Thermal behaviour of corn starch granules under action of fungal α-amylase

Corn starch, partially hydrolyzed by fungal α-amylase was investigated by using thermal analysis, microscopy and X-ray diffraction. After enzymatic treatment lower degradation onset temperatures were observed. DSC analysis showed almost similar range of gelatinization temperature, however, the enthalpies of gelatinization increased for the partially hydrolyzed starch granules. According to the X-ray diffraction analysis, stronger cereal pattern peaks were recognized after enzymatic digestion. The results suggested that the hydrolysis was more pronounced in the amorphous part of the starch granules.     

Thermal investigation of PEG 4000 — oxazepam binary system

A thermal study using DSC and Hot Stage Microscopy (HSM) was carried out to investigate the interaction in solid state of the binary system PEG 4000 — oxazepam, and to establish their phase diagram. The eutectic composition, which melting occurs at lower temperature as compared with the pure components, has been determined. The results obtained by DSC and HSM have indicated that PEG 4000 — oxazepam mixtures displays no obvious incompatibilities, and that the system shows a typical eutectic behaviour. However because of the closeness of the melting of PEG 4000 to the eutectic temperature, it was difficult to determine precisely the eutectic composition and temperature on the basis of DSC measurements alone. The use of heats of fusion corresponding to physical mixtures allowed an estimation of the eutectic composition at 6% w/w oxazepam. Additional information of temperature (57.6C) and composition (5–10% w/w oxazepam) of the eutectic was obtained by HSM using the contact method. This low melting temperature in this range of compositions offers advantages in terms of drug stability and easy manufacture.     

Low generational polyamidoamine dendrimers to enhance the solubility of folic acid:A‘‘dendritic effect’’investigation

Low generational(G0–G2,G for generation) polyamidoamine(PAMAM) dendrimers were investigated as enhancers to improve the aqueous solubility of folic acid at pH 11 and pH 5.In these two cases,the solubility of folic acid increases with both the dendrimer concentration and generation.However,the solubilization mechanism is different.The electrostatic interaction between the primary amines of dendrimers and the ionized carboxylic groups of folic acid dominates the dissolution process at pH 11 while the increase of the solubility of folic acid at pH 5 is attributed to the hydrophobic encapsulation inside the dendrimer molecules.In addition,for comparison ethylenediamine was used as a small molecule control to examine the ‘‘dendritic effect' in the dendrimer-related solubilization process.Interestingly,PAMAM dendrimers exhibit,at pH 5,a significant superiority over ethylenediamine in enhancing solubility,whereas this ‘‘dendritic effect' cannot be observed under the basic condition.     

Thermal study and solubility tests of films based on amaranth flour starch–protein hydrolysate

The study deals with the effect of chemical and physical modifications on thermal properties and solubility properties of films based on amaranth flour starch–protein hydrolysate. Biodegradable and edible films were prepared by casting a 25% (w/w) solution of hydrolysate containing 20% glycerol and various additions of dialdehyde starch (0, 1 and 5%). After thermal exposure of films at 65 and 95 °C (for 6 and 48 h), thermal properties of films were studied employing differential scanning calorimetry and thermogravimetric analysis. Film solubility tests were performed in an aqueous environment at 25 °C. Chemical and physical modifications of films markedly affect their thermal properties and solubility.     

Commentary on ‘investigation on molecular interaction studies of binary mixture of Dehpa and Petrofin at 298.15 K’

The Redlich–Kister equations reported in the published paper do not describe the observed excess molar volumes, excess molar refractions and excess molar refractions. Significant differences are noted between the observed excess quantities (based on mole fraction additivity) and calculated values based on the published Redlich–Kister polynomial equations.     

Thermal analysis of the improved Hummers’ synthesis of graphene oxide

Journal of Thermal Analysis and Calorimetry - The improved Hummers’ synthesis of graphene oxide (GO) from graphite is investigated to monitor how the functional groups form during the...     

Corrigendum on ‘investigation on molecular interaction studies of binary mixture of Dehpa and Petrofin at 298.15 K’

Expressions of Redlich–Kister (RK) excess function using polynomials on difference of molar composition are used. Calculated values of excess properties from experimental values are well presented in some curves as a function of mole fraction (x₂) of the second pure component of the studied binary liquid mixture. Nevertheless, the authors presented values of adjustable parameters, not for the polynomial of the popular RK equation (i.e. vs. x₂–x₁), but for globally the excess property Y^E as an overall three degree polynomial on (x₂) including implicitly the molar fraction product (x₁·x₂) in their nonlinear regression, which can then induces some readers to probable confusion.     

The meaning of ‘concentration’

Terminology within a small laboratory community can be informal without danger of misunderstanding, but communication with a wider audience and not least in publications, needs unequivocal terms for defined concepts. As an example, the many meanings of “concentration” are explored to present a systematic nomenclature, including a concept diagram.

Thermal stability of cluster structure in Bi x Sn1− x molten alloys in vicinity of eutectic point

Structure of liquid Bi _x Sn_{1? x} molten alloys has been studies in the vicinity of eutectic point at temperatures of complete melting and above by 100?K. It is shown that the structure parameter concentration dependences reveal the deviation from linear function with extremum points at eutectic composition. Such features exist also at higher temperatures. The reason of untypical behaviour of structure parameters is supposed to be attributed to the existence of two kinds of clusters with Sn‐ and Bi‐like structures.     

Calorimetric and Raman investigation of cow’s milk lactoferrin

Lactoferrin (LF), a non-heme iron-binding protein of blood plasma and milk with antioxidant, cariostatic, anticarcinogenic, and anti-inflammatory properties, has been studied by differential scanning calorimetry (DSC) and Raman spectroscopy over a wide pH range (4.0–9.0). Using these two techniques, the modifications in the quantity of iron bounded in the cow’s milk LF and in the secondary structures, as a function of pH and heating, have been evaluated. DSC curves showed higher value of denaturation temperatures and enthalpy changes when LF was saturated with iron (holo-form) than when it was in its unsaturated form (apo-form). The denaturation curves of the protein solutions at pH ≥ 5.5 confirming that LF is a mix of apo- and holo-forms; on the contrary at pH 4.0, the holo-form is practically absent. Spectroscopic investigation showed that, as a function of pH, the content of α-helix increases up to pH 7.4, followed by a small decrease by further pH increase. The β-sheet percentage exhibits the opposite behavior, while the random-coil and turn structures do not change noticeably. In contrast, after heat-induced denaturation, strong variations were observed in the secondary structure, with an evident increase of β-sheet and decrease of the α-helix percentage. Finally, both thermal and spectroscopic analysis pointed out that the structure of cow’s milk LF is strictly sensible to pH variation and it has the highest thermal stability at physiological pH.     

Thermal investigation of heavy crude oil by simultaneous TG–DSC–FTIR and EDXRF

Present study investigates thermal behavior of two heavy crude oils with different °API values by simultaneous thermogravimetry–differential scanning calorimetry–fourier transform infrared spectroscopy (TG–DSC–FTIR), and an evaluation of the chemical element levels present in the oils’ ashes was done by energy dispersive X-ray fluorescence spectrometry. TG and DSC curves were obtained for two samples in nitrogen atmosphere. Among all inorganic components evaluated, the highest concentration in the two oils was SO₃. Thus this study may contribute to a better understanding of the thermal behavior of heavy crude oils and their composition.     

Complementary analytical methods for the phytochemical investigation of ‘Jardin de Granville’, a rose dedicated to cosmetics

‘Jardin de Granville’ is a new hybrid rose variety dedicated to cosmetic applications. To perform an exhaustive molecular investigation of the non-volatile secondary metabolites in this cultivar, a global approach was developed, combining four chromatographic techniques (HPTLC, HPLC-DAD-ELSD, UHPLC-HRMS and GC–MS). This approach afforded an on-line phytochemical fingerprinting of four plant organs of ‘Jardin de Granville’. Despite the wide diversity of molecular families and the pronounced differences in polarity between the molecules, this analytical strategy enabled an overview of the molecular composition of each sample to be rapidly obtained by HPTLC and HPLC and the molecular content to be correctly identified thanks to coupling with mass spectrometry. Polyphenols were identified in the EtOH/H₂O extracts; triterpenes, chlorophyll derivatives and lipids were characterized in the EtOAc extracts, and the fatty acids squalene, α-tocopherol and β-sitosterol were highlighted in the heptane extracts.     

Synthesis and Crystal Structure of N—（1‘’‘’—Phenyl—2‘’‘’—hydroxyethyl）—2,3—naphthylenedicarboximide

IntroductionThe design and the synthesis of new chiral ox-azoline[1,2 ] and C2 symmetric bis( oxazoline) ligandsand the application of their metal complexes inasymmetric catalytic reactions have inspired manyscientists to great exertions in recent years[3— 8] .Our interest has been focussed on the studies ofenantioselective transition metal catalysis ofhetero-cyclic ligands[9— 11] . In the synthesis of our new de-signed ligands,what is crucial is to select a rigidcyclic backbone. Bis( oxazo…     

The features of nitric acid ‘mercerization’ of cellulose

Transformation of native cellulose species into cellulose-II polymorph through the additive Knecht compound formed under the action of 68.5% nitric acid has been studied. Probable causes of peculiar temperature effects in the course of phase transformations taking place in cellulose of various origin, crystallite dispersity, or morphologic structure are discussed. The processes of hydrolytic destruction and esterification of starting materials during their mercerization by this non-traditional agent at 20 °C and 0 °C are quantitatively characterized. In the case of mercerization of wood microcrystalline cellulose at 20 °C a decrystallizing effect due to side reactions of partial nitration is noted.     

Thermal magnetic investigation of the decomposition of NixMn1−xC2O4·2H2O

The systems Ni_xMn_1?xC₂O₄·2H₂O (x = 0.11, 0.34) are characterized by XRD, SEM, TG/DTA, EGA-MS and magnetic measurements. The last confirmed that the studied samples are real solid solutions. The SEM reveals that the morphology depends on both the excess of C₂O₄^2? and the initial ratio Ni/Mn. The thermal magnetic investigations (in situ) show that: (i) the presence of Ni in Ni_xMn_1?xC₂O₄·2H₂O leads to decreasing in the decomposition temperature in regard to that of the manganese oxalate; (ii) upon increasing the Ni content the temperature of decomposition (in air) is growing up; (iii) the presence of Ni stabilizes the manganese with respect to oxidation, in spite of the occurring process of decomposition.     

‘Intelligent’ alarm detector of gas leaks

Three types of tin oxide gas sensors have been developed and a gas-detecting apparatus using the developed sensors has been manufactured. This apparatus has the ability to identify the type of leaking gas out of isobutane, ethanol, hydrogen and carbon monoxide. It can also be used for accumulating data as the terminal unit of a microcomputer. When city gas or carbon monoxide gas is leaking, a pulse is output from the apparatus to an electromagnetic valve which cuts off the path of the gas. The use of the apparatus and microcomputer composes a countermeasure system against gas leak accidents.     

Consequences of the ‘jacketed’ effect on mesomorphic and orientational properties of ‘side-on fixed’ liquid crystalline polymers

Abstract

The mesomorphic properties have been studied as a function of the degree of polymerization for certain ‘side-on fixed’ polyacrylates. A peculiar evolution of the clearing temperature, T _IN, as well as of the glass transition temperatures, T _g, revealed that beyond a certain backbone length, T _IN and T _g decrease as the main chain length increases. The nematic ‘jacketed’ structure of these polymers induces a more or less high anisotropy of the polymer backbone conformation in the nematic phase and this can counterbalance the usual effect of an increase in the degree of polymerization on the thermodynamical properties of these systems. This evolution allows us to explain the unusual diamagnetic anisotropy anomaly observed as a function of temperature for this type of polymer.     

Thermal Stability of α-Phycoerythrocyanin

The α-subunit of the phycobiliprotein, phycoerythrocyanin (α-PEC), from Mastigocladus laminosus shows photoreversible photochromism that is based on the Z ↔ E isomerization of the phycoviolobilin (PVB) chromophore. Thermal stability of the photochemistry and chromoprotein secondary structure have been studied by absorption and circular dichroism (CD) spectroscopy. Both photoisomers are stable and photoconvertible up to ∼ 70 °C. At T > 75 °C, photochemistry ceases because the E-state reverts rapidly thermally to the Z–state. The chromoprotein melts at 72 °C, the apoprotein already at 55 °C, indicating a considerable stabilization of the protein secondary structure by the chromophore.     

‘Apples’ and ‘oranges’: comparing the structural aspects of biomineral- and ice-interaction proteins

The title of this review describes structural comparisons of protein classes whose task is to identify and interact with biological solids (minerals and ice). To date, the following trends have been noted: (1) biomineral-interaction proteins typically adopt unfolded, open conformations, and, where mineral binding motifs have been identified, these sequences exhibit structural trends towards extended, random coil, or other unstable secondary structures; (2) ice-interaction proteins typically adopt folded structures, featuring stable secondary structure preferences (α-helix, β-sheet, β-helix, etc.) and stable, planar ice binding motifs that exploit hydrophobicity and van der Waals’ interactions for ice binding.