Fiber-optic Bragg gratings as magnetic field-insensitive strain sensors for the surveillance of cryogenic devices

While conventional electrical resistance strain gages show increasing cross-sensitivities to temperature and magnetic field with decreasing temperature down to liquid helium, it has been found that fiber-optic Bragg grating strain sensors show negligible thermo-optic and magneto-optic effects in cryogenic environments; therefore, they allow reliable strain measurements. These specific application advantages of optical fiber Bragg grating sensors at low temperatures, together with the electrical isolation and low electro-magnetic interference, low thermal conductivity and their multiplexing capability, make them attractive for structural health monitoring in cryogenic devices such as superconductive magnets. In this paper we present low temperature characteristics of fiber Bragg grating-based sensors and address application-based side effects such as induced birefringence.     

Phosphorous doped SOG as a pre-metal-dielectric for sub-50 nm technology nodes

The goal of this work is to find a substitute for chemically-vapour-deposited (CVD) Borophosphosilicate glass (BPSG), which is currently used as a pre-metal dielectric (PMD) for sub 50 nm. Two spin-on candidates are considered, out of which one contains four weight percent (wt.%) of phosphor. First, their material properties are discussed and then their integration challenges are presented. Particularly, issues like thermal budget, direct CMP capability and compatibility to wet-cleans are explored. Then the suitable candidate is tested electrically.     

Effects of the presence of probiotic bacteria in the aging medium on the surface roughness and chemical composition of two dental alloys

The aims of this study were: (a) to determine if the presence of probiotic bacteria in an aging medium, that is, artificial saliva in this study, has relevant effects on the surface roughness and the chemical composition of two main alloys used in dentistry (NiTi and stainless steel [SS]) and (b) in the case of NiTi, if these effects are influenced by the coating of the alloy (rhodium and titanium nitride). Atomic force microscopy and Raman spectroscopy were used to study the surface morphology and identify metal oxides formed on the surface of the alloys. Experiments demonstrated that the probiotic bacteria Lactobacillus reuteri can induce processes that alter some features of the surface such as roughness and chemical composition. The effect is dependent on the type of alloy and coating. The bacteria increased roughness in the case of uncoated NiTi more than saliva alone (pH = 4.8). Probiotic bacteria tend to decrease the corrosive influence of saliva on NiTi when the alloy is coated with rhodium or titanium nitride and this effect was also evidenced on SS. Raman spectroscopy confirmed that only SS samples are prone to oxidation processes, predominantly associated with exposure to saliva rather than probiotic bacteria.     

Steelmaking / U.S.A.

This is the fourth and final installment of Leo Reinartz’ summation of the steelmaking industry over the first one hundred years.     

Involvement of human intracisternal A-type retroviral particles in autoimmunity

Prior studies have linked retroviruses to various arthropathies and autoimmune diseases. Sj?gren's syndrome (SS), a systemic autoimmune disease, is characterized by aggressive infiltration of lymphocytes into the salivary and lacrimal glands, resulting in destruction of the glands and dry mouth and eyes (sicca syndrome). The infiltrating lymphocytes in SS may become overtly malignant, and thus, the incidence of lymphoma is greatly increased in SS patients. A human intracisternal A-type retroviral particle type I (HIAP-I) has been isolated from persons with SS. HIAP-I shares a limited number of antigenic epitopes with human immunodeficiency virus (HIV), but is distinguishable from HIV by morphological, physical, and biochemical criteria. A substantial majority of patients with SS or systemic lupus erythematosus (SLE) have serum antibodies to the proteins of this human retrovirus. Fewer than 3% of the normal blood donor population have antibodies to any HIAP-associated proteins. A second type of a human intracisternal A-type retrovirus, HIAP-II, was detected in a subset of patients with idiopathic CD4 lymphocytopenia (ICL), an AIDS-like immunodeficiency disease. Most HIAP-II positive ICL patients were also antinuclear antibody positive. Reviewed here are additional studies from several laboratories suggesting that HIAP or related viruses may be involved in SLE and other autoimmune conditions. Additionally, results of comprehensive surveys of autoimmune patients to determine seroreactivity to HIAP, and other human retroviruses, including HIV and human T-lymphotropic virus type I, are reported.     

Steelmaking / U.S.A.

Part III of a four-part series on the history of steelmaking in the US, describes furnace developments, improvements during the last few decades, and the contribution of the AIME.     

Iron species in fusion-cast,glassy-phase-containing corundum materials; EPR and susceptibility analyses

By means of EPR, susceptibility, EMP, light-microscopic, thermal and chemical methods the influence of production conditions and subsequent treatments on glassy-phase-containing corundum materials were studied. Melting of the system (Al₂O₃, SiO₂, Na₂O, Fe₃O₄) under reductive conditions leads to a reduction of Fe³⁺ species contained to Fe²⁺ and even to Fe⁰ clusters with ferromagnetic behaviour. Both species markedly influence the mechanical properties of the material by increase of their volumes in consequence of oxidation in subsequent thermal processes. The following model with regard to the localization of the iron species in the system ensues: Fe(III) in corundum, Fe₂O₃, Fe₃O₄ and (scarcely) in the glassy phase; Fe(II) in the glassy phase, FeAl₂O₄ (hercynite) as a solid solution in corundum, and Fe₃O₄; (Fe⁰) clusters in corundum. It is therefore not surprising that grinding of the compact material considerably alters the magnetic properties of the samples.     

Programmed field decay thermal field flow fractionation of polymers: a calibration method

The universal calibration procedure typical of thermal field flow fractionation (ThFFF) under constant thermal field operation was extended to thermal field programming (TFP) operation. The method requires knowledge of the following: (a) the programming function, which only depends on the thermal field decay function, (b) the physicochemical properties of the solvent, and (c) the calibration plot under varying channel cold wall temperatures (T(c)). Two field flow fractionation field programming conditions, with either a constant or a variable in time carrier flow velocity, are exploited. The method is based on determination, for each retention time position, of the average lambda retention value typical of TFP ThFFF. This parameter is then used to obtain the calibration plot (i.e., the molecular weight of the species as a function of the retention time position) by using the programming function and the calibration plot under varying T(c) values. The procedure approximation errors are also derived as a function of the programming type and solute-solvent system. To properly test the procedure, the calibration plot for the system constituted by polystyrene (PS) in cis-trans Decalin was determined, under varying conditions T(c) and thermal gradients, by using a set of monodisperse PS standards of different molecular weights (M). The procedure was first validated by simulation under two typical cases of TFP ThFFF operation. The approximation errors were found acceptable (in the worse cases, the accuracy in M prediction was 3%) and are in agreement with the theory. The procedure was then experimentally validated under varying programming decay function conditions. The reproducibility and accuracy of the M determination are both better than 2%.