High Feed Rate Research Articles

Alternative economic and shortened method for the production of dried germinated rice

Since germination creates chalky grain around the entire surface of the kernel, it is commonly eliminated by steaming germinated paddy before drying. In this work, a continuous fluidized bed with a capacity of 100 kg/h was therefore used to treat the chalkiness with high-temperature hot air. The performance of this dryer in terms of water evaporation capacity and energy consumption along with the quality attributes was determined quantitatively. Two crops of Khao Dawk Mali 105 stored for 1 month and 8 and 9 months were used as the raw material. Hot air at temperatures of 130–150 °C with full recycling of the exhaust air was able to eliminate the chalkiness perfectly. The best performance, as indicated by higher water evaporation capacity and lower energy consumption, was obtained at a higher feed rate, higher bed depth and higher drying temperature. The higher bed depth and drying temperature provided a higher degree of starch gelatinization and the correspondingly higher head brown rice yield and hardness of the cooked germinated brown rice except for stickiness. Within the studied drying temperature range, the amount of accumulated gamma-aminobutyric acid after drying the rice which had been stored for 1 month decreased slightly compared to that of the sun-dried product, in a range of 11.4–12.6 mg per 100 g, and decreased significantly for the rice which had been stored for 8 and 9 months. The storage period also influenced the texture after cooking. It is recommended that to obtain the premium quality from the germinated product, the paddy should be stored for 1 month, and a drying temperature of approximately 130˚C should be applied. Under the recommended conditions, the energy consumption was about 1.13 MJ/kg of paddy, and the operating cost of the continuous fluidized bed was 0.17 USD/kg, which was more economical than that of the conventional method.

Temperature and food sources influence subadult development and blood-feeding response of Culicoides obsoletus (sensu lato) under laboratory conditions

BackgroundCulicoides obsoletus (s.l.) is the most abundant Culicoides species in northern Europe and an important vector of bluetongue virus and Schmallenberg virus. Nevertheless, information on its subadult life stages remains scarce and no laboratory-reared colony exists.MethodsC. obsoletus (s.l.) adults were collected in Belgium and transferred to the laboratory in an attempt to establish a laboratory-reared colony. C. obsoletus (s.l.) were reared from eggs to adults at different temperatures (28 °C, 24 °C, 20/16 °C) and under different food regimes.ResultsThe most suitable temperature for rearing seemed to be 24 °C for most developmental parameters, but resulted in a biased 3:1 male/female sex ratio. The latter could be optimized to a 1:1 sex ratio when a 20/16 °C day/night temperature gradient was applied, but rearing at these low temperature conditions resulted in significantly lower egg hatching and pupation rates and a longer subadult development time. Independent of the rearing temperature, adding dung as an additional food source during larval development resulted in a significantly higher adult emergence rate and a decrease in subadult development time. Furthermore, blood-feeding rates of field-collected C. obsoletus (s.l.) were compared for different blood sources and feeding systems. The overall blood-feeding success was low and only successful with cotton pledgets (2.7% blood-fed midges) and through a membrane system with chicken skin (3.5% blood-fed midges). Higher feeding rates were obtained on cattle blood compared to sheep blood.ConclusionsThese results will help us to determine the necessary conditions to rear a viable laboratory colony of this important vector species, although further optimization is still required.Graphical abstract

Physicochemical properties of red palm oil extruded potato and sweet potato snacks

Extruded potato (P) and sweet potato (SP) products with red palm oil (RPO) were prepared under different conditions. Superior product characteristics such as sensory score, expansion ratio, and water solubility index, among others, were obtained at high extrusion temperature (150-155 °C) and low water feed rate to the extruder (50.4-50.8 mL/min). The optimal products, P1 and SP1, had high micronutrients as their total contents of β-carotene, squalene, tocopherols, and tocotrienols were 883.2, 304.4, 262.4, and 397.0 mg/kg of oil, respectively. The average peroxide value was 4.3 meq O2/kg oil, p-anisidine value 3.3, and induction period (100 °C) 11.4 h. Moreover, RPO extruded with P showed a better extrusion behavior but lower micronutrient retention and oxidative stability than that extruded with SP. Thus, the finding herein is important for investigating extrusion conditions, increasing variety, improving nutritional quality, assessing applicability and predicting the shelf-life of RPO-P/SP-extruded food.

Holobiont nitrogen control and its potential for eutrophication resistance in an obligate photosymbiotic jellyfish

BackgroundMarine holobionts depend on microbial members for health and nutrient cycling. This is particularly evident in cnidarian-algae symbioses that facilitate energy and nutrient acquisition. However, this partnership is highly sensitive to environmental change—including eutrophication—that causes dysbiosis and contributes to global coral reef decline. Yet, some holobionts exhibit resistance to dysbiosis in eutrophic environments, including the obligate photosymbiotic scyphomedusa Cassiopea xamachana.MethodsOur aim was to assess the mechanisms in C. xamachana that stabilize symbiotic relationships. We combined labelled bicarbonate (13C) and nitrate (15N) with metabarcoding approaches to evaluate nutrient cycling and microbial community composition in symbiotic and aposymbiotic medusae.ResultsC-fixation and cycling by algal Symbiodiniaceae was essential for C. xamachana as even at high heterotrophic feeding rates aposymbiotic medusae continuously lost weight. Heterotrophically acquired C and N were readily shared among host and algae. This was in sharp contrast to nitrate assimilation by Symbiodiniaceae, which appeared to be strongly restricted. Instead, the bacterial microbiome seemed to play a major role in the holobiont’s DIN assimilation as uptake rates showed a significant positive relationship with phylogenetic diversity of medusa-associated bacteria. This is corroborated by inferred functional capacity that links the dominant bacterial taxa (~90 %) to nitrogen cycling. Observed bacterial community structure differed between apo- and symbiotic C. xamachana putatively highlighting enrichment of ammonium oxidizers and nitrite reducers and depletion of nitrogen-fixers in symbiotic medusae.ConclusionHost, algal symbionts, and bacterial associates contribute to regulated nutrient assimilation and cycling in C. xamachana. We found that the bacterial microbiome of symbiotic medusae was seemingly structured to increase DIN removal and enforce algal N-limitation—a mechanism that would help to stabilize the host-algae relationship even under eutrophic conditions.7oa3UySP_GrME2-vNuUwrBVideo abstract

Non-traditional legumes in the soil-protecting crop rotation of the mountain zone of the Republic of North Ossetia-Alania

Mountainous and sloping lands occupy one third of the territory of our country, more than 50% in the Republic of North Ossetia-Alania, and are a huge reserve for increasing agricultural production. Soil and climatic conditions on the slopes of the mountains and in the intermountain valleys make it possible to grow environmentally friendly products, to heal the seeds of agricultural crops from viral diseases. Increasing the production of agricultural products is one of the most important problems of agriculture. The mountainous territory of the Republic of North Ossetia-Alania is an important reserve for increasing the volume of agricultural production. About forty percent of the total area of the republic is concentrated here, most of which is characterized by favorable soil and climatic conditions. The development of agrotechnical, anti-erosion measures is one of the factors of preventing erosion processes in the soil and restoring soil fertility. The research was carried out in a mountainous area on mountain-meadow soils. According to the mechanical composition, it is middle loamy. The soil contains a high level of organic matter. It is moderately provided with hydrolyzable nitrogen and mobile phosphorus, and is highly provided with potassium. Studies have shown that these soils are favorable for the cultivation of perennial non-traditional leguminous grass species-eastern galega and crown vetch and the obtaining of products with high feed rates. The greatest soil protection effect from water erosion in the crop rotation was possessed by perennial leguminous grasses cultivated on a herbage – clover with timothy, eastern galega and crown vetch, which have a coefficient of soil protection from water erosion. In the soil-protecting six-field crop rotation eastern galega and crown vetch improved the structural and aggregate composition of the soil, the water resistance of soil aggregates, density and pore volume, also they increased soil fertility.

Effect of powder feed rate on adhesion strength and microhardness of APS NiTi coating: a microstructural investigation

In the current investigation, an atmospheric plasma spray technique has been adopted to coat the NiTi material on the mild steel substrate. The coatings have been developed by varying powder feed rates. The microhardness and adhesion strength of the coatings have been evaluated and analysed. It has been observed that the microhardness and adhesion strength of the coating developed at 60 g min−1 depicted the best results. The coatings fabricated by low powder feed rates have evaporation, over melting and low deposition efficiency which leads to the decrease in microhardness and adhesion strength value. Furthermore, the coatings developed at a very high powder feed rate having a lack of heat transfer between plasma and particles and change in trajectories of the particles which leads to increase unmelted particle formation, porosity, and microcracks. This results in a decline in microhardness and adhesion strength of the coating.

DEM study on the mixed feeding process of coal and cylindroid biomass particles in a screw feeder

The complex mixed feeding process for the binary mixture of coal and cylindroid biomass particles in a screw feeder was numerically studied by the discrete element method (DEM). The effects of biomass feeding ratio, feeding rate, and screw rotational speed on the feeding performance were investigated with the continuity, uniformity, and stability of the mixed feeding process being emphatically discussed. The results reveal that the stability of real-time mass flow rate and biomass blending ratio performs better at higher biomass feeding ratios. A larger variability of real-time biomass blending ratio is found at low feeding rate, while increasing the feeding rate reduces the stability of real-time mass flow rate and the too high feeding rate would cause some cylindroid biomass particles being hindered by the front wall surface of the hopper. Moreover, increasing the screw rotational speed significantly increases the stability of the mixed feeding process.

Analysis of Hole Quality and Chips Formation in the Dry Drilling Process of Al7075-T6

Millions of holes are produced in many industries where efficient drilling is considered the key factor in their success. High-quality holes are possible with the proper selection of drilling process parameters, appropriate tools, and machine setup. This paper deals with the effects of drilling parameters such as spindle speed and feed rate on the chips analysis and the hole quality like surface roughness, hole size, circularity, and burr formation. Al7075-T6 alloy, commonly used in the aerospace industry, was used for the drilling process, and the dry drilling experiments were performed using high-speed steel drill bits. Results have shown that surface roughness decreased with the increase in spindle speed and increased with the increase in the feed rate. The hole size increased with the high spindle speed, whereas the impact of spindle speed on circularity error was found insignificant. Furthermore, short and segmented chips were achieved at a high feed rate and low spindle speed. The percentage contribution of each input parameter on the output drilling parameters was evaluated using analysis of variance (ANOVA).

Conversion of Cyclohexane to 6-Hydroxyhexanoic Acid Using Recombinant Pseudomonas taiwanensis in a Stirred-Tank Bioreactor

6-hydroxyhexanoic acid (6HA) represents a polymer building block for the biodegradable polymer polycaprolactone. Alternatively to energy- and emission-intensive multistep chemical synthesis, it can be synthesized directly from cyclohexane in one step by recombinant Pseudomonas taiwanensis harboring a 4-step enzymatic cascade without the accumulation of any intermediate. In the present work, we performed a physiological characterization of this strain in different growth media and evaluated the resulting whole-cell activities. RB and M9* media led to reduced gluconate accumulation from glucose compared to M9 medium and allowed specific activities up to 37.5 ± 0.4 U gCDW−1 for 6HA synthesis. However, 50% of the specific activity was lost within 1 h in metabolically active resting cells, specifying growing cells, or induced resting cells as favored options for long-term biotransformation. Furthermore, the whole-cell biocatalyst was evaluated in a stirred-tank bioreactor setup with a continuous cyclohexane supply via the gas phase. At cyclohexane feed rates of 0.276 and 1.626 mmol min−1 L−1, whole-cell biotransformation occurred at first-order and zero-order rates, respectively. A final 6HA concentration of 25 mM (3.3 g L−1) and a specific product yield of 0.4 g gCDW−1 were achieved with the higher feed rate. Product inhibition and substrate toxification were identified as critical factors limiting biocatalytic performance. Future research efforts on these factors and the precise adjustment of the cyclohexane feed combined with an in situ product removal strategy are discussed as promising strategies to enhance biocatalyst durability and product titer and thus to enable the development of a sustainable multistep whole-cell process.

Process intensification in binary adsorption of VOC-water vapor on zeolite in a countercurrent fluidized bed adsorber

In this study, fast ideal adsorbed solution theory was coupled with a two-phase bubbling bed approach to describe the adsorption of volatile organic compounds (VOCs) on zeolite in the presence of water vapor in a multistage fluidized bed adsorber. The binary adsorption of VOC-water vapor was predicted using their single component adsorption isotherms. The model was verified by experimental data obtained at a wide range of operating conditions before being used for studying the process intensification. Validation tests revealed that the model could accurately predict the experimental removal efficiencies (R2 = 0.94), as well as VOC concentration profiles inside the bed (R2 = 0.98). The intensification simulations showed that increasing the adsorbent feed rate is effective when there is a need for more adsorption sites (e.g. at high inlet concentrations), and is quite ineffective when the adsorption process is limited by low solid-gas contact time (e.g. high air flow rates). Increasing the adsorbent feed rate can also diminish the interference of water vapor in adsorption of VOC (even at RH as high as 75%). Reducing air flow rate at constant VOC load is always effective specially when there are enough adsorption sites available (e.g. high adsorbent feed rate, and low VOC loads and RHs). Similarly, increasing the number of stages can effectively improve the fluidized bed performance at high adsorbent feed rates and low VOC inlet concentrations and RHs. Using 3 adsorbers of 2 stages instead of 1 adsorber of 6 stages can improve the removal efficiency up to 34.5% in the range of operating conditions simulated. While having the same high weir height along the bed yields better performance than having the same low weir height, an optimized arrangement of weir heights in a descending order from the top to the bottom of the bed would maximize the removal efficiency.

Spheroidization of borosilicate glass powder by RF induction coupled plasma

The International Simple Glass (ISG) spherical particles were prepared by Ar–H2 radio-frequency (RF) plasma, the effect of experimental parameters on the volatilization and size distribution of spherical particles was studied. The results show that the spherical powders can be obtained by RF plasma. The spheroidized powders (112 μm) have a smaller diameter than starting particles (124 μm). The high spheroidization (98%) was achieved under low flow rate of carry gas and low feed rate. In addition, the volatilization of B2O3 and Na2O are 23.48% and 56.36%, respectively. The higher feed rate and flow rate of carry gas, the lower volatilization of B2O3 and Na2O and well-spheroidization rate. Meanwhile, the particle surface is not completely smooth at low flow rate of carry gas. The distribution of elements was studied by Electro-probe Microanalyzer (EPMA), which shows the distribution of element is nearly homogeneous that provides a possibility for subsequent research.

Impact resistance of WC-Co reinforced HVAF-sprayed FeCrB-coatings

This study describes the development of cost-effective FeCrB-coatings and the evaluation of these novel coatings against impact loads. The cost reduction is achieved by using a new and economical iron-based feedstock material with a small particel size distribution, which can be processed at high feeding rates with the HVAF process. The reduced particle size distribution enhances the application of near-net-shape coatings, minimizing the need for expensive, time-consuming grinding postprocesses. Thicker coatings usually result in higher thermal insulation, whereas thin near-net-shape coatings can reduce the thermal insulation. Dense FeCrB and FeCrB/WC-Co coatings were applied by HVAF with feeding rates of ṁ = 200 g/min and a particle size distribution of -20 + 3 μm. Through curvature measurements during the application it is shown that by integrating WC-Co into FeCrB the tensile residual stress state of the coating was minimized, which in turn increased the fracture toughness of the coating. The evaluation of the impact resistance was investigated by an impact test. The results show that the crater volume was halved by adding WC-Co in the FeCrB-coating. However, it is shown that the plastic deformability of the coating is minimized and a stronger cracking behavior can be observed.

High-Performance Face Milling of 42CrMo4 Steel: Influence of Entering Angle on the Measured Surface Roughness, Cutting Force and Vibration Amplitude

High feed Milling is a new milling method, which allows to apply high feed rates and increase machining efficiency. The method utilizes face cutters with a very small entering angle, of about 10°–20°. Thus, the cut layer cross-section is different than in traditional milling. In order to examine the high feed milling (HFM), experimental tests were conducted, preceded by an analysis of cutting zones when milling with an HF face cutter. The face milling tests of 42CrMo4 steel with the use of an HF cutter characterized by an entering angle, dependent on axial depth of cut ap and insert radius r values, as well as with a conventional face cutter with the entering angle of 45° were performed. The study focused on analyzing the vibration amplitude, cutting force components in the workpiece coordinate system, and surface roughness. The experimental tests proved, that when milling with constant cut layer thickness, the high feed cutter allowed to obtain twice the cutting volume in comparison with the conventional face cutter. However, higher machining efficiency resulted in an increase in cutting force components. Furthermore, the results indicate significantly higher surface roughness and higher vibration amplitudes when milling with the HF cutter.

Machinability of A356 cast alloys under the effect of artificial aging treatment and lubrication modes

This article discuss the effects of heat treatment and lubrication modes on the machinability of A356 alloy (Al–Si–Mg), the alloy is studied as-received, with solution heat-treated alloy (SHT) as well as with solution heat-treated and then aged at 155 °C, 180 °C, and 220 °C. In the course of machinability evaluation, several criteria including cutting force, surface roughness, tool wears, and burr analysis (chip) were studied. The results and analysis in this work indicated that selected machinability criteria are important and necessary to effectively evaluate the machinability of A356 alloys. Machinability of both materials and tool was estimated in terms of cutting force, chip thickness ratio and burr formation, flank wear, and roughness. The effects of different cutting parameters (cutting speed and feed rate) and lubrication modes (dry, mist, and wet) on the machinability of A356 cast alloy were also examined. The influence of heat treatments on the burr formation and surface quality was clearly revealed by the experimental results. Experimental work revealed that cutting forces were influenced significantly by aging and cutting speed. However, the different aging at 155 °C, 180 °C, 220 °C and the cutting speed significantly affected the machinability of A356 cast alloy. The results obtained show that for better drilling performance in terms of surface quality occurs at high feed rate, dry drilling, and artificial aging at T6.

Testing configurations of attractive toxic sugar bait (ATSB) stations in Mali, West Africa, for improving the control of malaria parasite transmission by vector mosquitoes and minimizing their effect on non-target insects

BackgroundApplication methods of |Attractive Toxic Sugar Baits (ATSB) need to be improved for wide-scale use, and effects on non-target organisms (NTOs) must be assessed. The goals of this study were to determine, at the village level, the effect of different configurations of bait stations to (1) achieve < 25% Anopheles mosquito vector daily feeding rate for both males and females and (2) minimize the effect on non-target organisms.MethodsDye was added to Attractive Sugar Bait Stations (without toxin) to mark mosquitoes feeding on the baits, and CDC UV light traps were used to monitor for marked mosquitoes. An array of different traps were used to catch dye marked NTOs, indicating feeding on the ASB. Stations were hung on homes (1, 2, or 3 per home to optimize density) at different heights (1.0 m or 1.8 m above the ground). Eight villages were chosen as for the experiments.ResultsThe use of one ASB station per house did not mark enough mosquitoes. Use of two and three stations per house gave feeding rates above the 25% goal. There was no statistical difference in the percentage of marked mosquitoes between two and three stations, however, the catches using two and three bait stations were both significantly higher than using one. There was no difference in An. gambiae s.l. feeding when stations were hung at 1.0 and 1.8 m. At 1.8 m stations sustained less accidental damage. ASB stations 1.8 m above ground were fed on by three of seven monitored insect orders. The monitored orders were: Hymenoptera, Lepidoptera, Coleoptera, Diptera, Hemiptera, Neuroptera and Orthoptera. Using one or two stations significantly reduced percentage of bait-fed NTOs compared to three stations which had the highest feeding rates. Percentages were as follows: 6.84 ± 2.03% Brachycera followed by wasps (Hymenoptera: Vespidae) 5.32 ± 2.27%, and Rhopalocera 2.22 ± 1.79%. Hanging the optimal number of stations per house for catching mosquitoes (two) at 1.8 m above ground, limited the groups of non-targets to Brachycera, Chironomidae, Noctuoidea, Rhopalocera, parasitic wasps and wasps (Hymenoptera). Feeding at 1.8 m only occurred when stations were damaged.ConclusionsThe goal of marking quarter of the total Anopheles population per day was obtained using 2 bait stations at 1.8 m height above the ground. This configuration also had minimal effects on non-target insects.

Experimental modeling and optimization of surface quality and thrust forces in drilling of high-strength Al 7075 alloy: CRITIC and meta-heuristic algorithms

Al 7075 is a renowned high-strength engineering material used in automotive and aerospace applications, wherein many functional cylindrical parts are subjected to internal or external loads. Engineered parts with form errors (cylindricity CE and circularity error Ce) result in undesirable vibration and high deformation in rotating parts. In addition, reduced surface roughness (SR) and thrust forces (TF) are essential to limit the secondary process (namely, polishing) and power consumption. Experiments are performed based on central composite design considering drilling parameters (point angle, cutting speed, and feed rate) as inputs and output performances as CE, Ce, TF, and SR. It is noted that, except feed rate for Ce, all other parameters are found significant toward the output performance. Also, prediction accuracy with ten random experimental cases resulted with the percent error of 8.4% for SR, 5.41% for TF, 10.64% for Ce, and 10.35% for CE, respectively. Continuous ribbon-like chips at higher cutting speed, loose fragmented chips at higher feed rate, and increased arc length and radius at higher point angle were observed from the chip morphology analysis. Criteria importance through inter-criteria correlation (CRITIC) method applied to determine the weight fractions for Ce, CE, TF, and SR was found equal to 0.2802, 0.1991, 0.3293, and 0.1914, respectively. Four algorithms (genetic algorithm GA, particle swarm optimization PSO, teaching learning-based optimization TLBO, and JAYA algorithm) were applied to determine the optimal drilling conditions. JAYA algorithm determined optimized drilling conditions ensure predicted output values found close to experimental values with an acceptable percent error of 10.8% for Ce, 8.9% for CE, 6.73% for SR, and 3.51% for TF, respectively.

Control of corrosion features by forming parameters

During forming operations, the microstructure of metal parts is usually changed. Effects of cold hardening result in different mechanical properties, whereas the deformed microstructure also changes the electromechanical properties. The latter is responsible inter alia for the chemical corrosion behavior in terms of breakdown potential. In this study, the principle of corrosion resistance of steel E355 (EN 10305-1) was analyzed after rotary swaging with the same nominal strain but different process settings. Especially higher feed rates (forming increments per stroke) and the additional application of shear strain by eccentric rotary swaging increased the pitting potential significantly and thus the corrosion resistance. The introduced methods are assumed as prospective candidates for industrial production of parts that provide higher durability without further anti-corrosion treatment.

Start-up of a “zero-discharge” recirculating aquaculture system using woodchip denitrification, constructed wetland, and sand infiltration

Recirculating aquaculture systems (RAS) discharge management limits the development of the aquaculture sector, because RAS do not automatically result in low nutrient emissions. Research has helped develop discharge management systems such as wetlands and woodchip bioreactors that have been adopted by Danish commercial model trout farms. To further develop the Danish concept, we have modelled and built a novel “zero-discharge” recirculating aquaculture system with an annual capacity of approximately 14 tonnes. The aim of this paper is to describe the entire concept and present the results from the start-up phase of the whole system. The concept includes the treatment of RAS effluent (overflow and sludge supernatant) using a hybrid solution of a woodchip bioreactor, constructed vertical wetland, and sand infiltration. Using this three-step process, the nitrate, phosphorus, and organic matter effluent are decreased to acceptable levels to reuse the water in the RAS process reducing the need for new raw water. In the first nine months of operation, a water treatment field was used as an end-of-pipe treatment to ensure the water was safe to recirculate for fish. During the winter, the water temperature dropped to 2.7 degrees in the sand filter, but the frost did not reach the water levels in any of the treatment processes. It therefore appears that a hybrid solution can operate sufficiently even in winter conditions. In the first year of operation, a woodchip bioreactor can remove 97 % of the nitrate, although the slow start-up of the RAS caused the bioreactor to be N-limited. On average, 79 % and 92 % of the inflow phosphate concentration was removed in the woodchip bioreactor and the entire hybrid treatment field respectively. The wetland and sand filter removed organic matter sufficiently (35 %), but because of the longer than designed actual water residence, it leached from the bioreactor more than was expected. Further experimentation is needed to identify the financial applicability and performance during higher feeding rates.

Diet of Exotic Pirapitinga Piaractus brachypomus (Cuvier, 1818) From Vembanad-Kole Wetland, India, as Inferred From Gut Content Analysis and DNA Barcoding

Gut contents of the exotic characid fish Piaractus brachypomus (Cuvier, 1818) that escaped into the Vembanad-Kole Wetland, India, during the floods were examined for their gut food spectrum. The qualitative analysis of gut contents showed that the fish is an omnivore with detritus (27 %) as the most dominant food item followed by, plant matter (25 %), crabs (16 %), molluscs (12 %), fish (11 %) and insects (7 %), respectively. DNA barcoding of the gut contents revealed taxa such as Puntius mahecola (Valenciennes, 1844) (Cyprinid fish), Bellamaya sp. (Mollusca, Gastropoda, Viviparidae), Spiralothelphusa sp. (Crustacea, Brachyura, Gecarcinucidae) and Ictinogomphus sp. (Insecta, Odonata, Gomphidae) among diet contents. Ontogenic diet shift was not recorded, and none of the fishes showed empty guts, indicating the higher feeding rate and abundance of food in the habitat. The most predominant food item of P. brachypomus in the Vembanad-Kol wetland system is crabs in terms of percentage occurrence, percentage number, percentage volume, index of preponderance, and index of relative importance. Piaractus brachypomus showed greater variations in diet spectrum from their frugivorous nature in the home range (Amazon basin) to a more generalist heterogeneous feeding nature in the introduced ecosystem. The study found that in a highly biodiverse ecosystem, the introduced alien fish may compete with native fish and feed on native organisms. The paper suggests a precautionary approach in flood plain aquaculture, especially with the increase in extreme climatic events and holistic studies on invasion biology to manage invasive species.

High performance peel grinding of steel shafts using coarse electroplated CBN grinding wheels

Grinding is widely known for its low material removal rates and high surface quality. However, recent developments in production processes for cubic boron nitride (CBN) abrasive grains have led to commercially available grain sizes larger than 300 µm. These superabrasive CBN-grains allow higher material removal rates during grinding of hardened steel components. Currently, these components are pre-machined with turning processes before hardening and finishing the work piece by grinding. However, the turning process can be eliminated by grinding with coarse CBN-grains since higher depths of cut are achievable when machining hardened components. This paper explores the limits of grinding wheels using grains with a size of B602 during soft and hard machining in comparison to conventional B252 grains. It is shown that the use of coarser grains leads to lower process forces, higher (tensile) residual stress and higher surface roughness. Residual stress and surface roughness are of less importance as these grains are to be used mainly in roughing operations with ensuing finishing operations for the required surface properties. Over all investigations, especially in hard machining, neither grain nor tool wear was observed for the B602 grains, whereas the B252 tool was severely clogged during the experiments. Additionally, the grinding force ratio indicates that the coarse grain tools have not yet reached their productivity limit as it increases over all investigated feeds. This indicates improving tool performance with lower amounts of rubbing for increasing feed rate during hard grinding and shows the potential for the industrial use of higher feed rates with larger grains.