Poor Homogeneity Research Articles

Two-Step Solid State Synthesis of Medium Entropy LiNi0.5Mn1.5O4 Cathode with Enhanced Electrochemical Performance

Solid state reaction is widely used in the synthesis of electrode materials, due to its low cost and good scalability. However, the traditional solid-state reaction is not suitable for the synthesis of materials with multiple elements, such as high entropy or medium entropy materials, due to the poor homogeneity of raw material mixing. Here, we prepared multi-element doped LiNi0.5Mn1.5O4 (medium entropy) cathode material by two step solid state reaction. X-ray diffraction and Raman image show that the homogeneity of multi-element doped LiNi0.5Mn1.5O4 cathode has been greatly improved with this two-step method. As a result, the electrochemical performance is greatly improved, comparing to traditional solid-state reaction. First, the specific capacity at 0.1 C is increased from 126 mAh/g to 137 mAh/g. With a high current density of 10 C, the specific capacity is even increased from 64 mAh/g to 89 mAh/g with this two-step method. Second, the cycle stability is enhanced, with capacity retention of 86% after cycling at 1 C for 500 times (vs. 71% for the one-step method).

Assessment of lignin and extractive content based models used in estimation of higher heating value of lignocellulosics: Use of model mixtures

Cellulose, lignin and extractive material are mixed in certain proportions by having isolated from lignocellulosic materials, such as Zeyrek stem, hazelnut shell and Scotch pine, respectively. Their higher heating values (HHVs) are determined by using a bomb calorimeter system. Estimated HHVs are calculated by applying these mixture ratios to some Multiple (Non)-Linear Regression (M(N)LR) and Artificial Neural Network (ANN) models from the literature. MLR3 model is developed from the data of this study and this model reveals the highest R2 (0.974), lowest MAPE (0.012) and RMSE (0.278) values. The closest estimation accuracy to the MLR3 model is obtained from MLR2 (R2:0.972, MAPE:0.066 and RMSE:1.714) in the comparative analysis. MNLR and ANN equations containing quadratic terms are found to show deviations up to 132.6% (ANN3). It is attributed to the lower size and poor homogeneity of the individual group of samples from which model equations are developed.

Two-Dimensional Continuous Model in Bimolecular Reactive Transport

In this work, a continuum 2D model is proposed to study the interaction at the interface of reactive transport processes in porous media. The analysis of the segregation produced by poor reactant homogenization at the poral scale is addressed by a parametric heuristic model that considers the relative gradient of the reacting species involved in the process. The micro inhomogeneities are incorporated by means of longitudinal and transversal mechanical dispersion coefficients. A two-dimensional continuous model for the bimolecular reactive transport is considered where modelling parameters are estimated numerically from experimental data. A competitive effect between segregation and dispersion is observed that is analyzed by means of numerical experiments. The two-dimensional model reproduces properly both the total mass of the product as well as its increase with the velocity of flow and the inhomogeneity of the advanced front. The methodology used is simple and fast, and the numerical results presented here indicate its effectiveness.

Investigation of velocity distribution in channels and chambers of the electrostatic precipitator at TPP Nikola Tesla Unit A1

To achieve the optimum dust removal performance of an electrostatic precipitator, the flue gas should be distributed uniformly over its vertical cross-section. The flow in the upstream flue gas ducts has a significant influence on the downstream gas distribution in the chamber of the precipitator. This paper presents the results of homogeneity assessment of velocity distribution in the ducts and vertical cross-sections of the electrostatic precipitator of Unit A1 at the Nikola Tesla thermal power plant in Obrenovac. The measurements confirmed that the reconstruction of the vertical chamber at the front of the precipitator, which was carried out during the overhaul in 2020, effectively solved the problem of the original asymmetric arrangement of the vertical flue gas ducts. Nevertheless, the analysis revealed poor homogeneity of the flow field through the chambers. Therefore, additional measures must be taken to increase the dust removal efficiency of the precipitator.

Design and Application of Self-consolidating Concrete in Nigeria: A Review Paper

The design and application of Self-Consolidating Concrete (SCC) is limited in building and civil engineering projects in Nigeria due to the absence of self-consolidating concrete manufacturers, limited availability of some raw materials such as limestone powder, silica fume, air entrainment, metakaolin, and high cost of synthetic cementitious materials [1]. However, review of literatures revealed the potentials of locally available cementitious materials in improving the properties of universal concrete but its inclusion in SCC design has not been fully explored. The advantages of using Self-Consolidating Concrete (SCC) is not only limited to its durability but also prominent for mitigating problems of poor segregation, consolidation and homogeneity in congested reinforced concrete structures. Hence, this research reviewed various designs of SCC in Nigeria to enhance the existing knowledge and to create awareness about innovative methods of concrete design and possible areas of applications self-consolidating concrete in Nigeria construction industry. The findings from reviews indicated that lack of awareness, limited research data and instrumentation on SSC production has been the major setback in it applications in Nigeria. Conclusively, Nigeria Construction industry as one of largest sector of economy can benefit from the global market growth of self-consolidating concrete through its design and application.

Evaluating reclaimed asphalt mixture homogeneity using force chain transferring stress efficiency

Numerous studies have demonstrated a direct link between the homogeneity of asphalt mixture and the rutting performance, water stability, tensile strength, and service life of the asphalt pavement. Due to the existence of RAP clusters, poor homogeneity of the recycled asphalt mixtures is more severe than natural ones. However, previous studies have mainly focused on analyzing the distribution of aggregates, ignoring the transfer of the internal stress in the mixture. This paper proposed a novel approach for the analysis of the homogeneity of recycled asphalt mixture using the efficiency of force chain transferring stress. Therefore, to prepare gyratory compacted samples, diabase in green color was used as the virgin aggregate and marble in white color as the RAP aggregate. Moreover, to obtain the vertical section images, the samples were cut and processed by digital image processing (DIP). This included distinguishing the virgin and RAP aggregates by global gray threshold segmentation, adding asphalt film around the aggregates, and constructing a force chain network relied on the aggregate contact information. Also, the intensity of the force chain was determined using the finite element method (FEM). In addition, the efficiency of force chain transferring vertical stress (ETVS) was introduced and the homogeneity index D of the recycled asphalt mixture was proposed based on the variation coefficient of ETVS. Furthermore, uniaxial compression tests were carried out to mathematically analyze the homogeneity index D proposed in this paper and the homogeneity index D′ proposed based on the aggregate area ratio in previous studies. The obtained result showed that the homogeneity index D increased first and then decreased with the increase of RAP content. Moreover, the correlation analysis demonstrated the compressive performance of the mixture to be mainly reflected by the homogeneity index D. The correlation coefficients of the compressive strength and the compressive resilient modulus were found to be 0.9010 and 0.8464, respectively. Finally, the homogeneity index D′ was observed to mainly reflect the stability of the compressive performance of the mixture, with the correlation coefficients of the variation coefficient of the compressive strength and the compressive resilient modulus of 0.8745 and 0.8869, respectively.

Influence of the solid titanium source on the activity of La1−xTixFeO3 photo-CWPO catalysts under UV-A light

In the search for more efficient low-temperature catalysts able to oxidise biorecalcitrant pollutants in water, the selective substitution of La3+ by Ti3+ cations was reported to boost the UV-A light driven activity of LaFeO3 orthoferrites as H2O2-mediated photo-CWPO catalysts. La1−xTixFeO3 catalysts with 0 < x < 0.11 were obtained by a modified Pechini sol–gel route via the addition of a solid source of titanium during the synthesis. By using a span of crystallized and amorphous TiO2, the influence of the titanium source on the substitution rate in the orthoferrite network and on the performances of the catalysts under UV-A light was demonstrated using the degradation of 4-chlorophenol as test reaction. The amorphous content of the TiO2 precursor is proposed to be the key factor driving the substitution of La3+, the largest substitution of 11 % being obtained using a dried sol-gel TiO2 precursor. We suggest that the substitution proceeds during the thermal treatment via a solid-solid diffusion between TiO2 and the amorphous LaFeO3 before it crystallises. The catalyst robustness was influenced by the TiO2 nature. Small size Ti-LaFeO3 crystallites strongly lowered or blocked the Fe release, while no improvement was observed for large size crystallites vs. the pristine material, what was associated to a poor homogenization of the titanium in the network. We showed that the mineralization activity was proportional to the substitution rate of La1−xTixFeO3 catalysts, while a similar relationship could be drawn for the degradation activity only in the case of highly robust catalysts with pure heterogeneous surface reactions.

Non-destructive Evaluation of Powder Mixing for Food Processing Industries

Food and beverage (F&amp;amp;B) fast-moving consumer goods (FMCG) contribute a major portion of global food loss and waste in the food supply chain in the form of food loss and package defect-induced waste. Food products pass through several processing lines including, mixing, filling, dispensing, sealing, and packaging before dispatch. To save on the cost and footprint to build additional machinery, producers resort to using the same lines for processing food powders with similar or limited ingredients. The storage, mixing and filling conditions of processing lines affect the food powder quality. Hoppers are large stainless-steel containers to store and mix contents before filling into jars/containers for subsequent sealing/capping at high speeds. Such high-speed mixing and filling lead to poor powder homogeneity. Currently, such content-filled containers are subjected to invasive sample extraction for offline spectroscopic analysis in a laboratory on randomly picked samples, which is time-consuming, uses expensive machinery, requires user-dependent data analysis, and results in food loss and waste in the form of poor-quality powders and/or powder/package waste from batch rejection. In this work, we focus on applying a non-invasive sensing technology to prevent food loss and waste generation through early detection and screening of poorly mixed powders in filled containers. A capacitive system is proposed to detect dielectric differences between varying levels of binary blending of beverage powders to showcase its application for powder homogeneity analysis. The detection scheme showed a fast response time (50 ms) and a low detection limit of 15% for detecting powder fraction in a binary blended mixture non-invasively.

Pre-analytical errors in the phlebotomy process in a national hospital in Lima

Errors in the clinical laboratory are very frequent, most of which are mostly during the pre-analytical phase. That is why this research work proposes the identification of pre-analytical errors in the external office area of the Dos de Mayo National Hospital. To do this, a form was applied, filled out by the researcher at the time of supervision of the sampling. The instrument was validated by the joint recommendations of the EFLM-COLABIOCLI (European Federation of Clinical Chemistry and Laboratory Medicine) and the Latin American Working Group of the Pre-Analytical Phase (WG-PRE-LATAM) of the Latin American Confederation of Clinical Biochemistry. It was obtained as a result, among the most outstanding, that more than 90% of the patient was not recommended to rest for 5 minutes at the end of the phlebotomy, 80% did not register the identity of the phlebotomist in the request for examinations, in 40% there was a poor homogenization of the tubes, about 12% did not instruct the patient to apply pressure at the extraction site and 10% the barcode was not labeled in the presence of the tubes of the patient. It is concluded that the sampling personnel, phlebotomists, should follow the established standards and reinforce the previous knowledge through continuous supervision by the health personnel and pathologist.

강력분을 이용한 다단압출 생면 스파게티 개발

In this study, a comparative evaluation of multi-step extruded spaghetti prepared with bread flour, traditional spaghetti, and commercial spaghetti was carried out. Multi-step extruded wheat flour spaghetti (MWS) showed the highest pH value at 6.54 which was significantly higher than that of the conventional pasta-making spaghetti (CPS) and commercial semolina spaghetti (CSS)(p0.05). This could be due to the influence of cold soda, a minor ingredient. The water activity of CPS, 0.77±0.02, was significantly lower than those of MWS and CSS. Chromaticity showed significantly different results in MWS than in the CPS and CSS. This was influenced by a gardenia yellow color added to MWS. The changes in the volume and weight after cooking were the largest in CPS, followed by CSS and MWS. The change in the volume and weight of MWS was significantly different (p0.05). In addition, an analysis of cooking characteristics revealed that MWS (152.00%) and CSS (148.00%) had significantly higher water absorption and significantly lower turbidity values. Texture measurement showed that the hardness and springiness were similar, and the gumminess of MWS and CSS were 14.05 and 13.74, respectively, which were significantly lower than CPS (16.46) (p0.05). There was no significant difference between MWS and CSS in terms of flavors, taste, and overall acceptability. The appearance of MWS evoked a lower sensual preference compared to the CSS and hence, further research on the minor ingredients and additives of multi-stage extruded spaghetti is necessary. When subjected to scanning electron microscopy (SEM), CPS showed wide pores and poor homogeneity, and MWS and CSS showed denser and more homogeneous honeycomb microstructures. In conclusion, spaghetti prepared by multi-step extrusion can be a replacement for semolina spaghetti.

Biomineralization-Inspired Intermediate Precursor for the Controllable Gelation of Polyphenol-Macromolecule Hydrogels.

Hydrogels composed of polyphenols and various macromolecules have been widely reported to have the advantage of facile preparation, mainly through the formation of hydrogen bonds. However, the traditional preparation method involves the direct mixing of polyphenols and macromolecules, which generally occurs too quickly and uncontrollably, and results in poor homogeneity, injectability, and shape designability. Here, inspired by the intermediate precursor during biomineralization, to facilitate transformation in a controllable way, we propose a novel and universal internal gelation method that creates an intermediate precursor by controlling the pH value to manipulate the elimination and generation of hydrogen bonds between a polyphenol and macromolecules. The precursor strategy greatly improves the homogeneity, injectability, and shape designability of the hydrogel while also achieving a controllable gelation process, and the gelation time can be accurately adjusted. The hydrogels prepared with this method exhibited superior capability to seal leaks, provided complete wound coverage, and showed the potential to be a shape-designable wearable strain sensor. Our study opens up a new way to construct and apply polyphenol-macromolecule hydrogels in a more controllable manner.

Energy-saving optimization of application server clusters based on mixed integer linear programming

The issue of how to dynamically optimize the deployment of an application server cluster according to the changing load to reduce energy consumption is an important problem that must be urgently solved. In this paper, we propose an energy-saving optimization strategy for application server clusters, whose optimization content includes the on/off state, CPU frequency, and load size of each server. Compared with existing research, our strategy is not only more accurate in power and load models but also considers the switching cost of servers to avoid server switching jitter. The strategy includes two schemes, which both formulate the cluster energy-saving optimization as a mixed integer linear programming (MILP) problem and then adopt a toolkit to solve the problem. One scheme defines variables for each server, and the resulting programming problem is called the MILP4PH problem. The other scheme defines variables for each server type, resulting in a programming problem called the MILP4GH problem. The experimental results reveal that for clusters with poor homogeneity, the MILP4PH problem has fewer variables and can be solved in real time, while for clusters with good homogeneity, the MILP4GH problem has fewer variables and can be solved in real time.

The compositional homogenization control of Cu-Ti alloys prepared by accumulative roll bonding-deformation diffusion process

A new process of accumulative roll bonding-deformation diffusion (ARB-DD) with subsequent deformation diffusion heat treatment was proposed to solve the problem of poor composition homogeneity of alloys prepared by conventional accumulative roll bonding-diffusion heat treatment (ARB-DHT). The effects of ARB-DHT and ARB-DD on compositional homogeneity of Cu-Ti alloys were studied in comparison. And the mechanism of compositional homogeneity evolution of ARB-DDed Cu-Ti alloy was revealed. The results show that elements in Cu-Ti alloys prepared by the conventional ARB-DHT process are enriched and show a more obvious periodic distribution characteristic, and the compositional homogenization is poor. However, in ARB-DD process, the deformation process drives the Taylor lattice to reopen and form high-density nano-twin with a lamella width of 50–90 nm. Further, the high density of dislocations and stacking faults provides high diffusion rate channels for element diffusion, which effectively facilitates the diffusion and redistribution of elements in the subsequent diffusion heat treatment process and accelerates the compositional homogenization. On the contrary, in comparison with the conventional ARB-DHT process which promotes element diffusion through thermal effects, the ARB-DD process uses the synergistic effects of thermal and deformation effects to promote element diffusion, effectively enhancing the degree of compositional homogenization.

Decoupling engineering of formamidinium-cesium perovskites for efficient photovoltaics.

Although pure formamidinium iodide perovskite (FAPbI3) possesses an optimal gap for photovoltaics, their poor phase stability limits the long-term operational stability of the devices. A promising approach to enhance their phase stability is to incorporate cesium into FAPbI3. However, state-of-the-art formamidinium–cesium (FA–Cs) iodide perovskites demonstrate much worse efficiency compared with FAPbI3, limited by the different crystallization dynamics of formamidinium and cesium, which result in poor composition homogeneity and high trap densities. We develop a novel strategy of crystallization decoupling processes of formamidinium and cesium via a sequential cesium incorporation approach. As such, we obtain highly reproducible, highly efficient and stable solar cells based on FA1–xCsxPbI3 (x = 0.05–0.16) films with uniform composition distribution in the nanoscale and low defect densities. We also revealed a new stabilization mechanism for Cs doping to stabilize FAPbI3, i.e. the incorporation of Cs into FAPbI3 significantly reduces the electron–phonon coupling strength to suppress ionic migration, thereby improving the stability of FA–Cs-based devices.

Deciphering perovskite decomposition in a humid atmosphere with TOF-GISANS

Doping or alloying of the cations on the A-site and halides on the X site of ABX3 perovskites has been demonstrated as a successful technique for improving moisture stability of perovskite films for optoelectronic applications. Despite structural and electrical stability improvements, these films still undergo moisture induced degradation to Lead Iodide and other photo-inactive phases, reducing device lifetime and performance. Understanding of their moisture induced degradation has been limited by the contrast mechanisms and sensitivity of optical and x-ray scattering techniques. Time-of-Flight Grazing Incidence Small Angle Neutron Scattering (TOF-GISANS) presents itself as a powerful alternative capable of identifying low atomic weight phases and offering depth resolution. Herein we use TOF-GISANS to begin to uncover moisture induced degradation pathways in various mixed perovskite systems fabricated under ambient conditions and exposed to 90% rH in the dark for up to 12 h, showing poor stoichiometric homogeneity through the bulk of the film and facile formation of deuterated by-products at ambient temperatures. We find evidence indicative of formation of PbI2, and PbBr2 from peaks apparent in scattering from the surface of MAPbI3, FA0.83MA0.17Pb(I0.83Br0.17)3, and FA0.83Cs0.17Pb(I0.83Br0.17)3 thin films, with degradation less pronounced in the latter films containing Cs. Deuterated by-products form readily, resulting in decreasing average particle size as perovskite crystals swell and fragment from the grain periphery inwards. Cs0.05(FA0.83MA0.17)0.95Pb(I0.84Br0.16)3 shows impressive phase resilience compared to the other mixtures, with minimal segregation to other phases observed in vertical cuts through the 2D scattering image, though still exhibits deleterious morphological degradation. TOF-GISANS is demonstrated as a powerful tool for characterisation of these materials, with significant potential for future investigations into phase changes in thin films.

Biomimetic Exosomes: A New Generation of Drug Delivery System.

Most of the naked drugs, including small molecules, inorganic agents, and biomacromolecule agents, cannot be used directly for disease treatment because of their poor stability and undesirable pharmacokinetic behavior. Their shortcomings might seriously affect the exertion of their therapeutic effects. Recently, a variety of exogenous and endogenous nanomaterials have been developed as carriers for drug delivery. Among them, exosomes have attracted great attention due to their excellent biocompatibility, low immunogenicity, low toxicity, and ability to overcome biological barriers. However, exosomes used as drug delivery carriers have significant challenges, such as low yields, complex contents, and poor homogeneity, which limit their application. Engineered exosomes or biomimetic exosomes have been fabricated through a variety of approaches to tackle these drawbacks. We summarized recent advances in biomimetic exosomes over the past decades and addressed the opportunities and challenges of the next-generation drug delivery system.

IDENTIFICATION OF ROCK CHARACTERISTICS USING XRF, XRD, AND SEM TESTS ON API ALAM IN PAMEKASAN

Research has been conducted into the nature of geothermal rocks in Pamekasan. This place is located in Tlanakan Pamekasan. This study aims to determine the composition of mineral compounds in the soil so that fire can burst out from the soil and the soil does not melt. Three steps can be done with simple refinement and filtering methods, namely X-Ray Fluorescence (XRF), X-ray diffraction (XRD), and Scanning Electron Microscope (SEM). The results of XRF analysis show the element of Api Alam 1 is Ca 66.2%, Api Alam 2 is Si 37.4%, and in hot springs, is Si 39.6%. The XRD results show that mineral qualitatively in Api Alam 1 was in the form of CaCO3 compound at 60.1% and SiO2 at 39.9%, while in Api Alam 2, hot water sources were in the form of SiO2 compound (&gt;90%). SEM Results on Api Alam 1 show that the sample is almost homogeneous (the distribution of CaCO3 and SiO2 is uneven), the presence of slab-shaped clumps that identify the presence of varying grain size, and with high porosity, which indicates that the sample is partially amorphous in structure, in Api Alam 2. The Hot springs show irregular aggregations and poor homogeneity of the sample. The size of the three samples is ten μm or 10.000 nm, while PSA results showed an average size of Api Alam 1 was 509.7 nm, Api Alam 2 was 891.3 nm, and Hot Springs was 468.3 nm.

In-situ microstructural evolution during quenching and partitioning of a high-carbon steel by high-temperature X-Ray Diffraction

Carbon partitioning from martensite to austenite is essential for austenite stabilization during quenching and partitioning (Q&P), while a few competitive phenomena, such as bainitic transformation and carbide precipitation, alter the microstructural evolution. So, there is a need of using in-situ in combination with ex-situ characterisation techniques to understand the C partitioning at high temperature in relation to simultaneous competitive phenomena that might occur during the partitioning stage.In this study, microstructural evolutions of a medium carbon steel ( 0.6C–1.6Si–1.25Mn–1.75Cr wt%) during Q&P treatment were investigated by using an in-situ High-Temperature X-Ray Diffraction (HTXRD) equipment at three partitioning temperatures. Results confirmed that carbon enrichment of austenite at 280 and 400 ℃ originates from partial carbon depletion from martensite and bainitic transformation, while partitioning at 500 ℃ results in the complete depletion of carbon from initial martensite and ferrite formation. Short diffusion distance (~0.13 µm) of carbon at 280 ℃ caused a poor carbon homogenization of austenite and formation of 8 vol% fresh martensite after final quenching. High Si content of the steel stabilized transitional carbides and, concurrently, suppressed Fe3C formation during Q&P. The outcome of this study could contribute to the design of suitable chemistry and process parameters for producing quenched and partitioned steels.

Innovative use of industrially produced steel slag powders in asphalt mixture to replace mineral fillers

Using steel slag to partially replace the natural aggregate in asphalt mixture to produce high-performance asphalt mixture has gained significant interest in recent years as a value-added option to recycle steel slag. However, the poor homogeneity of the material properties of steel slag aggregates remains a concern for this recycling approach. In this study, an innovative method of using industrially produced steel slag powder (SSP) to replace the mineral filler in asphalt mixture was proposed to address this concern. Five fillers, including four SSP fillers, obtained by grinding different steel slag aggregates with an industrialized production line, and one conventional limestone powder (LP) filler, were evaluated. The chemical compositions and micro-morphologies of the SSPs were first characterized to evaluate the material homogeneity and gain insights into the advantages of using SSPs as fillers. Then, asphalt mixtures with different fillers were designed and produced, and their moisture stability, rutting resistance, and low-temperature crack resistance, were characterized. It was found that the industrially produced SSPs possessed homogeneous properties, and improved the compatibility between filler particles and asphalt binder. Besides, the asphalt mixtures with SSP fillers showed better resistance to the moisture damage, permanent deformation, low-temperature crack in terms of fracture energy, than the asphalt mixture with LP filler. Therefore, it was concluded that using SSPs as a replacement of mineral fillers in asphalt mixture provided a reliable and value-added solution to recycle steel slag.

Analysis of the thermal stability and optical properties of KBiFe2O5perovskite obtained by a polymeric precursor method

AbstractThe solar cells are the most prominent devices to generate energy from sunlight, however, one of the main factors limiting the efficiency of photovoltaic conversion is the recombination of charge carriers in their active layer, which is generated by the inhomogeneity of the material that constitutes this layer. KBiFe2O5is a perovskite with a high potential to be applied in the active layer of photovoltaic devices, however, it suffers from poor homogeneity during its synthesis, which is caused by the volatilization of K and Bi of its composition and, consequently, leads to the formation of secondary phases, which can sequester the charge carriers and decrease the efficiency of photovoltaic conversion. Thus, our objective is to evaluate the homogeneity of the powders obtained by the polymeric precursor method, its thermal stability until the formation of secondary phases, and the optical properties. With elemental mapping, it was possible to verify that the powder obtained was highly homogeneous and the band gap of 1.74 eV is within the optimal range for applications involving sunlight. Thus, it was possible to verify that this synthesis method generates highly homogeneous powders and at the temperatures employed does not undergo volatilization of K and Bi.