Concurrent sympathetic activation and vagal withdrawal in hyperthyroidism: Evidence from detrended fluctuation analysis of heart rate variability

Despite many previous studies on the association between hyperthyroidism and the hyperadrenergic state, controversies still exist. Detrended fluctuation analysis (DFA) is a well recognized method in the nonlinear analysis of heart rate variability (HRV), and it has physiological significance related to the autonomic nervous system. In particular, an increased short-term scaling exponent α1 calculated from DFA is associated with both increased sympathetic activity and decreased vagal activity. No study has investigated the DFA of HRV in hyperthyroidism. This study was designed to assess the sympathovagal balance in hyperthyroidism. We performed the DFA along with the linear analysis of HRV in 36 hyperthyroid Graves’ disease patients (32 females and 4 males; age 30 ± 1 years, means ± SE) and 36 normal controls matched by sex, age and body mass index. Compared with the normal controls, the hyperthyroid patients revealed a significant increase (P<0.001) in α1 (hyperthyroid 1.28±0.04 versus control 0.91±0.02), long-term scaling exponent , overall scaling exponent , low frequency power in normalized units (LF%) and the ratio of low frequency power to high frequency power (LF/HF); and a significant decrease (P<0.001) in the standard deviation of the R-R intervals (SDNN) and high frequency power (HF). In conclusion, hyperthyroidism is characterized by concurrent sympathetic activation and vagal withdrawal. This sympathovagal imbalance state in hyperthyroidism helps to explain the higher prevalence of atrial fibrillation and exercise intolerance among hyperthyroid patients.     

A single-machine scheduling problem with two-agent and deteriorating jobs

Deteriorating jobs scheduling problems have been extensively studied in recent years. However, it is assumed that there is a common goal to minimize for all jobs in most of the research. In many management situations, multiple agents compete on the usage of a common processing resource. In this paper, we considered a single-machine scheduling problem with a linear deterioration assumption where the objective is to minimize the total weighted completion time of jobs from the first agent with the restriction that no tardy job is allowed for the second agent. We proposed a branch-and-bound algorithm and three heuristic algorithms to search for the optimal solution and near-optimal solutions, respectively. A computational experiment was conducted to evaluate the performance of the proposed algorithms.     

Back to basics: label-free technologies for small molecule screening

Small molecule high-throughput screening in drug discovery today is dominated by techniques which are dependent upon artificial labels or reporter systems. While effective, these approaches can be affected by certain experimental limitations, such as conformational restrictions imposed by the selected label or compound fluorescence/quenching. Label-free approaches potentially address many of these issues by allowing researchers to investigate more native systems without fluorescence- or luminescence-based readouts. However, due to throughput and expense constraints, label-free methods have been largely relegated to a supporting role as the basis of secondary assays. In this review, we describe recent improvements in impedance-based, optical biosensor-based, automated patch clamp and mass spectrometry technologies that have enhanced their ease of use and throughput and, hence, their utility for primary screening of small- to medium-sized compound libraries. The ultimate maturation of these techniques will enable drug discovery researchers to screen large chemical libraries against minimally manipulated biological systems.     

Tool replacement policy for one-sided processes with low fraction defective

In most manufacturing industries, tool replacement policy is essential for minimizing the fraction defective and the manufacturing cost. Tool wear is caused by the action of sliding chips in the shear zone, and the friction generated between the tool flank and workpiece. This wear, apparently, is a dominant and irremovable component of variability in many machining processes, which is a systematic assignable cause. As the tool wear occurs in the machining processes, the fraction of defectives would gradually become significant. When the fraction defective reaches a certain level, the tool must be replaced. Therefore, detecting suitable time for tool replacement operation becomes essential. In this paper, we present an analytical approach for unilateral processes based on the one-sided process capability index C _PU (or C _PL ) to find the appropriate time for tool replacement. Accurate process capability must be calculated, particularly, when the data contains assignable cause variation. By calculating the index C _PU (or C _PL ) in a dynamical environment, we propose estimators of C _PU (or C _PL ) and obtain exact form of the sampling distribution in the presence of systematic assignable cause. The proposed procedure is then applied to a real manufacturing process involving tool wear problem, to demonstrate the applicability of the proposed approach.     

A Probability Model of Star‐Branched Polymers Formed by Connecting Polydispersed Primary Chains Onto a Multifunctional Coupling Agent

Summary: A probability model, based on the “in‐out” recursive analysis, is developed for obtaining the average molecular weights of star polymers formed by connecting polydispersed primary chains onto a multifunctional coupling agent. The average properties and the polydispersity index of the formed star polymers can be described as a function of the reaction conversion and the average properties of the polydispersed primary chains without the knowledge of the whole distribution. The results indicate that, although PI of the resulting star polymers might increase at the intermediate conversion for the higher functionalities of the core molecules, the resulting star polymers generally have narrower molecular weight distributions at the complete conversion compared to the initial polydispersed polymer chains.

A schematic illustration of the star polymer formation.     

Synthesis,structure, and electrochemistry of Ag-modified LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript> cathode materials for lithium-ion batteries

The composite of silver-modified lithium manganese oxide were prepared using thermal decomposition method of different mole ratio. Structural characterization was carried out by X-ray diffraction (XRD). XRD analysis revealed different patterns as the content of the dopant in the spinel increases. Phase analysis shows that Ag particles were dispersed on the LiMn₂O₄ surface instead of entering the spinel structure. On the other hand, the electrochemical behavior of cathode powder was examined by using two-electrode test cells consisting of a cathode, metallic lithium as anode, and a solid polymer electrolyte of 0.87PEO-0.13LiCF₃SO₃-0.10DBP. According to the electrochemical tests results, the influence of the Ag additive content on the electrochemical properties of Ag/LiMn₂O₄ composites is clearly shown.     

Synergistic antitumor effect of curcumin and dinitrosyl iron complexes for against melanoma cells

The aim of this study was to examine whether combining curcumin, a chemoprevention agent, and dinitrosyl iron complexes (DNICs) would have a synergistic cytotoxic effect on mouse melanoma B16-F10 cells in vitro. Three synthesized DNICs-[PPN] [(NO)₂Fe(SCH₂CONHCH₃)₂] (NC01), [PPN] [(NO)₂Fe(SCH₂CON(CH₃)₂)₂] (NC02), and [Na][(NO)₂Fe(SCH₂CON(CH₃)₂)₂] (NC03) were tested in this study. In vitro DNA cleavage assay showed all three DNICs could cause plasmid DNA damage through releasing NO under UV irradiation. The cytotoxicity assay demonstrated these DNICs were toxic to B16-F10 cells in vitro, and the estimated values of LD₅₀ (24 h of incubation) of NC01 and NC02 were 1 μM, while the values of LD₅₀ of NC03 was 200 μM. No synergistic cytotoxicity effect was noted in the treatments of the combinations of curcumin and DNICs. On the contrary, in the presence of NC03, the toxicity of curcumin was reduced. Using UV-Visible spectroscopy and fluorescence microscopy, we found NC03 might interact with curcumin and reduce the accumulation of curcumin in cells. Further experiments using the pretreatment of curcumin for 4 h followed by the treatment of NC03 showed the synergistic cytotoxic effect, while, the pretreatment of NC03 followed by the treatment of curcumin did not have any effect. This study provides the basis for further investigation on the effects of combinations of curcumin and other NO donors.     

Reactions of 2-aminothiobenzamide with isocyanates: A new synthesis of 2, 3-dihydroimidazo[1, 2-c]quinazolin-5(6H)-one and 3, 4-Dihydro-2H-pyrimido[1, 2-c]quinazolin-6(7H)-one

2-(2-Chloroethylureido)- and 2-(3-chloropropylureido)thiobenzamides 5a, b were prepared in good yields by treating 2-aminothiobenzamide with 2-chloroethyl and 3-chloropropyl isocyanates respectively. Subsequent treatment of compound 5a and 5b either with alkali or mineral acid led to the formation of 2, 3-dihydro-imidazo[1, 2-c]quinazolin-5(6H)-one 7a and 3, 4-Dihydro-2H-pyrimido[1, 2-c]quinazolin-6(7H)-one 7b .     

Studies on Polymerization of Vinyl Compounds Initiated by Metal Chelate II Kinetics of Polymerization of Methyl Methacrylate Initiated by Nickel Ethyl Acetoacetate in the Presence and the Absence of Aromatic Amines

The kintetic studies of polymerization of methyl methacrylate initiated with nickel ethyl acetoacetate gave the following equations. R_p=K₁[Monomer]^1.4[Chelate]^0.5, in the absence ox aniline R_p=K₂[Monomer]^1.2[Chelate]^0.5 [Aniline]^0,5, in the presence of aniline. Some aromatic amines such as aniline markedly accelerated the polymerization, while pyridine had no such effect. The activation energy of initiation was 24.8 kcal/mol in the absence of aniline, and 8.8 kcal/mol in the presence of aniline. Both the kinetic data and the infrared spectra of the polymer indicated that the polymerization was radical in nature. The reaction order against monomer varied, as the temperature differed. The spectrophotometric investigation indicated formation of a complex between the chelate and the monomer, or amines. It also showed that the formation of a complex was not a factor which controlled the rate of initiation. A scheme of initiation mechanism was presented on the basis of the above experimental evidence.     

Graphical Determination of Monomer Shift,Dimer Shift and Dimerization Constant for Self-Association: 2-Isopropyl Phenol in C6D12 as an Example

We propose a graphical method to treat dilution shift in NMR spectra to determine the monomer shift, dimer shift and dimerization constant simultaneously and consistently for the system of monomer/dimer equilibrium. The salient features include avoiding error-prone manual extrapolation to zero concentration to obtain a monomer shift, and providing consistent assessment and error estimation for the determination. The dilution shifts of 2-isopropyl phenol in C₆D₁₂ serve to demonstrate this graphical method. The enthalpy and entropy of dimerization are determined via a van't Hoff plot from the temperature variation of the dimerization constant.