Nanocomposite phase change materials based on NaCl–CaCl2 and mesoporous silica

The synthesis of phase change materials based on NaCl–CaCl₂ molten salt mixture and mesoporous silica was investigated. The influence of mesoporous silica porosity and salt concentration on the thermal energy storage properties of the resulting materials is discussed. The nanocomposite samples were characterized by X-ray diffraction, differential scanning calorimetry, infrared spectroscopy, thermogravimetry, scanning electron microscopy and X-ray photoelectron spectroscopy. The mesoporous silica was found to act as a reactive matrix for the molten salts. Composite samples with up 95% wt. salt can be obtained and used as shape-stabilized phase change materials. The materials have heat of fusion values of up to 60.8 J g^?1 and specific heat capacity between 1.0 and 1.1 J g^?1 K^?1. The samples exhibit thermal stability up to 700 °C and can be used for high-temperature thermal energy storage through both latent and sensible heat storage mechanisms.

     

Searching for biomarkers of chronic obstructive pulmonary disease using proteomics: The current state

Detection of proteins which may be potential biomarkers of disorders represents a big step forward in understanding the molecular mechanisms that underlie pathological processes. In this context proteomics plays the important role of opening a path for the identification of molecular signatures that can potentially assist in early diagnosis of several clinical disturbances. Aim of this report is to provide an overview of the wide variety of proteomic strategies that have been applied to the investigation of chronic obstructive pulmonary disease (COPD), a severe disorder that causes an irreversible damage to the lungs and for which there is no cure yet. The results in this area published over the past decade show that proteomics indeed has the ability of monitoring alterations in expression profiles of proteins from fluids/tissues of patients affected by COPD and healthy controls. However, these data also suggest that proteomics, while being an attractive tool for the identification of novel pathological mediators of COPD, remains a technique mainly generated and developed in research laboratories. Great efforts dedicated to the validation of these biological signatures will result in the proof of their clinical utility.     

Speciation analysis of chromium in water samples using nanometer zirconium dioxide and direct ultrasonic slurry sampling with electrothermal atomic absorption spectrometry

A new analytical procedure for the determination of chromium Cr(III) and Cr(VI) species in different water samples was developed. The method involves solid-phase extraction (SPE), direct ultrasonic slurry sampling (DUSSS), and subsequent electrothermal atomic absorption spectrometry (ETAAS). The nanometer-sized zirconium dioxide (ZrO₂) was used as the sorbent material. The optimal conditions for the proposed solid phase extraction were: 50 mg ZrO₂, 20 min extraction time, pH 2.5 for Cr(VI) and pH 8.0 for Cr(III) and for the ETAAS measurement: 1500°C pyrolysis and 2300°C atomisation temperatures, 1.5 g L^?1 Mg(NO₃)₂ as matrix modifier. The samples were sonicated directly in the autosampler cup, using an ultrasonic probe at 20% power setting for 10 seconds prior to injection into the graphite tube with ?vov platform. In this way, all drawbacks due to the elution procedure were eliminated. The limit of detection and limit of quantification for Cr(III) obtained under optimised conditions were 0.48 μg L^?1, and 1.61 μg L^?1, respectively, and for Cr(VI) 0.27 μg L^?1 and 0.90 μg L^?1. The pre-concentration factors attained for both the species were 25. The effects of alkaline, alkaline earth and some metal ions and some anions were also examined. The relative standard deviation estimated from six replicate measurements at a concentration of 0.4 μg L^?1 for both Cr(III) and Cr(VI) with a pre-concentration factor of 25 was 2.96% and 4.06%, respectively. The accuracy of the method was confirmed by analysis of the standard reference material SRM 1643e “Trace Elements in Water?. The proposed technique is simple, sensitive, environmentally friendly, and the risk of contamination is low. Hence, it was successfully applied to spiked synthetic and real water samples with recoveries ranging from 91.3% to 109.2%     

Studies on molten bath and aluminium contamination with ceramic anodes corrosion products

Two types of tin oxide ceramic anodes with 3 different bulk densities are prepared and tested in a laboratory aluminium reduction cell. During normal electrolysis, the regular chemical dissolution process of anode material should be controlled by mass–transport and subsequent reduction of the corrosion products into the cathode metal. The content of Sn species from each experimental anode in the electrolyte reaches stable values and does not contribute to the time dependent corrosion. Their concentration in metal becomes linear with time, providing that the concentration in the electrolyte remains constant. The mass transport anode dissolution mechanism is experimentally confirmed and it becomes evident that the dissolution rate is largely dependent by the conditions at the cathode, which has a hundred times lower rate factor. The smallest aluminium contamination (under 0.2 wt %) and corrosion rate (under 1 cm/year) were obtained by testing the tin oxide anode, with Recipe 2 (2) – 96% SnO₂+2%Sb₂O₃+2%CuO by our own sintering procedure and with bulk densities bigger than 6.5 g⋅cm⁻³ prepared. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Study of the Human Body Vibrations for the Seated Vehicle Driver

The paper presents some aspects about the dynamic response of the human body subjected to the vertical vibration in the travel inside the auto vehicle. There is a model presented in the specialized literature. This is transformed for the given study because was necessary to realize the vertical vibration along the human body. There are two different studies: using a linear lumped parameter systems seat - human body model; using a nonlinear lumped parameter systems seat-human body model. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Urea-Formaldehyde Microcapsules Containing an Epoxy Resin: Influence of Reaction Parameters on the Encapsulation Yield

In this work urea-formaldehyde microcapsules containing an epoxy resin are prepared by in situ polymerization of monomers in an oil-in-water emulsion. Scanning electronic microscopy (SEM) was performed to investigate on microcapsule size and surface morphology. Calorimetric and spectroscopic analyses were carried out with the aim of evaluate the encapsulation yield and the shell features. Factors determining the microencapsulability of the core material were described. In particular, our interest was devoted to a better understanding of the influence of the reaction parameters on the microcapsule properties. It was found that the encapsulation yield as well as the extent of urea-formaldehyde polymerization depends on the reaction temperature and the stirring speed.     

Dissociation Energy Computations for Saline Bonds Implied in Interactions Mediated by Peptidoglicans

Summary: Dissociation energy and hydration energy calculations, in water solution, are presented for saline bonds mediated by Ca²⁺ and Mg²⁺ ions with Brőnstedt type bases ( COO ,  OSO₃ ,  OH). A computationally intensive method, Polarisable Continuum Model (PCM) using 6-31G^* basis set, was applied. Hydration energies were computed by various methods, as well as dissociation energies of some L₂M complexes. L₂Ca complexes result as more stable against dissociation than L₂Mg complexes. Hydration energy calculation results, for some of the methods, here used, seem rather reliable as compared to experimental results.     

Carbonic anhydrase inhibitors: X-ray and molecular modeling study for the interaction of a fluorescent antitumor sulfonamide with isozyme II and IX

The X-ray crystal structure of the fluorescent antitumor sulfonamide carbonic anhydrase (CA, EC, 4.2.1.1) inhibitor (4-sulfamoylphenylethyl)thioureido fluorescein (1) in complex with the cytosolic isoform hCA II is reported, together with a modeling study of the adduct of 1 with the tumor-associated isoform hCA IX. Its binding to hCA II is similar to that of other benzesulfonamides, with the ionized sulfonamide coordinated to the Zn2+ ion within the enzyme active site, and also participating in a network of hydrogen bonds with residues Thr199 and Glu106. The scaffold of 1 did not establish polar interactions within the enzyme active site but made hydrophobic contacts (<4.5 A) with Gln92, Val121, Phe131, Val135, Leu198, Thr199, Thr200, and Pro202. The substituted 3-carboxy-amino-phenyl functionality was at van der Waals distance from Phe131, Gly132, and Val135. The bulky tricyclic fluorescein moiety was located at the rim of the active site, on the protein surface, and strongly interacted with the alpha-helix formed by residues Asp130-Val135. All these interactions were preserved in the hCA IX-1 adduct, but the carbonyl moiety of the fluorescein tail of 1 participates in a strong hydrogen bond with the guanidine moiety of Arg130, an amino acid characteristic of the hCA IX active site. This may account for the roughly 2 times higher affinity of 1 for hCA IX over hCA II and may explain why in vivo the compound specifically accumulates only in hypoxic tumors overexpressing CA IX and not in the normal tissues. The compound is in clinical studies as an imaging tool for acute hypoxic tumors.     

Highly enantioselective synthesis of tetrahydro-beta-carbolines and tetrahydro-gamma-carbolines via Pd-catalyzed intramolecular allylic alkylation

A novel Pd-catalyzed intramolecular allylic alkylation of indoles allows THBCs and THGCs to be effectively synthesized in high yields and excellent enantiomeric excesses (ee up to 97%).     

Tuning the structural and magnetic properties of thermally robust coordination polymers

Thermally robust materials of the M(5-X-pyrimidin-2-olate)2 type [M = Co, X = Cl (1(Cl)), X = Br (1(Br)), X = I (1(I)); M = Zn, X = Cl (2(Cl)), X = Br (2(Br)), X = I (2(I))] have been synthesized. Their X-ray powder diffraction structural characterization has revealed that they crystallize as I2d diamondoid frameworks, isomorphous to those of the pristine [M(pyrimidin-2-olate)2]n analogues (1(H), M = Co; 2(H), M = Zn). The magnetic measurements of the 1(X) series at magnetic fields of 100, 300, and 5000 Oe reveal a weak ferromagnetic ordering taking place below the Néel temperature (T(N) approximately 20 K), arising from spin canting phenomena of the antiferromagnetically coupled cobalt centers. Moreover, magnetic hysteresis studies carried out on the 1(X) series at 2 K reveal a strong dependence of both the coercive field H(coer) (2500, 1000, 775, and 500 Oe for 1(Br), 1(Cl), 1(I), and 1(H), respectively) and the remnant magnetization M(rem) (0.0501 mu(B) for 1(Br) and 1(Cl), 0.0457 mu(B) for 1(I), and 0.0358 mu(B) for 1(H)) on the 5-substituent of the pyrimidin-2-olates. The molecular alloys [Co(5-Y-pyrimidin-2-olate)2] (Y = Cl/Br, 1(Cl/Br)) and [Co(5-Y'-pyrimidin-2-olate)2] (Y' = Br/I, 1(Br/I)) have also been prepared and characterized, proving that they have intermediate properties. These materials combine interesting functional properties, such as chemical inertness, magnetism, photoluminescence, and (although weak) SHG activity.