Doped silicon and NIS junctions for bolometer applications

We discuss the performance, of a normal metal hot electron bolometer (NHEB) that we have measured at 0.3 K. We found that the noise equivalent power was limited by the amplifier noise. To improve the NHEB power response and to make it more robust and reliable we propose to substitute the normal metal with heavily doped silicon. The heavily doped silicon behaves like a metal with lower carrier concentration and has a smaller electron–phonon thermal coupling. We have fabricated superconductor-doped silicon-superconductor contacts (S-Sm-S) and we have used them as thermometers and coolers.     

Diphenylhydantoin affects glycosaminoglycans and collagen production by human fibroblasts from cleft palate patients

During embryonic development, the proper production of extracellular matrix molecules mediates morphogenetic processes involved in palatogenesis. In the present study, we investigated whether any differences exist in glycosaminoglycan (GAG) and collagen synthesis between palate fibroblasts from infants, with or without cleft palate, in two age ranges. Subsequently, the effects of diphenylhydantoin (PHT), a teratogen known to induce cleft palate in human and mammalian newborns, on extracellular matrix (ECM) production were studied. We found that cleft palate fibroblasts (CPFs) synthesize greater amounts of GAG and collagen than normal fibroblasts (NFs). CPFs produced less cellular hyaluronic acid (HA) and more sulphated GAG. HA was the principal GAG species in the medium, and its percentage was lower in one- to three-year-old CPFs. Cleft palate fibroblasts produced more extracellular chondroitin 4- and 6-sulphate (CS) and dermatan sulphate (DS). Associated with a higher production of sulphated GAG, we observed a higher synthesis of type III and type I collagen with a normal ratio of alpha2(I) to alpha1(I) chains. PHT treatment of NFs reduced collagen and GAG synthesis, with a marked effect on sulphated GAG. The drug changed collagen synthesis, whereas it did not affect GAG production in CPFs whose phenotype may already be impaired. These findings indicate that, in CPFs, modifications in the pattern of ECM components, which are most likely responsible for the anomalous development, persist in infants. In addition, NFs and CPFs with a different phenotype respond differently to PHT treatment.     

Remarkable Efficiency Improvement in the Preparation of Insoluble Polymer‐Bound (IPB) Enantioselective Catalytic Systems by the Use of Silicone Chemistry

The use of platinum‐catalyzed hydrosilylation chemistry of silicones greatly simplifies the preparation of bis‐oxazoline (box) ligands covalently bound to an insoluble polymeric support. The use of such immobilized chiral ligands in different copper‐catalyzed asymmetric transformations (carbonyl‐ene, Mukaiyama aldol and olefin cyclopropanation reactions) allows the attainment of high levels of enantioselectivity (91–99 % ee).     

Size-controlled synthesis and NMR characterization of mesitylene-vinylsiloxanes stabilized Pt nanoparticles in solution

Pt nanoclusters have been generated by reaction of Pt vapour and mesitylene vapour and the role of the mesitylene/platinum ratio and the Pt particle size has been evaluated, quenching the resulting mesitylene solvated Pt atoms with 1,3-divinyltetramethyldisiloxane (DVS) as additional ligand. The Pt particle sizes have been estimated on the basis of DOSY (Diffusion-Ordered SpectroscopY) analysis and information on their structure features have been obtained by combined use of 2D NMR techniques.     

Magnetic Imaging of Cyanide‐Bridged Co‐ordination Nanoparticles Grafted on FIB‐Patterned Si Substrates

Prussian blue CsNiCr nanoparticles are used to decorate selected portions of a Si substrate. For successful grafting to take place, the Si surface needs first to be chemically functionalized. Low‐dose focused ion beam patterning on uniformly functionalized surfaces selects those portions that will not participate in the grafting process. Step‐by‐step control is assured by atomic force and high‐resolution scanning electron microscopy, revealing a submonolayer distribution of the grafted nanoparticles. By novel scanning Hall‐probe microscopy, an in‐depth investigation of the magnetic response of the nanoparticles to varying temperature and applied magnetic field is provided. The magnetic images acquired suggest that low‐temperature canted ferromagnetism is found in the grafted nanoparticles, similar to what is observed in the equivalent bulk material.     

Identification and quantification of cholesterol oxidation products in canned tuna

Cholesterol oxidation in tuna canned in brine was studied. Gas chromatography-mass spectrometry was used for the detection of the seven major cholesterol oxidation products originating from both direct and indirect oxidation. The total amount of cholesterol oxidation products in the analyzed samples varied considerably, ranging between 40 and 350 μg/g lipids, with the exception of an anomalous sample, that reached a 1600 μg/g level. The lipid content ranged between 0.5 and 1 g/100 g wet product. As most samples did not exceed 100 μg/g lipids, it is possible to assume that the total content of cholesterol oxidation products can be kept below this value if good manufacturing conditions are used, together with a careful choice of the best tuna cuts. The application of principal component analysis to the detected variables confirmed that 7-ketocholesterol is a useful index of the whole oxidation process.     

Routine high-performance liquid chromatographic determination of free 7-ketocholesterol in some foods by two different analytical methods

Two methods for routine analysis of free 7-ketocholesterol (7-k) in foods by high-performance liquid chromatography (HPLC) were compared. The analyzed samples were egg noodles, biscuits prepared with eggs, sweet snacks, grated Parmesan cheeses, and some ingredients utilized in the food industry (whole-milk and whole-egg powder). The enrichment of cholesterol oxides was carried out by solid-phase separation of the total lipids with florisil and silica cartridges for methods A and B, respectively. The 7-k analyses were run in normal-phase HPLC for method A, and a reverse-phase process was used in method B. Identification of the 7-k peak was confirmed by gas chromatography/mass spectrometry analysis and peak purity checkvia spectral analysis with a diode array detector. The quantitation of 7-k was carried out with an internal standard for method A and with a calibration curve for method B. The limit of quantitation (LQ) was 3 × 10⁻⁹ g/injection; the limit of detection was ten times lower than the LQ for both methods. The two methods showed good recovery (99%) and good repeatability (coefficient of variation of 3.9 and 3.7% for methods A and B, respectively). These methods allow a fast, sensitive, and reliable determination of one cholesterol oxidation product, which is present at a high concentration level in the first stages of the oxidation process.