Application of classical versus bayesian statistical control charts to on-line radiological monitoring

False positive and false negative incidence rates of radiological monitoring data from classical and Bayesian statistical process control chart techniques are compared. The on-line monitoring for illicit radioactive material with no false positives or false negatives is the goal of homeland security monitoring, but is unrealistic. However, statistical fluctuations in the detector signal, short detection times, large source to detector distances, and shielding effects make distinguishing between a radiation source and natural background particularly difficult. Experimental time series data were collected using a 1″ × 1″ LaCl₃(Ce) based scintillation detector (Scionix, Orlando, FL) under various simulated conditions. Experimental parameters include radionuclide (gamma-ray) energy, activity, density thickness (source to detector distance and shielding), time, and temperature. All statistical algorithms were developed using MATLAB™. The Shewhart (3-σ) control chart and the cumulative sum (CUSUM) control chart are the classical procedures adopted, while the Bayesian technique is the Shiryayev–Roberts (S–R) control chart. The Shiryayev–Roberts method was the best method for controlling the number of false positive detects, followed by the CUSUM method. However, The Shiryayev–Roberts method, used without modification, resulted in one of the highest false negative incidence rates independent of the signal strength. Modification of The Shiryayev–Roberts statistical analysis method reduced the number of false negatives, but resulted in an increase in the false positive incidence rate.     

Vacancy Contents in MnZn Ferrites From TG Curves

Expressions for calculating the cation vacancy contents of MnZn ferrites from thermogravimetric curves are presented together with some experimental data. In a single-phase MnZn ferrite synthesized by conventional ceramic procedures, the O₂ evolution accompanying ferrite formation follows the formal equation. Mn²⁺ _σα Zn_σβ Fe³⁺ _2σ(1–γ) [V ]_{σ/4(1–2γ)} O₄ =σ'/σ Mn²⁺ _σ(α–2ϕ) Zn_σβ Fe²⁺ _2σθ Mn³⁺ _2σϕ Fe³⁺ _{2σ(1–γ–θ)} [V ]_{σ/4(1–2γ–3ϕ)} O₄ +σ'φ/2O₂ (g) where α and β denote the MnO and ZnO mole fractions in the primary mixture γ=α+β, θ and ϕ depend on the quantities of Fe²⁺ and Mn³⁺ formed, respectively, φ=θ–ϕ and σ'/σ is a function of the former parameters. Even though the relative amounts of Fe²⁺ /Fe³⁺ and Mn²⁺ /Mn³⁺ remain uncertain, the vacancy content [V ] of the ferrite can be determined because it depends on φ alone, which is related to the change in mass of the sample as the synthesis takes place through the equation φ=(1.5–γ) μ_β /μ_O2 (1–m _f /m _i ) Here, m _i and m _f are the masses of the sample before and after O₂ evolution, μ_B is the formula mass of the ferrite and μ_O2 is the O₂ molar mass. Practically vacancy-free single-phase MnZn ferrite samples were obtained by sintering in air at 1250°C and cooling in pure N₂ . This revised version was published online in July 2006 with corrections to the Cover Date.     

Monitoring analytical measurements in presence of two component measurement error

Control charts are increasingly adopted by laboratories for effective monitoring of analytical processes. Analytical methods are mostly subject to two types of measurement errors, i—additive and ii—multiplicative, or proportional, error. These errors have been combined in a single model, namely the two component error model (TCME) proposed by [1]. In this study we present a comparison among the performance of three widely used location control charts, i.e. Shewhart, CUSUM and EWMA charts in presence of TCME model. This study will help quality practitioners to choose an efficient chart for the monitoring of analytical measurements.     

Quasi-classical trajectory studies of the stereodynamics of the reaction O + HCl → ClO + H

The stereodynamics of the O + HCl → ClO + H reaction are investigated by quasi-classical trajectory (QCT) method. The calculations are carried out on the ground 1 ¹ A′ potential energy surface (PES). The orientation and alignments of the product rotational angular momentum for the title reaction are reported. The influence of collision energy on the product vector properties is also studied in the present work. Four (2π/σ)(dσ₀₀/dω _t ), (2π/σ)(dσ₂₀/dω _t ), (2π/σ)(dσ₂₂₊/dω _t ), and (2π / σ)(dσ₂₁₋/dω _t ), and have been calculated in the center of mass frame.     

Electronic absorption spectra of charge-transfer complexes and effects of substituents in radical cations

The effects of X substituents on the energies of charge-transfer bandshv _CT in electronic absorption spectra of charge-transfer complexes of π-, n-, or σ-donors (DX) with π- or σ-acceptors (A) as well as on the ionization potentialsI _D of individual DX molecules are described by the equationhv _CT(l _D)=a +bσ₁ +cσ _R ⁺ +dσ_α. When DX and A are fixed, the inductive (bσ₁), resonance (cσ _R ⁺ ), and polarization (dσ_α) contributions tohv _CT andI _D are virtually identical. The electronic structure of the D^.+X donor component of the compact [A^.−, D^.+X] radical-ionic pair in a solution is similar to that of the radical cation generated upon photoionization of the individual DX molecule in the gaseous phase. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1002–1006, June, 2000.     

Ionization potentials of non-metal monosulfides. Conjugation in radical cations containing Group IV elements

The first vertical ionization potentialsI(n_s) of 69 monosulfides XSY (X, Y=H, Hal, organic, or heteroorganic substituent) are related to the inductive σ_I resonance (σ _R ⁺ ) and polarizability (σ_α) constants of the substituents by dependences of theI(n_S)=a+bΣσ_I+bΣσ_R+bΣσ_α type. TheI(n_s) values are also affected by hyperconjugation which increases on going from XSH to XSY (Y≠H) compounds. The first calculations of the σ _R ⁺ parameters characterizing the conjugation of Si-, Ge-, Sn-, and Pb-containing substituents with the S^.+ radical cation center are reported. The reasons for weakening of resonance donor properties of heteroorganic substituents of the +M-type in the systems studied as compared to those of the same substituents in the corresponding aromatic radical cations are considered. Translated fromIzvestiya Akademii Nauk. Seriya Khmicheskaya, No. 1, pp. 25–31, January, 2000.     

Natural bond orbital analysis of some para-substituted N-nitrosoacetanilide biological molecules

Theoretical study of several para-substituted N-nitrosoacetanilide biological molecules has been performed using density functional B3LYP method with 6-31G(d,p) basis set. Geometries obtained from DFT calculation were used to perform natural bond orbital analysis. The p characters of two nitrogen natural hybrid orbital (NHO) σ _N3–N2 bond orbitals increase with increasing σ _p values of the para substituent group on the benzene, which results in a lengthening of the N₃–N₂ bond. The p characters of oxygen NHO σ _O1–N2 and nitrogen NHO σ _O1–N2 bond orbitals decrease with increasing σ _p values of the para substituent group on the benzene, which results in a shortening of the N₂=O₁ bond. It is also noted that decreased occupancy of the localized σ _N3–N2 orbital in the idealized Lewis structure, or increased occupancy of s_N3-N2^* \sigma_{\rm N3-N2}^{\ast} of the non-Lewis orbital, and their subsequent impact on molecular stability and geometry (bond lengths) are also related with the resulting p character of the corresponding nitrogen NHO of σ _N3–N2 bond orbital.     

Ionization potentials of non-metal monosulfides. Conjugation in radical cations containing Group IV elements

The first vertical ionization potentialsI(n_s) of 69 monosulfides XSY (X, Y=H, Hal, organic, or heteroorganic substituent) are related to the inductive σ_I resonance (σ _R ⁺ ) and polarizability (σ_α) constants of the substituents by dependences of theI(n_S)=a+bΣσ_I+bΣσ_R+bΣσ_α type. TheI(n_s) values are also affected by hyperconjugation which increases on going from XSH to XSY (Y≠H) compounds. The first calculations of the σ _R ⁺ parameters characterizing the conjugation of Si-, Ge-, Sn-, and Pb-containing substituents with the S^.+ radical cation center are reported. The reasons for weakening of resonance donor properties of heteroorganic substituents of the +M-type in the systems studied as compared to those of the same substituents in the corresponding aromatic radical cations are considered. Translated fromIzvestiya Akademii Nauk. Seriya Khmicheskaya, No. 1, pp. 25–31, January, 2000.     

Impedance studies on the 5-V cathode material,LiCoPO<Subscript>4</Subscript>

Olivine-structured LiCoPO₄ is synthesized by a Pechini-type polymer precursor method. The structure and the morphology of the compounds are studied by the Rietveld-refined X-ray diffraction, scanning electron microscopy, Brunauer, Emmett, and Teller surface area technique, infrared spectroscopy, and Raman spectroscopy techniques, respectively. The ionic conductivity (σ ionic), dielectric, and electric modulus properties of LiCoPO₄ are investigated on sintered pellets by impedance spectroscopy in the temperature range, 27–50 °C. The σ (ionic) values at 27 and 50 °C are 8.8 × 10⁻⁸ and 49 × 10⁻⁸ S cm⁻¹, respectively with an energy of activation (E _a) = 0.43 eV. The electric modulus studies suggest the presence of non-Debye type of relaxation. Preliminary charge–discharge cycling data are presented.     

First ionization potentials and conjugation in molecules of ethylene derivatives containing organoelemental substituents of Group IV elements

Unlike theE _HOMO energies, the first vertical ionization potentials (I ₁) of monosubstituted ethylenes dependen not only on both the inductive and resonance effects but also on the polarizability of the substituents, which can be characterized by the σ_α parameters. The σ _R ⁺ , σ _p ⁺ , and σ_α parameters for 12 silicon-, germanium-, and tin-containing groups were determined using the equations relating theI ₁ values and the σ_I, σ _R ⁺ , σ _p ⁺ and σ_α parameters of the substituents in the molecules of organic compounds. The conjugation of organoelemental substituents with the double bond is stronger than that with benzene ring; the σ _R ⁺ parameters in the ethylene and benzene series are related by a linear dependence. Translated fromIzvestiya Akademii Nauk Seriya Khimicheskaya, No. 9, pp. 1626–1631, September, 1997.     

The conjugation and effective charges of the atoms at the triple bond in germylacetylenes

The integrated extinction coefficients (A) of the C≡C stretching modes in the IR spectra of 12 germylacetylenes Me₃GeC≡CR are determined by the resonance interactions of substituents with the triple bond. TheA ^1/2 values change linearly with change in the difference between the effective π-electron charges on the atoms at the triple bond and σ⁰ _R constants of organic substituents R. The average value of the σ⁰ _R constant of the Me₃Ge substituent in the compounds studied is +0.06. The resonance acceptor effect of the Me₃Ge substituent toward the triple bond (d,π-conjugation) is stronger than the donor effect (σ,π-conjugation). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1569–1574, August, 1998.     

A new algorithm for the fixed-node quantum Monte Carlo method

A novel algorithm is proposed for the fixed-node quantum Monte Carlo (FNQMC) method.In contrast to previous procedures,its "guiding function" is not optimized prior to diffusion quantum Monte Carlo (DMC) computation but synchronistically in the diffusion process The new algorithm can not only save CPU time,but also make both of the optimization and diffusion carried out according to the same sampling fashion,reaching the goal to improve each other This new optimizing procedure converges super-linearly,and thus can accelerate the particle diffusion During the diffusion process,the node of the "guiding function" changes incessantly,which is conducible to reducing the "fixed-node error" The new algorithm has been used to calculate the total energies of states X3B1 and a1A1 of CH2 as well as π-X2B1 and λ-2A1 of NH2 The singlet-triplet energy splitting (λEsT) in CH2 and π energy splitting in NH2 obtained with this present method are (45 542±1.840) and (141.644±1.589) kJ/mol,respectively The calculated     

Specific adsorption of iodide-ion at liquid (Ga-In)-electrode of eutectic composition from aqueous solutions with constant ionic strength

The adsorption behavior of iodide-ion at liquid (Ga-In)-electrode in aqueous electrolyte solutions at 305 K is studied by the electrochemical impedance spectroscopy, differential capacitance, and cyclic voltammetry. The equivalent circuit describing the experimental data in the presence and in the absence of the I⁻ ion is a series connection of a resistance and a capacitance that is frequency-independent over a ∼500 Hz to 100 kHz range. The experimental data were obtained by the mixed electrolyte method in electrolyte solutions acidified with HClO₄ down to pH 3, with excess of surface-inactive ion ClO₄⁻ and constant ionic strength (0.1 M). The analysis resulted in the determination of the charge σ₁ of the I⁻ ion specifically adsorbed at the liquid (Ga-In)-electrode at the adsorbate maximal concentration: σ_I = 7.73 μC/cm² in the case of analysis at σ = const (at the zero charge potential) or σ_I = 7.50 μC/cm² in the case of analysis at E = const. These values are characteristic of rather strong specific adsorption. The values of σ_I of the studied anion were used in the calculations of different isotherms with the purpose of the adsorption parameters determination. The obtained results were compared with literature data determined on other metals in the presence of specifically adsorbable I⁻ ion.     

A Highly Sensitive Resonance Rayleigh Scattering Method for the Determination of Vitamin B1 with Gold Nanoparticles Probe

In weakly acidic buffer medium, vitamin B₁ (VB₁) interacts with gold nanoparticles to form a binding product, which resulted in a significant enhancement of resonance Rayleigh scattering (RRS) intensity and the appearance of a new RRS spectrum. The maximum RRS peak was at 368 nm, and there are three smaller scattering peaks that were at 284 nm, 440 nm and 495 nm, respectively. The enhanced RRS intensity (ΔI) was directly proportional to the concentration of VB₁ in the range of 0–2.8 × 10⁻⁷ mol L⁻¹. The method had high sensitivity and its detection limit (3σ) was 0.9 ng mL⁻¹. The optimum conditions and the influencing factors have been investigated. The method had good selectivity, which could be observed from the influence of coexisting substances. A sensitive, simple and fast RRS method for the determination of VB₁ with gold nanoparticle probe has been developed. In addition, the reasons for RRS enhancement were discussed.     

ESR studies of α-hydro p-substituted phenyl nitroxides and correlation analysis of their HFSC values

Well-resolved ESR spectra of a series of α-hydro p-substituted phenyl nitroxides were obtained in the fast ET reactions of p-substituted anilines with perfluoroacyl peroxides in F113 (CCl₂FCClF₂) solutions and one parameter (σ or σ^·) as well as dual-parameter (σ, σ^·) correlation analyses of their hyperfine splitting constants were conducted.     

Diatomic interactions in momentum space. The 1sσg and 2pσ u states of H 2 + system

The method of momentum electron density for interatomic interactions has been applied to the two lowest σ states of the H ₂ ⁺ system. For attractive (1sσ_g) and repulsive (2pσ _u ) interactions, the behaviour of momentum density and its effect on the stabilization energy of the system are examined quantitatively. The concept of contraction and expansion of the momentum density is shown to form an important guiding principle in this approach. The origin of covalent bonding is discussed based on the energy partitioning proposed previously.     

Electronic effects of Me3SiOCR2 substituents in acetylene derivatives

The σR⁰ and σ_p parameters of Me₃SiOCR₂ and HOCR₂ substituents at the triple bond were determined using the IR spectra of individual acetylene derivatives and their H-complexes. These parameters vary as the effective charge on the atoms of the C≡C fragment of terminal acetylenic alcohols and their trimethylsilyl ethers changes due to intermolecular interaction. The most reliable values of σR⁰ and σ_p parameters (−0.02 and −0.03, respectively) for the Me₃SiOCH₂ substituent were established; they indicate a sharp decrease in σ,π-conjugation of the Me₃SiOCH₂ substituent with the triple bond as compared to the Me₃SiCH₂ substituent. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1759–1762, September, 1998.     

Chemical effects on K and L shell production cross sections and transfer probabilities in Nb compounds

In this study, the chemical effects on σ_Ki (i = α, β), σ_Lα cross sections, K_β/K_α X-ray intensity ratios and vacancy transfer probabilities from K to L (η _KL) for pure Nb and Nb compounds were investigated. The samples were excited by 59.5 keV γ-rays from ²⁴¹Am and 5.96 keV photon energy from a ⁵⁵Fe annular radioactive sources. K and L X-rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. While it was observed that the chemical bonding had an effect on the σ_Kβ, σ_Lα cross sections and K_β/K_α X-ray intensity ratios for compounds, it was almost negligible for σ_Kα cross section because K_α transitions (2P_3/2,1/2→1S_1/2) occurred in inner shells. It is well known that interactions between central element atom and ligands come into existence in valence state, so outer energy levels are sensitive to the chemical environment. The experimental values of σ_Kα cross section and η _KL are in good agreement with theoretically calculated and other experimental values of pure niobium, but the experimental values of the σ_Kβ, σ_Lα cross sections and K_β/K_α X-ray intensity ratios have differences for some compounds because valence electrons have different bond distances and binding energies in different compounds.     

New one-step methods for the synthesis of the metallonium dication [Ru(η5-C5Me5)(η5:σ:σ-C5Me3(CH2)2]2+ and its heteroannular analog starting from decamethylruthenoceneand its heteroannular analog starting from decamethylruthenocene

The reaction of decamethylruthenocene with oleum or with an oleum—acid (CF₃SO₃H or CF₃CO₂H) mixture as well as UV photolysis of a Cp^* ₂Ru solution in CF₃SO₃H in the presence of a small amount of oleum afforded two metallonium dications,viz., [Ru(η⁵-C₅Me₅)(η⁵:σ:σ-C₅Me₃(CH₂)₂]²⁺ and [Ru(H₂)(η⁵:σ:-C₅Me₄CH₂)₂]²⁺. The structures of these dications were confirmed by the results of their alkaline hydrolysis and NMR spectra. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 517–522, March, 2000.     

A study on the electronic effect of <Emphasis Type="Italic">para</Emphasis> substituents in the aryloxy ring of the hydrazone ligands on the vanadium centre in a family of mixed-ligand [V<Superscript>V</Superscript>O(ONO)(OO)] complexes

[V^IVO(acac)₂] reacts with the methanolic solutions of tridentate dibasic ONO donor hydrazone ligands derived from the condensation of benzoyl hydrazine with either 2-hydroxyacetophenone (H₂L¹) or its para-substituted derivatives (H₂L^2–4) (general abbreviation H₂L), in the presence of vanillin (Hvan) in equimolar ratio under aerobic conditions generating the mixed-ligand oxovanadium(V) complexes of the type [V^VO(L)(van)], (1)–(4) in good yield. All the complexes are diamagnetic and exhibit only ligand-to-metal charge transfer (l.m.c.t.) band near 510 nm in addition to intra-ligand (π → π*) transition band near 330 nm in CH₂Cl₂ solution. ¹H-n.m.r. spectra of the complexes in CDCl₃ solution indicate the presence of two isomeric forms [(1A), (1B); (2A), (2B); (3A), (3B) and (4A), (4B)] in different ratios, which is explained by the interchange of the two binding sites of van⁻ motif between its coordinated equatorial and axial positions. Complexes display two quasi-reversible one electron reduction peaks near +0.10 V and near +0.30 V versus s.c.e. in CH₂Cl₂ solution which are attributed to the successive reduction of V^V→ V^IV and the V^IV→ V^III motifs, respectively. λ_max (for l.m.c.t. transition), and the two reduction potential values (E _1/2)^I (average of the first step anodic and first step cathodic peak potentials) and (E _1/2)^II (average of the second step anodic and second step cathodic peak potentials) of the complexes, are found to be linearly related to the Hammett constants (σ) of the substituents in the aryloxy ring of the hydrazone ligands. λ_max, (E _1/2)^I and (E _1/2)^II values show large dependence: dλ_max/dσ = 37.29 nm, d(E _1/2)^I/dσ = 0.21 V and d(E _1/2)^II/dσ = 0.21 V, respectively, on σ.