Normal Atmospheric Conditions Research Articles

One-Step Synthesis of N/N-S Graphene from Fruitwastes: Chemistry and Mechanism

The present work explored the synthesis of N-S containing graphene from nitrogen-rich fruit wastes in the presence of urea and thiourea. Since pure graphene exhibited limited electrocatalytic activity due to a low number of active sites, it is highly recommended to introduce multi-heteroatoms into the graphitic lattice, increasing electrical conductivity and interlayer spacing graphene. The results suggested that urea and thiourea played a dual role as they were involved in the cyclization and aromatization to form a graphitic lattice and introduced nitrogen and sulfur atoms within the lattice pyrolysis. The utilization of urea and thiourea facilitated the development of N-S containing graphene from fruit wastes and prevented oxygen's attack between 250-350 oC under normal atmospheric conditions.

QUALITY ASSESSMENT OF GAMMA IRRADIATED POWDERED DRIED MUSHROOMS (PLEUROTUS PULMONARIUS AND VOLVARIELLA VOLVACEA) IN EXTENDING SHELF LIFE DURING STORAGE

Mushrooms are soft textured and prone to deteriorate shortly after harvest if not properly stored. In view of their short shelf life under normal ambient conditions of temperature and humidity, it is imperative to preserve it by processing to extend shelf life for off season use. Drying is one of the common methods used for mushrooms for preservation owing to its easiness and economical nature. Irradiation is known to be a safe technology for treating food products using ionizing radiation. Gamma ray ionizing radiation is used to extend the shelf-life of food products and results in the inactivation of foodborne pathogens. This paper showed the ability of gamma irradiation for decontamination of powdered dried mushrooms (Pleurotus pulmonarius and Volvariella volvacea) and reliable process for edible mushrooms storage in commercial industries. The mushrooms were dried at temperature of 45-55ºC, powdered and given gamma irradiation at 0 (control), 2, 5 and 10 kGy. Results showed that irradiation at 2 kGy had the ability to reduce the microbial loads (bacterial and fungal colonies) in powdered dried mushrooms and there was no presence of microbes after irradiated at 5 and 10kGy. Nevertheless, after storage 9 months, the microbial loads increased in the control samples but maintained low in samples (Pleurotus pulmonarius and Volvariella volvacea) irradiated at 5kGy (1.4x102, 1.5x101 cfu/g) and 10kGy (4x101, 5x101 cfu/g). There were no significant changes in colour of all samples during storage. Although there were some changes observed for proximate compositions due to the gamma irradiation, the results obtained were no significant differences (P<0.05) and showed that the integrity of these compositions in the mushrooms were minimally affected as no adverse effects were observed. Irradiation at dose 5 and 10kGy are suitable in maintaining the quality of the powdered dried samples and also extended the storage period.

Biodegradation of plastics at home composting conditions

Plastics have become an ever-increasing environmental pollution problem since high amounts of them are dumped every year into the environment. To remediate this problem, many proposals attempt to produce new plastics with the same sound characteristics as the old ones, but with an increased biodegradability to remain only a few months in the environment before they can be turned into safe non-polluting natural products by microbes. One example of these materials is the polylactic acid-based plastic (PLA), which is presented as a biodegradable-compostable material but usually with a warning that they perform in this way under particular conditions. In this work, we evaluate the biodegradability of PLA and other plastics in a composting system under normal atmospheric conditions with an average temperature around 24 ºC in order to establish its compostability in typical conditions of tropical countries. Results obtained by monitoring the integrity and weight of plastic pieces and NMR over time reveal that none of the materials was biodegraded after 31 weeks (∼7 months) under the studied conditions. On the other hand, amplicon sequencing of the 16S rRNA showed the presence of bacterial groups identified previously on the degradation of biodegradable plastics (e.g., Methylotrophs and Actinobacteria) and are aligned with previous studies that conclude that plastics considered as biodegradable influence the soil microbiota. This work contributes to establishing which plastic materials should be classified as biodegradable in prevailing conditions in tropical countries.

Comparative analysis of wear behaviour of commercial polymeric pipe materials under different sliding environments

ABSTRACT The friction and wear behaviour of three commonly used commercial polymeric materials, namely, Acrylic, high density polyethylene (HDPE) and unplastisised polyvinyl chloride (uPVC), was studied experimentally under normal ambient conditions. More specifically, the wear rate and coefficient friction of the materials were evaluated against a mild steel counter disc under three different sliding conditions realised by dry, wet (water) and 5% bentonite-clay water environments, which were then analysed as a function of sliding distance as well as the applied load on the sample. Moreover, in order to visualise the results of the present investigation in a comprehensive manner, the associated major physical and mechanical properties of the materials were also investigated. The vertical pin-on-disc method was used to conduct the study. Both the wear and friction characteristics were strongly linked to the structure of the polymers; HDPE samples being fully crystalline show best wear and friction characteristics, whilst the amorphous Acrylic shows the worst. Optical microscopic analysis of the specimens, particles from the worn surfaces (wear debris) and the counter disc also indicated that Acrylic was most affected by wear, whilst HDPE was least affected. SEM and EDX observations showed that uPVC was most affected by oxidation followed by HDPE and Acrylic. The excellent wear and frictional properties of HDPE, especially, in particle-dense fluid transportation, make it ideal for dynamic applications, particularly with mine debris flows and transporting of slurry.

Environmental affected mechanical performance of additively manufactured carbon fiber–reinforced plastic composites

Due to their attractive strength-to-weight ratios, stiffness-to-weight ratios, thermal expansion, corrosion resistance, and vibration resistance properties, carbon fiber reinforced plastic (CFRP) composites have been widely used in applications ranging from aerospace to sporting goods. Considering some of the advantages of additive manufacturing (AM) over traditional subtractive methods, AM is being used to fabricate CFRP composites. For the fabrication method, several investigations have been conducted on materials and processing effects on the mechanical performance of the composites. However, no studies have investigated the effects of environmental conditions on mechanical performance. This study reports the environmental (temperature and relative humidity) affected mechanical performance of AM fabricated CFRP composites exposed to three different environmental conditions: warm–wet, warm–dry, and cold–dry, compared to samples tested immediately after fabrication under normal ambient conditions. The result was that the warm temperatures have insignificant effects on the mechanical performance of the composites, while near-zero degree cold temperatures have significant effects after the 96 h and 250 h short-term exposure periods. The result also showed the temperature to have more significant effects on mechanical properties than relative humidity. Under the warm conditions, the dry humidity resulted in a slight increase in material mechanical properties over the nominal ambient condition, while the wet humidity showed an insignificant reduction in material mechanical properties.

Mechanical Properties of Douglas Fir Wood at Elevated Temperatures under Nitrogen Conditions

AbstractThe mechanical properties of wood tend to decrease with increasing temperature under normal atmospheric conditions. A pyrolysis zone develops inside wood when it catches fire, and the surfa...

ß-Farnesene Exogenous Application as a Novel Damage Induction Model to Fast Explore the Effectiveness of Postharvest Strategies: The Case Study of the ‘Rocha’ Pear DOP

Since the prohibition of diphenylamine, replacement strategies have been needed for long-term disorder prevention, namely superficial scald (SC), in fruit. However, as this disorder only appears after months under cold storage, the assessment of effective strategies to prevent this disorder requires long periods. To tackle this challenge, we report in this paper a rapid and reliable system to induce symptoms, such as SC, based on storage under a β-farnesene-enriched atmosphere. Using this model, SC symptoms in ‘Rocha’ pear were induced after 15 d at 20 °C. As proof of concept, this model system allowed the study of the efficiency of antioxidant natural-based coatings on ‘Rocha’ pear quality maintenance. Pears treated with the coatings were submitted to 4 months of commercial storage under normal atmosphere conditions and the results were compared with those obtained using the induction model system. A PCA of chemical data allowed us to conclude that the model developed simulates the potential of certain strategies to prevent disorders.

Effect of Controlled Atmospheres and Environmental Conditions on the Physicochemical and Sensory Characteristics of Sweet Cherry Cultivar Satin

Sweet cherry is a highly appreciated seasonal fruit with a high content of bioactive compounds; however, this highly perishable fruit has a relatively short shelf-life period. Here, we evaluated the evolution of the physicochemical and sensory qualities of sweet cherries (Prunus avium (L.) cv. Satin) under different storage conditions, namely at a Farmers’ Organization (FO) and in a Research Centre (RC) under normal and four different conditions of controlled atmosphere for 49 days. Additional parameters were monitored, such as rotten fruit incidence and stem appearance. Temperature was the factor that most influenced the fruit quality changes over the study time. In fact, fruits stored at higher mean temperatures showed higher weight loss, higher variation in CIE-Lab colour parameters, higher firmness loss, and browner and more dehydrated stems and were less appealing to the consumer. Controlled atmosphere conditions showed a smaller decrease in CIE-Lab colour parameters and lower weight loss. The incidence of rotting was very low and was always equal or lower than 2% for all conditions. Thus, RC chamber conditions were able to sustain fruit quality parameters over 28 days under normal atmosphere conditions and 49 days under controlled atmosphere conditions.

Experimental Investigation on Mechanical Properties of A/GFRP, B/GFRP and AB/GFRP Polymer Composites

This study aims to reveal the consequence of thickness reinforcement on Fiber Laminates (Polyester Resin, Glass Fiber, Aluminum, and Bentonite) and to see if it can enhance the mechanical properties and resistance of laminates. Glass fiber reinforced polymer composites have recently been used in automotive, aerospace, and structural applications where they will be safe for the application s unique shape. Hand layup was used to fabricate three different combinations, including Aluminium /Glass fiber reinforced polyester composites (A/GFRP), Bentonite/Glass fiber reinforced polyester composites (B/GFRP), and Aluminium&Bentonie/Glass fiber reinforced polyester composites (AB/GFRP). Results revealed that AB/GFRP had better tensile strength, flexural strength, and hardness than GFRP and A/GFRP. Under normal atmospheric conditions and after exposure to boiling water, hybrid Aluminium&Bentonite and glass fiber-reinforced nanocomposites have improved mechanical properties than other hybrid composites. After exposure to temperature, the flexural strength, tensile strength and stiffness of AB/GFRP Composites are 40 % higher than A/GFRP and 17.44% higher than B/GFRP Composites.

Quality of fresh-cut apples as affected by dip wash treatments with organic acids and acidic electrolyzed water

The objective of this study was to investigate the effects of dipping in solutions of citric (2%), benzoic (0.2%), sorbic (0.2%) and ascorbic (0.5%) acids and in acidic electrolyzed water on the quality attributes and surface microbiota of fresh-cut apples, cvs ‘Florina’ and ‘Ionathan’, packaged in disposable plastic containers under normal atmospheric conditions during 14 days storage at 8 °C. The colour, firmness, total phenolic content, antioxidant activity and surface microbial load were determined weekly throughout storage. The colour results indicated that acidic electrolyzed water reduced browning while the ascorbic and citric acids were less effective in controlling the enzymatic browning of fresh-cut apples. After 14 days of refrigerated storage, the samples treated with 2% citric acid and acidic electrolyzed water maintained significantly higher firmness, total phenolic content and antioxidant activity than the other treated and control samples. The microbiological analysis revealed that organic acids successfully suppressed bacterial growth throughout the storage period as compared to the control samples. The sorbic and benzoic acids at 0.2% were also effective on yeasts but these dip treatments determined a higher darkening, yellowing and loss of firmness and of antioxidant activity during storage.

Multiple regression analysis on drilling performance of Al 2219 – SiCp metal matrix composite by Response surface Methodology (RSM) technique

In this work, Response Surface Methodology (RSM) based multiple performance analysis was used to investigate in detail about the influences of most dominating machining process parameters on responses like thrust force and surface roughness in the drilling of aluminium metal matrix composites developed through powder metallurgy process. Cylindrical specimens of Al 2219 aluminium alloy with silicon carbide particulates of average particle size 23, 37 and 67 µm as reinforcement are used in the experiment. Drilling test was carried out using poly crystalline diamond (PCD) coated solid tungsten carbide drill of diameter 5 mm at normal atmospheric conditions and different combinations of machining conditions. The RSM based multiple performance analysis was carried out to develop the input output relationships of the machining process parameters. The developed mathematical models were subjected to test their capability using analysis of variance (ANOVA). The main and interaction effect of the input variables on the responses was also investigated. The entire adequacy R2 has been more than 95%, which is within the desirable limit and indicate that the model is accurate and fit.

Self-combustion induced hierarchical nanoporous alloy transition toward high area property electrode for supercapacitor

The surfaces of nanoporous metals are easy to be oxidized under normal ambient condition. This usual attribute permits the exploration of metal-core oxide-shell structure that would be used for supercapacitors (SCs). However, the large-scale application of such electrodes is still limited by the intrinsically low ion diffusion coefficient, poor electronic conductivity and frustrating structural stability. Here we design a defect decorated hierarchical nanoporous CuMn2O4/Cu0.2Ni0.8O/CuxOy @ alloy electrode (HNP-TMO) by dealloying-coarsening-dealloying a sandwich-like NiCuMn/Ni/NiCuMn alloy and followed by self-combusting (2.1 mm s−1). The sandwiched Ni can synergy with unoxidized alloy to provide excellent mechanical stability and electronic conductivity, while the hierarchically porous structure with robust defects can ensure rapid electron/ion transportation. Benefiting from these merits, the HNP-TMO electrode with high mass loading of 7.8 mg cm−2 delivers an ultrahigh area capacity of 6.78 mAh cm−2 at 10 mA cm−2, good rate capability (maintaining 3.33 mAh cm−2 at ultra-high current density of 100 mA cm−2) and outstanding cycling performance with capacity retention of 92.7% after 12000 cycles. Full symmetric supercapacitor also demonstrates high energy and power density of 0.17 mWh cm−2 and 40.15 mW cm−2, respectively, indicating the promise for practical energy storage applications.

Enhancing sulfide mitigation via the sustainable supply of oxygen from air-nanobubbles in gravity sewers

Traditional air or oxygen injection is an effective and economical mitigation strategy for sulfide control in pressure sewers, but it is not suitable for gravity sewers due to the low solubility of oxygen in water under normal atmospheric conditions. Herein, an air-nanobubble (ANB) injection method was proposed for sulfide mitigation in gravity sewers, and its sulfide control efficiency was evaluated by long-term laboratory gravity sewer reactors. The results showed that an average inhibition rate of 45.36% for sulfide was obtained when ANBs were implemented, which was 3.75 times higher than that of the traditional air injection method, revealing the effectiveness and feasibility of the ANB injection method. As suggested by microbial community analysis of sewer biofilms, the relative abundance of sulfate-reducing bacteria (SRB) decreased 40.57% while that of sulfur oxidizing bacteria (SOB) increased 215.27% in the presence of ANBs, indicating that sulfide mitigation by ANB injection included both the inhibition of sulfide production and the oxidation of dissolved sulfide. The specific cost consumption of ANB injection was 1.7 $/kg-S, which was only 6.85% of that of traditional air injection (24.8 $/kg-S), suggesting that the sustainable supply of oxygen based on ANB injection is not only environmentally but also economically beneficial for sulfide mitigation. The findings of this study may provide an efficient sulfide mitigation strategy for the management of corrosion and malodour issues in the poorly ventilated gravity sewers.

Study on the electrowetting and beam current characteristics of externally wetted ionic liquid electrospray thruster

It is the theoretical basis to analyze the hydrodynamics mechanism of ionic liquid in an electrostatic field to ensure that the ionic liquid electrospray thruster possesses good wettability. Stable and continuous electrowetting emitters are closely related to thrust noise, resolution, and stability. Therefore, it is urgent to explore the law of ionic liquid electrowetting emitters in an electrostatic field to improve the performance of thrusters. The article proposes a new hybrid emitter structure, which consists of a V-blade emitter and a square capillary. It also carries out numerical simulation of emitter electrowetting under normal gravity and atmospheric conditions and emission experiments to explore the process of ionic liquid layer spreading on the external surface of the emitter. The dimensions of the emitter d1, d2, and θ and the physical properties of ionic liquids jointly determine the electrowetting velocity, the threshold of wetting voltage, and the liquid layer thickness. By analyzing the influence of various variables on electrowetting, a complete emitter electrowetting law of ionic liquid electrospray thrusters is summarized, which provides an important basis for the optimization of the emitter structure. Considering the scale of the emitter and bond ≈1, the meniscus in the electrostatic field is mainly affected by gravity, surface tension, viscous force, and electrophoretic force. Accordingly, it is worth noting that electrophoretic force is calculated by the Maxwell stress tensor method that treats ionic liquids as a dielectric to ensure the continuity of the meniscus. Although it can satisfy the electrowetting study at the macroscale, the interaction between anions and cations at the micro-scale is ignored. The numerical simulation results and the experimental results are correlated. It is proved that the method used in this article is accurate enough to simulate electrowetting before the liquid layer breaks up to form ion emission.

Effects of Electron Beam Irradiation on the Thermal Properties of Scrap Polytetrafluoroethylene

This study is focused on analyzing the effects of electron beam (EB) irradiation at high doses and normal atmospheric conditions on the thermal stability of scrap polytetrafluoroethylene (PTFE) solid to facilitate the recycling process of the material by grinding it into micro-powder additives for various applications. In this work, PTFE scrap with thickness not exceeding 1 mm was irradiated in doses between 0 - 1500 kGy using an electron beam accelerator machine (EBM) with a voltage energy of 3 MeV and current of 10 mA and grinded into powder by using a laboratory mill. The changes in morphology of the grinded powder, crystallinity and thermal properties of PTFE with increasing irradiation dose was studied by using scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The photomicrographs obtained from SEM showed that the particle size of the grinded micro-powder decreases with increasing irradiation dose with best results observed at 1500 kGy dose. DSC analysis showed that the crystallization temperature (Tc) and melting temperature (Tm) decreases with increasing irradiation doses as a result of lower molecular weight. XRD analysis of the irradiated PTFE indicated that the intensity of the peak had increased with increasing doses of irradiation due to the increase in crystallinity of the material. The distinctly shorter derivative thermogravimetric (DTG) peak height at 1500 kGy shows higher rate of mass loss at that dose due to the rapid loss of mechanical properties caused by degradation.

Enhanced voltammetric performance of sensors based on oxidized 2D layered black phosphorus

The exceptional properties of 2D layered black phosphorus (BP) make it a promising candidate for electrochemical sensing applications and, even though BP is considered unstable and tends to degrade by the presence of oxygen and moisture, its oxidation can be beneficial in some situations. In this work, we present an unequivocal demonstration that the exposition of BP-based working electrodes to normal ambient conditions can indeed be advantageous, leading to an enhancement of voltammetric sensing applications. This point was proved using a BP modified screen-printed carbon electrode (BP-SPCE) for the voltammetric determination of dopamine (DA) as a model target analyte. Oxidized BP-SPCE (up to 35% of PxOy at the surface) presented an enhanced analytical performance with a 5-fold and 2-fold increase in sensitivity, as compared to bare-SPCE and non-oxidized BP-SPCE stored in anhydrous atmosphere, respectively. Good detection limit, repeatability, reproducibility, stability, selectivity, and accuracy were also achieved. Overall, the results presented herein display the prominent possibilities of preparing and working with BP based-sensors in normal ambient settings and showcase their implementation under physiological conditions.

Synthesis and characterization of magnesium melting fluxes

Magnesium and its alloys are extremely susceptible to oxidation and fire due to their reactivity with oxygen. Therefore, special care should be taken while melting them. In this research, different types of fluxes were used to protect the molten magnesium from oxidation. These fluxes cover the molten magnesium surface and refine it. In this research, nine magnesium melting and refining fluxes were studied. Dow fluxes compositions were taken as a base to prepare five fluxes and another four fluxes were developed by varying the content of chlorides, fluorides, and oxide. The main purpose of this research is to increase the recovery of magnesium metal by melting in normal atmospheric conditions and develop a low-cost conventional melting practice. Decomposition behavior, mass change, and melting of these nine fluxes were studied by TG/DTA technique. After fusing, the surface morphology of these fluxes was studied by visual observation and scanning electron microscope. Magnesium was melted using these nine fluxes and for each flux, the weight loss of magnesium was calculated. From a thermal analysis study, it was confirmed that all the fluxes were fused before magnesium melting. Based on the flux layer which was generated during the melting and the weight loss analysis, flux 9 (250) was the best flux compared to other fluxes. The highest purity was obtained by using flux 2 with the highest tensile strength value.

Reduction of the carbon footprint of cargo vehicles with pneumatic recovery of braking energy

Reducing carbon dioxide emissions by passenger vehicles allows you to achieve the use of electric power plants and hybrid power plants made on the basis of thermal internal combustion engines and electric machines. However, the application of the above-mentioned approach for trucks is associated with significant difficulties due to the low specific capacity of the chemical current sources currently used. The recovery of braking energy of cargo vehicles in the pneumatic form is constrained by the need to achieve a high speed of switching on the pneumatic recuperator. In order to minimize the energy losses of the pneumatic recuperator during acceleration and steady-state. Without changing the design and reducing the reliability of the internal combustion engine, it is possible to supply air to its inlet at pressures not exceeding 350 kPa. When air is supplied to the internal combustion engine inlet at pressures of 200 and 300 kPa, it is possible to reduce specific carbon dioxide emissions by 16 and 37 % per unit of generated mechanical energy, respectively, compared to air supply under normal atmospheric conditions.

Mitochondrial superoxide dismutase overexpression and low oxygen conditioning hormesis improve the performance of irradiated sterile males

The Sterile Insect Technique (SIT) is a successful autocidal control method that uses ionizing radiation to sterilize insects. However, irradiation in normal atmospheric conditions can be damaging for males, because irradiation generates substantial biological oxidative stress that, combined with domestication and mass-rearing conditions, may reduce sterile male sexual competitiveness and quality. In this study, biological oxidative stress and antioxidant capacity were experimentally manipulated in Anastrepha suspensa using a combination of low-oxygen conditions and transgenic overexpression of mitochondrial superoxide dismutase (SOD2) to evaluate their role in the sexual behavior and quality of irradiated males. Our results showed that SOD2 overexpression enhances irradiated insect quality and improves male competitiveness in leks. However, the improvements in mating performance were modest, as normoxia-irradiated SOD2 males exhibited only a 22% improvement in mating success compared to normoxia-irradiated wild type males. Additionally, SOD2 overexpression did not synergistically improve the mating success of males irradiated in either hypoxia or severe hypoxia. Short-term hypoxic and severe-hypoxic conditioning hormesis, per se, increased antioxidant capacity and enhanced sexual competitiveness of irradiated males relative to non-irradiated males in leks. Our study provides valuable new information that antioxidant enzymes, particularly SOD2, have potential to improve the quality and lekking performance of sterile males used in SIT programs.

Effect of types of resin cements on the bond strength of fiber post under simulated dives

Background: Changes in barometric pressure conditions that occur during flying and diving under hyperbaric oxygen conditions were found to influence the retention of dental restorations. Aim: This experimental laboratory study aimed to evaluate the bond strength of glass fiber posts after being cemented with self-adhesive resin cement (RelyX™ Unicem, 3M ESPE) and self-etch adhesive resin cement (RelyX™ Ultimate, 3M ESPE) under normal atmospheric pressure and hyperbaric pressure cycles that simulate diving conditions. Methods: A total of 40 extracted, single-rooted mandibular premolars were treated endodontically and randomly divided into two groups according to the cements used for fiber post cementation. Each group was further randomly divided into two equal subgroups that were subjected to normal atmospheric pressure conditions and a simulated hyperbaric condition in a hyperbaric chamber. The pull-out bond strength of fiber posts was tested using a universal testing machine. Data were analyzed using one-way analysis of variance with the Tukey post-hoc test (p<0.05). Results: At normal atmospheric pressure the mean value of the pull-out bond strength of RelyX Ultimate cement was significantly higher than that of RelyX Unicem cement. At hyperbaric pressure condition no significant difference was found between the mean values of the pull-out bond strength of RelyX Ultimate and RelyX Unicem cement. Conclusion: Hyperbaric pressure cycles demonstrated improved pull-out bond strength of glass fiber posts in RelyX Unicem cement but did not have significant effect on pull-out bond strength in RelyX Ultimate cement. Both resin cements have similar pull-out bond strength of glass fibers post after simulated dives.