共查询到20条相似文献,搜索用时 15 毫秒
1.
C. A. STONE G. C. JOHNSON J. D. THORNTON B. J. MACAULEY P. W. HOLMES E. H. TAI 《Internal medicine journal》1989,19(6):727-729
Two patients were suspected of having extrinsic allergic alveolitis due to exposure to an agent in their home environment. On inspection of their houses, fungal decay was evident in the floorboards, and fungal spores were found deposited on many surfaces. The decay fungus was later identified as Leucogyrophana pinastri. Using an extract of the fruiting bodies and mycelium of this fungus, precipitating antibodies were identified in the sera of both patients. Based on the known exposure by the two patients to these small spores, the absence of a likely alternative allergen, the similarity between these two cases, and the positive precipitin test results, L pinastri was considered to be the most likely cause of extrinsic allergic alveolitis in our cases. 相似文献
2.
This paper introduces an innovative method for making cement-based composites from corn straw plants, and investigates the strength, thermal conductivity, and hydration characteristics of the composites. Corn straw is a natural, renewable, and breathable thermal insulation composite that contains cellular sealed pores. Corn straw contains a large amount of soluble cellulosic sugar, which hinders the hydration reaction of Portland cement and affects the use of corn straw as a building material. In this study, a 3 wt.% siliceous solution was used for surface treatment of corn straw particles to prevent cellulosic sugar from affecting the hydration performance of Portland cement. The composition of added cement-based composite materials with treated corn straw at the dosage of 11–20 wt.% was investigated. The test results showed that the corn straw cement-based composite (CSCC) had an optimal thermal conductivity of 0.102–0.112 (W/(m·K)) and a minimum compressive strength of above 1 MPa. The hydration performance of four typical CSCCs was examined using XRD, SEM, and EDS. The experimental results of this study may help to increase the comprehensive utilization of corn straw. The manufacturing method of the composite materials is simple, effective, and convenient for popularization and application, and it provides a new important technical measure to solve the problem of high energy consumption in rural houses. 相似文献
3.
Leong Tatt Loh Ming Kun Yew Ming Chian Yew Jing Han Beh Foo Wei Lee Siong Kang Lim Kok Zee Kwong 《Materials》2021,14(9)
Oil palm shell (OPS) is an agricultural solid waste from the extraction process of palm oil. All these wastes from industry pose serious disposal issues for the environment. This research aims to promote the replacement of conventional coarse aggregates with eco-friendly OPS aggregate which offers several advantages, such as being lightweight, renewable, and domestically available. This paper evaluates the mechanical and thermal performances of renewable OPS lightweight concrete (LWC) reinforced with various type of synthetic polypropylene (SPP) fibers. Monofilament polypropylene (MPS) and barchip polypropylene straight (BPS) were added to concrete at different volume fractions (singly and hybrid) of 0%, 0.1%, 0.3% and 0.4%. All specimens were mixed by using a new mixing method with a time saving of up to 14.3% compared to conventional mixing methods. The effects of SPP fibers on the mechanical properties were investigated by compressive strength, splitting tensile strength and residual strength. The strength of the oil palm shell lightweight concrete hybrid 0.4% (OPSLWC–HYB–0.4%) mixture achieved the highest compressive strength of 29 MPa at 28 days. The inclusion of 0.3% of BPS showed a positive outcome with the lowest thermal conductivity value at 0.55 W/m °C. Therefore, the results revealed that incorporation of BPS fiber enhanced the performance of thermal conductivity tests as compared to inclusion of MPS fiber. Hence, renewable OPS LWC was proven to be a highly recommended environmentally friendly aggregate as an alternative solution to replace natural aggregates used in the concrete industry. 相似文献
4.
Majka Odalanowska Magdalena Wo
niak Izabela Ratajczak Daria Zieliska Grzegorz Cofta Sawomir Borysiak 《Materials》2021,14(2)
The article presents characteristics of wood/polypropylene composites, where the wood was treated with propolis extract (EEP) and innovative propolis-silane formulations. Special interest in propolis for wood impregnation is due to its antimicrobial properties. One propolis-silane formulation (EEP-TEOS/VTMOS) consisted of EEP, tetraethyl orthosilicate (TEOS), and vinyltrimethoxysilane (VTMOS), while the other (EEP-TEOS/OTEOS) contained EEP, tetraethyl orthosilicate (TEOS), and octyltriethoxysilane (OTEOS). The treated wood fillers were characterized by Fourier transform infrared spectroscopy (FTIR), atomic absorption spectrometry (AAS), and X-ray diffraction (XRD), while the composites were investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD), and optical microscopy. The wood treated with EEP and propolis-silane formulations showed resistance against moulds, including Aspergillus niger, Chaetomium globosum, and Trichoderma viride. The chemical analyses confirmed presence of silanes and constituents of propolis in wood structure. In addition, treatment of wood with the propolis-silane formulations produced significant changes in nucleating abilities of wood in the polypropylene matrix, which was confirmed by an increase in crystallization temperature and crystal conversion, as well as a decrease in half-time of crystallization parameters compared to the untreated polymer matrix. In all the composites, the formation of a transcrystalline layer was observed, with the greatest rate recorded for the composite with the filler treated with EEP-TEOS/OTEOS. Moreover, impregnation of wood with propolis-silane formulations resulted in a considerable improvement of strength properties in the produced composites. A dependence was found between changes in the polymorphic structures of the polypropylene matrix and strength properties of composite materials. It needs to be stressed that to date literature sources have not reported on treatment of wood fillers using bifunctional modifiers providing a simultaneous effect of compatibility in the polymer-filler system or any protective effect against fungi. 相似文献
5.
Modification of Laser Marking Ability and Properties of Polypropylene Using Silica Waste as a Filler
Polypropylene (PP) belongs to the group of polymers characterized by low susceptibility to absorption of electromagnetic radiation in the infrared range (λ = 1064 nm). This research consisted of assessing the possibility of using silica waste from the metallurgic industry as an additive for PP laser marking. The modifier was introduced into the polymer matrix in the range from 1 to 10 wt%. The effects of laser radiation were assessed based on colorimetric tests and microscopic surface analysis. The mechanical properties of the composites were determined during the static tensile tests. The thermal properties were investigated via differential scanning calorimetry. It was found that the introduction of silica waste into polypropylene allows for the effective marking of sample surfaces with the use of a laser beam. The greatest contrast between the graphic symbol and the background was obtained for silica contents of 3 and 5 wt%, with the use of a low-speed laser head and a strong concentration of the laser beam. The application of silica caused an increase in the modulus of elasticity and the tensile strength of the composite samples. Increases in the crystallization temperature and the degree of crystallinity of the polymer matrix were also observed. It was found that silica waste can act as multifunctional additive for polypropylene. 相似文献
6.
Przemysaw Bartczak Julia Stachowiak Marta Szmitko Aleksandra Grzbka-Zasadziska Sawomir Borysiak 《Materials》2023,16(1)
Currently, the fundamental activity that will allow for the development of an economy with closed circulation is the management of food waste and production waste for the preparation of biocomposites. The use of waste materials of natural origin allows for the creation of innovative composites with improved physicochemical and functional properties. The present investigation concerns the use of coffee grounds (2.5–20 wt.%) and oak sawdust (2.5–20 wt.%) as effective fillers of rigid polyurethane foam. Innovative composite materials, previously indebted in the literature, were subjected to the necessary analyses to determine the application abilities: processing times, free density, water absorption, dimensional stability, mechanical properties (compressive strength), thermal conductivity, morphology, and flame resistance. The results with respect to the mechanical tests turned out to be the key. Increasing the number of coffee additives has a positive effect on the compressive strength. The addition of this filler in the range of 5–15 wt.% increased the compressive strength of the composites, 136–139 kPa, compared to the reference sample, 127 kPa. The key parameter analysed was thermal conductivity. The results obtained were in range of the requirements, that is, 0.022–0.024 W/m·K for all used amounts of fillers 2.5–20 wt.%. This is extremely important since these materials are used for insulation purposes. The results of the burning-behaviour test have confirmed that the addition of renewable materials does not negatively affect the fire resistance of the received foams; the results were obtained analogously to those obtained from the reference sample without the addition of fillers. The height of the flame did not exceed 17 cm, while the flame decay time was 17 s for the reference sample and the composite with coffee grounds and 18 s for the composite with oak sawdust. In this work, the practical application of bioorganic waste as an innovative filler for the insulation of flooded polyurethane foam is described for the first time. The introduction of fillers of natural origin into the polymer matrix is a promising method to improve the physicochemical and functional properties of rigid polyurethane foams. Composites modified with coffee grounds and sawdust are interesting from a technological, ecological, and economic point of view, significantly increasing the range of use of foam in various industries. 相似文献
7.
Silicon-based ceramic aerogels obtained by the polymer pyrolysis route possess excellent thermophysical properties, but their poor mechanical properties limit their broader applicability in thermal insulation materials. Herein, SiCN(O) ceramic aerogels were prepared under the toughening effect of a crosslinker (hexamethylene diisocyanate, HDI), which maintains the structural integrity of the aerogel during the wet gel-to-aerogel conversion. The aerogel maintained a high surface area (88.6 m2 g−1) and large pore volume (0.21 cm3 g−1) after pyrolysis. Based on this, mullite-fiber-reinforced SiCN(O) aerogels composites with outstanding thermal insulation properties and better mechanical performance were synthesized via ambient pressure impregnation. Furthermore, the effect of the impregnation concentration on the mechanical and insulation properties of the composites was investigated. The results revealed that the composite prepared with a solution ratio of 95 wt.% exhibited a low density (0.11 g cm−3) and a low thermal conductivity (0.035 W m−1 K−1), indicating an ~30% enhancement in its thermal insulation performance compared to the mullite fiber; the mesoporous aerogel structures wrapped on the mullite fibers inhibited the gas thermal conduction inside the composites. 相似文献
8.
Crop residue burning is one of the major sources of particulate matter (PM) in the air. The burning behaviors and PM emissions of the three typical crop residues (rice straw, wheat straw, corn straw) in China were characterized by a cone calorimeter (CONE) coupled with a laser dust meter. The water-soluble compounds, carbonaceous content, and morphology of PM were measured by ion chromatography, elemental analyzer, transmission electron microscopy (TEM) and energy-dispersive X-ray spectrometer (EDS). The results showed that thermal stability of corn straw was the worst among the three crop straws. The heat release rate (HRR) curves of the three crop straws were the typical curves of thermally thick charring (residue forming) samples. Wheat straw had the highest smoke yield, which was 2.9 times that of rice straw. The PM emission factor of wheat straw was 180.91 µg/g, which was about three times that of rice straw. The contents of K+, Na+, and Cl− in PM were significantly higher than those of the other six water-soluble inorganic ions. The ratio of organic carbon and elemental carbon (OC/EC) ranged from 14.82 to 30.82, which was similar to the results of open burning. There were mainly three kinds of aggregates in the PM of crop straws: network, chain-like, and soot. Individual particles were mixtures of KCl and organic matters. Core-shell structures were found in PM of rice straw and corn straw. The results in this study were provided based on CONE, an ISO-standard apparatus, which could avoid data conflicts caused by the difference of combustion devices. The relationship between the burning behavior and PM emission characteristics of crop straws was established, which is helpful to understand emissions of crop straws and to find a novel way to solve the problems from the burning of crop residues. 相似文献
9.
Oana Gherasim Roxana Cristina Popescu Valentina Grumezescu George Dan Mogoanu Laureniu Mogoant Florin Iordache Alina Maria Holban Bogdan tefan Vasile Alexandra Ctlina Bîrc Ovidiu-Cristian Oprea Alexandru Mihai Grumezescu Ecaterina Andronescu 《Materials》2021,14(7)
The present study reports on the development and evaluation of nanostructured composite coatings of polylactic acid (PLA) embedded with iron oxide nanoparticles (Fe3O4) modified with Eucalyptus (Eucalyptus globulus) essential oil. The co-precipitation method was employed to synthesize the magnetite particles conjugated with Eucalyptus natural antibiotic (Fe3O4@EG), while their composition and microstructure were investigated using grazing incidence X-ray diffraction (GIXRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The matrix-assisted pulsed laser evaporation (MAPLE) technique was further employed to obtain PLA/Fe3O4@EG thin films. Optimal experimental conditions for laser processing were established by complementary infrared microscopy (IRM) and scanning electron microscopy (SEM) investigations. The in vitro biocompatibility with eukaryote cells was proven using mesenchymal stem cells, while the anti-biofilm efficiency of composite PLA/Fe3O4@EG coatings was assessed against Gram-negative and Gram-positive pathogens. 相似文献
10.
AIM: A novel ex vivo model for the study of adherence and invasion of dermatophytes to the stratum corneum was developed. MATERIALS AND METHODS: A skin of full epidermis thickness was infected by spores of Trichophyton mentagrophytes and examined after various periods of time by scanning and transmission electron microscopy. RESULTS: After 12 h of inoculation a tenacious adherence between the spores and the stratum corneum was observed. There was a time dependent increase in the number of spores adhered to this surface. By 24 h, germination had commenced. The initial growth of germ tubes occurred extracellularly to the corneocytes. Three days after inoculation, the most prominent feature was proliferation of fungal hyphae and penetration of mycelium through the outer keratinocyte layer which is followed by invasion of the outer stratum corneum. CONCLUSION: The model introduced in the present study may contribute to a better understanding of the nature of the interaction between dermatophytes and skin cells in dermatophytosis process. 相似文献
11.
Paulina Jakubowska Grzegorz Borkowski Dariusz Brzkalski Bogna Sztorch Arkadiusz Kloziski Robert E. Przekop 《Materials》2022,15(1)
This paper presents the impact of accelerated aging on selected mechanical and thermal properties of isotactic polypropylene (iPP) composites filled with sedimentary hybrid natural filler-Opoka rock. The filler was used in two forms: an industrial raw material originating as a subsieve fraction natural material, and a rock calcinated at 1000 °C for production of phosphorous sorbents. Fillers were incorporated with constant amount of 5 wt % of the resulting composite, and the material was subjected to accelerated weathering tests with different exposition times. The neat polypropylene and composites with calcium carbonate as a reference filler material were used for comparison. The aim of the research was to determine the possibility of using the Opoka rock as a new hybrid filler for polypropylene, which could be an alternative to the widely used calcium carbonate and silica. The thermal, mechanical, and structural properties were evaluated by means of differential scanning calorimetry (DSC), tensile tests, scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR/ATR) prior to and after accelerated aging. As a result, it was found that the composites of polypropylene with Opoka were characterized by similar or higher functional properties and higher resistance to photodegradation compared to composites with conventional calcium carbonate. The results of measurements of mechanical properties, structural and surface changes, and the carbonyl index as a function of accelerated aging proved that Opoka was an effective ultraviolet (UV) stabilizer, significantly exceeding the reference calcium carbonate in this respect. The new hybrid filler of natural origin in the form of Opoka can therefore be used not only as a typical powder filler, but above all as a UV blocker/stabilizer, thus extending the life of polypropylene composites, especially for outdoor applications. 相似文献
12.
Jií Teslík 《Materials》2021,14(15)
Sustainable development in civil engineering is the clear and necessary goal of the current generation. There are many possibilities for reducing the use of depletable resources. One of them is to use renewable and recyclable materials on a larger scale in the construction industry. One possibility is the application of natural thermal insulators. A typical example is a crushed straw, which is generated as agricultural waste in the Czech Republic. Due to its small dimensions and good thermal insulation parameters, this material can also be used as blown thermal insulation. The research aims to examine the fire resistance of crushed straw as blown insulation. The single-flame source fire test results, thermal attack by a single burning item (SBI) test and large-scale test of a perimeter wall segment are shown. The results show that blown insulation made of crushed straw meets the requirements of fire protection. In addition, crushed straw can be also used to protect load-bearing structures due to its behaviour. This article also shows the production process of crushed straw used as blown insulation in brief. 相似文献
13.
Abhishek Sadananda Madival Deepak Doreswamy Shripathi Adiga Handady Krishna Raghava Hebbar Shobha Karabylu Lakshminarayana 《Materials》2022,15(2)
Managing rice crop stubble is one of the major challenges witnessed in the agricultural sector. This work attempts to investigate the physical, mechanical, and liquid absorption properties of rice straw (RS)-reinforced polymer composite for assessing its suitability to use as an ayurvedic treatment table. This material is expected to be an alternative for wooden-based ayurvedic treatment tables. The results showed that the addition of rice straw particles (RSp) up to 60% volume in epoxy reduced the density of the composite material by 46.20% and the hardness by 15.69%. The maximum tensile and flexural strength of the RSp composite was 17.53 MPa and 43.23 MPa, respectively. The scanning electron microscopy (SEM) analysis showed deposits of silica in the form of phytoliths in various size and shapes on the outer surface of RS. The study also revealed that the water absorption rate (WA) was less than 7.8% for the test samples with 45% volume of RSp. Interestingly the test samples showed greater resistance to the absorption of Kottakal Dhanvantaram Thailam (<2%). In addition, the developed samples showed resistance towards bacterial and fungal growth under the exposure of treatment oils and water. 相似文献
14.
Harlene Ghuman Alicia Shepherd-Roberts Stephanie Watson Malou Zuidscherwoude Steve P. Watson Kerstin Voelz 《Platelets》2019,30(2):256-263
Thrombosis is a hallmark of the fatal fungal infection mucormycosis. Yet, the platelet activation pathway in response to mucormycetes is unknown. In this study we determined the platelet aggregation potential of Mucor circinelloides (M. circinelloides) NRRL3631, characterized the signaling pathway facilitating aggregation in response to fungal spores, and identified the influence of the spore developmental stage upon platelet aggregation potential. Using impedance and light-transmission aggregometry, we showed that M. circinelloides induced platelet aggregation in whole blood and in platelet-rich plasma, respectively. The formation of large spore-platelet aggregates was confirmed by light-sheet microscopy, which showed spores dispersed throughout the aggregate. Aggregation potential was dependent on the spore’s developmental stage, with the strongest platelet aggregation by spores in mid-germination. Inhibitor studies revealed platelet aggregation was mediated by the low affinity IgG receptor FcγRIIA and integrin αIIbβ3; Src and Syk tyrosine kinase signaling; and the secondary mediators TxA2 and ADP. Flow cytometry of antibody stained platelets showed that interaction with spores increased expression of platelet surface integrin αIIbβ3 and the platelet activation marker CD62P. Together, this is the first elucidation of the signaling pathways underlying thrombosis formation during a fungal infection, highlighting targets for therapeutic intervention. 相似文献
15.
Ranit Mukherjee Hope A. Gruszewski Landon T. Bilyeu David G. Schmale III Jonathan B. Boreyko 《Proceedings of the National Academy of Sciences of the United States of America》2021,118(34)
Plant pathogens are responsible for the annual yield loss of crops worldwide and pose a significant threat to global food security. A necessary prelude to many plant disease epidemics is the short-range dispersal of spores, which may generate several disease foci within a field. New information is needed on the mechanisms of plant pathogen spread within and among susceptible plants. Here, we show that self-propelled jumping dew droplets, working synergistically with low wind flow, can propel spores of a fungal plant pathogen (wheat leaf rust) beyond the quiescent boundary layer and disperse them onto neighboring leaves downwind. An array of horizontal water-sensitive papers was used to mimic healthy wheat leaves and showed that up to 25 spores/h may be deposited on a single leaf downwind of the infected leaf during a single dew cycle. These findings reveal that a single dew cycle can disperse copious numbers of fungal spores to other wheat plants, even in the absence of rain splash or strong gusts of wind.Spores of plant pathogenic fungi are spread through the atmosphere in three stages: liberation from the host by some active or passive method(s), drift by biotic or abiotic factors, and deposition onto a new host (1). Examples of active liberation mechanisms include osmotic pressure–driven ejection of ascospores of Fusarium graminearum (the causal agent of Fusarium head blight of wheat) and ballistospore ejection from the tip of a sterigma due to the chemical secretion of a Buller’s drop (2, 3). In the absence of wind, the resulting dispersal distance is a function of both the weight of the spore(s) and the initial discharge velocity, with the range of discharge varying from 40 m for basidiospores (4) to 6 m for the artillery fungus (5). Passive liberation and dispersal mechanisms, such as wind and rain splash, can spread fungal diseases in plants (6). For wind to successfully liberate dry spores, an unusually strong and/or sudden gust of wind is often required (1, 6–9). In contrast, rain splash can liberate spores from a plant either through transferring momentum to the leaf to launch spores off (10, 11) or by adhering spores to splashed satellite droplets (12, 13). Spores ejected by active methods or rain splash can only disperse over a very short distance in the absence of wind (14) but when carried in moderate winds, can travel for many kilometers (15, 16).One recent study reported an entirely new mode of pathogen liberation, where coalescing dew droplets on superhydrophobic wheat leaves jump with considerable velocity (0.1 to 1.0 m/s) and carry adhered spores of a fungal plant pathogen (17). Mechanistically, the out-of-plane motion is a result of symmetry breaking as the expanding liquid bridge during coalescence impinges upon the bottom substrate (18–20) (Fig. 1A). While this initial report characterized the jumping-droplet liberation of spores in the absence of wind (17), it did not consider the subsequent dispersal or deposition, which ultimately governs the rate of disease spread. Here, we characterize the dispersal of spores of leaf rust (Puccinia triticina) after they are liberated from a diseased wheat leaf via jumping-droplet condensation. Two different scenarios are explored: short-range and long-range drift and deposition in the absence and presence of wind flow, respectively (Fig. 1 B and C). We found that even a low wind speed (0.5 m/s) is capable of dispersing as many as 100 jumping droplets and 25 spores to a single leaf downwind of a diseased leaf saturated in dew. Our ability to quantify both the liberation and dispersal of fungal spores from a diseased leaf during a dew cycle improves our understanding of disease spread within and among plants (1, 21–23).Open in a separate windowFig. 1.Spore dispersal via jumping-droplet condensation. (A) Jumping-droplet condensation on a healthy wheat leaf. Two condensed droplets coalesce (second frame) and jump off from the superhydrophobic wheat leaf (third frame). (B) Without any wind, the jumped droplets with spores can land on an adjacent healthy leaf, spreading the disease within the plant. (C) In low (0.5 m/s) to moderate (1.5 m/s) wind speed, the spore-laden jumped droplets can travel long-range to land on different healthy plants within the field. 相似文献
16.
The public pressure about the problems derived from the environmental issues increasingly pushes the research areas, of both industrial and academic sectors, to design material architectures with more and more foundations and reinforcements derived from renewable sources. In these efforts, researchers make extensive and profound use of thermal analysis. Among the different techniques available, thermal analysis offers, in addition to high accuracy in the measurement, smartness of execution, allowing to obtain with a very limited quantity of material precious information regarding the property–structure correlation, essential not only in the production process, but overall, in the design one. Thus, techniques such as differential scanning calorimetry (DSC), differential thermal analysis (DTA), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were, are, and will be used in this transition from fossil feedstock to renewable ones, and in the development on new manufacturing processes such as those of additive manufacturing (AM). In this review, we report the state of the art of the last two years, as regards the use of thermal techniques in biopolymer design, polymer recycling, and the preparation of recyclable polymers as well as potential tools for biopolymer design in AM. For each study, we highlight how the most known thermal parameters, namely glass transition temperature (Tg), melting temperature (Tf), crystallization temperature (Tc) and percentage (%c), initial decomposition temperature (Ti), temperature at maximum mass loss rate (Tm), and tan δ, helped the researchers in understanding the characteristics of the investigated materials and the right way to the best design and preparation. 相似文献
17.
Andreea Hegyi Horaiu Vermean Adrian-Victor Lzrescu Cristian Petcu Cezar Bulacu 《Materials》2022,15(4)
The current context provides, worldwide, the need to identify solutions for the thermal efficiency of constructions, through sustainable and innovative methods and products. A viable solution is to produce thermal insulating products by carding-folding technology, using natural fibres and recycled polyethylene terephthalate (rPET) and polyester (rPES) waste, converted to fibres. This paper presents experimental results obtained after testing several thermal insulation composite products produced using a mix of sheep wool, cellulose, rPET and rPES fibres. The results of the research demonstrate the thermal insulation properties but, at the same time, identify the benefits of using such materials on the quality of the air in the interior space (the ability to adjust humidity and reduce the concentration of harmful substances). At the same time, the advantages of using sheep wool composite mattresses concerning their resistance to insect attack is demonstrated when compared with ordinary thermal insulation materials. Finally, sensitivity elements of these composites are observed in terms of sensitivity to mould, and to contact with water or soil, drawing future research directions in the development of this type of materials. 相似文献
18.
AIM: To identify factors related to serious postoperative bacterial and fungal infections in the first 3 mo after living donor liver transplantation (LDLT).METHODS: In the present study, the data of 207 patients from 2004 to 2011 were reviewed. The pre-, intra- and post-operative factors were statistically analyzed. All transplantations were approved by the ethics committee of West China Hospital, Sichuan University. Patients with definitely preoperative infections and infections within 48 h after transplantation were excluded from current study. All potential risk factors were analyzed using univariate analyses. Factors significant at a P < 0.10 in the univariate analyses were involved in the multivariate analyses. The diagnostic accuracy of the identified risk factors was evaluated using receiver operating curve.RESULTS: The serious bacterial and fungal infection rates were 14.01% and 4.35% respectively. Enterococcus faecium was the predominant bacterial pathogen, whereas Candida albicans was the most common fungal pathogen. Lung was the most common infection site for both bacterial and fungal infections. Recipient age older than 45 years, preoperative hyponatremia, intensive care unit stay longer than 9 d, postoperative bile leak and severe hyperglycemia were independent risk factors for postoperative bacterial infection. Massive red blood cells transfusion and postoperative bacterial infection may be related to postoperative fungal infection.CONCLUSION: Predictive risk factors for bacterial and fungal infections were indentified in current study. Pre-, intra- and post-operative factors can cause postoperative bacterial and fungal infections after LDLT. 相似文献
19.
Van Laere A Van Schaftingen E Hers HG 《Proceedings of the National Academy of Sciences of the United States of America》1983,80(21):6601-6605
Induction of germination of Phycomyces blakesleeanus spores by a heat shock and subsequent incubation at 25°C in a glucose- or 6-deoxyglucose-containing culture medium resulted in an intense (20-40 times the initial value) rise in the concentration of fructose 2,6-bisphosphate and hexose 6-phosphates. The increase in the concentration of fructose 2,6-bisphosphate but not that of hexose 6-phosphates was restricted to a 25-min period during which the spores acquired an irreversible capacity to germinate. Incubation of the spores in water for any period of time during this critical period resulted in a parallel decrease in their ability to form hexose phosphates and to germinate. A similar rise in hexose phosphate concentration was also observed when P. blakesleeanus spores were activated by incubation in the presence of acetate and also after induction of germination of other dormant (Neurospora tetrasperma) or nondormant (Mucor racemosus) fungal spores. Extracts of dormant and heat-activated P. blakesleeanus spores contain a fructose, 1,6-bisphosphatase that is inhibited by fructose 2,6-bisphosphate and AMP in a synergistic manner. They also contain a 6-phosphofructo-2-kinase and a fructose-2,6-bisphosphatase. 相似文献
20.
An analytic-empirical model was developed to describe the heat transfer process in raw straw bulks based on laboratory experiments for calculating the thermal performance of straw-based walls and thermal insulations. During the tests, two different types of straw were investigated. The first was barley, which we used to compose our model and identify the influencing model parameters, and the second was wheat straw, which was used only for validation. Both straws were tested in their raw, natural bulks without any modification except drying. We tested the thermal conductivity of the materials in a bulk density range between 80 and 180 kg/m3 as well as the stem density, material density, cellulose content, and porosity. The proposed model considers the raw straw stems as natural composites that contain different solids and gas phases that are connected in parallel to each other. We identified and separated the following thermal conductivity factors: solid conduction, gas conduction in stem bulks with conduction factors for pore gas, void gas, and gaps among stems, as well as radiation. These factors are affected by the type of straw and their bulk density. Therefore, we introduced empirical flatness and reverse flatness factors to our model, describing the relationship between heat conduction in stems and voids to bulk density using the geometric parameters of undisturbed and compressed stems. After the validation, our model achieved good agreement with the measured thermal conductivities. As an additional outcome of our research, the optimal bulk densities of two different straw types were found to be similar at 120 kg/m3. 相似文献