Layer Of Residues Research Articles

Вплив параметрів дискових сошників на передавальну здатність прорізання пожнивних решток у системі нульового обробітку ґрунту

The implementation of no-tillage seeding technology has a number of economic and environmental benefits, such as improved soil properties, reduced erosion and soil degradation, and improved time and fuel efficiency. However, the main disadvantage of these technologies is that plant residues on the surface of the soil reduce the ability of uniform germination of seeds of agricultural crops, which requires the introduction of an additional process of harvesting or cutting plant residues. Theoretical studies substantiate the dependence of the diameter of a single disc coulter on the working depth of penetration of the disc, the depth of the layer of plant residues and the angle of compression. The use of active and passive coulters, which cut the straw by sliding on the working surface of the field. Experimental studies have established that the use of four different forms of disc coulters with a diameter of 380 mm (smooth with the number of teeth n=0, groove depth Δr=0 mm; toothed n=12, Δr=15 mm; toothed n=18, Δr=10 mm; toothed n=18, Δr=20 mm), straw with natural moisture (W=10.1%) and wet winter wheat straw with moisture (W=22.3%) were best cut through. Experimental studies have confirmed the restriction of the rotation of the active disc coulter at high speeds (speed coefficient λ>1.37 and λ=1.58), which leads to a greater amount of cut straw, compared to the case of using a disc coulter with passive rotation in contact with the soil ( λ=1.0). Serrated disc coulters cut straw and crop residues more efficiently than smooth discs. Studies confirm the dependence of straw cutting ability on the moisture content of the material, where the amount of straw cut through decreases as the moisture content of the material increases. Forced rotation of a toothed disc coulter (speed coefficient λ>1.37 and λ=1.58) in untreated soil (moisture 12.9±0.4%, hardness 0.5 MPa, disc penetration depth up to 35 mm) provides 56 ,0 – 69.3% cutting of winter wheat straw of natural moisture (W=10.1%); which is significantly greater than the values obtained during free movement of the disk toothed coulter at (λ=1.0).

Paul Gauguin, “Tahitian Pastorals”: Study of Painting Materials

A study is made of Paul Gauguin’s painting “Tahitian Pastorals” painted by him in 1892–1893, during his first stay in Tahiti. The painting was carried out on canvas in the technique of oil painting. To study the stratigraphy of the layers and the pigment composition of the paint layers, the method of polarization microscopy and energy-dispersive X-ray microanalysis are used. The results of the study show that chalk from silt deposits was used as the primer. Very thin paint layers, the thickness of which varies from 10 to 30 μm, are applied in one layer on the primer. Pigments such as viridian, ultramarine, cinnabar, arsenic copper, zinc white, lead white, chalk, and barite are revealed in the paint layers. Using the method of pyrolysis-gas chromatography-mass spectrometry, it is shown that beeswax was used as a transparent coating on the surface of the painting, which penetrated into the thickness of the paint layers and the primer of the painting during its life. The conducted research allows the presence of later layers of varnish, restoration records and residues of strengthening glue over the wax coating to be determined. The results of the study of the painting “Tahitian Pastorals” are of practical importance for further study, restoration, storage and transportation in case of the exhibition of paintings in other museums of other works by Gauguin from the collection of the State Hermitage.

Assessing the effect of complex ground types on ground-dwelling arthropod movements with video monitoring: Dealing with concealed movements under a layer of plant residues.

Understanding the effect of ground types on foraging movements of ground‐dwelling arthropods is a key step to managing their spatial distribution as required for successful conservation biological control. Indeed, fine movements at the centimeter scale can strongly influence the foraging ability of pest predators. However, because radio frequency identification or harmonic tracking techniques are not yet suitable for small species and video tracking focuses on uniform and light backgrounds, foraging movements have rarely been studied in relation to ground types. We present a method to track a ground‐dwelling arthropod (the earwig Euborellia caraibea) at night, walking on two contrasted ground types: bare soil and soil partly covered with a stratum of banana plant residues allowing individuals to hide periodically. The tracking of individuals within these ground types was achieved by infrared light, tagging individuals, video treatments, and semi‐automatic cleaning of trajectories. We tested different procedures to obtain segments with identical durations to quantify speeds and sinuosities. These procedures were characterized by the junction time gap between trajectory fragments, the rediscretization time of trajectories, and whether or not to use interpolation to fill in missing points in the trajectories. Earwigs exhibited significantly slower and more sinuous movements on soil with banana plant residues than on bare soil. Long time gaps for trajectory junction, extended rediscretization times, and interpolation were complementary means to integrate concealed movements in the trajectories. The highest slowdown in plant residues was detected when the procedure could account for longer periods under the residues. These results suggest that earwigs spent a significant amount of time concealed by the residues. Additionally, the residues strongly decreased the earwigs' movement. Since the technical solutions presented in this study are inexpensive, easy to set up, and replicate, they represent valuable contributions to the emerging field of video monitoring.

Identification of corrosion products on iron artefact from Bratislava castle

Abstract Corrosion layers of an iron artefact were characterized to study long-term exposition of iron in Slovakia. The iron artefact from Bratislava castle has been coated with a strong layer of corrosion products and masonry residues. Corrosion products were characterized by different methods including energy-dispersive X-ray spectroscopy (EDX), X-Ray diffraction (XRD), and µ-Raman Spectroscopy. Magnetite and goethite on the surface are confirmed typical corrosion products from long-term atmospheric exposure in environment with corrosivity category C-2 (low).

Spatial and temporal evolution of detritusphere hotspots at different soil moistures

As a result of the heterogeneous spatial distribution of microorganisms and substrates in soil and their restricted accessibility, biodegradation occurs mainly in hotspots, such as in the detritusphere, induced by decomposing plant residues. Knowing the characteristics of the volume of soil involved in biodegradation of a given organic substrate will facilitate the understanding and prediction of biodegradation. Our objectives were (i) to identify the volume of soil involved in the biodegradation of plant residues and (ii) to determine to what extent this volume is affected by soil moisture under diffusive conditions by monitoring the mineralization and spatio-temporal evolution of residue C and microorganisms in soil at the microbial habitat scale. We incubated repacked soil cores with a central layer of 13C-labelled maize residues at three different matric potentials (−0.0031, −0.031 and −0.31 MPa). We monitored 13C and total C mineralization, and at different dates over 45 days of incubation, we separated soil slices with increasing distances from the residues and analysed 13C from the residues and the microbial community structure and its activity by PLFA and 13C-PLFA processing. Residue mineralization increased with increasing soil moisture. A detritusphere a few mm thick was rapidly established, with a decreasing gradient of 13C and total PLFAs and 13C-PLFAs away from the residue layer. Most 13C from the residues was located in the first 2 mm of the detritusphere and was not dependent on the matric potential. Residue mineralization seemed to take place mainly on the residues themselves, but increasing residue C was transferred to the surrounding soil with increasing soil moisture. Dry conditions slowed residue C transfer and favoured fungi, but residue mineralization was carried out by both bacteria and fungi.

Priming of soil organic carbon induced by sugarcane residues and its biochar control the source of nitrogen for plant uptake: A dual 13C and 15N isotope three-source-partitioning study

Sugarcane (Saccharum spp.) farming systems globally have largely transitioned away from burning the crop prior to harvest. Harvesting the sugarcane crop ‘green’ results in large volumes of biomass residues being left on the soil. Despite this, there is little evidence for increased soil organic carbon stocks. We investigated the role of surface application or incorporation (0–200 mm soil layer) of harvest residues (15 t dry weight residues ha−1) and its biochar (5.4 t ha−1 based on the quantity of resource recovered after pyrolysis) on the priming of native soil organic carbon (SOC), the mineralisation of the organic amendments and the source of crop nitrogen (N) uptake (soil, organic amendment or urea). All treatments received urea at 180 kg N ha−1. To achieve the separation of C and N sources, dual 13C and 15N-enriched sugarcane residues and corresponding biochar (350 °C) were used in an 84-d controlled environment study. A three-pool isotope mixing model, utilising two levels of 13C enrichment in residue (16.6‰ and 23.8‰) and biochar (16.8‰ and 24.1‰), was also applied to partition the C from three sources: 1) root respiration, 2) organic amendment mineralisation, and 3) SOC priming. The SOC mineralisation was increased following both surface-applied and incorporated residues, over the nil organic amendment (control) by 72.3 and 78.3 CO2–C m−2 respectively over 84 days. In contrast, biochar lowered the mineralisation of SOC by 62.9 g CO2–C m−2 compared to the control. The cumulative mineralisation of sugarcane residue biochar (18.9 g CO2–C m−2) was lower (P = 0.03) than surface applied residue (50.1 g CO2–C m−2) and incorporated residue (71.9 g CO2–C m−2) over the study period. While there were no differences in total crop N uptake between the organic-amended soils and the control, the source of N was significantly different. The sugarcane plants utilised 31.0% and 29.4% of the supplied urea N in the nil organic-amended control and biochar treatment, respectively. This was significantly reduced to 24.8% and 20.6% in the surface residue and incorporated residue treatments, respectively. In comparison, the plant uptake of N derived from the organic amendments was 27.8%, 15.4% and 6.4% from incorporated residues, surface-applied residues and biochar, respectively (P < 0.001). Results suggest that the increased mineralisation of SOC, partly driven by the high C:N ratio (73:1) and the unbalanced nutrient stoichiometry may lead to low SOC accumulation from surface residue application and that sugarcane residue biochar results in SOC stabilisation and an increase in the use efficiency of fertiliser N in sugarcane systems.

Structural basis for ion selectivity in TMEM175 K+ channels.

The TMEM175 family constitutes recently discovered K+channels that are important for autophagosome turnover and lysosomal pH regulation and are associated with the early onset of Parkinson Disease. TMEM175 channels lack a P-loop selectivity filter, a hallmark of all known K+ channels, raising the question how selectivity is achieved. Here, we report the X-ray structure of a closed bacterial TMEM175 channel in complex with a nanobody fusion-protein disclosing bound K+ ions. Our analysis revealed that a highly conserved layer of threonine residues in the pore conveys a basal K+ selectivity. An additional layer comprising two serines in human TMEM175 increases selectivity further and renders this channel sensitive to 4-aminopyridine and Zn2+. Our findings suggest that large hydrophobic side chains occlude the pore, forming a physical gate, and that channel opening by iris-like motions simultaneously relocates the gate and exposes the otherwise concealed selectivity filter to the pore lumen.

Пряма сівба — no-till: агрофізична експертиза стадії переходу

The purpose. To carry out agrophysical expertise of typical superdeep low humus sandy loam chernozem of Left-bank Forest-steppe of Ukraine according to indexes of structurally-modular and humus state during the period of transition from straight sowing to no-till system. Methods. General scientific (field, morphological-genetic, comparative-analytical, agro-analytical, laboratory) and special (determination of the content of elementary soil particles and micro aggregation by S. Bulygin microscopy method). Results. It is experimentally fixed that 10-years application of straight sowing does not cause as a whole essential changes in macro structural nature of soil in comparison with moldboard plowing. However, its fertilized backgrounds increase lumpiness (index of deflationary resistance) and average diameter of water-resistant compounds (index of water-erosion resistance). Thus aggravation of micro aggregation state of soil, caused by absence of protective 3–4-cm layer of plant residues which are the precise attribute of no-till system is registered. Conclusions. Ten years’ application of straight sowing of crops on typical sandy loam chernozem leads to its deep-seated agrophysical degradation because of decrease micro-aggregation of soils and does not promote essential increase of productivity of crops. The transition period from straight sowing to no-till system should be as much as possible short (not more than 4 years). No-till system begins from the moment of formation of 3-4-cm layer of mulch on the surface of soil under condition of its 100% coatings.

An intramolecular hybrid of metal polyhedral oligomeric silsesquioxanes with special titanium-embedded cage structure and flame retardant functionality

A novel metal–organic-inorganic ternary intramolecular hybrid of N,N′-bis(methylene)-bis(dibenz[C,E][1,2]oxaphosphorin6-oxide)-propylisobutyl-amino-titanium-polyhedral oligomeric silsesquioxanes (Ti-POSS-bisDOPO) was synthesized via a feasible route including the corner-opening, corner-capping and Kabachnik-Fields reactions. The uniqueness of this compound lies in its structural design and has the function of flame retardant. Firstly, one Ti atom has been embedded into the polyhedral oligomeric silsesquioxanes (POSS) cage framework and two dibenz[C,E][1,2]oxaphosphorin6-oxide (DOPO) units with anti-burning functionality have been linked to the aminopropyl group on the corner of siliceous cage. For each molecule, the affinities of Ti-embedded POSS part and DOPO unit are different, which make Ti-POSS-bisDOPO to show the amphiphilicity. Therefore, Ti-POSS-bisDOPO could self-assemble into nanoparticle and achieve good dispersion in epoxy matrix with a particle size varying from 150 nm to 1.5 μm. Secondly, when Ti-POSS-bisDOPO was incorporated into EP matrix, the prepared EP/Ti-POSS-bisDOPO composites exhibited good comprehensive performances. Compared with pure EP, both limited oxygen index and char yield of EP/Ti-POSS-bisDOPO composites were increased greatly at a loading range of 1.5 wt%–6.0 wt%. Meanwhile, the corresponding heat release and smoke production of EP/Ti-POSS-bisDOPO were all reduced. It was observed that the interior layers of char residues were honeycomb-like multilayer structures and the exterior layers were compact, which could effectively hinder the heat transfer and gas diffusion by a barrier effect. Besides, when Ti was doped into the vertex of siliceous cage, it worked by catalyzing char formation, producing thermodynamically stable TiO2, and enhancing the flame retardancy. It was deduced that both condensed-phase and gas-phase flame-retardancy made contributions to the flame retardant mechanism. Overall, the metal-embedded and phosphorus-modified Ti-POSS-bisDOPO was a new kind of promising fire retardants in the field of non-halogen flame-retardant polymers.

Soil Mulching as an Important Element in the Strategy of Using Natural Water Resources in Agroecosystems of the Steppe Crimea

Using the earlier developed MULCH model of heat-and-water exchange in the “soil–mulch cover–vegetation cover–land-surface atmosphere layer” system, we showed that the zero (minimum) tillage technology in combination with mulching the soil surface with plant residues is the most promising method for increasing the water availability and yield of wheat in steppe regions of the Crimea. It was found that the optimal thickness of the mulching layer on rainfed fields under wheat is ~4–5 cm. It was shown that minimum tillage in combination with mulching the soil surface with a 5-cm-thick layer of plant residues increases the water availability of wheat plants (which is determined by the ratio between the actual and potential transpiration of plants) on rainfed fields in the steppe regions of Crimea by 13% on the average. The yield of wheat increases compared to the conventional tillage practice (with consideration for the increase of humus content in the soil under long-term (about 8–10 years) mulching of soil surface) by 12% (~5.3 dt/ha) on the average. The obtained results can be used in the development of methods for using natural water resources in agroecosystems of the steppe Crimea.

Утилізація деревних відходів шляхом виготовлення паливних гранул методом екструзії

Охарактеризовано специфічні особливості Покутсько-Буковинських Карпат, що визначають рівень їх екологічної безпеки. Оцінено екологічну небезпеку від неконтрольованого нагромадження деревних відходів у регіоні. Проаналізовано відомі технології гранулювання деревних відходів. Досліджено оптимальні умови сушіння деревних відходів у нерухомому шарі. Проведено експериментальні дослідження процесу сушіння відходів лісового господарства за різної висоти шару матеріалу та різної температури теплового агенту. Запропоновано спосіб екструзійного гранулювання композиції деревних відходів та в'яжучого натурального походження із отриманням паливних гранул. Показано перспективність використання сульфатного мила – в'яжучої речовини натурального походження, для покращення процесу грануляції деревних відходів. Запропоновано технологічне вдосконалення обладнання, що забезпечує рівномірний розподіл компонентів у процесі змішування в'яжучого та наповнювача в процесі гранулювання. Встановлено оптимальні умови отримання паливних гранул із деревним відходів екструзійним методом. Досліджено статистичну міцність та теплотворну здатність отриманих гранул, а також залежність між кількістю в'яжучого та концентрацією летких компонентів і коксовим залишком після спалювання гранули. Запропоновано принципову технологічну схему виробництва паливних гранул із деревних відходів екструзійним методом.

Complex-type N-glycans on VSV-G pseudotyped HIV exhibit 'tough' sialic and 'brittle' mannose self-adhesions.

The complex-type glycan shields of eukaryotic cells have a core layer of mannose residues buried under tiers of sugars that end with sialic acid (SA) residues. We investigate if the self-latching of mannose residues, earlier reported in pure monolayer studies, also manifests in the setting of a complex-type glycan shield. Would distal SA residues impede access to the mannose core? The interactions of mannobiose-, SA-, and lactose-coated probes with the complex-type VSV-G glycan shield on an HIV pseudovirus were studied with force-spectroscopy and gold-nanoparticle solutions. In force spectroscopy, the sugar probes can be forced to sample the depths of the glycan shield, whereas with sugar-coated nanoparticles, only interactions permitted by freely-diffusive contact occur. Deep-indentation mechanics was performed to verify the inferred structure of the engineered virus and to isolate the glycan shield layer for subsequent interaction studies. The adhesion between the sugar-probes and complex-type glycan shield was deconvoluted by comparing against the cross- and self- adhesions between the sugars in pure monolayers. Results from complementing systems were consistent with mannobiose-coated probes latching to the mannose core in the glycan shield, unhindered by the SA and distal sugars, with a short-range 'brittle' release of adhesion resulting in tightly coated viruses. SA-Coated probes, however, adhere to the terminal SA layer of a glycan shield with long-range and mechanically 'tough' adhesions resulting in large-scale virus aggregation. Lactose-coated probes exhibit ill-defined adherence to sialic residues. The selection and positioning of sugars within a glycan shield can influence how carbohydrate surfaces of different composition adhere.

Nitrogen in Chernozems under Traditional and Direct Seeding Cropping Systems: A Review

The functional role of nitrogen in the formation of crop yield on chernozems under conditions of traditional and direct seeding (DS) cropping systems is considered. In the course of long-term experimental studies of DS cropping system on chernozems, considerable experience has been gained and has found efficient practical application. It is shown that the effect of nitrogen as the most important element in the composition of humic substances influencing the fertility of chernozems depends on the variability of environmental factors, the forms and rates of nitrogen fertilizers, the rotation systems, and the soil treatment technologies. The DS cropping system has been tested for 4–10 years on experimental fields of the Stavropol Agricultural Research Institute and in a number of farms in Stavropol region. The obtained data on the yields of cereal crops and the application of fertilizers attest to the importance of the formation of a mulching layer of plant residues on the surface of ordinary and southern chernozems in the DS systems. This layer contributes to a gradual accumulation of nitrogen, protects the soil from erosion, and increases the number and mass of earthworms. Nitrogen in the DS cropping systems on chernozems in Russia is characterized by the high mobility and the capacity for considerable transformation. In this context, further investigations and special experiments are necessary to gain better knowledge of the behavior of nitrogen in different cropping systems. In particular, the relationships between nitrogen fluxes, agrophysical soil properties (aggregate-size distribution at the macro and micro levels), and specificity of the organic matter in different subtypes of chernozems under different cultivation technologies have to be clarified. In general, the role of DS cropping systems in farming practices has become more significant in the recent years; application of the DS cropping system is considered a positive factor in maintaining and restoring soil fertility.

Formation and Wet Removal of Organic and Titanium-Containing Residues on Patterned TiN/Porous Low-k Structure

The formation of the residues after patterning of a patterned metal hard mask/dielectric stack was characterized using surface-sensitive methods (attenuated total reflection-Fourier transform infrared spectroscopy and angle-resolved X-ray photoelectron spectroscopy) and scanning electron microscopy. The effect of a reducing plasma post-etch treatment (PET), aging, and moisture on the evolution of the residues was investigated. Both polymer-based (CFx) and metal-containing (TiFx) residues were identified on the exposed surface of the stack. Without the PET, the XPS data collected at different take-off angles suggested that the metal-containing residues were covered by a thin layer of polymer-based residues. The metal-containing residues were found to continue to evolve as a function of aging time if the layer of polymer-based residues was removed by the PET, making the metal hard mask in direct contact with cleanroom air. Exposing the MHM/dielectric stack to a 100% humidity environment did not induce further growing of the TiFx residues. Despite the PET only had limited removal of the TiFx-based residues, it was efficient in removing the polymer-based CFx residues, which in turn led to a better cleaning efficiency after the subsequent wet clean. The results in this study also confirmed that diluted HF dissolved TiFx-type residues and had no CFx removal capability. Although only two chemicals are shown as examples for post-etch residue removal, the type of test structure and methodology shown in this study can be applied for investigation and optimization of any other chemical mixture candidates for cleaning purpose.

The lysosomal potassium channel TMEM175 adopts a novel tetrameric architecture.

TMEM175 is a lysosomal K+ channel important for maintaining the lysosomal membrane potential and pH stability1. It contains two homologous copies of a six-transmembrane (6-TM) domain, which has no sequence homology to the canonical tetrameric K+ channels and lacks the TVGYG selectivity filter motif2–4. Present in a subset of bacteria and archaea, the prokaryotic TMEM175 contains only a single 6-TM domain and functions as a tetramer. Here, we present the crystal structure of a prokaryotic TMEM175 from Chamaesiphon minutus, CmTMEM175, whose architecture represents a completely different fold from that of canonical K+ channels. All six transmembrane helices of CmTMEM175 are tightly packed within each subunit without undergoing domain swap. The highly conserved TM1 acts as the pore lining inner helix, creating an hour-glass shaped ion permeation pathway in the channel tetramer. Three layers of hydrophobic residues on the C-terminal half of TM1s form a bottle neck along the ion conduction pathway and serve as the selectivity filter of the channel. Mutagenesis analysis suggests that the first layer of the highly conserved isoleucine residues in the filter plays the central role in channel selectivity. Thus, the structure of CmTMEM175 represents a novel architecture of a tetrameric cation channel whose ion selectivity mechanism appears distinct from that of the classical K+ channel family.

NMR structure of the Bacillus cereus hemolysin II C-terminal domain reveals a novel fold

In addition to multiple virulence factors, Bacillus cereus a pathogen that causes food poisoning and life-threatening wound infections, secretes the pore-forming toxin hemolysin II (HlyII). The HlyII toxin has a unique 94 amino acid C-terminal domain (HlyIIC). HlyIIC exhibits splitting of NMR resonances due to cis/trans isomerization of a single proline near the C-terminus. To overcome heterogeneity, we solved the structure of P405M-HlyIIC, a mutant that exclusively stabilizes the trans state. The NMR structure of HlyIIC reveals a novel fold, consisting of two subdomains αA-β1-β2 and β3-β4-αB-β5, that come together in a barrel-like structure. The barrel core is fastened by three layers of hydrophobic residues. The barrel end opposite the HlyIIC-core has a positively charged surface, that by binding negatively charged moieties on cellular membranes, may play a role in target-cell surface recognition or stabilization of the heptameric pore complex. In the WT domain, dynamic flexibility occurs at the N-terminus and the first α-helix that connects the HlyIIC domain to the HlyII-core structure. In the destabilizing P405M mutant, increased flexibility is evident throughout the first subdomain, suggesting that the HlyIIC structure may have arisen through gene fusion.

Toward High Carrier Mobility and Low Contact Resistance: Laser Cleaning of PMMA Residues on Graphene Surfaces.

Poly(methyl methacrylate) (PMMA) is widely used for graphene transfer and device fabrication. However, it inevitably leaves a thin layer of polymer residues after acetone rinsing and leads to dramatic degradation of device performance. How to eliminate contamination and restore clean surfaces of graphene is still highly demanded. In this paper, we present a reliable and position-controllable method to remove the polymer residues on graphene films by laser exposure. Under proper laser conditions, PMMA residues can be substantially reduced without introducing defects to the underlying graphene. Furthermore, by applying this laser cleaning technique to the channel and contacts of graphene field-effect transistors (GFETs), higher carrier mobility as well as lower contact resistance can be realized. This work opens a way for probing intrinsic properties of contaminant-free graphene and fabricating high-performance GFETs with both clean channel and intimate graphene/metal contact.Graphical Electronic supplementary materialThe online version of this article (doi:10.1007/s40820-016-0093-5) contains supplementary material, which is available to authorized users.

Influence of Polymer Residues on the Double Resonance Process of Bilayer Graphene

PMMA is commonly used for graphene transfer and device processing. However, it leaves a thin layer of polymer residues after standard acetone cleaning and causes electrical and thermal performance degradation of graphene devices. In this paper, we present a research of the impact of polymer residues on surface morphologies and electronic properties of bilayer graphene using Raman spectroscopy in combination with atomic force microscopy (AFM). The electronic structure of bilayer graphene is well captured in its Raman spectrum, of which the 2D band reveals four double resonance Raman scattering processes. The Raman analyses show universal blueshifts of the G band and the four 2D sub-bands P11, P12, P21, P22, as well as reduced intensity ratios of the sub-bands to the G band I(Pij)/I(G) after surface contamination by polymer residues, implying an electronic structure modulation in bilayer graphene. The effects are mainly attributed to p-type doping and extrinsic scattering induced by residual impurities and defects.

Resistance to forced airflow through layers of composting organic material

The objective of this study was to adjust equations to estimate the static pressure gradient of airflow through layers of organic residues submitted to two stages of biochemical degradation, and to evaluate the static pressure drop of airflow thought the material layer. Measurements of static pressure drop in the layers of sugarcane bagasse and coffee husks mixed with poultry litter on day 0 and after 30days of composting were performed using a prototype with specific airflow rates ranging from 0.02 to 0.13m3s−1m−2. Static pressure gradient and specific airflow rate data were properly fit to the Shedd, Hukill & Ives and Ergun models, which may be used to predict the static pressure gradient of air to be blown through the organic residue layers. However, the Shedd model was that which best represented the phenomenon studied. The static pressure drop of airflow increased as a power of the material layer thickness and showed tendency for decreasing with the biochemical degradation time of the organic material.

Activation of G-protein-coupled receptors correlates with the formation of a continuous internal water pathway.

Recent crystal structures of G-protein-coupled receptors (GPCRs) have revealed ordered internal water molecules, raising questions about the functional role of those waters for receptor activation that could not be answered by the static structures. Here, we used molecular dynamics simulations to monitor--at atomic and high temporal resolution--conformational changes of central importance for the activation of three prototypical GPCRs with known crystal structures: the adenosine A2A receptor, the β2-adrenergic receptor and rhodopsin. Our simulations reveal that a hydrophobic layer of amino acid residues next to the characteristic NPxxY motif forms a gate that opens to form a continuous water channel only upon receptor activation. The highly conserved tyrosine residue Y(7.53) undergoes transitions between three distinct conformations representative of inactive, G-protein activated and GPCR metastates. Additional analysis of the available GPCR crystal structures reveals general principles governing the functional roles of internal waters in GPCRs.