Intelligent feedback release systems and the application to neuron network model research

Intelligent feedback release systems, consisting of radiation-prepared porous polycarbonate film or silicone chip and radiation crosslinked stimuli-sensitive hydrogels with immobilized enzymes as a sensor–actuator gate were constructed. Those systems showed various signal responsive substance release functions, and selective signal transfer functions. The application of those integrated intelligent systems as neural network model was investigated.     

Uranium-bearing francolites present in organic-rich limestones of NW Greece: a preliminary study using synchrotron radiation and fission track techniques

Synchrotron radiation techniques (μ-XRF and μ-XANES) were applied to the study of organic-rich phosphatized limestones of NW Greece (Epirus). The results revealed uranium accumulation in areas of the material containing, among others, carbonate apatite (francolite) and organic matter. The UL ₃-edge of μ-XANES spectra showed that uranium was present in tetravalent form. U-bearing francolite crystals were separated from the rock and characterized by Raman spectroscopy and microprobe. The analysis of the crystals also indicated the presence of sodium and sulfur. The uranium presence in the crystals was also visualized, after neutron irradiation and etching, by the observation of the fission tracks.

     

YVO4:Eu3+ functionalized porous silica submicrospheres as delivery carriers of doxorubicin

Porous silica microspheres were fabricated by a facile surface-protected etching strategy. Polyvinylpyrrolidone (PVP) was used as a protecting polymer absorbed on the surface of silica microspheres and NaOH was employed as an etching agent. Owing to the protective action of PVP and inhomogeneous etching, mesopores were created in the silica microspheres. Then, based on the Pechini-type sol-gel and impregnating process, YVO(4):Eu(3+) nanocrystals were integrated into the channels to form highly luminescent YVO(4):Eu(3+)@SiO(2) composite microspheres. The biocompatibility tests on L929 fibroblast cells using MTT assay reveal low cytotoxicity of the system. Owing to the large interior space and electrostatic interaction, the porous microspheres show a relatively high loading capacity (438 mg DOX/YVO(4):Eu(3+)@SiO(2) g) and encapsulation efficiency (87.6%) for the anti-cancer drug doxorubicin hydrochloride (DOX). The drug release behavior and cytotoxic effect against human cervical carcinoma cells (HeLa cells) of the DOX-loaded YVO(4):Eu(3+)@SiO(2) carriers were investigated in vitro. It was found that the carriers present a highly pH-dependent drug release behavior due to electrostatic interaction between the silica surface and DOX molecules. The drug release rate became greater at low pH owing to the increased electrostatic repulsion. The DOX-loaded carriers demonstrate a similar or even greater anti-cancer activity with respect to the free DOX against HeLa cells. Furthermore, the PL intensity of the microspheres shows correlation with the cumulative release of DOX. These results suggest that the composite can potentially act as a multifunctional drug carrier system with luminescent tagging and pH-controlled release properties.     

Radiation curing of intelligent coating for controlled release and permeation

Intelligent membranes for pH and temperature-responsive drug releases were developed by coating and curing of polymer-drug composite film with electrolyte or N-isopropyl acrylamide curable mixture. It was proved that those intelligent membranes showed the stimule-sensitive and responsive release functions and could be produced efficiently by radiation curing prosessing with a conveyer system.     

Micromachining of crosslinked PTFE by direct photo-etching using synchrotron radiation

Micromachining of crosslinked PTFE (polytetrafluoroethylene) using synchrotron radiation direct photo-etching method has been demonstrated. High aspect-ratio microfabrication was carried out. The etching rate of crosslinked PTFE was higher than that of non-crosslinked PTFE. Through the etching rate measurements of various samples, it was found that synchrotron radiation etching rate of crosslinked PTFE only depends on the degree of crosslinking, neither molecular weight nor crystallinity. The effect of molecular motion on etching process was discussed from temperature dependence data on etching rate. Furthermore, the surface region of synchrotron radiation irradiated sample was investigated by Fourier transform infrared spectroscopy and the experimental result showed that the modification induced by synchrotron radiation proceeded before desorption.     

Fabrication of Mesoporous SiO2@CaSiO3 Hollow Spheres as Carriers for pH-sensitive Drug Delivery

Hollow mesoporous silica(HM-SiO₂) was prepared by the improved stober method. On this basis, HM-SiO₂ was dispersed in an alkaline solution for surface etching. Meanwhile, calcium source was introduced to combine with on the surface to form a CaSiO₃shell layer and an unprecedent SiO₂@CaSiO₃sphere with a hollow double-shell structure was obtained. The as-synthesized SiO₂@CaSiO₃ was characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), N₂-BET, IR and UV-Vis techniques, and its sustained release capacity of doxorubicin(DOX) loading was investigated. The drug loading capacity can be achieved to 0.692 mg DOX/mg SiO₂@CaSiO₃, exhibiting pH-responsivity under low pH conditions.     

A reevaluation of the correlation between the synthesis parameters and structure and properties of nitrogen-doped carbon nanotubes

Nitrogen-doped carbon nanotubes(NCNTs) were synthesized by chemical vapor deposition using cobaltbased oxides as catalyst and ethylenediamine(EDA) as carbon/nitrogen precursor. The influence of growth time,EDA concentration and growth temperature on the morphology,yield,composition,graphitization and oxidation resistance of the NCNTs was systematically investigated by using Raman spectroscopy,temperature-programmed oxidation and other techniques. The NCNT growth from ethylenediamine with a high N/C ratio involves several processes including mainly(1) catalytic growth of NCNTs,(2) homogeneous gas-phase decomposition of EDA,(3) non-catalytic deposition of pyrolytic carbon/nitrogen species and(4)surface etching of amorphous carbon or carbon at defect sites through gasification. At a later growth stage the etching process appears to be dominating,leading to the thinning of nanotubes and the decrease of yield.Moreover,the surface etching through carbon gasification strongly influences the structure and degree of graphitization of NCNTs.     

The role of ions and UV radiation in gallium arsenide etching process

The mechanism of gallium arsenide etching in a chlorine-argon plasma was studied. The absorption-desorption model was proposed which explains an increase in etching rate upon chlorine dilution with argon by enhancement of the efficiency of active site cleaning with plasma UV radiation and ion fluxes. The processes of desorption of etching products from the surface by ions and UV photons were shown to be energetically favored. The amount of active sites cleaned per ion or photon was calculated. The addition of argon was assumed to change the proportion of active sites. Procedures for calculating fluxes of reactive species onto the surface and the probability of ultraviolet light and ion-induced desorption were detailed.     

Effects of acid etching on the structure of PtNi catalyst and total exposed active sites

The integration technology of hydrogen preparation–hydrogen storage not only can utilize hydrogen energy efficiently but also can improve the selectivity of the electrode maximally. In the present work, the structure and composition of the PtNi catalyst was characterized by X-ray diffraction (XRD); and its electrochemical properties, morphology, and surface binding energy were analyzed by cyclic voltammetry (CV) and linear scanning voltammetry (LSV), scanning electron microscopy equipped with energy-dispersive spectrometry (SEM-EDS), and X-ray photoelectron spectroscopy (XPS), respectively. The effects of different acid etching treatments (e.g., etching time, etchant concentration, and etching temperature) on the structure and surface active sites were investigated by the orthogonal experiment. The experimental results reveal that after etching with 0.5 mol/L of perchloric acid for 0.5 h at 60°C, the electrode weight loss of the PtNi catalyst is mainly attributed to the large loss of Ni atoms in film layer. This results in the reduced alloy phase in film layer and the appearance of Pt characteristic diffraction peak. The relative content of Pt on the surface of the film electrode increases significantly, and the total number of active sites also increases correspondingly. The binding energy of Pt4f_7/2 decreases by 0.19 eV, and the number of active sites involved in hydrogen release decreases, indicative of the reduced promotion effect of the PtNi catalyst on hydrogen release.     

A study of surface modification and anchoring techniques used in the preparation of monolithic microcolumns in fused silica capillaries

Based on a survey of the literature on pretreatment of fused silica capillaries, 3 etching procedures and 11 silanization protocols based on the vinylic silane 3-((trimethoxysilyl)propyl) methacrylate (gamma-MAPS) were found to be most representative as a means of ensuring attachment of in situ prepared vinylic polymers. These techniques were applied to fused silica capillaries and the success in establishing the intended surface modification was assessed. X-ray photoelectron spectroscopy (XPS) was used to characterize the chemical state of the surface, providing information regarding presence of the reagent bound to the capillary. Wetting angles were measured and correlated with the XPS results. An adherence test was done by photopolymerization of a 2 mm long plug of 1,6-butanediol dimethacrylate in the prepared capillaries and evaluation of its ability to withstand applied hydraulic pressure. SEM was also performed in cases where the plug was released or other irregularities were observed. Finally, the roughness of the etched surface, considered to be of importance, was assessed by atomic force microscopy. Alkaline etching at elevated temperature provided a surface roughness promoting adhesion. The commonly used silanization protocols involving water in the silanization or washing steps gave inadequate surface treatment. The best silanization procedure was based on toluene as a solvent.     

金属铜表面的三维齿状图形的化学微加工

金属铜表面的三维齿状图形的化学微加工;约束刻蚀剂层技术(CELT);化学刻蚀     

Stability of a salicylate-based poly(anhydride-ester) to electron beam and gamma radiation

The effect of electron beam and gamma radiation on the physicochemical properties of a salicylate-based poly(anhydride-ester) was studied by exposing polymers to 0 (control), 25 and 50 kGy. After radiation exposure, salicylic acid release in vitro was monitored to assess any changes in drug release profiles. Molecular weight, glass transition temperature and decomposition temperature were evaluated for polymer chain scission and/or crosslinking as well as changes in thermal properties. Proton nuclear magnetic resonance and infrared spectroscopies were also used to determine polymer degradation and/or chain scission. In vitro cell studies were performed to identify cytocompatibility following radiation exposure. These studies demonstrate that the physicochemical properties of the polymer are not substantially affected by exposure to electron beam and gamma radiation.     

Microscopic study of ultra-thin gold layers on polyethyleneterephthalate

Continuous and discontinuous gold layers sputtered on polyethyleneterephthalate (PET) were characterized using atomic force microscopy (AFM), scanning electron microscopy (SEM) and by reflection of microwave radiation. The changes in the surface morphology of the continuous and discontinuous gold layers as a function of the sputtering time were clearly observed by AFM technique. SEM imaging of very thin gold layers was adversely affected by specimen charging. For medium sputtering times, when a continuous gold coverage is already formed, the SEM technique still show the presence of regions with very thin gold coverage which gradually disappear at longer sputtering times. Both, the AFM and SEM techniques confirmed that in the course of the gold deposition the initially small gold clusters grow and finally associate in a continuous layer. It was shown that the sub-microne metallic structures could be modeled by artificial, significantly larger structures prepared on PET by lithographic etching.     

Preparation of Porous Hollow SiO2 Spheres by a Modified St?ber Process Using MF Microspheres as Templates

Using the surface charged and acid dissolvable melamine formaldehyde (MF) microspheres as sacrificial hard templates, silica coated MF core?Cshell composite microspheres, denoted as MF@SiO₂, were synthesized via a surfactant-assisted sol?Cgel process by using tetraethyl orthosilicate (TEOS) as silica source. Hollow SiO₂ spheres with mesoporous shells were then obtained after selective removal of the MF cores and the pore directing surfactant by hydrochloric acid etching or calcinations in air. Interesting shrinkage phenomena were observed in both the hollow products derived from hydrochloric acid etching and calcinations. The influence of the ratio of MF sphere to TEOS and the removal method of the MF core on the size of the hollow spheres, the shell thickness and the shell surface roughness have been studied. The composition, the thermal stability, the morphology, the surface area and pore size distribution, the wall thickness and adsorption properties of the hollow spheres derived from hydrochloric acid etching and calcinations were also investigated and compared based on the FTIR, SEM, TEM, TGA, Nitrogen adsorption?Cdesorption and spectrophotometer techniques or measurements.     

Superparamagnetic pH‐sensitive multilayer hybrid hollow microspheres for targeted controlled release

The superparamagnetic multilayer hybrid hollow microspheres have been fabricated using the layer‐by‐layer assembly technique by the electrostatic interaction between the polyelectrolyte cation chitosan (CS) and the hybrid anion citrate modified ferroferric oxide nanoparticles (Fe₃O₄‐CA) onto the sacrificial polystyrene sulfonate microspheres templates after etching the templates by dialysis. The saturation magnetization and magnetite contents of the superparamagnetic multilayer hybrid hollow microspheres were 32.46 emu/g and 51.3%, respectively. The hybrid hollow microspheres showed pH‐sensitive characteristics. The adsorption and release of the basic dye (methylene blue) were applied to investigate the interaction between the amino groups of CS and the carboxyl groups of the Fe₃O₄‐CA nanoparticles in different pH media. The superparamagnetic pH‐sensitive multilayer hybrid hollow microspheres are expected to be used for the targeted controlled release of drugs or in diagnostics. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3135–3144, 2010     

Electrochemical properties of PP membranes with plasma polymer coatings of acrylic acid

Commercial polypropylene (PP) membranes were modified by plasma polymerization coating of acrylic acid, in combination with oxygen flow or oxygen plasma etching. First, conditions for plasma polymerization coating were optimized in terms of the chemical resistance of the coatings and their ion exchange capacity as a function of plasma power, internal pressure and treatment time. Next, the plasma polymerization coating of acrylic acid was combined with oxygen flow or oxygen plasma etching, and their conditions were also optimized by measuring the ion exchange capacity. Finally, the modified membranes were subjected to electrical resistance and transport number measurements and characterized by -step, FT-IR/ATR and SEM. Among the modification methods, oxygen plasma etching followed by the plasma polymerization coating of acrylic acid provided the best electrochemical properties with 1.75 meq/g (IEC) and 112 Ω cm² (ER), 0.88 (TN).     

Improving prediction selectivity for on-line near-infrared monitoring of components in etchant solution by spectral range optimization

The components (H₃PO₄, HNO₃, CH₃COOH and water) in an etchant solution have been accurately measured in an on-line manner using near-infrared (NIR) spectroscopy by directly illuminating NIR radiation through a Teflon line. In particular, the spectral features according to the change of H₃PO₄ or HNO₃ concentrations were not mainly from NIR absorption themselves, but from the perturbation (or displacement) of water bands; therefore, the resulting spectral variations were quite similar to each other. Consequently partial least squares (PLS) prediction selectivity among the components should be the most critical issue for continuous on-line compositional monitoring by NIR spectroscopy. To improve selectivity of the calibration model, we have optimized the calibration models by finding selective spectral ranges with the use of moving window PLS. Using the optimized PLS models for each component, the resulting prediction accuracies were substantially improved. Furthermore, on-line prediction selectivity was evaluated by spiking individual pure components step by step and examining the resulting prediction trends. When optimized PLS models were used, each concentration was selectively and sensitively varied at each spike; meanwhile, when whole or non-optimized ranges were used for PLS, the prediction selectivity was greatly degraded. This study verifies that the selection of an optimal spectral range for PLS is the most important factor to make Teflon-based NIR measurements successful for on-line and real-time monitoring of etching solutions.     

氧化铝纳米线的制备及其形成机理

采用二次铝阳极氧化技术, 制备高度有序的铝阳极氧化膜(AAO模板). 经X射线衍射(XRD)分析, 模板为无定形结构. 将模板放入腐蚀液中, 可获得大量无定形结构的氧化铝纳米线. 模板在800 ℃下退火4 h后, 变为γ-Al2O3结构, 采用类似腐蚀液溶解模板, 得到大量γ-Al₂O₃纳米线. 研究了腐蚀液种类、腐蚀时间和模板晶体结构等因素对生成氧化铝纳米线的影响, 并利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和XRD对纳米线的形貌与结构进行了表征. 结果表明, 在多种腐蚀液中, 均可获得氧化铝纳米线; 随着腐蚀时间的增加, 纳米线的长度增加, 直径变小, 长径比增大; 氧化铝纳米线的晶体结构与所采用模板的晶体结构一致. 此外, 还采用原子力显微镜(AFM)和SEM对AAO膜的表面形貌及其结构特点进行了详细的观测, 并以此为基础讨论了氧化铝纳米线的形成机理, 认为AAO模板本身存在的花状微结构是形成纳米线的内因, 花瓣间的凹陷部位首先被腐蚀断裂, 形成氧化铝纳米线.     

Synthesis and characterizations of various polyvinyl pyrrolidon/hydroxyl ethyl methacrylate nanocomposite hydrogels as drug delivery systems

Using polymer hydrogels and nanocomposites hydrogels still promising materials for many applications. Polyvinyl pyrrolidone (PVP) has been used with various polymers synthetic and natural for different applications. In this study PVP and hydroxyl ethyl methacrylate (HEMA) copolymer hydrogels were prepared by the aid of gamma radiation and the PVP/HEMA nanocomposite hydrogels were obtained by in situ adsorption and reduction method of iron salts and silver nitrates (AgNO₃) to form PVP/HEMA-Fe₃O₄ and PVP/HEMA-Ag nanocomposites. The prepared hydrogels and the formed nanoparticles were studied by various techniques; FTIR, TEM, SEM and also the gel content and swelling behavior were evaluated. The prepared hydrogels and nanocomposites hydrogels were examined as drug delivery systems for Ciprofloxacin HCl as model drug. The PVP/HEMA-Fe₃O₄ nanocomposite gave the suitable load and release behavior towards Ciprofloxacin HCl.     

Carbohydrate analysis of glycoproteins A review

Many of the products prepared by biotechnological approaches, including recombinant genetic engineering, cell tissue culture, and monoclonal technologies, are glycoproteins. As little as five years ago, glycosylation was believed to play no significant role in the function of glycoproteins. Recent large scale testing of glycoprotein-based pharmaceuticals has indicated that both the extent and type of glycosylation can play a central role in glycoprotein activity. Although methods for compositional and sequence analysis of proteins and nucleic acids are generally available, similar methods have yet to be developed for carbohydrate oligomers and polymers. This review focuses on new, developing methods for the analysis and sequencing of the carbohydrate portion of glycoproteins. Included are: (1) the release of oligosaccharides and hydrolysis of carbohydrate chains using enzymatic and chemical methods; (2) fractionation by LPLC, electrophoresis, HPLC, and lectin affinity chromatography; (3) detection through the preparation of derivatives or by new electrochemical methods; (4) analysis by spectroscopic methods, including MS and high-field NMR; and (5) their sequencing through the use of multiple, well-integrated techniques. The ultimate goal of the analytical approaches discussed is to firmly establish structure and, thus, permit the study of structure-function relationships and eventually to allow the intelligent application of carbohydrate remodeling techniques in the preparation of new glycoproteins.