Calorimetric Techniques Research Articles

Synthesis, Characterization of Polyhedral Oligomeric Silsesquioxane-Metronidazole Conjugate and Determination of Antibacterial, Biocompatible Properties

The aim of the present study is to synthesize the antibacterial and biocompatible novel polyhedral oligomeric silsesquioxane-metronidazole (POSS-MTZ) conjugate with condensation reaction from chloro-functional polyhedral oligomeric silsesquioxane and metronidazole. The prepared chloro-functional POSS metronidazole and POSS-metronidazole structures were characterized for their chemical structure; morphology and thermal behaviour by employing fourier transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, scanning electron microscope/energy dispersive X-ray spectroscopy and thermo gravimetric/differential thermal analysis, differential scanning calorimetric analyzer techniques. In addition, the antibacterial properties of the synthesized POSS-MTZ conjugate were tested with broth micro dilution methods on E.coli and S.aureus bacteria. The synthesized POSS-MTZ conjugate shows a statistically significant (p<0.001) antibacterial increase in both E.coli and S.aureus bacteria compared to pure metronidazole (MTZ). Biocompatibility of the POSS-MTZ conjugate was detected in an in vitro cell culture system with an MTT test on L929 mouse skin fibroblast cells. POSS-MTZ conjugates are not cytotoxic. POSS-MTZ conjugate with good biocompatibility and high antibacterial activity can be modified and used for medical and industrial purposes (e.g. wound dressing material, medical surface coating, packaging etc.

A sensitive calorimetric technique to study energy (heat) exchange at the nano-scale.

Every time a chemical reaction occurs, an energy exchange between reactants and the environment takes place, which is defined as the enthalpy of the reaction. During the last few decades, research has resulted in an increasing number of devices at the micro- or nano-scale. Sensors, catalyzers, and energy storage systems are more and more developed as nano-devices which represent the building blocks for commercial "macroscopic" objects. A general method for the direct evaluation of the energy balance of such systems is not available at present. Calorimetry is a powerful tool to investigate energy exchange, but it usually requires macroscopic sample quantities. Here, we report on the development of an original experimental setup able to detect temperature variations as low as 10 mK in a sample of ∼10 ng using a thermometer device having physical dimensions of 5 × 5 mm2. This technique has been utilized to measure the enthalpy release during the adsorption process of H2 on titanium-decorated monolayer graphene. The sensitivity of these thermometers is high enough to detect a hydrogen uptake of ∼10-10 moles, corresponding to ∼0.2 ng, with an enthalpy release of about 23 μJ. The experimental setup allows, in perspective, scalability to even smaller sizes.

Effect of dC → d(m5C) substitutions on the folding of intramolecular triplexes with mixed TAT and C+GC base triplets

Oligonucleotide-directed triple helix formation has been recognized as a potential tool for targeting genes with high specificity. Cystosine methylation in the 5′ position is both ubiquitous and a stable regulatory modification, which could potentially stabilize triple helix formation. In this work, we have used a combination of calorimetric and spectroscopic techniques to study the intramolecular unfolding of four triplexes and two duplexes. We used the following triplex control sequence, named Control Tri, d(AGAGAC5TCTCTC5TCTCT), where C5 are loops of five cytosines. From this sequence, we studied three other sequences with dC → d(m5C) substitutions on the Hoogsteen strand (2MeH), Crick strand (2MeC) and both strands (4MeHC). Calorimetric studies determined that methylation does increase the thermal and enthalpic stability, leading to an overall favorable free energy, and that this increased stability is cumulative, i.e. methylation on both the Hoogsteen and Crick strands yields the largest favorable free energy. The differential uptake of protons, counterions and water was determined. It was found that methylation increases cytosine protonation by shifting the apparent pKa value to a higher pH; this increase in proton uptake coincides with a release of counterions during folding of the triplex, likely due to repulsion from the increased positive charge from the protonated cytosines. The immobilization of water was not affected for triplexes with methylated cytosines on their Hoogsteen or Crick strands, but was seen for the triplex where both strands are methylated. This may be due to the alignment in the major groove of the methyl groups on the cytosines with the methyl groups on the thymines which causes an increase in structural water along the spine of the triplex.

Binding affinity and in vitro cytotoxicity of harmaline targeting different motifs of nucleic acids: An ultimate drug designing approach

The work focuses towards interaction of harmaline, with nucleic acids of different motifs by multispectroscopic and calorimetric techniques. Findings of this study suggest that binding constant varied in the order single-stranded (ss) poly(A)>double-stranded calf thymus (CT) DNA>double-stranded poly(G)·poly(C)>clover leaf tRNAPhe . Prominent structural changes of ss poly(A), CT DNA, and poly(G)· poly(C) with concomitant induction of optical activity in the bound achiral alkaloid molecule was observed, while with tRNAPhe , very weak induced circular dichroism perturbation was seen. The interaction was predominantly exothermic, enthalpy driven, and entropy favored with CT DNA and poly(G)·poly(C), while it was entropy driven with poly(A) and tRNAPhe . Intercalated state of harmaline inside poly(A), CT DNA, and poly(G)·poly(C) was shown by viscometry, ferrocyanide quenching, and molecular docking. All these findings unequivocally pointed out preference of harmaline towards ss poly(A) inducing self-structure formation. Furthermore, harmaline administration caused a significant decrease in proliferation of HeLa and HepG2 cells with GI50 of 28μM and 11.2μM, respectively. Nucleic acid fragmentation, cellular ultramorphological changes, decreased mitochondrial membrane potential, upregulation of p53 and caspase 3, generation of reactive oxygen species, and a significant increase in the G2 /M population made HepG2 more prone to apoptosis than are HeLa cells.

Thermodynamic Modeling and Experimental Study of CO2 Dissolution in New Absorbents for Post-Combustion CO2 Capture Processes

Demixing solvents have been suggested as an alternative to aqueous solutions of alkanolamines for the decarbonation of industrial effluents. These solvents undergo a liquid–liquid phase separation when heated. A phase-separation step could be integrated in the carbon dioxide (CO2) capture process to reduce energetic cost of the solvent regeneration step. As part of a general project on the dissolution of CO2 in aqueous solutions of piperidines, 3-methylpiperidine and 4-methylpiperidine have been investigated. The enthalpies of solution of CO2 in aqueous solutions of those methylpiperidines have been measured using a flow calorimetric technique. This technique makes it possible to simultaneously determine the enthalpies of solution and CO2 solubility limits. The experimental data were used to develop a thermodynamic model representative of phase equilibrium and enthalpy of solution. The carbamate formation constants of the 3-methylpiperidine and 4-methylpiperidine are adjusted in the model. The thermodynam...

Influence of Sb substitution on thermal and electrical characteristics of Ge-Sn-Se chalcogenide glass system

Present research work reports the systematic investigation of thermal and electrical characterizations of Ge20Sn10Se70-xSbx (x = 0, 3, 6, 9, 12, 15) glass system to probe the structural modifications. Bulk samples are prepared using melt quenching technique. Differential scanning calorimetric technique (DSC) is used at the constant heating rate of 100C under nonisothermal conditions. Different kinetic parameters viz. glass transition temperature Tg, Hruby parameter Hr, crystallization temperature Tc, etc., have been calculated. Glasses under study shows good thermal stability, hence, can find practical applications especially in optical fiber technology. Further, in the current study, an attempt has been made to observe the variation in conductivity with respect to the increase in temperature for amorphous Ge20Sn10Se70-xSbx (x = 0, 3, 6, 9, 12, 15) using two probe method and hence the band structure and corresponding conduction mechanism is studied.

Conductive bio-polymer electrolyte iota-carrageenan with ammonium nitrate for application in electrochemical devices

Bio-polymer electrolyte iota-carrageenan (Ι-carrageenan) with ammonium nitrate (NH4NO3) has been prepared by solution-casting technique. The increase in amorphous nature of the bio-polymer electrolyte due to the addition of salt has been confirmed by X-ray diffraction analysis. From the XRD spectra, the average particle size has been calculated using the Debye–Scherrer formula and the value is 0.98 nm. The complex formation between the polymer and the salt has been confirmed by Fourier transform infra-red spectroscopy. The glass transition temperature of the bio-polymer Ι-carrageenan with NH4NO3 electrolytes has been found using differential scanning calorimetric technique. From the AC impedance spectroscopic analysis, the ionic conductivity value has been found to be 1.46×10−3S/cm at ambient temperature for the composition of 1.0g Ι-carrageenan: 0.4wt% NH4NO3. The temperature dependent conductivity of the polymer electrolyte obeys an Arrhenius relationship. The dielectric behavior has been analyzed using dielectric permittivity (ε*) and the relaxation frequency (τ) has been calculated from the loss tangent spectra (tan δ). The modulus spectra indicate non-Debye nature of the material. Ionic transference number has been found to be 0.95 for the polymer 1.0g Ι-carrageenan: 0.4wt% NH4NO3. The result reveals that the conducting species are predominantly due to ions. Electrochemical stability window of 2.46V has been measured by using linear sweep voltammetry for the highest ionic conducting membrane. A primary proton battery has been constructed with the highest conductivity sample and open circuit voltage has been found to be 1.04V. Fuel cell has been constructed with the highest proton conductivity polymer 1.0g Ι-carrageenan: 0.4wt% NH4NO3 and the open circuit voltage found to be 442mV.

Determining the heat flux distribution of laminar plasma jet impinging upon a flat surface: An indirect method using surface transformation hardening

Laminar plasma jet (LPJ) is a promising high energy beam for various engineering applications. However, there lacks of a method for measuring the heat flux distribution of the LPJ impinging upon a flat surface (qH(r)), with high accuracy, little limitations on the axial distance from the torch exit and the power of the LPJ. Therefore, this paper proposes an indirect method for determining qH(r) using surface transformation hardening. It makes use of the fact that when LPJ is used in the surface transformation hardening of a ferrous material, the size of the heat affected zone is directly correlated with the heat flux distribution. It combines the experiment and numerical simulation on the heat transfer process of the surface transformation hardening to indirectly obtain qH(r) at a certain axial distance from the torch exit. The proposed method was used to determine qH(r) of the nitrogen LPJ generated by a customized laminar plasma torch at different axial distance from the torch exit. It was found that the proposed method exhibits high accuracy through benchmarking with the results obtained by numerical simulation and by direct measurement using the double calorimetric technique reported in literature. Furthermore, the proposed indirect method has little limitations on the axial distance from the torch exit and the power level of the LPJ. In addition, it was found that that axial gradient of the LPJ’s heat flux is low, with less than 50% drop after an axial distance of 100 mm from the torch exit. Finally, the determined qH(r) was directly verified by the numerical simulations and experimental observation on plasma surface transformation hardening of a different ferrous material.

Fabrication of MgO and ZnO nanoparticles by the aid of eggshell bioactive membrane and exploring their catalytic activities on thermal decomposition of ammonium perchlorate

In this research, spherical nanoparticles (NPs) of magnesium oxide (MgO) and zinc oxide (ZnO) were prepared by calcinations of their carbonate precursor, fabricated through the eggshell bioactive membrane at the room temperature. The chemical structure, purity, particle size and morphology of the fabricated MgO and ZnO NPs were characterized by X-ray diffraction and scanning electron microscopy (SEM) techniques. The results confirmed the formation of targeted materials, while the obtained MgO and ZnO NPs have the average particle size of about 35 and 30 nm, respectively. The fabricated NPs were explored as the additives to improve thermal behavior of ammonium perchlorate (AP) particles. To achieve this aim, NPs were mixed with AP by solvent/non-solvent method to prepare nano-composites. The SEM photographs showed the successful dispersion of MgO and ZnO NPs throughout the AP particles without considerable agglomeration. Thus, thermogravimetric analysis and differential scanning calorimetric techniques were utilized to examine thermal behavior of the prepared AP nano-composites. Thermal analysis results showed that introducing 0.5% MgO NPs yields an interested catalytic effect on the thermal pattern of AP, while adding 2% ZnO NPs leads to improve thermal decomposition of AP. Finally, the apparent activation energy (E), ΔG #, ΔH #, ΔS # of thermal decomposition processes of pure and treated samples were obtained by non-isothermal methods proposed by Kissinger and Starink.

\u03b1-Tocopherol/AOT/alkane/water system

In this paper the calorimetric studies on α-tocopherol/AOT/alkane/water systems are presented. Structural representations of surfactant AOT (a) and α-tocopherol (b) are shown below. α-Tocopherol (antioxidant) is a form of vitamin E that is preferentially absorbed and accumulated in humans. AOT is an anionic type of surfactant. Its molecule contains two non-polar hydrocarbon tails connected to the polar head. The paper contains new experimental data of heat of mixing (Q) for heterogeneous system α-tocopherol/AOT/n-alkane with and without water measured at 309.2 K. The heat of mixing for AOT (sodium bis (2-ethylhexyl) sulfosuccinate) and α-tocopherol solutions in n-alkane (heptane, decane, hexadecane) as the function of surfactant concentration and parameter R given as the water to surfactant molar ratio R = [H2O]/[AOT] was measured. It can be seen that the Q values grow significantly with temperature increase which indicates on entropic origin of this process. The significant influence of surfactant concentration on Q values was noticed. Unexpectedly, the water presence in the reverse micelles did not have any noticeable influence on the heat of mixing values measured at 309.2 K. There was not noticed the significant hydrocarbon chain length influence on the thermal effect of mixing α-tocopherol and AOT solutions. The thermodynamic parameters: the binding constant (K) and the molar enthalpy of transition (ΔHtr0) of α-tocopherol between solvent and AOT reverse micelles, were calculated from the heat of mixing data as a function of surfactant concentration using the nonlinear regression method. The new calorimetric data measured at 309.2 K were compared to results obtained earlier at 298.2 K, as well as have been discussed in the context of the hydrocarbon chain length and water presence influence on α-tocopherol solubility in AOT reverse micelles. Generally in all investigated systems have been not found a significant influence of water concentration in AOT reverse micelles on α-tocopherol molecules distribution between organic phase and micellar phases. The exothermic values of α-tocopherol molecules transition from organic to micellar phase indicate on spontaneous motion of α-tocopherol towards AOT aggregates. For the systems with n-heptane and n-decane as a solvent, the (ΔHtr0) values are between −51 and −52 kJ mol−1 whereas for n-hexadecane around −43 kJ mol−1. Such tendency can be explained through hydrocarbon chains orientation effect existing in hexadecane which probably is responsible for a α-tocopherol molecules freedom motion limitation. Moreover, the solubility of the α-tocopherol in AOT reverse micelles measured with calorimetric technique has been compared to the literature data obtained, respectively, with UV spectrophotometer for reverse micelles, and for phospholipids bilayer by other techniques. Finally, transferring of α-tocopherol from solvent to AOT reverse micelles, intermolecular interactions between α-tocopherol and AOT micelles were discussed, and a privileged place of α-tocopherol in the palisade layer of AOT reverse micelle has been deduced.

Thermodynamic properties of Li-Pb system

The integral mixing enthalpy of liquid Li-Pb alloys was measured with the use of the calorimetric technique. The experimental studies involved measurements at different temperatures: 817, 923, 1021 and 1023K in the entire concentration range. The thermodynamic optimization was performed basing on the obtained results and the available literature data. The description of the excess Gibbs energy of temperature and composition was proposed with the use of a new model, which connects the polynomial and associated modelling. The obtained molar mixing enthalpy changes, excess Gibbs energy, and the molar excess entropy values are negative in the entire concentration range. Moreover, the existence of Li4Pb and LiPb associates in the liquid solutions was found, according to the analysis of the partial concentration structure factors (Scc(0)) and short range order (SRO) parameters.

Calorimetric and Spectroscopic Studies of the Effects of the Cell Penetrating Peptide Pep-1 and the Antimicrobial Peptide Combi-2 on Vesicles Mimicking Escherichia coli Membrane.

The objective of this study is to measure and compare the effects of the cell penetrating peptide (CPP) Pep-1 and the antimicrobial peptide (AMP) combi-2 on vesicles of membranes mimicking Escherichia coli (E. coli). To characterize the effects of Pep-1 and combi-2 on E. coli membrane vesicles, a combination of five biophysical techniques was employed: fluorescence, infrared, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) techniques. Upon addition of E. coli membranes, tryptophan fluorescence intensity of Pep-1 showed a sudden blue-shift and decreased in a nonconcentration-dependent manner while the intensity of combi-2 decreased in a concentration-dependent manner, most significantly for a very low peptide-to-lipid ratio of 1:40. Complexes of Pep-1 and combi-2 with E. coli membrane mimicking vesicles having shown a significant blue-shift in fluorescence intensity were then prepared and studied in freeze-dried states. IR results indicate that Pep-1 and combi-2 adopt a major 310-helix structure in the presence of E. coli membrane mimicking vesicles at low peptide concentration. Pep-1 and combi-2 have a similar effect on E. coli membrane mimicking vesicles at low concentration even though combi-2 is in the interfacial region of the bilayer while Pep-1 is located between the interfacial region and the hydrophobic region. Combi-2 at low concentration acts as a CPP. TGA and DSC results reveal that combi-2 has a stabilizing effect on E. coli at any concentration while Pep-1 stabilizes the E. coli membrane only at high concentration. Both peptides show a preferential interaction with one of the anionic lipids leading to clustering in E. coli membrane. SEM images reveal that Pep-1 and combi-2 form superstructures including fibrils in the presence of E. coli membrane mimicking vesicles. Calorimetric and spectroscopic techniques may be used in a complementary way with imaging techniques to gain more insights into peptide-lipid interactions.

Geant4 simulations of the absorption of photons in CsI and NaI produced by electrons with energies up to 4 MeV and their application to precision measurements of the [formula omitted]-energy spectrum with a calorimetric technique

The yield of photons produced by electrons slowing down in CsI and NaI was studied with four electromagnetic physics constructors included in the Geant4 toolkit. The subsequent absorption of photons in detector geometries used for measurements of the β spectrum shape was also studied with a focus on the determination of the absorption fraction. For electrons with energies in the range 0.5–4 MeV, the relative photon yields determined with the four Geant4 constructors differ at the level of 10−2 in amplitude and the relative absorption fractions differ at the level of 10−4 in amplitude. The differences among constructors enabled the estimation of the sensitivity to Geant4 simulations for the measurement of the β energy spectrum shape in 6He decay using a calorimetric technique with ions implanted in the active volume of detectors. The size of the effect associated with photons escaping the detectors was quantified in terms of a slope which, on average, is respectively −5.4 %/MeV and −4.8 %/MeV for the CsI and NaI geometries. The corresponding relative uncertainties as determined from the spread of results obtained with the four Geant4 constructors are 0.0067 and 0.0058.

Combustion of Coal Volatiles in the Freeboard of a Fluidized Bed Combustor: an Experimental Approach

Previous attempts to determine the amount of volatile material transferred into and burnt in the freeboard region (FBR) of fluidized bed coal combustors have been few and/or ambiguous. A major reason for this is the difficulty of separating the two combustion processes (volatiles and char) occurring simultaneously within both bed and freeboard sections, and because the instrumentation for measuring these separate phenomena directly is non-existent. Therefore, a calorimetric technique is reported here to produce quantitative information on the fraction of heat released by the volatile component in the FBR. The calorimetric experiments revealed that over one third of the original volatiles may be released and burnt above the bed at low excess air levels ( 850°C) and high excess air levels (up to 40 %). The transfer of coal volatiles in the FBR was found to be influenced by the in-bed operating and fluidizing conditions in the following order: bed temperature (Tb), excess air (XSA), fluidizing velocity (Uo) and coal particle size (dc).

Binding of ibuprofen to human hemoglobin: elucidation of their molecular recognition by spectroscopy, calorimetry, and molecular modeling techniques

Ibuprofen, used for the treatment of acute and chronic pain, osteoarthritis, rheumatoid arthritis, and related conditions has ample affinity to globular proteins. Here we have explored this fundamental study pertaining to the interaction of ibuprofen with human hemoglobin (HHb), using multispectroscopic, calorimetric, and molecular modeling techniques to gain insights into molecular aspects of binding mechanism. Ibuprofen-induced graded decrease in absorption spectra indicates protein disruption along with sedimentation of HHb particle. Red shifting of absorption peak at 195 nm indicates alteration in the secondary structure of HHb upon interaction with ibuprofen. Flouremetric and isothermal titration calorimetric (ITC) studies suggested one binding site in HHb for ibuprofen at 298.15 K. However, with increase in temperature, ITC revealed increasing number of binding sites. The negative values of Gibbs energy change (ΔG0) and enthalpy change (ΔH0) along with positive value of entropy change (ΔS0) strongly suggest that it is entropy-driven spontaneous exothermic reaction. Moreover, hydrophobic interaction, hydrogen bonding, and π–π interaction play major role in this binding process as evidenced from ANS (8-anilino-1-napthalenesulphonic acid), sucrose binding, and molecular modeling studies. The interaction impacts on structural integrity and functional aspects of HHb as confirmed by CD spectroscopy, increased free iron release, increased rate of co-oxidation and decreased rate of esterase activity. These findings suggest us to conclude that ibuprofen upon interaction perturbs both structural and functional aspects of HHb.

Melting Behavior of a DNA Four-Way Junction Using Spectroscopic and Calorimetric Techniques.

Intramolecular four-way junctions are structures present during homologous recombination, repair of double stranded DNA breaks, and integron recombination. Because of the wide range of biological processes four-way junctions are involved in, understanding how and under what conditions these structures form is critical. In this work, we used a combination of spectroscopic and calorimetric techniques to present a complete thermodynamic description of the unfolding of a DNA four-way junction (FWJ) and its appropriate control stem-loop motifs (Dumbbell, GAAATT-Hp, CTATC-Hp, GTGC-Hp, and GCGC-Hp). The overall results show that the four-way junction increases the cooperative unfolding of its stems, although the reason for this is unclear, as the arms do not unfold as coaxial stacks, and thus its melting behavior cannot be accurately described by its control molecules. This is in contrast to what has been seen for two- and three-way junctions. In addition, the lack of base stacking and the ΔHvH/ΔHcal ratio seen at low salt indicate the four-way junction exists as a mixture of conformations, one of which is most likely the open-X structure which has unpaired bases at the junction. This was confirmed by single value decomposition of CD and UV spectra. This indicates that at low salt there is a third spectroscopically distinct species, while at higher salt there are only two species, folded and unfolded. Based on the enthalpy, Δnion, and ΔnW, the dominant folded structure at high salt is most likely the antiparallel stacked-X structure.

Thermokinetics behavior of epoxy adhesive reinforced with low viscous aliphatic reactive diluent and nano-fillers

The current study reports the effect of low viscous aliphatic reactive diluent (RD), MWCNT and VGCF on the curing kinetics of amine cured epoxy adhesive system employing non-isothermal differential scanning calorimetric (DSC) technique. Non-isothermal DSC thermograms of epoxy adhesive were studied at various heating rates: 5, 10 and 15 °C/min. The decrease in the exothermic peak height with the introduction of MWCNTs and VGCFs was taken as proof of the acceleration effect of nano-fillers on the epoxy-amine curing reaction. Also, increased T onset , T P and ΔH curs values were observed for epoxy/RD adhesive system at all heating rates. The value of activation energy (E a ) was determined using Kissinger and Flynn-Wall-Ozawa methods. Experimental results showed that the addition of 10 wt% RD increased the E a from 60 to 63 kJ/mol on account of the reduced viscosity, allowing better contact of resin with the curing agent. Furthermore, MWCNTs have an accelerating effect on the cure kinetics that does not change the autocatalytic cure reaction mechanism of epoxy resin. It was also found that the addition of MWCNT and VGCF decreases the overall degree of conversion, as evident with lower ΔH cure and E a of the cured adhesive when compared with epoxy/RD system. The dependency of E a on degree of conversion ranging from α =0.1 to 0.9was also investigated. The two normalized functions y(α) and z(α) were also considered in order to study the complex curing mechanism. The kinetic parameters m, n and lnA were obtained by using two parameter autocatalytic Sestak-Berggren model. The curves revealed good agreement between experimentally determined and theoretically obtained MWCNT/VGCF reinforced epoxy adhesive systems.

Thin-film calorimetry: In-situ characterization of materials for lithium-ion batteries

AbstractThin-film calorimetry allows for qualitative and quantitative in-situ analysis of thermodynamic properties of thin films and thin-film systems from room temperature up to 1000 °C. It is based on highly sensitive piezoelectric langasite resonators which serve simultaneously as planar temperature sensors and substrates for the films of interest. Generation or consumption of heat during phase transformations of the films cause deviations from the regular course of the resonance frequency. Thermodynamic data such as phase transformation temperatures and enthalpies are extracted from these deviations. Thin-film calorimetry on Sn and Al thin films is performed to prove the concept. The results demonstrate high reproducibility of the measurement approach and are in agreement with literature data obtained by established calorimetric techniques. The calibration of the system is done in different atmospheres by application of defined heat pulses via heating structures. The latter replace the films of interest and simulate phase transformations to provide detailed analysis of the heat transfer mechanisms occurring in the measurement system. Based on this analysis, a data evaluation concept is developed. Application-relevant studies are performed on thin films of the lithium-ion battery materials NMC(A), NCA, LMO, and MoS2. Their phase transformation temperatures and enthalpies are evaluated in oxidizing and reducing atmospheres. Furthermore, their thermodynamic stability ranges are presented. Finally, measurements on all-solid-state thin-film batteries during electrochemical cycling are performed. They demonstrate the suitability of the system for in-situ investigations.

Energy estimation and modeling solid thermal explosion containment on reactor for three organic peroxides by calorimetric technique

In this paper, we describe thermokinetic properties and decomposition characteristics of benzoyl peroxide, dicumyl peroxide, and lauroyl peroxide, which are widely used in the polymerization process as energy boosters. In the past, many accidents occurred that involved overpressure and runaway excursion of the process and thermal explosion. One reason for accidents is because of the peroxy group (–O–O–) of organic peroxides (OPs) due to its thermal instability and high sensitivity when exposing to heat. Apparent activation energy and pre-exponential factor were obtained during decomposition via non-isothermal well-recognized kinetic equation, fitting curve tests, and approximate solution to design safer reaction conditions when OPs are used as fuel. Moreover, the storage conditions were investigated for the simulation of thermal explosion in a 24-kg cubic box package and a 400-kg barrel reactor for commercial application. Experimental results established the novel features of solid explosion hazard of OPs.

New series of non-toxic DNA intercalators, mitochondria targeting fluorescent dyes

Five novel benzoxazolium and benzothiazolium derived asymmetric dicationic monomethine cyanine dyes, bearing a thioester group have been synthesised via condensation of quaternary nitrogen containing heterocyclic salts in various anhydrides. Their chemical structures were evaluated by NMR, ESI/MS, IR spectroscopy, and melting point temperatures. Photophysical studies on the title compounds were performed in methanol solutions. The longest wavelength absorption maxima λmax of the studied dyes are in the region 453–508 nm. The corresponding fluorescence maxima λfl were registered within the 489–553 nm. Further spectroscopy and calorimetric techniques including circular dichroism (CD), UV–Vis, fluorescence, thermal denaturation and isothermal titration calorimetry have been applied to the studied dyes in the presence of biopolymers, in order to evaluate their staining ability as fluorescent markers. In aqueous solution the compounds exhibit no intrinsic fluorescence, however upon binding to dsDNA and dsRNA they show considerable enhancement of fluorescence intensity. Binding constants Ks of the complexes [dye–polynucleotide] have been evaluated from fluorescence spectral titrations. Although the intercalation is the predominant binding mode, the compounds show little or no effect on the cell proliferation. Upon fast cell internalization the compounds accumulate in the mitochondrial space.