applications involving metals, polymers, ceramics and composites. The bonding mechanism involved in CS process is extremely complex considering the dynamic nature of the process. Though CS process offers great promise for several engineering applications, the realization of its full potential is limited by the lack of understanding of the complex mechanisms involved in this process and the effect of critical process parameters on the deposition efficiency. The goal of this research is to understand the complex nanoscale mechanisms involved in CS process. The study uses Molecular Dynamics (MD) simulation technique to understand the material deposition phenomenon during the CS process. Impact of a single crystalline copper nanoparticle on copper substrate is modelled under varying process conditions. The quantitative results of the impacts at different velocities, impact angle and size of the particles are evaluated using flattening ratio, von Mises stress distribution and local shear strain. The study finds that the flattening ratio and hence the quality of deposition was highest for an impact velocity of 700 m/s, particle size of 20 Å and an impact angle of 90°. The stress and strain analysis revealed regions of shear instabilities in the periphery of impact and also revealed plastic deformation of the particles after the impact. The results of this study can be used to augment our existing knowledge in the field of CS processes.

Keywords: cold spray process, molecular dynamics simulation, nanoparticles, particle impact

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1956 Effect of O2 Pressure of Fe-Doped TiO2 Nanostructure on Morphology Properties for Gas Sensing

Authors: Samar Y. Al-Dabagh, Adawiya J. Haider, Mirvat D. Majed

Abstract:

Pure nanostructure TiO2 and thin films doped with transition metal Fe were prepared by pulsed laser deposition (PLD) on Si (111) substrate. The thin films structures were determined by X-ray diffraction (XRD). The morphology properties were determined from atomic force microscopy (AFM), which shows that the roughness increases when TiO2 is doped with Fe. Results show TiO2 doped with Fe metal thin films deposited on Si (111) substrate has maximum sensitivity to ethanol vapor at 10 mbar oxygen pressure than at 0.01 and 0.1 mbar with optimum operation temperature of 250°C.

Keywords: pulsed laser deposition (PLD), TiO2 doped thin films, nanostructure, gas sensor

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1955 Simulation on Influence of Environmental Conditions on Part Distortion in Fused Deposition Modelling

Authors: Anto Antony Samy, Atefeh Golbang, Edward Archer, Alistair McIlhagger

Abstract:

Fused deposition modelling (FDM) is one of the additive manufacturing techniques that has become highly attractive in the industrial and academic sectors. However, parts fabricated through FDM are highly susceptible to geometrical defects such as warpage, shrinkage, and delamination that can severely affect their function. Among the thermoplastic polymer feedstock for FDM, semi-crystalline polymers are highly prone to part distortion due to polymer crystallization. In this study, the influence of FDM processing conditions such as chamber temperature and print bed temperature on the induced thermal residual stress and resulting warpage are investigated using the 3D transient thermal model for a semi-crystalline polymer. The thermo-mechanical properties and the viscoelasticity of the polymer, as well as the crystallization physics, which considers the crystallinity of the polymer, are coupled with the evolving temperature gradient of the print model. From the results, it was observed that increasing the chamber temperature from 25°C to 75°C lead to a decrease of 1.5% residual stress, while decreasing bed temperature from 100°C to 60°C, resulted in a 33% increase in residual stress and a significant rise of 138% in warpage. The simulated warpage data is validated by comparing it with the measured warpage values of the samples using 3D scanning.

Keywords: finite element analysis, fused deposition modelling, residual stress, warpage

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1954 Renal Amyloidosis in Domestic Iranian Sheep

Authors: Keivan Jamshidi, Fateme Behbahani, Sara Omidi, Nadia Shahi, Alireza Farkhonde

Abstract:

Amyloidosis represents a heterogenous group of diseases that have in common the deposition of fibrils composed of proteins of beta-pleated sheet structure, which can be specifically identified by histochemistry using the Congo red or similar stains. Between October 2013 to April 2014 (6 months) different patterns of renal amyloidosis was diagnosed on histopathological examination of kidneys belong to 196 out of 7065 slaughtered sheep subjected to postmortem examination. Microscopic examination of renal tissue sections stained with H&E and CR staining techniques revealed 3 patterns of renal amyloid deposition; including glomerular (22.72%), medullary (68.18%), and vascular (9.09%) were recognized. Renal medullary amyloidosis (RMA) was detected as the most prevalence pattern of renal amyloidosis in domestic sheep.

Keywords: sheep, amyloidosis, kidney, slaughterhouse

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1953 Factors Associated with Ketamine Use in Pancreatic Cancer Patient in a Single Hospice Center

Authors: Kyung Min Kwom, Young Joo Lee

Abstract:

Purpose: Up to 90% of pancreatic cancer patient suffer from neuropathic pain. In palliative care setting, pain control in a pancreatic cancer patient is one of the major goals. Ketamine is a NMDA receptor antagonist effective in neuropathic pain. Also, there have been studies about opioid sparing effect of ketamine. This study was held in palliative care unit among pancreatic cancer patients to find out the factors related to ketamine use and the opioid sparing effect. Methods: Medical records of pancreatic cancer patients admitted to St. Mary’s hospital palliative care unit from 2013.1 to 2014.12 were reviewed. Patients were divided into two categories according to ketamine use. Also, opioid use before and after ketamine use was compared in ketamine group. Results: Compared to non ketamine use group, patients in ketamine group required a higher dose of opioid. Total opioid dose, daily opioid dose, number of daily rescue medication, daily average rescue dose were statistically significantly higher in ketamine group. Opioid requirement was increased after ketamine administration. Conclusion: In this study, ketamine group required more opioid. Ketamine is frequently considered in patients with severe pain, requiring high amount of opioid. Also, ketamine did not have an opioid sparing effect. Future studies about palliative use of ketamine in a larger number of patients are required.

Keywords: ketamine, opioid sparing, palliative care, pancreatic cancer

Procedia PDF Downloads 210
1952 Conformal Noble Metal High-Entropy Alloy Nanofilms by Atomic Layer Deposition for Enhanced Hydrogen Evolution Reaction/Oxygen Evolution Reaction Electrocatalysis Applications

Authors: Jing Lin, Zou Yiming, Goei Ronn, Li Yun, Amanda Ong Jiamin, Alfred Tok Iing Yoong

Abstract:

High-entropy alloy (HEA) coatings comprise multiple (five or more) principal elements that give superior mechanical, electrical, and thermal properties. However, the current synthesis methods of HEA coating still face huge challenges in facile and controllable preparation, as well as conformal integration, which seriously restricts their potential applications. Herein, we report a controllable synthesis of conformal quinary HEA coating consisting of noble metals (Rh, Ru, Ir, Pt, and Pd) by using the atomic layer deposition (ALD) with a post-annealing approach. This approach realizes low temperature (below 200 °C), precise control (nanoscale), and conformal synthesis (over complex substrates) of HEA coating. Furthermore, the resulting quinary HEA coating shows promising potential as a platform for catalysis, exhibiting substantially enhanced electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances as compared to other noble metal-based structures such as single metal coating or multi-layered metal composites.

Keywords: high-entropy alloy, thin-film, catalysis, water splitting, atomic layer deposition

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1951 Determination of Natural Gamma Radioactivity in Sand along the Black Sea Coastal Region of Giresun, North Turkey

Authors: A. Karadeniz, Belgin Kucukomeroglu

Abstract:

In this study natural gamma radioactivity levels are determined on sands along the coastal regions of Giresun/Turkey. The coast of Giresun about 290 km long in investigated to collect 101 sand samples. Natural and artificial radioactivity concentrations of sand samples were measured by using HPGe gamma spectrometry. The average activity concentrations of 238U, 232Th, 40K and 137Cs on sand samples of Giresun were found to be 10.83±2.92 Bq/kg, 21.28±3.22 Bq/kg, 6.42±1.06 Bq/kg, 230.94±10.67 Bq/kg respectively. The average activity concentrations for these radionuclides were compared with the reported data of other parts of Turkey and other countries. The average absorbed dose rate for Giresun was calculated to be 38.68 nGy/h respectively. This value is significantly lower than the World averaged value of 60 nGy/h. The external annual effective dose rate concentration in Giresun was found to be 0.047 mSv/y respectively. This result is much lower than the recommeded limit of 5 mSv/y. The external hazard dose rate for Giresun weas calculated to be 0.21 respectively. This result is much lower than the recommended limit of 1.0.

Keywords: concentration, radioactivity, Giresun, natural gamma radioactivity

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1950 Study of Nanocrystalline Al Doped Zns Thin Films by Chemical Bath Deposition Method

Authors: Hamid Merzouk, Djahida Touati-Talantikite, Amina Zaabar

Abstract:

New nanosized materials are in huge expansion worldwide. They play a fundamental role in various industrial applications thanks their unique and functional properties. Moreover, in recent years, a great effort has been made to the design and control fabrication of nanostructured semiconductors such zinc sulphide. In recent years, much attention has been accorded in doped and co-doped ZnS to improve the ZnS films quality. We present in this work the preparation and characterization of ZnS and Al doped ZnS thin films. Nanoparticles ZnS and Al doped ZnS films are prepared by chemical bath deposition method (CBD), for various dopant concentrations. Thin films are deposed onto commercial microscope glass slides substrates. Thiourea is used as sulfide ion source, zinc acetate as zinc ion source and manganese acetate as manganese ion source in alkaline bath at 90 °C. X-ray diffraction (XRD) analyses are carried out at room temperature on films and powders with a powder diffractometer, using CuKα radiation. The average grain size obtained from the Debye–Scherrer’s formula is around 10 nm. Films morphology is examined by scanning electron microscopy. IR spectra of representative sample are recorded with the FTIR between 400 and 4000 cm-1.The transmittance (70 %) is performed with the UV–VIS spectrometer in the wavelength range 200–800 nm. This value is enhanced by Al doping.

Keywords: ZnS, nanostructured semiconductors, thin films, chemical bath deposition

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1949 Oral Antibiotics in Trans-Rectal Prostate Biopsy and Its Efficacy to Reduce Infectious Complications: Systematic Review

Authors: Mohand Yaghi, O. Kehinde

Abstract:

Background: For the diagnosis of prostate cancer Trans-rectal prostate biopsy (TRPB) is used commonly, the procedure is associated with infective complications. There is evidence that antibiotics (ABx) decrease infective events after TRPB, but different regimens are used. Aim: To systematically review different regimens of prophylactic oral antibiotics in TRPB. Design: Medline, Embase, Clinical trials site, and Cochrane library were searched, experts were consulted about relevant studies. Randomized clinical trials (RCT) conducted in the last twenty years, which investigated different oral antibiotic regimens in TRPB, and compared their efficacy to reduce infectious complications were analyzed. Measurements: Primary outcomes were bacteriuria, urinary tract infection (UTI), fever, bacteremia, sepsis. Secondary outcomes were hospitalization rate, and the prevalence of ABx-resistant bacteria. Results: Nine trials were eligible with 3012 patients. Antibiotics prevented bacteriuria (3.5% vs. 9.88%), UTI (4.46% vs. 9.75%), and hospitalization (0.21% vs. 2.13%) significantly in comparison with placebo or no treatment. No significant difference was found in all outcomes of the review between the single dose regimen and the 3 days. The single dose regimen was as effective as the multiple dose except in Bacteriuria (6.75% vs. 3.25%), and the prevalence of ABx-resistant bacteria (1.57% vs. 0.27%). Quinolones reduced only UTI significantly in comparison with other antibiotics. Lastly, Ciprofloxacin is the best Quinolone to prevent UTI, and hospitalization. Conclusion: it is essential to prescribe prophylactic Antibiotics in TRPB. No conclusive evidence could be claimed about the superiority of the multiple or the 3 days regimens to the single dose regimen. Unexpectedly, ABx-resistant bacteria was identified more often in the single dose cohorts.

Keywords: infection, prostate cancer, sepsis, TRPB

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1948 Cu Nanoparticle Embedded-Zno Nanoplate Thin Films for Highly Efficient Photocatalytic Hydrogen Production

Authors: Premrudee Promdet, Fan Cui, Gi Byoung Hwang, Ka Chuen To, Sanjayan Sathasivam, Claire J. Carmalt, Ivan P. Parkin

Abstract:

A novel single-step fabrication of Cu nanoparticle embedded ZnO (Cu.ZnO) thin films was developed by aerosol-assisted chemical vapor deposition for stable and efficient hydrogen production in Photoelectrochemical (PEC) cell. In this approach, the Cu.ZnO nanoplate thin films were grown by using acetic acid to promote preferential growth and enhance surface active sites, where Cu nanoparticles can be formed under chemical deposition by reduction of Cu salt. Studies using photoluminescence spectroscopy indicate the enhanced photocatalytic performance is attributed to hot electron generated from SPR. The Cu metal in the composite material is functioning as a sensitizer to supply electrons to the semiconductor resulting in enhanced electron density for redox reaction. This work not only describes a way to obtain photoanodes with high photocatalytic activity but also suggests a low-cost route towards production of photocatalysts for hydrogen production. This work also supports a vital need to understand electron transfer between photoexcited semiconductor materials and metals, a requirement for tailoring the properties of semiconductor/metal composites.

Keywords: photocatalysis, photoelectrochemical cell (PEC), aerosol-assisted chemical vapor deposition (AACVD), surface plasmon resonance (SPR)

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1947 Anxieolytic Activity of Ethyl Acetate Extract of Flowers Nerium indicum

Authors: D. S. Mohale, A. V. Chandewar

Abstract:

Anxiety is defined as an exaggerated feeling of apprehension, uncertainty and fear. Nerium indicum is a well-known ornamental and medicinal plant belonging to the family Apocynaceae. A wide spectrum of biological activities has been reported with various constituents isolated from different parts of the plant. This study was conducted to investigate antianxiety activity of flower extract. Flowers were collected and dried in shade and coarsely powdered. Powdered mixture was extracted with ethyl acetate by maceration process. Extract of flowers obtained was subsequently dried in oven at 40-50 °C. This extract is then tested for antianxiety activity at low and high dose using Elevated Plus Maze and Light & dark Model. Rats shown increased open arm entries and time spent in open arm in elevated Plus maze with treatment low and high dose of extract of Nerium indicum flower as compared to their respective control groups. In Light & dark Model, light box entries and time spent in light box increased with treatment low and high dose of extract of Nerium indicum flower as compared to their respective control groups. From result it is concluded that Ethyl acetate extract of flower of Nerium indicum possess antianxiety activity at low and high dose.

Keywords: anxiety, anxieolytic, social isolation, nerium indicum, kaner

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1946 Atomic Layer Deposition of MoO₃ on Mesoporous γ-Al₂O₃ Prepared by Sol-Gel Method as Efficient Catalyst for Oxidative Desulfurization of Refractory Dibenzothiophene Compound

Authors: S. Said, Asmaa A. Abdulrahman

Abstract:

MoOₓ/Al₂O₃ based catalyst has long been widely used as an active catalyst in oxidative desulfurization reaction due to its high stability under severe reaction conditions and high resistance to sulfur poisoning. In this context, 4 & 9wt.% MoO₃ grafted on mesoporous γ-Al₂O₃ has been synthesized using the modified atomic layer deposition (ALD) method. Another MoO₃/Al₂O₃ sample was prepared by the conventional wetness impregnation (IM) method, for comparison. The effect of the preparation methods on the metal-support interaction was evaluated using different characterization techniques, including X-ray diffraction, X-ray photoelectron spectroscopy (XPS), N₂-physisorption, transmission electron microscopy (TEM), H₂- temperature-programmed reduction and FT-IR. Oxidative desulfurization (ODS) reaction of the model fuel oil was used as a probe reaction to examine the catalytic efficiency of the prepared catalysts. ALD method led to samples with much better physicochemical properties than those of the prepared one via the impregnation method. However, the 9 wt.%MoO₃/Al₂O₃ (ALD) catalyst in the ODS reaction of model fuel oil shows enhanced catalytic performance with ~90%, which has been attributed to the more Mo⁶⁺ surface concentrations relative to Al³⁺ with large pore diameter and surface area. The kinetic study shows that the ODS of DBT follows a pseudo first-order rate reaction.

Keywords: mesoporous Al₂O₃, xMoO₃/Al₂O₃, atomic layer deposition, wetness impregnation, ODS, DBT

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1945 Coastline Change at Koh Tao Island, Thailand

Authors: Cherdvong Saengsupavanich

Abstract:

Human utilizes coastal resources as well as deteriorates them. Coastal tourism may degrade the environment if poorly managed. This research investigated the shoreline change at Koa Toa Island, one of the most famous tourist destinations. Aerial photographs and satellite images from three different periods were collected and analyzed. The results showed that the noticeable shoreline change before and after the tourism on the island had expanded. Between 1995 and 2002 when the tourism on Koh Toa Island was not intensive, sediment deposition occurred along most of the coastline. However, after the tourism had grown during 2002 to 2015, the coast evidently experienced less deposition and more erosion. The erosion resulted from less land-based sediment being provided to the littoral system. If the coastline of Koh Toa Island is not carefully sustained, the tourism will disappear along with the beautiful beach.  

Keywords: coastal engineering and management, coastal erosion, coastal tourism, Koh Toa Island, Thailand

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1944 Low-Surface Roughness and High Optical Quality CdS Thin Film Deposited on Heated Substrate Using Room-Temperature Chemical Solution

Authors: A. Elsayed, M. H. Dewaidar, M. Ghali, M. Elkemary

Abstract:

The high production cost of the conventional solar cells requires the search for economic methods suitable for solar energy conversion. Cadmium Sulfide (CdS) is one of the most important semiconductors used in photovoltaics, especially in large area solar cells; and can be prepared in a thin film form by a wide variety of deposition techniques. The preparation techniques include vacuum evaporation, sputtering and molecular beam epitaxy. Other techniques, based on chemical solutions, are also used for depositing CdS films with dramatically low-cost compared to other vacuum-based methods. Although this technique is widely used during the last decades, due to simplicity and low-deposition temperature (~100°C), there is still a strong need for more information on the growth process and its relation with the quality of the deposited films. Here, we report on deposition of high-quality CdS thin films; with low-surface roughness ( < 3.0 nm) and sharp optical absorption edge; on low-temperature glass substrates (70°C) using a new method based on the room-temperature chemical solution. In this method, a mixture solution of cadmium acetate and thiourea at room temperature was used under special growth conditions for deposition of CdS films. X-ray diffraction (XRD) measurements were used to examine the crystal structure properties of the deposited CdS films. In addition, UV-VIS transmittance and low-temperature (4K) photoluminescence (PL) measurements were performed for quantifying optical properties of the deposited films. The deposited films show high optical quality as confirmed by observation of both, sharp edge in the transmittance spectra and strong PL intensity at room temperature. Furthermore, we found a strong effect of the growth conditions on the optical band gap of the deposited films; where remarkable red-shift in the absorption edge with temperature is clearly seen in both transmission and PL spectra. Such tuning of both optical band gap of the deposited CdS films can be utilized for tuning the electronic bands' alignments between CdS and other light-harvesting materials, like CuInGaSe or CdTe, for potential improvement in the efficiency of solar cells devices based on these heterostructures.

Keywords: chemical deposition, CdS, optical properties, surface, thin film

Procedia PDF Downloads 129
1943 Rituximab Therapy for Musculoskeletal Involvement in Systemic Sclerosis

Authors: Liudmila Garzanova, Lidia Ananyeva, Olga Koneva, Olga Ovsyannikova, Oxana Desinova, Mayya Starovoytova, Rushana Shayahmetova, Anna Khelkovskaya-Sergeeva

Abstract:

Objectives. There is very few data on changes of the musculoskeletal manifestations (artritis, arthralgia, muscle weakness, etc.) in systemic sclerosis (SSc) on rituximab (RTX) therapy. The aim of our study was to assess the severity of the musculoskeletal involvement in SSc patients (pts) and its changes during RTX therapy. Methods. Our study included 103 pts with SSc. The mean followup period was 12.6±10.7 months. The mean age was 47±12.9 years, female-87 pts (84%), the diffuse cutaneous subset of the disease had 55 pts (53%). The mean disease duration was 6.2±5.5 years. All pts had interstitial lung disease (ILD) and were positive for ANA, 67% of them were positive for antitopoisomerase-1. All patients received prednisolone at a dose of 11.3±4.5 mg/day, immunosuppressants at inclusion received 47% of them. Pts received RTX due to the ineffectiveness of previous therapy for ILD. The cumulative mean dose of RTX was 1.7±0.6 grams. Arthritis was observed in 22 pts (21%), arthralgias in 47 pts (46%). Muscle weakness was observed in 17 pts (17%). Tendon friction rubs was established in 7 pts (7%). The results at baseline and at the end of the follow up are presented in the form of mean values. Results. There was an improvement of all outcome parameters and musculoskeletal manifestations on RTX therapy. There was a decrease in the number of pts with arthritis from 22 (21%) to 10 (9%), a decrease in the number of pts with arthralgias from 47 (46%) to 31 (30%). The number of pts with muscle weakness decreased from 17 (17%) to 7 (7%). The number of pts with tendon friction rubs decreased from 7 (7%) to 3 (3%). The creatine phosphokinase decreased from 365.5±186 to 70.8±50.4 (p=0.00006). The C-reactive protein (CRP) decreased from 23.2±31.3 to 8.62±7.4 (p=0.001). The dose of prednisolone was reduced from 11.3±4.5 to 9.8±3.5 mg/day (p=0.0004). Conclusion. In our study, musculoskeletal involvement was detected in almost half of the patients with SSc-ILD. There was an improvement of musculoskeletal manifestations despite a small cumulative dose of RTX. We also managed to reduce the dose of glucocorticosteroids. The improvement of musculoskeletal manifestations was accompanied by a decrease in laboratory parameters - creatine phosphokinase and CRP. RTX is effective option for treatment of musculoskeletal manifestations in SSc.

Keywords: arthritis, musculoskeletal involvement, systemic sclerosis, rituximab

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1942 Performance of Different Spray Nozzles in the Application of Defoliant on Cotton Plants (Gossypium hirsutum L.)

Authors: Mohamud Ali Ibrahim, Ali Bayat, Ali Bolat

Abstract:

Defoliant spraying is an important link in the mechanized cotton harvest because adequate and uniform spraying can improve defoliation quality and reduce cotton trash content. In defoliant application, application volume and spraying technology are extremely important. In this study, the effectiveness of defoliant application to cotton plant that has come to harvest with two different application volumes and three different types of nozzles with a standard field crop sprayer was determined. Experiments were carried in two phases as field area trials and laboratory analysis. Application rates were 250 l/ha and 400 L/ha, and spraying nozzles were (1) Standard flat fan nozzle (TP8006), (2) Air induction nozzle (AI 11002-VS), and (3) Dual Pattern nozzle (AI307003VP). A tracer (BSF) and defoliant were applied to mature cotton with approximately 60% open bolls and samplings for BSF deposition and spray coverage on the cotton plant were done at two plant height (upper layer, lower layer) of plant. Before and after spraying, bolls open and leaves rate on cotton plants were calculated, and filter papers were used to detect BSF deposition, and water sensitive papers (WSP) were used to measure the coverage rate of spraying methods used. Spectrofluorophotometer was used to detect the amount of tracer deposition on targets, and an image process computer programme was used to measure coverage rate on WSP. In analysis, conclusions showed that air induction nozzle (AI 11002-VS) achieved better results than the dual pattern and standard flat fan nozzles in terms of higher depositions, coverages, and leaf defoliations, and boll opening rates. AI nozzles operating at 250 L/ha application rate provide the highest deposition and coverage rate on applications of the defoliant; in addition, BSF as an indicator of the defoliant used reached on leaf beneath in merely this spray nozzle. After defoliation boll opening rate was 85% on the 7th and 12th days after spraying and falling rate of leaves was 76% at application rate of 250 L/ha with air induction (AI1102) nozzle.

Keywords: cotton defoliant, air induction nozzle, dual pattern nozzle, standard flat fan nozzle, coverage rate, spray deposition, boll opening rate, leaves falling rate

Procedia PDF Downloads 158
1941 Tensile Properties of 3D Printed PLA under Unidirectional and Bidirectional Raster Angle: A Comparative Study

Authors: Shilpesh R. Rajpurohit, Harshit K. Dave

Abstract:

Fused deposition modeling (FDM) gains popularity in recent times, due to its capability to create prototype as well as functional end use product directly from CAD file. Parts fabricated using FDM process have mechanical properties comparable with those of injection-molded parts. However, performance of the FDM part is severally affected by the poor mechanical properties of the part due to nature of layered structure of printed part. Mechanical properties of the part can be improved by proper selection of process variables. In the present study, a comparative study between unidirectional and bidirectional raster angle has been carried out at a combination of different layer height and raster width. Unidirectional raster angle varied at five different levels, and bidirectional raster angle has been varied at three different levels. Fabrication of tensile specimen and tensile testing of specimen has been conducted according to ASTM D638 standard. From the results, it can be observed that higher tensile strength has been obtained at 0° raster angle followed by 45°/45° raster angle, while lower tensile strength has been obtained at 90° raster angle. Analysis of fractured surface revealed that failure takes place along with raster deposition direction for unidirectional and zigzag failure can be observed for bidirectional raster angle.

Keywords: additive manufacturing, fused deposition modeling, unidirectional, bidirectional, raster angle, tensile strength

Procedia PDF Downloads 152
1940 Genoprotective Effect of Lepidium sativum L. Seed Methanolic Extract on Cyclophosphamide-Induced DNA Damage in Mice and Characterization of Its Flavonoidal Content

Authors: Iman A. A. Kassem, Ayman A. Farghaly, Zeinab M. Hassan, Farouk R. Melek, Neveen S. Ghaly

Abstract:

Lipidium sativum L, an annual herb that grows to 50 cm, is known as an important member of family Brassicaceae. Besides its nutritional value, the seeds were widely used in folk medicine for treatment of cough, asthma, and headache. It was also reported to possess hypocholesterolemic, anti-inflammatory, antidiarrheal, antimicrobial and anticancer activities. In this study, the genoprotective properties of L. sativum seed methanolic extract (LSME) were evaluated in vivo. Three groups of mice were given LSME for five consecutive days at the three dose levels 25, 50 and 100 mg/kg b.wt. The three groups were then injected intraperitoneally with cyclophosphamide at a dose of 20 mg/kg b.wt. to induce DNA damage. A group received only cyclophosphamide (20 mg/kg b.wt.) served as control. LSME significantly inhibited the DNA aberrations in mice caused by cyclophosphamide in a dose-dependent manner in the two groups that received LSME at 50 and 100 mg/kg b.wt. dose levels. The chromosomal aberrations' inhibitory indices were calculated as 18 and 31 in mice bone marrow cells and 27 and 48 in mice spermatocytes, respectively. Phytochemical examination carried out by us revealed that flavonoids were the main chemical constituents of LSME. The major flavonoids kaempferol, kaempferol-3-O-rhamnoside, kaempferol-3-O-glucoside, quercetin, and quercetin-3-O-glucoside were isolated and characterized. It was concluded that the genoprotective effect of LSME might be attributed to the presence of flavonoids which are well-known for their antioxidant properties.

Keywords: cyclophosphamide, flavonoids, genoprotective effect, Lepidium sativum

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1939 Efficacy of Single-Dose Azithromycin Therapy for the Treatment of Chlamydia trachomatis in Patients Evaluated for Child Sexual Abuse in an Urban Health Center 2006-16

Authors: Trenton Hubbard, Kenneth Soyemi, Emily Siffermann

Abstract:

Introduction: According to the American Academy of Pediatrics (AAP) there are different weight-based recommendations for the treatment of Chlamydia trachomatis (CT) in patients who are being evaluated for sexual assault. Current AAP Red Book guidelines recommend that uncomplicated C. trachomatis anogenital infection in prepubertal patients weighing less than =<45 kg be treated with oral erythromycin 50 mg/kg/day QID for 14 days with no alternative therapies, and for patients whose weight => 45 kg are Azithromycin 1 gm PO once. Our study objective was to determine the efficacy of single-dose Azithromycin therapy for the treatment of Chlamydia trachomatis in patients weighing less than 50 kg who were evaluated for child sexual abuse in an urban setting. Methods: We conducted a retrospective chart review of historical medical records (paper and electronic) patients weighing less than 50 kg who were evaluated for child sexual abuse and subsequently treated for C. trachomatis infection with Azithromycin (20 mg/kg PO once up to a maximum 1 gm) and received a Test of Cure (TOC) from 2006-2016. Qualitative variables were expressed as percentages. Quantitative variables were expressed as mean values (+/- standard deviation [SD]) if they followed a normal distribution or as median values (interquartile range[IQR]) if they did not. Wilcoxson two-sample test was used to compare means of Azithromycin Dose, mg/kg, and TOC timing between treatment responders and non-responders. Results: We reviewed records of 34 patients, average age (SD) was 5.4 (2.0) years, 33 (97%) were treated for CT and 1(3%) for both GC and CT. 25 (74%) were females. Urine PCR was the most commonly used test at evaluation and as TOC with 13 (38%) patients completing both tests. The average (SD) dose of Azithromycin at treatment was 470 (136) mg and average (SD) mg/kg dose of 20 (1.9) mg/kg for all patients. Median (IQR) timing for TOC testing was 19 (14-26) days. Of the 33 with complete data 25 (74%) had a negative TOC. When compared with treatment non-responders (TOC failures), treatment responders received higher doses (average dose (SD) received 495 (139) vs 401(110), P 0.06)); similar average (SD) weight base dosing received (20.8(2.0) vs 19.7 (1.5), P 0.15)), and earlier average (SD)TOC test timing (18.8 (5.6) vs 32 (28.6) P 0.02)). Conclusion: Azithromycin dosing appears to be efficacious in the treatment of CT post sexual assault as majority of patients responded. Although treatment responders and non-responders received similar weight based doses, there is need for additional studies to understand variances and predictors of response.

Keywords: child sexual abuse, chlmaydia trachmotis infection, single-dose azithromycin, weight less than or equal to 45 kilograms

Procedia PDF Downloads 263
1938 'Low Electronic Noise' Detector Technology in Computed Tomography

Authors: A. Ikhlef

Abstract:

Image noise in computed tomography, is mainly caused by the statistical noise, system noise reconstruction algorithm filters. Since last few years, low dose x-ray imaging became more and more desired and looked as a technical differentiating technology among CT manufacturers. In order to achieve this goal, several technologies and techniques are being investigated, including both hardware (integrated electronics and photon counting) and software (artificial intelligence and machine learning) based solutions. From a hardware point of view, electronic noise could indeed be a potential driver for low and ultra-low dose imaging. We demonstrated that the reduction or elimination of this term could lead to a reduction of dose without affecting image quality. Also, in this study, we will show that we can achieve this goal using conventional electronics (low cost and affordable technology), designed carefully and optimized for maximum detective quantum efficiency. We have conducted the tests using large imaging objects such as 30 cm water and 43 cm polyethylene phantoms. We compared the image quality with conventional imaging protocols with radiation as low as 10 mAs (<< 1 mGy). Clinical validation of such results has been performed as well.

Keywords: computed tomography, electronic noise, scintillation detector, x-ray detector

Procedia PDF Downloads 96
1937 Microstructural Evolution of an Interface Region in a Nickel-Based Superalloy Joint Produced by Direct Energy Deposition

Authors: Matthew Ferguson, Tatyana Konkova, Ioannis Violatos

Abstract:

Microstructure analysis of additively manufactured (AM) materials is an important step in understanding the interrelationship between mechanical properties and materials performance. Literature on the effect of laser-based AM process parameters on the microstructure in the substrate-deposit interface is limited. The interface region, the adjoining area of substrate and deposit, is characterized by the presence of the fusion zone (FZ) and heat-affected zone (HAZ), experiencing rapid thermal gyrations resulting in thermal-induced transformations. Inconel 718 was utilized as work material for both the substrate and deposit. Three blocks of Inconel 718 material were deposited by Direct Energy Deposition (DED) using three different laser powers, 550W, 750W and 950W, respectively. A coupled thermo-mechanical transient approach was utilized to correlate temperature history to the evolution of microstructure. The thermal history of the deposition process was monitored with the thermocouples installed inside the substrate material. The interface region of the blocks was analyzed with Optical Microscopy (OM) and Scanning Electron Microscopy (SEM), including the electron back-scattered diffraction (EBSD) technique. Laser power was found to influence the dissolution of intermetallic precipitated phases in the substrate and grain growth in the interface region. Microstructure and thermal history data were utilized to draw conclusive comparisons between the investigated process parameters.

Keywords: additive manufacturing, direct energy deposition, electron back-scattered diffraction, finite element analysis, inconel 718, microstructure, optical microscopy, scanning electron microscopy, substrate-deposit interface region

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1936 Growth of Multi-Layered Graphene Using Organic Solvent-PMMA Film as the Carbon Source under Low Temperature Conditions

Authors: Alaa Y. Ali, Natalie P. Holmes, John Holdsworth, Warwick Belcher, Paul Dastoor, Xiaojing Zhou

Abstract:

Multi-layered graphene has been produced under low temperature chemical vapour deposition (CVD) growth conditions by utilizing an organic solvent and polymer film source. Poly(methylmethacrylate) (PMMA) was dissolved in chlorobenzene solvent and used as a drop-cast film carbon source on a quartz slide. A source temperature (Tsource) of 180 °C provided sufficient carbon to grow graphene, as identified by Raman spectroscopy, on clean copper foil catalytic surfaces.  Systematic variation of hydrogen gas (H2) flow rate from 25 standard cubic centimeters per minute (sccm) to 100 sccm and CVD temperature (Tgrowth) from 400 to 800 °C, yielded graphene films of varying quality as characterized by Raman spectroscopy. The optimal graphene growth parameters were found to occur with a hydrogen flow rate of 75 sccm sweeping the 180 °C source carbon past the Cu foil at 600 °C for 1 min. The deposition at 600 °C with a H2 flow rate of 75 sccm yielded a 2D band peak with ~53.4 cm-1 FWHM and a relative intensity ratio of the G to 2D bands (IG/I2D) of 0.21. This recipe fabricated a few layers of good quality graphene.

Keywords: graphene, chemical vapor deposition, carbon source, low temperature growth

Procedia PDF Downloads 136
1935 Invistigation of Surface Properties of Nanostructured Carbon Films

Authors: Narek Margaryan, Zhozef Panosyan

Abstract:

Due to their unique properties, carbon nanofilms have become the object of general attention and intensive research. In this case it plays a very important role to study surface properties of these films. It is also important to study processes of forming of this films, which is accompanied by a process of self-organization at the nano and micro levels. For more detailed investigation, we examined diamond-like carbon (DLC) layers deposited by chemical vapor deposition (CVD) method on Ge substrate and hydro-generated grapheme layers obtained on surface of colloidal solution using grouping method. In this report surface transformation of these CVD nanolayers is studied by atomic force microscopy (AFM) upon deposition time. Also, it can be successfully used to study surface properties of self-assembled grapheme layers. In turn, it is possible to sketch out their boundary line, which enables one to draw an idea of peculiarities of formation of these layers. Images obtained by AFM are investigated as a mathematical set of numbers and fractal and roughness analysis were done. Fractal dimension, Regne’s fractal coefficient, histogram, Fast Fourier transformation, etc. were obtained. The dependence of fractal parameters on the deposition duration for CVD films and on temperature of solution tribolayers was revealed. As an important surface parameter for our carbon films, surface energy was calculated as function of Regne’s fractal coefficient. Surface potential was also measured with Kelvin probe method using semi-contacting AFM. The dependence of surface potential on the deposition duration for CVD films and on temperature of solution for hydro-generated graphene was found as well. Results obtained by fractal analysis method was related with purly esperimental results for number of samples.

Keywords: nanostructured films, self-assembled grapheme, diamond-like carbon, surface potential, Kelvin probe method, fractal analysis

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1934 Development of R³ UV Exposure for the UV Dose-Insensitive and Cost-Effective Fabrication of Biodegradable Polymer Microneedles

Authors: Sungmin Park, Gyungmok Nam, Seungpyo Woo, Young Choi, Sangheon Park, Sang-Hee Yoon

Abstract:

Puncturing human skin with microneedles is critically important for microneedle-mediate drug delivery. Despite of extensive efforts in the past decades, the scale-up fabrication of sharp-tipped and high-aspect-ratio microneedles, especially made of biodegradable polymers, is still a long way off. Here, we present a UV dose insensitive and cost-effective microfabrication method for the biodegradable polymer microneedles with sharp tips and long lengths which can pierce human skin with low insertion force. The biodegradable polymer microneedles are fabricated with the polymer solution casting where a poly(lactic-co-glycolic acid) (PLGA, 50:50) solution is coated onto a SU-8 mold prepared with a reverse, ramped, and rotational (R3) UV exposure. The R3 UV exposure is modified from the multidirectional UV exposure both to suppress UV reflection from the bottom surface without anti-reflection layers and to optimize solvent concentration in the SU-8 photoresist, therefore achieving robust (i.e., highly insensitive to UV dose) and cost-effective fabrication of biodegradable polymer microneedles. An optical model for describing the spatial distribution of UV irradiation dose of the R3 UV exposure is also developed to theoretically predict the microneedle geometry fabricated with the R3 UV exposure and also to demonstrate the insensitiveness of microneedle geometry to UV dose. In the experimental characterization, the microneedles fabricated with the R3 UV exposure are compared with those fabricated with a conventional method (i.e., multidirectional UV exposure). The R3 UV exposure-based microfabrication reduces the end-tip radius by a factor of 5.8 and the deviation from ideal aspect ratio by 74.8%, compared with conventional method-based microfabrication. The PLGA microneedles fabricated with the R3 UV exposure pierce full-thickness porcine skins successfully and are demonstrated to completely dissolve in PBS (phosphate-buffered saline). The findings of this study will lead to an explosive growth of the microneedle-mediated drug delivery market.

Keywords: R³ UV exposure, optical model, UV dose, reflection, solvent concentration, biodegradable polymer microneedle

Procedia PDF Downloads 140