Greater Resistance Research Articles

Supported Co3O4 catalyst on modified UiO-66 by Ce4+ for completely catalytic oxidation of toluene

Creating a new low-temperature catalyst in decreasing the emission of volatile organic compounds (VOCs) has great significance under different industrial production situations. In particular, the Zr-UiO-66 is optimized by different amounts of cerium, which not only enhances the physicochemical stability but also increases the number of active sites of CexZryUiO-66. Furthermore, the catalysts with Co3O4 nanoparticles supported on CexZryUiO-66 were successfully prepared via impregnation method. In the process of toluene degradation, the Co/Ce1Zr2-UiO-66 attains a 90% conversion rate at 210 °C with a space velocity of 60000 mL/(g·h) and toluene concentration at 1000×10–6. Meanwhile, the carbon dioxide selectivity reaches 100% at 218 °C. The Co/Ce1Zr2-UiO-66 shows great water resistance (3 vol% H2O). Multiple characterization methods were used to figure out the physicochemical properties of the catalysts. It is found that the addition of an appropriate amount of cerium can enhance stability of UiO-66 and surface lattice oxygen proportion. Additionally, the stronger electron transfer between Ce4+ and Co2+ enables the Co/Ce1Zr2-UiO-66 to possess more active surface oxygen species and Co3+ cationic species in all samples.

Supporting Patients with Amputated Lower Limb in Accepting Their New Body Images by Traumatology Nurses of Central Hospital Yaoundé-Cameroon: An Exploratory Study

This study aims at exploring the role of the nurse in supporting patients with the amputated lower limb towards the acceptance of their new body images in the traumatology B unit of the Central Hospital in Yaoundé-Cameroon. The study used a qualitative exploratory design. The study population was made up of eight nurses from the traumatology unit of the central hospital in Yaoundé-Cameroon. Data were collected using a semi-structured interview guide from a purposeful sample of nurses. The saturation level determined the sample size for the study. Data were analyzed using inductive content analysis. The results obtained from this study showed that it is difficult to take care of patients with amputated lower limbs as physical support e.g. hygiene care; wound dressings, pain evaluation and care were outlined by most of the nurses as the main mode of support given to patients. Consideration should be given to non-pharmacological and less invasive surgical interventions for phantom limb pain, as they are associated with less common and less severe side effects. Active listening, reassuring patients, helping relationship and confidence were the main elements of psychological support stated by the nurses. The main challenges nurses encountered in supporting amputated patients were difficult communication and language barrier. The findings from this study proposed that there were many factors to take into account in order to be able to help patients with amputated lower limb: physical and moral pain, the psychological aspect with modification of body image, loss of self-esteem etc... The nurse must demonstrate human and relational qualities and great psychological resistance in order to effectively support the amputated patient on the physical level by providing hygiene and comfort care, dressing; and on the psychological level by questioning the patients about their difficult emotions while being available to listen in order to establish a nursing diagnosis and help the patients to cope with their difficulties.

Aerobic Bacteria and Their Antibiotic Resistance Profile in Neonatal Septicaemia: A cross Sectional Study in a Tertiary Care Hospital of Rajshahi, Bangladesh

Objective: Neonatal sepsis is an infection of the bloodstream in infants younger than 28 days old. It continues to be the major cause of morbidity and mortality among newborns, particularly in middle- and low-income nations. The objective of this study was to isolate and identify aerobic bacteria of neonatal sepsis by blood culture using FAN method followed by subculture and relevant biochemical tests. Methods: It was a cross sectional type of descriptive study where the sample size was 95 and data were collected purposively from the clinically suspected neonatal septicaemia cases from inpatient Pediatric department in Rajshahi Medical College Hospital, Rajshahi. Results: Most 34 (35.79%) of the cases were culture positive, whereas 61 (64%) were culture negative. 7 (21%) of the 34 positive cases were Gram-positive, while 27 (79%) were Gram-negative. S. aureus was found in 6 (17.65%) of the culture-positive isolates, followed by CoNS with 1 (02.94%), E. coli with 14 (41.17%), Klebsiella spp. with 6 (17.65%), P. aeruginosa with 6 (17.65%), and Acinetobacter with 1 (02.94%). Gram-positive bacteria were extremely susceptible to Vancomycin (90%), Gentamicin (90%), and Ciprofloxacin (80%) based on antibacterial susceptibility testing. Colistin (100%) and ampicillin (100%) exhibited the greatest resistance. Meropenem (90%), Amikacin (90%), and Colistin (89%) were the most effective antibiotics against Gram-negative bacteria, whereas Ceftazidime (60%) was the least effective. Vancomycin (100%) and ampicillin (100%) exhibited the highest degree of resistance. Conclusion: Both Gram-positive and Gram-negative aerobic bacteria were related with newborn septicaemia, and a significant proportion of them were resistant to multiple medicines. CME J 2024; 3(2); 4-11

A high-performance TFN membrane prepared by a novel PE support layer, a polydopamine interlayer, and a doped MoS2 quantum dots@ZnO nanocomposites-incorporated polyamide active layer

Herein, thin film nanocomposite (TFN) membranes were prepared with excellent chemical stability and separation performance for organic solvent nanofiltration (OSN) applications. The support membrane was synthesized via a new approach, in which a blend of two immiscible polymers, i.e. high density polyethylene (HDPE)-polystyrene (PS), which were compatibilized with styrene-ethylene-butylene-styrene (SEBS), was prepared through mixing by a Brabender, followed by fabricating blend sheets through a hot press machine. The PE support was then prepared by extracting the PS/compatibilizer phase from the blend sheet. The hydrophilicity of the PE support membrane was considerably enhanced with a polydopamine (PDA) layer. Different nanoparticles including nanoflower (NF) ZnO, nanosphere (NS) ZnO, MoS2 Quantum dots-nanoflower ZnO nanocomposite (QDs@NF ZnO), and MoS2 Quantum dots-nanosphere ZnO nanocomposite (QDs@NS ZnO) were incorporated into the polyamide (PA) active layer of the membranes to enhance the performance of the TFN membranes. The separation performance of the TFN membranes was investigated for rejecting different dyes dissolved in methanol. Our results demonstrate outstanding separation performance, with a dye rejection of 99.6 %, 99.6 %, 99.8 %, and 99.9 % for methylene blue, crystal violet, rhodamine B, and methyl green, respectively. Additionally, the TFN membranes incorporated with QDs@NF ZnO nanoparticles showed great solvent resistance, with a methanol permeance up to 6.7 L/m2.h.bar after activation with dimethylformamide.

An instrumentation amplifier with series switch pseudo resistor DC-servo loop realizing 0.16-Hz high-pass corner

This paper presents an instrumentation amplifier for electrocardiogram (ECG) signal recording. A DC servo loop (DSL) based on a series-switch pseudo resistor (S2PR ) is utilized to suppress the effect of the unavoidable electrode DC offset effectively. The two-step pulse generation circuit realizes two sets of pulse signals with shallow duty cycles, and the pulse signals drive the path switches and virtual switches in the S2PR, respectively. Virtual switches reduce the channel charge injection effect, and finally, a great equivalent resistance with high linearity is realized. The continuous DSL realized based on S2PR can suppress the electrode DC offset of ±180 mV. At the same time, the active area of the DSL is significantly reduced. The proposed instrumentation amplifier is realized in a standard 0.18-μm CMOS process. Simulation results show the DSL designed with a 1.8-V supply introduces a 0.16-Hz high-pass corner. The power consumption of the S2PR-DSL is 92.7 μW. The gain of the instrumentation amplifier is 39.8 dB, and the input-referred noise at the TT corner is 1.78 μVrms over a bandwidth of 0.5 Hz to 150 Hz. The input impedance of the instrumentation amplifier is 772.2 MΩ, when the input signal frequency is 50 Hz, and the total harmonic distortion (THD) of a 10-mVpp input sinusoidal signal at 9.033 Hz is −61.6 dB.

Exploring the Influence of Stirring Temperature on the Fatigue and Mechanical Characteristics of AA5128/SiC Nanocomposites

Aluminum is anticipated to continue being the primary material for various essential uses like aviation and automobiles. This is because of the great resistance to various climatic conditions, required and controllable mechanical qualities, and high fatigue resistance. Aluminum nanocomposites like AA5128/SiC can be produced by several liquid metallurgical techniques. The main challenges for this method in producing nanocomposites involve ensuring a consistent distribution of strengthening components and controlling any chemical interactions between the strengthening compositions and the matrix. Intended for structural use, specifically in the aircraft industry, developing cost-effective nanocomposites with operational and geometric flexibility poses a significant ongoing challenge. Various methods of producing AA5128/SiC nanocomposites yield distinct mechanical characteristics. Nine nanocomposites were synthesized in the current research by varying the stirring temperatures (810, 860, and 910℃) with different levels of SiC added at 0, 6, 8, and 10 wt %. The composite consisting of 10 wt % SiC and agitated at 860℃ showed improved characteristics in tensile, hardness, and fatigue tests. The composite containing 10 wt % SiC with a stirring temperature (ST) of 860℃ led to a 22.3% rise in tensile strength, a 16.2% rise in Vickers hardness number, and a 40.2% reduction in ductility compared to the sample without nanoparticles. At 810℃ (ST), the fatigue life at a stress level of 100 MPa raised by 18.5% compared to the 10 wt% nanocomposite.

Influence of Particle Surface Energy and Sphericity on Filtration Performance Based on FLUENT-EDEM Coupling Simulation

The adhesion of dust particles on the surface of the dust collector tends to cause great resistance to the dust collector and affects the operating efficiency. In order to visualize particles in the filtration process and to grasp the mechanism of particle viscosity and sphericity on filtration performance, a numerical simulation study was conducted to investigate the deposition behavior of particles during filtration, employing FLUENT-EDEM coupling technology. By examining the deposition process, the role of particle characteristics on dust behavior within the entire filtration system was elucidated. The effects of varying particle surface energy and particle sphericity on filtration pressure drop and cake porosity were analyzed. The findings reveal that under the force of the air, particles on the surface of the filter membrane experience compaction, leading to a reduction in the porosity of the formed cake layer. The diminution of porosity serves to impede the air, consequently augmenting the pressure drop across the filtration system and hindering the operational efficacy of the dust collector. As the surface energy of the particles increases, the adhesive forces between particles are intensified, leading to an elevation in the porosity of the cake layer and a subsequent decrease in the pressure drop. When the surface energy of the particles is increased from 0.01 J/m2 to 0.04 J/m2, the porosity experiences a modest increase of only 9.1%, yet the pressure drop is significantly reduced by half, amounting to a decrease of 1594 Pa. Under high particle surface energy, as filtration air velocity increases, particles are compressed, resulting in a decrease in cake porosity and an increase in pressure drop. Concurrently, our findings indicate that as the sphericity of particles increases, their surfaces become increasingly smooth which in turn results in a decreased porosity of the cake layer and, consequently, an elevation in the filtration pressure drop.

Architecture differentially affects thermal properties of Song Thrush Turdus philomelos nest walls

ABSTRACT Thermistors embedded on and within the nest wall were used to measure the changes in temperature between different parts of the architecture of the wall of Song Thrush nests as heat from a light bulb was conducted across the wall. The wood pulp forming the nest cup provided the greatest resistance to heat loss across the nest wall. Despite differences in nest mass and architecture, thermal conductance for Song Thrush nest walls were not statistically different from values previously reported for Common Blackbird Turdus merula nests. Song Thrush nests constructed over many years in the same geographical location exhibited an increase in the thickness of the wood pulp cup and a reduction in thermal conductance, i.e. the most recent nests were better insulated. However, nest mass or thermal insulation did not affect reproductive success between years.

Combinatorial processing and evaluation of the phase evolution and oxidation behavior of Hf-Al-Si refractory complex concentrated alloys

Refractory complex concentrated alloys (RCCAs) are a unique group of materials defined by the shared principality between all alloying elements and the tailorable properties at high temperatures (>1000 °C). RCCA systems can be optimized using high-throughput processing which allows for simultaneous characterization and testing over a range of compositions. A compositionally-graded Hf-Al-Si coating was compositionally mapped using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) to identify relative compositions as a function of position on the wafer. High temperature CALPHAD phase diagrams and thermodynamic predictions for a Hf50Al50-xSix alloy and its (Hf50Al50-xSix)1-yOy oxide were coupled with experimental results. The RCCA wafer was heat treated at 1200 °C to observe any phase changes and oxidation behavior at elevated temperatures. Characterization of the RCCA was performed before and after heating using synchrotron radiation X-ray diffraction (SR-XRD) to identify the phases and oxidation states as a function of the compositional gradient and to determine an alloy composition range with the least oxidation. SR-XRD pre- and post-treating revealed an inherent amorphous Hf20Al7Si13 phase across the as-deposited coating, similarities in spectra pre- and post-treating for compositions containing less Hf and more Al and Si relative to the entire gradient film, and the presence of significant HfO2 and Al6Si2O13 oxide for compositions consisting of more Hf and less Al and Si relative to the entire gradient film. The SR-XRD and CALPHAD modeling suggests that compositions of 31–48 at.% Hf, 21–48 at.% Al, and 9–27 at.% Si display the greatest resistance to detrimental oxidation upon heating to 1200 ∘C.

A microstructure-based constitutive model for creep rate and damage of oxide dispersion strengthened high-entropy alloy

Oxide dispersion strengthened (ODS) high-entropy alloys (HEAs) exhibit a great resistance to creep, which has a great application potential on the nuclear energy field. However, the classical creep model hardly considers the coupling effect of the cutting and Orowan bypassing mechanism as well as severe atomic lattice distortion in ODS HEAs, leading to low prediction accuracy. Here, we propose a dislocation theory-based constitutive model for strength and creep rate considering the climbing mechanism, shearing mechanism, and Orowan bypassing mechanism in ODS HEAs. In addition, the effects of the size and spatial distribution of the oxide particle on creep rate and strength are studied. The creep rate and yield strength obtained from the experiments and developed model are compared to verify the rationality and accuracy. The proposed model has demonstrated a high prediction accuracy, with the creep rate and yield strength achieving levels as high as 98.2 % and 98.1 %, respectively. The incorporation of oxide particles within a specific size range and volume fraction has been proven to significantly improve creep resistance. Interestingly, the fracture time has the potential to exceed 41 years, significantly surpassing that Zr-based alloys under the same conditions. This model would be utilized to predict the creep rate in response to a complex applied stress, offering theoretical guidance for the development of ODS HEAs with superior creep resistance for nuclear reactor cladding materials.

Implementation of companding scheme for performance enhancement of optical OFDM structure

Abstract Due to its great spectral efficiency and resistance to multi-path fading, OFDM, or orthogonal frequency division multiplexing, is commonly utilized in optical communication systems. However, because of nonlinear distortions in optical components, OFDM signals are prone to a high peak-to-average power ratio (PAPR), which can severely impair bit error rate (BER) performance. This paper introduces a companding scheme to address high PAPR in optical OFDM systems and improve BER performance. The proposed scheme uses a nonlinear transformation to compress signal peaks and expand valleys, effectively reducing PAPR. Specifically, we investigate the µ-law companding technique, known for its simplicity and effectiveness in handling the active range of OFDM signals in optical communication. The companded signals are transmitted through an optical link and demodulated at the receiver. Simulation results show that the µ-law companding technique substantially reduces PAPR, leading to a significant improvement in BER performance. The companding process maintains signal integrity and spectral efficiency with minimal computational complexity and implementation cost. By mitigating nonlinearities introduced by optical components, this companding scheme enhances the overall reliability and efficiency of the optical OFDM system. An SNR gain of 2 dB–3 dB was achieved at a BER of 10−3.

Pore-scale flooding experiments reveal the thermally regulated flow fields of the curdlan solution

Polymers can enhance oil recovery depending on viscoelasticity. In a field, during polymer flow through porous strata, continuous shear forces result in severe viscosity loss. However, polymers with great shear resistance result in limited migration distance. One solution to the above dilemma is to regulate viscosity, which enables a polymer to migrate long distances through pores with low viscosity and subsequently maintain high viscosity in deep reservoirs. The viscosity of curdlan can be regulated by changing temperature. By curdlan, we mean a biopolymer that shows applications in food industry. However, regarding oil reservoirs, it is unclear whether curdlan viscosity can be effectively regulated in pores. To reveal the feasibility of curdlan viscosity regulation to enhance oil recovery, flooding experiments combined with micro-particle image velocimetry were conducted in a two-dimensional pore network to investigate flow fields of curdlan solutions (0.25%, 0.5%, 1%, and 2%, w/v) at different temperatures (40, 65, and 85 °C). As a result, at 40 °C, curdlan solution (0.25%) easily migrated with low viscosity loss and low adsorption [88.3% original throat diameter (OTD)], and the mobility of curdlan was higher than hydrolyzed polyacrylamide. After heating (65 °C), the viscoelasticity, adsorption (55.1% OTD), and flow resistance (injection pressure, 2.2–8.8 kPa) of curdlan increased, and the greater adsorption capacity of curdlan than xanthan gum led to a more homogeneous flow field [average velocity ratio (Rm), from 2.6 to 1.1]. Since a homogeneous flow field indicated better sweep efficiency, curdlan regulated by temperature could achieve both long-distance migration and improved sweep efficiency in deep strata. These results suggested that viscosity regulation by curdlan could potentially improve oil recovery in water-flooded reservoirs.

Caseinate-coated zein nanoparticles as potential delivery vehicles for guavinoside B from guava: Molecular interactions and encapsulation properties

Guavinoside B (GUB) is a characteristic constituent from guava with strong antioxidant activity; however, its low water solubility limits its utilization. Herein, we investigated the interaction between GUB and zein, a prolamin with self-assembling property, using multiple spectroscopic methods and fabricated GUB-zein-NaCas nanoparticles (GUB-Z-N NPs) via the antisolvent coprecipitation approach. GUB caused fluorescence quenching to zein via the static quenching mechanism. Fourier-transform infrared spectroscopy and computational analysis revealed that GUB bound to zein via van der Waals interaction, hydrogen bond, and hydrophobic forces. The GUB-Z-N NPs were in the nanometric size range (< 200 nm) and exhibited promising encapsulation efficiency and redispersibility after freeze-drying. These particles remained stable for up to 31 days at 4 °C and great resistance to salt and pH variation, and displayed superior antioxidant activity to native GUB. The current study highlights the potential of zein-based nanoparticles as delivery vehicles for GUB in the food industry.

Direct and pleiotropic effects of antimicrobial peptide transgene integration on reproductive, growth regulating, and non-coding loci in channel catfish (Ictalurus punctatus)

Antimicrobial peptides (AMPs) show promise in enhancing resistance against pathogens. Previously, we integrated two AMP genes, cathelicidin (Cath) from alligator (Alligator mississippiensis or Alligator sinensis) and cecropin (Cec) from moth (Hyalophora cecropia), into the channel catfish (Ictalurus punctatus) genome. This study examines the efficacy of exogenous AMP gene integration in improving bacterial resistance in transgenic channel catfish and assesses the direct and pleiotropic effects of gene replacement/knockout on survival and growth based on insertion site. Transgenic Cath- and Cec-expressing fish exhibited similar or higher survival rates (P ​> ​0.05) compared to controls during the initial culture. Integration of the Cec transgene doubled the survival rate when challenged with Edwardsiella ictaluri, with knock-in (KI) of Cath further increasing bacterial resistance. Coupling Cec KI with mstn knockout (KO) increased survival 3-fold after E. ictaluri infection and growth by 50% at 4 months post-fertilization (mpf). However, random integration of Cec had a minimal effect on disease resistance and did not enhance growth. Random integration of Cath increased survival 2.5-fold and 4-fold against E. ictaluri and Flavobacterium covae, respectively, without affecting growth. Cath KI at the lh locus increased survival 4-fold when challenged with F. covae and reduced growth by 10% (P ​> ​0.05) at 24 mpf, whereas Cath KI coupled with mc4r KO resulted in a 2.5-fold increase in survival following F. covae infection compared with controls, and increased growth by 80% at 3 mpf. Simultaneous KI of Cath and Cec, along with KO of mc4r and mstn, increased survival 4-fold against E. ictaluri, while increasing growth by 50% at 3 mpf. Dual insertion of AMP genes yielded the greatest resistance to disease. These direct and pleiotropic effects may increase comprehension and societal acceptance of genetic engineering in aquaculture.

Synthesis of composite membranes modified with graphene oxide and polyethylene glycol for the removal of emerging contaminants from water

Graphene oxide (GO) incorporation of the polymer matrix of membranes can provide properties such as great durability, resistance, and reduction of fouling. In turn, polyethylene glycol (PEG) is a polymer capable of increasing the porosity and flow of membranes. The study aimed to analyze the synthesis of composite membrane polysulfone (PSF), GO and PEG, to separate caffeine, diclofenac sodium, and amoxicillin dispersed in water. It observed an increase in roughness through the incorporation of GO and its reduction with the addition of PEG. Membrane permeability increased from 0.61 L m-2 h-1 bar-1 to 4.54 L m-2 h-1 bar-1 after the addition of GO and PEG. The water permeance of the synthesized membranes reached 37.81 L m-2 h-1 bar-1. It is concluded that the structure and porosity, as well as the rejection of contaminants, were directly influenced by the incorporation of materials added to the membranes. The charge of GO contributed to structural and mechanical improvements of the membranes, reaching rejections of up to 80.61% of caffeine, 66.03% of diclofenac sodium, and 87.33% of amoxicillin with the membrane containing 1.5% of GO, being thus, it is considered promising for applications in water contaminated by emerging contaminants. The study brings real contributions to the area of membranes by developing an improved material, especially as it presents a high rejection of emerging contaminants that are still little studied.

Physico-mechanical Characteristics of the Diaphragms of a Diaphragm Piston Pump Made of Polyurethane Compound

The results of the bench tests of the diaphragms of diaphragm piston pumps made of composite materials based on twocomponent polyurethane filled with basalt fiber are presented. The tests were carried out using a tensile testing machine equipped with special equipment that allows simulating a complex stress-strain state in the diaphragm which is characteristic of pump operation in the real conditions. According to the results of the tests the diaphragms with a basalt content of 1 and 2 vol. % showed the greatest resistance to mechanical loads.

A synergetic effect of ternary refractory nitride reinforcements on densification, mechanical, tribological and thermal stability characteristics of spark plasma sintering-developed Ti6Al4V matrix composites

This paper reports the possibility of developing advanced Ti6Al4V matrix composites (TMCs) with enhanced mechanical properties and highly improved resistance to wear and thermal degradation for structural and high-temperature aerospace applications. The synergetic effect of different weight compositions (1, 1.5 and 2 wt%) of ternary reinforcements consisting of h-BN, TiN and AlN nanoparticles on the characteristics of the microstructure, phase constitution, densification, mechanical, tribological and thermal stability of Ti6Al4V matrix composites developed by spark plasma sintering (SPS) is investigated. The unreinforced Ti6Al4V exhibited a two-phase microstructure made up of α/β phases, however the simultaneous reinforcements resulted in notable microstructural changes and emergence of nitride-rich secondary phases. The relative densities of the composites decrease with increasing reinforcement addition, whereas the nanohardness and elastic modulus values of the composites continue to improve with increasing reinforcement from 1 wt% (28.319 ± 0.525 GPa and 219.43 ± 6.77 GPa) to 2 wt% (55.642 ± 0.693 GPa and 314.59 ± 7.58 GPa) compared to the unreinforced Ti6Al4V (5.838 ± 0.323 GPa and 115.07 ± 3.63 GPa). The unreinforced alloy yields higher average COF values, while the composites at equivalent applied normal loads yield lower average COF values. Thus, in comparison to the unreinforced alloy, the produced composites exhibit considerably lower specific wear rates (with increasing applied normal load). Based on thermogravimetric analysis, the oxidized composite reinforced with 1 wt% of ternary reinforcements exhibits the highest thermal stability in the high-temperature oxidizing environment, as evidenced by its greatest resistance to oxidation and its smallest weight gain of 1.55%.

Effect of Hydrogen Charging on the Mechanical Properties of High-Strength Copper-Base Alloys, Austenitic Stainless Steel AISI 321, Inconel 625 and Ferritic Steel 1.4511

Hydrogen embrittlement (HE) poses the risk of premature failure for many metals, especially high-strength steels. Due to the utilization of hydrogen as an environmentally friendly energy source, efforts are made to improve the resistance to HE at elevated pressures and temperatures. In addition, applications in hydrogen environments might require specific material properties in terms of thermal and electrical conductivity, magnetic properties as well as corrosion resistance. In the present study, three high-strength Cu-base alloys (Alloy 25, PerforMet® and ToughMet® 3) as well as austenitic stainless AISI 321, Ni-base alloy IN 625 and ferritic steel 1.4511 are charged in pressurized hydrogen and subsequently tested by means of Slow Strain Rate Testing (SSRT). The results show that high-strength Cu-base alloys exhibit a great resistance to HE and could prove to be suitable for materials for a variety of hydrogen applications with rough conditions such as high pressure, elevated temperature and corrosive environments.

Resistance reduction characteristics analysis of the tee based on field synergy and viscous dissipation

There has been increasing attention on reducing pipe resistance friction losses, particularly those represented by tees, in heating, ventilation, and air conditioning systems to enhance the sustainability of buildings. This paper analyzes the resistance characteristics, flow patterns, and force conditions of tee, identifies the locations with great resistance losses, and proposes a novel tee with an added the U-shaped deflector. The resistance reduction effect of the U-shaped deflector through field synergy and viscous dissipation is also analyzed. The results indicate that the resistance loss of the tee is mainly from the main-branch pipe section, with the maximum velocity gradient on the outer side of the branch and the inner side of the straight pipe. The fluid resistance friction loss in the section taken by the branch pipe is much greater than that in the main pipe section, the fluid resistance friction loss in the section taken by the main pipe is not affected by the pipe diameter ratio, and the internal friction force accounts for 83 %–92 % of the resistance friction loss in the branch pipe section. Adding the U-shaped deflector can improve the synergy of the velocity and pressure gradient fields downstream of branch pipes and straight pipes, and reduce viscous dissipation. The total local resistance loss reduction rate of the novel tee is 83.15 %, the volume weighted average synergy angle is increased by 2.09°, and the viscous dissipation is reduced by 22.9 %.

Excess-sulphate phosphogypsum slag cement blended with magnesium ion: Part Ⅱ-the long-term microstructure characterisation and phase evolution

Magnesium ions, as the most destructive ions in seawater, significantly affect the durability of cement-based structure. Excess-sulphate phosphogypsum slag cement (ESPSC) with great resistance to chemical attack, exhibits a potential application in marine engineering. As a continuation of previous research, the long-term performance development and microstructure evolution of ESPSC mixed with water including various magnesium ion concentrations (0–0.5 mol/L), are investigated in this study. The results indicate that incorporating magnesium ions within 0.2 mol/L has optimised the later compressive strength, as well as the pore structure. Furthermore, the components and nanostructure of C-(A)-S-H gels change due to the charge balance and cation compensation caused by magnesium ions. The phase evolution of AlⅣ to AlⅥ and an increase in hydration degree have been detected, where the aluminium phase tends to exist stable as ettringite. The M-S-H gel production is detected in samples incorporating 0.5 mol/L magnesium ions at early stage, which is detrimental to the gelatinous structure and strength development of ESPSC. From the perspectives of technological feasibility and environmental requirements, ESPSC production is an effective method for CO2 emission reduction and phosphogypsum utilisation with scalable potential. Introducing magnesium ions through seawater is also regarded as a modification to enhance the mechanical performance of ESPSC.