Surface Chemistry and Structure of Ultrafine Silicon Carbide: An FT-IR Study

Using transmission FT-IR, surface characterizations are performed on ultrafine SiC powders produced by a laser-driven method. The surface species sensitive to thermal treatments (OH, CH _{x ,}, C = O, SiH _x ) are identified on samples evacuated at various temperatures. Absorption bands attributed to overtones of the fundamental Si—C modes are also present in the IR spectra and remain unchanged after treatment. The reaction of SiC with oxygen and water vapor produces a layer of silica on the sample and gaseous CO₂; the reaction with ammonia results in a partial nitridation of the surface, with the formation of NH _x groups that apparently increase the stability of the SiC against oxidation; and reaction with hydrogen produces methane in the gas phase and causes the disappearance of the bands due to surface CH _x groups.     

Symmetry-based Study of MoS2 and WS2 Nanotubes

The symmetry-based study of MS₂ (M=Mo, W) single-wall nanotubes (SWNTs) is reviewed. First, the structure and symmetry of MS₂ NTs is determined. Then, conserved quantum numbers and general forms of potentials are derived. The valence force-field method implemented into the POLSym code is used to calculate phonon dispersions. Phonons characterized by a zero angular-momentum quantum number are studied in detail. The functional dependence of the frequency of rigid layer modes on NT diameter and chirality are found, and Raman- and infrared-active modes are singled out. Electronic band structure calculations are performed by the symmetry-based density functional tight-binding (DFTB) method. Changes in the band-gap type and size with NT chirality and diameter are evaluated. Optical absorption spectra of individual NTs are calculated using DFTB wave functions for exact transition matrix element calculations. Diffraction patterns of MS₂ are predicted and NT characterization by different diffraction methods is discussed.     

表面结构不同的纳米二氧化硅原位改性聚甲醛的研究

分别选用环氧基纳米二氧化硅（SiO2）(RNSE)和甲基纳米SiO2(DNS)为填料,通过原位聚合法制备了聚甲醛(POM)/纳米SiO2复合材料,采用场发射扫描电子显微镜、热重分析仪、差示扫描量热仪、偏光显微镜和X射线衍射仪对所得复合材料的结构、热稳定性和结晶行为进行了研究。结果表明,纳米SiO2的用量和表面结构不仅影响了其在复合材料中的分散性,而且对复合材料的热稳定性和结晶行为影响显著;当RNSE的用量少于1 %（质量分数,下同）时,其在POM基体中具有较好的分散性,且相对于DNS,RNSE的分散性更好;纳米SiO2加速了POM结晶,减小了球晶尺寸,提高了结晶度,而且RNSE比DNS对POM的结晶具有更显著的促进作用,但纳米SiO2没有改变POM的晶体结构;引入纳米SiO2降低了POM的热稳定性。     

Interactions of Polyacrylamide with Cationic Surfactants: Thermodynamic and Surface Parameters

The aggregation behaviour of two cationic surfactants, viz. cetyl trimethyl ammonium bromide (CTAB) and N-cetyl pyridinium chloride (CPC), in different concentrations of water-soluble polyacrylamide has been studied in alkaline medium by electrical conductivity and surface tension measurements. A decrease in the critical micelle concentration (CMC) of the surfactant with an increase in polymer content in the mixture was observed. The thermodynamic and surface parameters have been determined and discussed. The results indicate that micellisation becomes more favourable at higher polymer content.     

Molecular Interactions of Silica Nanoparticles and Biomolecule-Functionalized Silica Nanoparticles with Bixa orellana L. Plant DNA

Silicon - Surface functionalization of silica nanoparticles (SiNPs) with biomolecules, such as amino acids, amino sugars and carbohydrates was performed to produce surface-functionalized silica...     

Interaction between Nanoparticles,Membranes and Proteins: A Surface Plasmon Resonance Study

Regardless of the promising use of nanoparticles (NPs) in biomedical applications, several toxic effects have increased the concerns about the safety of these nanomaterials. Although the pathways for NPs toxicity are diverse and dependent upon many parameters such as the nature of the nanoparticle and the biochemical environment, numerous studies have provided evidence that direct contact between NPs and biomolecules or cell membranes leads to cell inactivation or damage and may be a primary mechanism for cytotoxicity. In such a context, this work focused on developing a fast and accurate method to characterize the interaction between NPs, proteins and lipidic membranes by surface plasmon resonance imaging (SPRi) technique. The interaction of gold NPs with mimetic membranes was evaluated by monitoring the variation of reflectivity after several consecutive gold NPs injections on the lipidic membranes prepared on the SPRi biochip. The interaction on the membranes with varied lipidic composition was compared regarding the total surface concentration density of gold NPs adsorbed on them. Then, the interaction of gold and silver NPs with blood proteins was analyzed regarding their kinetic profile of the association/dissociation and dissociation constants (k_off). The surface concentration density on the membrane composed of 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine and cholesterol (POPC/cholesterol) was 2.5 times higher than the value found after the injections of gold NPs on POPC only or with dimethyldioctadecylammonium (POPC/DDAB). Regarding the proteins, gold NPs showed preferential binding to fibrinogen resulting in a value of the variation of reflectivity that was 8 times higher than the value found for the other proteins. Differently, silver NPs showed similar interaction on all the tested proteins but with a variation of reflectivity on immunoglobulin G (IgG) 2 times higher than the value found for the other tested proteins.     

单分散纳米二氧化硅微球表面化学修饰与表征

通过溶胶-凝胶法制备纳米二氧化硅微球,以乙醇作为分散介质,用硅烷偶联剂采用一步法对纳米二氧化硅进行了表面化学修饰。通过X-射线光电子能谱（XPS）、透射电子显微镜（TEM）和傅立叶红外光谱仪（FT-IR）等手段对其改性前后效果进行了分析。研究发现修饰后的纳米二氧化硅微球的疏水性增强;硅烷偶联剂与纳米二氧化硅表面羟基发生了化学反应。     

Interactions of Nanoparticles with Macrophages and Feasibility of Drug Delivery for Asthma

Understanding the interaction between nanoparticles and immune cells is essential for the evaluation of nanotoxicity and development of nanomedicines. However, to date, there is little data on the membrane microstructure and biochemical changes in nanoparticle-loaded immune cells. In this study, we observed the microstructure of nanoparticle-loaded macrophages and changes in lipid droplets using holotomography analysis. Quantitatively analyzing the refractive index distribution of nanoparticle-loaded macrophages, we identified the interactions between nanoparticles and macrophages. The results showed that, when nanoparticles were phagocytized by macrophages, the number of lipid droplets and cell volume increased. The volume and mass of the lipid droplets slightly increased, owing to the absorption of nanoparticles. Meanwhile, the number of lipid droplets increased more conspicuously than the other factors. Furthermore, alveolar macrophages are involved in the development and progression of asthma. Studies have shown that macrophages play an essential role in the maintenance of asthma-related inflammation and tissue damage, suggesting that macrophage cells may be applied to asthma target delivery strategies. Therefore, we investigated the target delivery efficiency of gold nanoparticle-loaded macrophages at the biodistribution level, using an ovalbumin-induced asthma mouse model. Normal and severe asthma models were selected to determine the difference in the level of inflammation in the lung. Consequently, macrophages had increased mobility in models of severe asthma, compared to those of normal asthma disease. In this regard, the detection of observable differences in nanoparticle-loaded macrophages may be of primary interest, as an essential endpoint analysis for investigating nanomedical applications and immunotheragnostic strategies.     

Surface Modification of Amorphous SiO2 Nanoparticles by Oxygen-Plasma and Nitrogen-Plasma Treatments

In this study, amorphous silica gels were synthesized and treated by oxygen plasma and nitrogen plasma at a radio frequency power of 60 W, at heating temperature of 300°C, and a treatment period of 400 s. The silica gels were characterized by using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, Brunauer–Emmett–Teller, and thermal conductivity analyzers. The characterization results show that oxygen-plasma treatment has remarkably reduced the surface hydroxyl groups in silica gels, whereas nitrogen-plasma treatment has less effects. The reduction of the hydroxyl groups is a key factor contributing to reduced particle size from 30 nm to 15 nm, thus resulting in an increased specific surface area from 124 to 420 m²/g. In addition, the reduced particle size has drastically lowered the thermal conductivity of silica gels, from 0.14220 to 0.00014 W/mK. Therefore, oxygen-plasma treatment is a feasible method to enhance the thermal insulating properties of silica gels.     

Interphase Chemistry: The Synergy of Surface Analysis,Surface Adsorption and Adhesion

The formation of an interphase zone at the junction between an organic system, such as an adhesive or coating, and an inorganic substrate is considered. Drawing on experimental work for a fully-formulated photocured resin and theoretical models for a simple homopolymer it is shown that such a feature may be the result of preferential adsorption (for a multicomponent system) or conformational changes in the case of a homopolymer. Guidelines for the recognition, cause and prediction of such layers are provided, and their possible effects on the strength and durability of the organic/inorganic couple are discussed. It is suggested that the consideration of these phenomena at the design stage of a new resin may provide a route to optimise hydrolytic stability. The behaviour of an interphase zone of this type as a weak boundary layer is also considered.     

Interphase Chemistry: The Synergy of Surface Analysis, Surface Adsorption and Adhesion

The formation of an interphase zone at the junction between an organic system, such as an adhesive or coating, and an inorganic substrate is considered. Drawing on experimental work for a fully-formulated photocured resin and theoretical models for a simple homopolymer it is shown that such a feature may be the result of preferential adsorption (for a multicomponent system) or conformational changes in the case of a homopolymer. Guidelines for the recognition, cause and prediction of such layers are provided, and their possible effects on the strength and durability of the organic/inorganic couple are discussed. It is suggested that the consideration of these phenomena at the design stage of a new resin may provide a route to optimise hydrolytic stability. The behaviour of an interphase zone of this type as a weak boundary layer is also considered.     

Comparative Study of WS2 and Co(Ni)/WS2 HDS Catalysts Prepared by ex situ/in situ Activation of Ammonium Thiotungstate

A comparative study of the syntheses of unsupported WS₂ and M/WS₂ (M = Co, Ni) catalysts by ex situ/in situ decomposition of ammonium thiotungstate (ATT) is herein reported. Ex situ activation was performed under a H₂S (15% volume)/H₂ flow, whereas in situ activation consists in the direct decomposition of ATT or Co(Ni)/ATT precursors in the presence of a hydrocarbon solvent during the hydrodesulfurization (HDS) of dibenzothiophene (DBT). Precursors were characterized by thermogravimetric analysis and final catalysts by X-ray diffraction (XRD), scanning electron microscopy (SEM) and specific surface area (BET). Catalysts activated using the in situ mode of activation present higher specific surface areas with the noticeable exception of the Ni/ATT precursor. Activity measurements showed that the in situ activated WS₂ and Ni/WS₂ catalysts exhibit higher activity than the ex situ activated catalysts.     

Chemistry of Uranium in Glass-Forming Melts: Redox Interactions of Uranium with Chromium and Iron in Aluminosilicates

The mutual interactions by internal redox reactions of uranium and chromium and uranium and iron in two aluminosilicate glass-forming melts were studied by optical spectrophotometry. Cr(VI) was found to oxidize completely all available U(V) and U(IV) to U(VI), whereas Fe(III) was not a strong enough oxidizing agent to affect the uranium redox states. Cr(II) totally reduced all the U(V) and U(VI) in the system to U(IV); Fe(II) did not reduce any of the uranium redox species. Cr(III) coexisted with U(VI), U(V), and U(IV) in the melts. The degree of mutual interaction was governed not only by the difference in redox potentials between the respective redox couples, but also by the stability of molecular associations between the redox ions within the melt microstructure.     

Surface and Lateral Interactions of Nonylphenol Nonionic Surfactants with Porous Resin

The adsorption process between porous resins with different surface properties and nonylphenol non-ionic surfactants of the same hydrocarbon chain length but varying oxyethylene units was investigated. The adsorption of NPEOn with shorter EO chains is greater than those with longer EO chains on the surfaces of resins, and the strength of the adsorption was affected by resin surface-surfactant and surfactant-surfactant lateral interactions. Lateral interactions are endothermic, and contribute more to the adsorption process on aminated resins (MN-100, MN-150) than on hyper-crosslinked resins (MN-200, NDA-150). The surface interactions are mainly due to bonding between the hydrophobic moiety of the surfactant and hydrophobic surfaces of the resins without electrical interaction or hydrogen bonding, even on aminated resins (MN-100, MN-150). Positive ΔH values indicate that the adsorption process is endothermic overall, which is supported by the increase in adsorption capacity observed with increasing temperature.     

In Silico Study of piRNA Interactions with the SARS-CoV-2 Genome

A prolonged pandemic with numerous human casualties requires a rapid search for means to control the various strains of SARS-CoV-2. Since only part of the human population is affected by coronaviruses, there are probably endogenous compounds preventing the spread of these viral pathogens. It has been shown that piRNA (PIWI-interacting RNAs) interact with the mRNA of human genes and can block protein synthesis at the stage of translation. Estimated the effects of piRNA on SARS-CoV-2 genomic RNA (gRNA) in silico. A cluster of 13 piRNA binding sites (BS) in the SARS-CoV-2 gRNA region encoding the oligopeptide was identified. The second cluster of BSs 39 piRNAs also encodes the oligopeptide. The third cluster of 24 piRNA BS encodes the oligopeptide. Twelve piRNAs were identified that strongly interact with the gRNA. Based on the identified functionally important endogenous piRNAs, synthetic piRNAs (spiRNAs) are proposed that will suppress the multiplication of the coronavirus even more strongly. These spiRNAs and selected endogenous piRNAs have little effect on human 17494 protein-coding genes, indicating a low probability of side effects. The piRNA and spiRNA selection methodology created for the control of SARS-CoV-2 ({"type":"entrez-nucleotide","attrs":{"text":"NC_045512.2","term_id":"1798174254","term_text":"NC_045512.2"}}NC_045512.2) can be used to control all strains of SARS-CoV-2.     

Interactions of Chemically Synthesized Ferrihydrite Nanoparticles with Human Serum Transferrin: Insights from Fluorescence Spectroscopic Studies

Human serum transferrin (HST) is a glycoprotein involved in iron transport that may be a candidate for functionalized nanoparticles to bind and target cancer cells. In this study, the effects of the simple and doped with cobalt (Co) and copper (Cu) ferrihydrite nanoparticles (Fh-NPs, Cu-Fh-NPs, and Co-Fh-NPs) were studied by spectroscopic and molecular approaches. Fluorescence spectroscopy revealed a static quenching mechanism for all three types of Fh-NPs. All Fh-NPs interacted with HST with low affinity, and the binding was driven by hydrogen bonding and van der Waals forces for simple Fh-NPs and by hydrophobic interactions for Cu-Fh-NPs and Co-Fh-NPs binding, respectively. Of all samples, simple Fh-NPs bound the most to the HST binding site. Fluorescence resonance energy transfer (FRET) allowed the efficient determination of the energy transfer between HST and NPs and the distance at which the transfer takes place and confirmed the mechanism of quenching. The denaturation of the HST is an endothermic process, both in the case of apo HST and HST in the presence of the three types of Fh-NPs. Molecular docking studies revealed that Fh binds with a low affinity to HST (K_a = 9.17 × 10³ M⁻¹) in accord with the fluorescence results, where the interaction between simple Fh-NPs and HST was described by a binding constant of 9.54 × 10³ M⁻¹.     

Carbon nanotube hybrids with MoS2 and WS2 synthesized with control of crystal structure and morphology

Carbon nanotube hybrids with molybdenum and tungsten disulfides have attracted lots of attentions due to their unique electronic and photonic properties. MoS₂ and WS₂ with different layers and morphology have been produced from homogeneous ultra-fine MoO₃ and WO₃ nanoparticles (1–2 nm) with different densities on multi-walled carbon nanotubes (MWCNTs) in this work. The different MWCNT hybrid structures not only provide the investigation feasibility of exciton transfer but also give potential applications of catalysts and batteries. A facile method, ultra-sonication, has been adopted to produce MWCNT hybrids with homogeneous ultra-dense and ultra-fine MoO₃ and WO₃ nanoparticles. The as-produced molybdenum trioxide nanoparticles and free-standing molybdenum trioxide nanowires from the same method with different reaction time have been found to crystallize in different crystal lattices. The nanoparticle morphology leads to the detachment of H₂O from molybdenum trioxide lattices, which was confirmed by thermodynamic analysis based on density functional theory. MWCNT hybrids with layered MoS₂ and WS₂ are preferred after the sulfuration of MoO₃ and WO₃ nanoparticle-MWCNT hybrid structures. The layers and morphology of MoS₂ and WS₂ have been controlled by the densities of trioxide nanoparticle precursors on MWCNTs.     

Polysiloxane Softener Coatings on Plasma‐Treated Wool: Study of the Surface Interactions

Low temperature plasma (LTP) improves the shrink‐resistance of wool fabrics but impairs their softness, so different polysiloxane coatings were applied. Modifications in surface hydrophilicity and topography of fabrics and fibres have been recorded through drop test, contact angle and SEM, respectively. LTP improves the deposition of the polysiloxanes which, depending on their functionalities alter the original hydrophilicity of the wool surface. Softness and shrink‐resist results of the fabrics point out to a possible relationship between hydrophilicity of the wool fibre surface and the shrinkage behaviour of the fabrics. A possible mechanism of interaction between the different polysiloxane groups and the surface of untreated (UT) and LTP‐treated wool is proposed.

     

聚合物改性纳米SiO2表面的研究

纳米SiO2粒子被广泛用作填料来改性聚合物.但纳米SiO2粒子极易发生团聚,在有机介质中难以均匀分散,使其在许多领域的应用和发展受到限制.对纳米SiO2粒子进行表面改性处理,可以使之较好地分散到有机介质中.纳米SiO2粒子有多种表面改性方法,其中以聚合物包覆的方法效果最好.本文综述了纳米SiO2表面聚合物改性的一般方法,并对其应用前景进行了展望.