Wide Range Of Strains Research Articles

Low-Temperature Adaptive Dual-Network MXene Nanocomposite Hydrogel as Flexible Wearable Strain Sensors.

Flexible electronic devices and conductive materials can be used as wearable sensors to detect human motions. However, the existing hydrogels generally have problems of weak tensile capacity, insufficient durability, and being easy to freeze at low temperatures, which greatly affect their application in the field of wearable devices. In this paper, glycerol was partially replaced by water as the solvent, agar was thermally dissolved to initiate acrylamide polymerization, and MXene was used as a conductive filler and initiator promoter to form the double network MXene-PAM/Agar organic hydrogel. The presence of MXene makes the hydrogel produce more conductive paths and enforces the hydrogel's higher conductivity (1.02 S·m-1). The mechanical properties of hydrogels were enhanced by the double network structure, and the hydrogel had high stretchability (1300%). In addition, the hydrogel-based wearable strain sensor exhibited good sensitivity over a wide strain range (GF = 2.99, 0-200% strain). The strain sensor based on MXene-PAM/Agar hydrogel was capable of real-time monitoring of human movement signals such as fingers, wrists, arms, etc. and could maintain good working conditions even in cold environments (-26 °C). Hence, we are of the opinion that delving into this hydrogel holds the potential to broaden the scope of utilizing conductive hydrogels as flexible and wearable strain sensors, especially in chilly environments.

Small Molecules Incorporating Privileged Amidine Moiety as Potential Hits Combating Antibiotic-Resistant Bacteria.

The continuing need for the discovery of potent antibacterial agents against antibiotic-resistant pathogens is the driving force for many researchers to design and develop such agents. Herein, we report the design, synthesis, and biological evaluation of amidine derivatives as new antibacterial agents. Compound 13d was the most active in this study against a wide range of antibiotic-resistant, and susceptible, Gram-positive, and Gram-negative bacterial strains. Time-kill assay experiments indicated that compound 13d was an effective bactericidal compound against the tested organisms at the log-phase of bacterial growth. Docking simulations were performed to assess in silico its mode of action regarding UPPS, KARI, and DNA as potential bacterial targets. Results unveiled the importance of structural features of compound 13d in its biological activity including central thiophene ring equipped with left and right pyrrolo[2,3-b]pyridine and phenyl moieties and two terminal amidines cyclized into 4,5-dihydro-1H-imidazol-2-yl functionalities. Collectively, compound 13d represents a possible hit for future development of potent antibacterial agents.

A Critical Review of Growth Media Recycling to Enhance the Economics and Sustainability of Algae Cultivation

Microalgae hold promise as a sustainable source of biofuels and bioproducts but their commercial development is impeded by high cultivation costs, primarily for growth nutrients, and concerns about the water-intensive nature of algae cultivation. As a result, minimizing water and nutrient input is imperative to reducing algal operating costs, while enhancing the sustainability of future algal biorefineries. However, spent media recycling often results in the accumulation of growth inhibitors, such as free fatty acids, polysaccharides, polyunsaturated aldehydes, and humic acid, which negatively affect algal growth and productivity. In this review, we critically assess media recycling research findings to assess the advantages and disadvantages of spent media reuse for a wide range of algae strains. Particular emphasis is placed on strategies to overcome growth inhibition through spent media treatment processes, such as ultraviolet oxidation, activated carbon, ultrasonication, microfiltration, crop rotation, and nutrient replenishment.

A highly conductive polymer composite with enhanced stretchability and long-term stability for wearable electronic applications

In this study, we investigate the impact of incorporating poly(acrylic acid) (PAA) as a soft polymer on the long-term stability and flexibility (or stretchability) of a highly conductive composite consisting of hydroquinone (HQ)-modified Poly(3,4-ethylenedioxythiophene): poly(styrene-sulfonate) (HQ-PEDOT:PSS). Our findings demonstrate that PAA can effectively act as a steric hindrance barrier between conductive-PEDOT and insulative-PSS, thus improving the stability of the composite over time. Furthermore, the PAA mixture minimizes the conductivity decrease compared to other representative hydrophilic soft polymers, such as poly(vinyl alcohol) (PVA) and poly(vinylpyrrolidone) (PVP). With the addition of 2 wt% PAA to HQ-PEDOT:PSS, the composite exhibits significantly higher conductivity (290 S/cm) compared to PVA (42 S/cm) and PVP (10−3 S/cm). The HQ-PEDOT:PSS/PAA composite also displays excellent stretchability, with a sharp strain response followed by a drastically enhanced gauge factor over a wide strain range (10%–50%). As a result, the composite shows great potential as a strain sensor, with high sensitivity for detecting diverse body motions. Moreover, due to its high conductivity, the composite exhibits high sensitivity for detecting human electrocardiogram (ECG) signals, with negligible degradation of signal intensity even one month after fabrication. Overall, our results suggest that the HQ-PEDOT:PSS/PAA conductive composite has significant potential for wearable smart textile applications, enabling diverse body motion and vital sign sensing.

Transparent, self-adhesive, highly environmental stable, and water-resistant ionogel enabled reliable strain/temperature sensors and underwater communicators

Electronic skins have gained considerable attentions for their promising applications in flexible and wearable electronics. Nevertheless, it remains challenging to realize high performance underwater sensing due to the great differences between the aquatic environment and the land environment. Herein, we developed hydrophobic ionogel consisting of hydrophobic polymer network and ionic liquid with high transparency, good stretchability, temperature-dependent ionic conductivity, long-term environmental stability, and excellent adhesion property. These merits enabled the ionogel-based sensor to be employed as strain and temperature sensor, exhibiting excellent sensing performance, such as wide strain range (0.05−250%), rapid response (100 ms), good durability, broad operating temperature window (−60−100 °C), and high-precision thermosensation (0.05 °C). More interestingly, the superior water-resistance ability of the ionogel endowed the ion-conducting gels with tremendous sensing performance in aqueous environment, performing as a wearable sensor for underwater communication and aquatic animals research.

Microbiological status of anti-SARS CoV-2 protective face masks

The SARS-CoV-2 pandemic situation put extreme pressure on the worldwide medical system from medical personnel to medical equipment. The protective face mask became the front line of anti-SARS-CoV-2 prevention methods, used by most of the world population, more than 7 billion people. The massive demand for face masks activated the world market, where countries from different continents increased their mask production and commercialization worldwide. Unfortunately, the focus on face mask production mostly relied on their ability to filter small-size molecules and less on their microbiological sterile status. Since bacterial structural communities could differ between various large populational groups or continents, in this study, we analyzed the microbial quality of face masks received from various countries/continents. There were analyzed the microbiological load of four types of masks, three from China and one from Romania. The bacterial density from masks was analyzed by membrane filtration and swabbing bacterial collection techniques. The results showed the Romanian mask had a smaller bacterial load than the Chinese masks. In addition, the bacterial identification showed a wide range of bacterial strains, quite different between face mask types.

Highly Robust and Strain-Resilient Thin Film Conductors Featuring Brittle Materials.

Stretchable conductors with stable electrical conductivity under various deformations are essential for wearable electronics, soft robots, and biointegrated devices. However, brittle film-based conductors on elastomeric substrates often suffer from unexpected electrical disconnection due to the obvious mechanical incompatibility between stiff films and soft substrates. We proposed a novel out-of-plane crack control strategy to achieve the strain-insensitive electrical performance of thin-film-based conductors, featuring conductive brittle materials, including nanocrystalline metals (Cu, Ag, Mo) and transparent oxides (ITO). Our metal film-based conductors exhibit an ultrahigh initial conductivity (1.3 × 105 S cm-1) and negligible resistance change (R/R0 = 1.5) over wide strain range from 0 to 130%, enabled by film-induced substrate cracking and liquid metal-induced electrical self-repairing. They could function well under multimodal deformations (stretching, bending, and twisting) and severe mechanical damage (cutting and puncturing). We demonstrated the strain-resilient electrical functionality of metal film-based conductors in a flexible light-emitting diode display that shows high mechanical compliance.

Experimental characterisation of the dilation angle of polymers

Despite the wide use of Drucker-Prager plasticity-based models on polymers, the experimental measurement of the dilation angle, a critical parameter to fully describe the plastic potential, has been rarely reported in existing literature. This paper shows, for the first time, the experimental characterisation of the dilation angle of polymers over a wide range of plastic strain. These measurements were obtained from uniaxial compression experiments conducted on poly(methyl methacrylate) (PMMA) and an untoughened epoxy resin. The calculation of the dilation angle relied on the measurements of the compressive force and the strain components obtained via Digital Image Correlation (DIC). Lower values of dilation angle were obtained for the epoxy resin, suggesting that resistance to volumetric change during plastic deformation could be associated to molecular structure and internal forces. The methodology and results presented in this study can be applied to different types of materials and employed for developing and validating constitutive models that incorporate plastic dilation.

Microstructure and Texture Evolution of Hot-Rolled Mg-3Gd Alloy during Recrystallization

An Mg-3Gd (wt.%) sample with gradient rolling strains (ε = 0–0.55) was prepared using a wedge-shaped plate after one-pass hot rolling, allowing a high-throughput characterization of microstructure and texture over a wide strain range within one hot-rolled plate. The microstructure and texture evolutions were characterized as a function of rolling strain for the as-hot-rolled sample and as a function of annealing temperature for the subsequently annealed samples. The deformed microstructure showed a gradual change with increasing rolling strain, i.e., from a deformation twins-dominant structure in the low strain range of 0–0.20, to a shear bands-dominant structure in the higher strain range of 0.20–0.55. The recrystallization behavior during annealing showed a clear correlation between the recrystallization nucleation site and the deformed microstructure. However, a weak recrystallization texture with non-basal texture components was formed over almost the entire strain range. This work demonstrates a high-throughput experimental strategy using a wedge-shaped sample to investigate the effect of various processing parameters, such as strain and annealing temperature, on the evolution of microstructure, texture, and mechanical properties, which could accelerate the optimization of processing parameters and microstructural design.

High-performance flexible strain sensors prepared by biaxially stretching conductive polymer composites with a double-layer structure

In this work, a high-performance flexible strain sensor was fabricated by biaxial stretching, based on conductive polymer composites (CPCs) with a double-layer structure (DLS) consisting of carbon nanotubes (CNTs)/thermoplastic polyurethane (TPU) and neat TPU. The results show that the DLS design improved the processability of the CPCs during biaxial stretching. The biaxial stretching process reduced the electrical conductivity of the CPCs as a result of the reorganized conductive pathway, while improving the sensing performance of the sensors due to the enhanced dispersion and planar orientation of the CNTs. The resulting 1 wt% DLS sensor (average CNT content = 0.5 wt% in this sensor) prepared with a stretching ratio (SR) of 2.0 shows a wide detectable strain range (0–420%), high sensitivity (GF = 102,571.8), and good stability (1600 cycles). This study provides an important strategy for the development of low-cost and high-performance flexible strain sensors by efficient biaxial stretching and structural design.

Synthetic pentatrideca-valent triazolylsialoside inhibits influenza virus hemagglutinin/neuraminidase and aggregates virion particles

A synthetic multivalent hemagglutinin and neuraminidase inhibitor was developed by the conjugation of a septa-valent triazolylsialoside to bovine serum albumin using di-(N-succinimidyl) adipate. Matrixassisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) confirmed the attachment of five septa-valent sialyl lactosides to the protein backbone, resulting in a pentatrideca-valent sialyl conjugate. This pseudo-glycoprotein demonstrated a high affinity for hemagglutinin/neuraminidase as well as for the drug-resistant NA mutation on the influenza virus surface due to the cluster effect. The conjugate also exhibited potent antiviral activity against a wide range of virus strains without cytotoxicity at high concentrations. Mechanistic studies revealed that the pentatrideca-valent sialyl conjugate bound strongly to the influenza virion particles through interactions with HA/NA on the virion surfaces. The KD of the interaction was approximately 1 μM, as determined by isothermal calorimetric titration, allowing the capture and trapping of the influenza virions and preventing their further infection of host cells. These findings provide insight into the development of new antiviral agents using multivalent sialic acid clusters.

Wrinkle Clamp Down on Structure Crack Strain Sensor Based on High Poisson's Ratio Material for Home Health Monitoring and Human-Machine Interaction.

Flexible wearable crack strain sensors are currently receiving significant attention because they can be used in a wide range of physiological signal monitoring and human-machine interaction applications. However, sensors with high sensitivity, great repeatability, and wide sensing range remain challenging. Herein, a tunable wrinkle clamp down structure (WCDS) crack strain sensor based on high Poisson's ratio material with high sensitivity, high stability, and wide strain range is proposed. Based on the high Poisson's ratio of the acrylic acid film, the WCDS was prepared by a prestretching process. The wrinkle structures can clamp down the crack to improve the cyclic stability of the crack strain sensor while maintaining its high sensitivity. Moreover, the tensile properties of the crack strain sensor are improved by introducing wrinkles in the bridge-like gold stripes connecting each separated gold flake. Owing to this structure, the sensitivity of the sensor can reach 3627, stable operation over 10 000 cycles is achieved, and the strain range can reach about 9%. In addition, the sensor exhibits low dynamic response and good frequency characteristics. Because of its demonstrated excellent performance, the strain sensor can be used in pulse wave and heart rate monitoring, as well as posture recognition and game control.

Highly stretchable, fast self-healing nanocellulose hydrogel combining borate ester bonds and acylhydrazone bonds

Self-healing hydrogels have received considerable attention as a promising material for flexible electronic devices given their mechanical durability and structurally tunable properties. In this study, a highly stretchable self-healing hydrogel with dual cross-linking network was developed via borate ester bonds generated by polyvinyl alcohol and borax, and acylhydrazone bonds formed by aldehyde nanocellulose with adipic acid dihydrazide-modified alginate. Compared with the single network hydrogel composed of polyvinyl alcohol and borax, the introduction of dynamic acylhydrazone bonds greatly increases the flexibility of the hydrogel. The elongation rate increased from 480 % to approximately 1440 %, and the self-healing efficiency increased from 84.6 % to 92.7 % after healing for 60 min at ambient temperature without any stimulus. Moreover, the longer the self-healing time, the more evident the self-healing effect of the acylhydrazone bonds. In addition, electrical measurements confirmed a wide working strain range (ca.1000 %), durability, and reliability. Once assembled as a strain sensor, the hydrogel is able to monitor both large and subtle human motions. Besides, this hydrogel exhibited desirable biocompatibility, as demonstrated by in vitro cytotoxicity towards NIH 3T3 cells. These integrated properties make this nanocomposite hydrogel a promising candidate for future applications as green, flexible, and smart sensors.

Novel gold(III)-dithiocarbamate complex targeting bacterial thioredoxin reductase: antimicrobial activity, synergy, toxicity, and mechanistic insights.

Antimicrobial resistance is a pressing global concern that has led to the search for new antibacterial agents with novel targets or non-traditional approaches. Recently, organogold compounds have emerged as a promising class of antibacterial agents. In this study, we present and characterize a (C^S)-cyclometallated Au(III) dithiocarbamate complex as a potential drug candidate. The Au(III) complex was found to be stable in the presence of effective biological reductants, and showed potent antibacterial and antibiofilm activity against a wide range of multidrug-resistant strains, particularly gram-positive strains, and gram-negative strains when used in combination with a permeabilizing antibiotic. No resistant mutants were detected after exposing bacterial cultures to strong selective pressure, indicating that the complex may have a low propensity for resistance development. Mechanistic studies indicate that the Au(III) complex exerts its antibacterial activity through a multimodal mechanism of action. Ultrastructural membrane damage and rapid bacterial uptake suggest direct interactions with the bacterial membrane, while transcriptomic analysis identified altered pathways related to energy metabolism and membrane stability including enzymes of the TCA cycle and fatty acid biosynthesis. Enzymatic studies further revealed a strong reversible inhibition of the bacterial thioredoxin reductase. Importantly, the Au(III) complex demonstrated low cytotoxicity at therapeutic concentrations in mammalian cell lines, and showed no acute in vivo toxicity in mice at the doses tested, with no signs of organ toxicity. Overall, these findings highlight the potential of the Au(III)-dithiocarbamate scaffold as a basis for developing novel antimicrobial agents, given its potent antibacterial activity, synergy, redox stability, inability to produce resistant mutants, low toxicity to mammalian cells both in vitro and in vivo, and non-conventional mechanism of action.

Tungsten alloy impact fracture for frangible armor piercing

This paper presents experimental and numerical studies of tungsten alloy fragmentation caused by impact loading. Impact loading is a complex mechanics including dynamic hardening and fracture coupled with a wide range of strain, strain rate, and temperature. In order to obtain the dynamic hardening behavior from low to high strain rates, compression tests have been conducted with the INTRON 5583 and the Split Hopkinson Pressure Bar testing machines. Taylor impact tests are also carried out at various impact velocities to evaluate the fragmentation. Considering the fragmentation tendency of tungsten alloy in this study, it could be utilized for the penetrator of FAP projectile. For the further investigation, finite element analysis is performed to predict the dynamic behaviors by using Lim–Huh hardening model and Mohr–Coulomb(MC) fracture model. In the MC fracture model, the mean stress concept is introduced. The fracture model parameters are calibrated using inverse engineering of the test results. The analysis successfully predicts the deformation and fragmentation according to the impact velocity. It is shown that the stress-based Mohr–Coulomb fracture model successfully predicts the direction of crack propagation and fragment size tendencies.

Wide-Range-Sensing Candle Soot/Elastomer Strain Sensors with High Sensitivity

Nowadays, flexible resistive strain sensors attract growing attention owing to their various applications in the fields of electronic skin, human health detection, body motion, etc. Unfortunately, to date, the fabrication of a high-sensitivity soft sensor under a wide-range strain through a simple and cost-competitive approach is still a challenge. In this work, a facile polymer-surface-swelling-adhesion approach was developed to fabricate bilayer candle soot/poly (styrene-b-ethylene-butylene-b-styrene) elastic strain sensors, which obtained a high sensitivity performance at a wide range of strain. When the surface density of candle soot was 0.42 mg/cm2, the gauge factor (GF) values of the sensor were 113, 77, and 177 for various strain ranges of 0%–9%, 9%–60%, and 60%–100%, respectively. The sensor could detect tiny strains such as 0.1% and demonstrated a sensing time of 265 ms at 10% strain. Moreover, after 1000 cyclic loading-unloading at 30% strain, the relative resistance variations remain stable. The sensing mechanism was explained by the tunnel effect for low and medium strain ranges and contact resistance change for the high strain range. As a further step, respiration with a surgical mask, body motion, and road roughness were successfully monitored by using the sensor.

Natural aging of a metastable β-type titanium alloy to simultaneously enhance yield strength and uniform elongation

Natural aging has received little attention in Ti alloys. In the present study, natural aging was detected in a transformation-induced plasticity (TRIP) Ti-15Nb-5Zr-4Sn-1Fe alloy which resulted in a significant increase in the yield strength from 493 MPa to 683 MPa without sacrificing ductility. Natural aging resulted in diffusional coarsening of the ω particles, which decreased the ω-to-β reversibility and impeded the stress-induced β-to-αʹ martensitic transformation under subsequent deformation. Consequently, the stress-induced β-to-αʹ martensitic transformation occurred continuously over a wider range of strains than without natural aging. This led to simultaneous increases in the yield strength and uniform elongation, attributing to enhanced strengthening from the coarsened ω and the more sluggish stress-induced martensitic transformation. These findings demonstrate the potential to regulate stress-induced martensitic transformation and mechanical properties of metastable β-Ti alloys by controlling the development of ω through natural aging.

Differentiated cultures of an immortalized human neural progenitor cell line do not replicate prions despite PrPC overexpression

ABSTRACT Prions are misfolded proteins that accumulate within the brain in association with a rare group of fatal and infectious neurological disorders in humans and animals. A current challenge to research is a lack of in vitro model systems that are compatible with a wide range of prion strains, reproduce prion toxicity, and are amenable to genetic manipulations. In an attempt to address this need, here we produced stable cell lines that overexpress different versions of PrPC through lentiviral transduction of immortalized human neural progenitor cells (ReN VM). Differentiated cultures made from the neural progenitor cell lines overexpressed PrPC within 3D spheroid-like structures of TUBB3+ neurons and we observed evidence that PrPC modulates formation of these structures, consistent with PrPC’s role in neurogenesis. However, through repeated measurements of amyloid seeding activity in 6-week time course experiments, we failed to observe any evidence of prion replication within the differentiated ReN cultures following challenge with four prion isolates (human sCJD subtypes MM1 and VV2, and rodent adapted scrapie strains RML and 263K). We attributed amyloid seeding activity detected within the cultures to residual inoculum and concluded that PrPC overexpression was insufficient to confer permissiveness of ReN cultures to prion infection. While our ReN cell prion infection model was unsuccessful, additional efforts to develop cellular models of human prion disease are highly warranted.

Analysis of the handling and preparation of samples in the resonant column and cyclic torsional shear equipment

In many geotechnical applications, the shear modulus G is the one that governs the dynamic behaviour of the soil, and many fields and laboratory methods are focused on calculating it. This is the case of the resonant column and cyclic torsional shear tests, which allow both the modulus G and the damping D to be obtained in different strain ranges. These laboratory tests are carried out in a triaxial cell and in both tests, torsion is applied to the upper part of the specimens, which has allowed new commercial devices to group both techniques in a piece of a single equipment. The combination of the two tests makes it possible to obtain the dynamic properties of the soil over a wide range of strains, 10-4≤γ≤1%.Due to the small strains reached in these tests, less than 1%, the correct preparation of the specimens and their mounting in the triaxial cell are factors of vital importance for the reliability of the test results. In undisturbed samples, the sample should be handled, and the specimen carved with special care, trying not to alter the structure of the original soil. For remoulded clay specimens, static compaction in an external press and subsequent mounting on the triaxial cell pedestal are recommended. Saturation can present difficulties, as in these tests drainage and saturation can only be carried out from the bottom of the specimen. Consolidation times can be long. Sand specimens should be made by placing a mould on the pedestal of the triaxial cell and applying a vacuum. The method of freezing the specimen is discarded due to the long assembly time.

In-feed nutritional additive probiotic Saccharomyces boulardii RC009 can substitute for prophylactic antibiotics and improve the production and health of weaning pigs.

Non-therapeutic antibiotic use is associated with the current decrease in antibiotic therapeutic efficiency and the emergence of a wide range of resistant strains, which constitutes a public health risk. This study aimed to evaluate the use of Saccharomyces cerevisiae var. boulardii RC009 as a nutritional feed additive to substitute the prophylactic use of antibiotics and improve the productive performance and health of post-weaning piglets. Four regular nutritional phases were prepared. Post-weaning pigs (21-70 days old) received one of two dietary treatments: T1-basal diet (BD-control group) with in-feed antibiotics as a prophylactic medication (one pulse of Tiamulin in P3 and one pulse of Amoxicillin in P4); and T2-BD without in-feed antibiotics but with Saccharomyces boulardii RC009 (1 × 1012 colony forming unit/T feed). The feed conversion ratio (FCR), total weight gain (TWG-kg), and daily weight gain (DWG-kg) were determined. A post-weaning growth index (GI) was calculated and animals (160 days old) from each treatment were analyzed at the abattoir after sacrifice for carcass weight and respiratory tract lesions. Pigs consuming probiotics had higher TWG and DWG than the control group. The group of animals with low body weight obtained the same results. Saccharomyces boulardii administration decreased diarrhea, and FCR reduction was related to a GI improvement. A significant increase in carcass weight and muscle thickness reduction was observed in animals received the probiotic post-weaning. Saccharomyces boulardii RC009, a probiotic additive, was found to improve the production parameters of pigs post-weaning and enhance their health status, indicating that it may be a promising alternative to prophylactic antibiotics.