Background Spots Research Articles

Towards high-throughput parallel imaging and single-cell transcriptomics of microbial eukaryotic plankton.

Single-cell transcriptomics has the potential to provide novel insights into poorly studied microbial eukaryotes. Although several such technologies are available and benchmarked on mammalian cells, few have been tested on protists. Here, we applied a microarray single-cell sequencing (MASC-seq) technology, that generates microscope images of cells in parallel with capturing their transcriptomes, on three species representing important plankton groups with different cell structures; the ciliate Tetrahymena thermophila, the diatom Phaeodactylum tricornutum, and the dinoflagellate Heterocapsa sp. Both the cell fixation and permeabilization steps were adjusted. For the ciliate and dinoflagellate, the number of transcripts of microarray spots with single cells were significantly higher than for background spots, and the overall expression patterns were correlated with that of bulk RNA, while for the much smaller diatom cells, it was not possible to separate single-cell transcripts from background. The MASC-seq method holds promise for investigating "microbial dark matter", although further optimizations are necessary to increase the signal-to-noise ratio.

Infrared Gas Detection and Concentration Inversion Based on Dual-Temperature Background Points

Gas detection based on infrared thermal imaging is applied in many areas, but it is generally applied as a qualitative detection method to observe the target area; on the other hand, quantitative research on gas concentration is less common, the measurement accuracy is poor, and the calculation method of concentration in the commonly adopted transmission model is also complicated. In this paper, based on the radiance transfer model of gas infrared imaging technology, the influence of gas concentration, gas temperature, and background temperature on gas imaging detection is investigated, a gas detection and concentration inversion method based on dual-temperature background points is proposed, and the effects of the choice of reference band on background temperature correction are analyzed in relation to the changing trend of dual-band radiance difference. To verify the effectiveness of this method, a gas detection system with dual-temperature background spots was constructed in this paper utilizing a cooled mid-wave infrared focal plane detector plus a reference filter and a measurement filter, which achieved a promising concentration accuracy of less than 10% for carbon dioxide at a detectable range. Meanwhile, an infrared imaging system with a noise equivalent temperature difference (NETD) of 40 mK was employed to simulate the detection of methane, which enables the detection and concentration inversion of methane gas at a minimum concentration of 500 ppm·m at a distance of 1 km, which proves the capability of long-range detection.

Pupal Warning Coloration of Three Species of Cystidia (Lepidoptera: Geometridae: Ennominae) in Relation to Their Pupation Sites.

Many insects display a cryptic color to avoid detection by predators that search for prey by sight. However, some species with chemicals that predators dislike may display a warning color (aposematism) to predators. The predators can learn easier that the species is unsuitable as prey if the color is more conspicuous. Therefore, it is assumed that the acquisition of the warning color requires not only unpalatability, but also exposure of the color to predators and the ability of predators to recognize and learn it unpalatable. In the moths of the subfamily Ennominae, almost all of genera produce uniformly brown or green pupae, but the pupae of the genus Cystidia have conspicuous coloration of yellow background and black spots. In this study, to clarify whether the color of these pupae is the warning color or not, we compared the coloration, pupation site, and palatability among the three species of this genus: C. couaggaria, C. truncangulata, and C. stratonice. Learning by the predators was also examined using lizards as a potential predator of the moths. The results showed that all three species were repelled (unpalatable) by the lizards, and that repeated providing of the pupae to the lizards decreased their willingness to prey on them (probably due to learning). Pupation sites of C. couaggaria and C. truncangulata were located on the surface of branches and leaves high above the ground, whereas C. stratonice pupated in the space of leaves spun with course silk at lower site above the ground. Thus, the conspicuous coloration of pupal Cystidia is considered to be a warning color, but the pupae of C. stratonice are more blackish than those of the most closely related C. truncangulata. The pupal color of C. stratonice is likely to have a dual meaning as cryptic and warning colors. The dark colored pupa may be inconspicuous when hidden within the leaf space, but once detected by the predators, the yellow color of the pupa may function as a warning color.

The application of the nnU-Net-based automatic segmentation model in assisting carotid artery stenosis and carotid atherosclerotic plaque evaluation.

Objective: No new U-net (nnU-Net) is a newly-developed deep learning neural network, whose advantages in medical image segmentation have been noticed recently. This study aimed to investigate the value of the nnU-Net-based model for computed tomography angiography (CTA) imaging in assisting the evaluation of carotid artery stenosis (CAS) and atherosclerotic plaque. Methods: This study retrospectively enrolled 93 CAS-suspected patients who underwent head and neck CTA examination, then randomly divided them into the training set (N = 70) and the validation set (N = 23) in a 3:1 ratio. The radiologist-marked images in the training set were used for the development of the nnU-Net model, which was subsequently tested in the validation set. Results: In the training set, the nnU-Net had already displayed a good performance for CAS diagnosis and atherosclerotic plaque segmentation. Then, its utility was further confirmed in the validation set: the Dice similarity coefficient value of the nnU-Net model in segmenting background, blood vessels, calcification plaques, and dark spots reached 0.975, 0.974 0.795, and 0.498, accordingly. Besides, the nnU-Net model displayed a good consistency with physicians in assessing CAS (Kappa = 0.893), stenosis degree (Kappa = 0.930), the number of calcification plaque (Kappa = 0.922), non-calcification (Kappa = 0.768) and mixed plaque (Kappa = 0.793), as well as the max thickness of calcification plaque (intraclass correlation coefficient = 0.972). Additionally, the evaluation time of the nnU-Net model was shortened compared with the physicians (27.3 ± 4.4s vs. 296.8 ± 81.1s, p < 0.001). Conclusion: The automatic segmentation model based on nnU-Net shows good accuracy, reliability, and efficiency in assisting CTA to evaluate CAS and carotid atherosclerotic plaques.

New genus of the family Ratardidae (Lepidoptera: Cossoidea) from New Guinea

Praesaturnia roepkei Yakovlev, de Vos et Hulsbosch, gen. et sp. n. is described from Papua Province of Indonesia. The new genus clearly differs from the known genera of Ratardidae in the very primitive wing pattern (wide dark portions on the light background and large round discal spots on all wings); the very deep cup-like ostium and the special sclerite of the lamina postvaginalis shaped as an elongated frustum, basally wide and apically forked into two small distinct lobes. The general distribution of representatives of the family Ratardidae is also discussed.

Bacterial taxa predictive of hyperpigmented skins.

Background and AimsDark spots, brown spots, or hyperpigmented spots (HPS) are oval or irregular brown areas of skin. Their emergence is associated with dysregulation of the immune system, and may also be caused by a deficiency in stromal cell‐derived factor‐1, leading to perturbed melanogenesis and accumulation of melanosomes within neighboring keratinocytes. The skin microbiota (living microorganisms present on the surface of the skin) is known to play essential roles in maintaining skin homeostasis and in regulating the immune system. Here, we investigated whether the microbiota could play a role in the emergence of HPS.MethodsThe clinical study involved 38 European women, selected from among 74 volunteers. Participants were divided into two groups depending on the spot areas measured on their faces. The study was designed to avoid conflicting factors: both groups presented similar skin pH, hydration, transepidermal water loss, and sebum levels. The two cohorts were also age‐matched, with a mean of 29‐years‐old for both.ResultsAlpha‐diversity of the microbiota was similar for the two groups. On skins with more HPS, seven bacterial genera were identified in significantly higher proportions and included opportunistic pathogens and inflammatory bacteria. Six bacterial genera, including bacteria showing antioxidant and anti‐UV properties, were identified in significantly higher proportions on less spotted skins. Cross‐domain association networks revealed distinct co‐occurrences of genera between the two groups, suggesting nonidentical community structures and exchanges, depending on the HPS status.ConclusionOur results reveal specific microbiota composition and networks on skins based on HPS status. Changes could alter communication with the immune system, leading to the emergence of dark spots. As an essential part of the overall skin ecosystem, and through its interaction with the skin matrix, the skin microbiota and its maintenance could be considered a new target for skincare applications.

Morphological and structural study of crystals in black-to-brown glazes of Yaozhou ware (Song dynasty) using imaging and spectroscopic techniques

The Yaozhou kiln complex (Shaanxi, China) is a famous black-to-brown ceramic production center due to its significant volume of production, long manufacturing history (from Tang Dynasty to Yuan Dynasty) and variety of decorations. In this work, four representative types of black-to-brown ware from the Yaozhou kilns were selected to study the morphology, structure and distribution of the precipitated crystals in the glazes using a series of imaging and analytical techniques (optical microscopy, XRF, SEM-EDS, TEM-EDS, μRS and UV–vis-IR). The results show that the rare metastable ε-Fe2O3 phase, already observed in typical sauce glaze, was also detected in other types of brown glaze decorations, such as light brown stripes on a darker background or irregular brown spots on a black background. Cross-section analyses also showed a three well-separated layered crystalline distribution in the glazes of lighter brown colors as it has been noted in glazes from Qilizhen kilns. Raman analyses revealed that the crystals contained in third layer are of varying nature: ε-Fe2O3 in the sauce glaze and magnetite in the light brown stripes. The peak shifts and line broadenings observed in the Raman spectra of ε-Fe2O3 crystals were also investigated. They are the result of Al, Ti and Mg substitutions, which were identified using TEM-EDS. Such ionic substitutions would stabilize the metastable ε-Fe2O3 crystals by increasing the cationic disorder. In addition, Mg-, Ca- and Fe-rich spinel crystals were observed for the first time in a black glaze of Yaozhou wares.

Primary yields of protons measured using CR-39 in laser-induced deuteron–deuteron fusion reactions

Investigating deuteron–deuteron (DD) fusion reactions in a plasma environment similar to the early stages of the Big Bang is an important topic in nuclear astrophysics. In this study, we experimentally investigated such reactions, using eight laser beams with the third harmonic impacting on a deuterated polyethylene target at the ShenGuang-II Upgrade laser facility. This work focused on the application of range-filter (RF) spectrometers, assembled from a 70 μm aluminum filter and two CR-39 nuclear track detectors, to measure the yields of primary DD-protons. Based on the track diameter calibration results of 3 MeV protons used to diagnose the tracks on the RF spectrometers, an approximate primary DD-proton yield of $$(8.5\pm 1.7)\times 10^6$$ was obtained, consistent with the yields from similar laser facilities worldwide. This indicates that the RF spectrometer is an effective way to measure primary DD-protons. However, due to the low yields of $${\hbox {D}}^{3}{\mathrm {He}}$$-protons and its small track diameter, CR-39 detectors were unable to distinguish it from the background spots. Using other accurate detectors may help to measure these rare events.

Effect of nickel addition on densification, microstructure and wear behaviour of spark plasma sintered CP-titanium

Titanium alloys with varying amounts of nickel additions (2, 6 and 10 wt%) were prepared through the spark plasma sintering technique. The influence of nickel additions on densification, microstructure and wear behaviour of the sintered alloys was investigated, against commercially-pure titanium (CP–Ti). SEM analysis results showed a mixed portion of dark background (α-Ti), white patches and bright spots within the matrix of the sintered binary alloys compared to sintered CP-Ti matrix. These white patches and bright spots were confirmed by the X-ray diffraction (XRD) results to be a mixture of intermetallic phases of Ti2Ni (FCC) and TiNi2 (HCP). The relative density and the microhardness value were found to increase from 91.42% to 99.6% and 212 HV0.1 to 343 HV0.1 respectively. Estimated yield and tensile strength values were observed to vary linearly with increasing concentration of Ni in the sintered alloys. Analysis of the worn surfaces indicated improved resistance to adhesive and abrasive wear with increasing nickel content in the sintered alloys.

Research on extraction and reproduction of deformation camouflage spot based on generative adversarial network model

The method of describing deformation camouflage spots based on feature space has some shortcomings, such as inaccurate description and difficult reproduction. Depending on the strong fitting ability of the generative adversarial network model, the distribution of deformation camouflage spot pattern can be directly fitted, thus simplifying the process of spot extraction and reproduction. The requirements of background spot extraction are analyzed theoretically. The calculation formula of limiting the range of image spot pixels is given and two kinds of spot data sets, forestland and snowfield, are established. Spot feature is decomposed into shape, size and color features, and a GAN (Generative Adversarial Network) framework is established. The effects of different loss functions on network training results are analyzed in the experiment. In the meantime, when the input dimension of generator network is 128, the balance between sample diversity and quality can be achieved. The effects of sample generation are investigated in two aspects. Subjectively, the probability of the generated spots being distinguished in the background is counted, and the results are all less than 20% and mostly close to zero. Objectively, the features of the spot shape are calculated and the independent sample T-test is applied to verify that the features are from the same distribution, and all the P-Values are much higher than 0.05. Both subjective and objective methods prove that the spots generated by this method are similar to the background spots. The proposed method can directly generate the desired camouflage pattern spots, which provides a new technical method for the deformation camouflage pattern design and camouflage effect evaluation.

A snapshot research and implementation of multimodal information fusion for data-driven emotion recognition

With the rapid development of artificial intelligence and mobile Internet, the new requirements for human-computer interaction have been put forward. The personalized emotional interaction service is a new trend in the human-computer interaction field. As a basis of emotional interaction, emotion recognition has also introduced many new advances with the development of artificial intelligence. The current research on emotion recognition mostly focuses on single-modal recognition such as expression recognition, speech recognition, limb recognition, and physiological signal recognition. However, the lack of the single-modal emotional information and vulnerability to various external factors lead to lower accuracy of emotion recognition. Therefore, multimodal information fusion for data-driven emotion recognition has been attracting the attention of researchers in the affective computing filed. This paper reviews the development background and hot spots of the data-driven multimodal emotion information fusion. Considering the real-time mental health monitoring system, the current development of multimodal emotion data sets, the multimodal features extraction, including the EEG, speech, expression, text features, and multimodal fusion strategies and recognition methods are discussed and summarized in detail. The main objective of this work is to present a clear explanation of the scientific problems and future research directions in the multimodal information fusion for data-driven emotion recognition field.

Abstract P4-06-04: Targeting neo-epitopes from PIK3CA and p53 mutations for immunotherapy of breast cancer

Abstract Introduction: Preclinical data suggests that priming T cell immunity to mutated or overexpressed proteins can induce tumor rejection, and may potentiate the effects of checkpoint blockade. PIK3CA and p53 are the most commonly mutated genes in breast cancer, and are enriched in high-grade and metastatic tumors. Here, we evaluated the immunogenicity of neo-epitopes derived from common PIK3CA and p53 mutations. Methods: We applied a custom informatics pipeline, EpitopeHunter, to predict neo-epitopes (8-11mers) from twelve PIK3CA and ten p53 mutations restricted to thirty-nine MHC class I alleles. We selected high affinity neo-epitopes (IEDB score &amp;lt; 500) with predicted poor binding of the matched wild type epitope. We used the predicted peptides to stimulate PBMC from healthy donors in vitro, and measured T cell immunity by interferon-γ ELISPOT. We compared the T cell specificity of mutant vs wild type epitopes. A positive response to an epitope was defined as a response that met both of the following criteria: 1) net number of spots (after subtracting background) was &amp;gt;5 spots/50,000 cells and 2) net number of spots exceeded the background spots plus two SDs. Results: In total, 1,824 PIK3CA and 1,520 p53 derived peptide sequences were generated. Of these, 42 PIK3CA (2%) and 45 p53 (3%) peptides were predicted to bind to the HLA class I molecules included in our study. Over 90% of the neo-epitopes were 9- and 10-mers, and the predicted neo-epitopes varied across mutations (range 2-10 per mutation). PIK3CAH1047L and p53R248W had the highest number of potential binding neo-epitopes (n=10 each). We successfully generated T cell lines specific for A*0201 PIK3CAH1047L, A*1101 PIK3CAH1047L, A*1101 PIK3CAE542K and A*0201 p53R248W. Conclusions: Common mutations of PIK3CA and p53 can lead to the generation of potential HLA class I restricted neo-epitopes. We identified four immunogenic neo-epitopes, which may serve as candidates for targeted immunotherapy in breast cancer. Citation Format: Chen M, Yuvaraj P, Sharma AA, Narang P, Wilson Sayres MA, Anderson KS. Targeting neo-epitopes from PIK3CA and p53 mutations for immunotherapy of breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-06-04.

IDENTIFICATION OF MOST SUITABLE BINARISATION METHODS FOR ACEHNESE ANCIENT MANUSCRIPTS RESTORATION SOFTWARE USER GUIDE

The Aceh Museum stores many digitized ancient manuscripts from hundreds of years ago. The condition of those manuscripts has degraded into several degradation types such as uneven contrast, show through effects, background spots, and text fading, which cause decreasing readability. A binarisation method is used to decrease the degradation effect on ancient manuscripts. Our research team is currently working on developing application software that consists of five binarisation methods, namely Otsu, Niblack, Sauvola, Lu, and Su for ancient manuscript restoration for the Aceh Museum staff to improve documents’ readability. In practice, a user still finds it difficult to choose the best method because there is no method that works best on every ancient manuscript for different types of degradation. This paper intends to determine a binarisation method that suits most manuscript conditions. The method used in this research includes the identification and classification of degradation types from 200 ancient Aceh digital manuscripts, followed by cropping the manuscripts to the size of 256 x 256 pixels. As many as five cropped areas from each degradation type are selected as research samples. These samples are binarisated using the methods. The last step is finding the most suitable binarisation method for each degradation type and classifying which methods are considered to have good readability, and that achieves at least 80% recall and precision values. From our experiments, we found that the Su binarisation methods demonstrate the best performance overall for every degradation type. Otsu, Lu, and Su are suited for uneven background; Sauvola, Lu, and Su are suited for showthrough effects; Otsu, Sauvola, and Su are suited for background spots; and Otsu and Su are suited for both text and background blurring and ‘fox’.

Binocular fusion of luminance, color, motion and flicker – Two eyes are worse than one

How much information is conserved, or discarded, as it travels through the visual system? A target (an oriented bar) was defined by dark grey spots embedded in light spots for the left eye, and by light grey spots embedded in dark spots for the right eye. With one eye open, the target bars were clearly visible, but with both eyes open the light and dark spots fused binocularly into medium grey and the target vanished. Results were similar for color; the target comprised greenish spots embedded in reddish spots for the left eye, and by reddish spots embedded in greenish spots for the right eye (somewhat like an Isihara color plate). Result The colored targets were invisible when both eyes were open but reappeared when one eye was closed. Small targets that moved in opposite directions in the two eyes were visible to each eye alone by common fate, but motion averaging made them disappear when both eyes were open. Conclusion Opposed retinal luminances or colors were averaged out by binocular fusion, but could be retrieved by a special afterimage technique in Experiment 6. Conversely, in Experiment 7 dichoptic target spots flickered in counterphase but background spots flickered in-phase to the two eyes. Result The targets were invisible monocularly but became visible as reduced-flicker when fused binocularly. We conclude that two eyes were worse than one eye when opposite colors or movements were fused (Experiments 1–6) but were better than one when binocular correlations could be extracted (Experiment 7). These experiments show how much of the visual information gets transmitted, gets discarded, can still be retrieved, or reaches conscious awareness.

Incorporation of methyl-protonated valine and leucine residues into deuterated ocean pout type III antifreeze protein: expression, crystallization and preliminary neutron diffraction studies.

Antifreeze proteins (AFPs) are found in different species from polar, alpine and subarctic regions, where they serve to inhibit ice-crystal growth by adsorption to ice surfaces. Recombinant North Atlantic ocean pout (Macrozoarces americanus) AFP has been used as a model protein to develop protocols for amino-acid-specific hydrogen reverse-labelling of methyl groups in leucine and valine residues using Escherichia coli high-density cell cultures supplemented with the amino-acid precursor alpha-ketoisovalerate. Here, the successful methyl protonation (methyl reverse-labelling) of leucine and valine residues in AFP is reported. Methyl-protonated AFP was expressed in inclusion bodies, refolded in deuterated buffer and purified by cation-exchange chromatography. Crystals were grown in D(2)O buffer by the sitting-drop method. Preliminary neutron Laue diffraction at 293 K using LADI-III at ILL showed in a few 24 h exposures a very low background and clear small spots up to a resolution of 1.80 A from a crystal of dimensions 1.60 x 0.38 x 0.38 mm corresponding to a volume of 0.23 mm(3).

Perdeuteration, purification, crystallization and preliminary neutron diffraction of an ocean pout type III antifreeze protein.

The highly homologous type III antifreeze protein (AFP) subfamily share the capability to inhibit ice growth at subzero temperatures. Extensive studies by X-ray crystallography have been conducted, mostly on AFPs from polar fishes. Although interactions between a defined flat ice-binding surface and a particular lattice plane of an ice crystal have now been identified, the fine structural features underlying the antifreeze mechanism still remain unclear owing to the intrinsic difficulty in identifying H atoms using X-ray diffraction data alone. Here, successful perdeuteration (i.e. complete deuteration) for neutron crystallographic studies of the North Atlantic ocean pout (Macrozoarces americanus) AFP in Escherichia coli high-density cell cultures is reported. The perdeuterated protein (AFP D) was expressed in inclusion bodies, refolded in deuterated buffer and purified by cation-exchange chromatography. Well shaped perdeuterated AFP D crystals have been grown in D(2)O by the sitting-drop method. Preliminary neutron Laue diffraction at 293 K using LADI-III at ILL showed that with a few exposures of 24 h a very low background and clear small spots up to a resolution of 1.85 A were obtained using a ;radically small' perdeuterated AFP D crystal of dimensions 0.70 x 0.55 x 0.35 mm, corresponding to a volume of 0.13 mm(3).

Biotin−Avidin Binding Kinetics Measured by Single-Molecule Imaging

The high affinity of avidin for biotin has made it useful for many bioanalytical applications involving the immobilization of proteins, vesicles, and other biomolecules to surfaces. To understand the formation and stability of the resulting biotin-avidin complex, it is useful to know the kinetics of the binding reaction, especially for situations where the complex is formed at a liquid-solid interface typically used in sensor or separation applications. In this work, a single-molecule fluorescence method is developed for measuring the kinetics and affinity constant for the binding of neutravidin, a deglycosylated variant of avidin, to surface-immobilized biotin. Biotin was immobilized using succinimidyl ester chemistry onto amine sites on glass surfaces. The surface density of biotin was controlled by the extreme dilution of 3-aminopropyltriethoxysilane into a monolayer of 2-cyanoethyltriethoxysilane. The resulting biotin binding sites are spaced apart by micrometer distances, and this avoids crowding effects and makes the resolution of single molecules possible. The binding and unbinding of individual tetramethylrhodamine-labeled neutravidin molecules is measured in situ by total-internal-reflection fluorescence (TIRF) microscopy imaging. Single-molecule detection and counting is readily achieved by this measurement, where quantitative control is established by determining the probabilities of false positive and negative events based on the intensity distributions of background and single-molecule spots and by comparing the bound molecule populations with the independently measured density of binding sites on the surface. The kinetics of binding and unbinding are evaluated by intermittent imaging and counting the number of bound neutravidin molecules versus time, following introduction of a neutravidin solution or its replacement by buffer over the low-density biotinylated surface. The neutravidin binding kinetics were found to be fast, essentially diffusion-controlled, while the stability of the complex and its dissociation rate appear to be influenced by the chemistry of biotin immobilization.

Methane production and bubble emissions from arctic lakes: Isotopic implications for source pathways and ages

This study reports an atmospheric methane (CH4) source term previously uncharacterized regarding strength and isotopic composition. Methane emissions from 14 Siberian lakes and 9 Alaskan lakes were characterized using stable isotopes (13C and D) and radiocarbon (14C) analyses. We classified ebullition (bubbling) into three categories (background, point sources, and hot spots) on the basis of fluxes, major gas concentrations, and isotopic composition. Point sources and hot spots had a strong association with thermokarst (thaw) erosion because permafrost degradation along lake margins releases ancient organic matter into anaerobic lake bottoms, fueling methanogenesis. With increasing ebullition rate, we observed increasing CH4 concentration of greater radiocarbon age, depletion of 13CCH4, and decreasing bubble N2 content. Microbial oxidation of methane was observed in bubbles that became trapped below and later within winter lake ice; however, oxidation appeared insignificant in bubbles sampled immediately after release from sediments. Methanogenic pathways differed among the bubble sources: CO2 reduction supported point source and hot spot ebullition to a large degree, while acetate fermentation appeared to contribute to background bubbling. To provide annual whole‐lake and regional CH4 isofluxes for the Siberian lakes, we combined maps of bubble source distributions with long‐term, continuous flux measurements and isotopic composition. In contrast to typical values used in inverse models of atmospheric CH4 for northern wetland sources (δ13CCH4 = −58‰, 14C age modern), which have not included northern lake ebullition as a source, we show that this large, new source of high‐latitude CH4 from lakes is isotopically distinct (δ13CCH4 = −70‰, 14C age 16,500 years, for North Siberian lakes).

Raman spectroscopic evaluation of the influence of Pseudomonas bacteria on aflatoxin B1 in the BioArena complex bioautographic system

AbstractThe mechanism of the antibacterial‐toxic effect of aflatoxin B1 (AFB1) was investigated in the BioArena complex bioautographic system that consists of planar liquid chromatographic development and biological detection. In this system, the killing‐inhibiting activity of AFB1 against Pseudomonas savastanoi (Psm) bacterial cells was visualised. The role of formaldehyde (HCHO) was suggested in the antibacterial‐toxic action of AFB1. Raman spectroscopy (RS) was used to investigate whether the excess HCHO found earlier in the AFB1 spot (comparing with background) originated partly from the demethylation of the toxin, or only from the enhanced demethylation of the normal cell ingredients because of the stress situation. Fourier transform (FT) Raman and surface‐enhanced FT‐Raman spectra were obtained in situ about the AFB1 chromatographic and background spots in bacteria‐free and inoculated thin layer chromatography (TLC) layers, and ex situ about their dried methanolic extract. The reduction of the δ CH3 band of AFB1 (1386 cm−1) in the presence of Psm can indicate the demethylation of aflatoxin at its methoxy‐group in BioArena. It seems from the Raman spectra that, apart from demethylation, aflatoxin does not suffer other structural changes. However, Psm can reduce the Raman activity of νCO bond of the pyran ring of AFB1, causing lower intensity and a broader band (1747 and 1754 cm−1). Psm can also disrupt the strong interactions between the AFB1 and the adsorbent layer through the νCO bond of the cyclopentene ring causing a blue‐shift (1667 → 1686 cm−1).The very reactive HCHO that originated from exogenous sources, e.g. from the demethylation of AFB1, has no determined biochemical pathway, so it means higher risk. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Cross-Linked Naphthalene Bisimide &amp;#x201C;E-Barrier&amp;#x201D; Layer Compositions Using Blocked Isocyanate Chemistry

High-quality electrophotographic applications demand a photoreceptor drum that is &#x201C;perfect&#x201D; in many aspects, such as being defect-free&#x2014;almost to the submicrometer level&#x2014;environmentally insensitive, and possessing a welldefined photosensitivity that matches the electrophotographic rendering process.Managing hole injection from the conductive substrate is critical to prevent &#x201C;background and breakdown spots&#x201D; on the final prints. Typical solutions require a hole-injection barrier layer. These layers need to be environmentally insensitive, resistant to the charge generation layer coating solutions, while allowing transport of photogenerated electrons to the conductive layer to prevent cycling charge buildup.This work describes the development of naphthalene bisimide hole-injection e-barrier layer compositions that can be both coated thick and uniform, and thermally cross-linked. These coating solutions are very stable at normal coating temperature and suitable for the dip coating process. The blocked isocyanate cross-linkers are activated after coating at a temperature above 120 &#xB0;C. We have developed an offline method to study the kinetics of the cross-linking reaction using the GC headspace analysis technique for optimizing the crosslinked network.