Untreated Reference Samples Research Articles

Effect of parboiling on physical and chemical characteristics and non-enzymatic browning of emmer (Triticum dicoccon Schrank)

Parboiling is a popular technology applied to rice to increase its milling yield, nutritional value and resistance to spoilage by insects and mould. This process was applied to Triticum dicoccon Schrank to induce physical, chemical and organoleptic modifications in order to increase its use and product diversification.Hulled and dehulled emmer samples, subjected to different parboiling conditions, were characterized by analyzing the physical and chemical modifications and the non enzymatic browning.The results showed that although parboiled grains were darker than the untreated reference sample, due to the development of non-enzymatic browning and the diffusion of the pigments contained in the husk and bran, during hydrothermal treatment glumes have a protective action on the caryopsis integrity and against thermal damage.

Gas Mixture and Current Density Variation and Their Effect on White-Layer Properties of Nitrided Steel

The effect of current density and gas mixture on surface properties of low alloy steel processed in a pulsed plasma nitriding system under strictly controlled conditions is evaluated in this work. As current density is a parameter that has not been particularly studied, this study seeks to demonstrate that current density and gas mixture have an important influence on the process and an adequate combination of these two variables is essential to obtain the desired surface properties: hardness, white layer thickness (or absence), and crystalline phases of the modified layer. In this sense, samples processed at low current densities with low nitrogen content in the plasma atmosphere show a diffusive nitrides region which increases the hardness from 250 HV (untreated reference sample) to 400 HV without the presence of the typical white layer that is sometimes undesired due to its fragility and tendency to break. On the other hand, treatment at high current densities and high nitrogen concentrations leads to obtain pieces with a homogeneous single-phase layer (γ-Fe4N) with an outstanding corrosion performance, diminishing the corrosion rate from 0.160 μm per year in the untreated sample up to 0.050 μm per year.

Sol–gel derived TiO2 wood composites

The sol–gel process was applied to enhance properties of pine sapwood. For this purpose wood prisms were soaked in nanoscaled precursor solutions prepared from titanium(IV) n-butoxide and titanium(IV) iso-propoxide, respectively, using vacuum impregnation technique. The wet composites were cured by special program with final heat treatment at 103 °C. Weight percent gains (WPG) of the wood specimen in the range of 19–25% were obtained due to these procedures. SEM investigations show that precursor solutions penetrate into the whole wood body and the titania formed after heat treatment in the composites is deposited in the pores (lumen) and partly in the cell walls of the wooden matrix. The moisture sorption was investigated in long term tests for a period of some months by storage at 20–23 °C in humid air (relative humidity of 99%) and ambient atmosphere (relative humidity 40–60%), respectively. For untreated reference samples the moisture sorption results in increasing of mass and volume according to saturation values of 24 and 13%, respectively, after about 15 days. The incorporation of titania reduces the saturation values of the moisture sorption by up to 12% in mass and by up to 5% in volume at a relative humidity of 99%. Thus, an enhancement of the dimensional stability of about 60% is obtained at best. The results demonstrate that modification of wood with sol–gel derived precursors can enhance its dimensional stability, which prevents the formation of cracks. Because of that reduced moisture sorption biological attacks should be delimited. Additionally, thermal analyses show a retarded combustion of the wood matrix due to titania infiltration.

Identification of marker compounds in pyrolysis–GC/MS of various acetylated wood types

Six different types of acetylated softwoods and hardwoods were analyzed with pyrolysis–GC/MS and compared to untreated reference samples. It was shown that besides the dominant but unspecific cleavage of acetic acid several marker compounds, such as acetylated lignin monomers and acetylated furan derivatives were released under pyrolysis conditions. Structural assignment was supported by the generation of deuterated acetyl moieties, which was accomplished by acetylation of wood with deuterated acetic anhydride. Pyrolysis products of acetylated biomass have so far been only scarcely described in literature but can very well be used to trace modified wood even in complex composites.

Effect of Enzymatic Mash Treatment and Storage on Phenolic Composition, Antioxidant Activity, and Turbidity of Cloudy Apple Juice

The effects of different commercial enzymatic mash treatments on yield, turbidity, color, and polyphenolic and sediment of procyanidins content of cloudy apple juice were studied. Addition of pectolytic enzymes to mash treatment had positive effect on the production of cloud apple juices by improving polyphenolic contents, especially procyanidins and juice yields (68.3% in control samples to 77% after Pectinex Yield Mash). As summary of the effect of enzymatic mash treatment, polyphenol contents in cloudy apple juices significantly increased after Pectinex Yield Mash, Pectinex Smash XXL, and Pectinex XXL maceration were applied but no effect was observed after Pectinex Ultra-SPL I Panzym XXL use, compared to the control samples. The content of polymeric procyanidins represented 50-70% of total polyphenols, but in the present study, polymeric procyanidins were significantly lower in juices than in fruits and also affected by enzymatic treatment (Pectinex AFP L-4 and Panzym Yield Mash) compared to the control samples. The enzymatic treatment decreased procyanidin content in most sediment with the exception of Pectinex Smash XXL and Pectinex AFP L-4. Generally in samples that were treated by pectinase, radical scavenging activity of cloudy apple juices was increased compared to the untreated reference samples. The highest radical scavenging activity was associated with Pectinex Yield Mash, Pectinex Smash XXL, and Pectinex XXL enzyme and the lowest activity with Pectinex Ultra SP-L and Pectinex APFL-4. However, in the case of enzymatic mash treatment cloudy apple juices showed instability of turbidity and low viscosity. These results must be ascribed to the much higher hydrolysis of pectin by enzymatic preparation which is responsible for viscosity. During 6 months of storage at 4 degrees C small changes in analyzed parameters of apple juices were observed.

Improvement of the Adhesion of a Galvanic Metallization of Polymers by Surface Functionalization Using Dielectric Barrier Discharges at Atmospheric Pressure

AbstractAn environmentally friendly plasma amination process for the activation of polymers prior to electroless metallization using dielectric barrier discharges (DBD) at atmospheric pressure was investigated. One focus of the work was on the correlation between plasma parameters and palladium coverage on the polymer on the one hand and the palladium coverage and adhesion of a galvanic copper metallization on the other hand. Using XPS spectroscopy it was found that a DBD treatment of polyimide (PI) films with mixtures of N2 and H2 leads to considerably higher Pd surface concentrations than on untreated reference samples or foils treated in air‐DBD. The Pd coverages achieved result in peel strengths of a copper metallization of up to 1.4 N · mm−1.

Oxygen implantation and diffusion in pure titanium by an rf inductively coupled plasma

The superficial oxidation of pure titanium, 9 mm diameter, 5 mm thick disc samples by implantation and diffusion from inductively coupled plasmas is reported. Such rf plasmas were generated in a 15 l cylindrical Pyrex-like glass chamber containing pure circulating oxygen. A quarter wavelength solenoidal antenna capable of transmitting 500 W at 13.54 MHz was externally wound around the chamber and connected to an rf generator capable of up to 1200 W through an automatic matching network. The oxidation process was carried out for 6 h periods while varying the gas pressure between 1 × 10 2 and 5 × 10 −1 Pa and the sample bias up to −3000 V DC. It was found that the sample temperature was a function both of the plasma density and the bias voltage. Without bias, the plasma heated the sample up to ∼200 °C, and with maximal bias voltage, the substrate was heated to 680 °C. At the latter temperature, the presence of the rutile phase was particularly evident in X-ray diffraction patterns. According to EDX data, the average oxygen to titanium ratio rose, from ∼0.06 for an untreated reference sample, to a ∼1.7 value for samples treated up to 680 °C.

N–O mix optimisation in low energy dense DC glow surface Ti conditioning

Samples of pure titanium have been treated by means a plasma immersed ion implantation (PIII) process in a DC glow discharge in pure oxygen and in different nitrogen-oxygen mixtures. In contrast with conventional voltage supply based glow PIII, the present study has been conducted with a novel specifically designed high current supply which allows a high electron density to be kept constant, regardless of gas pressure variations, within the operational ranks. Thus, the acquired sample characteristics can be more clearly ascribed to the chemical composition of the mixture. One stratified TiO2 (rutile) and TiN0.26 layer was identified from XRD and Raman spectroscopy, both of these compounds reputedly being highly biocompatible. The superficial hardness of the samples was improved up to more than five times that of the untreated reference sample, namely, ∼1600 Vickers microhardness (10 g load) thanks to a 2–6 μm deep implanted layer. These optimal results have been obtained from an 80% nitrogen 20% oxygen mixture at 1×10-2 torr. Furthermore, with this gas proportion, the best roughness finishing of the sample set was accomplished, which can be relevant for biocompatible applications.

Enhanced flux pinning and critical currents in YBa2Cu3O7−δ films by nanoparticle surface decoration: Extension to coated conductor templates

Interfacial engineering via nanoparticle substrate surface decoration has been extended to coated conductor templates. Preformed BaTiO3 and BaZrO3 nanoparticles were applied to substrate surfaces, prior to YBa2Cu3O7−δ (YBCO) deposition, by using a scalable and inexpensive technique of solution-based suspension. Compared to untreated reference samples, nanodecoration yields improved in-field critical current density (Jc) as well as strong correlated pinning along the c-axis direction of the YBCO film. Accordingly, a much reduced falloff of Jc with magnetic field strength was observed in all of the modified samples. In addition, scaling behavior of the normalized volume pinning force density (Fp) with respect to temperature provided insight as to the differences in flux pinning mechanisms dependent on the decoration technique. Finally, with these results our earlier proof-of-concept demonstrations on nanoparticle modified single crystal substrates were replicated on technological substrates, pointing to the versatility of this simple technique for realization of enhanced high temperature superconductor performance.

Assessing the Impact of Nanomaterials on Anaerobic Microbial Communities

As the technological benefits of nanotechnology begin to rapidly move from laboratory to large-scale industrial application, release of nanomaterials to the environment is inevitable. Little is known about the fate and effects of nanomaterials in nature. Major environmental receptors of nanomaterials will be soil, sediment, and biosolids from wastewater treatment. Analysis of anaerobic microbial activity and communities provides needed information about the effects of nanoparticles in certain environments. In this study, biosolids from anaerobic wastewater treatment sludge were exposed to fullerene (C60) in order to model an environmentally relevant discharge scenario. Activity was assessed by monitoring production of CO2 and CH4. Changes in community structure were monitored by denaturing gradient gel electrophoresis (DGGE), using primer sets targeting the small subunit rRNA genes of Bacteria, Archaea, and Eukarya. Findings suggest that C60 fullerenes have no significant effect on the anaerobic community over an exposure period of a few months. This conclusion is based on the absence of toxicity indicated by no change in methanogenesis relative to untreated reference samples. DGGE results show no evidence of substantial community shifts due to treatment with C60, in any subset of the microbial community.

Artificial weathering of wood surfaces modified by melamine formaldehyde resins

Spruce and poplar samples were treated with different melamine formaldehyde resins. A long term artificial weathering experiment was performed in order to clarify the resistance to weathering regarding wood colour and surface hardness. The increase in hardness due to melamine treatment was well preserved after simulated long term weathering. The treated samples also showed advantages compared to untreated reference samples regarding discolouration and crack formation. Low molar mass and low degree of methylolation of the melamine resin used was found to be favourable for a successful treatment.

The Effects of Calcium Chloride and Sucrose Prefreezing Treatments on the Structure of Strawberry Tissues

The structural changes in strawberry tissues during prefreezing treatments, freezing and thawing were studied by means of textural and drip loss measurements as well as by bright-field and confocal laser scanning microscopy (CLSM), and by Fourier transform infrared (FT-IR) microscopy. Calcium chloride or sucrose were used as dipping pretreatment agents before freezing. In the calcium chloride test series a full factorial screening design was used. The three-level factors included were the CaCl2concentration of the dipping solution, the dipping time and the temperature of the solution. Two kinds of sucrose treatments were used. Strawberries were either dipped in water–sucrose solutions or were sprinkled with crystallized sucrose. The CaCl2or sucrose pretreatments did not significantly affect the drip loss of thawed strawberries compared to water dips or untreated reference samples. The pretreated strawberries were firmer than the untreated control samples but some of the CaCl2- and sucrose-treated strawberries were less firm than the strawberries dipped in water. According to microscopical studies, both CaCl2and crystallized sucrose pretreatments affected the microstructure of strawberry tissues. These pretreatments especially affected pectin, protein, lignin and structural carbohydrates in the vascular tissue and cortex compared to the untreated reference samples. CaCl2-treatment had an even stronger effect than sucrose on the above compounds except lignin. The pretreatments did not seem to affect the epidermis, hypodermis or pith.