Low pressure DC-plasma system for the modification of polymeric membrane surfaces

The main objectives of this work were to develop a lab-scale direct current (DC) glow discharges plasma system for modification of organic and inorganic membranes. Characteristics of plasma system were presented under the discharge of five gases (Ar, N2, air, O2, and CO2). A Langmuir double probe was used for the evaluation of the electron temperature (Te) and electron density (ne) of plasmas. The current and voltage (I-V) characteristic curves were analyzed. Relationships between breakdown voltage (VB) of gases and products of gas pressure and inter-electrode gap (pd) were studied in form of Paschen curves. The results showed that Te of plasma in various gases was in the range of 4-13 eV, while the ne varied between 108 and 109 cm-3. The plasma generated at different gas pressure and applied voltage is in the normal and abnormal modes. Finally, the constructed DC-plasma system was utilized for modification of polymeric membrane surfaces. Treatment time, discharge power and type of gas were varied. The tailoring of membrane surfaces was analyzed through the water contact angle and percent-weight loss (PWL) measurements, DMTA, AFM, XPS and FTIR spectrum. It could be shown that DC-plasma from this system can be used to modify the surface of polymeric membranes

Monte Carlo simulation of 6 MV flattening filter free photon beam of TrueBeam STx LINAC at Songklanagarind Hospital

In this study, 6 MV photon beam of TrueBeam STx Varian LINAC with Flattening Filter Free (FFF) was simulated using PRIMO code. The depth dose profiles for various jaws open fields and cross beam profiles for various depths inside water phantom were determined using Monte Carlo (MC) simulation technique and validated with experimental result. The experiments were performed using the Source to Surface Distance (SSD) technique with a 100 cm distance from target to the surface of water. Simulation used 109 histories with the same configurations with experiments. The depth dose profiles and cross beam profiles of 6 MV FFF photon beam was determined using MC simulations and compared with experimental results. The results showed that depth dose profiles and cross beam profiles by MC simulation accurately matched with experimental results. The best result of depth dose profile was obtained at 10×10 cm2 jaws open field with 98.53% passing criterion whereas cross beam profile was obtained at 10 cm depth inside water phantom with 88.96% passing criterion.The discrepancies were caused by scatter of particle and incompatibility of primary beam in PRIMO with experiment

Surface Modification of Asymmetric Polysulfone/Polyethylene Glycol Membranes by DC Ar-Glow Discharge Plasma

Polysulfone/polyethylene glycol (PSF/PEG) membranes were prepared by dry/wet phase inversion method. Effects of direct current glow discharge plasma using argon as working gas on morphological structures and gas separation properties of membranes were studied. Alteration of membrane characteristics were analyzed by various techniques like contact angle, scanning electron microscope, Fourier transform infrared spectroscopy, and dynamic mechanical thermal analysis. Gas separation properties were measured in terms of permeation and ideal O2/N2 selectivity. Results showed that hydrophilic and gas separation properties of PSF/PEG membranes increased by plasma surface modification. It was also shown that the dosage of PEG and plasma treatment affected the morphological structures and mechanical and gas separation properties. The macro voids and transmembrane structure disappeared with a little amount of PEG dosage. Pore size and mechanical strength tend to decrease with increasing PEG dosage up to 10 wt%. Glass transition temperature (Tg) receded from 201.8 to 143.7°C for pure PSF and PSF/PEG with PEG dosage of 10 wt%. O2 and N2 gases permeation through the 10-minute plasma treated membranes tend to increase. However, the permeation strongly dispersed when treatment time was more extended

Stretched State Excitations in the 26-Mg(p,n)26-Al Reaction at 134 MeV

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

Shell Model Description of Isotope Shifts in Calcium

Isotope shifts in the nuclear charge radius of even and odd calcium isotopes are calculated within the nuclear shell model. The model space includes all configurations of nucleons in the $2s, 1d_{3/2}, 1f_{7/2}, {\rm and} ~2p_{3/2}$ orbits. The shell model describes well the energies of the intruder states in Sc and Ca, as well as the energies of the low-lying $2^+$ and $3^-$ states in the even Ca isotopes. The characteristic features of the isotope shifts, the parabolic dependence on $A$ and the prominent odd-even staggering, are well reproduced by the model. These features are related to the partial breakdown of the $Z = 20$ shell closure caused by promotion, due to the neutron-proton interaction, of the $ds$ shell protons into the $fp$ shell.Comment: 4 pages, 4 figures include

Magnetic dipole probes of the sd and pf shell crossing in the A=36,38 argon isotopes

We have calculated the M1 strength distributions in the A=36,38 argon isotopes within large-scale shell model studies which consider valence nucleons in the sd and pf shells. While the M1 strength in 36Ar is well reproduced within the sd shell, the experimentally observed strong fragmentation of the M1 strength in 38Ar requires configuration mixing between the sd and the pf shells adding to our understanding of correlations across the N=20 shell gap.Comment: 14 pages, 8 figure

Sinteza, spazmolitsko i antidijaretsko djelovanje nekih 1-supstituiranih derivata imidazola

A series of 1-substituted imidazoles 1a-d and 2a-d were synthesized and screened for antispasmodic and antidiarrheal activities. Antispasmodic activity was tested at various concentrations on isolated tissue preparations; concentration-response curves were plotted and compared with atropine. All compounds were found to inhibit contraction of the guinea pig ileum. Castor oil-induced diarrhea model in rats was used for evaluation of antidiarrheal activity. Parameters such as intestinal transit and volume of intestinal fluid were measured for antidiarrheal activity at 40 mg kg-1 dose and compared with the standard drug loperamide at a 6 mg kg1 dose. Defecation frequency in the test group was found to be significantly lower (p < 0.01) compared to the control group and comparable with that of the standard. The present study reveals that the compounds exert antidiarrheal activity through possible inhibition of intestinal movement and reduction of capillary permeability in the abdominal cavity.U radu je opisana sinteza serije novih 1-supstituiranih imidazola 1a-d i 2a-d te evaluacija njihovog spazmolitskog i antidijaretskog djelovanja. Spazmolitsko djelovanje različith koncentracija ispitivanih spojeva (10, 50 i 100 µg mL1) ispitano je na izoliranim tkivnim preparatima; krivulje ovisnosti djelovanja o koncentraciji uspoređene su s djelovanjem atropina. Svi ispitivani spojevi inhibirali su kontrakcije ileuma zamorca. Dijarea inducirana ricinusovim uljem u štakora korištena je za vrednovanje antidijaretskog djelovanja. Intestinalni prijenos i volumen intestinalne tekućine mjereni su pri dozi od 40 mg kg1 i uspoređeni s učinkom standarda loperamida (doza 6 mg kg1). Učestalost defekacije u testiranoj skupini bila je značajno niža (p < 0,01) u usporedbi s kontrolnom skupinom i standardom. Provedena ispitivanja pokazuju da antidijaretsko djelovanje ispitivanih spojeva može biti posljedica inhibicije intestinalnih pokreta i redukcije kapilarne permeabilnosti u abdominalnoj šupljini

PSU Quality Assurance Newsletter Y.1 No.1

Quality Assurance Office Tel. 0 7428 2940, 0 7428 2822 Fax. 0 7428 2822 E-mail : [email protected] Homepage : http://www.qa.psu.ac.t

Geological and Seismicity Evaluation of Srinagarind Dam

In April of 198 3, a sequence of earthquakes were recorded by the National Seismic Network where the epicenters were located in the upper reaches of the Srinagarind Reservoir. A detailed evaluation of these earthquakes has been initiated since that time. Network of micro seismic instruments have also been installed in the region in order to establish the capability of higher resolution for seismic parameters and allow the greater understanding of the mechanism of the activity. After seven years of monitoring and data collecting, analyses of the results have been performed. Results obtained from the evaluation of overall characteristic seismicity, including the review of world wide data on the seismic, geologic and characteristics of reservoir triggered seismicity (RTS) ensure us to accept the high possibility of reservoir induced seismicity phenomena

Nondestructive quality assessment of shogun mandarin fruits (Citrus reticulata Blanco cv. Shogun) using compton scattering of gamma-ray technique

Compton scattering of gamma radiation was applied for nondestructive testing of the shogun mandarin fruits with good quality defined as no dry sack or dry fibrous structures inside. In principle, the scattering deviated angles to the left and right of a gamma ray that penetrates through a homogeneous fibrous structure meat of any orange fruit should be equal. The source Cs-137, with an initial gamma ray activity of 9.25 mCi, placed in a 7 cm thick lead shielding, was radiated through a 10 mm diameter collimator onto any single fruit to be tested. A NaI(Tl)-detector, oriented perpendicular to both left and right of theincoming beam, was placed 5 cm from the fruit. Results showed that the net count rate of the scattering beam between the left and right counting for good-quality shogun mandarin with proper tissue for consumption was less than 85 counts per minute (average 83 cpm), whereas shogun mandarin with dry sack, which were unfit for consumption, had twice that rate or more (average 175 cpm)