Responses Of Strips Research Articles

Experimental investigation on the physical parameters of ionic polymer metal composites sensors for humidity perception

Ionic polymer metal composite (IPMC) is one of typical electromechanical transducing materials integrating actuation and sensing functions. In this work, we systematically investigate the evolutions of the capacitance, surface resistance and ionic electrical response of strip shaped IPMC under different humidity conditions. For each parameter, we have performed a set of static and dynamic humidity sensing tests, considering the change of the thickness, cations type and impregnation-reduction plating (IRP) times. Through conducting a series of experiments, it is concluded that the humidity-capacitance sensing has achieved a much wider sensing range (22 % RH - 100 %RH in this work, comparing with 40 % RH - 90 %RH in previous work) and an increased sensitivity (256μF in this work, comparing with140nF in previous work). In the meantime, humidity-surface resistance sensing has the perception of the full humidity range. While the humidity-ionic electrical response sensing can only respond to dynamic humidity changes but showing a very fast response time less than 0.5 s, which will be of great significance in some special humidity detection scenarios, such as the rapid detection and alarm for leakage of equipment with constant humidity. For each case, it implies a fact that the water absorption capacity of surface electrode and inter layer determines the humidity sensing abilities, such as response speed, amplitude and so on.

Ascorbic acid treatment inhibits wound healing of fresh-cut potato strips by controlling phenylpropanoid metabolism

In this study, we investigated the ability of ascorbic acid (AA) to regulate the wound-healing response in fresh-cut potato strips during storage. The results demonstrated that treatments of AA could delay browning, decrease hardening, improve taste, as well as reduce weight loss and respiration rate. Furthermore, AA treatment inhibited wound healing by modulating the activity of phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL), chalcone synthase (CHS) and coumarate-3-hydroxylase (C3H), increasing total phenolics and flavonoid content, and decreasing monomeric phenolic acid content, including caffeic acid, p-coumaric acid, and ferulic acid. The accumulation of lignin and the polyphenolic component of suberin was also reduced. Overall, our results provided information on wound healing and revealed the potential benefits of AA in regulating the process of suberization in potato strips.

Response of strip footing resting on earth bed reinforced with geotextile with wraparound ends using finite element analysis

The usage of reinforcement in the soil mass has resolved the issue of scarcity of suitable land for construction. It has enabled the wise utilization of problematic soils with the application of geotextile as reinforcements. Out of many alternatives of the utilization of geotextile material as a reinforcement element for the soil, the provision of geogrids with wraparound ends offers an improved load-bearing capacity of a foundation and also saves the land space needed for the preparation of the conventional reinforced earth bed. This potential method to improve the load–settlement response of the poor soil strata lacks the proper design recommendations. This paper presents a systematic numerical study to evaluate the optimum geometrical parameters for the improvement in the ultimate load-bearing capacity of a given strip footing resting over the reinforced earth bed. The geometrical parameters of the geotextiles that are considered in this study are: the reinforcement width, lap length of the ends of the reinforcement, the vertical spacing between two consecutive reinforcement layers, the optimum number of the reinforcing layers, and the critical position of the first reinforcing layer from the footing. The abovementioned parameters are modeled by using a finite element method-based numerical tool, and the load–settlement response for a footing of width B = 2 m is studied for multiple layers of reinforcements. This study recommends the optimum depth of the first layer of reinforcement from the bottom of the footing and the width of the reinforcing layers are 0.3 and 1.5 times the width of the footing, respectively.

Expression and function of vasoactive intestinal peptide receptors in human lower esophageal sphincter.

Vasoactive intestinal peptide (VIP) is an important neurotransmitter involved in the modulation of gastrointestinal function through the stimulation of VIP receptors. However, the expression of VPAC1R, VPAC2R and PAC1R in the human Lower esophageal sphincter (LES) has not been fully clarified. Therefore, the purpose of this study is to explore the expression of these receptors in the human Lower esophageal sphincter, the responses of the Lower esophageal sphincter to Vasoactive intestinal peptide, and the role of Vasoactive intestinal peptide receptors in the responses. Sling and clasp fiber samples of LES were acquired from patients undergoing subtotal esophagectomy, while circular muscle bundles from the esophagus and gastric fundus were used as control groups. Western blotting and RT-PCR technology were performed to determine the expression of the three VIP receptor subtypes. The isometric tension responses of the muscle sample strips to Ro25-1553 and PG99-465, and the effect of electrical field stimulation (EFS) on the sling and clasp fibers were studied. We found that VPAC2R messenger RNA (mRNA) and protein were expressed in the sling and clasp fibers of human LES. However, no VPAC1R or PAC1R mRNA and protein expressions were found in the LES samples. The sling and clasp fibers of the LES produced significant concentration-dependent relaxation following exposure to Ro25-1553 and EFS could induce them to produce frequency-dependent relaxation. Furthermore, the relaxation responses of the LES were inhibited by PG99-465 and induced by EFS and Ro25-1553. VPAC2R, but not VPAC1R or PAC1R, is expressed by the human LES. The relaxation responses of the LES generated by the VIP receptor agonist Ro25-1553 and EFS could be inhibited by the selective VPAC2 receptor antagonist PG99-465. VPAC2R may be important for the generation of relaxation and functional regulation of the LES.

Experimental and computational response of strip footing resting on prestressed geotextile-reinforced industrial waste

Geotechnical engineering practices involves the use of geosynthetic as one of the major construction materials for stabilizing terrains and these materials have been also proven to be technically efficient. In view of the above, a series of model load tests with variation in the depth of geotextile and prestressing force were carried out to study the strength and deformation characteristics of ferrochrome slag reinforced with single prestressed geotextile layer. The present study provides a sustainable replacements solution for industrial waste such as ferrochrome slag. It is also found that pretensioning of reinforcements is effective in comparison with simple reinforcement. The load settlement curves demonstrate that reinforcements and prestressing significantly reduce the settlement of a strip footing resting on geotextile-reinforced ferrochrome slag. Also, a pretensioning force of 9 kN/m is found to have the least settlement. Further, this study proposes the use of artificial neural network and extreme learning machine (ELM) to predict settlement using basic input parameters. Application of computational models provides an innovative solution for predicting the settlement of footing with ease and in a cost-efficient manner. The computational model concludes that the developed ELM models are efficient and effective in predicting the settlement of a footing and can be used as a robust tool for preliminary assessments.

Structural and functional indicators of the heart of patients with ischemic heart disease and type 2 diabetes mellitus. Rhythmoinotropic response isolated myocardium at different levels of glycated hemoglobin

BACKGROUND: Adequate glycemic control can significantly reduce the risk of developing cardiovascular events. However, until now, glycaemic targets in aged patients remain a subject of discussion, especially in the conditions of the combined development of Type 2 Diabetes Mellitus (T2DM) and ischemic heart disease (IHD).AIMS: To examine the structural and functional heart parameters in patients with IHD associated with T2DM and the rhythmoinotropic responses of their isolated myocardium depending on glycated hemoglobin level.MATERIALS AND METHODS: The study included 44 patients with a diagnosis of "chronic IHD associated with T2DM", of which 2 groups were formed. Patients with glycated hemoglobin level (HbA1c) <8% were included in the 1st group, and patients with HbA1c ≥8% were included in the 2nd group. The structural and functional heart parameters obtained with ultrasonography, and the rhythmoinotropic responses of myocardium in patients ex vivo were analyzed using the right atrial appendage fragments obtained during elective coronary artery bypass graft. The inotropic response of muscle strips at a basic stimulation frequency of 0,5 Hz to testing influences was assessed. An extrasystolic test and post-rest test were performed.RESULTS: It was found that extrasystolic contractions of isolated myocardial strips in patients of the 2nd group appeared at shorter extrasystolic intervals, which indicates a greater excitability of the myocardium in patients of this group. Postextrasystolic muscle contractions in patients of the 2nd group had significant potentiation. The amplitude of the muscle strips contractions in patients of both groups was potentiative after short rest periods. However, with an increase in the rest duration, potentiation of contractions was observed only in the group with a higher HbA1c level. According to the ultrasonography data, it was found that the values of the endsystolic and diastolic volumes, the interventricular septum thickness and the left ventricular (LV) myocardium mass were significantly lower in the patients of the 1st group compared with the corresponding indicators in the patients of the 2nd group. The early LV filling velocity (peak E) was significantly lower in the patients of the 1st group, which indicates a slower LV relaxation. At the same time, the rapid LV filling velocity did not have a significant intergroup difference, but this indicator exceeded the reference values in both groups.CONCLUSIONS: With a moderately increased glycemic level (9,2 [8,0; 10,3]%), the structural and functional heart parameters are preserved both at the level of the isolated myocardial tissue and at the level of the whole heart.

Deletion of the lysyl oxidase-like 1 gene induces impaired elastin fiber synthesis and inefficient urethral closure in rats.

We investigated the bladder and urethral function in a rat model lacking the protein lysyl oxidase-like 1 (Loxl1). Female nulliparous rats of Loxl1-/- or age-matched wild type (WT) rats had leak-point pressure testing, cystometry, histopathological analyses of lower urinary tract, and contractile response of isolated detrusor strips to carbachol and electric field stimulation. The Loxl1-/- rats showed increased looseness and redundancy of the skin, the decreased intercontraction interval and voided volume in cystometry, the lower leak-point pressure, thinner elastic fibers of the mesentery, bladder, urethra and vagina, and smaller contractile response of detrusor strips to carbachol when compared to the WT rats. Thus, the insufficient hydrostatic mechanism of urethra via submucosal impaired elastin synthesis might reduce the resting urethral closure pressure and the diminished cholinergic contractile response of detrusor smooth muscle might be involved in bladder activity in the Loxl1-/- rats.

Constitutive Models for the Tensile Behaviour of TRM Materials: Literature Review and Experimental Verification.

In recent years, the scientific community has focused its interest on innovative inorganic matrix composite materials, namely TRM (Textile Reinforced Mortar). This class of materials satisfies the need of retrofitting existing masonry buildings, by keeping the compatibility with the substrate. Different recent studies were addressed to improve the knowledge on their mechanical behaviour and some theoretical models were proposed for predicting the tensile response of TRM strips. However, this task is complex due to the heterogeneity of the constituent materials and the stress transfer mechanism developed between matrix and fabric through the interface in the cracked stage. This paper presents a state-of-the-art review on the existing constitutive models for the tensile behavior of TRM composites. Literature experimental results of tensile tests on TRM coupons are presented and compared with the most relevant analytical models proposed until now. Finally, a new experimental study is presented and its results are used to further verify the reliability of the literature expressions.

Структурно-функциональные показатели сердца пациентов с ишемической болезнью сердца и сахарным диабетом 2 типа. Ритмоинотропная реакция изолированного миокарда при разном уровне гликированного гемоглобина

BACKGROUND : Adequate glycemic control can significantly reduce the risk of developing cardiovascular events. However, until now, glycaemic targets in aged patients remain a subject of discussion, especially in the conditions of the combined development of Type 2 Diabetes Mellitus (T2DM) and ischemic heart disease (IHD). AIMS : To examine the structural and functional heart parameters in patients with IHD associated with T2DM and the rhythmoinotropic responses of their isolated myocardium depending on glycated hemoglobin level. MATERIALS AND METHODS : The study included 44 patients with a diagnosis of chronic IHD associated with T2DM, of which 2 groups were formed. Patients with glycated hemoglobin level (HbA 1c ) <8% were included in the 1 st group, and patients with HbA 1c ≥8% were included in the 2 nd group. The structural and functional heart parameters obtained with ultrasonography, and the rhythmoinotropic responses of myocardium in patients ex vivo were analyzed using the right atrial appendage fragments obtained during elective coronary artery bypass graft. The inotropic response of muscle strips at a basic stimulation frequency of 0,5 Hz to testing influences was assessed. An extrasystolic test and post-rest test were performed. RESULTS : It was found that extrasystolic contractions of isolated myocardial strips in patients of the 2 nd group appeared at shorter extrasystolic intervals, which indicates a greater excitability of the myocardium in patients of this group. Postextrasystolic muscle contractions in patients of the 2 nd group had significant potentiation. The amplitude of the muscle strips contractions in patients of both groups was potentiative after short rest periods. However, with an increase in the rest duration, potentiation of contractions was observed only in the group with a higher HbA 1c level. According to the ultrasonography data, it was found that the values of the endsystolic and diastolic volumes, the interventricular septum thickness and the left ventricular (LV) myocardium mass were significantly lower in the patients of the 1 st group compared with the corresponding indicators in the patients of the 2 nd group. The early LV filling velocity (peak E) was significantly lower in the patients of the 1 st group, which indicates a slower LV relaxation. At the same time, the rapid LV filling velocity did not have a significant intergroup difference, but this indicator exceeded the reference values in both groups. CONCLUSIONS : With a moderately increased glycemic level (9,2 [8,0; 10,3]%), the structural and functional heart parameters are preserved both at the level of the isolated myocardial tissue and at the level of the whole heart.

Gastric motor dysfunction coincides with the onset of obesity in rats fed with high-fat diet.

Exposure to a high-fat diet (HFD) has been reported to impair central autonomic and enteric neurocircuitries, however, the relevant mechanisms and their time course are inadequately clarified. This study aimed to investigate the effects of HFD consumption through the period of adolescence on gastric motor functions in adulthood. Male Sprague-Dawley rats consumed a regular diet or HFD (60% kcal by fat) from 4 to 12 weeks of age. Body weight and food intake were monitored weekly. In adult rats, gastric emptying (GE) was measured. Additionally, using in-vitro organ bath, contractile and relaxant responses of antral and fundic strips were assessed with bethanechol and sodium nitroprusside (SNP), respectively. The expressions of choline acetyltransferase (ChAT), neuronal nitric oxide synthase (nNOS) and vasoactive intestinal polypeptide (VIP) were detected by immunofluorescence, whereas, the number of myenteric neurons were evaluated by staining with cuprolinic blue and enteric neuronal marker PGP 9.5. In adulthood, the HFD did not alter food intake, while significantly increasing the body weight. In HFD-fed adult rats, increased visceral fat mass was accompanied by delayed GE. Moreover, bethanechol- and SNP-induced responses were attenuated in antral and fundic tissues. HFD remarkably decreased the number of myenteric neurons and NOS immunoreactivity both in fundus and antrum. HFD remarkably decreased ChAT expression, while increasing the immunoreactivity for VIP in antrum. In conclusion, consumption of HFD between early adolescence and adulthood results in obesity and impairment of gastric motor functions. Particularly, HFD-induced gastric dysmotility appears to be predominantly dependent on the modifications in the non-adrenergic non-cholinergic inhibitory neurotransmission.

Relief of Cadmium-Induced Intestinal Motility Disorder in Mice by Lactobacillus plantarum CCFM8610

Cadmium (Cd) is a toxic metal inducing a range of adverse effects on organs including liver and kidneys. However, the underlying molecular mechanisms of Cd-induced intestinal toxicity through dietary intake is poorly studied. This study evaluated the toxic effects of Cd on intestinal physiology and confirmed the effectiveness of the protective mechanism of the probiotic Lactobacillus plantarum CCFM8610 against chronic Cd toxicity. After treatment with Cd, the HT-29 cell line was subjected to iTRAQ analysis, which revealed that changes in the proteomic profiles after Cd exposure were related to pathways involved in the stress response and carbohydrate metabolism. The results of an animal trial also indicated that 10 weeks of Cd exposure decreased the fecal water content and contractile response of colonic muscle strips in mice, and delayed the excretion time of the first black feces. L. plantarum CCFM8610 treatment provided protective effects against these Cd-induced intestinal motility dysfunctions by recovering the levels of neurotransmitters, including substance P, acetyl cholinesterase, vasoactive intestinal peptide, 5-hydroxytryptamine, calcitonin gene-related peptide, and nitric oxide, and suppressing the cellular stress response in mice (e.g., the inhibition of mitogen-activated protein kinase pathways). The administration of this probiotic was also observed to reduce Cd levels in the tissues and blood of the mice. Our results suggest a newly identified protective mechanism of probiotics against Cd toxicity that involves the recovery of intestinal motility and increase in fecal cadmium excretion.

Spectral Splitting of Resonances in Topological Symmetry-Breaking Gyrotropic Nanostructures

We present a comprehensive study of plasmonic responses of a gyrotropic topological symmetry-breaking Mobius strip in the presence of an external magnetic field. The interplay between the magnetic ...

An inhibitory effect of Berberine from herbal Coptis chinensis Franch on rat detrusor contraction in benign prostatic hyperplasia associated with lower urinary tract symptoms

Ethnopharmacological relevanceCoptis chinensis Franch (CCF), also known as Huang Lian in China, is a traditional Chinese medicine that commonly used for more than 2000 years. Clinically, CCF often used as anti-inflammatory, immune regulation and other effects. It has been reported that the decoction containing CCF can be used for the treatment of benign prostatic hyperplasia (BPH) or lower urinary tract symptoms (LUTS).Aim of the study: This research aims to investigate the effect of CCF on inhibition of BPH development in vivo and in vitro, and further identify the active compound (s) and the possible mechanism involved in BPH-related bladder dysfunction. Materials and methodsOestrodial/testosterone-induced BPH rat model was established as the in vivo model. The prostate index (PI) was calculated, the pathogenesis was analyzed and the micturition parameters were determined in the shamed-operated, BPH model and BPH + CCF groups after 4-week administration. The tension in detrusor strips was then assessed upon KCl or ACh stimulation with or without incubation of CCF or active compounds. To further investigate the signaling involved, rat detrusor cells were cultured as the in vitro models, the instantaneous calcium influx was measured and the ROCK-1 expression was detected. ResultsIncreased PI value and the aggravated prostatic pathology were observed with voiding dysfunction in BPH rats, which were significantly blocked by oral CCF taken. ACh or KCl-induced contractile responses in detrusor strips were significantly inhibited and the micturition parameters were improved when incubation with CCF or its active compounds such as berberine. Both CCF and berberine suppressed the cellular calcium influx and ROCK-1 expression upon ACh stimulation, demonstrating that berberine was one of the active compounds that contributed to CCF-improved micturition symptoms and function. ConclusionsTaken together, our findings give evidence that CCF and its active compound berberine inhibited BPH and bladder dysfunction via Ca2+ and ROCK signaling, supporting their clinical use for BPH and BPH-related LUTS treatment.

Thermoviscoelastic fracture analysis of a cracked orthotropic fiber reinforced composite strip by the dual-phase-lag theory

Fiber-reinforced polymer composites have gained tremendous popularities in various engineering applications due to their superior mechanical performances. This work is devoted to investigating the transient thermomechanical responses of an orthotropic fiber-reinforced strip containing a crack aligned along the fiber direction. The non-Fourier, dual-phase-lag theory is employed to account for the finite time required to complete the process of transporting heat and building local thermal equilibrium in composites, while the Generalized Maxwell viscoelastic model is utilized to characterize the constitutive law of the polymeric matrix and the fibers are treated to be elastic. By using Laplace transform and Fourier transform, the mixed, boundary-value problems are finally reduced to the Cauchy-type singular integral equations, which are solved by the Lobatto-Chebyshev technique numerically. The temperatures and thermal stress intensity factors in the time domain are evaluated through the numerical inversion of Laplace transform. Numerical results are displayed graphically based on graphite fiber reinforced epoxy composite, and detailed comparisons are made to investigate the effects of thermal lags, viscoelastic properties, and fiber volume fractions on the thermoviscoelastic responses.

Experimental Study on GFRP Strips Strengthened New Two Stage Concrete Slabs under Falling Mass Collisions

In the course of global terrorist events prominent risks were faced by military and civilian infrastructure. Subsequently, the design of structures to resist impact load has become vital in the design process. Fibre reinforced polymer sheets were utilized as exceptional material to enhance the resistance of the structure to impact load. Until now, most researchers focused on the response of Fibre Reinforced Polymer (FRP) strengthened slabs under static load. Extensive research on the impact response of FRP strips strengthened slabs is relatively rare and the outcome of these investigations have been controversial. Therefore, it is vital to comprehend the response of FRP strengthened slabs subjected to falling mass collisions. In this study, impact response of Glass Fibre Reinforced Polymer (GFRP) strips strengthened Two Stage Reinforced Concrete Slabs (TSRCS) have been examined through experiments. Two different widths of 50 mm and 75 mm GFRP strips were used in perpendicular and oblique ways in one and two directions while strengthening TSRCS. In Total, a nine 1,000 mm × 1,000 mm × 60 mm TSRCS were fabricated and later impacted by a steel cylinder of 55 kg dropping at the centre from a 3,000 mm height. Study parameters analysed to discover the impact response of TSRCS include, impact-force history, acceleration, damaged area (top and bottom face), damage area ratio, damage volume ratio, and damage pattern. The results revealed that the slab strengthened with 75 mm GFRP strips was more effective in alleviating damage volume ratio compared to the 50 mm GFRP strips. Also, the obtained results in this study shed light on the impact performance of two stage reinforced concrete slabs.

Effect of Nebivolol on the Isolated Rat Bladder Strips Precontracted with Carbachol or Potassium Chloride

Objective: One of the proposed mechanism mediates the vasorelaxant effect of nebivolol is based on its agonistic activity on beta-2 and/or beta-3 adrenergic receptors. These receptors are also involved in the relaxation of urinary bladder. The aim of this study was to explore that the ability of nebivolol to induce relaxation of the isolated rat bladder strip precontracted with cholinergic stimuli using with carbachol or non-cholinergic stimuli using with potassium chloride (KCl). Methods: The isolated bladder strips were mounted in organ bath and contracted by KCl (40 mM) or carbachol(1 µM) before the cumulative addition of nebivolol (0.0001-100 µM). To investigate the role of beta-adrenergic receptors in the nebivolol-induced relaxant response, some bladder strips were incubated with propranolol (1 µM) for 30 min. Statistical significance was tested by Student’s t-test. p&amp;lt;0.05 was considered to be statistically significant. Results: Nebivolol elicited concentration-dependent relaxant response in the bladder strips precontracted with KCl or carbachol. Although the relaxant response to nebivolol in the bladder strips precontracted with carbachol was significantly inhibited by propranolol(p&amp;lt;0.05), the nebivolol-induced relaxation was failed to be inhibited by propranolol in the bladder strips precontracted with KCl. The maximum relaxation in response to nebivolol was found to be significantly higher in the bladder strips precontracted with carbachol compared to that of KCl (p&amp;lt;0.05). Conclusion: The findings of the present study indicate that beta-adrenergic receptors play role in the relaxant response of nebivolol in the isolated rat bladder strip precontracted with carbachol.

Gender-Related Differences of Tachykinin NK2 Receptor Expression and Activity in Human Colonic Smooth Muscle.

The tachykinin NK2 receptor plays a key role in gastrointestinal motor function. Enteric neurons release neurokinin A (NKA), which activates NK2 receptors on gastrointestinal smooth muscle, leading to contraction and increased motility. In patients with diarrhea-predominant irritable bowel syndrome, the NK2 receptor antagonist ibodutant had a greater therapeutic effect in females than males. The present study aimed to determine whether gender influences the expression and activity of NK2 receptors in human colonic smooth muscle. In vitro functional studies were performed to examine the contractile responses of colonic muscle strips to NKA and the selective NK2 receptor agonist [Lys5,MeLeu9,Nle10]NKA(4-10). Contractions were also measured in the presence of ibodutant to determine its antagonistic potency. The signal transduction pathways coupled to NK2 receptor activation were investigated using second messenger inhibitors. Western blot and fluorescent immunohistochemistry were conducted to determine the protein expression and localization of NK2 receptors. NK2 receptor-mediated contractility was greater in females compared with males. When against NKA, ibodutant was more potent in females. NK2 receptor expression increased with age in females, but not in males. Phospholipase C-mediated signaling was less prominent in females compared with males, whereas Ca2+ sensitization via Rho kinase and protein kinase C appeared to be the dominant pathway in both genders. The distribution of NK2 receptors in the human colon did not differ between the genders. Overall, gender differences exist in the expression and activity of NK2 receptors in colonic smooth muscle. These gender distinctions should be considered in the therapeutic development of NK2 receptor agents. SIGNIFICANCE STATEMENT: The tachykinin NK2 receptor has been identified as a therapeutic target for the treatment of bowel and bladder dysfunctions. The present study has revealed gender-related variations in NK2 receptor activity, signaling transduction pathways, antagonist potency, and changes in expression with age. These factors may underlie the gender differences in the treatment of diarrhea-predominant irritable bowel syndrome with NK2 receptor antagonists. Our findings highlight that gender differences should be considered in the therapeutic development of NK2 receptor agents.

A New Approach to Improve IPMC Performance for Sensing Dynamic Deflection: Sensor Biasing

This paper presents a new approach to improve the performance of IPMC-based sensors as reliable deflection sensors. Theoretical and experimental responses of an IPMC sensor strip were investigated when it was being biased by an AC electrical signal source. Using an especially-designed experimental setup, the sensitivity, linearity, and stability of the biased sensor were analyzed under different deflection angles. Moreover, the impact of frequency and amplitude of the bias signal, the influence of internal impedance of the bias signal source, and the effect of mechanical deflection frequency and angle on the performance of the IPMC sensor were studied. Theoretical and experimental results indicated that it would be possible to greatly improve the sensitivity (446.5 times) and stability (24.4 times) of an IPMC deflection sensor by applying an appropriate electrical bias signal.

Development of miniaturized peel experiments to quantify interfacial adhesion between 2D monolayers and viscoelastic polymers

ABSTRACT In this work, a miniaturized peel-testing setup capable of performing peel tests for viscoelastic polymer strips attached to rigid substrate at different peel rates (20 nm/s–20 µm/s) and at constant peel angles (45°–135°) was developed. A mathematical framework accounting for competition between the delamination from rigid substrate as well as bending and extension of the peel arm during the peel test was employed for modeling the viscoelastic response of the soft polymeric strips attached to a rigid substrate. The efficacy of the novel miniaturized peel-testing setup was evaluated for linear elastic and viscoelastic peel arms attached to rigid substrates. The adhesion measurements for the linear elastic peel arms were found to be insensitive to peel angles and the values were in great agreement with standardized macroscale adhesion measurements for the same interface. The peel tests revealed that the interfacial adhesion measurements for the viscoelastic PDMS peel arms were highly sensitive to the nominal peel rates. An elaborate specimen fabrication process was developed to evaluate the interfacial adhesion between large area 2D materials and soft polymer substrates. A series of peel-testing experiments were performed to ensure that the developed fabrication process does not adverse effects on the interfacial adhesion measurements. The peel-testing methodology was then employed to quantify the interfacial adhesion between graphene monolayers and PDMS substrates. Due to the weak van der Waals interactions associated with the graphene/PDMS interface, the interfacial adhesion measurements for this interface was significantly lower than the adhesion values for a PDMS/PDMS interface.

TRPM8 Channel Activation Reduces the Spontaneous Contractions in Human Distal Colon.

The transient receptor potential-melastatin 8 (TRPM8) is a non-selective Ca2+-permeable channel, activated by cold, membrane depolarization, and different cooling compounds. TRPM8 expression has been found in gut mucosal, submucosal, and muscular nerve endings. Although TRPM8 plays a role in pathological conditions, being involved in visceral pain and inflammation, the physiological functions in the digestive system remain unclear as yet. The aims of the present study were: (i) to verify the TRPM8 expression in human distal colon; (ii) to examine the effects of TRPM8 activation on colonic contractility; (iii) to characterize the mechanism of action. Reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting were used to analyze TRPM8 expression. The responses of human colon circular strips to different TRPM8 agonists [1-[Dialkyl-phosphinoyl]-alkane (DAPA) 2–5, 1-[Diisopropyl-phosphinoyl]-alkane (DIPA) 1–7, DIPA 1–8, DIPA 1–9, DIPA 1–10, and DIPA 1–12) were recorded using a vertical organ bath. The biomolecular analysis revealed gene and protein expression of TRPM8 in both mucosal and smooth muscle layers. All the agonists tested, except-DIPA 1–12, produced a concentration-dependent decrease in spontaneous contraction amplitude. The effect was significantly antagonized by 5-benzyloxytryptamine, a TRPM8 antagonist. The DIPA 1–8 agonist resulted in the most efficacious and potent activation among the tested molecules. The DIPA 1–8 effects were not affected by tetrodotoxin, a neural blocker, but they were significantly reduced by tetraethylammonium chloride, a non-selective blocker of K+ channels. Moreover, iberiotoxin, a blocker of the large-conductance Ca2+-dependent K+-channels, but not apamin, a blocker of small-conductance Ca2+-dependent K+ channels, significantly reduced the inhibitory DIPA 1–8 actions. The results of the present study demonstrated that TRPM8 receptors are also expressed in human distal colon in healthy conditions and that ligand-dependent TRPM8 activation is able to reduce the colonic spontaneous motility, probably by the opening of the large-conductance Ca2+-dependent K+-channels.