RbEu(MoO4)2 is synthesized by the two-step solid state reaction method. The crystal structure of RbEu(MoO4)2 is defined by Rietveld analysis in space group Pbcn with cell parameters a = 5.13502(5), ...b = 18.8581(2) and c = 8.12849(7) Å, V = 787.13(1) Å3, Z = 4 (RB = 0.86%). This molybdate possesses its phase transition at 817 K and melts at 1250 K. The Raman spectra were measured with the excitation at λ = 1064 and 514.5 nm. The photoluminescence spectrum is evaluated under the excitation at 514.5 nm. The absolute domination of hypersensitive 5D0→7F2 transition is observed. The ultranarrow 5D0→7F0 transition in RbEu(MoO4)2 is positioned at 580.2 nm being 0.2 nm blue shifted, with respect to that in Eu2(MoO4)3.
•RbEu(MoO4)2 is synthesized by the two-step solid state reaction method.•The crystal structure of RbEu(MoO4)2 is defined by Rietveld analysis in space group Pbcn.•The absolute domination of hypersensitive 5D0.→7F2 transition is observed.
The solid-state chemistry of drugs has seen growing importance in the pharmaceutical industry for the development of useful API (active pharmaceutical ingredients) of drugs and stable dosage forms. ...The stability of drugs in various solid dosage forms is an important issue because solid dosage forms are the most common pharmaceutical formulation in clinical use. In solid-state stability studies of drugs, an ideal accelerated method must not only be selected by different complicated methods, but must also detect the formation of degraded product. In this review article, an analytical technique combining differential scanning calorimetry and Fourier-transform infrared (DSC–FTIR) microspectroscopy simulates the accelerated stability test, and simultaneously detects the decomposed products in real time. The pharmaceutical dipeptides aspartame hemihydrate, lisinopril dihydrate, and enalapril maleate either with or without Eudragit E were used as testing examples. This one-step simultaneous DSC–FTIR technique for real-time detection of diketopiperazine (DKP) directly evidenced the dehydration process and DKP formation as an impurity common in pharmaceutical dipeptides. DKP formation in various dipeptides determined by different analytical methods had been collected and compiled. Although many analytical methods have been applied, the combined DSC–FTIR technique is an easy and fast analytical method which not only can simulate the accelerated drug stability testing but also at the same time enable to explore phase transformation as well as degradation due to thermal-related reactions.
This technique offers quick and proper interpretations.
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A series of segmental polyurethane organic inorganic hybrids with polyhedral oligomeric silsesquioxanes (POSS) incorporated along the chain contour on the hard segments is irradiated by γ radiation ...at doses up to 100 kGy. The effects of this treatment on the morphology of the materials and the low temperature stability to oxidation are assessed complementary by non-isothermal and isothermal chemiluminescence experiments as well as with differential scanning calorimetry. From the methodological point of view, it was found that both physical and chemical processes have a footprint on both methods, but the physical ones manifest themselves more intensely in the thermal method, whereas chemical ones in chemiluminescence. Due to γ-exposure the onset oxidation temperatures decrease by several degrees, but POSS seems to protect the material to some extent. γ-Irradiation damage has also a negative effect on the development of phase separation, which is further enhanced by the presence of POSS. The crystallinity of the soft segments in the matrix is completely suppressed by irradiation, however, even a small amount of POSS preserves the phenomenon.
•Physical events in polyurethanes have a small but observable CL footprint.•γ−irradiation makes material more vulnerable to thermal oxidation.•POSS protects to some extent from the effects of irradiation.
This paper investigates the finite-time adaptive fuzzy control problem for a class of multi-input and multi-output (MIMO) nonlinear nonstrict feedback systems. During the control design process, ...fuzzy logic systems (FLSs) are utilized to approximate the unknown nonlinear functions, and fuzzy state observer is constructed to estimate the unmeasured states. By combining adaptive backstepping with the dynamic surface control (DSC) technique, a finite-time fuzzy adaptive control scheme is presented to overcome the "explosion of complexity" problem. The stability of the close-loop systems can be proved based on the finite-time Lyapunov stability theory. The presented control scheme demonstrates that the closed-loop systems are semiglobal practical finite-time stability, and tracking errors converge to a small neighborhood of the origin in a finite time. Finally, two simulation examples are provided to show the effectiveness of the presented control method.
In the past years, the use of biomass has significantly increased and, therefore, so has the number of accidents related to its storage, transport, and use. To prevent these accidents, it is ...essential to properly know their flammability and explosion characteristics so their behaviour can be addressed as a first stop for preventing accidents. The present work studies the inertization with solid inerts of biomass layers and clouds (biomass powder suspended in air) as a possible solution to reduce their ignition tendency. To do so, two biomass samples were studied: wood pellets and dried sewage sludge; mixed with two different inert materials: recycled glass and sodium bicarbonate. In particular, the inert materials were mixed with biomass at three different concentrations (30%, 50% and 70%) and the ignition of the mixtures was studied, determining the minimum ignition temperature of layer and cloud (MITL and MITC) for each mixture, and detecting the needed concentration for avoiding the ignition. Additionally, samples were tested using TGA and DSC techniques to analyse their thermal behaviour and to determine the influence that the inert material has in the energetic power of the biofuel.
Different behaviours were observed depending on the different inert materials, showing that not only the amount of inert added is important but also its physico-chemical properties. If the results for a layer and a cloud are compared, it was noticed that inertization effect differs between biomass and test. Regarding TGA and DSC results, it was concluded that smaller percentages of inert material should be considered, as they substantially modify the energetic value.
•Inertization showed differences when testing different biomasses but also when addressing MITc and MITL.•When igniting the cloud, the heat transfer mechanisms are more evenly distributed.•Recycled glass provided a better inertization in MITc than sodium bicarbonate.•Physico-chemical properties of the inert materials played a significant role.
The effects of palladium doping on the catalytic activity of La0.6Sr0.4Co0.2Fe0.8O3−δ(LSCF) cathodes are investigated by comparing the performance of La0.6Sr0.4Co0.2Fe0.8−xPdxO3−δ (LSCFPd) cathodes ...with different doping content and LSCF cathodes. The electrochemical results show that Pd doping decreases the polarization resistance and promotes the catalytic activity of LSCF cathodes. This promotion becomes greater with the increase of Pd doping content, which is also reflected by electrical conductivity relaxation (ECR) measurement results because the oxygen surface exchange coefficient of LSCFPd is improved by Pd doping. According to the in-situ high temperature XRD and TG-DSC results, perovskite LSCFPd materials are stable at temperature below 700 °C, and some Pd species are segregated during heating process.
•The effects of Pd doping on the catalytic activity of La0.6Sr0.4Co0.2Fe0.8O3−δ cathodes are investigated.•The stability of La0.6Sr0.4Co0.2Fe0.8−xPdxO3−δ perovskite materials was studied by HT-XRD and TG-DSC.•Some Pd species decompose to Pd metal at temperature above 800 °C.
The mechanical and thermal characteristics composites reinforced with E-glass fibre were examined in the current study. The mechanical stirring technique followed by the hand layup method was used to ...make composites loaded with different weight percentages of nanographene and a layer of e-glass. Nano-composite is made up of three different compositions by adjusting the weight percentages of each nanomaterial by 1%, 2%, and 3%. The generated nanocomposites' mechanical characteristics, including flexural strength, tensile strength, TGA, DTA, DSC, and hardness, were investigated and compared on a varying of nanofillers. The results showed that, when compared to neatly stacked composites, the introduction of nanographene (NG) composites can be a successful strategy in terms of mechanical qualities. Results are presented after examination of the experimental values of 1, 2, and 3 wt% of nanographene in the E-glass fabric reinforced composite. Additionally, it was found that adding nanomaterials the mechanical and thermal properties of nanographene to decrease after reaching their optimum weight percentage.
•A new methodology shows amylose fine structure influences pasting & gelatinization.•Peak and trough viscosities are increased by short and medium amylose chains.•Peak, trough & setback viscosities ...are suppressed by long amylose chains.•Molecular mechanisms are put forward to explain these new observations.
Starch molecular fine structure can have significant effects on pasting and thermal properties of rice flour. This study investigates the mechanistic explanation of these effects, by obtaining data for rice flour with different starch fine structures. Starch structural parameters for both amylose and amylopectin were obtained using size-exclusion chromatography (SEC, a type of gel-permeation chromatography, GPC), and the data fitted with methodologies (one of which is new) based on the underlying biosynthetic processes. It is found that the setback viscosity of rice starch measured by the rapid viscosity analyzer (RVA) depends not only on amylose content but also on the amount of long amylose chains and the size of whole amylopectin molecules. Conversely, long amylose chains and large amylopectin molecules are found to be responsible for the lower peak and trough viscosities. Other results for the effects of amylopectin chains are consistent with the literature. Mechanistic explanations for all observations are put forward. The novel findings about the influence of the distribution of amylose chain lengths and whole amylopectin size, in addition to amylose content alone, can provide guidance for rice breeders and food scientists in the selection of rices with improved functional properties.
Protein folding/unfolding processes involve a large number of weak, non-covalent interactions and are more appropriately described in terms of the movement of a point representing protein ...conformation in a plot of internal free energy versus conformational degrees of freedom. While these energy landscapes have an astronomically large number of dimensions, it has been shown that many relevant aspects of protein folding can be understood in terms of their projections onto a few relevant coordinates. Remarkably, such low-dimensional free energy surfaces can be obtained from experimental DSC data using suitable analytical models. Here, we describe the experimental procedures to be used to obtain the high-quality DSC data that are required for free-energy surface analysis.
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