Optimal orthogonalization processes

Two optimal orthogonalization processes are devised toorthogonalize,possibly approximately,the columns of a very large and possiblysparse matrix A∈C^n×k.Algorithmically the aim is,at each step,to optimallydecrease nonorthogonality of all the columns of A.One process relies on using translated small rank corrections.Another is a polynomial orthogonalization process forperforming the L?wdin orthogonalization.The steps rely on using iterative methods combined,preferably,with preconditioning which can have a dramatic effect on how fast thenonorthogonality decreases.The speed of orthogonalization depends on howbunched the singular values of A are,modulo the number of steps taken.These methods put the steps of the Gram-Schmidt orthogonalizationprocess into perspective regardingtheir(lack of)optimality.The constructions are entirely operatortheoretic and can be extended to infinite dimensional Hilbert spaces.     

Alpha decay of the new isotopes207, 208Ac

Two new neutron-deficient isotopes^207,208Ac have been produced in fusion reactions with 5.2–5.6 MeV/nucleon⁴⁰Ar ions on¹⁷⁵Lu and identified on the basis of genetic correlations. The fusion evaporation products were separated on-line using a gas-filled magnetic recoil separator. The alpha energy and half-life of²⁰⁸Ac were determined to be (7572±15) keV and (95 _?16 ⁺²⁴ ) ms, respectively. A new alpha line with a half-life of (25 _?5 ⁺⁹ ) ms and an energy of (7758±20) keV is assigned to the decay of an isomeric state in²⁰⁸Ac. Another new activity with a half-life of (22 _?9 ⁺⁴⁰ ) ms and an alpha energy of (7712±25) keV is assigned to²⁰⁷Ac.     

Alpha decay studies of neutron-deficient radium isotopes

Neutron-deficient isotopes of radium have been produced in the reactions³⁵Cl+¹⁷⁵Lu,⁴⁰Ar+^170,171Yb, and³⁶Ar+^170,171Yb and separated in-flight with a gas-filled recoil separator. The activities have been identified on the basis of correlated alpha decay chains. The alpha particle energy E_α and the half-life T_1/2 of an isomeric state of the new isotope,^203m Ra, have been determined to be (7615±20) keV and (33 _?10 ⁺²² ) ms, respectively. An assignment of another decay with E_α = (7577±20) keV and T_1/2=(1.1 _?0.5 ^+5.0 ) ms to^203g Ra is made on the basis of one observed three-decay chain. Tentative evidence for the production of the new isotope²⁰²Ra is also given. The values E_α = (7860±60) keV and T_1/2=(0.7 _?0.3 ^+3.3 ) ms were measured. Improved decay data have been obtained for²⁰⁴Ra. The results are E_α = (7484±10) keV and T_1/2=(59 _?9 ⁺¹² ) ms. Earlier findings concerning the decay of two states in²⁰⁵Ra and an isomer in²⁰⁷Ra have been confirmed. Approximate values for cross sections have been determined for²⁰²Ra, produced using the³⁶Ar+¹⁷⁰Yb reaction and for²⁰³Ra,²⁰⁴Ra, and²⁰⁵Ra using the³⁵Cl+¹⁷⁵Lu reaction. The results are 2 nb (²⁰²Ra), 4 nb (²⁰³Ra), 40 nb (²⁰⁴Ra), and 800 nb (²⁰⁵Ra).     

An NMR-Based Approach to the Measurement of High Log K HL Values at Low Ionic Strength. 31P NMR Study of 1,2-Diaminoethane-N,N,N′,N′-tetra(methylenephosphonic Acid) Protonation Equilibrium at pH > 12

A sequential NMR based approach is proposed for measurements of high log K values at low ionic strength. [³¹P] NMR technique is used to determine the protonation constants of 1,2-diaminoethane-N,N,N,N-tetra(methylenephosphonic acid) (EDTPH, H₈L) at 25°C in 0.1 mol-dm^–3 KNO₃ and at 37°C in 0.15 mol-dm^–3 NaCl at pH 11–14. For equilibrium L + H HL log K are found to be 13.3 (0.1) and 12.9 (0.1), respectively.     

Synthesis and spectroscopic characterization of a new family of Ni(4) spin clusters

A new family of tetranuclear Ni complexes [Ni(4)(ROH)(4)L(4)] (H(2)L = salicylidene-2-ethanolamine; R = Me (1) or Et (2)) has been synthesized and studied. Complexes 1 and 2 possess a [Ni(4)O(4)] core comprising a distorted cubane arrangement. Magnetic susceptibility and inelastic neutron scattering studies indicate a combination of ferromagnetic and antiferromagnetic pairwise exchange interactions between the four Ni(II) centers, resulting in an S = 4 spin ground state. Magnetization measurements reveal an easy-axis-type magnetic anisotropy with D approximately -0.93 cm(-)(1) for both complexes. Despite the large magnetic anisotropy, no slow relaxation of the magnetization is observed down to 40 mK. To determine the origin of the low-temperature magnetic behavior, the magnetic anisotropy of complex 1 was probed in detail using inelastic neutron scattering and frequency domain magnetic resonance spectroscopy. The spectroscopic studies confirm the easy-axis-type anisotropy and indicate strong transverse interactions. These lead to rapid quantum tunneling of the magnetization, explaining the unexpected absence of slow magnetization relaxation for complex 1.     

Determination of naphthodianthrones and phloroglucinols from Hypericum perforatum extracts by liquid chromatography/tandem mass spectrometry

Hypericum perforatum L. (St. John's Wort) has long been known as a medicinal plant, and has been used for the treatment of depression and neuralgic disorders. Its main active constituents are believed to be a naphthodianthrone, hypericin, and a phloroglucinol, hyperforin. A sensitive high performance liquid chromatography (HPLC)/electrospray tandem mass spectrometric method for fast simultaneous determination of six major naphthodianthrones and phloroglucinols of Hypericum perforatum extract has been developed. The method, based on multiple dissociation reaction monitoring (MRM), allows the analysis of hypericin, protohypericin, pseudohypericin, protopseudo-hypericin, hyperforin and adhyperforin from the extract in less than 5 min. Good linearity over the range 0.1-1000 ng/mL for hyperforin and 2-500 ng/mL for hypericin was observed. Intra-assay accuracy and precision varied from 2 to 19% within these ranges. Lower levels of quantitation for hyperforin were 0.5 ng/mL and 2 ng/mL for hypericin.     

Quantitation of perfluoroalkyl acids,parabens and cotinine from single low volume serum sample by validated analytical method

ABSTRACT

In this paper, we present the results of an analytical method that has been recently developed, validated and successfully applied in a biomonitoring approach. In the environmental pollutant studies it is desirable that the analytical method can determine multiple classes of compounds from a single, small volume sample. The presented analytical method with a simple sample pre-treatment allows the quantitation of 13 perfluoroalkyl acids (PFAAs), 6 parabens and cotinine (used as nicotine biomarker) from a single, small volume of 100 µL serum sample by liquid chromatography-triple quadrupole mass spectrometer (LC-MS/MS). The limits of quantitation (LOQ) for PFAAs, parabens and cotinine were 0.10–0.50, 0.20–0.80 and 0.10 ng/mL, respectively. Besides sensitivity the method has excellent trueness/accuracy and repeatability. The trueness of the method for the determination of PFAAs ranged from 95% to 106% and the repeatability (as RSD %) from 0.6% to 5.6%. The accuracy and RSD for parabens were 73–120% and 1.3–9.7%, respectively, and 100–106% and 1.3–3.5 % for cotinine. Biomonitoring data reveals the presence of several PFAAs and parabens in serum samples of Finnish population. The total concentrations for PFAAs and parabens were from 2.0 to 33 ng/mL and from <LOQ to 1100 ng/mL, respectively. Nearly all non-smokers had the serum cotinine concentration below 1.0 ng/mL, which can be suggested as the cut point for cotinine concentration to identify smoking.     

Wettability conversion on the liquid flame spray generated superhydrophobic TiO2 nanoparticle coating on paper and board by photocatalytic decomposition of spontaneously accumulated carbonaceous overlayer

Titanium dioxide (TiO₂) is a photoactive material with various interesting and useful properties. One of those is the perfect wettability of TiO₂ surface after ultraviolet (UV) illumination. Wettability of a solid surface plays an important role in the field of printing, coating, and adhesion among others. Here we report on a superhydrophobic and photoactive liquid flame spray (LFS) generated TiO₂ nanoparticle coating that can be applied on web-like materials such as paper and board in one-step roll-to-roll process. The LFS TiO₂ nanoparticle coated paper and board were superhydrophobic instantly after the coating procedure because of spontaneously accumulated carbonaceous overlayer on TiO₂, and thus there was no need for any type of separate hydrophobization treatment. The highly photoactive LFS TiO₂ nanoparticle coating could be converted steplessly from superhydrophobic to superhydrophilic by UV-illumination, and the coating gave strong response to natural daylight illumination even in the shade. The superhydrophobic LFS TiO₂ coated surface can be used as an intelligent substrate, where photo-generated hydrophilic patterns guide the fluid setting and figure formation. Our study reveals that the wettability changes on the LFS TiO₂ surface were primarily caused by the photocatalytic removal of the carbonaceous material from TiO₂ during the UV-illumination and spontaneous accumulation of the carbonaceous material on the surface of the metal oxide during storage in the dark. The latter mechanism was found to be a temperature activated process which could be significantly speeded up by heat treatment. If other mechanisms such as surface oxidization, increment of hydroxyl groups, or charge separation played a role in the wetting phenomena on TiO₂, their effect was rather secondary as the removal and accumulation of the carbonaceous material dominated the wettability changes on the surface. Our study gives valuable information on the complex issue of photo-induced wettability changes on TiO₂.     

Monitoring bisphenol A and estrogenic chemicals in thermal paper with yeast-based bioreporter assay

Bioluminescent Saccharomyces cerevisiae yeast-based bioreporters were used to monitor bisphenol A and other estrogenic chemicals in thermal paper samples collected mainly from Finland on two occasions in 2010/2011, and 2013. The bisphenol A-targeted (BPA-R) and the human oestrogen receptor (hERα) bioreporters were applied to analyse both non-treated and extracted paper samples. Bisphenol A was readily bioavailable to the yeast bioreporters on the non-treated paper samples without any pre-treatment. Detected concentrations ranged from a detection limit of 9–142 μg/g to over 20 mg/g of bisphenol A equivalents in the thermal papers. Low bisphenol A like activities were detected in many samples, and were considered to be caused by residual bisphenol A or other types of bisphenols, such as bisphenol S. Most of the thermal paper samples were toxic to the yeast bioreporters. The toxicity did not, however, depend on the bisphenol A concentration of the samples. The yeast bioreporters were demonstrated to be a robust and cost-efficient method to monitor thermal paper samples for their bisphenol A content and estrogenicity. Thermal paper was considered as a potential BPA source for both human exposure and environmental emission.