Cotton gauze-hydrogel composites: Valuable tools for electrically modulated drug delivery

Cotton gauze was inserted into a hydrogel network composed of acrylamide, sodium methacrylate, and polyethylene glycol dimethacrylate to fabricate an electroresponsive delivery system for wound dressing. The composite was characterized by swelling measurements, showing that shrinking or swelling depend on the applied voltage. The release profile of incorporated diclofenac sodium salt shows the possibility to modulate the kinetics by changes in the amplitude and duration of applied electric pulses. Mathematical models allow a characterization of release profiles, which are slower when an external voltage of 6, 12, and 18 V is applied, and faster at 24 V.     

Detection of Pinosylvins in Solid Wood of Scots Pine Using Fourier Transform Raman and Infrared Spectroscopy

Abstract

Diffuse reflectance Fourier transform infrared (DRIFT) and near infrared (NIR) FT-Raman spectroscopy were used to detect pinosylvins in the wood of Pinus sylvestris L. trees. NIR FT-Raman spectroscopy offered the possibility of revealing pinosylvins simply by visual inspection of Raman spectra whereas DRIFT spectra needed a more complicated evaluation. Pinosylvin and resin acids from Scots pine were examined as to the possibility of their being the cause of observed spectral differences between sapwood and heartwood. Since pinosylvins are important compounds for the decay resistance of Scots pine wood, the detection of pinosylvins with Raman spectroscopy might be used to assess durability of wood products.     

Study of the Ion‐Irradiation Behavior of Advanced SiC Fibers by Raman Spectroscopy and Transmission Electron Microscopy

6H–SiC single crystals and two types of SiC fibers, Hi‐Nicalon type S and Tyranno SA3, have been irradiated with 4‐MeV Au³⁺ up to 2 × 10¹⁵ cm^?2 (4 dpa) at room temperature, 100°C and 200°C. These fibers are composed of highly faulted 3C–SiC grains and free intergranular C. Stacking fault linear density and grain size estimations yield, respectively, 0.29 nm^?1 and 26–36 nm for the Hi‐Nicalon type S fibers and 0.18 nm^?1 and 141–210 nm for the Tyranno SA3 fibers. Both transmission electron microscopy and surface micro‐Raman spectroscopy reveal the complete amorphization of all the samples when irradiated at room temperature and 100°C and a remaining crystallinity when irradiated at 200°C. The latter observations reveal a multi‐band irradiated layer consisting in a partially amorphized band near the surface and an in‐depth amorphous band. Also, nanocrystalline SiC grains with high stacking fault densities can be found embedded in amorphous SiC at the maximum damage zone of the Hi‐Nicalon type S fibers irradiated at 200°C.     

Analysis of the Single-Fiber Pullout Test Using Raman Spectroscopy: Part III, Pullout of Nicalon Fibers from a Pyrex Matrix

Single-fiber pullout specimens consisting of Nicalon fibers and a Pyrex-glass matrix were fabricated using a specially designed, simple mold. Raman spectroscopy was used to map the distribution of fiber strain within the glass matrix following deformation of the fiber section in air, and the results were compared with those predicted by theoretical analyses. It was demonstrated that the behavior also could be modeled using a partial debonding theory and that the force balance equilibrium allowed the variation of inter-facial shear stress along the interface to be derived. The partial debonding theory showed that debonding occurred at an interfacial shear stress of 60 ± 20 MPa and that the friction shear stress following debonding was 23 ± 8 MPa for the specimen investigated. Furthermore, it was shown that the fracture toughness of the fiber-matrix interface was 1.8 ± 0.6 J·m^–2.     

Effect of Wood Fibers on the Rheological and Mechanical Properties of Polystyrene/Wood Composites

The effects of wood fibers on the rheological and mechanical properties of polystyrene/wood (PS/wood) composites were investigated. The composites with different ratios of PS and wood were prepared by means of internal mixer and, additionally, two different sizes of the wood particles were used, such as ～100 and ～600 µm. The rheological properties were studied using capillary rheometer, apparent shear rate, apparent shear stress, apparent viscosity, power law index, and flow activation energy at a constant shear stress were determined. The rheological results showed that the shear stress–shear rate variations obeyed a power law equation, and the composites exhibited shear thinning. The flow activation energy of the composites increased with the addition of wood particles. Mechanical results showed that stress at break of the composites was higher than that of pure PS, whereas the strain at break and impact strength of the composites were lower than that of PS. In addition, the mechanical properties of the present composites were improved when the small size of wood particles were incorporated.     

Hydroxy Propylated Lignin-Isocyanate Combinations as Bonding Agents for Wood and Cellulosic Fibers

Lignin and hydroxy propylated lignin derivatives were reacted with diisocyanates in the presence of cellulose fibers and wood particles. The attachment of lignin and lignin derivates to hydroxyl-rich surfaces of lignocellulosic materials proved to be a convenient way for increasing strength properties of reconstituted fiber and particle materials. Results indicate that hydroxypropylated lignin derivatives are capable of contributing equal or even greater strength increases to relignified fiber composites than do monomeric or polymeric diisocyanates alone. With reinforced fiber mats, it was found that strength properties were virtually unaffected up to a level of approximately 50% replacement of diisocyanates by lignin-based materials. This beneficial contribution by lignin to bonding properties could not be verified for reconstituted wood products, the strength and swelling properties of which suffered in relation to lignin content. Thftse differences are explained with differences in method of adhesive preparation and application. Lignins were obtained from the spent pulping liquor of the Kraft process, and by alkaline extraction of steam exploded Aspen wood chips. These lignins were, for the most part, reacted with propylene oxide.     

Hydroxy Propylated Lignin-Isocyanate Combinations as Bonding Agents for Wood and Cellulosic Fibers

Lignin and hydroxy propylated lignin derivatives were reacted with diisocyanates in the presence of cellulose fibers and wood particles. The attachment of lignin and lignin derivates to hydroxyl-rich surfaces of lignocellulosic materials proved to be a convenient way for increasing strength properties of reconstituted fiber and particle materials. Results indicate that hydroxypropylated lignin derivatives are capable of contributing equal or even greater strength increases to relignified fiber composites than do monomeric or polymeric diisocyanates alone. With reinforced fiber mats, it was found that strength properties were virtually unaffected up to a level of approximately 50% replacement of diisocyanates by lignin-based materials. This beneficial contribution by lignin to bonding properties could not be verified for reconstituted wood products, the strength and swelling properties of which suffered in relation to lignin content. Thftse differences are explained with differences in method of adhesive preparation and application. Lignins were obtained from the spent pulping liquor of the Kraft process, and by alkaline extraction of steam exploded Aspen wood chips. These lignins were, for the most part, reacted with propylene oxide.     

拉曼光谱及其在癌症检测中的应用

简述了拉曼光谱的原理、特点及应用,重点介绍了其在在癌症检测和诊断中的应用。     

棉浆和木浆掺混纺醋酸纤维素纤维结构与性能的分析

对棉浆和木浆三种掺混纺比例(棉浆与木浆的掺混纺比例为0∶100,50∶50,100∶0)的醋酸纤维素纤维的结构与性能进行了测试分析。采用光学显微镜观察、纤维图形分析软件计算、X射线衍射和强伸性能测试,对比分析了三种掺混纺比例纤维的截面形态、结晶度、取向度、断裂伸长率、断裂强度以及初始模量,为棉浆与木浆掺混纺醋酸纤维素纤维的广泛应用提供了理论依据。实验结果表明:三种掺混纺比例纤维的截面形态指标无显著差异,内部晶体基本结构相同,随着棉浆与木浆掺混纺比例的增加,结晶度、取向度以及强伸性能呈现出略微增大的趋势。     

Non-Destructive Determination of the Structure and Composition of Glazes by Raman Spectroscopy

The utility of Raman spectroscopy as a non-destructive technique for the characterization of glassy (alumino)silicates (modern or ancient glazes and glasses) is demonstrated. The addition of fluxing ions breaks the Si–O linkages and the degree of (de)polymerization determines the relative intensity of the Si–O bending and stretching modes and hence the degree of polymerization could be classified. The analysis can be used to predict the processing temperature of glasses. Bending ( Q ^{' n} ) and stretching ( Qⁿ ) spectral components assigned to isolated ( Q ⁰ or SiO₄), and more or less connected SiO₄ vibrational units with one, two three/four bridging oxygen allow more precise analysis. The method is applied to reference modern porcelain glazes and selected ancient ceramic glazes and glasses, representative of the different production technologies used in the Asian, Islamic, and European worlds from Roman Empire to 19th century.     

Raman Spectroscopy and Kelvin Probe Force Microscopy characteristics of the CVD suspended graphene

In this work we present combined Kelvin probe force microscopy and Raman spectroscopy studies of supported and suspended structures formed out of chemical vapor deposition (CVD) grown graphene. Work function of both suspended and supported graphene was -4.81 ± 0.06eV and -4.92 ± 0.06eV respectively. By G and 2D modes correlation we showed, that CVD graphene was influenced by biaxial strain. Increased contact potential difference (CPD) on the suspended graphene in comparison with the areas of the supported graphene was the sign of increased strain (from 0.05% to ~ 0.12%) rather than decreased doping (p-doping decreased from ~ 5.5 × 10¹²cm^-2 to ~ 4.5 × 10¹²cm^-2).     

Chemical Markers of Human Tendon Health Identified Using Raman Spectroscopy: Potential for In Vivo Assessment

The purpose of this study is to determine whether age-related changes to tendon matrix molecules can be detected using Raman spectroscopy. Raman spectra were collected from human Achilles (n = 8) and tibialis anterior (n = 8) tendon tissue excised from young (17 ± 3 years) and old (72 ± 7 years) age groups. Normalised Raman spectra underwent principal component analysis (PCA), to objectively identify differences between age groups and tendon types. Certain Raman band intensities were correlated with levels of advanced glycation end-product (AGE) collagen crosslinks, quantified using conventional destructive biochemistry techniques. Achilles and tibialis anterior tendons in the old age group demonstrated significantly higher overall Raman intensities and fluorescence levels compared to young tendons. PCA was able to distinguish young and old age groups and different tendon types. Raman intensities differed significantly for several bands, including those previously associated with AGE crosslinks, where a significant positive correlation with biochemical measures was demonstrated. Differences in Raman spectra between old and young tendon tissue and correlation with AGE crosslinks provides the basis for quantifying age-related chemical modifications to tendon matrix molecules in intact tissue. Our results suggest that Raman spectroscopy may provide a powerful tool to assess tendon health and vitality in the future.     

Preparation of a New Adsorbent Based on Wood Pulp for the Removal of Direct Blue 2 from Aqueous Solutions

Wood pulp was used as starting material for preparation of a new adsorbent for removal of Direct Blue (DB 2) from aqueous solutions. The adsorbent material was prepared by the reaction of wood pulp (WP) with epichlorohydrin and dimethylamine in the presence of pyridine and N,N-dimethylformamide (DMF). The so obtained adsorbent was called with wood pulp adsorbent (WPA). The adsorption of DB 2 onto WPA was investigated. The adsorption data show that the maximum adsorption capacity, Q_max, of DB 2 onto WPA is 102.04 mg/g. The adsorption data also show that the adsorption of DB 2 onto WPA obeys Langmuir and Freundlich isotherms.     

Recombinant yeast technology at the cutting edge: robust tools for both designed catalysts and new biologicals

Health and safety concerns, enhanced quality criteria, and environmental sustainability, have prompted investigations into production using recombinant yeasts as a feasible alternative for isolation of proteins from natural animal or plant sources, as well as for processes utilising either mammalian cell cultures or bacterial systems. An overview of recent research papers and review articles provides readers with a comprehensive insight into the field of next-generation yeast expression systems. Major breakthroughs in recombinant yeast technology linked to Pichia pastoris are (i) the public availability of tools to generate proteins with tailored and highly homogenous N-glycan structures, similar to the forms assembled in humans, (ii) the recent accomplishment of the annotation of its genome sequence, and finally, (iii) the presence of the first few (non-glycosylated) therapeutic proteins in Pichia on the market. The P. pastoris expression platform is now well developed, as proven by multiple products used in human and veterinary medicine and in industry (e.g., enzymes for chemical synthesis and for the modification/synthesis of pharmaceuticals, drug target proteins used for structural analysis or for high throughput screening, proteins for diagnostics, proteinous biomaterials, vaccines, and therapeutic proteins). Nevertheless, the complexity of protein analysis (monitoring) continues to restrict process development for recombinant products. Drawing on combined expertise in molecular biology and process technology, the Institute of Biotechnology (IBT) at the Zurich University of Applied Science (ZHAW) and its international partners have developed solutions which (i) fully eliminate (or partially reduce) the use of methanol, which is undesirable in high-cell-density and high-productivity processes, (ii) match both strain construction and process design with the target protein characteristics to the benefit of the cells' physiological shape, and (iii) allow multi-gene expressions to be balanced to achieve custom tailored and reproducible protein quality at the level of (engineered) posttranslational modifications. In addition to enabling superior product quality specifications to be achieved with reduced development time, these innovations have helped the industries involved to minimise financial risks and the risk of failure, as well as create an opportunity for (new) drugs with improved functionality at low cost.     

Raman Spectroscopy of Oral Candida Species: Molecular-Scale Analyses,Chemometrics, and Barcode Identification

Oral candidiasis, a common opportunistic infection of the oral cavity, is mainly caused by the following four Candida species (in decreasing incidence rate): Candida albicans, Candida glabrata, Candida tropicalis, and Candida krusei. This study offers in-depth Raman spectroscopy analyses of these species and proposes procedures for an accurate and rapid identification of oral yeast species. We first obtained average spectra for different Candida species and systematically analyzed them in order to decode structural differences among species at the molecular scale. Then, we searched for a statistical validation through a chemometric method based on principal component analysis (PCA). This method was found only partially capable to mechanistically distinguish among Candida species. We thus proposed a new Raman barcoding approach based on an algorithm that converts spectrally deconvoluted Raman sub-bands into barcodes. Barcode-assisted Raman analyses could enable on-site identification in nearly real-time, thus implementing preventive oral control, enabling prompt selection of the most effective drug, and increasing the probability to interrupt disease transmission.     

Characterization of the Cotunnite-Type Phases of Zirconia and Hafnia by Neutron Diffraction and Raman Spectroscopy

The crystal structures of the cotunnite-type phases (space group, Pnam, Z = 4) of pure zirconia and hafnia prepared under high-temperature, high-pressure conditions in a multianvil device were refined by time-of-flight neutron powder diffraction. The structures of both compounds are very similar and the nine polyhedral metal-oxygen distances range from 2.133(1) to 2.546(1) Å in ZrO₂ and from 2.121(1) to 2.535(2) Å in HfO₂. The Raman spectra of both phases resemble one another strongly and are consistent with the cotunnite-type structure. These results confirm that ZrO₂ and HfO₂ undergo transitions to the same phase at high pressure.     

Tautomerism in Xenon Hexafluoride: An Investigation of Xenon Hexafluoride and its Complexes by Raman Spectroscopy

Raman spectra are reported for (i) complexes of xenon hexafluoride with the fluoride-ion acceptors BF₃, PdF₄, PF₅, AsF₅, RuF₅, PtF₅, and AuF₅, and (ii) for solutions of xenon hexafluoride in HF and in WF₆. Vibrational assignments are made for the cations XeF⁺₅ and Xe₂F⁺₁₁, and evoke a normal coordinate analysis for XeF⁺₅. Xenon hexafluoride, present in concentrated solution in HF as [XeF⁺₅F⁻]₄, progressively ionizes on dilution to give Xe₂F⁺₁₁; and XeF⁺₅; on the other hand, in WF₆ solution [XeF⁺₅F⁻]₄ exists in equilibrium only with molecular XeF₆.     

Characterizing various types of defects in nuclear graphite using Raman scattering: Heat treatment,ion irradiation and polishing

Raman spectroscopy has proved to be an appropriate technique to probe defects in carbon-based materials owing to its high sensitivity, most often focused on the commonly used I_D/I_G parameter. However, this ratio may be activated by various types of defects and in a completely independent manner. Therefore, discriminating between defects is challenging. The central idea of the present work is to provide a better understanding of the Raman response to the various types of defects that may appear in nuclear graphite (carbon–carbon composite) during its manufacturing process, its operation in the nuclear reactor, or even during its preparation process such as polishing which is usually used prior to Raman characterization. This work also demonstrates the discrimination of the defect types using the combination of the I_D/I_G and FWHM(G), two structural disorder indicators evolving differently according to the type and the concentration of the introduced defects into the carbon network. The ion-beam irradiation was used here as an effective way for creating defects that could be similar to those created by neutrons in the nuclear reactor.     

Powellite‐Rich Glass‐Ceramics: A Spectroscopic Study by EPR and Raman Spectroscopy

The aim of this study was to better understand the incorporation of rare‐earth elements in glass‐ceramics of nuclear interest. We synthesized glass‐ceramics from glasses in the system SiO₂–B₂O₃–Na₂O–CaO–Al₂O₃–MoO₃–Gd₂O₃ by various heat treatments. Gadolinium is used both as a spectroscopic probe and as a minor actinide surrogate. Glass‐ceramics contain only one crystalline phase in the bulk: powellite (CaMoO₄). This phase can incorporate Gd³⁺ and Na⁺ ions by substitutions on the Ca site. We demonstrated that the charge compensation by Na⁺ favors the incorporation of rare‐earth elements. Moreover, the incorporated elements do not seem to be randomly distributed into the powellite structure.