排序方式: 共有17条查询结果,搜索用时 15 毫秒
1.
Krivenko Pavel Vaičiukynienė Danutė Kantautas Aras Vaitkevičius Vitoldas Šerelis Evaldas 《Journal of Thermal Analysis and Calorimetry》2019,138(2):879-887
Journal of Thermal Analysis and Calorimetry - Generally, the early strength of hardened Portland cement paste is controlled, by changing the mineral composition of clinker and grinding fineness. By... 相似文献
2.
Alexandru Cecal Dan Colisnic Karin Popa Andrei O. Paraschivescu Nicolae Bilba Danut G. Cozma 《Central European Journal of Chemistry》2004,2(1):247-253
This paper reports a study of the decomposition of water by gamma radiolysis in the presence of zeolites ZSM-5, SAPO-5, and
MOR. The irradiation is performed using 60Co as a source with 1.12×1015 Bq activity at a 8.3 kGy/h dose rate. The stable products of radiolysis as well as the other chemical species are measured
by mass spectrometry. The calculated radiation yield (GH
2) generally decreases in the order: H-ZSM-5>Na-ZSM-5>H-SAPO-5>MOR under the given experimental conditions; the yield is higher
in the presence of these catalysts than in their absence. 相似文献
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Ionel Danut Savu Sorin Vasile Savu Nicusor Alin Sirbu 《Journal of Thermal Analysis and Calorimetry》2014,115(2):1427-1437
Laser marking is based on the laser heating of the subjected material, the heating being below the melting temperature or thermal degradation starting point. Within and nearby the mark, the material is chemically, physically and mechanically affected. This means that the main characteristics are changing in such a way that the material is ageing. Thermal and mechanical analysis can be used to determine the modification of the material, which is important and necessary to know for predicting its use lifetime. This paper investigates the physical and mechanical modification of the polymer HDPE100, when laser marking is applied. Burst stress, elongation and relaxation modulus were determined for the base material, within the heat affected zone and within the laser burned mark. Information on the crystallization rate and on the elongation viscosity is also reported. According to the results, the polyethylene has very fast crystallization and that affects the marking process if lower than appropriate maintaining during heating process is applied. It becomes stabile after 0.23 min, when it is tested at 103 °C. The elongation viscosity was analysed and values of 105 Pa s were recorded for 10 s, which is a usual time of applying pressure. The performed analysis revealed about 10 % difference between the relaxation modulus of the irradiated and non-irradiated HDPE. 相似文献
5.
D. Bontea C. Mita D. Humelnicu 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):305-311
Summary Three
silylcellulosic derivatives with different substitution degree were examined as
sorbents for uranyl ions. The adsorption rate and capacity of cellulose and
modified cellulose were investigated in aqueous media, at various pH and
temperature values. The polymer - metal complexes of UO22+
were characterized by infrared and electronic spectra, and thermogravimetry.
The thermal behavior of cellulose (C), trimethylsilyl - cellulose (tmsc, SD=
2.85) and triphenylsilyl - cellulose (TPSC1, SD=2.89 and TPSC2, SD
=2.70) and their complexes with
uranyl ions in atmospheric air has been studied between room temperature and
600 °C. The Coats-Redfern method was applied to estimate the kinetic
parameters. The results revealed that the complexation of C and TMSC with UO22+
increases the thermal stability.</p>
</p> 相似文献
6.
Danutė Krapavickaitė 《Acta Appl Math》2007,96(1-3):339-347
A model-based estimator of a finite population total using a tobit model for a study variable is proposed. Formulas for its
approximate bias, approximate variance and an estimator of the variance are given. Simulation results show situations of possible
effective applications of the model.
The study is supported by the Nordplus Neighbour program of the Nordic Council of Ministers. 相似文献
7.
Vasile Danut Cojocaru 《Journal of magnetism and magnetic materials》2012,324(9):1664-1669
The main aim of the present work is to study the synthesis and stability of soft-magnetic nanostructured materials under high pressure-high temperature conditions. HITPERM alloy powders were prepared by high-energy ball-milling. The as-milled alloys consist of an iron-based nanocrystalline solid solution. The evolution of crystallinity and grain-size during the ball-milling process and investigations under external pressure up to 3 GPa for temperatures up to 1200 °C were evaluated using synchrotron radiation X-ray diffraction. 相似文献
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Ruxandra Mihailovici Alexandra Croitoriu Florin Nedeff Valentin Nedeff Lacramioara Ochiuz Decebal Vasincu Ovidiu Popa Maricel Agop Andreea Moraru Danut Costin Marcel Costuleanu Liliana Verestiuc 《Molecules (Basel, Switzerland)》2022,27(14)
Drug delivery to the anterior or posterior segments of the eye is a major challenge due to the protection barriers and removal mechanisms associated with the unique anatomical and physiological nature of the ocular system. The paper presents the preparation and characterization of drug-loaded polymeric particulated systems based on pre-emulsion coated with biodegradable polymers. Low molecular weight biopolymers (chitosan, sodium hyaluronate and heparin sodium) were selected due to their ability to attach polymer chains to the surface of the growing system. The particulated systems with dimensions of 190–270 nm and a zeta potential varying from −37 mV to +24 mV depending on the biopolymer charges have been obtained. Current studies show that particles release drugs (dexamethasone/pilocarpine/bevacizumab) in a safe and effective manner, maintaining therapeutic concentration for a longer period of time. An extensive modeling study was performed in order to evaluate the drug release profile from the prepared systems. In a multifractal paradigm of motion, nonlinear behaviors of a drug delivery system are analyzed in the fractal theory of motion, in order to correlate the drug structure with polymer. Then, the functionality of a SL(2R) type “hidden symmetry” implies, through a Riccati type gauge, different “synchronization modes” (period doubling, damped oscillations, quasi-periodicity and intermittency) during the drug release process. Among these, a special mode of Kink type, better reflects the empirical data. The fractal study indicated more complex interactions between the angiogenesis inhibitor Bevacizumab and polymeric structure. 相似文献
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