In this article, a fundamental method based on mutual conductance elimination is proposed for the ultimate decoupling of closely spaced antenna pairs. First, the mutual coupling between radiators is ...characterized by lossy J/K inverters, and the analysis with circuit models shows that the traditional lumped loading method can only suppress the mutual susceptance. Particularly, the decoupling will not be ultimate unless the mutual conductance is further eliminated, which requires equal modal conductance of the odd and even modes of the antenna pair. After that, a method based on antenna-shape modification is proposed, and three types of antennas are designed with characteristic mode analysis (CMA). As for the single-band and wideband patch antenna pairs, by changing the patch shape into a parallelogram and adjusting the patch angle, the modal conductance of the odd and even modes are regulated to be equal, and the isolation is thus significantly improved when compared with the traditional ones to be loaded with lumped elements. As for the inverted-F antenna (IFA) pair, enhanced isolation is achieved by changing the bending configuration, coupling gap, and ground length of the antenna. Good agreement between simulated and measured results shows that all these antennas have achieved isolation over 20 dB.
Methanol steam reforming (MSR) is an attractive option for in-situ hydrogen production and to supply for transportation and industrial applications. This paper presents a novel thermally autonomous ...MSR microreactor that uses silicon carbide (SiC) honeycomb ceramic as a catalyst support to enhance energy conversion efficiency and hydrogen production. The structural design and working principle of the MSR microreactor are described along with the development of a 3D numerical model to study the heat transfer and fluid flow characteristics. The simulation results indicate that the proposed microreactor has a significantly low drop in pressure and more uniform temperature distribution in the SiC ceramic support. Further, the microreactor was developed and an experimental setup was conducted to test its hydrogen production performance. The experimental results show that the developed microreactor can be operated as thermally autonomous to reach its target working temperature within 9 min. The maximum energy efficiency of the microreactor is 67.85% and a hydrogen production of 316.37 ml/min can be achieved at an inlet methanol flow rate of 360 μl/min. The obtained results demonstrate that SiC honeycomb ceramic with high thermal conductivity can serve as an effective catalyst support for the development of MSR microreactors for high volume and efficient hydrogen production.
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•A novel methanol steam reforming microreactor using silicon carbide honeycomb ceramic is proposed.•The methanol steam reactor microreactor has low pressure drop (<1.2 Pa) and short startup time (<9 min).•The energy efficiency of the microreactor is 67.85% at methanol conversion of 86.78%.
•In situ preparing Au nanoparticles by photoreduction in chitosan hydrogels was firstly achieved.•In situ photoreduction for creating Au nanoparticles is environmentally friendly and the operation ...procedure is very simple.•The as-prepared Au nanoparticles have good catalytic performance.•Affording an effective strategy for converting some high explosive compounds such as 2,4,6-tNT to nonexplosive.
Developing hydrogel systems featured by catalytic active is of importance to construct highly effective platforms for removing environmental pollutants/hazardous substances or for bio-/chemosensing. Reported herein are our recent finding that Au nanoparticles could be in situ prepared in chitosan-AuIII hydrogel system via photoreduction, and the as-prepared Au nanoparticles could be employed for the catalytic reduction of a series of nitroaromatic compounds by sodium borohydride (NaBH4). Experimental conditions of synthesizing Au nanoparticles, including pH, concentration of AuIII, and light irradiation time were systematically investigated. The as-prepared Au nanoparticles were characterized by UV–vis absorption spectroscopy, X-ray diffraction (XRD), transmission and field emission scanning electron microscopy (TEM and FESEM). This is the first example for in situ formed metal nanoparticles in chitosan hydrogel systems via photoreduction. The effectiveness of the as-prepared Au nanoparticles as nanocatalysts was evaluated by employing the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4 as a model reaction. The catalytic reduction reaction was found to be very efficient and to follow a pseudo-first-order kinetics. The as-prepared Au nanoparticles demonstrated good reusability and stability. The reduction of a series of other nitroaromatic compounds including highly explosives 2,4,6-trinitrophenol (2,4,6-tNP) and 2,4,6-trinitrotoluene (2,4,6-tNT) was achieved by means of this catalytic system.
This work aims to study the surface modification and reinforcing effect in carbon fiber (CF)/nylon 12 (PA12) composites of CFs, and more importantly, resolves the practical application problems of ...modified CF/PA12 composite powder in selective laser sintering (SLS). CFs were surface modified by nitric acid (HNO3), the surface changes of CFs were characterized by SEM, FT-IR and XPS. Initially, the effects of the experimental factors on the properties of composites were investigated, and the CF/PA12 composite powder prepared with optimized technological parameters was subsequently adopted in SLS experiments. The sintering behavior and relationship between mechanical properties and porosity of sintered specimens were also discussed. The results indicated that the oxygen functional groups on HNO3 modified CFs were partly thermally decomposed and released as gas in the process of laser sintering, which caused high porosity and poor mechanical properties of sintered specimens. Treating CFs at 400°C (approximately the laser sintering temperature) after HNO3 modification was proposed as a solution. This treatment preserved part of the modified effect and reduced the porosity of the composites at the same time. Compared with the unmodified CF/PA12 sintered specimens, the tensile strength, tensile modulus, flexural strength, and flexural modulus were all increased to different degrees.
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•Modified CFs were firstly used as reinforcement phases of composites made by selective laser sintering (SLS).•The interfacial adhesion between fillers and matrix in SLS were firstly discussed.•The oxygenic groups on the surface of CFs were thermally decomposed during the sintering process.•Treating CFs at 400°C after HNO3 modification can decrease the porosity of sintered composites.•The practical application problems of modified CF/PA12 composite powder in SLS were resolved.
Stochastic competitive models with pollution and without pollution are proposed and studied. For the first system with pollution, sufficient criteria for extinction, nonpersistence in the mean, weak ...persistence in the mean, strong persistence in the mean, and stochastic permanence are established. The threshold between weak persistence in the mean and extinction for each population is obtained. It is found that stochastic disturbance is favorable for the survival of one species and is unfavorable for the survival of the other species. For the second system with pollution, sufficient conditions for extinction and weak persistence are obtained. For the model without pollution, a partial stochastic competitive exclusion principle is derived.
A gradual increase in population and urbanization has increased the demand for global resources, which ultimately burdens the depletion of resources and challenges environmental sustainability ...worldwide. In recent decades, nature sustainability has been the biggest challenge encountered by humankind. In addition, the changing lifestyle and consumption patterns have enormously played a key role. However, the consumption pattern from the employee’s perspective suffers from the lack of research. Therefore, grounded on the theory of planned behavior (TPB), this research explores the antecedents and consequences of employees’ buying intentions in the world’s emerging market (China). Data were collected using a web-based link shared
via
WeChat and Q.Q.; resultants into 451 valid responses and partial least square structural equation modeling (PLS-SEM) using SmartPLS 4 have been administered for the analysis. Besides the insignificant effect of descriptive norms on buying intention and environmental concerns on purchasing behavior, other factors significantly impact purchase intention and actual buying behavior. This research witnesses a significant mediating role of buying intention. This research suggests that practitioners (i.e., marketers, government, policymakers, and environmental focus companies) develop strategies for public advertisement and launch a general message and campaigns both in urban and rural areas to prevent environmental sustainability and increases awareness related to organic consumption.
Tebuconazole is a widely used fungicide that has been detected in water ecosystems, of which the concentrations may affect the endocrine function of aquatic organisms. At present study, ...tissue-specific bioaccumulation of tebuconazole was found in ovary of adult zebrafish, indicating a potential risk of endocrine disruption. In order to evaluate the potential endocrine disrupting effects, three life stages (2 hpf (hours post-fertilization) −60 dpf (days post-fertilization), Stage I; 60–120 dpf, Stage II; 180–208 dpf, Stage III) of zebrafish (Danio rerio) were chronically exposed to tebuconazole at the concentrations ranging from 0.05 mg/L to 1.84 mg/L. Result showed that exposed to tebuconazole could lead to a male-biased sex differentiation in juvenile zebrafish and significant decrease of the percentage of germ cells in sexually-mature zebrafish. Egg production was significantly inhibited by 57.8% and 19.2% after Stage II- and Stage III-exposures, respectively. The contents of 17β-estradiol in gonad decreased by 63.5% when exposed to 0.20 mg/L tebuconazole at Stage II and by 49.5% after exposed to 0.18 mg/L tebuconazole at Stage III, respectively. For all stages exposure, reductions in 17β-estradiol/testosterone ratio were observed, indicating an imbalance in steroids synthesis. Additionally, tebuconazole reduced the expression of cyp19a, which was consistent with the decrease of E2 level. In overall, the present findings indicated that, playing as an anti-estrogen-like chemical, tebuconazole inhibited the expression of Cyp19, thereby impairing steroid hormones biosynthesis, leading to a diminished fecundity of zebrafish.
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•Tebuconazole plays as an anti-estrogen endocrine disrupting effects on zebrafish.•Tebuconazole induces a male-biased gonadal differentiation in juvenile zebrafish.•Tebuconazole delays development of germ cells in puberty and adult zebrafish.•Block of E2 pathway may be the disrupting mechanism caused by tebuconazole.
Tebuconazole blocks E2 pathway, thereby leading to a male-biased differentiation in juvenile zebrafish and delaying germ cells development in puberty and adult zebrafish, playing an antiestrogen-like role.
Polyhydoxyalkanoates (PHA) are polyesters produced by microorganisms under unbalanced growth conditions. They are generally biodegradable and thermoprocessable, making them attractive as biomaterials ...for applications in both conventional medical devices and tissue engineering. Over the past years, PHA, particularly poly 3-hydroxybutyrate (PHB), copolymers of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), poly 4-hydroxybutyrate (P4HB), copolymers of 3-hydroxybutyrate and 3-hydroxyhexanoate (PHBHHx) and poly 3-hydroxyoctanoate (PHO) and its composites have been used to develop devices including sutures, repair devices, repair patches, slings, cardiovascular patches, orthopedic pins, adhesion barriers, stents, guided tissue repair/regeneration devices, articular cartilage repair devices, nerve guides, tendon repair devices, bone marrow scaffolds, and wound dressings. The changing PHA compositions also allow favorable mechanical properties, biocompatibility, and degradation times within desirable time frames under specific physiological conditions. This paper reviews what have been achieved in the PHA tissue engineering area and concluded that the PHA prospective will look very bright in the near future.
A wideband circularly polarised patch antenna with multi-section λ/4 transmission lines is proposed. The multi-section lines are directly connected to the patch radiator. The feeding circuit and ...patch are on the same layer, which makes it easy for integration. There is no coupling structure, and consequently, the parasitic radiation from the feeding circuit can be minimised. The whole antenna structure is designed according to the traditional filter design theory. Two minima in the axial ratio response come up to achieve wideband characteristic. Finally, the proposed antenna structure and wideband performances are experimentally verified by an antenna prototype.
Abstract
Background
The R1441G mutation in the leucine-rich repeat kinase 2 (LRRK2) gene results in late-onset Parkinson’s disease (PD). Peripheral inflammation and gut microbiota are closely ...associated with the pathogenesis of PD. Chronic periodontitis is a common type of peripheral inflammation, which is associated with PD.
Porphyromonas gingivalis
(Pg), the most common bacterium causing chronic periodontitis, can cause alteration of gut microbiota. It is not known whether Pg-induced dysbiosis plays a role in the pathophysiology of PD.
Methods
In this study, live Pg were orally administrated to animals, three times a week for 1 month. Pg-derived lipopolysaccharide (LPS) was used to stimulate mononuclear cells in vitro. The effects of oral Pg administration on the gut and brain were evaluated through behaviors, morphology, and cytokine expression.
Results
Dopaminergic neurons in the substantia nigra were reduced, and activated microglial cells were increased in R1441G mice given oral Pg. In addition, an increase in mRNA expression of tumor necrosis factor (TNF-α) and interleukin-1β (IL-1β) as well as protein level of α-synuclein together with a decrease in zonula occludens-1 (Zo-1) was detected in the colon in Pg-treated R1441G mice. Furthermore, serum interleukin-17A (IL-17A) and brain IL-17 receptor A (IL-17RA) were increased in Pg-treated R1441G mice.
Conclusions
These findings suggest that oral Pg-induced inflammation may play an important role in the pathophysiology of LRRK2-associated PD.
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