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Morphology of hydraulic fracture surface has significant effects on oil and gas flow, proppant migration and fracture closure, which plays an important role in oil and gas fracturing stimulation. In this paper, we analyzed the fracture surface characteristics induced by supercritical carbon dioxide (SC-CO2) and water in open-hole and perforation completion conditions under triaxial stresses. A simple calculation method was proposed to quantitatively analyze the fracture surface area and roughness in macro-level based on three-dimensional (3D) scanning data. In micro-level, scanning electron micrograph (SEM) was used to analyze the features of fracture surface. The results showed that the surface area of the induced fracture increases with perforation angle for both SC-CO2 and water fracturing, and the surface area of SC-CO2-induced fracture is 6.49%-58.57% larger than that of water-induced fracture. The fractal dimension and surface roughness of water-induced fractures increase with the increase in perforation angle, while those of SC-CO2-induced fractures decrease with the increasing perforation angle. A considerable number of microcracks and particle peeling pits can be observed on SC-CO2-induced fracture surface while there are more flat particle surfaces in water-induced fracture surface through SEM images, indicating that fractures tend to propagate along the boundary of the particle for SC-CO2 fracturing while water-induced fractures prefer to cut through particles. These findings are of great significance for analyzing fracture mechanism and evaluating fracturing stimulation performance.

The paper presents the results of the elastoplastic properties of Ti/Cu bimetallic rods. They were obtained by extrusion and composed of a copper core with a covered titanium layer. Experiments were carried out at room temperature on virgin samples, and samples were subjected to prior annealing in the temperature range of 600–900 °C for 30, 60, and 90 min. The modern technique of impulse excitation of vibration was used to analyze the elastic properties of bimetal, obtaining the temperature and time characteristics of Young’s modulus, internal friction, and resonance frequency variability. Subsequently, the samples were stretched to breakage, obtaining information on the values of limit stresses, their deformability, and the energy demand for uniform elastic–plastic deformation in terms of the effect of temperature and annealing time. The influence of thermal processes on the strengthening of the Ti/Cu bimetal was also examined, and microscopic observations and qualitative analysis of the diffusion zone at the interface of the phases were carried out. The research was to answer the question of how a short-term temperature increase in 600–900 °C affects the physical properties of Ti/Cu bimetallic rods. These rods were used as a high-density electric current carrier in metallurgical processes in environments of aggressive chemical compounds. Studies have shown that short-term annealing at elevated temperatures causes a drastic reduction in the strength of the Ti/Cu bimetal, leading to structural changes within the components, and the diffusion zone with the release of intermetallic compounds, leading to structural degradation. Heating at 900 °C for 60 and 90 min caused accelerated interface degradation and destruction of the Ti/Cu bimetal by delamination.

Wire arc additive manufacturing (WAAM) is the latest development in 3D printing because of its high build rate. This study investigated the first use of cable-type welding wire (CWW) to manufacture thin-walled AA5356 aluminum alloy through cold metal transfer technology. The inherent advantages of the CCW, such as high deposition efficiency, energy savings, and better stirring of the weld puddle due to arc rotation, were tapped and analyzed for WAAM. The experimental results showed that WAAM CWW provides enhanced quality built parts. The grain morphology, phase in micro-constituents, and defect formation were investigated through structured optical micrography and XRD analyses. The mechanical test was also performed along and normal to the build direction. The optical microscopy results showed that a defect free deposit with equiaxed grains was formed. Compared with the casting aluminum alloy, the average ultimate tensile strength and yield strength of the parts made by the WAAM with CWW increased by 19.8% and 22.5%, respectively.

Evaporation of droplets of water–ethanol solutions with different concentrations has been experimentally studied at different relative humidities of ambient air. High-speed micrography has been employed to monitor the dynamics of variations in the sizes of the evaporating droplets. It has been found that relative humidity of the ambient air significantly affects variations in the diameters of water–ethanol solution droplets. Infrared thermography has been used to study variations in the temperature of the evaporating droplets. It has been shown that the temperature of the evaporating droplets decreases with an increase in ethanol concentration at all studied relative air humidities. The minimum values of evaporating droplet surface temperature and evaporation time increase with relative air humidity. The performed generalization of the obtained experimental data may be used when calculating the heat and mass transfer of evaporating droplets of water–ethanol solutions.

This paper presents a novel algorithm to generate micrography QR codes , a novel machine-readable graphic generated by embedding a QR code within a micrography image. The unique structure of micrography makes it incompatible with existing methods used to combine QR codes with natural or halftone images. We exploited the high-frequency nature of micrography in the design of a novel deformation model that enables the skillful warping of individual letters and adjustment of font weights to enable the embedding of a QR code within a micrography. The entire process is supervised by a set of visual quality metrics tailored specifically for micrography, in conjunction with a novel QR code quality measure aimed at striking a balance between visual fidelity and decoding robustness. The proposed QR code quality measure is based on probabilistic models learned from decoding experiments using popular decoders with synthetic QR codes to capture the various forms of distortion that result from image embedding. Experiment results demonstrate the efficacy of the proposed method in generating micrography QR codes of high quality from a wide variety of inputs. The ability to embed QR codes with multiple scales makes it possible to produce a wide range of diverse designs. Experiments and user studies were conducted to evaluate the proposed method from a qualitative as well as quantitative perspective.

Made available in DSpace on 2020-12-10T20:03:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-06-30 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The final quality of mechanical components is directly linked to the efficiency of the machining processes to which it is subjected. In this sense, grinding can provide high standards of surface and geometric quality for mechanical components, since these characteristics are increasingly necessary for the automotive and aerospace sectors. However, the complexity of the mechanical components creates increasing difficulties for grinding. Workpieces with geometric interruptions, as in the case of gears, splined shafts, pistons, and crankshafts generate mechanical impacts and aggravate the thermal gradients during grinding, causing errors of shape, drop in surface quality and reduction in the life of the cutting tool. However, few studies on better conditions for interrupted cut grinding are seen, thus making it difficult to determine ideal grinding conditions. Thus, the present experimental investigation aims to make a comparison between cylindrical grinding of workpieces of hardened AISI 4340 steel with two, six, and twelve geometric interruptions, comparing them with the grinding workpieces without interruptions, applying white aluminum oxide wheels with vitrified and resinoid bonds. Results in terms of surface roughness, roundness deviation, acoustic emission, grinding power, diametrical wheel wear, and micrography are pointed out, indicating that the greater rigidity of the vitrified bond can be harmful during the grinding of workpieces with interrupted geometry. Sao Paulo State Univ Julio de Mesquita Filho, Dept Mech Engn, Bauru Campus, Bauru, SP, Brazil Sao Paulo State Univ Julio de Mesquita Filho, Dept Elect Engn, Bauru campus, Bauru, SP, Brazil Sao Paulo State Univ Julio de Mesquita Filho, Dept Mech Engn, Bauru Campus, Bauru, SP, Brazil Sao Paulo State Univ Julio de Mesquita Filho, Dept Elect Engn, Bauru campus, Bauru, SP, Brazil FAPESP: 2017/03788-9 FAPESP: 2018/22661-2

Duplex structural stainless steels (DP) are highly corrosion-resistant with austenite (γ)-ferrite (δ) compositions and processing routes. These DP steels are used in chemical, petrochemical, marine, power generation, and nuclear industries due to their unique properties. Experimental data of 2D slices obtained from optical micrography were used in a multilevel finite element analysis to investigate the interface stresses between the two phases of DP material. Level #1 (macro-level) finite element analysis involves homogenizing the 2D slices based on their representative constituent properties to identify high-stress regions. Level #2 (micro-level) finite element analysis was conducted with representative austenite/ferrite microstructure identified from level #1 analysis. The results from finite element simulations from both macro- and micro-levels revealed that interface stresses are affected by the phase’s microstructure distributions. Micro-level analysis revealed maximum interface stress is much higher than macro-level analysis. It was also found that stress localization occurred at the ferrite/austenite interfaces based on their distributions.

The converting of copper matte after the smelting process is one of the main steps in the copper-making industry. This work used microstructural analyses of samples collected at different stages of converting and thermochemical calculations to study a real converting batch in a Peirce-Smith converter at Atlantic Copper. The transformation of matte and slag produced during the converting was studied. The use of thermochemical calculations allowed a simulation of non-standard process conditions that provides valuable additional information on converting. The examined non-standard conditions were slag blow carried out in a single blow, the influence of the Fe/SiO2 slag ratio and over-oxidation at the end of the copper blow in the converting process. The micrographical investigation showed two predominant phases formed in the matte matrix after slow cooling, and their proportion varied along the slag blow. The slag presented two fayalitic olivine phases with different Fe/SiO2 ratios, the most abundant being the one with a higher Fe/SiO2 ratio. Magnetite crystals were identified in slags, and some of them were surrounded by fayalitic olivine. The analytical data of samples show that the measured copper in the slag is higher than in the theoretical thermochemical calculations. This indicates that the physical entrainment of matte/copper droplets in slag prevents a complete separation of the matte from the slag (residence time, agitation by blowing and viscosity). The final slag produced at the end of converting contains a high copper content, wherein copper is distributed after slow cooling into cuprite (Cu2O) and delafossite [(Cu,Fe)O] phases.

Microscope is one of the tools used in practicums with high intensity. The use of a microscope adjusts to the object to be observed in order to obtain optimal micrographic results. Stereo microscopes are used to observe three-dimensional objects. Upright microscopes are used to observe two-dimensional objects. This study aims to combine the two advantages of stereo microscopy that can produce three-dimensional micrography with the advantages of an upright microscope that has a high total magnification. The method used in this study is an experimental method by adding an optical fiber illuminator in the use of an upright microscope and then applying it in various observations. The conclusion of this research is the addition of an optical fiber illuminator in observations using an upright microscope can replace the function of a stereo microscope; can produce three-dimensional effects and increase magnification in Daphnia magna micrographic observations.

The objective of this research is to perform the processing and mechanical characterization on 3D-printed high-temperature polymer (polycarbonate) reinforced with short carbon fiber (SCF) composite material fabricated with the help of fused filament fabrication process. For this study, different SCF volume fractions (3%, 5%, 7.5%, 10%) with varying printing speed (25, 50, 75 mm/s) are taken as the input variables. It was observed that tensile, flexural, compressive properties and micro-hardness were greatly affected by varying the input processing parameters. To find the orthotropic properties of 3D-printed specimens, tensile properties are analyzed on 0° in the X-Y plane, 90° in the X-Y plane, and 90° in Z-axis. Scanning electron microscopy (SEM) is performed to study the effect of fiber breakage, fiber distribution, fiber accumulation, and fiber length on the mechanical performance of the final part. After performing mechanical testing, investigation of microstructural behavior of tensile, flexural, and compressive samples is accomplished using SEM. From the micrograph analysis and mechanical testing, it was noticed that fiber behavior inside the composite has created a great influence in deciding the mechanical performance of the final part. Micromechanics and classical lamination theory phenomena are followed to determine the effective young’s modulus of 3D-printed samples mathematically. Printing direction and reinforcement percentage are found out to be the most influential parameters in deciding the final properties of 3D-printed specimens by using the statistical tool ANOVA. Response surface methodology is used to determine the optimum parameters to get good-quality print with SCF-reinforced PC.

Pure lead powder can be electrodeposited by reduction of lead ions (Pb2+) in aqueous electrolyte. In this investigation, ultra-fine lead powders with a minimum median diameter of 4.5 μm were electrodeposited in acetate solution. The formation mechanism of lead oxide (PbO) during electrodeposition was proposed. Operation parameters such as pH value, current density, and gelatin had remarkable influence on oxidation degree, median diameter, and current efficiency, which were detailed for the first time. Metallic Pb was formed with strong (111) preferred orientation, and micrography, composition, and structure were characterized. Amorphous PbO was found in as-deposited lead powder, and a gel-layer process was proposed to elucidate the formation of PbO. It was suggested the Pb···OH was the most important intermediate state to form PbO and the gel-layer played the key role in generation of pure lead powder.

Purpose In this study, we aim to explore the effects of graphene oxide (GO), a derivative of graphene, nanoparticles of four different sizes on the cellular fate of mouse neural stem cells (mNSCs). Methods GO NPs were characterized with transmission electron microscopy (TEM), scanning electron micrography (SEM), atomic force microscopy (AFM) and Raman Spectra analysis. The cytotoxic effects of the GO NPs of different sizes on the mNSCs were determined using CCK-8 assay, Annexin V-APC/ 7-AAD staining and EdU staining assays. We investigated the biological and the mechanisms of GO NPs on cells using immunofluorescence analysis and quantitative real-time PCR (qPCR). Results The average hydrodynamic sizes of the GO NPs were 417 nm, 663 nm, 1047 nm, and 4651 nm, with a thickness of approximately 22.5 nm, 17.7 nm, 22.4 nm, and 13.4 nm, respectively. GO NPs of all sizes showed low cytotoxicity at a concentration of 20 μg/mL on the mNSCs. Immunostaining demonstrated that treatment with GO NPs, especially the 663 nm ones, enhanced the self-renewal ability of mNSCs in the absence of EGF and bFGF. Under differentiation medium conditions that are free of mitogenic factors, all the GO NPs, particularly the 4651 nm ones, increased the expression level of Tuj1 and GFAP. With regards to the migration ability, we found that 417 nm GO-NP-treated mNSCs migrated over a longer distance than the control group obviously. In addition, higher expression of Rap1, Vinculin and Paxillin was observed in the GO NP-treated groups compared to the control group. mRNA-Sequence analysis and Western blotting results suggested that the 4651 nm GO NPs triggered positive neuronal differentiation through phosphorylation of ERK1/2 by the downregulating of TRPC2. Conclusion GO NPs play an important role in the applications of inducing self-renewal and differentiation of mNSC, and are promising in the future for further studies.

Biocorrosion is the main process that causes pipeline damages and losses in the oil industry. The objective of this work was to investigate the influence of biofilm forming microorganisms on the biocorrosion of X80 steel exposed in produced water through microbiological characterization, film and biofilm analysis by optical microscopy and scanning electron microscopy, weight loss and surface analysis by laser confocal microscopy. Changes in produced water after 360 days were attributed to planktonic cells, temperature conditions, contact with air, photo-oxidation, biodegradation, and seasonality. The total aerobic bacteria presented sessile cell concentration of 7.39 x 104 CFU/cm2, while the other investigated groups showed lower concentrations. The micrography of the film showed salt crystals, whereas in the biofilm microorganisms, exopolysaccharides and corrosion products were observed. Weight loss after 360 days for the abiotic and biotic systems was 0.0222 g/cm2 and 0.3039 g/cm2, respectively, showing that microorganisms accentuated the corrosion of X80 steel.

Water hyacinth hydrothermal carbonization was studied under different temperature (160–250 C), time (30–120 min) and biomass/water ratio (10–50%) conditions. The research was designed following response surface methodology, which was very useful to infer interactions between variables and to develop models predicting the system behaviour with good accuracy. Output functions were solid yield, hydrochar C and N content, as well as their captures, and heating value. It was found that while temperature was the most influential variable promoting HTC reactions, time and even biomass load were decisive to provide particular C and N captures; based on these results, reaction mechanisms were discussed. On the other hand, 2D graphs allowed to build different scenarios in which target properties might be achieved under a wide range of dissimilar conditions, leading to process optimization. The study was complemented by exploring hydrochar surface properties by N2 adsorption at 77 K, SEM micrography and XPS analyses.

Giant clams have evolved to maximize sunlight utilization by their photosymbiotic partners, while affording them protection from harmful ultraviolet (UV) light. The presence of UV absorbing substances in the mantle is thought to be critical for light protection; however, the exact localization of such compounds remains unknown. Here, we applied a combination of UV liquid chromatography (LC), LC-mass spectrometry (MS), MS imaging, and UV micrography to localize UV absorbing substances in the giant clam Tridacna crocea. LC-MS analysis revealed that the animal contained three classes of mycosporines: progenitor, primary, and secondary mycosporines. MS imaging revealed that primary and secondary mycosporines were localized in the outermost layer of the mantle; whereas progenitor mycosporines were distributed throughout the mantle tissue. These findings were consistent with the results of UV micrography, which revealed that the surface layer of the mantle absorbed UV light at 320 ± 10 nm. This is the first report indicating that progenitor and primary mycosporines are metabolized to secondary mycosporines by the giant clam and that they are differentially localized in the surface layer of the mantle to protect the animal from UV light.

Shape memory alloys (SMAs) are the new generation functional material and being recognized as a smart or intelligent material. In this research, a novel Ni-rich NiTip shape memory alloy (SMA) reinforced magnesium matrix composites were prepared using a recent solid-state friction stir processing (FSP) technique. High speed steel was selected as tool material. A flat shouldered plain cylindrical tool pin profile was selected for experiment. The FSP was performed on a fixed value of 560 tool rpm, 100 mm/min traversing speed and 3° tool tilt. The particle distribution in processed zone was analyzed using optical micrography while micro-hardness were evaluated by Vickers indentation test. The results revealed that the FSP was successful in fabrication of surface composite on magnesium matrix. The processed zone indicates good bonding of reinforcement particles with the substrate. However, some accumulation of reinforcement was observed in the processed region. The micro-hardness of the reinforced zone shows significant improvement.

Electrical Discharge Machining (EDM) is the one of the earliest nontraditional machining processes. Today, many parts used in the aerospace and automotive industries and in the final processes of surgical can be finished by the EDM process. The machining parameters mainly affect the economy of process. This work emphasizes to find the optimization of machining parameters using response surface methodology (RSM)by variation of peak current, pulse time variation so that good Surface Finish (SF) can be achieved with the optimum Material Removal Rate (MRR). It was concluded that with the increasing peak current and pulseon Time (Ton), MRR increases but the surface roughness also starts to increase resulted in poor surface finish whereas with decreasing the pulse off Time (Toff), the surface finish increases but MRR starts to decrease. During the experimentation, Tool Steel-D2 was selected as work specimen with the copper electrode. Surface micrography had been done for the deep analysis to see the effect of machining on the Tool Steel-D2. This study indicates towards the practical feasibility of optimized EDM parameters in multi response conditions. How to cite this article:Singh P, Singh L. An Experimental Investigation During Electric Discharge Machining of Tool Steel-D2. J Adv Res Mfg Mater Sci Met Engr 2019; 6(3&4): 1-7.

Unprinting of paper can reduce multiple life-cycle stages in the recycling of paper to yield significant environmental impact. Laser-unprinting has been demonstrated for uncoated paper but causes significant damage to coated paper. This work explores a scalable optical (non-laser) process for unprinting coated paper. Printed coated paper is exposed to pulsed broad-spectrum Intense Pulsed Light (IPL) from a xenon lamp and the toner is then removed by dabbing gently with an ethanol wipe. While black toner is easily unprinted, unprinting of colored prints (red, blue, green) is best realized by incorporating an initial overprint of black toner. An unprinting throughput on the order of mm2/s is achieved. Three distinct regimes of unprinting are identified based on the extent of toner removal and damage of the paper. The optical properties of the unprinted paper, characterized via UV–Visible spectrophotometry, are correlated to these regimes to understand the potential for in-situ optical process monitoring. Scanning Electron Micrography and Fourier-Transform Infrared Spectroscopy are performed to understand the underlying mechanisms that govern the occurrence of the different unprinting regimes. Further, the potential impact of the developed approach on recycling of paper is discussed in the context of the capabilities of current optical unprinting approaches and the potential elimination of life-cycle stages in conventional paper recycling.

The annealing behaviours of the equal channel angular pressed (ECAP) structural steel (hypoeutectoid) were investigated. The sample was processed up to four pass-through routes Bc in 120° angle die at ambient condition. Due to the effect of ECAP process, mechanical properties significantly improved, whereas the ductility drastically decreased in the material. The microstructural and mechanical characterization illustrates that the recovery process occurred at an annealed temperature of 500–525 °C and the recrystallization process occurred when the sample was annealed at 550 °C. When the annealing temperature was 600 °C, the grain growth process occured in the ECAPed sample and the strength, hardness and ductility were almost equivalent to the as-received material. The microstructural analysis was revealed in the TEM micrography. According to the microstructural and mechanical property analysis, the intermediate annealing temperature of 525 °C to 550 °C was suitable for this material to optimize the strength and ductility.

A novel finishing agent, N,N-dimethyl-octadecyl phosphate acrylamide (NDOPA), was synthesized with octadecanol, phosphorous acid, formaldehyde and acrylamide, and applied to cotton fabrics by ultraviolet curing to endow cotton fabrics with superhydrophobicity and flame retardancy. Results showed that NDOPA could be grafted onto cotton fabrics through C–O–C covalent bonds during the ultraviolet curing process. The contact angle of cotton fabric treated with the 10% NDOPA agent could reach 157.5°. The treated cotton fabrics exhibited clear flame retardancy. The treated cotton retained strong hydrophobicity and flame retardancy after 30 laundering cycles, indicating that the treated cotton fabrics had excellent durability. Thermogravimetric analysis revealed that the treated samples had flame-retardant properties. The results of Fourier-transform infrared spectroscopy, energy dispersive X-ray analysis and scanning electron micrography showed that NDOPA was successfully grafted onto the cotton fabrics; X-ray diffraction analysis indicated that the crystallized structure of treated cotton fibers nearly did not change.

Background: Electrospun gelatin/polycaprolactone (Gt/PCL) nanofibrous scaffolds loaded with graphene are novel nanomaterials with the uniquely strong property of electrical conductivity, which have been widely investigated for their potential applications in cardiovascular tissue engineering, including in bypass tracts for atrioventricular block. Purpose: Electrospun Gt/PCL/graphene nanofibrous mats were successfully produced. Scanning electron micrography showed that the fibers with graphene were smooth and homogeneous. In vitro, to determine the biocompatibility of the scaffolds, hybrid scaffolds with different fractions of graphene were seeded with neonatal rat ventricular myocytes. In vivo, Gt/PCL scaffolds with different concentrations of graphene were implanted into rats for 4, 8 and 12 weeks. Results: CCK-8 assays and histopathological staining (including DAPI, cTNT, and CX43) indicated that cells grew and survived well on the hybrid scaffolds if the mass fraction of graphene was lower than 0.5%. After implanting into rats for 4, 8 or 12 weeks, there was no gathering of inflammatory cells around the nanomaterials according to the HE staining results. Conclusion: The results indicate that Gt/PCL nanofibrous scaffolds loaded with graphene have favorable electrical conductivity and biological properties and may be suitable scaffolds for use in the treatment of atrioventricular block. These findings alleviate safety concerns and provide novel insights into the potential applications of Gt/PCL loaded with graphene, offering a solid foundation for comprehensive in vivo studies.

Inorganic materials such as nanotubes and nanorods have attracted much attention due to their anisotropic properties. Although controlling the alignment of inorganic materials is able to enhance their functionality, macroscopic alignment over a large area remains a challenge. We have recently proposed a simple method for inducing unidirectional alignment of ZnO nanorods on a rubbed polyimide layer. In this method, ZnO nanorods grafted with liquid-crystalline (LC) polymers are aligned by cooperative interaction between the LC moieties in the grafted polymers and surrounding LC host molecules. In this study, we investigated the unidirectional alignment of surface-modified ZnO nanorods in nematic LCs in a micrometer-thick cells. Alignment of LC polymer-grafted ZnO nanorods along nematic LC host molecules has been revealed by polarized optical micrography and ultraviolet-visible absorption spectroscopy.

Orientadores: Miriam Dupas Hubinger, Maurício Cordeiro Mancini Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos Resumo: O objetivo do presente trabalho foi propor um modelo matemático baseado na redução da taxa de perda de água durante o processo de desidratação osmótica de melão tipo honeydew orange flesh. Paralelamente, procurou-se verificar a influência da temperatura (25-45 ºC), tipo (sacarose e xarope de milho) e concentração da solução (29 a 57% em peso de sacarose e 34 a 66% em peso de xarope de milho) na cinética do processo de desidratação/impregnação e determinar as melhores condições de temperatura e concentração das soluções osmóticas, mediante planejamentos fatoriais 22. O estudo cinético do processo foi realizado em fatias de melão com 5 mm de espessura e 30 x 40 mm2 de área de transferência submetidas ao processo por até 1440 minutos. Os dados experimentais obtidos foram ajustados aos modelos de Fick, Peleg e ao modelo de n-redução da taxa inicial de desidratação/impregnação proposto neste trabalho. Para fins práticos, usou-se a redução à metade da taxa inicial (n=2) e o modelo foi chamado de "tempo de meia vida". Por fim, avaliou-se a qualidade do produto processado em ambos os solutos. Para tal, foram avaliados o perfil de açúcares, o teor de carotenoides, a variação dos parâmetros instrumentais de cor, a capacidade antioxidante (FRAP, DPPH e teor de fenólicos totais) e os parâmetros estruturais (ensaios de compressão axial e micrografia) das amostras in natura e processadas osmoticamente nos tempos de n-reduções (n=2, 3, 4, 6, 8, 10 e ?). O modelo proposto apresentou boa correlação aos dados experimentais de perda de água e de ganho de sólidos, cujos valores calculados nos tempos necessários para n-reduções da taxa inicial foram fortemente influenciados pelo valor de n. Nas soluções de sacarose, os valores médios da perda de água calculados nesses instantes (PA(t1/n)) foram: 16,1±2,4; 21,9±4,8; 24,8±3,4; 27,6±3,7 e 29,8±4,1 (gágua/100 gamostra); para n igual a 2, 3, 4, 5 e 6, respectivamente. Já nas soluções de xarope de milho obtiveram-se: 17,9±3,5; 22,8±4,8; 36,7±5,7; 29,6±6,3 e 32,0±6,8 (gágua/100 gamostra); para n igual a 2, 3, 4, 5 e 6, respectivamente. Consequentemente, quando n??, PA(t1/n) tendeu a PA?. O planejamento experimental demonstrou que, de modo geral, a concentração foi a variável mais importante no processo e apresentou efeito positivo nos processos de desidratação (PA) e de impregnação (GS). A temperatura apresentou efeito positivo, sobretudo, em altas concentrações de sacarose e xarope de milho. As condições escolhidas para avaliar a qualidade dos produtos processados foram de 28 ºC e 53% de sacarose e 28 ºC e 61% de xarope de milho. O xarope de milho apresentou uma melhor eficiência na transferência de massa do processo (menores ganhos de sólidos) e ambos os solutos influenciaram a qualidade de maneira semelhante. O xarope de milho, forneceu amostras com menor alteração na doçura relativa, mas com maiores alterações estruturais Abstract: The aim of this work was to propose a mathematical model based on dehydration rate reduction during the osmotic dehydration of orange flesh honeydew melon. The influence of temperature (25-45 ºC), type (sucrose and corn syrup solids) and concentration of solution (29 to 57% w/w of sucrose and 34 to 66% w/w of corn syrup solids) on kinetics of dehydration/impregnation processes was verified. A 22 full factorial design was utilized in order to provide the best process conditions (temperature and concentration of solution) for each type of solute. Melon slices (5 mm thick and 30 x 40 mm2 superficial area) were subjected to osmotic solutions for 30, 60, 90, 120, 180, 240, 360, 600 and 1440 minutes. The experimental data were fitted by the models of Peleg, Fick and the n-reduction time of dehydration/impregnation time model, which was proposed in the present work. The half-life (n=2) concept was used for practical purposes. Final product quality was evaluated, in terms of sugar profile, carotenoids content, color measurements, antioxidant capacity (FRAP, DPPH and total phenolics content) and the structure (compression tests and micrographs) for in natura and processed sample during the n-reduction times of dehydration rates (n=2, 3, 4, 6, 8, 10 e ?). The proposed model presented a good correlation with the experimental data of water loss (WL) and solids gain (SG), whose obtained values were strongly influenced by process extension (n). In sucrose solutions, the WL values obtained in n-reduction times of dehydration rates were 16.1±2.4; 21.9±4.8; 24.8±3.4; 27.6±3.7 e 29.8±4.1 (gwater/100 gsample); for n = 2, 3, 4, 5 e 6, respectively. For corn syrup solutions, the values were 17.9±3.5; 22.8±4.8; 36.7±5.7; 29.6±6.3 e 32.0±6.8 (gwater/100 gsample), n = 2, 3, 4, 5 e 6, respectively. Consequently, if n??, WL(t1/n) has tended to the water loss at equilibrium values (WL?). The full factorial desing showed that the solution concentration was the most important variable, presenting a positive effect on dehydration and impregnation processes. The solution temperature also showed a positive effect, at high sucrose and corn syrup solids concentrations. In order to evaluate the product quality, the following conditions were chosen: 28 ºC (for both osmotic agents) and 53% w/w for sucrose and 61% w/w for corn syrup. The corn syrup solids presented a greater efficiency on mass transfer (similar WL, but lower SG) and both solutes provided produtcts with similar quality attributes. However, the samples osmo-dehydrated in corn syrup solutions showed relative sweetness values similar to fresh fruits, but a greater structural changes than those dehydrated in sucrose solutions Doutorado Engenharia de Alimentos Doutor em Engenharia de Alimentos

This study was designed to examine osteoconductive effects of Mg in rats tibia. The animals were sacrificed after 1, 2, and 8 weeks. The elemental analysis was performed using SEM/EDX at week 1. Following X-ray micrography at weeks 2 and 8, samples were embedded in paraffin. The expression of osteocalcin was observed by immunohistochemical staining. The element concentrations of fibrous capsules around the specimens were also measured by ICP-MS. The concentrations of Ca and P on the surface of the Mg specimen increased in SEM/EDX. The tissue specimen showed new bone formation on the bone surface near the implanted area. The concentrations of Mg, Ca, and P were high in the fibrous capsules surrounding Mg. Implantation induced differentiation of osteoblasts, and this process was considered to be associated with new bone formation. Induction of cell differentiation may be influenced by corrosion products in addition to corroding magnesium.

In this work, novel stationary phase coatings by zeolite SiO2NPs coupled with β-cyclodextrin (β-CD) or β-CD/L-phenylalanine were developed for chiral open-tubular capillary electrochromatography (OT-CEC). The OT columns were prepared taking advantage of the strong adhesion of polydopamine in one-step method. Scanning electron micrography and electroosmotic flow were used to characterize the prepared single/dual-selector OT columns. Chiral separation of four chiral analytes (catechin/epicatechin, ephedrine/pseudoephedrine, ritodrine and salbutamol) was carried out in order to evaluate the performance of the prepared columns in OT-CEC with amperometric detection system. In terms of migration time, peak area, resolution, and selectivity factor of catechin/epicatechin and salbutamol, the run-to-run, day-to-day, and column-to-column repeatability were within 8.9%. Under the optimum conditions, the developed methods were applied for the analyses of Chinese herbal medicine Catechu herbs and salbutamol aerosol samples.

The nanofluids may be considered as multifaceted fluids, generally employed to improve the effectiveness of thermal systems, though poor stability due to sedimentation and agglomeration has limited their applications in practical use. In this work, commercial Al2O3 nanopowders were dispersed in distilled water using CTAB as surfactant. Stable Al2O3 /water nanofluids with weight concentrations ranging from 0.02–0.5 wt% were synthesized using bath and probe ultrasonication. Nanopowders were characterized using high-resolution TEM micrography. UV–Vis spectroscopy and zeta potential tests were also conducted to check stability of the nanofluids.

Made available in DSpace on 2022-02-23T19:00:56Z (GMT). No. of bitstreams: 1 TS-2021.026.pdf: 2514013 bytes, checksum: 2ace48c21ad65cbd1c4f86aaaf7066b7 (MD5) Previous issue date: 2021 Orientadora: Profª. Drª Evânia Altina Teixeira de Figueiredo Coorientadoora: Profª. Drª Larissa Morais Ribeiro da Silva Co-orientadora técnica: Drª. Celli Rodrigues Muniz

Microbially induced calcium carbonate precipitation (MICP) process utilising the biogeochemical reactions for low energy cementation has recently emerged as a potential technology for numerous engineering applications. The design and development of an efficient MICP process depends upon several physicochemical and biological variables; amongst which the initial bacterial cell concentration is a major factor. The goal of this study is to assess the impact of initial bacterial cell concentration on ureolysis and carbonate precipitation kinetics along with its influence on the calcium carbonate crystal properties; as all these factors determine the efficacy of this process for specific engineering applications. We have also investigated the role of subsequent cell recharge in calcium carbonate precipitation kinetics for the first time. Experimental results showed that the kinetics of ureolysis and calcium carbonate precipitation are well-fitted by an exponential logistic equation for cell concentrations between optical density range of 0.1 OD to 0.4 OD. This equation is highly applicable for designing the optimal processes for microbially cemented soil stabilization applications using native or augmented bacterial cultures. Multiple recharge kinetics study revealed that the addition of fresh bacterial cells is an essential step to keep the fast rate of precipitation, as desirable in certain applications. Our results of calcium carbonate crystal morphology and mineralogy via scanning electron micrography, energy dispersive X-ray spectroscopy and X-ray diffraction analysis exhibited a notable impact of cell number and extracellular urease concentration on the properties of carbonate crystals. Lower cell numbers led to formation of larger crystals compared to high cell numbers and these crystals transform from vaterite phase to the calcite phase over time. This study has demonstrated the significance of kinetic models for designing large-scale MICP applications.

Artykuł jest próbą omówienia, jakim zaburzeniom neurologicznym u osób dorosłych mogą towarzyszyć zaburzenia pisania. Analiza wybranych form pisemnych jest dowodem na ich występowanie, a tym samym przybliża odkształcenia jakościowe i ilościowe, które mogą pojawić się. Jednocześnie ma na celu zachęcić, oprócz diagnozowania takich zaburzeń do budowania postępowania terapeutycznego. This article is an attempt to discuss what neurological disorders in adults can be associated with writing disorders. The analysis of selected written forms proves their occurrence and thus brings closer qualitative and quantitative deformations that may occur. At the same time, it aims to encourage, apart from diagnosing such disorders, to build a therapeutic procedure.

We introduce a technique for obtaining three-dimensional (3D) profiles of objects captured in two-dimensional (2D) flat images (FI). This technique performs a numerical approximation of the object’s topography from their image gray tones, analyzing topological concepts such as algebraic bases construction, metric functions in terms of such bases, as well as modeling and development of an isomorphism to project masks (fringe patterns) in the FI, allowing us to use the optimal 3D profilometry techniques. Among these techniques, phase shifting (four steps) is applied in the pattern shifts of the projected masks, but with a 2D shift from left to right and from top to bottom, simultaneously. Moreover, the fringe patterns in the masks are binary and with superposed periods in x , y (bi-Ronchi). We show the results of the construction of the masks, as well as their projection into the FIs. We also show the 3D profilometry of the objects after the projection and phase-shifting application and a simple segmentation to observe a particular object. Subsequently, we perform the analysis of a single Mg crystal’s micrography.