Terms Of Impurities Research Articles

Federated-Learning-Based Synchrotron X-Ray Microdiffraction Image Screening for Industry Materials

Synchrotron X-ray microdiffraction ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> XRD) services are conducted for industrial minerals to identify their crystal impurities in terms of crystallinity and potential impurities. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> XRD services generate huge loads of images that have to be screened before further processing and storage. However, there are insufficient effective labeled samples to train a screening model since service consumers are unwilling to share their original experimental images. In this article, we propose a physics law-informed federated learning (FL) based <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> XRD image screening method to improve the screening while protecting data privacy. In our method, we handle the unbalanced data distribution challenge incurred by service consumers with different categories and amounts of samples with novel client sampling algorithms. We also propose hybrid training schemes to handle asynchronous data communications between FL clients and servers. The experiments show that our method can ensure effective screening for industrial users conducting industrial material testing while keeping commercially confidential information.

The effect of renewed melting process under electrical slag on the fatigue life of the precipitation hardened stainless steel Custom-450

The aim of this study was to investigate the effect of under electro slag re-melting (ESR) process on the fatigue behavior of GTD-450 steel used for manufacturing gas turbin blades. These parts are always at risk of failure due to fatigue. Refining of steel by ESR process is one of the most important modern methods of steelmaking in order to achieve a homogeneous structure, minimal elemental and structural segeregation, as well as reducing non-metallic impurities in terms of their number and size and most importantly their uniform distribution in the steel structure. Due to dependency of fatigue properties of steels on structural factors of steel, the role of ESR process using different slag compositions on this important property of GTD-450 steel was investigated. Microstructural studies by optical and electron microscopes showed that grain size of ESR samples were averagely 10% finer than non-ESR ones. As well as performing various mechanical tests including tensile and fatigue on samples prepared in different conditions, showed that although ESR had a minor effect on tensile properties of steel but impact energy of steel in ESR condition were averagely 16% more than non-ESR condition. Finally, the core finding of this paper is that, fatigue life of GTD-steel turbine blade produced via ESR method can be improved by 30%.

Application of a Machine Learning Approach for the Analysis of Clinical and Radiomic Features of Pretreatment [18F]-FDG PET/CT to Predict Prognosis of Patients with Endometrial Cancer

To examine the prognostic significance of pretreatment 2-deoxy-2-[18F]fluoro-D-glucose ([18F]-FDG) positron emission tomography (PET)-based radiomic features using a machine learning approach in patients with endometrial cancers. Included in this retrospective study were 53 patients with endometrial cancers who underwent [18F]-FDG PET/X-ray computed tomography (CT) before treatment. Since two different PET scanners were used, post-reconstruction harmonization was performed for all PET parameters using the ComBat harmonization method. Four clinical (age, histological type, stage, and treatment method) and 40 [18F]-FDG PET-based radiomic features were ranked, and a subset of useful features was selected based on the decrease in the Gini impurity in terms of associations with disease progression. The machine learning algorithms (random forest, neural network, k-nearest neighbors (kNN), naive Bayes, logistic regression, and support vector machine) were compared using the areas under the receiver operating characteristic curve (AUC) and validated by the random sampling method. Progression-free survival (PFS) and overall survival (OS) were assessed by the Cox regression analysis. The five best predictors of disease progression were coarseness, gray-level run length nonuniformity, stage, treatment method, and gray-level zone length nonuniformity. The kNN model obtained the best performance classifier for predicting the disease progression (AUC =0.890, accuracy =0.849, F1 score =0.848, precision =0.857, and recall =0.849). Coarseness which was the first ranked radiomic feature was selected for survival analyses, and only coarseness remained as a significant and independent factor for both PFS (hazard ratios (HR), 0.65; 95 % confidence interval [CI], 0.49-0.86; p=0.003) and OS (HR, 0.52; 95 % CI, 0.36-0.76; p<0.001) at multivariate Cox regression analysis. [18F]-FDG PET-based radiomic analysis using a machine learning approach may be useful for predicting tumor progression and prognosis in patients with endometrial cancers.

Lift force coefficient of ellipsoidal single bubbles in water

For the simulation of bubbly flows, knowledge of the lift force as an interaction between gas bubbles and a surrounding shear field is of great importance. The sign of the lift coefficient CL changes with increasing bubble size, i.e. with more pronounced bubble deformation. Beside this, impurities in terms of surface-active components are well-known to change the complete hydrodynamic behavior of a bubble even if the amount is very small. In the present work, the lift coefficient of single ellipsoidal bubbles is determined with a recently developed method, which is suitable to overcome difficulties connected to low viscous systems. In order to investigate the influence of impurities on the lift force, we conducted experiments with single bubbles of different sizes in purified, deionized and tap water. Overall, the determined lift coefficients show no difference between deionized and tap water but reveal differences to results obtained with purified water. As no significant differences in shape and velocity are found between the different water qualities, it remains unclear how the impurities cause the observed differences. For the deionized and tap water results that are more relevant in practice, a new correlation is proposed to account for the observed differences in comparison to data from the literature. It can be used to calculate CL of ellipsoidal bubbles in the investigated size range.

Factors affecting the amount of impurities when harvesting produced sugarcane with sugarcane harvester

This study aimed to determine the amount of impurities adhering to sugarcane harvested from sugarcane harvesters. A factorial experimental design was used to study the effect of three factors: sugarcane type, planting and soil type. The experiments showed that the three factors affected the quantity of impurities adhering to the sugarcane. The following types of impurities can be classified as tops at 54%, trash at 32%, and root and soil at 14%. The variance analysis was done at a significant level of 0.05, and it was found that the sugarcane type and the planting technique had an influence on the amount of tops impurities in both terms of the main factors and co-factors. The type of sugarcane was the main factor affecting the amount of trash impurities in terms of main factors; planting and soil type had an influence on the amount of trash impurities in terms of the co-factors.

Wave propagation across interfaces induced by different interaction exponents in ordered and disordered Hertz-like granular chains

We study solitary wave propagation in 1D granular crystals with Hertz-like interaction potentials. We consider interfaces between media with different exponents in the interaction potential. For an interface with increasing interaction potential exponent along the propagation direction we obtain mainly transmission with delayed secondary transmitted and reflected pulses. For interfaces with decreasing interaction potential exponent we observe both significant reflection and transmission of the solitary wave, where the transmitted part of the wave forms a multipulse structure. We also investigate impurities consisting of beads with different interaction exponents compared to the media they are embedded in, and we find that the impurities cause both reflection and transmission, including the formation of multipulse structures, independent of whether the exponent in the impurities is smaller than in the surrounding media. We explain wave propagation effects at interfaces and impurities in terms of quasi-particle collisions. Next we consider wave propagation along Hertz-like granular chains of beads in the presence of disorder and periodicity in the interaction exponents present in the Hertz-like potential, modelling, for instance, inhomogeneity in the contact geometry between beads in the granular chain. We find that solitary waves in media with randomised interaction exponents (which models disorder in the contact geometry) experience exponential decay, where the dependence of the decay rate is similar to the case of randomised bead masses. In the periodic case of chains with interaction exponents alternating between two fixed values, we find qualitatively different propagation properties depending on the choice of the two exponents. In particular, we find regimes with either exponential decay or stable solitary wave propagation with pairwise collective behaviour. For some specific interaction exponent values, we observe a new type of stable confined wave which exhibits a periodically changing wave form. These results cast light on how inhomogeneity in the contact geometry will influence solitary wave propagation along Hertz-like granular chains.

The g-theorem and quantum information theory

We study boundary renormalization group flows between boundary conformal field theories in $1+1$ dimensions using methods of quantum information theory. We define an entropic $g$-function for theories with impurities in terms of the relative entanglement entropy, and we prove that this $g$-function decreases along boundary renormalization group flows. This entropic $g$-theorem is valid at zero temperature, and is independent from the $g$-theorem based on the thermal partition function. We also discuss the mutual information in boundary RG flows, and how it encodes the correlations between the impurity and bulk degrees of freedom. Our results provide a quantum-information understanding of (boundary) RG flow as increase of distinguishability between the UV fixed point and the theory along the RG flow.

Impurity effect of Mg on the generalized planar fault energy of Al

Generalized planar fault energy (GPFE) curves are widely used to evaluate the deformation behavior of metals and alloys. In the present work, a systematic analysis of the microscopic plastic deformation mechanism of face-centered cubic Al in comparison to Cu was conducted based on GPFE curves generated via first-principles calculations. Focus has been put on the effects of Mg impurities in terms of local concentration and local atomic arrangement nearby the deformation plane, upon the GPFE curve of Al, with the aim to investigate the twinnability of Al–Mg alloys subjected to plastic deformation. It is found that Mg exhibits a Suzuki segregation feature to the stacking fault of Al, either intrinsic or extrinsic. Mg atoms residing in the stacking fault plane can decrease the intrinsic stacking fault energy γ ISFE and enhance the twinning propensity of Al. However, the γ ISFE value does not decrease monotonically with increasing Mg concentration in the alloy, and a continuous twinnability increase with increasing Mg content is not observed. It is also seen that different local concentrations and atomic configurations of Mg atoms in the vicinity of deformation plane could yield a large variation of γ ISFE and the twinning propensity of Al. It is proposed that Mg alloying cannot substantially enhance the twinning propensity of Al alloys.

Jacques Friedel and the physics of metals and alloys

This is an introduction to the theoretical physics of metals for students and physicists from other specialities. Certain simple consequences of the Fermi statistics in pure metals are first addressed, namely the Peierls distortion, Kohn anomalies and the Labb\'e-Friedel distortion. Then the physics of dilute alloys is discussed. The analogy with nuclear collisions was a fruitful starting point, which suggested one should analyse the effects of impurities in terms of a scattering problem with the introduction of phase shifts. Starting from these concepts, Friedel derived a theory of the resistivity of alloys, and a celebrated sum rule relating the phase shifts at the Fermi level to the number of electrons in the impurity, which turned out to play a prominent role later in the context of correlated impurities, as for instance in the Kondo effect. Friedel oscillations are also an important result, related to incommensurate magnetic structures. It is shown how they can be derived in various ways: from collision theory, perturbation theory, self-consistent approximations and Green's function methods. While collision theory does not permit to take the crystal structure into account, which is responsible for electronic bands, those effects can be included in other descriptions, using for instance the tight binding approximation.

Catalytic behaviour of four different supported noble metals in the crude glycerol oxidation

The activity of four different noble metals (Ag, Au, Pd and Pt) in the liquid phase oxidation of pure glycerol was confronted with the results obtained with a crude glycerol fraction, received from a large-scale biodiesel production plant. The catalysts were characterized by numerous techniques, giving insight into actual metal loading (elemental analysis by ICP and XRF), surface morphology (nitrogen absorption methods—BET and porosity), chemical state of both the support and the metal (XRD and XPS), and, finally, the metal particle size distribution (TEM microscopy). A good dispersion of totally reduced noble metal particles of a nanometric size (an average metal diameters were equal 3.5nm, 4.2nm, 4.7nm and 21.2nm for respectively Pd, Pt, Au and Ag) was accompanied with a comparable values of total metal loadings on the alumina support (from 0.95 and 0.96wt.% for Pt and Pd, up to 0.98 and 1.13wt.% for Au and Ag supported catalysts, respectively). In terms of initial reaction rate, the most active sample was the Au/Al2O3 catalyst, both using pure (12976molh−1molAu−1) or crude glycerol (1230molh−1molAu−1). However, comparison of the selectivities and conversions after 1–2h shows that the most robust and resistant catalyst – toward the impurities present in crude glycerol – is Pd/Al2O3, with a loss of conversion less than 50% (in respect to analogous reaction using pure glycerol) and almost unchanged high selectivity to glyceric acid (close to 80–90%). Ag/Al2O3 also showed a relatively high resistance to impurities in terms of glycerol conversion, but with a drastic modification of its selectivity. The activity of the two other catalysts was dramatically affected with a conversion divided by ca. 4 and even 10 for the Pt and the Au catalysts, respectively, when using crude glycerol instead of pure glycerol. Finally, the effect of each main impurity (MONG-NM, i.e., matter organic non-glycerol and non-methanol; ash; methanol; sulphur compounds) was independently studied. In any case, the sulphur compounds and MONG-NM were the impurities the most detrimental for the performances of catalysts. Thus, they should be removed in priority from crude glycerol fractions before reaction, while ashes and methanol should not be considered as completely undesirable.

Evolution of Soluble Impurities Concentrations in Industrial Phosphoric Acid during the Operations of Desupersaturation

The desupersaturation of industrial phosphoric acid is a unit operation integrated either explicitly or implicitly in the Wet Process for Phosphoric Acid production (WPPA). This operation aims to improve the acid quality by elimination or reduction of impurities, which impair the acid quality and affect the process downstream performance.Given the importance and impact of the phosphoric acid quality and its treatment on the performance of the whole production chain, we studied the operation of desupersaturation of this acid under various conditions of temperature and residence time. This allows determination, on one hand of the concentration evolution and the nature of various mineral phases of impurities present in the solution acid, and on the other hand the determination of the optimum treatment conditions of the acid to be adopted for improving production units performances. These measures can reduce the negative impacts of impurities in terms of fouling, corrosion, abrasion and produced acid quality.

The politics of purity

In Purity and Danger, Douglas theorizes purity and impurity in terms of the instantiation and disruption of a shared symbolic order. Purity/impurity discourses act, according to Purity and Danger, as a homeostatic system which ensures the preservation of this social whole, generally encoding that which threatens social equilibrium as impurity. There have been calls for new social theory on this ‘under-theorized’ topic. Presenting such further reflections, I argue that Douglas’ account is less a full explanation than a regularity. Representations of purity are only secondarily symbols of the social order. Rather, purity/impurity discourses are only associated with ‘matter out of place’ when phenomena are assessed for their relative deviation from an imputed state of ‘self-identity’: qualitative homogeneity and correspondence with their essence. Purity and impurity do more than judge self-identity, however. They can play a fundamental role in its performative construction; they are well adapted for smuggling assumptions into our discourses regarding the essence of particular phenomena and forms of subjectivity, simplifying a complex world into a stark contrast between the dangerous and the innocent, the valuable and the valueless, the necessary and the contingent, the originary and the prosthetic, the real and the apparent, and the unitary and the fragmented.

Impurity control and corrosion resistance of magnesium–aluminum alloy

In the present study, the corrosion behavior of AXJ530 magnesium alloy with different iron and manganese contents is investigated in 3.5 wt% sodium chloride solution in order to tailor the tolerance limit of Fe impurity in the magnesium alloy. Through a comprehensive phase diagram calculation and corrosion evaluation, the mechanisms for the tolerance limit of Fe in magnesium alloys are discussed. The study adds a new dimension to controlling the Mg alloy impurity in terms of alloying composition design and casting conditions.

Ritual Impurity in Tannaitic Literature: Two Opposing Perspectives

This paper examines the rabbinic concept of impurity in terms of the essence of the reality that this term implies. Did the Rabbis consider impurity to be a force of nature, or rather an abstract formalistic structure devoid of any actual existence? A review of rabbinic sources regarding corpse impurity reveals that the essential structures of tannaitic halakhah are grounded in a natural, immanent perception of impurity, which gave rise to an entire system, intricate and coherent, of “natural laws of impurity.” Layered onto this system, as a secondary stratum of sorts comprising exceptions and “addenda,” is a more subtle halakhic tapestry woven from a diametrically opposed perception. This view subjects the concept of impurity to human awareness and intention, severing it from reality and, in so doing, also stripping it of its “natural” substance.

The oxycoal process with cryogenic oxygen supply

Due to its large reserves, coal is expected to continue to play an important role in the future. However, specific and absolute CO2 emissions are among the highest when burning coal for power generation. Therefore, the capture of CO2 from power plants may contribute significantly in reducing global CO2 emissions. This review deals with the oxyfuel process, where pure oxygen is used for burning coal, resulting in a flue gas with high CO2 concentrations. After further conditioning, the highly concentrated CO2 is compressed and transported in the liquid state to, for example, geological storages. The enormous oxygen demand is generated in an air-separation unit by a cryogenic process, which is the only available state-of-the-art technology. The generation of oxygen and the purification and liquefaction of the CO2-enriched flue gas consumes significant auxiliary power. Therefore, the overall net efficiency is expected to be lowered by 8 to 12 percentage points, corresponding to a 21 to 36% increase in fuel consumption. Oxygen combustion is associated with higher temperatures compared with conventional air combustion. Both the fuel properties as well as limitations of steam and metal temperatures of the various heat exchanger sections of the steam generator require a moderation of the temperatures during combustion and in the subsequent heat-transfer sections. This is done by means of flue gas recirculation. The interdependencies among fuel properties, the amount and the temperature of the recycled flue gas, and the resulting oxygen concentration in the combustion atmosphere are investigated. Expected effects of the modified flue gas composition in comparison with the air-fired case are studied theoretically and experimentally. The different atmosphere resulting from oxygen-fired combustion gives rise to various questions related to firing, in particular, with regard to the combustion mechanism, pollutant reduction, the risk of corrosion, and the properties of the fly ash or the deposits that form. In particular, detailed nitrogen and sulphur chemistry was investigated by combustion tests in a laboratory-scale facility. Oxidant staging, in order to reduce NO formation, turned out to work with similar effectiveness as for conventional air combustion. With regard to sulphur, a considerable increase in the SO2 concentration was found, as expected. However, the H2S concentration in the combustion atmosphere increased as well. Further results were achieved with a pilot-scale test facility, where acid dew points were measured and deposition probes were exposed to the combustion environment. Besides CO2 and water vapour, the flue gas contains impurities like sulphur species, nitrogen oxides, argon, nitrogen, and oxygen. The CO2 liquefaction is strongly affected by these impurities in terms of the auxiliary power requirement and the CO2 capture rate. Furthermore, the impurity of the liquefied CO2 is affected as well. Since the requirements on the liquid CO2 with regard to geological storage or enhanced oil recovery are currently undefined, the effects of possible flue gas treatment and the design of the liquefaction plant are studied over a wide range.

Enantiomeric Separation of Docetaxel Starting Material by Chiral LC Using Amylose Based Stationary Phase

The present work narrates an LC method for determination of enantiomeric purity of (4S,5R)-3,5-oxazolidinedicarboxylic acid 2,2-dimethyl-4-phenyl-3-(1,1-dimethylethyl) ester, which is a key starting material of docetaxel, an antineoplastic agent and belongs to the taxoid family. Resolution between enantiomers was achieved ≥4.0 within 30 min on Chiralpak AD-H (250 mm × 4.6 mm) column using n-hexane, 2-propanol, ethanol and trifluoroacetic acid (97.5, 1.5, 1.0, 0.15 v/v) as mobile phase at a flow rate of 1.0 mL min−1 at 25 °C. The detection was made at 215 nm using UV detection. The effects of 2-propanol, ethanol and temperature on enantioselectivity and resolution of enantiomers were evaluated. The method was validated for (4R,5S)-enantiomeric impurity in terms of accuracy, precision and linearity in the range of 0.5–5 μg mL−1 and the correlation coefficient was >0.999. The recoveries were 93.2–104.4%. The limits of detection (LOD) and quantification (LOQ) of unwanted (4R,5S)-enantiomer was 0.1 and 0.5 μg mL−1. The method was found to be suitable for rapid quantification of (4R,5S)-enantiomer of docetaxel starting material.

X-Ray Characterization of Ag Impurities in Na&lt;sub&gt;1-x&lt;/sub&gt;Ag&lt;sub&gt;x&lt;/sub&gt;Cl

The alkali halide Na1-xAgxCl, with two different compositions (x = 0.03 and 0.10), was studied with regard to the Ag impurities in terms of the bonding and electron density distribution. X-ray single crystal data sets have been used for the purpose. The present analysis focused on the electron density distribution and hence the interaction between the atoms is clearly revealed by maximum entropy method (MEM) and multipole analyses. The bonding in these systems has been studied using two-dimensional MEM electron density maps on the (100) and (110) planes and onedimensional electron density profiles along the [100], [110] and [111] directions. The mid-bond electron densities between atoms in these systems are found to be 0.175 e/Å3 and 0.183 e/Å3, respectively, for Na0.97Ag0.03Cl and Na0.90Ag0.10Cl. Multipole analysis of the structure has been performed for these two systems, with respect to the expansion/contraction of the ion involved.

The geochemistry of gem opals as evidence of their origin

Seventy-seven gem opals from ten countries were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) through a dilution process, in order to establish the nature of the impurities. The results are correlated to the mode of formation and physical properties and are instrumental in establishing the geographical origin of a gem opal. The geochemistry of an opal is shown to be dependant mostly on the host rock, at least for examples from Mexico and Brazil, even if modified by weathering processes. In order of decreasing concentration, the main impurities present are Al, Ca, Fe, K, Na, and Mg (more than 500 ppm). Other noticeable elements in lesser amounts are Ba, followed by Zr, Sr, Rb, U, and Pb. For the first time, geochemistry helps to discriminate some varieties of opals. The Ba content, as well as the chondrite-normalized REE pattern, are the keys to separating sedimentary opals (Ba > 110 ppm, Eu and Ce anomalies) from volcanic opals (Ba < 110 ppm, no Eu or Ce anomaly). The Ca content, and to a lesser extent that of Mg, Al, K and Nb, helps to distinguish gem opals from different volcanic environments. The limited range of concentrations for all elements in precious (play-of-color) compared to common opals, indicates that this variety must have very specific, or more restricted, conditions of formation. We tentatively interpreted the presence of impurities in terms of crystallochemistry, even if opal is a poorly crystallized or amorphous material. The main replacement is the substitution of Si 4+ by Al 3+ and Fe 3+. The induced charge imbalance is compensated chiefly by Ca 2+, Mg 2+, Mn 2+, Ba 2+, K +, and Na +. In terms of origin of color, greater concentrations of iron induce darker colors (from yellow to “chocolate brown”). This element inhibits luminescence for concentrations above 1000 ppm, whereas already a low content in U (≤ 1 ppm) induces a green luminescence.

Transport of strong-coupling polarons in optical lattices

We study the transport of ultracold impurity atoms immersed in a Bose–Einstein condensate (BEC) and trapped in a tight optical lattice. Within the strong-coupling regime, we derive an extended Hubbard model describing the dynamics of the impurities in terms of polarons, i.e. impurities dressed by a coherent state of Bogoliubov phonons. Using a generalized master equation based on this microscopic model, we show that inelastic and dissipative phonon scattering results in (i) a crossover from coherent to incoherent transport of impurities with increasing BEC temperature and (ii) the emergence of a net atomic current across a tilted optical lattice. The dependence of the atomic current on the lattice tilt changes from ohmic conductance to negative differential conductance within an experimentally accessible parameter regime. This transition is accurately described by an Esaki–Tsu-type relation with the effective relaxation time of the impurities as a temperature-dependent parameter.

Impurity and quaternions in nonrelativistic scattering from a quantum memory

Models of quantum computing rely on transformations of the states of a quantum memory. We study mathematical aspects of a model proposed by Wu in which the memory state is changed via the scattering of incoming particles. This operation causes the memory content to deviate from a pure state, i.e. induces impurity. For nonrelativistic particles scattered from a two-state memory and sufficiently general interaction potentials in (1+1) dimensions, we express impurity in terms of quaternionic commutators. In this context, pure memory states correspond to null hyperbolic quaternions. In the case with point interactions, the scattering process amounts to appropriate rotations of quaternions in the frequency domain. Our work complements previous analyses by Margetis and Myers (2006 J. Phys. A 39 11567).