The temperature dependence of the molar heat capacity of porous vinylbenzyl chloride and divinylbenzene copolymer was studied using a precise automated adiabatic calorimeter and a differential scanning calorimeter in the range 6.24–496.5 K. On the basis of the obtained experimental data, three anomalous changes in heat capacity were detected in the above temperature range, caused by the glass transition of the copolymer (T = 367–388 K and T = 420–460 K) and desorption of the heat-conducting gas – helium (T = 6–9 K). The standard thermodynamic functions C_p^o (T), H^o(T)-H^o(0) , S^o(T)-S^o(0) , G^o(T)-G^o(0) in the range from T → 0 to 490 K, as well as the standard entropy of copolymer formation at T = 298.15 K were calculated from the obtained experimental data.

In this work the heat capacity C op,m = f ( T ) of the garnet-structured Na3Cr2(AsO4)3 3 Cr 2 (AsO 4 ) 3 was first investigated. Measurements were performed in the range of T = (5 and 323) K using a precise adiabatic vacuum calorimeter. The phase purity and composition homogeneity were verified by X-ray diffraction analysis with Rietveld method calculations and X-ray microanalysis. The C op,m , Delta T 0 H 0 m , Delta T0 S 0m and Delta T 0 G 0 m have been calculated using experimental data from T -> 0 to 323 K.

Precision adiabatic vacuum and high-precision differential scanning calorimetry (DSC) are used to study the temperature dependence of the heat capacity of betamethasone dipropionate in the range of 6–520 K for the first time. A phase transition of betamethasone dipropionate (melting) is detected in the above range of temperatures, and its thermodynamic characteristics are calculated. The low temperature heat capacity (20 ≤ T ≤ 50 K) is processed on the basis of a multifractal model, and the chain-layered topology of the structure is established. The thermal stability of the steroid hormone is studied via thermogravimetric analysis (TGA). It is found that the temperature at which the substance begins to decompose is 480 K. The experimental data are used to calculate standard thermodynamic functions in the region T → 0 to 480 K for the crystalline and liquid states of betamethasone dipropionate.

Formulas of phosphates K5/3MgE4/3(PO4)3 (E = Ti, Zr) have been designed from crystal-chemical positions, their synthesis has been carried out, thermal stability, thermal expansion and temperature dependence of heat capacity have been studied. The samples obtained were characterized by XRD, IR, TG-DSC, scanning electron microscopy and microprobe electron analysis. The crystal structure and unit cell parameters were obtained by powder X-ray diffraction with Rietveld calculations (langbeinite structure, sp. gr. P213). The isobaric heat capacities of K5/3MgZr4/3(PO4)3 phosphate were measured from T = 5 to 365 K by adiabatic vacuum calorimetry and the thermodynamic functions were calculated from the experimental data. An anomaly in the heat capacity curve was observed at T below 6 K, the nature of which was explained by the magnetic disorder-order phase transition. In the temperature range of 298–1473 K, no effects were observed in the TG-DSC curves, indicating the thermodynamic stability of the samples. A minimum thermal expansion value of 2.0‧10−6 K−1 was found for K5/3MgTi4/3(PO4)3 in the 173–473 K range. Due to the structural stability of langbeinite, wide range of ionic substitutions, thermal, radiation and chemical resistance to leaching under time-varying conditions, phosphates with such structure can be considered as environmentally safe ceramic matrices for nuclear waste immobilization.

In this work the heat capacity Cp,mo=f(T) of the garnet-structured Na3Cr2(AsO4)3 was first investigated. Measurements were performed in the range of T = (5 and 323) K using a precise adiabatic vacuum calorimeter. The phase purity and composition homogeneity were verified by X-ray diffraction analysis with Rietveld method calculations and X-ray microanalysis. The Cp,mo,Δ0THm0,Δ0TSm0andΔ0TGm0 have been calculated using experimental data from T→0 to 323 K.

Quantum dots are semiconductor crystals with unique optical properties. Analytical applications are made possible due to the stability of the crystal, the ability to vary the fluorescence wavelength, and the capacity for non-radiative energy transfer. They are influenced by the composition, structure and coating of QDs.

New amphiphilic block copolymers on based benzylmethacrylates or 2,3,4,5,6-pentafluorobenzyl methacrylate and N-isopropylacrylamide with high yields (89–94

BACKGROUND:A key restriction of label-free surface-enhanced Raman spectroscopy (SERS) in analysis of objects with complex composition (including with several target analytes) is the competition of mixture components for interaction with SERS-active surface. This leads to poor selectivity of the analysis of such mixtures (e.g., body fluids) and the need to use advanced sample pretreatment procedures such as HPLC or TLC. Therefore, this work aims to develop a set of simple and fast pretreatment steps (dilution, pH correction, etc.) to increase the sorption of the target analyte, reduce the sorption of admixtures, and prevent suppression of the target analyte SERS signal. RESULTS:We have developed label-free SERS assay suitable for the determination of three analytes (methotrexate, cephalosporin antibiotic, and creatinine) in one real urine sample as a model matrix with complex and deviating composition. The choice of drugs is justified by the need to monitor their concentration in urine during joint drug treatment of cancer patients with concomitant bacterial infection, while monitoring creatinine concentration helps to evaluate kidney function of the patients. Additionally, three cephalosporin representatives were used in the study to maximize versatility of the assay. As a results, the optimized pretreatment steps enable to eliminate the negative influence of excess of interferences (including other analytes) and achieve precise (≤12 % RSD) and accurate (88-111 % recovery) determination of several analytes in the therapeutically relevant ranges: 300-3000 μg mL-1 for creatinine, 20-200 μg mL-1 for methotrexate and cephalosporins. SIGNIFICANCE:Therefore, in addition to reporting a new SERS assay for the analysis of body fluids, this study clearly demonstrates the importance of taking into account competitive adsorption processes on the SERS substrate surface. We suggest making this practice mandatory when developing any label-free SERS assay because it enables to maximize the selectivity and accuracy of the analysis as well as to simplify the analysis procedure.

Analysis of real objects based on surface-enhanced Raman spectroscopy (SERS) often utilizes new SERS substrates and/or complex analysis procedures, and they are optimized for only the determination of a single analyte. Moreover, analysis simplicity and selectivity are often sacrificed for maximum (sometimes unnecessary) sensitivity. Consequently, this trend limits the versatility of SERS analysis and complicates its practical implementation. Thus, we have developed a universal, but simple SERS assay suitable for the determination of structurally related antibiotics (five representatives of the sulfanilamide class) in complex objects (human urine and saliva). The assay involves only mixing of acidified analyzed solution with co-activating agent (polydiallyldimethylammonium chloride - PDDA) and SERS substrate (standard colloidal silver nanoparticles). Acidification promotes the generation of SERS spectra with maximum similarity and intensity, which is explained by the favorable enhancement of the protonated sulfanilamide moiety (a structurally similar part of the studied antibiotics) as a result of its strong electrostatic interaction with the SERS-active surface. Meanwhile, the addition of PDDA improves analysis selectivity by reducing background signal from body fluids, enabling to simplify sample pretreatment (dilution for urine; mucin removal and dilution for saliva). Therefore, the assay allows for rapid (<= 10 min), precise, and accurate class-specific determination of sulfanilamides within concentration ranges suitable for non-invasive therapeutic drug monitoring in urine (40-600 mu M) and saliva (10-30 mu M). We also believe that thorough investigation of structurally related analytes and accompanying effects (e.g., high spectral similarity) is a promising direction to improve the understanding of SERS in general and expand its capabilities as an analytical tool.

The temperature dependences of the heat capacities of carbosilane dendrimers of the third and sixth generations with ethyleneoxide terminal groups are examined for the first time by means of precision adiabatic vacuum calorimetry at temperatures between 6.5 and 350 K. In this temperature range, physical transformations are observed and their standard thermodynamic characteristics are determined and discussed. The standard thermodynamic functions are calculated per nominal mole of a chosen unit using the obtained experimental data: C° p (T), H°(T) - H°(0), S°(T) - S°(0), and G°(T) - H°(0) in the interval T → 0 to 350 K, and the standard entropies of formation at T = 298.15 K. The low-temperature (T ≤ 50 K) heat capacity is analyzed using the Debye theory of specific heat and a multifractal model. The values of fractal dimension D are also determined, and conclusions on the investigated structures’ topology are drawn. The corresponding thermodynamic properties of the studied dendrimers are compared as well.

The molar heat capacity of 1,4-bis(3-methylimidazolium-1-yl)butane bis(trifluoromethylsulfonyl)imide dicationic ionic compound ([C4(MIm)2][NTf2]2) has been studied over the temperature range from 6 to 350 K by adiabatic calorimetry. In the above temperature interval, this compound has been found to form crystal, liquid, and supercooled liquid. For [C4(MIm)2][NTf2]2, the temperature of fusion T°fus = (337.88 ± 0.01) K has been determined by the fractional melting experiments, the enthalpy of fusion ΔfusH° = (52.79 ± 0.28) kJ mol−1 has been measured using the calorimetric method of continuous energy input, and the entropy of fusion ΔfusS° = (156.2 ± 1.7) J K−1 mol−1 has also been evaluated. The standard thermodynamic functions of the studied dicationic ionic compound, namely, the heat capacity Cp°(T), the enthalpy [H°(T) − H°(0)], the entropy S°(T) and the Gibbs free energy [G°(T) − H°(0)] have been calculated on the basis of the experimental data for the temperature range up to 350 K. The results have been discussed and compared with those available in the literature and in the NIST Ionic Liquids Database (ILThermo) for monocationic ionic compounds.

Surface enhanced Raman spectroscopy (SERS) is meeting the requirements in biomedical science being a highly sensitive and specific analytical tool.

Amphoteric polymers based on chitosan, acrylamide and sodium acrylate with different content of the latter were synthesized using the radical copolymerization method in solution in the presence of 1.4 × 10–3 mol/L ammonium persulfate in an inert medium at 333 K. Terpolymers’ molecular weight characteristics, their structure, as well as the ability to flocculation and sorption of hydrogels based on them were investigated. The copolymers’ formation was proved by extraction, IR-spectroscopy, conductometric titration, differential scanning calorimetry, and statistical light scattering. The chitosan modification with acrylamide leads to an increasing of its molecular weight up to 5.2 × 105. The subsequent introduction of the sodium acrylate into the copolymer allows obtaining terpolymers with molecular weight from 7.7 × 105 to 18.5 × 105 depending on the amount of the introduced monomer. The maximum content of acid groups in the graft copolymers reached 26.8 wt

Gadolinium-strontium phosphate with the eulytite structure was synthesized. Its structure refinement was performed applying the Rietveld method. The isobaric heat capacities of phosphate Sr3Gd(PO4)(3) have been measured from T = 6 to 800 K by adiabatic vacuum and differential scanning calorimetry. The standard thermodynamic functions C-p,m(0), [H-m(o)(T) - H-m(o)(6)], [S-m(o)(T) - S-m(o)(6)], and Phi(o)(m) in the range of T -> 6-800 K were calculated from the experimental data. Thermal expansion of phosphate using X-ray diffraction was studied in the temperature range 298-473 K. The linear thermal expansion coefficient was alpha = 12.1 x 10(-6) K-1.

It was for the first time that the heat capacity of β-pyrochlore complex oxides RbTe1.5W0.5O6 and Rb0.95Nb1.375Mo0.625O5.79 was investigated by adiabatic vacuum calorimetry and differential scanning calorimetry in the temperature range T = (6–640) K. The obtained experimental data were used to calculate the standard thermodynamic functions: heat capacity C_p^o , enthalpy [H°(T)−H°(0)], absolute entropy [S°(T)], and Gibbs free energy [G°(T)−H°(0)] for the range from T → 0 to 640 K. The low-temperature (T < 50 K) heat capacity trends were analyzed in terms of the multifractal model, and a chain–layered structure topology of the studied compounds was established.

Thermodynamic properties of (CaO)0.501(Al2O3)0.098(SiO2)0.401 (Ca40.10) glass are studied using two techniques: low-temperature vacuum adiabatic calorimetry and high-temperature drop solution calorimetry. The enthalpy of formation from oxides (−17.6 ± 2.6 kJ/mol) is determined for the first time. Heat capacity is shown to grow monotonically with temperature in the interval of 8 to 357 K. No phase transitions are revealed in this region of temperatures. Results from measuring heat capacity are approximated using the semi-empirical Planck–Einstein model. The possibility of using incremental scheme to estimate the heat capacity of ternary glasses formed by calcium, aluminium, and silicon oxides is confirmed.

Surface-enhanced Raman spectroscopy (SERS) is a powerful biosensing technique that combines molecular fingerprint specificity with high sensitivity, detecting trace amounts using plasmonic-based metallic nanostructured sensor platforms. SERS strategies include direct and indirect, as well as targeted and untargeted methods, depending on sample complexity and target analyte affinity. The development of SERS platforms, such as microfluidic environments, lab-on-a-fiber approaches, and paper-based immunoassays, aims at creating portable systems for point-of-care use in clinical and non-lab settings. Combining SERS with other techniques enhances measurement conditions, miniaturization, and sensitivity. This review summarizes key analytical applications of SERS in biosensing, including medicine, clinical diagnostics, environmental monitoring, food quality assessment, and biological studies.

Hydrogermylation is used to obtain new compound, tris(pentafluorophenyl)-2-pyridylethylgermane. The structure is confirmed via IR and NMR spectroscopy, and X-ray diffraction analysis. Thermophysical properties are determined using DSC and TGA. Two polymorphic modifications (triclinic and monoclinic) of tris(pentafluorophenyl)-2-pyridylethylgermane are discovered. It is shown that the triclinic modification is more energetically advantageous than monoclinic modification. The topology of the electron density of tris(pentafluorophenyl)-2-pyridylethylgermane is studied theoretically and experimentally. an intramolecular Ge(1)-N(1) contact is discovered and its energy is estimated from the topology of electron density.

Впервые методом калориметрии сгорания определена энергия сгорания кристаллического 2,6-ди- трет- бутил- пара -бензохинона при температуре Т = 298.15 K. По экспериментальным данным рассчитаны стандартные энтальпии сгорания и образования исследуемого соединения. Полученные термохимические характеристики 2,6-ди- трет- бутил- пара -бензохинона были сопоставлены с литературными данными для других производных бензохинона, изученных ранее.

Получены новые стекла системы TeO 2 –Na 6 P 6 O 18 . Методом дифференциальной сканирующей калориметрии изучено термическое поведение стекол в области 25–580°C, исследованы температурные зависимости теплоемкости в интервале 25–400°C. Определены характеристики расстеклования и стеклообразного состояния, подобраны аналитические зависимости температур стеклования и термодинамических характеристик стекол от их состава при t = 80°C. Проведен сравнительный анализ полученных зависимостей с аналогичными для изученных ранее бинарных систем на основе TeO 2 . Исследована оптическая прозрачность стекол в УФ-, видимой и ИК-областях спектра. Показана возможность введения в стекла оксидов редкоземельных элементов. Для стекла состава 0.89TeO 2 –0.08Na 6 P 6 O 18 –0.03Nd 2 O 3 изучены люминесцентные характеристики.