Search

The insect Tenebrio molitorexhibits ultrafast efficiency in biodegrading polystyrene (PS). However, the generation and fate of nanoplastics (NPs) in the intestine during plastic biodegradation remain unknown. In this study, we investigated the biodegradation of PS microplastics (MPs) mediated by T. molitorlarvae over a 4-week period and confirmed biodegradation by analyzing Δδ13C in the PS before and after biotreatment (−28.37‰ versus −24.88‰) as an effective tool. The ·OH radicals, primarily contributed by gut microbiota, and H2O2, primarily produced by the host, both increased after MP digestion. The size distribution of residual MP particles in excrements fluctuated within the micrometer ranges. PS NPs were detected in the intestine but not in the excrements. At the end of Weeks 1, 2, 3, and 4, the concentrations of PS NPs in gut tissues were 3.778, 2.505, 2.087, and 2.853 ng/lava, respectively, while PS NPs in glands were quantified at 0.636, 0.284, and 0.113 ng/lava and eventually fell below the detection limit. The PS NPs in glands remained below the detection limit at the end of Weeks 5 and 6. This indicates that initially, NPs generated in the gut entered glands, then declined gradually and eventually disappeared or possibly biodegraded after Week 4, associated with the elevated plastic-degrading capacities of T. molitorlarvae. Our findings unveil rapid synergistic MP biodegradation by the larval host and gut microbiota, as well as the fate of generated NPs, providing new insights into the risks and fate associated with NPs during invertebrate-mediated plastic biodegradation.

Gallium nitride (GaN)-on-Si technologies for advanced RF applications have been raising the attentions in semiconductor industries, which accompany with RF electrostatic discharge (ESD) reliability challenges. Both positive and negative ESD stress polarities are equally important to be investigated. Four scenarios of the positive and negative human body model (HBM) stresses on a gate-tied-to-source configuration (G S $_{\mathbf {\textit {MI}{S}-\textit {HE}\textit {MT}}}$ ) and a gate-tied-to-drain configuration (G $\text{D}_{\mathbf {\textit {MI}{S}-\textit {HE}\textit {MT}}}$ ) were conducted in GaN-on-Si MIS-HEMTs. A failure mechanism unveiled in the negative G S $_{\mathbf {\textit {MI}{S}-\textit {HE}\textit {MT}}}$ which is different from the constant-power 2DEG failure mechanism in the typical positive G S $_{\mathbf {\textit {MI}{S}-\textit {HE}\textit {MT}}}$ , was demonstrated by the measured HBM transient I-V characteristics and the subsequent DC I-V traces. The specific ON-state failure mechanism is related to the constant-voltage gate dielectric failures, resulting from a unique HBM discharge mechanism without the existence of depletion region in the 2DEG channel. This causes the degradation of the HBM failure voltages on the devices. Thus, the lower HBM failure powers are required to destroy the gate dielectric layer, as compared to the high failure powers to induce the 2DEG burnouts.

Tenebrio molitorand Tenebrio obscurus(Coleoptera: Tenebrionidae) larvae are two commercial insects that eat plant and crop residues as diets and also biodegrade synthetic plastics polyethylene (PE). We examined biodegradation of low-density PE (LDPE) foam (Mn= 28.9 kDa and Mw= 342.0 kDa) with and without respective co-diets, i.e., wheat brain (WB) or corn flour (CF), corn straw (CS), and rice straw (RS) at 4:1 (w/w), and their gut microbiome and genetic metabolic functional groups at 27.0 ± 0.5 °C after 28 days of incubation. The presence of co-diets enhanced LDPE consumption in both larvae and broad-depolymerized the ingested LDPE. The diet type shaped gut microbial diversity, potential pathways, and metabolic functions. The sequence of effectiveness of co-diets was WB or CF > CS > RS for larval development and LDPE degradation. Co-occurrence networks indicated that the larvae co-fed with LDPE displayed more complex correlations of gut microbiome than the larvae fed with single diets. The primary diet of WB or CF and crop residues CS and RS provided energy and nitrogen source to significantly enhance LDPE biodegradation with synergistic activities of the gut microbiota. For the larvae fed LDPE and LDPE plus co-diets, nitrogen fixation function was stimulated compared to normal diets and associated with LDPE biodegradation.

Biodegradation of polystyrene (PS) in mealworms (Tenebrio molitorlavae) has been identified with commercial PS foams. However, there is currently limited understanding of the influence of molecular weight (MW) on insect-mediated plastic biodegradation and the corresponding responses of mealworms. In this study, we provided the results of PS biodegradation, gut microbiome, and metabolome by feeding mealworms with high-purity PS microplastics with a wide variety of MW. Over 24 days, mealworms (50 individuals) fed with 0.20 g of PS showed decreasing removal of 74.1 ± 1.7, 64.1 ± 1.6, 64.4 ± 4.0, 73.5 ± 0.9, 60.6 ± 2.6, and 39.7 ± 4.3% for PS polymers with respective weight-average molecular weights (Mw) of 6.70, 29.17, 88.63, 192.9, 612.2, and 1346 kDa. The mealworms degraded most PS polymers viabroad depolymerization but ultrahigh-MW PS vialimited-extent depolymerization. The gut microbiome was strongly associated with biodegradation, but that with low- and medium-MW PS was significantly distinct from that with ultrahigh-MW PS. Metabolomic analysis indicated that PS biodegradation reprogrammed the metabolome and caused intestinal dysbiosis depending on MW. Our findings demonstrate that mealworms alter their gut microbiome and intestinal metabolic pathways in response to in vivobiodegradation of PS polymers of various MWs.

Insects damaging and penetrating plastic packaged materials has been reported since the 1950s. Radical innovation breakthroughs of plastic biodegradation have been initiated since the discovery of biodegradation of plastics by Tenebrio molitorlarvae in 2015 followed by Galleria mellonellain 2017. Here we review updated studies on the insect-mediated biodegradation of plastics. Plastic biodegradation by insect larvae, mainly by some species of darkling beetles (Tenebrionidae) and pyralid moths (Pyralidae) is currently a highly active and potentially transformative area of research. Over the past eight years, publications have increased explosively, including discoveries of the ability of different insect species to biodegrade plastics, biodegradation performance, and the contribution of host and microbiomes, impacts of polymer types and their physic-chemical properties, and responsible enzymes secreted by the host and gut microbes. To date, almost all major plastics including polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyurethane (PUR), and polystyrene (PS) can be biodegraded by T. molitorand ten other insect species representing the Tenebrionidae and Pyralidae families. The biodegradation processes are symbiotic reactions or performed by synergistic efforts of both host and gut-microbes to rapidly depolymerize and biodegrade plastics with hourly half-lives. The digestive ezymens and bioreagents screted by the insects play an essential role in plasatic biodegradation in certain species of Tenebrionidae and Pyralidae families. New research on the insect itself, gut microbiomes, transcriptomes, proteomes and metabolomes has evaluated the mechanisms of plastic biodegradation in insects. We conclude this review by discussing future research perspectives on insect-mediated biodegradation of plastics.

Serine carboxypeptidase-like (SCPL) proteins are a group of acyltransferase enzymes that have important roles in plant growth, development, and stress responses. Although SCPL proteins have been studied in many plants, the biological functions of SCPLgenes in grape are still unknown. In this study, 59 putative SCPL proteins were identified from the grape genome. A bioinformatics analysis, including chromosomal locations, exon/intron structures, phylogeny, cis-elements, and conserved motifs, was performed for the gene family. The phylogenetic analysis revealed that VvSCPL proteins could be classified into three groups, with the gene motifs in each group showing high similarity levels. The number of exons in the VvSCPLgenes ranged from 1 to 19, suggesting significant variations among grape SCPLgenes. The expression of the VvSCPLgenes, as assessed by RNA sequencing (RNA-seq) and quantitative real-time PCR, showed that most VvSCPLgenes responded to drought- and waterlogging-stress treatments, which indicated their roles in abiotic stress responses. The results provide useful information for further study of SCPLgenes in grape.

The detrimental effects of plastics on aquatic organisms, including those of macroplastics, microplastics, and nanoplastics, have been well established. However, knowledge on the interaction between plastics and terrestrial insects is limited. To develop effective strategies for mitigating the impact of plastic pollution on terrestrial ecosystems, it is necessary to understand the toxicity effects and influencing factors of plastic ingestion by insects. An overview of current knowledge regarding plastic ingestion by terrestrial insects is provided in this Review, and the factors influencing this interaction are identified. The pathways through which insects interact with plastics, which can lead to plastic accumulation and microplastic transfer to higher trophic levels, are also discussed using an overview and a conceptual model. The diverse impacts of plastic exposure on insects are discussed, and the challenges in existing studies, such as a limited focus on certain plastic types, are identified. Further research on standardized methods for sampling and analysis is crucial for reliable research, and long-term monitoring is essential to assess plastic trends and ecological impacts in terrestrial ecosystems. The mechanisms underlying these effects need to be uncovered, and their potential long-term consequences for insect populations and ecosystems require evaluation.

The biodegradation of polypropylene (PP), a highly persistent nonhydrolyzable polymer, by Tenebrio molitorhas been confirmed using commercial PP microplastics (MPs) (Mn26.59 and Mw187.12 kDa). This confirmation was based on the reduction of the PP mass, change in molecular weight (MW), and a positive Δδ13C in the residual PP. A MW-dependent biodegradation mechanism was investigated using five high-purity PP MPs, classified into low (0.83 and 6.20 kDa), medium (50.40 and 108.0 kDa), and high (575.0 kDa) MW categories to access the impact of MW on the depolymerization pattern and associated gene expression of gut bacteria and the larval host. The larvae can depolymerize/biodegrade PP polymers with high MW although the consumption rate and weight losses increased, and survival rates declined with increasing PP MW. This pattern is similar to observations with polystyrene (PS) and polyethylene (PE), i.e., both Mnand Mwdecreased after being fed low MW PP, while Mnand/or Mwincreased after high MW PP was fed. The gut microbiota exhibited specific bacteria associations, such as Kluyverasp. and Pediococcussp. for high MW PP degradation, Acinetobactersp. for medium MW PP, and Bacillussp. alongside three other bacteria for low MW PP metabolism. In the host transcriptome, digestive enzymes and plastic degradation-related bacterial enzymes were up-regulated after feeding on PP depending on different MWs. The T. molitorhost exhibited both defensive function and degradation capability during the biodegradation of plastics, with high MW PP showing a relatively negative impact on the larvae.

Recent discoveries indicate that several insect larvae are capable of ingesting and biodegrading plastics rapidly and symbiotically, but the ecological adaptability of the larval gut microbiome to microplastics (MPs) remains unclear. Here, we described the gut microbiome assemblage and MP biodegradation of superworms (Zophobas atratuslarvae) fed MPs of five major petroleum-based polymers (polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyethylene terephthalate) and antibiotics. The shift of molecular weight distribution, characteristic peaks of C═O, and metabolic intermediates of residual polymers in egested frass proved depolymerization and biodegradation of all MPs tested in the larval intestines, even under antibiotic suppression. Superworms showed a wide adaptation to the digestion of the five polymer MPs. Antibiotic suppression negatively influenced the survival rate and plastic depolymerization patterns. The larval gut microbiomes differed from those fed MPs and antibiotics, indicating that antibiotic supplementation substantially shaped the gut microbiome composition. The larval gut microbiomes fed MPs had higher network complexity and stability than those fed MPs and antibiotics, suggesting that the ecological robustness of the gut microbiomes ensured the functional adaptability of larvae to different MPs. In addition, Mantel’s test indicated that the gut microbiome assemblage was obviously related to the polymer type, the plastic degradability, antibiotic stress, and larval survival rate. This finding provided novel insights into the self-adaptation of the gut microbiome of superworms in response to different MPs.

As awareness of the ubiquity and magnitude of plastic pollution has increased, so has interest in the long term fate of plastics. To date, however, the fate of potentially toxic plastic additives has received comparatively little attention. In this study, we investigated the fate of the flame retardant hexabromocyclododecane (HBCD) in polystyrene (PS)-degrading mealworms and in mealworm-fed shrimp. Most of the commercial HBCD consumed by the mealworms was egested in frass within 24 h (1-log removal) with nearly a 3-log removal after 48 h. In mealworms fed PS containing high HBCD levels, only 0.27 ± 0.10%, of the ingested HBCD remained in the mealworm body tissue. This value did not increase over the course of the experiment, indicating little or no bioaccumulation. Additionally, no evidence of higher trophic level bioaccumulation or toxicity was observed when L. vannamei(Pacific whiteleg shrimp) were fed mealworm biomass grown with PS containing HBCD. Differences in shrimp survival were attributable to the fraction of mealworm biomass incorporated into the diet, not HBCD. We conclude that the environmental effects of PS ingestion need further evaluation as the generation of smaller, more contaminated particles is possible, and may contribute to toxicity at nanoscale.

As the global threat of plastic pollution has grown in scale and urgency, so have efforts to find sustainable and efficient solutions. Research conducted over the past few years has identified gut environments within insect larvae, including Tenebrio molitor(yellow mealworms), as microenvironments uniquely suited to rapid plastic biodegradation. However, there is currently limited understanding of how the insect host and its gut microbiome collaborate to create an environment conducive to plastic biodegradation. In this work, we provide evidence that T. molitorsecretes one or more emulsifying factor(s) (30–100 kDa) that mediate plastic bioavailability. We also demonstrate that the insect gut microbiome secretes factor(s) (<30 kDa) that enhance respiration on polystyrene (PS). We apply these insights to culture PS-fed gut microbiome enrichments, with elevated rates of respiration and degradation compared to the unenriched gut microbiome. Within the enrichment, we identified eight unique gut microorganisms associated with PS biodegradation including Citrobacter freundii, Serratia marcescens, and Klebsiella aerogenes. Our results demonstrate that both the mealworm itself and its gut microbiome contribute to accelerated plastic biodegradation. This work provides new insights into insect-mediated mechanisms of plastic degradation and potential strategies for cultivation of plastic-degrading microorganisms in future investigations and scale-up.

Yellow mealworms (larvae of Tenebrio molitor, Coleoptera: Tenebrionidae) have been proven to be capable of biodegrading polystyrene (PS) products. Using four geographic sources, we found that dark mealworms (larvae of Tenebrio obscurus) ate PS as well. We subsequently tested T. obscurusfrom Shandong, China for PS degradation capability. Our results demonstrated the ability for PS degradation within the gut of T. obscurusat greater rates than T. molitor. With expanded PS foam as the sole diet, the specific PS consumption rates for T. obscurusand T. molitorat similar sizes (2.0 cm, 62–64 mg per larva) were 32.44 ± 0.51 and 24.30 ± 1.34 mg 100 larvae–1d–1, respectively. After 31 days, the molecular weight (Mn) of residual PS in frass (excrement) of T. obscurusdecreased by 26.03%, remarkably higher than that of T. molitor(11.67%). Fourier transform infrared spectroscopy (FTIR) indicated formation of functional groups of intermediates and chemical modification. Thermo gravimetric analysis (TGA) suggested that T. obscuruslarvae degraded PS effectively based on the proportion of PS residue. Co-fed corn flour to T. obscurusand wheat bran to T. molitorincreased total PS consumption by 11.6% and 15.2%, respectively. Antibiotic gentamicin almost completely inhibited PS depolymerization. High-throughput sequencing revealed significant shifts in the gut microbial community in both Tenebriospecies that were associated with the PS diet and PS biodegradation, with changes in three predominant families (Enterobacteriaceae, Spiroplasmataceae, and Enterococcaceae). The results indicate that PS biodegradability may be ubiquitous within the Tenebriogenus which could provide a bioresource for plastic waste biodegradation.

Recent studies have demonstrated the ability for polystyrene (PS) degradation within the gut of mealworms (Tenebrio molitor). To determine whether plastics may be broadly susceptible to biodegradation within mealworms, we evaluated the fate of polyethylene (PE) and mixtures (PE + PS). We find that PE biodegrades at comparable rates to PS. Mass balances indicate conversion of up 49.0 ± 1.4% of the ingested PE into a putative gas fraction (CO2). The molecular weights (Mn) of egested polymer residues decreased by 40.1 ± 8.5% in PE-fed mealworms and by 12.8 ± 3.1% in PS-fed mealworms. NMR and FTIR analyses revealed chemical modifications consistent with degradation and partial oxidation of the polymer. Mixtures likewise degraded. Our results are consistent with a nonspecific degradation mechanism. Analysis of the gut microbiome by next-generation sequencing revealed two OTUs (Citrobactersp. and Kosakoniasp.) strongly associated with both PE and PS as well as OTUs unique to each plastic. Our results suggest that adaptability of the mealworm gut microbiome enables degradation of chemically dissimilar plastics.

Microplastic particles smaller than 5 mm in size are of increasing concern, especially in aquatic environments, such as the ocean. Primary source is microbeads (<1 mm) used in cosmetics and cleaning agents and fiber fragments from washing of clothes, and secondary source such as broken down plastic litter and debris. These particles are mostly made from polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET) and polyesters. They are ingested by diverse marine fauna, including zooplanktons, mussel, oyster, shrimp, fish etc. and can enter human food chains via several pathways. Strategy for control of microplastics pollution should primarily focus on source reduction and subsequently on the development of cost-effective clean up and remediation technologies. Recent research results on biodegradation of plastics have revealed a potential for microbial biodegradation and bioremediation of plastic pollutants, such as PE, PS and PET under appropriate conditions.

It remains unknown whether plastic-biodegrading macroinvertebrates generate microplastics (MPs) and nanoplastics (NPs) during the biodegradation of plastics. In this study, we utilized highly sensitive particle analyzers and pyrolyzer-gas chromatography mass spectrometry (Py-GCMS) to investigate the possibility of generating MPs and NPs in frass during the biodegradation of polystyrene (PS) and low-density polyethylene (LDPE) foams by mealworms (Tenebrio molitorlarvae). We also developed a digestive biofragmentation model to predict and unveil the fragmentation process of ingested plastics. The mealworms removed 77.3% of ingested PS and 71.1% of ingested PE over a 6-week test period. Biodegradation of both polymers was verified by the increase in the δ13C signature of residual plastics, changes in molecular weights, and the formation of new oxidative functional groups. MPs accumulated in the frass due to biofragmentation, with residual PS and PE exhibiting the maximum percentage by number at 2.75 and 7.27 μm, respectively. Nevertheless, NPs were not detected using a laser light scattering sizer with a detection limit of 10 nm and Py-GCMS analysis. The digestive biofragmentation model predicted that the ingested PS and PE were progressively size-reduced and rapidly biodegraded, indicating the shorter half-life the smaller plastic particles have. This study allayed concerns regarding the accumulation of NPs by plastic-degrading mealworms and provided critical insights into the factors controlling MP and NP generation during macroinvertebrate-mediated plastic biodegradation.

Stable isotope probing (SIP) was used to identify microbes stimulated by ethanol addition in microcosms containing two sediments collected from the bioremediation test zone at the US Department of Energy Oak Ridge site, TN, USA. One sample was highly bioreduced with ethanol while another was less reduced. Microcosms with the respective sediments were amended with 13C labeled ethanol and incubated for 7 days for SIP. Ethanol was rapidly converted to acetate within 24 h accompanied with the reduction of nitrate and sulfate. The accumulation of acetate persisted beyond the 7 d period. Aqueous U did not decline in the microcosm with the reduced sediment due to desorption of U but continuously declined in the less reduced sample. Microbial growth and concomitant 13C-DNA production was detected when ethanol was exhausted and abundant acetate had accumulated in both microcosms. This coincided with U(VI) reduction in the less reduced sample. 13C originating from ethanol was ultimately utilized for growth, either directly or indirectly, by the dominant microbial community members within 7 days of incubation. The microbial community was comprised predominantly of known denitrifiers, sulfate-reducing bacteria and iron (III) reducing bacteria including Desulfovibrio, Sphingomonas, Ferribacterium, Rhodanobacter, Geothrix, Thiobacillusand others, including the known U(VI)-reducing bacteria Acidovorax, Anaeromyxobacter, Desulfovibrio, Geobacterand Desulfosporosinus. The findings suggest that ethanol biostimulates the U(VI)-reducing microbial community by first serving as an electron donor for nitrate, sulfate, iron (III) and U(VI) reduction, and acetate which then functions as electron donor for U(VI) reduction and carbon source for microbial growth.

This paper takes a two-stage three-phase inverter as an example. The efficiency calculation method is analyzed in detail for the inverter, and the power losses calculation method is proposed for the second stage under SVPWM. A 10kW/380V inverter system is designed. The system efficiency and the power losses for every part are theoretically calculated. Finally, experiments on a 10 kW prototype are carried out to verify the calculation.

In cognitive radio networks (CRNs), improving the performance of SUs is the main aspect of present study. In this paper, we focus on the optimal access strategy to provide QoS guarantees for multi-services. The contribution of this paper is as follows. Firstly, we formulate and solve the optimal spectrum access problem with different channel reservation scheme. Secondly, we take account of buffer for handoff secondary users and propose a handoff scheme for multi-services. In addition, the computation complexity of solving the optimal channel reservation problem is simplified by a binary search. The system is analyzed using a continuous-time Markov chain model. The numerical results confirm the validity of the proposed scheme.

With the rapid development of scripting language, javascript has been widely used in the application and web development industry.One of the main disadvantages of javascript for developers of commercial applications is the ease by which customers and competitors can study, analyze, and reuse the source code . Therefore, this paper proposes a technique of javascript code obfuscation based on control flow tansformations. The experimental results prove that,its effective protect javascript source code.

Combined with practical research project, a novel discharge method using high voltage pulsed power technology was put into practice for a special kind of underground sonic source device. The sonic source guaranteed large power as well as broad and thick sonic wave. Simulation as well as field test confirmed the correctness and effectiveness of the design method.

This paper take the impeller of S series airfoil for instance, in view of the complex flow field which is in the condition for the optimum attack angle of design wind velocity with tip vortex, presents a new generating strategy of grid based on controlling gradient method which takes the non-uniform tetrahedral grid with gradient gradual change in the near blade wall flow field. The transition layer grid which is in the development from body-fitted field to the middle of the domain having relatively high density of grid contrast with the far flow field can well capture the size and location of tip vortex, and find that the decay rate of the vorticity magnitude of tip vortex of S series impeller is more quickly than the tip vortex of traditional airfoil impeller. As well as find a fraction of central vortex and tip vortex shaded into each other in the far field and Doppler effect in the downstream. Because the numerical experiment and analysis showed that through controlling gradient change of grid can get high precision of calculating results, can also get S series impeller had higher efficiency in conversion of wind energy contrast with NACA series impeller, so the generating strategy of grid is reasonable and effective.

In the last few years, cloud computing has grown from a business concept to one of the fastest growing IT industry. It is a fundamental change and represents a movement towards the intensive, large scale specialized calculation model. But as more information and organizations are moved to the cloud, more concerns about security emerge. This paper discusses security issues, requirements and challenges, and provides a Cloud Computing security framework and an ESI assessment model.

Firmware is an important part of the computer architecture, the Firmware in the process of self-test can be set through selecting specific options to adjust the boot sequence menu list, allowing the computer to select the media type to start the operating system. In this paper,through the analysis of  Firmware’s boot sequence principle, pointed out the process of implementation of the Firmware boot sequence, including the position of reading boot sequence data, get the signatures of boot sequence and other key technologies. The correctness of results of the boot sequence modification experimental has been proved.

In view of the increasingly serious software protection problem, the software protection technology based on code obfuscation is analyzed and researched, and a new software protection system, maze protection is designed and realized. With the principle of maze encryption, this program insert a large number of the complex judgments code between function entry and exit, which change the execution order, enhancing the ability of software protection. On this basis, Anti-debug techniques incorporated into the maze protection, which against the mainstream anti-debugger, increasing the advantage of high anti-reversing, tamper-proof and anti-cracking. Experimental analysis has proved that this maze protection technology was better than other virtual machine protection technologies.

This paper describes the theory and method of programming under the environment of UEFI Shell and also introduces the UDK2010.UP4 install and configuration. The program run in UEFI Shell can get EFI Boot Services through the EFI_SYSTEM_TABLE parameter, after this it can operate disk files through Simple File System Protocol and EFI File Protocol. The work in this paper mainly introduces some file operations in UEFI Shell, such as file creating, data access on a FAT file system disk through a UEFI Application (UEFI App hereafter).

This paper addresses the priority of channel selection and switch over heterogeneous spectrum in cognitive radio ad hoc networks, which is not addressed carefully in the literature, with the aid of a novel 3-D structured Markov-chain model analysis. Our analysis indicates that the performance of the capacity, the probability of collision or switch of the Secondary Users (SUs) will be improved if the new SUs select available channels to initialize a session with a proper priority of Secondary Channels (SCs). Moreover, our work indicates that the same performance improvement would be gained if the active SUs interrupted by the PUs switch their working spectrum to available secondary channels with a proper priority. Extensive numerical analysis results verify the effectiveness of the proposed models and analysis methods.

Coexistence of different wireless communiation system is a worldwide phenomenon at present. Thus how to mitigate the spurious emission interference has become an emergent point to improve the performance of communication. This paper analyzes the spurious emission interference in TD-SCDMA on POI. According to the theories of spurious emission interference and isolation, this paper constructs a platform to simulate such coexistence. Considering the characters of each system, the platform applies Monte-Carlo method to obtain desired parameters, including stray electrical level and MCL. These parameters are significant guide lines for equipments to mitigate interference.

In this paper we do some researches on the ARQ mechanism which provides the probability of involving the relay nodes into the UWB multi-hop network. The ARQ mechanism we designed combines PWMR ARQ and Relay ARQ, which can perform on both the end nodes and relay nodes. Then we make a theoretical analysis of the indoor UWB channel model and give a Finite-state Markov linker layer model. With the simulation results, we can get the conclusion that using ARQ mechanism designed in this paper significant enhances throughput, time delay and bandwidth utilization of the UWB multi-hop network.

Diamond-like carbon (DLC) films were synthesized by RF plasma enhanced chemical vapor deposition using methane as carbon source. Effect of substrate on the growth of DLC films was investigated by using four different substrate materials, silicon wafer (100), glass, flat-polished and mirror-polished alumina. The carbon films were deposited at four different self-bias voltages (-157 V, -403 V, -500 V and -590 V) by changing the plasma power under fixed flow rate and working pressure. Raman analyses indicated that DLC films were deposited on silicon and glass substrates at the self-bias -403 V ~ -590 V, and polymer-like carbon films were obtained at -157 V. For the alumina substrates, different Raman results were observed for flat-polished and mirror-polished alumina substrates. The hardness of DLC films, deposited on silicon and glass substrates at the self-bias -403 V ~ -590 V, was within 16~20 GPa using nanoindentation technique.

Rings of rabbit aorta that were both incubated in a high concentration of D-glucose and contracted submaximally by phenylephrine showed significantly decreased endothelium-dependent relaxations induced by acetylcholine. The cGMP production of aorta rings was also reduced. Treatment with endomorphins (1-1000 nmol/L) restored acetylcholineinduced relaxations of aorta rings incubated in high glucose concentrations and increased the cGMP synthesis. Moreover, this effect of endomorphins on endothelium was antagonized by naloxone, and the increase in the production of cGMP was also blocked.

Two types of mesophilic methanogenic granules (R- and F-granules) were developed on different synthetic feeds containing acetate, propionate and butyrate as major carbon sources and their metabolic properties were characterized. The metabolic activities of granules on acetate, formate and H2-CO2 were related to the feed composition used for their development. These granules performed a reversible reaction between H2 production from formate and formate synthesis from H2 plus bicarbonate. Both types of granules exhibited high activity on normal and branched volatile fatty acids with three to five carbons and low activity on ethanol and glucose. The granules performed a reversible isomerization between isobutyrate and butyrate during butyrate or isobutyrate degradation. Valerate and 2-methylbutyrate were produced and consumed during propionate-butyrate degradation. The respective apparent Km (mm) for various substrates in disrupted R- and F-granules was: acetate, 0.43 and 0.41; propionate, 0.056 and 0.038; butyrate, 0.15 and 0.19; isobutyrate, 0.12 and 0.19; valerate, 0.15 and 0.098. Both granules had an optimum temperature range from 40 to 50° C for H2-CO2 and formate utilization and 40° C for acetate, propionate and butyrate utilization and a similar optimum pH.

Two types of methanogenic granules capable of high chemical oxygen demand removal rates were developed in laboratory-scale upflow reactors at 35° C. One granule type (R-granules) had a rod-type Methanothrix-like species as the predominant species whereas the other (F-granules) had a filament-type M. soehngenii-like acetate-utilizer as the predominant species. These two types of granules were compared in terms of operational performance, physical-chemical characteristics and microbial population. The R-granules had a higher density [65–70 vs 39–43 g suspended solids (SS)/l], specific gravity (1.03 vs 1.01) and specific volumetric methane production rate (180 vs 120 l CH4/l granules per day) than the F-granules. Acetate, propionate and butyrate degraders in both types of granules had similar specific growth rates. The most probable number enumeration indicated that both types of granule had the same population levels (cells/g SS) in terms of methanogens (H2-CO2-, formate- and acetate-utilizing) and syntrophic acetogens. Hydrolytic-fermentative bacteria were present in greater number in the F-granules than in the R-granules. The R-granules had a higher cell density than the F-granules. The differences in operational performance were due mainly to their different microbial composition, especially the predominant acetate-utilizing methanogens in the granules. The long-filamentous M. soehngenii-like rods in the F-granules appeared to be responsible for their lower density and large-sized granules.

The microbial species composition of methanogenic granules developed on an acetate-propionate-butyrate mixture was characterized. The granules contained high numbers of adhesive methanogens (1012/g dry weight) and butyrate-, isobutyrate-, and propionate-degrading syntrophic acetogens (1011/g dry weight), but low numbers of hydrolytic-fermentative bacteria (109/g dry weight). Prevalent methanogens in the granules included: Methanobacterium formicicum strain T1N and RF, Methanosarcina mazei strain T18, Methanospirillum hungatei strain BD, and a non-filamentous, bamboo-shaped rod species, Methanothrix/Methanosaeta-like strain M7. Prevalent syntrophic acetogens included: a butyrate-degrading Syntrophospora bryantii-like strain BH, a butyrate-isobutyrate degrading non-spore-forming rod, strain IB, a propionate-degrading sporeforming oval-shaped species, strain PT, and a propionate-degrading none-spore-forming sulfate-reducing rod species, strain PW, which was able to grow syntrophically with an H2-utilizing methanogen. Sulfate-reducing bacteria did not play a significant role in the metabolism of H2, formate, acetate and butyrate but they were involved in propionate degradation.

Accumulation of formate to millimolar levels was observed during the growth of Methanobacterium formicicum species on H2-CO2. Hydrogen was also produced during formate metabolism by M. formicicum. The amount of formate accumulated in the medium or the amount H2 released in gas phase was influenced by the bicarbonate concentration. The formate hydrogenlyase system was constitutive but regulated by formate. When methanogenesis was inhibited by addition of 2-bromoethane sulfonate, M. formicicum synthesized formate from H2 plus HCOinf3sup-or produced H2 from formate to a steady-state level at which point the Gibbs free energy (?G') available for formate synthesis or H2 production was approximately -2 to -3 kJ/reaction. Formate conversion to methane was inhibited in the presence of high H2 pressure. The relative rates of conversion of formate and H2 were apparently controlled by the ?G' available for formate synthesis, hydrogen production, methane production from formate and methane production from H2. Results from 14C-tracer tests indicated that a rapid isotopic exchange between HCOO- and HCOinf3sup-occurred during the growth of M. formicicum on H2-CO2. Data from metabolism of 14C-labelled formate to methane suggested that formate was initially split to H2 and HCOinf3sup-and then subsequently converted to methane. When molybdate was replaced with tungstate in the growth media, the growth of M. formicicum strain MF on H2-CO2 was inhibited although production of methane was not Formate synthesis from H2 was also inhibited.

Microplastics (MPs) are drawing increasing attention from the international community due to their potential threats to the ecosystem and human health. Although their occurrence and spatial distribution have been extensively studied in recent years, the relationship between their abundance and sizes remains unclear. Moreover, the underlying mechanisms dominating their size distribution have rarely been explored. In the present study, we developed a novel conditional fragmentation model to describe MP size distribution in the soil environment. It is proposed that the distribution of MPs is not a coincidence but controlled by conditional aging. The applicability of this model was tested using data collected from different land use settings in Beijing, China. A distinct downsizing phenomenon from fibers, films, and fragments to granules is observed. Undisturbed land use types accumulated larger sized MPs with higher stability, while human interference accelerated the fragmentation of MPs. Both morphological analysis and time-of-flight secondary ion mass spectroscopy (TOF-SIMS) observations provided direct evidence for the conditional fragmentation process. Furthermore, the model has proven to be suitable for describing the size distribution of MPs from various sources (including atmospheric deposition, transportation, and agriculture) and aging processes (such as mechanical abrasion, chemical oxidation, and photochemical transformation). It is proposed that this model can be used for various purposes in MP-related studies, especially source identification, transport modeling, and risk assessment.