Selective Chemical Treatments Research Articles

DirectRMDB: a database of post-transcriptional RNA modifications unveiled from direct RNA sequencing technology.

With advanced technologies to map RNA modifications, our understanding of them has been revolutionized, and they are seen to be far more widespread and important than previously thought. Current next-generation sequencing (NGS)-based modification profiling methods are blind to RNA modifications and thus require selective chemical treatment or antibody immunoprecipitation methods for particular modification types. They also face the problem of short read length, isoform ambiguities, biases and artifacts. Direct RNA sequencing (DRS) technologies, commercialized by Oxford Nanopore Technologies (ONT), enable the direct interrogation of any given modification present in individual transcripts and promise to address the limitations of previous NGS-based methods. Here, we present the first ONT-based database of quantitative RNA modification profiles, DirectRMDB, which includes 16 types of modification and a total of 904,712 modification sites in 25 species identified from 39 independent studies. In addition to standard functions adopted by existing databases, such as gene annotations and post-transcriptional association analysis, we provide a fresh view of RNA modifications, which enables exploration of the epitranscriptome in an isoform-specific manner. The DirectRMDB database is freely available at: http://www.rnamd.org/directRMDB/.

Effects of soil components, solution chemical properties, and temperature on Cu(II) adsorption by alluvial acid soil: a case study in Southwest China

Soil components, solution chemical properties, and temperature are important factors that affect Cu(II) adsorption in soil. However, the research in this area is currently lacking. In this study, the clay fraction was separated from alluvial acid soil. In addition, organic matter, free Fe oxides, and Mn oxides were selectively removed by washing the bulk soil and the clay fraction with H2O2, Na3C6H5O7·2H2O + NaHCO3 + Na2S2O4, and HONH3Cl. Adsorption experiment results indicate that Cu(II) adsorption decreased for bulk soil and clay fractions after removing organic matter and Mn oxides. However, after free Fe oxides were removed, the Cu(II) adsorption increased for bulk soil and clay fractions. The adsorption capacity of the clay fraction for Cu(II) was higher than that of the bulk soil irrespective of the selective chemical extraction treatment. When the initial pH increased from 2 to 3.5, the adsorption capacity increased rapidly; when the pH > 6, the adsorption capacity did not change significantly. When the pH was greater than 6, increased Cu(II) adsorption may occur due to the precipitation of Cu(II). Increased ionic strength can inhibit Cu(II) adsorption. The effects of foreign ions on Cu(II) adsorption were in the order Na+ < K+ < Mg2+ < Ca2+ for cations and NO3− < SO42− ≈ Cl− for anions. The Cu(II) adsorption was an endothermic and spontaneous process under the investigated experimental conditions.

MaTrEx AM: A new hybrid additive manufacturing process to selectively control mechanical properties

This study is the first to demonstrate how mechanical and geometrical properties of polylactide (PLA) and acrylonitrile butadiene styrene (ABS) additively manufactured with material extrusion can be selectively tailored using a newly devised treatment method of chemical immersion in acetone. This combination of manufacturing and chemical treatment results in a hybrid process capable of modifying mechanical behaviour in a predictable and time-controlled manner. Key new understanding is generated by analysing short-term effects (tested immediately after immersion) on mechanical and geometrical properties of printed specimens, with different immersion times (1–60 seconds) causing significant increases in strain-at-fracture - up to 25- and 16-fold for PLA and ABS, respectively. In the long-term mechanical properties were found to recover by up to 90% of those for untreated specimens in ABS within 3 hours, while PLA properties recovered after 60 days. Importantly, while mechanical properties in both PLA and ABS recovered, the geometrical changes were retained. Annealing allowed the recovery time to be shortened: PLA specimens achieved full recovery within 24 hours. Chemical immersion provides significant advantages over widely used vapour-based treatment methods, since it allows selective application to achieve and localised changes of mechanical and geometrical properties. Applications of this new hybrid process, called Material Treatment Extrusion Additive Manufacturing (MaTrEx AM), are presented, including the capability to add new functionality (dramatically increased plasticity) to material structures manufactured with PLA and ABS. The implementation of MaTrEx AM as a hybrid manufacturing system is demonstrated. MatrEX AM enabled selective and localised modification of mechanical properties to increase toughness and redirect strain into selected regions of a mesh material. • A new hybrid extrusion AM-chemical treatment process (MaTrEx AM) is developed. • Short- and long-term effects of acetone on polymer properties is investigated. • Plasticity significantly increased up to 25-fold after chemical treatment. • Material properties took 60 days to recover to original levels after exposure. • Selective chemical treatment transformed deformation mechanisms of lattices.

Paper Ageing: The Effect of Paper Chemical Composition on Hydrolysis and Oxidation.

The degradation of cellulose is an important factor influencing its mechanical, optical, physical, and chemical properties and, hence, the lifetime of paper in libraries and archival collections. Regardless of the complexity of the paper material, the main chemical pathways for its degradation are hydrolysis and oxidation. This study presents an overview of the analytical techniques employed in the evaluation of the hydrolysis and oxidation processes; these techniques include size-exclusion chromatography, Fourier-transform infrared and ultraviolet–visible spectroscopy, and X-ray diffraction. This paper aims to determine the extent to which these instrumental methods are useful for studying the aforementioned processes and for which lignin contents. It also highlights how atmospheric humidity could affect the cellulose structure in paper containing lignin. It was found that humidity causes significant changes in the cellulose chain lengths and that a high lignin content in paper could suppress some cellulose degradation pathways. This knowledge can be applied to developing strategies and selective chemical treatments preventing the consequences of paper ageing.

Anodic TiO2 nanotube walls reconstructed: Inner wall replaced by ALD TiO2 coating

A reconstruction process of TiO2 nanotube (TNT) layers towards their superior photoelectrochemical performance and photocatalytic activity is presented. At first, TNT layers (~5 μm thick, ~250 nm in diameter) were prepared via electrochemical anodization to obtain double-wall (DW) TNT layers. Second, a selective chemical treatment was conducted to etch the inner wall, yielding single-wall (SW) TNT layers. Third, TNT layers were coated by an additional approx. 5.5 nm, 11 nm, and 16 nm thick TiO2 coatings, respectively, using Atomic Layer Deposition (ALD). A pronounced increase in the incident photon-to-electron conversion efficiency (reaching ~85% at λ = 350 nm) was achieved on SW TNT layers coated with 11 nm thick ALD coatings compared to SW without coating (~35% at λ = 350 nm). This is due to the optimal thickness of the ALD TiO2 coating that passivates surface states and improves the separation of the photogenerated charge carriers. Photocatalytic performance of SW TNT layers with 11 nm thick ALD coatings (rate constant; k = 0.1156 min−1) was increased by approx. 10-times compared to that of the nowadays most reported blank DW TNT layers (rate constant; k = 0.0119 min−1).

Weed Density and Distribution Estimation for Precision Agriculture Using Semi-Supervised Learning

Uncontrolled growth of weeds can severely affect the crop yield and quality. Unrestricted use of herbicide for weed removal alters biodiversity and cause environmental pollution. Instead, identifying weed-infested regions can aid selective chemical treatment of these regions. Advances in analyzing farm images have resulted in solutions to identify weed plants. However, a majority of these approaches are based on supervised learning methods which requires huge amount of manually annotated images. As a result, these supervised approaches are economically infeasible for the individual farmer because of the wide variety of plant species being cultivated. In this paper, we propose a deep learning-based semi-supervised approach for robust estimation of weed density and distribution across farmlands using only limited color images acquired from autonomous robots. This weed density and distribution can be useful in a site-specific weed management system for selective treatment of infected areas using autonomous robots. In this work, the foreground vegetation pixels containing crops and weeds are first identified using a Convolutional Neural Network (CNN) based unsupervised segmentation. Subsequently, the weed infected regions are identified using a fine-tuned CNN, eliminating the need for designing hand-crafted features. The approach is validated on two datasets of different crop/weed species (1) Crop Weed Field Image Dataset (CWFID), which consists of carrot plant images and the (2) Sugar Beets dataset. The proposed method is able to localize weed-infested regions a maximum recall of 0.99 and estimate weed density with a maximum accuracy of 82.13%. Hence, the proposed approach is shown to generalize to different plant species without the need for extensive labeled data.

Side Effects of Pesticides on the Olive Fruit Fly Parasitoid Psyttalia concolor (Szépligeti): A Review

Pesticide applications in olive orchards could alter the biological control of parasitoid Psyttalia concolor Szépligeti (Hymenoptera: Braconidae) on the key pest Bactrocera oleae Rossi (Diptera: Tephritidae). Psyttalia concolor adults can be contaminated by exposure to spray droplets, contact with treated surfaces or oral uptake from contaminated food sources. Pesticides impact both pest and parasitoid populations when they coexist in time and space, as they reduce pest numbers available for parasitoids and might cause toxic effects to parasitoids from which they need to recover. Therefore, the appropriate timing and application of selective chemical treatments provides the opportunity to incorporate this parasitoid in the IPM of B. oleae. This manuscript reviews the current literature on lethal and sublethal effects of insecticides, fungicides, herbicides, and biopesticides on P. concolor. Insecticides were generally more toxic, particularly organophosphates and pyrethroids, while herbicides and biopesticides had less effects on mortality and reproductive parameters. Some fungicides were quite harmful. Most of the studies were conducted in laboratory conditions, focused on reproduction as the only sublethal effect, exclusively considered the effect of a single pesticide and persistence was hardly explored. Field studies, currently quite scarce, are absolutely needed to satisfactorily assess the impact of pesticides on P. concolor.

Dynamic Liquid Drop/Meniscus: A New Route to Electrodeposition

Dynamic Liquid Drop/Dynamic Liquid Meniscus (DLD/DLM) is a patented technology suitable for localized chemical and electrochemical surface treatments. Indeed, DLD/DLM is an original and highly innovative tool able to continually renew the chemical solution used to produce selective chemical processes and treatments on a wide range of substrates and materials allowing very fast electrodeposition. High-speed electroplating is usually performed in the mass transport-controlled regime [1]. Therefore, the limiting current density (Jmax )is given by: Jmax=nFD/(δCb) Where D is the diffusion coefficient of the deposited species, n is the number of electrons per ion, F the Faraday constant, Cb the bulk concentration of the ions in the solution and δ the diffusion layer thickness. Under mass control conditions, metal ions are reduced as soon as they reach the electrode. Conversely, current densities higher than Jmax result into hydrogen evolution and lead to "burnt" and porous deposits [1]. Multiple approaches are employed to decrease the diffusion layer thickness (δ) and, therefore raise the limiting current density [2]: Improving the hydrodynamics (i.e. the flow velocity) of the electrolytic solution (e.g. jet plating, rotating electrode, ultrasonic agitation)Exploiting thermal effects stemming from Brownian motion and laser platingModifying the electrodes’ current distribution through Pulse plating, and by tailoring the anode–cathode configurationIntroducing additives into the electroplating bath formulation. Feasibility of copper electroplating with deposition rates as high as 50µm/s (corresponding to a 150A·cm-2 current density) have been proven by using laser jet-electroplating [3]. Furthermore, deposition rates of µm/s combined to high cathodic efficiency (e.g. > 80%) could be achieved through electrolyte flows in the m/s range[4]. The present work puts forward DLD/DLM systems, relying on special 3D nozzles, for two technologically-relevant electronics application: Mask-free metallization of HJT (i.e. Heterojunction) solar cells [5] by PRP (Pulse Reverse Plating) techniques. Electrolyte flow rates ranging from 0.1 to 2 m/s and electrodeposition rates between 1 and 5 µm/s can be attained (see figure 1.A).Deposition of highly uniform and homogeneous multicomponent alloys by taking advantage of sequentially arranged DLD/DLM plating heads (i.e. multilayer method). Lead-free solders (e.g. 305 and 405 SAC) were deposited at 0.8 micron/s from single-component electrochemical baths (see Figure 1.B) [6]. In addition, nanostructured composite materials comprised of multilayers containing up to 10-15% of nanoparticles can be fabricated by means of coalescent DLD/DLM (a variant of the original technique). Thus, new methods aiming at enhancing the performances of anti-corrosion coatings can be developed from the DLD/DLM. Furthermore, chemical treatments other than electrochemical deposition such as galvanic displacement and electroless coating can be easily implemented by the DLD/DLM approach. The presentation will provide a detailed description of the new sheet-to-sheet automatic DLD/DLM prototype equipment (see figure 1.C) with different 3D nozzles. Moreover, applications including a three-step metallization process for solar cells, multilayer deposition of two, three or four components lead-free solders, and nanostructured composites incorporating nanoparticles (e.g. SiO2 or Teflon). Finally, DLD/DLM capabilities in terms of speed of plating, flexibility and versatility will be also illustrated. In fact, the relatively small amounts of plating bath (typically 2-5 L) in conjunction with the possibility to adapt the technique to the coating of a broad range of surface areas (from tens of square microns to thousands of square centimeters) may bring about remarkable cost reductions in the electronic devices manufacturing and open a new route to electrodeposition. [1] F. C. Strong "Faraday's Laws in One Equation". Journal of Chemical Education. 38 (2) (1961) 98 [2] M. De Vogelaere, V. Sommer, H. Springborn, U. Michelsen-Mohammadein, "High-speed plating for electronic applications", Electrochimica Acta 47 (2001) pp. 109–116 [3] R. J. von Gutfeld and D. R. Vigliotti, "High-speed electroplating of copper using the laser jet technique" , Appl. Phys. Lett. 46, (1985), pp. 1003-1005 [4] L. J. J. Janssen "High-rate electrochemical copper deposition on bars" J. of Applied Electrochemistry 18 (1988) 339-346 [5] M. Balucani, S. Quaranta "A Breakthrough in Plating for Solar Cell Metallization" AiMES 2018, Tuesday, 2 October 2018: 14:40 MA2018-02 818 [6] M. Balucani, S. Quaranta "A Breakthrough in Pb-Free Solder Electroplating" AiMES 2018, Tuesday, 2 October 2018: 10:40 MA2018-02 1128 Figure 1

Selective delipidation of Mycobacterium bovis BCG enables direct pulmonary vaccination and enhances protection against Mycobacterium tuberculosis.

Mycobacterium tuberculosis (M.tb), the causative agent of tuberculosis (TB), is the leading killer due to an infectious organism. Mycobacterium bovis bacillus Calmette-Guérin (BCG) is the only vaccine approved against TB, however, its efficacy against pulmonary TB is poor. While BCG is currently inoculated intradermally, the natural route of M.tb infection is through the lung. Excessive lung pathology caused by pulmonary inoculation of BCG has prevented the use of this immunization route. Here, we show that selective chemical treatment of BCG with petroleum ether removes inflammatory lipids from the bacterial surface while keeping BCG viable. Pulmonary vaccination using this modified BCG attenuated inflammatory responses, prevented immunopathology of the lung, and significantly increased protection against M.tb infection in mice. We further directly linked IL-17A as the responsible contributor of improved immunity against M.tb infection. These results provide evidence that selective removal of cytotoxic lipids from the BCG surface attenuates inflammation and offers a safer and superior vaccine against TB causing less damage post-infectious challenge with M.tb.

Understanding the role of silicate concentration on the early-age reaction kinetics of a calcium containing geopolymeric binder

Understanding the effects of silicate concentration of activator solution is critical for developing cost effective geopolymeric binders, and controlling their setting and hardening behavior. However, in calcium containing geopolymers, effects of silicate concentration of activator solution on the amount and nature of reaction products at different ages are still unclear. In this study, we examined class F fly ash and slag binders activated by both silicate and hydroxide solutions. Faster hardening from ultrasonic wave reflection and faster reaction from calorimetry were seen in the binder activated by silicates than that by hydroxides. Subtraction of infrared spectra, aided by selective chemical treatments, indicated the main reaction peak in calorimetry curves correlates with formation of calcium silicate hydrate/calcium aluminosilicate hydrate (C-S-H/C-A-S-H) of the same Ca/Si ratio in the hydroxide activated binder but formation of both C-S-H gel and potassium aluminosilicate hydrate (K-A-S-H) gel in the silicate activated binder. In additional tests, the main reaction peak of the silicate activated binder was delayed as silicates in the activator solution became less polymerized, further confirming contribution of K-A-S-H formation towards the main heat peak in calorimetry curve. Scanning electron micrographs showed products grew from surface into pore space in the hydroxide activated binder but within interstitial space in the silicate activated binder.

Comparison of photoelectrochemical performance of anodic single- and double-walled TiO2 nanotube layers

In this work, the photoelectrochemical response of single-walled (SW) and double-walled (DW) TiO2 nanotube (TNT) layers is presented. TNT layers were grown on Ti substrates by anodization in two different ethylene glycol-based electrolytes to obtain ~5 and ~15 μm thick TNT layers. The inner shell of the TNT was quantitatively removed via a mild pre-annealing followed by a selective chemical etching treatment in piranha solution. All TNT layers were investigated for their photoelectrochemical response in the ultraviolet and near visible spectral range. Significantly enhanced photocurrent densities were revealed for the SW-TNT layers. This is ascribed to improved charge carrier separation along the tube walls due to the lack of the C- and F-rich inner shell removed by etching.

Spatial coexistence of American beech and sugar maple regeneration in post-harvest northern hardwood forests

Fine scale regeneration patterns of coexistent species are influenced by regeneration mechanisms and microsite requirements. Spatial patterns may be either disjunct or overlapping, which will determine competitive effects and microsite dominance, and future forest composition. Using American beech (Fagus grandifolia Ehrh.) and sugar maple (Acer saccharum Marshall) as an example, three hypotheses were tested: (1) random beech spatial patterns, (2) clumped spatial patterns of small sugar maple seedlings, and (3) disjunct beech and sugar maple patterns. Individual stems were sampled in a contiguous grid of 1-m2 quadrats across a 576-m2 area at three sites. Densities were separated into three height classes (≤30 cm, 30–90 cm, and > 90 cm, ≤4 cm diameter at breast height). Spatial statistics and regression were used to analyze spatial patterns and correlations. Beech and seedling sugar maple patterns were patchy, rejecting the first and not rejecting the second hypotheses. Hypothesis three was rejected because patches of the two species overlapped with advance regeneration beech overtopping sugar maple. Patchy patterns of advance regeneration beech and post-harvest sugar maple establishment suggest spatiotemporal niche partitioning. Beech had a competitive height advantage following harvest, but sugar maple still occurred in beech-free patches and beneath overtopping beech at a fine scale. Self-replacing beech patterns will ensure the species will continue dominance unless a selective chemical or manual treatment is applied that removes beech and releases sugar maple.

The effect of chemical treatments in laboratory and broiler plant studies on the microbial status and shelf-life of poultry

Poultry products are highly perishable with a short shelf-life of approximately 4–5 days. Chemical treatments have the potential to inhibit microbial spoilage and extend shelf-life. Preliminary tests were carried out on broiler skin samples in the laboratory and the most promising treatments tested on carcasses in the broiler processing plant. In the laboratory, the immediate and storage (3 days at 4 °C) effect of trisodium phosphate (TSP, 10 & 14%, w/v), lactic acid (LA, 1 & 5% v/v), citric acid (CA, 1 & 5%, w/v), peroxyacids (POA, 100 & 200ppm) and acidified sodium chlorite (ASC, 500 & 1,200ppm) on TVC (mesophiles and psychrotrophs), Enterobacteriaceae, Pseudomonas, lactic acid bacteria and yeasts/moulds were investigated. In general, TSP and CA were the most effective immediate treatments and in the broiler processing plant, the effect of dipping and spraying carcasses with these chemicals on microbial shelf-life was examined over 15 days at 4 °C. Although a significant (P < 0.05) immediate reduction in TVC (mesophiles and psychrotrophs) was observed with TSP in the laboratory experiment, there was no further inhibition and after 3 days the treated and control samples had similar counts. The organic acids also caused a significant (P < 0.05) immediate reduction in TVC (mesophiles and psychrotrophs) but, in contrast to TSP, a mild inhibition of subsequent growth was also observed. In the processing plant, a microbial shelf-life of approximately 4 days was obtained at 4 °C on the control (water-treated) samples which was extended by 1–2 days after treatment with TSP (14%, dip) and by up to 4 days with CA (5%, dip). It was concluded that the microbial quality and microbial shelf-life of poultry may be considerably enhanced using selective chemical treatments.

Elucidation of Novel Nanostructures by Time-Lapse Monitoring of Polystyrene-block-Polyvinylpyridine under Chemical Treatment

Nanoscale micellar structures of polystyrene-block-polyvinylpyridine (PS-b-PVP) diblock copolymers have proven their effectiveness in lithography and biological detection by serving as a choice material to produce nanoscale guides and delivery systems in a straightforward and rapid manner through self-assembly. Such applications can greatly benefit from having high versatility for the selection of template sizes (pattern repeat spacing) and shapes (pattern geometry), especially when reaching a size regime that conventional top-down fabrication techniques may not readily be able to provide desired feature dimensions. Selective chemical treatments of the diblock copolymers are one of the useful methods yielding a rich set of nanoscale features on PS-b-PVP. Exposure to selective vapor can induce reorganization of the polymeric chains of PS-b-PVP and alter the original micellar nanostructures. In this Article, we identify for the first time a host of new nanostructures formed at different stages of chloroform vapor annealing by performing time-lapse atomic force microscopy measurements. We determine key, time-dependent, topological parameters defining each nanostructure and present the likely scenario of polymeric chain reorganization during the morphological evolution of the diblock polymer nanodomains over time. We also ascertain intermediate morphological states containing the characteristic nanostructures from two consecutive phases as well as transition states appearing for a short time in between two subsequent phases. These research efforts may not only provide insight into the domain evolution steps of the micellar to the cylindrical structures of PS-b-PVP but may also be technologically advantageous for subwavelength mask design in nanolithography and high-density array fabrication in high throughput biodetection.

Novel polymer electrolyte membranes based on semi‐interpenetrating blends of poly(vinyl alcohol) and sulfonated poly(ether ether ketone)

AbstractIn this work, the properties of novel ionic polymer blends of crosslinked and sulfonated poly(vinyl alcohol) (PVA) and sulfonated poly(ether ether ketone) (SPEEK) are investigated. Crosslinking and sulfonation of PVA were carried out using sulfosuccinic acid (SSA) in the presence of dispersed SPEEK to obtain semi‐interpenetrating network blends. PVA–SSA/SPEEK blend membranes of different compositions were studied for their ion‐exchange capacity, proton conductivity, water uptake, and thermal and mechanical properties. The hydrated blend membranes show good proton conductivities in the range of 10−3 to 10−2 S/cm. When compared with pure component membranes, the PVA–SSA/SPEEK blend membranes also exhibit improvement in tensile strength, tensile modulus, and delay in the onset of thermal and chemical degradation. Semi‐interpenetrating nature of the blends is established from morphology and dynamic mechanical analysis. Morphology of the membranes was studied using scanning electron microscopy after selective chemical treatment. The dynamic mechanical properties of the membranes are examined to understand the miscibility characteristics of the blends. The relative proportions of PVA and SPEEK and the degree of crosslinking of PVA–SSA are important factors in determining the optimum properties for the blend. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Role of Cellulose Oxidation in the Yellowing of Ancient Paper

The yellowing of paper on aging causes major aesthetic damages of cultural heritage. It is due to cellulose oxidation, a complex process with many possible products still to be clarified. By comparing ultraviolet-visible reflectance spectra of ancient and artificially aged modern papers with abinitio time-dependent density functional theory calculations, we identify and estimate the abundance of oxidized functional groups acting as chromophores and responsible of paper yellowing. This knowledge can be used to set up strategies and selective chemical treatments preventing paper yellowing.

Bioactive Ti metal analogous to human cancellous bone: Fabrication by selective laser melting and chemical treatments

Selective laser melting (SLM) is a useful technique for preparing three-dimensional porous bodies with complicated internal structures directly from titanium (Ti) powders without any intermediate processing steps, with the products being expected to be useful as a bone substitute. In this study the necessary SLM processing conditions to obtain a dense product, such as the laser power, scanning speed, and hatching pattern, were investigated using a Ti powder of less than 45μm particle size. The results show that a fully dense plate thinner than 1.8mm was obtained when the laser power to scanning speed ratio was greater than 0.5 and the hatch spacing was less than the laser diameter, with a 30μm thick powder layer. Porous Ti metals with structures analogous to human cancellous bone were fabricated and the compressive strength measured. The compressive strength was in the range 35–120MPa when the porosity was in the range 75–55%. Porous Ti metals fabricated by SLM were heat-treated at 1300°C for 1h in an argon gas atmosphere to smooth the surface. Such prepared specimens were subjected to NaOH, HCl, and heat treatment to provide bioactivity. Field emission scanning electron micrographs showed that fine networks of titanium oxide were formed over the whole surface of the porous body. These treated porous bodies formed bone-like apatite on their surfaces in a simulated body fluid within 3days. In vivo studies showed that new bone penetrated into the pores and directly bonded to the walls within 12weeks after implantation into the femur of Japanese white rabbits. The percentage bone affinity indices of the chemical- and heat-treated porous bodies were significantly higher than that of untreated implants.

AMMONIUM OXALATE AND CITRATE-ASCORBATE AS SELECTIVE CHEMICAL AGENTS FOR THE MINERALOGICAL ANALYSIS OF CLAY FRACTIONS OF AN ULTISOLAND ANDISOLS FROM SOUTHERN CHILE

ABSTRACT Two selective chemical treatments consisting of mixtures of (i) oxalic acid - ammonium oxalate at pH 3 (OX) and (ii) sodium citrate - ascorbic acid at pH 6 (CA) were used to selectively remove minerals from clay fractions of four volcanic soils: one from an Ultisol and three Andisols, of the southern Chile. Chemical analysis shows that CA is more effective in removing iron from Ultisol, and OX extracts it more efficiently from Andisols. 6 K 57 Fe-Mossbauer data indicate that OX tends to remove all magnetically ordered species with low hyperfine fields; CA has no clear effect on the removal of those or the identified iron oxides in these volcanic soil materials. INTRODUCTION Selective chemical dissolution treatments are useful, and in many circumstances essential, laboratory procedures in order to improve the mineralogical analysis of soil samples. However, no chemical extractive solution, whatever the chemical dissolution mechanism, is expected to completely dissolve certain groups of chemically related minerals, while leaving unaffected the other species. In soils, iron (oxyhydr)oxides very often occur as a continuum of inter-related mineral forms or assemblages of strongly cemented multiphase grains in heterogeneous systems, of a wide range of degree of crystallinity.Cornell and Schwertmann

One-step electrodeposited CuInSe 2 thin films studied by Raman spectroscopy

CuInSe 2 thin films one-step electrodeposited under different conditions were studied by MicroRaman spectroscopy to identify and quantify the individual phases present in the films. From the analysis of the Raman spectra, the main ternary phase (CuInSe 2) and elementary selenium Se 0 were clearly identified. Specific chemical etches confirm the presence of elementary selenium Se 0 and copper selenide binary phases Cu x Se in selenium rich film. The amounts of these two phases were evaluated from X-ray Fluorescence measurements and confirmed using phase selective chemical treatments.

Study of Structural Morphology of Hemp Fiber from the Micro to the Nanoscale

The focus of this work has been to study how high pressure defibrillation and chemical purification affect the hemp fiber morphology from micro to nanoscale. Microscopy techniques, chemical analysis and X-ray diffraction were used to study the structure and properties of the prepared micro and nanofibers. Microscopy studies showed that the used individualization processes lead to a unique morphology of interconnected web-like structure of hemp fibers. The nanofibers are bundles of cellulose fibers of widths ranging between 30 and 100 nm and estimated lengths of several micrometers. The chemical analysis showed that selective chemical treatments increased the α-cellulose content of hemp nanofibers from 75 to 94%. Fourier transform infrared spectroscopy (FTIR) study showed that the pectins were partially removed during the individualization treatments. X-ray analysis showed that the relative crystallinity of the studied fibers increased after each stage of chemical and mechanical treatments. It was also observed that the hemp nanofibers had an increased crystallinity of 71 from 57% of untreated hemp fibers.