Impurities In Materials Research Articles

Electrochemical hydrogen detection in DONES loop materials

• Design of an electrochemical sensor adequate to RAMI conditions of IFMIF-DONES. • Determination of hydrogen in liquid lithium. • Online electrochemical muliplex monitoring. • Modular design for different extended approaches (impurities, electrochemical procedures, sizes). The radiation-induced degradation of materials in fusion systems is planned to be investigated in IFMIF-DONES ( International Fusion Materials Irradiation Facility - DEMO Oriented NEutron Source ), where fast neutrons are produced by a reaction of deuteron-beams with a liquid lithium target. A by-product as critical impurity is hydrogen, which might affect the reliable and safe operation of the IFMIF-DONES loops. Therefore, an important issue is the measurement and control of the hydrogen impurity concentrations in liquid lithium. Initially, a practically applicable direct measurement of hydrogen concentrations in lithium facilities did not exist. However, one promising approach to manage this issue is based on the electrochemistry of the DONES materials The developed Electro-Chemical Hydrogen Sensor for Liquid Lithium (ECHSLL) allows the measurement of the electromotive Force (EMF) between a reference materials system and the loop lithium melt, and thus the monitoring of the hydrogen impurity concentrations. This article will show backgrounds of non-metallic impurities in liquid metal materials and the specific material stabilities within DONES. Liquid lithium is a very reactive material. Therefore critical issuesareviable materials compatibilities, the interactions with hydrogen and the transport behaviour of H-ions in electrolytes at the applied temperatures. Further issues are also the syntheses of the electrochemical materials, as hydrogen conducting electrolytes, reference electrode systems and the different procedures (heat treatments and conditioning steps). The tests showed the functionality of the developed H-sensor. Beyond that, the used material combinations exhibited reliable behaviour in melts under harsh conditions. Hence, the most critical aspect (stability of the sensor materials in the Li-melt) has been resolved by using niobium sensor heads. The observed experimental EMF potentials are in good accordance compared with calculated models, also in long-time experiments.

Influence of metal codeposition on the growth and orientation of nanoripple structure during ion bombardment

Surface engineering to tune the surface characteristics for the enhancement of a system is an emerging area of research in terms of its immense technological applications and basic scientific understanding. The ion beam sputtering technique in combination with cosputtered material deposition to form various structures is found to be a very effective bottom-up approach to modify the surface morphology of a material. In this paper, a theoretical model is developed for ripple evolution of a flat elemental surface which is subjected to erosion by ion bombardment at off-normal incidence with concurrent deposition of some impurity or foreign materials. The orientation of the ripple wave vector thus produced exhibits a directional dependence behavior on the projection of both the ion beam and the foreign elements on the surface. The compound formation at the near-surface depth is considered to be the key assumption for inducing such patterns on the surface. The theoretical prediction is realized in the experimental work demonstrated herein. Stainless steel is used as a cosputtering target during irradiation of Si at ${30}^{\ensuremath{\circ}}$ incidence by a low-energy ${\text{Ar}}^{+}$ ion beam. The ripples that so emerge possess a wave vector lying oblique to the direction of the ion beam and impurity. The development of such morphological instability is attributed to the reaction between Fe and Si, which gives rise to a compound with an erosion rate lower than that of Si. Thus, the formation of the ${\text{FeSi}}_{2}$ bond, which is interpreted as being a crucial criterion for pattern evolution, agrees well with the theory, making it quite efficient and widely acceptable.

Univariate data analysis versus multivariate approach in liquid chromatography. An application for melamine migration from food contact materials

The aim of this work is focused on the melamine migration from food contact materials (FCMs), considering data obtained from univariate analysis versus that obtained from multivariate approach in liquid chromatography coupled to diode array detector.Plastic food contact materials are made from monomers and additives. Moreover, non-intentionally added substances (NIAS) can be part of the composition of the FCM: raw material impurities or process by-products, inks or adhesives.Any compound present within a FCM can migrate to foodstuff. Specific migration of some substances from plastic FCMs to food/simulant is limited by European legislation in force (Commission Regulation No 10/2011).Quantification of analytes in migration samples through a univariate analysis could lead to erroneous results. As an example, in liquid chromatography NIAS can interfere when coeluting with analytes or when they have close retention time. In that case, an overestimation would happen and the verification of the compliance of the specific migration limit (SML) of a substance would be incorrect.A solution to the problem can be found in the application of a chemometric tool with the second-order advantage, which allows the unequivocal identification of analytes. Specifically, for this work, PARAFAC/PARAFAC2 decomposition technique along with tensors arranged from HPLC-DAD data of migration (test and kinetics) samples were used for the identification and quantification of melamine.Results of melamine quantity found in migration samples from five types of melaware by means of a multivariate approach were compared to results obtained with a univariate data analysis carried out with values of chromatographic peak area as response. The comparison reveals that in test samples, univariate analysis supposes an overestimation in the quantity of melamine of 30 % on average, with respect of the concentration obtained from the multivariate approach. Besides, in kinetics samples it is remarkable that for one migration cycle the melamine found was 10 times above the one that obtained with PARAFAC decomposition.Summing up, multivariate data analysis of migration samples supposes a great advantage in order to comply with the established regulation about migrants and to decrease the false non-compliant results.

Superfast crystalline powder synthetic strategy toward scale-up of perovskite solar cells

Commercialized perovskite solar cells (PSCs) are limited owing to the high cost of high-purity PbI2 (99.999%), raw material batch variance, and stoichiometric deviation. Here, we report a rapid antisolvent-assisted crystallization (RAC) method to speedily obtain high-grade perovskite powders from low-purity and inexpensive PbI2 (98%) raw materials. Without long-term stirring or employing any toxic antisolvent, RAC is a cost-efficient and environmentally friendly method with a high yield of over 92%. By precise characterization, the RAC method can reduce the impurities in raw materials that minimize the impurity-induced shallow-level trap density and hence the non-radiative recombination of carriers. As per the results, over 12% increase in power conversion efficiency (PCE) is obtained from low-grade raw materials, resulting in a champion PCE of 20.5% for small-area MAPbI3 PSCs and certified 18.35% for doctor-bladed 6.75-cm2 mini-module. With a reduction in material cost and a considerable increase in efficiency, RAC is a suitable alternative to the mass-produced, commercially available large-scale PSC.

Measurement uncertainty for detection of visual impurities in granular feed and food materials in relation to the investigated amount of material

The presence is regulated of visually detectable seeds from a selection of toxic plants and fungi mycelium bodies (sclerotia) in feed (Directive 2002/32/EC) and in food (Regulation (EC) 1881/2006). Homogenisation as typical for chemical analyses is not applicable, and dedicated approaches are needed for visual examination methods. Visual methods require two parameters to characterise measurement uncertainties for both unit counts and unit weights. A new approach is to divide approximately 2 kg of sample material into four subsamples of approximately 500 g and to separately examine the four subsamples for numbers and particle weights of seeds or sclerotia. This study is the first to produce datasets on inhomogeneity among subsamples of a sample for visually detectable undesirable substances. Analytical thresholds were calculated from a simulation model and bootstrap procedures based on our data. The analytical thresholds assuring a controlled false-negative rate of 5% for decisions in compliance with legal limits depend on the diversity of the unit counts and weights, the level of the legal limit and the amount of material examined initially in the step-wise approach, either one or two subsamples. A procedure is proposed for examination in practice where only two subsamples, or alternatively even only one subsample, would be examined. If the resulting level of contamination exceeds the relevant threshold additional subsamples need to be examined as well. In most of the investigated cases, analytical thresholds could be established for the examination of just one subsample (500 g) taken from a sample of 2 kg. However, for ergot sclerotia in food with a legal limit of 200 mg kg−1, at least two subsamples (1000 g) need to be examined in the first step. Other groups of visually detectable undesirable substances exist which need further attention.

Analisis Elektrik Motor Penggerak TBS (Traveling Band Screen) PLTU

<p><em>The Traveling Band Screen (TBS) is a means of filtering trash and sea creatures such as jellyfish in the PLTU Intake area. FFB filters waste by rotating the screen, then the waste is sprayed using backwash water so that the filtered waste can fall into the disposal route. The amount of impurity material stuck on the screen has an impact on the decrease in flow capacity, thus affecting the increase in the load of the TBS motor and causing the TBS to become overloaded so that the PLTU will Shut Down, so an analysis is needed to determine the electric ability of the motor drive of the TBS system to block the screen. One of the analyzes carried out is observing the optimal load of the motor with power: 2/1 HP, Rotation: 1500 rpm with reduction ratio: 1500: 1 to determine the load blockage by using the SEW Eurodrive motor manufacturer. From the results of the load analysis, the existing motor specifications are only able to operate for a screen clogging percentage of less than 13.6%.</em></p>

Concentration of Ammonia Pollution in Madura Traditional Salt Production Water

Ammonia (NH3) is one of the impurities in salt-producing water, which is often found in the traditional salt ponds of the Madurese. The purpose of this study was to determine the concentration of ammonia contamination as an impurity in salt production process water from raw water, reservoir ponds, evaporator ponds to geomembrane crystallizer ponds when salt production takes place in the salt ponds of Tanjungan Village, Bangkalan Regency. Determination of ammonia concentration using the phenate method based on SNI 06-6989.30-2005 with a spectrophotometer reading tool (UV-2700 Serial No. A11674900027) at a wavelength of 420 nm. The average concentration of ammonia as an impurity in raw materials in traditional pond ponds in Tajungan village, namely raw water is 2.31±0.24 mg/L, reservoir ponds are 2.56±0.57 mg/L, evaporator ponds are 2, 39±0.84 mg/L and the geomembrane crystallizer ponds are 1.37±0.09 mg/L. The highest average ammonia concentration was found in the reservoir ponds raw saltwater sample, while the lowest concentration was found in the geomembrane crystallizer ponds sample. The high average ammonia concentration in the salt ponds of Tajungan Village, Bangkalan Regency indicates that all raw saltwater in these ponds is contaminated with ammonia. The high concentration of ammonia in the salt ponds may be due to the entry of household waste. Keywords: (NH3), raw water, reservoir ponds, evaporation ponds, geomembrane crystallizer ponds

Copper impurity of iron raw material contributes to improved cell culture performance.

Cell culture medium (CCM) formulations are chemically defined to reduce lot‐to‐lot variability and complexity of the medium while still providing all essential nutrients supporting cell growth and productivity of various cell lines. However, raw material impurities may still introduce variations and inconsistencies to final CCM formulations. In one of our previous studies (Weiss et al. Biotechnol Prog. 2021;37(4):e3148), we have demonstrated the impact of iron raw material impurity on Chinese hamster ovary (CHO) cell performance and critical quality attributes (CQAs) of recombinant proteins within the Cellvento® 4CHO CCM platform by identifying manganese impurity as the main root cause for improved cell performance and altered glycosylation profiles. This study sought to investigate the impact of iron raw material impurities within another medium platform, namely EX‐CELL® Advanced CHO Fed‐Batch‐Medium. As opposed to previously published results, in this platform, copper instead of manganese impurity present within the used ferric ammonium citrate (FAC) iron source was responsible for an improved cell performance of a CHOZN® cell line and a slight difference in CQAs of the produced recombinant protein. The use of tightly controlled raw material specifications or the use of low impurity iron sources is therefore crucial to minimize the impact of impurities on cell performance in any CCM platform and thereby guarantee consistent and reproducible cell culture processes.

Development of a derivatization RP-HPLC method for determination of sulfuryl chloride in chlorosulfonic acid for gefapixant citrate manufacture

Control of process impurities during manufacturing of drug substance is critical to ensure quality and process robustness. During commercial process development for the gefapixant citrate drug substance, several process impurities were found to derive from sulfuryl chloride, an impurity in the raw material, chlorosulfonic acid (CSA). This made controlling the CSA quality essential for commercial production of this drug substance. Various direct analysis methods were evaluated and found unsuitable because of the highly reactive nature and structural similarity of sulfuryl chloride and CSA. Therefore, a robust derivatization reversed-phase high performance liquid chromatography (RP-HPLC) method was developed and validated to accurately quantify sulfuryl chloride in CSA. The derivatization method was utilized to evaluate many CSA batches from different commercial suppliers and to establish a correlation between sulfuryl chloride levels in CSA and the levels of process impurities in downstream materials. The methodology described herein informed the development of setting the specification on sulfuryl chloride for CSA to ensure a robust process for manufacturing high-quality gefapixant citrate drug substance. The derivatization method was successfully validated and transferred to the commercial commodity supplier for release testing of CSA as a raw material for gefapixant citrate commercial campaigns.

Study on the Activity of Metakaolin Produced by Traditional Rotary Kiln in China

This paper analyzed the activity of coal-based metakaolin and non-coal-based metakaolin (ordinary metakaolin) commonly used in the Chinese market. The content of kaolin was detected by XPF. The phases of kaolin, metakaolin and corresponding alkali-excited reactants were detected by XRD. The contents of Al (IV), Al (V) and Al (VI) in kaolin and metakaolin were analyzed by 27Al NMR. The micromorphology of kaolin and metakaolin were observed by SEM. The water-resistance of alkali-activated metakaolin was tested by immersion experiment. The results showed that a lot of corundum and quartz were present in the coal-based metakaolin, which was caused by over calcination. Furthermore, large amounts of sillimanite, quartz and cristobalite existed in ordinary metakaolin with a low content of amorphous aluminum silicate, which was caused by excessive impurities in the raw materials and over calcination. These crystalline substances could not react in an alkali solution, and their existence reduced the activity of the two metakaolins. Both of the two metakaolin production methods need to be improved to increase the activity.

Self-Defense Effects of Ti-Modified Attapulgite for Alkali-Resistant NOx Catalytic Reduction.

Nowadays, the serious deactivation of deNOx catalysts caused by alkali metal poisoning was still a huge bottleneck in the practical application of selective catalytic reduction of NOx with NH3. Herein, alkali-resistant NOx catalytic reduction over metal oxide catalysts using Ti-modified attapulgite (ATP) as supports has been originally demonstrated. The self-defense effects of Ti-modified ATP for alkali-resistant NOx catalytic reduction have been clarified. Ti-modified ATP with self-defense ability was obtained by removing alkaline metal cation impurities in the natural ATP materials without destroying its initial layered-chain structure through the ion-exchange procedure, accompanied with an obvious enrichment of Brønsted acid and Lewis acid sites. The self-defense effects embodied that both ion-exchanged Ti octahedral centers and abundant Si-OH sites in the Ti-ion-exchange-modified ATP could effectively anchor alkali metals via coordinate bonding or ion-exchange process, which induced alkali metals to be immobilized by the Ti-ion-exchange-modified ATP carrier rather than impair active species. Under this special protection of self-defense effects, Ti-ion-exchange-modified ATP supported catalysts still retained plentiful acidic sites and superior redox ability even after alkali metal poisoning, giving rise to the maintenance of sufficient NHx and NOx adsorption and the subsequent efficient reaction, which in turn resulted in high NOx catalytic reduction capacity of the catalyst. The strategy provided new inspiration for the development of novel and efficient selective catalytic reduction of NOx with NH3 (NH3-SCR) catalysts with high alkali resistance.

Determination of Cyclophosphamide Impurity in Raw Materials and Preparations by Ion Chromatography

Determination of Cyclophosphamide Impurity in Raw Materials and Preparations by Ion Chromatography

Model Predictive Control with Integrated Model Reduction for a Continuous Lactide Ring-Opening Polymerization Process.

Poly(lactic acid) production has received increasing attention, mainly due to its inherent biodegradable thermoplastic properties and to its renewable-resource-based composition. This process is affected by changes in the operating conditions and by raw material impurities which influence the reaction rate and degrade the polymer properties. As the system model is multivariable with coupled dynamics and constraints, linear model predictive control (LMPC) is employed here. A model reduction technique is proposed to obtain an approximate linear representation of the nonlinear system around the operating point to minimize the calculation cost of the controller. The proposed LMPC approach is validated by simulation and is compared to a proportional-integral controller and a nonlinear model predictive control. It is found that LMPC has a superior performance in terms of off-spec time when a disturbance occurs in the feed, and it can restore the target conditions better and faster.

Urbach Energy and Open-Circuit Voltage Deficit for Mixed Anion-Cation Perovskite Solar Cells.

The Urbach energy indicating the width of the exponentially decaying sub-bandgap absorption tail is commonly used as the indicator of electronic quality of thin-film materials used as absorbers in solar cells. Urbach energies of hybrid inorganic-organic metal halide perovskites with various anion-cation compositions are measured by photothermal deflection spectroscopy. The variation in anion-cation composition has a substantial effect on the measured Urbach energy and hence the electronic quality of the perovskite. Depending upon the compositions, the Urbach energy varies from 18 to 65 meV for perovskite films with similar bandgap energies. For most of the perovskite compositions studied here including methylammonium (MA) + formamidinium (FA)-based Pb iodides, mixed Sn + Pb narrow-bandgap perovskites with low or intermediate Sn contents, and wide-bandgap FA + Cs- and I + Br-based perovskites, the correlation between the Urbach energy of the perovskite thin film and open-circuit voltage (VOC) deficit for corresponding solar cells shows a direct relationship with reduction of the Urbach energy occurring with a beneficial decrease in the VOC deficit. However, due to issues related to material quality, impurity phases and stability in laboratory ambient air, and unoptimized film processing techniques, the solar cells incorporating Cs-based inorganic and mixed Sn + Pb perovskites with a higher than optimum Sn content show a higher VOC deficit even though the corresponding films show a lower Urbach energy.

Upravljanje otpadnom livačkom šljakom u skladu sa principima cirkularne ekonomije

Waste foundry slag, which is formed in the process of melting iron and is collected from the mouths of electric arc furnaces, is stored in all foundries in Serbia in temporary landfills, usually within the factory. Given the large amounts of waste slag, there is a need for a permanent solution to this problem. As one of the solutions, the possibility of depositing foundry slag as a buffer base under the concrete cover is imposed. In order to dispose of this type of waste, appropriate geomechanical tests of the waste in question were performed. It was concluded that waste casting slag, without impurities of piece materials, ground to a granulation below 10 mm, stored so as not to contaminate with hydrocarbons can be used to make the road bed and make the lower bearing buffer layer in the granulation below 31.5 mm. In this way, the system of waste management and treatment as a material resource based on scientific knowledge and procedures and in accordance with the principles of circular economy will be improved.

Effect of B2O3 additive on the properties of ZnS-Ge system and the resulting thin-film coatings

The effect of B2O3 additive to ZnS and ZnS-Ge system on their properties and parameters of thin-film coatings obtained from them has been studied. The essence of the additive is the binding of ZnO in Zinc sulfide, which has a negative effect due to the interaction with the evaporator material. According to X-ray diffraction, the introduction of B2O3 additive to ZnS results in the disappearance of the wurtzite phases (β-ZnS and ZnO). There is also a change in the IR spectra, in which reveal the bands at ≈300 cm−1 and 415 cm−1, which correspond to the valence vibrations of the Zn-S and Zn-O bonds, respectively. It is established that the addition of B2O3 noticeable improves the technological mode of evaporation in vacuum of materials due to the increase of their volatility. The reflection spectra of thin films of undoped and doped ZnS indicate a certain increase in the refractive index of the latter, while in the ZnS-Ge system such a difference is not observed. The mechanical durability of coatings increases especially significantly - more than 10 times for ZnS and more than 2 times - for the ZnS-Ge system. Therefore, the use of B2O3 as an additive has proved to be an effective method for minimizing the effects of oxide impurities in chalcogenide materials on the properties of thin-film coatings.

Hydrothermal synthesis of Siliceous Beta Zeolite by an inorganic cation-driven strategy and its crystallization mechanism

Siliceous Beta zeolite and its metal-containing counterparts are effective adsorption and catalysis materials. To develop facile and efficient synthesis strategy would facilitate their large-scale production and application. Herein, we report the fluoride-free hydrothermal synthesis of siliceous Beta achieved by an inorganic cation-driven strategy. It is found that the types of inorganic cations are more critical than anions in determining the product phase. Inorganic cations with smaller sizes (such as Li+, Na+ and Mg2+) facilitate the synthesis of siliceous Beta, while the larger ones (such as K+, Ca2+ and NH4+) tend to give rise to impurity or amorphous materials. Crystallization mechanism investigation based on the Na+-added system revealed that inorganic cations can effectively promote the fast polymerization of SiO2 colloids at the initial stage. The crystallization occurs on the polymerized composites, yielding siliceous Beta with high solid yield. The resultant material is well characterized, which possesses few framework defects, high hydrophobicity and large adsorption uptake for toluene (one of the common volatile organic compounds). Breakthrough experiments further evidence the dynamic toluene adsorption capacity of the material is 24% higher than that of siliceous Beta synthesized by fluoride route.

Effect of dopant on piezoelectric and dielectric properties of thin films Bi-=SUB=-3.25-=/SUB=-La-=SUB=-0.75-=/SUB=-Ti-=SUB=-3-x-=/SUB=-A-=SUB=-x-=/SUB=-O-=SUB=-12-=/SUB=- (A --- Mn, Zr, Nb)

It is shown that microstructure, dielectric and piezoelectric properties change in films based on lanthanum-substituted bismuth titanate (BLT) depending on the alloying impurity material, which leads to changes in coercive voltage, internal displacement field and control coefficient. Keywords: lead-free ferroelectric films, bismuth titanate, electrophysical properties, capacitance-voltage characteristics, piezoresponse force microscopy.

On Ultra-High Dilutions: Global Effects Caused by Minimal Quantities

On Ultra-High Dilutions: Global Effects Caused by Minimal Quantities

Effect of co-addition of WC and MoSi2 on the microstructure of ZrB2–SiC–Si composites

In this paper, ZrB2–SiC–Si-based ceramic composites with WC and MoSi2 additives were fabricated using SPS method and their densification behavior was investigated by phase and microstructural studies. During the SPS process and according to the prevailing conditions, WC and MoSi2 additives reacted with the surface oxide impurities of the main raw materials. As a result of these reactions and the decomposition of some raw materials, a series of oxide liquid phases formed, which were often Si-based, and due to their good fluidity, undissolved and free elements such as Zr, Mo and W moved to open porosities and grain boundaries. According to the established thermodynamic conditions, binary solid solutions and new phases such as MoB, ZrC and WB formed. The synthesis of such phases boosted the densification of the composites due to the fact that they formed in porosities or voids between the main grains. The results showed that the sample doped with 2.5 vol% WC and 2.5 vol% MoSi2 had the highest relative density (about 99%). Meanwhile, microstructural studies showed that homogeneous and dense parts can be achieved by SPS technology.