Effect of Gamma Irradiation on the Microstructure and Morphology of Polyethylene Oxide and Polyvinyl Alcohol Blends

2009 ◽  
Vol 83-86 ◽  
pp. 524-529
Author(s):  
Mariam Al-Ma'adeed ◽  
N.J. Al-Thani
Keyword(s):  
Thin Films ◽  
Thermal Stability ◽  
Hydrogen Bonding ◽  
Free Radicals ◽  
Polyvinyl Alcohol ◽  
Polyethylene Oxide ◽  
Diffusion Controlled ◽  
High Doses ◽  
Higher Doses ◽  
Very High

Thin films of a blend of 90, 75, 50 (wt/wt%) percentage of polyethylene oxide and polyvinyl alcohol were synthesized and irradiated with 5, 25, 50, 100 and 200 kGy. The presence of PVA leads to diffusion controlled mechanism where it decreases the crystallinity of PEO as restricted crystallization occurs.Low doses of 5 kGy cause crosslinking of the blends and increase the thermal stability. Higher doses up to 100 kGy cause the PEO crystallite boundaries to be erased and to blur spherulites structure; it also leads to an increase in the crystallinity. Higher doses of 200 kGy cause an increase in the hydrogen bonding where the material is more crystalline in structure and broken down which made more segments available for the hydrogen bonding. Degradation and oxidation of the blends due to the presence of free radicals in the polymer irradiated in air is noticed for blends with very high doses. Never the less, PVA in these blends protects the PEO composite from the effect of radiation.

scholarly journals Effect of Bronchial Thermoplasty on Airway Closure

2007 ◽  
Vol 1 ◽  
pp. CCRPM.S365
Author(s):  
Robert Brown ◽  
William Wizeman ◽  
Christopher Danek ◽  
Wayne Mitzner
Keyword(s):  
Experimental Studies ◽  
Airway Wall ◽  
Airway Narrowing ◽  
Bronchial Thermoplasty ◽  
Basket Catheter ◽  
Significant Impairment ◽  
High Concentrations ◽  
High Doses ◽  
Higher Doses ◽  
Very High

Background Bronchial Thermoplasty, a procedure that applies thermal energy to the airway wall has been shown to impair the ability of airway to contract in response to methacholine chloride (Mch). The technique has been advocated as an alternative treatment for asthma that may permanently limit airway narrowing. In previous experimental studies in dogs and humans, it was shown that those airways treated with bronchial thermoplasty had significant impairment of Mch responsiveness. Methods In the present study, we investigated the ability of canine airways to close completely with very high concentrations of Mch after bronchial thermoplasty. Bronchial thermoplasty was performed on dogs using the Alair System, comprising a low power RF controller and a basket catheter with four electrodes. A local atomization of Mch agonist was delivered directly to the epithelium of the same airway locations with repeated challenges. Airway size was measured with computed tomography, and closure was considered to occur in any airway where the lumen fell below the resolution of the scanner (< 1 mm). Results Our results show that, while treated airways still have the capacity to close at very high doses of Mch, this ability is seriously impaired after treatment, requiring much higher doses. Conclusions Bronchial thermoplasty as currently applied seems to simply shift the entire dose response curve toward increasing airway size. Thus, this procedure simply serves to minimize the ability of airways to narrow under any level of stimulation.

Interleukin-6 is a centrally acting endogenous pyrogen in the rat

1991 ◽  
Vol 69 (10) ◽  
pp. 1465-1469 ◽  
Author(s):  
N. J. Rothwell ◽  
N. J. Busbridge ◽  
R. A. Lefeuvre ◽  
A. J. Hardwick ◽  
J. Gauldie ◽  
...  
Keyword(s):  
Interleukin 6 ◽  
Cyclooxygenase Inhibitor ◽  
Endogenous Pyrogen ◽  
Conscious Rats ◽  
Corticotrophin Releasing Factor ◽  
High Doses ◽  
Colonic Temperature ◽  
Higher Doses ◽  
Very High ◽  
Factor Antagonist

Intracerebroventricular (i.c.v.) injection of human recombinant interleukin-6 (IL-6; 20–100 ng) caused significant increases in colonic temperature and resting oxygen consumption [Formula: see text] in conscious rats. These effects were prevented by pretreatment with a cyclooxygenase inhibitor (flurbiprofen, 1 mg/kg, i.p.) or a corticotrophin-releasing factor antagonist (α-helical CRF 9–41, 25 μg, i.c.v.). Higher doses of IL-6 (i.c.v.) caused only small changes in [Formula: see text] and temperature, and very high doses given intravenously (i.v.) (4 μg/kg) were required to stimulate these parameters. Central injection of anti-rat IL-6 antibody inhibited the effects of interleukin-1β (i.c.v.) or endotoxin injection (i.p.) on colonic temperature and [Formula: see text] in conscious rats. These data indicate that IL-6 is an important endogenous pyrogen that acts within the central nervous system.Key words: interleukin 6, fever, thermogenesis, brain, pyrogen.

Daunorubicin and Platelet Function

1981 ◽  
Vol 45 (01) ◽  
pp. 038-042 ◽  
Author(s):  
M E Pogliani ◽  
R Fantasia ◽  
G Lambertenghi-Deliliers ◽  
E Cofrancesco
Keyword(s):  
Electron Microscope ◽  
Cellular Membrane ◽  
Hemorrhagic Diathesis ◽  
Clot Retraction ◽  
Freezing And Thawing ◽  
Platelet Factor ◽  
High Doses ◽  
Very High ◽  
Platelet Functions

SummaryThe influence of Daunorubicin on some platelet functions in vitro was investigated, using different concentrations of the drug (0.01-0.02-0.04 μg/ml). Daunorubicin was shown to inhibit Collagen and Thrombin induced platelet aggregation and the intensity of inhibition depended on both drug concentration and the time of preincubation.Daunorubicin was also shown to inhibit the release reaction, the platelet prostaglandin pathway and the availability platelet factor 3; the drug at concentrations for clinical use does not damage the platelet membrane, as is the case with the freezing and thawing test, in platelet uptake of 14C-serotonin and as confirmed by the electron microscope. When very high doses (0.16 mg) of Daunorubicin are used, lysis of the platelets can be observed and this is confirmed under the electron microscope by the presence of empty platelets with fractures at the level of the cytoplasmic membrane.Finally, Daunorubicin causes irreversible inhibition of reptilase clot-retraction, even if this is less severe than with Vincristine. Working with gel-filtered platelets, it would appear that the inhibition exercised by the drug on platelet reactions is not caused through modifications in Ca++ metabolism.The authors suggest that Daunorubicin, at the dosages used clinically, induces in vitro thrombocytopathy without damaging the cellular membrane as confirmed by the electron microscope.This impairment of platelet functions could play a part in hemorrhagic diathesis observed during Daunorubicin therapy.

The effect of cation concentration on the nitrogen splitting constant of nitroxide free radicals

1990 ◽  
Vol 55 (10) ◽  
pp. 2377-2380
Author(s):  
Hamza A. Hussain
Keyword(s):  
Hydrogen Peroxide ◽  
Hydrogen Bonding ◽  
Free Radicals ◽  
Esr Spectroscopy ◽  
The Other ◽  
Tetraethylammonium Bromide ◽  
Splitting Constant ◽  
The One ◽  
Positively Charged ◽  
Two Equilibria

Nitroxide free radicals prepared from diethylamine, piperidine and pyrrolidine by oxidation with hydrogen peroxide were studied by ESR spectroscopy. The changes in the 14N splitting constant (aN) caused by the addition of KBr or tetraethylammonium bromide were measured in dependence on the concentration of the ions. For diethylamine nitroxide and piperidine nitroxide, the results are discussed in terms of two equilibria: the one, involving the anion, is associated with a gain or loss of hydrogen bonds to the nitroxide oxygen atom, the other is associated with the formation of solvent shared units involving the cation, which results in changes in the hydrogen bonding strenght. The large increase in the aN value in the case of pyrrolidine nitroxide is explained in terms of an interaction from one side of the positively charged N atom; the increase in aN in the case of diethylamine and piperidine nitroxides is explained in terms of interactions with both sides of the positively charged N atom.

scholarly journals The role of the substrate on the mechanical and thermal stability of Pd thin films during hydrogen (de)sorption

2021 ◽  
Vol 46 (5) ◽  
pp. 4137-4153
Author(s):  
Neha Verma ◽  
Rob Delhez ◽  
Niek M. van der Pers ◽  
Frans D. Tichelaar ◽  
Amarante J. Böttger
Keyword(s):  
Thin Films ◽  
Thermal Stability ◽  
Thermal Stability Of

scholarly journals Effect of Growth Temperature on the Characteristics of CsPbI3-Quantum Dots Doped Perovskite Film

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4439
Author(s):  
Shui-Yang Lien ◽  
Yu-Hao Chen ◽  
Wen-Ray Chen ◽  
Chuan-Hsi Liu ◽  
Chien-Jung Huang
Keyword(s):  
Thin Films ◽  
Thermal Stability ◽  
Quantum Dots ◽  
Quantum Dot ◽  
Growth Temperature ◽  
Electron Mobility ◽  
Surface Defects ◽  
Different Temperatures ◽  
Pb Doping ◽  
Pristine Film

In this study, adding CsPbI3 quantum dots to organic perovskite methylamine lead triiodide (CH3NH3PbI3) to form a doped perovskite film filmed by different temperatures was found to effectively reduce the formation of unsaturated metal Pb. Doping a small amount of CsPbI3 quantum dots could enhance thermal stability and improve surface defects. The electron mobility of the doped film was 2.5 times higher than the pristine film. This was a major breakthrough for inorganic quantum dot doped organic perovskite thin films.

scholarly journals Measurement of Electrical Properties of Superconducting YBCO Thin Films in the VHF Range

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3360
Author(s):  
Yakir Dahan ◽  
Eldad Holdengreber ◽  
Elichai Glassner ◽  
Oz Sorkin ◽  
Shmuel E. Schacham ◽  
...  
Keyword(s):  
Thin Films ◽  
Theoretical Model ◽  
Quality Factor ◽  
High Frequency ◽  
Unit Length ◽  
Superconducting Thin Films ◽  
Electrical Parameters ◽  
Very High Frequency ◽  
Production Constraints ◽  
Very High

A new measurement technique of electrical parameters of superconducting thin films at the Very High Frequency (VHF) range is described, based on resonators with microstrip (MS) structures. The design of an optimal resonator was achieved, based on a thorough theoretical analysis, which is required for derivation of the exact configuration of the MS. A theoretical model is presented, from which an expression for the attenuation of a MS line can be derived. Accordingly, simulations were performed, and an optimal resonator for the VHF range was designed and implemented. Production constraints of YBa2Cu3O7 (YBCO) limited the diameter of the sapphire substrate to 3″. Therefore, a meander configuration was formed to fit the long λ/4 MS line on the wafer. By measuring the complex input reflection coefficients of a λ/4 resonator, we extracted the quality factor, which is mainly affected by the dielectric and conductor attenuations. The experimental results are well fitted by the theoretical model. The dielectric attenuation was calculated using the quasi-static analysis of the MS line. An identical copper resonator was produced and measured to compare the properties of the YBCO resonator in reference to the copper one. A quality factor of ~6·105 was calculated for the YBCO resonator, three orders of magnitude larger than that of the copper resonator. The attenuation per unit length of the YBCO layer was smaller by more than five orders of magnitude than that of the copper.

scholarly journals Quantifying prescribed high dose opioids in the community and risk of overdose

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Joe Schofield ◽  
Deborah Steven ◽  
Rebecca Foster ◽  
Catriona Matheson ◽  
Alexander Baldacchino ◽  
...  
Keyword(s):  
Risk Factors ◽  
Service Improvement ◽  
High Dose ◽  
Opioid Overdose ◽  
Opioid Prescribing ◽  
Patient Level ◽  
Strong Opioid ◽  
High Doses ◽  
Strong Opioids ◽  
Very High

Abstract Background Opioid prescribing for a range of health issues is increasing globally. The risk of fatal and non-fatal overdose is increased among people prescribed strong opioids: in high doses in the context of polypharmacy (the use of multiple medications at the same time), especially with other sedatives; and among people with multiple morbidities including cardiorespiratory, hepatic and renal conditions. This study described and quantified the prescribing of strong opioids, comorbidities and other overdose risk factors among those prescribed strong opioids, and factors associated with high/very high opioid dosage in a regional health authority in Scotland as part of a wider service improvement exercise. Methods Participating practices ran searches to identify patients prescribed strong opioids and their characteristics, polypharmacy, and other overdose risk factors. Data were anonymised before being analysed at practice and patient-level. Morphine Equivalent Doses were calculated for patients based on drug/dose information and classed as Low/Medium/High/Very High. Descriptive statistics were generated on the strong opioid patient population and overdose risk factors. The relationship between the prescribing of strong opioids and practice/patient-level factors was investigated using linear and logistic regression models. Results Eighty-five percent (46/54) of GP practices participated. 12.4% (42,382/341,240) of individuals in participating practices were prescribed opioids and, of these, one third (14,079/42,382) were prescribed strong opioids. The most common comorbidities and overdose risk factors among strong opioid recipients were pain (67.2%), cardiovascular disease (43.2%), and mental health problems (39.3%). There was a positive significant relationship between level of social deprivation among practice caseload and level of strong opioid prescribing (p < 0.001). People prescribed strong opioids tended to be older (mean 59.7 years) and female (8638, 61.4%) and, among a subset of patients, age, gender and opioid drug class were significantly associated with prescribing of High/Very High doses. Conclusions Our findings have identified a large population at potential risk of prescription opioid overdose. There is a need to explore pragmatic models of tailored interventions which may reduce the risk of overdose within this group and clinical practice may need to be tightened to minimise overdose risk for individuals prescribed high dose opioids.

EFFECTS OF ECDYSONES, JUVENILE HORMONE ANALOGS, AND 6-OXOOCTANOIC ACID ON THE DEVELOPMENT OF THE MOSQUITO, CULEX TARSALIS (DIPTERA: CULICIDAE)

1974 ◽  
Vol 106 (1) ◽  
pp. 79-85 ◽  
Author(s):  
P. I. Ittycheriah ◽  
M. S. Quraishi ◽  
E. P. Marks
Keyword(s):  
Juvenile Hormone ◽  
Topical Treatment ◽  
Adult Emergence ◽  
Fourth Instar ◽  
Culex Tarsalis ◽  
Juvenile Hormone Analog ◽  
Hormone Analog ◽  
High Doses ◽  
Hormone Analogs ◽  
Very High

AbstractEggs, larvae, and pupae of Culex tarsalis Coquillett were treated with ecdysones, juvenile hormone analogs, and 6-oxooctanoic acid. Effects of these agents on mortality, induction of supernumerary stages, and adult emergence were determined. Topical treatment of eggs with CRD9499 (a juvenile hormone analog), β-ecdysone, and 22-isoecdysone caused a reduction in adult emergence. Treatment of fourth-instar larvae with these chemicals not only induced mortality but also caused the formation of supernumerary intermediate stages. Larvae of C. tarsalis were very susceptible to CRD9499, but pupae were resistant. The ecdysones caused some mortality but only at very high doses and would thus be of little use as larvicides. 6-Oxooctanoic acid caused high rates of mortality at 0.001 M concentrations.

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