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The coronavirus disease 2019 (COVID-19) pandemic has resulted in reduced performance of elective surgeries and procedures at medical centers across the United States. Awareness of the prevalence of asymptomatic disease is critical for guiding safe approaches to operative/procedural services. As COVID-19 polymerase chain reaction (PCR) testing has been limited largely to symptomatic patients, health care workers, or to those in communal care centers, data regarding asymptomatic viral disease carriage are limited. In this retrospective observational case series evaluating UCLA Health patients enrolled in pre-operative/pre-procedure protocol COVID-19 reverse transcriptase (RT)–PCR testing between April 7, 2020 and May 21, 2020, we determine the prevalence of COVID-19 infection in asymptomatic patients scheduled for surgeries and procedures. Primary outcomes include the prevalence of COVID-19 infection in this asymptomatic population. Secondary data analysis includes overall population testing results and population demographics. Eighteen of 4,751 (0.38%) patients scheduled for upcoming surgeries and high-risk procedures had abnormal (positive/inconclusive) COVID-19 RT-PCR testing results. Six of 18 patients were confirmed asymptomatic and had positive test results. Four of 18 were confirmed asymptomtic and had inconclusive results. Eight of 18 had positive results in the setting of recent symptoms or known COVID-19 infection. The prevalence of asymptomatic COVID-19 infection was 0.13%. More than 90% of patients had residential addresses within a 67-mile geographic radius of our medical center, the median age was 58, and there was equal male/female distribution. These data demonstrating low levels (0.13% prevalence) of COVID-19 infection in an asymptomatic population of patients undergoing scheduled surgeries/procedures in a large urban area have helped to inform perioperative protocols during the COVID-19 pandemic. Testing protocols like ours may prove valuable for other health systems in their approaches to safe procedural practices during COVID-19. [ABSTRACT FROM AUTHOR]

Diagnostic radiology (DxR), having had successful serial co-evolutions with imaging equipment and PACS, is faced with another. With a backdrop termed "globotics transition," it should create an IT and informatics infrastructure capable of integrating artificial intelligence (AI) into current critical communication functions of PACS and incorporating functions currently residing in balkanized products. DxR will face the challenge of adopting sustaining and disruptive AI innovations simultaneously. In this co-evolution, a major selection force for AI will be increasing the flow of information and patients; "increasing" means faster flow over larger areas defined by geography and content. Larger content includes a broader spectrum of imaging and nonimaging information streams that facilitate medical decision making. Evolution to faster flow will gravitate toward a hierarchical IT architecture consisting of many small channels feeding into fewer larger channels, something potentially difficult for current PACS. Smartphone-like architecture optimized for communication and integration could provide a large-channel backbone and many smaller feeding channels for basic functions, as well as those needing to innovate rapidly. New, more flexible architectures stimulate market competition in which DxR could act as an artificial selection force to influence development of faster increased flow in current PACS companies, in disruptors such as consolidated AI companies, or in entirely new entrants like Apple or Google. In this co-evolution, DxR should be able to stimulate design of a modern communication medium that increases the flow of information and decreases the time and energy necessary to absorb it, thereby creating even more indispensable clinical value for itself. [ABSTRACT FROM AUTHOR]

Stroke is a leading cause of disability and death in advanced heart failure patients supported with a continuous-flow left ventricular assist system (CF-LVAS). Statins (HMG-CoA reductase inhibitors) reduce the risk of major cardiovascular and neurological events such as stroke, but their impact has not been evaluated in patients implanted with a CF-LVAS. We sought to explore the association between use of statin therapy and subsequent occurrence of neurological events, particularly stroke, following CF-LVAS implantation. We performed a single center, retrospective, observational cohort study in 200 consecutive adults implanted with a durable CF-LVAS over a 10-year period (2008-2018). We compared patients according to statin use following pump implantation, stratified by an exploratory analysis of pump type (HeartMate II, HeartWare HVAD, and HeartMate 3 [HM3] LVAS). Overall, 24% of CF-LVAS recipients developed at least 1 neurological event, at a rate of 0.11 events per patient-year (EPPY) among those prescribed statins and 0.22 EPPY among non-users (age-adjusted hazard ratio [HR] 0.46; 95% confidence interval [CI],0.24–0.88; p = 0.019). In the cohort without the HM3 pump, ischemic strokes were 62% lower among statin users (0.05 versus 0.12 EPPY for non-users; age-adjusted HR, 0.38; 95% CI, 0.15–0.99; p = 0.048). The risk of ischemic stroke did not differ significantly when HM3 recipients were included in the analysis (age-adjusted HR, 0.51; 95% CI, 0.22–1.21; p = 0.13). However, ischemic stroke rate in HM3 LVAS recipients was similar to the rate in statin users who received a non-HM3 LVAS (0.06 and 0.05 EPPY, respectively). Rates of hemorrhagic stroke and other safety end points were not significantly different according to statin use. Statin prescription following CF-LVAS is associated with lower rates of neurological events, driven predominantly by a reduction in ischemic strokes. These findings suggest that most patients with a pre-existing indication for statin therapy may continue using statins following CF-LVAS in an effort to decrease the incidence of ischemic stroke. [ABSTRACT FROM AUTHOR]

Abstract Purpose There is an increasing effort to allow patients open access to their physician notes through electronic medical record portals. However, limited data exist on the impact of such access on oncology patients, and concerns remain regarding potential harms. Therefore, we determined the baseline perceptions and impact of open access to oncology notes on radiation oncology patients. Methods and materials Patients receiving radiation therapy were provided instructional materials on accessing oncology notes at the time of their initial evaluation. Patients were prospectively surveyed to evaluate baseline interest and expectations before access and to determine the actual usage and impact at the end of their radiation treatment course. Results A total of 220 patients were surveyed; 136 (62%) completed the baseline survey, of which 88 (40%) completed the final survey. The majority of participants were age >60 years (n = 83; 61%), and 70 were male (51%). Before accessing the notes, the majority of patients agreed that open access to oncology notes would improve understanding of diagnosis (99%), understanding of treatment side effects (98%), reassurance about treatment goals (96%), and communication with family (99%). All patients who accessed the notes found them to be useful. After accessing the notes, approximately 96%, 94%, and 96% of patients reported an improved understanding of their diagnosis, an improved understanding of treatment side effects, and feeling more reassured about their treatment, respectively. Approximately 11%, 6%, and 4% of patients noted increased worry, increased confusion, and finding information they now regret reading, respectively. Patient age, sex, and specific cancer diagnoses were not predictive of experiencing negative effects from accessing the notes. Conclusions Radiation oncology patients have a strong interest in open access to their physician notes, and the majority of patients expect and actually report meaningful benefits. These data support strategies to allow more patients with cancer access to their physicians' notes. [ABSTRACT FROM AUTHOR]

Single-crystalline, ternary n -type Bi 2 Te 3−y Se y nanowires are grown by potential-pulsed electrochemical deposition with 45 nm, 70 nm and 195 nm nominal diameters. Electrical conductivity and thermopower of the nanowires are measured. TEM analysis proves that the nanowires grow along the [110] direction with the c-axis perpendicular to the nanowire axis and yield diameters of 70–80 nm (nominally 45 nm, #1), 85–100 nm (70 nm, #2) and 265–325 nm (195 nm, #3). This yields electronic transport along the basal plane of the Bi 2 Te 3 crystal structure. Chemical composition of the nanowires is measured by TEM-EDX spectroscopy. These nanowires show exciting electronic properties, like Shubnikov-de-Haas oscillations at low temperatures, summarized in another paper. All nanowires investigated are oxygen contaminated but single crystalline, precipitates are only observed in #3 nanowire. The stoichiometry offset and fluctuations of #2 nanowire are significantly larger compared to #1 and #3 nanowires. The thermopower correlates with these structural data, the smallest thermopower is found for #2 nanowire and a similar, larger thermopower is found for #1 and #3 nanowires. For #1 and #2 nanowires dislocation densities of about 7.8 × 10 10 cm −2 and 1.0 × 10 11 cm −2 are observed, respectively, wherein dislocations lie parallel to the growth direction. While for #3 nanowire, a dislocation density of 1.2 × 10 10 cm −2 is observed and dislocations are oriented perpendicular to the growth direction. This reduces the heat conductivity of the #3 nanowire due to phonon scattering on the strain field of dislocations. [ABSTRACT FROM AUTHOR]

The overall efficiencies of screen printed monocrystalline Si solar cells are limited by electrical losses across the Si-metallization interface. The process of metallization affects the emitter and space charge region of the solar cell, particularly with respect to the dopant distributions. Until now, direct imaging of dopant distributions across the interface has not been reported mainly because the concentrations of dopants are far below the detection limit of conventional analytical tools. In the present study, we harness the high-resolution (100 nm) high-sensitivity chemical imaging with Nano Secondary Ion Mass Spectrometry (NanoSIMS) and correlate with microstructural and electrical properties to elucidate the factors limiting the overall cell efficiencies. We analysed two sets of p-type solar cells fabricated from identical starting materials, the only difference being the firing temperature. It was found that the overall efficiency of cells fired at 900 °C was ∼17% while the efficiency of cells fired at 960 °C was only 13.6%. In phosphorus (P) ion maps, the P emitter structure was found to be well-preserved by NanoSIMS in cells fired at 900 °C, it was completely disintegrated in the overfired cells and thereby increasing the contact resistance. The passivation layer (SiN X ) was found to be disintegrated in the overfired cell and furthermore, below the metallization, a diffusion cloud was observed wherein boron (B) rich domains extend over several µm. In the overfired cell the disintegration of the SiN X layer identified in the SEM correlated with the disintegrated emitter structure (P) analysed by NanoSIMS. This implies that the disintegration of the passivation layer leads to a diffusion of the dopants resulting in the loss of overall cell efficiency. Thus, our new comprehensive approach provides unprecedented insights into the factors limiting the overall efficiencies in solar cells. [ABSTRACT FROM AUTHOR]

Screen printed front side contacts were investigated in n-type, high efficiency, single-crystalline Si solar cells with B doped emitters. Cells were processed identically and two different front side pastes were used: paste Ag–Al yielded efficiencies of 20.0%, and paste Ag, without Al, yielded 16.1% efficiency only. Cells contacted with paste Ag–Al yielded a continuous glass layer, a significantly higher density of Ag colloids, and an Al mole fraction of ∼1 at%. In contrast, cells contacted with paste Ag revealed a thinner but continuous glass layer as compared to cells processed with paste Ag–Al. It contained a lower density of Ag colloids and Al was below the detection limit of the EDX microanalysis. In n-type cells pyramidal shaped Ag nanocrystals did not appear, whereas for p-type cells they are formed at intersections of differently {111} oriented surface planes at the Si emitter. We did not find Ag/Al spikes at the Si emitter for cells contacted with paste Ag–Al. Cells contacted with paste Ag–Al had a smaller series resistance as well as a significantly lower specific contact resistance (4 mΩ cm 2 ). A higher series resistance and specific contact resistance >100 mΩ cm 2 was found for cells contacted with paste Ag. It was concluded that the specific contact resistance decreases with increased wetting and increased density of Ag colloids in the glass layer. The series resistance of the Ag–Al alloy contact depended only weakly on temperature, whereas the series resistance linearly increased with temperature for contacts processed with paste Ag. p- and n-type cells with maximum efficiency yield a similar microstructure of the front side contact, similar series and contact resistance, respectively. A high density of Ag colloids in the glass layer was found for cells with low specific contact resistance. This suggests that also for n-type cells a three dimensional percolative charge transport through the glass layer is assisted by the presence of metallic Ag colloids. [ABSTRACT FROM AUTHOR]

Given the high-intensity interaction between radiology and IT, radiology leadership should understand IT's new, somewhat conflicting, dual roles. Managing large-scale and small-scale projects concurrently has become an important challenge for leaders of health IT (HIT). Historical parallels of this challenge can be drawn from transportation and communication systems, in which a large-scale mind-set is needed to build the initial network, whereas a small-scale mind-set is more useful to develop the content that will traverse this network. Innovation and creativity is a cornerstone of content small-scale thinking, and in HIT, that is what is needed to extract the value from it. However, unlike the early historical transportation and communication examples, the time between the development of the infrastructure and the follow-on, value-rich content is shortened greatly because it has become nearly simultaneous in HIT. Weaving the ability to concomitantly manage both large- and small-scale projects into the fabric of the organizational HIT culture will be critical for its success. [ABSTRACT FROM AUTHOR]

Screen printed front side contacts were investigated in single-crystalline (planar and textured) Si solar cells with n-type emitters, yielding maximum efficiencies of 18.0%. The crystallographic orientation of the Si surface and the paste strongly affect the contact formation as well as the contact resistance of the cells. For textured cells a continuous glass layer together with the formation of Ag colloids yielded a small contact resistance. Planar 〈111〉oriented Si yielded specifically lower contact resistance (〈5 mΩ cm 2 ) as compared to planar 〈100〉 orientation (〉10–40 mΩ cm 2 ) for different pastes. Pyramidal Ag crystals are formed only on 〈100〉 oriented Si, whereas lens shaped Ag crystals are grown on 〈111〉surfaces. From this it was concluded that the shape of the Ag nanocrystals determines the contact resistance, pyramidal Ag crystals formed on 〈100〉 planar surfaces yielded cells with large contact resistance and are, therefore, not considered to be necessary for a low contact resistance. Temperature dependent series resistance measurements yielded metallic behavior for cells with the lowest contact resistance bound to a certain paste. For other pastes and processing conditions a semiconducting behavior of the series resistance was found. However, cells with significant density of colloids in the glass layer yielded a small series and contact resistance. By considering the above arguments, a percolation model has been introduced in which metallic Ag colloids generate current filaments across the glass layer. This reduces the resistivity of the glass layer and thereby introduces a percolative nature of the current via Ag nanocolloids. The percolation limit for the 2d case was calculated for periodically arranged colloids with equal size and yields a minimum volume fraction of 15% for the Ag colloids in the glass layer. [ABSTRACT FROM AUTHOR]

Data on the efficacy and safety of the combination of warfarin and dual-antiplatelet therapy compared with warfarin and mono-antiplatelet therapy (MAPT) in patients with left ventricular assist devices (LVAD) remains scarce. Single-center study of 130 consecutive patients with durable LVAD. Baseline demographics, antithrombotic and antiplatelet regimen, and outcomes were compared between patients receiving warfarin plus dual-antiplatelet therapy (Group 1) and warfarin plus MAPT (Group 2). Antiplatelet therapy was assessed at hospital discharge post-LVAD implant and included aspirin, clopidogrel and dipyridamole. Outcomes at 1-year were assessed in each group. All patients were on aspirin and warfarin. No significant differences with regards to age, gender or ethnicity were noted at baseline between the two groups. Group 1 was more likely to have higher lactate dehydrogenase LDH levels at discharge and a history of stroke. No significant differences in international normalized ratio INR, hemoglobin or hematocrit were noted at discharge. During the study period, 48 patients had gastrointestinal bleeding events: 28 of 68 (41.2%) in Group 1 vs 20 of 62 (32.2%) in Group 2 (P = 0.293). At 1year, no statistically significant differences were noted in gastrointestinal bleeding (Group 1=27.90% vs Group 2 = 25.80, P = 0.784), ischemic stroke (Group 1 = 8.8% vs group 2 = 6.5%, P = 0.612), hemorrhagic stroke (Group 1 = 4.4% vs group 2 = 3.2%, P = 0.725) or mortality (Group 1 = 5.9% vs Group 2 = 1.6%, P = 0.206). Rates of pump thrombosis however were lower in Group 1 (Group 1 = 0% vs Group 2 = 6.5%, P = 0.033). Our study showed a high prevalence of triple-therapy antithrombotic use in LVAD patients with no significant differences in bleeding, stroke or survival. However, the risk for pump thrombosis was lower at 1-year when compared to patient receiving MAPT. [ABSTRACT FROM AUTHOR]

Abstract: Studies on the combined effects of beech–spruce mixtures are very rare. Hence, forest nutrition (soil, foliage) and nutrient fluxes via throughfall and soil solution were measured in adjacent stands of pure spruce, mixed spruce–beech and pure beech on three nutrient rich sites (Flysch) and three nutrient poor sites (Molasse) over a 2-year period. At low deposition rates (highest throughfall fluxes: 17kgNha−1 year−1 and 5kgSha−1 year−1) there was hardly any linkage between nutrient inputs and outputs. Element outputs were rather driven by internal N (mineralization, nitrification) and S (net mineralization of organic S compounds, desorption of historically deposited S) sources. Nitrate and sulfate seepage losses of spruce–beech mixtures were higher than expected from the corresponding single-species stands due to an unfavorable combination of spruce-similar soil solution concentrations coupled with beech-similar water fluxes on Flysch, while most processes on Molasse showed linear responses. Our data show that nutrient leaching through the soil is not simply a “wash through” but is mediated by a complex set of reactions within the plant–soil system. [Copyright &y& Elsevier]

Abstract: Phosphonates are widely used as chelating agents, e.g., in water cooling systems, in bleaching baths or as scale inhibitors in deflocculation agents. They are considered to be difficult to degrade and produce aminomethylphosphonic acid (AMPA) as a metabolite. As the fate of phosphonates in the environment is not very well known the present work aims at simulating the time dependent photodegradation of four selected phosphonates: nitrilotris-methylenephosphonic acid (NTMP), ethylenediamine-tetra-methylenephosphonic acid (EDTMP), diethylenetriaminepenta-methylenephosphonic acid (DTPMP) and hexaethylenediamine-tetra-methylenephosphonic acid (HDTMP), at concentrations of 1mg/l (i.e. 3.2μM NTMP, 2.3μM EDTMP, 1.7μM DTPMP and 2.0μM HDTMP) irradiated by a middle pressure mercury lamp emitting between 190 and 600nm. The influence of iron under different pH ranges (3, 5–6 and 10) are tested. The degradation of phosphonates is measured by the release of orthophosphates (PO4-P) and aminomethylphosphonic acid (AMPA). This study shows that phosphonates are substances that undergo UV light conversion, which is enhanced in the presence of iron. The half-life without iron is between 15 and 35min at pH 3, between 10 and 35min at pH 5–6 and between 50 and 75min at pH 10. The half-life in the presence of 3.6μM iron is between 5 and 10min at pH 3, between 5 and 15min at pH 5–6 and between 35 and 60min at pH 10. The individual substances do not significantly influence the reaction rates whereas the presence of iron and the pH have significant effects. The total conversion of phosphonates after 90min is 75–100% for pH values of 3 and 5–6 and 55–75% for a pH of 10 dependent on the presence of iron. In the environment longer degradation times are to be expected since natural light is weaker by a factor between 125 and 300in the UVB, a factor between 3 and 8 in the UVA and of the same intensity in the visible range than the light in our study. Although orthophosphates are the major products, AMPA is also shown to be a by-product of the photodegradation of phosphonates that is later converted into orthophosphate. [Copyright &y& Elsevier]

Abstract: Phospholipid fatty acid (PLFA) patterns were used to describe the composition of the soil microbial communities under 12 natural forest stands including oak and beech, spruce–fir–beech, floodplain and pine forests. In addition to the quantification of total PLFAs, soil microbial biomass was measured by substrate-induced respiration and chloroform fumigation–extraction. The forest stands possess natural vegetation, representing an expression of the natural site factors, and we hypothesised that each forest type would support a specific soil microbial community. Principal component analysis (PCA) of PLFA patterns revealed that the microbial communities were compositionally distinct in the floodplain and pine forests, comprising azonal forest types, and were more similar in the oak, beech and spruce–fir–beech forests, which represent the zonal vegetation types of the region. In the nutrient-rich floodplain forests, the fatty acids 16:1ω5, 17:0cy, a15:0 and a17:0 were the most prevalent and soil pH seemed to be responsible for the discrimination of the soil microbial communities against those of the zonal forest types. The pine forest soils were set apart from the other forest soils by a higher abundance of PLFA 18:2ω6,9, which is typical of fungi and may also indicate ectomycorrhizal fungi associated with pine trees, and high amounts of PLFA 10Me18:0, which is common in actinomycetes. These findings suggest that the occurrence of azonal forest types at sites with specific soil conditions is accompanied by the development of specific soil microbial communities. The study provides information on the microbial communities in undisturbed forest soils which may facilitate interpretation of data derived from managed or even damaged or degraded forests. [Copyright &y& Elsevier]

Patients with durable left ventricular assist devices (LVADs) are at high risk for serious infection and associated mortality. Furthermore, these patients also have a high prevalence of iron deficiency due to ongoing hemolysis, increased propensity for gastrointestinal bleeding, and dysregulated iron metabolism that accompanies mechanical circulatory support and heart failure. Intravenous (IV) iron-related supplementation [IVIRS, including IV iron infusion or red blood cell transfusion (RBC)] has been hypothesized to increase risk of infection. IVIRS (IV iron infusion or RBC transfusion) is associated with an increased risk of serious infection in LVAD patients. This is a single center, retrospective, observational cohort study of 211 consecutive adult patients [median age 57.2 years (25th-75th percentile: 48.7-65.7 years), 19% female] who were discharged and followed after de-novo LVAD implantation between May 2008 and December 2019. Patients were followed until either end of the study period, or occurrence of death, heart transplantation, or LVAD removal/replacement, whichever came first. All administration of IVIRS and diagnosis of serious infection after discharge from index hospitalization was abstracted from the electronic medical record. Serious infection was defined as the first incident infection requiring hospitalization, divided into LVAD-associated infections (pump/cannula, pocket or driveline infection) and non-LVAD infections. Multivariate logistic regression was used to examine the association between IVIRS and serious infections. Over a median follow-up of 15.2 months (25th-75th percentile: 6.9-29.4 months), 69 (33%) LVAD patients received IVIRS, of whom 47 (68%) received IV iron and 44 (64%) received RBC transfusion. During follow-up, 87 (41%) patients suffered a serious infection, of which 48 (55%) were LVAD-associated infections and 39 (45%) were non-LVAD infections. After adjustment for age, sex, diabetes, chronic kidney disease, prior cardiac surgery, destination therapy and pre-IVIRS serious infection, LVAD patients who received IVIRS had 2.85 times higher odds of any first serious infection compared to those who did not receive IVIRS during the study period (95% CI 1.49-5.46, p=0.002). Patients who received IVIRS had a significant 3.03 times greater odds of non-LVAD infection (95% CI 1.37-6.70, p=0.006) and a non-significant 1.54 times greater odds of LVAD infection (95% CI 0.75-3.18, p=0.24), compared to LVAD patients who did not receive IVIRS. IVIRS use is associated with a higher risk of serious infection in LVAD patients, primarily due to serious non-LVAD infections. These findings merit further study in larger cohorts and randomized trials to determine best practices surrounding IVIRS in LVAD patients. [ABSTRACT FROM AUTHOR]

Recent investigations of the front side metallization of high-efficiency mono-crystalline Si solar cells proved that the glass layer formed at the Si/metallization interface during the screen printing plays an essential role for the charge transport, both in n- and p-type cells. High-efficiency cells (~ 18.0% for p-type and ~ 20% for n-type cells) show similar microstructure of the glass layer and similar temperature dependence of the series resistance. From this it is concluded that the microstructure of the glass layer determines the series and contact resistance of the front side metallization. The glass layers of high-efficiency cells contain a high density of nano-Ag colloids and other precipitates which reduce the contact resistance. A percolation model was proposed and is best suited to describe the charge transport in a dirty semiconductor containing metallic precipitates. Quantitative chemical composition of the glass layer of p- and n-type cells was investigated by Energy Dispersive X-ray (EDX) microanalysis in SEM and TEM. The chemical composition of the glass layer showed (SiO x )Pb, as main constitutes and Zn, Ti, Al, Ag, P and B as minor constituents with mole fractions above the detection limit of EDX. The glass layer is therefore considered to be a dirty semiconductor rather than a perfect insulator. The mole fractions of Zn (~ 1 at%) and Al (~ 1 at%) were quantitatively analyzed. Such analyses are important to correlate microstructural features with electrical properties of the front side metallization. We could prove that in p-type cells the efficiency of the cells correlated with the chemical composition of the glass layer. In n-type cells, with Al-containing pastes EDX spectroscopy yielded Al beyond the detection limit in the glass layer, whereas for Al free pastes the Al mole fraction was below the detection limit of EDX and yielded reduced efficiencies. In p-type cells pastes with enhanced Zn mole fraction yielding zinc oxide phases in the bulk Ag finger and Zn mole fractions up to 5 at% in the glass layer. [ABSTRACT FROM AUTHOR]

Abstract: The soil microbial communities of a landfill cover substrate, which was treated with landfill gas (100lCH4 m−2 d−1) and landfill leachate for 1.5 years, were investigated by phospholipid fatty acid (PLFA), ergosterol and respiratory quinone analyses. The natural 13C depletion of methane was used to assess the activity of methanotrophs and carbon turnover in the soil system. Under methane addition, the soil microbial community was dominated by PLFAs (14:0 and 16:1 isomers) and quinones (ubiquinone-8 and 18-methylene-ubiquinone-8) related to type I methanotrophs, and 18:1 PLFAs contained in type II methanotrophs. While type I methanotrophic PLFAs were 13C depleted, i.e. type I methanotrophs were actively oxidising and assimilating methane, 13C depletion of 18:1 PLFAs was low and inconsistent with their abundance. This, possibly reflects isotopic discrimination, assimilation of carbon derived from type I methanotrophs and a high contribution of non-methanotrophic bacteria to the 18:1 isomers. Landfill leachate irrigation caused the methanotrophic community to shift closer to the soil surface. It also decreased 18:1 PLFAs, while type I methanotrophs were probably stimulated. Gram positive bacteria, but not fungi, were also 13C depleted and consequently involved in the secondary turnover of carbon originating from methanotrophic bacteria. Cy17:0 PLFA was 13C depleted in deep soil layers, indicating anaerobic methane oxidation. [Copyright &y& Elsevier]

Presqualene diphosphate (PSDP) is a bioactive lipid that rapidly remodels to presqualene monophosphate (PSMP) upon cell activation (Levy, B. D., Petasis, N. A., and Serhan, C. N. (1997) Nature 389, 985–990). Here, we have identified and characterized a phosphatase that converts PSDP to PSMP. Unlike the related polyisoprenyl phosphate farnesyl diphosphate (FDP), PSDP was not a substrate for type 2 lipid phosphate phosphohydrolases. PSDP phosphatase activity was identified in activated human neutrophil (PMN) extracts and partially purified in the presence of Nonidet P-40 with gel filtration and anion exchange chromatography. Peptide sequencing of a candidate phosphatase was consistent with phosphatidic acid phosphatase domain containing 2 (PPAPDC2), an uncharacterized protein that contains a lipid phosphate phosphohydrolase consensus motif. Recombinant PPAPDC2 displayed diphosphate phosphatase activity with a substrate preference for PSDP > FDP > phosphatidic acid. PPAPDC2 activity was independent of Mg2+ and optimal at pH 7.0 to 8.0. Incubation of [14C]FDP with recombinant human squalene synthase led to [14C]PSDP and [14C]squalene formation, and in the presence of PPAPDC2, [14C]PSMP was generated from [14C]PSDP. PPAPDC2 mRNA was detected in human PMN, and is widely expressed in human tissues. Together, these findings indicate that PPAPDC2 in human PMN is the first lipid phosphate phosphohydrolase identified for PSDP. Regulation of this activity of the enzyme may have important roles for PMN activation in innate immunity. [ABSTRACT FROM AUTHOR]

Mesophase pitch, in common with other liquid crystalline substances, exhibits preferred angles of molecular orientation at its boundaries with other phases. These orientations, or surface anchoring states, are important because they influence the ultimate graphene layer arrangement in a variety of carbon materials where the pitch precursor encounters a composite filler, a free surface, a bubble cavity, or the surfaces of processing equipment such as a fiber spinneret. This paper presents experimentally determined anchoring states for two mesophase pitches at free surfaces, and on twenty solid substrates. Edge-on anchoring is found to be the most common state, occurring on the free surface, on some metals, on PTFE, and on all oxides with the exception of the lamellar material mica. The optical texture associated with the edge-on films is observed to be stable during carbonization up to 1200 °C. Face-on anchoring is observed on carbon graphene planes, mica and the metals Pt, Ni, and Ag. Trends in the data are discussed in terms of the strength of pitch/substrate intermolecular forces relative to π–π bonding between large discotic mesogens within the pitch. The implications for the structure and properties of carbon materials are discussed. [Copyright &y& Elsevier]