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51.
Alexandru Gheorghe Ai Matsuno Oliver Reiser 《Advanced Synthesis \u0026amp; Catalysis》2006,348(9):1016-1020
TEMPO was readily grafted by copper(I)‐catalyzed azide‐alkyne cycloaddition onto polystyrene. Starting with commercially available Merrifield resin (4.3 mmol/ g) almost quantitative loading of TEMPO onto the polymer was achieved (≥ 4 mmol/ g). The so obtained PS‐CLICK‐TEMPO allowed the oxidation of alcohols to aldehydes with bleach or molecular oxygen as the terminal oxidant with high yields and selectivity in multiple cycles without loss of activity. 相似文献
52.
Sowlati T. Rozenblit D. Pullela R. Damgaard M. McCarthy E. Dongsoo Koh Ripley D. Balteanu F. Gheorghe I. 《Solid-State Circuits, IEEE Journal of》2004,39(12):2179-2189
An enhanced data-rates for GSM evolution (EDGE) transmitter using a nonlinear GSM-type PA is presented. It is based on a novel polar loop architecture that employs separate feedback control of the amplitude and the phase of the output signal. With this approach, the problems with AM-to-PM as well as AM-to-AM of the nonlinear PA are essentially eliminated. In addition, this architecture allows for a large dynamic output power control range, as required by the GSM specification. The transmitter uses a standard I/Q interface and does not require the extraction of amplitude and phase modulation in the digital domain. The dual feedback loop ensures robust performance even under voltage-standing wave ratio variations without using an isolator. No external PA filtering is required to meet the transmitter noise in the receive band. The EDGE spectral mask is met with an rms error vector magnitude of <3% at 29 dBm at the antenna, corresponding to 2 dB above nominal maximum output power. There is no mode change between GMSK and EDGE, and the transmitter operates seamlessly in multislot Enhanced General Packet Radio Service. The polar modulation transmitter meets or exceeds the GSM-type approval requirements for both EDGE and GMSK in quad band (850/900/1800/1900 MHz). 相似文献
53.
A general fuzzy multicriteria decision aid method for conceptual design is proposed. It is used for selecting the best compromise alternative, among a finite set of design concepts, considering environmental and economic performance. At the conceptual design phase most of the environmental impact is committed, whereas at that stage the design concepts are imprecisely defined and should be selected based on multiple, often conflicting criteria. Three vacuum cleaners, using different design principles for the dust storage, are analyzed. The best compromise design alternative is selected, considering trade offs between end-of-life profit and environmental criteria. 相似文献
54.
Maria Elena Zarif Saa Alexandra Yehia Bogdan Bi Veronica Stulu Sorin Vizireanu Gheorghe Dinescu Alina Maria Holban Florica Marinescu Ecaterina Andronescu Alexandru Mihai Grumezescu Alexandra Ctlina Bîrc Alexandru Titus Farcaiu 《International journal of molecular sciences》2021,22(23)
Despite the technological progress of the last decade, dental caries is still the most frequent oral health threat in children and adults alike. Such a condition has multiple triggers and is caused mainly by enamel degradation under the acidic attack of microbial cells, which compose the biofilm of the dental plaque. The biofilm of the dental plaque is a multispecific microbial consortium that periodically develops on mammalian teeth. It can be partially removed through mechanical forces by individual brushing or in specialized oral care facilities. Inhibition of microbial attachment and biofilm formation, as well as methods to strengthen dental enamel to microbial attack, represent the key factors in caries prevention. The purpose of this study was to elaborate a cold plasma-based method in order to modulate microbial attachment and biofilm formation and to improve the retention of fluoride (F−) in an enamel-like hydroxyapatite (HAP) model sample. Our results showed improved F retention in the HAP model, which correlated with an increased antimicrobial and antibiofilm effect. The obtained cold plasma with a dual effect exhibited through biofilm modulation and enamel strengthening through fluoridation is intended for dental application, such as preventing and treating dental caries and enamel deterioration. 相似文献
55.
Perozziello G La Rocca R Cojoc G Liberale C Malara N Simone G Candeloro P Anichini A Tirinato L Gentile F Coluccio ML Carbone E Di Fabrizio E 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(18):2886-2894
This study aims to adoptively reduce the major histocompatibility complex class I (MHC-I) molecule surface expression of cancer cells by exposure to microfluid shear stress and a monoclonal antibody. A microfluidic system is developed and tumor cells are injected at different flow rates. The bottom surface of the microfluidic system is biofunctionalized with antibodies (W6/32) specific for the MHC-I molecules with a simple method based on microfluidic protocols. The antibodies promote binding between the bottom surface and the MHC-I molecules on the tumor cell membrane. The cells are injected at an optimized flow rate, then roll on the bottom surface and are subjected to shear stress. The stress is localized and enhanced on the part of the membrane where MHC-I proteins are expressed, since they stick to the antibodies of the system. The localized stress allows a stripping effect and consequent reduction of the MHC-I expression. It is shown that it is possible to specifically treat and recover eukaryotic cells without damaging the biological samples. MHC-I molecule expression on treated and control cell surfaces is measured on tumor and healthy cells. After the cell rolling treatment a clear reduction of MHC-I levels on the tumor cell membrane is observed, whereas no changes are observed on healthy cells (monocytes). The MHC-I reduction is investigated and the possibility that the developed system could induce a loss of these molecules from the tumor cell surface is addressed. The percentage of living tumor cells (viability) that remain after the treatment is measured. The changes induced by the microfluidic system are analyzed by fluorescence-activated cell sorting and confocal microscopy. Cytotoxicity tests show a relevant increased susceptibility of natural killer (NK) cells on microchip-treated tumor cells. 相似文献
56.
Gheorghe Batrinescu Roxana-Elena Scutariu Gheorghe Nechifor Ioana-Alexandra Ionescu Vasile-Ion Iancu 《应用聚合物科学杂志》2021,138(12):50055
Tangential flow filtration of the collagen protein solutions with a molecular weight 12, 14, and 24 kDa is investigated using flat sheet membranes. The effects of tangential ultrafiltration (UF) on the permeate properties using two regenerated celluloses (RCs) and two polyethersulfone (PES) membranes with molecular weight cut-off (MWCO) of 5 and 10 kDa are reported. The permeate and concentrate obtained in the UF experiments are characterized from a physical–chemical point of view by determining the temperature, pH, electrical conductivity, nitrogen content, and protein concentration. In addition, the experimental data are modeled using Hermia's model. The UF experiments demonstrated that permeate flux declined with increasing molecular weight of collagen at constant concentration (1%). Regardless of the molecular weight of collagen, the rejections decrease in the following order: PES 5 kDa > RC5kDa > RC10kDa > PES10kDa. In case of membrane with higher MWCO, the clogging phenomenon is mainly due to the blockage of the internal pores of the membrane than the formation of a polarization layer. Morphologies and characteristics of the membranes are characterized using scanning electron microscopy. 相似文献
57.
Simona Gabriela Muntean Oana Paska Sergiu Coseri Georgeta Maria Simu Maria Elena Grad Gheorghe Ilia 《应用聚合物科学杂志》2013,127(6):4409-4421
Functionalized polymeric microbeads were investigated as adsorbent for the removal of three direct dyes from aqueous solutions. The effects of different experimental parameters, such as initial dye concentration, temperature, and solution pH on the adsorption process were investigated. The adsorption process can be conducted with very good result at normal working conditions: neutral pH and normal temperature. The maximum percentage removal obtained was 99.11% for the symmetrical disazo dye, 90.14% for asymmetrical disazo dye, and 98.53% for trisazo dye. The adsorption kinetics followed the pseudo‐second‐order equation for all three investigated dyes in all working conditions. The experimental data were fitted to Langmuir, Freundlich, Sips, and Redlich–Peterson isotherm models, and the best fit was obtained with Sips model. Thermodynamic parameters (ΔH°, ΔS°, and ΔG°) revealed that dye adsorption is an endothermic and spontaneous process. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
58.
Maria Poroch-SeritanSonia Gutt Gheorghe GuttIgor Cretescu Corneliu Cojocaru Traian Severin 《Chemical Engineering Research and Design》2011,89(2):136-147
The central composite experimental design and response surface methodology have been employed for statistical modeling and analysis of the results dealing with nickel electroplating process. The empirical models developed in terms of design variables (current density J (A/dm2), temperature T (°C) and pH) have been found statistically adequate to describe the process responses, i.e. cathode efficiency Y (%), coating thickness U (μm), brightness V (%) and hardness W (HV). The graphical representations consisted of 2D contour plots and 3D surface plots have been used for exploring and analysis of response surfaces in order to identify the main, quadratic and interaction effects. The multi-response optimization of nickel electroplating process has been carried out by means of desirability function approach. To this end, a genetic algorithm has been used for mathematical optimization of the multi-response problem. The optimization algorithm has conducted to a set of equivalent solutions named Pareto optimal set. The confirmation runs have been employed in order to make a decision about the optimal solution approved by experiment. Thus, the optimum conditions of nickel electroplating has been defined in this work as J* = 5.35 (A/dm2), T* = 33.44 (°C) and pH* = 6.22 and respectively the responses confirmed by experiment were Y = 79.12 ± 0.18 (%), U = 52.77 ± 0.48 (μm), V = 26.12 ± 0.45 (%) and W = 371.6 ± 1.77 (HV). In such conditions the quality of nickel electroplating deposit was the best one in accordance with experimental results. 相似文献
59.
Lavinia Macarie Nicoleta Plesu Smaranda Iliescu Adriana Popa Gheorghe Ilia 《应用聚合物科学杂志》2011,119(3):1820-1826
UV‐cured nanocomposite films were prepared from acrylic monomer and two types of nanomaterial: zirconium vinylphosphonate and zirconia, in the presence of a photoinitiator. The films were characterized by FTIR, SEM, and AFM. FTIR spectra showed the disappearance of band assigned to the CC group both of monomer and zirconium vinylphosphonate by polymerization and the presence of the phosphonate group in polymer. The influence of zirconium vinylphosphonate and zirconia content on thermooxidative degradation of polymeric films was studied by thermogravimetry. SEM and AFM images showed that nanomaterials are dispersed in polymer matrix with no macroscopic phase separation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
60.
Anca Dumbrava Daniela Berger Cristian Matei Marius Daniel Radu Emma Gheorghe 《Ceramics International》2018,44(5):4931-4936
Zinc oxide was deposited onto calcium carbonate precipitated using a template of polysaccharides from Ulva lactuca green seaweeds (Black Sea). The resulted composite material was characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, UV–vis and FTIR spectroscopy. The therapeutic effect of prepared composite material was assessed in vivo as a topical application for the burns treatment and compared with that of ZnO. An increased antioxidant activity by combining zinc oxide with calcium carbonate capped with polysaccharides from green seaweeds extract in a composite material was demonstrated. 相似文献