Viscous Liquid State Research Articles

Hydrophobic eutectic and hydrophilic melts of gabapentin-lactam & citric acid mixtures; green promoters for selective synthesis of xanthenes/ benzo[b]pyrans and dihydropyrroles

Gabapentin-lactam and citric acid form a glassy hydrophobic deep eutectic mixture. Certain non-eutectic molar ratios of the two components are also low-melting mixtures and slight differences can be discerned in their differential calorimetric curves. Yet, they impose different selective promotions on the reaction of malononitrile, arylaldehyde, and dimedone. Interestingly, the reaction mixture selectively gives tetrahydrobenzo[b]pyran-2H-ones or 1,8-dioxo-octahydroxanthenes depending on being carried out in the melted 2/1 or 1/2 molar mixtures of gabapentin-lactam/citric acid. An excellent promoting activity was also observed for the melt of gabapentin-lactam and citric acid mixture in 1/1 molar ratio. This melt proved to be an efficient promoter for synthesis of 4‑hydroxy-2,5-dihydropyrrol-5-ones from the domino reaction of an arylaldehyde, an aniline derivative, water, and an acetylenic ester. No additional organic solvents are required to perform the reactions and the bio-compatible melts can be reused several times after easy separation from the products. The eutectic and the non-eutectic melts preserve their viscous liquid state even upon a long-term storage at ambient temperature.

Temperature dependence of the viscoelastic properties of a natural gastropod mucus by Brillouin light scattering spectroscopy.

Brillouin spectroscopy was used to probe the viscoelastic properties of a natural gastropod mucus at GHz frequencies over the range -11 °C ≤ T ≤ 52 °C. Anomalies in the temperature dependence of mucus longitudinal acoustic mode peak parameters and associated viscoelastic properties at T = -2.5 °C, together with the appearance of a peak due to ice at this temperature, suggest that the mucus undergoes a phase transition from a viscous liquid state to one in which liquid mucus and solid ice phases coexist. Failure of this transition to proceed to completion even at -11 °C is attributed to glycoprotein-water interaction. The temperature dependence of the viscoelastic properties and the phase behaviour suggest that water molecules bind to glycoprotein at a temperature above the onset of freezing and that the reduced ability of this bound water to take on a configuration that facilitates freezing is responsible for the observed freezing point depression and gradual nature of the liquid-solid transition.

Effect of sodium lauryl sulfate-mediated gelation on the suppressed dissolution of crystalline lurasidone hydrochloride and a strategy to mitigate the gelation

In dissolution test, the surfactant sodium lauryl sulfate (SLS) is usually added to increase the dissolution of insoluble drugs and achieve the sink condition. However, the current study found that 0.1 % SLS would significantly decrease the dissolution of crystalline lurasidone hydrochloride (LH, a BCS Ⅱ drug). The aim of this study was to clarify the mechanism of this unexpected phenomenon and explore a strategy for mitigating the negative effect of SLS on the dissolution of LH. Sample characterizations (such as PLM, DSC, PXRD, IR and NMR) confirmed that the insoluble single-phase amorphous LH-SLS complex (with a single Tg at 35.2 °C) formed during dissolution in 0.1 % SLS aqueous solution via electrostatic interaction, tetrel bond interaction, and hydrophobic effect. Due to the plasticization effect of water, the transition of amorphous LH-SLS from its glassy state to viscous supercooled liquid state led to the gel formation, and suppressd the dissolution of LH. Meanwhile, the solubility curve of LH in SLS aqueous solution at various concentrations exhibited an unusual V-shaped feature, with the CMC value of SLS serving as the inflection point, since the gel degree was attenuated due to the micelle solubilization of SLS. Additionally, an innovative strategy was developed to alleviate the inhibiting effect of SLS on LH dissolution based on the potential competitive interactions. This study not only enriches the internal mechanism of surfactant-inhibited drug dissolution but also informs an effective strategy to mitigate the gelation.

Q-dependent collective relaxation dynamics of glass-forming liquid Ca0.4K0.6(NO3)1.4 investigated by wide-angle neutron spin-echo

The relaxation behavior of glass formers exhibits spatial heterogeneity and dramatically changes upon cooling towards the glass transition. However, the underlying mechanisms of the dynamics at different microscopic length scales are not fully understood. Employing the recently developed wide-angle neutron spin-echo spectroscopy technique, we measured the Q-dependent coherent intermediate scattering function of a prototypical ionic glass former Ca0.4K0.6(NO3)1.4, in the highly viscous liquid state. In contrast to the structure modulated dynamics for Q < 2.4 Å−1, i.e., at and below the structure factor main peak, for Q > 2.4 Å−1, beyond the first minimum above the structure factor main peak, the stretching exponent exhibits no temperature dependence and concomitantly the relaxation time shows smaller deviations from Arrhenius behavior. This finding indicates a change in the dominant relaxation mechanisms around a characteristic length of 2π/(2.4 Å−1) ≈ 2.6 Å, below which the relaxation process exhibits a temperature independent distribution and more Arrhenius-like behavior.

The intimate relationship between structural relaxation and the energy landscape of monatomic liquid metals

The characteristic property of a liquid, discriminating it from a solid, is its fluidity, which can be expressed by a velocity field. The reaction of the velocity field on forces is enshrined in the transport parameter viscosity. In contrast, a solid reacts to forces elastically through a displacement field, the particles are trapped in their potential minimum. The flow in a liquid needs enough thermal energy to overcome the changing potential barriers, which is supported through a continuous rearrangement of surrounding particles. Cooling a liquid will decrease the fluidity of a particle and the mobility of the neighbouring particles, resulting in an increase of the viscosity until the system comes to an arrest. This process with a concomitant slowing down of collective particle rearrangements might already start deep inside the liquid state. The idea of the potential energy landscape provides an attractive picture for these dramatic changes. However, despite the appealing idea there is a scarcity of quantitative assessments, in particular, when it comes to experimental studies. Here we present results on a monatomic liquid metal through a combination of ab initio molecular dynamics, neutron spectroscopy and inelastic x-ray scattering. We investigated the collective dynamics of liquid aluminium to reveal the changes in dynamics when the high temperature liquid is cooled towards solidification. The results demonstrate the main signatures of the energy landscape picture, a reduction in the internal atomic structural energy, a transition to a stretched relaxation process and a deviation from the high-temperature Arrhenius behavior of the relaxation time. All changes occur in the same temperature range at about 1.4 cdot T_{melting}, which can be regarded as the temperature when the liquid aluminium enters the landscape influenced phase and enters a more viscous liquid state towards solidification. The similarity in dynamics with other monatomic liquid metals suggests a universal dynamic crossover above the melting point.

The Influence of Freezing on the Course of Carbonization and Pyrolysis of a Bituminous High-Volatile Coal

The course of thermal behavior of a fresh bituminous high-volatile coal during carbonization and pyrolysis was compared to that of this coal thawed after storage. The research was carried out using the following techniques: X-raying, thermogravimetry/Fourier transform-infrared spectroscopy (TG/FT-IR), extraction, Diffuse Reflectance Infrared Fourier Transform Spectroscopes (DRIFT), Attenuated Total Reflectance (ATR), and SEM. The increase in range of the viscous-liquid state and a decrease in temperature of its appearance were stated along with the formation of a more compact residue at the re-solidification stagtablee for the thawed coal during its carbonization. There is a fourfold reduction in the charge volume. The leakage of bitumen that contains 87 At % of C atoms from swollen grains and a fourfold increase in the yield of the material extracted from these grains are the proof of a greater plasticization of thawed coal. During the pyrolysis of thawed coal, the yield in volatile products of pyrolysis increases, and the composition of these products changes. The contribution ratio of saturated and unsaturated hydrocarbons, CO2, alcohols, and phenols decreases in the composition of volatile products of thawed coal. It is suggested that the use of freezing during the storage of a freshly mined coal that has a poorer caking ability can improve its plasticization during carbonization.

Suppression of Orientational Correlations in the Viscous-Liquid State of Hyperquenched Pressure-Densified Glycerol.

Glycerol pressurized to 2kbar and hyperquenched from the bulk liquid at rates of about -10 000 K/s, has been frozen to an extreme out-of-equilibrium state. As compared to conventionally cooled melts, the resulting material exhibits lower orientational correlations, enabling the observation of a secondary relaxation peak in the ambient-pressure dielectric response. The hyperquenching rather than the pressurizing part of the preparation protocol induces the observed structural changes. These vanish entirely only well above the glass transition temperature of the equilibrium liquid and are evidence for strong similarities between hyperquenched and vapor-deposited glass formers.

Proper Management of Planetary Hydrocarbon Resources

Much has been said about the planet's gas and oil resources and many assumptions and speculations have been made regarding their rapid depletion, but a report on the normal and judicious management of these important planetary resources for both energy and other various materials that are obtained today from them, such as composites, synthetic fibers for fabrics, plastics, rubber produced synthetically ... The paper wants to clearly establish how these important planetary resources are produced and obtained, but also the possibility of extension their lives in symbiosis with the greening of the planet through the rational exploitation and use of these resources. Even if new oil and gas deposits are found from time to time, this fact cannot justify the almost continuous operation at large capacities of many of the old processed reserves, which have long been declared on extinct. Something is going on with these old oil deposits. They are in a continually rebuild or bring other deposits from somewhere in the depths of the earth from a probably a huge and deep reserve. The universe we live in is designed in such a way that it abounds in hydrogen, carbon, or combined gases, i.e., hydrocarbons, which under certain conditions pass into a viscous liquid state thus producing oil in large quantities. It is ridiculous to much longer support the theory that gases inside the earth were formed like oil otherwise from organic matter decomposed over time, possibly from dead dinosaurs that rotted and then turned into oil and gas. Hydrogen, the element whose nuclear fusion gives life to stars, including the Sun, is an extremely important wheel in the gear of the Universe and is also the most widespread element in the Universe, being the simplest of all chemical elements. As long as a reserve (bag) of oil or gas is not emptied very quickly, but is rationally exploited, it will recover normally by feeding from the internal source of the planet.

Proper Management of Planetary Hydrocarbon Resources

Much has been said about the planet's gas and oil resources and many assumptions and speculations have been made regarding their rapid depletion, but a report on the normal and judicious management of these important planetary resources for both energy and other various materials that are obtained today from them, such as composites, synthetic fibers for fabrics, plastics, rubber produced synthetically ... The paper wants to clearly establish how these important planetary resources are produced and obtained, but also the possibility of extension their lives in symbiosis with the greening of the planet through the rational exploitation and use of these resources. Even if new oil and gas deposits are found from time to time, this fact cannot justify the almost continuous operation at large capacities of many of the old processed reserves, which have long been declared on extinct. Something is going on with these old oil deposits. They are in a continually rebuild or bring other deposits from somewhere in the depths of the earth from a probably a huge and deep reserve. The universe we live in is designed in such a way that it abounds in hydrogen, carbon, or combined gases, i.e., hydrocarbons, which under certain conditions pass into a viscous liquid state thus producing oil in large quantities. It is ridiculous to much longer support the theory that gases inside the earth were formed like oil otherwise from organic matter decomposed over time, possibly from dead dinosaurs that rotted and then turned into oil and gas. Hydrogen, the element whose nuclear fusion gives life to stars, including the Sun, is an extremely important wheel in the gear of the Universe and is also the most widespread element in the Universe, being the simplest of all chemical elements. As long as a reserve (bag) of oil or gas is not emptied very quickly, but is rationally exploited, it will recover normally by feeding from the internal source of the planet.

Study the safeguarding performance of shear thickening gel by the mechanoluminescence method

This work reports the potential of a full-field, simple-setup and user-interactive method to study the safeguarding property of shear thickening gel (STG) by converting the invisible force/energy information to visible mechanoluminescence. Both the instantaneous intensity and force signals under impact prove the phase change of STG from viscous liquid state to rubbery state. The illumination images, presenting the energy maps, directly visualize the remarkably expanded impact area and phase change induced energy absorption, promoting the understanding of safeguarding mechanisms. The shear thickening property and viscoelastic deformation of STG significantly expand the impact area by almost 5 times, spreading and dissipating force/energy significantly. Moreover, the phase change accompanied by cracks is observed clearly, which is demonstrated to be beneficial to the energy absorption and contributes to the further enlargement of the impact area.

High temperature polymerization monitoring of an epoxy resin using ultrasound

In this study, the real time ultrasonic monitoring is investigated to quantify changes in physical and mechanical properties during the manufacture of composite structures. In this context, an experimental transmission was developed with the aim of characterizing a high temperature polymerization reaction and post-curing properties using an ultrasonic method. First, the monitoring of ultrasonic parameters of a thermosetting resin is carried out in a device reproducing the experimental conditions for manufacturing a composite material with a process known as RTM, that is to say an isothermal polymerization at T = 160°C. During this curing, the resin is changing from its initial viscous liquid state to its final viscous solid state. Between those states, a glassy transition stage is observed, during which the physical properties are strongly changing, i.e. an increase of the ultrasonic velocity up to its steady value and a transient increase of the ultrasonic attenuation. Second, the ultrasonic inspection of the thermosetting resin is performed during a heating and cooling process to study the temperature sensitivity after curing. This type of characterization leads to identifying the ultrasonic properties dependence before, during and after the glassy transition temperature Tg. Eventually, this study is composed of two complementary parts: the first is useful for the curing optimization, while the second one is fruitful for the post-processing characterization in a temperature range including the glassy transition temperature Tg.

Initially Synthesize [BMIM]CL and Apply to Extract Cellulose from Banana Rachis

Ionic liquors are organic salts with cations as organic and anionic inorganic bases, which exist in a viscous liquid state than organic solvents. The banana rachis is one of the agricultural products from banana trees. In Vietnam, bananas are high yield fruit trees. The amount of debris from banana trees is quite large but not yet utilized effectively to bring economic value. Banana rachis material is utilized and treated with 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid to initially investigate the ability of cellulose to separate the ionic liquid from the banana rachis. Banana rachis processing by [BMIM]Cl was investigated at 80oC, 100oC, 120oC and 140oC for 1 hour. Then analyze the reducing sugar and cellulose ingredients in the banana rachis samples. The results showed that the optimum temperature for banana rachis processing with [BMIM]Cl is 140°C for 1 hour. Ionic liquid in general and [BMIM]Cl in particular have great potential in the processing of fruit waste. Specifically, the content of cellulose in the banana kernel after treatment [BMIM]Cl was 73.04±7.49% compared to untreated sample was 26.25±1.43%, 3 times higher . The results of FTIR of banana rachis and recycled [BMIM]Cl showed that the lignin component in the banana rachis was quite soluble, resulting in a significant increase in cellulose content.

Real-time polymerization monitoring of a thermosetting resin around its glassy transition temperature

Real-time ultrasonic monitoring is investigated to quantify changes in physical and mechanical properties during the manufacture of composite structures. In this context, an experimental transmission was developed with the aim to characterize a high temperature polymerization reaction and post-curing properties using an ultrasonic method. First, the monitoring of ultrasonic parameters of a thermosetting resin is carried out in an isothermal polymerization process at 160°C. During this curing, the resin is changing from its initial viscous liquid state to its final viscous solid state. Between those states, a glassy transition stage is observed, during which the physical properties are strongly changing, i.e., an increase of the ultrasonic velocity up to its steady value and a transient increase of the ultrasonic attenuation. Second, the ultrasonic inspection of the thermosetting resin is performed during a heating and cooling process to study the temperature sensitivity after curing. This type of characterization lead to identify the ultrasonic properties dependence before, during, and after the glassy transition temperature Tg. This study is composed of two complementary parts: the first is useful for the curing optimization, while the second one is fruitful for the post-processing characterization in a temperature range including the glassy transition temperature.

Dynamic behavior of magnetically responsive shear-stiffening gel under high strain rate

The dynamic mechanical behavior of the magnetically responsive shear-stiffening gel (MSTG) was investigated by using a modified Split Hopkinson Pressure Bar (SHPB) system. It was found that the elastic modulus of the MSTG increased with increasing strain rate and magnetic field. The elastic modulus of the MSTG with 45 wt% carbonyl iron (CI) particles reached to 126.6 MPa at the strain rate of 7236 s−1, while it was merely 160 Pa without excitation. Under a 300 mT magnetic field, the elastic modulus also increased from 116.5 MPa (no magnetic field) to 255.5 MPa at the strain rate of 2900 s−1. The shear stiffening performance of the MSTG was stable and its maximum yield strain was 17.2%, which was very important for its practical application. The magnetically strengthened mechanisms of the high strain-rate-dependent mechanical properties were proposed. It was found that the enhanced shear-stiffening behavior was attributed to the phase transitions from viscous-liquid state to elastomeric state to glassy state under impact.

Effects of ionic solvent-free carbon nanotube nanofluid on the properties of polyurethane thermoplastic elastomer

A solvent-free ionic carbon nanotube (CNT) nanofluid with about 80 wt.% organic content was synthesized by oxidation of CNTs with mixed acid followed by a surface reaction with PEG-substituted tertiary amine. The CNT nanofluid and the pristine CNTs were introduced to polyurethane (PU) by melt-blending. The structures and properties of the nanofluid and the nanocomposites were investigated. The results show that the CNT nanofluid is in a viscous liquid state at room temperature and is stable and soluble in both aqueous and organic solvents. The CNT nanofluid distributes homogenously in the PU matrix. Due to the high content organic chains on the CNT surfaces, the breaking strength and elastic modulus of the nanocomposite decrease slightly but with about 100 % increase of breaking elongation and 50 % increase of toughness. Better dispersion of the nanofluid leads to more improvement of electrical conductivities of the composite. The solvent-free ionic nanofluid will be an excellent nanofiller in the nanocomposites.

A Study on the General Characteristics and Instrumental Analysis of Natural Omija Extract

Omija component was known to possess natural odor, taste, color, and various general characteristics. Omija extraction was extracted using ethanol as a solvent. Omija extract showed a red-purple color of some viscous liquid state. Some conclusions from natural Omija extract were obtained as follow. The result of antimicrobial experiment to add Omija extract, the number of microbial population showed negative reaction from 3 days after it cultivated. This phenomenon could confirm that Omija component affected to antimicrobial effect. The result of dyeing experiment to add Omija extract, fiber dyeing effect showed with some ivory color after dyed to cotton and silk. Also, this phenomenon could confirm that Omija component affected to natural dyeing effect from observated dye state with biological microscope(BM). The result of instrumental analysis, inorganic components of K(109.60ppm), Na(3.500ppm), Ca(1.205ppm), Mg(0.900ppm), Li(0.350ppm), Si(0.380ppm), Cu(0.250ppm), Fe(0.125ppm), Zn(0.090ppm), etcs from Omija were ascertained with ICP/OES, and organic components of benzene(10.808), borny lacetate(11.289), phenol(14.183), β-terpinene(15.840), α-terpinolene(17.616) etcs from Omija were ascertained with GC/MSD.

Flow box test for viscosity of soil in plastic and viscous liquid states

The transformation of soil from a plastic state to a viscous liquid state is primarily caused by a change in the water content of the soil mass. As the water content increases, the soil mass gradually starts to behave like a viscous liquid. In spite of viscosity being a key parameter to the initiation of mudflows, there have only been a few datasets on soil viscosity changes successfully measured continuously as the soil moves from a plastic state to a viscous liquid state. The aim of the current research is to design a new device to overcome this problem. Based on the trap door principle, formulated by Terzaghi (1943) and the Bingham model, a new device called the flow box was designed. The governing equation of the flow box was derived in this research in order to obtain the relationship between the initial viscosity and the liquidity index. In this study, the viscosities in both plastic and viscous liquid states were clearly defined by the flow box test. The expected decrease in initial viscosity was followed by an increase in the liquidity index, which corroborated with the test results. The initial viscosity readings were also validated with the results of other similar researches and the case study of the Maokong mudflow. Hence, the purpose of this research is to create a new device to successfully determine the viscosity levels as soil changes from the plastic state to the liquid state.

Two-dimensional magnetism and spin-size effect in theS = 1 triangularantiferromagnet NiGa2S4

The triangular antiferromagnet is one of the most fundamental systems of geometrically frustrated magnets.NiGa2S4 is alayered chalcogenide compound with an equilateral triangular lattice, and it is a prime candidate foran S = 1 triangular antiferromagnet. Here we focus on low temperature magnetism inNiGa2S4,where quasi-static spins develop a spin-wave-like mode without forming any long-range ordering.We have studied low temperature magnetism of both polycrystalline samples and single crystals ofNi1 − xAxGa2S4 (A = Mn, Fe, Co, and Zn). A scaling law with a single energy scale of the Weisstemperature is found as an impurity effect and a hydrostatic pressure effect,providing evidence that it is in-plane interactions in the two-dimensionalNiS2 plane that drive the critical slowing down to the viscous spin liquid state atT* = 8.5 K and the spin-wave-likeexcitations of NiGa2S4 that emerge below T ∼ 3 K. Furthermore, we find spin-size dependent impurity effects in the temperature dependence of the specific heat ofNi1 − xAxGa2S4. Even with a highimpurity content, Zn2 + (S = 0) andFe2 + (S = 2) substitutedsystems with weak XY anisotropy and integral spins retain the quadratic temperature dependence of the magnetic specific heatlike pure NiGa2S4. A spin glass-like phase, on the other hand, emerges at low temperatureswith the substitution of magnetic impurities with half-odd integer spins: IsingCo2 + (S = 3⁄2) and weak XY Mn2 + S = 5⁄2) spins. This indicates that an integer size of spins is important for stabilizing thetwo-dimensional spin-wave-like behavior, and the unconventional spin state ofNiGa2S4 at low temperatures is distinct from a canonical spin glass.

Towards a matrix mechanics framework for dynamic protein network

Protein–protein interaction networks are currently visualized by software generated interaction webs based upon static experimental data. Current state is limited to static, mostly non-compartmental network and non time resolved protein interactions. A satisfactory mathematical foundation for particle interactions within a viscous liquid state (situation within the cytoplasm) does not exist nor do current computer programs enable building dynamic interaction networks for time resolved interactions. Building mathematical foundation for intracellular protein interactions can be achieved in two increments (a) trigger and capture the dynamic molecular changes for a select subset of proteins using several model systems and high throughput time resolved proteomics and, (b) use this information to build the mathematical foundation and computational algorithm for a compartmentalized and dynamic protein interaction network. Such a foundation is expected to provide benefit in at least two spheres: (a) understanding physiology enabling explanation of phenomenon such as incomplete penetrance in genetic disorders and (b) enabling several fold increase in biopharmaceutical production using impure starting materials.

Reversibility and isotope effect of the calorimetric glass → liquid transition of low-density amorphous ice

We here report differential scanning calorimetry (DSC) scans recorded by repeatedly heating the H(2)O (D(2)O) low density amorph (LDA) which was made by isothermal decompression of very high-density amorphous ice (VHDA) at 140 K from 1.1 to 0.006 GPa. These DSC scans show a glass --> liquid transition endotherm with an onset temperature (T(g)) of approximately 137 (140) K at a heating rate of 30 K min(-1) accompanied by an increase in heat capacity of approximately 1.7 (1.5) J K(-1) mol(-1). We establish the reversibility of this effect by thermally cycling between its glassy state below 137 K and its highly viscous liquid state at 149 K. All calorimetric signatures, including H/D isotope effect, are highly similar to the signatures in hyperquenched glassy water (HGW). We argue that the observation of almost identical calorimetric traces for HGW and LDA implies that there is no need to reassign HGWs T(g) to higher temperatures provided that the viscous liquid state connected to both LDA and HGW behaves as an ideally "strong" liquid in the Angell classification. We furthermore show that LDA prepared by isothermal decompression of VHDA is more crystallization-resistant than LDA made from high-density amorphous ice (HDA) by isobaric warming. We suggest that the former route via VHDA removes "nanocrystalline remnants" in LDA which are still present in the latter after pressure-amorphization of hexagonal ice to HDA at 77 K.