Calorimetry

In the present study, a novel environment friendly dry method for preparation of guar gum maleate (GGM) with varying degrees of substitution (DS; 0.02-1.04) was optimized. GGM with a maximum DS of 1.04 was successfully synthesized using guar gum (GG) and maleic anhydride (MA) in proportion of 1: 1 at 80 °C with 4 h of reaction time. The activation energy for the reaction was determined to be 36.91 ± 3.61 kJ mol-1 with pre-exponential factor of 1392 min-1 ...

To study thermal behaviour during spontaneous combustion of an open-pit coal mine, mixed slag (coal, oil shale, and coal gangue) was taken as the research object. Laser thermal conductivity analyser and differential scanning calorimetry were used to test thermophysical parameters and heat release characteristics of the minerals. The parameters can be employed to calculate the apparent activation energy using the Arrhenius equation and evaluate the thermal behaviour of open-pit mixed slag. The results indicate that thermophysical parameters have stage characteristics...

T4 polynucleotide kinase (T4 PNK) phosphorylates the 5'-terminus of DNA and RNA substrates. It is widely used in molecular biology. Single nucleotides can serve as substrates if a 3'-phosphate group is present. In this study, the T4 PNK-catalyzed conversion of adenosine 3'-monophosphate (3'-AMP) to adenosine-3',5'-bisphosphate was characterized using isothermal titration calorimetry (ITC). Although ITC is typically used to study ligand binding, in this case the instrument was used to evaluate enzyme kinetics by monitoring the heat production due to reaction enthalpy...

Lanmodulins are small, ∼110-residue proteins with four EF-hand motifs that demonstrate a picomolar affinity for lanthanide ions, making them efficient in the recovery and separation of these technologically important metals. In this study, we examine the thermodynamic and structural complexities of lanthanide ion binding to a 41-residue domain, EF 2-3, that constitutes the two highest-affinity metal-binding sites in the lanmodulin protein from Methylorubrum extorquens . Using a combination of circular dichroism (CD) spectroscopy, isothermal titration calorimetry (ITC), two-dimensional infrared (2D IR) spectroscopy, and molecular dynamics (MD) simulations, we characterize the metal binding capabilities of EF 2-3...

Herein, a self-healing polyacrylate system was successfully prepared by introducing crosslinking agents containing disulfide bonds and monomers capable of forming quadruple hydrogen bonds through free radical copolymerization. This polymer material exhibited good toughness and self-healing properties through chemical and physical dual dynamic networks while maintaining excellent mechanical properties, which expanded the development path of self-healing acrylate materials. Compared to uncrosslinked and single dynamically crosslinked polymers, its elongation at break was as high as 437%, and its tensile strength was 5...

BACKGROUND: Monascus pigment (MP) is a natural food coloring with vital physiological functions but prone to degradation and color fading under light conditions. RESULTS: This study investigated the effect of complex formation of soybean protein isolate (SPI), maltodextrin (MD), and MP on the photostability of MP. Light stability was assessed through retention rate and color difference. Fluorescence spectroscopy (FS), circular dichroism (CD), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) explored MP, SPI, and MD interactions, clarifying the MP-SPI-MD complex mechanism on MP's light stability...

BACKGROUND/PURPOSE: Temperature-dependent phase compositional changes influence the mechanical properties of heat-treated nickel-titanium (NiTi) rotary instruments. This study evaluated the phase composition, bending properties, and cyclic fatigue resistance of HyFlex EDM NiTi rotary instruments against differently heat-treated and non-heat-treated NiTi instruments at body temperature (BT). MATERIALS AND METHODS: HyFlex EDM OneFile (EDM) instruments, heat-treated HyFlex CM (CM) and Twisted File (TF) instruments, and non-heat-treated K3 instruments (size #25/...

Polymer science is receiving wider acceptance in the organic chemistry community; thus, it is imperative to include it in the undergraduate organic chemistry curriculum. Despite the ever-increasing popularity of the topic of polymer chemistry in undergraduate curricula, a comprehensive laboratory experiment module describing a polypeptide synthesis by ring-opening polymerization of N-carboxyanhydride (NCA ROP) and a homopolymer synthesis by activators-regenerated by electron-transfer for atom transfer radical polymerization (ARGET ATRP) has yet to be proposed...

The porous skeleton structure of oxidizers can effectively enlarge the contact area with fuels and boost the reactivity of thermites, but the overly complex preparation processes tend to limit their use to some extent. To overcome this issue, water-soluble starch and copper nitrate were used as a template to form a carbon skeleton copper oxide (C-CuO) after spray drying and calcination. By adding nanoaluminum into the spray drying process, the n-Al@C-CuO was prepared and compared with the physically mixed n-Al/C-CuO in the context...

Two synthesis routes of the zircon-hafnon solid solution series were carried out. The high-temperature route uses the growth of single crystals via a flux mixture that has been cooled down slowly from 1400 °C over 4 weeks. The reaction products were colorless and idiomorphic without byproducts. The hydrothermal tetraethoxysilane (TEOS)-based route represents the low-temperature method at 200 °C for approximately 7 days. The hydrothermal route yielded a white powder and scanning electron microscopy analysis thereof did not reveal any specific idiomorphic properties...

This research work aimed to develop and evaluate proniosomes for the oral delivery of the lipophilic drug Irbesartan (IRB) to improve its solubility and bioavailability. Proniosomes of Irbesartan were formulated using a lipid, surfactant, and carrier by a slurry method. Based on the prepared preliminary trial batches and their evaluation, the formulation was optimized by employing a Box-Behnken design (BBD) in which concentrations of span 60 ( X 1 ), cholesterol ( X 2 ), and mannitol ( X 3 ) were used as three independent variables and the vesicular size (VS) ( Y 1 ), % entrapment efficiency (% EE) ( Y 2 ), and % cumulative drug release (% CDR) ( Y 3 ) were used as dependent variables...

We report the results of a study focusing on the influence of crystallization kinetics and flow behavior on structural inhomogeneities in 3D-printed parts made from polyamide 12 (PA12) and poly(lactic acid) (PLA) by dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), fast scanning calorimetry (FSC), and wide-angle X-ray diffraction (WAXD). Temperature-dependent WAXD measurements on the neat PLA filament reveal that PLA forms a single orthorhombic α phase during slow cooling and subsequent 2nd heating...

OBJECTIVES: Antibiotics are the most commonly administered medications among pediatric patients. However most of the time, accurate dose administration to children becomes a problem due to the extremely bitter taste. Cefpodoxime proxetil (CP) and roxithromycin (ROX) are antibiotics often prescribed to the pediatric population and have a bitter taste. Marketed formulations of these drugs are dry suspension and/or tablets. The lyophilization method involves various steps and thus is time consuming and expensive...

This research addresses the growing need for fast and cost-efficient methods for microplastic (MP) analysis. We present a thermo-analytical method that enables the identification and quantification of different polymer types in sediment and sand composite samples based on their phase transition behavior. Differential scanning calorimetry (DSC) was performed, and the results were evaluated by using different regression models. The melting and crystallization enthalpies or the change in heat capacity at the glass transition point were measured as regression analysis data...

A new concept for the regioselective synthesis of Hamilton-receptor and cyanurate-functionalized oligo adducts of the fullerene C60 was developed. Based on an in-situ deprotection and click-post-functionalization approach with novel azido precursors, the corresponding fullerene hexakis-adducts with octahedral addition patterns and up to twelve Hamilton-receptor/cyanurate moieties surrounding the fullerene sphere were synthesized. The versatility of this approach was further demonstrated by the synthesis of Hamilton-receptor/cyanurate functionalized fullerene mono-adducts, which are not accessible by direct cyclopropanation...

Histamine is a biogenic amine that poses a potential threat to public health due to its toxicological effects. In this study, we identified histamine-binding peptides by screening a random 12-mer peptide library, employing a novel biopanning approach that excluded histidine-binding sequences in the final round. This additional step enhanced the selectivity of the peptides and prevented interference from histidine during detection. The binding affinities of synthesized peptides to histamine were assessed using isothermal titration calorimetry (ITC)...

Starches are hydrolyzed into monosaccharides by mucosal α-glucosidases in the human small intestine. However, there are few studies assessing the direct digestion of starch by these enzymes. The objective of this study was to investigate the changes in the structure and enzyme binding of starches during in vitro hydrolysis by mammalian mucosal enzymes. Waxy maize (WMS), normal maize (NMS), high-amylose maize (HAMS), waxy potato (WPS), and normal potato (NPS) starches were examined. The order of the digestion rate was different compared with other studies using a mixture of pancreatic α-amylase and amyloglucosidase...

Acyl-Coenzyme A binding domain containing proteins (ACBDs) are ubiquitous in nearly all eukaryotes. They can exist as a free protein, or a domain of a large, multidomain, multifunctional protein. Besides modularity, ACBDs also display multiplicity. The same organism may have multiple ACBDs, differing in sequence and organization. By virtue of this diversity, ACBDs perform functions ranging from transport, synthesis, trafficking, signal transduction, transcription, and gene regulation. In plants and some microorganisms, these ACBDs are designated ACBPs (acyl-CoA binding proteins)...

Developing a reliable and effective quality evaluation system for traditional Chinese medicine (TCM) is both challenging and crucial for its advancement. This study employs fingerprinting techniques to establish precise and comprehensive quality control for TCM, taking Xuezhikang capsules as an example and aiming to facilitate the internationalization of TCM. The "double wavelength absorption coefficient ratio fingerprint" and "Reliability theory" are developed to determine the fingerprint peak purity and fingerprint reliability respectively...

BACKGROUND: Health-related quality of life (HRQOL) is related to body composition, which is also related to resting metabolic rate (RMR). RMR can be increased by exercise and diet interventions that are not dependent on changes in body composition, so a link between RMR and HRQOL may provide interventions that directly improve HRQOL in women. METHODS: One hundred twenty women (median age 63.5 [IQR: 53.0-71.0] years) completed one-time measurement of body composition (multi-frequency bioelectrical impedance), RMR (handheld calorimetry), and HRQOL (RAND-36)...