Chemical and physical characterization by EELS of strontium hexanoate reverse micelles and strontium carbonate nanophase produced during tribological experiments

Electron energy‐loss spectroscopy (EELS) in the analytical electron microscope has been used to characterize nanometre‐scale phases of overbased strontium 3,5‐dimethylhexanoate reverse micelles and the tribological film obtained during a friction test when the phases are used as lubricant additives. Accurate chemical, molecular and structural information on these materials are deduced by interpreting the EELS near‐edge structure. This approach allows confirmation of the composite structure of the micelles, which contain a mineral core and amorphous strontium carbonate surrounded by an organic shell. It also allows identification of the chemical composition and physical structure of the tribological film as an assembly of pure strontium carbonate microcrystals, i.e. strontianite, distributed in an amorphous intergranular phase.     

The Effects of Cryogenic Storage on Human Dental Pulp Stem Cells

Dental pulp stem cells (DPSCs) are a type of easily accessible adult mesenchymal stem cell. Due to their ease of access, DPSCs show great promise in regenerative medicine. However, the tooth extractions from which DPSCs can be obtained are usually performed at a period of life when donors would have no therapeutic need of them. For this reason, it is imperative that successful stem cell storage techniques are employed so that these cells remain viable for future use. Any such techniques must result in high post-thaw stem cell recovery without compromising stemness, proliferation, or multipotency. Uncontrolled-rate freezing is not a technically or financially demanding technique compared to expensive and laborious controlled-rate freezing techniques. This study was aimed at observing the effect of uncontrolled-rate freezing on DPSCs stored for 6 and 12 months. Dimethyl sulfoxide at a concentration of 10% was used as a cryoprotective agent. Various features such as shape, proliferation capacity, phenotype, and multipotency were studied after DPSC thawing. The DPSCs did not compromise their stemness, viability, proliferation, or differentiating capabilities, even after one year of cryopreservation at −80 °C. After thawing, they retained their stemness markers and low-level expression of hematopoietic markers. We observed a size reduction in recovery DPSCs after one year of storage. This observation indicates that DPSCs can be successfully used in potential clinical applications, even after a year of uncontrolled cryopreservation.     

Development of a transparent hydrorepellent modified SiO2 coatings for glazed sanitarywares

The formulation of innovative transparent hydrorepellent coatings is strongly motivated in order to satisfy the market request and necessity to improve the cleanability of the sanitarywares. A lot of attention is devoted to the use of cheap precursors, low temperature synthesis process and industrial scalability potentiality. In this framework, in the present paper the set-up of the deposition of modified SiO₂ coatings on glazed ceramic supports by spraying technique was reported. Several solutions were formulated using as precursor tetraethylorthosilicate (TEOS) and co-precursor methyltriethoxysilane (MTES) in different molar ratios (i.e. 50:50, 25:75, 75:25), in suitable solvents and mixture of solvents (i.e. H₂O, ethanol). The influence of the process parameters (i.e. precursors ratio, solvents, catalyser, annealing temperature) on the properties of the produced coatings was deeply investigated by means of scanning electron microscopy (SEM), simultaneous thermogravimetric and differential analyses (TG–DTA), infrared spectroscopy (FT-IR), X-Ray diffraction (XRD) and Vickers microhardness. Their hydrophobic behaviour was tested by the measurements of the static water contact angles and the chemical and stain resistance by the conformity to some tests of the standard UNI 4543. The obtained coatings were amorphous, homogeneous, uniform, thin (average thickness 300 nm), crack-free, leading to an improved hardness value of the glazed ceramic support (4.47 GPa vs 3.68 GPa for the coated and uncoated substrates, respectively), and allowed to improve both the hydrophobic behaviour and the chemical and stains resistance of the glazed sanitaryware supports, on the basis of the standard UNI 4543. The best hydrophobic performances were revealed in the case of coatings prepared starting from acidic catalysis derived precursor solutions. Moreover, the highest water contact angle values were detected for lower temperatures annealing, due to the methyl groups preservation, in agreement with the FT-IR and TG–DTA findings.     

Nanodiamonds for In Vivo Applications

Due to their unique optical properties, diamonds are the most valued gemstones. However, beyond the sparkle, diamonds have a number of unique properties. Their extreme hardness gives them outstanding performance as abrasives and cutting tools. Similar to many materials, their nanometer‐sized form has yet other unique properties. Nanodiamonds are very inert but still can be functionalized on the surface. Additionally, they can be made in very small sizes and a narrow size distribution. Nanodiamonds can also host very stable fluorescent defects. Since they are protected in the crystal lattice, they never bleach. These defects can also be utilized for nanoscale sensing since they change their optical properties, for example, based on temperature or magnetic fields in their surroundings. In this Review, in vivo applications are focused upon. To this end, how different diamond materials are made and how this affects their properties are discussed first. Next, in vivo biocompatibility studies are reviewed. Finally, the reader is introduced to in vivo applications of diamonds. These include drug delivery, aiding radiology, labeling, and use in cosmetics. The field is critically reviewed and a perspective on future developments is provided.     

Expression of extracellular matrix metalloproteinase inducer and matrix metalloproteinases during mouse embryonic development

Mouse embryo implantation is a highly invasive and controlled process that involves remodeling and degradation of the extracellular matrix of the uterus. Matrix metalloproteinases (MMPs) are the main proteinases facilitating this process. Extracellular matrix metalloproteinase inducer (EMMPRIN) can stimulate the production of MMPs and is required for successful implantation in the mouse. The aims of the present study were to examine the expression profiles of mRNA and proteins for EMMPRIN and MMPs in the developing mouse embryo in vitro, and to study whether EMMPRIN protein induces the production of MMPs by mouse blastocysts. EMMPRIN mRNA, detected by RT-PCR, was present at all stages of embryo development from the one-cell to the blastocyst outgrowth. EMMPRIN protein, observed by confocal microscopy, was present on the cell surface at the same stages of development as was the mRNA. Of seven MMPs studied, murine collagenase-like A (Mcol-A), murine collagenase-like B (Mcol-B) and gelatinase A (MMP-2) mRNAs were detected only in blastocyst outgrowths by RT-PCR. Gelatinase B (MMP-9) mRNA was detected both in expanded blastocysts and blastocyst outgrowths. MMP-2 and -9 proteins were detected in the cytoplasm of outgrowing trophoblast cells. Collagenase-2 (MMP-8), collagenase-3 (MMP-13), or stromelysin-1 (MMP-3) mRNAs were not present at any stage of pre- or peri-implantation mouse embryo development. Quantitative RT-PCR analyses showed that recombinant EMMPRIN protein did not stimulate MMP-2 or -9 expression by mouse blastocyst outgrowths. These data suggest that EMMPRIN may regulate physiological functions other than MMP production by mouse embryos during implantation.     

Cationic catalysis and hidden negative differential resistance in reduction of radical anion of nitrobenzene

Well-known reduction of nitrobenzene in acetonitrile yields an anion radical, which is further reduced at more negative potentials. The reduction of anion radical is strongly influenced by the nature of tetraalkylammonium salts (tetramethyl- to tetraheptylammonium) used as supporting electrolytes. At low concentration of tetrahexylammonium hexafluorophosphate the anion radical reduction occurs at extremely negative potential, however, traces of alkali metal cations yield a remarkable acceleration effect. At potentials where alkali metal cations are reduced the acceleration ceases. As a result the current-potential curves show negative or hidden negative slope. Electrochemical impedance spectroscopy sensitively indicates the presence of the negative differential resistance (NDR) or the hidden negative differential resistance (HNDR). Oscillatory behavior based on this type of cationic catalysis is currently under investigation.     

Kynurenine/Tryptophan Ratio as a Potential Blood-Based Biomarker in Non-Small Cell Lung Cancer

The enzyme indoleamine 2,3-dioxygenase 1 (IDO1) degrade tryptophan (Trp) into kynurenine (Kyn) at the initial step of an enzymatic pathway affecting T cell proliferation. IDO1 is highly expressed in various cancer types and associated with poor prognosis. Nevertheless, the serum Kyn/Trp concentration ratio has been suggested as a marker of cancer-associated immune suppression. We measured Kyn and Trp in blood samples of a wide cohort of non-small-cell lung cancer (NSCLC) patients, before they underwent surgery, and analyzed possible correlations of the Kyn/Trp ratio with either IDO1 expression or clinical–pathological parameters. Low Kyn/Trp significantly correlated with low IDO1 expression and never-smoker patients; while high Kyn/Trp was significantly associated with older (≥68 years) patients, advanced tumor stage, and squamous cell carcinoma (Sqcc), rather than the adenocarcinoma (Adc) histotype. Moreover, high Kyn/Trp was associated, among the Adc group, with higher tumor stages (II and III), and, among the Sqcc group, with a high density of tumor-infiltrating lymphocytes. A trend correlating the high Kyn/Trp ratio with the probability of recurrences from NSCLC was also found. In conclusion, high serum Kyn/Trp ratio, associated with clinical and histopathological parameters, may serve as a serum biomarker to optimize risk stratification and therapy of NSCLC patients.     

Rapid Models for Predicting the Low‐Temperature Behavior of Diesel

The cold filtration plugging point (CFPP) is the method most commonly applied to characterize the low‐temperature behavior of diesel and its components. However, this method is time‐consuming and does not have good repeatability, especially for samples with very low CFPP values like kerosene, light cycle oil, etc. Three new models for CFPP prediction were developed and compared: a combined density and distillation curve, differential scanning calorimetry, and near‐infrared. A set of 133 samples of diesel components were used to create the models, containing streams from different sources and levels of treatment. A further 28 diesel samples were used to validate and compare the models. All three models not only were faster than the standard method but also were found to be in good agreement with CFPP values. Each model has its own particular advantages suiting it to a particular type of diesel sample and stage of the diesel production process.     

Basic study of ceramic lithium strontium borates as thermal neutron scintillators

A special group of luminescence materials are scintillators for thermal neutron detection. Due to the properties of neutrons (contrary to e.g. electrons or gamma photons), a different approach has to be utilized—the high content of atoms with the sufficient absorption cross-section toward neutrons and lower material density are needed. This work pursues a basic study of LiSrBO₃ and LiSr₄(BO₃)₃ doped with cerium or europium—materials promising as thermal neutron scintillators. These borates exhibit promising properties such as the high content of lithium and boron, suitable density, and proper environment for luminescent ions. Radioluminescence of these ceramic borates doped with cerium and europium was examined and promising samples were further characterized by photoluminescence spectroscopy and radioluminescence and photoluminescence kinetics measurement. The radioluminescence study of these borates is published for the first time. Cerium-doped borates, in particular, exhibit a very promising response to an X-ray excitation.