Energy Dispersive X-ray Detector Research Articles

Investigation of Hydrogen Embrittlement Effect on Microstructure Mechanical Properties and Fracture of Low-Carbon Steels

Steel hydrogen embrittlement (HE), a complex and multifaceted issue, can lead to sudden and catastrophic failure, without significant plastic deformation, making it a critical concern in the industrial sector. The present investigation focuses on the evaluation of HE effects regarding microstructure, mechanical properties degradation and type of fracture of AISI 1010 low-carbon steel, after accelerated hydrogen cathodic charging. Hydrogen was diffused electrolytically in 0.2 Μ H2SO4 solution, containing 3g/L of NH4SCN, using a cathodic current density of 10 and 20 mA/cm2, for 6 and 18 h. Mechanical properties were investigated through slow-rate tensile tests, as well as Charpy V-notch (CVN) impact tests, to determine the value of fracture toughness, both in uncharged and electrochemically pre-charged specimens. Vickers microhardness tests were conducted on the cross-sections of the hydrogen charged samples to evaluate embrittlement susceptibility, due to the presence of dissolved hydrogen. The microstructure modification was carried out through light optical (LOM) and scanning electron microscopy (SEM), in conjunction with an energy-dispersive X-ray detector (EDS). Slow scan X-ray diffraction (SSXRD) was also conducted for crystal structure analysis. The microstructure analysis showed the presence of large amounts of secondary cracks and cavities into the steel matrix, due to hydrogen diffusion and its accumulation at various sites. Hydrogen charging caused a significant gradual elongation decrease of the parent material, from 25% to 6.73%, in case of embrittlement at 20 mA/cm2 for 18h. Accordingly, after 18 h of exposure, the impact energy decrement was determined at 31.5%, at a current density of 10 mA/cm2, whereas the corresponding reduction at 20 mA/cm2 reached 68%.

Changes in the enamel surface in patients with genetic polymorphism of the VDR gene under the action of remineralizing composition and vitamin D

AIMS: To study the effect of vitamin D and a remineralizing paste on the enamel surface structure in patients with VDR genetic polymorphism.
 MATERIALS AND METHODS: 18 people with a polymorphism index of the VDR A/A gene, a laboratory indicator of 25 (OH) vitamin D in the blood of 18.2 ± 1.84 ng/ml, according to orthodontic indications, the retinated third molars of the lower jaw were removed. Next, the samples were lowered into 3 flasks of 6 pieces with 100 ml of artificial saliva. Containers with teeth were divided into groups: the first – with a solution of artificial saliva only; the second – an additional 1000 ML of an aqueous solution of vitamin D; the third – tooth enamel was treated for 2 minutes with an electric toothbrush with a paste containing a remineralizing composition, immersed in artificial saliva with cholecalciferol 1000ME. The flasks were in the thermostat at a temperature of 37.4 C a day. In all samples, electron microscopy of the enamel contact surface at the level of the crown equator was performed with a Tescan Mira LMU microscope with an Oxford X-MAX 5 energy dispersive X-ray detector with analysis of local mineral composition.
 RESULTS:. In the first group, with electron microscopy of enamel, areas of increased mineralization alternated with areas of reduced density. The coefficient of the molar ratio Ca/P was 1.32 ± 0.13, was regarded as the destruction of hydroxyapatites. In the second group, with vitamin D in artificial saliva, the intercrystalline pore space was filled with calcium and phosphate ions. In the third group, the enamel surface acquired a smooth homogeneous relief. An increase in the weight percentage of trace elements was observed, the Ca/P ratio was 2.2± 0.02, which indicated a phase of remineralization.
 CONCLUSIONS: Patients with VDR polymorphism have a deficiency of vitamin D in the blood serum. The trace element composition of the enamel surface is characterized by a phase of demineralization. Treatment with remineralizing paste and addition of cholecalciferol solution to artificial saliva, changes the structure of hydroxyappatite, increases the caries-resistant properties of enamel.

Advances in Lead-Barium-Zinc-Silicate-Type Glazed Warming Bowl Related to the Chinese Xuande Reign (1426–1435)

Diagnostic investigations were carried out on a rare Chinese polychrome glazed ceramic dating back to the reign of the Xuande Emperor (1426–1435). The double-walled warming bowl was investigated using several non-invasive methods such as portable optical microscopy, endoscopy, portable X-ray fluorescence spectrometry, X-radiography, and computed tomography. One microsample was collected and analyzed by scanning electron microscopy with an energy dispersive X-ray detector. According to the results, the chemical composition of the paste suggested a porcelain typology, while the glaze belongs to the lead–barium–silicate (PbO-BaO-ZnO-SiO2) system. These unexpected data contrast with common knowledge, which attests that the addition of barium in glass and ceramics manufacturing disappeared soon after the Han dynasty (206 BCE-220 CE). Moreover, the combination of PbO-BaO-ZnO-SiO2 seems to be quite rare both in ancient pre-Han times and during the Ming and Qing dynasties. This paper aims to demonstrate that (a) the use of barium for glaze and glass composition, which seems to have its roots in Taoist alchemy, was not totally halted in later periods compared to the Han dynasty; (b) lead–barium–zinc–silicate glaze was used during the Xuande Emperor’s reign. Through a review of ancient Chinese literary sources, we found a lot of unpublished information on the use of barium, lead, and zinc in the production of glazed ceramics during this period. The polychrome glazed warming bowl suggests a particular production that flourished during the brief reign of the Xuande Emperor.

Transient submillimeter-scale periodic banding of Ag2O precipitate through reaction–transport–reaction processes

We describe a new class of the periodic banding of Ag2O precipitates through reaction–transport–reaction processes in an agarose-hydrogel column; the gel contains NaNO3 as an additive and is inserted between Ag and Ti rods with an applied constant voltage of 4.0–7.0 V. Submillimeter-scale periodic dark-brown precipitation bands were transiently generated with high reproducibility in this system, in which (i) electrochemical reactions at the metal rods to generate Ag+ and OH−, (ii) transportation of the reactant ions by the electric field, and (iii) reactions to produce Ag2O are expected to couple. The bands successively emerged mainly toward the cathode, accompanied by substantial changes in the electric current through the gel. The periodic banding depended on the applied voltage, duration of application, and concentration of NaNO3 initially loaded in the gel. The banding was most clearly observed in a 2.0 mass% agarose gel column containing 0.005 M NaNO3 under a constant applied voltage of ∼5.5 V for ∼3 h. This optimal condition resulted in more than ten periodic bands, of which the bandwidth (w) and the distance between the adjacent bands (d) were randomly distributed around the average values: for the bands formed up to 2 h, w = 0.25 ± 0.04 mm and d = 0.42 ± 0.05 mm; for the bands formed after 2 h, w = 0.42 ± 0.11 mm and d = 0.68 ± 0.07 mm. The generated periodic bands were gradually painted out with time to form an almost continuous broad band, even after the applied voltage was discontinued, although immersion of the gel in deionized water for 3 h could suppress this uniformization. Observations using optical and scanning electron microscopes with an energy-dispersive X-ray detector suggested that the periodic bands were composed of gelatinous Ag2O and micrometer-scale (1–50 μm) clusters, which comprised Ag-abundant nanoparticles with considerable size dispersion (10–500 nm). The relationship between the periodic banding and inhomogeneous distribution of the reactant ions and potential applications of the observed banding phenomena are discussed.

Mekanik alaşımlama ile üretilen Al4.5Cu/TiO2 kompozitlerinin mikroyapı, sertlik ve termal özellikleri

Al4.5Cu/TiO2 composites were fabricated from their elemental powders by the mechanical alloying method. Microstructural and thermal properties of the composites were investigated by a combination of differential thermal analysis (DTA), scanning electron microscopy with energy dispersive X-ray detection (SEM-EDX), and X-ray diffraction (XRD). Microstructural evolutions, phase transformations, and crystallite size changes were investigated depending on the milling time. XRD and SEM results showed that there were a more homogeneous structure and shrinkage in grain size due to the increased milling time. The DTA results showed an endothermic peak of around 650 oC which indicates the melting temperature of Al. Besides, the mechanical properties of the pressed and sintered composites were investigated by Vickers micro-hardness testing. The results showed that microhardness values significantly increased as milling time increased from 5h to 10h. The maximum microhardness value of 173±10 HV was obtained for Al4.5Cu with 20 wt% TiO2 composite after milling for 10h.

Investigation of the inner microstructure of composite materials during their densification by scanning electron microscopy – LSM:YSZ electrode case study

An understanding of the high-temperature processes, such as sintering, remains a challenge despite its paramount importance, and has yet to be achieved by the scientific community. Scanning electron microscopy is a valuable technique for investigating morphological changes, including elemental composition, by means of an energy-dispersive X-ray detector associated with these processes, with high resolution in-situ. Historically, this technique has been limited to experiments conducted at ambient temperature. However, by integrating scanning electron microscopy with a MEMS® heating chip, this limitation can be overcome, enabling the study of solid-state processes at temperatures of up to 1 200 °C. This study demonstrates one potential application of in-situ scanning electron microscopy – the densification of La1-xSrxMnO3-δ : (ZrO2:Y2O3) composite. This material, employed as an oxygen electrode in solid oxide cells, exhibits a complex microstructure. Achieving a balance between effective particle interconnection, ensuring high electric conductivity, and efficient mass transport through its porous structure is crucial. A comprehensive understanding of microstructure and surface composition evolution during the sintering process is vital to addressing trade off when optimizing densification conditions. It was shown that the densification of La1-xSrxMnO3-δ : (ZrO2:Y2O3) composite occurs in two steps. At 900 °C a significant additional porosity emerged due to the La1-xSrxMnO3-δ phase shrinkage (densification). The main densification process at 1 150 °C then acts as a self-healing mechanism, leading to the formation of a well-interconnected microstructure. Interparticle ligament formation is exclusively induced by the La1-xSrxMnO3-δ phase. Notably, no common degradation processes, such as La2Zr2O7 formation, were observed under the experimental conditions employed. This study underscores the promise of scanning electron microscopy with a heating chip extension for in-situ investigations pertinent to various high-temperature technologies.

Effect of Hexagonal Boron Nitride on Morphology, crystallinity and internal Exfoliation properties of Polypropylene melt and solid phases

ABSTRACT Polypropylene (PP) is one of the most important polymers widely used in different industries due to its many superior properties. Hexagonal boron nitride (hBN) is generally used in the electronic packaging industry and insulator material production due to its high thermal conductivity and low electrical conductivity. However, the lubrication properties have not yet been examined in the polymer matrix. The main purpose of this study is to examine the lubricating properties of hBN in the PP matrix and to expand its application areas. In this research, hBN/PP composites have been produced and characterized by scanning electron microscopy with an energy dispersive X-ray detector (SEM-EDX) and the differential scanning calorimeter (DSC), respectively. The linear viscoelastic behaviors (LVBs) and rheological properties of the hBN/PP composites have been investigated at 190°C by hybrid rheometer which had high temperature plate-plate geometry system; furthermore, the SEM has been used for searching hBN particles deformation, which was mechanical deformation and distribution into the PP. The oscillation sweeps tests have shown that the critical strain values and the gelation point of composites decreased with the increasing of the hBN content into the composites. Over the 10%, hBN addition into the PP elevated internal lubrication by the exfoliation of hBN plaques. The Williamson model and the discrete retardation spectrum (DRS) equation has been applied on the hBN loaded PP composites and the PP.

Multi-Analytical Techniques for the Study of Burial Clothes of Polish King Sigismund III Vasa (1566-1633) and His Wife Constance Habsburg (1588-1631).

The subjects of this research are the burial clothes of Polish King Sigismund III Vasa and his wife Constance, which were woven and embroidered with silk and metal threads. Fragments of the textiles underwent spectroscopic, spectrometric, and thermogravimetric analyses. The hydrofluoric acid extraction method was improved to isolate various classes of dyes from the textile samples that had direct contact with human remains. High-performance liquid chromatography, coupled with diode array and tandem mass spectrometry detectors with electrospray ionization (HPLC-DAD-ESI-MS/MS) facilitated the detection and identification of colorants present in the textiles. Cochineal, indigo-, madder-, orchil-, and tannin-producing plants were identified as the sources of dyes used. Scanning electron microscopy with an energy-dispersive X-ray detector (SEM-EDS) was employed to identify and characterize the silk fibers and mordants and the metal threads. The presence of iron, aluminum, sodium, and calcium in the silk threads suggests their potential use as mordants. The analysis of the metal threads revealed that most of them were made from flattened gilded silver wire, with only a few being cut from a sheet of metal. Typical degradation mechanisms of metal threads were shown, resulting from both burial environment and earlier manufacturing process, and the use of the textiles in clothing, i.e., a significant loss of the gold layer was observed in most of silver gilt threads, caused by abrasion and delamination. The results of the thermal analysis confirmed the presence of silk and silver threads in the examined textiles.

Coal Fire Sublimates: Are We Missing Something?

Uncontrolled coal fires present a nearly unparalleled environmental and human health disaster. These fires can cause the destruction of the ecosystem, ignite forest fires, become a source of windblown dust and siltation of streams, and pollute surface water, ground water, and crops. They can cause significant disruption of families and communities resulting from physical hazards of collapse or explosion, excessive heat, visual blight and loss of potentially valuable acreage, deterioration of cultural infrastructure, personal and public property, and loss of a valuable energy resource. The emission of CO2 and other greenhouse gases presents a significant health hazard due to respiration of dust and aerosols, and exposure to acidic gases, potentially toxic trace elements, and organic compounds. Numerous studies have described many dozens of phases that have condensed from the effluents of these fires. However, many of these studies may have overlooked the nano- and ultra-fine particles that exist beside, in, and under the brightly colored, often spectacular crystalline macro phases. Using a scanning electron microscope with an energy dispersive X-ray detector we examined a small (30 mm × 10 mm) piece of condensate from an uncontrolled coal fire in the Jharia region of India and found more than 30 different phases in this one small piece. The phases included ammonium, copper, iron, lead, bismuth chlorides; bismuth, lead, and ammonium silici-fluorides; ammonium and lead iodates; iron, barium, lead, copper, and zinc sulfides; iron and silicon oxides; and others. Broken fragments revealed multiple generations of phases. Though not strictly nanoparticles (smaller than 0.1 μm), many of these particles are in the micrometer to sub-micron range and it is likely that there are phases present in the nanoparticle size range. Certainly, particulates in the nanoparticle and ultra-fine particle range are being released from the uncontrolled coal fires and may be impacting the environment and the health of the mine workers and nearby residents, an issue that should be investigated.

Some new insights into the biological activities of carboxymethylated polysaccharides from Lasiodiplodia theobromae

BackgroundCarboxymethylated Lasiodiplodan (LaEPS-C), Lasiodiplodia theobromae β-glucan exopolysaccharide derivative, has a well-known range of biological activities. Compared to LaEPS-C, its fractions, Linear (LLaEPS-C) and Branched (BLaEPS-C), have biological potentialities scarcely described in the literature. So, in this study, we investigate the immunomodulatory, antiviral, antiproliferative, and anticoagulant activities of LLaEPS-C and BLaEPS-C and compare them to the LaEPS-C.MethodsLaEPS was obtained from L. theobromae MMBJ. After carboxymethylation, LaEPS-C structural characteristics were confirmed by Elementary Composition Analysis by Energy Dispersive X-Ray Detector (EDS), Fourier Transform Infrared (FTIR), and Nuclear Magnetic Resonance (NMR). The immunomodulatory activity on cytokine secretion was evaluated in human monocyte-derived macrophage cultures. The antiviral activity was evaluated by Hep-2 cell viability in the presence or absence of hRSV (human respiratory syncytial virus). In vitro antiproliferative activity was tested by sulforhodamine B assay. The anticoagulant activity was determined by APTT (Activated Partial Thromboplastin Time) and PT (Prothrombin Time).ResultsLaEPS-C showed low macrophage cell viability only at 100 µg/mL (52.84 ± 24.06, 48 h), and LLaEPS-C presented no effect. Conversely, BLaEPS-C showed cytotoxicity from 25 to 100 µg/mL (44.36 ± 20.16, 40.64 ± 25.55, 33.87 ± 25.16; 48 h). LaEPS-C and LLaEPS-C showed anti-inflammatory activity. LaEPS-C presented this at 100 µg/mL (36.75 ± 5.53, 48 h) for IL-10, and LLaEPS-C reduces TNF-α cytokine productions at 100 µg/mL (18.27 ± 5.80, 48 h). LLaEPS-C showed an anti-hRSV activity (0.7 µg/ml) plus a low cytotoxic activity for Hep-2 cells (1.4 µg/ml). LaEPS-C presented an antiproliferative activity for NCI-ADR/RES (GI50 65.3 µg/mL). A better PT was achieved for LLaEPS-C at 5.0 µg/mL (11.85 ± 0.87s).ConclusionsThese findings demonstrated that carboxymethylation effectively improves the biological potential of the LaEPS-C and their fractions. From those polysaccharides tested, LLaEPS provided the best results with low toxicity for anti-inflammatory, antiviral, and anticoagulant activities.

Residual mechanical performance and rust characterization of self-prestressing UHPM subjected to chloride-induced corrosion

Chloride-induced corrosion poses extreme vulnerabilities to the strength degradation and delamination of reinforced concrete structures in the oceanic environment. For this reason, the self-prestressing effect produced from the synergy of the combined addition of expansive agent (EA) and steel fibre (SF) into the concrete is suggested to enhance the corrosion performance (cracking and degradation) of concrete-steel tubular columns (CSTCs). Four mortar mixtures were prepared with the no EA and SF, individual use of EA or SF and combined use. The corrosion rate was measured by the linear polarization resistance (LPR) method, while crack-width and pit-depth were measured with scanning electron microscopy (SEM). Test results revealed that the self-prestressing ultra-high-performance mortar (UHPM) prepared by the combined use of EA and SF reduced the corrosion rate, pit depth, and crack width up to 87.3%, 55.8%, and 68.3%, respectively. Furthermore, it also results in the highest residual compressive strength. The corrosion products characterized by using an energy-dispersive x-ray detector (EDX) and x-ray diffractometry (XRD) for self-prestressing UHPM were oxides with a volume ratio to parent iron of approximately 2, which is the lowest amongst all and justifies its superior performance.

Effects of co-combustion Fe-rich mediocre ash coal on slag deposition of Ca-rich Zhundong coal in a 0.4 MW pilot-scale facility

A type of coal with low calorific value and high ash content, locally known as mediocre ash coal (MAC), has been discovered in the interlayer of stratified coals in Jiang Jun Temple area Zhundong district, Xinjiang, China. In order to investigate slag deposition on the convective heating surface during co-combustion of MAC and Wucaiwan Ca-rich Zhundong Coal (WCW), a 0.4 MW pilot-scale facility, with tube panels #1 and #2 located in horizontal flue gas ducts, was constructed. The tube panels were designed to simulate the superheater and reheater of the Π-type boiler. FactSage was utilized to simulate the material balance, whereas the classic models were employed to calculate the slag viscosity. Combustion tests were conducted while maintaining flue gas temperatures (FGT) of 1050∼1100 °C and 900∼950 °C at tube panels #1 and #2, respectively, which were consistent with those observed during sole combustion of WCW. The slags collected from tube panels were analyzed by X-ray fluorescence, X-ray diffraction and Scanning Electron Microscopy coupled with Energy Dispersive X-ray Detector. Furthermore, Computer-Controlled Scanning Electron Microscopy analysis was used to obtain a quantitative characterization of the symbiotic relationship among mineral elements. The study of co-combustion MAC led to the following conclusions: The liquid phase ratio of slag decreased by 44% compared to sole combustion of WCW at 1100 °C. The viscosity was higher than that of sole combustion of WCW from 900 to 1650 °C. Compared to the sole combustion of WCW, the average S, Ca, and Na contents in the slag obtained on the two tube panels decreased by more than 85%, 40%, and 43.5% respectively. Sulfate formation in the slag on the tube panel was significantly reduced at medium to low FGT, and no Na2SO4 and CaSO4 compounds could be detected in the slag. The interaction between Fe-bearing minerals and Si- and Al-bearing minerals during combustion was evidently stronger than that between Ca-bearing minerals and Si- and Al-bearing minerals during combustion. The interaction of Fe with Ca/Na during medium to high FGTs led to a decrease in Si/ Al consumption, thereby increasing their availability for reacting with Ca/Na at medium to low FGTs. As a result, the formation of Na2SO4 and CaSO4 was inhibited.

Bonding Characteristics of Grey Cast Iron and Microalloyed Steel Using Furnace Brazing

The present research work focuses on the study of the microstructure evolution, corrosion resistance, and mechanical properties of GG25 grey cast iron and AISI 4140 microalloyed steel dissimilar brazing joints, using a eutectic type Ag-based filler metal. The welding zone microstructure study was carried out through optical (OM) and scanning electron microscopy (SEM), in conjunction with an energy-dispersive X-ray detector (EDS). Joints’ mechanical properties were investigated through tensile tests, as well as detecting the Vickers microhardness across the microstructure’s zones. For the assessment of the joints’ corrosion resistance, potentiodynamic polarization tests were performed in 3.5 wt% NaCl solution, at various temperatures. The corrosion products evaluation was carried out by both X-ray Diffraction (XRD) and scanning electron microscopy (SEM). According to the results, sound brazing joint was attained, presenting an average tensile strength and ductility of about 230 MPa and 20 %, respectively.

Pyrolysis kinetic study of the thermal degradation of pre-treated empty fruit bunches

Empty fruit bunch (EFB) wastes are a significant source of biomass waste in Malaysia and have the potential to be a high-quality source of energy. This study aims to evaluate the kinetic of EFB biochar degradation and its characteristics under three conditions of washing pre-treatments. Prior to biochar production via slow pyrolysis process, stirring and soaking techniques were utilised as part of the pre-treatment for the washing process, with varying solid-to-liquid (S:L) ratios of 1:50, and 1:50 to 1:70, respectively. The study analysed the higher heating value (HHV), pyrolysis yield and kinetic activation energy of the biochar. The morphology and elemental composition of the biochar samples were determined using ultra-high resolution scanning electron microscopy (UHR-SEM) and energy dispersive X-Ray detector (EDX). The Coats-Redfern model was used to estimate the activation energies of the EFB biochar from thermogravimetric (TGA) data in a temperature range of 30 °C to 800 °C and a constant heating rate of 10 °C/min under a nitrogen atmosphere. The results showed that washing pre-treatment significantly changed the morphology and elemental compositions of the EFB biochar samples. The higher S:L ratio of 1:70 has a more significant impact on the breakdown of the lignocellulosic structure of EFB. The soaked samples had slightly lower biochar and bio-oil yields (22.73 mf wt. % to 24.86 mf wt. % and 27.97 mf wt. % to 39.39 mf wt. %, respectively) than the stirred samples (25.22 mf wt. % and 49.59 mf wt. %). The pre-treatment process improved the carbon content while reducing potassium by 60.7 to 81.39%. The HHVs of EFB-4 (28.24 MJ/kg) and EFB-3 (26.57 MJ/kg) were higher than those of EFB-2 (26.2 MJ/kg) and EFB-1 (23.14 MJ/kg), indicating an improvement in their fuel properties. The higher kinetic activation energies of EFB-4 (43.27 to 48.30 MJ/mol) indicate better thermal stability than the others. Therefore, concerning improved fuel properties, the recommended pre-treatment of EFB for the pyrolysis process is soaking at 90 °C with an S:L ratio of 1:70. The kinetic analysis revealed that the pyrolysis of pre-treated EFBs follows a multi-step reaction mechanism, with different activation energies for each stage. The obtained kinetic parameters can be used to optimize the pyrolysis process and design efficient pyrolysis reactors for the valorization of EFBs. Overall, this study provides valuable insights into the thermal behavior of pre-treated EFBs and their potential for bioenergy production.

Influence of feedstock mixtures on the fuel characteristics of blended cornhusk, cassava peels, and sawdust briquettes

This study investigated the influence of feedstock mixture on the fuel characteristics of briquettes produced from sawdust (SD), cornhusk (CH), and cassava peels (CP) for domestic and industrial applications. The feedstock was each studied singly and mixed in the ratio 30/70, 50/50, and 70/30 with the binder to feedstock ratio of 20:100 by mass for briquette production and characterization. The elemental and proximate analyses were carried out to evaluate fuel properties. The briquette structural arrangement was determined with the Scanning Electron Microscope and Energy Dispersive X-Ray Detector, while the functional groups was obtained from FTIR analyzer. A non-isothermal Coats-Redfern method was carried out to determine the activation energy and pre-exponential factors. The O/C and H/C ratios slightly decrease when the mixing ratio of sawdust with other feedstocks increased. The bonding of the briquette samples was enhanced by blending CH with other feedstocks, thereby improving the structural integrity of the mixed briquettes and closing the gaps and voids within and between particles. The highest infrared transmittance of C–H, OH, C–O, and C=C was found in SD briquette followed by CH and CP while CH briquette contained higher C–C. The activation energy of the briquettes varied between 39.70 and 60.76 kJ/mol. The hypothetical thermal plant analysis of the briquettes shows that mixed CH/CP and CH/SD respectively reduced the potential for CO2 and NO2 emissions. Furthermore, Ca, P, and K played the most significant role in the briquette’s agglomeration. The mixing of feedstocks for briquettes production has great fuel potential for heating applications.

Variation in Juvenile Long Bone Properties as a Function of Age: Mechanical and Compositional Characterization.

Bone is a heterogeneous, hierarchical biocomposite material made of an organic matrix filled with a mineral component, which plays an important role in bone strength. Although the effect of the mineral/matrix ratio on the mechanical properties of bone during aging has been intensively investigated, the relationship between the mechanical properties and the chemical composition of bone with age requires additional research in juvenile individuals. In this study, bone coupons from bovine and ovine animal species were machined from cortical areas of long bones to quantify whether the variation in mechanical properties at different stages of development is related to the change in the composition of bone tissue. An energy-dispersive X-ray detector (EDX) attached to a scanning electron microscope (SEM) was used to perform a compositional analysis of the tissue. In addition, nanoindentation analyses were carried out to address how the elastic modulus changed with age. Nonparametric statistical analyses found significant differences (p < 0.05) in Ca content and elastic modulus between species, but no differences were found within each species with development. A multiple linear regression model found that the elastic modulus was significantly related to the decrease in P and C in the samples, to the animal species (larger in bovine), and development, although not linearly. This model also found an interaction between Ca and development that could explain the lack of significance of the relationship between the elastic modulus and development in the univariate models.

The Effect of Surface Treatments on Zirconia Bond Strength and Durability.

To evaluate the effects of airborne particle abrasion (APA) combined with MDP-containing resin cement, a glass-ceramic spray deposition (GCSD) method on the shear bond strengths (SBSs) and durability of 3 mol% yttrium oxide-stabilized zirconia ceramic (3Y-TZP) compared with lithium disilicate glass ceramics (LDGC). 3Y-TZP disks were randomly treated as follows: for Group APA+MDP, 3Y-TZP was abrased using 50 μm Al2O3 particles under 0.1 Mpa and bonded with MDP-containing resin cement; for Group GCSD, 3Y-TZP was treated with the GCSD method, etched by 5% HF for 90 s, silanized and bonded with resin cement without MDP. Group LDGC was bonded as the Group GCSD. X-ray diffraction (XRD), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-ray detector (EDX) were used to analyze the surface chemical and micro-morphological changes of the ceramics before bonding. The bonded ceramic specimens were randomly divided into subgroups, and the SBSs were determined before and after 10,000 thermocycling. The SBSs were analyzed with a one-way ANOVA analysis. Failure modes were determined with optical microscopy and SEM. The XRD, ATR-FTIR and XPS results identified the formation of lithium disilicate and zirconium silicate on 3Y-TZP after GCSD. The SEM micrographs revealed that 3Y-TZP surfaces were roughened by APA, while 3Y-TZP with GCSD and LDGC surfaces could be etched by HF to be porous. The APA treatment combined with MDP-containing resin cement produced the high immediate zirconia shear bond strengths (SBSs: 37.41 ± 13.51 Mpa) that was similar to the SBSs of the LDGC (34.87 ± 11.02 Mpa, p > 0.05), but, after thermocycling, the former dramatically decreased (24.00 ± 6.86 Mpa, maximum reduction by 35.85%) and the latter exhibited the highest SBSs (30.72 ± 7.97 Mpa, minimum reduction by 11.9%). The 3Y-TZP with GCSD treatment displayed the lower zirconia SBSs before thermocycling (27.03 ± 9.76 Mpa, p < 0.05), but it was similar to the 3Y-TZP treated with APA and MDP containing resin cement after thermocycling (21.84 ± 7.03 vs. 24.00 ± 6.86 Mpa, p > 0.05). The APA combined with MDP-containing resin cement could achieve the high immediate zirconia SBSs of those of the LDGC, but it decreased significantly after thermocycling. The GCSD technique could yield the immediate zirconia SBSs similar to those of LDGC before thermocycling, and long-term zirconia SBSs were similar to those of 3Y-TZP treated with APA followed by MDP-containing resin cement after thermocycling. Hence, the GCSD technique could enrich zirconia surface treatments and is an alternative to zirconia surface pretreatment for 3Y-TZP bond durability.

Polypyrrole-Barium Ferrite Magnetic Cryogels for Water Purification

Magnetic polypyrrole-gelatin-barium ferrite (PPy-G-BaFe) cryogels/aerogels were synthesized by one-step oxidative cryopolymerization of pyrrole in the presence of various fractions of barium ferrite (BaFe) nanoparticles, dispersed in aqueous gelatin solution. The successful incorporation of BaFe into the composites was confirmed by elemental analysis and scanning electron microscopy paired with an energy-dispersive X-ray detector. The maximum achieved content of BaFe in the resulting material was 3.9 wt%. The aerogels with incorporated BaFe had significantly higher specific surface area and conductivity, reaching 19.3 m2 g-1 and 4 × 10-4 S cm-1, respectively, compared to PPy-G aerogel, prepared in the absence of BaFe (7.3 m2 g-1 and 1 × 10-5 S cm-1). The model adsorption experiment using an anionic dye, Reactive Black 5, showed that magnetic PPy-G-BaFe aerogel, prepared at 10 wt% BaFe fraction, had significantly higher adsorption rate and higher adsorption capacity, compared to PPy-G (dye removal fraction 99.6% and 89.1%, respectively, after 23 h). Therefore, the prepared PPy-G-BaFe aerogels are attractive adsorbents for water purification due to their enhanced adsorption performance and the possibility of facilitated separation from solution by a magnetic field.

Cyclic growth and tillering of layered polycrystalline zinc hydroxide sulfate and the resulting dendritic fractals

Two-dimensional dendritic fractals of layered zinc hydroxide sulfate (LZHS) were allowed to grow on a porous ZnO substrate-coated glass slide in an aqueous ZnSO4 solution through the dissolution-redeposition process. The generated LZHS seeds with polycrystalline structure gradually evolved into two-dimensional dendritic fractals with a diameter of 50∼100 μm through a plant-like growth mode involving tillering and the formation of layered tiller buds at branch ends. Such tiller mechanism is proposed to explain the evolution of LZHS fractals based on results obtained by the scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, and energy dispersive X-ray detection. The synthesized polycrystalline LZHS fractals can be topologically converted into hierarchical nanostructured zinc oxide by thermal pyrolysis combined with an alkaline wash process. After the modification by octyltrimethoxysilane, the topological zinc oxide surfaces, corresponding to the immersion time of 2, 4 and 6 h, showed superhydrophobic property with a water contact angle of 153.4°, 157.6°, and 164.7°, respectively. The enhanced hydrophobicity of zinc oxide films compared with the porous ZnO substrate surface is mainly attributed to the topological fractal morphologies and hierarchical nanostructures.

Identifying the causes of the two-part engine piston destruction in a gas-diesel mining dump truck

Introduction. The paper considers the relevance and prospects of using liquefied natural gas in BelAZ 75131 mining dump trucks. It is an alternative fuel source which allows reducing greenhouse gas emissions. Accidents occurring in the course of such gas-diesel dump trucks operation are associated with the destruction of one two-part piston from the entire KTA 50-C engine piston group. Research objective is to find the cause of the KTA 50-C engine two-part piston destruction during its gas-diesel operation by studying its microstructural characteristics. Methods of research. Тhree prototypes from different parts of a two-piece piston are sampled for research. The microstructural characteristics of the prototypes were studied using a JEOL JSM-6390 LV scanning electron microscope with a JED 2300 energy-dispersive X-ray detector under certain regulated conditions. Research results. The results of the microstructure studies showed the difference in the elemental mass composition of the aluminum alloy of the piston’s upper and lower parts, as well as the presence of more developed caverns and microcracks in the upper part of the piston than in the lower one. Analysis and discussion. At high operating temperatures and variable high-frequency pressures, the presence of cavities in the upper part of the piston contributed to the formation and propagation of large microcracks, which subsequently led to its destruction. There is a hypothesis that liquefied natural gas used as motor fuel may lead to the destruction of the two-part piston aluminum alloy upper part as it increases the operating temperature in the cylinder by 3–3.5%. This hypothesis has been proved invalid. Conclusions. The cause of the two-part piston destruction was found and revealed no interconnection with the conversion of BelAZ 75131 mining dump truck to dual-fuel (gas-diesel) operation using liquefied natural gas as motor fuel. A recommendation was given to enterprises operating and repairing mining equipment.