Presence Of Carbon Particles Research Articles

All-in-one fabrication of NiO nanorods/carbon-containing porous catalytic polymer membranes for persulfate-facilitated oxidation-adsorption of diclofenac in flow–through

We introduce a novel all-in-one fabrication method for porous catalytic polyethersulfone (PES) membranes containing NiO nanorods and carbon nanoparticles. This method is based on the sonochemical in situ solidification of a metal salt with NaBH4 in presence of carbon particles in a PES-containing casting-reaction solution, directly followed by membrane preparation via film casting cum phase separation. In the catalytic flow-through degradation of 20 mg/L aqueous diclofenac with persulfate as oxidant, an as-prepared NiO-carbon-PES membrane achieved a 99 % aromatic content removal degree at a residence time of only 1.6 s. In comparison, NiO and CuO membranes without carbon particles exhibited < 40 % aromatic removal degrees. The high performance was attributed to a degradation-induced adsorption, with a diclofenac removal capacity of 950 mg/g of incorporated carbon particles. We demonstrated that diclofenac is catalytically mineralized in the membrane at incorporated NiO nanorods, followed by adsorption of remaining degradation products at nearby carbon particles. Our data further suggests that reducing NiO to Ni(0) via a membrane pretreatment shifts the catalytic persulfate activation from a radicaltoa non-radical pathway, and that HCO3– can function as sacrificial electron donor for Ni(0). This completely mitigated nickel leaching from the membrane in contact to persulfate. Moreover, even in the presence of NaHCO3 and NaCl, a Ni(0)–carbon–PES membrane consistently eliminated ∼ 90 % of the total organic carbon (TOC) from a 2 mg/L diclofenac feed containing persulfate in single-pass flow-through mode (continuously for 5 h, respectively for 500 L/m2 permeate volume), with no detectable release of degradation products or any nickel leaching.

Overview of tritium retention in divertor tiles and dust particles from the JET tokamak with the ITER-like wall

Divertor tiles after Joint European Torus-ITER like wall (JET-ILW) campaigns and dust collected after JET-C and JET-ILW operation were examined by a set of complementary techniques (full combustion and radiography) to determine the total, specific and areal tritium activities, poloidal tritium distribution in the divertor and the presence of that isotope in individual dust particles. In the divertor tiles, the majority of tritium is detected in the surface region and, the areal activities in the ILW divertor are in the 0.5–12 kBq cm−2 range. The activity in the ILW dust is associated mainly with the presence of carbon particles being a legacy from the JET-C operation. The total tritium activities show significant differences between the JET operation with ILW and the earlier phase with the carbon wall (JET-C) indicating that tritium retention has been significantly decreased in the operation with ILW.

The presence of anthracosis is associated with the environmental air quality of zoo, wildlife, and companion animals in Jeollabuk-do Province, South Korea.

To determine pulmonary anthracosis in zoo, wildlife, and companion animals of Jeollabuk-do Province, South Korea. A total of 350 animals of 61 different species, belonging to 3 classes (mammals: n = 38; avian: 21; and reptiles: 2) from different habitats in Jeollabuk-do Province, were examined. Gross lung examination and tissue sampling were done at postmortem, and histopathological analysis was microscopically done on hematoxylin and eosin-stained slides. Macroscopic analysis of anthracotic lung tissue revealed minute (pinpoint size) spots and black pigmentation in a scattered and/or coalescing fashion. The presence of carbon particles was noted in 154 (44%, 154/350) cases. Based on habitation, zoo animals had the highest frequency of anthracosis in the lung (55.2%, 69/125), followed by companion animals (45.2%, 56/124) and wildlife animals (28.7%, 29/101). There was an association between habitation and the presence of anthracosis (P < .05). This study revealed evidence that the presence of anthracosis is associated with the environmental air quality of zoo, wildlife, and companion animals in Jeollabuk-do Province, South Korea. Air pollution may affect the respiratory health of the endangered species at the Jeonju Zoo as well as the human population. Continuous monitoring of particulate matter and establishing policies that control industrialization around the province would enable quick action to curb any potential respiratory health risks to animals kept in the urban cities of the province.

Structure and biological activity of particles produced from highly activated carbon adsorbent

Over the recent years, carbon particles have gained relevance in the field of biomedical application to diminish the level of endo-/exogenous intoxication and oxidative stress products, which occur at different pathological states. However, it is very important that such carbon particles, specially developed for parenteral administration or per oral usage, possess a high adsorption potential and can remove hazard toxic substances of the hydrophilic, hydrophobic and amphiphilic nature usually accumulated in the blood due to the disease, and be absolutely safe for normal living cells and tissues of organism. In this work, the stable monodisperse suspension containing very small-sized (Dhydro = 1125.3 ± 243.8 nm) and highly pure carbon particles with an excellent accepting ability were obtained. UV-spectra, fluorescence quenching constant and binding association constant were provided by the information about conformational alterations in an albumin molecule in presence of carbon particles, about the dynamic type of quenching process and low binding affinity between carbon and protein. The later was confirmed by DSC method. In vitro cell culture experiments showed that carbon particles did not possess any cytotoxic effect towards all testing the normal cell lines of different histogenesis, did not show genotoxic effects and were absolutely safe for experimental animals during and after their parenteral administration. These observations may provide more information about how to develop a safe preparation of carbon particles for different biomedical applications, in particular, as a mean for intracorporeal therapy of various heavy diseases accompanied by the increased endogenous intoxication and the level of oxidative stress.

Compatibility Study of Silicone Rubber and Mineral Oil

In this study, three types of silicone rubbers, namely, insulative silicone rubber, conductive silicone rubber and silicone rubber with conductive as well as insulative layers are investigated for their compatibility with mineral oil. Mineral oil with different silicone rubber samples is thermally aged at 130 °C for 360 h, 720 h and 1080 h and at 23 °C, 98 °C and 130 °C for 360 h. At the end of each ageing interval, mineral oil and oil-impregnated silicone rubbers are investigated for their dielectric properties. Aged mineral oil samples are investigated for their moisture content, breakdown voltage, colour number, dissolved gases and total acid number, whereas solid insulation samples are investigated for their moisture content. Additionally, pressboard samples in mineral oil and mineral oil without any solid insulation materials are also aged under the same conditions and are investigated for their dielectric properties. From the obtained results, it can be assessed that the presence of carbon particles in conductive silicone rubber negatively impacts the dielectric properties of mineral oil. Among the investigated silicone rubbers, the insulative silicone rubber exhibits good compatibility with mineral oil and a strong potential for being used in mineral oil.

Electrocatalyst of two-dimensional CoP nanosheets embedded by carbon nanoparticles for hydrogen generation and urea oxidation in alkaline solution

Hydrogen (H2) producing from the electrolysis of water at cathode is limited by the sluggish kinetics of oxygen evolution reaction (OER) at anode. It is essential to search a facile anodic reaction to replace OER in the hydrogen generation process. Urea oxidation reaction (UOR) is an alternative strategy to instead of OER in the water splitting reaction. Based on this, we successfully prepare two-dimensional (2D) CoP nanosheets embedded by carbon nanoparticles (CoP/C) composites as bifunctional catalysts to achieve hydrogen evolution reaction (HER) at cathode and UOR at anode simultaneously. Benefiting from the presence of carbon particles and 2D sheet structure of CoP in the composites, the contact area of electrolyte/electrode is enlarged, the exposed active sites are increased, and charge transfer rate is improved. As the anode and cathode catalysts in a two-electrode system with continuous electrolyte supplementation by a flow reactor, the CoP/C-3 composite only need 1.40 V to reach the current density of 10 mA cm−2 in the 1 M KOH electrolyte with 0.1 M urea. This study on hydrogen generation and urea oxidation at a low potential provides a promising method to prepare bifunctional catalysts for practical applications.

Waste Toner-Derived Carbon/Fe3O4 Nanocomposite for High-Performance Supercapacitor.

Electronic waste management is one of the key challenges for the green revolution without affecting the environment. The wide use of printer devices has brought a horde of discarded waste toner, which release ∼6000 tons of processed carbon powder into the atmosphere every year that would essentially pollute the atmosphere. Here, we propose a one-step thermal conversion of waste toner powder into carbon/Fe3O4 nanocomposites for energy storage applications. Recovered toner carbon (RTC) and toner carbon calcined at 300 °C (RTC-300) were characterized using various analytical tools. From the FE-SEM analysis, the presence of carbon particles with uniformly decorated Fe3O4 nanoparticles was confirmed. RTC-300 carbon was used as an electrode material for supercapacitors, and it exhibited a high specific capacitance of 536 F/g at a current density of 3 A/g, which is almost six times higher than that of the commercial mesoporous graphitized carbon black. RTC-300 showed excellent electrochemical stability of 97% over 5000 cycles at a high current density of 20 A/g. The fabricated symmetric cell using RTC-300 electrode materials in an aqueous electrolyte with a cell voltage of 1.8 V delivered a high energy and high-power density of 42 W h/kg and 14.5 kW/kg, respectively. The fabricated device is stable up to 20,000 cycles at a high current density of 20 A/g with a loss of 23% capacitance.

Photocatalytic Activity of TiO2-C Nanocomposites in the Oxidation of Safranin T Under UV and Visible Light

A comparative analysis was carried out on the photocatalytic properties of nanocomposites derived from anatase and carbon obtained by two different reactions in the decomposition of Safranin T. Compared with samples obtained by mechanochemical modification of titanium dioxide by carbon, the nanocomposites obtained by the sol–gel method in the presence of carbon particles are more effective photocatalysts for this reaction due to narrowing of the band gap and the appearance of additional (defective) absorption in the visible spectral range. The effects of the pH of the solution, the extent of substrate adsorption, and the concentrations of the photocatalyst and substrate on the rate of decomposition of this dye were studied.

Analytical and Thermal Evaluation of Carbon Particles Recovered at the Cyclone of a Downdraft Biomass Gasification System

Gasification of biomass gives off syngas that is contaminated mostly by carbon particulates and tars. The degree of contamination is attributed to factors such as gasification process, type of gasifier and type of biomass material. Downdraft gasifier minimizes the production of tar to a tolerable limit for engine applications; however, carbon particles still pose a challenge particularly with the integration of a heat exchanger for the purpose of heat recovery from the product gas. The presence of carbon particles in the syngas does influence the heat recovery process and materials used in the recovery. Hence, there is need for the characterization of these carbon particles to ascertain their chemical compositions, thermal properties and morphological features. This study was aimed at evaluating the characteristic features of carbon particles recovered from the syngas stream during gas cleaning at the cyclone. The elemental analysis of the carbon particle samples was performed using energy dispersive X-ray spectroscopy. An electron beam from scanning electron microscopy was passed through the sample surface at a magnification of 1000× and an accelerating voltage of 15 kV to determine the morphological features of the carbon particles. Their thermal properties were investigated using a thermogravimetric analyzer at a heating rate of 10°C/min. A weight loss of approximately 5.4 wt % was recorded at the maximum temperature of 900 °C. Silicon, oxygen and carbon were found to be the dominating elements in the carbon particulate.

Physical and mathematical modeling of ignition of methane-air mixture in the presence of coal microparticles

The results of numerical investigation of the ignition of a stoichiometric methane-air mixture in the presence of carbon particles with diameters of 20-52 μm in the temperature range 950-1150 K and pressures of 1.5-2.0 MPa are presented. The calculated data of the ignition delay times of coal particles in the coal particles/air mixture and of the ignition delay times of methane and coal particles in the methane/coal particles /air mixture are compared with the experimental ones. A satisfactory agreement of the data on the coal particles ignition delay times and methane ignition delay times in all the mixtures considered is shown.

Copper-Modified Covalent Triazine Frameworks As Efficient Electrocatalysts for Oxygen Reduction Reactions

1. Introduction Electrochemical oxygen reduction reaction (ORR) is important as a cathode reaction of various types of fuel cells. At present, platinum (Pt) is used as a practical ORR electrocatalyst. However, as Pt is scarce and expensive, development of electrocatalysts composed only of abundant elements is strongly required. One of the effective approaches to synthesize non-noble metal catalysts is to learn from enzymes. Cu ions in Cu-containing enzymes such as laccase serve as the active centers for ORR. Especially, multi-copper oxidases (MCOs) are representative enzymes that catalyze ORR with almost no activation energy [1]. For MCOs, the modulation of the electronic state of the copper (Cu) active sites through the coordination with amino acid residues is known to be essential for the superior ORR catalytic activity. Therefore, many studies have been conducted on developing Cu-complex based electrocatalysts that mimic the molecular structure of MCOs [2]. However, their catalytic activity and stability developed to date are not satisfactory. Covalent triazine framework (CTF) is a promising material as a novel platform for non-noble metal based electrocatalysts since the CTF is robust and possesses abundant nitrogen (N) atoms with electron lone pair for metal coordination. Recently, our laboratory has successfully synthesized Pt-modified CTF hybridized with conductive carbon nanoparticles (Pt-CTF) as methanol-tolerant ORR electrocatalyst [3]. However, modification of CTFs by non-noble metals has not been achieved yet. In this work, it was attempted to synthesize Cu modified CTF hybridized with carbon particles as an ORR electrocatalyst. 2.Experimental The CTF hybridized with conductive carbon particles was synthesized by in situ polymerization of 2,6-dicyanopyridine in the presence of carbon particles. Briefly, the mixture of ZnCl2 molten salt, 2,6-dicyanopyridine and carbon particles were placed in a vacuum-sealed pyrex glass tube and heated at 400 °C for 40 h. The modification of Cu atoms was performed by an impregnation method in CuCl2 solutions (Cu-CTF). Electrocatalytic activity was evaluated by conducting cyclic voltammetry (CV) in 0.1 M phosphate buffer solutions (PBS) at room temperature using a rotating ring disk electrode. The molecular structure of the catalyst was characterized by an extended X-ray absorption fine structure (EXAFS) and a transmission electron microscope (TEM). 3.Result and discussion The EXAFS and TEM results (not shown here) demonstrated that Cu atoms were coordinated to N atoms located in pores of the CTFs (Figure 1(a)). Figure 1(b) shows CVs for Cu-CTF and CTF in deaerated PBS (pH 7). The single pair of redox peaks corresponding to the Cu(I)/Cu(II) couple was observed for Cu-CTF. In the presence of dissolved oxygen, ORR current started to flow at the potential where Cu(II) is reduced to Cu(I) (Figure 1(c)), indicating that Cu(I) is the key species for the catalytic activity. Notably, both the redox potential of Cu(I)/Cu(II) (0.57 V) and the ORR onset potential (0.81 V) for the Cu-CTF were higher than those for the other Cu-complexes reported so far [4]. To clarify the molecular mechanism of ORR for Cu-CTF, we calculated the adsorption energy of O atom (ΔEo) as the indicator of interaction with ORR intermediates by the density functional theory (DFT) method. The result showed that Cu-CTF has similar ΔEo to platinum cluster which is the best artificial ORR catalyst. It strongly suggests that the regulation of the coordination structure by CTF modulates the interaction between reactant and metal centers [4][5]. Next, the stability of Cu-CTF during ORR was evaluated by conducting continuous CV cycles. For comparison, the Cu-(3,5-diamino-1,2,4-triazole) complex that shows similar ORR onset potential to the Cu-CTF [2] was also tested as a reference sample. For the conventional Cu-complex, the current density at 0.6 V decreased by 84 % after 500 cycles. However, the current decreased only by 19 % for the Cu-CTF, clearly indicating the superior stability of the Cu-CTF. 4.Conclusion Thus, it was demonstrated that newly-synthesized Cu-CTF could serve as an efficient ORR electrocatalyst in neutral solutions. Notably, the Cu-CTF exhibited the best activity and stability among the Cu-complex based electrocatalysts reported so far. 5.

The Role of Individual and Combined Ions in Waterflooding Carbonate Reservoirs: Electrokinetic Study

Summary Adjusting the injection-water chemistry during waterflooding for both carbonate and clastic reservoirs shows a significant effect on oil recovery. In carbonates, however, the role of ions plays a key role in rock/fluid interaction, and eventually affects the rock wettability. Research studies for carbonate-rock systems have been continuously conducted to identify the reaction mechanisms that modify the rock wettability toward water-wet. Most of these studies are conducted at macroscopic scales by use of conventional methods such as coreflooding, contact-angle, and imbibition/drainage procedures. Potential mechanisms for rock-wettability alteration were proposed including sulfate (SO4) adsorption, mineral dissolution, ionic exchange, and improving fluid diffusion among different pore systems. Further research studies have noted that certain ions have a significant role in the proposed mechanisms. Moreover, the main interactions are expected to take place at rock/fluid and/or fluid/fluid interfaces. In this paper, more attention is given to indirect measurements of carbonate- and crude-oil-surface charges at different ionic composition and temperatures by use of unique preparation procedures and advanced techniques. Individual and combined dissolved cations and anions were studied at fixed salinity. An ultrasonic homogenizer bath was used to create oil-in-water emulsions and carbonate suspensions in different brines at high temperatures. To determine the interactions between immiscible fluids with carbonates, oil-in-water emulsions were prepared in the presence of carbonate particles. To mimic the reservoir condition, the aging effect on the chemical interactions of emulsions and carbonate suspensions was investigated. The findings in this study bring new insights on the effect of different ions on crude-oil components and carbonate-rock interactions at fixed salinity. Individual ions including cations and anions altered carbonate-surface charges and interacted differently at interfaces, although all water recipes have the same salinity. Individual sodium (Na) salts, in particular, significantly influenced the surface potential at the calcite/water interfaces. The hard ions as calcium (Ca) and magnesium (Mg), on the other hand, shifted the ζ-potential of calcites toward the positive side. These divalent ions can either adsorb directly on the negative sites or penetrate the adsorbed hydrolysis layer of water on the calcite surface. The electrical properties of calcites are also affected by the ionic content and the cation/anion ratio, as in SmartWater (a mixture of dissolved salt species such as cations and anions) (Yousef et al. 2012) and key ion solutions. In addition, the dissolved divalent cations can play a role in the interactions at the Stern-layer boundary and eventually they can affect the surface charges at oil/water interfaces. In view of the ζ-potential results, only SmartWater, sodium chloride (NaCl), and sodium sulfate (Na2SO4) solutions were able to create electrical repulsions between oil/water and calcite/water interfaces. As a result, wettability of the rock will be altered to water-wet, thus enhancing oil recovery.

X-ray-induced reduction of Au ions in an aqueous solution in the presence of support materials and in situ time-resolved XANES measurements.

Synchrotron X-ray-induced reduction of Au ions in an aqueous solution with or without support materials is reported. To clarify the process of radiation-induced reduction of metal ions in aqueous solutions in the presence of carbon particles as support materials, in situ time-resolved XANES measurements of Au ions were performed under synchrotron X-ray irradiation. XANES spectra were obtained only when hydrophobic carbon particles were added to the precursor solution containing Au ions. Changes in the shape of the XANES spectra indicated a rapid reduction from ionic to metallic Au in the precursor solution owing to synchrotron X-ray irradiation. In addition, the effects of the wettability of the carbon particles on the deposited Au metallic spots were examined. The deposited Au metallic spots were different depending on the relationship of surface charges between metal precursors and support materials. Moreover, a Au film was obtained as a by-product only when hydrophilic carbon particles were added to the precursor solution containing the Au ions.

Effect of carbon particles on heavy metal emissions under ash-melting conditions

In Japan, incineration ash is subjected to a melting process to reduce waste volume and to stabilize hazardous heavy metals. In previous articles, we reported that large quantities of volatile metals are emitted under ash-melting conditions at temperatures higher than 1200°C and that such emissions are considerably increased under reducing conditions. However, the emission behavior in the presence of large amounts of char particles was unclear, and we suspected that emissions under these conditions might differ from emissions under the previous conditions. Therefore, we investigated heavy metal emissions and the melting characteristics of ash in the presence of carbon particles. In this experiment, a small crucible with ash and carbon was rapidly heated using a high-frequency induction-heating furnace to simulate the melting ash gasification with carbon. As a result, it was found that additive carbon can promote emissions of heavy metals such as zinc and lead and control the melt of the ash.

Bleomycin induces pleural and subpleural fibrosis in the presence of carbon particles

The pathological changes in idiopathic pulmonary fibrosis (IPF) typically start in subpleural lung regions, a feature that is currently not explained. IPF, as well as bleomycin-induced lung fibrosis, are more common in smokers. We hypothesised that carbon particles, which are major components of cigarette smoke that are transported to alveoli and pleural surface, might be involved in the development of subpleural fibrosis through interaction with pleural mesothelial cells. Carbon particles were administered to mice in combination with bleomycin through intratracheal and/or intrapleural injection and fibrosis was assessed using histomorphometry. Carbon administered to the chest cavity caused severe pleural fibrosis in the presence of bleomycin, whereas bleomycin alone had no fibrogenic effect. The pleural response was associated with progressive fibrosis in subpleural regions, similar to IPF in humans. Matrix accumulation within this area evolved through mesothelial-fibroblastoid transformation, where mesothelial cells acquire myofibroblast characteristics. In contrast, carbon did not exaggerate bleomycin-induced pulmonary fibrosis after combined intratracheal administration. This represents a novel approach to induce a robust experimental model of pleural fibrosis. It also suggests that carbon particles might be involved as a cofactor in the initiation and/or progression of (subpleural) pulmonary and pleural fibrosis. Mesothelial cells appear to be critical contributors to this fibrotic process.

Nanoparticle‐induced platelet aggregation and vascular thrombosis

Ever increasing use of engineered carbon nanoparticles in nanopharmacology for selective imaging, sensor or drug delivery systems has increased the potential for blood platelet-nanoparticle interactions. We studied the effects of engineered and combustion-derived carbon nanoparticles on human platelet aggregation in vitro and rat vascular thrombosis in vivo. Multiplewall (MWNT), singlewall (SWNT) nanotubes, C60 fullerenes (C60CS) and mixed carbon nanoparticles (MCN) (0.2-300 microg ml(-1)) were investigated. Nanoparticles were compared with standard urban particulate matter (SRM1648, average size 1.4 microm). Platelet function was studied using lumi aggregometry, phase-contrast, immunofluorescence and transmission electron microscopy, flow cytometry, zymography and pharmacological inhibitors of platelet aggregation. Vascular thrombosis was induced by ferric chloride and the rate of thrombosis was measured, in the presence of carbon particles, with an ultrasonic flow probe. Carbon particles, except C60CS, stimulated platelet aggregation (MCN>or=SWNT>MWNT>SRM1648) and accelerated the rate of vascular thrombosis in rat carotid arteries with a similar rank order of efficacy. All particles resulted in upregulation of GPIIb/IIIa in platelets. In contrast, particles differentially affected the release of platelet granules, as well as the activity of thromboxane-, ADP, matrix metalloproteinase- and protein kinase C-dependent pathways of aggregation. Furthermore, particle-induced aggregation was inhibited by prostacyclin and S-nitroso-glutathione, but not by aspirin. Thus, some carbon nanoparticles and microparticles have the ability to activate platelets and enhance vascular thrombosis. These observations are of importance for the pharmacological use of carbon nanoparticles and pathology of urban particulate matter.

8-Hydroxyguanosine formed in human lung tissues and the association with diesel exhaust particles

Diesel exhaust particles consist of various organic chemicals, heavy metals, and carbon particles. Knowledge of the fate of organic chemicals and carbon particles in the lungs is important to determine the mechanisms responsible for lung tumors. In the present study, diesel particle extracts were found to show mutagenicity for YG3003, a sensitive strain to some oxidative mutagens, as well as other mutant strains, and those of lung tissues obtained from lung cancer patients exhibited potent mutagenicity. Formation of 8-hydroxyguanosine (8-OHdG) as a biomarker of oxidative damage was analyzed with in vitro and in vivo assay systems. The 8-OHdG was detected in all 22 cases of lung tissues with carcinomas tested and their levels increased with the increasing age of the patients, suggesting a correlation between age and the presence of carbon particles in lung tissues. Therefore, the formation of 8-OHdG due to diesel exhaust particles was investigated via intratracheal injections into mice. 8-OHdG formation was elevated when carboneceous particles, after removal of organic chemicals with various solvents, were administered to mice, but it was not elevated when polyaromatic compounds such as benzo[a]pyrene, 1,8-dinitropyrene, and 1-nitropyrene were used in the same procedure in mice. The carboneceous particles were formed from a giant particle that was aggregated by micro-particles with diameters of 1.47 ± 1.34 to 1.05 ± 0.83 μm. These results suggest that carboneceous particles, but not mutagens and carcinogens, promote the formation of 8-OHdG, and that as a mechanism, alveolar macrophages may be involved in oxidative damage. The oxidative damage may be due to the fact that the mutation is involved with the generation of a hydroxyl radical during phagocytosis, and the hydroxyl radical leads to hydroxylation at the C-8 position of the deoxyguanosine residue in the DNA.

Improved operability in Hg1−xCdxTe detector arrays

As liquid phase epitaxial (LPE) growth and array fabrication processes have matured to give excellent wafer average performance, the yield limiter for infrared focal plane arrays (IRFPAs), especially large ones, have become outages. In this work, significant progress has been made in identifying the source and eliminating outages from LPE grown Hg1−xCdxTe P-on-n structures. Historically, studies of the sources of outages have employed defect etches to look for dislocations and other crystalline defects, and secondary ion mass spectroscopy (SIMS), imaging SIMS, and sputter initiated resonance ion spectrometry (SIRIS) to look for impurities at critical interfaces. Using these techniques, trends were established, but direct correlation with outages have been observed. In LPE grown materials, where the dislocation densities are always below 5×105 cm−2, and often below 1×105 cm−2 on CdZnTe substrates, dislocations only account for a few outages. In order to understand the source(s) of outages, a failure analysis was performed on several long wavelength IRFPAs. Using a dilute etchant, the metals and then cap layers of some 64×64 pixel IRFPAs which had excellent average performance, but suffered from a high density of pixels with excessive leakage current, were removed. Using a scanning electron microscope with energy dispersive spectroscopy capability, the presence of carbon particles was correlated with excessive leakage current on a 1:1 pixel basis. A series of experiments was then conducted which isolated the source of the particles to the cap layer growth process, which was consequently changed to eliminate them. The process improvements have reduced the particle density to below the measurement limit of the optical measurement technique implemented to monitor the density of particles on witness wafers. These improvements are resulting in IRFPAs with significantly improved operability.

A Case of Dextrocardia with Normal Situs

We report here a case of dextrocardia with normal situs in an 81-year-old man who died from non-pulmonary causes. Removal of the chest wall revealed a large, but otherwise anatomically normal, left lung occupying the entire left hemithorax and extending across the midline to overlap the left border of the heart which was positioned in the right hemithorax. The gross anatomy of the heart was normal save its position and the presence of only 2 pulmonary veins. Dissection of the heart showed all chambers in their classically described position, and there were no valvular defects. The anatomy of the great vessels was also normal. The right lung was hypoplastic and lay posterior to the heart. This lung lacked any lobular structure, but the presence of carbon particles throughout it suggested that it was capable of normal inflation.

Ultrastructural study of phagocytic activities of young astrocytes in injured neonatal rat brain following intracerebral injection of colloidal carbon.

The cellular reaction to injury in the mature central nervous system (CNS) has been extensively studied in both man and animals, while a detailed study of the reaction of the immature CNS to injury is lacking in the literature. This study was undertaken to elucidate the response of young astrocytes following injection injury to developing brain. Colloidal carbon was applied because it is a suitable marker for phagocytosis, it is nontoxic, and it is readily identifiable by light and electron microscopy. The cerebral cortex of the neonatal rat was injected with 0.1 microliter of colloidal carbon solution. The animals were allowed to survive from 1 hour to 30 days postoperation. The brains were fixed by vascular perfusion and processed for light and electron microscopy. Carbon particles were ingested in membrane-bound vacuoles and sequestered in lysosomes of young astrocytes. Astrocytes, loaded with carbon particles, were identified after 4 days, and were seen in abundance between 10 to 21 days postoperation. Carbon-laden astrocytes were seen in the immediate vicinity of the site of the injection; in the surrounding, apparently normal, neuropil; and in the perivascular regions. This study demonstrates the ability of young astrocytes to engulf foreign particles injected into the developing brain. The presence of carbon particles in astrocytes located further away from the site of injection is discussed.