Picometer-differential twice-exposed element for three-dimensional measurement with extremely long depth of field.

The accuracy of optical three-dimensional (3D) shape measurement is always influenced by the defocusing of a projection or imaging system. In this paper, a novel optical element made by picometer-differential twice-exposed holography, called a picometer comb, is proposed to generate the projection pattern for 3D shape measurement. Two interference fields with picometer-scale period difference are recorded on a substrate to fabricate the picometer comb by twice-exposed laser holography; this element reconstructs the diffraction field, which is essentially the interference between the holograms of two object waves with a slight angle. This picometer comb has the advantage of the generation of a stable light field distribution with extremely long depth of field and small divergence angle. We demonstrate that this diffraction field provides a solution for non-defocusing 3D shape measurement.

[The Investigation on the Interaction of Colistin Sulfate with Bovine Serum Albumin with Resonance Light Scattering Spectroscopy].

The interaction between colistin sulfate (CS) with bovine serum albumin in physiological buffer (pH 7.4) was investigated with resonance light scattering spectroscopy at 298, 310, and 318 K. The analysis of data indicated that quenching mechanism of BSA-CS was probably static. The value of n was approximately 1, indicating there was only a single class of binding sites on BSA for CS compounds. The thermodynamic parameters were calculated at different temperatures, implying that the interaction was spontaneous and electrostatic force played major role in the binding between CS and BSA. The values of nH were equal to 1 at different temperatures, indicating there was non-cooperative reaction between BSA and CS. The feasibility of resonance light scattering spectroscopy was verified by fluorescence quenching spectroscopy. The quenching reactive parameters (KSV，Kq，n，Ka) from two methods were similar, suggesting resonance light scattering spectroscopy could be used to study the binding interaction between protein and drugs. Resonance light scattering spectroscopy can be used to explore the substance without intrinsic fluorescence, suggesting that the application of resonance light scattering spectroscopy broadens the understanding of the interaction between small molecules and protein.

Studies on the interaction of palmatine hydrochloride with bovine hemoglobin.

The interaction between bovine hemoglobin (BHb) and palmatine hydrochloride (PMT) was investigated at different temperatures using multispectroscopy, as well as the effect of common metal ions (Ca(2+) , Mg(2+) , Zn(2+) , Cu(2+) , Fe(2+) , Fe(3+) , Co(2+) , Ni(2+) ) on the BHb-PMT system. Results showed that the quenching mechanism of PMT on BHb was a static process. The electrostatic force played an important role in the conjugation reaction between BHb and PMT. The order of magnitude of the binding constants (Ka ) was 10(4) , and the number of binding sites (n) in the binary system was ~ 1. The binding distance (r) was ~ 2.44 nm and the primary binding for PMT was located at ß-37 tryptophan in the hydrophobic cavity of BHb. In addition, the Hill's coefficients were ~ 1. Synchronous and circular dichroism spectra revealed that the microenvironment and the conformation of BHb were changed during the binding reaction.

Greater intake of fruit and vegetables is associated with lower risk of nasopharyngeal carcinoma in Chinese adults: a case-control study.

PURPOSE: The effect of fruit and vegetable intake on the risk of nasopharyngeal carcinoma (NPC) remains uncertain due to limited published evidence. We performed a matched case-control study to investigate the relationship between the intake of fruit and vegetables and the risk of NPC. METHODS: Between July 2009 and March 2011, 600 (448 male, 152 female), NPC incident cases from a single hospital in Guangzhou, Guangdong Province, China, a high-incidence area, were enrolled in the study. 600 controls, matched by gender, age (± 3 years) and household type (urban/rural) were also enrolled. Face-to-face interviews were used to collect habitual dietary intakes and information on various covariates. RESULTS: Multivariate conditional logistic regression analyses showed significant, dose-dependent inverse associations between the intake of vegetables, fruit or a combination of the two and the risk of NPC, even after adjustments for social-economic status, body mass index, dietary factors and other potential covariates. The adjusted odds ratios (95% confidence intervals) for NPC in the top quartile of vegetable intake, fruit intake or a combination of the two, as compared to the lowest quartile, were 0.33 (0.22-0.50), 0.70 (0.47-1.04) and 0.37 (0.25-0.55), respectively. Dark green leafy vegetables, carrots, peppers and tomatoes, citrus fruit and pome fruit showed much more pronounced benefits with regards to NPC than other types of fruit and vegetables. Interaction analyses demonstrated that the effects of total combined vegetable and fruit intake were much more significant in subjects with a higher education level (p interaction: 0.027), and the benefits of fruit were observed in males, but not in females (p interaction: 0.088). CONCLUSION: Our findings suggest that a greater consumption of fruit and vegetables may lower the risk of NPC in Chinese adults.

[Simultaneous determination of ten fluoroquinolone residues in organic fertilizers by QuEChERS and high performance liquid chromatography-tandem mass spectrometry].

The analysis of veterinary drugs in organic fertilizers is crucial for an assessment of their potential risks to microbial communities in soils and to human health. A method has been developed for the simultaneous determination of ten fluoroquinolones in organic fertilizers by using the QuEChERS method coupled with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was extracted with disodium ethylenediaminetetraacetic acid (Na2EDTA)-McIlvaine buffer (pH=4.0) and acetonitrile. The target compounds were separated on an Atlantis T3 C18 column (250 mm×4.6 mm, 5 µm) with a mobile phase of 0.2% (v/v) formic acid in acetonitrile and analyzed in the multiple reaction monitoring (MRM) mode via electrospray ionization (ESI). Ten fluoroquinolones were quantified by an internal standard method. The calibration curves of the ten fluoroquinolones exhibited good linearity over the range of 10-500 µg/kg, and the correlation coefficients were above 0.9930. The limits of detection were 0.5-2.5 µg/kg; the limits of quantification were 1.7-8.3 µg/kg. The analytical method was successfully applied in a survey of veterinary drug contamination in nine compost samples. The average recoveries were 82.5%-117.1%, with relative standard deviations of 3.4%-10.2%. The method is accurate, reliable, and sensitive and supports the simultaneous detection of various veterinary drug residues. Therefore, this method can provide a basis for the risk assessment of veterinary drugs in organic fertilizers.

[Study on the mechanism of energy transfer between fluorescein sodium and tetrabromofluorescein sodium in micelles of cationic surface active agent].

In the present paper, the fluorescence reaction of cationic surface-active agents (CSAA) with Tetrabromofluorescein sodium (TBF) in aqueous solution was investigated. It was found that the fluorescence quenching of TBF appears when it reacts with the cation monomer of a CSAA and a new stronger fluorescence is obtained when the ion-associates react with the micellate of CSAA. The authors investigated the condition of energy transfer between acidic fluorescent dyes in micelles of cetyl trimethyl ammonium bromide or hexadecyl pyridinium bromide. It was indicated that in the micelles formed by cationic surface active agent with dyes embedded (cationic surface active agent and dyes are charge opposite), the effective energy transfer between anionic dyes could occur. When the concentration of cationic surface active agent reached certain value, the energy transfer could occur. With the value of two thirds of critical micelle concentration, the efficiency of energy transfer reached the maximum; when the concentration of cationic surface active agent increased, the efficiency of energy transfer would be decreased. The authors also deduced the model of energy transfer between dyes in micelles and laws of it.

[Study on mechanism of lanthanide sensitized fluorescence energy transfer between terbium(III)-ciprofloxacin and rhodamine B].

A complex composed of ciprofloxacin and terbium (Tb3+) in the solution of acetic acid-sodium acetate buffer (pH 6.2) was studied by fluorescence spectroscopy and ultra-violet absorption spectroscopy. The emission peak of Tb3+ appeared at 490, 545, 590 nm, (the sensitized fluorescence was enforced mightily) and the intensity of 545 nm emission peak was increased obviously. In its acute emission spectrum, the strongest emission peak of Tb3+ was at 545 nm, which was close to the wavelength of the biggest absorption peak of RB, 552 nm. Therefore, as the basic dye rhodamine B(RB) was added, the fluorescence intensity of 545 nm emission peak decreased regularly, indicating that there was a great quenching process. The result showed that the course was statistic. Based on the mechanism of the Förster energy transfer, the efficiency of energy transfer and the distance between the acceptor RB and the complex were found. Thereby, it was indicated that the course of action was single static quenching and the mechanism of quenching was based on energy transfer.

[Recent advances in the application of headspace gas chromatography-mass spectrometry].

As a sample preparation technique without extraction by organic solvent, headspace analysis is usually combined with gas chromatography-mass spectrometry (GC-MS) to analyze volatile organic compounds in complex matrices. Headspace gas chromatography-mass spectrometry (HS-GC-MS) is a fast, efficient, green, and sensitive technique, and thus it plays an important role in routine analysis. A brief overview of static headspace, dynamic headspace, headspace solid-phase microextraction and GC-MS is provided, followed by the impact of the analysis system and the optimization process. According to the matrix type classification, the application of HS-GC-MS in the analysis of food samples, environment samples, biology samples, etc. is reviewed. This report clearly indicates that the ongoing research on HS-GC-MS is active and new applications are emerging. It has significant prospects for the analysis of volatile organic compounds.

[Preparation of hydrophilic polymer brushes magnetic microspheres by surface-initiated for magnetic dispersive solid phase extraction of tetracycline antibiotic residues from honey].

Activators regenerated by electron transfer-atom transfer radical polymerization (ARGET-ATRP) was applied to the continuous grafting of polybasic polymers and poly(ethylene glycol) (PEG) brushes on the surface of the magnetic microspheres (MMs). At first, the MMs were coated with silica gel, modified by amino group, and then 2-bromoisobutyryl bromide was grafted on the surface of MMs. After that, the hydrophilic polymer brushes magnetic microspheres (HMMs) were prepared by polymerization on the surface of the MMs. HMMs were characterized by transmission electron microscope (TEM) and Fourier transform-infrared (FT-IR) spectrometer. The adsorption performance to protein was studied. The results demonstrated that HMMs have the relatively uniform particle size, good dispersity and excellent protein resistance properties. Tetracycline antibiotics (TCs, tetracycline hydrochloride, chlortetracycline hydrochloride and doxycycline hydrochloride) in honey samples were determined by magnetic dispersion solid phase extraction (MDSPE) using the prepared HMMs and high performance liquid chromatography (HPLC). The average recoveries were obtained in the range of 85.8%-94.5%. The limits of detection (LODs) and limits of quantification (LOQs) of the proposed method were in the ranges of 1.92-2.56 µg/kg and 6.40-8.53 µg/kg, respectively. The proposed method was successfully applied to fast clean-up and enrichment of the TCs residues in honey.

Diet Quality Scores and Risk of Nasopharyngeal Carcinoma in Chinese Adults: A Case-Control Study.

Many studies show that dietary factors may affect the risk of nasopharyngeal carcinoma (NPC). We examined the association between overall diet quality and NPC risk in a Chinese population. This case-control study included 600 NPC patients and 600 matched controls between 2009 and 2011 in Guangzhou, China. Habitual dietary intake and various covariates were assessed via face-to-face interviews. Diet quality scores were calculated according to the Healthy Eating Index-2005 (HEI-2005), the alternate Healthy Eating Index (aHEI), the Diet Quality Index-International (DQI-I), and the alternate Mediterranean Diet Score (aMed). After adjustment for various lifestyle and dietary factors, greater diet quality scores on the HEI-2005, aHEI, and DQI-I-but not on the aMed-showed a significant association with a lower risk of NPC (p-trends, <0.001-0.001). The odds ratios (95% confidence interval) comparing the extreme quartiles of the three significant scores were 0.47 (0.32-0.68) (HEI-2005), 0.48 (0.33-0.70) (aHEI), and 0.43 (0.30-0.62) (DQI-I). In gender-stratified analyses, the favorable association remained significant in men but not in women. We found that adherence to the predefined dietary patterns represented by the HEI-2005, aHEI, and DQI-I scales predicted a lower risk of NPC in adults from south China, especially in men.

Comparison of the Educational Effect upon Myopia Prevention and Treatment between Video Demonstration and Traditional Teaching.

PURPOSE: To compare the education effect of video demonstrations and conventional teaching on the prevention and control of myopia. METHODS: Eighty students were randomly divided into an experimental (n = 40) and a control (n = 40) group, and each group was split into two classes of 40 students. The students in the experimental group attended classes mainly based on video demonstration and those in the control group received conventional teaching. All students then undertook a test and the examination scores were statistically compared between the two groups. RESULTS: The educational background, age, and gender did not differ between the two groups (all P > 0.05). The experimental group had a mean test score of 8.25 ± 1.45, which was slightly lower than the mean of 8.58 ± 1.11 in the control group, but the difference was not statistically significant (t = -1.589, P = 0.114). CONCLUSION: The educational effect of video demonstrations was almost identical to that of traditional teaching. In addition, video classes reduced the training time and financial costs, indicating that they deserve widespread application.

Simultaneous determination of trace cadmium and mercury in Chinese herbal medicine by non-dispersive atomic fluorescence spectrometry using intermittent flow vapor generator.

A method was proposed for the simultaneous determination of trace cadmium and mercury by vapor generation non-dispersive atomic fluorescence spectrometry using an intermittent flow system. The effects of the parameters on the performance were studied systematically. The parameters such as acid concentration of the reaction medium, flow rate of the carrier gas and shield gas, the observation height and the atomizer temperature, etc. which affected the sensitivity, were optimized. Ascorbic acid, cobalt ion and thiourea were used as enhancement reagents or masking agents to enhance the generation efficiency of the volatile species of Cd and Hg. The mechanisms of their effects on vapor generation were investigated. In the presence of thiourea and ascorbic acid, the influences of some coexisting elements on the determination of cadmium and mercury were investigated. The detection limits (3sigma) were 0.010 microg l(-1) for Cd and 0.019 microg l(-1) for Hg, respectively. The relative standard deviations for Cd and Hg at 1.00 microg l(-1) were 2.6% and 0.97% (n = 11), respectively. The proposed method has been satisfactorily applied to the determination of trace cadmium and mercury in Chinese herbal medicine.

Experimental and finite element analysis of dynamic loading of the mouse forearm.

Bone formation is reported to initiate in osteocytes by mechanotransduction due to dynamic loading of bone. The first step towards this is to characterize the dynamic strain fields in the overall bone. Here, the previously developed mouse forearm ulna-radius model, subjected to static loading, has been further enhanced by incorporating a loading cap and applying a cyclic dynamic load to more closely approximate experimental biological conditions. This study also incorporates data obtained from strain gauging both the ulna and radius simultaneously. Based on separate experiments, the elastic modulus of the ulna and radius were determined to be 13.8 and 9.9 GPa, respectively. Another novel aspect of the numerical model is the inclusion of the interosseous membrane in the FE model with membrane stiffness ranging from 5-15 N/mm that have been found to give strain values closer to that from the experiments. Interestingly, the inclusion of the interosseous membrane helped to equalize the peak strain magnitudes in the ulna and radius (∼1800 at 2 N load and ∼3200 at 3.5 N), which was also observed experimentally. This model represents a significant advance towards being able to simulate through FE analysis the strain fields generated in vivo upon mechanical loading of the mouse forearm.

A preliminary three-dimensional finite element analysis of mandibular implant overdentures.

A treatment protocol that may lead to reduced mandibular posterior residual ridge resorption in patients with overdentures retained and supported by two interforaminal implants was investigated. The treatment included the addition of short implants in the posterior edentulous mandible for the presumed purpose of favorable provision of mechanical load stimulus to alveolar bone. Three-dimensional finite element analysis was used to model cited effective strains that may stimulate bone remodeling in two selected models. Based on this laboratory study, the addition of posterior short implants has a favorable effect in maintaining bone mass under implant retained overdentures.

Application of neural networks for the prediction of cartilage stress in a musculoskeletal system.

Traditional finite element (FE) analysis is computationally demanding. The computational time becomes prohibitively long when multiple loading and boundary conditions need to be considered such as in musculoskeletal movement simulations involving multiple joints and muscles. Presented in this study is an innovative approach that takes advantage of the computational efficiency of both the dynamic multibody (MB) method and neural network (NN) analysis. A NN model that captures the behavior of musculoskeletal tissue subjected to known loading situations is built, trained, and validated based on both MB and FE simulation data. It is found that nonlinear, dynamic NNs yield better predictions over their linear, static counterparts. The developed NN model is then capable of predicting stress values at regions of interest within the musculoskeletal system in only a fraction of the time required by FE simulation.

Habitual consumption of soy products and risk of nasopharyngeal carcinoma in Chinese adults: a case-control study.

BACKGROUND AND OBJECTIVES: Many studies have shown a negative association between the consumption of soy products and the risk of some cancers, but little is known about the effect of soy consumption on nasopharyngeal carcinoma. We assessed the association between the consumption of soy products on nasopharyngeal carcinoma risk in Chinese individuals. METHODS: This case-control study included 600 (448 males and 152 females) incident cases of nasopharyngeal carcinoma, and an equal number of controls, matched according to gender, age (± 3 y) and household type to the nasopharyngeal carcinoma cases. All subjects were recruited from hospitals in Guangzhou, China. A face-to-face interview was conducted with each study individual to collect general information and habitual dietary intake using a 78-item quantitative food-frequency questionnaire. Odds ratios and their 95% confidence intervals were estimated using conditional logistic regression analyses. RESULTS: The median intakes of soy foods (in protein) were 0.5/0.5, 1.4/1.7, 2.7/3.3 and 6.1/7.7 (male/female) g/d in the quartiles 1 to 4. Both univariate and multivariate analyses showed no significant association between the consumption of soy proteins or soy isoflavones and the risk of nasopharyngeal carcinoma. The adjusted odds ratios (95% confidence intervals) between extreme quartiles were 0.97 (0.66-1.45) for soy proteins and 0.97 (0.66-1.42) for total isoflavones. Null associations were also observed between intake of the individual isoflavones daidzein, genistein and glycitein and NPC risk, with adjusted odds ratios for the extreme quartiles ranging between 0.73 and 1.23. CONCLUSION: Habitual consumption of soy products had no significant effect on the risk of nasopharyngeal carcinoma in Chinese adults with a relatively low intake.

Load/strain distribution between ulna and radius in the mouse forearm compression loading model.

Finite element analysis (FEA) of the mouse forearm compression loading model is used to relate strain distributions with downstream changes in bone formation and responses of bone cells. The objective of this study was to develop two FEA models - the first one with the traditional ulna only and the second one in which both the ulna and radius are included, in order to examine the effect of the inclusion of the radius on the strain distributions in the ulna. The entire mouse forearm was scanned using microCT and images were converted into FEA tetrahedral meshes using a suite of software programs. The performance of both linear and quadratic tetrahedral elements and coarse and fine meshes were studied. A load of 2N was applied to the ulna/radius model and a 1.3N load (based on previous investigations of load sharing between the ulna and radius in rats) was applied to the ulna only model for subsequent simulations. The results showed differences in the cross sectional strain distributions and magnitude within the ulna for the combined ulna/radius model versus the ulna only model. The maximal strain in the combined model occurred about 4mm toward the distal end from the ulna mid-shaft in both models. Results from the FEA model simulations were also compared to experimentally determined strain values. We conclude that inclusion of the radius in FE models to predict strains during in vivo forearm loading increases the magnitude of the estimated ulna strains compared to those predicted from a model of the ulna alone but the distribution was similar. This has important ramifications for future studies to understand strain thresholds needed to activate bone cell responses to mechanical loading.

An imprinted organic--inorganic hybrid sorbent for selective separation of cadmium from aqueous solution.

A hierarchical double-imprinting concept was applied to the preparation of a new organic-inorganic hybrid sorbent for selective separation of Cd(II) from aqueous solution. In the prepared hierarchically imprinted sorbent, both Cd(II) and surfactant micelles (cetyltrimethylammonium bromide) were used as templates. The sorbent was prepared through self-hydrolysis, self-condensation, and co-condensation of the cross-linking agent (tetraethoxysilicate) and the functional precursor (3-(2-aminoethylamino)-propyltrimethoxysilane) in an alkaline media followed by gelation. The selectivity of the sorbent was investigated by a batch competitive ion-binding experiment using an aqueous Cd(II) and Zn(II) mixture. The largest selectivity coefficient for Cd(II) in the presence of Zn(II) was found to be over 100; the largest relative selectivity coefficient between Cd(II) and Zn(II), over 200. The uptake capacity of the prepared hierarchically imprinted sol-gel sorbent and the selectivity coefficient are much higher than those of the sorbent prepared in the absence of CTAB-template. The sorbent possesses a fast kinetics for the removal of Cd(II) from aqueous solution.

Simultaneous determination of trace cadmium and arsenic in biological samples by hydride generation-double channel atomic fluorescence spectrometry.

Hydride generation atomic fluorescence spectrometry (HG-AFS) has been used for determination of hydride-forming elements because of its high sensitivity, simplicity, and low costs, but most of such work has been concentrated on single element analysis, and reports dealing with multielement determination by HG-nondispersive (ND)AFS are rare. In this work, a sensitive HG-NDAFS method was developed for simultaneous determination of trace cadmium and arsenic in biological materials. The conditions for the generation of volatile cadmium and arsenic species from the reaction with KBH4 in aqueous solution were investigated using a double-channel AFS integrated with an intermittent flow reactor. Like thiourea and Co(II), ascorbic acid was found to significantly enhance the generation efficiency of volatile Cd and As species. The interferences of coexisting ions were evaluated. Under optimal conditions, the detection limits for Cd and As were determined to be 10 and 150 ng L(-1), respectively. The precision for 11 replicate determinations at the 1 microg L(-1) Cd level and the 10 microg L(-1) As level were 3.5 and 2.7% (RSD), respectively. The recoveries of spike analytes in the biological samples studied ranged from 94 to 109%. The proposed method was successfully applied to the simultaneous determination of Cd and As in a variety of biological samples.