Effect of oligoethylene glycol moieties in porous silicon surface functionalisation on protein adsorption and cell attachment

We report on the synthesis of two carboxy-functional alkene compounds as modifiers of porous silicon (pSi) surface chemistry by means of thermal hydrosilylation. Both alkene compounds have hydrophobic, aliphatic carbon segments, with terminal carboxylic acid functionality appended through a thioether linkage. In one of the alkene linkers, we incorporated a short oligoethylene glycol (OEG) moiety to explore its low-fouling properties when attached to porous silicon. We examined surface stability of the surface-modified porous silicon in aqueous milieu. Albumin and fibronectin were adsorbed and, using carbodiimide chemistry, covalently immobilised to linker-modified porous silicon, and the propensity for mammalian cells to attach to these surfaces investigated. Surface chemistry was characterised by infrared spectroscopy and the stability of porous silicon in an aqueous milieu was investigated by interferometric reflectance spectroscopy (IRS). Surfaces functionalised with the alkene linker containing OEG displayed greater resistance to the adsorption of albumin. This linker also facilitated higher levels of covalent protein immobilisation to the functionalised pSi surface. Higher levels of cell attachment were observed on pSi surfaces with fibronectin covalently immobilised onto the OEG linker, than for fibronectin covalently immobilised on the non-OEG linker.     

Enlargement of omnidirectional electronic gap in the graphene superlattice heterostructures with Gaussian profile potential voltages

A valid method is used to extend the omnidirectional electronic gap (OEG) of Gaussian gapped graphene superlattices (GSLs) heterostructure. The heterostructure consists of two superlattices with different width ratios of potentials. Each superlattice comprises a periodic repetition of a unit cell consisting of 21 layers with the potential voltages varying according to a Gaussian function and another layer with a fixed potential voltage. The potential width ratios of constituent Gaussian gapped GSL are established utilizing the lower and upper energy edges of omnidirectional electronic gap depending on the width ratio of potentials. Moreover, it is shown that the width of OEG of the heterostructure is sensitive to lattice constant, which can be applicable to the development of graphene-based electronics.     

Protein adsorption properties of OEG monolayers and dense PNIPAM brushes probed by neutron reflectivity

The structure of dense poly(N-isopropylacrylamide) (PNIPAM) brushes and oligo(ethylene glycol) (OEG) monolayers has been probed using neutron reflectometry and ellipsometry. The PNIPAM brush is swollen below the Lower Critical Solution Temperature (LCST) of 32?^°C and is collapsed at 37?^°C. Neutron reflectivity shows that below the LCST, the brush is described by a two-layer model: an inner dense layer and a hydrated outer layer. Above the LCST the collapsed brush forms a homogenous layer. With a fully deuterated myoglobin protein to increase the neutron scattering length density contrast, the reflectivity data show no detectable primary adsorption on the grafted OEG surface. A bound on the ternary adsorption onto PNIPAM chains forming dense brushes below and above the LCST is obtained.     

Tandem diazonium salt electroreduction and click chemistry as a novel, efficient route for grafting macromolecules to gold surface

Bis-alkynylated oligoethyleneglycol (OEG) and a monopropargyl-functionalized perfluorinated ethylene glycol (FEG) were clicked to azide-functionalized gold surface (Au–N₃) at room temperature via the well known 1,3 cycloaddition click chemical reaction. The Au–N₃ substrate was obtained by nucleophilic attack of NaN₃ on gold substrates modified by the electrochemical reduction of the , ⁺N₂–C₆H₄–CH₂Br diazonium salt. This electrochemical process yields aryl layer-modified gold of the type Au–C₆H₄–CH₂Br (hereafter Au–Br). The untreated and modified gold plates were examined by XPS, PMIRRAS and contact angle measurements. XPS brought evidence for electrografting aryl layers by the detection of Br3d; azide functionalization by the increase of the N/Br atomic ratio; and click reaction of OEG with Au–N₃ by the increase of O/N ratio. In addition, the perfluorinated plate (Au-FEG) exhibited F1s and characteristic C1s peaks from -(CF₂)₇- chain and terminal CF₃. Infra red spectroscopy (PMIRRAS) evidenced (i) grafting N₃ to Au–Br; (ii) characteristic stretching bands, from ethylene glycol units, C–O–C (1100–1300 cm⁻¹); CF₂ (1000–1100 cm⁻¹) and CF₃ (1100–1350 cm⁻¹) from FEG grafts; and (iii) suppression of alkynyl bands from OEG and FEG after surface click chemistry. More importantly, PMIRRAS results support an important bridging of the bispropargyl oligoethylene glycol at the gold surface. Water drop contact angles were found to be 48.7° and 83.0° for Au-OEG and Au-FEG, respectively, therefore highlighting the control over the hydrophilic/hydrophobic character of the clicked substrate.This work shows that clicking macromolecules to grafted, diazonium salt-derived aryl layers is a novel, simple and valuable approach for designing robust, functional surface organic coatings.     

In-situ formation of silver nanoparticles stabilized by amphiphilic star-shaped copolymer and their catalytic application

Silver nanoparticles (Ag NPs) were prepared via in situ reduction of silver nitrate (AgNO₃) using polymeric micelles as nanoreactors without any additional reductant. The micelles were constructed from the amphiphilic star-shaped copolymer composed of poly(?-caprolactone) (PCL) segment, 2-(dimethylamino)ethyl methacrylate (DMAEMA or DMA) units and oligo(ethylene glycol)monomethyl ether methacrylate (OEGMA or OEG) units. The Ag NPs stabilized by those star-shaped copolymers were characterized using UV-vis spectrum, DLS, TEM and FTIR. It confirmed that PDMAEMA exhibited the reducing property unless pH was above 7. The Ag NPs were sphere-like with a diameter of 10-20 nm, which was independent of the architecture of the copolymer and AgNO₃ concentration. Furthermore, the catalytic activity of these Ag NPs was investigated by monitoring the reduction of p-nitrophenol (4-NP) by NaBH₄. The result showed that the Ag NPs formed by coordination reduction can be effectively applied in catalytic reaction.     

Study of molecular mobility of fluid in zeolite NaX.

The self-diffusion of n-decane in zeolite NaX was studied by NMR PFG method. The situation when the liquid was only in the crystalline channels was studied in details. The restricted molecular motion of liquid in the crystalline channels was observed. The reasons of the anomalous self-diffusion of n-decane in zeolite bed were stated. The technique of the determination of the genuine self-diffusion coefficient in such porous systems was proposed. The genuine self-diffusion coefficients for system NaX/n-decane were obtained.     

Electrical breakdown of microwave plasma in water

The electrical breakdown of microwave plasma in water was investigated between 1 and 30 kPa. The dependency of the ignition power for generating plasma on the size of coaxial electrode was measured. The ignition power decreases with a decrease of the diameter of the inner electrode. The behavior of microwave plasma in water was observed using a high-speed camera. The plasma ignites in a bubble generated by microwave heating. The model for calculating the electric field was created on the basis of the captured images of the bubble just before plasma ignition. The method presented can be used to visualize the electrical field distribution in the bubble. The electric field breakdown was calculated using the measured ignition power. The electric field breakdown of plasma in water is of the same order as gas phase plasma.     

Isospin-dependent relativistic microscopic optical potential in the Dirac Brueckner-Hartree-Fock method

There is growing evidence to suggest that the binding energy of nucleon in nuclear matter comes from a cancellation between large Lorentz scalar and vector potentials[1,2]. The relativistic approach has been of a great success in describing not only the ground state properties of stable nuclei, but also those of exotic nuclei. In the relativistic frame, the spin-orbit coupling can be deduced automatically, which is usually given by hand in the non-relativistic approach. The relativistic method…     

Nonlinear cyclotron-impurity resonance in semiconductors

The nonlinear absorption of electromagnetic radiation by electrons in a quantizing magnetic field is investigated. The inclusion of multiphoton processes is shown to result in additional peaks in the absorption curve. The shape and arrangement of these peaks were found. The absorption is shown to depend on the electric field strength in the electromagnetic wave nonlinearly and nonmonotonically. The results obtained are in good agreement with experimental data.     

Modeling and Analysis of Anomalies in the Network Infrastructure Based on the Potts Model

The paper discusses issues concerning the occurrence of anomalies affecting the process of phase transitions. The considered issue was examined from the perspective of phase transitions in network structures, particularly in IT networks, Internet of Things and Internet of Everything. The basis for the research was the Potts model in the context of IT networks. The author proposed the classification of anomalies in relation to the states of particular nodes in the network structure. Considered anomalies included homogeneous, heterogeneous, individual and cyclic disorders. The results of tests and simulations clearly showed the impact of anomalies on the phase transitions in the network structures. The obtained results can be applied in modelling the processes occurring in network structures, particularly in IT networks.     

氧化铁浆液脱硫的实验研究与理论分析

本文实验研究了氧化铁浆液在酸性环境下脱除烟气中的二氧化硫气体。实验在一自制的脱硫塔中进行。通过燃烧液化石油气来产生烟气,将氧化铁的超细粉加入水中作为脱硫介质。实验中研究了二氧化硫初始浓度、水气比对脱硫效率的影响。从实验结果可以看出,脱硫率随着水气比的增加而增大;随二氧化硫的初始浓度的增加,其脱硫率呈降低趋势。在文中同时分析了氧化铁浆液的脱硫机理和此方法脱硫的优点以及目前存在的问题。     

Some Aspects of Nuclear Structure in Relativistic Approach

The nucleon effective interaction in the nuclear medium is investigated in the framework of the DiracBrueckner-Hartree-Fock (DBHF) approach. A new decomposition of the Dirac structure of nucleon self-energy in the DBHF is adopted for asymmetric nuclear matter. The properties of finite nuclei are investigated with the nucleon effective interaction. The agreement with the experimental data is satisfactory. The relativistic microscopic optical potential in asymmetric nuclear matter is investigated in the DBHF approach. The proton scattering from nuclei is calculated and compared with the experimental data. A proper treatment of the resonant continuum for exotic nuclei is studied. The width effect of the resonant continuum on the pairing correlation is discussed. The quasiparticle relativistic random phase approximation based on the relativistic mean-field ground state in the response function formalism is also addressed.     

Investigation on the electronic transport properties of MgS nanotube based molecular devices – a first-principles study

The electronic transport properties of pure MgS nanotube based molecular devices, Mn-substituted nanotubes and Se-substituted nanotubes are investigated using density functional theory. The state of the art of this work is to study the transport properties of MgS nanotubes with substitution impurities across electrodes. The electronic transport properties are discussed in terms of device density of states and transmission spectrum of MgS nanotubes. The effects of Mn substitution and Se substitution in nanotubes are studied. The major contribution to density of states arises only from p orbitals in MgS nanotubes. The substitution effect and bias voltages also have influence in the density of states. The transmission spectrum provides information about the transmission of electrons along the nanotube. The information provided in this work gives a clear vision to fine-tune MgS nanostructures with improved transport property in nanoelectronic device fabrication.     

Retinex彩色图像增强理论的物理思考及其截断区间对图像质量的影响

指出了Retinex彩色图像增强理论的物理意义,在对数空间中,将原图像减去高斯函数与原图像的卷积,其物理本质是除去了原图像中的平滑的部分,突出了原图像中的快速变化的部分,而且高斯函数越尖锐,越是突出图像中的细节,高斯函数越平坦,图像色调保持得越好,多尺度Retinex综合了不同高斯函数与原图像进行卷积的优点。研究了多尺度Retinex标准差截断法,结果是,以多尺度Retinex处理后的图像强度在其平均值附近1倍标准差截断后再拉伸得到的图像,普遍好于以2倍、3倍标准差截断后再拉伸得到的图像。     

Prevalence of spontaneous otoacoustic emissions in neonates.

The prevalence of spontaneous otoacoustic emissions (SOAEs) was measured in a group of 100 neonates and in a group of 50 normal-hearing young adults. The prevalence of SOAEs in the adult group (0.62) is at the high end of the range of prevalences reported in other surveys of adult SOAEs based on measurements using similar microphones. The prevalence of SOAEs in neonates (0.64) is not significantly different from that in adults. The various tendencies that have been found to be significant in the pooled results of other surveys are also evident in our adult group: more SOAEs in right ears, a higher prevalence of SOAEs in females, and a dependence between ears for the occurrence of SOAEs. The above-mentioned tendencies are also significant in the infant data. The major differences between the infant and adult results are the predominant SOAE frequency range and the average levels of SOAEs. The majority of adult SOAEs are between 1.0 and 2.0 kHz, whereas the majority of neonatal SOAEs are between 2.5 and 5.0 kHz. The average SOAE level is -2.6 dB SPL for adults and 8.5 dB SPL for infants.     

Analysis of dusty plasma in the positive column of glow discharges

The radial distributions of ions,electrons and dust particles in the positive colum of glow discharges are investigated in a tripled-pole diffusion model.The dust particles are mainly trapped in the region around the column axis where the electrostatic potential is the highest.The presence of the dust particles results in the ion density increasing and the electron density decreasiung in the dust-trapped region.The dust-trapped region is wider for a higher dust temperature or a smaller particulate redius.The ions and electrons in the dust-free region away from the column axis are in ambipolar diffusion.     

Japanese cedar pollinosis: Discovery,nomenclature, and epidemiological trends

The history of pollinosis in Japan before the discovery of Japanese cedar pollinosis was presented in part I in this paper. Until early 1960s, it was believed that there was no pollinosis in Japan except one case of ragweed pollinosis.The summary of how the Japanese cedar pollinosis was discovered and named was presented in part II, by referring to the paper in which we reported the presence of Japanese cedar pollinosis for the first time.The epidemiology after the discovery of Japanese cedar pollinosis was presented in part III. The number of the patients suffering from Japanese cedar pollinosis gradually increased since the 1970s. The annual incidence rate of the pollinosis had correlations with the dispersed pollen count per year. The prevalence rate of the patients with Japanese cedar pollinosis increased from 16.2% in 1998 to 26.5% in 2008 by the nationwide survey. The prevalence rate of the patients with Japanese cedar pollinosis in Tokyo metropolitan area was 10% from 1983 to 1987, 19.4% in 1996, and 28.2% in 2006.The prospects of current research and future studies were discussed in parts IV and V.     

Vapour and plasma ignition thresholds for visible pulsed-laser ablation of metallic targets

The coupling of visible nanosecond laser pulses to metallic targets irradiated in vacuum is studied. The expressions of the vapour and plasma ignition times are obtained. Two cases for vapour breakdown in the plasma ignition process are considered. The first case is that 40 generations of new electrons are born in vapour generation time before plasma formation as assumed in the literature. The second case is that 10 generations of new electrons are born in vapour generation time. Molybdenum (Mo), niobium (Nb) and aluminium (Al) targets are considered for illustrations of our results. The expression of the plasma ignition time for the Al target is substantially different from that reported in the literature. The vapour and plasma ignition threshold laser intensities are calculated and compared with those reported in the literature. Reasons for disagreement are discussed. The plasma ignition threshold estimated in the second case is noted to be in good agreement with the reported experimental result.     

Commissioning of electron cooling in CSRe

The 400 MeV/u 12C6+ion beam was successfully cooled by the intensive electron beam near 1 A in CSRe.The momentum cooling time was estimated near 15 s.The cooling force was measured in the cases of different electron beam profiles,and the different angles between the ion beam and electron beam.The lifetime of the ion beam in CSRe was over 80 h.The dispersion in the cooling section was confirmed as positive close to zero.The beam sizes before cooling and after cooling were measured by the moving screen.The beam diameter after cooling was about 1 mm.The bunch length was measured with the help of the signals from the beam position monitor.The diffusion was studied in the absence of the electron beam.     

Influence of the degree of plastic deformation on the thermal photostability of F-centers in NaCl crystals

The effect of plastic deformations on the thermal stability and thermal photostability of F-centers in NaCl crystals was examined. The thermal photostability of F-centers and the thermal stability of some of these centers increases in proportion to the degree of plastic deformation. The concentration of the less stable F-centers increases due to plastic deformation. The effect was studied in crystals which were deformed before and after x-ray excitation. The results were interpreted from the viewpoint of an ionic activation mechanism in the thermal and photothermal decomposition of the color centers in alkalihalide crystals.The authors are indebted to Yu. L. Lukantsever for an evaluation of the results of this work.