Higher Specific Volume Research Articles

Study on Physicochemical Properties and Rock-Cracking Mechanism of High-Energy Expansion Agent

Aiming at the shortcomings of the current rock-breaking technology, a new type of high-energy expansion agent for energetic materials based on combustion-to-detonation was developed. By characterizing the basic physical and chemical properties of the high-energy expansion agent (HEEA) such as morphology, particle size distribution, and pyrolysis characteristics, the work performance of different types of high-energy expansion agents was analyzed in combination with the energy characteristics. The results showed that the relationship between the expansion work done by the gas to the outside world was WHEEA-I > WHEEA-II > WHEEA-III under the same quality of HEEA combustion. The damage effect of high-temperature and high-pressure gas cracking specimens generated by deflagration of HEEA was obvious, having the rule that the disturbance damage of rock caused by low heat and high gas specific volume was smaller, and the damage degree of rock caused by high heat and low gas specific volume was larger. The mechanism of HEEA combustion and detonation in confined space is revealed, which provides a theoretical basis for the application of HEEA-cracked rock.

Preparation and electrochemical application of porous carbon materials derived from extraction residue of Ganoderma lucidum

As a valuable biomass resource, a large number of Chinese medicine residue have not been effectively utilized and are often treated as garbage, which not only causes environmental pollution, but also leads to the waste of resources. Ganoderma lucidum is a common raw material of Chinese herbal medicine, its natural mycelium and tube structure is conducive to the formation the porous structure of carbon materials. In this paper, porous carbon materials with high specific surface area and high pore volume were prepared by high temperature carbonization in nitrogen atmosphere using Ganoderma lucidum residue as a raw material and KOH as an alkali activator. The morphology and pore structure of the prepared carbon materials were analyzed and characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction, Raman spectroscopy and nitrogen adsorption method. When the mass ratio of carbon to alkali was 1:4 and the temperature was 800 °C, ultra-high specific surface area microporous carbon materials were obtained with specific surface area of 3425 m3 g−1 and total pore volume of 1.74 cm3 g−1. The prepared porous carbon material was assembled into hydrogen peroxide electrode and cholesteric oxide modified electrode, which showed good catalytic performance.

Mesoporous manganese dioxide prepared by nano-casting: An efficient catalyst for of methyl orange and oxalic acid degradation in aqueous solution

In the present study, mesoporous manganese dioxide catalysts with large high specific surface area, pore volume and large pore size structure were synthesised using the nano-casting method with a mesoporous structure of silica SBA-15 as a hard template. Therefore, the physical and chemical properties of mesoporous MnO2 were characterised by XRD, FT-IR, Raman, UV–Vis, N2 adsorption-desorption, SEM, EDS, TEM, TG and XPS. In this study, the oxidative reactivity of MnO2 corresponding to methyl orange (MO) and oxalic acid (OA) was assessed. MnO2 was found to contain the most abundant oxygen vacancies and easily reducible surface adsorbed oxygen (Olatt), which facilitates the catalytic utilisation of ozone. As a result, the highest catalytic performance was achieved for methyl orange and oxalic acid, with degradation efficiencies of 98.37% and 92.96%. This present study deepens our understanding of manganese dioxide catalyzed ozone and provides a reference for improving process efficiency.

Rationalizing nitrogen-doped secondary carbon particles for practical lithium-sulfur batteries

Nanostructured carbon host materials are widely used to improve both sulfur utilization rate and reaction kinetics in lithium-sulfur (Li-S) batteries. However, high complexity/cost of materials synthesis and difficulty in processing nano-materials into high-mass-loading electrodes are still significant barriers to the development of low-cost and high-energy Li-S batteries. In this study, we reported a generic and scalable synthesis approach to prepare nitrogen-doped secondary carbon particles. By using nitrogen-containing precursor as an integration reagent, the nanosized Ketjen Black particles were integrated into micron-size secondary ones and nitrogen-doped (NKB) simultaneously through a one-step heat treatment. With NKB as an example material, the effects of particle integration degree on the secondary particles’ structures, pore volume and connectivity, sulfur loading capability, and cell performance were studied and discussed. At an optimal integration condition, the NKB particles had significantly improved particle dimensions with well-maintained high specific surface area and pore volume. Contributed by the micron size and high pore volume, the NKB/S were successfully used for high-sulfur-loading cathode coating (4–7 mgs cm−2) and were able to deliver a specific capacity of ∼1100 mAh g−1 at a practical low-porosity (50 %) and lean-electrolyte conditions (E/S =4 µL mg−1). Feasibility of the materials for practical use was validated through scaling up synthesis (40 g/batch), large-area electrode coating, and practical pouch cell (1.6 Ah) assembly and test.

Relation between hydration level and quality of steamed oat cakes: from the view of batter rheological properties

SummaryThe effects of hydration level on the rheological properties of oat batters and quality of steamed oat cakes were evaluated. With the increase in hydration level, the apparent viscosity was sharply decreased from 18.47 to 7.08 Pa⋅s, and the frequency sweep results suggested an increasing fraction of uncross‐linked component in oat batter. The water fluidity was enhanced, and the cross‐linking of proteins were weakened, resulting in loose batter structure. Apparent viscosity and microstructure analysis suggested that the gas chamber size was negatively correlated with the viscosity. Large gas chamber formed by low viscosity batter was unstable, resulting in steamed oat cakes collapsed. Besides, a highly viscous batter resulted in excessive cross‐linking and restricted gas expansion. Medium viscosity of oat batter, 15.28 Pa⋅s, with 110% water addition resulted in highest specific volume, cell area fraction and minimum hardness, 2.22 mL g−1, 34.73% and 7.61 N, respectively.

Polyolefin-based electrospun fibrous matrices embedded with magnetic nanoparticles for effective removal of viscous oils.

In this work, we present a poly (ethylene-co-1-octene)-based fibrous matrix prepared via electrospinning for highly efficient removal of viscous oils. The sorbent consisting of linear low density polyethylene (LLDPE) allows selective absorption of crude oil spills at the water surface without the need for additional isolation of the matrix prior to the refining process. Moreover, the high specific pore volume of the LLDPE sorbent with uniform fibrous morphology was shown to enable the sorbent reach 81.5±5.9% of its equilibrium absorption capacity within 5min. Furthermore, magnetic nanoparticles (MNP) are incorporated into each fiber comprising the matrix to facilitate the recovery process via external magnetic field without altering the intrinsic absorption capacity. We envision that these sorbents offer a sustainable route for the quick and thorough clean-up of spilled oil due to their high absorption capacity, fast absorption rate, ease of recovery, and absence of secondary waste.

Screen-Printed Microcantilevers Coated With Functionalized Mesocellular Foam Silica for Detection of Solvent Vapors

This work presents an application of mass-sensitive microcantilevers coated with a new alternative of sensitive materials that is hexamethyldisilazane functionalized mesocellular foam silica (HMDS-MCF-Si) for detection of solvent vapors. The microcantilevers (3 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times2$ </tex-math></inline-formula> mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times0.1$ </tex-math></inline-formula> mm) based on a lead zirconate titanate (PZT) beam sandwiched by thin gold (Au) electrodes were fabricated by screen-printing. Mesocellular foam silica (MCF-Si) was synthesized and used as the sensitive material due to its high specific surface area and pore volume. This material was functionalized by hexamethyldisilazane (HMDS) to enhance hydrophobicity. By a small deposition of HMDS-MCF-Si, the obtained devices demonstrated longitudinal vibration mode with the quality factor of approximately 200 at ambient temperatures. Responsiveness of the microcantilever coated with HMDS-MCF-Si to each solvent vapor at room temperature was compared. The largest response was obtained from exposure to toluene vapor with the sensitivity of 0.85 ppm/ppmV (218 mHz/ppmV) and a limit of detection (LOD) of 28 ppmV. The sensitivity dropped by almost six times when exposed to the higher polar vapor of ethanol. Very low response to water vapor (0.05 ppm/ppmV) confirmed the hydrophobic behavior of HMDS-MCF-Si. Detectable performances under different vapors of our device can be utilized as a guide for developing sensitive materials and resonant microcantilever-based vapor sensors.

Carbon spheres prepared by amino acid-catalyzed resorcinol-formaldehyde polymerization for supercapacitors

Carbon spheres (CS) have been widely used in supercapacitor due to their uniform structure and high surface area. The final properties of CS are affected by both the synthesis conditions and the preparation of precursors. Herein, a simple and green method to catalyze resorcinol/formaldehyde polymerization with catalysis of amino acids was proposed. As the reaction progressed, the amino acid molecules were consumed through the interaction with resorcinol, indicating that it can successfully catalyze the resin polymerization. The L-arginine catalyzed CS shows favorable characteristics for electrochemical energy storage, such as high specific surface area (416 m2 g−1) and high pore volumes (0.24 cm3 g−1). As the electrode material of supercapacitors, it has high specific capacitance of 235 F g−1 at 1 A g−1, excellent rate performance and long-term stability in 6 M KOH As an electrode material, after 10,000 cycles of testing, it can still retain 97.46 % of the initial capacity.

Impact of drying methods on banana flour in the gluten-free bread quality

Green banana flour (GBF) is considered a functional ingredient that could improve banana world's production sustainability. The banana drying method might influence the physicochemical and nutritional properties of GBF, affecting its performance in bread-making. The study aims to determine the impact of freeze-drying and oven-drying on gluten-free banana bread's quality. Freeze-dried banana flour (FDBF) bread had higher specific volume, resilience, and less brown coloration than oven-dried banana flour (ODBF) bread. Also, FDBF bread presented higher resistant starch (RS). The slowly digested starch (SDS) was similar in both types of bread. In contrast, rapidly digested starch (RDS) was significantly higher in FDBF bread, which led to higher expected glycemic index. Even though the nutritional fractions (RS and SDS) of both gluten-free banana bread exceeded 20 g/100 g bread (db), with no significant difference concerning the drying type, the FDBF bread presented improved characteristic.

THE EFFECT OF THE ADDITION OF VARIOUS TYPES OF OILS ON THE TECHNOLOGICAL QUALITY OF WHEAT DOUGH AND BREAD

The aim of this work was to evaluate the effect of the addition (0.5 %, 1 % and 1.5 %) of vegetable oils (pumpkin, rapeseed and sunflower oil) on the technological quality (rheological properties of dough, bakery indicators and bakery experiment) of wheat dough and subsequently wheat bread. The wheat flour type T 650 was used as a base and also control. In this type was determined a dry matter of 86.65 %. By determining the bakery indicators (crude protein content, falling number, starch content, ash content, titratable acidity and Zeleny index) it is possible to summarize that this type of four was strong. The gluten properties of T 650 flour were optimal and suitable for bakery use. The specific volume, volume yield, bulk productivity, bread yield, loss during baking and shape were determined by a baking experiment. The highest specific volume was determined in a bread loaf with the addition of 1.5 % pumpkin oil – 424.2 cm3.100 g-1. The volume of prepared breads increased with oil addition – the highest value was determined in sample with the addition of 1.5 % sunflower oil (volume increase of 24 % with compared to the control variant without addition. The shape of prepared breads was optimal; the bulk productivity increased in direct proportion to the addition of individual oils. The addition of vegetable oils had a beneficial effect on the rheological properties of the dough. The farinograph properties were good, but in the wheat dough with the addition of rapeseed oil, the development time of the dough gradually decreased. After the addition of pumpkin oil, it was determined development time of the dough (the difference between the maximum and minimum) higher by 55 % with compared to the control variant without addition. It was also recorded positive results for the evaluation by the extenzograph properties. By a comprehensive evaluation, it can be stated that the addition of vegetable oils had positive effects on wheat dough and prepared bread.

Insulating Material Development for the Design of Standoff Insulators Fed by Hybrid Voltage.

Innovative electrical assets are being developed in transmission and distribution, as well as in electrified transportation, from ships to aerospace. In general, power electronics have to master the whole power supply, being the driver of high specific power, low weight and volume components, in addition to enabling flexible and highly variable power flow. In these conditions, electrical and electronic insulation systems will have to withstand new types and levels of electric stresses, while still maintaining its reliability throughout its whole design life. This paper presents a study on the interrelation between insulating material properties and surface field of standoff insulators. The aim is mainly to provide indications on material properties which can be tailored to provide a robust, reliable and optimised insulator design that will hold for any type of electrical stress the insulation will have to withstand during operation. Specifically, we focus on ac and dc supply, including voltage transients, which could feed the same insulator depending on operation, according to a hybrid asset paradigm. The challenge is, indeed, to establish a pattern to material and insulation system design which takes into account the differences between the types of electrical stress profile and magnitude when insulators are supplied either in a dc or in ac, in order to infer which type of material characteristics would be more appropriate for the sake of life and reliability. The main contribution of this paper is to show that engineering the values of bulk and surface conductivity (which can be done selecting appropriate materials or modifying them, e.g., by nano-structuration) and modelling surface discharge inception would allow the electric field profile to be stabilised whatever the shape of the applied waveform. This will enable us to reach a reliability target that not only accounts for macroscopic phenomena, but also for the likelihood of extrinsic accelerated aging mechanism occurrence as partial discharges. In such a way, optimization of conditions to improve life, reliability, design and creepage and clearance characteristics can be achieved.

Biomass-Based N-Rich Porous Carbon Materials for CO2 Capture and in-situ Conversion.

Capturing CO2 and subsequently converting into valuable chemicals has attracted extensive attention. Herein, a series of biomass-based N-rich porous carbon materials with high specific surface area and pore volume were prepared using biomass waste soybean dregs as precursors. The nitrogen content was up to 4 % with different forms in the carbon skeleton such as pyridine-N, pyrrole-N. The synergistic effect of ultra-micropore (pore size <0.7 nm) and N-containing groups endowed the materials with a high CO2 adsorption capacity, reaching 6.3 and 3.6 mmol g-1 at 0 and 25 °C under atmospheric pressure, respectively. In addition, the sufficient interaction between N-containing groups and CO2 was demonstrated by solid-state nuclear magnetic resonance spectroscopy, and the captured CO2 was possibly activated in the form of carbamate, which is conducive to subsequent conversion. Therefore, the supported catalyst with the as-synthetic porous carbon material as the carrier and ZnII as catalytic sites was prepared and successfully applied for carboxylative cyclization of propargylic amine with CO2 to afford the 3-benzyl-5-methyleneoxazolidin-2-one. The results showed that CO2 capture and in-situ conversion work effectively to produce highly value-added chemicals. In this process, the captured CO2 could be activated and fixed into chemicals in mild conditions. More importantly, the energy consumption in CO2 desorption and adsorbent regeneration could be avoided. The valorization of both solid waste and CO2 to valuable chemicals provides an elegant strategy of killing three birds with one stone.

POROUS CARBON FROM PINEAPPLE PEEL AS ELECTRODE MATERIAL OF SUPERCAPACITOR

Porous carbon from biomass has a great potential to be developed. Biomass as a resource is renewable, abundantly available, and cheap. One application of porous carbon is as an electrode material of supercapacitor due to its advantageous pore properties such as high specific surface area and pore volume. This research prepared porous carbon material from pineapple peel waste and tested it as a supercapacitor electrode. The research steps were material preparation, conversion of pineapple peel to porous carbon, and characterization, including material characterization and electrochemical characterizations. Pineapple peel (under 80 mesh size) was pre-carbonized by hydrothermal method at 1900C for 2 hours under a subcritical condition. After that, biochar was pyrolyzed at 9000C and activated using CO2/N2 (KB-900-50). As a reference, biochar was also pyrolyzed under a nitrogen atmosphere at 9000C without activation (KB-900). Produced porous carbon was characterized (i) pore structures, e.g., specific surface area, average pore diameter, and total pore volume using N2-sorption analysis, and (ii) electrochemical performance, e.g., cyclic voltammetry and galvanostatic method using 1 M H2SO4 electrolyte solution. The result showed that the activation process effectively increased the porosity of porous carbon. Material (KB-900-50) possesses a high surface area of 648 m2/g and a high capacitance value of 78 F/g.

Efficient Sodium Storage in Selenium Electrodes Achieved by Selenium Doping and Copper Current Collector Induced Displacement Redox Mechanisms

AbstractSelenium (Se), with its high specific volume capacity and high electronic and superior kinetics, is considered a promising electrode material with promising applications. However, the solvation and shuttle effects of polyselenides hinder their further application. The selenium/nitrogen‐doped hollow porous carbon spheres (Se/NHPCs) are obtained using the sacrificial template and in situ gas‐phase selenization methods. The Se species are doped into carbon matrixes in an adjustable amount to form Se‐C(N) bonds during this process. Density functional theory calculations show that the Se‐C(N) bond enhances the charge transfer between Na2Se and carbon matrix and binding energy, which improves rate performance and cycling stability. As expected, Se/NHPCs electrode exhibit high reversible capacity (480 mAh g–1 at 0.5 A g–1 after 200 cycles) and rate performance (311 mAh g–1 at 5 A g–1) as the anode for sodium‐ion batteries. A series of ex situ characterization results show that Cu2Se produced by copper current collector induction is effective in the adsorption of polyselenides while enhancing the electrode conductivity. Since the lattice structures of Cu2Se and Na2Se are similar, this displacement reaction that does not involve lattice reconfiguration provides an effective strategy for the preparation of high‐performance and low‐cost electrode materials.

The effect of some additives on the rheology of dough and quality of bread

The technology of production of baking products today can not be imagined without the use of food additives. In this research it was aimed to investigate the use of some additives in wheat flour type 500 for bread production. The formulations and additives used in this study are: without additives for M0, emulsifiers (E 472e) for M1, calcium phosphate (E341 ii) for M2, L-ascorbic acid (E300) for M3 and Damil additive complex (antifouling E170 - 0.06 %; emulsifier E472e -0.08 %; antioxidant E300 -0.01 %; fungal a-amylase - 0.01 %) for M4 formulation. The results showed that the use of additives positively affects some rheological qualities such as water absorption capacity, stability and energy of the dough. M4 bread had a higher specific volume than all breads with 5.14 cm 3 g-1, while M1 and M3 breads were similar. From the total points accumulated for the sensory qualities the M4 bread with a total of 88.8 points accumulated had the best qualities with volume, external appearance and very good crust and crumb taste. It is therefore recommended to use the Damil additive complex in bread production.

Assessment of instrumental and sensory quality characteristics of the bread products enriched with Kombucha tea

Kombucha tea, which is one of the popular probiotic beverage, have been increasingly consumed in recent years due to its nutritional value and many health benefits. It is prepared mainly from the fermentation of different type of tea leaves with kombucha yeast in suitable conditions. This study aimed to develop newly formulated bread products from kombucha tea, that were fermented from black and green tea leaves, and to compare with the bread from the classical recipe based on some instrumental and sensory quality characteristics. Results showed that breads enriched with both type of kombucha tea had higher specific volume (mL/g), more pore ratio, lower moisture content and higher mineral (ash) content than the control bread. Color parameters were found different in the bread with kombucha fermented from black tea because of the dark color formed by browning reactions of phenolic compounds in the black tea. Both type of kombucha tea affected the textural characteristics (hardness, springiness, cohesiveness, gumminess and resilience) of the breads, i.e. higher hardness and less elasticity were obtained. Adding kombucha tea greatly enhanced the total phenolic content of the crumb (by 31.5–37.3%) and the crust (by 54.3–60.3%) in breads. Antioxidant activities evaluated by ABTS⁺ and DPPH methods exhibited that bread products with significantly higher radical scavenging property were produced in the crumb and crust of the newly formulated breads. From a sensory point of view, all bread products were described, both kombucha breads had slightly brown color, sour taste and hard texture. They were correlated with the instrumental results. Bread enriched with kombucha fermented from black tea was liked and preferred as the best one by panelists. In future, these alternative breads enriched with kombucha tea have potential as a new healthy and functional product to be explored by the bakery industry.

Adsorption characteristics of Cs and cation selectivity of todorokite

Todorokite has a high ion exchange capacity and can be a good adsorbent to fix Cs. Here, the adsorption behavior of Cs and the cation selectivity of two todorokites synthesized using two different methods (Oxi-TOD and Red-TOD) were investigated by kinetic and isotherm experiments. Todorokite exhibited a range of physicochemical properties depending on the synthesis method, while the Cs adsorption capacity also varied accordingly. Todorokite, possessing a high specific surface area and pore volume combined with the low average oxidation state of the manganese ion, exhibited a high adsorption capacity. The todorokite attained adsorption equilibrium within 48 h and followed the pseudo-second model. For the adsorption isotherm models, the correlation coefficient was high in the Langmuir model by linear regression and in the Redlich–Peterson model by nonlinear regression. For the adsorption experiment, todorokite had at least two adsorption sites for Cs: a high adsorption preference site with small capacity and a low adsorption preference site with large capacity. The result of the competition experiment between Cs and other cations showed that the ion selectivity was generally similar between the two todorokites except for Cs, K, and Rb, which exhibited similar ionic radii. The selectivity for Oxi-TOD was Li < Na < K < Rb, Cs < Sr while that for Red-TOD was Li < Na < K, Rb, Cs < Sr.

Fabrication of Janus silica nanocarriers for enhancing foliage retention

The deposition performance of drug droplets on plant foliage has played a key role in determining pesticide availability. Herein, we designed and prepared hollow mesoporous silica (HMS) carriers using the etching method. The HMS carriers are uniform hollow spheres with a diameter of 400 nm and shell thickness of 50 nm. The as-prepared HMS carriers show high specific surface area (1148.9 m2/g) and pore volume (0.89 cm3/g) and are suitable for loading pesticides. The HMS carriers were further modified with amino and alkyl groups to form Janus structure (J-HMS) carriers with the amphipathic surface. Abamectin (Aba) is used as a model pesticide to assess the release and adhesive property of J-HMS carriers. The Aba-J-HMS system displayed pH-responsive release behavior and improved wetting and adhesive performance on both hydrophilic and hydrophobic foliar surfaces. In addition, the J-HMS had a good ultraviolet (UV) shielding performance.

Recombinant Rice Quiescin Sulfhydryl Oxidase Strengthens the Gluten Structure through Thiol/Disulfide Exchange and Hydrogen Peroxide Oxidation.

Recombinant rice quiescin sulfhydryl oxidase (rQSOX) has the potential to improve the flour processing quality, but the mechanisms remain unclear. The effects of rQSOX on bread quality, dough rheology, and gluten structure and composition, with glucose oxidase as a positive control, were investigated. rQSOX addition could improve the dough processing quality, as proved by enhanced viscoelastic properties of dough as well as a softer crumb, higher specific volume, and lower moisture loss of bread. These beneficial effects were attributed to gluten protein polymerization and gluten network strengthening, evidenced by the improved concentration of SDS-insoluble gluten and formation of large gluten aggregates and the increased α-helix and β-turn conformation. Furthermore, decreased free sulfhydryl and increased dityrosine in gluten as well as improved H2O2 content in dough suggested that the rQSOX dough strengthening mechanism was mainly based on the formation of disulfide bonds and dityrosine cross-links in gluten by both thiol/disulfide direct exchange and hydrogen peroxide indirect oxidation pathways.

Effects of sodium alginate and locust bean gum on dough rheology and microstructures, and bread quality

AbstractBackground and ObjectivesStrengthening effects of sodium alginate (AG, anionic gum) and locust bean gum (LBG, neutral gum) on dough's network structures were investigated.FindingsAmong all samples, dough containing 0.6% AG showed the longest development and stability time, which was longer than that containing 0.6% LBG by 7.8% and 15.5%, respectively. The relative elastic part of maximum creep compliance (36.26%–59.13%), zero‐shear viscosity (3.69–6.35 × 106 Pa s), elasticity index (0.17–0.44 nm−2), and macroscopic viscosity index (0.14–0.39 nm−2 s) significantly increased with adding AG and LBG. Results of extensograph and dynamic rheology suggested that adding NaCl decreased the tensile energy, storage modulus, and loss modulus of dough containing AG, which might be related to the presence of electrostatic interactions between dough and AG. The bread containing 0.6% AG had a higher specific volume (3.30 ml g−1), height/width ratio (0.74), and springiness (0.93) compared with the bread containing 0.6% LBG.ConclusionsThese results showed denser gluten networks were formed in dough containing AG with electrostatic interactions than in dough containing LBG with hydrogen‐bonding interactions, indicating that electrostatic interactions had a more pronounced effect on dough's network structures than hydrogen‐bonding interactions.Significance and NoveltyThis investigation could provide useful information for the potential application of AG in the development of whole wheat bread.