Micron Size Research Articles

Increasing the efficiency of coagulation in resonant gaps due to acoustic flow formation

Relevance. The urgent need to eliminate environmental pollution from industrial emissions of various solid particles. At the same time, maximum attention is paid to cleaning exhaust gases from particles of 2.5 microns in size or less. One of the most promising ways to increase the efficiency of existing gas purification equipment in capturing such particles is their coagulation by exposing the gas flow to high-intensity acoustic vibrations of ultrasonic frequency. However, at low concentrations, even at the maximum permissible sound pressure level, the coagulation efficiency of particles smaller than 2.5 microns is insufficient to increase the recovery rate of gas cleaning equipment. Therefore, there is an urgent need to find new ways to further improve the efficiency of ultrasonic coagulation of particles smaller than 2.5 μm. Aim. To determine the conditions for the formation of vortex flows in ultrasonic fields with the maximum ultrasonic influence in terms of sound pressure level. Conducting comparative studies of the coagulation of particles with a size of 2.5 microns with and without vortex flows. This will make it possible to determine the real values of increasing the efficiency of ultrasonic coagulation during turbulization of a gas-dispersed flow by acoustic flows in comparison with coagulation in a uniform ultrasonic field and without it. Objects. Coagulation of particles under the influence of homogeneous and inhomogeneous ultrasonic fields. Methods. Computer modeling of the formed ultrasonic field by the finite element method using harmonic acoustic analysis. The paper considers the experimental method for studying the process of combining particles under the influence of ultrasonic vibrations. To determine the characteristics of an aerosol during experimental studies, a TIPAS-1 meter based on the small-angle scattering method and the spectral transparency method was used. Results. The paper introduces the results of studies of coagulation of particles with a size of 2.5 microns or less in an ultrasonic field formed in resonant gaps by oscillating disk emitters. The authors proposed to increase the efficiency of coagulation in resonant gaps through the use of ultrasonic disk emitters capable of forming alternating zones of maximum and minimum amplitude oscillations in the resonant gaps. The creation of such zones ensured the formation of vortex-type acoustic flows capable of moving particles within the nodal regions of a standing wave and between them. The involvement of small particles in the formed flows made it possible to increase the probability of their collision. It was established that more effective ultrasonic coagulation provides an increase in the degree of inertial capture for particles of 2.5 microns in size by 6% – from 89 to 95%, for particles of 1.5 microns in size by 7% – from 85 to 92%, and for particles of 0.5 microns by 9% – from 76 to 85%.

TREATMENT FOR REMOVING ZN COMPOUNDS FROM SILICA-FILLED VULCANIZED RUBBER AND ANALYSIS OF SILICA AGGREGATE DISPERSION

ABSTRACT Treatment of silica-filled rubber vulcanizates with a diethyl ether/concentrated hydrochloric acid solution for 96 h at room temperature can remove most Zn compounds smaller than approximately 90 nm, which account for most of the residual ZnO, rubber-soluble Zn compounds and ZnS resulting from crosslinking reactions of by-products. However, a very small number of giant ZnO particles of a few micrometers in size remain after such treatment. In the silica-filled SBR matrix treated for 96 h, a significant increase in crosslink density and Young’s modulus was observed due to crosslinking reactions after HCl was removed from HCl-added rubber molecules. This increase in crosslink density was accompanied by an increase in the surrounding layer of bound rubber closest to the silica of the two bound rubber layers around it and a decrease in the rubber matrix of the same volume. It is inferred that there was little change in the aggregate structure of the silica due to these volume changes. Alternatively, ultra-small X-ray scattering measurements of the treated samples showed shoulders derived from silica aggregates and clear high-resolution X-ray computed microtomography (X-ray CT) images were obtained due to the removal of Zn compounds smaller than approximately 90 nm in size. The relationship between these shoulders and the size of silica aggregates obtained by X-ray CT imaging was qualitatively consistent, and it was not affected by the presence or absence of bis-(3-triethoxysilylpropyl) tetrasulfide and 1,3-diphenylguanidine, but was dependent on the rubber type. The distance between nearest neighbor particles of silica aggregates, determined by X-ray CT imaging, also depended on the types of rubber.

Comparative Analysis of Locally Sourced Adsorbents for Iponda and Idominasi, Abandoned Gold Mine Wastewater Bioremediation in Osun State, Nigeria

This study investigates and compares the effects of Neem leaf (NL) and coconut husk (CCH) adsorbents in reducing the levels of heavy metal concentration and elemental content in wastewater from two specific abandoned gold mining sites, namely Iponda (Iponda wastewater- IPWW) (longitude 4°43'18''E, Latitude 7°43'57''N ) and Idominasi (Idominasi wastewater -IDWW) (longitude 4°42'0''E, Latitude 7°40'59''N). Preparation of locally sourced adsorbents, bioremediation process through adsorption and physico-chemical analysis of the treated wastewater samples were carried out. Adsorbents were prepared from washed, air-dried neem leaves, grinded to 40 microns size to facilitate penetration of the adsorbate. In addition, washed and airdried CCH was carbonized in an electric muffle furnace at between 300 0C and 350 0C over a period of 30 minutes, and then granulated and sieved with a mesh size of 40 µm to ensure uniform size. Measured dosages of adsorbent (0.5 g, 0.75 g, and 1 g) were added to a 50 ml volume of wastewater and the mixture was agitated at different speeds ranging from 30 rpm to 120 rpm. The treated wastewater samples were then subjected to various physico-chemical analytical tests to determine the effect of the adsorbents on the reduction of the heavy metal concentration and elemental content of the wasted water samples. The results of this study demonstrate that both NL and CCH adsorbents have a significant impact on the wastewater from the two abandoned gold mining sites, IPWW and IDWW. This impact is reflected in the reduction of heavy metal and other element concentrations in the wastewater. Furthermore, it can be concluded that the bioremediation process is more effective when utilizing NL compared to carbonized CCH. Locally sourced cheap non-edible biomass materials hitherto considered as wastes have proved to be highly effective and efficient when used as adsorbents in the treatment of wastewater from abandoned gold mining sites. This is evident from the results obtained from this study.

Marginal Aggregates: The Role of Clays.

Clays are components in the fine portion of aggregates, less than 75 microns in size (micro-fines), which are usually washed away when producing coarse or fine (manufactured sand) aggregates in quarries. When marginal sources of aggregates are being used, the content of this washed portion can be quite high, and there is an incentive to keep as much of it in the aggregate, including the clays. The present paper presents a comprehensive treatment of the role of clays in terms of the characterization of their composition and quantification of their effects on the rheological and mechanical properties of cementitious systems, as well as the means to mitigate deleterious influences. It is shown that the strategy for neutralizing the effect of micro-fines containing clays on increased water demand in concrete can be quantified in terms of the combination of their content in concrete and their nature as characterized by the methylene blue value (MBV); this is a more rational approach to considering their influence than their content in specific aggregates as specified in standards. The effect of low and medium MBV aggregates on the water requirement can be neutralized by lignosulfonates when their content in the concrete is below a threshold value of about 150 kg/m3; polycarboxylates (PC) are required at higher contents; for high MBV aggregates, a combination of PC and clay mitigating admixture (CMA) is required. It is also demonstrated that with proper treatment, such micro-fines can be turned into useful fillers, enhancing the strength of concrete and thus also serving as a means for reducing cement content.

Participation of strong charge-assisted hydrogen bonds in interactions of dissolved organic matter represented by Suwannee River Humic Acid

Terrestrial dissolved organic matter (DOM) plays critical roles in many biotic and abiotic environmental reactions as well as in water treatment. Its structure is therefore of great interest. We examined dissolved Suwannee River Humic Acid (HA) to probe the potential participation of exceptionally strong, negative charge-assisted hydrogen bonds, (−)CAHB, in DOM cohesion and interaction with small weak acids using high performance size exclusion chromatography (HPSEC), transmission electron microscopy, zeta-pH curves, and pH drift experiments. The results support a previously proposed two-tier state of aggregation, in which tightly-knit primary particles (≤ ∼10 kDa) form larger secondary aggregates (up to micrometer in size). Evidence for (−)CAHB is gained through zeta potential changes and pH drift experiments. The primary particles interact with (−)CAHB-capable solutes (simple carboxylic acids and phosphate) but not (−)CAHB-incapable solutes. We identified disruption of intra-segmental and inter-molecular (−)CAHB leading to swelling and disaggregation, as well as formation of nouveau (−)CAHB with free groups on HA. The effects were solute-concentration dependent and greater at pH 5 than pH 6, consistent with CAHB theory. Phosphate induced the greatest shifts in the HPSEC molecular size distribution curves. The shifts were unaffected by prior stripping of innate polyvalent metals. We conclude that the (−)CAHB contributes to the cohesion of DOM, affecting its size and charge, and provides a means by which weak acid pollutants, nutrients, and natural compounds can interact with DOM. Such interactions have implications for the behavior of DOM in the environment, the fate and transport of anthropogenic pollutants, and the roles DOM play in water treatment technologies.

Live imaging of center of calcification formation during septum development in primary polyps of Acropora digitifera

Recent studies have revealed that stony corals create their extracellular skeletons via biologically controlled calcification, in which amorphous calcium carbonate (ACC), regarded as precursors of aragonite crystals, have been observed at nanoscale using electron microscopy. However, the exact mechanism by which ACC is generated, and how it contributes to skeletal growth in coral calcifying tissue, remains enigmatic. The septal skeleton of an individual polyp is composed of radially aligned plates extending upward from the aboral calcifying tissue. This structure includes microstructure known as the centers of calcification (CoC). However, despite its importance, direct in vivo observation of septal growth has not been reported. Observations under transmitted illumination using polarized light microscopy on calcifying tissue of young Acropora digitifera revealed small crystals, a few micrometers in size, that accompany subtle movements and that emerge exclusively on the inner wall of the pocket in extracellular calcifying fluid (ECF). Crystal growth initiated from small, scattered crystals on a glass plate resembles this phenomenon observed in coral skeletons. Time-lapse photographs of 12 individuals in early primary polyp settlement revealed this process in three individuals, documenting 13 of these crystal events. This phenomenon occurred solely at the bases of subsequently formed septa. These crystals differ notably from fusiform crystals and from dumbbell-like or rod-like crystals growing individually. Upright two-photon microscopy captured movement of sub-micron-sized fluorescent calcein-accumulating particles, emphasizing their presence on the surface of the growing fronts of septa. Methodological advances that facilitate comprehensive in vivo observation of sub-micron-sized structures, calcein-accumulating particles to the skeleton, are needed to develop a more detailed understanding of coral skeletal growth.

Surface enhanced raman spectroscopy based sensitive and onsite detection of microplastics in water utilizing silver nanoparticles and nanodendrites.

Plastics, of the order of microns in size, being not visible to the naked eye, are one of the significant contributors to pollution in the environment. Thus, the detection of micron-sized plastics (microplastics (MPs)) is crucial because of its hazardous toxic effects on our surroundings. In this work, we have proposed a quick and on-site detection of MPs, such as, polyvinyl chloride (PVC), polyvinyl alcohol (PVA) and polystyrene (PS) at ultra trace level using surface-enhanced Raman spectroscopy (SERS). To detect and analyse the spectra, two different nanostructures, such as, spherical shaped Ag nanoparticles (NPs), and shape anisotropic Ag nano-dendrites (NDs) were utilised to acquire the SERS spectra. A comprehensive analysis was further performed to check and investigate the amount of enhancements due to the mentioned nanostructures. We observed the Ag NDs exhibited amplified signal intensity compared to the Ag NPs due to the shape anisotropy leading to the surface charge confinement effect to create highly dense hotspots. However, the spherical shaped polystyrene beads of micron size exhibited better enhancement in Raman signal intensity when mixed with Ag NPs due to increased surface adsorption with the NPs. Therefore, the comparative study emphasizes the ability of using solution-based nanostructure as SERS for the onsite detection of microplastics having diverge size range at low concentration.

Particle–droplet coalescence and jumping on superhydrophobic surfaces—A direct numerical simulations study

We report here multiphase direct numerical simulations of a recently discovered passive mechanism of self-cleaning on superhydrophobic surfaces. The removal of contaminants is governed by coalescence of a single droplet with a particle of micrometer size, where the droplet initiates spontaneous spreading on the particle and drives particle–droplet jumping. We use an in-house volume of fluid–immersed boundary numerical framework, introduce and thoroughly analyze capillary forces at the particle–droplet contact line, and validate our simulations in relation to previous experimental results. We then perform a comprehensive investigation over a number of different parameters regarding the interaction physics of the droplet with the particle and the substrate. We systematically vary particle, droplet, and surface physical and wetting properties and unveil a range of scenarios related to different energy dissipation mechanisms as a function of the substrate contact angles and contact-angle hysteresis. Detailed parameter studies establish the connection between the droplet, substrate and particle properties, and the outcome and efficiency of the particle-launching process. We particularly highlight the effects of the particle–droplet size ratio and the wettability of the particle. We reveal and discuss the corresponding dissipation mechanisms and quantify the energy efficiencies of the jumping process in the treated parameter space.

Polyethylene Terephthalate Microplastics Generated from Disposable Water Bottles Induce Interferon Signaling Pathways in Mouse Lung Epithelial Cells.

Microplastics (MPs) are present in ambient air in a respirable size fraction; however, their potential impact on human health via inhalation routes is not well documented. In the present study, methods for a lab-scale generation of MPs from regularly used and littered plastic articles were optimized. The toxicity of 11 different types of MPs, both commercially purchased and in-lab prepared MPs, was investigated in lung epithelial cells using cell viability, immune and inflammatory response, and genotoxicity endpoints. The underlying mechanisms were identified by microarray analysis. Although laborious, the laboratory-scale methods generated a sufficient quantity of well characterized MPs for toxicity testing. Of the 11 MPs tested, the small sized polyethylene terephthalate (PETE) MPs prepared from disposable water bottles induced the maximum toxicity. Specifically, the smaller size PETE MPs induced a robust activation of the interferon signaling pathway, implying that PETE MPs are perceived by cells by similar mechanisms as those employed to recognize pathogens. The PETE MPs of heterogenous size and shapes induced cell injury, triggering cell death, inflammatory cascade, and DNA damage, hallmark in vitro events indicative of potential in vivo tissue injury. The study establishes toxicity of specific types of plastic materials in micron and nano size.

Evolution of Morphology, Particle Size and Oxidation Resistance of Recycled Ti-6Al-4V Powders Prepared by Planetary Ball Milling

AbstractPlanetary ball milling is a high-energy ball milling technique that is widely used for the synthesis of alloy and composite powders with micrometer or nanometer particle sizes. The effect of process control agent (PCA) content (wt%) and milling time on the morphology, particle size and distribution, crystallite structure, apparent density and oxidation resistance of recycled T-6Al-4V alloy powders from lathe chips is investigated in this study. To investigate the effect of the PCA on the properties of the Ti-6Al-4V alloy particles, methanol is used as the PCA in various amounts of 0.5, 1 and 2 wt%. The milling is carried out using 20:1 of ball-to-powder ratio (BPR) and 400 rpm of milling speed. A morphological change from scrap form to flake-like shape, from flake-like morphology to irregular and semispherical shape and finally from semispherical form to spherical morphology is observed with increase in milling time for all PCA ratios. The results showed that the average particle sizes (D50) are 20, 18.1 and 21.8 μm after milling of 360 min with 0.5 wt%, 1 wt% and 2 wt% PCA, respectively. Results show that the most suitable recycled Ti-6Al-4V powders for powder-based manufacturing techniques are produced between 180 and 360 min of milling with 2 wt% PCA.

Synthesis and alloying of zinc sulfide in a homogeneous system based on dodecane, its identification and optical properties

Zinc sulfide doped with Mn2+ ions was synthesized in a homogeneous dodecane medium by the method of emerging reagents. By methods of chemical and X-ray phase analysis, IR spectroscopy, electron microprobe microscopy, identification of products was carried out, photographs of the surface of powder particles (SEM) were recorded. Based on the totality of the results, a conclusion is made about the formation of nanoscale objects having a polytype structure with a predominance of distorted cubic crystals forming agglomerates up to 10 microns in size in ZnS powder and up to 100 microns in ZnS–Mn powder. The formation of nanoscale ZnS particles is confirmed by spectral data. The effect of manganese ions on the photoluminescence (FL) of the powder is manifested by a change in the type of the descending branch of the ZnS–Mn FL band, it is associated with recombination processes at the levels of defects formed by Mn2+ ions in the ZnS structure at their low concentration.

Chip-scale integrated holographic devices based on top-emitting vertical cavity surface emitting lasers.

Holography technology is considered the ultimate three-dimensional (3D) visualization technology in the future. However, conventional methods for achieving holography generally utilize discrete optical components and off-chip laser sources, resulting in a large size and high complexity, which are undesirable for practical applications. In this Letter, chip-scale integrated holographic devices are realized by integrating top-emitting vertical cavity surface emitting lasers (VCSELs) with micro holograms printed by 3D femtosecond laser nanoprinting technology. The VCSELs are designed to operate in a single fundamental mode with a Gaussian emission profile. Then the Gaussian beams are phase-modulated by the integrated micro holograms designed by the Gerchberg-Saxton (GS) algorithm and the target holographic images can be displayed behind the holograms. Such integrated holographic devices are of micron size and can be easily scaled into arrays with arbitrary channels on-demand, which are important for achieving miniaturized and portable holographic imaging systems.

Application of Anti-Solvent Crystallization for High-Purity Potash Production from K-Feldspar Leaching Solution

Potassium-containing feldspars provide a high potential for producing potash, a product with widespread use in agriculture. The present work assesses applying the anti-solvent crystallization method for the purification and recovery of high-purity muriate of potash (KCl) from feldspar leaching solutions. Initially, screening experiments were carried out on a synthetic leaching solution with the aim of analyzing the crystallization behavior of key components. Screening experiments were performed using five anti-solvents, namely methanol, ethanol, acetone, 2-propanol, and ethylene glycol. Acetone and 2-propanol were viable options for crystallization of potassium chloride. Then, the effects of anti-solvent ratio (O/A), time, and anti-solvent addition rate on potassium-chloride crystallization were further investigated using acetone and 2-propanol. A recovery of 83% of potassium was achieved when using acetone at the O/A of 5 with the addition rate of 10 mL/min, at room temperature with a hold time of 180 min. The optimum conditions for 2-propanol were determined to be similar, except for using a 5 mL/min addition rate for 79% recovery. The final muriate of potash products had a purity of over 99.9% using either of the anti-solvent. However, differences in morphology and crystal size of products were observed. Acetone-formed potash crystals were aggregates of cubic crystals with an average size of 3 microns, while 2-propanol-formed potash crystals were 20 microns in size as cubic particles with a hollow core. Despite having almost the same performance in potassium recovery, acetone was found to be a more feasible anti-solvent for potash recovery due to simpler downstream solvent recovery.

P-730 A feasibility study of the impact of the level of exposure to ambient air pollutants on outcomes of assisted reproductive technologies

Abstract Study question What is the impact of air pollution exposure on outcomes for couples having IVF treatment? Summary answer Environmental exposure to high levels of air pollutants may negatively influence IVF outcomes with potential implications for fertility treatment. What is known already Air pollutants are harmful substances in the atmosphere that have adverse effects on human health. Increased levels of air pollutants have been associated with respiratory disorders, cardiovascular disease, and increased morbidity in humans across all age groups. Existing evidence suggests that increased exposure to air pollutants may adversely affect fertility. The relationship between air pollutants and IVF outcomes remains poorly understood. Study design, size, duration This was an ethically approved prospective observational feasibility study conducted over a two-year period. Ten couples due to undergo an IVF cycle were recruited from a fertility centre in the UK. Environmental exposure to ambient air pollutant for particulate matter (PM) 2.5 and 10 micron size was measured using portable AirBeam monitors over the course of two weeks from commencement of the ovarian stimulation regime. Participants/materials, setting, methods Eligible participants were those aged 18-35 years old, undergoing fresh IVF, with a good ovarian reserve and ability to provide informed consent. Data of interest included: BMI, age, parity, ethnicity, smoking status. IVF data included: number of oocytes retrieved, embryo quality and cycle outcomes. AirBeam device data was extracted, analysed and correlated with IVF outcomes. Participants feedback was sought for qualitative input for future studies. Main results and the role of chance Total of 28,269 data points of ambient air pollutant data for PM 2.5 and 10 micron size were recorded amongst the ten participants. One participant was exposed to significantly high air pollutant levels during ovarian stimulation on certain days (PM2.5 - 81.06 µg/m³ and PM10 - 154.48 µg/m³) compared to standard annual air pollution level for the UK of 25 µg/m³ for PM2.5 and 40 µg/m³ for PM10. Two women did not have embryo transfer due to embryo arrest. Of those who had transfer, 50% (n = 4) had positive pregnancy tests however three experienced early pregnancy losses. At the time of writing there was one ongoing single viable pregnancy. On correlation of air quality data with clinical outcomes, the one participant who exhibited fluctuant very high exposure levels to the measured air pollutants, had unexpected low fertilization rate (20%) with IVF and no transfer due to embryo arrest. Of the nine participants returning the questionnaire feedback, all but one rated it acceptable to most acceptable to carry the device around. The main barrier was the size of device and battery life. All respondents were willing to recommend others to participate in a future similar study confirming feasibility to recruit. Limitations, reasons for caution As a feasibility study, with a limited sample size, our findings should be interpreted cautiously. The small cohort limits the generalisability of our results. Further research with larger sample sizes is required to validate our findings. Wider implications of the findings Understanding the impact of air pollutants on IVF outcomes is important for developing evidence-based guidance and interventions to optimise fertility treatment efficacy. Our study demonstrates the feasibility of personal air quality monitoring and emphasises the necessity for larger scale research and the practicality of pollutant exposure measurements in fertility treatments. Trial registration number REC reference: 21/NE/0233 IRAS project ID: 294240. Theramex BIRTH Grant

Micrometer-sized 3D porous structure decorated with uniform InSb alloy layer towards dendrite-free Li metal electrode

Li metal electrode is expected to be one promising anode to construct high energy density batteries because of its high theoretical specific capacity and the lowest electrode potential. However, uncontrollable dendrite growth and large volume changes cause batteries failure and safety risks. Here, an InSb alloy modified three-dimensional porous Cu (3D Cu@InSb) is constructed by electroless plating coupled with electroplating to stabilize the Li metal electrode. The suitable 3D porous structure with pore size of several micrometers can provide uniform current distribution, rapid ionic transferring channels, and effectively accommodate volumetric changes and release stress as well, avoiding the limited modifying effect using too large pores and poor ionic transport kinetics using too small pores. Moreover, the InSb alloy modified layer with high binding energy to Li+ reduces the nucleation overpotential and enhances the Li plating/stripping reversibility. Under the synergistic effects of InSb alloy modified layer and suitable 3D porous structure, Li metal is uniformly plated/stripped in pores with almost thorough flat surface even under a high area capacity of 4 mAh cm−2. The full battery assembled using LiFePO4 (LFP) cathode demonstrates a long life of 600 cycles at 2 C with a capacity retention of 86 %.

Optimization of embedded cooling for hotspots based on compound plate thermal spreading model

Heat fluxes of GaN-based high electron mobility transistors (HEMTs) can reach dozens of kilowatts per square centimeter, and the heat is generated only within a small area with feature size of micrometer to millimeter length scales, which poses a huge challenge for thermal management. In this study, an embedded microfluidic cooling solution is proposed to dissipate heat from the hotspots, and thermal test vehicles are fabricated using the Micro-Electro-Mechanical System (MEMS) process. Cooling performances of hotspots with sizes ranging from 40 × 40 μm2 to 500 × 500 μm2 and varying locations are demonstrated. Thermal resistances of the test samples are analysed and the heat transfer coefficient can achieve 1.5 × 105 W/(m2∙K) using embedded microchannel cooling. We propose a compound plate spreading thermal resistance model to demonstrate the effect of the dielectric layer and the size of the heat source on heat dissipating capability of the microfluidic cooling system. Based on the thermal spreading model, when the heat source is small, integrating high thermal conductivity materials near the heat source can reduce its total thermal resistance by two orders of magnitude. By balancing the heat spreading resistance with the convective resistance of microchannel cooling, we find that ∼1 mm can be considered as the critical length for distinguishing the primary thermal management approach for different sized hotspots. This paper provides useful design guidelines for embedded microchannel cooling of devices with localized heat generation patterns, such as HEMT devices.

Exploring uncommon Fe-oxides in non-metallic inclusions in ultra-high-strength steel

Investigating non-metallic inclusions within ultra-high-strength-steel via conventional methods is a known: however, the challenge is to obtain chemical information of such inclusions at the sub-micrometer level. In this context, probing Fe-based oxide in inclusions is a vital aspect for guiding steel’ performance. The vibrational properties of sub micrometer size Fe-based oxides were investigated by Raman mapping along with chemometric analysis with the aim of probing their chemical composition. Highly contrasted Raman spectra were recorded from several inclusions embedded at different spatial locations. The observed spectral features were identified as specific markers of hematite (α-Fe2O3) and magnetite (Fe3O4). Principal Component Analysis was used to confirm the presence of these markers and potentially revealing additional patterns. Their unambiguous assignment has been inferred by comparing our experimental findings with the literature data recorded either in single crystals of iron oxides or oxyhydroxides. Micro-Raman spectroscopy is proven to be a reliable, cost-effective, and non-invasive tool for the unambiguous identification of subsurface regions of steel.

Sarcoidosis Mortality in North Carolina: Role of Region, Race, and Other Sociodemographic Variables.

There is regional variability in sarcoidosis mortality across the United States. North Carolina ranks highly in sarcoidosis-related mortality, especially among African Americans (AA). We sought to determine any regional variability of sarcoidosis-related mortality and the relationship to sociodemographic determinants of health in North Carolina. Counties in North Carolina were categorized into three distinct geographic regions: Western, Piedmont, and Eastern. Sarcoidosis deaths were stratified by region, race, and gender. We conducted a mapping and cluster analysis utilizing ArcGIS; Global and Local Moran's I was used to determine the prevalence, spatial autocorrelation, and clustering of mortality vis-a-vis various sociodemographic variables, occupational/environmental exposures, and levels of atmospheric particulate matter less than 2.5 microns in size (PM2.5). Multivariate linear regression with exposure limited to the county level was used to determine the relationship between sarcoidosis mortality and the variables of interest. Eastern North Carolina (ENC) had the highest age-adjusted sarcoidosis mortality rate (1.16/100,000 versus 0.49/100,000 in Piedmont and 0.32/100,000 in the Western region) with statistically significant high-high mortality clusters (P < .001 for Global Moran's I). Several sociodemographic and occupational factors (proportion of AA, obese adults, and individuals working in nature) were more prevalent in ENC. Region and proportion of AA were the significant mortality predictors in our multivariate analysis. This was a cross-sectional study with exposure limited to the county level. Associations do not imply causality and risks cannot be extrapolated to the individual level. There is regional variability of sarcoidosis mortality in North Carolina. Eastern North Carolina had the highest mortality with high-high mortality clusters.

Effect of Y2Ti2O7 on microstructure and tensile properties of ODS-CLAM steel

Nano-Y2Ti2O7 is one of the phases used for improving the strength of oxide dispersion strengthened (ODS) steels, which is usually precipitated with Ti and Y2O3 added. The effect of synthesized Y2Ti2O7 on China low activation martensitic (CLAM) steel was studied. Two kinds of ODS-CLAM samples with nano-Y2Ti2O7 and amorphous Y2Ti2O7 additions were prepared using mechanical alloying (MA) and spark plasma sintering (SPS). The results indicates that amorphous Y2Ti2O7 powders had both amorphous and crystal oxides after milling with CLAM powders. Y2Ti2O7 powders were refined to below 10 nm in size with almost no structural change, and randomly distributed in the matrix. The initial size of added Y2Ti2O7 had a smaller impact on the size of precipitates, and the initial structure or the transform of the oxides during milling process were more important. The added Y2Ti2O7 particles were refined from ∼32 nm to 9.2 nm in size, while the size of amorphous Y2Ti2O7 particles was reduced from micron size to 6.9 nm in the sintered sample. The structure of Y2Ti2O7 in ODS powders affected the microstructure and strength of the sample after sintering. The sample with Y2Ti2O7 had higher strength and lower plasticity at both room temperature and 650 °C because of the higher dislocation density, while the sample with amorphous Y2Ti2O7 had higher plasticity with almost the same yield strength due to its higher dispersion strengthening. This study reveals the changes in Y2Ti2O7 structure during preparation process and suggests that the expected properties of ODS steels can be obtained by controlling the oxide structure.

Microtextural evidence for the recrystallization of opal-A to quartz in epithermal veins: A case study from the McLaughlin deposit, California

High-grade ores in low-sulfidation epithermal deposits commonly consist of banded veins containing quartz as the most abundant gangue mineral. Previous studies suggested that at least some of the quartz has formed as a product of recrystallization from a noncrystalline silica precursor. Detailed petrographic studies confirm that high-grade veins from the <2.2 Ma McLaughlin deposit in California were originally entirely composed of opal-AG. The noncrystalline silica is isotropic in crossed-polarized light and consists of compacted microspheres that are up to several micrometers in size. In many bands of the high-grade veins, the thermodynamically unstable opal-AG has matured to quartz. The recrystallization of the noncrystalline silica resulted in the development of quartz and ore textures that mask the original conditions of vein formation. Incipient recrystallization of the opal-AG caused the formation of lepispheres consisting of opal-CT as well as the development of concentrically banded silica spheres. Continued maturation led to the growth of elongated quartz crystals or complexly shaped quartz aggregates in the cores of the concentrically banded silica spheres. Amalgamation of quartz crystals caused the development of mosaic quartz or flamboyant quartz. Ripening produced large prismatic quartz crystals, which are characterized by zones of feathery appearance. Fluid inclusions within the quartz formed through recrystallization are typically highly irregular in shape and show inconsistent liquid-to-vapor volumetric proportions, but assemblages with consistent ratios are also present. Bands rich in fluid inclusions occurring along former recrystallization fronts in prismatic quartz crystals resemble growth zones in zonal quartz. Recrystallization of the silica matrix resulted in grain coarsening of the ore minerals and encapsulation of ore minerals by quartz. In areas where recrystallization of the noncrystalline silica proceeded to completeness, the quartz textures could be easily misinterpreted to indicate that quartz growth occurred in open space with the ore minerals infilling vug spaces. Correct recognition of recrystallization textures has significant implications for paragenetic investigations on vein material from epithermal deposits as well as the design of fluid inclusion studies.