Introduction Of Glycerol Research Articles

Thermoelectric Hydrogel Electronic Skin for Passive Multimodal Physiological Perception.

Electronic skins (e-skins) are being extensively researched for their ability to recognize physiological data and deliver feedback via electrical signals. However, their wide range of applications is frequently restricted by the indispensableness of external power supplies and single sensory function. Here, we report a passive multimodal e-skin for real-time human health assessment based on a thermoelectric hydrogel. The hydrogel network consists of poly(vinyl alcohol)/low acyl gellan gum with [Fe(CN)6]4-/3- as the redox couple. The introduction of glycerol and Li+ furnishes the gel-based e-skin with antidrying and antifreezing properties, a thermopower of 2.04 mV K-1, fast self-healing in less than 10 min, and high conductivity of 2.56 S m-1. As a prospective application, the e-skin can actively perceive multimodal physiological signals without the need for decoupling, including body temperature, pulse rate, and sweat content, in real time by synergistically coupling sensing and transduction. This work offers a scientific basis and designs an approach to develop passive multimodal e-skins and promotes the application of wearable electronics in advanced intelligent medicine.

The strengthening mechanism of mechanical performance for polyurethanes with micro-content crosslinkers

Chemical crosslinking is one widely used method to endow polyurethane (PU) with desirable properties. However, the introduction of crosslinkers in PU elastomers can often lead to the destruction of phase separation, resulting in weakened mechanical properties. Herein, a series of PUs with micro-content crosslinker were synthesized from poly(oxytetramethylene) glycol (PTMG), diphenylmethane-4,4′-diisocyanate (MDI), and chain extender of butane-1,4-diol (BDO) containing varied amounts of glycerol. The phase separation of PUs decreases with increased glycerol content, while the tensile strength increases. To elucidate this enhancement in mechanical properties, morphology investigation with capability of direct observation of components distribution is employed. An increased thickness of interphase between the domain of hard segment (HS) and soft segment (SS) is observed, which indicates that more HS is moved to the interphase upon the introduction of glycerol. The results of electron energy loss spectroscopy (EELS) further disclosed that glycerol formed aggregations located at the interphase. These aggregations increase the crosslinking density of the interphase, which strengthens HS domains and prevents them from being destroyed under tension, thereby increasing the tensile strength. It is the first time of disclosing distribution feature of micro-content crosslinker of PU as well its strengthening mechanism in tensile strength, which could assist in developing PU with desirable mechanical properties.

Highly tough and ionic conductive starch/poly(vinyl alcohol) hydrogels based on a universal soaking strategy

High-performance hydrogels with favorable mechanical strength, high modulus, sufficient ionic conductivity and freezing resistance have far-ranging applications in flexible electronic equipment. Nevertheless, it is challenging to combine admirable mechanical properties and high ionic conductivity into one hydrogel. Herein, a facile strategy was developed for the preparation of the hydrogel with excellent strength (1.45 MPa), super Young's modulus (8.85 MPa) and high conductivity (1.47 S/m) using starch and poly(vinyl alcohol) (PVA) as raw materials. The starch/PVA/Gly/Na3Cit (SPGN) gel was firstly cross-linked by crystalline regions of PVA upon freezing-thawing cycles. It was further immersed in the saturated Na3Cit solution to enhance the interaction between the substrates through the salting-out effect. The effect of soaking time on the crystallinity, intermolecular interactions, mechanical and electrical properties of SPGN gel was demonstrated by X-ray diffraction, Fourier transform infrared spectroscopy, tensile and impedance testing measurements. The introduction of glycerol and Na3Cit also endowed SPGN gels with favorable anti-freezing properties. The SPGN gel could maintain high mechanical flexibility and ionic conductivity at −15 °C.

Anti-freezing, water-retaining, conductive, and strain-sensitive hemicellulose/polypyrrole composite hydrogels for flexible sensors

High-performance conductive hydrogels are desired for the development of flexible wearable sensors. However, it remains a challenge to simultaneously realize high stretchable, freezing tolerance, and attractive conductivity through a simple approach. In this work, we present stretchable, water retention, anti-freezing, and conductive hemicellulose/polypyrrole (H/PPY) composite hydrogels for application in epidermal strain sensors via freezing-thawing method. The composite hydrogels were obtained using hemicellulose as a hydrophilic carrier and polypyrrole as a conductive matrix. The freezing and thawing temperatures of the hydrogels decreased and the conductivity increased benefiting from the introduction of glycerol and NaCl. The hydrogels had good mechanical properties, remodeling ability and water retention after storage for 7 days. In addition, the strain sensors assembled by hydrogels accurately monitored the signals of human motions with good strain sensing durability. It is expected that the as-prepared hydrogels have the potential to be applied in the fields of wearable devices.

Experimental evaluation of Pt/TiO2/rGO as an efficient HER catalyst via artificial photosynthesis under UVB & visible irradiation

The study investigated the synergistic effects of rGO and Pt over TiO2 for the HER via artificial photosynthesis under UVB and visible light irradiation. The introduction of glycerol and industrial wastewater to the system as sacrificial reductants signifies that the major reaction pathway is photocatalytic partial water splitting. The material characterizations revealed successful heterojunction formation and provided insight into chemistry behind the activity of the photocatalysts. Amongst various combinations of rGO on TiO2, 1GNT exhibited an HER yield five times that of bare TiO2 under UVB light. Addition of Pt led to the formation of a strong Schottky barrier at the heterojunction and consequently boosted HER performance. 1P0.5 GT presented the highest of 28.5 mmol g−1 h−1 with glycerol and 9.6 mmol g−1 h−1 with wastewater under UVB light respectively. For both binary and ternary photocatalysts, the HER performances dwindled under visible light irradiation, accentuating the insufficient activation of the TiO2. In addition, 1PT outperformed all the other photocatalysts thereby elucidating the impression that rGO and Pt does not work well together in enhancing HER despite quenching the exciton recombination rate of TiO2 significantly. The role of pH in the synthesis and the experiments has been discussed. Finally, the underlying mechanisms in the photodeposition and photoreformation have been proposed.

Effect of Additive Glycerol on Piezoelectric Properties of Modified Sol-Gel (Ba<sub>0.85</sub>Ca<sub>0.15</sub>)(Ti<sub>0.9</sub>Zr<sub>0.1</sub>)O<sub>3 </sub>Ceramics

Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCTZ) ceramics, one of the lead-free pizoelectric materials, were focused due to the environmental concern against lead. A modified BCTZ powder sol-gel fabrication process was experimentally introduced with the addition of glycerol, in order to provide an effective approach to optimize the piezoelectric response of BCTZ ceramics. The results showed that the piezoelectric properties enhanced in terms of the piezoelectric coefficient of d33, 510 pC/N and the electromechanical coupling coefficient of kp, 0.501. The enhancement in electrical properties, such as dielectric, ferroelectric and piezoelectric, could be related to the homogenous microstructure and larger grain size of BCTZ ceramic powders after the introduction of glycerol during the modified sol-gel strategy.

Пластифицированные плёнки на основе сукцинила хитозана

The article is devoted to the development of new approaches to the creation of modern wound healing highly elastic films with good hemocompatibility based on a water-soluble chitosan derivative – the succinyl of chitosan. These trips are based on the use of plasticizers. It was established that chitosan succinyl, in contrast to chitosan, is capable of exhibiting insignificant forced-elastic deformation, but still not sufficient to use unmodified films based on it as wound healing coatings. The deformation-strength properties of the films were studied on a universal tensile testing machine. The tensile stress (σ) was determined taking into account the cross-sectional area of the sample taken for testing, and expressed in MPa. The elongation at break (ε) was calculated taking into account the initial length of the film sample taken for testing, and expressed as a percentage. The values of elongation at break and tensile stress were calculated as the arithmetic average of five parallel measurements. The hemocompatibility of chitosan-glycerol succinyl systems was evaluated by determining the osmotic resistance of healthy human erythrocytes using a unified method in the modification of L.I. Idelson. It is shown that the introduction of glycerol as a plasticizer in the process of film formation leads to a significant improvement in their physical and mechanical characteristics. An increase in the glycerol content in the film up to 50 wt% is accompanied by a significant increase in tensile elongation. The value of the breaking stress in this case, naturally decreases. But, since the value of the breaking stress in any case remains at the level of the necessary values, the observed drop in strength indicators is not fundamental. The stabilizing effect of the succinyl of chitosan-glycerin systems on cell membranes under physiological conditions is proved, which suggests their high hemocompatibility.

Regularities of formation of adhesive contact “sol-silicate paint - substrate”

Introduction. The use as a binder in the manufacture of silicate paints polysilicate solutions obtained by mixing liquid glass and silica sol is considered. To regulate the rheological properties of the paint, improve the filling and prevent the pigment part from sagging, it has been proposed to introduce glycerin into the binder composition. The results of studying the interfacial interaction between the paint and the substrate are given. Materials and methods. In developing the formulation of silicate paints based on polysilicate solutions, MK-2 microcalcite, marshalite, diatomite and talc of MT-GSM grade were used as a filler, and titanium dioxide as a pigment. Polysilicate solutions were obtained by reacting stabilized solutions of colloidal silica (sols) with aqueous solutions of alkali silicates (liquid glasses). Nanosil 20 and Nanosil 30 silicic acid sol were used, produced by the Promsteklocentr PC. Used potassium liquid glass with module M = 3.29. A thermodynamic method was used to assess the interfacial interaction. Results. Shown that the introduction of glycerol into the formulation of a sol of silicate paint promotes a decrease in the interfacial surface tension and a better wetting of the surface of the mortar substrate. An increase in wetting coefficient is observed. Coatings based on sol silicate paints with the addition of glycerin are characterized by increased crack resistance. An increase in tensile strength, maximum tensile properties, and decrease in the elastic modulus of paint membranes based on the composition with glycerol has been established. The values of the free surface energy of the coating based on the sol of silicate paint and the ratio of the polar to the dispersion component of the free energy of the surface are given. Coatings based on sol of silicate paint with the addition of glycerin are characterized by a large value of the free energy of the surface. In the process of moistening a decrease in the free surface energy is observed due to a decrease in the dispersion component. Conclusions. Studies have shown that the introduction of an additive of glycerin in the formulation of a silicate paint sol contributes to an increase in the performance properties of coatings based on it.

Influence of preliminary introduction of placenta cryoextracts on ultrastructure of rat’s adrenal gland glomerular zone with acute renal failure.

Background. When developing new available methods of restorative correction of renal function in renal insufficiency, the placenta preparations are increasingly used. The course of acute renal failure and its transformation into a chronic form significantly affects aldosterone, that is one of the links of the hypothalamic-pituitary-adrenal system. Determination of ultrastructural adrenocorticocyte changes in the glomerular zone of adrenal glands and the level of saturation of cells with lipids will allow judging the degree of this hormone secretion. The objective of the research was to investigate the ultrastructure of cells of adrenal cortex glomerular of rats with acute renal failure when introducing the placenta cryoextracts of allogeneic and xenogeneic origin prior to the renal pathology simulation. Methods. The research object were 65 white male rats aged 4 months. Animals were givenwith the cryoextracts of placental tissue of various origins by 0.5 ml three times a week. A week after the introduction of cryoextracts, renal insufficiency was modeled by intramuscular injection of 50% aqueous solution of glycerol in a dose of 10 ml per 1 kg body weight. Animals were divided into 3 groups: 1 - rats with the simulated renal failure; 2, 3 - rats with simulated renal failure, which were pre-administered with cryoexracts of the rat and human placenta, respectively. Animals were withdrawn from the experiment to the first, second and third week after the introduction of glycerol. The ultrastructure of the cells was examined using an electron microscope PEM-125K (Selmi JSC). Results. Within 3 weeks of glycerol model of an acute renal failure, regardless of the previous administration of either rat’s or human placenta cryoextracts the ultrastructure of adrenocorticocytes of glomerular zone showed the signs of strengthening steroidogenesis, which were manifested by hypertrophy of endoplasmic reticulum and mitochondria, swelling of mitochondria, formation of myelin-like structures and mitochondrial vacuoles as well as tight mitochondrial complexes, endoplasmic reticulum and liposomes. Conclusion. The signs of increased steroidogenesis in glomerular zone of rat’s adrenal cortex were most pronounced when introducing the xenogeneous cryoextracts of placenta prior to the start of pathology modeling.

A TECHNIQUE FOR PURIFICATION OF HYBRID RECOMBINANT E7 ONCOPROTEINS OF 16 AND 18 TYPES OF HUMAN PAPILLOMA VIRUS CONJUGATED WITH HEAT SHOCK PROTEIN70

A nickel-chelate affinity chromatography has been used to isolate fused proteins of Hsp70-E7 from yeast lysate at the initial stage of the work. The low purity of the monomeric Hsp70-E7 in the final fraction was associated with the occurrence of dimeric and tetrameric forms of the target protein and low-molecular impurities. A modification of the purification procces by the addition of reduced L-glutathione to inhibit the formation of unwanted disulfide bonds permitted to increase the purity of the target protein by reducing the content of the oligomerized products. Further changes in the purification protocol, namely the reduction of hydrophobic interactions by the introduction of glycerol, significantly reduced the amount of low-molecular impurities. For a finer purification of E7-HSP70, a two-stage process of anion-exchange chromatography that made it possible to effectively eliminate low-molecular impurities was used. The assessment of the final material by electrophoresis under non-reducing conditions showed that the purity of the monomeric forms of either of the proteins was higher than 95%.

Nano-Li4Ti5O12 with high rate performance synthesized by a glycerol assisted hydrothermal method

Here we report a facile approach to synthesize pure nano-Li4Ti5O12 by a glycerol assisted hydrothermal process and subsequent thermal treatment. During the hydrothermal process, the introduction of glycerol helps to control the morphologies of products and significantly improve the electrochemical performance of Li4Ti5O12 as an anode material. On the other hand, an accurate Ti:Li ratio is controlled in order to obtain pure Li4Ti5O12 since the Ti:Li ratio of starting materials sensitively impacts the final composition of product. X-ray diffraction, thermogravimetric-differential scanning calorimetry, field-emission scanning electron microscopy and transmission electron microscopy are used to characterize their structures and morphologies. The glycerol assisted sample annealed at 500 °C can retain a discharge capacity of 154 mAh g−1 after 500 cycles at 5 C and deliver a high discharge capacity of 155 mAh g−1 at 20 C. The excellent cycling and rate performance can be attributed to the minor particle size, lower charge-transfer resistance (15.8 Ω) and larger lithium ion diffusion coefficient (4.32 × 10−11 cm2 s−1).

Relaxation kinetics of cytochrome P450 reductase: internal electron transfer is limited by conformational change and regulated by coenzyme binding.

The kinetics of internal electron transfer in human cytochrome P450 reductase have been studied using temperature-jump relaxation spectroscopy. Temperature perturbation of CPR reduced at the two-electron level with NADPH yields biphasic absorption transients at 450 and 600 nm. The observed rate, 1/tau, for the fast phase is 2200 +/- 300 s(-1). The absence of this phase in fluorescence transients and in absorption transients collected with dithionite-reduced enzyme indicates this phase does not report on electron/hydride transfer and is consistent with its origin in local conformational change in the vicinity of the FAD isoalloxazine ring. The slow phase (1/tau = 55 +/- 2 s(-1)) observed in the absorption transients obtained with CPR reduced at the two-electron level with NADPH reports on internal electron transfer: FAD(sq)-FMN(sq) --> FAD(ox)-FMN(hq). The observed rate of this transient is slower (1/tau = 11 +/- 0.5 s(-1)) in CPR reduced to the two-electron level by dithionite rather than NADPH, demonstrating that coenzyme binding has an important influence on the observed rate of internal electron transfer. Temperature perturbation experiments with CPR reduced with 10-fold molar excess of NADPH produce monophasic absorption transients (1/tau = 20 +/- 0.2 s(-1)) reporting on internal electron transfer: FAD(sq)-FMN(hq) --> FAD(hq)-FMN(sq). The observed rate constants for electron transfer are substantially less than those expected from analysis of CPR by electron-transfer theory (approximately 10(10) s(-1)). Potential gating mechanisms have been investigated using the temperature-jump method. Observed rates for electron transfer were unaffected in experiments performed in deuterated solvent, indicating that deprotonation does not gate the reaction. Introduction of glycerol into the sample significantly decreased the observed rate for internal electron transfer, suggesting conformational gating of the reaction. Replacement of Trp-676 with His-676 reduces approximately 2-fold the observed rate of internal electron transfer in two-electron-reduced enzyme, whereas the observed rate for FAD(sq)-FMN(hq) --> FAD(hq)-FMN(sq) transfer is increased approximately 13-fold in the W676H mutant reduced with a 10-fold molar excess of NADPH. The studies reveal altered redox properties of the FAD in W676H CPR. The data are discussed in the context of previous stopped-flow studies of human CPR and the X-ray crystallographic structure of rat CPR.

Stereoselective Reduction ofα- andβ-Keto Esters with Aerobic Thermophiles,BacillusStrains

The first example of stereoselective reduction with aerobic thermophiles is reported. Various α- and β-keto esters were reduced stereoselectively to the corresponding alcohols by the aerobic thermophiles, Bacillus strains. In particular, the reduction of ethyl 3-methyl-2-oxobutanoate with B. stearothermophilus DSM 297 gave the corresponding (R)-alcohol with high yield in excellent enan-tioselectively (> 99% e.e.). The conversions of keto esters to the corresponding hydroxy esters with Bacillus strains were increased by introduction of glycerol in the reaction mixture as an additive.

Study of cryostructuration of polymer systems. XI. The formation of PVA cryogels by freezing–thawing the polymer aqueous solutions containing additives of some polyols

AbstractThe influence of the presence of some polyols in initial poly(vinyl alcohol) aqueous solutions on rheological and thermal properties of the cryogels, which were produced by the freezing–thawing method, was investigated. The polyol additives (cosolvents) were as follows: glycerol, propylene glycol, mono‐, di‐, and triethylene glycols, and oligoethylene glycols (PEG‐400 and PEG‐1000). It was shown that the introduction of glycerol, propylene, or ethylene glycols into the polymer solution resulted in a decrease of cryogel's shear modulus and fusion temperature, whereas the use of triethylene and higher ethylene glycol oligomers as cosolvents gave rise to an increase in the gel's strength and thermostability, and diethylene glycol exhibited a transitional influence. The possible mechanism of the action of reinforcing cosolvents is discussed. © 1995 John Wiley & Sons, Inc.

Photothermal formation of copper conductors on multichip module substrates using a Nd:YAG laser

A simple method for laser direct writing of copper from copper formate precursor films has been developed. Unlike previously reported laser processes involving the decomposition of solid precursor films, this process does not require any postprocessing (e.g., plating) to enhance the deposits in thickness or conductivity. Precursor crystallization has been completely eliminated by introduction of glycerol into the precursor. The lateral resolution has been improved by replacing the commonly used CW laser with a 100-kHz Q-switched laser of much lower average power, allowing for deposition of copper lines less than 20- mu m wide. Thousands of individual conductors per substrate with thicknesses of 4-6 mu m and resistivities below 10 mu Omega -cm are routinely obtained with this method.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An analysis for the introduction of glycerol in a heart

An analysis for the introduction of glycerol in a heart

Washing erythrocytes in a centrifugal system with particular reference to glycerolized cells.

True countercurrent washing is difficult to achieve with unaggregated erythrocytes because of their small size and tendency to engage in bulk flow. Continuous‐flow centrifugal washing of cells suspended in isotonic saline is extremely efficient, permitting a reduction in the concentration of extracellular contaminant by a factor of 100 in less than five minutes with a wash solution volume less than twice the volume of the cell solution. The introduction of glycerol into a cell suspension decreases sedimentation rates and imposes several obstacles to continuous‐flow wash. The efficiency of centrifugal wash procedures for fully glycerolized cells is poor and a preliminary reduction in glycerol concentration by some other method is necessary before continuous‐flow wash can be used effectively. A preliminary dilution with a hypertonic sodium chloride wash improves sedimentation characteristics, but excessive packing of the crenated cells results in washing hemolysis. Some further dilution with isotonic saline prevents this and permits completion of the wash on a continuous‐flow centrifugal basis.

Introduction of Glycerol into Flake Aggregates by Vapour Pressure

Introduction of Glycerol into Flake Aggregates by Vapour Pressure