On determining cluster size of randomly deployed heterogeneous WSNs

Clustering is an efficient method to solve scalability problems and energy consumption challenges. For this reason it is widely exploited in Wireless Sensor Network (WSN) applications. It is very critical to determine the number of required clusterheads and thus the overall cost of WSNs while satisfying the desired level of coverage. Our objective is to study cluster size, i.e., how much a clusterhead together with sensors can cover a region when all the devices in a WSN are deployed randomly. Therefore, it is possible to compute the required number of nodes of each type for given network parameters.     

Multi-objective optimization of transporting blood products by routing UAVs: the case of Istanbul

Since the blood is necessary for surgical operations, disease treatments, chronic disorders, and traumatic accidents, it is staminal to manage the flow in the supply chain of blood products from donors to patients that can save lives. Therefore, this paper focuses on transporting blood products from distribution centers to hospitals in cities by routing unmanned aerial vehicles (UAVs). The problem includes two objective functions as minimizing the used number of UAVs and their total travel distances, simultaneously by considering range, payload weight, and payload volume of UAVs. The problem also covers the blood product demands of hospitals and the supply capacities of distribution centers. A multi-objective integer programming (MOIP) model and three multi-objective metaheuristics are designed to solve the defined problem. To test the effectiveness of the proposed methods, real-life blood product demands of hospitals in Istanbul for the year 2019 are obtained from the Turkish Red Crescent and several scenarios are created as the case study. In scenarios, two types of vertical take-off and landing UAVs are considered, the MOIP is developed by using ILOG, solved via CPLEX, and the metaheuristics are coded in MATLAB. The results reveal that the proposed methods can find good solutions for the problem in acceptable CPU times.     

Synthesis and characterization of novel fluorine‐containing methacrylate copolymers: Reactivity ratios,thermal properties,and antimicrobial activity

The free‐radical‐initiated copolymerization of 2‐(4‐acetylphenoxy)‐2‐oxoethyl‐2‐methylacrylate (AOEMA) and 2‐(4‐benzoylphenoxy)‐2‐oxoethyl‐2‐methylacrylate (BOEMA) with 2‐[(4‐fluorophenyoxy]‐2‐oxoethyl‐2‐methylacrylate (FPEMA) were carried out in 1,4‐dioxane solution at 65°C using 2,2′‐azobisisobutyronitrile as an initiator with different monomer‐to‐monomer ratios in the feed. The monomers and copolymers were characterized by FTIR and ¹H‐ and ¹³C‐NMR spectral studies. ¹H‐NMR analysis was used to determine the molar fractions of AOEMA, BOEMA, and FPEMA in the copolymers. The reactivity ratios of the monomers were determined by the application of Fineman‐Ross and Kelen‐Tudos methods. The analysis of reactivity ratios revealed that BOEMA and AOEMA are less reactive than FPEMA, and copolymers formed are statistically in nature. The molecular weights (M _w and M _n) and polydispersity index of the polymers were determined using gel permeation chromatography. Thermogravimetric analysis of the polymers reveals that the thermal stability of the copolymers increases with an increase in the mole fraction of FPEMA in the copolymers. Glass transition temperatures of the copolymers were found to decrease with an increase in the mole fraction of FPEMA in the copolymers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Motorcycle riders' perception of helmet use: complaints and dissatisfaction

In accidents which involve two-wheeled vehicles the helmet plays a life-saving role, but very little is known about the motorcycle rider's perception of the helmet. We evaluated the relationships between having been involved in an accident and dissatisfaction with the helmet, and between the perception of motorcycle riders and the objective features of the helmet. This was a case-control study: riders of motorized two-wheelers who had been involved in accidents (accident cases) were compared against a similarly interviewed sample of riders that had not been in accidents (control cases). Information about the driver, the vehicle and the helmet was collected in all interviews. To evaluate the relationships, logistic regressions were carried out. The majority of drivers were dissatisfied with their helmets, but no evidence was found to link this dissatisfaction with having been involved in an accident. The two most common complaints related to noisiness, followed by the helmet visor. Complaints did not seem to be statistically associated with physical features of the helmet.     

Interfacial strength and fracture energy of individual carbon nanofibers in epoxy matrix as a function of surface conditions

The interfacial shear strength (IFSS) and fracture energy of individual carbon nanofibers embedded in epoxy were obtained for different surface conditions and treatments by novel, MEMS-based, nanoscale fiber pull-out experiments. As-grown vapor grown carbon nanofibers (VGCNFs) with turbostratic surface and 5 nm peak-to-valley surface roughness exhibited high IFSS and interfacial fracture energy, averaging 106 ± 29 MPa and 1.9 ± 0.9 J/m², respectively. Subsequent high temperature heat treatment and graphitization resulted in drastically reduced IFSS of 66 ± 10 MPa and interfacial fracture energy of 0.65 ± 0.14 J/m². The smaller IFSS values and the reduced standard deviation were due to significant reduction of the fiber surface roughness to 1–2 nm, as well as a decrease in surface defect density during conversion of turbostratic and amorphous carbon to highly ordered graphitic carbon. For both grades of VGCNFs failure was adhesive with clear nanofiber surfaces after debonding. Oxidative functionalization of high temperature heat-treated VGCNFs resulted in much higher IFSS of 189 ± 15 MPa and interfacial fracture energy of 3.3 ± 1.0 J/m². The debond surfaces of functionalized nanofibers had signs of matrix residue and/or shearing of the outer graphitic layer of the VGCNFs, namely the failure mode was a combination of cohesive matrix and/or cohesive fiber failure which contributed to the high IFSS. For all three grades of VGCNFs the IFSS was independent of fiber length and diameter. The findings of this experimental study emphasized the critical role of nanofiber surface morphology and chemistry in determining the shear strength and fracture energy of nanofiber interfaces, and shed light to prior composite-level strength and fracture toughness measurements.     

Reversibility of electric-field-induced mechanical changes in soft tissues

Recently, ultrasound has been used to study the physiological-level electric-field-induced mechanical changes (EIMC) in general soft biological tissues. Here, we present the experimental results on the dependence of EIMC on the polarity of the applied electric field. We applied an ac voltage source to heart tissues and monitored the amplitude changes and time shifting of the ultrasound echoes. The shifting of the echoes was decomposed into a trend component and a fluctuation (feature) component. The changes in amplitude and the fluctuation component of the time shift, but not the trend component of the time shift, can be mostly reversed by reversing the polarity of the applied voltage. The polarity-dependence study reveals two different mechanisms underlying EIMC.     

N‐(hydroxymethyl) acrylamide as a multifunctional finish to cotton and a tether for grafting methacrylamide for biocidal coatings

N‐(hydroxymethyl) acrylamide (NMA) was immobilized on cotton surfaces through etherification, and then methacrylamide (MA) was grafted onto the treated surface. The coatings were characterized by ATR‐IR spectroscopy and were rendered biocidal upon exposure to dilute household bleach. The treated fabrics were challenged with Gram‐negative and Gram‐positive bacteria; both NMA and NMA/MA‐treated fabrics inactivated about 8 logs of Escherichia coli O157:H7 and Staphylococcus aureus within only 5 min of contact time. The coatings were also quite stable toward ultraviolet (UVA) light exposure and repeated laundering. Moreover, a substantial improvement in wrinkle recovery angle was obtained for the NMA/MA‐treated fabrics. The new acyclic acrylamide N‐halamine coating should be less expensive to produce and use than previous cyclic N‐halamine coatings developed in these laboratories. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Heparin Antagonism by Polyvalent Display of Cationic Motifs on Virus‐Like Particles

Particles to the rescue! The construction of cationic amino acid motifs on the surface of bacteriophage Qβ by genetic engineering or chemical conjugation gives particles that are potent inhibitors of the anticoagulant action of heparin, which is a common anticlotting agent subject to clinical overdose.

     

Role of lanthanide elements on the catalytic behavior of supported Pd catalysts in the reduction of NO with methane

In this study, the role of lanthanide elements (Ce, Gd, La, and Yb) on Pd/TiO₂ catalysts in the catalytic reduction of NO with methane was investigated. Steady-state reaction experiments in the presence of oxygen showed that the addition of lanthanide elements increases the oxygen resistance of the catalyst. The post-reaction XPS characterization results revealed that majority of the Pd sites remained in the zero oxidation state in the presence of Ce or Gd. The effect of SO₂ (145 ppm) and H₂O (0–6.6%) in NO–CH₄–O₂ reaction over supported Pd and Gd–Pd catalysts was also investigated. Over the Gd–Pd catalyst with the presence of SO₂, more than 70% NO conversion was obtained for over 6 h while the Pd only catalyst showed a sharper drop in NO conversion. Over the Gd–Pd catalyst, the presence of H₂O showed no effect on NO conversion activity (>99% conversion) during the 18 h the catalyst was kept on stream. Among the lanthanide elements tested, Gd is the most effective, allowing the use of above stoichiometric oxygen concentration.     

Nitrogen-Containing Carbon Nanostructures as Oxygen-Reduction Catalysts

Nitrogen-containing carbon nanostructure (CN _x ) catalysts developed by acetonitrile pyrolysis have been studied to better understand their role in the oxygen reduction reaction (ORR) in PEM and direct methanol fuel cell environments. Additional functionalization of the CN _x catalysts with nitric acid has the ability to improve both the activity and selectivity towards ORR.