Raman Spectroscopic Characteristics of Zeolite Group Minerals

In this work, Raman spectroscopic experiments are conducted on zeolites, including a total of 33 varieties and seven groups with different secondary structural frameworks, for which characteristic vibration modes are studied. Most of the zeolites show prominent Raman peaks in the spectral range between 200–1200 cm−1. Different groups of zeolites can be recognized by differences in the wavenumbers of the T-O-T (T = Si and Al, O = oxygen) modes in the range 379–538 cm−1, the M-O (M = metal,) modes in the range 250–360 cm−1 and the T-O bending modes in the range 530–575 cm−1. All zeolites show characteristic Raman peaks in the range 379–529 cm−1, except for natrolite group (fibrous) zeolites, which are characterized by T-O-T modes in the 433–447 cm−1 range and T-O bending modes in the 528–538 cm−1 range. The analcime group (with singly connected four-ring chains) zeolites show T-O-T modes in the 379–392 cm−1 and 475–497 cm−1 ranges. The gismondine group (with doubly connected four-ring chains) zeolites have T-O-T modes in the 391–432 cm−1 and 463–497 cm−1 ranges. The chabazite group (with a six-cyclic ring) zeolites are characterized by M-O modes in the 320–340 cm−1 range and T-O-T modes in the 477–509 cm−1 range. The Raman modes of mordenite group zeolites (397–410 cm−1 and 470–529 cm−1) overlap with those of heulandite group zeolites (402–416 cm−1 and 480–500 cm−1). Moreover, the mordenite group has a characteristic peak in the 502–529 cm−1 range, and an additional peak in the 800–965 cm−1 range. Another recognizable peak for the heulandite group is in the 612–620 cm−1 range. The unknown zeolites (cowlesite) have unique characteristic peaks at 534 cm−1, which can aid in the verification of their identity.

Influence of synthesis parameters on mechanical properties of nanocomposite PMMA-MXene

In this paper, the influence of solvents and reinforcement processing methods on the mechanical properties of nanocomposite poly-(methyl methacrylate) PMMA-Ti3C2Tx MXene was investigated. A weight fraction of reinforcement was 1% and two types of solvents were used for sample preparation: dimethylformamide (DMF) and acetone (Ac). Deionized water and DMF were used to delaminate the MXene. An additional peak at 1675 cm-1 was observed on the FTIR spectra of the obtained samples, which indicates that some amount of DMF remained in the material after drying. The results of microindentation show that samples where MXene was delaminated in deionized water and PMMA dissolved in acetone had a 74.46% higher reduced modulus of elasticity, which is supported by SEM images where better dispersion of MXenes is observed.

ENGAGEMENT OF BIOMASS CHP FOR POWER GRID BALANCING IN UKRAINE

Work is aimed on determination of possibilities of biomass CHP engagement for power grid balancing in Ukraine. The principal technical possibility for biomass CHP (existing and greenfield construction) engagement for balancing is considered and confirmed. The technical concept for biomass CHP switch from baseload regime into balancing regime has been developed. For effective operation on the peak load market, the existing biomass CHP shall be additionally equipped with boiler and turbine of higher capacity to provide possibility of additional peak electricity supply to the grid. As one of the possible decisions for stimulation of biomass CHP/TPP operation in balancing regime, the mechanism for provision of incentive tariff for peak hours (morning and evening peaks) has been proposed. According to the calculation, the respective incentive tariff to stimulate biomass CHP investor for balancing operation shall be 0.273-0.279 EUR/kWh depending on the electricity supply scheme and for the ratio between balancing and baseload capacities as 6/3. It was demonstrated, that for more large-scale projects and for smaller ratio between balancing and baseload capacities, the respective tariff will be lower.

Comparison of neutral and charged polyelectrolyte bottlebrush polymers in dilute salt-free conditions

ABSTRACTWe investigate the structure of neutral and charged bottlebrush polymers in salt-free solutions at different polymer concentrations. In particular, we use molecular dynamics simulations by utilizing a coarse-grained bead-spring model that includes an explicit solvent and complementary experiments made by small angle neutron scattering (SANS). We find that the charged groups along the side chains exert significant repulsive forces, resulting in polymer swelling and backbone stretching. In addition to the primary polyelectrolyte peak, we find that bottlebrush polymers exhibit an additional peak in the form and static structure factors, a feature that is absent in neutral polymers. We show that this additional peak describes the intra-molecular correlations between the charged side chains.

Evaluation of the Colorimetric Performance of Unmodified Citrate-Stabilized Silver Nanoparticles for Copper (II) Sensing in Water

In this study, the colorimetric performance of unmodified citrate-stabilized silver nanoparticles (cit-AgNP) for Cu2+ detection was investigated. Cit-AgNP was successfully synthesized using the modified Creighton method with sodium borohydride as reducing agent and trisodium citrate as stabilizing agent. The resulting nanoparticle was yellow in color, characteristic of AgNP. The absorbance peak was determined at 400 nm using UV Vis analysis while for morphology, the particles were spherical in shape with an average diameter of 11 nm determined by TEM analysis. In the presence of increasing Cu2+ concentration, the yellow cit-AgNP turned orange and showed decreasing absorbance at 400 nm with simultaneous emergence of additional peak at 450 nm. These changes were attributed to the nanoparticle aggregation confirmed by TEM analysis. A calibration curve generated showed that the absorbance ratio 450/400 nm is directly proportional to Cu2+ concentration from 0 to 40x10-4 M with good linear fit at R2 = 0.9749. The detection and quantification limits were determined to be 6.59x10-4 M and 21.97x10-4 M, respectively. Overall, the study demonstrated the potential of the assay for Cu2+ sensing application.

Investigation of the Creep Resistance of a Spray-Compacted Si-Particle Reinforced Al-Based MMC (Dispal® S270)

MMCs exhibit a high potential in modern structures due to many positive attributes. One of these attributes is a heightened creep resistance compared to conventional single or multi-phase alloys. The following paper focuses on the creep resistance of a spray-compacted Al-based alloy (DISPAL® S270). This alloy, designed for high temperature applications like turbochargers, cylinder bore liners or pistons can be subjected to temperatures up to 450°C, which is considerably higher compared to unreinforced Al-alloys. DISPAL® S270 microscopically consists of Si-particles with round shapes in an Al-rich α solid solution, which is additionally reinforced by complex precipitates, including Al9FeNi and Al3Ti, among others. The particle sizes and ratios differ with the heat treatment. The same applies to the precipitates in the matrix. The investigated heat treatments are F (after extrusion) and T6 (additional peak aged). The alloy is tested at 250°C using different loads at constant force with stress values between 125 and 200 MPa. The measured minimal creep rates are in the range of min. = 10-5-10-8 1/s. In comparison to conventional single or multiple phase alloys MMCs reveal some advantages, since the modified threshold stresses and direct strengthening often reduce the minimum creep rate. The stress exponent of the MMCs has higher values ​​compared to aluminum alloys, as known from previous MMC studies. The specimens are analyzed with LM, SEM, EDS and XRD. It could be shown that an additional heat treatment (peak aged T6) enhances the creep properties by introducing very fine precipitates containing the Mg5Si6 phase.

Enhanced Diffusion in a Model of Molecular Motors with Potential Switching

Diffusion enhancement is a phenomenon in which the diffusion coefficient of a system is increased by an external force and it becomes larger than that of the force-free diffusion in thermal equilibrium. It is known that this phenomenon occurs for a Brownian particle in a periodic potential under a constant external force. Recently, it was found that diffusion enhancement also occurred in a biological molecular motor, whose moving part could move itself by switching the potentials generated by the other parts. It was shown that the diffusion coefficient exhibited peaks as a function of a constant external force. Here, we report the occurrence of an additional peak and investigate the condition governing its appearance.

Double magnetocaloric peak feature observed in quaternary Ni-Mn-In based Heusler alloys

We present the results of the studies of magnetic and magnetocaloric (MCE) properties of quaternary Heusler alloys Ni48.5Mn35In15Co1.5 and Ni50Mn35In13.5Al1.5 in temperature range between 80 K and 400 K. While doping initial ternary Ni-Mn-In alloy with 1.5 at.% Al does not change TCA as well as MS, doping with 1.5 at.% Co significantly increases both TCA and MS. The direct magnetocaloric measurements around martensitic transition and austenite Curie temperature reveal the competition between the contributions of different signs. The latter is related to the vicinity of transition temperatures of austenite and martensite, resulting in mixed state, where both phases undergo magnetic order-disorder transformation in the same temperature region. Additionally temperature dependencies of adiabatic temperature change ΔTad and magnetic entropy ΔSM of the system exhibit additional peak feature which we attribute to intermartensitic transition occurring in these alloys.

Низко- и инфранизкочастотная дисперсия диэлектрической проницаемости в матричном композите нанокристаллическая целлюлоза-триглицинсульфат

The dispersion of dielectric permittivity in nanocrystalline cellulose–triglycine sulfate composites is studied in the range of frequencies from 10^–3 to 10^6 Hz, at temperatures varying from room temperature to the temperature of phase transition in this composite (54°C), in weak electric fields (1 V cm^–1). Two behaviors for the dielectric dispersion are identified in the studied frequency range: at ultralow frequencies (10^–3–10 Hz), the dispersion is due to Maxwell–Wagner polarization, while at higher frequencies (10–10^6 Hz), the dispersion is due to the movement of domain walls in the embedded triglycine sulfate crystallites. An additional peak in the temperature-dependent profiles of dielectric permittivity is detected at lower temperatures in freshly prepared samples of the considered composite; we associate it with the presence of residual water in these samples.

Identification of haemoglobin New York by haemoglobin A1c measurement using the Sebia Capillarys 2 Flex Piercing system

Haemoglobinopathies may interfere with the haemoglobin A1c (HbA1c) measurement, leading to incorrect diagnosis and inappropriate treatment. It is essential that HbA1c assays are capable of identifying haemoglobinopathies. We report two cases of haemoglobin New York (HbNY) discovered through HbA1c analysis using capillary electrophoresis (Capillarys 2 Flex Piercing [C2FP], Sebia). We used these samples to evaluate the ability of three other HbA1c assays to identify this variant: ion-exchange high-performance liquid chromatography (Variant II Turbo [VII-T], Bio-Rad); boronate affinity high-performance liquid chromatography (Ultra2, Trinity Biotech) and immunoassay (Cobas c501 Tina-quant Generation 3, Roche Diagnostics). Each method was used for HbA1c assay of in samples from two cases of heterozygous haemoglobinopathy: β0-thalassemia/HbNY (Case 1) and HbA/NY (Case 2). Only the C2FP system detected HbNY (an additional peak appeared between HbA1c and HbA0). Clinical laboratories should be aware of the limitations of their HbA1c assay methods especially in geographic areas, where haemoglobinopathy prevalence is high.