Adsorptive separation of CO<Subscript>2</Subscript> and CH<Subscript>4</Subscript> by the broom sorghum based activated carbon functionalized by diethanolamine

A low-cost activated carbon (AC) was produced from the broom sorghum stalk using KOH as the chemical activating agent, and then the surface of AC was functionalized with diethanolamine to enhance CO₂/CH4 selectivity. Characteristics of pristine and DEA-functionalized ACs were determined through different analyses such as Boehm’s method, BET, FT-IR, SEM, and TGA. The adsorption behavior of pure carbon dioxide and pure methane on these adsorbents was investigated in a temperature range of 288-308 K and pressure range of 0-25 bar using an apparatus based on a volumetric method. Results indicated that amine functionalization significantly improved the selectivity of CO₂/CH₄. The enhancement of CO₂ ideal adsorption selectivity over CH₄ from 1.51 for the pristine AC to 5.75 for the AC-DEA was attributed to adsorbate-adsorbent chemical interaction. The present DEA-functionalized AC adsorbent can be a good candidate for applications in natural gas and landfill gas purifications.     

A constitutive model of thermoviscoelastic semicrystalline shape memory polymer considering viscous dissipation in the amorphous phase

Mathematical modeling has increasingly recognized as a powerful tool that could aid the understanding of shape memory behavior in semicrystalline shape memory polymer (SMP). Up to now, studies have not fully taken into account the viscous effect of the amorphous phase in the whole shape memory cycle, which causes a more realistic prediction of the SMP behavior. In this work, a constitutive thermoviscoelastic model was developed to predict the thermomechanical behavior of semicrystalline SMP. The simulated results of the proposed model for a typical uniaxial deformation were compared with the case having no dissipation effect, also with experimental data. The accuracy improvements in the results of the stress–strain trends together with fixing ratio and recovery ratio obtained from the modified model were significant. The results were in good agreement with the experimental data. The modified model revealed a real and more accurate trend by considering viscous dissipation.     

Reduced Graphene Oxide‐GelMA Hybrid Hydrogels as Scaffolds for Cardiac Tissue Engineering

Biomaterials currently used in cardiac tissue engineering have certain limitations, such as lack of electrical conductivity and appropriate mechanical properties, which are two parameters playing a key role in regulating cardiac cell behavior. Here, the myocardial tissue constructs are engineered based on reduced graphene oxide (rGO)‐incorporated gelatin methacryloyl (GelMA) hybrid hydrogels. The incorporation of rGO into the GelMA matrix significantly enhances the electrical conductivity and mechanical properties of the material. Moreover, cells cultured on composite rGO‐GelMA scaffolds exhibit better biological activities such as cell viability, proliferation, and maturation compared to ones cultured on GelMA hydrogels. Cardiomyocytes show stronger contractility and faster spontaneous beating rate on rGO‐GelMA hydrogel sheets compared to those on pristine GelMA hydrogels, as well as GO‐GelMA hydrogel sheets with similar mechanical property and particle concentration. Our strategy of integrating rGO within a biocompatible hydrogel is expected to be broadly applicable for future biomaterial designs to improve tissue engineering outcomes. The engineered cardiac tissue constructs using rGO incorporated hybrid hydrogels can potentially provide high‐fidelity tissue models for drug studies and the investigations of cardiac tissue development and/or disease processes in vitro.     

Potential benefits of solar reflective car shells: Cooler cabins,fuel savings and emission reductions

Vehicle thermal loads and air conditioning ancillary loads are strongly influenced by the absorption of solar energy. The adoption of solar reflective coatings for opaque surfaces of the vehicle shell can decrease the “soak” temperature of the air in the cabin of a vehicle parked in the sun, potentially reducing the vehicle’s ancillary load and improving its fuel economy by permitting the use of a smaller air conditioner. An experimental comparison of otherwise identical black and silver compact sedans indicated that increasing the solar reflectance (ρ) of the car’s shell by about 0.5 lowered the soak temperature of breath-level air by about 5–6 °C. Thermal analysis predicts that the air conditioning capacity required to cool the cabin air in the silver car to 25 °C within 30 min is 13% less than that required in the black car. Assuming that potential reductions in AC capacity and engine ancillary load scale linearly with increase in shell solar reflectance, ADVISOR simulations of the SC03 driving cycle indicate that substituting a typical cool-colored shell (ρ = 0.35) for a black shell (ρ = 0.05) would reduce fuel consumption by 0.12 L per 100 km (1.1%), increasing fuel economy by 0.10 km L⁻¹ [0.24 mpg] (1.1%). It would also decrease carbon dioxide (CO₂) emissions by 2.7 g km⁻¹ (1.1%), nitrogen oxide (NO_x) emissions by 5.4 mg km⁻¹ (0.44%), carbon monoxide (CO) emissions by 17 mg km⁻¹ (0.43%), and hydrocarbon (HC) emissions by 4.1 mg km⁻¹ (0.37%). Selecting a typical white or silver shell (ρ = 0.60) instead of a black shell would lower fuel consumption by 0.21 L per 100 km (1.9%), raising fuel economy by 0.19 km L⁻¹ [0.44 mpg] (2.0%). It would also decrease CO₂ emissions by 4.9 g km⁻¹ (1.9%), NO_x emissions by 9.9 mg km⁻¹ (0.80%), CO emissions by 31 mg km⁻¹ (0.79%), and HC emissions by 7.4 mg km⁻¹ (0.67%). Our simulations may underestimate emission reductions because emissions in standardized driving cycles are typically lower than those in real-world driving.     

A multi-stage stochastic transmission expansion planning method

This paper presents a multi-stage stochastic model for short-term transmission expansion planning considering the available transfer capability (ATC). The ATC can have a huge impact on the power market outcomes and the power system reliability. The transmission expansion planning (TEP) studies deal with many uncertainties, such as system load uncertainties that are considered in this paper. The Monte Carlo simulation method has been applied for generating different scenarios. A scenario reduction technique is used for reducing the number of scenarios. The objective is to minimize the sum of investment costs (IC) and the expected operation costs (OC). The solution technique is based on the benders decomposition algorithm. The N-1 contingency analysis is also done for the TEP problem.The proposed model is applied to the IEEE 24 bus reliability test system and the results are efficient and promising.     

Rapid synthesis of flower-like ZnO nanostructures

Flower-like ZnO nanostructures were prepared via microwave assisted heating in the presence and absence of ionic liquid (IL). X-ray diffraction analysis (XRD), Scanning electron microscopy SEM and room temperature photoluminescence (PL) spectra have been employed for characterization of the products. The SEM image illustrates the surface of flower-like ZnO prepared in the presence of IL is not smooth and consists of nanoparticles with grain size of about 48 nm. PL spectra of flower-like ZnO in absence and presence IL reveal similar photoluminescence features: a strong UV, weak blue and green-yellow emissions peak at a bout 393 nm, 448 nm and 583 nm respectively. The strong UV photoluminescence and the weak green emission indicate the good crystallization quality of the flower-like nanostructure. The results show that imidazolium-based IL can be used as template for achieving very high level control over the size and shape of nanostructures. The approach developed in this work can potentially be used as a viable method for making various other uniform nanostructures in the presence of IL. This method is simple, fast, low-cost and suitable for large-scale production of ZnO nanostructures.     

Chemoattraction of Neoplastic Glial Cells with CXCL10, CCL2 and CCL11 as a Paradigm for a Promising Therapeutic Approach for Primary Brain Tumors

Chemoattraction is a normal and essential process, but it can also be involved in tumorigenesis. This phenomenon plays a key role in glioblastoma (GBM). The GBM tumor cells are extremely difficult to eradicate, due to their strong capacity to migrate into the brain parenchyma. Consequently, a complete resection of the tumor is rarely a possibility, and recurrence is inevitable. To overcome this problem, we proposed to exploit this behavior by using three chemoattractants: CXCL10, CCL2 and CCL11, released by a biodegradable hydrogel (GlioGel) to produce a migration of tumor cells toward a therapeutic trap. To investigate this hypothesis, the agarose drop assay was used to test the chemoattraction capacity of these three chemokines on murine F98 and human U87MG cell lines. We then studied the potency of this approach in vivo in the well-established syngeneic F98-Fischer glioma-bearing rat model using GlioGel containing different mixtures of the chemoattractants. In vitro assays resulted in an invasive cell rate 2-fold higher when chemokines were present in the environment. In vivo experiments demonstrated the capacity of these specific chemoattractants to strongly attract neoplastic glioblastoma cells. The use of this strong locomotion ability to our end is a promising avenue in the establishment of a new therapeutic approach in the treatment of primary brain tumors.     

An energy-efficient topology construction algorithm for wireless sensor networks

Topology management schemes have emerged as promising approaches for prolonging the lifetime of the wireless sensor networks (WSNs). The connected dominating set (CDS) concept has also emerged as the most popular method for energy-efficient topology control in WSNs. A sparse CDS-based network topology is highly susceptible to partitioning, while a dense CDS leads to excessive energy consumption due to overlapped sensing areas. Therefore, finding an optimal-size CDS with which a good trade-off between the network lifetime and network coverage can be made is a crucial problem in CDS-based topology control. In this paper, a degree-constrained minimum-weight version of the CDS problem, seeking for the load-balanced network topology with the maximum energy, is presented to model the energy-efficient topology control problem in WSNs. A learning automata-based heuristic is proposed for finding a near optimal solution to the proxy equivalent degree-constrained minimum-weight CDS problem in WSN. A strong theorem in presented to show the convergence of the proposed algorithm. Superiority of the proposed topology control algorithm over the prominent existing methods is shown through the simulation experiments in terms of the number of active nodes (network topology size), control message overhead, residual energy level, and network lifetime.