A New Hafnium-Beryllium System Prioduced by Ion Implantation and Annealing Techniques

1983 ◽  
Vol 27 ◽  
Author(s):  
J.C. Soares ◽  
A.A. Melo ◽  
M.F. DA Silva ◽  
E.J. Alves ◽  
K. Freitag ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Single Crystals ◽  
Room Temperature ◽  
Low Dose ◽  
Correlation Method ◽  
High Dose ◽  
Tetrahedral Sites ◽  
Time Differential ◽  
Before And After ◽  
Beryllium Foil

ABSTRACTLow and high dose hafnium imolanted beryllium samoles have been prepared at room temperature by ion implantation of beryllium commercial foils and single crystals. These samples have been studied before and after annealing with the time differential perturbed angular correlation method (TDPAC) and with Rutherford backscattering and channeling techniques. A new metastable system has been discovered in TDPAC-measurements in a low dose hafnium implanted beryllium foil annealed at 500°C. Channeling measurements show that the hafnium atoms after annealing, are in the regular tetrahedral sites but dislocated from the previous position occupied after implantation. The formation of this system is connected with the redistribution of oxygen in a thin layer under the surface. This effect does not take place precisely at the same temperature in foils and in single crystals.

Benefit/Risk Profile of Combined Antiplatelet Therapy with Ticlopidine and Aspirin

1991 ◽  
Vol 65 (05) ◽  
pp. 504-510 ◽  
Author(s):  
Raffaele De Caterina ◽  
Rosa Sicari ◽  
Walter Bernini ◽  
Guido Lazzerini ◽  
Giuliana Buti Strata ◽  
...  
Keyword(s):  
Platelet Function ◽  
Low Dose ◽  
Bleeding Time ◽  
Ex Vivo ◽  
Stable Coronary Artery Disease ◽  
High Dose ◽  
Single Drug ◽  
Before And After ◽  
Serum Thromboxane ◽  
Artery Disease

SummaryTiclopidine (T) and aspirin (ASA) are two antiplatelet drugs both capable of prolonging bleeding time (BT), with a different mechanism of action. A synergism in BT prolongation has been reported and is currently considered an argument for not recommending their combination. However, a profound suppression of platelet function might be a desirable counterpart of a marked prolongation of BT, with a possible use in selected clinical situations. We therefore studied ex vivo platelet function (aggregation by ADP 0.5-1-2.5 μM; adrenaline 0.75-2.5 μM; collagen 1.5-150 μg/ml; arachidonic acid 1 mM; PAF 1 μM; adrenaline 0.17 μM + ADP 0.62 μM; serum thromboxane ([TX]B2 generation) and BT (Mielke) in 6 patients with stable coronary artery disease receiving such combination. Patients underwent sequential laboratory evaluations at baseline, after 7 days of T 250 mg b.i.d., before and after the intravenous administration of ASA 500 mg, respectively, and, finally, after a minimum of 7 days of sole ASA oral administration (50 mg/day). The experimental design, therefore, allowed a comparison of T and ASA effects (2nd and 4th evaluation), and an assessment of the combination effect (3rd evaluation). Platelet aggregation in response to all doses of ADP was depressed more by T than by ASA. Conversely, responses to adrenaline, and arachidonate were affected more by ASA than by T. For all other agents, differences were not significant. T + ASA combination was more effective (p <0.05) than either treatment alone in depressing responses to high-dose collagen (% over control, mean ± SEM: T: 95 ± 3; ASA: 96 ± 5; T + ASA: 89 ± 4). Serum TXB2 (basal, ng/ml: 380 ± 54) did not change with T (372 ± 36), dropped to <1 ng/ml on ASA injection and slightly re-increased to 9.1 ± 3.1 ng/ml on oral low-dose ASA. BT (basal 7.4 ± 0.6 min) was affected similarly by T (9.2 ± 0.8) or ASA (9.7 ± 0.9) alone, but increased to 15.0 ± 0.7 min on combination treatment (106% increase over control). Thus, the strong synergism in BT prolongation by ASA-T combination has a counterpart in the inhibition of platelet function in response to strong stimuli such as high-dose collagen, not otherwise affected significantly by single-drug treatment. This effect is a possible rationale for the clinical evaluation of T + ASA combination.

Generation of Defects and Strain by Ion Implantation in Ge (100) Single Crystals, and in Pseudomorphic GexSi1-x Films Grown on Si (100)

1992 ◽  
Vol 262 ◽  
Author(s):  
D. Y. C. Lie ◽  
A. Vantomme ◽  
F. Eisen ◽  
M. -A. Nicolet ◽  
V. Arbet-Engels ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Single Crystals ◽  
Room Temperature ◽  
Defect Concentration ◽  
Double Crystal ◽  
X Ray ◽  
Positive Strain ◽  
Independent Coefficient ◽  
The Relationship ◽  
Si Ion Implantation

ABSTRACTWe have studied the damage and strain produced in Ge (100) single crystals by implantation of various doses of 300 keV 28Si ions at room temperature. The analyzing tools were x-ray double-crystal diffractometry, and MeV 4He channeling spectrometry. The damage induced by implantation produces positive strain in Ge (100). The maximum perpendicular strain and maximum defect concentration rise nonlinearly with increasing dose. These quantities are linearly related with a dose-independent coefficient of ∼ 0.013 for Ge (100) single crystals implanted at room temperature. The results are compared with those available for Si (100) self-implantation. We have also monitored the strain and defects generated in pseudomorphic Ge0.1Si0.9/Si (100) films induced by room temperature 28Si ion implantation. It is found that the relationship between the strain and defect concentration induced by ion implantation is no longer a simple linear one.

Effect of insulin on regional vascular resistances in conscious rats

1996 ◽  
Vol 270 (2) ◽  
pp. R450-R455
Author(s):  
E. Qadir ◽  
J. P. Porter
Keyword(s):  
Skeletal Muscle ◽  
Arterial Pressure ◽  
Low Dose ◽  
Chronic Administration ◽  
High Dose ◽  
Ganglionic Blockade ◽  
Conscious Rats ◽  
Before And After ◽  
Vascular Beds ◽  
Renal Vascular

In the rat, but not in humans and other mammals, chronic administration of insulin produces hypertension. The present aim was to determine the effect of acute insulin infusion on regional vascular resistances and to determine the neurogenic contribution to the response. Conscious rats were infused with insulin (2 or 6 mU/min) before and after ganglionic blockade with chlorisondamine (5 mg/kg). The low dose of insulin produced an increase in arterial pressure and hindquarter vascular resistance; the high dose produced a gradual decrease in arterial pressure and renal resistance. After ganglionic blockade, the hindquarter vasoconstriction produced by the low dose was abolished. The high dose of insulin produced both hindquarter and renal vasodilation. Thus the low dose of insulin had a selective neurogenic vasoconstrictor effect in rat skeletal muscle vascular beds. With higher doses, direct vasodilatory effects in both skeletal muscle and renal vascular beds appeared. This greater sensitivity of the sympathoexcitatory effects of insulin in rats may explain the ability of chronic insulin infusions to increase blood pressure in this species.

Efficacy of Low-Dose versus High-Dose Continuous Cyclic Azithromycin Therapy for Preventing Acute Exacerbations of COPD

Respiration ◽  
2021 ◽  
pp. 1-8
Author(s):  
Xavier Pomares ◽  
Concepción Montón ◽  
Daniel Huertas ◽  
Alicia Marín ◽  
Ester Cuevas ◽  
...  
Keyword(s):  
Dose Group ◽  
Low Dose ◽  
Therapy Group ◽  
High Dose ◽  
University Hospitals ◽  
Copd Exacerbations ◽  
Before And After ◽  
Dosing Regimens ◽  
Maximal Medical Therapy ◽  
Severe Copd

<b><i>Background:</i></b> Long-term azithromycin therapy significantly reduces the frequency of COPD exacerbations (ECOPD). However, previous studies have used different dosing regimens, and the efficacy of these regimens has not been compared. <b><i>Objective:</i></b> Compare the efficacy of low-dose with high-dose continuous cyclic azithromycin (CC-A) in severe COPD. <b><i>Methods:</i></b> Patients with severe COPD and repeated exacerbations (ECOPD ≥4 or ≥3 with at least 1 hospital admission in the previous year) were prospectively recruited (January 2017 to December 2019) as a multicenter cohort (from 3 university hospitals in the Barcelona area) and treated with low-dose CC-A: 250 mg 3 times per week (250-CC-A group). This cohort was compared with a historical (January 2007 to December 2013) single-center cohort of severe COPD with frequent ECOPD treated with high-dose CC-A: 500 mg 3 times per week (500-CC-A group). To assess differences in ECOPD prevention according to the administration of low-dose or high-dose CC-A, moderate-to-severe ECOPD was evaluated during the 12-month period before and after starting CC-A therapy. <b><i>Results:</i></b> Fifty-eight patients with severe COPD were evaluated: 37 in the low-dose group and 21 in the high-dose group. The 250-CC-A therapy group achieved a mean reduction in moderate-to-severe ECOPD of 65.6% at 12 months after starting CC-A therapy (with a 61.5% reduction in hospitalizations), while the 500-CC-A group achieved a reduction of 60.5% (with a 44.8% reduction in hospitalizations). No significant differences between 250-CC-A and 500-CC-A dosages were observed in the mean annual reduction of moderate-to-severe ECOPD (<i>p</i> = 0.55) or hospitalizations (<i>p</i> = 0.07) with respect to the year prior to starting CC-A. <b><i>Conclusions:</i></b> Low-dose 250-CC-A therapy over a 1-year period is similar to high-dose 500-CC-A in reducing exacerbation frequency in severe COPD patients with frequent ECOPD despite maximal medical therapy.

Direct Observation of Intermixing in GAAS/AIAS Multilayers After Very Low-Dose Ion-Implantation

1989 ◽  
Vol 157 ◽  
Author(s):  
M. Bode ◽  
A. Ourmazd ◽  
J.A. Rentschler ◽  
M. Hong ◽  
L.C. Feldman ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Monte Carlo ◽  
Ion Implantation ◽  
Monte Carlo Simulations ◽  
Low Dose ◽  
Atomic Plane ◽  
Lattice Imaging ◽  
Energetic Ions ◽  
Before And After ◽  
Composition Profiles

ABSTRACTWe combine chemical lattice imaging and digital vector pattern recognition to study quantitatively, kinetic intermixing in GaAs/AlAs multilayers. We thus obtain, with atomic plane resolution and near-atomic sensitivity, composition profiles across each interface of a multilayer stack before and after ion-implantation. Our results show significant intermixing even when only one 320 keV Ga+ ion is implanted at 77 K into each 2000 A2 area of the interface. This corresponds to an incident ion dose of 5×l012/cm2.The intermixing is not uniform along the interface. At each interface, we observe more intensely intermixed regions, whose widths correspond to those created by the damage track of a single implanted ion, as expected from Monte-Carlo simulations. It thus appears that we can directly image intermixing due to single energetic ions implanted into the multilayered GaAs/AlAs structure.

Comparison of Antileukotrienes and Antihistamines in the Treatment of Allergic Rhinitis

2007 ◽  
Vol 21 (4) ◽  
pp. 439-443 ◽  
Author(s):  
Ching-Yin Ho ◽  
Ching-Ting Tan
Keyword(s):  
Allergic Rhinitis ◽  
Low Dose ◽  
Treated Group ◽  
Nasal Symptom ◽  
Controlled Study ◽  
Control Group ◽  
High Dose ◽  
Nasal Resistance ◽  
Before And After ◽  
Nasal Secretions

Background The aim of this study was to compare the effect of antileukotriene (anti-LT), antihistamine, and a combination of anti-LT and antihistamine on the symptoms and nasal resistance in allergic rhinitis patients. Methods We performed a placebo-controlled study, with 120 persistent, moderate to severe allergic rhinitis patients randomly selected to receive the different treatments for 4 weeks: no treatment, 10 mg of cetirizine once per day, 20 mg of zafirlukast once per day, 20 mg of zafirlukast twice per day, a combination of 20 mg of zafirlukast and 10 mg of cetirizine once per day, or a combination of 20 mg of zafirlukast twice per day and 10 mg cetirizine once per day. The nasal secretion nitric oxide (NO) concentration, nasal symptom score, and nasal resistance were measured before and after treatment. Results Total symptom scores improved in each treated group compared with the control group (p < 0.05). Nasal obstruction significantly improved in the anti-LT-treated groups (p < 0.05). High-dose anti-LT or the combination of low-dose anti-LT and antihistamine significantly improved allergy symptoms compared with no treatment, low-dose anti-LT, or antihistamine alone (p < 0.05). Furthermore, anti-LT decreased NO concentration in nasal secretions (p < 0.05), regardless of the dose administered. Conclusion These results suggest that high-dose anti-LT alone or the combination of low-dose anti-LY and antihistamine can effectively treat allergic rhinitis.

Aluminum Ion Implantation in Silicon Carbide at High Temperature of Target

1992 ◽  
Vol 279 ◽  
Author(s):  
Alexander V. Suvorov ◽  
D. A. Plotkin ◽  
V. N. Makarov ◽  
V. N. Svetlov
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Single Crystals ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Epitaxial Films ◽  
High Dose ◽  
Layer Surface ◽  
Considerable Part ◽  
Before And After

ABSTRACTSingle crystals and epitaxial films of SiC - 4H and 6H were implanted at an energy of 40 and 90 KeV by ions of Al at various temperatures and high dose.The implanted layers were studied before and after annealing by Raman scattering, Auger electron spectroscopy and SIMS. Results of this investigation show intensive graphitization of the implanted layer surface, the formation of great associations of defects in the implanted layer and shallow defects. It was found that recrystallization of the implanted layer pushes out a considerable part of aluminum atoms. The nature of the processes in silicon carbide during implantation and annealing is discussed.

Unimpaired thermogenic response to noradrenaline in genetic (ob/ob) and hypothalamic (MSG) obese mice

1984 ◽  
Vol 4 (4) ◽  
pp. 343-349 ◽  
Author(s):  
A. G. Duloo ◽  
D. S. Miller
Keyword(s):  
Metabolic Rate ◽  
Room Temperature ◽  
Low Dose ◽  
Monosodium Glutamate ◽  
Whole Body ◽  
High Dose ◽  
Obese Mice ◽  
Subcutaneous Injections ◽  
Noradrenaline Administration ◽  
Thermogenic Response

The thermogenic response to noradrenaline administration was investigated at 25° in two models of obese mice (genetic ob/ob obesity of the ‘QEC’ strain and monosodium-glutamate-induced obesity) and in their respective lean littermates. Subcutaneous injections of a low dose of noradrenaline (I00 μg/kg body wt.) eJevated metabolic rate by about 3096 in both obese models but not in their respective lean counterparts. In contrast, the increase in metabolic rate after injections of a high dose of noradrenaline (600 μg/kg body wt.) was of a similar magnitude in both lean and obese animals: metabolic rate was increased by 70–80%. These results indicate that the overall whole body thermogenic capacity is unimpaired at room temperature in this ‘QEC’ strain of ob/ob mice and in the hypothalamic damaged obese mice. Obesity in these models is therefore not associated with a reduced ability to respond to noradrenaline but could rather be due to a failure to release noradrenaline.

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