Constant Feeding Rate Research Articles

Nickel-aluminide cladding on a steel substrate using dual wire arc additive manufacturing

In this study the nickel-aluminide intermetallic cladded on AISI 1010 steed using dual wire arc process. The nickel-aluminide is fabricated in situ through an arc provided by a gas tungsten arc welding process and changing aluminum wire feeding rate. The research findings reveal that at a constant Ni wire feeding rate of 450 mm/min, by decreasing the Al wire feeding rate lower than 800 mm/min, the instability of the melt pool prevents the formation of a uniform deposit on the substrate. Although deposition has been done at an Al wire feeding rate higher than 1600 mm/min, transverse cracks have formed in the clad layer. Increasing the aluminum wire feeding rate from 1000 to 1400 mm/min decreases the dendritic arm size from 9.2 ± 0.1 to 4.1 ± 0.3 μm. Although unreacted nickel is visible in the microstructure at the Al wire feeding rate of 1000 mm/min, at a high feeding rate (1400 mm/min), most of the microstructure contains AlNi and Ni3Al intermetallic compounds. With the rise in Al wire feeding rate from 1000 to 1400 mm/min, both yield strength and ultimate tensile strength increase from 521.45 ± 14.16 to 620.89 ± 16.08 MPa and from 762.11 ± 19.89 to 855.65 ± 21.54 MPa, respectively. Intriguingly, the clad layer's tensile toughness decreases from 26.51 ± 2.43 to 18.32 ± 2.56 MJ m−3. By increasing the wire feeding rate from 1000 to 1400 mm/min, the wear rate at room temperature, 500 °C, and 800 °C increases by 61.2, 45.7, and 44.3%, respectively.

Conversion of pyrolysis vapors derived from non-biodegradable waste plastics (PET) into valuable fuels using nickel-impregnated HZSM5-70 catalysts

Recycling waste plastics into pyrolytic fuels is a highly promising energy-saving approach. The improvement and enhancement of the resulting fuel quality from heavy oil-derived-waste plastics pyrolysis is in high demand. We performed catalytic reforming of heavy oils-derived polyethylene terephthalate (PET) pyrolysis to simultaneously improve the quality of oils into valuable fuels (gasoline-range hydrocarbon) and reduce the oxygenated compounds. Nickel-impregnated HZSM5-70 catalysts were prepared by the wet-impregnation method. The catalytic process was carried out in a catalytic tubular reactor at a constant feeding rate of 2.5 mL/h. In particular, various processing factors were examined by varying the impregnation loading of nickel (2–10 wt%), catalyst mass (1–5 wt%), and process temperature (400–500 °C). Increasing any of the three process parameters resulted in a relatively similar decrease in the quantity of liquid products and an improvement in the quality of reformed products. The best quality of reformed oils were obtained at 5 % catalyst loading and 10 % nickel loading on the catalyst at 450 °C. FT-IR analyses show that raising process parameters has a substantial influence on increasing aliphatic and aromatic hydrocarbon content, while lowering the quantity of undesired products (acids, alcohols, and ketones) in the oils. GC–MS analysis results confirmed that the relative content/area of liquid products predominantly contains gasoline-range hydrocarbons (C5-C12), with a total of 33.39 % on blank-run. The hydrocarbons (C5-C12) production from HZSM5-70 and NiO/HZSM5-70 was greatly enhanced to 66.48 % and 85.05 %, repectively, while the oxygenated compounds, including alcohols, acids, and ketones were reduced from 39.38 to 10.75 % (total area). In comparison to HZSM5-70, the NiO/HZSM5-70 catalyst performs more effectively, retaining its catalytic activity after five cycles (∼3 % decrease). Thus, the NiO/HZSM5-70 exhibits high catalytic performance and reusability.

Efficient biosynthesis of exopolysaccharide in Candida glabrata by a fed-batch culture.

Polysaccharides are important natural biomacromolecules. In particular, microbial exopolysaccharides have received much attention. They are produced by a variety of microorganisms, and they are widely used in the food, pharmaceutical, and chemical industries. The Candida glabrata mutant 4-C10, which has the capacity to produce exopolysaccharide, was previously obtained by random mutagenesis. In this study we aimed to further enhance exopolysaccharide production by systemic fermentation optimization. By single factor optimization and orthogonal design optimization in shaking flasks, an optimal fermentation medium composition was obtained. By optimizing agitation speed, aeration rate, and fed-batch fermentation mode, 118.6 g L−1 of exopolysaccharide was obtained by a constant rate feeding fermentation mode, with a glucose yield of 0.62 g g−1 and a productivity of 1.24 g L−1 h−1. Scaling up the established fermentation mode to a 15-L fermenter led to an exopolysaccharide yield of 113.8 g L−1, with a glucose yield of 0.60 g g−1 and a productivity of 1.29 g L−1 h−1.

Design and validation of reactant feeding control strategies for the solar-autothermal hybrid gasification of woody biomass

Several hybridization strategies of a solar-autothermal biomass gasifier were examined for stable and continuous operation under variable solar irradiation. The ultimate objective was to demonstrate the feasibility of controlled syngas production, through the modification of oxygen, water, and biomass injection rates. Various hybridization strategies were probed by thermodynamic analysis and experimentally validated. Thermodynamic equilibrium calculations detailed the impact of both H2O and O2 injection rates on the produced syngas composition under constant wood feeding. Oxygen injection decreased the H2:CO molar ratio, while reducing the solar thermal power required to carry out the gasification reaction. Meanwhile, the total H2+CO production dropped by 1.36 mol of H2 and 0.64 mol of CO per mole of O2 added, independently of the quantity of water provided. Validation experiments were then carried out under real concentrated solar flux in a directly-irradiated conical spouted-bed reactor, following distinct hybridization paths. Maintaining constant the H2:CO ratio above 1 during hybridization required to provide high amounts of water steam with oxygen, which penalized the gasifier efficient heating. In contrast, minimizing the water injection rate throughout hybridization strongly altered the H2:CO ratio but decreased the CO2 production and the solar thermal power requirement. Finally, the successful control of the outlet H2+CO volume flow rate with simultaneous oxygen and wood injection was demonstrated (under constant water feeding rate). Solar-to-fuel efficiencies were kept around 20%, while hybridization decreased the cold-gas efficiency below 80%.

Aerosol filtration performance of nanofibrous mats produced via electrically assisted industrial‐scale solution blowing

AbstractHighly efficient polyamide 6 (PA6)‐based nanofibrous air filter media was developed for particulate matter (PM) removal in the ambient atmosphere. The PA6 nanofibrous mats exhibited 85% PM0.3 capture performance at a cost of 164 Pa pressure drop when the multiple‐nozzle solution blowing system was set to 8 m/h fabric winding speed. However, an increase in the winding speed at a constant feeding rate lowered the filtration efficiency to 62% due to the less amount of nanofibrous mats collected on the substrate. The application of electrical field at the same parameters allowed us to produce a filter media having FFP3‐level filtration performance, which means 99% PM0.3 capture performance. This was attributed to a fine fiber diameter (116 nm), higher solidity value (0.149), and lower average pore size (2.28 μm). These results show that the electrically assisted solution blowing provides a feasible route for the production of high‐quality nanofibrous filter media.

Optimization of Hydrolysis-Acidogenesis Phase of Swine Manure for Biogas Production Using Two-Stage Anaerobic Fermentation

The traditional pig manure wastewater treatment in Taiwan has been low in methane production efficiency due to unstable influent concentration, wastewater volume, and quality. Two-stage anaerobic systems, in contrast, have the advantage of buffering the organic loading rate in the first stage (hydrolysis-acidogenesis phase), allowing a more constant feeding rate to the second stage (methanogenesis phase). Response surface methodology was applied to optimize the operational period (0.5–2.0 d) and initial operational pH (4–10) for hydrolysis and acidogenesis of the swine manure (total solid 5.3%) at 35 °C in batch operation mode. A methanogenesis verification experiment with the optimal condition of operational period 1.5 d and pH 6.5 using batch operation resulted in peak volatile acid production 7 g COD/L, methane production rate (MPR) 0.3 L-CH4/L-d, and methane yield (MY) 92 mL-CH4/g-CODre (chemical oxygen demand removed). Moreover, a two-stage system including a hydrolysis-acidogenesis reactor with the optimal operating condition and a methanogenesis reactor provided an average MPR 163 mL/L-d and MY 38 mL/g volatile solids, which values are 60% higher than those of a single-stage system; both systems have similar dominant methane-producing species of Firmicutes and Bacteroidetes with each having around 30%–40%. The advantages of a two-stage anaerobic fermentation system in treating swine manure for biogas production are obvious.

Transient shifts in hydraulic retention times improve the methane production from ruminal hydrolysates of agave bagasse

AbstractBACKGROUNDValorization of lignocellulosic wastes such as agave bagasse from tequila industries can be enhanced using efficient biomass pretreatments. However, the next challenge requires finding the best process conditions to produce methane and remove chemical oxygen demand (COD) from the pretreatment hydrolysates. In this work, an innovative feeding strategy based on alternating hydraulic retention times (HRT) was investigated to improve methane production from ruminal hydrolysates of Agave tequilana bagasse.RESULTSThe ruminal hydrolysate provided a substrate rich in volatile fatty acids (VFA) for direct use in the methanogenic process. The alternating feeding strategy increased the volumetric methane production rate by up to 25% (from 0.76 ± 0.05 to 0.95 ± 0.03 L CH4 L−1 d−1) compared to operating at a constant feeding rate, equivalent HRT of 15 h, and organic loading rate (OLR) of 8 g COD L−1 d−1. The alternating HRT operation improved VFA conversion without modifying the methane yield, and the COD removal was increased by 14%. The system stability, measured through the alkalinity index, was maintained during the proposed feeding strategy and after the increase in OLR.CONCLUSIONThe proposed feeding strategy is a promising tool for improving methane production from agave bagasse hydrolysates. The strategy was robust and easy to apply, which could expand its use for a wider variety of substrates. © 2021 Society of Chemical Industry (SCI).

Laser Surface Modification of TC21 (α/β) Titanium Alloy Using a Direct Energy Deposition (DED) Process.

The TC21 alloy (Ti-6Al-3Mo-1.9Nb-2.2Sn-2.2Zr-1.5Cr) is considered a new titanium alloy that replaced the commercial Ti-6Al-4V alloy in aerospace applications due to its higher operating temperatures. Recently, direct energy deposition was usually applied to enhance the hardness, tribological properties, and corrosion resistance for many alloys. Consequently, this study was performed by utilizing direct energy deposition (DED) on TC21 (α/β) titanium alloy to improve their mechanical properties by depositing a mixture powder of stellite-6 (Co-based alloy) and tungsten carbides particles (WC). Different WC percentages were applied to the surfaces of TC21 using a 4 kW continuous-wave fiber-coupled diode laser at a constant powder feeding rate. This study aimed to obtain a uniform distribution of hard surfaces containing undissolved WC particles that were dispersed in a Co-based alloy matrix to enhance the wear resistance of such alloys. Scanning electron microscopy, energy dispersive X-ray analysis (EDAX), and X-ray diffractometry (XRD) were used to characterize the deposited layers. New constituents and intermetallic compounds were found in the deposited layers. The microhardness was measured for all deposited layers and wear resistance was evaluated at room temperature using a dry sliding ball during a disk abrasion test. The results showed that the microstructure of the deposited layer consisted of a hypereutectic structure and undissolved tungsten carbide dispersed in the matrix of the Co-based alloy that depended on the WC weight fraction. The microhardness values increased with increasing WC weight fraction in the deposited powder by more than threefold as compared with the as-cast samples. A notable enhancement of wear resistance of the deposited layers was thus achieved.

A simple image analysis technique for measuring bed surface texture in flume experiments

We present a simple image analysis technique for measuring the sediment composition of the bed surface during flow with bedload transport in flume experiments. The bed was composed by a bimodal mixture of natural sediments and the flow conditions were such that both fractions were mobile. A camera placed 2.5 meters above the flume framed the central part and took pictures every minute, allowing for a high-resolution data acquisition. The two sediment fractions had different colors, thus we developed an image analysis technique based on color detection. This technique provided the areal fraction content of each fraction and the detection of patterns of sorted sediments, namely patches of each grain size, and it was applied in three laboratory experiments conducted to study the influence of lateral width constraint on channel morphology, sediment sorting, and bedload transport. The three experiments were carried out under constant feeding rate conditions, in particular a sediment supply equal to the transport capacity was provided, thereby matching dynamic equilibrium conditions. The image processing was implemented through a code written in Matlab and made available for other users.

Effect of mechtrode rotational speed on friction surfacing of AA2024 on AA1050 substrate

The present work investigated the fabrication of two-layered AA1050-AA2024 material by friction surfacing process. The effect of rotational speed of a consumable rod was evaluated on the microstructure, macrotexture, and tribological characteristics of AA1050-AA2024 bimetal. In this regard, AA2024 aluminum alloy was friction surfaced on AA1050 substrate by three rotational speeds of 1000, 800, and 600rpm, constant axial feeding rate of 125mm/min, and traverse speed of 75mm/min. The AA2024 cladded material was characterized by optical microscopy, scanning electron microscopy, texture analysis, and wear test. As observed, the shear and recrystallization texture of low intensity was created in the clad layer. The precipitation hardening and grain refinement hardening are the main strengthening mechanism in the AA2024 clad layer. The AA2024 clad layer with the maximum shear strength of 189.64MPa, wear rate of 0.0012mg/m, and coefficient of friction of 0.52 was applied on AA1050 using friction surfacing. Given the excellent corrosion resistant and formability of AA1050 substrate, friction surfacing of AA2024 with rotational speed, traverse speed, and axial feeding rate of 1000rpm, 125mm/min, and 75mm/min, respectively, resulted in the formation of AA1050-AA2024 bimetal with a reduction in wear rate, and an increase in hardness of the clad layer by factors of 2.83 and 3.37 compared to substrate, respectively.

Fed-Batch Cultivation and Adding Supplements to Increase Yield of β-1,3-1,4-Glucanase by Genetically Engineered Escherichia coli

The aim of this study was to analyze the major influence factors of culture medium on the expression level of β-1,3-1,4-glucanase, and to further develop an optimized process for the extracellular production of β-glucanase at a bioreactor scale (7 L) with a genetically engineered Escherichia coli (E. coli) JM109-pLF3. In this study, batch cultivation and fed-batch cultivation including the constant rate feeding strategy and the DO-stat (DO: Dissolved Oxygen) feeding strategy were conducted. At a 7 L bioreactor scale for batch cultivation, biomass reached 3.14 g/L and the maximum β-glucanase activity was 506.94 U/mL. Compared with batch cultivation, the addition of glycerol, complex nitrogen and complete medium during fed-batch cultivation increased the production of biomass and β-1,3-1,4-glucanase. The maximum biomass and β-glucanase activity, which were 7.67 g/L and 1680 U/mL, respectively, that is, 2.45 and 3.31 times higher than those obtained with batch cultivation, were obtained by feeding a complex nitrogen source at a constant rate of 1.11 mL/min. Therefore, these nutritional supplements and strategies can be used as a reference to enhance the production of other bioproducts from E. coli.

Sequential coupling of enzymatic hydrolysis and fermentation platform for high yield and economical production of 2,3‐butanediol from cassava by metabolically engineered Klebsiella oxytoca

AbstractBACKGROUND2,3‐butanediol (2,3‐BD) is one of the important platform chemicals used for biofuels and biochemicals. To make an economically feasible production of 2,3‐BD, an optimization process with a cheap substrate is required. The best conditions for enzymatic hydrolysis and fermentation were investigated to achieve high concentration and yield of 2,3‐BD from cassava starch while reducing the production cost regarding enzyme usage, energy input and medium preparation.RESULTSA 2.5 L bioreactor containing 1 L working volume of sterilized and gelatinized starch (130 g L−1) was placed at room temperature (25 °C). When the temperature of the starch solution reached 85 °C, α‐amylase (200 U g−1 starch) was added to the solution. The enzymatic reaction was allowed to proceed while the temperature of the solution was simultaneously dampened to 45 °C within 1 h. The reaction was further maintained at 45 °C for another 2 h. After hydrolysis, 64.8 g L−1 2,3‐BD was produced with a yield of 0.46 g g−1, productivity of 1.25 g L−1 h−1 and few by‐products by Klebsiella oxytoca KMS006. Further improvements of 2,3‐BD (92.5 g L−1) and yield (0.49 g g−1) were observed in fed‐batch mode under a constant feeding rate of 3.5 g starch h−1.CONCLUSIONWith our developed strategy, costs related to energy consumption and medium preparation were reduced by using heat generated by autoclave as well as by neglecting the use of glucoamylase for hydrolysis of cassava starch. The highest yield of 2,3‐BD (0.49 g g−1) was achieved, which is 98% of theoretical maximum. The process may be applied to the economical production of 2,3‐BD. © 2020 Society of Chemical Industry

Morphology, Bedload, and Sorting Process Variability in Response to Lateral Confinement: Results From Physical Models of Gravel‐bed Rivers

This paper uses flume experiments to investigate the influence of lateral width confinement on channel morphology, sediment sorting, and bedload transport. Three runs of about 60 hr were carried out under constant feeding rate equal to 0.6 l/s and 8 g/s, with a bimodal mixture of natural sediments, a fixed flume slope of 3%, and width imposed by lateral walls from 0.12 to 0.50 m in order to model three different flow confinement configurations. Despite the three runs transporting at the same rate on average, they presented different gravel‐bed river morphologies and different degrees of bed complexity. The three runs also presented differences in bedload transport rate fluctuations associated with different magnitude and mechanisms of bed storage and release of sediments. The intermediate width configuration (Run 2) was found to have a minimum storage and release of sediments compared with both the wider configuration (Run 1) and the narrower configuration (Run 3). Runs 1 and 3 were characterized by a significant storage and release of sediments resulting in a highly fluctuating bedload transport rate; however, while Run 1 (braiding morphology) stored and released sediments through lateral deposits and bed variations with planimetric sorting, Run 3 (single‐thread channel) stored and released sediments through variations in bed elevation accompanied by vertical sorting. We extrapolated this concept to the full set of gravel‐bed river morphologies, thus speculating about the channel morphology for optimal sediment transfer.

Development of a New High-Cell Density Fermentation Strategy for Enhanced Production of a Fungus β-Glucosidase in Pichia pastoris.

Traditional diosgenin manufacturing process has led to serious environmental contamination and wastewater. Clean processes are needed that can alternate the diosgenin production. The β-glucosidase FBG1, cloned from Fusarium sp. CPCC 400709, can biotransform trillin and produce diosgenin. In this study, Pichia pastoris production of recombinant FBG1 was implemented to investigate various conventional methanol induction strategies, mainly including DO-stat (constant induction DO), μ-stat (constant exponential feeding rate) and m-stat (constant methanol concentration). The new co-stat strategy combining μ-stat and m-stat strategies was then developed for enhanced FBG1 production during fed-batch high-cell density fermentation on methanol. The fermentation process was characterized with respect to cell growth, methanol consumption, FBG1 production and methanol metabolism. It was found that large amounts of formaldehyde were released by the enhanced dissimilation pathway when the co-stat strategy was implemented, and therefore the energy generation was enhanced because of improved methanol metabolism. Using co-stat feeding, the highest volumetric activity reached ∼89 × 104 U/L, with the maximum specific activity of ∼90 × 102 U/g. After 108 h induction, the highest volumetric production reached ∼403 mg/L, which was ∼91, 154, and 183 mg/L higher than the maximal production obtained at m-stat, μ-stat, and DO-stat strategies, respectively. FBG1 is the first P. pastoris produced recombinant enzyme for diosgenin production through the biotransformation of trillin. Moreover, this newly developed co-stat induction strategy represents the highest expression of FBG1 in P. pastoris, and the strategy can be used to produce FBG1 from similar Pichia strains harboring Fbg1 gene, which lays solid foundation for clean and sustainable production of diosgenin. The current work provides unique information on cell growth, substrate metabolism and protein biosynthesis for enhanced β-glucosidase production using a P. pastoris strain under controlled fermentation conditions. This information may be applicable for expression of similar proteins from P. pastoris strains.

Preparation of Hot-Melt Extruded Dosage Form for Enhancing Drugs Absorption Based on Computational Simulation.

The aim of this study was to control the dissolution rate and permeability of cilostazol. To enhance the dissolution rate of the active pharmaceutical ingredient (API), hot-melt extrusion (HME) technology was applied to prepare a solid dispersion (SD). To control permeability in the gastrointestinal tract regardless of food intake, the HME process was optimized based on physiologically based pharmacokinetic (PBPK) simulation. The extrudates were produced using a laboratory-scale twin-screw hot-melt extruder with co-rotatory screws and a constant feeding rate. Next, for PBPK simulation, parameter-sensitive analysis (PSA) was conducted to determine the optimization approach direction. As demonstrated by the dissolution test, the solubility of extrudate was enhanced comparing cilostazol alone. Based on the PSA analysis, the surfactant induction was a crucial factor in cilostazol absorption; thus, an extrudate with an even distribution of lipids was produced using hot-melt extrusion technology, for inducing the bile salts in the gastrointestinal tract. In vivo experiments with rats demonstrated that the optimized hot-melt extruded formulation was absorbed more rapidly with lower deviation and regardless of the meal consumed when compared to marketed cilostazol formulations.

The Digestibility of Banana Peel and Testa coconut and Its Effects on the Growth and Mortality of Black Soldier Fly Larvae (Hermetia illucens) at Constant Feeding Rates

Organic waste produced by economic activities may create health, aesthetic, and economic problems. One of the approaches applied to solve this problem is the utilization of decomposer macrofauna to decompose the waste. One of the decomposers with great potential is Black Soldier Fly larvae (Hermetia illucens) that can consume various types of organic wastes and converts it into biomass with high protein and lipid content. In this study, banana peels and coconut testa had been fed to the larvae at 200 mg/larvae/day as the objects that represented organic wastes with low fiber content and high fiber content respectively. The purpose of this study was to observe the growth and efficiency of BSF larvae in decomposing those wastes. The analysis was conducted on some parameters such as the growth and consumption rate, the efficiency of conversion of digested (ECD), waste reduction index, and mortality rate. The results showed that BSF larvae THAT consumed banana peel had a higher final weight (58.24 mg), growth rate, and consumption rate while the mortality rate was lower than BSF larvae that consumed coconut testa. The ECD of the larvae group that consumed banana peel was higher than the larvae group that consumed coconut testa. The waste reduction index of banana peel was higher than coconut testa (1.5 and 1.4, respectively). The larvae that consumed coconut testa had a longer pupation period (9±1,75 days) compared to the larvae that consumed banana peel. Based on this result, it can be concluded that the fiber content of organic waste affected the decomposition rate and growth of BSF larvae.

Enhancement of pullulanase production from recombinant Bacillus subtilis by optimization of feeding strategy and fermentation conditions

Pullulanase is an important starch-debranching enzyme mostly used in starch processing-related food industries. However, the levels of pullulanase produced from recombinant Bacillus subtilis, a Generally Recognized as Safe (GRAS) host, are generally limited. To enhance the activity of pullulanase, batch fermentation and fed-batch fermentation were systematically investigated. The overall purpose is to improve the fermentation yield by optimizing the feeding strategy in the fermentation process, thereby increasing the enzyme activity of pullulanase. Therefore, in this study, the feeding methods, the feeding ingredients, the feeding concentration, and pH values were studied in detail. The optimized fermentation conditions for pullulanase production from recombinant B. subtilis were determined as following: inoculum volume 7%, pH 6.5, the dissolved oxygen level 30%, and constant-rate feeding of 100 mL glucose solution (400 g L−1) in late logarithmic growth. The OD600 of recombinant B. subtilis and enzyme activity were 84.54 and 102.75 U mL−1, which were respectively 141% and 144% higher than that before optimization. These findings provided a prerequisite for further amplification of the fermentation system to obtain higher enzyme activity.

A comparison of ten digestive enzymes reveals a lack of chitinase in a phasmid and the loss of two β‐glucanases in a mantid

AbstractIn all developmental stages, the phasmid Peruphasma schultei (Conle & Hennemann, 2005) is an obligate herbivore, whereas the mantid Hierodula membranacea (Burmeister, 1838) is an obligatory carnivore. In P. schultei, the luminal activity of all enzymes is approxximately 50% in the crop and 50% in the midgut, which corresponds to the approximate 50 : 50 ratio of volumes of these two regions. These ratios would be expected in insects with a constant feeding rate on an unvaried diet. The enzyme activity and volume ratios in Hierodula membranacea vary considerably because of the irregular feeding habits. These differences in activity ratios between phasmids and mantids are not associated with the obligate phytophagous or carnivorous diet. The ratio of membrane bound to luminal aminopeptidases and disaccharidases in the midgut of both species are not significantly different and are within the normal range of other paurometabolous insects. Cellobiase and other plant cell wall digesting enzymes, laminarinase and cellobiase, are present in the phasmid but totally lacking in the mantid. The obligate carnivorous feeding habits of mantids could represent a selective factor leading to the loss of the ability to produce β‐glucanases. Chitinase is a moulting enzyme in all insects, whereas, in H. membranacea, chitinase also occurs as a luminal digestive enzyme. This modified enzyme function requires production and secretion in another tissue, namely the midgut.

Heat dissipation capacity influences reproductive performance in an aerial insectivore.

Climatic warming is predicted to increase the frequency of extreme weather events, which may reduce an individual's capacity for sustained activity because of thermal limits. We tested whether the risk of overheating may limit parental provisioning of an aerial insectivorous bird in population decline. For many seasonally breeding birds, parents are thought to operate close to an energetic ceiling during the 2-3 week chick-rearing period. The factors determining the ceiling remain unknown, although it may be set by an individual's capacity to dissipate body heat (the heat dissipation limitation hypothesis). Over two breeding seasons we experimentally trimmed the ventral feathers of female tree swallows (Tachycineta bicolor) to provide a thermal window. We then monitored maternal and paternal provisioning rates, nestling growth rates and fledging success. We found the effect of our experimental treatment was context dependent. Females with an enhanced capacity to dissipate heat fed their nestlings at higher rates than controls when conditions were hot, but the reverse was true under cool conditions. Control females and their mates both reduced foraging under hot conditions. In contrast, male partners of trimmed females maintained a constant feeding rate across temperatures, suggesting attempts to match the feeding rate of their partners. On average, nestlings of trimmed females were heavier than controls, but did not have a higher probability of fledging. We suggest that removal of a thermal constraint allowed females to increase provisioning rates, but additionally provided nestlings with a thermal advantage via increased heat transfer during maternal brooding. Our data provide support for the heat dissipation limitation hypothesis and suggest that depending on temperature, heat dissipation capacity can influence reproductive success in aerial insectivores.

An auto-inducible expression and high cell density fermentation of Beefy Meaty Peptide with Bacillus subtilis.

Currently, some cases about the expression of flavor peptides with microorganisms were reported owing to the obvious advantages of biological expression over traditional methods. However, beefy meaty peptide (BMP), the focus of umami peptides, has neither been concerned in its safe expression nor its overproduction in fermenter. In this study, multi-copy BMP (8BMP) was successfully auto-inducibly expressed and efficiently produced in Bacillus subtilis 168. First, 8BMP was successfully auto-inducibly expressed with srfA promoter in B. subtilis 168. Further, the efficient production of 8BMP was researched in a 5-L fermenter: the fermentation optimized by Pontryagin's maximum principle obtained the highest 8BMP yield (3.16g/L), which was 1.2 times and 1.8 times than that of two-stage feeding cultivation (2.67g/L) and constant-rate feeding cultivation (1.75g/L), respectively. Overall, the auto-inducible expression of 8BMP in B. subtilis and fermentation with Pontryagin's maximum principle are conductive for overproduction of BMP and other peptides.