Pouring Method Research Articles

A composite film of oxidized levan crosslinked with gelatin: strong hydrophobic and mechanical properties and effective preservation of fresh Mozzarella cheese.

The fructosan levan was synthesized in vitro using a recombinant levansucrase. The levan was oxidized with sodium periodate to prepare oxidized levan (OLevan) with three oxidation degrees. OLevan, gelatin (Gel), and gallic acid (GA) were used to prepare the composite films by the method of plate pouring. The analytical results of FT-IR and XPS indicated that OLevan and gelatin were covalently crosslinked through a Schiff base reaction. The crosslinked films had better properties compared to the non-crosslinked films, especially the Gel/GA/50%OLevan film. The film had the lowest swelling degree (44.4 %), while that of Gel/GA/Levan film was 352.6 %. Gel/GA/50%OLevan film also had the highest tensile strength (25.48 MPa), while that of Gel/GA film was 9.48 MPa. Also, Gel/GA/50%OLevan film was used as a packaging material of Mozzarella cheese. The film effectively slowed down changes in the texture and color of the cheese. On the first day, the coliform in the control and PE groups had already exceeded the maximum acceptable limit of cheese (2.0 Log CFU/g). However, that of Gel/GA/50%OLevan group reached the limit on the fifth day. The results show that the new film prepared by crosslinking and composite of natural edible materials has good potential as a safe food packaging material.

Determination of the energy efficiency of granulation equipment based on exergy analysis

The object of research is the process of granulation of mineral fertilizers by applying rolling and pouring methods, as well as in fluidized and suspended layers with active hydrodynamics of flows. It is noted that the development of the main technological stages of the production of granulated fertilizers should be aimed at improving the hardware design of granulators, establishing the most rational regime and technological parameters of the process in order to increase its efficiency and reduce energy costs. It is noted that the main indicators of the efficiency of granulation plants using heat are economic costs, exergy losses, as well as reduced costs. The method of exergy analysis for the assessment of energy costs for granulation processes in different types of granulators is presented, which allows to justify the choice of rational parameters of the specified processes, taking into account energy costs and equipment efficiency. Equations are presented for determining the amount of exergy of material flows and exergy losses caused by heat exchange at finite temperature differences of technological flows at the entrance to the device and at the exit from it. The equation for determining the exergy efficiency, which characterizes the energy efficiency of the technical system, is presented. The smaller the temperature difference for the technological flows at the exit from the device, the smaller the exergy losses, the higher the value of the exergy efficiency. and, accordingly, the device will have greater energy efficiency. An exergy analysis of granulation processes in granulation towers without a cooler, in granulation towers with a cooler, fluidized bed devices and multi-stage (shelf) devices was carried out. The analysis showed that the exergy efficiency for the specified granulation plants is equal to: 64 %, 71 %, 32 % and 96 %, respectively. The obtained research results can be applied in production conditions where granulation towers and devices of fluidized or suspended layers are used. Enterprises that plan to reduce energy costs and increase the environmental safety of their technological processes can implement improvements based on the proposed methods and equations. The application of research results will contribute to the selection of more rational indicators of the granule production process, which will increase the productivity and quality of the final product.

Study on the Shear Strength and Erosion Resistance of Sand Solidified by Enzyme-Induced Calcium Carbonate Precipitation (EICP).

Sand solidification of earth-rock dams is the key to flood discharge capacity and collapse prevention of earth-rock dams. It is urgent to find an economical, environmentally friendly, and durable sand solidification technology. However, the traditional grouting reinforcement method has some problems, such as high costs, complex operations, and environmental pollution. Enzyme-induced calcium carbonate precipitation (EICP) is an anti-seepage reinforcement technology emerging in recent years with the characteristics of economy, environmental protection, and durability. The erosion resistance and shear strength of earth-rock dams solidified by EICP need further verification. In this paper, EICP-solidified standard sand is taken as the research object, and EICP-cemented standard sand is carried out by a consolidated undrained triaxial test. A two-stage pouring method is adopted to pour samples, and the effects of dry density, cementation times, standing time, and confining pressure on the shear strength of cemented standard sand are emphatically analyzed. The relationship between cohesion, internal friction angle, and CaCO3 formation was analyzed. After the optimal curing conditions are obtained through the triaxial shear strength test, the erosion resistance model test is carried out. The effects of erosion angle, erosion flow rate, and erosion time on the erosion resistance of EICP-solidified sand were analyzed through an erosion model test. The results of triaxial tests show that the standard sand solidified by EICP exhibits strain softening, and the peak strength increases with the increase in initial dry density, cementation times, standing time, and confining pressure. When the content of CaCO3 increases from 2.84 g to 12.61 g, the cohesive force and internal friction angle change to 23.13 times and 1.18 times, and the determination coefficients reach 0.93 and 0.94, respectively. Erosion model test results indicate that the EICP-solidified sand dam has good erosion resistance. As the increase in erosion angle, erosion flow rate, and erosion time, the breach of solidified samples gradually becomes larger. Due to the deep solidification of sand by EICP, the development of breaches is relatively slow. Under different erosion conditions, the solidified samples did not collapse and the dam broke. The research results have important reference value and scientific significance for the practice of sand consolidation engineering in earth-rock dams.

Influence of primary interface characteristics on mechanical properties and damage evolution of coal-rock combination

Indirect fracturing technology of coal seam roofs is a crucial method to enhance coalbed methane extraction efficiency in broken soft coal seams. The cracks formed significantly increase permeability by extending from the rock-coal interface into the coal seam. The structural features of the coal-rock interface are pivotal in determining the path of crack propagation, highlighting the importance of studying the mechanical properties and damage evolution in coal-rock combinations. Industrial CT, three-dimensional (3D) reconstruction, and 3D printing technology are utilized to create physical models with authentic interface structure features. Subsequently, coal-rock combination samples exhibiting smooth and original interface characteristics are produced through a layered pouring method. Uniaxial compression experiments are conducted on various interface feature combinations to examine the impact of primary interface structure characteristics on the mechanical properties and damage evolution of the combinations. Real-time monitoring is performed using acoustic emission (AE) equipment. The results show that the compressive strength of coal-rock combinations treated with glue and pouring is significantly higher than those treated with vaseline, while the axial strain shows an opposite trend. The presence of an interface constraint effect weakens the strength of the rock near the coal-rock interface, while enhancing the strength of the coal. The damage in coal-rock combinations initially occurs in the middle and lower parts of the coal, then progresses towards the interface and rock. Finally, a uniaxial compression model considering the interface constraint effect explains and theoretically demonstrates the phenomenon observed in the experiment, where more complex coal-rock interface structures result in higher compressive capacities of samples. It provides insights for further investigation into fracture trans-media expansion and permeability enhancement during the indirect fracturing of coal seam roofs.

Designing prepacked aggregate concrete for improved mechanical properties and its field application in constructing steel tube concrete

Prepacked aggregate concrete (PAC) is made by placing coarse aggregates of various sizes into a formwork and then filling the voids between coarse aggregate and grout. The mechanical performance of PAC is dominated by the compactness due to grout filling, but few study considered the pouring methods and grout performance synchronously. The coupled effect of pouring methods and grout performance on the compactness of PAC is investigated in this study. The results show that the gravity pouring method is only suitable for grouts with good flowability. The pump pouring method is more widely used. It can be adapted to grout with poorer fluidity and coarse aggregate with greater apparent density. The ultrasonic pulse velocity test method provides a relatively accurate evaluation of the compactness of PAC. Furthermore, due to the enhanced mechanical properties of PAC, the filed application potential in the preparation of steel tube concrete columns has also been confirmed, where the results exhibited that PAC based steel tube concrete contributed to an enhanced ductility and autogenous shrinkage.

On the question of hardening of a slug poured along the wall of a rotating mold

A comparative analysis of metal pouring into rotating molds using the siphon method and top pouring was performed. A new top pouring method is proposed to reduce defects of shrinkage origin: looseness, central porosity, liquation, etc. The method is based on rotating the mold during pouring around its axis or moving a metal melt stream relatively to the rotating mold. The peculiarity of the process is that steel pouring is carried out along the inner wall of the mold. The results of experimental cold physical modeling are presented. A glycerol solution was used as a model liquid. The results of cold modeling showed that implementing the proposed pouring method results in temperature losses averaging up to 5%. Taking into account the scale factor, higher values can be expected in a real process.

On the question of hardening of a slug poured along the wall of a rotating mold

A comparative analysis of metal pouring into rotating molds using the siphon method and top pouring was performed. A new top pouring method is proposed to reduce defects of shrinkage origin: looseness, central porosity, liquation, etc. The method is based on rotating the mold during pouring around its axis or moving a metal melt stream relatively to the rotating mold. The peculiarity of the process is that steel pouring is carried out along the inner wall of the mold. The results of experimental cold physical modeling are presented. A glycerol solution was used as a model liquid. The results of cold modeling showed that implementing the proposed pouring method results in temperature losses averaging up to 5%. Taking into account the scale factor, higher values can be expected in a real process.

Seismic behavior of precast segmental bridge columns confined by grouted glass fiber reinforced plastic tubes

The application of precast segmental bridge columns (PSBCs) is still restricted in seismicity areas due to concerns such as lower lateral stiffness and column base bearing capacity. To enhance the applicability of PSBCs, this study proposed a novel approach of confining them with grouted GFRP tubes. Four novel and one reference specimens were tested under low cyclic loading to evaluate the effects of energy dissipation (ED) bars ratios, concrete interlayer strength, type of segment concrete, and concrete pouring methods within the outer GFRP tube (OGT) on the seismic behavior. Experimental results reveal that the failure modes of all specimens were triggered by the yielding of ED bars and the break of OGT at the top of ED bars. No crushed concrete at column bases or cracks at the segment joint were observed during the test due to the good confinement of GFRP tubes. All the specimens exhibited stable hysteretic behavior with small residual drift ratios and low strength degradation. Furthermore, finite element models (FEMs) were generated to predict the hysteretic behavior of novel specimens. The effects of some parameters such as OGT thickness, ED bars diameter, and concrete strength were further studied.

Real-time monitoring of pork freshness using polyvinyl alcohol/modified agar multilayer gas-sensitive labels

Accurate consumer perception of food packages should provide real-time feedback on any changes inside food packaging. Hence, a new multilayer gas-sensitive label (POA-12) was prepared using a layer-by-layer pouring method for simple, visual, and real-time detection of pork's freshness, while the front side was developed by immobilizing red carbon dots and fluorescein isothiocyanate in POA as indicator for volatile nitrogen, and the back side was created using bromothymol blue in POA as pH indicator. The swelling index of the multilayer gas-sensitive labels reduced from 159.19% to 148.36%, and the tensile strength increased from 25.52 MPa to 42.61 MPa. In addition, the POA-12 multilayer label showed a red-to-yellow fluorescence change as TVB-N increased from 6.84 to 31.4 and a yellow-brown-to-blue-green color change as pH increased from 5.74 to 7.24 when detecting pork samples. Thus, it provides dual-indicator monitoring that improves the accuracy and reliability of assessing the freshness of high-protein products.

Use of Blood Powder (Ground and Irradiated) for the Manufacture of Chocolate Agar.

Chocolate agar (CA) is an enriched medium for the isolation and identification of fastidious bacteria. Defibrinated blood is used to manufacture CA, but this expensive product is not always affordable for companies in developing countries. Blood powder (BP) is potentially a cheaper alternative, although its pre-treatment using autoclaving can impair the quality of the media. Therefore, optimization of BP as a substitute for defibrinated blood for CA manufacture deserves further research. CA was manufactured with irradiated BP (dehydrated bovine blood powder) and its physical and microbiological characteristics were compared with those of conventional CA and CA prepared with autoclaved BP. Each medium was seeded with 20-200 CFU of target bacteria using the spiral pouring method. Finally, another medium was prepared using BP pre-treated by grinding and gamma irradiation and its performance assessed. Compared to conventional CA, the medium containing ground and irradiated BP provided a similar CFU count for both fastidious (Neisseria, Haemophilus, Campylobacter, and Streptococcus) and non-fastidious (Moraxella, Staphylococcus, Enterococcus, Klebsiella, and Pseudomonas) species, unlike the medium prepared with BP subjected only to irradiation, which provided a lower growth of fastidious species. Morphology and characteristics of all bacterial colonies were very similar in conventional CA and the new medium, the number of Pseudomonas CFU being higher in the latter. The medium prepared with ground plus irradiated vs. irradiated BP more closely resembled conventional CA, having a browner background. The new CA medium prepared with ground and gamma irradiation-sterilized BP has comparable productivity properties to conventional CA. Therefore, it could be a more practical and economical methodology to facilitate large-scale CA manufacture.

Influence of Reactive Amine-Based Catalysts on Cryogenic Properties of Rigid Polyurethane Foams for Space and On-Ground Applications.

Rigid polyurethane (PUR) foams have outstanding properties, and some of them are successfully used even today as cryogenic insulation. The fourth-generation blowing agent Solstice® LBA and commercial polyols were used for the production of a low-density cryogenic PUR foam composition. A lab-scale pouring method for PUR foam preparation and up-scaling of the processes using an industrial spraying machine are described in this article. For the determination of the foam properties at cryogenic temperature, original methods, devices, and appliances were used. The properties at room and cryogenic temperatures of the developed PUR foams using a low-toxicity, bismuth-based, and low-emission amine catalyst were compared with a reference foam with a conventional tin-based additive amine catalyst. It was found that the values of important cryogenic characteristics such as adhesion strength after cryoshock and the safety coefficient of the PUR foams formed with new reactive-type amine-based catalysts and with the blowing agent Solstice® LBA were higher than those of the foam with conventional catalysts.

Multi-dimensional functionally graded insulator for HVDC compact gas insulated apparatus

Gas insulated switchgear may be exposed to AC-DC mixed voltages in bipolar high voltage direct current (HVDC) systems. To improve the insulation performance of the epoxy insulator, this paper develops the multi-dimensional functionally graded materials (MFGM), which combines the bulk permittivity graded materials (ϵ-FGM) and the surface nonlinear conductivity materials (SNCM). The ϵ-FGM bulk and the SNCM layer of the MFGM insulator were prepared by the layer-by-layer pouring method and the air spraying technology. Results show that the electric field strength of the MFGM insulator around the HV triple junction is reduced by over 37% and 39% under AC and DC voltages. Compared with the uniform insulator, the AC and the DC flashover voltages of the MFGM insulator are raised by 17.5% and 27.5%, respectively. The MFGM insulator can adapt to both stationary and transient conditions, and thus has a promising application in HVDC compact gas-insulated apparatuses.

Synergistic Effect of HEDP.4Na and Different Induced Pouring Angles on Mechanical Properties of Fiber-Reinforced Alkali-Activated Slag Composites

The poor flexural and damping properties of building materials damages concrete structures and affects their service life when concrete structures are subjected to dynamic loads. Three different dosages (i.e., 0%, 0.3%, and 0.6%) of organic phosphonates (HEDP.4Na) and different pouring methods (i.e., conventional pouring method, 90°-induced pouring method, and 150°-induced pouring method) were designed to improve the flexural and damping performance of fiber-reinforced alkali-activated slag composites (FR-AASC). The enhanced mechanism of HEDP.4Na was revealed by phase analysis (X-ray diffraction, XRD), pore structure analysis (Mercury Intrusion Porosimetry, MIP), the heat of hydration, and scanning electron microscopy (SEM) analysis. The results showed that 0.3% HEDP.4Na combined with the 150°-induced pouring angle can significantly improve the mechanical properties of the FR-AASC sample compared with the reference group. The sample with 0.3% HEDP.4Na cast by the 150°-induced pouring angle increased compressive and flexural strength, damping energy consumption and storage modulus by 20%, 60%, 78%, and 30%, respectively, compared with the reference sample cast by the conventional pouring methodology. HEDP.4Na reduced the early hydration heat and total porosity of the FR-AASC matrix, modified the fiber–matrix interface transition zone, and increased the frictional energy consumption of steel fibers. Overall, the synergistic effect of HEDP.4Na and the induced pouring methodology significantly improved the flexural and damping properties of FR-AASC. This study can provide a guidance for improving the flexural and damping capacity of FR-AASC and promote the application of FR-AASC in construction engineering.

Preparation, Characterization, and Evaluation of Cytotoxicity of Fast Dissolving Hydrogel Based Oral Thin Films Containing Pregabalin and Methylcobalamin

The oral availability of many drugs is problematic due to the pH of the stomach, enzymes, and first-pass effects through the liver. However, especially geriatric, pediatric, bedridden, or mentally handicapped patients and those with dysphagia have difficulty swallowing or chewing solid dosage forms. Oral Thin Films (OTFs) are one of the new drug delivery systems that can solve these problems. Pregabalin (PG) and Methylcobalamin (MC), which are frequently preferred for pain originating in the central nervous system, were brought together for the first time using OTF technology in this study. In this study, a quantification method for PG and MC was developed and validated simultaneously. Optimum formulations were selected with organoleptic and morphological controls, moisture absorption capacity, swelling capacity, percent elongation, foldability, pH, weight variability, thickness, disintegration time, and transparency tests on OTFs prepared by the solvent pouring method. Content uniformity, dissolution rate, determination of release kinetics, SEM, XRD, FT-IR, DSC, long-term stability, and cytotoxicity studies on the tongue epithelial cell line (SCC-9) were performed on selected OTFs. As a result, OTFs containing PG-MC, which are non-toxic, highly flexible, transparent, compatible with intraoral pH, with fast disintegration time (<30 s), and acceptable in taste and appearance, have been developed successfully.

A large-sized thermoelectric module composed of cement-based composite blocks for pavement energy harvesting and surface temperature reducing

Roads carry a lot of green and renewable energy. Thermoelectric cement as a green material can convert thermal energy to electrical power by using the temperature difference between the road surface and the underground. Cement-based materials can meet the needs for large-scale application in pavements because of their wide source, low cost, and good mechanical properties. Due to the preparation of large-size thermoelectric cement materials, the thermoelectric performance will be reduced, but the existing thermoelectric cement materials with excellent thermoelectric performance are small in size and they cannot be used for large-area applications. It is still a problem that thermoelectric properties of large-size thermoelectric cement-based composites prepared by the traditional pouring method are prone to dry shrinkage crack. Herein, to solve the problem of poor thermoelectric properties of large-sized thermoelectric cement materials. A thermoelectric cement block prepared by dry pressing is reported to be assembled into a large thermoelectric module of cement-based composite more suitable for pavement energy harvesting. The thermoelectric cement block is 50mm × 50mm × 20 mm, and the size of assembled into a large thermoelectric module is 300mm × 300mm × 35 mm. The addition of expanded graphite and metal oxides raised the average conductivity of the cement blocks to 0.63 S/cm and the average Seebeck coefficient to 20.79 μV/K, respectively. Tests have found that using a series connection of thermoelectric conversion modules can yield higher energy. Compared to other pavement thermoelectric generator (TEG) energy harvesting systems, the thermoelectric modules are less expensive and allow for large areas to be laid on the pavement. The module assembled using thermoelectric cement-based composite materials can generate 0.5 kW h of energy for 24 h on a road with a length of 1 km and a width of 10 m. Meanwhile, the thermoelectric module of cement-based composite has the ability to reduce the surface temperature and mitigate the urban heat island effect. The test results showed that it can reduce the temperature by 1°C–3°C. The results of this study provide a reference for future large scale practical applications of thermoelectric cement-based composites.

Design of carbon aerogels with variable surface morphology for electromagnetic wave absorption

Carbon-based materials, as one of the most important electromagnetic wave absorbing materials, face the main problem of narrow effective absorption bandwidth. Here, carbon aerogels modified by carbon microspheres with different morphologies were prepared by controlling reaction parameters and carbonization process. The integral pouring method was proposed to test the electromagnetic parameters for the first time, which retained the skeleton structure of carbon aerogels. The complete skeleton and unique surface morphology significantly improve the electromagnetic wave absorption performance of carbon aerogels. At a low filling rate (7.7%), the effective absorption bandwidth is 8.47 GHz at 3.0 mm. The reflection loss absorption rate reaches 99.6%, meeting the requirements of efficient electromagnetic wave absorbing materials with wide bandwidth, thin thickness, and light weight.

Application of Automatic Colony Counter in the Detection of Dairy Products

Objective: To improve the counting efficiency and realize the traceability of raw data. The applicability, accuracy, precision and repeatability of the automatic colony counter were verified by experiments, Determine the applicability of colony count in the detection of dairy products and raw and auxiliary materials. Methods: The plate pouring method and test piece method are selected for verification test, including psychrophilic bacteria, aerobic spores, thermophilic aerobic spores, lactic acid bacteria count, total number of colonies, coliform, mold, yeast, Staphylococcus aureus and other items. The manual count is compared with the automatic colony counter to determine its feasibility, applicability and accuracy. Results: The colony count of normal Petri dish without background interference was compared with that of 3M test piece. The paired t-test was carried out by visual method and instrument method, <I>P </I>= 0.17, greater than 0.05. There was no significant difference in statistical results, and the colored medium had no significant effect on automatic counting. The counting effect of the instrument is poor when there are needle shaped colonies, the color of colonies is close to that of the culture medium, the contour of colonies is not obvious, the colonies spread greatly and the edges of colonies are irregular, there are food particles and colonies in the culture medium at the same time, or the color of colonies is close to that of food particles, which can not meet the accuracy requirements. Conclusion: For samples with uniform texture, the accuracy and precision of automatic colony counting are relatively good, the work efficiency is high, the operation time of experimental personnel is saved, and the original experimental data and images can be stored in the instrument for a long time. It is a counting method worthy of popularization in the laboratory. However, for the samples and culture medium with interference in the test verification, appropriate measures can be taken to change the counting conditions and manually correct the counting results of the instrument, but the counting efficiency will be reduced, and the laboratory can choose to use it according to the situation.

Integrated Construction Technology of Large-Scale Floor Structure and Decorative Surface

In order to solve the many deficiencies in the construction method of secondary pouring of large-scale floor decoration surface layer, this paper proposes the integrated construction method of large-area floor plate structure and decorative surface layer, and clarifies the principle, main technological process and quality of construction process of this construction method. Control points, on the basis of comparison with the traditional secondary pouring method, the advantages of the integrated construction method are clarified. The research results show that the integrated construction method can save cost and construction period, and can achieve that the surface layer after construction is not hollow, cracked, flat, wear-resistant, and dust-free. The construction process is low-carbon and environmentally friendly, and it is worthy of follow-up. It is popularized in the construction of large-scale floor decoration surface layer.

Experimental study of heat transfer between fluid flowing through fracture surface with tortuous seepage path

Under the dual challenges of energy demand and environmental protection, geothermal energy has broad application prospects because of their cleanliness and huge reserves. Understanding the flow and heat transfer process of fluid flowing through fractured rock is of importance for the utilization of geothermal resources. A more practical calculation equation for convective heat transfer coefficient is derived based on Newton's cooling equation and previous research. Samples with different seepage paths were prepared through 3D printing technology and cement mortar pouring method. The effect of seepage path tortuosity, aperture, and initial temperature on the characteristics of heat transfer were analyzed and discussed by conducting the seepage and heat transfer test. The experimental results show that the overall convective heat transfer coefficient of sample with seepage path are lower than those of sample with smooth fractures. The greater the tortuosity of seepage path, the greater the overall convective heat transfer coefficient. In addition, the correlation of tortuosity and C, n in the characteristic number equation is proposed, providing significant parameters for the study of hydraulic-mechanical-thermal coupling when fluid flowing through rock mass with high temperature.

Experimental Study on Optimization of Cementation Solution for Wind-Erosion Resistance Using the MICP Method

In the present study, an environmentally friendly microbial-induced calcium carbonate precipitation (MICP) technique was explored to reinforce the desert sand using the stopped-flow pouring method. A detailed experimental study has been conducted with Sporosarcina (S.) pasteurii urease-producing bacteria with a 0.5 M cementation solution. To optimize the cementation solution, three different pore volumes (PV), i.e., 0.4, 0.6, and 0.8, were considered. The cementation solution was provided every 24 h and considered as one treatment cycle. The cylindrical specimen in three replicas was biotreated for 7, 14, and 21 days in 1:1 and 1:2 (diameter: height) ratios for determina-tion of split-tensile strength (STS) and unconfined compressive strength (UCS), respectively. Micro-structure characterization of untreated and biotreated sand was also examined using a scanning electron microscope (SEM) and energy-dispersive X-ray analysis (EDX). Rocklike behavior was ob-served for biotreated-sand samples using the UPV test. Test results for 21 days with 0.8 PV were 1340 kPa, 241 kPa, and 1762 m/s for UCS, STS, and UPV, respectively, with an average calcite content of 16.2%. Overall, the 0.5 M cementation solution with a 24 h treatment cycle, 0.8 PV with 7 days, and 0.4 PV with 14 days gave optimum treatment solution, and showed heavily cemented and rock-type behavior of the biotreated-sand sample.