In this paper, the polystyrene nanofiber (PSnF) with diameter in range 40–80 nm were fabricated using electrospinning technique from solution of polystyrene in toluene and used as an effective filler ...for glass fiber reinforced epoxy composite materials (GF/EP) with contents in range from 0 to 0.1 wt%. GF/EP composites with absence and presence of PSnF were characterized by different techniques, namely; mode I interlaminar fracture toughness, tensile testing and scanning electron microscope. The bonding between GF and EP were also accessed by interfacial shear strength test (IFSS). The obtained results indicated that at 0.07 wt% of PSnF incorporation in epoxy matrix the stress intensity factor (
K
IC
), initiation and propagation interlaminar fracture toughness in mode I were improved by 42.2% from 0.631 to 0.839 MPa m
1/2
, and 43% from 389.82 to 512.09 J/m
2
and 47% from 401.38 to 545.34 J/m
2
, respectively, when compared to pristine epoxy resin as well as pristine composite material. The scanning electron microscopy (SEM) observation pointed out that fibers pull out during initiation delamination accounting for fracture toughness improvement the fracture surface of GF/EP.
The generalized XY model has seen renewed interest recently. This model contains both the spin-spin exchange interaction and q-fold nematic interaction. Due to competition between these two kinds of ...interaction, the model exhibits a rich phase diagram with various phases and unusual phase transitions. Here, we perform an extensive Monte Carlo simulation for this model, focusing on the case of q=3, which corresponds to a three-fold nematic interaction. We use the correlation length to locate the phase transition lines, including the Kosterlitz-Thouless (KT) line, the 1/3 KT line, and the Potts line, which meet at the tricritical point. Further, the magnetic correlation length gives more insights into the tricritical region. Finally, it signifies an intermediate region starting from the tricritical point, where the transition line is neither of the same physics as the Pott transition below nor the KT transition far above the tricritical point.
•We study the phase transition of a generalized 2D XY model with a three-fold nematic-like interaction.•We reconstruct the phase diagram in this model based purely on the magnetic and nematic correlation lengths.•The numerical evidence shows an intermediate region between the three-state Potts and the KT phase transition lines.
•Facile method has employed to prepare mesoporous Co3O4 nanochains with high specific surface area.•The Co3O4 nanochains has highly sensitive and selective toward H2S gas with rapid response.•Such a ...potential gas sensing strategy can be easily extended to other metal oxides.
In this paper, cobalt carbonate hydroxide (Co(CO3)0.5(OH)..11H2O) nanowires were successfully fabricated by a simple hydrothermal route without using surfactants and by subsequent heat treatment in air at 600 °C for 5 h to obtain mesoporous Co3O4 nanochains. As-synthesized nanochains with length of several micrometers consisted of well-linked Co3O4 nanoparticles with an average size of 50 nm. The sensor based on mesoporous Co3O4 nanochains was used to detect flammable and toxic gases, including H2S, NH3, CO, and H2. Results showed potential of mesoporous Co3O4 nanochains as sensor material for detection of hydrogen sulfides at low concentration with rapid response.
In this study, the epoxidized soybean oil (ESO) was successfully synthesized from soybean oil based on its double bond, and used to synthesize the ESO-modified phenolic resin via reaction between ...ESO, phenol and formaldehyde. The ESO contents used in this study vary in range from 0 to 40 wt%. Then, the obtained ESO modified phenolic resin (ESO-PR) was used as resin matrices to fabricate glass-fiber-based composites by using prepreg technique. The chemical structures of both epoxidized soybean oil and phenolic resin modified with epoxidized soybean oil were confirmed with the help of Fourier transform infrared spectrometry (FTIR). The mechanical characteristics of fabricated composite materials examined include the tensile property, flexural property, impact property as well as the mode I interlaminar fracture toughness, while the morphology composite materials were also confirmed by scanning electron microscopy. The test results showed that at 20 wt% of ESO-PR, the mode I interlaminar fracture toughness for both propagation and initiation, the tensile strength, flexural strength and impact strength were increased by 78.3 and 84.5%, 7.0%; 20.5 and 39.7%, respectively. The scanning electron microscopy (SEM) observation indicated that the fracture surface of the modified composite was rougher when compared to the fracture surface of the pristine composite, and hence more energy was needed for the crack to propagate.
The quest for finding an effective photocatalyst for environmental remediation and treatment strategies is attracting considerable attentions from scientists. In this study, a new hybrid material, ...Cu0.5Mg0.5Fe2O4–TiO2, was designed and fabricated using coprecipitation and sol-gel approaches for degrading organic dyes in wastewater. The prepared hybrid materials were fully characterized using scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results revealed that the Cu0.5Mg0.5Fe2O4–TiO2 hybrid material was successfully synthesized with average particle sizes of 40.09 nm for TiO2 and 27.9 nm for Cu0.5Mg0.5Fe2O4. As the calculated bandgap energy of the hybrid material was approximately 2.86 eV, it could harvest photon energy in the visible region. Results indicate that the Cu0.5Mg0.5Fe2O4–TiO2 also had reasonable magnetic properties with a saturation magnetization value of 11.2 emu/g, which is a level of making easy separation from the solution by an external magnet. The resultant Cu0.5Mg0.5Fe2O4–TiO2 hybrid material revealed better photocatalytic performance for rhodamine B dye (consistent removal rate in the 13.96 × 10−3 min−1) compared with free-standing Cu0.5Mg0.5Fe2O4 and TiO2 materials. The recyclability and photocatalytic mechanism of Cu0.5Mg0.5Fe2O4–TiO2 are also well discussed.
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•A new hybrid Cu0.5Mg0.5Fe2O4–TiO2 material was designed and fabricated.•A 2.86-eV-bandgap-energy semiconductor harvests photon energy in the visible region.•High photocatalytic performance with a good degrading rate constant was obtained.•High photocatalytic performance with stability was achieved.•Separation/recovery from the treated solution was achieved using an external magnet.
•This research article investigates the use of pin–fin cooling in gas turbine blades, a crucial technique for managing extreme thermal conditions during operation.•It introduces a novel geometry, the ...C-shaped-recessed endwall, and explores its impact on pin–fin cooling channels.•The study reveals significant improvements in Heat Transfer Efficiency Index (HTEI) of up to 49.75 % compared to conventional flat endwalls, promising enhanced heat transfer capabilities in gas turbine blades.
Pin-fin cooling has long been a crucial technique employed in gas turbine blades to manage the extreme thermal conditions experienced during operation. While numerous studies have investigated the heat transfer characteristics of different pin–fin configurations, the substantial impact of the endwall of the cooling channel on the heat transfer capability of turbine blades has not received adequate attention or thorough investigation. This research paper focuses on studying the influence of a novel geometry, termed C-shaped-recessed endwall, on pin–fin cooling channels in gas turbine blades. The primary objective of this investigation is to analyze the vortex formation and its impact on heat transfer characteristics within the cooling system. The study involved testing five different pin–fin arrays with C-shaped-recessed endwalls inserted between them, spanning a Reynolds number range of 7400 to 36000. The results show that with reference geometrical values, the new geometry increases the Heat Transfer Efficiency Index (HTEI) by 36.53 % compared to the flat endwall at Re = 29000. Higher heat transfer capacities were achieved by manipulating the C-shaped-recessed endwall heights and width of indentations, and the peak HTEI recorded an increase of 49.75 % at Re = 29000 compared to the flat endwall. The findings from this study underscore the potential of the C-shaped-recessed endwall geometry to improve the heat transfer capability of pin-fins by optimizing endwall configurations.
This study aimed to examine: (1) how the Internet has changed consumers food-buying behavior and identify its associated factors; (2) consumers' concern about food safety information of online food ...products. A cross-sectional study was performed from October to December 2015 in Hanoi-a Vietnamese epicenter of food service. One thousand seven hundred and thirty six (1736) customers were randomly chosen from food establishments of 176 communes. Data were collected through face-to-face interviews using structured questionnaires. The majority of participants reported using the Internet to search for food products (81.3%). The most crucial factors influencing food purchases through the Internet were convenience (69.1%) and price (59.3%). Only one-third of participants selected products based on accurate evidence about food safety certification or food origin. The majority of participants were concerned about the expiration date (51.6%), while brand (9.8%) and food licensing information (11.3%) were often neglected. People who were:(1) female, (2) highly influenced by online relationships, and (3) having difficulty in doing usual activities were more likely to look for online food products. These findings produce practical advice to consumers when purchasing their desired food products on the Internet, to online food retailers and to the Government of Vietnam to implement appropriate legislation regarding trading online food products.
The development of low-cost, catalytically efficient, and durable earth-abundant electrocatalysts for replacing platinum-group-metal (PGM) materials has always been at the forefront of materials ...engineering for sustainable hydrogen generation. Metal-organic frameworks (MOFs), especially cobalt (Co)-based zeolitic imidazolate framework (ZIF-67) can be used as precursors or templates for preparing non-precious electrocatalysts. Herein, we successfully fabricated metallic cobalt/cobalt sulfide hetero-nanostructures embedded within N-doped graphitic carbon nanocages (Co/Co
x
S
y
@NC-750) by the one-step pyrolysis of ZIF-67 under H
2
and S. Co/Co
x
S
y
@NC-750 exhibits a hollow configuration with a high degree of morphological uniformity. The pyrolysis temperature and resulting control of the composition played a crucial role in material engineering with application-oriented properties. Examination of the activity for the hydrogen evolution reaction (HER) in 0.5 M H
2
SO
4
and 1.0 M KOH aqueous electrolytes demonstrated that Co/Co
x
S
y
@NC-750 exhibits substantially improved HER performance in both acidic (overpotential of 130 mV and Tafel slope of 82 mV dec
−1
) and basic (330 mV and 160 mV dec
−1
) media. The unique metallic cobalt core/cobalt sulfide shell is particularly beneficial for maintaining the electrochemical long-term durability (≥30 h and 40 h in acids and bases, respectively). This study provides guidance for achieving MOF-derived inorganic nanomaterials with the desired structural heterogeneity and compositional control for non-PGM electrochemical catalysis through fundamental quantification of the structural and catalytic parameters.
Metallic cobalt/cobalt sulfide embedded within N-doped graphitic carbon nanocages synthesized through a pyrolysis of ZIF-67 under H
2
and S show morphological uniformity beneficial for maintaining electrochemical long-term durability.
The development of a low cost and scalable gas sensor for the detection of toxic and flammable gases with fast response and high sensitivity is extremely important for monitoring environmental ...pollution. In this work, we introduce two different synthesis pathways for the preparation of scalable Fe2O3 nanoparticles for gas sensor applications. One is co-precipitation and the other is hydrothermal method. The gas sensing properties of the α-Fe2O3 nanoparticles (NPs) fabricated by different synthesis pathways were studied and compared. The performance of the NPs in the detection of toxic and flammable gases such as carbon dioxide, ammonia, liquefied petroleum gas, ethanol, and hydrogen was evaluated. The Fe2O3 NP-based gas sensors exhibited high sensitivity and a response time of less than a minute to analytic gases. However, the NPs fabricated by the one-step direct method exhibited higher sensitivities than those generated by the α-Fe2O3 NPs obtained by co-precipitation synthesis possibly because of their nanoporous structure. This performance is attributed to the large specific surface area of the NPs, which results in higher sensitivity.
► Nanoporous hematite NPs were prepared by a facile synthesis pathway for gas nanosensors. ► The nanoporous NPs exhibited higher sensor response compared to those of the condense counterpart. ► The developed gas nanosensors allowed detecting the toxic gases at low concentrations.
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