Increase In Relative Resistance Research Articles

Conductive compliant mechanisms: Geometric tuning of 3D printed flexural sensors

• The geometric design of MEX fabricated compliant flexural sensors highly influences the measured signal amplitude. • An increase in relative resistance is seen when concentrating the bend to a smaller section and is proportional to the bending force. • Hysteresis of the measured signal, due to material relaxation, increases with the concentration of the bending area. • The reproduced flexural sensors fabricated via MEX show consistent sensor behavior. Additive manufacturing of thermoplastic conductive polymer composites offers interesting opportunities for customizing compliant flexural sensors. The study aimed to show that additive manufacturing could be used to fabricate flexural sensors for evaluating the effect of sensor geometry on the sensor output. Prior literature has primarily focused on material optimization rather than geometrical design. The results of this paper show that the signal amplitude between geometrically different flexural sensors with the same footprint can increase ∼28 times. In addition, the bending force is found proportional to the signal amplitude. Thus, concentrating the bending to a small section increases the signal amplitude but also increases the effect of material relaxation broadening the hysteresis loop. This study highlights the importance of considering the geometrical design when fine-tuning additive manufactured flexural sensors. In future work, it is paramount to improve reproducibility, signal linearity, and investigate the effects of geometry on other sensor parameters.

Multifunctional, flexible and mechanically resilient porous polyurea/graphene composite film

In this study, a porous polyurea/graphene platelet (GnP) composite film with high flexibility and multifunctionality was developed and investigated for strain sensing and energy storage applications. Morphology and mechanical properties were studied; tensile strength and Young’s modulus were enhanced by 132% and 900%, respectively at 5 wt% GnPs. The polyurea/GnP film exhibited high sensitivity to various strains– namely, tension, compression, bending and twisting. In tensile strain, gauge factor was 1.86 and 6.26 within strain ranges of 0–30% and 30–60%, respectively. Interestingly, the film showed piezoresistive and capacitive-type strain sensor under compression load; a 33% increase in relative resistance with response time of 108 millisecond; and 22% increase in relative capacitance with response time of 92 millisecond when load of 5 kPa was applied. Furthermore, the strain sensor showed high durability and reliability over 20,000 cycles. The developed polyurea/GnP film showed a stable capacitive performance over 20,000 charge–discharge cycles. This work provides important insights for the potential of polyurea/graphene films in multifunctional sensors and flexible energy storage applications.

Cohesively Enhancing the Conductance, Mechanical Robustness, and Environmental Stability of Random Metallic Mesh Electrodes via Hot-Pressing-Induced In-Plane Configuration.

Flexible transparent conductive electrode (FTCE) is highly desirable due to the fast-growing flexible optoelectronic devices. Several promising FTCEs based on metal material have been developed to replace conventional indium tin oxide (ITO). The random metal mesh is considered to be one of the competitive candidates. However, obtaining feasible random metal mesh with low sheet resistance, high transparency, good mechanical durability, and strong environmental stability is still a great challenge. Here, a random metal mesh-based FTCE with an in-plane structure, achieved by a facile hot-pressing process, is demonstrated. The hot-pressing process enables the fabrication of highly conductive FTCE with improved mechanical robustness and environmental stability. The in-plane FTCE shows a low sheet resistance of 1.63 Ω·sq-1 with an 80.6% transmittance, low relative resistance increase (RRI) of 7.9% after 240 h 85 °C/85% RH test, and low RRI of 8.0% after 105 cycles of bending test. Besides, various applications of the in-plane FTCE were demonstrated, including the flexible heater, flexible touch screen, and flexible electroluminescence. We anticipate that these results will spark interest in in-plane random metal mesh electrodes and enable the application of random metal mesh in flexible optoelectronic devices.

Influence of Alloying Elements on Cyclic Oxidation Behavior of (Cu/Al) Alloys

This study is conducted to extend the effective life of Cu/Al alloy. The used samples were (Cu/9.5%Al),(Cu/9.5%Al/5%Ni),(Cu/9.5%Al/5%Ni/0.9%Mn),(Cu/%9.5Al/5%Ni/4.5%Fe), (Cu/9.5%Al/5%Ni/0.9%Mn/4.5%Fe),(Cu/9.5%Al/5%Ni/0.9%Mn/4.5%Fe/0,1%Y),(Cu/9.5%Al/5% Ni/0.9%Mn/4.5%Fe/0.2%Ge) by using powder metallurgy these samples were prepared, the cyclic oxidation test was conducted in the presence of air in a programmable furnace (typeVBF-1200X-H8-USA) at 250°C and 800°C for 50 hours at 5-hours cycle. It was represented by the weight-gain of all examined samples that the oxidation rate increased as the temperature increased. It appears that cracking or spalling of oxides was at high temperatures such it found the weight gain of the base alloy (Cu/9.5%Al) was (12.09*10−3g/cm2)at 250°C otherwise, it was (5.98*10−2 g/cm2) at 800°C for the same alloy. This is attributable to the expected behavior of oxides when stressed. The addition of Ni, Mn, & Fe to (Cu/9.5%Al) caused a relative increase in resistance to cyclic oxidation, while the addition 0.1% Y to (Cu/9.5%Al/5%Ni/0.9Mn/4.5%Fe) caused the lowest oxidation rate as compared with other alloys, it showed that the reduction in weight gain (165.13%) relative to(Cu/9.5%Al) the highest weight gain at 250°C, and it was (285.22%) relative to (Cu/9.5%Al/5%Ni) which has highest weight gain at 800 °C. Both alloying elements Y and Ge represented a major change in cyclic oxidation resistance.

Effect of Substrate Strain, Aluminum Thickness and Corona Pretreatment on the Electrical Resistance of Physical Vapor Deposited Aluminum Coatings

Aluminum coatings applied to polymer films by physical vapor deposition should be defect-free for applications such as packaging and electronic devices. However, cracks can appear in the aluminum coating as the polymer film stretches, becoming manifest as an increase in resistance. We evaluated the effect of different aluminum thicknesses (10–85 nm), polymer films (polyethylene terephthalate or polypropylene), and corona doses (0–280 W∙min/m2) on the relative increase in resistance during stretching (strain = 0–100%). We found that the thickness of the aluminum coating was inversely related to the increase in resistance. Corona pretreatment led to an increase in surface energy (≤40 mN/m for polypropylene; ≤50 mN/m for polyethylene terephthalate) although high corona doses resulted in overtreatment, which limited the adhesion of aluminum to the substrate and led to a greater increase in resistance. Varying the coating thickness had a much greater effect than the corona pretreatment, suggesting that thicker aluminum coatings are more effective than corona pretreatment as a strategy to increase coating stability. The effect of aluminum thickness and strain on resistance was described using a fit function containing three fit factors.

Ultimate seismic bearing capacities and failure mechanisms for strip footings placed adjacent to slopes

Assessment of the ultimate bearing capacity of foundations adjacent to slopes is complex as it is highly dependent on the slope geometry and soil properties. Seismic loading may impact both the critical failure mechanism and its associated bearing capacity. The existing approaches for analyzing the seismic bearing capacity of footings near slopes typically employ coefficients developed to fit the conventions of Terzaghi’s bearing capacity equation, herein referred to as the “superposition method.” In this study, a rigorous assessment of the seismic bearing capacity is performed using an upper-bound limit state plasticity framework known as discontinuity layout optimization (DLO), which makes few prior assumptions concerning the failure geometry. Results show that soil properties, slope configuration, and pseudostatic seismic loading all influence the realized failure mechanism and associated bearing capacity. The use of bearing capacity coefficients that fit within the conventional superposition method may underestimate limit loads when the underlying soil provides a relative increase in resistance, but may greatly overestimate bearing capacity when the self-weight of the soil is destabilizing in nature. A set of design charts using direct computational methods for a variety of geometric, geotechnical, and seismic conditions is provided.

Polyaniline emeraldine salt as an ammonia gas sensor - Comparison of quantum-based simulation with experiment

Abstract Polyaniline as a conducting polymer is proposed to react with gas molecules and thus change its electrical conductivity. In this paper, a polyaniline molecule, in the form of emeraldine salt, and its electrical conductivity in or without the presence of NH3 were studied using numerical modeling (Synopsys QuantumATK [1]). From the I-V characteristic of emeraldine salt molecule in the presence and without the presence of ammonia molecule, the effective resistance (R − R0)/R0 was computed and compared with experimental data from [2] and from [3]. Because of only one molecule computation, I-V characteristics comes to saturation (limited amount of charge carriers). The resistance is computed for pure polyaniline (PANI) and PANI with adsorbed ammonia molecule corresponding to approximative ammonia gas concentration of 3 ppm. The relative resistance increase was compared with experimental data and it was shown to be consistent with the measured values. From the results, PANI in the form of emeraldine salt is suitable as a sensing element in NH3 gas sensors.

Emergence of a resistance anomaly by Cu-doping in TaSe3

We have synthesized single crystals doped with Cu atoms in TaSe3 which exhibits no Charge Density Wave (CDW) transition, and measured precisely the temperature dependence of the resistance. We discover an anomalous sharp dip in the temperature derivative of the resistance at about 91 K in Cu-doped TaSe3, which is never observed in pure TaSe3. The dip suggests that there is a phase transition with a relative increase in resistance. In addition, the dip is “γ” shaped. We reveal that the same “γ”-shaped dip in dR/dT is commonly observed at the CDW transition temperature in many CDW conductors, which is a universal consequence resulting from the opening and growth of a CDW gap on a Fermi surface. Furthermore, the result of the single-crystal X-ray diffraction (XRD) analysis implies that Cu-doping increases the lattice parameter of the a-axis and c-axis and decreases that of the b-axis, leading to an improvement in the nesting condition. Based on the “γ”-shaped dip and the result of the single-crystal XRD analysis, we conclude that a CDW emerges by Cu-doping in TaSe3.

Multidrug Resistance-Associated Protein 2 Expression Is Upregulated by Adenosine 5'-Triphosphate in Colorectal Cancer Cells and Enhances Their Survival to Chemotherapeutic Drugs.

Extracellular adenosine 5’-triphosphate (ATP) is a signaling molecule that induces a plethora of effects ranging from the regulation of cell proliferation to modulation of cancerous cell behavior. In colorectal cancer, ATP was reported to stimulate epithelial cell proliferation and possibly promote resistance to anti-cancer treatments. However, the exact role of this danger-signaling molecule on cancerous intestinal epithelial cells (IECs) in response to chemotherapeutic agents remains unknown. To address how ATP may influence the response of cancerous IECs to chemotherapeutic agents, we used Caco-2 cells, which display enterocyte-like features, to determine the effect of ATP on the expression of multidrug resistance-associated protein 2 (MRP2). Gene and protein expression were determined by quantitative real-time PCR (qRT-PCR) and Western blotting. Resistance to etoposide, cisplatin and doxorubicin was determined by MTT assays in response to ATP stimulation of Caco-2 cells and in cells for which MRP2 expression was down-regulated by shRNA. ATP increased the expression of MRP2 at both the mRNA and protein levels. MRP2 expression involved an ATP-dependent stimulation of the MEK/ERK signaling pathway that was associated with an increase in relative resistance of Caco-2 cells to etoposide. Abolition of MRP2 expression using shRNA significantly reduced the protective effect of MRP2 toward etoposide as well as to cisplatin and doxorubicin. This study describes the mechanism by which ATP may contribute to the chemoresistance of cancerous IECs in colorectal cancer. Given the heterogeneity of colorectal adenocarcinoma responses to anti-cancer drugs, these findings call for further study to understand the role of P2 receptors in cancer drug therapy and to develop novel therapies aimed at regulating P2 receptor activity.

Enhancement of Resistance vis-à-vis Defence-Enzyme Activity in Tea Mosquito Bug, Helopeltis theivora Waterhouse (Hemiptera: Miridae) Selected Through Exposure to Sub-lethal Dose of Monochrotophos

Tea industry is the back bone of agro-economy of the tea producing regions. Tea mosquito bug, Helopeltis theivora Waterhouse is one of the most devastating sucking pests of tea and is a menace to tea plantations of North Bengal and other states of NE India. Insecticide forms the mainstay of pest management programme in tea plantations. Insecticide stress and selection have led to the development of high tolerance or resistance in many pests including the sucking bug H. theivora. LC50 value of an organophosphate insecticide, monochrotophos (SL 36 %) to this species increased about 105 fold when selected by exposure to sub-lethal dose for three generations. Generation-wise relative tolerance level when selected by sub-lethal dose of monochrotophos showed a significant increase in 1st and 2nd filial generations as compared to the parental generation (P < F1 < F2). General esterases (GE) activity got enhanced by 5.32 and 16.4 fold, and the activity of cytochrome P450 monooxygenases (CYP) increased by 1.96 and 9.50 fold in F1 and F2 generations respectively as compared to parental generation. The generation-wise increase in relative resistance and the activity of defence enzymes were found to have high positive correlation; r = 0.999 for GE and r = 0.994 for CYP. The study suggests that the titres of GE and CYP in H. theivora can be used as the markers of relative tolerance to insecticides in general, with mode of action similar to monochrotophos. Such defence-enzyme based detection technique for tolerance levels may help early identification of resistant population of H. theivora; hence its management.

The effects of low-high doses of dexmedetomidine on erythrocyte deformability in rats

Dexmedetomidine is an anesthetic agent frequently used for sedation, intensive care units, and general anesthesia. The purpose of our study was to investigate the effect of two different doses of dexmedetomidine on erythrocyte deformability in rats. The study was performed on 21 male rats, with 7 rats in each study group and the control group. The rats in the study groups were administered dexmedetomidine (low dose 5 µg.kg-, high dose 10 µg.kg-) intraperitoneally, and the rats in the control group were administered physiological saline. Erythrocyte packs were prepared using heparinized total blood samples. Deformability measurements were done by erythrocyte suspensions in phosphate buffered saline (PBS) buffer. A constant flow filtrometer system was used to measure erythrocyte deformability, and the relative resistance was calculated. Use of a high dose dexmedetomidine resulted in an increase in relative resistance, which is an indicator for erythrocyte deformability in control rats (p=0.014). High dose dexmedetomidine via negative change in erythrocyte deformability may cause a functional deterioration in blood flow and tissue perfusion. Our results showed that low dose dexmedetomidine protects erythrocyte deformability better than the high dose (Fig. 1, Ref. 23).

Resistance of a Single Domain Wall in(Co/Pt)7Multilayer Nanowires

Single (Co/Pt)_{7} multilayer nanowires prepared by electron beam lithography with perpendicular magnetic anisotropy are locally modified by means of Ga-ion implantation generating 180 degrees domain walls which are pinned at the edges of underlying thin Pt wires. Since we can exclude contributions from the anisotropic and the Lorentz magnetoresistance this allows us to determine the resistance of a single domain wall at room temperature. We find a positive relative resistance increase of DeltaR/R=1.8% inside the domain wall which agrees well with the model of Levy and Zhang [Phys. Rev. Lett. 79, 5110 (1997)10.1103/PhysRevLett.79.5110].

Identification of residues in the first cytoplasmic loop of P-glycoprotein involved in the function of chimeric human MDR1-MDR2 transporters.

The human MDR1 gene encodes the multidrug transporter (P-glycoprotein), a multidrug efflux pump. The highly homologous MDR2 gene product does not appear to be a functional multidrug pump. We have constructed a chimeric protein in which the first intracytoplasmic loop and the third and fourth transmembrane domains of the MDR1 protein were replaced by the analogous region of MDR2. Substitution of the MDR2 sequences encompassing amino acid residues 140 to 229 resulted in 17 amino acid changes, 10 in the intracytoplasmic loop (amino acids 141-188) and 7 in the transmembrane regions. This chimeric protein was expressed on the surface of NIH 3T3 cells where it bound [3H]azidopine but did not confer drug resistance. When only 4 residues, 165, 166, 168, and 169, were changed back to MDR1 amino acids, a functional drug transporter was recovered. When residues 165, 166, 168, and 169 from MDR2 were substituted into a functional MDR1 cDNA, the resulting construction was not able to confer drug resistance. These results indicate that the major functional differences between MDR1 and MDR2 in this region of P-glycoprotein reside in a small segment of the first intracytoplasmic loop. We also independently analyzed the effect of replacing Asn183 of MDR1 with Ser which occurs in MDR2. Substitution of Ser at position 183 in combination with Val at position 185 in P-glycoprotein resulted in a relative increase in resistance to actinomycin D, vinblastine, and doxorubicin in transfected NIH 3T3 cells. These results emphasize the importance of the first intracytoplasmic loop in P-glycoprotein in determining function and relative drug specificity of the transporter.

Magneto-resistance of a highly stable industrial-grade platinum resistance thermometer between 20 and 240 K

The stability and magneto-resistance of a newly introduced Japanese Industrial Standard (JIS) platinum resistance thermometer were studied. The stability was estimated from the change in resistance at the triple point of water after thermal cycles between room temperature and liquid nitrogen temperature. The variation among the resistance values at 20, 50 and 100 cycles was < 1 mK. Its magneto-resistance was measured between 20 and 240 K under a magnetic field B of up to 8 T. The relative resistance increase, ϵ, was found to obey the equation ϵ = D( T) B 2/ [1 + E( T) B]. The fitting error in the field dependence was < 15 mK above 30 K and was about 0.1% of the correction for a magnetic field of 8 T. The parameters D( T) and E( T) are tabulated for the new JIS thermometer and a standard rhodium-iron thermometer.

Contributions oftraTandissgenes to the serum resistance phenotype of plasmid ColV2-K94

A genetic determinant for serum resistance, designated iss, has been found previously on the colicinogenic plasmid ColV2-K94. In this work we have identified a second serum resistance gene, traT, on ColV2-K94. The serum resistance mediated by derivatives of ColV2-K94 was due to presence of one or both of the iss and traT genes. Plasmid pWS12 (TraT+ Iss+) contained the kanamycin (Km) resistance transposon Tn903 inserted near the origin of replication of ColV2-K94, and plasmids pWS15 (TraT+), pWS16 (TraT+) and pWS18 (TraT+ Iss+) were deletion derivatives of pWS12 constructed in vitro and in vivo. pWS12 and pWS18 conferred a 20-fold increase in relative resistance to 20% guinea pig serum when introduced into the serum-susceptible, genetically defined recA strain of Escherichia coli K-12, AB2463. Plasmids pWS15 and pWS16, from which iss had been deleted, still conferred 5-fold increases in relative resistance on AB2463. The level of resistance conferred on this strain by the antibiotic resistance plasmid R100–1 (which expresses the traT serum resistance gene) was comparable to that of plasmids pWS15 and pWS16. The 25-kDa traT gene product was identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the outer membrane proteins of strain AB2463 carrying ColV2-K94. This protein cross-reacted immunologically with the traT protein expressed by F or R100–1. Our results indicated that both traT and iss are capable of mediating serum resistance in ColV2-K94.

Production and annealing of ion-bombardment damage in silicides of Pt, Pd, and Ni

Sheet resistance measurements on polycrystalline films of seven transition-metal silicides have been used to study the production of damage by Ar+-ion bombardment. The sensitivity of the compounds to bombardment, as measured by the relative increase in resistance for a given ion dose, increases in the following order: Pd2Si, Pt2Si, PdSi, Ni2Si, PtSi, NiSi, NiSi2. The heat of formation per metal atom, which is believed to be correlated with the degree of covalent bonding, increases in the same order. In experiments on films of Pd2Si, PtSi, and NiSi2, the difficulty in removing bombardment damage by thermal annealing was found to increase in the same order as the sensitivity to bombardment.

Mechanisms of cation permeation across apical cell membrane of Necturus gallbladder: effects of luminal pH and divalent cations on K+ and Na+ permeability.

Conventional microelectrode techniques were combined with unilateral mucosal ionic substitutions to determine the effects of luminal pH and luminal alkali-earth cation concentrations on apical membrane cation permeability in Necturus gallbladder epithelium. Acidification of the mucosal solution caused reversible depolarization of both cell membranes and increase of transepithelial resistance. Low pH media also caused: (a) reduction of the apical membrane depolarization induced by high K, and (b) increase of the apical membrane hyperpolarization produced by Na replacement with Li or N-Methyl-D-glucamine. These results, in conjunction with estimates of cell membrane conductances, indicate that acidification of the luminal solution produces a reduction of apical membrane K permeability (PK). Addition of alkali earth cations (Mg2+, Ca2+, Sr2+, or Ba2+) produced cell membrane depolarization, increase of relative resistance of the luminal membrane and reduction of the apical membrane potential change produced by a high-K mucosal medium. These results, as those produced by low pH, can be explained by a reduction of apical membrane PK. The effects of Ba2+ on membrane potential and relative apical membrane PK were larger than those of all other four cations at all concentrations tested (1-10 mM). The effect of Sr2+ was significantly larger than those of Mg2+ and Ca2+ at 10 mM, but not different at 5 mM. The reduction of PK produced by mucosal acidification appears to be mediated by: (a) nonspecific titration of membrane fixed negative charges, and (b) an effect of luminal proton activity on the apical K channel. Divalent cations reduce apical membrane PK probably by screening negative surface charges. The larger magnitude of the effects of Ba2+ and Sr2+ can be explained by binding to membrane sites, in the surface or in the K channel, in addition to their screening effect. We suggest that the action of luminal pH on K secretion in some segments of the renal tubule could be mediated in part by this pH-dependent K permeability of the luminal membrane.

Quantum Localization in Amorphous W-Re Alloys

The resistance of amorphous W-Re wires between 2 and 20\ifmmode^\circ\else\textdegree\fi{} K has been measured. Wires with a resistance of approximately 10 k\ensuremath{\Omega} show a different temperature dependence from that of wires with a resistance of over 200 k\ensuremath{\Omega}. The latter show a relative increase in resistance as the temperature is decreased or the magnetic field is increased. These wires also show an anomalous dependence of resistance on width and length. These results are discussed in the perspective of Thouless's suggestion of maximum metallic resistance.

Blood flow in the resting forearm during prolonged contralateral isometric handgrip at maximal effort.

1. In earlier studies we have shown that muscle contraction performed as handgrip at constant force, one third of maximal voluntary contraction (MVC), induces a rapid vasodilation in the resting contralateral forearm which in all probability is neurogenically mediated, followed by a relative increase in resistance.2. The maintenance of contraction at one third MVC for 2 min requires continuously increasing effort because of fatigue, as also evidence by the e.m.g. The biphasic response of the vascular bed may then be related to the increasing intensity of somatomotor activation which is needed to maintain contraction force, or, alternatively, to differences in vasomotor activity on initiation of and continued muscle activity.3. To elucidate these two possibilities blood flow in the resting forearm was measured during contralateral handgrips at constant maximal effort for 6 min (in which case force will drop) and compared to handgrip at constant force, one third MVC, for 2 min.4. The flow reaction during prolonged contraction at maximal effort was similar to that induced by contraction at constant force with a marked transient lowering of vascular resistance, although maximal vasodilation tended to be more pronounced and occur earlier.5. The results indicate that the rapid decrease in vascular resistance is related primarily to the initiation of somatomotor activity, whereas continued muscle contraction produces a relative increase in vasoconstrictor activity irrespective of changes in contraction effort.

The Effects of Ploidy upon Cell Cycle Dependent Changes in X-Ray Sensitivity of Saccharomyces cerevisiae

Comparison of the x-ray responses of cells of isogenic haploid, diploid, and hexaploid strains of Saccharomyces cerevisiae showed that the early budding cells of diploids are significantly more resistant than those of haploids, which are in turn more resistant than those of hexaploids. Studies of synchronous cultures showed that, although with all strains the fraction surviving a single dose oscillates between extreme values during the cell cycle, the haploids showed the longest radioresistant phase and the hexaploids the shortest, and that increase in ploidy diminishes the relative increase in resistance achieved during prebudding and early budding. In view of evidence that budding cell resistance results from repair and the evidence favoring an increasing role with increased ploidy of dominant (relative to recessive) lethal damage in the x-ray inactivation of yeast, it is proposed that budding cell repair is more effective upon recessive than upon dominant lethal damage.