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As a rapidly developing additive manufacturing technology, fused deposition modeling (FDM) has become widespread in many industry fields. It can fabricate complicated geometries using filament of thermoplastic materials such as PP, polylactic acid, acrylonitrile butadiene styrene, etc. However, poor mechanical properties of raw materials limit their application. Poly-ether-ether-ketone is a type of special engineering plastic with high performance, which could be further reinforced by adding carbon fibers (CFs). During FDM process, the mechanical properties of printed parts are largely subject to careful selection of process parameters. To improve the mechanical properties of PEEK and CF/PEEK 3D-printed parts, the effects of various process parameters including building orientation, raster angle, nozzle temperature, platform temperature, ambient temperature, printing speed, layer thickness, infill density, and number of printed parts on mechanical properties were investigated. The tensile fracture interfaces of printed parts were observed by scanning electron microscope (SEM) to explain the influence mechanism of process parameters. In the single factor experiments, flat and on-edge specimens show the best tensile and flexural strength, respectively; the specimens with raster angle ±45° and 0° show the best tensile and flexural strength, respectively. When the nozzle temperature at 500°C, platform temperature at 200°C, ambient temperature at 150°C, printing speed is 20 mm/s, layer thickness is 0.2 mm, and infill density is 100%, the printed parts exhibit the best mechanical properties.

The central carbon (C) metabolic network harvests energy to power the cell and feed biosynthesis for growth. In pure cultures, bacteria use some but not all of the network’s major pathways, such as glycolysis and pentose phosphate and Entner-Doudoroff pathways. However, how these pathways are used in microorganisms in intact soil communities is unknown. Here, we analyzed the incorporation of 13 C from glucose isotopomers into phospholipid fatty acids. We showed that groups of Gram-positive and Gram-negative bacteria in an intact agricultural soil used different pathways to metabolize glucose. They also differed in C use efficiency (CUE), the efficiency with which a substrate is used for biosynthesis. Our results provide experimental evidence for diversity among microbes in the organization of their central carbon metabolic network and CUE under in situ conditions. These results have important implications for our understanding of how community composition affects soil C cycling and organic matter formation.

When multiple metabolic pathways lead to the same product, compound-specific isotope analysis may not provide enough information to quantify the activities of the contributing pathways. Instead, identification of where in the molecule the 13C is incorporated is required. Here we show how knowledge of position-specific 13C incorporation in fatty acids (FA) and FA fragments can be used to quantitatively estimate the fluxes through the central C metabolic network. We developed a method to measure 13C enrichment of FA and FA fragments (ethanoate, propionate) using electron impact GC–MS. We tested the accuracy and repeatability of the measurements using natural abundance and position-specific 13C labelled standards and FA extracted from Bacillus licheniformis and Pseudomonas fluorescens grown with labelled and unlabelled glucose. The molecular ions of FA generally reflected theoretical predictions of mass isotopomer distributions for natural abundance values, but that of the associated FA fragments deviated from expected values, likely associated with McLafferty rearrangements of hydrogen. After correction for naturally occurring isotopes, 13C enrichments of FA and FA fragments showed good agreement with expected isotope composition of FA standards (root mean square error The ratio of glucose-1-13C to glucose-3-13C incorporation into FA fragments was high for B. licheniformis, but low for P. fluorescens. Metabolic flux modelling based on the 13C enrichment of ethanoate and propionate fragments showed that B. licheniformis used Embden-Meyerhof-Parnas and pentose phosphate pathway (66% and 30%, respectively), whereas P. fluorescens utilized Entner-Doudoroff and pentose phosphate pathway (72% and 27%, respectively). FA fragment analysis is therefore a promising tool to study central C metabolic network activities of co-occurring groups of microbes in intact and complex environmental communities.

The distributed control plane of Software-Defined Networks improves the scalability of the control plane and enables to dynamically assign switches to controllers. However, existing works calculate the assignment mainly based on the number of flow path setup requests generated from the switches and neglect the different resource demand of the requests on the controllers. To address this problem, we analyze the controller resource demands of the requests of different paths and formulate a flow path-aware switch assignment problem to minimize the controller resource demand. To efficiently solve the problem, we propose a heuristic algorithm which is inspired by the rearrangement inequality theory to accommodate to the frequent flow fluctuation. Simulation results show that our solution can save the controller resources significantly compared with the existing solutions.

Two novel low melting pointing metals (LMPMs), Bi-21In-18Pb-12Sn alloy and Ga-13.5Sn alloy as phase change materials (PCMs), were firstly proposed to work for thermal management in aerospace applications. Their phase change characteristics and thermal stability were investigated in comparison with that of conventional paraffin PCMs (i.e. C26H58 and C17H36). The results indicate that the latent heat per unit volume in the LMPMs is higher than that of the paraffin PCMs, leading to much better thermal capacity of the former, and this can effectively reduce the volume proportion of LMPMs in use. LMPMs exhibit excellent thermal conductivity compared with the paraffin PCMs, and this contributes to rapid absorption of the heat released by the temperature-controlled target, and consequently the temperature of the target could remain stable near the phase change temperature. Besides, the Al2O3 coating by the spraying method could act as effective corrosion inhibitor in protecting Al alloy container used for electronic packaging from the liquid Ga-Sn alloy. The temperature control characteristic and temperature gradient of LMPMs consequently could suit the applied requirement of spacecraft device operated in vacuum condition. Therefore, low melting point metals with better thermal conductivity and stability would be promising candidates for PCMs applied in the field of aerospace.

The low-cost Fe-based amorphous coating with the composition of Fe49.9Mo32.9Cr9.32Co4.55Si2.28Al1.55 (wt.%) were deposited on 316L stainless steel substrate by subsonic flame spraying under optimum spraying parameters. The microstructure, phase composition, microhardness, corrosion-resistance, and wear-resistance properties of the coatings were systematically investigated. The prepared coating primarily consists of amorphous phase (calculated amorphous phase content was 90.23%), and the hardness of the prepared coating can reach 981.6 HV0.1, which is much larger than that of the substrate material 316L stainless steel. The corrosion potential and corrosion current density of the prepared Fe-based amorphous coating in 3.5 wt.% NaCl solution are −438 mV and 6.9 μA/cm2, respectively. Compared with 316L stainless steel and some newly published Fe-based amorphous coatings, the prepared coating shows better corrosion resistance properties. The dry sliding wear rate of the coatings with 0.45% C steel balls at 19.6 N is 1.68 × 10−5 mm3/Nm. The friction coefficient of the coating is at an ultra-low level (about 0.26) and can keep relatively steady throughout the sliding test. The study shows that the prepared Fe-based amorphous coating has high amorphous phase content, high hardness, superior corrosion-resistance, and wear-resistance properties.

Biochemistry is an essential yet often undervalued aspect of soil ecology, especially in soil C cycling. We assume based on tradition, intuition or hope that the complexity of biochemistry is confined to the microscopic world, and can be ignored when dealing with whole soil systems. This opinion paper draws attention to patterns caused by basic biochemical processes that permeate the world of ecosystem processes. From these patterns, we can estimate activities of the biochemical reactions of the central C metabolic network and gain insights into the ecophysiology of microbial biosynthesis and growth and maintenance energy requirements; important components of Carbon Use Efficiency (CUE).The biochemical pathways used to metabolize glucose vary from soil to soil, with mostly glycolysis in some soils, and pentose phosphate or Entner-Doudoroff pathways in others. However, notwithstanding this metabolic diversity, glucose use efficiency is high and thus substrate use for maintenance energy and overflow respiration is low in these three soils. These results contradict current dogma based on four decades of research in soil ecology. We identify three main shortcomings in our current understanding of substrate use efficiency: 1) in numeric and conceptual models, we lack appreciation of the strategies that microbes employ to quickly reduce energy needs in response to starvation; 2) production of exudates and microbial turnover affect whole-soil CUE more than variation in maintenance energy demand; and 3) whether tracer experiments can be used to measure the long-term substrate use efficiency of soil microbial communities depends critically on the ability of non-growing cells to take up tracer substrates, how biosynthesis responds to these substrates, as well as on how cellular activities scale to the community level.To move the field of soil ecology forward, future research must consider the details of microbial ecophysiology and develop new tools that enable direct measurement of microbial functioning in intact soils. We submit that 13C metabolic flux analysis is one of those new tools.

Background Laparoscopic resection of the pancreatic body and tail is the predominant methodology to remove lesions in these locations; its safety and surgical planning are relatively mature, but it remains a complex and high-precision surgical operation, requiring abundant experience and skills in laparoscopic surgery, with a 10% rate of complications. Aim To verify the feasibility and safety, as well as to examine the complications of endoscopic pancreatectomy and healing mechanisms of pancreatic wounds after endoscopic resection. Methods Transgastric endoscopic resections of varying sizes of pancreases were performed in 15 healthy Bama miniature pigs. The technical success rate, the incidence of serious complications, and the survival of the animals were studied. The healing of the wounds was evaluated by sacrificing the animals at various time points. Finally, the expression of transforming growth factor-β1 and Smad3/Smad7 in the surgical site was examined by immunohistochemistry to explore the role of these factors in wound healing of the pancreas. Results Partial and total resections were successfully performed in two groups of animals, respectively. The technical success rate and the survival rate of the pigs were both 100%. We obtained 12 pancreatic tissue samples by endoscopic resection. The pancreatic wounds were closed with metal clips in one group and the wounds healed well by forming scars. There was a small amount of pancreatic leakage in the other group, but it can be fully encapsulated. The level of transforming growth factor-β1 (TGF-β1) in the wounds increased during the inflammatory and fibrous hyperplasia phases, and decreased in the scar phase. The expression of Smad3 paralleled that of TGF-β1, while the expression of Smad7 had an inverse relationship with the expression of TGF-β1. Conclusion Purely transgastric endoscopic resection of the pancreas is a safe, effective, and feasible procedure, but the incidence of pancreatic leakage in total pancreatic tail resection is high. The expression of TGF-β1 and Smad3/Samd7 is related to the progression of pancreatic wound healing.

Hydroxylated isoprenoid glycerol dialkyl glycerol tetraethers (OH-GDGTs) were found having the potential to track past sea surface temperatures (SST), in analogy to the TEX86 – a paleothermometer based on isoprenoid GDGTs (iGDGTs). Especially in estuarine regions with high terrestrial input, the ring index of OH-GDGTs (RI-OH) was more robust to trace the summer SST than TEX86. In order to clarify the potential sources of sedimentary GDGTs and to further elucidate the potential of OH-GDGTs as SST proxy, we investigated the seasonal distribution of core OH-GDGTs and iGDGTs in the suspended particulate matter in a transition section in the Yangtze River Estuary. The concentrations of OH-GDGTs and iGDGTs were higher in the estuary than those in the lower Yangtze River, which suggested the OH-GDGTs and iGDGTs in estuarine sediment mainly came from marine autochthonous organisms, whereas the terrestrial contribution was relatively low. The higher content of OH-GDGTs and iGDGTs in summer than in winter indicated that sedimentary OH-GDGTs and iGDGTs mainly originated from the summer SPM deposition. In addition, the ratio of OH-GDGTs versus iGDGTs suggested that OH-GDGTs were relatively abundant in the upper water layer compared to iGDGTs, regardless of season. Furthermore, the distributions of iGDGTs and OH-GDGTs were found to be influenced by hydrodynamics. The increasing warm bias of iGDGT and OH-GDGT reconstructed temperatures with water depth suggested that either GDGTs in deeper waters derive mainly from surface water or GDGTs cyclization in deeper waters was influenced by reduced ammonium oxidation rates in response to the limited supply of ammonium and oxygen, especially in summer.

The East Siberian Arctic Shelf is an integrated coastal sea system with complex biogeochemical processes influenced by underlying subsea permafrost, hydrates and thermogenic compartments. Methane is released from the marine sediments to the water column, which serves as an interphase between the lithosphere and the atmosphere. Before escaping into water column and atmosphere, methane has potentially experienced extensive aerobic and anaerobic oxidation by microbes in the marine sediment. In particular, the aerobic process is assumed to be dominant in the surface oxic/suboxic marine sediment (upper 1cm) after anaerobic processes in deeper zones. However, these processes are insufficiently understood in sediments of the Arctic Ocean. To probe these, we investigated the microbial lipids and their stable carbon composition in surface marine sediment (upper 1 cm) from two active methane seep areas in the Laptev Sea and the East Siberian Sea.The microbial fatty acids (C12 to C18 fatty acids) were relatively enriched in 13C (δ13C -18.8 to -31.2‰) compared to that of dissolved CH4 in nearby bottom water (-54.6 to -29.7‰). This contrasts to previous reports of strongly depleted δ13C signals in microbial lipids (e.g., -100‰) at active marine mid-ocean ridges and mud volcanoes, from quite different ocean areas. The absence of a depleted δ13C signal in these general microbial biomarkers suggest that these reflect substrates other than methane such as other parts of the sediment organic matter, indicated by the stronger correlation of δ13C between fatty acids and bulk organic carbon than that between fatty acid and CH4. However, the putatively more specific biomarkers for aerobic methanotrophic bacteria (mono-unsaturated C16 and C18 fatty acids) show a distinct pattern in the Laptev Sea and East Siberian Sea: C16:1 and C18:1 were enriched in 13C (up to 4.5 ‰) relative to their saturated analogs in the Laptev Sea; whereas, C18:1 was depleted in 13C (up to 4.5 ‰) compared to C18 in the East Siberian Sea. This could be because the relative populations of Type I and II methanotrophs were different in the two areas with different carbon assimilation pathways. Our results cannot exclude a slowly active aerobic methanotrophs at methane seeps in the East Siberian Arctic Ocean and thus call for more information from molecular microbiology.

This study investigates the dynamic and nonlinear behavior of an eddy current (EC) damping mechanism by using shaking table tests and finite-element modeling. A noncontact and friction-free...

A traditional strain measurement sensor needs to be electrified and is susceptible to electromagnetic interference. In order to solve the fluctuations in the analog electrical signal in a traditional strain gauge operation, a new strain measurement method is presented here. It uses a photographic technique to display the strain change by amplifying the change of the pointer displacement of the mechanism. A visual polydimethylsiloxane (PDMS) lens with a focal length of 7.16 mm was added to a smartphone camera to generate a lens group acting as a microscope to capture images. It had an equivalent focal length of 5.74 mm. Acrylonitrile butadiene styrene (ABS) and nylon amplifiers were used to test the influence of different materials on the sensor performance. The production of the amplifiers and PDMS lens is based on improved 3D printing technology. The data obtained were compared with the results from finite element analysis (FEA) to verify their validity. The sensitivity of the ABS amplifier was 36.03 ± 1.34 µe/µm, and the sensitivity of the nylon amplifier was 36.55 ± 0.53 µe/µm.

Dual stable isotope probing has been used to infer rates of microbial biomass production and modes of carbon fixation. In order to validate this approach for assessing archaeal production, the methanogenic archaeon Methanosarcina barkeri was grown either with H2 , acetate or methanol with D2 O and 13 C-dissolved inorganic carbon (DIC). Our results revealed unexpectedly low D incorporation into lipids, with the net fraction of water-derived hydrogen amounting to 0.357±0.042, 0.226±0.003 and 0.393±0.029 for growth on H2 /CO2 , acetate and methanol, respectively. The variability in net water H assimilation into lipids during growth of M. barkeri on different substrates is possibly attributed to different Gibbs free energy yields, such that higher energy yield promoted the exchange of hydrogen between medium water and lipids. Because NADPH likely serves as the portal for H transfer, increased NADPH production and/or turnover associated with high energy yield may explain the apparent differences in net water H assimilation into lipids. The variable DIC and water H incorporation into M. barkeri lipids imply systematic, metabolic patterns of isotope incorporation and suggest that the ratio of 13 C-DIC vs D2 O assimilation in environmental samples may serve as a proxy for microbial energetics in addition to microbial production and carbon assimilation pathways. This article is protected by copyright. All rights reserved.

Benthic microorganisms play a significant role in the remineralization of sedimentary organic matter (OM). In order to constrain the growth rate, turnover and carbon metabolism of microbial communities in anoxic sandy sediments, we quantified the rate of inorganic carbon (IC) assimilation and of lipid production via a recently developed dual isotope-labelling assay that can differentiate autotrophic vs. heterotrophic production in a 22 cm sediment core from the Janssand tidal flat (Wadden Sea, Germany). Despite an extremely low concentration of total organic carbon (TOC) in the majority of samples (

Members of the archaeal phylum Bathyarchaeota are among the most abundant microorganisms on Earth. Although versatile metabolic capabilities such as acetogenesis, methanogenesis, and fermentation have been suggested for bathyarchaeotal members, no direct confirmation of these metabolic functions has been achieved through growth of Bathyarchaeota in the laboratory. Here we demonstrate, on the basis of gene-copy numbers and probing of archaeal lipids, the growth of Bathyarchaeota subgroup Bathy-8 in enrichments of estuarine sediments with the biopolymer lignin. Other organic substrates (casein, oleic acid, cellulose, and phenol) did not significantly stimulate growth of Bathyarchaeota . Meanwhile, putative bathyarchaeotal tetraether lipids incorporated 13 C from 13 C-bicarbonate only when added in concert with lignin. Our results are consistent with organoautotrophic growth of a bathyarchaeotal group with lignin as an energy source and bicarbonate as a carbon source and shed light into the cycling of one of Earth’s most abundant biopolymers in anoxic marine sediment.