Bead-bead interaction parameters in dissipative particle dynamics: Relation to bead-size, solubility parameter, and surface tension

NASA Astrophysics Data System (ADS)

Maiti, Amitesh; McGrother, Simon

2004-01-01

Dissipative particle dynamics (DPD) is a mesoscale modeling method for simulating equilibrium and dynamical properties of polymers in solution. The basic idea has been around for several decades in the form of bead-spring models. A few years ago, Groot and Warren [J. Chem. Phys. 107, 4423 (1997)] established an important link between DPD and the Flory-Huggins χ-parameter theory for polymer solutions. We revisit the Groot-Warren theory and investigate the DPD interaction parameters as a function of bead size. In particular, we show a consistent scheme of computing the interfacial tension in a segregated binary mixture. Results for three systems chosen for illustration are in excellent agreement with experimental results. This opens the door for determining DPD interactions using interfacial tension as a fitting parameter.

Direct position determination for digital modulation signals based on improved particle swarm optimization algorithm

NASA Astrophysics Data System (ADS)

Yu, Wan-Ting; Yu, Hong-yi; Du, Jian-Ping; Wang, Ding

2018-04-01

The Direct Position Determination (DPD) algorithm has been demonstrated to achieve a better accuracy with known signal waveforms. However, the signal waveform is difficult to be completely known in the actual positioning process. To solve the problem, we proposed a DPD method for digital modulation signals based on improved particle swarm optimization algorithm. First, a DPD model is established for known modulation signals and a cost function is obtained on symbol estimation. Second, as the optimization of the cost function is a nonlinear integer optimization problem, an improved Particle Swarm Optimization (PSO) algorithm is considered for the optimal symbol search. Simulations are carried out to show the higher position accuracy of the proposed DPD method and the convergence of the fitness function under different inertia weight and population size. On the one hand, the proposed algorithm can take full advantage of the signal feature to improve the positioning accuracy. On the other hand, the improved PSO algorithm can improve the efficiency of symbol search by nearly one hundred times to achieve a global optimal solution.

Automated HPLC assay for urinary collagen cross-links: effect of age, menopause, and metabolic bone diseases.

PubMed

Kraenzlin, Marius E; Kraenzlin, Claude A; Meier, Christian; Giunta, Cecilia; Steinmann, Beat

2008-09-01

The pyridinium cross-links pyridinoline (PYD) and deoxypyridinoline (DPD) are established markers of bone resorption. We evaluated the analytical and clinical performance of a commercially available PYD HPLC assay and established reference intervals in children and adults. We used a commercially available reagent set (Chromsystems Instruments & Chemicals) to measure PYD and DPD in 319 healthy controls (156 premenopausal women, 80 healthy men, and 83 healthy children age 1 month to 14 years) and 397 patients with metabolic bone diseases (postmenopausal osteoporosis, n = 175; male osteoporosis, n = 176; hyperparathyroidism, n = 17; hyperthyroidism, n = 19; Paget disease, n = 10). The mean intraassay and interassay CVs were <6% and <8% for both PYD and DPD, respectively. The reference interval was constant for premenopausal women in the age group 20-49 years. In men, cross-link values peaked at 20-29 years and decreased thereafter. Women with postmenopausal osteoporosis had significantly higher PYD (51%) and DPD (58%) values compared to premenopausal women. Similar results were found in osteoporotic men. In children the highest values were found in the first weeks and months after birth, followed by a decrease of 50%-60% at age 11-14 years. In metabolic bone diseases cross-link concentrations were significantly increased. The DPD:PYD ratio (mean value approximately 0.2) was remarkably constant in all populations evaluated. The automated HPLC assay is a precise and convenient method for PYD and DPD measurement. We established reference intervals for adult women and men and for children up to 14 years old. The cross-link concentrations we determined by use of this HPLC method confirm its clinical value in enabling identification of increased bone resorption in patients with metabolic bone diseases.

Active learning of constitutive relation from mesoscopic dynamics for macroscopic modeling of non-Newtonian flows

NASA Astrophysics Data System (ADS)

Zhao, Lifei; Li, Zhen; Caswell, Bruce; Ouyang, Jie; Karniadakis, George Em

2018-06-01

We simulate complex fluids by means of an on-the-fly coupling of the bulk rheology to the underlying microstructure dynamics. In particular, a continuum model of polymeric fluids is constructed without a pre-specified constitutive relation, but instead it is actively learned from mesoscopic simulations where the dynamics of polymer chains is explicitly computed. To couple the bulk rheology of polymeric fluids and the microscale dynamics of polymer chains, the continuum approach (based on the finite volume method) provides the transient flow field as inputs for the (mesoscopic) dissipative particle dynamics (DPD), and in turn DPD returns an effective constitutive relation to close the continuum equations. In this multiscale modeling procedure, we employ an active learning strategy based on Gaussian process regression (GPR) to minimize the number of expensive DPD simulations, where adaptively selected DPD simulations are performed only as necessary. Numerical experiments are carried out for flow past a circular cylinder of a non-Newtonian fluid, modeled at the mesoscopic level by bead-spring chains. The results show that only five DPD simulations are required to achieve an effective closure of the continuum equations at Reynolds number Re = 10. Furthermore, when Re is increased to 100, only one additional DPD simulation is required for constructing an extended GPR-informed model closure. Compared to traditional message-passing multiscale approaches, applying an active learning scheme to multiscale modeling of non-Newtonian fluids can significantly increase the computational efficiency. Although the method demonstrated here obtains only a local viscosity from the polymer dynamics, it can be extended to other multiscale models of complex fluids whose macro-rheology is unknown.

Development of DPD coarse-grained models: From bulk to interfacial properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solano Canchaya, José G.; Dequidt, Alain, E-mail: alain.dequidt@univ-bpclermont.fr; Goujon, Florent

2016-08-07

A new Bayesian method was recently introduced for developing coarse-grain (CG) force fields for molecular dynamics. The CG models designed for dissipative particle dynamics (DPD) are optimized based on trajectory matching. Here we extend this method to improve transferability across thermodynamic conditions. We demonstrate the capability of the method by developing a CG model of n-pentane from constant-NPT atomistic simulations of bulk liquid phases and we apply the CG-DPD model to the calculation of the surface tension of the liquid-vapor interface over a large range of temperatures. The coexisting densities, vapor pressures, and surface tensions calculated with different CG andmore » atomistic models are compared to experiments. Depending on the database used for the development of the potentials, it is possible to build a CG model which performs very well in the reproduction of the surface tension on the orthobaric curve.« less

On the comparisons between dissipative particle dynamics simulations and self-consistent field calculations of diblock copolymer microphase separation

NASA Astrophysics Data System (ADS)

Sandhu, Paramvir; Zong, Jing; Yang, Delian; Wang, Qiang

2013-05-01

To highlight the importance of quantitative and parameter-fitting-free comparisons among different models/methods, we revisited the comparisons made by Groot and Madden [J. Chem. Phys. 108, 8713 (1998), 10.1063/1.476300] and Chen et al. [J. Chem. Phys. 122, 104907 (2005), 10.1063/1.1860351] between their dissipative particle dynamics (DPD) simulations of the DPD model and the self-consistent field (SCF) calculations of the "standard" model done by Matsen and Bates [Macromolecules 29, 1091 (1996), 10.1021/ma951138i] for diblock copolymer (DBC) A-B melts. The small values of the invariant degree of polymerization used in the DPD simulations do not justify the use of the fluctuation theory of Fredrickson and Helfand [J. Chem. Phys. 87, 697 (1987), 10.1063/1.453566] by Groot and Madden, and their fitting between the DPD interaction parameters and the Flory-Huggins χ parameter in the "standard" model also has no rigorous basis. Even with their use of the fluctuation theory and the parameter-fitting, we do not find the "quantitative match" for the order-disorder transition of symmetric DBC claimed by Groot and Madden. For lamellar and cylindrical structures, we find that the system fluctuations/correlations decrease the bulk period and greatly suppress the large depletion of the total segmental density at the A-B interfaces as well as its oscillations in A- and B-domains predicted by our SCF calculations of the DPD model. At all values of the A-block volume fractions in the copolymer f (which are integer multiples of 0.1), our SCF calculations give the same sequence of phase transitions with varying χN as the "standard" model, where N denotes the number of segments on each DBC chain. All phase boundaries, however, are shifted to higher χN due to the finite interaction range in the DPD model, except at f = 0.1 (and 0.9), where χN at the transition between the disordered phase and the spheres arranged on a body-centered cubic lattice is lower due to N = 10 in the DPD model. Finally, in 11 of the total 20 cases (f-χN combinations) studied in the DPD simulations, a morphology different from the SCF prediction was obtained due to the differences between these two methods.

Computing the non-Markovian coarse-grained interactions derived from the Mori-Zwanzig formalism in molecular systems: Application to polymer melts

NASA Astrophysics Data System (ADS)

Li, Zhen; Lee, Hee Sun; Darve, Eric; Karniadakis, George Em

2017-01-01

Memory effects are often introduced during coarse-graining of a complex dynamical system. In particular, a generalized Langevin equation (GLE) for the coarse-grained (CG) system arises in the context of Mori-Zwanzig formalism. Upon a pairwise decomposition, GLE can be reformulated into its pairwise version, i.e., non-Markovian dissipative particle dynamics (DPD). GLE models the dynamics of a single coarse particle, while DPD considers the dynamics of many interacting CG particles, with both CG systems governed by non-Markovian interactions. We compare two different methods for the practical implementation of the non-Markovian interactions in GLE and DPD systems. More specifically, a direct evaluation of the non-Markovian (NM) terms is performed in LE-NM and DPD-NM models, which requires the storage of historical information that significantly increases computational complexity. Alternatively, we use a few auxiliary variables in LE-AUX and DPD-AUX models to replace the non-Markovian dynamics with a Markovian dynamics in a higher dimensional space, leading to a much reduced memory footprint and computational cost. In our numerical benchmarks, the GLE and non-Markovian DPD models are constructed from molecular dynamics (MD) simulations of star-polymer melts. Results show that a Markovian dynamics with auxiliary variables successfully generates equivalent non-Markovian dynamics consistent with the reference MD system, while maintaining a tractable computational cost. Also, transient subdiffusion of the star-polymers observed in the MD system can be reproduced by the coarse-grained models. The non-interacting particle models, LE-NM/AUX, are computationally much cheaper than the interacting particle models, DPD-NM/AUX. However, the pairwise models with momentum conservation are more appropriate for correctly reproducing the long-time hydrodynamics characterised by an algebraic decay in the velocity autocorrelation function.

Relationship Between the DPD and TS mRNA Expression and the Response to S-1-Based Chemotherapy and Prognosis in Patients with Advanced Gastric Cancer.

PubMed

Shen, Xiao-Ming; Zhou, Chong; Lian, Lian; Li, Li-Qun; Li, Wei; Tao, Min

2015-04-01

The aim was to determine changes in dihydropyrimidine dehydrogenase (DPD) and thymidylate synthase (TS) mRNAs in the blood of advanced gastric cancer (AGC) patients to see whether these enzymes affected the patients' response to S-1-based chemotherapy and prognosis. For this purpose, pretreatment DPD/TS mRNA expressions were determined in 40 AGC patients using RT-PCR. The patients were then administered with S-1-based regimen (S-1 + cisplatin) and toxicities were recorded. The relationship between the DPD/TS mRNA expressions and the chemotherapy response, drug resistance, and prognosis was analyzed. The data show that DPD mRNA expression correlated significantly with Lauren type while TS mRNA expression correlated with distant metastasis. Patients with higher DPD and/or TS mRNA expression(s) showed poor response, while those with low DPD mRNA expression showed better response to the chemotherapy. Pooled analysis showed that the patients with low DPD/TS mRNA expressions had better therapeutic response. The incidence of bone marrow suppression, diarrhea, and oral mucositis was high in patients with low DPD mRNA expression. Median overall survival (OS) in 40 patients was 13.5 months. It was 17 months for low and 10 months for high DPD (P = 0.044) and TS mRNA expression (P = 0.047). Pooled analysis showed that the patients with both low DPD/TS mRNA expressions had longer OS (P = 0.001). In conclusion, the detection of DPD and/or TS mRNA expression can be used to predict the response to S-1-based chemotherapy, drug resistance, and prognosis in AGC patients as well as to help guide the individualized treatment of gastric cancer.

Simulating the frontal instability of lock-exchange density currents with dissipative particle dynamics

NASA Astrophysics Data System (ADS)

Li, Yanggui; Geng, Xingguo; Wang, Heping; Zhuang, Xin; Ouyang, Jie

2016-06-01

The frontal instability of lock-exchange density currents is numerically investigated using dissipative particle dynamics (DPD) at the mesoscopic particle level. For modeling two-phase flow, the “color” repulsion model is adopted to describe binary fluids according to Rothman-Keller method. The present DPD simulation can reproduce the flow phenomena of lock-exchange density currents, including the lobe-and-cleft instability that appears at the head, as well as the formation of coherent billow structures at the interface behind the head due to the growth of Kelvin-Helmholtz instability. Furthermore, through the DPD simulation, some small-scale characteristics can be observed, which are difficult to be captured in macroscopic simulation and experiment.

Investigation of some disinfection chemicals and water quality parameters in swimming pools in the city center and districts of Canakkale, Turkey.

PubMed

Uysal, Tolga; Yilmaz, Selehattin; Turkoglu, Muhammet; Sadikoglu, Murat

2017-07-01

In this study, the variations in concentrations of some disinfection chemicals such as cyanuric acid (CyA), free chlorine (FC), and residual chlorine (RC), which affect human health, were investigated in the water of swimming pools. In addition, quality parameters such as temperature, pH, and total alkalinity (TA) in 44 swimming pools located in the city center and districts of Canakkale, Turkey, were examined in the summer period. While FC and RC amounts were analyzed using tablet tests with N-N-diethyl phenylenediamine (DPD 1) and potassium iodine (DPD 3) using the colorimetric method in the comparator, TA and CyA levels were measured with a photometric method. Temperature and pH were measured using YSI 556 MPS. Levels of CyA, FC, RC, pH, temperature, and TA varied between 0.00 and 725.0 mg L -1 (108.0 ± 111.4 mg L -1 ), 0.00 and 5.00 mg L -1 (1.60 ± 0.962 mg L -1 ), 0 and 0.55 mg L -1 (0.087 ± 0.059), 6.40 and 8.20 mg L -1 (7.30 ± 0.038 mg L -1 ), 22.0 and 32.0 °C (27.6 ± 1.45 °C), and 0.00 and 391.0 mg L -1 (129.3 ± 89.0), respectively. The findings were compared to standard limit values of the Ministry of Health of the Turkish Republic and other countries. Not only maximum concentrations of CyA but also the average concentrations exceeded the standard limit values of different countries in July and August with high tourism activity in Turkey. Although there is no problem in view of average values of other quality parameters, there are some problems in view of the maximum values in pool waters compared to standard limit values.

Direct Position Determination of Unknown Signals in the Presence of Multipath Propagation

PubMed Central

Yu, Hongyi

2018-01-01

A novel geolocation architecture, termed “Multiple Transponders and Multiple Receivers for Multiple Emitters Positioning System (MTRE)” is proposed in this paper. Existing Direct Position Determination (DPD) methods take advantage of a rather simple channel assumption (line of sight channels with complex path attenuations) and a simplified MUltiple SIgnal Classification (MUSIC) algorithm cost function to avoid the high dimension searching. We point out that the simplified assumption and cost function reduce the positioning accuracy because of the singularity of the array manifold in a multi-path environment. We present a DPD model for unknown signals in the presence of Multi-path Propagation (MP-DPD) in this paper. MP-DPD adds non-negative real path attenuation constraints to avoid the mistake caused by the singularity of the array manifold. The Multi-path Propagation MUSIC (MP-MUSIC) method and the Active Set Algorithm (ASA) are designed to reduce the dimension of searching. A Multi-path Propagation Maximum Likelihood (MP-ML) method is proposed in addition to overcome the limitation of MP-MUSIC in the sense of a time-sensitive application. An iterative algorithm and an approach of initial value setting are given to make the MP-ML time consumption acceptable. Numerical results validate the performances improvement of MP-MUSIC and MP-ML. A closed form of the Cramér–Rao Lower Bound (CRLB) is derived as a benchmark to evaluate the performances of MP-MUSIC and MP-ML. PMID:29562601

Direct Position Determination of Unknown Signals in the Presence of Multipath Propagation.

PubMed

Du, Jianping; Wang, Ding; Yu, Wanting; Yu, Hongyi

2018-03-17

A novel geolocation architecture, termed "Multiple Transponders and Multiple Receivers for Multiple Emitters Positioning System (MTRE)" is proposed in this paper. Existing Direct Position Determination (DPD) methods take advantage of a rather simple channel assumption (line of sight channels with complex path attenuations) and a simplified MUltiple SIgnal Classification (MUSIC) algorithm cost function to avoid the high dimension searching. We point out that the simplified assumption and cost function reduce the positioning accuracy because of the singularity of the array manifold in a multi-path environment. We present a DPD model for unknown signals in the presence of Multi-path Propagation (MP-DPD) in this paper. MP-DPD adds non-negative real path attenuation constraints to avoid the mistake caused by the singularity of the array manifold. The Multi-path Propagation MUSIC (MP-MUSIC) method and the Active Set Algorithm (ASA) are designed to reduce the dimension of searching. A Multi-path Propagation Maximum Likelihood (MP-ML) method is proposed in addition to overcome the limitation of MP-MUSIC in the sense of a time-sensitive application. An iterative algorithm and an approach of initial value setting are given to make the MP-ML time consumption acceptable. Numerical results validate the performances improvement of MP-MUSIC and MP-ML. A closed form of the Cramér-Rao Lower Bound (CRLB) is derived as a benchmark to evaluate the performances of MP-MUSIC and MP-ML.

Frequency specific brain networks in Parkinson's disease and comorbid depression.

PubMed

Qian, Long; Zhang, Yi; Zheng, Li; Fu, Xuemei; Liu, Weiguo; Shang, Yuqing; Zhang, Yaoyu; Xu, Yuanyuan; Liu, Yijun; Zhu, Huaiqiu; Gao, Jia-Hong

2017-02-01

The topological organization underlying the human brain was extensively investigated using resting-state functional magnetic resonance imaging, focusing on a low frequency of signal oscillation from 0.01 to 0.1 Hz. However, the frequency specificities with regard to the topological properties of the brain networks have not been fully revealed. In this study, a novel complementary ensemble empirical mode decomposition (CEEMD) method was used to separate the fMRI time series into five characteristic oscillations with distinct frequencies. Then, the small world properties of brain networks were analyzed for each of these five oscillations in patients (n = 67) with depressed Parkinson's disease (DPD, n = 20) , non-depressed Parkinson's disease (NDPD, n = 47) and healthy controls (HC, n = 46). Compared with HC, the results showed decreased network efficiency in characteristic oscillations from 0.05 to 0.12 Hz and from 0.02 to 0.05 Hz for the DPD and NDPD patients, respectively. Furthermore, compared with HC, the most significant inter-group difference across five brain oscillations was found in the basal ganglia (0.01 to 0.05 Hz) and paralimbic-limbic network (0.02 to 0.22 Hz) for the DPD patients, and in the visual cortex (0.02 to 0.05 Hz) for the NDPD patients. Compared with NDPD, the DPD patients showed reduced efficiency of nodes in the basal ganglia network (0.01 to 0.05 Hz). Our results demonstrated that DPD is characterized by a disrupted topological organization in large-scale brain functional networks. Moreover, the CEEMD analysis suggested a prominent dissociation in the topological organization of brain networks between DPD and NDPD in both space and frequency domains. Our findings indicated that these characteristic oscillatory activities in different functional circuits may contribute to distinct motor and non-motor components of clinical impairments in Parkinson's disease.

LAMMPS Implementation of Constant Energy Dissipative Particle Dynamics (DPD-E)

DTIC Science & Technology

2014-03-01

LAMMPS Implementation of Constant Energy Dissipative Particle Dynamics (DPD-E) by James P. Larentzos, John K. Brennan, Joshua D. Moore, and...MD 21005-5069 ARL-TR-6863 March 2014 LAMMPS Implementation of Constant Energy Dissipative Particle Dynamics (DPD-E) James P...13 September 2013 4. TITLE AND SUBTITLE LAMMPS Implementation of Constant Energy Dissipative Particle Dynamics (DPD-E) 5a. CONTRACT NUMBER 5b

Comparison of prototypic cases of depressive personality disorder and dysthymic disorder.

PubMed

Sprock, June; Fredendall, Laura

2008-12-01

Although depressive personality disorder (DPD) was included in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV; American Psychiatric Association, 1994) appendix as a proposed category needing further research, there are concerns that it overlaps excessively with dysthymic disorder (DD). The purpose of this investigation was to identify the characteristic features of representative patients with DPD and patients with DD, and to determine whether they could be distinguished by their symptoms. Two matched samples of psychologists (n=57, n=48) identified a prototypic patient with DPD or DD, provided demographic and treatment information about the patient, and rated the patient's symptoms on a series of mood and personality disorder symptoms taken from the DSM-IV and the literature. When composite descriptions were constructed using the highest rated symptoms, there was considerable overlap in symptoms of identified DPD and DD patients. The DSM-IV research criteria for DPD provided the best description of the DPD patients; however, there was a high degree of correlation between DPD and DD criteria sets. There was also considerable comorbidity, with the majority of the patients in both groups meeting criteria for DPD and DD. However, there was a significant difference in comorbid diagnoses (and other differences in family history, outcome, and treatment history that failed to reach the more stringent level of statistical significance, i.e., p<.001) suggesting that there may be some important differences between DPD and DD. Nevertheless, the symptom ratings imply blurred boundaries between DPD and DD, suggesting the need for clearer differentiation between the two disorders or the need to adopt an alternative model of classification. (c) 2008 Wiley Periodicals, Inc.

Effect of graphite particle size and content on the formation mechanism of detonation polycrystalline diamond

NASA Astrophysics Data System (ADS)

Tong, Y.; Cao, Y.; Liu, R.; Shang, S. Y.; Huang, F. L.

2018-03-01

The formation mechanism of detonation polycrystalline diamond (DPD) generated from the detonation of a mixed RDX/graphite explosive is investigated. It is found experimentally that the DPD conversion rate decreases with both the content and the particle size of the graphite. Moreover, the particle sizes of the generated DPD powder are analyzed, which shows that, with the decrease in the graphite particle size, the mean number diameter of DPD decreases, but the mean volume diameter increases. In addition, with the help of scanning electron microscopy, it is observed that the in situ phase change occurs in the graphite particles, by which the small particles combine to form numerous large DPD particles. Based on both the experimental data and the classical ZND detonation model, we divide such a DPD synthesis process into two stages: In the first stage, the in situ phase change from graphite to diamond is dominant, supplemented by some coalescence growth at high pressure and temperature, which is affected mainly by the detonation performance of the mixed explosive under consideration. In the second stage, the graphitization of DPD caused by the residual heat is dominant, which is affected mainly by the unloading rate of the particle temperature.

Depressive personality disorder, dysthymia, and their relationship to perfectionism.

PubMed

Huprich, Steven K; Porcerelli, John; Keaschuk, Rachel; Binienda, Juliann; Engle, Benjamin

2008-01-01

This paper reports the results of two studies in a nonclinical (n=105) and primary care outpatient sample (n=110), in which Depressive Personality Disorder (DPD), Dysthymia, and depression were assessed for their distinctive relationship with perfectionism. Results from both studies found that self-reported DPD, Dysthymia, and depressive symptoms were all intercorrelated, and that DPD, Dysthymia, and depressive symptoms were correlated with three dimensions of perfectionism-Concern over Mistakes, Doubts about Actions, and Parental Criticism. In the nonclinical sample, variance in measures of DPD was predicted by measures of perfectionism after controlling for depression and Dysthymia symptoms. A similar pattern of findings was observed in the primary care sample. This relationship with perfectionism did not occur when Dysthymia or depressive symptoms were predicted. Nevertheless, much of the variance in measures of DPD, Dysthymia, and depressive symptoms is associated with each other and not perfectionism. It is concluded that a common factor or set of factors underlies these disorders, but that DPD may be more strongly related to perfectionism than Dysthymia and depression. As a common factor(s) is identified, measures of DPD and Dysthymia may be refined, thereby increasing the discriminant validity of their measures.

GENETIC AND ENVIRONMENTAL CONTRIBUTIONS TO THE CO-OCCURRENCE OF DEPRESSIVE PERSONALITY DISORDER AND DSM-IV PERSONALITY DISORDERS

PubMed Central

Ørstavik, Ragnhild E.; Kendler, Kenneth S.; Røysamb, Espen; Czajkowski, Nikolai; Tambs, Kristian; Reichborn-Kjennerud, Ted

2012-01-01

One of the main controversies with regard to depressive personality disorder (DPD) concerns the co-occurrence with the established DSM-IV personality disorders (PDs). The main aim of this study was to examine to what extent DPD and the DSM-IV PDs share genetic and environmental risk factors, using multivariate twin modeling. The DSM-IV Structured Interview for Personality was applied to 2,794 young adult twins. Paranoid PD from Cluster A, borderline PD from Cluster B, and all three PDs from Cluster C were independently and significantly associated with DPD in multiple regression analysis. The genetic correlations between DPD and the other PDs were strong (.53–.83), while the environmental correlations were moderate (.36–.40). Close to 50% of the total variance in DPD was disorder specific. However, only 5% was due to disorder-specific genetic factors, indicating that a substantial part of the genetic vulnerability to DPD also increases the vulnerability to other PDs. PMID:22686231

Genetic and environmental contributions to the co-occurrence of depressive personality disorder and DSM-IV personality disorders.

PubMed

Ørstavik, Ragnhild E; Kendler, Kenneth S; Røysamb, Espen; Czajkowski, Nikolai; Tambs, Kristian; Reichborn-Kjennerud, Ted

2012-06-01

One of the main controversies with regard to depressive personality disorder (DPD) concerns the co-occurrence with the established DSM-IV personality disorders (PDs). The main aim of this study was to examine to what extent DPD and the DSM-IV PDs share genetic and environmental risk factors, using multivariate twin modeling. The DSM-IV Structured Interview for Personality was applied to 2,794 young adult twins. Paranoid PD from Cluster A, borderline PD from Cluster B, and all three PDs from Cluster C were independently and significantly associated with DPD in multiple regression analysis. The genetic correlations between DPD and the other PDs were strong (.53-.83), while the environmental correlations were moderate (.36-.40). Close to 50% of the total variance in DPD was disorder specific. However, only 5% was due to disorder-specific genetic factors, indicating that a substantial part of the genetic vulnerability to DPD also increases the vulnerability to other PDs.

Implicit Self-Esteem in Borderline Personality and Depersonalization Disorder

PubMed Central

Hedrick, Alexis N.; Berlin, Heather A.

2012-01-01

Self-perception is disrupted in people with borderline personality disorder (BPD) and depersonalization disorder (DPD), fluctuating with sudden shifts in affect in BPD and experienced as detached in DPD. Measures of implicit self-esteem (ISE), free from conscious control and presentation biases, may highlight how such disruptions of self-concept differentially affect these two populations on an unconscious level. We examined ISE using the Implicit Association Test, along with measures of emotion, behavior, and temperament, in BPD (n = 18), DPD (n = 18), and healthy control (n = 35) participants. DPD participants had significantly higher ISE and were more harm avoidant than BPD and control participants, while BPD participants had more “frontal” behaviors and impulsivity and less self-directedness and cooperativeness than DPD and control participants. Thus, while BPD and DPD commonly overlap in terms of dissociative symptoms and emotional irregularities, differences in self-esteem, behavior, and temperament can help identify where they diverge in terms of their cognition, behavior, and ultimately underlying neurobiology. PMID:22493585

Bottom-up derivation of conservative and dissipative interactions for coarse-grained molecular liquids with the conditional reversible work method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deichmann, Gregor; Marcon, Valentina; Vegt, Nico F. A. van der, E-mail: vandervegt@csi.tu-darmstadt.de

Molecular simulations of soft matter systems have been performed in recent years using a variety of systematically coarse-grained models. With these models, structural or thermodynamic properties can be quite accurately represented while the prediction of dynamic properties remains difficult, especially for multi-component systems. In this work, we use constraint molecular dynamics simulations for calculating dissipative pair forces which are used together with conditional reversible work (CRW) conservative forces in dissipative particle dynamics (DPD) simulations. The combined CRW-DPD approach aims to extend the representability of CRW models to dynamic properties and uses a bottom-up approach. Dissipative pair forces are derived frommore » fluctuations of the direct atomistic forces between mapped groups. The conservative CRW potential is obtained from a similar series of constraint dynamics simulations and represents the reversible work performed to couple the direct atomistic interactions between the mapped atom groups. Neopentane, tetrachloromethane, cyclohexane, and n-hexane have been considered as model systems. These molecular liquids are simulated with atomistic molecular dynamics, coarse-grained molecular dynamics, and DPD. We find that the CRW-DPD models reproduce the liquid structure and diffusive dynamics of the liquid systems in reasonable agreement with the atomistic models when using single-site mapping schemes with beads containing five or six heavy atoms. For a two-site representation of n-hexane (3 carbons per bead), time scale separation can no longer be assumed and the DPD approach consequently fails to reproduce the atomistic dynamics.« less

A DPYD variant (Y186C) in individuals of African ancestry associated with reduced DPD enzyme activity

PubMed Central

Offer, Steven M.; Lee, Adam M.; Mattison, Lori K.; Fossum, Croix; Wegner, Natalie J.; Diasio, Robert B.

2013-01-01

5-fluorouracil (5-FU) is used to treat many aggressive cancers, such as those of the colon, breast, and head & neck. The responses to 5-FU, both toxicity and efficacy, vary between racial groups, potentially due to variability in enzyme activity of dihydropyrimidine dehydrogenase (DPD, encoded by DPYD). In the present study, the genetic associations between DPYD variations and circulating mononuclear cell DPD enzyme activity were evaluated in 94 African American and 81 European American volunteers. The DPYD-Y186C variant was unique to individuals of African ancestry, and DPD activity was 46% reduced in carriers compared to non-carriers (279±35 compared to 514±168 pmol 5-FU min−1 mg−1; P=0.00029). 26% of the African Americans with reduced DPD activity in this study carried Y186C. In the African American cohort, following exclusion of Y186C carriers, homozygous carriers of C29R showed 27% higher DPD activity compared to non-carriers (609±152 and 480±152 pmol 5-FU min−1 mg−1, respectively; P=0.013). PMID:23588312

DOE Office of Scientific and Technical Information (OSTI.GOV)

Müller, Kathrin, E-mail: k.mueller@fz-juelich.de; Fedosov, Dmitry A., E-mail: d.fedosov@fz-juelich.de; Gompper, Gerhard, E-mail: g.gompper@fz-juelich.de

Smoothed dissipative particle dynamics (SDPD) combines two popular mesoscopic techniques, the smoothed particle hydrodynamics and dissipative particle dynamics (DPD) methods, and can be considered as an improved dissipative particle dynamics approach. Despite several advantages of the SDPD method over the conventional DPD model, the original formulation of SDPD by Español and Revenga (2003) [9], lacks angular momentum conservation, leading to unphysical results for problems where the conservation of angular momentum is essential. To overcome this limitation, we extend the SDPD method by introducing a particle spin variable such that local and global angular momentum conservation is restored. The new SDPDmore » formulation (SDPD+a) is directly derived from the Navier–Stokes equation for fluids with spin, while thermal fluctuations are incorporated similarly to the DPD method. We test the new SDPD method and demonstrate that it properly reproduces fluid transport coefficients. Also, SDPD with angular momentum conservation is validated using two problems: (i) the Taylor–Couette flow with two immiscible fluids and (ii) a tank-treading vesicle in shear flow with a viscosity contrast between inner and outer fluids. For both problems, the new SDPD method leads to simulation predictions in agreement with the corresponding analytical theories, while the original SDPD method fails to capture properly physical characteristics of the systems due to violation of angular momentum conservation. In conclusion, the extended SDPD method with angular momentum conservation provides a new approach to tackle fluid problems such as multiphase flows and vesicle/cell suspensions, where the conservation of angular momentum is essential.« less

Smoothed dissipative particle dynamics with angular momentum conservation

NASA Astrophysics Data System (ADS)

Müller, Kathrin; Fedosov, Dmitry A.; Gompper, Gerhard

2015-01-01

Smoothed dissipative particle dynamics (SDPD) combines two popular mesoscopic techniques, the smoothed particle hydrodynamics and dissipative particle dynamics (DPD) methods, and can be considered as an improved dissipative particle dynamics approach. Despite several advantages of the SDPD method over the conventional DPD model, the original formulation of SDPD by Español and Revenga (2003) [9], lacks angular momentum conservation, leading to unphysical results for problems where the conservation of angular momentum is essential. To overcome this limitation, we extend the SDPD method by introducing a particle spin variable such that local and global angular momentum conservation is restored. The new SDPD formulation (SDPD+a) is directly derived from the Navier-Stokes equation for fluids with spin, while thermal fluctuations are incorporated similarly to the DPD method. We test the new SDPD method and demonstrate that it properly reproduces fluid transport coefficients. Also, SDPD with angular momentum conservation is validated using two problems: (i) the Taylor-Couette flow with two immiscible fluids and (ii) a tank-treading vesicle in shear flow with a viscosity contrast between inner and outer fluids. For both problems, the new SDPD method leads to simulation predictions in agreement with the corresponding analytical theories, while the original SDPD method fails to capture properly physical characteristics of the systems due to violation of angular momentum conservation. In conclusion, the extended SDPD method with angular momentum conservation provides a new approach to tackle fluid problems such as multiphase flows and vesicle/cell suspensions, where the conservation of angular momentum is essential.

Processing the Interspecies Quorum-sensing Signal Autoinducer-2 (AI-2)

PubMed Central

Marques, João C.; Lamosa, Pedro; Russell, Caitlin; Ventura, Rita; Maycock, Christopher; Semmelhack, Martin F.; Miller, Stephen T.; Xavier, Karina B.

2011-01-01

The molecule (S)-4,5-dihydroxy-2,3-pentanedione (DPD) is produced by many different species of bacteria and is the precursor of the signal molecule autoinducer-2 (AI-2). AI-2 mediates interspecies communication and facilitates regulation of bacterial behaviors such as biofilm formation and virulence. A variety of bacterial species have the ability to sequester and process the AI-2 present in their environment, thereby interfering with the cell-cell communication of other bacteria. This process involves the AI-2-regulated lsr operon, comprised of the Lsr transport system that facilitates uptake of the signal, a kinase that phosphorylates the signal to phospho-DPD (P-DPD), and enzymes (like LsrG) that are responsible for processing the phosphorylated signal. Because P-DPD is the intracellular inducer of the lsr operon, enzymes involved in P-DPD processing impact the levels of Lsr expression. Here we show that LsrG catalyzes isomerization of P-DPD into 3,4,4-trihydroxy-2-pentanone-5-phosphate. We present the crystal structure of LsrG, identify potential catalytic residues, and determine which of these residues affects P-DPD processing in vivo and in vitro. We also show that an lsrG deletion mutant accumulates at least 10 times more P-DPD than wild type cells. Consistent with this result, we find that the lsrG mutant has increased expression of the lsr operon and an altered profile of AI-2 accumulation and removal. Understanding of the biochemical mechanisms employed by bacteria to quench signaling of other species can be of great utility in the development of therapies to control bacterial behavior. PMID:21454635

Processing the Interspecies Quorum-sensing Signal Autoinducer-2 (AI-2)

DOE Office of Scientific and Technical Information (OSTI.GOV)

J Marques; P Lamosa; C Russell

The molecule (S)-4,5-dihydroxy-2,3-pentanedione (DPD) is produced by many different species of bacteria and is the precursor of the signal molecule autoinducer-2 (AI-2). AI-2 mediates interspecies communication and facilitates regulation of bacterial behaviors such as biofilm formation and virulence. A variety of bacterial species have the ability to sequester and process the AI-2 present in their environment, thereby interfering with the cell-cell communication of other bacteria. This process involves the AI-2-regulated lsr operon, comprised of the Lsr transport system that facilitates uptake of the signal, a kinase that phosphorylates the signal to phospho-DPD (P-DPD), and enzymes (like LsrG) that are responsiblemore » for processing the phosphorylated signal. Because P-DPD is the intracellular inducer of the lsr operon, enzymes involved in P-DPD processing impact the levels of Lsr expression. Here we show that LsrG catalyzes isomerization of P-DPD into 3,4,4-trihydroxy-2-pentanone-5-phosphate. We present the crystal structure of LsrG, identify potential catalytic residues, and determine which of these residues affects P-DPD processing in vivo and in vitro. We also show that an lsrG deletion mutant accumulates at least 10 times more P-DPD than wild type cells. Consistent with this result, we find that the lsrG mutant has increased expression of the lsr operon and an altered profile of AI-2 accumulation and removal. Understanding of the biochemical mechanisms employed by bacteria to quench signaling of other species can be of great utility in the development of therapies to control bacterial behavior.« less

Verbal learning on depressive pseudodementia: accentuate impairment of free recall, moderate on learning processes, and spared short-term and recognition memory.

PubMed

Paula, Jonas Jardim de; Miranda, Débora Marques; Nicolato, Rodrigo; Moraes, Edgar Nunes de; Bicalho, Maria Aparecida Camargos; Malloy-Diniz, Leandro Fernandes

2013-09-01

Depressive pseudodementia (DPD) is a clinical condition characterized by depressive symptoms followed by cognitive and functional impairment characteristics of dementia. Memory complaints are one of the most related cognitive symptoms in DPD. The present study aims to assess the verbal learning profile of elderly patients with DPD. Ninety-six older adults (34 DPD and 62 controls) were assessed by neuropsychological tests including the Rey auditory-verbal learning test (RAVLT). A multivariate general linear model was used to assess group differences and controlled for demographic factors. Moderate or large effects were found on all RAVLT components, except for short-term and recognition memory. DPD impairs verbal memory, with large effect size on free recall and moderate effect size on the learning. Short-term storage and recognition memory are useful in clinical contexts when the differential diagnosis is required.

A dissipative particle dynamics method for arbitrarily complex geometries

NASA Astrophysics Data System (ADS)

Li, Zhen; Bian, Xin; Tang, Yu-Hang; Karniadakis, George Em

2018-02-01

Dissipative particle dynamics (DPD) is an effective Lagrangian method for modeling complex fluids in the mesoscale regime but so far it has been limited to relatively simple geometries. Here, we formulate a local detection method for DPD involving arbitrarily shaped geometric three-dimensional domains. By introducing an indicator variable of boundary volume fraction (BVF) for each fluid particle, the boundary of arbitrary-shape objects is detected on-the-fly for the moving fluid particles using only the local particle configuration. Therefore, this approach eliminates the need of an analytical description of the boundary and geometry of objects in DPD simulations and makes it possible to load the geometry of a system directly from experimental images or computer-aided designs/drawings. More specifically, the BVF of a fluid particle is defined by the weighted summation over its neighboring particles within a cutoff distance. Wall penetration is inferred from the value of the BVF and prevented by a predictor-corrector algorithm. The no-slip boundary condition is achieved by employing effective dissipative coefficients for liquid-solid interactions. Quantitative evaluations of the new method are performed for the plane Poiseuille flow, the plane Couette flow and the Wannier flow in a cylindrical domain and compared with their corresponding analytical solutions and (high-order) spectral element solution of the Navier-Stokes equations. We verify that the proposed method yields correct no-slip boundary conditions for velocity and generates negligible fluctuations of density and temperature in the vicinity of the wall surface. Moreover, we construct a very complex 3D geometry - the "Brown Pacman" microfluidic device - to explicitly demonstrate how to construct a DPD system with complex geometry directly from loading a graphical image. Subsequently, we simulate the flow of a surfactant solution through this complex microfluidic device using the new method. Its effectiveness is demonstrated by examining the rich dynamics of surfactant micelles, which are flowing around multiple small cylinders and stenotic regions in the microfluidic device without wall penetration. In addition to stationary arbitrary-shape objects, the new method is particularly useful for problems involving moving and deformable boundaries, because it only uses local information of neighboring particles and satisfies the desired boundary conditions on-the-fly.

Clinical response to dorsal duct drainage via the minor papilla in refractory obstructing chronic calcific pancreatitis

PubMed Central

Kwon, Chang-Il; Gromski, Mark A.; Sherman, Stuart; El Hajj, Ihab I.; Easler, Jeffrey J.; Watkins, James; McHenry, Lee; Lehman, Glen A.; Fogel, Evan L.

2017-01-01

Background and study aims Complete stone removal from the main pancreatic duct might not be achieved in all patients with obstructive chronic calcific pancreatitis. We report our results for endoscopic dorsal pancreatic duct (DPD) bypass of obstructing stones in the ventral pancreatic duct (VPD). Patients and methods 16 patients with obstructive chronic calcific pancreatitis were treated with a DPD bypass. Clinical success was defined as significant pain relief and no hospital admissions for pain management during the ongoing treatment period. Results Among 16 patients meeting entry criteria, 10 (62.5%) had a history of unsuccessful endoscopic therapy, and 8 had failed extracorporeal shockwave lithotripsy (ESWL). Clinical success was achieved in 12 patients (75 %). Among these responders, 10 patients (83.3 %) had markedly improved or complete pain relief after the first stent placement, which persisted throughout the follow-up period; 11 patients (91.7 %) were able to discontinue their daily analgesics. Conclusions In selected patients with obstructive chronic calcific pancreatitis, the DPD bypass may be considered as a rescue endoscopic therapy, potentially obviating the need for surgery when standard endoscopic methods and ESWL fail. PMID:28201840

Using Resistivity to Measure H/Pd and D/Pd Loading:. Method and Significance

NASA Astrophysics Data System (ADS)

McKubre, M. C. H.; Tanzella, F. L.

The resistance ratio method is the most frequent technique used to determine the extent of interstitial loading of hydrogen or deuterium atoms into palladium electrodes, or extended structures used in electrolytic or gas phase cold fusion experiments. Specifically, advantage is taken of an empirical relationship between the measured resistance, R, normalized to that of the same body at the same temperature in the absence of hydrogen isotope, R0, hence R/R0, and the atomic fraction occupancy of octahedral interstitials, x = H/Pd or D/Pd. This method was first suggested and employed in cold fusion studies by the present authors, and received immediate and widespread acceptance because of the ease with which this experimental technique could be used to make in situ, real-time measurements of a parameter, D/Pd, anticipated or hypothesized at that time to relate to cold fusion heat excess or nuclear production. We take up this topic again 15 years later in an attempt to clear up some errors and misunderstandings regarding the resistance ratio method and its application in cold fusion studies. The relationship between R/R0 and x is empirical. That is, calibrations are only as good as the experiments that support the shape of the curve and cannot be used outside the range (P, T, x) in which data are taken. The original calibration (unaccountably and erroneously immortalized as the "famous Baranowski curve") involved an extrapolation of known data into the region of cold fusion interest in the D-Pd system, at x > 0.6. Present theory and results focus new attention on the very high loading region as x approaches or even exceeds unity, where double occupation of octahedral sites, tetrahedral site occupancy, new phase formation or new electrical states, may be relevant to the underlying physical process of excess heat and nuclear production. Rather than simply using the resistance ratio as a qualitative tool to determine whether an electrode is better or lesser loaded, it is now important to obtain accurate quantitative information for x close to unity. With further experimentation and analysis of published data it is apparent that the curve originally published in 1990 is in error in the high loading condition. This paper describes how this empirical fit has been improved over the years for both H/Pd and D/Pd by employing new data, new analysis of old data, new experimental methods and results.

Conserving the linear momentum in stochastic dynamics: Dissipative particle dynamics as a general strategy to achieve local thermostatization in molecular dynamics simulations.

PubMed

Passler, Peter P; Hofer, Thomas S

2017-02-15

Stochastic dynamics is a widely employed strategy to achieve local thermostatization in molecular dynamics simulation studies; however, it suffers from an inherent violation of momentum conservation. Although this short-coming has little impact on structural and short-time dynamic properties, it can be shown that dynamics in the long-time limit such as diffusion is strongly dependent on the respective thermostat setting. Application of the methodically similar dissipative particle dynamics (DPD) provides a simple, effective strategy to ensure the advantages of local, stochastic thermostatization while at the same time the linear momentum of the system remains conserved. In this work, the key parameters to employ the DPD thermostats in the framework of periodic boundary conditions are investigated, in particular the dependence of the system properties on the size of the DPD-region as well as the treatment of forces near the cutoff. Structural and dynamical data for light and heavy water as well as a Lennard-Jones fluid have been compared to simulations executed via stochastic dynamics as well as via use of the widely employed Nose-Hoover chain and Berendsen thermostats. It is demonstrated that a small size of the DPD region is sufficient to achieve local thermalization, while at the same time artifacts in the self-diffusion characteristic for stochastic dynamics are eliminated. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Using drug sales data to evaluate the epidemiology of cardiometabolic risk factors and their inequality: an ecological study on atorvastatin and total cholesterol in Iran.

PubMed

Ahmadvand, Alireza; Farzadfar, Farshad; Jamshidi, Hamid Reza; Mohammadi, Naser; Holakouie-Naieni, Kourosh

2015-01-01

Statins have been effective medications in lowering serum total cholesterol (TC) concentrations across populations over time. The aim of this study was to estimate national and provincial trends in atorvastatin sales in Iran, to systematically quantify its relationship with socioeconomic indicators, and changes in TC level. In this retrospective ecological study, conducted in Iran, we examined trends in atorvastatin sales, the wealth index (WI) as a validly-available socio-economic indicator, and TC level between 2004 and 2011. The main outcome variable was mean atorvastatin sold in defined daily dose per 100,000 people per day (DPD). We analyzed the relationship between WI and DPD and between DPD and mean TC across time and space. At national level, both mean WI and mean DPD showed increasing trend over time, while we observed decreasing trend for TC. Mean WI and DPD in 2011 was nearly 5 and 50 time that of their respective figures in 2004, while the mean TC decreased for nearly 10%. Increases in both WI and DPD had happened in every province, but with different patterns. The maximum and minimum changes in DPD versus WI were seen in Gilan and North Khorasan respectively. A striking increase occurred in the sales for atorvastatin in Iran from 2004-2012 in most provinces examined. The wealthier a province became, the more sales were seen for atorvastatin. TC optimistically decreased from 2005 to 2011 and its decrease was positively correlated with increasing sales for atorvastatin.

Hidden Sylvatic Foci of the Main Vector of Chagas Disease Triatoma infestans: Threats to the Vector Elimination Campaign?

PubMed Central

Schachter-Broide, Judith; Dujardin, Jean-Pierre; Dotson, Ellen M.; Kitron, Uriel; Gürtler, Ricardo E.

2011-01-01

Background Establishing the sources of reinfestation after residual insecticide spraying is crucial for vector elimination programs. Triatoma infestans, traditionally considered to be limited to domestic or peridomestic (abbreviated as D/PD) habitats throughout most of its range, is the target of an elimination program that has achieved limited success in the Gran Chaco region in South America. Methodology/Principal Findings During a two-year period we conducted semi-annual searches for triatomine bugs in every D/PD site and surrounding sylvatic habitats after full-coverage spraying of pyrethroid insecticides of all houses in a well-defined rural area in northwestern Argentina. We found six low-density sylvatic foci with 24 T. infestans in fallen or standing trees located 110–2,300 m from the nearest house or infested D/PD site detected after insecticide spraying, when house infestations were rare. Analysis of two mitochondrial gene fragments of 20 sylvatic specimens confirmed their species identity as T. infestans and showed that their composite haplotypes were the same as or closely related to D/PD haplotypes. Population studies with 10 polymorphic microsatellite loci and wing geometric morphometry consistently indicated the occurrence of unrestricted gene flow between local D/PD and sylvatic populations. Mitochondrial DNA and microsatellite sibship analyses in the most abundant sylvatic colony revealed descendents from five different females. Spatial analysis showed a significant association between two sylvatic foci and the nearest D/PD bug population found before insecticide spraying. Conclusions Our study shows that, despite of its high degree of domesticity, T. infestans has sylvatic colonies with normal chromatic characters (not melanic morphs) highly connected to D/PD conspecifics in the Argentinean Chaco. Sylvatic habitats may provide a transient or permanent refuge after control interventions, and function as sources for D/PD reinfestation. The occurrence of sylvatic foci of T. infestans in the Gran Chaco may pose additional threats to ongoing vector elimination efforts. PMID:22039559

Deoxypyridinoline in the Urine of Rats with Unloaded Hindlimbs

NASA Technical Reports Server (NTRS)

Arnaud, Sara B.; Navidi, M.; Wren, J.; Holton, Emily M. (Technical Monitor)

1997-01-01

The urinary excretion of deoxypyridinoline (U-Dpd), a nonreducible collagen crosslink in bone released by osteoclastic activity, is thought to be an accurate marker of bone resorption. The role of increased resorption in the osteopenia of a space flight model which unloads the hindlimbs by suspending the tail is controversial. To assess skeletal resorption in the model we measured U-Dpd (Pyrilinks-D, Metro Biosystems, Inc.) in serial 24 hour urine specimens collected from 250 a (Y) and 450 a (M) male rats with unloaded hindlimbs for four weeks. Both groups of rats were fed AIN76 diets with calcium restricted to 0.2% in Y and to 0.1 % in M. Blood was obtained after 28 days for parathyroid hormone (PTH), 1,25-dihydroxyvitamin D (1,25-D) and alkaline phosphatase (Alkptase). Basal U-Dpd was higher and more variable in Y than M (475+/-200 vs 67+/-9, nM/mM creatinine, p<.001). Repeated measures ANOVA in Y revealed decreases in U-Dpd, 36% in control (C) and 24% in unloaded (S) rats (p<.005). There was a nadir in YS on the 14th day not observed in YC (p<.05). U-Dpd in MC showed no change, but increased in MS by the 14th day and remained elevated. At the end of the experiment, body weights in both Y and M were less in S than C (337+/-16 vs 306+/-12g and 485+/-10 vs 461+/-6g, p=.002). Bill was inversely related to U-Dpd only in M (r=0.699, p=.024). PTH, similar in C and S in Y (52+/-15 vs 42+/-7pg/ml, NS) and M (68+/-13 vs 61+/-12, NS), was unrelated to U-Dpd. 1,25-D tended toward higher values in YC than YS (197+/-103 vs 119+/-30, NS) and correlated with U-Dpd (0.773, p=.015). Alkptase, 1.3 times higher in Y than M, was similar in C and S at the end of unloading. These findings indicate that bone resorption, as reflected by U-Dpd, is suppressed in young and stimulated in mature rats exposed to a space flight model. U-Dpd reflects reduced growth from the diet change in young control and experimental rats and loss of Bill in mature animals exposed to the space flight model, 2 situations with opposite effects on bone resorption.

Influence of Dissipative Particle Dynamics parameters and wall models on planar micro-channel flows

NASA Astrophysics Data System (ADS)

Wang, Yuyi; She, Jiangwei; Zhou, Zhe-Wei; microflow Group Team

2017-11-01

Dissipative Particle Dynamics (DPD) is a very effective approach in simulating mesoscale hydrodynamics. The influence of solid boundaries and DPD parameters are typically very strong in DPD simulations. The present work studies a micro-channel Poisseuille flow. Taking the neutron scattering experiment and molecular dynamics simulation result as bench mark, the DPD results of density distribution and velocity profile are systematically studied. The influence of different levels of coarse-graining, the number densities of wall and fluid, conservative force coefficients, random and dissipative force coefficients, different wall model and reflective boundary conditions are discussed. Some mechanisms behind such influences are discussed and the artifacts in the simulation are identified with the bench mark. Chinese natural science foundation (A020405).

White matter network alterations in patients with depersonalization/derealization disorder.

PubMed

Sierk, Anika; Daniels, Judith K; Manthey, Antje; Kok, Jelmer G; Leemans, Alexander; Gaebler, Michael; Lamke, Jan-Peter; Kruschwitz, Johann; Walter, Henrik

2018-06-06

Depersonalization/derealization disorder (DPD) is a chronic and distressing condition characterized by detachment from oneself and/or the external world. Neuroimaging studies have associated DPD with structural and functional alterations in a variety of distinct brain regions. Such local neuronal changes might be mediated by altered interregional white matter connections. However, to our knowledge, no research on network characteristics in this patient population exists to date. We explored the structural connectome in 23 individuals with DPD and 23 matched, healthy controls by applying graph theory to diffusion tensor imaging data. Mean interregional fractional anisotropy (FA) was used to define the network weights. Group differences were assessed using network-based statistics and a link-based controlling procedure. Our main finding refers to lower FA values within left temporal and right temporoparietal regions in individuals with DPD than in healthy controls when using a link-based controlling procedure. These links were also associated with dissociative symptom severity and could not be explained by anxiety or depression scores. Using network-based statistics, no significant results emerged. However, we found a trend for 1 subnetwork that may support the model of frontolimbic dysbalance suggested to underlie DPD symptomatology. To ensure ecological validity, patients with certain comorbidities or psychotropic medication were included in the study. Confirmatory replications are necessary to corroborate the results of this explorative investigation. In patients with DPD, the structural connectivity between brain regions crucial for multimodal integration and emotion regulation may be altered. Aberrations in fibre tract communication seem to be not solely a secondary effect of local grey matter volume loss, but may present a primary pathophysiology in patients with DPD.

5-ethynyl-2(1H)-pyrimidinone: aldehyde oxidase-activation to 5-ethynyluracil, a mechanism-based inactivator of dihydropyrimidine dehydrogenase.

PubMed

Porter, D J; Harrington, J A; Almond, M R; Lowen, G T; Zimmerman, T P; Spector, T

1994-03-29

5-Ethynyluracil is a potent mechanism-based inactivator of dihydropyrimidine dehydrogenase (DPD, EC 1.3.1.2) in vitro (Porter et al., J Biol Chem 267: 5236-5242, 1992) and in vivo (Spector et al., Biochem Pharmacol, 46: 2243-2248, 1993. 5-Ethynyl-2(1H)-pyrimidinone was rapidly oxidized to 5-ethynyluracil by aldehyde oxidase. The substrate efficiency (kcat/Km) was 60-fold greater than that for N-methylnicotinamide. In contrast, xanthine oxidase oxidized 5-ethynyl-2(1H)-pyrimidinone to 5-ethynyluracil with a substrate efficiency that was only 0.02% that of xanthine. Because 5-ethynyl-2(1H)-pyrimidinone did not itself inactivate purified DPD in vitro and aldehyde oxidase is predominately found in liver, we hypothesized that 5-ethynyl-2(1H)-pyrimidinone could be a liver-specific inactivator of DPD. We found that 5-ethynyl-2(1H)-pyrimidinone administered orally to rats at 2 micrograms/kg inactivated DPD in all tissues studied. Although 5-ethynyl-2(1H)-pyrimidinone produced slightly less inactivation than 5-ethynyluracil, the two compounds showed fairly similar patterns of inactivation of DPD in these tissues. At doses of 20 micrograms/kg, however, 5-ethynyl-2-pyrimidinone and 5-ethynyluracil produced equivalent inactivation of DPD. Thus, 5-ethynyl-2(1H)-pyrimidinone appeared to be an efficient, but not highly liver-selective prodrug of 5-ethynyluracil.

Correlation between three-dimensional power Doppler and morphometric measurement of endometrial vascularity at the time of embryo implantation in women with unexplained recurrent miscarriage.

PubMed

Chen, Xiaoyan; Saravelos, Sotirios H; Liu, Yingyu; Huang, Jin; Wang, Chi Chiu; Li, Tin Chiu

2017-06-01

Power Doppler in combination with three-dimensional (3D-PD) ultrasonography has been used as a noninvasive tool to evaluate the vascularity. However, it is unclear whether 3D-PD can accurately reflect endometrial vascularization and replace the invasive endometrial biopsy. This study aims to investigate the correlation between 3D-PD and micro vessel morphometric measurement of endometrial vascularity. Twenty-five women with unexplained recurrent miscarriage were recruited for 3D-PD and endometrial biopsy on precisely day LH + 7. Immunohistochemistry using vWF was employed to identify micro vessels in endometrial biopsy specimens followed by the use of morphometric technique to measure the mean vessel diameter and volume fractions. The vascularization index (VI), flow index (FI) and vascularization flow index (VFI) assessed by 3D-PD were calculated for both the endometrial and sub-endometrial regions. There were no significant correlations between any of the ultrasonographic measurements (endometrial thickness, endometrial volume, endometrial VI/FI/VFI, sub-endometrial volume, sub-endometrial VI/FI/VFI) and morphometric features (number of micro vessel, mean diameter of micro vessel and volume fraction measurement of vessel). This study indicates that endometrial vascularity assessed by 3D-PD could not be used to reflect changes in micro vessels of the endometrium at the time of embryo implantation in women with unexplained recurrent miscarriage.

Dependent personality disorder: a critical review.

PubMed

Disney, Krystle L

2013-12-01

Dependent personality disorder (DPD) has evolved from an abstract idea rooted in a historic and psychoanalytic context to a codified diagnosis in the DSM-IV-TR. This comprehensive review paper chronicles the evolution of DPD through each version of the DSM. Major topics relevant to the disorder are also investigated, including gender and cultural considerations, stability and manifestations of DPD across different developmental stages, comorbidity issues, and others. The purpose of this review is to provide a broad yet comprehensive examination of the complex angles of maladaptive dependency and to identify essential next steps in furthering our knowledge of this disorder. The paper concludes with a discussion of shortcomings in the body of research relevant to DPD, along with specific suggestions for improvement in this field of study. © 2013.

Multi-scale coarse-graining of non-conservative interactions in molecular liquids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Izvekov, Sergei, E-mail: sergiy.izvyekov.civ@mail.mil; Rice, Betsy M.

2014-03-14

A new bottom-up procedure for constructing non-conservative (dissipative and stochastic) interactions for dissipative particle dynamics (DPD) models is described and applied to perform hierarchical coarse-graining of a polar molecular liquid (nitromethane). The distant-dependent radial and shear frictions in functional-free form are derived consistently with a chosen form for conservative interactions by matching two-body force-velocity and three-body velocity-velocity correlations along the microscopic trajectories of the centroids of Voronoi cells (clusters), which represent the dissipative particles within the DPD description. The Voronoi tessellation is achieved by application of the K-means clustering algorithm at regular time intervals. Consistently with a notion of many-bodymore » DPD, the conservative interactions are determined through the multi-scale coarse-graining (MS-CG) method, which naturally implements a pairwise decomposition of the microscopic free energy. A hierarchy of MS-CG/DPD models starting with one molecule per Voronoi cell and up to 64 molecules per cell is derived. The radial contribution to the friction appears to be dominant for all models. As the Voronoi cell sizes increase, the dissipative forces rapidly become confined to the first coordination shell. For Voronoi cells of two and more molecules the time dependence of the velocity autocorrelation function becomes monotonic and well reproduced by the respective MS-CG/DPD models. A comparative analysis of force and velocity correlations in the atomistic and CG ensembles indicates Markovian behavior with as low as two molecules per dissipative particle. The models with one and two molecules per Voronoi cell yield transport properties (diffusion and shear viscosity) that are in good agreement with the atomistic data. The coarser models produce slower dynamics that can be appreciably attributed to unaccounted dissipation introduced by regular Voronoi re-partitioning as well as by larger numerical errors in mapping out the dissipative forces. The framework presented herein can be used to develop computational models of real liquids which are capable of bridging the atomistic and mesoscopic scales.« less

Cardiovascular diseases in older patients with osteoporotic hip fracture: prevalence, disturbances in mineral and bone metabolism, and bidirectional links

PubMed Central

Fisher, A; Srikusalanukul, W; Davis, M; Smith, P

2013-01-01

Background Considerable controversy exists regarding the contribution of mineral/bone metabolism abnormalities to the association between cardiovascular diseases (CVDs) and osteoporotic fractures. Aims and methods To determine the relationships between mineral/bone metabolism biomarkers and CVD in 746 older patients with hip fracture, clinical data were recorded and serum concentrations of parathyroid hormone (PTH), 25-hydroxyvitamin D, calcium, phosphate, magnesium, troponin I, parameters of bone turnover, and renal, liver, and thyroid functions were measured. Results CVDs were diagnosed in 472 (63.3%) patients. Vitamin D deficiency was similarly prevalent in patients with (78.0%) and without (82.1%) CVD. The CVD group had significantly higher mean PTH concentrations (7.6 vs 6.0 pmol/L, P < 0.001), a higher prevalence of secondary hyperparathyroidism (SPTH) (PTH > 6.8 pmol/L, 43.0% vs 23.3%, P < 0.001), and excess bone resorption (urinary deoxypyridinoline corrected by creatinine [DPD/Cr] > 7.5 nmol/μmol, 87.9% vs 74.8%, P < 0.001). In multivariate regression analysis, SHPT (odds ratio [OR] 2.6, P = 0.007) and high DPD/Cr (OR 2.8, P = 0.016) were independent indictors of CVD. Compared to those with both PTH and DPD/Cr in the normal range, multivariate-adjusted ORs for the presence of CVD were 17.3 (P = 0.004) in subjects with SHPT and 9.7 (P < 0.001) in patients with high DPD/Cr. CVD was an independent predicator of SHPT (OR 2.8, P = 0.007) and excess DPD/Cr (OR 2.5, P = 0.031). CVD was predictive of postoperative myocardial injury, while SHPT was also an independent predictor of prolonged hospital stay and in-hospital death. Conclusion SHPT and excess bone resorption are independent pathophysiological mediators underlying the bidirectional associations between CVD and hip fracture, and therefore are important diagnostic and therapeutic targets. PMID:23460043

Combined Analyses of hENT1, TS, and DPD Predict Outcomes of Borderline-resectable Pancreatic Cancer.

PubMed

Yabushita, Yasuhiro; Mori, Ryutaro; Taniguchi, Koichi; Matsuyama, Ryusei; Kumamoto, Takafumi; Sakamaki, Kentaro; Kubota, Kensuke; Endo, Itaru

2017-05-01

Predicting chemosensitivity to neoadjuvant chemoradiotherapy (NACRT) in pancreatic cancer is desired. The present study aimed to examine the relationship between intratumoral expression of human equilibrative nucleoside transporter 1 (hENT1), thymidylate synthase (TS), and dihydropyrimidine dehydrogenase (DPD) and the outcomes of NACRT with gemcitabine (GEM) combined with S-1 in patients with borderline-resectable pancreatic cancer (BRPC). Forty-seven patients who underwent NACRT with GEM plus S-1, following curative surgery, were recruited in our Institution between 2009 and 2012. Immunohistochemical expressions of hENT1, TS, and DPD in fine-needle aspiration (FNA) biopsies and resected specimens were examined. The correlation between these enzyme expressions and long-term outcome was analyzed. In 21 FNA specimens, no relationship between clinical responses to NACRT and long-term survival was found. However, in 47 resected specimens, patients were classified according to the number of favorable hENT1, TS, and DPD expression factors (hENT1 positive/TS negative/DPD negative). The presence of three favorable factors was strongly associated with improved partial response rates to NACRT (p=0.002). Patients with 2 or more favorable factors showed a significantly longer overall survival than the other patients (p=0.002). Combined expression analyses of hENT1, TS, and DPD may predict long-term outcomes in patients with BRPC after NACRT. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

White matter microstructure changes in the thalamus in Parkinson disease with depression: A diffusion tensor MR imaging study.

PubMed

Li, W; Liu, J; Skidmore, F; Liu, Y; Tian, J; Li, K

2010-11-01

Depression occurs frequently in PD; however the neural basis of depression in PD remains unclear. The aim of this study was to characterize possible depression-related white matter microstructural changes in the thalamus of patients with DPD compared with those with NDPD. FA and MD maps from DTI were obtained in 14 patients with DPD and 18 patients with NDPD. Region-of-interest-guided VBA was conducted on the FA maps to detect possible microstructural differences in the thalamus between these 2 patient groups. Moreover, mean FA and MD in regions with a detected difference were compared between DPD and NDPD groups, and correlations between diffusion quantities and the severity of depression were analyzed. White matter microstructure differences were found between the patients with DPD and NDPD in the bilateral mediodorsal thalamic regions. In these regions, patients with DPD showed significantly decreased FA values (P < .005) compared with patients with NDPD, and the mean values of FA were negatively correlated with the scores of depression severity (P < .05) for patients with PD. No significant differences of MD were found in the mediodorsal thalamus between these 2 groups. Our results provide preliminary evidence that the mediodorsal thalamus may play an important role in depression in PD and suggest a relationship between FA in the mediodorsal thalamus and the presence of depressive symptoms in patients with DPD. These findings may be helpful for further understanding the potential mechanisms of depression in PD.

Multiscale Universal Interface: A concurrent framework for coupling heterogeneous solvers

NASA Astrophysics Data System (ADS)

Tang, Yu-Hang; Kudo, Shuhei; Bian, Xin; Li, Zhen; Karniadakis, George Em

2015-09-01

Concurrently coupled numerical simulations using heterogeneous solvers are powerful tools for modeling multiscale phenomena. However, major modifications to existing codes are often required to enable such simulations, posing significant difficulties in practice. In this paper we present a C++ library, i.e. the Multiscale Universal Interface (MUI), which is capable of facilitating the coupling effort for a wide range of multiscale simulations. The library adopts a header-only form with minimal external dependency and hence can be easily dropped into existing codes. A data sampler concept is introduced, combined with a hybrid dynamic/static typing mechanism, to create an easily customizable framework for solver-independent data interpretation. The library integrates MPI MPMD support and an asynchronous communication protocol to handle inter-solver information exchange irrespective of the solvers' own MPI awareness. Template metaprogramming is heavily employed to simultaneously improve runtime performance and code flexibility. We validated the library by solving three different multiscale problems, which also serve to demonstrate the flexibility of the framework in handling heterogeneous models and solvers. In the first example, a Couette flow was simulated using two concurrently coupled Smoothed Particle Hydrodynamics (SPH) simulations of different spatial resolutions. In the second example, we coupled the deterministic SPH method with the stochastic Dissipative Particle Dynamics (DPD) method to study the effect of surface grafting on the hydrodynamics properties on the surface. In the third example, we consider conjugate heat transfer between a solid domain and a fluid domain by coupling the particle-based energy-conserving DPD (eDPD) method with the Finite Element Method (FEM).

Multiscale Universal Interface: A concurrent framework for coupling heterogeneous solvers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Yu-Hang, E-mail: yuhang_tang@brown.edu; Kudo, Shuhei, E-mail: shuhei-kudo@outlook.jp; Bian, Xin, E-mail: xin_bian@brown.edu

2015-09-15

Graphical abstract: - Abstract: Concurrently coupled numerical simulations using heterogeneous solvers are powerful tools for modeling multiscale phenomena. However, major modifications to existing codes are often required to enable such simulations, posing significant difficulties in practice. In this paper we present a C++ library, i.e. the Multiscale Universal Interface (MUI), which is capable of facilitating the coupling effort for a wide range of multiscale simulations. The library adopts a header-only form with minimal external dependency and hence can be easily dropped into existing codes. A data sampler concept is introduced, combined with a hybrid dynamic/static typing mechanism, to create anmore » easily customizable framework for solver-independent data interpretation. The library integrates MPI MPMD support and an asynchronous communication protocol to handle inter-solver information exchange irrespective of the solvers' own MPI awareness. Template metaprogramming is heavily employed to simultaneously improve runtime performance and code flexibility. We validated the library by solving three different multiscale problems, which also serve to demonstrate the flexibility of the framework in handling heterogeneous models and solvers. In the first example, a Couette flow was simulated using two concurrently coupled Smoothed Particle Hydrodynamics (SPH) simulations of different spatial resolutions. In the second example, we coupled the deterministic SPH method with the stochastic Dissipative Particle Dynamics (DPD) method to study the effect of surface grafting on the hydrodynamics properties on the surface. In the third example, we consider conjugate heat transfer between a solid domain and a fluid domain by coupling the particle-based energy-conserving DPD (eDPD) method with the Finite Element Method (FEM)« less

Conditional reasoning in Asperger's syndrome and depersonalization disorder.

PubMed

Lawrence, Emma Jane; Dumigan, Rachael; Schoenberg, Poppy; Mauricio, Sierra; Murphy, Declan G; David, Anthony S

2012-09-01

Conditional reasoning premises can be systematically manipulated to elicit specific response patterns. This is useful for investigating the reasoning style of people who report clinical symptoms. We administered a standardized conditional reasoning task to 16 participants with a diagnosis of Asperger's syndrome (AS), 16 participants with a diagnosis of depersonalization disorder (DPD), and 32 intelligence-quotient-matched controls. Premises were manipulated for a) context, with some being embedded within extra statements, and b) content, neutral or emotional. Both the AS and DPD participants were less likely to incorporate exceptions to the given premises than the controls, indicating difficulties with mental flexibility, although this effect was less marked in the DPD group. It seems the AS participants were also less influenced than the controls by statements that highlight possible alternative consequences. However, this effect was less robust than that observed with statements detailing exceptions, suggesting it may be because of general problems with executive function rather than difficulties in processing contextual information. We did not observe the expected difference between the DPD participants and the controls when reasoning with emotional premises. Overall, these data suggest that the DPD and AS participants have distinct reasoning styles, which may be of use for interventions based on cognitive change.

Degenerate pressure driven self-gravito-acoustic solitary waves in a self-gravitating degenerate quantum plasma system

NASA Astrophysics Data System (ADS)

Mamun, A. A.

2018-02-01

A general (but realistic) self-gravitating degenerate quantum plasma system (SG-DQPS) containing inertialess degenerate electron species, inertial degenerate light, and heavy ion/nucleus species is considered to examine the possibility for the existence of degenerate pressure driven self-gravito-acoustic (DPD-SGA) solitary waves (SWs) formed in such a SG-DQPS. The pseudo-potential approach, which is valid for the arbitrary amplitude DPD-SGA SWs, is employed. It is found that depending on the value of the number density of heavy ion/nucleus species, the SG-DQPS under consideration supports the existence of positive or the coexistence of positive and negative DPD-SGA SWs. The basic features (polarity, amplitude, and width) of both positive and negative DPD-SGA SWs are found to be significantly modified by the dynamics of heavy ion/nucleus species. The theoretical investigation presented here is so general that it can be applied not only in astrophysical SG-DQPSs (such as white dwarf and neutron star SG-DQPSs), but also in laboratory SG-DQPSs (viz., solid density and laser-produced SG-DQPSs) to identify the salient features of the DPD-SGA SWs formed in them.

Psychophysiological investigations in depersonalization disorder and effects of electrodermal biofeedback.

PubMed

Schoenberg, Poppy L A; Sierra, Mauricio; David, Anthony S

2012-01-01

Previous studies investigating depersonalization disorder (DPD) report a lower baseline skin conductance level (SCL) and attenuated skin conductance response (SCR) to emotive stimuli. We hypothesized that increasing physiological arousal levels via electrodermal biofeedback may ameliorate disembodiment and emotional numbing symptomatology. Real-time versus sham biofeedback yielded a significant SCL increase after just 3 real-time biofeedback sessions in healthy volunteers. Subsequently, a randomized controlled biofeedback trial was administered with DPD patients. Findings were not replicated as SCL tended to fall, curiously more substantially in the real-time condition, concomitant with increased low- and high-frequency heart rate variability. To further investigate abnormal autonomic regulation in DPD, we compared basal autonomic activity between patients and healthy volunteers and found the former to be significantly more labile, indexed by greater nonspecific SCRs and higher resting SCLs. Rather than low sympathetic arousal, DPD might be better characterized by abnormal autonomic regulation affecting emotional and physiological responsivity.

Danish Palliative Care Database.

PubMed

Groenvold, Mogens; Adsersen, Mathilde; Hansen, Maiken Bang

2016-01-01

The aim of the Danish Palliative Care Database (DPD) is to monitor, evaluate, and improve the clinical quality of specialized palliative care (SPC) (ie, the activity of hospital-based palliative care teams/departments and hospices) in Denmark. The study population is all patients in Denmark referred to and/or in contact with SPC after January 1, 2010. The main variables in DPD are data about referral for patients admitted and not admitted to SPC, type of the first SPC contact, clinical and sociodemographic factors, multidisciplinary conference, and the patient-reported European Organisation for Research and Treatment of Cancer Quality of Life Questionaire-Core-15-Palliative Care questionnaire, assessing health-related quality of life. The data support the estimation of currently five quality of care indicators, ie, the proportions of 1) referred and eligible patients who were actually admitted to SPC, 2) patients who waited <10 days before admission to SPC, 3) patients who died from cancer and who obtained contact with SPC, 4) patients who were screened with European Organisation for Research and Treatment of Cancer Quality of Life Questionaire-Core-15-Palliative Care at admission to SPC, and 5) patients who were discussed at a multidisciplinary conference. In 2014, all 43 SPC units in Denmark reported their data to DPD, and all 9,434 cancer patients (100%) referred to SPC were registered in DPD. In total, 41,104 unique cancer patients were registered in DPD during the 5 years 2010-2014. Of those registered, 96% had cancer. DPD is a national clinical quality database for SPC having clinically relevant variables and high data and patient completeness.

Dissipative particle dynamics simulations of polymersomes.

PubMed

Ortiz, Vanessa; Nielsen, Steven O; Discher, Dennis E; Klein, Michael L; Lipowsky, Reinhard; Shillcock, Julian

2005-09-22

A DPD model of PEO-based block copolymer vesicles in water is developed by introducing a new density based coarse graining and by using experimental data for interfacial tension. Simulated as a membrane patch, the DPD model is in excellent agreement with experimental data for both the area expansion modulus and the scaling of hydrophobic core thickness with molecular weight. Rupture simulations of polymer vesicles, or "polymersomes", are presented to illustrate the system sizes feasible with DPD. The results should provide guidance for theoretical derivations of scaling laws and also illustrate how spherical polymer vesicles might be studied in simulation.

The roles of dominos and nonsimultaneous chains in kidney paired donation.

PubMed

Gentry, S E; Montgomery, R A; Swihart, B J; Segev, D L

2009-06-01

Efforts to expand kidney paired donation have included matching nondirected donors (NDDs) to incompatible pairs. In domino paired donation (DPD), an NDD gives to the recipient of an incompatible pair, beginning a string of simultaneous transplants that ends with a living donor giving to a recipient on the deceased donor waitlist. Recently, nonsimultaneous extended altruistic donor (NEAD) chains were introduced. In a NEAD chain, the last donor of the string of transplants initiated by an NDD is reserved to donate at a later time. Our aim was to project the impact of each of these strategies over 2 years of operation for paired donation programs that also allocate a given number of NDDs. Each NDD facilitated an average of 1.99 transplants using DPD versus 1.90 transplants using NEAD chains (p = 0.3), or 1.0 transplants donating directly to the waitlist (p < 0.001). NEAD chains did not yield more transplants compared with simultaneous DPD. Both DPD and NEAD chains relax reciprocality requirements and rebalance the blood-type distribution of donors. Because traditional paired donation will leave many incompatible pairs unmatched, novel approaches like DPD and NEAD chains must be explored if paired donation programs are to help a greater number of people.

Effect of amiloride and bumetanide on transepithelial ion transport in isolated rabbit cecal and colonic wall.

PubMed

Kosik-Bogacka, Danuta; Młodzik-Danielewicz, Natalia; Banach, Bolesław; Tyrakowski, Tomasz

2005-06-03

The aim of the study was to compare the effects of amiloride and bumetanide on the baseline transepithelial electrical potential difference (PD) and changes in PD during mechanical stimulation (dPD) in isolated cecal and colonic wall of rabbits. The experiments were performed with a modified Ussing chamber system. Isolated tissue specimens were incubated in Ringer's solution, in amiloride and/or bumetanide, or in dimethyl sulfoxide (DMSO). Under control conditions, i.e. when all the experimental fluids were Ringer's solution, the PD and R values of the rabbit cecum and colon were similar, while during mechanical stimulation, dPD of the colon was twice as high as that of the cecum. Addition of amiloride and/or bumetanide to all experimental fluids diminished the electrophysiological parameters of both tissues. DMSO added to all experimental fluids significantly diminished the values of the electrophysiological parameters of the cecum. Addition of amiloride to the stimulation fluid only diminished the PD and dPD values in the colon, whereas addition of bumetanide to the stimulation fluid only diminished the PD and dPD values in the cecum. It was found that the PD and dPD values of the rabbit cecum depend primarily on chloride ion transport, while those of the colon depend on sodium ion transport.

A Conserved, Mg2+-Dependent Exonuclease Degrades Organelle DNA during Arabidopsis Pollen Development[C][W

PubMed Central

Matsushima, Ryo; Tang, Lay Yin; Zhang, Lingang; Yamada, Hiroshi; Twell, David; Sakamoto, Wataru

2011-01-01

In plant cells, mitochondria and plastids contain their own genomes derived from the ancestral bacteria endosymbiont. Despite their limited genetic capacity, these multicopy organelle genomes account for a substantial fraction of total cellular DNA, raising the question of whether organelle DNA quantity is controlled spatially or temporally. In this study, we genetically dissected the organelle DNA decrease in pollen, a phenomenon that appears to be common in most angiosperm species. By staining mature pollen grains with fluorescent DNA dye, we screened Arabidopsis thaliana for mutants in which extrachromosomal DNAs had accumulated. Such a recessive mutant, termed defective in pollen organelle DNA degradation1 (dpd1), showing elevated levels of DNAs in both plastids and mitochondria, was isolated and characterized. DPD1 encodes a protein belonging to the exonuclease family, whose homologs appear to be found in angiosperms. Indeed, DPD1 has Mg2+-dependent exonuclease activity when expressed as a fusion protein and when assayed in vitro and is highly active in developing pollen. Consistent with the dpd phenotype, DPD1 is dual-targeted to plastids and mitochondria. Therefore, we provide evidence of active organelle DNA degradation in the angiosperm male gametophyte, primarily independent of maternal inheritance; the biological function of organellar DNA degradation in pollen is currently unclear. PMID:21521697

Emergency First Responders' Experience with Colorimetric Detection Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sandra L. Fox; Keith A. Daum; Carla J. Miller

2007-10-01

Nationwide, first responders from state and federal support teams respond to hazardous materials incidents, industrial chemical spills, and potential weapons of mass destruction (WMD) attacks. Although first responders have sophisticated chemical, biological, radiological, and explosive detectors available for assessment of the incident scene, simple colorimetric detectors have a role in response actions. The large number of colorimetric chemical detection methods available on the market can make the selection of the proper methods difficult. Although each detector has unique aspects to provide qualitative or quantitative data about the unknown chemicals present, not all detectors provide consistent, accurate, and reliable results. Includedmore » here, in a consumer-report-style format, we provide “boots on the ground” information directly from first responders about how well colorimetric chemical detection methods meet their needs in the field and how they procure these methods.« less

Pharmacogenetics and Metabolism from Science to Implementation in Clinical Practice: The Example of Dihydropyrimidine Dehydrogenase.

PubMed

Del Re, Marzia; Restante, Giuliana; Di Paolo, Antonello; Crucitta, Stefania; Rofi, Eleonora; Danesi, Romano

2017-01-01

Fluoropyrimidines are widely used in the treatment of solid tumors and remain the backbone of many combination chemotherapy regimens. Despite their clinical benefit, they are associated with frequent gastrointestinal and hematological toxicities, which often lead to treatment discontinuation. Fluoropyrimidines undergo complex anabolic and catabolic biotransformation. Enzymes involved in this pathway include dihydropyrimidine dehydrogenase (DPD), which breaks down 5-FU and its prodrugs. Candidate gene approaches have demonstrated associations between 5-FU treatment outcomes and germline polymorphisms in DPD. The aim of this review is to report and discuss the latest results on fluoropyrimidine pharmacogenetics. Literature from PubMed databases and bibliography from retrieved publications have been analyzed according to terms such DPD, DPYD, fluoropyrimdines, polymorphisms, toxicity, pharmacogenetics. To date, many sequence variations have been identified within DPYD gene, although the majority of these have no functional consequences on enzymatic activity. Nowadays, there is a general agreement on the clinical significance of the importance of DPD deficiency in patients who suffer from severe, life-threatening drug toxicity although preemptive testing is not applied to all patients. Considering the published literature, clinicians are strongly encouraged to consider testing for DPD poor metabolizer variants as a rational pre-treatment screening for patients candidate to a fluoropyrimidine-based regimens, in order to prevent toxicities and personalise treatments. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Accuracy of Blood Loss Measurement during Cesarean Delivery.

PubMed

Doctorvaladan, Sahar V; Jelks, Andrea T; Hsieh, Eric W; Thurer, Robert L; Zakowski, Mark I; Lagrew, David C

2017-04-01

Objective  This study aims to compare the accuracy of visual, quantitative gravimetric, and colorimetric methods used to determine blood loss during cesarean delivery procedures employing a hemoglobin extraction assay as the reference standard. Study Design  In 50 patients having cesarean deliveries blood loss determined by assays of hemoglobin content on surgical sponges and in suction canisters was compared with obstetricians' visual estimates, a quantitative gravimetric method, and the blood loss determined by a novel colorimetric system. Agreement between the reference assay and other measures was evaluated by the Bland-Altman method. Results  Compared with the blood loss measured by the reference assay (470 ± 296 mL), the colorimetric system (572 ± 334 mL) was more accurate than either visual estimation (928 ± 261 mL) or gravimetric measurement (822 ± 489 mL). The correlation between the assay method and the colorimetric system was more predictive (standardized coefficient = 0.951, adjusted R 2  = 0.902) than either visual estimation (standardized coefficient = 0.700, adjusted R 2  = 00.479) or the gravimetric determination (standardized coefficient = 0.564, adjusted R 2  = 0.304). Conclusion  During cesarean delivery, measuring blood loss using colorimetric image analysis is superior to visual estimation and a gravimetric method. Implementation of colorimetric analysis may enhance the ability of management protocols to improve clinical outcomes.

Accuracy of Blood Loss Measurement during Cesarean Delivery

PubMed Central

Doctorvaladan, Sahar V.; Jelks, Andrea T.; Hsieh, Eric W.; Thurer, Robert L.; Zakowski, Mark I.; Lagrew, David C.

2017-01-01

Objective This study aims to compare the accuracy of visual, quantitative gravimetric, and colorimetric methods used to determine blood loss during cesarean delivery procedures employing a hemoglobin extraction assay as the reference standard. Study Design In 50 patients having cesarean deliveries blood loss determined by assays of hemoglobin content on surgical sponges and in suction canisters was compared with obstetricians' visual estimates, a quantitative gravimetric method, and the blood loss determined by a novel colorimetric system. Agreement between the reference assay and other measures was evaluated by the Bland–Altman method. Results Compared with the blood loss measured by the reference assay (470 ± 296 mL), the colorimetric system (572 ± 334 mL) was more accurate than either visual estimation (928 ± 261 mL) or gravimetric measurement (822 ± 489 mL). The correlation between the assay method and the colorimetric system was more predictive (standardized coefficient = 0.951, adjusted R2 = 0.902) than either visual estimation (standardized coefficient = 0.700, adjusted R2 = 00.479) or the gravimetric determination (standardized coefficient = 0.564, adjusted R2 = 0.304). Conclusion During cesarean delivery, measuring blood loss using colorimetric image analysis is superior to visual estimation and a gravimetric method. Implementation of colorimetric analysis may enhance the ability of management protocols to improve clinical outcomes. PMID:28497007

Underlying Manifestations of Developmental Phonological Disorders in French-Speaking Pre-Schoolers

ERIC Educational Resources Information Center

Brosseau-Lapré, Françoise; Rvachew, Susan

2017-01-01

This study examined the psycholinguistic profiles of Quebec French-speaking children with developmental phonological disorders (DPD). The purpose was to determine whether the endophenotypes that have been identified in English-speaking children with DPD are similarly associated with speech impairment in French-speaking children. Seventy-two…

DPD epitope-specific glutamic acid decarboxylase GAD)65 autoantibodies in children with Type 1 diabetes

USDA-ARS?s Scientific Manuscript database

To study whether DPD epitope-specific glutamate decarboxylase autoantibodies are found more frequently in children with milder forms of Type 1 diabetes. We prospectively evaluated 75 children with new-onset autoimmune Type 1 diabetes, in whom we collected demographic, anthropometric and clinical dat...

Comparative Chemometric Analysis for Classification of Acids and Bases via a Colorimetric Sensor Array.

PubMed

Kangas, Michael J; Burks, Raychelle M; Atwater, Jordyn; Lukowicz, Rachel M; Garver, Billy; Holmes, Andrea E

2018-02-01

With the increasing availability of digital imaging devices, colorimetric sensor arrays are rapidly becoming a simple, yet effective tool for the identification and quantification of various analytes. Colorimetric arrays utilize colorimetric data from many colorimetric sensors, with the multidimensional nature of the resulting data necessitating the use of chemometric analysis. Herein, an 8 sensor colorimetric array was used to analyze select acid and basic samples (0.5 - 10 M) to determine which chemometric methods are best suited for classification quantification of analytes within clusters. PCA, HCA, and LDA were used to visualize the data set. All three methods showed well-separated clusters for each of the acid or base analytes and moderate separation between analyte concentrations, indicating that the sensor array can be used to identify and quantify samples. Furthermore, PCA could be used to determine which sensors showed the most effective analyte identification. LDA, KNN, and HQI were used for identification of analyte and concentration. HQI and KNN could be used to correctly identify the analytes in all cases, while LDA correctly identified 95 of 96 analytes correctly. Additional studies demonstrated that controlling for solvent and image effects was unnecessary for all chemometric methods utilized in this study.

Morphology and Performance of Polymer Solar Cell Characterized by DPD Simulation and Graph Theory.

PubMed

Du, Chunmiao; Ji, Yujin; Xue, Junwei; Hou, Tingjun; Tang, Jianxin; Lee, Shuit-Tong; Li, Youyong

2015-11-19

The morphology of active layers in the bulk heterojunction (BHJ) solar cells is critical to the performance of organic photovoltaics (OPV). Currently, there is limited information for the morphology from transmission electron microscopy (TEM) techniques. Meanwhile, there are limited approaches to predict the morphology /efficiency of OPV. Here we use Dissipative Particle Dynamics (DPD) to determine 3D morphology of BHJ solar cells and show DPD to be an efficient approach to predict the 3D morphology. Based on the 3D morphology, we estimate the performance indicator of BHJ solar cells by using graph theory. Specifically, we study poly (3-hexylthiophene)/[6, 6]-phenyl-C61butyric acid methyl ester (P3HT/PCBM) BHJ solar cells. We find that, when the volume fraction of PCBM is in the region 0.4 ∼ 0.5, P3HT/PCBM will show bi-continuous morphology and optimum performance, consistent with experimental results. Further, the optimum temperature (413 K) for the morphology and performance of P3HT/PCBM is in accord with annealing results. We find that solvent additive plays a critical role in the desolvation process of P3HT/PCBM BHJ solar cell. Our approach provides a direct method to predict dynamic 3D morphology and performance indicator for BHJ solar cells.

A novel, colorimetric method for biogenic amine detection based on arylalkylamine N-acetyltransferase.

PubMed

Leng, Pei-Qiang; Zhao, Feng-Lan; Yin, Bin-Cheng; Ye, Bang-Ce

2015-05-21

We developed a novel colorimetric method for rapid detection of biogenic amines based on arylalkylamine N-acetyltransferase (aaNAT). The proposed method offers distinct advantages including simple handling, high speed, low cost, good sensitivity and selectivity.

Time-dependent and outflow boundary conditions for Dissipative Particle Dynamics

PubMed Central

Lei, Huan; Fedosov, Dmitry A.; Karniadakis, George Em

2011-01-01

We propose a simple method to impose both no-slip boundary conditions at fluid-wall interfaces and at outflow boundaries in fully developed regions for Dissipative Particle Dynamics (DPD) fluid systems. The procedure to enforce the no-slip condition is based on a velocity-dependent shear force, which is a generalized force to represent the presence of the solid-wall particles and to maintain locally thermodynamic consistency. We show that this method can be implemented in both steady and time-dependent fluid systems and compare the DPD results with the continuum limit (Navier-Stokes) results. We also develop a force-adaptive method to impose the outflow boundary conditions for fully developed flow with unspecified outflow velocity profile or pressure value. We study flows over the backward-facing step and in idealized arterial bifurcations using a combination of the two new boundary methods with different flow rates. Finally, we explore the applicability of the outflow method in time-dependent flow systems. The outflow boundary method works well for systems with Womersley number of O(1), i.e., when the pressure and flowrate at the outflow are approximately in-phase. PMID:21499548

Dissipative particle dynamics (DPD) simulations with fragment molecular orbital (FMO) based effective parameters for 1-Palmitoyl-2-oleoyl phosphatidyl choline (POPC) membrane

NASA Astrophysics Data System (ADS)

Doi, Hideo; Okuwaki, Koji; Mochizuki, Yuji; Ozawa, Taku; Yasuoka, Kenji

2017-09-01

In dissipative particle dynamics (DPD) simulations, it is necessary to use the so-called χ parameter set that express the effective interactions between particles. Recently, we have developed a new scheme to evaluate the χ parameters in a non-empirical way through a series of fragment molecular orbital (FMO) calculations. As a challenging test, we have performed the DPD simulations using the FMO-based χ parameters for a mixture of 1-Palmitoyl-2-oleoyl phosphatidyl choline (POPC) and water. The structures of both membrane and vesicle were formed successfully. The calculated structural parameters of membrane were in good agreement with experimental results.

Illuminating a neglected clinical issue: societal costs of interpersonal dependency and dependent personality disorder.

PubMed

Bornstein, Robert F

2012-07-01

To determine the degree to which patients with high levels of trait dependency or dependent personality disorder (DPD) engage in behaviors that harm themselves and others (e.g., domestic violence, child abuse). Six domains of literature were reviewed: (a) dependency as a risk factor for physical illness; (b) health care utilization and expenditures; (c) global and domain-specific functional impairment; (d) violence toward others; (e) victimization by others; and (f) self-harm. High levels of trait dependency and DPD are associated with elevated risk for physical illness, partner and child abuse, and suicidality, as well as with high levels of functional impairment and increased health care expenditure. Contrary to clinical lore, trait dependency and DPD are associated with behaviors that lead to myriad negative consequences for the dependent person, those close to them, and society as a whole. These patterns have noteworthy implications for assessment and treatment of dependent patients and suggest that DPD should be included as a diagnostic category in the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition. © 2012 Wiley Periodicals, Inc.

Imposition of physical parameters in dissipative particle dynamics

NASA Astrophysics Data System (ADS)

Mai-Duy, N.; Phan-Thien, N.; Tran-Cong, T.

2017-12-01

In the mesoscale simulations by the dissipative particle dynamics (DPD), the motion of a fluid is modelled by a set of particles interacting in a pairwise manner, and it has been shown to be governed by the Navier-Stokes equation, with its physical properties, such as viscosity, Schmidt number, isothermal compressibility, relaxation and inertia time scales, in fact its whole rheology resulted from the choice of the DPD model parameters. In this work, we will explore the response of a DPD fluid with respect to its parameter space, where the model input parameters can be chosen in advance so that (i) the ratio between the relaxation and inertia time scales is fixed; (ii) the isothermal compressibility of water at room temperature is enforced; and (iii) the viscosity and Schmidt number can be specified as inputs. These impositions are possible with some extra degrees of freedom in the weighting functions for the conservative and dissipative forces. Numerical experiments show an improvement in the solution quality over conventional DPD parameters/weighting functions, particularly for the number density distribution and computed stresses.

Altered orientation of spatial attention in depersonalization disorder.

PubMed

Adler, Julia; Beutel, Manfred E; Knebel, Achim; Berti, Stefan; Unterrainer, Josef; Michal, Matthias

2014-05-15

Difficulties with concentration are frequent complaints of patients with depersonalization disorder (DPD). Standard neuropsychological tests suggested alterations of the attentional and perceptual systems. To investigate this, the well-validated Spatial Cueing paradigm was used with two different tasks, consisting either in the detection or in the discrimination of visual stimuli. At the start of each trial a cue indicated either the correct (valid) or the incorrect (invalid) position of the upcoming stimulus or was uninformative (neutral). Only under the condition of increased task difficulty (discrimination task) differences between DPD patients and controls were observed. DPD patients showed a smaller total attention directing effect (RT in valid vs. invalid trials) compared to healthy controls only in the discrimination condition. RT costs (i.e., prolonged RT in neutral vs. invalid trials) mainly accounted for this difference. These results indicate that DPD is associated with altered attentional mechanisms, especially with a stronger responsiveness to unexpected events. From an evolutionary perspective this may be advantageous in a dangerous environment, in daily life it may be experienced as high distractibility. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Coarse-grained model of water diffusion and proton conductivity in hydrated polyelectrolyte membrane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Ming-Tsung; Vishnyakov, Aleksey; Neimark, Alexander V., E-mail: aneimark@rutgers.edu

2016-01-07

Using dissipative particle dynamics (DPD), we simulate nanoscale segregation, water diffusion, and proton conductivity in hydrated sulfonated polystyrene (sPS). We employ a novel model [Lee et al. J. Chem. Theory Comput. 11(9), 4395-4403 (2015)] that incorporates protonation/deprotonation equilibria into DPD simulations. The polymer and water are modeled by coarse-grained beads interacting via short-range soft repulsion and smeared charge electrostatic potentials. The proton is introduced as a separate charged bead that forms dissociable Morse bonds with the base beads representing water and sulfonate anions. Morse bond formation and breakup artificially mimics the Grotthuss mechanism of proton hopping between the bases. Themore » DPD model is parameterized by matching the proton mobility in bulk water, dissociation constant of benzenesulfonic acid, and liquid-liquid equilibrium of water-ethylbenzene solutions. The DPD simulations semi-quantitatively predict nanoscale segregation in the hydrated sPS into hydrophobic and hydrophilic subphases, water self-diffusion, and proton mobility. As the hydration level increases, the hydrophilic subphase exhibits a percolation transition from isolated water clusters to a 3D network. The analysis of hydrophilic subphase connectivity and water diffusion demonstrates the importance of the dynamic percolation effect of formation and breakup of temporary junctions between water clusters. The proposed DPD model qualitatively predicts the ratio of proton to water self-diffusion and its dependence on the hydration level that is in reasonable agreement with experiments.« less

Incorporation of memory effects in coarse-grained modeling via the Mori-Zwanzig formalism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zhen; Bian, Xin; Karniadakis, George Em, E-mail: george-karniadakis@brown.edu

2015-12-28

The Mori-Zwanzig formalism for coarse-graining a complex dynamical system typically introduces memory effects. The Markovian assumption of delta-correlated fluctuating forces is often employed to simplify the formulation of coarse-grained (CG) models and numerical implementations. However, when the time scales of a system are not clearly separated, the memory effects become strong and the Markovian assumption becomes inaccurate. To this end, we incorporate memory effects into CG modeling by preserving non-Markovian interactions between CG variables, and the memory kernel is evaluated directly from microscopic dynamics. For a specific example, molecular dynamics (MD) simulations of star polymer melts are performed while themore » corresponding CG system is defined by grouping many bonded atoms into single clusters. Then, the effective interactions between CG clusters as well as the memory kernel are obtained from the MD simulations. The constructed CG force field with a memory kernel leads to a non-Markovian dissipative particle dynamics (NM-DPD). Quantitative comparisons between the CG models with Markovian and non-Markovian approximations indicate that including the memory effects using NM-DPD yields similar results as the Markovian-based DPD if the system has clear time scale separation. However, for systems with small separation of time scales, NM-DPD can reproduce correct short-time properties that are related to how the system responds to high-frequency disturbances, which cannot be captured by the Markovian-based DPD model.« less

Longitudinal comparison of depressive personality disorder and dysthymic disorder.

PubMed

Markowitz, John C; Skodol, Andrew E; Petkova, Eva; Xie, Hui; Cheng, Jianfeng; Hellerstein, David J; Gunderson, John G; Sanislow, Charles A; Grilo, Carlos M; McGlashan, Thomas H

2005-01-01

Few studies have compared the related diagnostic constructs of depressive personality disorder (DPD) and dysthymic disorder (DD). The authors attempted to replicate findings of Klein and Shih in longitudinally followed patients with personality disorder or major depressive disorder (MDD) in the Collaborative Longitudinal Personality Disorders Study. Subjects (N = 665) were evaluated at baseline and over 2 years (n = 546) by reliably trained clinical interviewers using semistructured interviews and self-report personality questionnaires. Only 44 subjects (24.6% of 179 DPD and 49.4% of 89 early-onset dysthymic subjects) met criteria for both disorders at baseline. Depressive personality disorder was associated with increased comorbidity of some axis I anxiety disorders and other axis II diagnoses, particularly avoidant (71.5%) and borderline (55.9%) personality disorders. Depressive personality disorder was associated with low positive and high negative affectivity on dimensional measures of temperament. Depressive personality disorder subjects had lower likelihood of remission of baseline MDD at 2-year follow-up, whereas DD subjects did not. The DPD diagnosis appeared unstable over 2 years of follow-up, as only 31% (n = 47) of 154 subjects who had DPD at baseline and also had follow-up assessment met criteria on blind retesting. Results from this sample may not generalize to other populations. Depressive personality disorder and dysthymic disorder appear to be related but differ in diagnostic constructs. Its moderating effect on MDD and predicted relationship to measures of temperament support the validity of DPD, but its diagnostic instability raises questions about its course, utility, and measurement.

Comparison of macro-gravimetric and micro-colorimetric lipid determination methods.

PubMed

Inouye, Laura S; Lotufo, Guiherme R

2006-10-15

In order to validate a method for lipid analysis of small tissue samples, the standard macro-gravimetric method of Bligh-Dyer (1959) [E.G. Bligh, W.J. Dyer, Can. J. Biochem. Physiol. 37 (1959) 911] and a modification of the micro-colorimetric assay developed by Van Handel (1985) [E. Van Handel, J. Am. Mosq. Control Assoc. 1 (1985) 302] were compared. No significant differences were observed for wet tissues of two species of fish. However, limited analysis of wet tissue of the amphipod, Leptocheirusplumulosus, indicated that the Bligh-Dyer gravimetric method generated higher lipid values, most likely due to the inclusion of non-lipid materials. Additionally, significant differences between the methods were observed with dry tissues, with the micro-colorimetric method consistently reporting calculated lipid values greater than as reported by the gravimetric method. This was most likely due to poor extraction of dry tissue in the standard Bligh-Dyer method, as no significant differences were found when analyzing a single composite extract. The data presented supports the conclusion that the micro-colorimetric method described in this paper is accurate, rapid, and minimizes time and solvent use.

Effects of soy isoflavone supplements on bone turnover markers in menopausal women: systematic review and meta-analysis of randomized controlled trials.

PubMed

Taku, Kyoko; Melby, Melissa K; Kurzer, Mindy S; Mizuno, Shoichi; Watanabe, Shaw; Ishimi, Yoshiko

2010-08-01

Effects of soy isoflavone supplements on bone turnover markers remain unclear. This up-to-date systematic review and meta-analysis of randomized controlled trials (RCTs) was performed primarily to more completely and precisely clarify the effects on urinary deoxypyridinoline (DPD) and serum bone alkaline phosphatase (BAP) and secondarily to evaluate the effects on other bone turnover markers, compared with placebo in menopausal women. PubMed, CENTRAL, ICHUSHI, and CNKI were searched in June 2009 for relevant studies of RCTs. Data on study design, participants, interventions, and outcomes were extracted and methodological quality of each included trial was assessed. From 3740 identified relevant articles, 10 (887 participants), 10 (1210 participants), and 8 (380 participants) RCTs were selected for meta-analysis of effects on DPD, BAP, and serum osteocalcin (OC), respectively, using Review Manager 5.0.22. Daily ingestion of an average 56 mg soy isoflavones (aglycone equivalents) for 10 weeks to 12 months significantly decreased DPD by 14.1% (95% CI: -26.8% to -1.5%; P=0.03) compared to baseline (heterogeneity: P<0.00001; I(2)=93%; random effects model). The overall effect of soy isoflavones on DPD compared with placebo was a significant decrease of -18.0% (95% CI: -28.4% to -7.7%, P=0.0007; heterogeneity: P=0.0001; I(2)=73%; random effects model). Subgroup analyses and meta-regressions revealed that isoflavone dose and intervention duration did not significantly relate to the variable effects on DPD. Daily supplementation of about 84 mg and 73 mg of soy isoflavones for up to 12 months insignificantly increased BAP by 8.0% (95% CI: -4.2% to 20.2%, P=0.20; heterogeneity: P<0.00001; I(2)=98%) and OC by 10.3% (95% CI: -3.1% to 23.7%, P=0.13; heterogeneity: P=0.002; I(2)=69%) compared with placebo (random effects model), respectively. Soy isoflavone supplements moderately decreased the bone resorption marker DPD, but did not affect bone formation markers BAP and OC in menopausal women. The effects varied between studies, and further studies are needed to address factors relating to the observed effects of soy isoflavones on DPD and to verify effects on other bone turnover markers. Copyright 2010 Elsevier Inc. All rights reserved.

Infrared and colorimetric characterization of discolored kiln-dried hard maple lumber

Treesearch

Benjamin E. Dawson-Andoh; Michael Wiemann; Laurent Matuana; John Baumgras

2004-01-01

Discoloration of hard maple lumber commonly occurs during kiln-drying. In this study, discolored andnondiscolored kiln-dried hard maple lumber boards were characterized using a colorimetric method and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR). Colorimetric measurements (L*, a*, b*) were found to be in good agreement with visual...

Comparison of serum copper determination by colorimetric and atomic absorption spectrometric methods in seven different laboratories. The S.F.B.C. (Société Française de Biologie Clinique) Trace Element Group.

PubMed

Arnaud, J; Chappuis, P; Zawislak, R; Houot, O; Jaudon, M C; Bienvenu, F; Bureau, F

1993-02-01

An interlaboratory collaborative trial was conducted on the determination of serum copper using two different methods, based on colorimetry (test combination Copper, Boehringer Mannheim, Mannheim, Germany) and flame atomic absorption spectrometry (FAAS). The general performance of the colorimetric method was below that of FAAS, except for sensitivity and linear range, as assessed by detection limit (0.44 versus 1.32 mumol/L) and upper limit of linearity (150 versus 50 mumol/L). The range of the between-run CVs and the recovery of standard additions were, respectively, 2.3-11.9% and 92-127% for the colorimetric method and 1.1-6.0% and 93-101% for the FAAS method. Interferences were minimal with both methods. The two techniques correlated satisfactorily (the correlation coefficients ranged from 0.945-0.970 among laboratories) but the colorimetric assay exhibited slightly higher results than the FAAS method. Each method was transferable among laboratories.

Colorimetric detection of ammonia using smartphones based on localized surface plasmon resonance of silver nanoparticles.

PubMed

Amirjani, Amirmostafa; Fatmehsari, Davoud Haghshenas

2018-01-01

In this work, a rapid and straightforward method was developed for colorimetric determination of ammonia using smartphones. The mechanisms is based on the manipulation of the surface plasmon band of silver nanoparticles (AgNPs) via the formation of Ag (NH 3 ) 2 + complex. This complex decreases the amount of AgNPs in the solution and consequently, the color intensity of the colloidal system decreases. Not only the variation in color intensity of the solution can be tracked by a UV-vis spectrophotometer, but also a smartphone can be employed to monitor the color intensity variation by RGB analysis. Ammonia, in the concentration range of 10-1000mgL -1 , was successfully measured spectrophotometrically (UV-vis spectrophotometer) and colorimetrically (RGB measurement) with the detection limit of 180 and 200mgL -1 , respectively. Linear relationships were also developed for both methods. Also, the response time of the developed colorimetric sensor was around 20s. Both of the colorimetric and spectrophotometric methods showed a reliable performance for determination of ammonia in the real samples. Copyright © 2017 Elsevier B.V. All rights reserved.

An Illumination-Adaptive Colorimetric Measurement Using Color Image Sensor

NASA Astrophysics Data System (ADS)

Lee, Sung-Hak; Lee, Jong-Hyub; Sohng, Kyu-Ik

An image sensor for a use of colorimeter is characterized based on the CIE standard colorimetric observer. We use the method of least squares to derive a colorimetric characterization matrix between RGB output signals and CIE XYZ tristimulus values. This paper proposes an adaptive measuring method to obtain the chromaticity of colored scenes and illumination through a 3×3 camera transfer matrix under a certain illuminant. Camera RGB outputs, sensor status values, and photoelectric characteristic are used to obtain the chromaticity. Experimental results show that the proposed method is valid in the measuring performance.

Mobile micro-colorimeter and micro-spectrometer sensor modules as enablers for the replacement of subjective inspections by objective measurements for optically clear colored liquids in-field

NASA Astrophysics Data System (ADS)

Dittrich, Paul-Gerald; Grunert, Fred; Ehehalt, Jörg; Hofmann, Dietrich

2015-03-01

Aim of the paper is to show that the colorimetric characterization of optically clear colored liquids can be performed with different measurement methods and their application specific multichannel spectral sensors. The possible measurement methods are differentiated by the applied types of multichannel spectral sensors and therefore by their spectral resolution, measurement speed, measurement accuracy and measurement costs. The paper describes how different types of multichannel spectral sensors are calibrated with different types of calibration methods and how the measurement values can be used for further colorimetric calculations. The different measurement methods and the different application specific calibration methods will be explained methodically and theoretically. The paper proofs that and how different multichannel spectral sensor modules with different calibration methods can be applied with smartpads for the calculation of measurement results both in laboratory and in field. A given practical example is the application of different multichannel spectral sensors for the colorimetric characterization of petroleum oils and fuels and their colorimetric characterization by the Saybolt color scale.

A look-up-table digital predistortion technique for high-voltage power amplifiers in ultrasonic applications.

PubMed

Gao, Zheng; Gui, Ping

2012-07-01

In this paper, we present a digital predistortion technique to improve the linearity and power efficiency of a high-voltage class-AB power amplifier (PA) for ultrasound transmitters. The system is composed of a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), and a field-programmable gate array (FPGA) in which the digital predistortion (DPD) algorithm is implemented. The DPD algorithm updates the error, which is the difference between the ideal signal and the attenuated distorted output signal, in the look-up table (LUT) memory during each cycle of a sinusoidal signal using the least-mean-square (LMS) algorithm. On the next signal cycle, the error data are used to equalize the signal with negative harmonic components to cancel the amplifier's nonlinear response. The algorithm also includes a linear interpolation method applied to the windowed sinusoidal signals for the B-mode and Doppler modes. The measurement test bench uses an arbitrary function generator as the DAC to generate the input signal, an oscilloscope as the ADC to capture the output waveform, and software to implement the DPD algorithm. The measurement results show that the proposed system is able to reduce the second-order harmonic distortion (HD2) by 20 dB and the third-order harmonic distortion (HD3) by 14.5 dB, while at the same time improving the power efficiency by 18%.

Depression in Parkinson's disease: symptom improvement and residual symptoms after acute pharmacologic management.

PubMed

Dobkin, Roseanne DeFronzo; Menza, Matthew; Bienfait, Karina L; Gara, Michael; Marin, Humberto; Mark, Margery H; Dicke, Allison; Friedman, Jill

2011-03-01

Parkinson's disease (PD) is frequently complicated by depression and there is a paucity of controlled research that can inform the management of this disabling nonmotor complaint. A randomized controlled trial of nortriptyline, paroxetine, and placebo for the treatment of depression in PD (dPD) was recently completed. The purpose of this article is to describe the baseline pattern of depressive symptom presentation in PD, the specific symptoms of dPD that improve with pharmacotherapy, and the residual symptoms that remain in patients who meet a priori criteria for response or remission after acute treatment (8 weeks). The Departments of Psychiatry and Neurology at Robert Wood Johnson Medical School, New Jersey. : Fifty-two depressed patients (major depression or dysthymia based on Diagnostic and Statistical Manual of Mental Disorders 4th edition criteria) with Parkinson's disease (by research criteria). A randomized controlled trial of nortriptyline, paroxetine, and placebo. The four subscales (core mood, anxiety, insomnia, and somatic) and individual items from the Hamilton Rating Scale for Depression-17 were the focus of this study. These measures were assessed at baseline and Week 8. Baseline depressive symptoms were unrelated to motor functioning. Treatment response was associated with significant improvements in the core mood, anxiety, insomnia, and somatic symptoms seen in dPD. Residual symptoms, such as sadness and loss of interest, persisted in treatment responders in a milder form than was initially present. Antidepressants may influence all symptoms of dPD, including those that share great overlap with the physical disease process. Additional research regarding adjunctive interventions is needed to help optimize the management of dPD.

Biomechanics of Hybrid Anterior Cervical Fusion and Artificial Disc Replacement in 3-Level Constructs: An In Vitro Investigation

PubMed Central

Liao, Zhenhua; Fogel, Guy R.; Pu, Ting; Gu, Hongsheng; Liu, Weiqiang

2015-01-01

Background The ideal surgical approach for cervical disk disease remains controversial, especially for multilevel cervical disease. The purpose of this study was to investigate the biomechanics of the cervical spine after 3-level hybrid surgery compared with 3-level anterior cervical discectomy and fusion (ACDF). Material/Methods Eighteen human cadaveric spines (C2-T1) were evaluated under displacement-input protocol. After intact testing, a simulated hybrid construct or fusion construct was created between C3 to C6 and tested in the following 3 conditions: 3-level disc plate disc (3DPD), 3-level plate disc plate (3PDP), and 3-level plate (3P). Results Compared to intact, almost 65~80% of motion was successfully restricted at C3-C6 fusion levels (p<0.05). 3DPD construct resulted in slight increase at the 3 instrumented levels (p>0.05). 3PDP construct resulted in significant decrease of ROM at C3-C6 levels less than 3P (p<0.05). Both 3DPD and 3PDP caused significant reduction of ROM at the arthrodesis level and produced motion increase at the arthroplasty level. For adjacent levels, 3P resulted in markedly increased contribution of both upper and lower adjacent levels (p<0.05). Significant motion increases lower than 3P were only noted at partly adjacent levels in some conditions for 3DPD and 3PDP (p<0.05). Conclusions ACDF eliminated motion within the construct and greatly increased adjacent motion. Artificial cervical disc replacement normalized motion of its segment and adjacent segments. While hybrid conditions failed to restore normal motion within the construct, they significantly normalized motion in adjacent segments compared with the 3-level ACDF condition. The artificial disc in 3-level constructs has biomechanical advantages compared to fusion in normalizing motion. PMID:26529430

Investigation of broadband digital predistortion for broadband radio over fiber transmission systems

NASA Astrophysics Data System (ADS)

Zhang, Xiupu; Liu, Taijun; Shen, Dongya

2016-12-01

In future broadband cloud radio access networks (C-RAN), front-haul transmission systems play a significant role in performance and cost of C-RAN. Broadband and high linearity radio over fiber (RoF) transmission systems are considered a promising solution for the front-haul. Digital linearization is one possible solution for RoF front-haul. In this paper, we investigate RF domain digital predistortion (DPD) linearization for broadband RoF front-haul. The implemented DPD is first investigated in 2.4 GHz WiFi over fiber transmission systems at 36 Mb/s, and more than 8-dB and 5.6-dB improvements of error vector magnitude (EVM) are achieved in back to back (BTB) and after 10 km single mode fiber (SMF) transmission. Further, both WiFi and ultra wide band (UWB) wireless signals are transmitted together, in which the DPD has linearization bandwidth of 2.4 GHz. It is shown that the implemented DPD leads to EVM improvements of 4.5-dB (BTB) and 3.1-dB (10 km SMF) for the WiFi signal, and 4.6-dB (BTB) and 4-dB (10 km SMF) for the broadband UWB signal.

Evaluation of micro-colorimetric lipid determination method with samples prepared using sonication and accelerated solvent extraction methods

EPA Science Inventory

Two common laboratory extraction techniques were evaluated for routine use with the micro-colorimetric lipid determination method developed by Van Handel (1985) [E. Van Handel, J. Am. Mosq. Control Assoc. 1(1985) 302] and recently validated for small samples by Inouye and Lotufo ...

Cost Effective Paper-Based Colorimetric Microfluidic Devices and Mobile Phone Camera Readers for the Classroom

ERIC Educational Resources Information Center

Koesdjojo, Myra T.; Pengpumkiat, Sumate; Wu, Yuanyuan; Boonloed, Anukul; Huynh, Daniel; Remcho, Thomas P.; Remcho, Vincent T.

2015-01-01

We have developed a simple and direct method to fabricate paper-based microfluidic devices that can be used for a wide range of colorimetric assay applications. With these devices, assays can be performed within minutes to allow for quantitative colorimetric analysis by use of a widely accessible iPhone camera and an RGB color reader application…

Colorimetric characterization of digital cameras with unrestricted capture settings applicable for different illumination circumstances

NASA Astrophysics Data System (ADS)

Fang, Jingyu; Xu, Haisong; Wang, Zhehong; Wu, Xiaomin

2016-05-01

With colorimetric characterization, digital cameras can be used as image-based tristimulus colorimeters for color communication. In order to overcome the restriction of fixed capture settings adopted in the conventional colorimetric characterization procedures, a novel method was proposed considering capture settings. The method calculating colorimetric value of the measured image contains five main steps, including conversion from RGB values to equivalent ones of training settings through factors based on imaging system model so as to build the bridge between different settings, scaling factors involved in preparation steps for transformation mapping to avoid errors resulted from nonlinearity of polynomial mapping for different ranges of illumination levels. The experiment results indicate that the prediction error of the proposed method, which was measured by CIELAB color difference formula, reaches less than 2 CIELAB units under different illumination levels and different correlated color temperatures. This prediction accuracy for different capture settings remains the same level as the conventional method for particular lighting condition.

Basic methods for measuring the reflectance color of iron oxides

NASA Astrophysics Data System (ADS)

Pospisil, Jaroslav; Hrdy, Jan; Hrdy Jan, Jr.

2007-06-01

The main contribution of the present article consists in coherent description and interpretation of the principles of basic measuring methods and colorimeters for color classification and evaluation of light reflecting samples containing iron oxides. The chosen relevant theoretical background is based on the CIE tristimulus colorimetric system (X,Y,Z), the CIE colorimetric system (L*,a*,b*) and the Munsell colorimetric system (H,V,C). As an example of color identification and evaluation, some specific mathematical and graphical relationships between the soil redness rate and the corresponding hematite content are shown.

Dislocation-pipe diffusion in nitride superlattices observed in direct atomic resolution.

PubMed

Garbrecht, Magnus; Saha, Bivas; Schroeder, Jeremy L; Hultman, Lars; Sands, Timothy D

2017-04-06

Device failure from diffusion short circuits in microelectronic components occurs via thermally induced migration of atoms along high-diffusivity paths: dislocations, grain boundaries, and free surfaces. Even well-annealed single-grain metallic films contain dislocation densities of about 10 14  m -2 ; hence dislocation-pipe diffusion (DPD) becomes a major contribution at working temperatures. While its theoretical concept was established already in the 1950s and its contribution is commonly measured using indirect tracer, spectroscopy, or electrical methods, no direct observation of DPD at the atomic level has been reported. We present atomically-resolved electron microscopy images of the onset and progression of diffusion along threading dislocations in sequentially annealed nitride metal/semiconductor superlattices, and show that this type of diffusion can be independent of concentration gradients in the system but governed by the reduction of strain fields in the lattice.

Determination of water-soluble vitamins using a colorimetric microbial viability assay based on the reduction of water-soluble tetrazolium salts.

PubMed

Tsukatani, Tadayuki; Suenaga, Hikaru; Ishiyama, Munetaka; Ezoe, Takatoshi; Matsumoto, Kiyoshi

2011-07-15

A method for the determination of water-soluble vitamins using a colorimetric microbial viability assay based on the reduction of the tetrazolium salt {2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt (WST-8)} via 2-methyl-1,4-napthoquinone (NQ) was developed. Measurement conditions were optimized for the microbiological determination of water-soluble vitamins, such as vitamin B(6), biotin, folic acid, niacin, and pantothenic acid, using microorganisms that have a water-soluble vitamin requirement. A linear relationship between absorbance and water-soluble vitamin concentration was obtained. The proposed method was applied to determine the concentration of vitamin B(6) in various foodstuffs. There was good agreement between vitamin B(6) concentrations determined after 24h using the WST-8 colorimetric method and those obtained after 48h using a conventional method. The results suggest that the WST-8 colorimetric assay is a useful method for the rapid determination of water-soluble vitamins in a 96-well microtiter plate. Copyright © 2011 Elsevier Ltd. All rights reserved.

Feasibility of ecological momentary assessment to characterize adolescent postoperative diet and activity patterns after weight loss surgery.

PubMed

Ratcliff, Megan B; Zeller, Meg H; Inge, Thomas H; Hrovat, Kathleen B; Modi, Avani C

2014-01-01

Adherence to postoperative lifestyle recommendations may be associated with weight outcomes among weight loss surgery (WLS) patients, but it is difficult to objectively assess and has not been reported among adolescents. Methods of assessment that are ecologically valid and provide important contextual information related to adherence are needed. The objective of this pilot study was to demonstrate the feasibility of using a form of ecological momentary assessment (i.e., daily phone diaries; DPD) to assess postoperative diet and activity patterns among a sample of adolescent WLS patients to determine adherence to best-practice lifestyle recommendations. University Hospital. Eight adolescent WLS patients completed 3 consecutive DPDs at 12 and 18 months postsurgery. Ninety-four percent of DPD's were completed with an average 20.9 ± 5.0 activities/day. Although adolescents engaged in recommended lifestyle behaviors (e.g.,≥ 30 min moderate physical activity/d; duration of meals/snacks ≥ 20 min) some of the time, few were adherent to postoperative physical activity and dietary recommendations the majority of the time. The DPD provides a feasible and informative methodology for assessing adherence behaviors among adolescent WLS patients. It is a relatively low burden method that may be useful in identifying behavioral targets for postoperative intervention. Adherence to postoperative lifestyle recommendations may be a serious concern among this cohort. These preliminary data shed light on potential targets for postoperative intervention. Targeting nonadherence is essential in not only improving health outcomes but in deciphering the true potential effectiveness of WLS in this at-risk population. Copyright © 2014 American Society for Metabolic and Bariatric Surgery. Published by Elsevier Inc. All rights reserved.

Accelerated Colorimetric Micro-assay for Screening Mold Inhibitors

Treesearch

Carol A. Clausen; Vina W. Yang

2014-01-01

Rapid quantitative laboratory test methods are needed to screen potential antifungal agents. Existing laboratory test methods are relatively time consuming, may require specialized test equipment and rely on subjective visual ratings. A quantitative, colorimetric micro-assay has been developed that uses XTT tetrazolium salt to metabolically assess mold spore...

An improved colorimetric method for the determination of proline in the presence of other ninhydrin-positive compounds

PubMed Central

Wren, J. J.; Wiggall, P. H.

1965-01-01

1. The conditions required for sensitive and specific colorimetric determination of proline with acidified ninhydrin were investigated. 2. A method applicable to protein samples was developed. 3. The only compound found to interfere appreciably was a hydroxyproline. PMID:14342233

Innovative Procedure for the, in Situ, Measurement of the Resistive Thermal Coefficient of H(D)/Pd during Electrolysis:. Cross-Comparison of New Elements Detected in the Th-Hg-Pd-D(H) Electrolytic Cells

NASA Astrophysics Data System (ADS)

Celani, Francesco; Spallone, A.; Righi, E.; Trenta, G.; Catena, C.; D'Agostaro, G.; Quercia, P.; Andreassi, V.; Marini, P.; di Stefano, V.; Nakamura, M.; Mancini, A.; Sona, P. G.; Fontana, F.; Gamberale, L.; Garbelli, D.; Celia, E.; Falcioni, F.; Marchesini, M.; Novaro, E.; Mastromatteo, U.

2006-02-01

In the framework of cold fusion studies one of the most important parameters is the deuterium (D) to palladium (Pd) ratio, D/Pd. It is well known that the value of this parameter is related to the normalised resistivity (R/R0) of the D-Pd system. When at high D/Pd ratios (i.e. at low R/R0 values) some excess heat occurs, the Pd wire temperature increase and, as a consequence, the apparent R/R0 value also increases. This effect might give raise to ambiguous data interpretation: similar results are in fact expected in case of a Pd wire degassing (i.e. decreasing of D/Pd ratio). To solve this problem, we developed an innovative procedure and a suitable experimental set-up for the in situ measurement of the Resistive Temperature Coefficient (which is affected only by the real D/Pd ratio) during electrolysis. We will report the results on the hydrogen and deuterium loading of thin (50 μm), and long (60cm) Pd wires, immersed in a solution of C2H5OD (or C2H5OH) and D2O (or H2O), with addition of thorium (Th) and mercury (Hg) salts at micromolar concentrations. Evidence of "transmutations" of some elements occasionally present on the Pd surface, and sometimes also in the electrolytic solution, have often been claimed in cold fusion experiments. In the present work, unexpected elements have been detected by high-resolution ICP-MS analysis. Some of these elements have also an isotopic composition different from the natural one.

BONE TURNOVER IN OSTEOPOROTIC WOMEN DURING LONG-TERM ORAL BISPHOSPHONATES TREATMENT: IMPLICATIONS FOR TREATMENT FAILURE AND "DRUG HOLIDAY" IN THE REAL WORLD.

PubMed

Liel, Yair; Plakht, Ygal; Tailakh, Muhammad Abu

2017-07-01

Little data exist to support concerns over bone turnover suppression during prolonged oral bisphosphonate treatment and on consequences of the recommended "drug holiday." This study was performed to assess bone resorption rates in postmenopausal osteoporotic women on prolonged oral bisphosphonate treatment and in response to switching to "drug holiday" intravenous bisphosphonate, or continuation of oral bisphosphonates. The frequency distribution of the bone resorption marker urinary deoxypyridinoline crosslinks (uDPD), was obtained retrospectively from 211 osteoporotic women attended at an academic hospital endocrine clinic, treated for >2 years with oral bisphosphonates. In some patients, uDPD was re-assessed following modification or continuation of treatment. The mean duration of oral bisphosphonates treatment was 7.2 ± 3.1 years. uDPD was within reference range for premenopausal women in 61.6% of the patients, below in 7.6% of the patients, and above upper limit in 30.8%. uDPD decreased significantly following intravenous zoledronic acid, increased significantly during "drug holiday," and slightly decreased in those continued on oral bisphosphonate treatment. In this real-world study, the majority of women on prolonged oral bisphosphonates maintained bone resorption rates within the normal reference range for premenopausal women. The likelihood for inadequate suppression was considerably greater than that of over-suppression. Implementing a "drug holiday" resulted in a marked increase in bone resorption rates. Additional studies should explore the potential role of bone turnover markers in the evaluation of patients on prolonged oral bisphosphonates and during "drug holiday" in different settings and using additional markers. BMD = bone mineral density; IQR = interquartile range; uDPD = urinary deoxypyridinoline crosslinks.

Use of Daily Phone Diary to study religiosity and mood: Convergent validity

PubMed Central

Szczesniak, Rhonda D.; Zou, Yuanshu; Dimitriou, Sophia M.; Quittner, Alexandra L.; Grossoehme, Daniel H.

2017-01-01

Studies of religious/spiritual behavior frequently rely on self-reported questionnaire data, which is susceptible to bias. The Daily Phone Diary (DPD) was developed to minimize bias in reporting activities and behavior across a 24-hour period. A cross-sectional study of 126 parents of children with cystic fibrosis was used to establish the validity of the DPD to study religious/spiritual behaviors. Longitudinal models were used to determine the odds of improved mood during religious/spiritual activities. Convergent validity was found. Participants had increased odds of improved mood during religious/spiritual activities compared to non-religious/spiritual activities. Associations with gender and religious affiliations were found. The DPD is a valid tool for studying religious/spiritual activities and opens novel avenues for chaplaincy research and the development of chaplaincy interventions incorporating these findings. PMID:27869567

Structural and dynamic characterization of ultrafine fibers based on the poly-3-hydroxybutyrate-dipyridamole system

NASA Astrophysics Data System (ADS)

Olkhov, A. A.; Karpova, S. G.; Staroverova, O. V.; Krutikova, A. A.; Orlov, N. A.; Kucherenko, E. L.; Iordanskii, A. L.

2016-11-01

The fibrous materials (the mats) based on poly-3-hydroxybutyrate (PHB) containing the drug, dipiridomole (DPD) were produced by electrospinning (ES). Thermophysical and dynamical properties of the single filaments and the mats were studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and probe electron paramagnetic resonance spectroscopy (EPR). The effect of annealing temperature on the structure and crystallinity of the fibers was examined. It was shown that the loading of DPD influences on both the melting enthalpy and the morphology of the fibers. Besides the analysis of EPR spectra revealed that there are two populations of spin-probes distributed in the rigid and nonrigid amorphous regions of the PHB fibers respectively. For all fibrous materials with different content of DPD (0-5%) the correlation between thermophysical (DSC) and dynamic data (EPR) was observed.

Doped colorimetric assay liposomes

DOEpatents

Charych, Deborah; Stevens, Raymond C.

2001-01-01

The present invention provides compositions comprising colorimetric assay liposomes. The present invention also provides methods for producing colorimetric liposomes and calorimetric liposome assay systems. In preferred embodiments, these calorimetric liposome systems provide high levels of sensitivity through the use of dopant molecules. As these dopants allow the controlled destabilization of the liposome structure, upon exposure of the doped liposomes to analyte(s) of interest, the indicator color change is facilitated and more easily recognized.

Colorimetric characterization models based on colorimetric characteristics evaluation for active matrix organic light emitting diode panels.

PubMed

Gong, Rui; Xu, Haisong; Tong, Qingfen

2012-10-20

The colorimetric characterization of active matrix organic light emitting diode (AMOLED) panels suffers from their poor channel independence. Based on the colorimetric characteristics evaluation of channel independence and chromaticity constancy, an accurate colorimetric characterization method, namely, the polynomial compensation model (PC model) considering channel interactions was proposed for AMOLED panels. In this model, polynomial expressions are employed to calculate the relationship between the prediction errors of XYZ tristimulus values and the digital inputs to compensate the XYZ prediction errors of the conventional piecewise linear interpolation assuming the variable chromaticity coordinates (PLVC) model. The experimental results indicated that the proposed PC model outperformed other typical characterization models for the two tested AMOLED smart-phone displays and for the professional liquid crystal display monitor as well.

Accelerating Calculations of Reaction Dissipative Particle Dynamics in LAMMPS

DTIC Science & Technology

2017-05-17

order reaction mechanism, the best acceleration was 6.1 times. For a larger, more chemically detailed mechanism, the best acceleration exceeded 60 times...simulations at previously inaccessible scales. A principle feature of DPD-RX is its ability to model chemical reactions within each CG particle. The...change in composition due to chemical reactions is described by a system of ordinary differential equations (ODEs) that are evaluated at each DPD time

Nonsimultaneous chains and dominos in kidney- paired donation-revisited.

PubMed

Ashlagi, I; Gilchrist, D S; Roth, A E; Rees, M A

2011-05-01

Since 2008, kidney exchange in America has grown in part from the incorporation of nondirected donors in transplant chains rather than simple exchanges. It is controversial whether these chains should be performed simultaneously 'domino-paired donation', (DPD) or nonsimultaneously 'nonsimultaneous extended altruistic donor, chains (NEAD). NEAD chains create 'bridge donors' whose incompatible recipients receive kidneys before the bridge donor donates, and so risk reneging by bridge donors, but offer the opportunity to create more transplants by overcoming logistical barriers inherent in simultaneous chains. Gentry et al. simulated whether DPD or NEAD chains would produce more transplants when chain segment length was limited to three transplants, and reported that DPD performed at least as well as NEAD chains. As this finding contrasts with the experience of several groups involved in kidney-paired donation, we performed simulations that allowed for longer chain segments and used actual patient data from the Alliance for Paired Donation. When chain segments of 4-6 transplants are allowed in the simulations, NEAD chains produce more transplants than DPD. Our simulations showed not only more transplants as chain length increased, but also that NEAD chains produced more transplants for highly sensitized and blood type O recipients. ©2011 The Authors Journal compilation©2011 The American Society of Transplantation and the American Society of Transplant Surgeons.

Revisiting AI-2 quorum sensing inhibitors: direct comparison of alkyl-DPD analogues and a natural product fimbrolide.

PubMed

Lowery, Colin A; Abe, Takumi; Park, Junguk; Eubanks, Lisa M; Sawada, Daisuke; Kaufmann, Gunnar F; Janda, Kim D

2009-11-04

Quorum sensing (QS) systems have been discovered in a wide variety of bacteria, and mediate both intra- and interspecies communication. The AI-2-based QS system represents the most studied of these proposed interspecies systems and has been shown to regulate diverse functions such as bioluminescence, expression of virulence factors, and biofilm formation. As such, the development of modulatory compounds, both agonists and antagonists, is of great interest for the study of unknown AI-2-based QS systems and the potential treatment of bacterial infections. The fimbrolide class of natural products has exhibited excellent inhibitory activity against AI-2-based QS and as such may be considered the "gold standard" of AI-2 inhibitors. Thus, we sought to include a fimbrolide as a control compound for our recently developed alkyl-DPD panel of AI-2 modulators. Herein, we present a revised synthesis of a commonly studied fimbrolide as well as a direct comparison between the fimbrolide and alkyl-DPD analogues. We demonstrate that our alkyl-DPD analogues are more potent inhibitors of QS in both Vibrio harveyi and Salmonella typhimurium, the two organisms with defined AI-2 QS systems, and in doing so call into question the widely accepted use of fimbrolide-derived compounds as the "gold standard" of AI-2 inhibition.

Localized surface plasmon resonance of gold nanoparticles as colorimetric probes for determination of Isoniazid in pharmacological formulation.

PubMed

Zargar, Behrooz; Hatamie, Amir

2013-04-01

Isoniazid is an important antibiotic, which is widely used to treat tuberculosis. This study presents a colorimetric method for the determination of Isoniazid based on localized surface plasmon resonance (LSPR) property of gold nanoparticles. An LSPR band is produced by reducing gold ions in solution using Isoniazid as the reducing agent. Influences of the following relevant variables were examined and optimized in the experiment, formation time of gold nanoparticles, pH, buffer and stabilizer. These tests demonstrated that under optimum conditions the absorbance of Au nanoparticles at 530 nm related linearly to the concentration of Isoniazid in the range of 1.0-8.0 μg mL(-1) with a detection limit of 0.98 μg mL(-1). This colorimetric method has been successfully applied to the determine Isoniazid in tablets and spiked serum samples. The proposed colorimetric assay exhibits good reproducibility and accuracy, providing a simple and rapid method for analysis of Isoniazid. Copyright © 2013 Elsevier B.V. All rights reserved.

Localized surface plasmon resonance of gold nanoparticles as colorimetric probes for determination of Isoniazid in pharmacological formulation

NASA Astrophysics Data System (ADS)

Zargar, Behrooz; Hatamie, Amir

2013-04-01

Isoniazid is an important antibiotic, which is widely used to treat tuberculosis. This study presents a colorimetric method for the determination of Isoniazid based on localized surface plasmon resonance (LSPR) property of gold nanoparticles. An LSPR band is produced by reducing gold ions in solution using Isoniazid as the reducing agent. Influences of the following relevant variables were examined and optimized in the experiment, formation time of gold nanoparticles, pH, buffer and stabilizer. These tests demonstrated that under optimum conditions the absorbance of Au nanoparticles at 530 nm related linearly to the concentration of Isoniazid in the range of 1.0-8.0 μg mL-1 with a detection limit of 0.98 μg mL-1. This colorimetric method has been successfully applied to the determine Isoniazid in tablets and spiked serum samples. The proposed colorimetric assay exhibits good reproducibility and accuracy, providing a simple and rapid method for analysis of Isoniazid.

Colorimetric micro-assay for accelerated screening of mould inhibitors

Treesearch

Carol A. Clausen; Vina W. Yang

2013-01-01

Since current standard laboratory methods are time-consuming macro-assays that rely on subjective visual ratings of mould growth, rapid and quantitative laboratory methods are needed to screen potential mould inhibitors for use in and on cellulose-based products. A colorimetric micro-assay has been developed that uses XTT tetrazolium salt to enzymatically assess...

Rapid colorimetric sensing of tetracycline antibiotics with in situ growth of gold nanoparticles.

PubMed

Shen, Li; Chen, Jing; Li, Na; He, Pingli; Li, Zhen

2014-08-11

A colorimetric assay utilizing the formation of gold nanoparticles was developed to detect tetracycline antibiotics in fluidic samples. Tetracycline antibiotics showed the capability of directly reducing aurate salts into atomic gold which form gold nanoparticles spontaneously under proper conditions. The resulted gold nanoparticles showed characteristic plasmon absorbance at 526 nm, which can be visualized by naked eyes or with a spectrophotometer. UV-vis absorbance of the resulted gold nanoparticles is correlated directly with the concentrations of tetracycline antibiotics in the solution, allowing for quantitative colorimetric detection of tetracycline antibiotics. Reaction conditions, such as pH, temperature, reaction time, and ionic strength were optimized. Sensitivity of the colorimetric assay can be enhanced by the addition of gold nanoparticle seeds, a LOD as low as 20 ng mL(-1) can be achieved with the help of seed particles. The colorimetric assay showed minimum interference from ethanol, methanol, urea, glucose, and other antibiotics such as sulfonamides, amino glycosides etc. Validity of the method was also evaluated on urine samples spiked with tetracycline antibiotics. The method provides a broad spectrum detection method for rapid and sensitive detection of reductive substances such as tetracycline antibiotics in liquid and biological samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Maladaptive variants of conscientiousness and agreeableness.

PubMed

Samuel, Douglas B; Gore, Whitney L

2012-12-01

Although reasonably strong support has been obtained for the Five-Factor Model's (FFM) ability to account for the existing personality disorder (PD) constructs, the support for obsessive-compulsive PD (OCPD) and dependent PD (DPD) has been relatively less consistent. Specifically, the expected correlation between OCPD and the FFM trait of Conscientiousness has varied in magnitude across studies while DPD has, at times, also evinced rather weak relationships with FFM Agreeableness. We determined that these inconsistencies were due primarily to the reliance on FFM measures that lack adequate fidelity to assess the maladaptive aspects of high Conscientiousness and Agreeableness. When alternative measures were utilized, the correlations were generally large and in line with expectations. We conclude that OCPD and DPD can be fruitfully conceptualized within the FFM but encourage the use of measures that provide a comprehensive assessment of both the adaptive and maladaptive aspects of the FFM traits. © 2012 The Authors. Journal of Personality © 2012, Wiley Periodicals, Inc.

Bone Remodeling Monitor

NASA Technical Reports Server (NTRS)

Foucar, Charlie; Goldberg, Leslie; Hon, Bodin; Moore, Shannon; Williams, Evan

2009-01-01

The impact of bone loss due to different mechanical loadings in microgravity is a major concern for astronauts upon reintroduction to gravitational forces in exploration missions to the Moon and Mars. it has been shown that astronauts not only lose bone at differing rates, with levels up to 2% per month, but each astronaut will respond to bone loss treatments differently. Pre- and post-flight imaging techniques and frozen urine samples for post-flight laboratory immunoassays To develop a novel, non-invasive, highly . sensitive, portable, intuitive, and low-powered device to measure bone resorption levels in 'real time' to provide rapid and Individualized feedback to maximize the efficacy of bone loss countermeasures 1. Collect urine specimen and analyze the level of bone resorption marker, DPD (deoxypridinoline) excreted. 2. Antibodies specific to DPD conjugated with nanoshells and mixed with specimen, the change in absorbance from agglutination is measured by an optical device. 3. The concentration of DPD is displayed and recorded on a PDA

Zinc Biosorption by Seaweed Illustrated by the Zincon Colorimetric Method and the Langmuir Isotherm

ERIC Educational Resources Information Center

Areco, Maria Mar; dos Santos Afonso, Maria; Valdman, Erika

2007-01-01

An experiment is conducted to promote biotechnology knowledge that is an emerging technology on cleaning treatment, showing the potential of seaweed to remove heavy-metal ions from solution. The rapid and accurate determination of zinc in aqueous solution by the zincon colorimetric method gives an interesting and simple experiment for any…

Colorimetric and fluorescent detection of hydrazine with high sensitivity and excellent selectivity

NASA Astrophysics Data System (ADS)

Shi, Bingjie; Qi, Sujie; Yu, Mingming; Liu, Chunxia; Li, Zhanxian; Wei, Liuhe; Ni, Zhonghai

2018-01-01

It is critical to develop probes for rapid, selective, and sensitive detection of the highly toxic hydrazine in both environmental and biological science. In this work, under mild condition, a novel colorimetric and off-on fluorescent probe was synthesized for rapid recognition of hydrazine with excellent selectivity over other various species including some biological species, metal ions and anions. The limit of quantification (LOQ) value was 1.5 × 10- 4 M-3.2 × 10- 3 M (colorimetric method) and 1.5 × 10- 4 M - 3.2 × 10- 3 M (fluorescent method) with as low as detection limit of 46.2 μM.

Colorimetric determination of cyanide liberated from apricot kernels.

PubMed

Egli, K L

1977-07-01

A simple colorimetric method is described for determining the quantity of hydrogen cyanide produced by the spontaneous decomposition of amygdalin in apricot kernels. The evolved cyanide is collected in sodium hydroxide solution and assayed colorimetrically by reaction with picric acid. Results for duplicate assays, 3.02 and 3.06 mg CN-/g, compare well with those obtained by AOAC method 26.115 which specifies steam distillation and silver nitrate titration; results for triplicate assays were 3.02, 3.03, and 3.08 mg CN-/g by the latter. Recovery of cyanide from potassium cyanide at a level equivalent to 243 microgram CN-/g was 101.0%.

Colorimetric detection for paper-based biosensing applications

NASA Astrophysics Data System (ADS)

Brink, C.; Joubert, T.-H.

2016-02-01

Research on affordable point-of-care health diagnostics is rapidly advancing1. Colorimetric biosensor applications are typically qualitative, but recently the focus has been shifted to quantitative measurements2,3. Although numerous qualitative point-of-care (POC) health diagnostic devices are available, the challenge exists of developing a quantitative colorimetric array reader system that complies with the ASSURED (Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment-free, Deliverable to end-users) principles of the World Health Organization4. This paper presents a battery powered 8-bit tonal resolution colorimetric sensor circuit for paper microfluidic assays using low cost photo-detection circuitry and a low-power LED light source. A colorimetric 3×3-pixel array reader was developed for rural environments where resources and personnel are limited. The device sports an ultralow-power E-ink paper display. The colorimetric device includes integrated GPS functionality and EEPROM memory to log measurements with geo-tags for possible analysis of regional trends. The device competes with colour intensity measurement techniques using smartphone cameras, but proves to be a cheaper solution, compensating for the typical performance variations between cameras of different brands of smartphones. Inexpensive methods for quantifying bacterial assays have been shown using desktop scanners, which are not portable, and cameras, which suffer severely from changes in ambient light in different environments. Promising colorimetric detection results have been demonstrated using devices such as video cameras5, digital colour analysers6, flatbed scanners7 or custom portable readers8. The major drawback of most of these methods is the need for specialized instrumentation and for image analysis on a computer.

Stimulation of in vivo hepatic uptake and in vitro hepatic binding of (/sup 125/I)2-lodo-3,7,8-trichlorodibenzo-p-dioxin by the administration of agonist for the Ah receptor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poland, A.; Teitelbaum, P.; Glover, E.

1989-07-01

(125I)2-lodo-3,7,8-trichlorodibenzo-p-dioxin ((125I)Cl3DpD), a radiolabeled, isosteric, analogue of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), was synthesized and used to study in vivo tissue localization and in vivo tissue binding. Twenty-four hours after the administration of a tracer dose (1 X 10(-10) mol/kg) of (125I) Cl3DpD to C57BL/6J mice, the hepatic concentration of radioactivity was 1-2% of the administered dose, whereas in mice pretreated with TCDD (1 X 10(-7) mol/kg), the hepatic accumulation of radiolabel was 25-30% of that administered. Liver homogenate from TCDD-treated mice bound 4 to 10 times more (125I)Cl3DpD than homogenate from control mice. The enhancement of in vivo uptake and in vitromore » tissue binding of (125I)Cl3DpD by TCDD administration was confined to liver and was not observed in other tissues examined, kidney, lung, spleen, small intestines, and muscle. The administration of TCDD to C57BL/6J mice produces dose-related stimulation of in vivo hepatic uptake of (125I)Cl3DpD, binding of radioligand to liver homogenate, and hepatic aryl hydrocarbon hydroxylase activity, with the dose for half-maximal stimulation, ED50, varying from 1.5 to 4.0 x 10(-9) mol/kg. In congenic C57BL/6J (Ahd/Ahd) mice, which express the lower affinity Ah receptor, the ED50 values for all three responses were shifted to approximately 10-fold higher doses. 3,3',4,4',5,5'-Hexabromobiphenyl, a weak agonist for the Ah receptor produced a dose-related stimulation of these three responses in C57BL/6J mice (ED50 values of approximately 5 X 10(-7) mol/kg), but was without effect in C57BL/6J (Ahd/Ahd) mice. Stimulation of vivo hepatic uptake and in vitro liver homogenate binding of (125I)Cl3DpD was produced by administration of Ah agonists, such as 2,3,7,8-tetrachlorodibenzofuran and beta-naphthoflavone, but inactive congeners and other compounds that do not act via the Ah receptor.« less

Comparative analysis for strength serum sodium and potassium in three different methods: Flame photometry, ion-selective electrode (ISE) and colorimetric enzymatic.

PubMed

Garcia, Rafaela Alvim; Vanelli, Chislene Pereira; Pereira Junior, Olavo Dos Santos; Corrêa, José Otávio do Amaral

2018-06-19

Hydroelectrolytic disorders are common in clinical situations and may be harmful to the patient, especially those involving plasma sodium and potassium dosages. Among the possible methods for the dosages are flame photometry, ion-selective electrode (ISE) and colorimetric enzymatic method. We analyzed 175 samples in the three different methods cited from patients attending the laboratory of the University Hospital of the Federal University of Juiz de Fora. The values obtained were statistically treated using SPSS 19.0 software. The present study aims to evaluate the impact of the use of these different methods in the determination of plasma sodium and potassium. The averages obtained for sodium and potassium measurements by flame photometry were similar (P > .05) to the means obtained for the two electrolytes by ISE. The averages obtained by the colorimetric enzymatic method presented statistical difference in relation to ISE, both for sodium and potassium. In the correlation analysis, both flame photometry and colorimetric enzymatic showed a strong correlation with the ISE method for both dosages. At the first time in the same work sodium and potassium were analyzed by three different methods and the results allowed us to conclude that the methods showed a positive and strong correlation, and can be applied in the clinical routine. © 2018 Wiley Periodicals, Inc.

User Manual and Source Code for a LAMMPS Implementation of Constant Energy Dissipative Particle Dynamics (DPD-E)

DTIC Science & Technology

2014-06-01

User Manual and Source Code for a LAMMPS Implementation of Constant Energy Dissipative Particle Dynamics (DPD-E) by James P. Larentzos...Laboratory Aberdeen Proving Ground, MD 21005-5069 ARL-SR-290 June 2014 User Manual and Source Code for a LAMMPS Implementation of Constant...3. DATES COVERED (From - To) September 2013–February 2014 4. TITLE AND SUBTITLE User Manual and Source Code for a LAMMPS Implementation of

An evaluation of the effect of age and the peri-parturient period on bone metabolism in dairy cows as measured by serum bone-specific alkaline phosphatase activity and urinary deoxypyridinoline concentration.

PubMed

Sato, Reiichiro; Onda, Ken; Kato, Hajime; Ochiai, Hideharu; Kawai, Kazuhiro; Iriki, Tsunenori; Kaneko, Kazuyuki; Yamazaki, Yukio; Wada, Yasunori

2013-08-01

Various biochemical markers help to evaluate the state of bone turnover in humans and could be used during the peri-parturient period in dairy cows when calcium (Ca) metabolism changes dramatically. To investigate this, the peri-partum characteristics of serum bone-specific alkaline phosphatase (BAP) and urinary deoxypyridinoline (DPD) were investigated. Both serum BAP activity and urinary DPD concentrations were increased and demonstrated wide variability in younger animals, and these findings were consistent with other bone turnover markers. Around the time of parturition, serum Ca concentration and serum BAP activity in multiparous cows were significantly lower than in primiparous cows, but urinary DPD concentration was unchanged. The use of BAP as a bone formation marker appears to be valuable for evaluating bone remodelling status in cows, but the specificity of the test needs to be confirmed. The DPD/BAP ratio around parturition demonstrated a clear difference in bone turnover status between the two parity groups with multiparous cows demonstrating increased signs of bone resorption compared with primiparous cows, corresponding to the Ca requirement for milk production. In future studies, the applicability of the ratio of bone resorption marker to bone formation marker should be evaluated for bone turnover assessment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Spatial averaging of a dissipative particle dynamics model for active suspensions

NASA Astrophysics Data System (ADS)

Panchenko, Alexander; Hinz, Denis F.; Fried, Eliot

2018-03-01

Starting from a fine-scale dissipative particle dynamics (DPD) model of self-motile point particles, we derive meso-scale continuum equations by applying a spatial averaging version of the Irving-Kirkwood-Noll procedure. Since the method does not rely on kinetic theory, the derivation is valid for highly concentrated particle systems. Spatial averaging yields stochastic continuum equations similar to those of Toner and Tu. However, our theory also involves a constitutive equation for the average fluctuation force. According to this equation, both the strength and the probability distribution vary with time and position through the effective mass density. The statistics of the fluctuation force also depend on the fine scale dissipative force equation, the physical temperature, and two additional parameters which characterize fluctuation strengths. Although the self-propulsion force entering our DPD model contains no explicit mechanism for aligning the velocities of neighboring particles, our averaged coarse-scale equations include the commonly encountered cubically nonlinear (internal) body force density.

Visual detection of organophosphorus pesticides represented by mathamidophos using Au nanoparticles as colorimetric probe.

PubMed

Li, Hongkun; Guo, Jiajia; Ping, Hong; Liu, Lurui; Zhang, Minwei; Guan, Fengrui; Sun, Chunyan; Zhang, Qian

2011-12-15

With citrate-coated Au nanoparticles as colorimetric probe, a novel visual method for rapid assay of organophosphorus pesticides has been developed. The assay principle is based on catalytic hydrolysis of acetylthiocholine into thiocholine by acetylcholinesterase, which induces the aggregation of Au nanoparticles and the color change from claret-red to purple or even grey. The original plasmon absorption of Au nanoparticles at 522 nm decreases, and simultaneously, a new absorption band appears at 675 nm. The irreversible inhibition of organophosphorus pesticides on acetylcholinesterase prevents aggregation of Au nanoparticles. Under optimum conditions, the absorbance at 522 nm of Au nanoparticles is related linearly to the concentration of mathamidophos in the range of 0.02-1.42 μg/mL with a detection limit of 1.40 ng/mL. This colorimetric method has been successfully utilized to detect mathamidophos in vegetables with satisfactory results. The proposed colorimetric assay exhibits good reproducibility and accuracy, providing a simple and rapid method for the analysis of organophosphorus pesticides. Copyright © 2011 Elsevier B.V. All rights reserved.

4-Aminothiophenol functionalized gold nanoparticle-based colorimetric sensor for the determination of nitramine energetic materials.

PubMed

Üzer, Ayşem; Can, Ziya; Akın, Ilknur; Erçağ, Erol; Apak, Reşat

2014-01-07

The heterocyclic nitramine compounds, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), are two most important military-purpose high explosives. Differentiation of RDX and HMX with colorimetric methods of determination has not yet been made because of their similar chemical structures. In this study, a sensitive colorimetric method for the determination of RDX and HMX was proposed on the basis of differential kinetics in the hydrolysis of the two compounds (yielding nitrite as a product) followed by their colorimetric determination using 4-aminothiophenol (4-ATP) modified gold nanoparticles (AuNPs) and naphthylethylene diamine (NED) as coupling agent for azo-dye formation, abbreviated as "4-ATP-AuNP+NED" colorimetric method. After alkaline hydrolysis in a 1 M Na2CO3 + 0.04 M NaOH mixture solution at room temperature, only RDX (but not HMX) was hydrolyzed to give a sufficient colorimetric response in neutralized solution, the molar absorptivity (ε) at 565 nm and the limit of detection (LOD) for RDX being (17.6 ± 1.3) × 10(3) L mol(-1) cm(-1) and 0.55 μg mL(-1), respectively. On the other hand, hot water bath (at 60 °C) hydrolysis enabled both nitramines, RDX and HMX, to give substantial colorimetric responses; i.e., ε and LOD for RDX were (32.8 ± 0.5) × 10(3) L mol(-1)cm(-1) and 0.20 μg mL(-1) and for HMX were (37.1 ± 2.8) × 10(3) L mol(-1)cm(-1) and 0.24 μg mL(-1), respectively. Unlike other AuNP-based nitrite sensors in the literature showing absorbance quenching within a relatively narrow concentration range, the developed sensor operated with an absorbance increase over a wide range of nitrite. Synthetic mixtures of (RDX + HMX) gave additive responses, and the proposed method was statistically validated against HPLC using nitramine mixtures.

Protein-bound polysaccharide-K augments the anticancer effect of fluoropyrimidine derivatives possibly by lowering dihydropyrimidine dehydrogenase expression in gastrointestinal cancers.

PubMed

Mekata, Eiji; Murata, Satoshi; Sonoda, Hiromichi; Shimizu, Tomoharu; Umeda, Tomoko; Shiomi, Hisanori; Naka, Shigeyuki; Yamamoto, Hiroshi; Abe, Hajime; Edamatsu, Takeo; Fujieda, Ayako; Fujioka, Masaki; Wada, Tsutomu; Tani, Tohru

2013-12-01

Protein-bound polysaccharide-K (PSK) enhances the antitumor effect of anticancer drug when used clinically in combination with such drugs. PSK is known to act by immune-mediated mechanisms; however, the relationship between PSK and metabolic enzymes of anticancer drugs is unknown. We used the collagen gel droplet-embedded culture drug sensitivity test (CD-DST) clinically to evaluate the sensitivity of anticancer drugs. In the present study, we modified the CD-DST by adding peripheral blood mononuclear cells (PBMCs) (immuno-CD-DST) and examined the antitumor effect of PSK in combination with anticancer drugs. First, HCT116 human colon cancer cells were cultured with PSK and 5-fluorouracil (5-FU) or 5'-deoxy-5-fluorouridine (5'-DFUR) in the presence or absence of PBMCs, and the antiproliferative effects were compared. In the presence of PBMCs, PSK augmented the inhibitory effects of 5-FU and 5'-DFUR on HCT116 cell proliferation. Next, using human gastric cancer and colon cancer cell lines, the effects of PSK on mRNA expression of various metabolic enzymes of fluoropyrimidines: dihydropyrimidine dehydrogenase (DPD), thymidylate synthase, thymidine phosphorylase and orotate phosphoribosyl transferase, were examined by real-time PCR. PSK significantly enhanced DPD mRNA expression in all of the cancer cell lines tested, but not those of the other enzymes. Addition of IFN-α and TRAIL, cytokines known to inhibit DPD expression, to the cultures reduced DPD mRNA expression in the cancer cells. When PBMC samples collected from healthy volunteers were cultured with PSK, IFN-α mRNA expression increased in 3 of the 5 PBMC samples, while TRAIL mRNA expression was unchanged. The present results propose the possibility that PSK induces PBMCs to express IFN-α which inhibits DPD expression, and consequently augments the antitumor effect of 5-FU or 5'-DFUR. Immuno-CD-DST is useful for evaluating drugs with immunological mechanisms of action.

Noninvasive markers of bone metabolism in the rhesus monkey: normal effects of age and gender

NASA Technical Reports Server (NTRS)

Cahoon, S.; Boden, S. D.; Gould, K. G.; Vailas, A. C.

1996-01-01

Measurement of bone turnover in conditions such as osteoporosis has been limited by the need for invasive iliac bone biopsy to reliably determine parameters of bone metabolism. Recent advances in the area of serum and urinary markers of bone metabolism have raised the possibility for noninvasive measurements; however, little nonhuman primate data exist for these parameters. The purpose of this experiment was to define the normal range and variability of several of the newer noninvasive bone markers which are currently under investigation in humans. The primary intent was to determine age and gender variability, as well as provide some normative data for future experiments in nonhuman primates. Twenty-four rhesus macaques were divided into equal groups of male and female according to the following age groupings: 3 years, 5-10 years, 15-20 years, and > 25 years. Urine was collected three times daily for a four-day period and measured for several markers of bone turnoverm including pyridinoline (PYD), deoxypyrodinoline (DPD), hydroxyproline, and creatinine. Bone mineral density measurements of the lumbar spine were performed at the beginning and end of the study period. Serum was also obtained at the time of bone densitometry for measurement of osteocalcin levels by radioimmunoassay. There were no significant differences in bone mineral density, urine PYD, or urine DPD based on gender. Bone density was lowest in the youngest animals, peaked in the 15-20-year group, but again decreased in the oldest animals. The osteocalcin, PYD, and DPD levels followed an inversely related pattern to bone density. The most important result was the relative age insensitivity of the ratio of PYD:DPD in monkeys up to age 20 years. Since bone density changes take months or years to become measurable and iliac biopsies are invasive, the PYD/DPD marker ratio may have important implications for rapid noninvasive measurement of the effects of potential treatments for osteoporosis in the non-human primate model.

Modeling of Red Blood Cells and Related Spleen Function

NASA Astrophysics Data System (ADS)

Peng, Zhangli; Pivkin, Igor; Dao, Ming

2011-11-01

A key function of the spleen is to clear red blood cells (RBCs) with abnormal mechanical properties from the circulation. These abnormal mechanical properties may be due to RBC aging or RBC diseases, e.g., malaria and sickle cell anemia. Specifically, 10% of RBCs passing through the spleen are forced to squeeze into the narrow slits between the endothelial cells, and stiffer cells which get stuck are killed and digested by macrophages. To investigate this important physiological process, we employ three different approaches to study RBCs passage through these small slits, including analytical theory, Dissipative Particle Dynamics (DPD) simulation and Multiscale Finite Element Method (MS-FEM). By applying the analytical theory, we estimate the critical limiting geometries RBCs can pass. By using the DPD method, we study the full fluid-structure interaction problem, and compute RBC deformation under different pressure gradients. By employing the MS-FEM approach, we model the lipid bilayer and the cytoskeleton as two distinct layers, and focus on the cytoskeleton deformation and the bilayer-skeleton interaction force at the molecular level. Finally the results of these three approaches are compared to each other and correlated to the experimental observations.

[Comparative research into sensitivity and specificity of immune-enzyme analysis with chemiluminescence and colorimetric detection for detecting antigens and antibodies to avian influenza viruses and newcastle disease].

PubMed

Vitkova, O N; Kapustina, T P; Mikhailova, V V; Safonov, G A; Vlasova, N N; Belousova, R V

2015-01-01

The goal of this work was to demonstrate the results of the development of the enzyme-linked immunosorbent tests with chemiluminescence detection and colorimetric detection of specific viral antigens and antibodies for identifying the avian influenza and the Newcastle disease viruses: high sensitivity and specificity of the immuno- chemiluminescence assay, which are 10-50 times higher than those of the ELISA colorimetric method. The high effectiveness of the results and the automation of the process of laboratory testing (using a luminometer) allow these methods to be recommended for including in primary screening tests for these infectious diseases.

Collagen degradation products and proinflammatory cytokines in systemic and localized scleroderma.

PubMed

Becvár, R; Hulejová, H; Braun, M; Stork, J

2007-01-01

The aim of this study was to assess the degradation of collagen type I and proinflammatory cytokines in systemic and localized scleroderma compared with psoriasis and healthy controls. Total 99 individuals were examined - 24 with SSc, 22 with LSc, 39 patients with PsV and 14 healthy controls. U-PD and U-DPD were measured using a sensitive isocratic HPLC method. Serum levels of IL-6 and soluble IL-2R were assayed using commercial ELISA kits. In the SSc group U-PD and U-DPD levels (nmol/mmol creatinine) were increased compared with controls (P = 0.001) and with PsV (P = 0.006). IL-6 levels were increased compared with controls (P = 0.004) and with PsV (P = 0.002). IL-2R concentrations were insignificantly increased in comparison with controls and were lower than in PsV, but the difference was not significant. In the LSc group excretion of U-PD and U-DPD did not differ from controls, but was insignificantly decreased compared with PsV. IL-6 levels were increased compared with controls (P = 0.001) and also with PsV (P = 0.03). IL-2R concentrations were significantly increased in comparison with controls only (P = 0.03). In patients with SSc our data have shown the most intensive collagen degradation and simultaneously an active inflammation, as documented by IL-6, which reflects the pathological processes in the skin and visceral organs compared with PsV patients and healthy individuals. In the LSc group collagen degradation was similar to that in control groups, but a certain inflammatory activity was observed.

Discovering the enzyme mimetic activity of metal-organic framework (MOF) for label-free and colorimetric sensing of biomolecules.

PubMed

Wang, Ying; Zhu, Yingjing; Binyam, Atsebeha; Liu, Misha; Wu, Yinan; Li, Fengting

2016-12-15

A label-free sensing strategy based on the enzyme-mimicking activity of MOF was demonstrated for colorimetric detection of biomolecules. Firstly obvious blue color was observed due to the high efficiency of peroxidase-like catalytic activity of Fe-MIL-88A (an ion-based MOF material) toward 3,3',5,5'-tetramethylbenzidine (TMB). Then in the presence of target biomolecule and corresponding aptamer, the mimetic activity of Fe-MIL-88A can be strongly inhibited and used directly to realize the colorimetric detection. On the basis of the interesting findings, we designed a straightforward, label-free and sensitive colorimetric method for biomolecule detection by using the enzyme mimetic property of MOF coupling with molecular recognition element. Compared with the existed publications, our work breaks the routine way by setting up an inorganic-organic MOF-aptamer hybrid platform for colorimetric determination of biomolecules, expanding the targets scope from H2O2 or glucose to biomolecules. As a proof of concept, thrombin and thrombin aptamer was used as a model analyte. The limit of detection of 10nM can be achieved with naked eyes and ultrahigh selectivity of thrombin toward numerous interfering substances with 10-fold concentration was demonstrated significantly. Of note, the method was further applied for the detection of thrombin in human serum samples, showing the results in agreement with those values obtained in an immobilization buffer by the colorimetric method. This inorganic-organic MOF-aptamer sensing strategy may in principle be universally applicable for the detection of a range of environmental or biomedical molecules of interests. Copyright © 2016 Elsevier B.V. All rights reserved.

Self-Referenced Smartphone-Based Nanoplasmonic Imaging Platform for Colorimetric Biochemical Sensing.

PubMed

Wang, Xinhao; Chang, Te-Wei; Lin, Guohong; Gartia, Manas Ranjan; Liu, Gang Logan

2017-01-03

Colorimetric sensors usually suffer due to errors from variation in light source intensity, the type of light source, the Bayer filter algorithm, and the sensitivity of the camera to incoming light. Here, we demonstrate a self-referenced portable smartphone-based plasmonic sensing platform integrated with an internal reference sample along with an image processing method to perform colorimetric sensing. Two sensing principles based on unique nanoplasmonics enabled phenomena from a nanostructured plasmonic sensor, named as nanoLCA (nano Lycurgus cup array), were demonstrated here for colorimetric biochemical sensing: liquid refractive index sensing and optical absorbance enhancement sensing. Refractive indices of colorless liquids were measured by simple smartphone imaging and color analysis. Optical absorbance enhancement in the colorimetric biochemical assay was achieved by matching the plasmon resonance wavelength with the chromophore's absorbance peak wavelength. Such a sensing mechanism improved the limit of detection (LoD) by 100 times in a microplate reader format. Compared with a traditional colorimetric assay such as urine testing strips, a smartphone plasmon enhanced colorimetric sensing system provided 30 times improvement in the LoD. The platform was applied for simulated urine testing to precisely identify the samples with higher protein concentration, which showed potential point-of-care and early detection of kidney disease with the smartphone plasmonic resonance sensing system.

Coarse-Grained Models for Automated Fragmentation and Parametrization of Molecular Databases.

PubMed

Fraaije, Johannes G E M; van Male, Jan; Becherer, Paul; Serral Gracià, Rubèn

2016-12-27

We calibrate coarse-grained interaction potentials suitable for screening large data sets in top-down fashion. Three new algorithms are introduced: (i) automated decomposition of molecules into coarse-grained units (fragmentation); (ii) Coarse-Grained Reference Interaction Site Model-Hypernetted Chain (CG RISM-HNC) as an intermediate proxy for dissipative particle dynamics (DPD); and (iii) a simple top-down coarse-grained interaction potential/model based on activity coefficient theories from engineering (using COSMO-RS). We find that the fragment distribution follows Zipf and Heaps scaling laws. The accuracy in Gibbs energy of mixing calculations is a few tenths of a kilocalorie per mole. As a final proof of principle, we use full coarse-grained sampling through DPD thermodynamics integration to calculate log P OW for 4627 compounds with an average error of 0.84 log unit. The computational speeds per calculation are a few seconds for CG RISM-HNC and a few minutes for DPD thermodynamic integration.

Method for hue plane preserving color correction.

PubMed

Mackiewicz, Michal; Andersen, Casper F; Finlayson, Graham

2016-11-01

Hue plane preserving color correction (HPPCC), introduced by Andersen and Hardeberg [Proceedings of the 13th Color and Imaging Conference (CIC) (2005), pp. 141-146], maps device-dependent color values (RGB) to colorimetric color values (XYZ) using a set of linear transforms, realized by white point preserving 3×3 matrices, where each transform is learned and applied in a subregion of color space, defined by two adjacent hue planes. The hue plane delimited subregions of camera RGB values are mapped to corresponding hue plane delimited subregions of estimated colorimetric XYZ values. Hue planes are geometrical half-planes, where each is defined by the neutral axis and a chromatic color in a linear color space. The key advantage of the HPPCC method is that, while offering an estimation accuracy of higher order methods, it maintains the linear colorimetric relations of colors in hue planes. As a significant result, it therefore also renders the colorimetric estimates invariant to exposure and shading of object reflection. In this paper, we present a new flexible and robust version of HPPCC using constrained least squares in the optimization, where the subregions can be chosen freely in number and position in order to optimize the results while constraining transform continuity at the subregion boundaries. The method is compared to a selection of other state-of-the-art characterization methods, and the results show that it outperforms the original HPPCC method.

Field demonstration of on-site analytical methods for TNT and RDX in ground water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Craig, H.; Ferguson, G.; Markos, A.

1996-12-31

A field demonstration was conducted to assess the performance of eight commercially-available and emerging colorimetric, immunoassay, and biosensor on-site analytical methods for explosives 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in ground water and leachate at the Umatilla Army Depot Activity, Hermiston, Oregon and US Naval Submarine Base, Bangor, Washington, Superfund sites. Ground water samples were analyzed by each of the on-site methods and results compared to laboratory analysis using high performance liquid chromatography (HPLC) with EPA SW-846 Method 8330. The commercial methods evaluated include the EnSys, Inc., TNT and RDX colorimetric test kits (EPA SW-846 Methods 8515 and 8510) with amore » solid phase extraction (SPE) step, the DTECH/EM Science TNT and RDX immunoassay test kits (EPA SW-846 Methods 4050 and 4051), and the Ohmicron TNT immunoassay test kit. The emerging methods tested include the antibody-based Naval Research Laboratory (NRL) Continuous Flow Immunosensor (CFI) for TNT and RDX, and the Fiber Optic Biosensor (FOB) for TNT. Accuracy of the on-site methods were evaluated using linear regression analysis and relative percent difference (RPD) comparison criteria. Over the range of conditions tested, the colorimetric methods for TNT and RDX showed the highest accuracy of the emerging methods for TNT and RDX. The colorimetric method was selected for routine ground water monitoring at the Umatilla site, and further field testing on the NRL CFI and FOB biosensors will continue at both Superfund sites.« less

Sensorimotor gating characteristics of violent men with comorbid psychosis and dissocial personality disorder: Relationship with antisocial traits and psychosocial deprivation.

PubMed

Sedgwick, Ottilie; Young, Susan; Greer, Ben; Arnold, Jack; Parsons, Aisling; Puzzo, Ignazio; Terracciano, Mariafatima; Das, Mrigendra; Kumari, Veena

2017-07-06

Evidence suggests violence amongst those with psychosis is not aetiologically homogeneous, and that a large proportion of those who engage in violent behaviour have a comorbid antisocial personality disorder. Initial investigations indicate that this subgroup has distinct historical and neuropsychological characteristics, which may indicate diverse treatment needs. This study investigated sensorimotor gating characteristics of violent men with diagnoses of both psychosis and dissocial personality disorder (DPD) (n=21) relative to violent men with psychosis alone (n=12), DPD alone (n=14) and healthy, non-violent male controls (n=27), using the prepulse inhibition (PPI) paradigm. The results indicated that, relative to the psychosis alone and healthy control groups, the comorbid group had lower PPI, especially at 60-ms prepulse-to-pulse interval. The DPD group took an intermediary position and did not differ from any group. Antisocial personality traits (factor two scores of the Psychopathy Checklist - Revised), and greater severity of childhood psychosocial deprivation (including physical and sexual abuse), were significantly correlated with poor PPI across the clinical sample. The findings suggest diverse sensorimotor gating profiles amongst subgroups of violent offenders, with comorbid psychosis and DPD showing most impairment. This is consistent with a 'double dose' of deficit explanation amongst those with both diagnoses, explained at least in part by presence of antisocial personality traits and childhood psychosocial deprivation. Copyright © 2017 Elsevier B.V. All rights reserved.

A comparison of bone-related biomarkers and CA27.29 to assess response to treatment of osseous metastatic breast cancer.

PubMed

Lüfter, D; Richter, A; Günther, S; Flath, B; Akrivakis, C; Geppert, R; Wernecke, K D; Possinger, K

2000-01-01

The assessment of bone metastases by clinical examination or imaging techniques is still considered unreliable. We compared a specific marker of bone resorption, urinary deoxypyridinoline (DPD)-crosslinks, with serum calcium (Ca), alkaline phosphatase (AP) and CA27.29, to evaluate the status of bone metastases in patients with breast cancer. Second morning voided urine was collected from 2 groups of patient (pts), those without evidence of disease (n = 118), and those with bone metastases (n = 85) under specific therapy plus pamidronate. DPD and CA27.29 were measured on the automated ACS180 system (Bayer Diagnostics, Tarrytown, NY, USA). Receiver operating characteristics (ROC) curves were established for each of the 4 biomarkers to determine whether they could distinguish the 2 subsets of pts with clinically sufficient validity, and to establish the corresponding cut-off values. Neither Ca nor AP was useful in discriminating the 2 subgroups. At a DPD cut-off of 13 nmol/mmol, we found a specificity of 69% and a sensitivity of 53% for diagnosing bone metastases. Best results, however, were seen for CA27.29. A cut-off value of 30 U/ml resulted in a specificity of 62% and a sensitivity of 81%. CA27.29 was the best parameter for the discrimination of stage IV breast cancer with bone metastases. The primary advantage of DPD lies in the monitoring of bone metastases under specific therapy.

Biochemical markers of bone turnover in diagnosis of myeloma bone disease.

PubMed

Dizdar, Omer; Barista, Ibrahim; Kalyoncu, Umut; Karadag, Omer; Hascelik, Gulsen; Cila, Aysenur; Pinar, Asli; Celik, Ismail; Kars, Ayse; Tekuzman, Gulten

2007-03-01

This study was designed to explore the value of markers of bone turnover, macrophage inflammatory protein-1alpha (MIP-1alpha), and osteopontin (OPN) in the diagnosis of myeloma bone disease. Twenty-five patients with newly diagnosed and untreated multiple myeloma (MM), and 22 age-, sex-, and bone mineral density-matched control subjects were enrolled. Levels of MIP-1alpha, OPN, carboxy-terminal telopeptide of Type-1 collagen (C-telopeptide or Ctx), deoxypyridinoline (DPD), Type-1 collagen propeptide (T1Pro), and bone-specific alkaline phosphatase (BALP) were assessed in both groups. Twenty-two of the patients had bone involvement documented by skeletal surveys and lumbar spinal magnetic resonance imaging. Levels of serum Ctx, OPN, MIP-1alpha, and urine DPD were significantly higher in MM patients with bone disease than in controls (P<0.01). Serum Ctx levels were elevated in 90.9% of patients with MM and 40.9% of controls (P<0.001). Urine DPD levels were elevated in 90.4% of the patients and 31.8% of the controls (P<0.001). The serum OPN and MIP-1alpha levels of the patients were significantly correlated with beta2-microglobulin and lactate dehydrogenase levels (P<0.05). Our study indicates that Ctx and DPD are sensitive markers of bone disease in MM, and higher than normal values suggest presence of bone disease rather than benign osteoporosis in MM. The utility of OPN and MIP-1alpha needs to be further investigated. Copyright (c) 2006 Wiley-Liss, Inc.

A DPYD variant (Y186C) specific to individuals of African descent in a patient with life-threatening 5-FU toxic effects: potential for an individualized medicine approach.

PubMed

Saif, M Wasif; Lee, Adam M; Offer, Steven M; McConnell, Kathleen; Relias, Valerie; Diasio, Robert B

2014-01-01

5-Fluorouracil (5-FU) is commonly administered as a therapeutic agent for the treatment of various aggressive cancers. Severe toxic reactions to 5-FU have been associated with decreased levels of dihydropyrimidine dehydrogenase (DPD) enzyme activity. Manifestations of 5-FU toxicity typically include cytopenia, diarrhea, stomatitis, mucositis, neurotoxicity, and, in extreme cases, death. A variety of genetic variations in DPYD, the gene encoding DPD, are known to result in decreased DPD enzyme activity and to contribute to 5-FU toxic effects. Recently, it was reported that healthy African American individuals carrying the Y186C DPYD variant (rs115232898) had significantly reduced DPD enzyme activity compared with noncarriers of Y186C. Herein, we describe for the first time, to our knowledge, an African American patient with cancer with the Y186C variant who had severe toxic effects after administration of the standard dose of 5-FU chemotherapy. The patient lacked any additional toxic effect-associated variations in the DPYD gene or the thymidylate synthase (TYMS) promoter. This case suggests that Y186C may have contributed to 5-FU toxicity in this patient and supports the use of Y186C as a predictive marker for 5-FU toxic effects in individuals of African ancestry. Copyright © 2014 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.

Adaptations of the Saker-Solomons test: simple, reliable colorimetric field assays for chloroquine and its metabolites in urine.

PubMed

Mount, D L; Nahlen, B L; Patchen, L C; Churchill, F C

1989-01-01

Two field-adapted colorimetric methods for measuring the antimalarial drug chloroquine in urine are described. Both are modifications of the method of Saker and Solomons for screening urine for phencyclidine and other drugs of abuse, using the colour reagent tetrabromophenolphthalein ethyl ester. One method is semiquantitative, detecting the presence of chloroquine (Cq) and its metabolites in urine with a 1 microgram/ml detection limit; it is more sensitive and reliable than the commonly used Dill-Glazko method and is as easy to apply in the field. The second method uses a hand-held, battery-operated filter photometer to quantify Cq and its metabolites with a 2 microgram/ml detection limit and a linear range up to 8 micrograms/ml. The first method was validated in the field using a published quantitative colorimetric method and samples from a malaria study in Nigeria. The second method was validated in the laboratory against high-performance liquid chromatographic results on paired samples from the Nigerian study. Both methods may be used in remote locations where malaria is endemic and no electricity is available.

Multispectral Image Compression for Improvement of Colorimetric and Spectral Reproducibility by Nonlinear Spectral Transform

NASA Astrophysics Data System (ADS)

Yu, Shanshan; Murakami, Yuri; Obi, Takashi; Yamaguchi, Masahiro; Ohyama, Nagaaki

2006-09-01

The article proposes a multispectral image compression scheme using nonlinear spectral transform for better colorimetric and spectral reproducibility. In the method, we show the reduction of colorimetric error under a defined viewing illuminant and also that spectral accuracy can be improved simultaneously using a nonlinear spectral transform called Labplus, which takes into account the nonlinearity of human color vision. Moreover, we show that the addition of diagonal matrices to Labplus can further preserve the spectral accuracy and has a generalized effect of improving the colorimetric accuracy under other viewing illuminants than the defined one. Finally, we discuss the usage of the first-order Markov model to form the analysis vectors for the higher order channels in Labplus to reduce the computational complexity. We implement a multispectral image compression system that integrates Labplus with JPEG2000 for high colorimetric and spectral reproducibility. Experimental results for a 16-band multispectral image show the effectiveness of the proposed scheme.

Visualizing Capsaicinoids: Colorimetric Analysis of Chili Peppers

ERIC Educational Resources Information Center

Thompson, Robert Q.; Chu, Christopher; Gent, Robin; Gould, Alexandra P.; Rios, Laura; Vertigan, Theresa M.

2012-01-01

A colorimetric method for total capsaicinoids in chili pepper ("Capsicum") fruit is described. The placental material of the pepper, containing 90% of the capsaicinoids, was physically separated from the colored materials in the pericarp and extracted twice with methanol, capturing 85% of the remaining capsaicinoids. The extract, evaporated and…

Modified nondestructive colorimetric method to evaluate the variability of oxygen diffusion rate through wine bottle closures.

PubMed

Brotto, Laura; Battistutta, Franco; Tat, Lara; Comuzzo, Piergiorgio; Zironi, Roberto

2010-03-24

Some modifications to a previous nondestructive colorimetric method that permits evaluation of the oxygen diffusion rate through wine closures were proposed. The method is based on the reaction of indigo carmine solution with oxygen and the tristimulus measurement of the consequent color change. Simplified preparation and measurement procedures were set up, allowing the analysis of a large number of samples simultaneously. The method was applied to the evaluation of the variability within the lot of 20 different types of stoppers (synthetic, produced by molding, and natural cork). The closures were tested at a storage temperature of 26 degrees C. With regard to oxygen permeability, the natural cork stopper showed a low homogeneity within the lot, especially during the first month after bottling, whereas the synthetic closure showed a greater steadiness in the performance. The limits of the colorimetric method were also analyzed, and three possible causes of degradation of the indigo carmine solution were identified: oxygen, light, and heat.

Assessment of simple colorimetric procedures to determine smoking status of diabetic subjects.

PubMed

Smith, R F; Mather, H M; Ellard, G A

1998-02-01

The performance of a simple colorimetric assay for urinary nicotine metabolites to assess smoking status in diabetic subjects (n = 251) was investigated. Several variations of the colorimetric assay and a qualitative extraction procedure were evaluated in comparison with a cotinine immunoassay as the "gold standard." Among these, the best overall performance was achieved with the qualitative test (sensitivity 95%; specificity 100%). The quantitative measurement of total nicotine metabolites performed less well (sensitivity 92%; specificity 97%) but could be improved by incorporating a blank extraction (sensitivity 98%; specificity 98%). Allowance for diuresis appeared to offer no advantage over the other methods. These results support previous findings regarding the use of these colorimetric procedures in nondiabetic subjects and, contrary to other recent observations, their performance was not impaired in diabetic patients.

Systematic parameter inference in stochastic mesoscopic modeling

NASA Astrophysics Data System (ADS)

Lei, Huan; Yang, Xiu; Li, Zhen; Karniadakis, George Em

2017-02-01

We propose a method to efficiently determine the optimal coarse-grained force field in mesoscopic stochastic simulations of Newtonian fluid and polymer melt systems modeled by dissipative particle dynamics (DPD) and energy conserving dissipative particle dynamics (eDPD). The response surfaces of various target properties (viscosity, diffusivity, pressure, etc.) with respect to model parameters are constructed based on the generalized polynomial chaos (gPC) expansion using simulation results on sampling points (e.g., individual parameter sets). To alleviate the computational cost to evaluate the target properties, we employ the compressive sensing method to compute the coefficients of the dominant gPC terms given the prior knowledge that the coefficients are "sparse". The proposed method shows comparable accuracy with the standard probabilistic collocation method (PCM) while it imposes a much weaker restriction on the number of the simulation samples especially for systems with high dimensional parametric space. Fully access to the response surfaces within the confidence range enables us to infer the optimal force parameters given the desirable values of target properties at the macroscopic scale. Moreover, it enables us to investigate the intrinsic relationship between the model parameters, identify possible degeneracies in the parameter space, and optimize the model by eliminating model redundancies. The proposed method provides an efficient alternative approach for constructing mesoscopic models by inferring model parameters to recover target properties of the physics systems (e.g., from experimental measurements), where those force field parameters and formulation cannot be derived from the microscopic level in a straight forward way.

Combined enzymatic and colorimetric method for determining the uronic acid and methylester content of pectin: Application to tomato products.

PubMed

Anthon, Gordon E; Barrett, Diane M

2008-09-01

A simple procedure for determining the galacturonic acid and methanol contents of soluble and insoluble pectins, relying on enzymatic pectin hydrolysis and colorimetric quantification, is described. Pectin samples are incubated with a commercial pectinase preparation, Viscozyme, then the galacturonic acid content of the hydrolyzed pectin is quantified colorimetrically using a modification of the Cu reduction procedure originally described by Avigad and Milner. This modification, substituting the commonly used Folin-Ciocalteau reagent for the arsenic containing Nelson reagent, gives a response that is linear, sensitive, and selective for uronic acids over neutral sugars. This method also avoids the use of concentrated acids needed for the commonly used m-phenylphenol method. Methanol, released by the action of the pectin methylesterase found in the Viscozyme, is quantified using alcohol oxidase and Purpald. This combined enzymatic and colorimetric procedure correctly determined the galacturonic acid and methanol content of purified, soluble citrus pectin. Application of the procedure to water insoluble pectins was evaluated with water insoluble material from apples and oranges. In both cases good agreement was obtained between this method and commonly used methods based on chemical pectin hydrolysis. Good agreement between these procedures was also found in the analysis of both soluble and insoluble pectins from several tomato products. Copyright © 2008 Elsevier Ltd. All rights reserved.

Offset-sparsity decomposition for enhancement of color microscopic image of stained specimen in histopathology: further results

NASA Astrophysics Data System (ADS)

Kopriva, Ivica; Popović Hadžija, Marijana; Hadžija, Mirko; Aralica, Gorana

2016-03-01

Recently, novel data-driven offset-sparsity decomposition (OSD) method was proposed by us to increase colorimetric difference between tissue-structures present in the color microscopic image of stained specimen in histopathology. The OSD method performs additive decomposition of vectorized spectral images into image-adapted offset term and sparse term. Thereby, the sparse term represents an enhanced image. The method was tested on images of the histological slides of human liver stained with hematoxylin and eosin, anti-CD34 monoclonal antibody and Sudan III. Herein, we present further results related to increase of colorimetric difference between tissue structures present in the images of human liver specimens with pancreatic carcinoma metastasis stained with Gomori, CK7, CDX2 and LCA, and with colon carcinoma metastasis stained with Gomori, CK20 and PAN CK. Obtained relative increase of colorimetric difference is in the range [19.36%, 103.94%].

Dihydropyrimidine dehydrogenase gene (DPYD) polymorphism among Caucasian and non-Caucasian patients with 5-FU- and capecitabine-related toxicity using full sequencing of DPYD.

PubMed

Saif, Muhammad Wasif

2013-01-01

Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme of the degradation of pyrimidine base, and plays a pivotal role in the pharmacogenetic syndrome of 5-fluorouracil (5-FU). Deficiency of DPD activity leads to severe toxicities, even death, following administration of 5-FU. Several studies have demonstrated that molecular defects of the dihydropyrimidine dehydrogenase gene (DPYD) lead to the deficiency of DPD activity and cause this pharmacogenetic syndrome. We present the analysis of DPYD genotyping in untreated Caucasian patients (control group) and Caucasian patients with 5-FU/CAP-related grade 3/4 toxicities (toxicity group) who underwent a capecitabine TheraGuide 5-FU testing. Full sequencing of DPYD was performed in the Myriad Genetic Laboratories, Inc. as part of TheraGuide 5-FU test. Among 227 patients from the toxicity group, 27 (12%) had deleterious mutations in DPYD: twelve (5%) had IVS14 +1 G>A, eleven (5%) had D949V and four (2%) had other mutations. Only 7/192 (4%) patients from the control group had DPYD genotype abnormalities: two (1%) had IVS14 +1 G>A, four (2%) had D949V and one (1%) had other mutation. Genotype abnormalities were observed more frequently in the toxicity group (p=0.001). Among 65 patients with toxicities due to capecitabine, nine (14%) had mutated DPYD, which was more frequent than in the control group (p=0.006). Mutated DPYD is frequently observed in Caucasian patients who experience toxicities while receiving 5-FU/capecitabine. Screening of patients for DPYD mutations prior to administration of 5-FU/capecitabine using new pharmacogenetic testing methods, may help for identify those patients who are at greatest risk for adverse effects, allowing a more individualized approach to their chemotherapy management.

CASPR2 autoantibodies are raised during pregnancy in mothers of children with mental retardation and disorders of psychological development but not autism

PubMed Central

Coutinho, Ester; Jacobson, Leslie; Pedersen, Marianne Giørtz; Benros, Michael Eriksen; Nørgaard-Pedersen, Bent; Mortensen, Preben Bo; Harrison, Paul J; Vincent, Angela

2017-01-01

Background, Methods and Objectives Maternal autoantibodies to neuronal proteins may be one cause of neurodevelopmental disorders. This exploratory study used the Danish archived midgestational sera and their nationwide registers to search for antibodies to the N-methyl-D-aspartate receptor (NMDAR) and contactin-associated protein-like 2 (CASPR2) in maternal sera, and to relate them to subsequent psychiatric diagnoses in the woman or her child. Results In a sample of 192 women, there was no association between antibody status and subsequent psychosis in the mothers. However, NMDAR antibodies (n=4) or CASPR2 antibodies (n=1) were identified in 5/11 (45.5%) women whose children were given a diagnosis of mild or unspecified mental retardation or disorders of psychological and motor development (collectively abbreviated as mental retardation and/or disorders of psychological development (MR/DPD)) compared with 9/176 (5.1%) of the remaining mother (p<0.001). These findings were followed up in a specifically selected cohort, in which CASPR2 antibodies were detected in 7/171 (4.1%) mothers of MR/DPD progeny, compared with only 1/171 (0.6%) control mother (p=0.067). The combined sample showed a significantly higher frequency of CASPR2 antibodies in mothers of MD/DPD children (p=0.01). These autoantibodies were not increased in mothers of children with autistic spectrum disorder. Conclusions These findings complement the known roles of CASPR2 in brain development, and warrant further epidemiological and experimental studies to clarify the role of CASPR2 and possibly other antibodies in neurodevelopmental disorders. PMID:28572274

Nucleic acid-coupled colorimetric analyte detectors

DOEpatents

Charych, Deborah H.; Jonas, Ulrich

2001-01-01

The present invention relates to methods and compositions for the direct detection of analytes and membrane conformational changes through the detection of color changes in biopolymeric materials. In particular, the present invention provide for the direct colorimetric detection of analytes using nucleic acid ligands at surfaces of polydiacetylene liposomes and related molecular layer systems.

A rapid colorimetric assay for mold spore germination using XTT tetrazolium salt

Treesearch

Carol A. Clausen; Vina W. Yang

2011-01-01

Current laboratory test methods to measure efficacy of new mold inhibitors are time consuming, some require specialized test equipment and ratings are subjective. Rapid, simple quantitative assays to measure the efficacy of mold inhibitors are needed. A quantitative, colorimetric microassay was developed using XTT tetrazolium salt to metabolically assess mold spore...

A mesoscopic bridging scale method for fluids and coupling dissipative particle dynamics with continuum finite element method

PubMed Central

Kojic, Milos; Filipovic, Nenad; Tsuda, Akira

2012-01-01

A multiscale procedure to couple a mesoscale discrete particle model and a macroscale continuum model of incompressible fluid flow is proposed in this study. We call this procedure the mesoscopic bridging scale (MBS) method since it is developed on the basis of the bridging scale method for coupling molecular dynamics and finite element models [G.J. Wagner, W.K. Liu, Coupling of atomistic and continuum simulations using a bridging scale decomposition, J. Comput. Phys. 190 (2003) 249–274]. We derive the governing equations of the MBS method and show that the differential equations of motion of the mesoscale discrete particle model and finite element (FE) model are only coupled through the force terms. Based on this coupling, we express the finite element equations which rely on the Navier–Stokes and continuity equations, in a way that the internal nodal FE forces are evaluated using viscous stresses from the mesoscale model. The dissipative particle dynamics (DPD) method for the discrete particle mesoscale model is employed. The entire fluid domain is divided into a local domain and a global domain. Fluid flow in the local domain is modeled with both DPD and FE method, while fluid flow in the global domain is modeled by the FE method only. The MBS method is suitable for modeling complex (colloidal) fluid flows, where continuum methods are sufficiently accurate only in the large fluid domain, while small, local regions of particular interest require detailed modeling by mesoscopic discrete particles. Solved examples – simple Poiseuille and driven cavity flows illustrate the applicability of the proposed MBS method. PMID:23814322

Prediction of in vivo drug-drug interactions based on mechanism-based inhibition from in vitro data: inhibition of 5-fluorouracil metabolism by (E)-5-(2-Bromovinyl)uracil.

PubMed

Kanamitsu, S I; Ito, K; Okuda, H; Ogura, K; Watabe, T; Muro, K; Sugiyama, Y

2000-04-01

The fatal drug-drug interaction between sorivudine, an antiviral drug, and 5-fluorouracil (5-FU) has been shown to be caused by a mechanism-based inhibition. In this interaction, sorivudine is converted by gut flora to (E)-5-(2-bromovinyl)uracil (BVU), which is metabolically activated by dihydropyrimidine dehydrogenase (DPD), and the activated BVU irreversibly binds to DPD itself, thereby inactivating it. In an attempt to predict this interaction in vivo from in vitro data, inhibition of 5-FU metabolism by BVU was investigated by using rat and human hepatic cytosol and human recombinant DPD. Whichever enzyme was used, increased inhibition was observed that depended on the preincubation time of BVU and enzyme in the presence of NADPH and BVU concentration. The kinetic parameters obtained for inactivation represented by k(inact) and K'(app) were 2.05 +/- 1.52 min(-1), 69.2 +/- 60.8 microM (rat hepatic cytosol), 2.39 +/- 0.13 min(-1), 48.6 +/- 11.8 microM (human hepatic cytosol), and 0.574 +/- 0.121 min(-1), 2.20 +/- 0.57 microM (human recombinant DPD). The drug-drug interaction in vivo was predicted quantitatively based on a physiologically based pharmacokinetic model, using pharmacokinetic parameters obtained from the literature and kinetic parameters for the enzyme inactivation obtained in the in vitro studies. In rats, DPD was predicted to be completely inactivated by administration of BVU and the area under the curve of 5-FU was predicted to increase 11-fold, which agreed well with the reported data. In humans, a 5-fold increase in the area under the curve of 5-FU was predicted after administration of sorivudine, 150 mg/day for 5 days. Mechanism-based inhibition of drug metabolism is supposed to be very dangerous. We propose that such in vitro studies should be carried out during the drug-developing phase so that in vivo drug-drug interactions can be predicted.

Azomethine H colorimetric method for determining dissolved boron in water

USGS Publications Warehouse

Spencer, R.R.; Erdmann, D.E.

1979-01-01

An automated colorimetric method for determining dissolved boron in water is described. The boron is complexed with azomethine H, which is readily available as the condensation product of H acid (8-amino-1-naphthol-3,6-disulfonic acid) and salicylaldehyde. The absorbance of the yellow complex formed is then measured colorimetrically at 410 nm. Interference effects from other dissolved species are minimized by the addition of diethylenetriaminepentaacetic acid (DTPA); however, iron, zinc, and bicarbonate interfere at concentrations above 400 ??g/L, 2000 ??g/L, and 200 mg/L, respectively. The bicarbonate interference can be eliminated by careful acidification of the sample with concentrated HCl to a pH between 5 and 6. Thirty samples per hour can be routinely analyzed over the range of from 10 to 400 ??g/L, boron.

GPU-accelerated Red Blood Cells Simulations with Transport Dissipative Particle Dynamics.

PubMed

Blumers, Ansel L; Tang, Yu-Hang; Li, Zhen; Li, Xuejin; Karniadakis, George E

2017-08-01

Mesoscopic numerical simulations provide a unique approach for the quantification of the chemical influences on red blood cell functionalities. The transport Dissipative Particles Dynamics (tDPD) method can lead to such effective multiscale simulations due to its ability to simultaneously capture mesoscopic advection, diffusion, and reaction. In this paper, we present a GPU-accelerated red blood cell simulation package based on a tDPD adaptation of our red blood cell model, which can correctly recover the cell membrane viscosity, elasticity, bending stiffness, and cross-membrane chemical transport. The package essentially processes all computational workloads in parallel by GPU, and it incorporates multi-stream scheduling and non-blocking MPI communications to improve inter-node scalability. Our code is validated for accuracy and compared against the CPU counterpart for speed. Strong scaling and weak scaling are also presented to characterizes scalability. We observe a speedup of 10.1 on one GPU over all 16 cores within a single node, and a weak scaling efficiency of 91% across 256 nodes. The program enables quick-turnaround and high-throughput numerical simulations for investigating chemical-driven red blood cell phenomena and disorders.

Novel 5-fluorouracil-resistant human esophageal squamous cell carcinoma cells with dihydropyrimidine dehydrogenase overexpression

PubMed Central

Kikuchi, Osamu; Ohashi, Shinya; Nakai, Yukie; Nakagawa, Shunsaku; Matsuoka, Kazuaki; Kobunai, Takashi; Takechi, Teiji; Amanuma, Yusuke; Yoshioka, Masahiro; Ida, Tomomi; Yamamoto, Yoshihiro; Okuno, Yasushi; Miyamoto, Shin’ichi; Nakagawa, Hiroshi; Matsubara, Kazuo; Chiba, Tsutomu; Muto, Manabu

2015-01-01

5-Fluorouracil (5-FU) is a key drug for the treatment of esophageal squamous cell carcinoma (ESCC); however, resistance to it remains a critical limitation to its clinical use. To clarify the mechanisms of 5-FU resistance of ESCC, we originally established 5-FU-resistant ESCC cells, TE-5R, by step-wise treatment with continuously increasing concentrations of 5-FU. The half maximal inhibitory concentration of 5-FU showed that TE-5R cells were 15.6-fold more resistant to 5-FU in comparison with parental TE-5 cells. TE-5R cells showed regional copy number amplification of chromosome 1p including the DPYD gene, as well as high mRNA and protein expressions of dihydropyrimidine dehydrogenase (DPD), an enzyme involved in 5-FU degradation. 5-FU treatment resulted in a significant decrease of the intracellular 5-FU concentration and increase of the concentration of α-fluoro-ureidopropionic acid (FUPA), a metabolite of 5-FU, in TE-5R compared with TE-5 cells in vitro. Conversely, gimeracil, a DPD inhibitor, markedly increased the intracellular 5-FU concentration, decreased the intracellular FUPA concentration, and attenuated 5-FU resistance of TE-5R cells. These results indicate that 5-FU resistance of TE-5R cells is due to the rapid degradation of 5-FU by DPD overexpression. The investigation of 5-FU-resistant ESCC with DPYD gene copy number amplification and consequent DPD overexpression may generate novel biological evidence to explore strategies against ESCC with 5-FU resistance. PMID:26396918

Aptamer-mediated colorimetric method for rapid and sensitive detection of chloramphenicol in food.

PubMed

Yan, Chao; Zhang, Jing; Yao, Li; Xue, Feng; Lu, Jianfeng; Li, Baoguang; Chen, Wei

2018-09-15

We report an aptamer-mediated colorimetric method for sensitive detection of chloramphenicol (CAP). The aptamer of CAP is immobilized by the hybridization with pre-immobilized capture probe in the microtiter plate. The horseradish peroxidase (HRP) is covalently attached to the aptamer by the biotin-streptavidin system for signal production. CAP will preferably bind with aptamer due to the high binding affinity, which attributes to the release of aptamer and HRP and thus, affects the optical signal intensity. Quantitative determination of CAP is successfully achieved in the wide range from 0.001 to 1000 ng/mL with detection limit of 0.0031 ng/mL, which is more sensitive than traditional immunoassays. This method is further validated by measuring the recovery of CAP spiked in two different food matrices (honey and fish). The aptamer-mediated colorimetric method can be a useful protocol for rapid and sensitive screening of CAP, and may be used as an alternative means for traditional immunoassays. Copyright © 2018 Elsevier Ltd. All rights reserved.

Improving reflectance reconstruction from tristimulus values by adaptively combining colorimetric and reflectance similarities

NASA Astrophysics Data System (ADS)

Cao, Bin; Liao, Ningfang; Li, Yasheng; Cheng, Haobo

2017-05-01

The use of spectral reflectance as fundamental color information finds application in diverse fields related to imaging. Many approaches use training sets to train the algorithm used for color classification. In this context, we note that the modification of training sets obviously impacts the accuracy of reflectance reconstruction based on classical reflectance reconstruction methods. Different modifying criteria are not always consistent with each other, since they have different emphases; spectral reflectance similarity focuses on the deviation of reconstructed reflectance, whereas colorimetric similarity emphasizes human perception. We present a method to improve the accuracy of the reconstructed spectral reflectance by adaptively combining colorimetric and spectral reflectance similarities. The different exponential factors of the weighting coefficients were investigated. The spectral reflectance reconstructed by the proposed method exhibits considerable improvements in terms of the root-mean-square error and goodness-of-fit coefficient of the spectral reflectance errors as well as color differences under different illuminants. Our method is applicable to diverse areas such as textiles, printing, art, and other industries.

False positive acetaminophen concentrations in patients with liver injury.

PubMed

Polson, Julie; Wians, Frank H; Orsulak, Paul; Fuller, Dwain; Murray, Natalie G; Koff, Jonathan M; Khan, Adil I; Balko, Jody A; Hynan, Linda S; Lee, William M

2008-05-01

Acetaminophen toxicity is the most common form of acute liver failure in the U.S. After acetaminophen overdoses, quantitation of plasma acetaminophen can aid in predicting severity of injury. However, recent case reports have suggested that acetaminophen concentrations may be falsely increased in the presence of hyperbilirubinemia. We tested sera obtained from 43 patients with acute liver failure, mostly unrelated to acetaminophen, utilizing 6 different acetaminophen quantitation systems to determine the significance of this effect. In 36 of the 43 samples with bilirubin concentrations ranging from 1.0-61.5 mg/dl no acetaminophen was detectable by gas chromatography-mass spectroscopy. These 36 samples were then utilized to test the performance characteristics of 2 immunoassay and 4 enzymatic-colorimetric methods. Three of four colorimetric methods demonstrated 'detectable' values for acetaminophen in from 4 to 27 of the 36 negative samples, low concentration positive values being observed when serum bilirubin concentrations exceeded 10 mg/dl. By contrast, the 2 immunoassay methods (EMIT, FPIA) were virtually unaffected. The false positive values obtained were, in general, proportional to the quantity of bilirubin in the sample. However, prepared samples of normal human serum with added bilirubin showed a dose-response curve for only one of the 4 colorimetric assays. False positive acetaminophen tests may result when enzymatic-colorimetric assays are used, most commonly with bilirubin concentrations >10 mg/dl, leading to potential clinical errors in this setting. Bilirubin (or possibly other substances in acute liver failure sera) appears to affect the reliable measurement of acetaminophen, particularly with enzymatic-colorimetric assays.

Single droplet drying step characterization in microsphere preparation.

PubMed

Al Zaitone, Belal; Lamprecht, Alf

2013-05-01

Spray drying processes are difficult to characterize since process parameters are not directly accessible. Acoustic levitation was used to investigate microencapsulation by spray drying on one single droplet facilitating the analyses of droplet behavior upon drying. Process parameters were simulated on a poly(lactide-co-glycolide)/ethyl acetate combination for microencapsulation. The results allowed quantifying the influence of process parameters such as temperature (0-40°C), polymer concentration (5-400 mg/ml), and droplet size (0.5-1.37 μl) on the drying time and drying kinetics as well as the particle morphology. The drying of polymer solutions at temperature of 21°C and concentration of 5 mg/ml, shows that the dimensionless particle diameter (Dp/D0) approaches 0.25 and the particle needs 350 s to dry. At 400 mg/ml, Dp/D0=0.8 and the drying time increases to one order of magnitude and a hollow particle is formed. The study demonstrates the benefit of using the acoustic levitator as a lab scale method to characterize and study the microparticle formation. This method can be considered as a helpful tool to mimic the full scale spray drying process by providing identical operational parameters such as air velocity, temperature, and variable droplet sizes. Copyright © 2013 Elsevier B.V. All rights reserved.

Non-equilibrium dynamics due to moving deflagration front at RDX/HTPB interface

NASA Astrophysics Data System (ADS)

Chaudhuri, Santanu; Joshi, Kaushik; Lacevic, Naida

Reactive dissipative particle dynamics (DPD-RX), a promising tool in characterizing the sensitivity and performance of heterogeneous solid propellants like polymer bonded explosives (PSXs), requires further testing for non-equilibrium dynamics. It is important to understand detailed atomistic chemistry for developing coarse grain reactive models needed for the DPD-RX. In order to obtain insights into combustion chemistry of RDX/HTPB binder, we used reactive molecular dynamics (RMD) to obtain energy up-pumping and reaction mechanisms at RDX/HTPB interface when exposed to a self-sustaining deflagration front. Hot spots are ignited near and away from the heterogeneous interface using the thermal pulse. The results show that the hot spot near interface significantly delays the transition from ignition to deflagration. We will present the mechanical response and the combustion chemistry of HTPB when the propagating deflagration front hits the polymer binder. We will discuss our efforts to incorporate this RMD based chemistry into the DPD-RX which will enable us to perform such non-equilibrium dynamics simulations on large-length scale with microstructural heterogeneities. Funding from DTRA Grant Number HDTRA1-15-1-0034 is acknowledged.

Analysis of structure and dynamics of superfine polyhydroxybutyrate fibers for targeted drug delivery

NASA Astrophysics Data System (ADS)

Olkhov, A.; Kucherenko, E.; Pantyukhov, P.; Zykova, A.; Karpova, S.; Iordanskii, A.

2017-02-01

Creation of polymer matrix systems for targeted drug delivery into a living organism is a challenging problem of modern treatment of various diseases and injuries. Poly-3-hydroxybutyrate (PHB) is commonly used for development of therapeutic systems. The aim of this article is to examine the changes in structure and morphology of fibers in presence of dipyridamole (DPD) as model drug for controlled release. It was found that addition of dipyridamole led to disappearance of spindle-shaped nodules on fibers of PHB in comparison with pure PHB. The research of thermophysical parameters showed that specific melting enthalpy (and the degree of crystallinity) of PHB fibers increased with the addition of DPD. With the increasing of DPD content in PHB fibers, more perfect and equilibrium crystal structure was formed. According to analysis of intercrystalline regions of PHB fibers, it was found that as the crystallinity of PHB in intergranular regions rose, the corresponding decrease of radical rotation speed was observed. It was concluded that fibers of PHB can be used for creating therapeutic systems for targeted and prolonged drug delivery.

Discordance Between Physician Assessment and Patient-Reported Depressive Symptoms in Parkinson Disease.

PubMed

Lachner, Christian; Armstrong, Melissa J; Gruber-Baldini, Ann L; Rezvani, Zahra; Reich, Stephen G; Fishman, Paul S; Salazar, Richard; Shulman, Lisa M

2017-07-01

To assess concordance between physician assessment and patient-reported symptoms when screening for depression in Parkinson disease (dPD). Depression in Parkinson disease is highly prevalent (∼40%) and has a significant impact on quality of life and disability, yet physician recognition and treatment remain inadequate. One thousand seventy-six patients with PD completed the Brief Symptom Inventory-18 (BSI-18), a screening questionnaire for psychiatric symptoms, which was compared to item #3 (depression) on the Unified Parkinson's Disease Rating Scale (UPDRS). The mean BSI-18 depression score was 51.4 (9.7). Of the 170 (16%) patients screening positive for dPD on the BSI-18, 104 (61%) were not recognized as depressed by neurologists on the UPDRS. Factors associated with lower neurologist recognition included male gender, better mental health quality of life, and lack of antidepressant use. More than 60% of patients screening positive for depression on self-report were not recognized by neurologists on the UPDRS. A patient-reported screening tool for depression may improve recognition and management of dPD.

One-tube loop-mediated isothermal amplification combined with restriction endonuclease digestion and ELISA for colorimetric detection of resistance to isoniazid, ethambutol and streptomycin in Mycobacterium tuberculosis isolates.

PubMed

Lee, Mei-Feng; Chen, Yen-Hsu; Hsu, Hui-Jine; Peng, Chien-Fang

2010-10-01

In this study, we designed a simple and rapid colorimetric detection method, a one-tube loop-mediated isothermal amplification (LAMP)-PCR-hybridization-restriction endonuclease-ELISA [one-tube LAMP-PCR-HY-RE-ELISA] system, to detect resistance to isoniazid, ethambutol and streptomycin in strains of Mycobacterium tuberculosis isolated from clinical specimens. The clinical performance of this method for detecting isoniazid-resistant, ethambutol-resistant and streptomycin-resistant isolates of M. tuberculosis showed 98.9%, 94.3% and 93.8%, respectively. This assay is rapid and convenient that can be performed within one working day. One-tube LAMP-PCR-HY-RE-ELISA system was designed based on hot spot point mutations in target drug-resistant genes, using LAMP-PCR, hybridization, digestion with restriction endonuclease and colorimetric method of ELISA. In this study, LAMP assay was used to amplify DNA from drug-resistant M. tuberculosis, and ELISA was used for colorimetrical determination. This assay will be a useful tool for rapid diagnosis of mutant codons in strains of M. tuberculosis for isoniazid at katG 315 and katG 463, ethambutol at embB 306 and embB 497, and streptomycin at rpsL 43. Crown Copyright © 2010. Published by Elsevier B.V. All rights reserved.

A highly sensitive and selective aptamer-based colorimetric sensor for the rapid detection of PCB 77.

PubMed

Cheng, Ruojie; Liu, Siyao; Shi, Huijie; Zhao, Guohua

2018-01-05

A highly sensitive, specific and simple colorimetric sensor based on aptamer was established for the detection of polychlorinated biphenyls (PCB 77). The use of unmodified gold nanoparticles as a colorimetric probe for aptamer sensors enabled the highly sensitive and selective detection of polychlorinated biphenyls (PCB 77). A linear range of 0.5nM to 900nM was obtained for the colorimetric assay with a minimum detection limit of 0.05nM. In addition, by the methods of circular dichroism, UV and naked eyes, we found that the 35 base fragments retained after cutting 5 bases from the 5 'end of aptamer plays the most significant role in the PCB 77 specific recognition process. We found a novel way to truncated nucleotides to optimize the detection of PCB 77, and the selected nucleotides also could achieve high affinity with PCB 77. At the same time, the efficient detection of the PCB 77 by our colorimetric sensor in the complex environmental water samples was realized, which shows a good application prospect. Copyright © 2017 Elsevier B.V. All rights reserved.

Colorimetric detection of UV light-induced single-strand DNA breaks using gold nanoparticles.

PubMed

Kim, Joong Hyun; Chung, Chan Ho; Chung, Bong Hyun

2013-02-21

We developed a colorimetric method to specifically detect single-strand DNA breaks using gold nanoparticles. In our assay, broken DNA cannot stabilize gold nanoparticles to prevent salt-induced aggregation as good as intact DNA can, and this effect can be easily observed with the naked eye as a red-to-purple color change.

Method for estimating effects of unknown correlations in spectral irradiance data on uncertainties of spectrally integrated colorimetric quantities

NASA Astrophysics Data System (ADS)

Kärhä, Petri; Vaskuri, Anna; Mäntynen, Henrik; Mikkonen, Nikke; Ikonen, Erkki

2017-08-01

Spectral irradiance data are often used to calculate colorimetric properties, such as color coordinates and color temperatures of light sources by integration. The spectral data may contain unknown correlations that should be accounted for in the uncertainty estimation. We propose a new method for estimating uncertainties in such cases. The method goes through all possible scenarios of deviations using Monte Carlo analysis. Varying spectral error functions are produced by combining spectral base functions, and the distorted spectra are used to calculate the colorimetric quantities. Standard deviations of the colorimetric quantities at different scenarios give uncertainties assuming no correlations, uncertainties assuming full correlation, and uncertainties for an unfavorable case of unknown correlations, which turn out to be a significant source of uncertainty. With 1% standard uncertainty in spectral irradiance, the expanded uncertainty of the correlated color temperature of a source corresponding to the CIE Standard Illuminant A may reach as high as 37.2 K in unfavorable conditions, when calculations assuming full correlation give zero uncertainty, and calculations assuming no correlations yield the expanded uncertainties of 5.6 K and 12.1 K, with wavelength steps of 1 nm and 5 nm used in spectral integrations, respectively. We also show that there is an absolute limit of 60.2 K in the error of the correlated color temperature for Standard Illuminant A when assuming 1% standard uncertainty in the spectral irradiance. A comparison of our uncorrelated uncertainties with those obtained using analytical methods by other research groups shows good agreement. We re-estimated the uncertainties for the colorimetric properties of our 1 kW photometric standard lamps using the new method. The revised uncertainty of color temperature is a factor of 2.5 higher than the uncertainty assuming no correlations.

Highly selective colorimetric bacteria sensing based on protein-capped nanoparticles.

PubMed

Qiu, Suyan; Lin, Zhenyu; Zhou, Yaomin; Wang, Donggen; Yuan, Lijuan; Wei, Yihua; Dai, Tingcan; Luo, Linguang; Chen, Guonan

2015-02-21

A rapid and cost-effective colorimetric sensor has been developed for the detection of bacteria (Bacillus subtilis was selected as an example). The sensor was designed to rely on lysozyme-capped AuNPs with the advantages of effective amplification and high specificity. In the sensing system, lysozyme was able to bind strongly to Bacillus subtilis, which effectively induced a color change of the solution from light purple to purplish red. The lowest concentration of Bacillus subtilis detectable by the naked eye was 4.5 × 10(3) colony-forming units (CFU) mL(-1). Similar results were discernable from UV-Vis absorption measurements. A good specificity was observed through a statistical analysis method using the SPSS software (version 17.0). This simple colorimetric sensor may therefore be a rapid and specific method for a bacterial detection assay in complex samples.

Systematic parameter inference in stochastic mesoscopic modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lei, Huan; Yang, Xiu; Li, Zhen

2017-02-01

We propose a method to efficiently determine the optimal coarse-grained force field in mesoscopic stochastic simulations of Newtonian fluid and polymer melt systems modeled by dissipative particle dynamics (DPD) and energy conserving dissipative particle dynamics (eDPD). The response surfaces of various target properties (viscosity, diffusivity, pressure, etc.) with respect to model parameters are constructed based on the generalized polynomial chaos (gPC) expansion using simulation results on sampling points (e.g., individual parameter sets). To alleviate the computational cost to evaluate the target properties, we employ the compressive sensing method to compute the coefficients of the dominant gPC terms given the priormore » knowledge that the coefficients are “sparse”. The proposed method shows comparable accuracy with the standard probabilistic collocation method (PCM) while it imposes a much weaker restriction on the number of the simulation samples especially for systems with high dimensional parametric space. Fully access to the response surfaces within the confidence range enables us to infer the optimal force parameters given the desirable values of target properties at the macroscopic scale. Moreover, it enables us to investigate the intrinsic relationship between the model parameters, identify possible degeneracies in the parameter space, and optimize the model by eliminating model redundancies. The proposed method provides an efficient alternative approach for constructing mesoscopic models by inferring model parameters to recover target properties of the physics systems (e.g., from experimental measurements), where those force field parameters and formulation cannot be derived from the microscopic level in a straight forward way.« less

A New Colorimetric Assay of Tabletop Sweeteners Using a Modified Biuret Reagent: An Analytical Chemistry Experiment for the Undergraduate Curriculum

ERIC Educational Resources Information Center

Fenk, Christopher J.; Kaufman, Nathan; Gerbig, Donald G., Jr.

2007-01-01

A new, fast and effective colorimetric analysis of the artificial sweetener aspartame is presented for application in undergraduate laboratory courses. This new method incorporates the use of a modified biuret reagent for selective detection and analysis of aspartame in aqueous solutions. The modified reagent is less caustic than the traditional…

Application of Colorimetric Solid Phase Extraction (C-SPE) to Monitoring Nickel(II) and Lead(II) in Spacecraft Water Supplies

NASA Technical Reports Server (NTRS)

Diaz, Neil C.; Gazda, Daniel B.; Fritz, James S.; Porter, Marc D.; Rutz, Jeff; Mudgett, Paul; Schultz, John

2004-01-01

Archived water samples collected on the International Space Station (ISS) and returned to Earth for analysis have, in a few instances, contained trace levels of heavy metals. Building on our previous advances using Colorimetric Solid Phase Extraction (C-SPE) as a biocide monitoring technique, we are devising methods for the low level monitoring of nickel(II), lead(II) and other heavy metals. C-SPE is a sorption-spectrophotometric platform based on the extraction of analytes onto a membrane impregnated with a colorimetric reagent that are then quantified on the surface of the membrane using a diffuse reflectance spectrophotometer. Along these lines, we have determined nickel(II) via complexation with dimethylglyoxime (DMG) and begun to examine the analysis of lead(II) by its reaction with 2,5- dimercapto-1,3,4-thiadiazole (DMTD) and 4-(2- pyridylazo)-resorcinol (PAR). These developments are also extending a new variant of C-SPE in which immobilized reagents are being incorporated into this methodology in order to optimize sample reaction conditions and to introduce the colorimetric reagent. This paper describes the status of our development of these two new methods.

Colorimetric and fluorimetric detection of Hg2 + and Cr3 + by boronic acid conjugated rhodamine derivatives: Mechanistic aspects and their bio-imaging application in bacterial cells

NASA Astrophysics Data System (ADS)

Vallu, Rama Krishna; Velugula, Krishna; Doshi, Sejal; Chinta, Jugun Prakash

2018-01-01

Colorimetric and fluorimetric detection of toxic metal ions such as Hg2 + and Cr3 + has gained tremendous popularity over the conventional methods due to their operational simplicity, high selectivity, and speediness. Although numerous colorimetric and fluorescent receptors for Hg2 + or Cr3 + were reported in the literature, boronic acid-based receptors for these metal ions are rather scarce in the literature. Hence, in the present study dual function boronic acid conjugated rhodamine derivatives were developed, and their toxic metal ion detection abilities were studied by absorption, emission and visual detection methods. Absorption and emission spectral studies revealed that these derivatives displayed selectivity towards Hg2 +, Cr3 + and Fe3 + among the other metal ions studied by forming new absorption band. Both the derivatives exhibited colorimetric response towards Hg2 + and Cr3 + by the change in color of the solution to pink and reddish pink with Fe3 +. The detailed mechanism involved in the detection of Hg2 + was deduced by 1H NMR and ESI-MS studies. Further, these derivatives were used for fluorescence imaging of Hg2 + and Cr3 + in S. aureus bacterial cells. Thus the present manuscript demonstrated the use of boronic acid conjugated rhodamine derivatives as a dual function (colorimetric and fluorescent) probes and as imaging agents for Hg2 + and Cr3 +, which are known for their toxic influence on bacterial cells.

A Rapid Colorimetric Method Reveals Fraudulent Substitutions in Sea Urchin Roe Marketed in Sardinia (Italy).

PubMed

Meloni, Domenico; Spina, Antonio; Satta, Gianluca; Chessa, Vittorio

2016-06-25

In recent years, besides the consumption of fresh sea urchin specimens, the demand of minimally-processed roe has grown considerably. This product has made frequent consumption in restaurants possible and frauds are becoming widespread with the partial replacement of sea urchin roe with surrogates that are similar in colour. One of the main factors that determines the quality of the roe is its colour and small differences in colour scale cannot be easily discerned by the consumers. In this study we have applied a rapid colorimetric method for reveal the fraudulent partial substitution of semi-solid sea urchin roe with liquid egg yolk. Objective assessment of whiteness (L*), redness (a*), yellowness (b*), hue (h*), and chroma (C*) was carried out with a digital spectrophotometer using the CIE L*a*b* colour measurement system. The colorimetric method highlighted statistically significant differences among sea urchin roe and liquid egg yolk that could be easily discerned quantitatively.

Detection of proteins using a colorimetric bio-barcode assay.

PubMed

Nam, Jwa-Min; Jang, Kyung-Jin; Groves, Jay T

2007-01-01

The colorimetric bio-barcode assay is a red-to-blue color change-based protein detection method with ultrahigh sensitivity. This assay is based on both the bio-barcode amplification method that allows for detecting miniscule amount of targets with attomolar sensitivity and gold nanoparticle-based colorimetric DNA detection method that allows for a simple and straightforward detection of biomolecules of interest (here we detect interleukin-2, an important biomarker (cytokine) for many immunodeficiency-related diseases and cancers). The protocol is composed of the following steps: (i) conjugation of target capture molecules and barcode DNA strands onto silica microparticles, (ii) target capture with probes, (iii) separation and release of barcode DNA strands from the separated probes, (iv) detection of released barcode DNA using DNA-modified gold nanoparticle probes and (v) red-to-blue color change analysis with a graphic software. Actual target detection and quantification steps with premade probes take approximately 3 h (whole protocol including probe preparations takes approximately 3 days).

Visual and highly sensitive detection of cancer cells by a colorimetric aptasensor based on cell-triggered cyclic enzymatic signal amplification.

PubMed

Zhang, Xianxia; Xiao, Kunyi; Cheng, Liwei; Chen, Hui; Liu, Baohong; Zhang, Song; Kong, Jilie

2014-06-03

Rapid and efficient detection of cancer cells at their earliest stages is one of the central challenges in cancer diagnostics. We developed a simple, cost-effective, and highly sensitive colorimetric method for visually detecting rare cancer cells based on cell-triggered cyclic enzymatic signal amplification (CTCESA). In the absence of target cells, hairpin aptamer probes (HAPs) and linker DNAs stably coexist in solution, and the linker DNA assembles DNA-AuNPs, producing a purple solution. In the presence of target cells, the specific binding of HAPs to the target cells triggers a conformational switch that results in linker DNA hybridization and cleavage by nicking endonuclease-strand scission cycles. Consequently, the cleaved fragments of linker DNA can no longer assemble into DNA-AuNPs, resulting in a red color. UV-vis spectrometry and photograph analyses demonstrated that this CTCESA-based method exhibited selective and sensitive colorimetric responses to the presence of target CCRF-CEM cells, which could be detected by the naked eye. The linear response for CCRF-CEM cells in a concentration range from 10(2) to 10(4) cells was obtained with a detection limit of 40 cells, which is approximately 20 times lower than the detection limit of normal AuNP-based methods without amplification. Given the high specificity and sensitivity of CTCESA, this colorimetric method provides a sensitive, label-free, and cost-effective approach for early cancer diagnosis and point-to-care applications.

Distinction of Gram-positive and -negative bacteria using a colorimetric microbial viability assay based on the reduction of water-soluble tetrazolium salts with a selection medium.

PubMed

Tsukatani, Tadayuki; Suenaga, Hikaru; Higuchi, Tomoko; Shiga, Masanobu; Noguchi, Katsuya; Matsumoto, Kiyoshi

2011-01-01

Bacteria are fundamentally divided into two groups: Gram-positive and Gram-negative. Although the Gram stain and other techniques can be used to differentiate these groups, some issues exist with traditional approaches. In this study, we developed a method for differentiating Gram-positive and -negative bacteria using a colorimetric microbial viability assay based on the reduction of the tetrazolium salt {2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt} (WST-8) via 2-methyl-1,4-napthoquinone with a selection medium. We optimized the composition of the selection medium to allow the growth of Gram-negative bacteria while inhibiting the growth of Gram-positive bacteria. When the colorimetric viability assay was carried out in a selection medium containing 0.5µg/ml crystal violet, 5.0 µg/ml daptomycin, and 5.0µg/ml vancomycin, the reduction in WST-8 by Gram-positive bacteria was inhibited. On the other hand, Gram-negative bacteria produced WST-8-formazan in the selection medium. The proposed method was also applied to determine the Gram staining characteristics of bacteria isolated from various foodstuffs. There was good agreement between the results obtained using the present method and those obtained using a conventional staining method. These results suggest that the WST-8 colorimetric assay with selection medium is a useful technique for accurately differentiating Gram-positive and -negative bacteria.

Surface plasmon resonance based selective and sensitive colorimetric determination of azithromycin using unmodified silver nanoparticles in pharmaceuticals and human plasma

NASA Astrophysics Data System (ADS)

Chavada, Vijay D.; Bhatt, Nejal M.; Sanyal, Mallika; Shrivastav, Pranav S.

2017-01-01

In this article we report a novel method for colorimetric sensing and selective determination of a non-chromophoric drug-azithromycin, which lacks native absorbance in the UV-Visible region using unmodified silver nanoparticles (AgNPs). The citrate-capped AgNps dispersed in water afforded a bright yellow colour owing to the electrostatic repulsion between the particles due to the presence of negatively charged surface and showed surface plasmon resonance (SPR) band at 394 nm. Addition of positively charged azithromycin at a concentration as low as 0.2 μM induced rapid aggregation of AgNPs by neutralizing the negative charge on the particle surface. This phenomenon resulted in the colour change from bright yellow to purple which could be easily observed by the naked eye. This provided a simple platform for rapid determination of azithromycin based on colorimetric measurements. The factors affecting the colorimetric response like pH, volume of AgNPs suspension and incubation time were suitably optimized. The validated method was found to work efficiently in the established concentration range of 0.2-100.0 μM using two different calibration models. The selectivity of the method was also evaluated by analysis of nanoparticles-aggregation response upon addition of several anions, cations and some commonly prescribed antibiotics. The method was successfully applied for the analysis of azithromycin in pharmaceuticals and spiked human plasma samples with good accuracy and precision. The simplicity, efficiency and cost-effectiveness of the method hold tremendous potential for the analysis of such non-chromophoric pharmaceuticals.

A high-throughput colorimetric assay for glucose detection based on glucose oxidase-catalyzed enlargement of gold nanoparticles

NASA Astrophysics Data System (ADS)

Xiong, Yanmei; Zhang, Yuyan; Rong, Pengfei; Yang, Jie; Wang, Wei; Liu, Dingbin

2015-09-01

We developed a simple high-throughput colorimetric assay to detect glucose based on the glucose oxidase (GOx)-catalysed enlargement of gold nanoparticles (AuNPs). Compared with the currently available glucose kit method, the AuNP-based assay provides higher clinical sensitivity at lower cost, indicating its great potential to be a powerful tool for clinical screening of glucose.We developed a simple high-throughput colorimetric assay to detect glucose based on the glucose oxidase (GOx)-catalysed enlargement of gold nanoparticles (AuNPs). Compared with the currently available glucose kit method, the AuNP-based assay provides higher clinical sensitivity at lower cost, indicating its great potential to be a powerful tool for clinical screening of glucose. Electronic supplementary information (ESI) available: Experimental section and additional figures. See DOI: 10.1039/c5nr03758a

Simple colorimetric detection of doxycycline and oxytetracycline using unmodified gold nanoparticles

NASA Astrophysics Data System (ADS)

Li, Jie; Fan, Shumin; Li, Zhigang; Xie, Yuanzhe; Wang, Rui; Ge, Baoyu; Wu, Jing; Wang, Ruiyong

2014-08-01

The interaction between tetracycline antibiotics and gold nanoparticles was studied. With citrate-coated gold nanoparticles as colorimetric probe, a simple and rapid detection method for doxycycline and oxytetracycline has been developed. This method relies on the distance-dependent optical properties of gold nanoparticles. In weakly acidic buffer medium, doxycycline and oxytetracycline could rapidly induce the aggregation of gold nanoparticles, resulting in red-to-blue (or purple) colour change. The experimental parameters were optimized with regard to pH, the concentration of the gold nanoparticles and the reaction time. Under optimal experimental conditions, the linear range of the colorimetric sensor for doxycycline/oxytetracycline was 0.06-0.66 and 0.59-8.85 μg mL-1, respectively. The corresponding limit of detection for doxycycline and oxytetracycline was 0.0086 and 0.0838 μg mL-1, respectively. This assay was sensitive, selective, simple and readily used to detect tetracycline antibiotics in food products.

An imaging-based photometric and colorimetric measurement method for characterizing OLED panels for lighting applications

NASA Astrophysics Data System (ADS)

Zhu, Yiting; Narendran, Nadarajah; Tan, Jianchuan; Mou, Xi

2014-09-01

The organic light-emitting diode (OLED) has demonstrated its novelty in displays and certain lighting applications. Similar to white light-emitting diode (LED) technology, it also holds the promise of saving energy. Even though the luminous efficacy values of OLED products have been steadily growing, their longevity is still not well understood. Furthermore, currently there is no industry standard for photometric and colorimetric testing, short and long term, of OLEDs. Each OLED manufacturer tests its OLED panels under different electrical and thermal conditions using different measurement methods. In this study, an imaging-based photometric and colorimetric measurement method for OLED panels was investigated. Unlike an LED that can be considered as a point source, the OLED is a large form area source. Therefore, for an area source to satisfy lighting application needs, it is important that it maintains uniform light level and color properties across the emitting surface of the panel over a long period. This study intended to develop a measurement procedure that can be used to test long-term photometric and colorimetric properties of OLED panels. The objective was to better understand how test parameters such as drive current or luminance and temperature affect the degradation rate. In addition, this study investigated whether data interpolation could allow for determination of degradation and lifetime, L70, at application conditions based on the degradation rates measured at different operating conditions.

Click chemistry-mediated cyclic cleavage of metal ion-dependent DNAzymes for amplified and colorimetric detection of human serum copper (II).

PubMed

Li, Daxiu; Xie, Jiaqing; Zhou, Wenjiao; Jiang, Bingying; Yuan, Ruo; Xiang, Yun

2017-11-01

The determination of the level of Cu 2+ plays important roles in disease diagnosis and environmental monitoring. By coupling Cu + -catalyzed click chemistry and metal ion-dependent DNAzyme cyclic amplification, we have developed a convenient and sensitive colorimetric sensing method for the detection of Cu 2+ in human serums. The target Cu 2+ can be reduced by ascorbate to form Cu + , which catalyzes the azide-alkyne cycloaddition between the azide- and alkyne-modified DNAs to form Mg 2+ -dependent DNAzymes. Subsequently, the Mg 2+ ions catalyze the cleavage of the hairpin DNA substrate sequences of the DNAzymes and trigger cyclic generation of a large number of free G-quadruplex sequences, which bind hemin to form the G-quadruplex/hemin artificial peroxidase to cause significant color transition of the sensing solution for sensitive colorimetric detection of Cu 2+ . This method shows a dynamic range of 5 to 500 nM and a detection limit of 2 nM for Cu 2+ detection. Besides, the level of Cu 2+ in human serums can also be determined by using this sensing approach. With the advantages of simplicity and high sensitivity, such sensing method thus holds great potential for on-site determination of Cu 2+ in different samples. Graphical abstract Sensitive colorimetric detection of copper (II) by coupling click chemistry with metal ion-dependentDNAzymes.

Dissipative particle dynamics parameterization and simulations to predict negative volume excess and structure of PEG and water mixtures

NASA Astrophysics Data System (ADS)

Kacar, Gokhan

2017-12-01

We report the results of dissipative particle dynamics (DPD) parameterization and simulations of a mixture of hydrophilic polymer, PEG 400, and water which are known to exhibit negative volume excess property upon mixing. The addition of a Morse potential to the conventional DPD potential mimics the hydrogen bond attraction, where the parameterization takes the internal chemistry of the beads into account. The results indicate that the mixing of PEG and water are maintained by the influence of hydrogen bonds, and the mesoscopic structure is characterized by the trade-off of enthalpic and entropic effects.

Application of mesoscale simulation to explore the aggregate morphology of pH-sensitive nanoparticles used as the oral drug delivery carriers under different conditions.

PubMed

Wang, Yan; Chen, Bo Zhi; Liu, Yue Jin; Wu, Zhi Min; Guo, Xin Dong

2017-03-01

The pH-sensitive nanoparticles are selected as the potentially promising oral protein and peptide drug carriers due to their excellent performance. With the poly (lactic-co-glycolic acid)/hydroxypropyl methylcellulose phthalate (PLGA/HP55) nanoparticle as a model nanoparticle, the structure-property relationship of nanoparticles with different conditions is investigated by dissipative particle dynamics (DPD) simulations in our work. In the oral drug delivery system, the poly (lactic-co-glycolic acid) (PLGA) is hydrophobic polymer, hydroxypropyl methylcellulose phthalate (HP55) is pH-sensitive enteric polymer which used to protect the nanoparticles through the stomach and polyvinyl alcohol (PVA) is hydrophilic polymer as the stabilizer. It can be seen from DPD simulations that all polymer molecules form spherical core-shell nanoparticles with stabilizer PVA molecules adsorbed on the outer surface of the PLGA/HP55 matrix at certain compositions. The DPD simulation study can provide microscopic insight into the formation and morphological changes of pH-sensitive nanoparticles which is useful for the design of new materials for high-efficacy oral drug delivery. Copyright © 2016 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

McAfee, J.G.; Krauss, D.J.; Subramanian, G.

The 3-hour biodistribution of /sup 99m/Tc complexes of five diphosphonates (HMDP, NMMDP, DMAD, DPD, and APD), imidodiphosphonate (IDP), and pyrophosphate (PYP) was compared in rats with segmental renal infarction induced by a 1-hour occlusion of a renal artery branch. /sup 95m/Tc labeled MDP was a reference substance in all animals. Three agents (APD, HMDP and IDP) had a higher infarct/normal kidney concentration ratio than MDP, the latter two by virtue of a lower content in normal kidney. HMDP, DPD, and IDP had very high liver concentrations. DPD showed relatively high concentrations in soft tissues and blood. The blood and kidneymore » levels of PYP were higher than those of MDP but the infarct/normal kidney ratios were similar. None of the agents had a higher uptake in bone than MDP: four had a significantly lower uptake. The increased concentration of /sup 99m/Tc MDP in the infarcts was readily seen in camera images one day after renal artery occlusion, but not at three or seven days. Increased diphosphonate uptake was accompanied by an influx of calcium in both cortex and medulla. The accumulation of diphosphonate in areas of infarction was not modified by infusions of verapamil or Captopril.« less

Convert a low-cost sensor to a colorimeter using an improved regression method

NASA Astrophysics Data System (ADS)

Wu, Yifeng

2008-01-01

Closed loop color calibration is a process to maintain consistent color reproduction for color printers. To perform closed loop color calibration, a pre-designed color target should be printed, and automatically measured by a color measuring instrument. A low cost sensor has been embedded to the printer to perform the color measurement. A series of sensor calibration and color conversion methods have been developed. The purpose is to get accurate colorimetric measurement from the data measured by the low cost sensor. In order to get high accuracy colorimetric measurement, we need carefully calibrate the sensor, and minimize all possible errors during the color conversion. After comparing several classical color conversion methods, a regression based color conversion method has been selected. The regression is a powerful method to estimate the color conversion functions. But the main difficulty to use this method is to find an appropriate function to describe the relationship between the input and the output data. In this paper, we propose to use 1D pre-linearization tables to improve the linearity between the input sensor measuring data and the output colorimetric data. Using this method, we can increase the accuracy of the regression method, so as to improve the accuracy of the color conversion.

A MODIFIED LOW COST COLOURIMETRIC METHOD FOR PARACETAMOL (ACETAMINOPHEN) MEASUREMENT IN PLASMA

PubMed Central

Shihana, Fathima; Dissanayake, Dhammika Menike; Dargan, Paul Ivor; Dawson, Andrew Hamilton

2011-01-01

Background Despite a significant increase in the number of patients with paracetamol poisoning in the developing world, plasma paracetamol assays are not widely available. The purpose of this study was to assess a low cost modified colorimetric paracetamol assay that has the potential to be performed in small laboratories with restricted resources. Methods The paracetamol assay used in this study was based on the Glynn and Kendal colorimetric method with a few modifications in order to decrease the production of nitrous gas and thereby reduce infrastructure costs. Preliminary validation studies were performed using spiked aqueous samples with known concentrations of paracetamol. Subsequently, the results from the colorimetric method for 114 stored clinical samples from patients with paracetamol poisoning were compared with those from the current gold-standard high-performance liquid chromatography (HPLC) method. A prospective survey, assessing the clinical use of the paracetamol assay, was performed on all patients with paracetamol poisoning attending the Peradeniya General Hospital, Sri Lanka over a ten-month period. Results The recovery study showed an excellent correlation (r2 >0.998) for paracetamol concentrations from 25- 400 mg/l. The final yellow colour was stable for at least 10 minutes at room temperature. There was also excellent correlation with the HPLC method (r2=0.9758). In the clinical cohort study, use of the antidote N-acetylcysteine was avoided in over a third of patients who had a plasma paracetamol concentration measured. The cost of consumables used per assay was $0.50 (US). Conclusions This colorimetric paracetamol assay is reliable and accurate and can be performed rapidly, easily and economically. Use of this assay in resource poor clinical settings has the potential to have a significant clinical and economic impact on the management of paracetamol poisoning. PMID:20095813

Can Spatiotemporal Fluoride (18F-) Uptake be Used to Assess Bone Formation in the Tibia? A Longitudinal Study Using PET/CT.

PubMed

Lundblad, Henrik; Karlsson-Thur, Charlotte; Maguire, Gerald Q; Jonsson, Cathrine; Noz, Marilyn E; Zeleznik, Michael P; Weidenhielm, Lars

2017-05-01

When a bone is broken for any reason, it is important for the orthopaedic surgeon to know how bone healing is progressing. There has been resurgence in the use of the fluoride ( 18 F - ) ion to evaluate various bone conditions. This has been made possible by availability of positron emission tomography (PET)/CT hybrid scanners together with cyclotrons. Absorbed on the bone surface from blood flow, 18 F - attaches to the osteoblasts in cancellous bone and acts as a pharmacokinetic agent, which reflects the local physiologic activity of bone. This is important because it shows bone formation indicating that the bone is healing or no bone formation indicating no healing. As 18 F - is extracted from blood in proportion to blood flow and bone formation, it thus enables determination of bone healing progress. The primary objective of this study was to determine whether videos showing the spatiotemporal uptake of 18 F - via PET bone scans could show problematic bone healing in patients with complex tibia conditions. A secondary objective was to determine if semiquantification of radionuclide uptake was consistent with bone healing. This study investigated measurements of tibia bone formation in patients with complex fractures, osteomyelitis, and osteotomies treated with a Taylor Spatial Frame TM (TSF) by comparing clinical healing progress with spatiotemporal fluoride ( 18 F - ) uptake and the semiquantitative standardized uptake value (SUV). This procedure included static and dynamic image acquisition. For intrapatient volumes acquired at different times, the CT and PET data were spatially registered to bring the ends of the bones that were supposed to heal into alignment. To qualitatively observe how and where bone formation was occurring, time-sequenced volumes were reconstructed and viewed as a video. To semiquantify the uptake, the mean and maximum SUVs (SUVmean, SUVmax) were calculated for the ends of the bones that were supposed to heal and for normal bone, using a spherical volume of interest drawn on the registered volumes. To make the semiquantitative data comparable for all patients with multiple examinations, the SUVmean and SUVmax difference per day (SUVmeanDPD and SUVmaxDPD) between the first PET/CT scan and each subsequent one was calculated. Indicators of poor healing progress were (1) uneven distribution of the radionuclide uptake between ends of the bones that were supposed to heal as seen in the video or, (2) low absolute magnitude of the SUV difference data. Twenty-four patients treated between October 2013 and April 2015 with a TSF gave informed consent to be examined with 18 F - PET/CT bone scans. Twenty-two patients successfully completed treatment, one of whom had only one PET/CT scan. Observation of 18 F - uptake was able to identify three patients whose healing progress was poor, indicated by uneven distribution of radionuclide uptake across the ends of the bones that were supposed to heal. An absolute magnitude of the SUVmaxDPD of 0.18 or greater indicated good bone formation progress. This was verified in 10 patients by the days between the operation to attach and to remove the TSF being less than 250 days, whereas other SUVmaxDPD values were ambiguous, with 11 patients achieving successful completion. Observation of the spatiotemporal uptake of 18 F - appears to be a promising method to enable the clinician to assess the progress of bone formation in different parts of the bone. Bone uptake which is uneven across the ends of bone that were supposed to heal or very low bone uptake might indicate impaired bone healing where early intervention may then be needed. However, semiquantification of 18 F - uptake (SUVmaxDPD), SUVmeanDPD) was ambiguous in showing consistency with the bone-healing progress. Level III, diagnostic study.

Achromatic-chromatic colorimetric sensors for on-off type detection of analytes.

PubMed

Heo, Jun Hyuk; Cho, Hui Hun; Lee, Jin Woong; Lee, Jung Heon

2014-12-21

We report the development of achromatic colorimetric sensors; sensors changing their colors from achromatic black to other chromatic colors. An achromatic colorimetric sensor was prepared by mixing a general colorimetric indicator, whose color changes between chromatic colors, and a complementary colored dye with no reaction to the targeted analyte. As the color of an achromatic colorimetric sensor changes from black to a chromatic color, the color change could be much easily recognized than general colorimetric sensors with naked eyes. More importantly, the achromatic colorimetric sensors enable on-off type recognition of the presence of analytes, which have not been achieved from most colorimetric sensors. In addition, the color changes from some achromatic colorimetric sensors (achromatic Eriochrome Black T and achromatic Benedict's solution) could be recognized with naked eyes at much lower concentration ranges than normal chromatic colorimetric sensors. These results provide new opportunities in the use of colorimetric sensors for diverse applications, such as harsh industrial, environmental, and biological detection.

Multiscale Modeling of Hematologic Disorders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fedosov, Dmitry A.; Pivkin, Igor; Pan, Wenxiao

Parasitic infectious diseases and other hereditary hematologic disorders are often associated with major changes in the shape and viscoelastic properties of red blood cells (RBCs). Such changes can disrupt blood flow and even brain perfusion, as in the case of cerebral malaria. Modeling of these hematologic disorders requires a seamless multiscale approach, where blood cells and blood flow in the entire arterial tree are represented accurately using physiologically consistent parameters. In this chapter, we present a computational methodology based on dissipative particle dynamics (DPD) which models RBCs as well as whole blood in health and disease. DPD is a Lagrangianmore » method that can be derived from systematic coarse-graining of molecular dynamics but can scale efficiently up to small arteries and can also be used to model RBCs down to spectrin level. To this end, we present two complementary mathematical models for RBCs and describe a systematic procedure on extracting the relevant input parameters from optical tweezers and microfluidic experiments for single RBCs. We then use these validated RBC models to predict the behavior of whole healthy blood and compare with experimental results. The same procedure is applied to modeling malaria, and results for infected single RBCs and whole blood are presented.« less

Analysis of phytochemical profile of Terminalia arjuna bark extract with antioxidative and antimicrobial properties

PubMed Central

Mandal, Shreya; Patra, Arpita; Samanta, Animesh; Roy, Suchismita; Mandal, Arpita; Mahapatra, Tapasi Das; Pradhan, Shrabani; Das, Koushik; Nandi, Dilip Kumar

2013-01-01

Objective To investigate phytochemical screening, antimicrobial activity and qualitative thin layer chromatographic separation of flavonoid components, antioxidant activity and total flavonoid compound of Terminalia arjuna. Methods For phytochemical screening, some common and available standard tests were done. Antimicrobial bioassay was done through agar well diffusion method. Detection of antioxidant activity and flavonoid compounds were done through thin layer chromatography. Total antioxidant activity was measured by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) in colorimetric method. Aluminum chloride colorimetric method was used for total flavonoid determination. Results Phytochemical screening showed the active compounds presence in high concentration, such as phytosterol, lactones, flavonoids, phenolic compounds and tannins and glycosides. The antimicrobial activity of extract showed that greater inhibition zone against Gram negative bacteria than Gram positive bacteria. This methanolic extract showed a promising antioxidant activity, as absorption of DPPH redicles decreased in DPPH free radical scavenging assay. Flavonoids components having antioxidant property present in the methanol extract at a level of 199.00 mg quercetin equivalent/g of dried methanol extract in colorimetric method. Conclusions The Terminalia arjuna bark extract revealed the presence of bio-active constituents which are known to exhibit medicinal as well as physiological activities. PMID:24093787

Color digital halftoning taking colorimetric color reproduction into account

NASA Astrophysics Data System (ADS)

Haneishi, Hideaki; Suzuki, Toshiaki; Shimoyama, Nobukatsu; Miyake, Yoichi

1996-01-01

Taking colorimetric color reproduction into account, the conventional error diffusion method is modified for color digital half-toning. Assuming that the input to a bilevel color printer is given in CIE-XYZ tristimulus values or CIE-LAB values instead of the more conventional RGB or YMC values, two modified versions based on vector operation in (1) the XYZ color space and (2) the LAB color space were tested. Experimental results show that the modified methods, especially the method using the LAB color space, resulted in better color reproduction performance than the conventional methods. Spatial artifacts that appear in the modified methods are presented and analyzed. It is also shown that the modified method (2) with a thresholding technique achieves a good spatial image quality.

Construction of mathematical model for measuring material concentration by colorimetric method

NASA Astrophysics Data System (ADS)

Liu, Bing; Gao, Lingceng; Yu, Kairong; Tan, Xianghua

2018-06-01

This paper use the method of multiple linear regression to discuss the data of C problem of mathematical modeling in 2017. First, we have established a regression model for the concentration of 5 substances. But only the regression model of the substance concentration of urea in milk can pass through the significance test. The regression model established by the second sets of data can pass the significance test. But this model exists serious multicollinearity. We have improved the model by principal component analysis. The improved model is used to control the system so that it is possible to measure the concentration of material by direct colorimetric method.

Spectral data compression using weighted principal component analysis with consideration of human visual system and light sources

NASA Astrophysics Data System (ADS)

Cao, Qian; Wan, Xiaoxia; Li, Junfeng; Liu, Qiang; Liang, Jingxing; Li, Chan

2016-10-01

This paper proposed two weight functions based on principal component analysis (PCA) to reserve more colorimetric information in spectral data compression process. One weight function consisted of the CIE XYZ color-matching functions representing the characteristic of the human visual system, while another was made up of the CIE XYZ color-matching functions of human visual system and relative spectral power distribution of the CIE standard illuminant D65. The improvement obtained from the proposed two methods were tested to compress and reconstruct the reflectance spectra of 1600 glossy Munsell color chips and 1950 Natural Color System color chips as well as six multispectral images. The performance was evaluated by the mean values of color difference under the CIE 1931 standard colorimetric observer and the CIE standard illuminant D65 and A. The mean values of root mean square errors between the original and reconstructed spectra were also calculated. The experimental results show that the proposed two methods significantly outperform the standard PCA and another two weighted PCA in the aspects of colorimetric reconstruction accuracy with very slight degradation in spectral reconstruction accuracy. In addition, weight functions with the CIE standard illuminant D65 can improve the colorimetric reconstruction accuracy compared to weight functions without the CIE standard illuminant D65.

Colorimetric assay of copper ions based on the inhibition of peroxidase-like activity of MoS2 nanosheets

NASA Astrophysics Data System (ADS)

Chen, Huan; Li, Zhihong; Liu, Xueting; Zhong, Jianhai; Lin, Tianran; Guo, Liangqia; Fu, Fengfu

2017-10-01

The peroxidase-like catalytic activity of MoS2 nanomaterials has been utilized for colorimetric bioassays and medical diagnostics. However, the application of peroxidase-like catalytic activity of MoS2 nanomaterials in environmental analysis was seldom explored. Herein, copper ions were found to inhibit the peroxidase-like catalytic activity of MoS2 nanosheets, which can catalyze the oxidation of 3, 3‧, 5, 5‧-tetramethylbenzidine by H2O2 to produce a colorimetric product. Based on this finding, a simple sensitive colorimetric method for the detection of copper ions was developed. In the presence of copper ions, the absorbance and color of the solution decreased with the increasing concentration of copper ions. The color of the solution can be used to semi-quantitative on-site assay of copper ions by naked eyes. A linear relationship between the absorbance and the concentration of copper ions was observed in the range of 0.4-4.0 μmol L- 1 with a detection limit of 92 nmol L- 1, which was much lower than the maximum contaminant level of copper in drinking water legislated by the Environmental Protection Agency of USA and the World Health Organization. The method was applied to detect copper ions in environmental water samples with satisfactory results.

Analysis of hydrodynamic fluctuations in heterogeneous adjacent multidomains in shear flow

NASA Astrophysics Data System (ADS)

Bian, Xin; Deng, Mingge; Tang, Yu-Hang; Karniadakis, George Em

2016-03-01

We analyze hydrodynamic fluctuations of a hybrid simulation under shear flow. The hybrid simulation is based on the Navier-Stokes (NS) equations on one domain and dissipative particle dynamics (DPD) on the other. The two domains overlap, and there is an artificial boundary for each one within the overlapping region. To impose the artificial boundary of the NS solver, a simple spatial-temporal averaging is performed on the DPD simulation. In the artificial boundary of the particle simulation, four popular strategies of constraint dynamics are implemented, namely the Maxwell buffer [Hadjiconstantinou and Patera, Int. J. Mod. Phys. C 08, 967 (1997), 10.1142/S0129183197000837], the relaxation dynamics [O'Connell and Thompson, Phys. Rev. E 52, R5792 (1995), 10.1103/PhysRevE.52.R5792], the least constraint dynamics [Nie et al., J. Fluid Mech. 500, 55 (2004), 10.1017/S0022112003007225; Werder et al., J. Comput. Phys. 205, 373 (2005), 10.1016/j.jcp.2004.11.019], and the flux imposition [Flekkøy et al., Europhys. Lett. 52, 271 (2000), 10.1209/epl/i2000-00434-8], to achieve a target mean value given by the NS solver. Going beyond the mean flow field of the hybrid simulations, we investigate the hydrodynamic fluctuations in the DPD domain. Toward that end, we calculate the transversal autocorrelation functions of the fluctuating variables in k space to evaluate the generation, transport, and dissipation of fluctuations in the presence of a hybrid interface. We quantify the unavoidable errors in the fluctuations, due to both the truncation of the domain and the constraint dynamics performed in the artificial boundary. Furthermore, we compare the four methods of constraint dynamics and demonstrate how to reduce the errors in fluctuations. The analysis and findings of this work are directly applicable to other hybrid simulations of fluid flow with thermal fluctuations.

Predicting dynamics and rheology of blood flow: A comparative study of multiscale and low-dimensional models of red blood cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Wenxiao; Fedosov, Dmitry A.; Caswell, Bruce

In this work we compare the predictive capability of two mathematical models for red blood cells (RBCs) focusing on blood flow in capillaries and arterioles. Both RBC models as well as their corresponding blood flows are based on the dissipative particle dynamics (DPD) method, a coarse-grained molecular dynamics approach. The first model employs a multiscale description of the RBC (MS-RBC), with its membrane represented by hundreds or even thousands of DPD-particles connected by springs into a triangular network in combination with out-of-plane elastic bending resistance. Extra dissipation within the network accounts for membrane viscosity, while the characteristic biconcave RBC shapemore » is achieved by imposition of constraints for constant membrane area and constant cell volume. The second model is based on a low-dimensional description (LD-RBC) constructed as a closed torus-like ring of only 10 large DPD colloidal particles. They are connected into a ring by worm-like chain (WLC) springs combined with bending resistance. The LD-RBC model can be fitted to represent the entire range of nonlinear elastic deformations as measured by optical-tweezers for healthy and for infected RBCs in malaria. MS-RBCs suspensions model the dynamics and rheology of blood flow accurately for any size vessel but this approach is computationally expensive above 100 microns. Surprisingly, the much more economical suspensions of LD-RBCs also capture the blood flow dynamics and rheology accurately except for vessels with sizes comparable to RBC diameter. In particular, the LD-RBC suspensions are shown to properly capture the experimental data for the apparent viscosity of blood and its cell-free layer (CFL) in tube flow. Taken together, these findings suggest a hierarchical approach in modeling blood flow in the arterial tree, whereby the MS-RBC model should be employed for capillaries and arterioles below 100 microns, the LD-RBC model for arterioles, and the continuum description for arteries.« less

Colorimetric DNAzyme Biosensor for Convenience Detection of Enterotoxin B Harboring Staphylococcus aureus from Food Samples.

PubMed

Mondal, Bhairab; N, Bhavanashri; Ramlal, Shylaja; Kingston, Joseph

2018-02-14

In the present study, a colorimetric DNAzymes biosensor strategy was devised in combination with immunomagnetic separation for rapid and easy detection of enterotoxin B harboring Staphylococcus aureus from food and clinical samples. The method employs immunocapture of S. aureus and amplification of seb gene by DNAzyme complementary sequence integrated forward primer and with specific reverse primer. The DNAzyme sequence integrated dsDNA PCR products when treated with hemin and TMB (3,3',5,5'-tetramethylbenzidine) in the presence of H 2 O 2 produce colorimetric signal. A linear relationship of optical signal with the initial template of seb was obtained which could be monitored by visually or spectrophotrometrically for qualitative and quantitative detection. The limit of detection for the assay was approximately 10 2 CFU/mL of seb gene harboring target. This method is convenient compared to gel based and ELISA systems. Further, spiking studies and analysis on natural samples emphasized the robustness and applicability of developed method. Altogether, the established assay could be a reliable alternative, low-cost, viable detection tool for the routine investigation of seb from food and clinical sources.

Indigo Carmine-Cu complex probe exhibiting dual colorimetric/fluorimetric sensing for selective determination of mono hydrogen phosphate ion and its logic behavior

NASA Astrophysics Data System (ADS)

Tavallali, Hossein; Deilamy-Rad, Gohar; Moaddeli, Ali; Asghari, Khadijeh

2017-08-01

A new selective probe based on copper complex of Indigo Carmine (IC-Cu2) for colorimetric, naked-eye, and fluorimetric recognition of mono hydrogen phosphate (MHP) ion in H2O/DMSO (4:1 v/v, 1.0 mmol L- 1 HEPES buffer solution pH 7.5) was developed. Detection limit of HPO42 - determination, achieved by fluorimetric and 3lorimetric method, are 0.071 and 1.46 μmol L- 1, respectively. Potential, therefore is clearly available in IC-Cu2 complex to detect HPO42 - in micromolar range via dual visible color change and fluorescence response. Present method shows high selectivity toward HPO42 - over other phosphate species and other anions and was successfully utilized for analysis of P2O5 content of a fertilizer sample. The results obtained by proposed chemosensor presented good agreement with those obtained the colorimetric reference method. INHIBIT and IMPLICATION logic gates operating at molecular level have been achieved using Cu2 + and HPO42 - as chemical inputs and UV-Vis absorbance signal as output.

Colorimetric determination of Timolol concentration based on localized surface plasmon resonance of silver nanoparticles

NASA Astrophysics Data System (ADS)

Amirjani, Amirmostafa; Bagheri, Mozhgan; Heydari, Mojgan; Hesaraki, Saeed

2016-09-01

In this work, a rapid and simple colorimetric method based on the surface plasmon resonance of silver nanoparticles (AgNPs) was developed for the detection of the drug Timolol. The method used is based on the interaction of Timolol with the surface of the as-synthesized AgNPs, which promotes aggregation of the nanoparticles. This aggregation exploits the surface plasmon resonance through the electric dipole-dipole interaction and coupling among the agglomerated particles, hence bringing forth distinctive changes in the spectra as well as the color of colloidal silver. UV-vis spectrophotometery was used to monitor the changes of the localized surface plasmon resonance of AgNPs at wavelengths of 400 and 550 nm. The developed colorimetric sensor has a wide dynamic range of 1.0 × 10-7 M-1.0 × 10-3 M for detection of Timolol with a low detection limit of 1.2 × 10-6 M. The proposed method was successfully applied for the determination of Timolol concentration in ophthalmic eye-drop solution with a response time lower than 40 s.

Gold nanorods for in-drop colorimetric determination of thiomersal after photochemical decomposition.

PubMed

Martín-Alonso, Manuel; Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

2018-03-13

This work reports on the implementation of gold nanorods (AuNRs) in headspace solvent microextraction for colorimetric determination of volatile analyte derivatives in a single drop. The exposure of AuNRs to both H 2 Se and elemental mercury (Hg 0 ) results in a shift of the longitudinal plasmonic band, unlike a number of volatiles. Accordingly, a method is reported for the determination of Hg 0 with potential applicability to the determination of thiomersal (sodium ethylmercurithiosalicylate). It is based on the photochemical decomposition of thiomersal into Hg(II) and subsequent exposure of AuNRs-containing microdrop to in situ generated Hg 0 . Colorimetric analysis of the enriched drop was carried out without dilution by means of a cuvetteless microvolume UV-vis spectrometer. Under optimal conditions, the limit of detection was 0.5 ng mL -1 (as Hg). The repeatability, expressed as relative standard deviation, was 8.4% (for n = 10). AuNRs exposed to increasing concentrations of the analyte were characterized by means of transmission electron microscopy and UV-vis spectrophotometry to ascertain the mechanism of detection. The method was finally applied to the determination of thiomersal in various pharmaceutical samples and showed quantitative recoveries. Graphical abstract Schematic illustration of a miniaturized colorimetric method based on the use of a microdrop of gold nanorods (AuNRs) for thiomersal determination in pharmaceuticals. It is based on the photochemical decomposition of thiomersal and subsequent Hg 0 generation with in-drop amalgamation.

Atomic absorption spectroscopic, conductometric and colorimetric methods for determination of fluoroquinolone antibiotics using ammonium reineckate ion-pair complex formation

NASA Astrophysics Data System (ADS)

Ragab, Gamal H.; Amin, Alaa S.

2004-03-01

Three accurate, rapid and simple atomic absorption spectrometric, conductometric and colorimetric methods were developed for the determination of norfloxacin (NRF), ciprofloxacin (CIP), ofloxacin (OFL) and enrofloxacin (ENF). The proposed methods depend upon the reaction of ammonium reineckate with the studied drugs to form stable precipitate of ion-pair complexes, which was dissolved in acetone. The pink coloured complexes were determined either by AAS or colorimetrically at λmax 525 nm directly using the dissolved complex. Using conductometric titration, the studied drugs could be evaluated in 50% (v/v) acetone in the range 5.0-65, 4.0-48, 5.0-56 and 6.0-72 μg ml -1 of NRF, CPF, OFL and ENF, respectively. The optimizations of various experimental conditions were described. The results obtained showed good recoveries of 99.15±1.15, 99.30±1.40, 99.60±1.50, and 99.00±1.25% with relative standard deviations of 0.81, 1.06, 0.97, and 0.69% for NRF, CPF, OFL, and ENF, respectively. Applications of the proposed methods to representative pharmaceutical formulations are successfully presented.

Parameterization of a mesoscopic model for the self-assembly of linear sodium alkyl sulfates

NASA Astrophysics Data System (ADS)

Mai, Zhaohuan; Couallier, Estelle; Rakib, Mohammed; Rousseau, Bernard

2014-05-01

A systematic approach to develop mesoscopic models for a series of linear anionic surfactants (CH3(CH2)n - 1OSO3Na, n = 6, 9, 12, 15) by dissipative particle dynamics (DPD) simulations is presented in this work. The four surfactants are represented by coarse-grained models composed of the same head group and different numbers of identical tail beads. The transferability of the DPD model over different surfactant systems is carefully checked by adjusting the repulsive interaction parameters and the rigidity of surfactant molecules, in order to reproduce key equilibrium properties of the aqueous micellar solutions observed experimentally, including critical micelle concentration (CMC) and average micelle aggregation number (Nag). We find that the chain length is a good index to optimize the parameters and evaluate the transferability of the DPD model. Our models qualitatively reproduce the essential properties of these surfactant analogues with a set of best-fit parameters. It is observed that the logarithm of the CMC value decreases linearly with the surfactant chain length, in agreement with Klevens' rule. With the best-fit and transferable set of parameters, we have been able to calculate the free energy contribution to micelle formation per methylene unit of -1.7 kJ/mol, very close to the experimentally reported value.

Heritability of markers of bone metabolism

NASA Technical Reports Server (NTRS)

Smith, Scott M.; Zwart, S. R.; Hargens, A. R.

2005-01-01

Several classic twin studies show genetic effects on markers of bone health, including bone mineral density and parathyroid hormone (PTH). This study was performed to assess the relative contribution of genetics to biochemical markers of bone metabolism. Fifteen sets of identical twins (8 male, 7 female) were housed in a clinical research center where diet was controlled (15% protein, 55% carbohydrate, 30% fat) for 3 consecutive days. Each day, 24-h urine pools were collected and N-telopeptide (NTX), deoxypyridinoline (DPD), calcium, and serum PTH were measured. The broad-sense heritability factor (H2) is an estimation of the portion of the total variance of a given phenotype that is attributable to genetic variance. H2 was estimated from the correlation coefficient of the phenotype data. H2 for NTX was 94% for males and 80% for females, DPD was 88% for males and 97% for females, urinary calcium excretion was 97% for males and 90% for females, and PTH was 92% for males and 79% for females. Since environmental variability was minimized for the 3 days of data collection, these heritability factors are likely overestimated. Nonetheless, the data support the concept that PTH is a predominantly heritable trait, and suggest that NTX, DPD, and calcium excretion are as well. These biochemical data support the previously documented heritability of bone health.

PLLA-PHB fiber membranes obtained by solvent-free electrospinning for short-time drug delivery.

PubMed

Cao, K; Liu, Y; Olkhov, A A; Siracusa, V; Iordanskii, A L

2018-02-01

Fibers of poly(L-lactic acid) (PLLA)/polyhydroxybutyrate (PHB) with different concentrations of the drug dipyridamole (DPD) were prepared using solvent-free melt electrospinning to obtain a polymeric drug delivery system. The electrospun fibers were morphologically, structurally, thermally, and dynamically characterized. Crazes that resemble lotus root crevices were interestingly observed in the 7:3 PLLA/PHB fibers with 1% DPD. The crystallinity of PLLA slightly decreased as PHB was incorporated, and the addition of DPD significantly reduced the melting temperature of the composite. The interactions between PLLA and PHB mainly occurred at a proportion of 7:3, and drug encapsulation in the fibers was verified. The kinetic profiles of drug release demonstrated the predominant multiple patterns involving a diffusional stage in the short-term mode of release and kinetic process related to the hydrolysis of the biopolymers. Furthermore, the dynamic behavior of the polymer molecules was evaluated based on the segmental mobility using probe electron spin resonance spectroscopy. The segmental mobility in the amorphous fraction of PLLA decreased with increasing PLLA content. The 9:1 PLLA/PHB system was more resistant to polymer hydrolysis than to the 7:3 system and the rate of diffusion transport was approximately two times higher for the 7:3 PLLA/PHB fibers than for the 9:1 PLLA/PHB fibers.

Dissipative particle dynamics study of velocity autocorrelation function and self-diffusion coefficient in terms of interaction potential strength

NASA Astrophysics Data System (ADS)

Zohravi, Elnaz; Shirani, Ebrahim; Pishevar, Ahmadreza; Karimpour, Hossein

2018-07-01

This research focuses on numerically investigating the self-diffusion coefficient and velocity autocorrelation function (VACF) of a dissipative particle dynamics (DPD) fluid as a function of the conservative interaction strength. Analytic solutions to VACF and self-diffusion coefficients in DPD were obtained by many researchers in some restricted cases including ideal gases, without the account of conservative force. As departure from the ideal gas conditions are accentuated with increasing the relative proportion of conservative force, it is anticipated that the VACF should gradually deviate from its normally expected exponentially decay. This trend is confirmed through numerical simulations and an expression in terms of the conservative force parameter, density and temperature is proposed for the self-diffusion coefficient. As it concerned the VACF, the equivalent Langevin equation describing Brownian motion of particles with a harmonic potential is adapted to the problem and reveals an exponentially decaying oscillatory pattern influenced by the conservative force parameter, dissipative parameter and temperature. Although the proposed model for obtaining the self-diffusion coefficient with consideration of the conservative force could not be verified due to computational complexities, nonetheless the Arrhenius dependency of the self-diffusion coefficient to temperature and pressure permits to certify our model over a definite range of DPD parameters.

Establishing a clinically relevant cutoff to the Dependency Scale from the dimensional clinical personality inventory.

PubMed

Carvalho, Lucas de F; Pianowski, Giselle; Filho, Nelson H

2017-05-01

The Clinical Dimensional Personality Inventory (IDCP) is a 163-item self-report tool developed for the assessment of 12 dimensions of personality pathology. One of the scales comprising the instrument-the Dependency scale-is intended to provide psychometric information on traits closely related to the Dependent Personality Disorder (DPD). In the present study, we used both Item Response Theory modeling and Receiver Operating Characteristic curve analysis to establishing a clinically meaningful cutoff for the IDCP Dependency Scale. Participants were 2.481 adults, comprised by outpatients diagnosed with DPD, outpatients diagnosed with other PDs, and adults from the general population. The Wright's item map graphing technique revealed that outpatients were located at the very high levels in the latent scale continuum of the Dependency Scale, with a very large effect size for the mean difference between patients and non-patients. The ROC curve analysis supported a cutoff at 2.3 points in the Dependency Scale, which yielded 0.86 of sensitivity and 0.79 of specificity. Findings from the present investigation suggest the IDCP Dependency Scale is useful as a screening tool of the core features of the DPD. We address potential clinical applications for the instrument, and discuss limitations from the present study. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

Reverse phase protein microarrays: fluorometric and colorimetric detection.

PubMed

Gallagher, Rosa I; Silvestri, Alessandra; Petricoin, Emanuel F; Liotta, Lance A; Espina, Virginia

2011-01-01

The Reverse Phase Protein Microarray (RPMA) is an array platform used to quantitate proteins and their posttranslationally modified forms. RPMAs are applicable for profiling key cellular signaling pathways and protein networks, allowing direct comparison of the activation state of proteins from multiple samples within the same array. The RPMA format consists of proteins immobilized directly on a nitrocellulose substratum. The analyte is subsequently probed with a primary antibody and a series of reagents for signal amplification and detection. Due to the diversity, low concentration, and large dynamic range of protein analytes, RPMAs require stringent signal amplification methods, high quality image acquisition, and software capable of precisely analyzing spot intensities on an array. Microarray detection strategies can be either fluorescent or colorimetric. The choice of a detection system depends on (a) the expected analyte concentration, (b) type of microarray imaging system, and (c) type of sample. The focus of this chapter is to describe RPMA detection and imaging using fluorescent and colorimetric (diaminobenzidine (DAB)) methods.

Silver nanoparticles-based colorimetric array for the detection of Thiophanate-methyl

NASA Astrophysics Data System (ADS)

Zheng, Mingda; Wang, Yingying; Wang, Chenge; Wei, Wei; Ma, Shuang; Sun, Xiaohan; He, Jiang

2018-06-01

A simple and selective colorimetric sensor based on citrate capped silver nanoparticles (Cit-AgNPs) is proposed for the detection of Thiophanate-methyl (TM) with high sensitivity and selectivity. The method based on the color change of Cit-AgNPs from yellow to cherry red with the addition of TM to Cit-AgNPs that caused a red-shift on the surface plasmon resonance (SPR) band from 394 nm to 525 nm due to the hydrogen-bonding and substitution. The density functional theory (DFT) method was also calculated the interactions between the TM and citrate ions. Under the optimized conditions, a linear relationship between the absorption ratio (A525nm/A394nm) and TM concentration was found in the range of 2-100 μM with correlation coefficient (R2) of 0.988. The detection limit of TM was 0.12 μM by UV-vis spectrometer. Moreover, the applicability of colorimetric sensor is successfully verified by the detection of TM in environmental samples with good recoveries.

Elevated urinary excretion of free pyridinoline in Friesian horses suggests a breed-specific increase in collagen degradation.

PubMed

Saey, Veronique; Tang, Jonathan; Ducatelle, Richard; Croubels, Siska; De Baere, Siegrid; Schauvliege, Stijn; van Loon, Gunther; Chiers, Koen

2018-04-25

Friesian horses are known for their high inbreeding rate resulting in several genetic diseases such as hydrocephaly and dwarfism. This last decade, several studies focused on two other presumed hereditary traits in Friesian horses: megaoesophagus and aortic rupture. The pathogenesis of these diseases remains obscure but an important role of collagen has been hypothesized. The purpose of this study was to examine possible breed-related differences in collagen catabolism. Urinary specimens from Friesian (n = 17, median age 10 years old) and Warmblood horses (n = 17, median age 10 years old) were assessed for mature collagen cross-links, i.e. pyridinoline (PYD) (=hydroxylysylpyridinoline/HP) and deoxypyridinoline (DPD) (lysylpyridinoline /LP). Solid-phase extraction was performed, followed by reversed-phase ion-paired liquid chromatography prior to tandem mass spectrometry (MS/MS) detection. Mean urinary concentrations of free PYD, expressed as fPYD/creatinine ratio, were significantly higher in Friesian horses compared to Warmblood horses (28.5 ± 5.2 versus 22.2 ± 9.6 nmol/mmol, p = 0.02) while mean fDPD/creatinine ratios were similar in both horse breeds (3.0 ± 0.7 versus 4.6 ± 3.7 nmol/mmol, p = 0.09). Since DPD is considered a specific bone degradation marker and PYD is more widely distributed in connective tissues, the significant elevation in the mean PYD/DPD ratio in Friesian versus Warmblood horses (9.6 ± 1.6 versus 5.7 ± 1.8, p < 0.0001) suggests a soft tissue origin for the increased fPYD levels. Considering that a previous study found no differences in total collagen content between Friesian and Warmblood horses for tendon and aortic tissue, this indicates a higher rate of collagen degradation. The latter might, at least in part, explain the predisposition of Friesians to connective tissue disorders.

Biomechanics of Hybrid Anterior Cervical Fusion and Artificial Disc Replacement in 3-Level Constructs: An In Vitro Investigation.

PubMed

Liao, Zhenhua; Fogel, Guy R; Pu, Ting; Gu, Hongsheng; Liu, Weiqiang

2015-11-03

The ideal surgical approach for cervical disk disease remains controversial, especially for multilevel cervical disease. The purpose of this study was to investigate the biomechanics of the cervical spine after 3-level hybrid surgery compared with 3-level anterior cervical discectomy and fusion (ACDF). Eighteen human cadaveric spines (C2-T1) were evaluated under displacement-input protocol. After intact testing, a simulated hybrid construct or fusion construct was created between C3 to C6 and tested in the following 3 conditions: 3-level disc plate disc (3DPD), 3-level plate disc plate (3PDP), and 3-level plate (3P). Compared to intact, almost 65~80% of motion was successfully restricted at C3-C6 fusion levels (p<0.05). 3DPD construct resulted in slight increase at the 3 instrumented levels (p>0.05). 3PDP construct resulted in significant decrease of ROM at C3-C6 levels less than 3P (p<0.05). Both 3DPD and 3PDP caused significant reduction of ROM at the arthrodesis level and produced motion increase at the arthroplasty level. For adjacent levels, 3P resulted in markedly increased contribution of both upper and lower adjacent levels (p<0.05). Significant motion increases lower than 3P were only noted at partly adjacent levels in some conditions for 3DPD and 3PDP (p<0.05). ACDF eliminated motion within the construct and greatly increased adjacent motion. Artificial cervical disc replacement normalized motion of its segment and adjacent segments. While hybrid conditions failed to restore normal motion within the construct, they significantly normalized motion in adjacent segments compared with the 3-level ACDF condition. The artificial disc in 3-level constructs has biomechanical advantages compared to fusion in normalizing motion.

New method for the direct determination of dissolved Fe(III) concentration in acid mine waters

USGS Publications Warehouse

To, T.B.; Nordstrom, D. Kirk; Cunningham, K.M.; Ball, J.W.; McCleskey, R. Blaine

1999-01-01

A new method for direct determination of dissolved Fe(III) in acid mine water has been developed. In most present methods, Fe(III) is determined by computing the difference between total dissolved Fe and dissolved Fe(II). For acid mine waters, frequently Fe(II) >> Fe(III); thus, accuracy and precision are considerably improved by determining Fe(III) concentration directly. The new method utilizes two selective ligands to stabilize Fe(III) and Fe(II), thereby preventing changes in Fe reduction-oxidation distribution. Complexed Fe(II) is cleanly removed using a silica-based, reversed-phase adsorbent, yielding excellent isolation of the Fe(III) complex. Iron(III) concentration is measured colorimetrically or by graphite furnace atomic absorption spectrometry (GFAAS). The method requires inexpensive commercial reagents and simple procedures that can be used in the field. Calcium(II), Ni(II), Pb(II), AI(III), Zn(II), and Cd(II) cause insignificant colorimetric interferences for most acid mine waters. Waters containing >20 mg of Cu/L could cause a colorimetric interference and should be measured by GFAAS. Cobalt(II) and Cr(III) interfere if their molar ratios to Fe(III) exceed 24 and 5, respectively. Iron(II) interferes when its concentration exceeds the capacity of the complexing ligand (14 mg/L). Because of the GFAAS elemental specificity, only Fe(II) is a potential interferent in the GFAAS technique. The method detection limit is 2 ??g/L (40 nM) using GFAAS and 20 ??g/L (0.4 ??M) by colorimetry.A new method for direct determination of dissolved Fe(III) in acid mine water has been developed. In most present methods, Fe(III) is determined by computing the difference between total dissolved Fe and dissolved Fe(II). For acid mine waters, frequently Fe(II)???Fe(III); thus, accuracy and precision are considerably improved by determining Fe(III) concentration directly. The new method utilizes two selective ligands to stabilize Fe(III) and Fe(II), thereby preventing changes in Fe reduction-oxidation distribution. Complexed Fe(II) is cleanly removed using a silica-based, reversed-phase adsorbent, yielding excellent isolation of the Fe(III) complex. Iron(III) concentration is measured colorimetrically or by graphite furnace atomic absorption spectrometry (GFAAS). The method requires inexpensive commercial reagents and simple procedures that can be used in the field. Calcium(II), Ni(II), Pb(II), Al(III), Zn(II), and Cd(II) cause insignificant colorimetric interferences for most acid mine waters. Waters containing >20 mg of Cu/L could cause a colorimetric interference and should be measured by GFAAS. Cobalt(II) and Cr(III) interfere if their molar ratios to Fe(III) exceed 24 and 5, respectively. Iron(II) interferes when its concentration exceeds the capacity of the complexing ligand (14 mg/L). Because of the GFAAS elemental specificity, only Fe(II) is a potential interferent in the GFAAS technique. The method detection limit is 2/??g/L (40 nM) using GFAAS and 20 ??g/L (0.4 ??M) by colorimetry.

Automated, colorimetric methods for determination of nitrate plus nitrite, nitrite, ammonium and orthophosphate ions in natural water samples

USGS Publications Warehouse

Antweiler, Ronald C.; Patton, Charles J.; Taylor, Howard E.

1996-01-01

The apparatus and methods used for the automatic, colorimetric determinations of dissolved nutrients (nitrate plus nitrite, nitrite, ammonium and orthophosphate) in natural waters are described. These techniques allow for the determination of nitrate plus nitrite for the concentration range 0.02 to 8 mg/L (milligrams per liter) as N (nitrogen); for nitrite, the range is 0.002 to 1.0 mg/L as N; for ammonium, the range is 0.006 to 2.0 mg/L as N; and for orthophosphate, the range is 0.002 to 1.0 mg/L as P (phosphorus). Data are presented that demonstrate the accuracy, precision and quality control of the methods.

An Improved Method for Determination of Cyanide Content in Bitter Almond Oil.

PubMed

Chen, Jia; Liu, Lei; Li, Mengjun; Yu, Xiuzhu; Zhang, Rui

2018-01-01

An improved colorimetric method for determination of cyanide content in bitter almond oil was developed. The optimal determination parameters were as follows: volume ratio of hydrochloric acid to bitter almond oil (v/v), 1.5:1; holding time for hydrolysis, 120 min; and volume ratio of distillation solution to bitter almond oil (v/v), 8:1. Analytical results showed that the relative standard deviations (SDs) of determinations were less than 10%, which satisfies the test requirements. The results of high-performance liquid chromatography and measurements exhibited a significant correlation (R = 0.9888, SD = 0.2015). Therefore, the improved colorimetric method can be used to determine cyanide content in bitter almond oil.

Colorimetric detection of genetically modified organisms based on exonuclease III-assisted target recycling and hemin/G-quadruplex DNAzyme amplification.

PubMed

Zhang, Decai; Wang, Weijia; Dong, Qian; Huang, Yunxiu; Wen, Dongmei; Mu, Yuejing; Yuan, Yong

2017-12-21

An isothermal colorimetric method is described for amplified detection of the CaMV 35S promoter sequence in genetically modified organism (GMO). It is based on (a) target DNA-triggered unlabeled molecular beacon (UMB) termini binding, and (b) exonuclease III (Exo III)-assisted target recycling, and (c) hemin/G-quadruplex (DNAzyme) based signal amplification. The specific binding of target to the G-quadruplex sequence-locked UMB triggers the digestion of Exo III. This, in turn, releases an active G-quadruplex segment and target DNA for successive hybridization and cleavage. The Exo III impellent recycling of targets produces numerous G-quadruplex sequences. These further associate with hemin to form DNAzymes and hence will catalyze H 2 O 2 -mediated oxidation of the chromogenic enzyme substrate ABTS 2- causing the formation of a green colored product. This finding enables a sensitive colorimetric determination of GMO DNA (at an analytical wavelength of 420 nm) at concentrations as low as 0.23 nM. By taking advantage of isothermal incubation, this method does not require sophisticated equipment or complicated syntheses. Analyses can be performed within 90 min. The method also discriminates single base mismatches. In our perception, it has a wide scope in that it may be applied to the detection of many other GMOs. Graphical abstract An isothermal and sensitive colorimetric method is described for amplified detection of CaMV 35S promoter sequence in genetically modified organism (GMO). It is based on target DNA-triggered molecular beacon (UMB) termini-binding and exonuclease III assisted target recycling, and on hemin/G-quadruplex (DNAzyme) signal amplification.

Visual detection of telomerase activity with a tunable dynamic range by using a gold nanoparticle probe-based hybridization protection strategy

NASA Astrophysics Data System (ADS)

Wang, Jiasi; Wu, Li; Ren, Jinsong; Qu, Xiaogang

2014-01-01

We developed a novel telomere complementary (TC) oligonucleotide modified AuNP probe (TC-AuNPs) for colorimetric analysis of telomerase activity. The mechanism of this method is that the telomerase reaction products (TRP), which can hybridize with the TC-AuNPs, are able to protect the AuNPs from the aggregation induced by salt. It is demonstrated that the colorimetric method enabled the analysis of the telomerase activity in 1000 HeLa cells with the naked eye, and down to 100 HeLa cells with the aid of UV-Vis spectroscopy. This strategy is not only convenient and sensitive, but also has a tunable dynamic range. The platform is also applicable for the initial screening of a telomerase inhibitor to discover new anticancer drugs.We developed a novel telomere complementary (TC) oligonucleotide modified AuNP probe (TC-AuNPs) for colorimetric analysis of telomerase activity. The mechanism of this method is that the telomerase reaction products (TRP), which can hybridize with the TC-AuNPs, are able to protect the AuNPs from the aggregation induced by salt. It is demonstrated that the colorimetric method enabled the analysis of the telomerase activity in 1000 HeLa cells with the naked eye, and down to 100 HeLa cells with the aid of UV-Vis spectroscopy. This strategy is not only convenient and sensitive, but also has a tunable dynamic range. The platform is also applicable for the initial screening of a telomerase inhibitor to discover new anticancer drugs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr05185d

Analytical properties of some commercially available nitrate reductase enzymes evaluated as replacements for cadmium in automated, semiautomated, and manual colorimetric methods for determination of nitrate plus nitrite in water

USGS Publications Warehouse

Patton, Charles J.; Kryskalla, Jennifer R.

2013-01-01

A multiyear research effort at the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) evaluated several commercially available nitrate reductase (NaR) enzymes as replacements for toxic cadmium in longstanding automated colorimetric air-segmented continuous-flow analyzer (CFA) methods for determining nitrate plus nitrite (NOx) in water. This research culminated in USGS approved standard- and low-level enzymatic reduction, colorimetric automated discrete analyzer NOx methods that have been in routine operation at the NWQL since October 2011. The enzyme used in these methods (AtNaR2) is a product of recombinant expression of NaR from Arabidopsis thaliana (L.) Heynh. (mouseear cress) in the yeast Pichia pastoris. Because the scope of the validation report for these new automated discrete analyzer methods, published as U.S. Geological Survey Techniques and Methods 5–B8, was limited to performance benchmarks and operational details, extensive foundational research with different enzymes—primarily YNaR1, a product of recombinant expression of NaR from Pichia angusta in the yeast Pichia pastoris—remained unpublished until now. This report documents research and development at the NWQL that was foundational to development and validation of the discrete analyzer methods. It includes: (1) details of instrumentation used to acquire kinetics data for several NaR enzymes in the presence and absence of known or suspected inhibitors in relation to reaction temperature and reaction pH; and (2) validation results—method detection limits, precision and bias estimates, spike recoveries, and interference studies—for standard- and low-level automated colorimetric CFA-YNaR1 reduction NOx methods in relation to corresponding USGS approved CFA cadmium-reduction (CdR) NOx methods. The cornerstone of this validation is paired sample statistical and graphical analysis of NOx concentrations from more than 3,800 geographically and seasonally diverse surface-water and groundwater samples that were analyzed in parallel by CFA-CdR and CFA enzyme-reduction methods. Finally, (3) demonstration of a semiautomated batch procedure in which 2-milliliter analyzer cups or disposable spectrophotometer cuvettes serve as reaction vessels for enzymatic reduction of nitrate to nitrite prior to analytical determinations. After the reduction step, analyzer cups are loaded onto CFA, flow injection, or discrete analyzers for simple, rapid, automatic nitrite determinations. In the case of manual determinations, analysts dispense colorimetric reagents into cuvettes containing post-reduction samples, allow time for color to develop, insert cuvettes individually into a spectrophotometer, and record percent transmittance or absorbance in relation to a reagent blank. Data presented here demonstrate equivalent analytical performance of enzymatic reduction NOx methods in these various formats to that of benchmark CFA-CdR NOx methods.

Effect of black point on accuracy of LCD displays colorimetric characterization

NASA Astrophysics Data System (ADS)

Li, Tong; Xie, Kai; He, Nannan; Ye, Yushan

2018-03-01

Black point is the point at which RGB's single channel digital drive value is 0. Due to the problem of light leakage of liquid-crystal displays (LCDs), black point's luminance value is not 0, this phenomenon bring some errors to colorimetric characterization of LCDs, especially low luminance value driving greater sampling effect. This paper describes the characteristic accuracy of polynomial model method and the effect of black point on accuracy, the color difference accuracy is given. When considering the black point in the characteristics equation, the maximum color difference is 3.246, the maximum color difference than without considering the black points reduced by 2.36. The experimental results show that the accuracy of LCDs colorimetric characterization can be improved, if the effect of black point is eliminated properly.

Colorimetric determination of Al(III) based on the aggregation of gold nanoparticles functionalized with novel 4-benzoyl pyrazolone derivative

NASA Astrophysics Data System (ADS)

Abubaker, Mariam; Ngah, Che Wan Zanariah Che Wan; Ahmad, Musa; Kuswandi, Bambang

2018-06-01

A sensitive and selective colorimetric method has been developed for detection of Al3+ ion using 4-benzoyl pyrazolone-functionalized gold nanoparticles (BMPBP-AuNPs) as novel colorimetric probes. The BMPBP-AuNPs were characterized by UV-visible spectrometry and transmission electron microscopy (TEM). It was found that the addition of the Al3+ ions led to a rapid aggregation of the BMPBP-AuNPs, which changed the color of the mixture from red to blue. Furthermore, there was a shift in the characteristic surface plasmon resonance (SPR) peak from 524 to 650 nm of BMPBP-AuNPs, which confirmed that a good linear relation (R2 = 0.9935) was present between the absorption ratio of 524 and 650 nm. Also, the assay detected the Al3+ ion concentrations in the linear range 0-12 ppm with the detection limit is 0.05 ppm. Finally, the synthesized BMPBP-AuNPs were successfully used as a colorimetric sensor for the selective and sensitive detection of the Al3+ ions in water samples.

Highly Sensitive Colorimetric Biosensor for Staphylococcal Enterotoxin B by a Label-Free Aptamer and Gold Nanoparticles

PubMed Central

Mondal, Bhairab; Ramlal, Shylaja; Lavu, Padma S.; N, Bhavanashri; Kingston, Joseph

2018-01-01

A simple, sensitive and selective colorimetric biosensor for the detection of Staphylococcal enterotoxin B (SEB) was developed using SEB-binding aptamer (SEB2) as recognition element and unmodified gold nanoparticles (AuNPs) as colorimetric probes. The assay is based on color change from red to purple due to conformational change of aptamer in the presence of SEB, and the phenomenon of salt-induced AuNPs aggregation which could be monitored by naked eye or UV–vis spectrometer. Results showed that the AuNPs can effectively differentiate the SEB induced conformational change of the aptamer in the presence of a given high salt concentration. A linear response in the range of 50 μg/mL to 0.5 ng/mL of SEB concentration was obtained. The assay was highly specific to SEB as compared to other related toxins. The limit of detection (LOD) of SEB achieved within few minutes was 50 ng/mL visually and spectrometric method improved it to 0.5 ng/mL. Robustness of the assay was tested in artificially spiked milk samples and cross-checked using in house developed sandwich ELISA (IgY as capturing and SEB specific monoclonal as revealing antibody) and PCR. This colorimetric assay could be a suitable alternative over existing methods during biological emergencies due to its simplicity, sensitive and cost effectiveness. PMID:29487580

Nano-colloid electrophoretic transport: Fully explicit modelling via dissipative particle dynamics

NASA Astrophysics Data System (ADS)

Hassanzadeh Afrouzi, Hamid; Farhadi, Mousa; Sedighi, Kurosh; Moshfegh, Abouzar

2018-02-01

In present study, a novel fully explicit approach using dissipative particle dynamics (DPD) method is introduced for modelling electrophoretic transport of nano-colloids in an electrolyte solution. Slater type charge smearing function included in 3D Ewald summation method is employed to treat electrostatic interaction. Moreover, capability of different thermostats are challenged to control the system temperature and study the dynamic response of colloidal electrophoretic mobility under practical ranges of external electric field in nano scale application (0.072 < E < 0.361 v / nm) covering non-linear response regime, and ionic salt concentration (0.049 < SC < 0.69 [M]) covering weak to strong Debye screening of the colloid. The effect of different colloidal repulsions are then studied on temperature, reduced mobility and zeta potential which is computed based on charge distribution within the spherical colloidal EDL. System temperature and electrophoretic mobility both show a direct and inverse relationship respectively with electric field and colloidal repulsion. Mobility declining with colloidal repulsion reaches a plateau which is a relatively constant value at each electrolyte salinity for Aii > 600 in DPD units regardless of electric field intensity. Nosé-Hoover-Lowe-Andersen and Lowe-Andersen thermostats are found to function more effectively under high electric fields (E > 0.145 [ v / nm ]) while thermal equilibrium is maintained. Reasonable agreements are achieved by benchmarking the radial distribution function with available electrolyte structure modellings, as well as comparing reduced mobility against conventional Smoluchowski and Hückel theories, and numerical solution of Poisson-Boltzmann equation.

Dissipative particle dynamics: Systematic parametrization using water-octanol partition coefficients

NASA Astrophysics Data System (ADS)

Anderson, Richard L.; Bray, David J.; Ferrante, Andrea S.; Noro, Massimo G.; Stott, Ian P.; Warren, Patrick B.

2017-09-01

We present a systematic, top-down, thermodynamic parametrization scheme for dissipative particle dynamics (DPD) using water-octanol partition coefficients, supplemented by water-octanol phase equilibria and pure liquid phase density data. We demonstrate the feasibility of computing the required partition coefficients in DPD using brute-force simulation, within an adaptive semi-automatic staged optimization scheme. We test the methodology by fitting to experimental partition coefficient data for twenty one small molecules in five classes comprising alcohols and poly-alcohols, amines, ethers and simple aromatics, and alkanes (i.e., hexane). Finally, we illustrate the transferability of a subset of the determined parameters by calculating the critical micelle concentrations and mean aggregation numbers of selected alkyl ethoxylate surfactants, in good agreement with reported experimental values.

Augmented Reality for Real-Time Detection and Interpretation of Colorimetric Signals Generated by Paper-Based Biosensors.

PubMed

Russell, Steven M; Doménech-Sánchez, Antonio; de la Rica, Roberto

2017-06-23

Colorimetric tests are becoming increasingly popular in point-of-need analyses due to the possibility of detecting the signal with the naked eye, which eliminates the utilization of bulky and costly instruments only available in laboratories. However, colorimetric tests may be interpreted incorrectly by nonspecialists due to disparities in color perception or a lack of training. Here we solve this issue with a method that not only detects colorimetric signals but also interprets them so that the test outcome is understandable for anyone. It consists of an augmented reality (AR) app that uses a camera to detect the colored signals generated by a nanoparticle-based immunoassay, and that yields a warning symbol or message when the concentration of analyte is higher than a certain threshold. The proposed method detected the model analyte mouse IgG with a limit of detection of 0.3 μg mL -1 , which was comparable to the limit of detection afforded by classical densitometry performed with a nonportable device. When adapted to the detection of E. coli, the app always yielded a "hazard" warning symbol when the concentration of E. coli in the sample was above the infective dose (10 6 cfu mL -1 or higher). The proposed method could help nonspecialists make a decision about drinking from a potentially contaminated water source by yielding an unambiguous message that is easily understood by anyone. The widespread availability of smartphones along with the inexpensive paper test that requires no enzymes to generate the signal makes the proposed assay promising for analyses in remote locations and developing countries.

A simple and selective colorimetric mercury (II) sensing system based on chitosan stabilized gold nanoparticles and 2,6-pyridinedicarboxylic acid.

PubMed

Tian, Kun; Siegel, Gene; Tiwari, Ashutosh

2017-02-01

The development of simple and cost-effective methods for the detection and treatment of Hg 2+ in the environment is an important area of research due to the serious health risk that Hg 2+ poses to humans. Colorimetric sensing based on the induced aggregation of nanoparticles is of great interest since it offers a low cost, simple, and relatively rapid procedure, making it perfect for on-site analysis. Herein we report the development of a simple colorimetric sensor for the selective detection and estimation of mercury ions in water, based on chitosan stabilized gold nanoparticles (AuNPs) and 2,6-pyridinedicarboxylic acid (PDA). In the presence of Hg 2+ , PDA induces the aggregation of AuNPs, causing the solution to change colors varying from red to blue, depending on the concentration of Hg 2+ . The formation of aggregated AuNPs in the presence of Hg 2+ was confirmed using transmission electron microscopy (TEM) and UV-Vis spectroscopy. The method exhibits linearity in the range of 300nM to 5μM and shows excellent selectivity towards Hg 2+ among seventeen different metal ions and was successfully applied for the detection of Hg 2+ in spiked river water samples. The developed technique is simple and superior to the existing techniques in that it allows detection of Hg 2+ using the naked eye and simple and rapid colorimetric analysis, which eliminates the need for sophisticated instruments and sample preparation methods. Copyright © 2016 Elsevier B.V. All rights reserved.

Pitfalls in the detection of cholesterol in Huntington's disease models.

PubMed

Marullo, Manuela; Valenza, Marta; Leoni, Valerio; Caccia, Claudio; Scarlatti, Chiara; De Mario, Agnese; Zuccato, Chiara; Di Donato, Stefano; Carafoli, Ernesto; Cattaneo, Elena

2012-10-11

Background Abnormalities in brain cholesterol homeostasis have been reported in Huntington's disease (HD), an adult-onset neurodegenerative disorder caused by an expansion in the number of CAG repeats in the huntingtin (HTT) gene. However, the results have been contradictory with respect to whether cholesterol levels increase or decrease in HD models. Biochemical and mass spectrometry methods show reduced levels of cholesterol precursors and cholesterol in HD cells and in the brains of several HD animal models. Abnormal brain cholesterol homeostasis was also inferred from studies in HD patients. In contrast, colorimetric and enzymatic methods indicate cholesterol accumulation in HD cells and tissues. Here we used several methods to investigate cholesterol levels in cultured cells in the presence or absence of mutant HTT protein. Results Colorimetric and enzymatic methods with low sensitivity gave variable results, whereas results from a sensitive analytical method, gas chromatography-mass spectrometry, were more reliable. Sample preparation, high cell density and cell clonality also influenced the detection of intracellular cholesterol. Conclusions Detection of cholesterol in HD samples by colorimetric and enzymatic assays should be supplemented by detection using more sensitive analytical methods. Care must be taken to prepare the sample appropriately. By evaluating lathosterol levels using isotopic dilution mass spectrometry, we confirmed reduced cholesterol biosynthesis in knock-in cells expressing the polyQ mutation in a constitutive or inducible manner. *Correspondence should be addressed to Elena Cattaneo: elena.cattaneo@unimi.it.

Limitations of three-dimensional power Doppler angiography in preoperative evaluation of ovarian tumors.

PubMed

Silvestre, Liliane; Martins, Wellington P; Candido-Dos-Reis, Francisco J

2015-07-29

This study describes the accuracy of three-dimensional power Doppler (3D-PD) angiography as secondary method for differential diagnosis of ovarian tumors. Seventy-five women scheduled for surgical removal of adnexal masses were assessed by transvaginal ultrasound. Ovarian tumors were classified by IOTA simple rules and two three-dimensional blocks were recorded. In a second step analyses, a 4 cm(3) spherical sample was obtained from the highest vascularized solid area of each stored block. Vascularization index (VI), flow index (FI) and vascularization-flow index (VFI) were calculated. The repeatability was assessed by concordance correlation coefficient (CCC) and limits of agreement (LoA), and diagnostic accuracy by area under ROC curve. IOTA simple rules classified 26 cases as benign, nine as inconclusive and 40 as malignant. There were eight false positive and no false negative. Among the masses classified as inconclusive or malignant by IOTA simple rules, the CCCs were 0.91 for VI, 0.70 for FI, and 0.86 for VFI. The areas under ROC curve were 0.82 for VI, 0.67 for FI and 0.81 for VFI. 3D-PD angiography presented considerable intraobserver variability and low accuracy for identifying false positive results of IOTA simple rules.

Institutional analysis of milkfish supply chain using interpretive structural modelling (ISM) (case study of UD. Bunda Foods, Sidoarjo District)

NASA Astrophysics Data System (ADS)

Silalahi, R. L. R.; Mustaniroh, S. A.; Ikasari, D. M.; Sriulina, R. P.

2018-03-01

UD. Bunda Foods is an SME located in the district of Sidoarjo. UD. Bunda Foods has problems of maintaining its milkfish’s quality assurance and developing marketing strategies. Improving those problems enables UD. Bunda Foods to compete with other similar SMEs and to market its product for further expansion of their business. The objectives of this study were to determine the model of the institutional structure of the milkfish supply chain, to determine the elements, the sub-elements, and the relationship among each element. The method used in this research was Interpretive Structural Modeling (ISM), involving 5 experts as respondents consisting of 1 practitioner, 1 academician, and 3 government organisation employees. The results showed that there were two key elements include requirement and goals elements. Based on the Drive Power-Dependence (DP-D) matrix, the key sub-elements of requirement element, consisted of raw material continuity, appropriate marketing strategy, and production capital, were positioned in the Linkage sector quadrant. The DP-D matrix for the key sub-elements of the goal element also showed a similar position. The findings suggested several managerial implications to be carried out by UD. Bunda Foods include establishing good relationships with all involved institutions, obtaining capital assistance, and attending the marketing training provided by the government.

Pharmacogenetics in cancer therapy - 8 years of experience at the Institute for Oncology and Radiology of Serbia.

PubMed

Cavic, Milena; Krivokuca, Ana; Boljevic, Ivana; Brotto, Ksenija; Jovanovic, Katarina; Tanic, Miljana; Filipovic, Lana; Zec, Manja; Malisic, Emina; Jankovic, Radmila; Radulovic, Sinisa

2016-01-01

Pharmacogenetics is a study of possible mechanism by which an individual's response to drugs is genetically determined by variations in their DNA sequence. The aim of pharmacogenetics is to identify the optimal drug and dose for each individual based on their genetic constitution, i.e. to individualize drug treatment. This leads to achieving the maximal therapeutic response for each patient, while reducing adverse side effects of therapy and the cost of treatment. A centralized pharmacogenetics service was formed at the Institute for Oncology and Radiology of Serbia (IORS) with the aim to provide a personalized approach to cancer treatment of Serbian patients. Analyses of KRAS mutations in metastatic colorectal cancer, EGFR mutations in advanced non-small cell lung cancer, CYP2D6 polymorphism in breast cancer, DPD polymorphism in colorectal cancer and MTHFR polymorphism in osteosarcoma have been performed by real time polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (PCR-RFLP). Mutation testing analyses were successful for 1694 KRAS samples and 1821 EGFR samples, while polymorphism testing was successful for 9 CYP2D6 samples, 65 DPD samples and 35 MTHFR samples. Pharmacogenetic methods presented in this paper provide cancer patients in Serbia the best possible choice of treatment at the moment.

A simple and highly sensitive colorimetric detection method for gaseous formaldehyde.

PubMed

Feng, Liang; Musto, Christopher J; Suslick, Kenneth S

2010-03-31

A colorimetric detection method using amine-functionalized polymer films doped with a pH indicator has been developed for the rapid, sensitive, and quantitative detection of gaseous formaldehyde at concentrations well below the immediately dangerous to life or health (IDLH) limit. In 1 min, visible color changes are easily observed, even down to the permissible exposure limit (PEL) at 750 ppb. The limit of detection is below 50 ppb (7% of the PEL) after 10 min of exposure. This sensor is essentially unaffected by changes in humidity or temperature (4 to 50 degrees C) and is not sensitive to common interferents.

Cyclen dithiocarbamate-functionalized silver nanoparticles as a probe for colorimetric sensing of thiram and paraquat pesticides via host-guest chemistry

NASA Astrophysics Data System (ADS)

Rohit, Jigneshkumar V.; Kailasa, Suresh Kumar

2014-11-01

We have developed a simple and rapid colorimetric method for on-site analysis of thiram and paraquat using cyclen dithiocarbamate-functionalized silver nanoparticles (CN-DTC-Ag NPs) as a colorimetric probe. The synthesized CN-DTC-Ag NPs were characterized by UV-Visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy, dynamic light scattering, and transmission electron microscopic techniques. The CN-DTC molecules provide good supramolecular self assembly on the surfaces of Ag NPs to encapsulate thiram and paraquat selectively via "host-guest" chemistry, resulting in red-shift in surface plasmon resonance peak of CN-DTC-Ag NPs from 396 to 530 nm and 510 nm and color change from yellow to pink for thiram and to orange for paraquat, which can be naked-eye detected. The present method shows good linearity in the range of 10.0-20.0 µM and of 50.0-250 µM with limits of detection 2.81 × 10-6 M and 7.21 × 10-6 M for thiram and paraquat, respectively. This method was proved as a promising tool for on-site and real-time monitoring of thiram and paraquat in environmental water, potato, and wheat samples.

A Colorimetric Microplate Assay for DNA-Binding Activity of His-Tagged MutS Protein.

PubMed

Banasik, Michał; Sachadyn, Paweł

2016-09-01

A simple microplate method was designed for rapid testing DNA-binding activity of proteins. The principle of the assay involves binding of tested DNA by his-tagged protein immobilized on a nickel-coated ELISA plate, following colorimetric detection of biotinylated DNA with avidin conjugated to horseradish peroxidase. The method was used to compare DNA mismatch binding activities of MutS proteins from three bacterial species. The assay required relatively low amounts of tested protein (approximately 0.5-10 pmol) and DNA (0.1-10 pmol) and a relatively short time of analysis (up to 60 min). The method is very simple to apply and convenient to test different buffer conditions of DNA-protein binding. Sensitive colorimetric detection enables naked eye observations and quantitation with an ELISA reader. The performance of the assay, which we believe is a distinguishing trait of the method, is based on two strong and specific molecular interactions: binding of a his-tagged protein to a nickel-coated microplate and binding of biotinylated DNA to avidin. In the reported experiments, the solution was used to optimize the conditions for DNA mismatch binding by MutS protein; however, the approach could be implemented to test nucleic acids interactions with any protein of interest.

Analysis of phytochemical profile of Terminalia arjuna bark extract with antioxidative and antimicrobial properties.

PubMed

Mandal, Shreya; Patra, Arpita; Samanta, Animesh; Roy, Suchismita; Mandal, Arpita; Mahapatra, Tapasi Das; Pradhan, Shrabani; Das, Koushik; Nandi, Dilip Kumar

2013-12-01

To investigate phytochemical screening, antimicrobial activity and qualitative thin layer chromatographic separation of flavonoid components, antioxidant activity and total flavonoid compound of Terminalia arjuna. For phytochemical screening, some common and available standard tests were done. Antimicrobial bioassay was done through agar well diffusion method. Detection of antioxidant activity and flavonoid compounds were done through thin layer chromatography. Total antioxidant activity was measured by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) in colorimetric method. Aluminum chloride colorimetric method was used for total flavonoid determination. Phytochemical screening showed the active compounds presence in high concentration, such as phytosterol, lactones, flavonoids, phenolic compounds and tannins and glycosides. The antimicrobial activity of extract showed that greater inhibition zone against Gram negative bacteria than Gram positive bacteria. This methanolic extract showed a promising antioxidant activity, as absorption of DPPH redicles decreased in DPPH free radical scavenging assay. Flavonoids components having antioxidant property present in the methanol extract at a level of 199.00 mg quercetin equivalent/g of dried methanol extract in colorimetric method. The Terminalia arjuna bark extract revealed the presence of bio-active constituents which are known to exhibit medicinal as well as physiological activities. Copyright © 2013 Asian Pacific Tropical Biomedical Magazine. Published by Elsevier B.V. All rights reserved.

[Research on the designing method of a special shade guide for tooth whitening].

PubMed

Xu, Yingxin

2015-10-01

To investigate a method of designing an accurate and scientific shade guide, especially used for judging the effect of tooth whitening, by analyzing the colorimetric values of discolored teeth statistically. One hundred thirty-six pictures of patients who had been receiving the Beyond cold light whitening treatment from February 2009 to July 2014 were analyzed, including 25 tetracycline teeth, 61 mottled-enamel teeth, and 50 yellow teeth. The colorimetric values of discolored teeth were measured. The L* values of shade tabs were calculated by hierarchical clustering of those of discolored teeth. The a* and b* values of shade tabs were the mean of those observed for discolored teeth. Accordingly, different shade guides were designed for each type of discolored teeth, and the effects were evaluated. A statistically significant difference in colorimetric values was found among the three types of discolored teeth. Compared with the Vitapan Classical shade guide, the shade guides designed through the present method were more scientific and accurate in judging the effect of tooth whitening. Moreover, the arrangement of shade tabs was more logical, and the color difference between shade tabs and discolored teeth was smaller. The proposed designing method is theoretically feasible, although its clinical effect has yet to be proven.

Colorimetric and atomic absorption spectrometric determination of mucolytic drug ambroxol through ion-pair formation with iron and thiocyanate.

PubMed

Levent, Abdulkadir; Sentürk, Zühre

2010-09-01

Colorimetric and atomic absorption spectrometric methods have been developed for the determination of mucolytic drug Ambroxol. These procedures depend upon the reaction of iron(III) metal ion with the drug in the presence of thiocyanate ion to form stable ion-pair complex which extractable chloroform. The red-coloured complex was determined either colorimetrically at 510 nm or by indirect atomic absorption spectrometry (AAS) via the determination of the iron content in the formed complex. The optimum experimental conditions for pH, concentrations of Fe(3+) and SCN(-), shaking time, phase ratio, and the number of extractions were determined. Under the proposed conditions, linearity was obeyed in the concentration ranges 4.1x10(-6) - 5.7x10(-5) M (1.7-23.6 µg mL(-1)) using both methods, with detection limits of 4.6x10(-7) M (0.19 µg mL(-1)) for colorimetry and 1.1x10(-6) M (0.46 µg mL(-1)) for AAS. The proposed methods were applied for the determination of Ambroxol in tablet dosage forms. The results obtained were statistically analyzed and compared with those obtained by applying the high-performance liquid chromatographic method with diode-array detection.

Colorimetric detection of trivalent chromium in aqueous solution using tartrate-capped silver nanoparticles as probe.

PubMed

Xu, Yunbo; Dong, Yangjun; Jiang, Xue; Zhu, Ningning

2013-10-01

This study describes a simple and highly selective method for the colorimetric detection of trivalent chromium (Cr3+) using tartrate-capped silver nanoparticles (AgNPs) as probe. The addition of tartrate to the initially prepared AgNPs gives tartrate-stabilized AgNPs ascribing to the electrostatic repulsion of the highly negatively charged tartrate ions covered on the surface of AgNPs. It is found that, in the presence of Cr3+ in aqueous solution, the aggregation of tartrate-stabilized AgNPs occurs. The color of AgNPs suspension changes from yellow to pink and the surface plasmon absorption band broadens and red shifts, which could be applied for the colorimetric detection of Cr3+ in aqueous solution. The utilization of tartrate-stabilized AgNPs as probe substantially increases the selectivity and sensitivity for colorimetric detection of Cr3+. Control experiments with the addition of over 14 other metal ions, such as Pb2+, Zn2+, Cr2O7(2-), Cd2+, Co2+, Cu2+, Al3+, Ni2+, Mn2+, Ba2+, Fe3+, Ca2+, Mg2+, Sr+ do not result in a distinct change in the color or in the spectrum of the suspension, indicating that these metal ions do not interfere with the colorimetric detection of Cr3+. Under the conditions employed here, A502/A393 (ratio of absorption value at 502 nm to 393 nm) is linear with the concentration of Cr3+ within a concentration range from 0.1 to 1.17 microM with a detection limit of 0.06 microM. This study may offer a simple, rapid and sensitive approach to colorimetric detection of Cr3+ in aqueous solution.

Colorimetric susceptibility testing for Aspergillus fumigatus: comparison of menadione-augmented 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide and Alamar blue tests.

PubMed Central

Jahn, B; Stüben, A; Bhakdi, S

1996-01-01

Two colorimetric methods that use Alamar Blue or 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) for assaying the in vitro activities of antifungal agents have been described. We report that both tests performed similarly when the antifungal activity of amphotericin B against Candida albicans was determined. However, only the MTT test generated interpretable data when Aspergillus fumigatus was used. PMID:8818910

A smartphone colorimetric reader integrated with an ambient light sensor and a 3D printed attachment for on-site detection of zearalenone.

PubMed

Chen, Yuan; Fu, Qiangqiang; Li, Dagang; Xie, Jun; Ke, Dongxu; Song, Qifang; Tang, Yong; Wang, Hong

2017-11-01

Smartphone biosensors could be cost-effective, portable instruments to be used for the readout of liquid colorimetric assays. However, current reported smartphone colorimetric readers have relied on photos of liquid assays captured using a camera, and then analyzed using software programs. This approach results in a relatively low accuracy and low generality. In this work, we reported a novel smartphone colorimetric reader that has been integrated with an ambient light sensor and a 3D printed attachment for the readout of liquid colorimetric assays. The portable and low-cost ($0.15) reader utilized a simplified electronic and light path design. Furthermore, our reported smartphone colorimetric reader can be compatible with different smartphones. As a proof of principle, the utility of this device was demonstrated using it in conjunction with an enzyme-linked immunosorbent assay to detect zearalenone. Results were consistent with those obtained using a professional microplate reader. The developed smartphone colorimetric reader was capable of providing scalable, cost-effective, and accurate results for liquid colorimetric assays that related to clinical diagnoses, environment pollution, and food testing. Graphical abstract A novel smartphone colorimetric reader that has been integrated with an ambient light sensor and a 3D printed attachment for the readout of liquid colorimetric assays.

An improved method for LCD displays colorimetric characterization

NASA Astrophysics Data System (ADS)

Li, Tong; Xie, Kai; Wang, Qiaojie; He, Nannan; Ye, Yushan

2018-03-01

The colorimetric characterization of the display can achieve the purpose of precisely controlling the color of the monitor. This paper describes an improved method for estimating the gamma value of liquid-crystal displays (LCDs) without using a measurement device was described by Xiao et al. It relies on observer's luminance matching by presenting eight half-tone patterns with luminance from 1/9 to 8/9 of the maximum value of each color channel. Since the previous method lacked partial low frequency information, we partially replaced the half-tone patterns. A large number of experiments show that the color difference is reduced from 3.726 to 2.835, and our half-tone pattern can better estimate the visual gamma value of LCDs.

Biochemical markers of bone turnover in children with clinical bone fragility.

PubMed

Bowden, Sasigarn A; Akusoba, Chiazor I; Hayes, John R; Mahan, John D

2016-06-01

The role of biochemical bone turnover markers (BTMs) in assessing low bone mass and monitoring bisphosphonate treatment in pediatric patients with clinical bone fragility is not well established. The aim of the study was to examine the correlations of BTMs and the bone mineral density (BMD), and evaluate the effects of bisphosphonates therapy on BTMs in children with clinical bone fragility. Clinical data of 115 patients with clinical bone fragility (mean age 9.7±5.8 years), 102 of whom received bisphosphonates, were studied. Serum alkaline phosphatase (ALP), osteocalcin (OC), urine pyridinoline (PD) and deoxypyridinoline (DPD), BMD at baseline and subsequent years were analyzed. There was a significant negative correlation between urine PD and lumbar BMD (slope=-0.29, p<0.001). There were no correlations between BTMs and lumbar BMD Z-score. There was a significant positive correlation between serum OC and serum ALP, urine PD and DPD (p<0.001). Serum OC, urine PD and DPD index, as expressed as measured value/upper limit of normal value for age, decreased during the first 3 years of bisphosphonate therapy. In children with clinical bone fragility, BTMs correlated with each other, but not with lumbar BMD Z-score. While they were not reliable predictors of degree of low BMD, the bone markers showed suppression during bisphosphonate therapy and may be helpful in monitoring the response to therapy.

Nab-Paclitaxel Plus S-1 Shows Increased Antitumor Activity in Patient-Derived Pancreatic Cancer Xenograft Mouse Models.

PubMed

Li, Jian-Ang; Xu, Xue-Feng; Han, Xu; Fang, Yuan; Shi, Chen-Ye; Jin, Da-Yong; Lou, Wen-Hui

2016-03-01

To investigate the antitumor activity of nanoparticle albumin-bound paclitaxel (nab-paclitaxel) plus S-1 in patient-derived pancreatic cancer xenograft mouse models and to explore biomarkers that could predict drug efficacy. Ten patient-derived xenograft models were established. The third-generation tumor-bearing mice were randomized into 4 treatment groups: (1) control; (2) S-1; (3) nab-paclitaxel; (4) S-1 plus nab-paclitaxel. Resected tumors were tested by immunohistochemistry for the expression of thymidylate synthase, orotate phosphoribosyltransferase (OPRT), dihydropyrimidine dehydrogenase (DPD), secreted protein that is acidic and rich in cysteine, human epidermal growth factor receptor 2 (HER2), collagen-1, and CD31. Tumor growth inhibition of the S-1 group, nab-paclitaxel group, and combination group was 69.52%, 86.63%, 103.56%, respectively (P < 0.05). The efficacy of S-1 is better in thymidylate synthase-negative, OPRT-positive, and DPD-negative tumors. The efficacy of nab-paclitaxel is better in HER2-positive tumors. Collagen-1 was decreased and CD31 was increased in tumors treated with nab-paclitaxel and S-1 plus nab-paclitaxel compared with control or S-1. This preclinical study showed that S-1 plus nab-paclitaxel exerted significantly better antitumor activity than S-1 or nab-paclitaxel alone. Thymidylate synthase, OPRT, and DPD were possibly biomarkers of S-1 and HER2 of nab-paclitaxel.

A new data format for the commissioning phase of the ATLAS detector

NASA Astrophysics Data System (ADS)

Köneke, Karsten; ATLAS Collaboration

2010-04-01

In the commissioning phase of the ATLAS experiment, low-level Event Summary Data (ESD) are analyzed to evaluate the performance of the individual subdetectors, the performance of the reconstruction and particle identification algorithms, and to obtain calibration coefficients. In the grid model of distributed analysis, these data must be transferred to Tier-1 and Tier-2 sites before they can be analyzed. However, the large size of ESD (approxeq1 MByte/event) constrains the amount of data that can be distributed on the grid and is available on disks. In order to overcome this constraint and make the data fully available, new data sets — collectively known as Derived Physics Data (DPD) — have been designed. Each DPD set contains a subset of the ESD data, tailored to specific needs of the subdetector and object reconstruction and identification performance groups. Filtering algorithms perform a selection based on physics contents and trigger response, further reducing the data volume. Thanks to these techniques, the total volume of DPD to be distributed on the grid amounts to 20% of the initial ESD data. An evolution of the tools developed in this context serves to produce another set of DPDs that are specifically tailored for physics analysis. All selection criteria and other relevant information is stored inside these DPDs as meta-data and a connection to external databases is also established.

Enzyme-free colorimetric detection systems based on the DNA strand displacement competition reaction

NASA Astrophysics Data System (ADS)

Zhang, Z.; Birkedal, V.; Gothelf, K. V.

2016-05-01

The strand displacement competition assay is based on the dynamic equilibrium of the competitive hybridization of two oligonucleotides (A and B) to a third oligonucleotide (S). In the presence of an analyte that binds to a specific affinity-moiety conjugated to strand B, the equilibrium shifts, which can be detected by a shift in the fluorescence resonance energy transfer signal between dyes attached to the DNA strands. In the present study we have integrated an ATP aptamer in the strand B and demonstrated the optical detection of ATP. Furthermore we explore a new readout method using a split G-quadruplex DNAzyme for colorimetric readout of the detection of streptavidin by the naked eye. Finally, we integrate the whole G-quadruplex DNAzyme system in a single DNA strand and show that it is applicable to colorimetric detection.

The Disassembly of a Core-Satellite Nanoassembled Substrate for Colorimetric Biomolecular Detection

PubMed Central

Waldeisen, John R.; Wang, Tim; Ross, Benjamin M.; Lee, Luke P.

2012-01-01

The disassembly of a core-satellite nanostructured substrate is presented as a colorimetric biosensor observable under dark field illumination. The fabrication method described herein utilizes thiol-mediated adsorption and streptavidin-biotin binding to self-assemble core-satellite nanostructures with a sacrificial linking peptide. Biosensing functionality is demonstrated with the protease trypsin and the optical properties of the nanoassemblies are characterized. A figure of merit is presented to determine the optimal core and satellite size for visual detection. Nanoassemblies with 50 nm cores and 30 nm or 50 nm satellites are superior as these structures achieve an orange to green color shift greater than 70 nm that is easily discernible by naked eye. This colorimetric substrate may prove to be a favorable alternative to liquid-based colloidal sensors and a useful visual readout mechanism for microfluidic diagnostic assays. PMID:21667984

Colour change evaluation on UV radiation exposure for Păun-Repedea calcareous geomaterial

NASA Astrophysics Data System (ADS)

Pelin, V.; Sandu, I.; Munteanu, M.; Iurcovschi, C. T.; Gurlui, S.; Sandu, AV; Vasilache, V.; Brȃnzilă, M.; Sandu, I. G.

2016-06-01

When talking about the preservation treatments that can be applied to natural stones used in different constructions, the surface hydrophobization plays an important part, especially when referring to porous surfaces like the calcareous oolithic stones specific to Repedea area, Iasi County, Romania. The present paper presents a method that evaluates the hydrophobization efficiency of two types of pellicles, involving UV artificial ageing and colorimetric analysis of the treated surfaces. The evaluation was done through continuous colorimetric monitoring and by comparing the evolution of the chromatic modifications of the two treated surfaces with the original colorimetric values and with the witness area, which was exposed to UV radiations under the same conditions, but left chemical untreated. The techniques used during this experiment were: CIE L*a*b* colorimetry, OM, SEM-EDX, UV radiation exposure and Spectrum Irradiance Measurement.

A colorimetric detection of acrylamide in potato chips based on nucleophile-initiated thiol-ene Michael addition.

PubMed

Hu, Qinqin; Fu, Yingchun; Xu, Xiahong; Qiao, Zhaohui; Wang, Ronghui; Zhang, Ying; Li, Yanbin

2016-02-07

Acrylamide (AA), a neurotoxin and a potential carcinogen, has been found in various thermally processed foods such as potato chips, biscuits, and coffee. Simple, cost-effective, and sensitive methods for the rapid detection of AA are needed to ensure food safety. Herein, a novel colorimetric method was proposed for the visual detection of AA based on a nucleophile-initiated thiol-ene Michael addition reaction. Gold nanoparticles (AuNPs) were aggregated by glutathione (GSH) because of a ligand-replacement, accompanied by a color change from red to purple. In the presence of AA, after the thiol-ene Michael addition reaction between GSH and AA with the catalysis of a nucleophile, the sulfhydryl group of GSH was consumed by AA, which hindered the subsequent ligand-replacement and the aggregation of AuNPs. Therefore, the concentration of AA could be determined by the visible color change caused by dispersion/aggregation of AuNPs. This new method showed high sensitivity with a linear range from 0.1 μmol L(-1) to 80 μmol L(-1) and a detection limit of 28.6 nmol L(-1), and especially revealed better selectivity than the fluorescence sensing method reported previously. Moreover, this new method was used to detect AA in potato chips with a satisfactory result in comparison with the standard methods based on chromatography, which indicated that the colorimetric method can be expanded for the rapid detection of AA in thermally processed foods.

A gas chromatography-mass spectrometry method for the determination of delta-aminolevulinic acid in plant leaves.

PubMed

Hijaz, Faraj; Killiny, Nabil

2016-05-20

Delta-aminolevulinic (δ-ALA) acid is an important intermediate for tetrapyrroles biosynthesis and it has recently received great attention in plant physiology and human toxicology. However, the colorimetric method which is the most common method for determination of δ-ALA is time consuming and is not specific. In this study, a method for determination of δ-ALA in plant tissues was developed based on the trimethylsilyl (TMS) derivative of the pyrrole formed from the reaction of δ-ALA with ethyl acetoacetate via Knorr condensation. The δ-ALA in the HCl extract was reacted with ethyl acetoacetate to form a pyrrole. Then, the pyrrole compound was extracted using ethyl acetate and the solvent was evaporated to dryness. The dried sample was derivatized to its TMS ester and analyzed using GC-MS. The concentration of δ-ALA in citrus leaves incubated with levulinic acid was also determined by the conventional colorimetric method. The linear range was 10-200ppm in the full scan mode and 0.1-20ppm in the selected ion monitoring (SIM). The limit of detection was 6ppm in the full scan and 0.05ppm in SIM mode, representing a four-fold increase in sensitivity compared to the colorimetric method. The GC-MS method developed in this study is simple, accurate, sensitive, and could also be used to measure δ-ALA in other biological samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Blue emitting copper nanoclusters as colorimetric and fluorescent probe for the selective detection of bilirubin

NASA Astrophysics Data System (ADS)

R. S., Aparna; J. S., Anjali Devi; John, Nebu; Abha, K.; S. S., Syamchand; George, Sony

2018-06-01

Hurdles to develop point of care diagnostic methods restrict the translation of progress in the health care sector from bench side to bedside. In this article a simple, cost effective fluorescent as well as colorimetric nanosensor was developed for the early and easy detection of hyperbilirubinemia. A stable, water soluble bovine serum albumin stabilised copper nanocluster (BSA CuNC) was used as the fluorescent probe which exhibited strong blue emission (404 nm) upon 330 nm excitation. The fluorescence of the BSA CuNC can be effectively quenched by the addition of bilirubin by the formation of copper-bilirubin complex. Meanwhile the copper-bilirubin complex resulted in an observable colour change from pale violet to green facilitating colorimetric detection. The prepared sensor displayed good selectivity and sensitivity over other co-existing molecules, and can be used for quantifying bilirubin with a detection limit down to 257 fM. Additionally, the as-prepared probe was coated on a paper strip to develop a portable paper strip sensor of bilirubin. Moreover, the method was successfully applied in real sample analysis and obtained promising result.

Poly(acrylic acid)-templated silver nanoclusters as a platform for dual fluorometric turn-on and colorimetric detection of mercury (II) ions.

PubMed

Tao, Yu; Lin, Youhui; Huang, Zhenzhen; Ren, Jinsong; Qu, Xiaogang

2012-01-15

An easy prepared fluorescence turn-on and colorimetric dual channel probe was developed for rapid assay of Hg(2+) ions with high sensitivity and selectivity by using poly(acrylic acid)-templated silver nanoclusters (PAA-AgNCs). The PAA-AgNCs exhibited weak fluorescence, while upon the addition of Hg(2+) ions, AgNCs gives a dramatic increase in fluorescence as a result of the changes of the AgNCs states. The detection limit was estimated to be 2 nM, which is much lower than the Hg(2+) detection requirement for drinking water of U.S. Environmental Protection Agency, and the turn-on sensing mode offers additional advantage to efficiently reduce background noise. Also, a colorimetric assay of Hg(2+) ions can be realized due to the observed absorbance changes of the AgNCs. More importantly, the method was successfully applied to the determination of Hg(2+) ions in real water samples, which suggests our proposed method has a great potential of application in environmental monitoring. Copyright © 2011 Elsevier B.V. All rights reserved.

Improving colorimetric assays through protein enzyme-assisted gold nanoparticle amplification.

PubMed

Xie, Xiaoji; Xu, Wei; Liu, Xiaogang

2012-09-18

The discovery of the DNA-mediated assembly of gold nanoparticles was a great moment in the history of science; this understanding and chemical control enabled the rational design of functional nanomaterials as novel probes in biodetection. In contrast with conventional probes such as organic dyes, gold nanoparticles exhibit high photostability and unique size-dependent optical properties. Because of their high extinction coefficients and strong distance dependent optical properties, these nanoparticles have emerged over the past decade as a promising platform for rapid, highly sensitive colorimetric assays that allow for the visual detection of low concentrations of metal ions, small molecules, and biomacromolecules. These discoveries have deepened our knowledge of biological phenomena and facilitated the development of many new diagnostic and therapeutic tools. Despite these many advances and continued research efforts, current nanoparticle-based colorimetric detection systems still suffer from several drawbacks, such as limited sensitivity and selectivity. This Account describes the recent development of colorimetric assays based on protein enzyme-assisted gold nanoparticle amplification. The benefits of such detection systems include significantly improved detection sensitivity and selectivity. First, we discuss the general design of enzyme-modified nanoparticle systems in colorimetric assays. We show that a quantitative understanding of the unique properties of different enzymes is paramount for effective biological assays. We then examine the assays for nucleic acid detection based on different types of enzymes, including endonucleases, ligases, and polymerases. For each of these assays, we identify the underlying principles that contribute to the enhanced detection capability of nanoparticle systems and illustrate them with selected examples. Furthermore, we demonstrate that the combination of gold nanoparticles and specific enzymes can probe enzyme dynamics and function with high specificity, offering substantial advantages in both sensitivity and specificity over conventional detection methods. The screening of nuclease, methyltransferase, protease, and kinase activities can be colorimetrically performed in a straightforward manner. Finally, we discuss examples of colorimetric assays for metal ions and small molecules that constitute important advances toward visual monitoring of enzyme catalytic functions and gene expression. Although these enzyme-assisted assay methods hold great promise for myriad applications in biomedicine and bioimaging, the application of the described techniques in vivo faces formidable challenges. In addition, researchers do not fully understand the interactions of gold nanoparticles with enzyme molecules. This understanding will require the development of new techniques to probe enzyme substrate dynamics at the particle interface with higher spatial resolution and chemical specificity.

Ultrasensitive colorimetric immunoassay for hCG detection based on dual catalysis of Au@Pt core-shell nanoparticle functionalized by horseradish peroxidase

NASA Astrophysics Data System (ADS)

Wang, Weiguo; Zou, Yake; Yan, Jinwu; Liu, Jing; Chen, Huixiong; Li, Shan; Zhang, Lei

2018-03-01

In this paper, an ultrasensitive colorimetric biosensor for human chorionic gonadotrophin (hCG) detection was designed from bottom-up method based on the dual catalysis of the horseradish peroxidase (HRP) and Au@Pt nanoparticles (NPs) relative to H2O2-TEM system. HRP and monoclonal mouse anti-hCG antibody (β-submit, mAb1) were co-immobilized onto the Au@Pt NP surface to improve catalytic efficiency and specificity, which formed a dual functionalized Au@Pt-HRP probe with the mean size of 42.8 nm (D50). The colorimetric immunoassay was developed for the hCG detection, and the Au@Pt-HRP probe featured a higher sensitivity in the concentration range of 0.4-12.8 IU L- 1 with a low limit of detection (LOD) of 0.1 IU L- 1 compared with the LODs of 0.8 IU L- 1 for BA-ELISA and of 2.0 IU L- 1 for Au@Pt, which indicated that the Au@Pt-HRP probe possessed higher catalytic efficiency with 2.8-fold increase over Au@Pt and 33.8-fold increase over HRP. Also, the Au@Pt-HRP probe exhibited good precision and reproducibility, high specificity and acceptable accuracy with CV being less than 15%. The dual functionalized Au@Pt-HRP probe as a type of signal amplified method was firstly applied in the colorimetric immunoassay for the hCG detection.

Longitudinal Study of Hepatitis A Infection by Saliva Sampling: The Kinetics of HAV Markers in Saliva Revealed the Application of Saliva Tests for Hepatitis A Study.

PubMed

Amado Leon, Luciane Almeida; de Almeida, Adilson José; de Paula, Vanessa Salete; Tourinho, Renata Santos; Villela, Daniel Antunes Maciel; Gaspar, Ana Maria Coimbra; Lewis-Ximenez, Lia Laura; Pinto, Marcelo Alves

2015-01-01

Despite the increasing numbers of studies investigating hepatitis A diagnostic through saliva, the frequency and the pattern of hepatitis A virus (HAV) markers in this fluid still remains unknown. To address this issue, we carried on a longitudinal study to examine the kinetics of HAV markers in saliva, in comparison with serum samples. The present study followed-up ten patients with acute hepatitis A infection during 180 days post diagnosis (dpd). Total anti-HAV was detected in paired serum and saliva samples until the end of the follow-up, showing a peak titer at 90th. However, total anti-HAV level was higher in serum than in saliva samples. This HAV marker showed a probability of 100% to be detected in both serum and saliva during 180 dpd. The IgM anti-HAV could be detected in saliva up to 150 dpd, showing the highest frequency at 30th, when it was detected in all individuals. During the first month of HAV infection, this acute HAV marker showed a detection probability of 100% in paired samples. The detection of IgM anti-HAV in saliva was not dependent on its level in serum, HAV-RNA detection and/or viral load, since no association was found between IgM anti-HAV positivity in saliva and any of these parameter (p>0.05). Most of the patients (80%) were found to contain HAV-RNA in saliva, mainly at early acute phase (30th day). However, it was possible to demonstrate the HAV RNA presence in paired samples for more than 90 days, even after seroconversion. No significant relationship was observed between salivary HAV-RNA positivity and serum viral load, demonstrating that serum viral load is not predictive of HAV-RNA detection in saliva. Similar viral load was seen in paired samples (on average 104 copies/mL). These data demonstrate that the best diagnostic coverage can be achieved by salivary anti-HAV antibodies and HAV-RNA tests during 30-90 dpd. The long detection and high probability of specific-HAV antibodies positivity in saliva samples make the assessment of salivary antibodies a useful tool for diagnosis and epidemiological studies. The high frequency of HAV-RNA in saliva and the probability of detection of about 50%, during the first 30 dpd, demonstrate that saliva is also useful for molecular investigation of hepatitis A cases, mainly during the early course of infection. Therefore, the collection of saliva may provide a simple, cheap and non-invasive means of diagnosis, epidemiological surveys and monitoring of hepatitis A infection purposes.

Longitudinal Study of Hepatitis A Infection by Saliva Sampling: The Kinetics of HAV Markers in Saliva Revealed the Application of Saliva Tests for Hepatitis A Study

PubMed Central

Amado Leon, Luciane Almeida; de Almeida, Adilson José; de Paula, Vanessa Salete; Tourinho, Renata Santos; Villela, Daniel Antunes Maciel; Gaspar, Ana Maria Coimbra; Lewis-Ximenez, Lia Laura; Pinto, Marcelo Alves

2015-01-01

Despite the increasing numbers of studies investigating hepatitis A diagnostic through saliva, the frequency and the pattern of hepatitis A virus (HAV) markers in this fluid still remains unknown. To address this issue, we carried on a longitudinal study to examine the kinetics of HAV markers in saliva, in comparison with serum samples. The present study followed-up ten patients with acute hepatitis A infection during 180 days post diagnosis (dpd). Total anti-HAV was detected in paired serum and saliva samples until the end of the follow-up, showing a peak titer at 90th. However, total anti-HAV level was higher in serum than in saliva samples. This HAV marker showed a probability of 100% to be detected in both serum and saliva during 180 dpd. The IgM anti-HAV could be detected in saliva up to 150 dpd, showing the highest frequency at 30th, when it was detected in all individuals. During the first month of HAV infection, this acute HAV marker showed a detection probability of 100% in paired samples. The detection of IgM anti-HAV in saliva was not dependent on its level in serum, HAV-RNA detection and/or viral load, since no association was found between IgM anti-HAV positivity in saliva and any of these parameter (p>0.05). Most of the patients (80%) were found to contain HAV-RNA in saliva, mainly at early acute phase (30th day). However, it was possible to demonstrate the HAV RNA presence in paired samples for more than 90 days, even after seroconversion. No significant relationship was observed between salivary HAV-RNA positivity and serum viral load, demonstrating that serum viral load is not predictive of HAV-RNA detection in saliva. Similar viral load was seen in paired samples (on average 104 copies/mL). These data demonstrate that the best diagnostic coverage can be achieved by salivary anti-HAV antibodies and HAV-RNA tests during 30–90 dpd. The long detection and high probability of specific-HAV antibodies positivity in saliva samples make the assessment of salivary antibodies a useful tool for diagnosis and epidemiological studies. The high frequency of HAV-RNA in saliva and the probability of detection of about 50%, during the first 30 dpd, demonstrate that saliva is also useful for molecular investigation of hepatitis A cases, mainly during the early course of infection. Therefore, the collection of saliva may provide a simple, cheap and non-invasive means of diagnosis, epidemiological surveys and monitoring of hepatitis A infection purposes. PMID:26690904

Optical and Electrochemical Aptasensors for Sensitive Detection of Streptomycin in Blood Serum and Milk.

PubMed

Ramezani, Mohammad; Abnous, Khalil; Taghdisi, Seyed Mohammad

2017-01-01

Detection and quantitation of antibiotic residues in blood serum and foodstuffs are in great demand. We have developed aptasensors for detection of streptomycin using electrochemical and optical methods. In the first method, an electrochemical aptasensor was developed for sensitive and selective detection of streptomycin, based on combination of exonuclease I (Exo I), complementary strand of aptamer (CS), arch shaped structure of aptamer (Apt)-CS conjugate, and gold electrode. The designed electrochemical aptasensor exhibited high selectivity toward streptomycin with a limit of detection (LOD) as low as 11.4 nM. Moreover, the developed electrochemical aptasensor was successfully used to detect streptomycin in milk and serum with LODs of 14.1 and 15.3 nM, respectively. In the second method, fluorescence quenching and colorimetric aptasensors were designed for detection of streptomycin based on aqueous gold nanoparticles (AuNPs) and double-stranded DNA (dsDNA). In the absence of streptomycin, aptamer/FAM-labeled complementary strand dsDNA is stable, resulting in the aggregation of AuNPs by salt bridge and an obvious color change from red to blue and strong emission of fluorescence. The colorimetric and fluorescence quenching aptasensors showed excellent selectivity toward streptomycin with limit of detections as low as 73.1 and 47.6 nM, respectively. The presented aptasensors were successfully used to detect streptomycin in milk and serum. For serum, LODs were determined to be 58.2 and 102.4 nM for fluorescence quenching and colorimetric aptasensors, respectively. For milk, LODs were calculated to be 56.2 and 108.7 nM for fluorescence quenching and colorimetric aptasensors, respectively.

Dual-responsive immunosensor that combines colorimetric recognition and electrochemical response for ultrasensitive detection of cancer biomarkers.

PubMed

Hong, Wooyoung; Lee, Sooyeon; Cho, Youngnam

2016-12-15

We developed a nanoroughened, biotin-doped polypyrrole immunosensor for the detection of tumor markers through dual-signal (electrochemical and colorimetric) channels, electrochemical and colorimetric, that demonstrates remarkable analytical performance. A rapid, one-step electric field-mediated method was employed to fabricate the immunosensor with nanoscale roughness by simply modulating the applied electrical potential. We demonstrated the successful detection of three tumor markers (CA125, CEA, and PSA) via the double enzymatic signal amplifications in the presence of a target antigen, ultimately leading to desired diagnostic accuracy and reliability. The addition of multiple horseradish peroxidase (HRP)- and antibody-labeled nanoparticles greatly amplified the signal and simplified the measurement of cancer biomarker proteins by sequentially magnifying electrochemical and colorimetric signals in a single platform. The two parallel assays performed using the proposed immunosensor have yielded highly consistent and reproducible results. Additionally, for the analysis of plasma samples in a clinical setting, the values obtained with our immunosensor were validated by correlating the results with those of a standard radioimmunoassay (RIA), which obtained very similar clinically valid responses. Copyright © 2016 Elsevier B.V. All rights reserved.

CHEMICAL METHODS FOR THE DETERMINATION OF BORON IN REACTOR MATERIALS. PART I. ION-EXCHANGE SEPARATION OF BORON FROM COKES, PITCHES AND GRAPHITES AND ITS COLORIMETRIC DETERMINATION BY THE CURCUMIN-TRI-CHLORACETIC ACID METHOD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Desai, H.B.; Desai, S.R.; Nadkarni, M.N.

1961-01-01

A procedure has been standardized for the determination of boron in cokes, pitches, and graphites. The method consists of fixing the boron present in the sample as calcium borate, ion-exchange separation of boric acid from the associated cations, and the colorimetric determination of boron using the curcumin-trichloracetic acid method. Sulfur which is usually present in pitches and cokes is expected to be oxidized to sulfate during the fixation of boron and hence its effect on the colorimetry has been studied. Application of the procedure to the determination of 0.50 and 1.00 microgram amounts of boron, has given coefficients of variationmore » of l0.0 and 6.7% respectively. (auth)« less

Evaluation of a colorimetric reagent strip assay for urine specific gravity.

PubMed

Kirschbaum, B B

1983-06-01

N-Multistix SG provides a convenient colorimetric assay for the determination of the specific gravity (sp. gr.) of freshly voided urine. When compared with results obtained by standard hydrometry, the colorimetric assay sp. gr. was observed to decrease by as much as 0.010 units as urine pH increased from 5 to 7. Moderate levels of proteinuria that did not alter hydrometer readings effectively raised the colorimetric sp. gr. by 0.005-0.010 units. The colorimetric assay was almost completely insensitive to clinically encountered concentrations of glucose and urea but responded appropriately to monovalent salts. The magnitude of these observed discrepancies places serious limitations on the value of the colorimetric sp. gr. measurement.

Pitfalls in the detection of cholesterol in Huntington’s disease models

PubMed Central

Marullo, Manuela; Valenza, Marta; Leoni, Valerio; Caccia, Claudio; Scarlatti, Chiara; De Mario, Agnese; Zuccato, Chiara; Di Donato, Stefano; Carafoli, Ernesto; Cattaneo, Elena

2012-01-01

Background Abnormalities in brain cholesterol homeostasis have been reported in Huntington’s disease (HD), an adult-onset neurodegenerative disorder caused by an expansion in the number of CAG repeats in the huntingtin (HTT) gene. However, the results have been contradictory with respect to whether cholesterol levels increase or decrease in HD models. Biochemical and mass spectrometry methods show reduced levels of cholesterol precursors and cholesterol in HD cells and in the brains of several HD animal models. Abnormal brain cholesterol homeostasis was also inferred from studies in HD patients. In contrast, colorimetric and enzymatic methods indicate cholesterol accumulation in HD cells and tissues. Here we used several methods to investigate cholesterol levels in cultured cells in the presence or absence of mutant HTT protein. Results Colorimetric and enzymatic methods with low sensitivity gave variable results, whereas results from a sensitive analytical method, gas chromatography-mass spectrometry, were more reliable. Sample preparation, high cell density and cell clonality also influenced the detection of intracellular cholesterol. Conclusions Detection of cholesterol in HD samples by colorimetric and enzymatic assays should be supplemented by detection using more sensitive analytical methods. Care must be taken to prepare the sample appropriately. By evaluating lathosterol levels using isotopic dilution mass spectrometry, we confirmed reduced cholesterol biosynthesis in knock-in cells expressing the polyQ mutation in a constitutive or inducible manner. *Correspondence should be addressed to Elena Cattaneo: elena.cattaneo@unimi.it PMID:23145355

Real-time monitoring of enzyme-free strand displacement cascades by colorimetric assays.

PubMed

Duan, Ruixue; Wang, Boya; Hong, Fan; Zhang, Tianchi; Jia, Yongmei; Huang, Jiayu; Hakeem, Abdul; Liu, Nannan; Lou, Xiaoding; Xia, Fan

2015-03-19

The enzyme-free toehold-mediated strand displacement reaction has shown potential for building programmable DNA circuits, biosensors, molecular machines and chemical reaction networks. Here we report a simple colorimetric method using gold nanoparticles as signal generators for the real-time detection of the product of the strand displacement cascade. During the process the assembled gold nanoparticles can be separated, resulting in a color change of the solution. This assay can also be applied in complex mixtures, fetal bovine serum, and to detect single-base mismatches. These results suggest that this method could be of general utility to monitor more complex enzyme-free strand displacement reaction-based programmable systems or for further low-cost diagnostic applications.

Colorimetric protein determination in microalgae (Chlorophyta): association of milling and SDS treatment for total protein extraction.

PubMed

Mota, Maria Fernanda S; Souza, Marcella F; Bon, Elba P S; Rodrigues, Marcoaurelio A; Freitas, Suely Pereira

2018-05-24

The use of colorimetric methods for protein quantification in microalgae is hindered by their elevated amounts of membrane-embedded intracellular proteins. In this work, the protein content of three species of microalgae was determined by the Lowry method after the cells were dried, ball-milled, and treated with the detergent sodium dodecyl sulfate (SDS). Results demonstrated that the association of milling and SDS treatment resulted in a 3- to 7-fold increase in protein quantification. Milling promoted microalgal disaggregation and cell wall disruption enabling access of the SDS detergent to the microalgal intracellular membrane proteins and their efficient solubilization and quantification. © 2018 Phycological Society of America.

Modeling and Bio molecular Self-assembly via Molecular Dynamics and Dissipative Particle Dynamics

NASA Astrophysics Data System (ADS)

Rakesh, L.

2009-09-01

Surfactants like materials can be used to increase the solubility of poorly soluble drugs in water and to increase drug bioavailability. A typical case study will be demonstrated using DPD simulation to model the distribution of anti-inflammatory drug molecules. Computer simulation is a convenient approach to understand drug distribution and solubility concepts without much wastage and costly experiments in the laboratory. Often in molecular dynamics (MD) the atoms are represented explicitly and the equation of motion as described by Newtonian dynamics is integrated explicitly. MD has been used to study spontaneous formation of micelles by hydrophobic molecules with amphiphilic head groups in bulk water, as well as stability of pre-configured micelles and membranes. DPD is a state-of the- art mesoscale simulation, it is a more recent molecular dynamics technique, originally developed for simulating complex fluids but lately also applied to membrane dynamics, hemodynamic in biomedical applications. Such fluids pervade industrial research from paints to pharmaceuticals and from cosmetics to the controlled release of drugs. Dissipative particle dynamics (DPD) can provide structural and dynamic properties of fluids in equilibrium, under shear or confined to narrow cavities, at length- and time-scales beyond the scope of traditional atomistic molecular dynamics simulation methods. Mesoscopic particles are used to represent clusters of molecules. The interaction conserves mass and momentum and as a consequence the dynamics is consistent with Navier-Stokes equations. In addition to the conservative forces, stochastic drive and dissipation is introduced to represent internal degrees of freedom in the mesoscopic particles. In this research, an initial study is being conducted using the aqueous solubilization of the nonsteroidal, anti-inflammatory drug is studied theoretically in micellar solution of nonionic (dodecyl hexa(ethylene oxide), C12E6) surfactants possessing the hydrocarbon "tail" and their hydrophilic head groups. We find that, for the surfactants, the aqueous solubility of anti-inflammatory molecules increases linearly with increasing surfactant concentration. In particular, we observed a 10-fold increase in the solubility of anti-inflammatory drugs relative to that in the aqueous buffer upon the addition of 100 mM dodecyltrimethyl ammonium bromide -DTAB.

Accuracy, Precision, Ease-Of-Use, and Cost of Methods to Test Ebola-Relevant Chlorine Solutions

PubMed Central

Wells, Emma; Wolfe, Marlene K.; Murray, Anna; Lantagne, Daniele

2016-01-01

To prevent transmission in Ebola Virus Disease (EVD) outbreaks, it is recommended to disinfect living things (hands and people) with 0.05% chlorine solution and non-living things (surfaces, personal protective equipment, dead bodies) with 0.5% chlorine solution. In the current West African EVD outbreak, these solutions (manufactured from calcium hypochlorite (HTH), sodium dichloroisocyanurate (NaDCC), and sodium hypochlorite (NaOCl)) have been widely used in both Ebola Treatment Unit and community settings. To ensure solution quality, testing is necessary, however test method appropriateness for these Ebola-relevant concentrations has not previously been evaluated. We identified fourteen commercially-available methods to test Ebola-relevant chlorine solution concentrations, including two titration methods, four DPD dilution methods, and six test strips. We assessed these methods by: 1) determining accuracy and precision by measuring in quintuplicate five different 0.05% and 0.5% chlorine solutions manufactured from NaDCC, HTH, and NaOCl; 2) conducting volunteer testing to assess ease-of-use; and, 3) determining costs. Accuracy was greatest in titration methods (reference-12.4% error compared to reference method), then DPD dilution methods (2.4–19% error), then test strips (5.2–48% error); precision followed this same trend. Two methods had an accuracy of <10% error across all five chlorine solutions with good precision: Hach digital titration for 0.05% and 0.5% solutions (recommended for contexts with trained personnel and financial resources), and Serim test strips for 0.05% solutions (recommended for contexts where rapid, inexpensive, and low-training burden testing is needed). Measurement error from test methods not including pH adjustment varied significantly across the five chlorine solutions, which had pH values 5–11. Volunteers found test strip easiest and titration hardest; costs per 100 tests were $14–37 for test strips and $33–609 for titration. Given the ease-of-use and cost benefits of test strips, we recommend further development of test strips robust to pH variation and appropriate for Ebola-relevant chlorine solution concentrations. PMID:27243817

Plasmon-Based Colorimetric Nanosensors for Ultrasensitive Molecular Diagnostics.

PubMed

Tang, Longhua; Li, Jinghong

2017-07-28

Colorimetric detection of target analytes with high specificity and sensitivity is of fundamental importance to clinical and personalized point-of-care diagnostics. Because of their extraordinary optical properties, plasmonic nanomaterials have been introduced into colorimetric sensing systems, which provide significantly improved sensitivity in various biosensing applications. Here we review the recent progress on these plasmonic nanoparticles-based colorimetric nanosensors for ultrasensitive molecular diagnostics. According to their different colorimetric signal generation mechanisms, these plasmonic nanosensors are classified into two categories: (1) interparticle distance-dependent colorimetric assay based on target-induced forming cross-linking assembly/aggregate of plasmonic nanoparticles; and (2) size/morphology-dependent colorimetric assay by target-controlled growth/etching of the plasmonic nanoparticles. The sensing fundamentals and cutting-edge applications will be provided for each of them, particularly focusing on signal generation and/or amplification mechanisms that realize ultrasensitive molecular detection. Finally, we also discuss the challenge and give our future perspective in this emerging field.

Design of a dual-function peptide probe as a binder of angiotensin II and an inducer of silver nanoparticle aggregation for use in label-free colorimetric assays.

PubMed

Okochi, Mina; Kuboyama, Masashi; Tanaka, Masayoshi; Honda, Hiroyuki

2015-09-01

Label-free colorimetric assays using metallic nanoparticles have received much recent attention, for their application in simple and sensitive methods for detection of biomolecules. Short peptide probes that can bind to analyte biomolecules are attractive ligands in molecular nanotechnology; however, identification of biological recognition motifs is usually based on trial-and-error experiments. Herein, a peptide probe was screened for colorimetric detection of angiotensin II (Ang II) using a mechanism for non-crosslinking aggregation of silver nanoparticles (AgNPs). The dual-function peptides, which bind to the analyte and induce AgNP aggregation, were identified using a two-step strategy: (1) screening of an Ang II-binding peptide from an Ang II receptor sequence library, using SPOT technology, which enable peptides synthesis on cellulose membranes via an Fmoc method and (2) selection of peptide probes that effectively induce aggregation of AgNPs using a photolinker modified peptide array. Using the identified peptide probe, KGKNKRRR, aggregation of AgNPs was detected by observation of a pink color in the absence of Ang II, whereas AgNPs remained dispersed in the presence of Ang II (yellow). The color changes were not observed in the presence of other hormone molecules. Ang II could be detected within 15 min, with a detection limit of 10 µM, by measuring the ratio of absorbance at 400 nm and 568 nm; the signal could also be observed with the naked eye. These data suggest that the peptide identified here could be used as a probe for simple and rapid colorimetric detection of Ang II. This strategy for the identification of functional peptides shows promise for the development of colorimetric detection of various diagnostically important biomolecules. Copyright © 2015 Elsevier B.V. All rights reserved.

Bio-inspired colorimetric film based on hygroscopic coloration of longhorn beetles (Tmesisternus isabellae)

PubMed Central

Seo, Han-bok; Lee, Seung-Yop

2017-01-01

Structure-dependent colour is caused by the interaction of light with photonic crystal structures rather than pigments. The elytra of longhorn beetles Tmesisternus isabellae appear to be iridescent green in a dry state and turn to red when exposed to humidity. Based on the hygroscopic colouration of the longhorn beetle, we have developed centimeter-scale colorimetric opal films using a novel self-assembly method. The micro-channel assisted assembly technique adopts both natural evaporation and rotational forced drying, enhancing the surface binding of silica particles and the packing density by reducing the lattice constant and structural defects. The fabricated large-scale photonic film changes its structural colour from green to red when exposed to water vapour, similarly to the colorimetric feature of the longhorn beetle. The humidity-dependent colour change of the opal film is shown to be reversible and durable over five-hundred cycles of wetting and drying. PMID:28322307

Bio-inspired colorimetric film based on hygroscopic coloration of longhorn beetles (Tmesisternus isabellae)

NASA Astrophysics Data System (ADS)

Seo, Han-Bok; Lee, Seung-Yop

2017-03-01

Structure-dependent colour is caused by the interaction of light with photonic crystal structures rather than pigments. The elytra of longhorn beetles Tmesisternus isabellae appear to be iridescent green in a dry state and turn to red when exposed to humidity. Based on the hygroscopic colouration of the longhorn beetle, we have developed centimeter-scale colorimetric opal films using a novel self-assembly method. The micro-channel assisted assembly technique adopts both natural evaporation and rotational forced drying, enhancing the surface binding of silica particles and the packing density by reducing the lattice constant and structural defects. The fabricated large-scale photonic film changes its structural colour from green to red when exposed to water vapour, similarly to the colorimetric feature of the longhorn beetle. The humidity-dependent colour change of the opal film is shown to be reversible and durable over five-hundred cycles of wetting and drying.

GAMMA AND X-RAY DOSIMETER AND DOSIMETRIC METHOD

DOEpatents

Taplin, G.V.; Douglas, C.H.; Sigoloff, S.C.

1958-08-19

An improvement in colorimetric gamma and x-ray dosimeter systems and a self-contained. hand carried dostmeter of the afore-mentioned type ts described. A novel point of the invention ltes in the addition of specific quantities of certain normalizing agents to the two phase chlorinated hydro-carbon-aqueous dyc colortmetric dosimeter to eliminate the after reaction and thereby extend the utility of such systein. The structure of the two phase colorimetric dosimeter tubes and the carrying case for the tubes of the portable dosimeter are unique features.

Label-free detection of specific DNA sequence-telomere using unmodified gold nanoparticles as colorimetric probes

NASA Astrophysics Data System (ADS)

Qi, Yingying; Li, Li; Li, Baoxin

2009-09-01

A simple and sensitive label-free colorimetric detection of telomere DNA has been developed. It was based on the color change of gold nanoparticles (AuNPs) due to DNA hybridization. UV-vis spectra and transmission electron microscopy (TEM) were used to investigate the change of AuNPs. Under the optimized conditions, the linear range for determination of telomere DNA was 5.7 × 10 -13 to 4.5 × 10 -6 mol/L. The detection limit (3 σ) of this method has decreased to pico-molar level.

Considerations for point-of-care diagnostics: evaluation of acridine orange staining and postprocessing methods for a three-part leukocyte differential test

NASA Astrophysics Data System (ADS)

Powless, Amy J.; Conley, Roxanna J.; Freeman, Karan A.; Muldoon, Timothy J.

2017-03-01

There exists a broad range of techniques that can be used to classify and count white blood cells in a point-of-care (POC) three-part leukocyte differential test. Improvements in lenses, light sources, and cameras for image-based POC systems have renewed interest in acridine orange (AO) as a contrast agent, whereby subpopulations of leukocytes can be differentiated by colorimetric analysis of AO fluorescence emission. We evaluated the effect on test accuracy using different AO staining and postprocessing methods in the context of an image-based POC colorimetric cell classification scheme. Thirty blood specimens were measured for percent cell counts using our POC system and a conventional hematology analyzer for comparison. Controlling the AO concentration used during whole-blood staining, the incubation time with AO, and the colorimetric ratios among the three population of leukocytes yielded a percent deviation of 0.706%, -1.534%, and -0.645% for the lymphocytes, monocytes, and granulocytes, respectively. Overall, we demonstrated that a redshift in AO fluorescence was observed at elevated AO concentrations, which lead to reproducible inaccuracy of cell counts. This study demonstrates there is a need for a strict control of the AO staining and postprocessing methods to improve test accuracy in these POC systems.

Colorimetric determination of sildenafil citrate (Viagra) through ion-associate complex formation.

PubMed

Amin, Alaa S; Moustafa, Moustafa E; El-Dosoky, Reham

2009-01-01

A simple, quick, accurate, and sensitive colorimetric method is described for the determination of sildenafil citrate (SLD). The method is based on the reaction of SLD with Congo Red, Sudan II, and Gentian Violet in buffered aqueous solutions at pH 2.5, 6.5, and 11.0, respectively, to give highly colored soluble ion-associate complex species; the colored products are quantitated colorimetrically at 523, 554, and 569 nm, respectively. The various experimental conditions were optimized. The stoichiometric ratio was found to be 1:1 for all ion associates; the calculated logarithmic stability constants were 8.51, 7.79, and 5.58, respectively. Beer's law was obeyed over the concentration range of 0.2-7.0 microg/mL, whereas the Ringbom optimum concentration range was 0.4-6.5 microg/mL. Values for molar absorptivity, Sandell sensitivity, and detection and quantification limits were also calculated. The proposed method was successfully applied to the determination of SLD in Viagra tablets and in serum samples by using the technique of standard additions with mean accuracy values of 100.06 +/- 1.14, 99.87 +/- 0.70, and 99.86 +/- 0.97% for Viagra tablets and 99.88 +/- 0.60, 99.90 +/- 0.90, and 100.24 +/- 0.80% for serum samples, respectively.

Novel colorimetric method overcoming phosphorus interference during trace arsenic analysis in soil solution.

PubMed

Makris, Konstantinos C; Punamiya, Pravin; Sarkar, Dibyendu; Datta, Rupali

2008-02-01

A sensitive (method detection limit, 2.0 microg As L(-1)) colorimetric determination of trace As(v) and As(iii) concentrations in the presence of soluble phosphorus (P) concentrations in soil/water extracts is presented. The proposed method modifies the malachite green method (MG) originally developed for P in soil and water. Our method relies upon the finding that As(iii) and As(v) do not develop the green color during P analysis using the MG method. When an optimum concentration of ascorbic acid (AA) is added to a sample containing up to 15 times P > As (microM) concentrations, the final sample absorbance due to P will be equal to that of As(v) molecules. The soluble As concentration can then be quantified by the concentration difference between the mixed oxyanion (As + P) absorbance (proposed method) and the MG method absorbance that measures only P. Our method is miniaturized using a 96-well microplate UV-VIS reader that utilizes minute reagent and sample volumes (120 and 200 microL sample(-1), respectively), thus, minimizing waste and offering flexibility in the field. Our method was tested in a suite of As-contaminated soils that successfully measured both As and P in soil water extracts and total digests. Mean% As recoveries ranged between 84 and 117%, corroborating data obtained with high-resolution inductively-coupled plasma mass-spectrometry. The performance of the proposed colorimetric As method was unaffected by the presence of Cu, Zn, Pb, Ni, Fe, Al, Si, and Cr in both neutral and highly-acidic (ca. pH 2) soil extracts. Data from this study provide the proof of concept towards creating a field-deployable, portable As kit.

Movement patterns of peak-dose levodopa-induced dyskinesias in patients with Parkinson's disease.

PubMed

Gour, Jackie; Edwards, Roderick; Lemieux, Sarah; Ghassemi, Mehrdad; Jog, Mandar; Duval, Christian

2007-09-14

The present study characterized involuntary movements associated with levodopa-induced dyskinesias (LID) in patients with Parkinson's disease. We used amplitude, proportional energy, frequency dispersion and sample entropy to determine whether LID movement patterns are truly random, as clinical description seems to suggest, or possess some underlying pattern that is not visible to the naked eye. LID was captured using a magnetic tracker system, which provided 3D rendering of whole-body LID. Patients were instructed to maintain a standing position, with arms extended in front of them. We compared the measurements of the dyskinetic PD group (DPD) with 10 patients without dyskinesias (NDPD) and 10 control subjects. In comparison to the other two groups, movement patterns from the DPD group had significantly higher amplitude, confirming the presence of dyskinesias. In addition, higher frequency components in the power spectrum of velocity were detected, suggestive of higher velocity in LID movement. Furthermore, there was a concentration in narrow frequency bands, which suggested stable oscillatory activity. Finally, sample entropy revealed more regularity in the DPD group. Although not statistically significant, we found that the amplitude from the NDPD group had a tendency to be smaller than those of controls. As well, the spectra were often more dispersed for the NDPD group. In conclusion, the present results suggest that LID cannot be considered as purely random movement since they possess some deterministic pattern of motion. This may provide a way for patients to adapt to these involuntary movements while performing voluntary motor acts.

RbsB (NTHI_0632) mediates quorum signal uptake in nontypeable Haemophilus influenzae strain 86-028NP

PubMed Central

Armbruster, Chelsie E.; Pang, Bing; Murrah, Kyle; Juneau, Richard A.; Perez, Antonia C.; Weimer, Kristin E.D.; Swords, W. Edward

2011-01-01

Summary Nontypeable Haemophilus influenzae (NTHI) is a respiratory commensal and opportunistic pathogen, which persists within biofilms on airway mucosal surfaces. For many species, biofilm formation is impacted by quorum signaling. Our prior work shows that production of autoinducer-2 (AI-2) promotes biofilm development and persistence for NTHI 86-028NP. NTHI 86-028NP encodes an ABC transporter annotated as a ribose transport system that includes a protein (RbsB) with similarity to the Escherichia coli LsrB and Aggregatibacter actinomycetemcomitans RbsB proteins that bind AI-2. In this study, inactivation of rbsB significantly reduced uptake of AI-2 and the AI-2 precursor dihydroxypentanedione (DPD) by NTHI 86-028NP. Moreover, DPD uptake was not competitively inhibited by ribose or other pentose sugars. Transcript levels of rbsB increased in response to DPD and as bacteria approached stationary-phase growth. The NTHI 86-028NP rbsB mutant also formed biofilms with significantly reduced thickness and total biomass and reduced surface phosphorylcholine, similar to a luxS mutant. Infection studies revealed that loss of rbsB impaired bacterial persistence in the chinchilla middle-ear, similar to our previous results with luxS mutants. Based on these data, we conclude that in NTHI 86-028NP, RbsB is a LuxS/AI-2 regulated protein that is required for uptake of and response to AI-2. PMID:21923771

RbsB (NTHI_0632) mediates quorum signal uptake in nontypeable Haemophilus influenzae strain 86-028NP.

PubMed

Armbruster, Chelsie E; Pang, Bing; Murrah, Kyle; Juneau, Richard A; Perez, Antonia C; Weimer, Kristin E D; Swords, W Edward

2011-11-01

Nontypeable Haemophilus influenzae (NTHI) is a respiratory commensal and opportunistic pathogen, which persists within biofilms on airway mucosal surfaces. For many species, biofilm formation is impacted by quorum signalling. Our prior work shows that production of autoinducer-2 (AI-2) promotes biofilm development and persistence for NTHI 86-028NP. NTHI 86-028NP encodes an ABC transporter annotated as a ribose transport system that includes a protein (RbsB) with similarity to the Escherichia coli LsrB and Aggregatibacter actinomycetemcomitans RbsB proteins that bind AI-2. In this study, inactivation of rbsB significantly reduced uptake of AI-2 and the AI-2 precursor dihydroxypentanedione (DPD) by NTHI 86-028NP. Moreover, DPD uptake was not competitively inhibited by ribose or other pentose sugars. Transcript levels of rbsB increased in response to DPD and as bacteria approached stationary-phase growth. The NTHI 86-028NP rbsB mutant also formed biofilms with significantly reduced thickness and total biomass and reduced surface phosphorylcholine, similar to a luxS mutant. Infection studies revealed that loss of rbsB impaired bacterial persistence in the chinchilla middle ear, similar to our previous results with luxS mutants. Based on these data, we conclude that in NTHI 86-028NP, RbsB is a LuxS/AI-2 regulated protein that is required for uptake of and response to AI-2. © 2011 Blackwell Publishing Ltd.

Job optimization in ATLAS TAG-based distributed analysis

NASA Astrophysics Data System (ADS)

Mambelli, M.; Cranshaw, J.; Gardner, R.; Maeno, T.; Malon, D.; Novak, M.

2010-04-01

The ATLAS experiment is projected to collect over one billion events/year during the first few years of operation. The efficient selection of events for various physics analyses across all appropriate samples presents a significant technical challenge. ATLAS computing infrastructure leverages the Grid to tackle the analysis across large samples by organizing data into a hierarchical structure and exploiting distributed computing to churn through the computations. This includes events at different stages of processing: RAW, ESD (Event Summary Data), AOD (Analysis Object Data), DPD (Derived Physics Data). Event Level Metadata Tags (TAGs) contain information about each event stored using multiple technologies accessible by POOL and various web services. This allows users to apply selection cuts on quantities of interest across the entire sample to compile a subset of events that are appropriate for their analysis. This paper describes new methods for organizing jobs using the TAGs criteria to analyze ATLAS data. It further compares different access patterns to the event data and explores ways to partition the workload for event selection and analysis. Here analysis is defined as a broader set of event processing tasks including event selection and reduction operations ("skimming", "slimming" and "thinning") as well as DPD making. Specifically it compares analysis with direct access to the events (AOD and ESD data) to access mediated by different TAG-based event selections. We then compare different ways of splitting the processing to maximize performance.

Evaluating an alternative method for rapid urinary creatinine determination

EPA Science Inventory

Creatinine (CR) is an endogenously-produced chemical routinely assayed in urine specimens to assess kidney function, sample dilution. The industry-standard method for CR determination, known as the kinetic Jaffe (KJ) method, relies on an exponential rate of a colorimetric change,...

Biochip Which Examines Hepatic Function by Employing Colorimetric Method

NASA Astrophysics Data System (ADS)

Oki, Akio; Ogawa, Hiroki; Takamura, Yuzuru; Horiike, Yasuhiro

2003-03-01

A biochip that is able to quickly analyze hepatic function from the bedside or at home was investigated. The chip essentially consisted of two chips, one that mixed the substrate buffer solution with serums using a centrifugal method and a chip that measured the amounts of γ-glutamyltranspeptidase (γ-GTP), glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) in the serums employing a colorimetric method. The chip should be inexpensive and disposable. Therefore the mixing and measurement channels were fabricated by molding their reverse patterns onto a poly (ethylene terephthalate) (PET) plate. Furthermore, a hydrophobic treatment was performed on the inner wall of the measurement channel to efficiently propagate the light efficiently in the channel. Subsequently, calibration curves were obtained for γ-GTP, GOT and GPT activity levels based on an endpoint method for the γ-GTP and a rate assay for GOT and GPT.

Colorimetric sensor for cysteine in human urine based on novel gold nanoparticles.

PubMed

Zhang, Yan; Jiang, Jingjing; Li, Min; Gao, Pengfei; Zhou, Ying; Zhang, Guomei; Shuang, Shaomin; Dong, Chuan

2016-12-01

Herein, a novel, high sensitive, and specific colorimetric sensor for cysteine (Cys) based on pectinase protected gold nanoparticles (P@AuNPs) has been demonstrated for the first time. The P@AuNPs were synthesized by "MW-assisted heat method" and were characterized by UV-vis, TEM, FT-IR and zeta potential techniques. Cys could cause the aggregation of P@AuNPs due to formation of the strong covalent Au-S bond and electrostatic binding. As the Cys concentration increased, the color of the solutions gradually changed from wine-red to blue as well as the large absorption band shifted from 523 to 650nm upon P@AuNPs aggregation. In addition, various experimental parameters such as pH, the amount of P@AuNPs and incubation time were investigated for the optimum sensing conditions. The concentration of Cys could be determined by monitoring with the naked eye or a UV-vis spectrometer. The proposed colorimetric sensor showed an extreme selectivity toward the determination of Cys in the presence of 20-fold all other different interferents. Under optimum conditions, this method exhibited two good linear ranges from 4.85×10 -9 to 3.02×10 -4 M (R 2 =0.996) and 3.25×10 -3 to 1.03×10 -2 M (R 2 =0.999), with a low detection limit of 4.6×10 -9 M. Moreover, this colorimetric sensor was successfully applied to the detection of Cys in human urine samples, demonstrating its great value for practical application in biological systems. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of a novel colorimetric sensor based on alginate beads for monitoring rainbow trout spoilage.

PubMed

Majdinasab, Marjan; Hosseini, Seyed Mohammad Hashem; Sepidname, Marziyeh; Negahdarifar, Manizheh; Li, Peiwu

2018-05-01

Alginate is a non-toxic, renewable, and linear copolymer obtained from the brown algae Laminaria digitata that can be easily shaped into beads. Its good gel forming properties have made it useful for entrapping food and pharmaceutical ingredients. In this study, alginate beads were used in a novel application as a colorimetric sensor in food intelligent packaging. Colorimetric sensor was developed through entrapping red cabbage extract as a pH indicator in alginate beads. The pH indicator beads were used in rainbow trout packaging for monitoring fillets spoilage. Color change of beads during fish storage was measured using the CIELab method. The alginate bead colorimetric sensor is validated by measuring total volatile basic nitrogen (TVB-N) levels and microbial populations in fish samples. Moreover, peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) were evaluated during storage. Results indicated that increasing the bacterial population during storage and production of proteolytic enzymes resulted in protein degradation, accumulation of volatile amine compounds, increase in the pH and finally color change of alginate beads. The values of TVB-N, pH, PV and TBARS increased with time of storage. The results of TVB-N and microbial growth were in accordance with color change of beads and CIELab data. Therefore, the proposed system enjoys a high sensitivity to pH variations and is capable of monitoring the spoilage of fish or other protein-rich products through its wide range of color changes. The alginate beads containing the red cabbage extract can, thus, be used as a low-cost colorimetric sensor for intelligent packaging applications.

Improved detection of chemical substances from colorimetric sensor data using probabilistic machine learning

NASA Astrophysics Data System (ADS)

Mølgaard, Lasse L.; Buus, Ole T.; Larsen, Jan; Babamoradi, Hamid; Thygesen, Ida L.; Laustsen, Milan; Munk, Jens Kristian; Dossi, Eleftheria; O'Keeffe, Caroline; Lässig, Lina; Tatlow, Sol; Sandström, Lars; Jakobsen, Mogens H.

2017-05-01

We present a data-driven machine learning approach to detect drug- and explosives-precursors using colorimetric sensor technology for air-sampling. The sensing technology has been developed in the context of the CRIM-TRACK project. At present a fully- integrated portable prototype for air sampling with disposable sensing chips and automated data acquisition has been developed. The prototype allows for fast, user-friendly sampling, which has made it possible to produce large datasets of colorimetric data for different target analytes in laboratory and simulated real-world application scenarios. To make use of the highly multi-variate data produced from the colorimetric chip a number of machine learning techniques are employed to provide reliable classification of target analytes from confounders found in the air streams. We demonstrate that a data-driven machine learning method using dimensionality reduction in combination with a probabilistic classifier makes it possible to produce informative features and a high detection rate of analytes. Furthermore, the probabilistic machine learning approach provides a means of automatically identifying unreliable measurements that could produce false predictions. The robustness of the colorimetric sensor has been evaluated in a series of experiments focusing on the amphetamine pre-cursor phenylacetone as well as the improvised explosives pre-cursor hydrogen peroxide. The analysis demonstrates that the system is able to detect analytes in clean air and mixed with substances that occur naturally in real-world sampling scenarios. The technology under development in CRIM-TRACK has the potential as an effective tool to control trafficking of illegal drugs, explosive detection, or in other law enforcement applications.

Discrimination of complex mixtures by a colorimetric sensor array: coffee aromas.

PubMed

Suslick, Benjamin A; Feng, Liang; Suslick, Kenneth S

2010-03-01

The analysis of complex mixtures presents a difficult challenge even for modern analytical techniques, and the ability to discriminate among closely similar such mixtures often remains problematic. Coffee provides a readily available archetype of such highly multicomponent systems. The use of a low-cost, sensitive colorimetric sensor array for the detection and identification of coffee aromas is reported. The color changes of the sensor array were used as a digital representation of the array response and analyzed with standard statistical methods, including principal component analysis (PCA) and hierarchical clustering analysis (HCA). PCA revealed that the sensor array has exceptionally high dimensionality with 18 dimensions required to define 90% of the total variance. In quintuplicate runs of 10 commercial coffees and controls, no confusions or errors in classification by HCA were observed in 55 trials. In addition, the effects of temperature and time in the roasting of green coffee beans were readily observed and distinguishable with a resolution better than 10 degrees C and 5 min, respectively. Colorimetric sensor arrays demonstrate excellent potential for complex systems analysis in real-world applications and provide a novel method for discrimination among closely similar complex mixtures.

Discrimination of Complex Mixtures by a Colorimetric Sensor Array: Coffee Aromas

PubMed Central

Suslick, Benjamin A.; Feng, Liang; Suslick, Kenneth S.

2010-01-01

The analysis of complex mixtures presents a difficult challenge even for modern analytical techniques, and the ability to discriminate among closely similar such mixtures often remains problematic. Coffee provides a readily available archetype of such highly multicomponent systems. The use of a low-cost, sensitive colorimetric sensor array for the detection and identification of coffee aromas is reported. The color changes of the sensor array were used as a digital representation of the array response and analyzed with standard statistical methods, including principal component analysis (PCA) and hierarchical clustering analysis (HCA). PCA revealed that the sensor array has exceptionally high dimensionality with 18 dimensions required to define 90% of the total variance. In quintuplicate runs of 10 commercial coffees and controls, no confusions or errors in classification by HCA were observed in 55 trials. In addition, the effects of temperature and time in the roasting of green coffee beans were readily observed and distinguishable with a resolution better than 10 °C and 5 min, respectively. Colorimetric sensor arrays demonstrate excellent potential for complex systems analysis in real-world applications and provide a novel method for discrimination among closely similar complex mixtures. PMID:20143838

Copper-Based Metal-Organic Framework Nanoparticles with Peroxidase-Like Activity for Sensitive Colorimetric Detection of Staphylococcus aureus.

PubMed

Wang, Shuqin; Deng, Wenfang; Yang, Lu; Tan, Yueming; Xie, Qingji; Yao, Shouzhuo

2017-07-26

Cu-MOF nanoparticles with an average diameter of 550 nm were synthesized from 2-aminoterephthalic acid and Cu(NO 3 ) 2 by a mixed solvothermal method. The Cu-MOF nanoparticles can show peroxidase-like activity that can catalyze 3,3',5,5'-tetramethylbenzidine to produce a yellow chromogenic reaction in the presence of H 2 O 2 . The presence of abundant amine groups on the surfaces of Cu-MOF nanoparticles enables facile modification of Staphylococcus aureus (S. aureus) aptamer on Cu-MOF nanoparticles. By combining Cu-MOF-catalyzed chromogenic reaction with aptamer recognition and magnetic separation, a simple, sensitive, and selective colorimetric method for the detection of S. aureus was developed.

Facial skin color measurement based on camera colorimetric characterization

NASA Astrophysics Data System (ADS)

Yang, Boquan; Zhou, Changhe; Wang, Shaoqing; Fan, Xin; Li, Chao

2016-10-01

The objective measurement of facial skin color and its variance is of great significance as much information can be obtained from it. In this paper, we developed a new skin color measurement procedure which includes following parts: first, a new skin tone color checker made of pantone Skin Tone Color Checker was designed for camera colorimetric characterization; second, the chromaticity of light source was estimated via a new scene illumination estimation method considering several previous algorithms; third, chromatic adaption was used to convert the input facial image into output facial image which appears taken under canonical light; finally the validity and accuracy of our method was verified by comparing the results obtained by our procedure with these by spectrophotometer.

Colorimetric sensing of anions in water using ratiometric indicator-displacement assay.

PubMed

Feng, Liang; Li, Hui; Li, Xiao; Chen, Liang; Shen, Zheng; Guan, Yafeng

2012-09-19

The analysis of anions in water presents a difficult challenge due to their low charge-to-radius ratio, and the ability to discriminate among similar anions often remains problematic. The use of a 3×6 ratiometric indicator-displacement assay (RIDA) array for the colorimetric detection and identification of ten anions in water is reported. The sensor array consists of different combinations of colorimetric indicators and metal cations. The colorimetric indicators chelate with metal cations, forming the color changes. Upon the addition of anions, anions compete with the indicator ligands according to solubility product constants (K(sp)). The indicator-metal chelate compound changes color back dramatically when the competition of anions wins. The color changes of the RIDA array were used as a digital representation of the array response and analyzed with standard statistical methods, including principal component analysis and hierarchical clustering analysis. No confusion or errors in classification by hierarchical clustering analysis were observed in 44 trials. The limit of detection was calculated approximately, and most limits of detections of anions are well below μM level using our RIDA array. The pH effect, temperature influence, interfering anions were also investigated, and the RIDA array shows the feasibility of real sample testing. Copyright © 2012 Elsevier B.V. All rights reserved.

Tuning the chromaticity of the emission color of the copolymers containing Eu(III), Tb(III), Be(II) ions based on colorimetric principle

NASA Astrophysics Data System (ADS)

Zhang, Aiqin; Yang, Yamin; Zhai, Guangmei; Jia, Husheng; Xu, Bingshe

2016-02-01

In this work, a method of tuning the chromaticity of the emission color of the copolymers containing Eu(III), Tb(III), Be(II) ions based on colorimetric principle was proposed. The technological route from coordination to copolymerization was employed to obtain the white light macromolecular phosphor. The three primary color monomers have been synthesized and their Commission Internationale de L'Eclairage (CIE) coordinates are respectively (0.540, 0.314), (0.231, 0.463), and (0.161, 0.054). The molar feed ratios of the three primary color monomers were calculated from the CIE coordinates based on colorimetric principle. Serial copolymers have been synthesized by free radical copolymerization of the three primary color monomers and methyl methacrylate. The quantum efficiency of the copolymers was higher than that of the complex monomers. The complexes were directly boned to the polymer chain, in which the energy transfer was reduced significantly compared to the doped-polymers. The experimental values of copolymers' CIE coordinates were located in the white light region in good agreement with theoretical values. The results indicate that the chromaticity of the emission color of the copolymers containing Eu(III), Tb(III), Be(II) ions could be tuned by theoretical calculation based on colorimetric principle.

EPA Method 3135.2I: Cyanide, Total and Amenable in Aqueous and Solid Samples Automated Colorimetric With Manual Digestion

EPA Pesticide Factsheets

This method describes procedures for preparation and analysis of solid, water and wipe samples for detection and measurement of cyanide amendable to chlorination using acid digestion and spectrophotometry.

Plasmonic colorimetric sensors based on etching and growth of noble metal nanoparticles: Strategies and applications.

PubMed

Zhang, Zhiyang; Wang, Han; Chen, Zhaopeng; Wang, Xiaoyan; Choo, Jaebum; Chen, Lingxin

2018-08-30

Plasmonic colorimetric sensors have emerged as a powerful tool in chemical and biological sensing applications due to the localized surface plasmon resonance (LSPR) extinction in the visible range. Among the plasmonic sensors, the most famous sensing mode is the "aggregation" plasmonic colorimetric sensor which is based on plasmon coupling due to nanoparticle aggregation. Herein, this review focuses on the newly-developing plasmonic colorimetric sensing mode - the etching or the growth of metal nanoparticles induces plasmon changes, namely, "non-aggregation" plasmonic colorimetric sensor. This type of sensors has attracted increasing interest because of their exciting properties of high sensitivity, multi-color changes, and applicability to make a test strip. Of particular interest, the test strip by immobilization of nanoparticles on the substrate can avoid the influence of nanoparticle auto-aggregation and increase the simplicity in storage and use. Although there are many excellent reviews available that describe the advance of plasmonic sensors, limited attention has been paid to the plasmonic colorimetric sensors based on etching or growth of metal nanoparticles. This review highlights recent progress on strategies and application of "non-aggregation" plasmonic colorimetric sensors. We also provide some personal insights into current challenges associated with "non-aggregation" plasmonic colorimetric sensors and propose future research directions. Copyright © 2018 Elsevier B.V. All rights reserved.

A Colorimetric and Fluorescent Chemosensor of Fe3+ Based on an Asymmetrical Squarylium Dye

NASA Astrophysics Data System (ADS)

Lu, Min; Wang, Yue; Li, Ying; Li, Zhongyu; Xu, Song; Yao, Chao

2018-05-01

A novel asymmetrical squarylium-dye-based dual signaling probe was synthesized and found to exhibit colorimetric and fluorescent properties on selective binding towards Fe3+ in ethanol/water (4:1, v/v) solution. The binding constant was determined to be 7.69 × 102 M-1, and the detection limit of SQ was 9.158 × 10-6 M. Most importantly, the 1:2 stoichiometry of the host-guest complexation was confirmed by Job's method. Moreover, the high sensing ability of the receptor towards Fe3+ was also investigated by the electrochemical technique.

CBT for the treatment of depression in Parkinson's disease: a promising nonpharmacological approach.

PubMed

Dobkin, Roseanne DeFronzo; Menza, Matthew; Bienfait, Karina L

2008-01-01

Depression is very common in Parkinson's disease (PD) and linked with a faster progression of physical symptoms, greater cognitive decline and poorer quality of life. Nonpharmacological approaches, such as cognitive-behavioral therapy (CBT), for the treatment of depression in PD (dPD) have received little experimental attention despite strong demonstrated efficacy in other geriatric and medical populations. Depressed PD patients often differ from the depressed non-PD elderly in that they present with increased rates of both executive dysfunction and comorbid psychiatric diagnoses, may differ in their depressive symptom presentation and typically have caregivers who are highly involved in their treatment. Therefore, it is not possible to conclude that empirically validated treatments in the depressed aged will generalize to those with PD. In order to be most effective for PD patients, CBT should be tailored to their unique needs. Additional controlled research is needed to further explore the efficacy of CBT for dPD.

Formation of incoherent deformation twin boundaries in a coarse-grained Al-7Mg alloy

NASA Astrophysics Data System (ADS)

Jin, S. B.; Zhang, K.; Bjørge, R.; Tao, N. R.; Marthinsen, K.; Lu, K.; Li, Y. J.

2015-08-01

Deformation twinning has rarely been observed in coarse grained Al and its alloys except under some extreme conditions such as ultrahigh deformation strain or strain rates. Here, we report that a significant amount of Σ3 deformation twins could be generated in a coarse-grained Al-7 Mg alloy by dynamic plastic deformation (DPD). A systematic investigation of the Σ3 boundaries shows that they are Σ3{112} type incoherent twin boundaries (ITBs). These ITBs have formed by gradual evolution from copious low-angle deformation bands through <111>-twist Σ boundaries by lattice rotation. These findings provide an approach to generate deformation twin boundaries in high stacking fault energy metallic alloys. It is suggested that high solution content of Mg in the alloy and the special deformation mode of DPD played an important role in formation of the Σ and ITBs.

Short-term variability in biomarkers of bone metabolism in sheep.

PubMed

Sousa, Cristina P; de Azevedo, Jorge T; Reis, Rui L; Gomes, Manuela E; Dias, Isabel R

2014-01-01

Changes in bone remodeling during pathological states and during their treatment can be assessed noninvasively by measuring biomarkers of bone metabolism. Their application is limited, however, by the potential biological variability in the levels of these biomarkers over time. To determine the short-term variability in biomarkers of bone metabolism in adult sheep, the authors measured serum levels of alkaline phosphatase (ALP), bone-specific alkaline phosphatase (BALP), osteocalcin (OC), N-terminal propeptide of type-III procollagen (PIIINP), deoxypyridinoline (DPD), tartrate-resistant acid phosphatase (TRAP), calcium and phosphorus intermittently over a 12-week period. There were significant differences in mean ALP activity and in phosphorus concentrations over time, but all other biomarkers showed no significant short-term variability. The results suggest that biomarkers of bone metabolism in sheep, especially the bone resorption marker DPD and the bone formation marker BALP, can be used reliably to detect changes in bone cellular activity.

Real-time monitoring of enzyme-free strand displacement cascades by colorimetric assays

NASA Astrophysics Data System (ADS)

Duan, Ruixue; Wang, Boya; Hong, Fan; Zhang, Tianchi; Jia, Yongmei; Huang, Jiayu; Hakeem, Abdul; Liu, Nannan; Lou, Xiaoding; Xia, Fan

2015-03-01

The enzyme-free toehold-mediated strand displacement reaction has shown potential for building programmable DNA circuits, biosensors, molecular machines and chemical reaction networks. Here we report a simple colorimetric method using gold nanoparticles as signal generators for the real-time detection of the product of the strand displacement cascade. During the process the assembled gold nanoparticles can be separated, resulting in a color change of the solution. This assay can also be applied in complex mixtures, fetal bovine serum, and to detect single-base mismatches. These results suggest that this method could be of general utility to monitor more complex enzyme-free strand displacement reaction-based programmable systems or for further low-cost diagnostic applications.The enzyme-free toehold-mediated strand displacement reaction has shown potential for building programmable DNA circuits, biosensors, molecular machines and chemical reaction networks. Here we report a simple colorimetric method using gold nanoparticles as signal generators for the real-time detection of the product of the strand displacement cascade. During the process the assembled gold nanoparticles can be separated, resulting in a color change of the solution. This assay can also be applied in complex mixtures, fetal bovine serum, and to detect single-base mismatches. These results suggest that this method could be of general utility to monitor more complex enzyme-free strand displacement reaction-based programmable systems or for further low-cost diagnostic applications. Electronic supplementary information (ESI) available: Experimental procedures and analytical data are provided. See DOI: 10.1039/c5nr00697j

[Colorimetric characterization of LCD based on wavelength partition spectral model].

PubMed

Liu, Hao-Xue; Cui, Gui-Hua; Huang, Min; Wu, Bing; Xu, Yan-Fang; Luo, Ming

2013-10-01

To establish a colorimetrical characterization model of LCDs, an experiment with EIZO CG19, IBM 19, DELL 19 and HP 19 LCDs was designed and carried out to test the interaction between RGB channels, and then to test the spectral additive property of LCDs. The RGB digital values of single channel and two channels were given and the corresponding tristimulus values were measured, then a chart was plotted and calculations were made to test the independency of RGB channels. The results showed that the interaction between channels was reasonably weak and spectral additivity property was held well. We also found that the relations between radiations and digital values at different wavelengths varied, that is, they were the functions of wavelength. A new calculation method based on piecewise spectral model, in which the relation between radiations and digital values was fitted by a cubic polynomial in each piece of wavelength with measured spectral radiation curves, was proposed and tested. The spectral radiation curves of RGB primaries with any digital values can be found out with only a few measurements and fitted cubic polynomial in this way and then any displayed color can be turned out by the spectral additivity property of primaries at given digital values. The algorithm of this method was discussed in detail in this paper. The computations showed that the proposed method was simple and the number of measurements needed was reduced greatly while keeping a very high computation precision. This method can be used as a colorimetrical characterization model.

A colorimetric assay of 1-aminocyclopropane-1-carboxylate (ACC) based on ninhydrin reaction for rapid screening of bacteria containing ACC deaminase.

PubMed

Li, Z; Chang, S; Lin, L; Li, Y; An, Q

2011-08-01

1-Aminocyclopropane-1-carboxylate (ACC) deaminase activity is an efficient marker for bacteria to promote plant growth by lowering ethylene levels in plants. We aim to develop a method for rapidly screening bacteria containing ACC deaminase, based on a colorimetric ninhydrin assay of ACC. A reliable colorimetric ninhydrin assay was developed to quantify ACC using heat-resistant polypropylene chimney-top 96-well PCR plates, having the wells evenly heated in boiling water, preventing accidental contamination from boiling water and limiting evaporation. With this method to measure bacterial consumption of ACC, 44 ACC-utilizing bacterial isolates were rapidly screened out from 311 bacterial isolates that were able to grow on minimal media containing ACC as the sole nitrogen source. The 44 ACC-utilizing bacterial isolates showed ACC deaminase activities and belonged to the genus Burkholderia, Pseudomonas or Herbaspirillum. Determination of bacterial ACC consumption by the PCR-plate ninhydrin-ACC assay is a rapid and efficient method for screening bacteria containing ACC deaminase from a large number of bacterial isolates. The PCR-plate ninhydrin-ACC assay extends the utility of the ninhydrin reaction and enables a rapid screening of bacteria containing ACC deaminase from large numbers of bacterial isolates. © 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

A quick inexpensive laboratory method in acute paracetamol poisoning could improve risk assessment, management and resource utilization

PubMed Central

Senarathna, S.M.D.K. Ganga; Ranganathan, Shalini S.; Buckley, Nick; Soysa, S.S.S.B.D. Preethi; Fernandopulle, B. M. Rohini

2012-01-01

Objectives: Acute paracetamol poisoning is an emerging problem in Sri Lanka. Management guidelines recommend ingested dose and serum paracetamol concentrations to assess the risk. Our aim was to determine the usefulness of the patient's history of an ingested dose of >150 mg/kg and paracetamol concentration obtained by a simple colorimetric method to assess risk in patients with acute paracetamol poisoning. Materials and Methods: Serum paracetamol concentrations were determined in 100 patients with a history of paracetamol overdose using High Performance Liquid Chromatography (HPLC); (reference method). The results were compared to those obtained with a colorimetric method. The utility of risk assessment by reported dose ingested and colorimetric analysis were compared. Results: The area under the receiver operating characteristic curve for the history of ingested dose was 0.578 and there was no dose cut-off providing useful risk categorization. Both analytical methods had less than 5% intra- and inter-batch variation and were accurate on spiked samples. The time from blood collection to result was six times faster and ten times cheaper for colorimetry (30 minutes, US$2) than for HPLC (180 minutes, US$20). The correlation coefficient between the paracetamol levels by the two methods was 0.85. The agreement on clinical risk categorization on the standard nomogram was also good (Kappa = 0.62, sensitivity 81%, specificity 89%). Conclusions: History of dose ingested alone greatly over-estimated the number of patients who need antidotes and it was a poor predictor of risk. Paracetamol concentrations by colorimetry are rapid and inexpensive. The use of these would greatly improve the assessment of risk and greatly reduce unnecessary expenditure on antidotes. PMID:23087506

Colorimetric determination of glutathione by using a nanohybrid composed of manganese dioxide and carbon dots.

PubMed

Wang, Qian; Pang, Hongchang; Dong, Yongqiang; Chi, Yuwu; Fu, Fengfu

2018-05-10

A kind of single-layer carbon based dots (CDs) with abundant carboxyl functional groups was hybridized with manganese dioxide (MnO 2 ). The resulting nanohybrid is stable and can be well dispersed in water. MnO 2 is capable of oxidizing the substrate 3,3'5,5'-tetramethylbenzidine (TMB) to form a blue product whose absorption (peaking at 655 nm) fades in the presence of glutathione (GSH). A sensitive and selective colorimetric GSH assay was worked out that has a linear response in the 10 to 0.1 µM GSH concentration range, with a 0.095 μM detection limit. The method was applied to the determination of GSH in spiked fetal calf serum where it gave excellent recoveries. Graphical abstract Schematic of the preparation of a nanohybrid composed of manganese dioxide and carbon based dots (MnO 2 /CDs). They can be used for the colorimetric detection of glutathione (GSH) based on the color change of 3,3'5,5'-tetramethylbenzidine (TMB).

Spectral gamuts and spectral gamut mapping

NASA Astrophysics Data System (ADS)

Rosen, Mitchell R.; Derhak, Maxim W.

2006-01-01

All imaging devices have two gamuts: the stimulus gamut and the response gamut. The response gamut of a print engine is typically described in CIE colorimetry units, a system derived to quantify human color response. More fundamental than colorimetric gamuts are spectral gamuts, based on radiance, reflectance or transmittance units. Spectral gamuts depend on the physics of light or on how materials interact with light and do not involve the human's photoreceptor integration or brain processing. Methods for visualizing a spectral gamut raise challenges as do considerations of how to utilize such a data-set for producing superior color reproductions. Recent work has described a transformation of spectra reduced to 6-dimensions called LabPQR. LabPQR was designed as a hybrid space with three explicit colorimetric axes and three additional spectral reconstruction axes. In this paper spectral gamuts are discussed making use of LabPQR. Also, spectral gamut mapping is considered in light of the colorimetric-spectral duality of the LabPQR space.

Enhanced Colorimetric Immunoassay Accompanying with Enzyme Cascade Amplification Strategy for Ultrasensitive Detection of Low-Abundance Protein

PubMed Central

Gao, Zhuangqiang; Hou, Li; Xu, Mingdi; Tang, Dianping

2014-01-01

Methods based on enzyme labels have been developed for colorimetric immunoassays, but most involve poor sensitivity and are unsuitable for routine use. Herein, we design an enhanced colorimetric immunoassay for prostate-specific antigen (PSA) coupling with an enzyme-cascade-amplification strategy (ECAS-CIA). In the presence of target PSA, the labeled alkaline phosphatase on secondary antibody catalyzes the formation of palladium nanostructures, which catalyze 3,3′,5,5′-tetramethylbenzidine-H2O2 system to produce the colored products, thus resulting in the signal cascade amplification. Results indicated that the ECAS-CIA presents good responses toward PSA, and allows detection of PSA at a concentration as low as 0.05 ng mL−1. Intra- and inter-assay coefficients of variation are below 9.5% and 10.7%, respectively. Additionally, the methodology is validated for analysis of clinical serum specimens with consistent results obtained by PSA ELISA kit. Importantly, the ECAS-CIA opens a new horizon for protein diagnostics and biosecurity. PMID:24509941

A new colorimetric DPPH• scavenging activity method with no need for a spectrophotometer applied on synthetic and natural antioxidants and medicinal herbs.

PubMed

Akar, Zeynep; Küçük, Murat; Doğan, Hacer

2017-12-01

2,2-Diphenyl-1-picrylhydrazyl (DPPH • ) radical scavenging, the most commonly used antioxidant method with more than seventeen thousand articles cited, is very practical; however, as with most assays, it has the major disadvantage of dependence on a spectrophotometer. To overcome this drawback, the colorimetric determination of the antioxidant activity using a scanner and freely available Image J software was developed. In this new method, the mixtures of solutions of DPPH • and standard antioxidants or extracts of common medicinal herbs were dropped onto TLC plates, after an incubation period. The spot images were evaluated with Image J software to determine CSC 50 values, the sample concentrations providing 50% colour reduction, which were very similar with the SC 50 values obtained with spectrophotometric method. The advantages of the new method are the use of lower amounts of reagents and solvents, no need for costly spectrophotometers, and thus significantly lowered costs, and convenient implementation in any environment and situation.

Comparing different methods for fast screening of microbiological quality of beach sand aimed at rapid-response remediation.

PubMed

Testolin, Renan C; Almeida, Tito C M; Polette, Marcus; Branco, Joaquim O; Fischer, Larissa L; Niero, Guilherme; Poyer-Radetski, Gabriel; Silva, Valéria C; Somensi, Cleder A; Corrêa, Albertina X R; Corrêa, Rogério; Rörig, Leonardo R; Itokazu, Ana Gabriela; Férard, Jean-François; Cotelle, Sylvie; Radetski, Claudemir M

2017-05-15

There is scientific evidence that beach sands are a significant contributor to the pathogen load to which visitors are exposed. To develop beach quality guidelines all beach zones must be included in microbiological evaluations, but monitoring methods for beach sand quality are relatively longstanding, expensive, laborious and require moderate laboratory infrastructure. This paper aimed to evaluate the microorganism activity in different beach zones applying and comparing a classical method of membrane filtration (MF) with two colorimetric screening methods based on fluorescein (FDA) and tetrazolium (TTC) salt biotransformation to evaluate a new rapid and low-cost method for beach sand microbiological contamination assessments. The colorimetric results can help beach managers to evaluate rapidly and at low cost the microbiological quality of different beach zones in order to decide whether remedial actions need to be adopted to prevent exposure of the public to microbes due to beach sand and/or water contamination. Copyright © 2017. Published by Elsevier Ltd.

Computational Biorheology of Human Blood Flow in Health and Disease

PubMed Central

Fedosov, Dmitry A.; Dao, Ming; Karniadakis, George Em; Suresh, Subra

2014-01-01

Hematologic disorders arising from infectious diseases, hereditary factors and environmental influences can lead to, and can be influenced by, significant changes in the shape, mechanical and physical properties of red blood cells (RBCs), and the biorheology of blood flow. Hence, modeling of hematologic disorders should take into account the multiphase nature of blood flow, especially in arterioles and capillaries. We present here an overview of a general computational framework based on dissipative particle dynamics (DPD) which has broad applicability in cell biophysics with implications for diagnostics, therapeutics and drug efficacy assessments for a wide variety of human diseases. This computational approach, validated by independent experimental results, is capable of modeling the biorheology of whole blood and its individual components during blood flow so as to investigate cell mechanistic processes in health and disease. DPD is a Lagrangian method that can be derived from systematic coarse-graining of molecular dynamics but can scale efficiently up to arterioles and can also be used to model RBCs down to the spectrin level. We start from experimental measurements of a single RBC to extract the relevant biophysical parameters, using single-cell measurements involving such methods as optical tweezers, atomic force microscopy and micropipette aspiration, and cell-population experiments involving microfluidic devices. We then use these validated RBC models to predict the biorheological behavior of whole blood in healthy or pathological states, and compare the simulations with experimental results involving apparent viscosity and other relevant parameters. While the approach discussed here is sufficiently general to address a broad spectrum of hematologic disorders including certain types of cancer, this paper specifically deals with results obtained using this computational framework for blood flow in malaria and sickle cell anemia. PMID:24419829

Decision peptide-driven: a free software tool for accurate protein quantification using gel electrophoresis and matrix assisted laser desorption ionization time of flight mass spectrometry.

PubMed

Santos, Hugo M; Reboiro-Jato, Miguel; Glez-Peña, Daniel; Nunes-Miranda, J D; Fdez-Riverola, Florentino; Carvallo, R; Capelo, J L

2010-09-15

The decision peptide-driven tool implements a software application for assisting the user in a protocol for accurate protein quantification based on the following steps: (1) protein separation through gel electrophoresis; (2) in-gel protein digestion; (3) direct and inverse (18)O-labeling and (4) matrix assisted laser desorption ionization time of flight mass spectrometry, MALDI analysis. The DPD software compares the MALDI results of the direct and inverse (18)O-labeling experiments and quickly identifies those peptides with paralleled loses in different sets of a typical proteomic workflow. Those peptides are used for subsequent accurate protein quantification. The interpretation of the MALDI data from direct and inverse labeling experiments is time-consuming requiring a significant amount of time to do all comparisons manually. The DPD software shortens and simplifies the searching of the peptides that must be used for quantification from a week to just some minutes. To do so, it takes as input several MALDI spectra and aids the researcher in an automatic mode (i) to compare data from direct and inverse (18)O-labeling experiments, calculating the corresponding ratios to determine those peptides with paralleled losses throughout different sets of experiments; and (ii) allow to use those peptides as internal standards for subsequent accurate protein quantification using (18)O-labeling. In this work the DPD software is presented and explained with the quantification of protein carbonic anhydrase. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Recurrence and 5-FU sensitivity of stage I/II node-negative breast, lung, or gastric cancer with occult neoplastic cells in lymph node sinuses.

PubMed

Mukai, Masaya; Sato, Shinkichi; Tajima, Takayuki; Ninomiya, Hiromi; Wakui, Kanako; Komatsu, Nobukazu; Tsuchiya, Kazutoshi; Nakasaki, Hisao; Makuuchi, Hiroyasu

2006-04-01

This study was designed to examine the relationship between the presence of occult neoplastic cells (ONCs) in lymph nodes (LNs) and survival in 238 patients with stage I/II LN-negative cancer of the breast, lung, or stomach. In addition, immunohistochemistry for TS and DPD was used to compare the 5-FU sensitivity of the primary tumor in ONC (+) patients. The 5-year relapse-free survival (RFS) rate of 215 ONC (-) patients and 23 ONC (+) patients was 95.2 and 82.6%, respectively (p=0.0107). The 5-year overall survival (OS) rate of the ONC (-) and (+) patients was 97.4 and 77.4%, respectively (p=0.0000). The 6 ONC (+) patients with recurrence showed high and low TS expression in 33.3% (2/6) and 66.7% (4/6), respectively, while high and low DPD expression was observed in 16.7% (1/6) and 83.3% (5/6), respectively. In the 17 ONC (+) patients without recurrence, the corresponding values were 64.7% (11/17), 35.3% (6/17), 29.4% (5/17), and 70.6% (12/17). Patients with a combination of high TS and low DPD expression accounted for 33.3% (2/6) of the ONC (+) patients with recurrence and 52.9% (9/17) of those without recurrence, showing no significant difference between the two groups. These results suggest that ONCs are associated with a lower survival rate and that ONC (+) patients are unlikely to respond to 5-FU+LV therapy.

Targeting miR-21 enhances the sensitivity of human colon cancer HT-29 cells to chemoradiotherapy in vitro

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng, Jun; Lei, Wan; Fu, Jian-Chun

2014-01-17

Highlight: •MiR-21 plays a significant role in 5-FU resistance. •This role might be attributed to targeting of hMSH2 as well as TP and DPD via miR-21 targeted hMSH2. •Indirectly targeted TP and DPD to influence 5-FU chemotherapy sensitivity. -- Abstract: 5-Fluorouracil (5-FU) is a classic chemotherapeutic drug that has been widely used for colorectal cancer treatment, but colorectal cancer cells are often resistant to primary or acquired 5-FU therapy. Several studies have shown that miR-21 is significantly elevated in colorectal cancer. This suggests that this miRNA might play a role in this resistance. In this study, we investigated this possibilitymore » and the possible mechanism underlying this role. We showed that forced expression of miR-21 significantly inhibited apoptosis, enhanced cell proliferation, invasion, and colony formation ability, promoted G1/S cell cycle transition and increased the resistance of tumor cells to 5-FU and X radiation in HT-29 colon cancer cells. Furthermore, knockdown of miR-21 reversed these effects on HT-29 cells and increased the sensitivity of HT-29/5-FU to 5-FU chemotherapy. Finally, we showed that miR-21 targeted the human mutS homolog2 (hMSH2), and indirectly regulated the expression of thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD). These results demonstrate that miR-21 may play an important role in the 5-FU resistance of colon cancer cells.« less

Bupropion improves attention but does not affect impulsive behavior in healthy young adults.

PubMed

Acheson, Ashley; de Wit, Harriet

2008-04-01

Bupropion is an effective abstinence aid for cessation of smoking and possibly other drug use as well. There is evidence that bupropion improves attention and impulse control in certain patient populations, and improvements in these processes could mediate its efficacy as an abstinence aid. In the present study, we tested the effects of acute bupropion on measures of attention and impulsivity in healthy adults with d-amphetamine included as a positive control. Twenty-two nonsmokers (11 women) and 11 smokers (4 women) completed four 4-hr sessions where they received placebo, bupropion (150 or 300 mg), or d-amphetamine (20 mg) in capsules. Ninety minutes after capsule administration, participants were tested on attention with a simple reaction time task (SRT) and on impulsivity with the stop task, a delay and probability discounting task (DPD), and the balloon analogue risk task (BART). Participants also completed mood questionnaires during sessions. Bupropion (150 mg) decreased lapses in attention on the SRT, but did not affect performance on the stop task, DPD, or BART. Amphetamine decreased lapses in attention and speeded sensory motor processing time on the SRT but did not significantly affect responding on the stop task or DPD. On the BART, d-amphetamine tended to decrease risk taking in men but increased risk taking in women. Bupropion (300 mg) and d-amphetamine increased ratings of arousal. These results suggest that bupropion improves attention without affecting impulsive behavior in healthy adults. Improvements in attention may contribute to the effectiveness of bupropion as a pharmacotherapy for smoking.

Bupropion improves attention but does not affect impulsive behavior in healthy young adults

PubMed Central

Acheson, Ashley; de Wit, Harriet

2014-01-01

Bupropion is an effective abstinence aid for cessation of smoking and possibly other drug use as well. There is evidence that bupropion improves attention and impulse control in certain patient populations, and improvements in these processes could mediate its efficacy as an abstinence aid. In the present study, we tested the effects of acute bupropion on measures of attention and impulsivity in healthy adults with d-amphetamine included as a positive control. Twenty-two nonsmokers (11 women) and 11 smokers (4 women) completed four 4-h sessions where they received placebo, bupropion (150 or 300 mg) or d-amphetamine (20 mg) in capsules. Ninety minutes after capsule administration, participants were tested on attention with a Simple Reaction Time Task (SRT) and on impulsivity with the Stop Task, a Delay and Probability Discounting Task (DPD), and the Balloon Analogue Risk Task (BART). Participants also completed mood questionnaires during sessions. Bupropion (150 mg) decreased lapses in attention on the SRT, but did not affect performance on the Stop Task, DPD or BART. d-Amphetamine decreased lapses in attention and speeded sensory motor processing time on the SRT but did not significantly affect responding on the Stop Task or DPD. On the BART, d-amphetamine tended to decrease risk taking in men but increased risk taking in women. Bupropion (300 mg) and d-amphetamine increased ratings of arousal. These results suggest that bupropion improves attention without affecting impulsive behavior in healthy adults. Improvements in attention may contribute to the effectiveness of bupropion as a pharmacotherapy for smoking. PMID:18489015

Activity restriction increases deoxypyridinoline excretion in hospitalized high-risk pregnant women.

PubMed

Vanderspank, Dana; Bernier, Suzanne M; Sopper, Maggie M; Watson, Patricia; Mottola, Michelle F

2014-01-01

Activity restriction (AR), one of the most common interventions used in high-risk pregnancies, may exacerbate loss of bone mass. The purpose of this study was to determine changes over time in bone resorption in hospitalized AR women during late pregnancy. This was a short-term prospective study conducted in two tertiary-care obstetric hospitals. We measured urinary deoxypyridinoline (Dpd) excretion, a marker of bone resorption, once per week in a convenience sample of 14 hospitalized AR women in the third trimester and compared values at 28-31 and 34-36 weeks' gestation to those of 11 ambulatory control women. Both groups completed a bone-loading questionnaire, 3-day food intake record, and pedometer step counts at the same gestational age. Urinary Dpd excretion increased from Days 1-7 (2.60 ± 0.32 nmol/mmol creatinine) to Days 22-28 (5.36 ± 0.83 nmol/mmol creatinine; p ≤ .05). Dpd excretion was higher in AR women (4.51 ± 0.31 nmol/mmol creatinine) than ambulatory women (2.72 ± 0.39 nmol/mmol creatinine) at 34-36 weeks' gestation (p ≤ .05). Energy intake between ambulatory and AR women was not different (p ≥ .05). All women met the daily requirements for calcium and vitamin D intake during pregnancy. Average daily pedometer steps for the AR women were significantly less compared to controls (1,329 ± 936 and 8,024 ± 1,890 steps/day, respectively; p ≤ .05). AR leads to increased bone resorption in hospitalized pregnant women, which may impact future risk of developing osteopenia and osteoporosis.

Needle Decompression of Tension Pneumothorax with Colorimetric Capnography.

PubMed

Naik, Nimesh D; Hernandez, Matthew C; Anderson, Jeff R; Ross, Erika K; Zielinski, Martin D; Aho, Johnathon M

2017-11-01

The success of needle decompression for tension pneumothorax is variable, and there are no objective measures assessing effective decompression. Colorimetric capnography, which detects carbon dioxide present within the pleural space, may serve as a simple test to assess effective needle decompression. Three swine underwent traumatically induced tension pneumothorax (standard of care, n = 15; standard of care with needle capnography, n = 15). Needle thoracostomy was performed with an 8-cm angiocatheter. Similarly, decompression was performed with the addition of colorimetric capnography. Subjective operator assessment of decompression was recorded and compared with true decompression, using thoracoscopic visualization for both techniques. Areas under receiver operating curves were calculated and pairwise comparison was performed to assess statistical significance (P < .05). The detection of decompression by needle colorimetric capnography was found to be 100% accurate (15 of 15 attempts), when compared with thoracoscopic assessment (true decompression). Furthermore, it accurately detected the lack of tension pneumothorax, that is, the absence of any pathologic/space-occupying lesion, in 100% of cases (10 of 10 attempts). Standard of care needle decompression was detected by operators in 9 of 15 attempts (60%) and was detected in 3 of 10 attempts when tension pneumothorax was not present (30%). True decompression, under direct visualization with thoracoscopy, occurred 15 of 15 times (100%) with capnography, and 12 of 15 times (80%) without capnography. Areas under receiver operating curves were 0.65 for standard of care and 1.0 for needle capnography (P = .002). Needle decompression with colorimetric capnography provides a rapid, effective, and highly accurate method for eliminating operator bias for tension pneumothorax decompression. This may be useful for the treatment of this life-threatening condition. Copyright © 2017 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

Ultrasensitive colorimetric detection of Cu2+ ion based on catalytic oxidation of L-cysteine.

PubMed

Yin, Kun; Li, Bowei; Wang, Xiaochun; Zhang, Weiwei; Chen, Lingxin

2015-02-15

As an essential element, copper ion (Cu(2+)) plays important roles in human beings for its participation in diverse metabolic processes as a cofactor and/or a structural component of enzymes. However, excessive uptake of Cu(2+) ion gives rise to the risk of certain diseases. So, it is important to develop simple ways to monitor and detect Cu(2+) ion. In this study, a simple, facile colorimetric sensor for the ultrasensitive determination of Cu(2+) ion was developed based on the following principle: L-cysteine and 1-chloro-2,4-dinitrobenzene (CDNB) could be conjugated to form the yellow product 2,4-dinitrophenylcysteine (DNPC), which was measurable at 355nm; however, upon addition of Cu(2+) ion, the absorbance of DNPC would be decreased owing to the Cu(2+) ion catalytic oxidation of L-cysteine to L-cystine in the presence of O2. Thus, the colorimetric detection of Cu(2+) ion could be achieved. The optimal pH, buffer, temperature and incubation time for the colorimetric sensor were obtained of pH 6.8 in 0.1M HEPES solution, 90 °C and 50 min, respectively. A good linearity within the range of 0.8-10 nM (r = 0.996) was attained, with a high detectability up to 0.5nM. Analyses of Cu(2+) ion in drinking water, lake water, seawater and biological samples were carried out and the method performances were found to agree well with that obtained by ICP-MS. The developed simple colorimetric sensor proved applicable for Cu(2+) ion determination in real samples with high sensitivity and selectivity. Copyright © 2014 Elsevier B.V. All rights reserved.

Evaluation of a QuECHERS-like extraction approach for the determination of PBDEs in mussels by immuno-assay-based screening methods

USDA-ARS?s Scientific Manuscript database

A sample preparation method was evaluated for the determination of polybrominated diphenyl ethers (PBDEs) in mussel samples, by using colorimetric and electrochemical immunoassay-based screening methods. A simple sample preparation in conjunction with a rapid screening method possesses the desired c...

A continuous spectrophotometric assay method for peptidylarginine deiminase type 4 activity.

PubMed

Liao, Ya-Fan; Hsieh, Hui-Chieh; Liu, Guang-Yaw; Hung, Hui-Chih

2005-12-15

A simple, continuous spectrophotometric assay for peptidylarginine deiminase (PAD) is described. Deimination of peptidylarginine results in the formation of peptidylcitrulline and ammonia. The ammonia released during peptidylarginine hydrolysis is coupled to the glutamate-dehydrogenase-catalyzed reductive amination of alpha-ketoglutarate to glutamate and reduced nicotinamide adenine dinucleotide (NADH) oxidation. The disappearance of absorbance at 340nm due to NADH oxidation is continuously measured. The specific activity obtained by this new protocol for highly purified human PAD is comparable to that obtained by a commonly used colorimetric procedure, which measures the ureido group of peptidylcitrulline by coupling with diacetyl monoxime. The present continuous spectrophotometric method is highly sensitive and accurate and is thus suitable for enzyme kinetic analysis of PAD. The Ca(2+) concentration for half-maximal activity of PAD obtained by this method is comparable to that previously obtained by the colorimetric procedure.

The colorimetric analysis of anti-tuberculosis fixed-dose combination tablets and capsules.

PubMed

Ellard, G A

1999-11-01

The perceived need to demonstrate whether or not the actual amounts of rifampicin, isoniazid and pyrazinamide in fixed-dose combination tablets or capsules correspond to their stated drug contents. To adapt specific, robust and simple colorimetric methods that have been previously applied to measuring plasma and urinary rifampicin, isoniazid, pyrazinamide and ethambutol concentrations to estimate tablet and capsule drug contents. The methods were applied to the analysis of 14 commercially manufactured fixed-dose combinations: two capsule and three tablet formulations containing rifampicin and isoniazid; seven tablet formulations containing rifampicin, isoniazid and pyrazinamide; and two tablet formulations containing rifampicin, isoniazid, pyrazinamide and ethambutol. All the combined formulations contained near to their stated drug contents. Replicate analyses confirmed the excellent precision of the drug analyses. Such methods are not only rapid to perform but should be practical in many Third World situations with relatively modest laboratory facilities.

Reconstruction of reflectance data using an interpolation technique.

PubMed

Abed, Farhad Moghareh; Amirshahi, Seyed Hossein; Abed, Mohammad Reza Moghareh

2009-03-01

A linear interpolation method is applied for reconstruction of reflectance spectra of Munsell as well as ColorChecker SG color chips from the corresponding colorimetric values under a given set of viewing conditions. Hence, different types of lookup tables (LUTs) have been created to connect the colorimetric and spectrophotometeric data as the source and destination spaces in this approach. To optimize the algorithm, different color spaces and light sources have been used to build different types of LUTs. The effects of applied color datasets as well as employed color spaces are investigated. Results of recovery are evaluated by the mean and the maximum color difference values under other sets of standard light sources. The mean and the maximum values of root mean square (RMS) error between the reconstructed and the actual spectra are also calculated. Since the speed of reflectance reconstruction is a key point in the LUT algorithm, the processing time spent for interpolation of spectral data has also been measured for each model. Finally, the performance of the suggested interpolation technique is compared with that of the common principal component analysis method. According to the results, using the CIEXYZ tristimulus values as a source space shows priority over the CIELAB color space. Besides, the colorimetric position of a desired sample is a key point that indicates the success of the approach. In fact, because of the nature of the interpolation technique, the colorimetric position of the desired samples should be located inside the color gamut of available samples in the dataset. The resultant spectra that have been reconstructed by this technique show considerable improvement in terms of RMS error between the actual and the reconstructed reflectance spectra as well as CIELAB color differences under the other light source in comparison with those obtained from the standard PCA technique.

Colorimetric detection of Cucumber green mottle mosaic virus using unmodified gold nanoparticles as colorimetric probes.

PubMed

Wang, Lin; Liu, Zhanmin; Xia, Xueying; Yang, Cuiyun; Huang, Junyi; Wan, Sibao

2017-05-01

Cucumber green mottle mosaic virus (CGMMV)causes a severe mosaic symptom of watermelon and cucumber, and can be transmitted via infected cucumber seeds, leaves and soil. It remains a challenge to detect this virus to prevent its introduction and infection and spread in fields. For this purpose, a simple and sensitive label-free colorimetric detection method for CGMMV has been developed with unmodified gold nanoparticles (AuNPs) as colorimetric probes. The method is based on the finding that the presence of RT-PCR target products of CGMMV and species-specific probes results in color change of AuNPs from red to blue after NaCl induction. Normally, species-specific probes attach to the surface of AuNPs and thereby increasing their resistance to NaCl-induced aggregation. The concentration of sodium, probes in the reaction system and evaluation of specificity and sensitivity of a novel assay, visual detection of Cucumber green mottle mosaic virus using unmodified AuNPs has been carried out with simple preparation of samples in our study. Through this assay, as low as 30pg/μL of CGMMV RNA was thus detected visually, by the naked eye, without the need for any sophisticated, expensive instrumentation and biochemical reagents. The specificity was 100% and exhibited good reproducibility in our assays. The results note that this assay is highly species-specific, simple, low-cost, and visual for easy detection of CGMMV in plant tissues. Therefore, visual assay is a potentially useful tool for middle or small-scales corporations and entry-exit inspection and quarantine bureau to detect CGMMV in cucumber seeds or plant tissues. Copyright © 2017 Elsevier B.V. All rights reserved.

Phosphorus Determination by Derivative Activation Analysis: A Multifaceted Radiochemical Application.

ERIC Educational Resources Information Center

Kleppinger, E. W.; And Others

1984-01-01

Although determination of phosphorus is important in biology, physiology, and environmental science, traditional gravimetric and colorimetric methods are cumbersome and lack the requisite sensitivity. Therefore, a derivative activation analysis method is suggested. Background information, procedures, and results are provided. (JN)

Colorimetric consideration of transparencies for a typical LACIE scene

NASA Technical Reports Server (NTRS)

Juday, R. D. (Principal Investigator)

1979-01-01

The production film converter used to produce LACIE imagery is described as well as schemes designed to provide the analyst with operational film products. Two of these products are discussed from the standpoint of color theory. Colorimetric terminology is defined and the mathematical calculations are given. Topics covered include (1) history of product 1 and 3 algorithm development; (2) colorimetric assumptions for product 1 and 3 algorithms; (3) qualitative results from a colorimetric analysis of a typical LACIE scene; and (4) image-to-image color stability.

Highly selective fluorescent and colorimetric chemosensor for detection of Hg2 + ion in aqueous media

NASA Astrophysics Data System (ADS)

Zareh Jonaghani, Mohammad; Zali-Boeini, Hassan

2017-05-01

A highly efficient and selective fluorescent and colorimetric chemosensor based on naphthothiazole skeleton was synthesized and its colorimetric and fluorescent properties were investigated. The sensor displays a rapid and highly selective colorimetric and fluorescence response toward Hg2 + without interference with other metal ions in CH3CN/H2O mixture (50/50, v/v). The detection limit for the fluorescent chemosensor S1 toward Hg2 + was 3.42 × 10- 8 M.

A quick inexpensive laboratory method in acute paracetamol poisoning could improve risk assessment, management and resource utilization.

PubMed

Senarathna, S M D K Ganga; Ranganathan, Shalini S; Buckley, Nick; Soysa, S S S B D Preethi; Fernandopulle, B M Rohini

2012-01-01

Acute paracetamol poisoning is an emerging problem in Sri Lanka. Management guidelines recommend ingested dose and serum paracetamol concentrations to assess the risk. Our aim was to determine the usefulness of the patient's history of an ingested dose of >150 mg/kg and paracetamol concentration obtained by a simple colorimetric method to assess risk in patients with acute paracetamol poisoning. Serum paracetamol concentrations were determined in 100 patients with a history of paracetamol overdose using High Performance Liquid Chromatography (HPLC); (reference method). The results were compared to those obtained with a colorimetric method. The utility of risk assessment by reported dose ingested and colorimetric analysis were compared. The area under the receiver operating characteristic curve for the history of ingested dose was 0.578 and there was no dose cut-off providing useful risk categorization. Both analytical methods had less than 5% intra- and inter-batch variation and were accurate on spiked samples. The time from blood collection to result was six times faster and ten times cheaper for colorimetry (30 minutes, US$2) than for HPLC (180 minutes, US$20). The correlation coefficient between the paracetamol levels by the two methods was 0.85. The agreement on clinical risk categorization on the standard nomogram was also good (Kappa = 0.62, sensitivity 81%, specificity 89%). History of dose ingested alone greatly over-estimated the number of patients who need antidotes and it was a poor predictor of risk. Paracetamol concentrations by colorimetry are rapid and inexpensive. The use of these would greatly improve the assessment of risk and greatly reduce unnecessary expenditure on antidotes.

L-Phenylalanine concentration in blood of phenylketonuria patients: a modified enzyme colorimetric assay compared with amino acid analysis, tandem mass spectrometry, and HPLC methods.

PubMed

De Silva, Veronica; Oldham, Charlie D; May, Sheldon W

2010-09-01

Phenylketonuria (PKU) is an autosomal recessive disorder caused by an impaired conversion of L-phenylalanine (Phe) to L-tyrosine, typically resulting from a deficiency in activity of a hepatic and renal enzyme L-phenylalanine hydroxylase. The disease is characterized by an increased concentration of Phe and its metabolites in body fluids. A modified assay based on an enzymatic-colorimetric methodology was developed for measuring blood Phe levels in PKU patients; this method is designed for use with undeproteinized samples and avoids the use of solvents or amphiphilic agents. Thus, the method could be suitable for incorporation into a simple home-monitoring device. We report here on a comparison of blood Phe concentrations in PKU patients measured in undeproteinized plasma using this enzyme colorimetric assay (ECA), with values determined by amino acid analysis (AAA) of deproteinized samples, and HPLC and tandem mass spectrometry (MS/MS) analyses of dried blood spot (DBS) eluates. Pearson correlation coefficients of 0.951, 0.976 and 0.988 were obtained when AAA-measured Phe concentrations were compared with the ECA-, HPLC- or MS/MS-measured values, respectively. A Bland-Altman analysis revealed that mean Phe concentrations determined using AAA were on average 65 μmol/L lower than values measured by our ECA. These results may be the result of minimizing the manipulations performed on the patient sample compared with AAA, HPLC, and MS/MS methods, which involve plasma deproteinization or DBS elution and derivatization. The results reported here confirm that Phe concentrations determined by our ECA method are comparable to those determined by other widely used methods for a broad range of plasma Phe concentrations.

Colorimetric sensing of selenocystine using gold nanoparticles.

PubMed

Liu, Liyang; Wang, Xia; Yang, Juan; Bai, Yan

2017-10-15

We present a highly selective and sensitive colorimetric method for the detection of selenocystine (SeCys) coexisting with other amino acids, especially cysteine (Cys) using the gold nanoparticles (AuNPs). Firstly, Cys was oxidized to cystine (Cys-Cys) by dissolved oxygen under Cu 2+ catalysis in the pre-reaction, which eliminated the interference of Cys in the SeCys sensing process. Then SeCys induced the rapid aggregation of AuNPs through Au-Se bond and complex formation of Cu 2+ -SeCys in the colorimetric reaction, in which the color change of AuNPs from red to blue or purple with the naked eye detection or with a UV-vis spectrophotometric determination. The concentration of SeCys was quantified by the value at 670 nm from the second-derivative SPR absorbance spectrum. The linear range was from 2 μM to 14 μM with correlation coefficient of 0.999 and a detection limit (LOD) was 0.14 μM. Moreover, the colorimetric response of AuNPs exhibited remarkable specificity to SeCys coexisting with 18 amino acids in a simulation sample, in which the total concentration of Cys and Cys-Cys was less than 15 μM and the each concentration of other 16 common amino acids was 10 μM. Copyright © 2017 Elsevier Inc. All rights reserved.

Highly sensitive colorimetric detection of glucose in a serum based on DNA-embeded Au@Ag core-shell nanoparticles

NASA Astrophysics Data System (ADS)

Kang, Fei; Hou, Xiangshu; Xu, Kun

2015-10-01

Glucose is a key energy substance in diverse biology and closely related to the life activities of the organism. To develop a simple and sensitive method for glucose detection is extremely urgent but still remains a key challenge. Herein, we report a colorimetric glucose sensor in a homogeneous system based on DNA-embedded core-shell Au@Ag nanoparticles. In this assay, a glucose substrate was first catalytically oxidized by glucose oxidase to produce H2O2 which would further oxidize and gradually etch the outer silver shell of Au@Ag nanoparticles. Afterwards, the solution color changed from yellow to red and the surface plasmon resonance (SPR) band of Au@Ag nanoparticles declined and red-shifted from 430 to 516 nm. Compared with previous silver-based glucose colorimetric detection strategies, the distinctive SPR band change is superior to the color variation, which is critical to the high sensitivity of this assay. Benefiting from the outstanding optical property, robust stability and well-dispersion of the core-shell Au@AgNPs hybrid, this colorimetric assay obtained a detection limit of glucose as low as 10 nM, which is at least a 10-fold improvement over other AgNPs-based procedures. Moreover, this optical biosensor was successfully employed to the determination of glucose in fetal bovine serum.

The effect of carbonated beverages on colorimetric end-tidal CO(2) determination

PubMed

Qureshi; Park; Sturmann; Hsu

2000-10-01

Esophageal intubation is a significant complication of attempted airway control. Colorimetric end-tidal CO(2) monitors are highly sensitive and specific for detecting the presence of CO(2). There are reports of false-positive end-tidal CO(2) readings from esophageal intubations in patients who had ingested carbonated beverages. OBJECTIVE: To determine whether carbonated gastric contents can affect colorimetric end-tidal CO(2) readings. METHODS: End-tidal CO(2) was measured in sacrificed piglets at measured time intervals after instillation of 5-, 10-, 15-, and 20-mL aliquots of Diet Coke were placed into the stomach via a 28-French orogastric tube followed by esophageal intubation. The stomach was completely evacuated prior to each instillation and rechecked for baseline CO(2). RESULTS: Compiled data from three piglets (20-30 kg). Piglets were not ventilated or moved and determinations were measured at 20 degrees while supine. All data collected within 2 hours postmortem (table 24-1). CONCLUSIONS: The colorimetric end-tidal CO(2) turned "yellow" and did not change to blue with extended insufflations. The CO(2) of a small quantity of carbonated beverage in the stomach could be "blown off" by multiple insufflations. We conclude that esophageal intubation in the setting of recent ingestion of a carbonated beverage may result in a false-positive end-tidal CO(2) determination.

A sensitive colorimetric assay system for nucleic acid detection based on isothermal signal amplification technology.

PubMed

Hu, Bo; Guo, Jing; Xu, Ying; Wei, Hua; Zhao, Guojie; Guan, Yifu

2017-08-01

Rapid and accurate detection of microRNAs in biological systems is of great importance. Here, we report the development of a visual colorimetric assay which possesses the high amplification capabilities and high selectivity of the rolling circle amplification (RCA) method and the simplicity and convenience of gold nanoparticles used as a signal indicator. The designed padlock probe recognizes the target miRNA and is circularized, and then acts as the template to extend the target miRNA into a long single-stranded nucleotide chain of many tandem repeats of nucleotide sequences. Next, the RCA product is hybridized with oligonucleotides tagged onto gold nanoparticles. This interaction leads to the aggregation of gold nanoparticles, and the color of the system changes from wine red to dark blue according to the abundance of miRNA. A linear correlation between fluorescence and target oligonucleotide content was obtained in the range 0.3-300 pM, along with a detection limit of 0.13 pM (n = 7) and a RSD of 3.9% (30 pM, n = 9). The present approach provides a simple, rapid, and accurate visual colorimetric assay that allows sensitive biodetection and bioanalysis of DNA and RNA nucleotides of interest in biologically important samples. Graphical abstract The colorimetric assay system for analyzing target oligonucleotides.

[Examination of placental three-dimensional power Doppler indices and perinatal outcome in pregnancies complicated by intrauterine growth restriction].

PubMed

Molnár, András; Surányi, Andrea; Jakó, Mária; Nyári, Tibor; Németh, Gábor

2017-07-01

Development of intrauterine growth restriction (IUGR) can be traced back to maternal or fetal factors, but in many cases we find placental factors (reduced placental circulation) in the background. Our aim was to examine whether the reduced placental bloodperfusion and vascularity show any correlation with cesarean section frequency and the clinical outcome in IUGR pregnancies. The aim of the present study was also to use a properly calibrated and reproducible method for evaluating placental blood flow, that can later be incorporated into the routine examination. 254 women were recruited in our prospective case-control study. The 3 dimensional power Doppler (3DPD) ultrasound indices; vascularisation index (VI), flow index (FI) and vascularization flow index (VFI) were measured on each participant. Median VI was 3.7% (interquartile range [IQR] 3.2%-4.2%) in the IUGR group and 10.1% (IQR 8.6%-10.9%) in the control group (p = 0.001). Median FI value was 40.0 (IQR 39.7-42.5) in the IUGR group and 45.1 (IQR 44.1-53.1) in the control group (p = 0.012). Median VFI was 2.2 (IQR 2.1-2.4) in the IUGR group and 4.8 (IQR 4.4-5.3) in the control. The 3DPD indices may be useful for examining changes in circulation in IUGR pregnancies to characterize the underlying pathology. Orv Hetil. 2017; 158(26): 1008-1013.

Efficacy of a lead based paint XRF analyzer and a commercially available colorimetric lead test kit as qualitative field tools for determining presence of lead in religious powders.

PubMed

Shah, Manthan P; Shendell, Derek G; Meng, Qingyu; Ohman-Strickland, Pamela; Halperin, William

2018-04-23

The performances of a portable X-Ray Fluorescence (XRF) lead paint analyzer (RMD LPA-1, Protec Instrument Corp., Waltham, MA) and a commercially available colorimetric lead test kit (First Alert Lead Test Kit, eAccess Solutions, Inc., Palatine, IL) were evaluated for use by local or state health departments as potential cost-effective rapid analysis or "spot test" field techniques for tentative identification of lead content in sindoor powders. For both field-sampling methods, sensitivity, specificity and predictive values varied widely for samples containing <300,000 μg/g lead. For samples containing ≥300,000 μg/g lead, the aforementioned metrics were 100% (however, the CIs had a wide range). In addition, both field sampling methods showed clear, consistent positive readings only for samples containing ≥300,000 μg/g lead. Even samples with lead content as high as 5,110 μg/g were not positively identified by either field analysis technique. The results of this study suggest the XRF analyzer and colorimetric lead test kit cannot be used as a rapid field test for sindoor by health department inspectors.

DNA aptamer-based colorimetric detection platform for Salmonella Enteritidis.

PubMed

Bayraç, Ceren; Eyidoğan, Füsun; Avni Öktem, Hüseyin

2017-12-15

Food safety is a major issue to protect public health and a key challenge is to find detection methods for identification of hazards in food. Food borne infections affects millions of people each year and among pathogens, Salmonella Enteritidis is most widely found bacteria causing food borne diseases. Therefore, simple, rapid, and specific detection methods are needed for food safety. In this study, we demonstrated the selection of DNA aptamers with high affinity and specificity against S. Enteritidis via Cell Systematic Evolution of Ligands by Exponential Enrichment (Cell-SELEX) and development of sandwich type aptamer-based colorimetric platforms for its detection. Two highly specific aptamers, crn-1 and crn-2, were developed through 12 rounds of selection with K d of 0.971µM and 0.309µM, respectively. Both aptamers were used to construct sandwich type capillary detection platforms. With the detection limit of 10 3 CFU/mL, crn-1 and crn-2 based platforms detected target bacteria specifically based on color change. This platform is also suitable for detection of S. Enteritidis in complex food matrix. Thus, this is the first to demonstrate use of Salmonella aptamers for development of the colorimetric aptamer-based detection platform in its identification and detection with naked eye in point-of-care. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluating the feasibility of using insecticide quantification kits (IQK) for estimating cyanopyrethroid levels for indoor residual spraying in Vanuatu

PubMed Central

2014-01-01

Background The quality of routine indoor residual spraying (IRS) operations is rarely assessed because of the limited choice of methods available for quantifying insecticide content in the field. This study, therefore, evaluated a user-friendly, rapid colorimetric assay for detecting insecticide content after routine IRS operations were conducted. Methods This study was conducted in Tafea Province, Vanuatu. Routine IRS was conducted with lambda cyhalothrin. Two methods were used to quantify the IRS activities: 1) pre-spray application of small felt pads and 2) post-spray removal of insecticide with adhesive. The insecticide content was quantified using a colorimetric assay (Insecticide Quantification Kit [IQK]), which involved exposing each sample to the test reagents for 15 mins. The concentration of insecticide was indicated by the depth of red colour. Results The IQK proved simple to perform in the field and results could be immediately interpreted by the programme staff. The insecticide content was successfully sampled by attaching felt pads to the house walls prior to spraying. The IRS operation was well conducted, with 83% of houses being sprayed at the target dose (20 – 30 mg AI/m2). The average reading across all houses was 24.4 ± 1.5 mg AI/m2. The results from the felt pads applied pre-spray were used as a base to compare methods for sampling insecticide from walls post-spray. The adhesive of Sellotape did not collect adequate samples. However, the adhesive of the felt pads provided accurate samples of the insecticide content on walls. Conclusion The IQK colorimetric assay proved to be a useful tool that was simple to use under realistic field conditions. The assay provided rapid information on IRS spray dynamics and spray team performance, facilitating timely decision making and reporting for programme managers. The IQK colorimetric assay will have direct applications for routine quality control in malaria control programmes globally and has the potential to improve the efficacy of vector control operations. PMID:24885084

Improvement of the uric acid determination by the carbonate method for serum and urine

PubMed Central

Eichhorn, F.; Zelmanowski, S.; Lew, E.; Rutenberg, A.; Fanias, B.

1961-01-01

An improved colorimetric procedure for determining uric acid by the carbonate method in serum and urine is described, using a 20% sodium carbonate solution with urea. Reliable results are also obtained in high concentrations of uric acid. PMID:13726059

Method 365.5 Determination of Orthophosphate in Estuarine and Coastal Waters by Automated Colorimetric Analysis

EPA Science Inventory

This method provides a procedure for the determination of low-level orthophosphate concentrations normally found in estuarine and/or coastal waters. It is based upon the method of Murphy and Riley1 adapted for automated segmented flow analysis2 in which the two reagent solutions ...

Development of a field method for measuring manganese in welding fume.

PubMed

Dale Marcy, A; Drake, Pamela L

2007-11-01

Workers who perform routine welding tasks are potentially exposed to fume that may contain manganese. Manganese may cause respiratory problems and is implicated in causing the occurrence of Parkinson-like symptoms. In this study, a field colorimetric method for extracting and measuring manganese in welding fume was developed. The method uses ultrasonic extraction with an acidic hydrogen peroxide solution to extract welding fume collected on polyvinyl chloride filters. Commercially available pre-packaged reagents are used to produce a colored solution, created by a reaction of manganese(ii) with 1-(2-pyridylazo)-2-naphthol. Absorbance measurements are then made using a portable spectrophotometer. The method detection limit and limit of quantification (LOQ) were 5.2 microg filter(-1) and 17 microg filter(-1), respectively, with a dynamic range up to 400 microg filter(-1). When the results are above the LOQ for the colorimetric method, the manganese masses are equivalent to those measured by the International Organization for Standardization Method 15202-2, which employs a strong acid digestion and analysis using inductively coupled plasma-optical emission spectrometry.

Comparison of thiaminase activity in fish using the radiometric and 4-nitrothiophenol colorimetric methods

USGS Publications Warehouse

Honeyfield, D.C.; Hanes, J.W.; Brown, L.; Kraft, C.E.; Begley, T.P.

2010-01-01

Thiaminase induced thiamine deficiency occurs in fish, humans, livestock and wild animals. A non-radioactive thiaminase assay was described in 2007, but a direct comparison with the radioactive 14C-thiamine method which has been in use for more than 30years has not been reported. The objective was to measure thiaminase activity in forage fish (alewife Alosa pseudoharengus, rainbow smelt Osmerus mordax, and slimy sculpin Cottus cognatus) consumed by predators that manifest thiamine deficiency using both methods. Modifications were made to the colorimetric assay to improve repeatability. Modification included a change in assay pH, enhanced sample clean-up, constant assay temperature (37??C), increase in the concentration of 4-nitrothiophenol (4NTP) and use of a spectrophotometer fitted with a 0.2cm cell. A strong relationship between the two assays was found for 51 alewife (R2=0.85), 36 smelt (R2=0.87) and 20 sculpin (R2=0.82). Thiaminase activity in the colorimetric assay was about 1000 times higher than activity measured by the radioactive method. Application of the assay to fish species from which no thiaminase activity has previously been reported resulted in no 4NTP thiaminase activity being found in bloater Coregonus hoyi, lake trout Salvelinus namaycusch, steelhead trout Oncorhynchus mykiss or Chinook salmon Oncorhynchus tshawytscha. In species previously reported to contain thiaminase, 4NTP thiaminase activity was measured in bacteria Paenibacillus thiaminolyticus, gizzard shad Dorosoma cepedianum, bracken fern Pteridium aquilinum, quagga mussel Dreissena bugensis and zebra mussels D. polymorpha. ?? 2010.

Antibody modified gold nanoparticles for fast and selective, colorimetric T7 bacteriophage detection.

PubMed

Lesniewski, Adam; Los, Marcin; Jonsson-Niedziółka, Martin; Krajewska, Anna; Szot, Katarzyna; Los, Joanna M; Niedziolka-Jonsson, Joanna

2014-04-16

Herein, we report a colorimetric immunosensor for T7 bacteriophage based on gold nanoparticles modified with covalently bonded anti-T7 antibodies. The new immunosensor allows for a fast, simple, and selective detection of T7 virus. T7 virions form immunological complexes with the antibody modified gold nanoparticles which causes them to aggregate. The aggregation can be observed with the naked eye as a color change from red to purple, as well as with a UV-vis spectrophotometer. The aggregate formation was confirmed with SEM imaging. Sensor selectivity against the M13 bacteriophage was demonstrated. The limit of detection (LOD) is 1.08 × 10(10) PFU/mL (18 pM) T7. The new method was compared with a traditional plaque test. In contrast to biological tests the colorimetric method allows for detection of all T7 phages, not only those biologically active. This includes phage ghosts and fragments of virions. T7 virus has been chosen as a model organism for adenoviruses. The described method has several advantages over the traditional ones. It is much faster than a standard plaque test. It is more robust since no bacteria-virus interactions are utilized in the detection process. Since antibodies are available for a large variety of pathogenic viruses, the described concept is very flexible and can be adapted to detect many different viruses, not only bacteriophages. Contrary to the classical immunoassays, it is a one-step detection method, and no additional amplification, e.g., enzymatic, is needed to read the result.

Spectrophotometric, colorimetric and visually detection of Pseudomonas aeruginosa ETA gene based gold nanoparticles DNA probe and endonuclease enzyme

NASA Astrophysics Data System (ADS)

Amini, Bahram; Kamali, Mehdi; Salouti, Mojtaba; Yaghmaei, Parichehreh

2018-06-01

Colorimetric DNA detection is preferred over other methods for clinical molecular diagnosis because it does not require expensive equipment. In the present study, the colorimetric method based on gold nanoparticles (GNPs) and endonuclease enzyme was used for the detection of P. aeruginosa ETA gene. Firstly, the primers and probe for P. aeruginosa exotoxin A (ETA) gene were designed and checked for specificity by the PCR method. Then, GNPs were synthesized using the citrate reduction method and conjugated with the prepared probe to develop the new nano-biosensor. Next, the extracted target DNA of the bacteria was added to GNP-probe complex to check its efficacy for P. aeruginosa ETA gene diagnosis. A decrease in absorbance was seen when GNP-probe-target DNA cleaved into the small fragments of BamHI endonuclease due to the weakened electrostatic interaction between GNPs and the shortened DNA. The right shift of the absorbance peak from 530 to 562 nm occurred after adding the endonuclease. It was measured using a UV-VIS absorption spectroscopy that indicates the existence of the P. aeruginosa ETA gene. Sensitivity was determined in the presence of different concentrations of target DNA of P. aeruginosa. The results obtained from the optimized conditions showed that the absorbance value has linear correlation with concentration of target DNA (R: 0.9850) in the range of 10-50 ng mL-1 with the limit detection of 9.899 ng mL-1. Thus, the specificity of the new method for detection of P. aeruginosa was established in comparison with other bacteria. Additionally, the designed assay was quantitatively applied to detect the P. aeruginosa ETA gene from 103 to 108 CFU mL-1 in real samples with a detection limit of 320 CFU mL-1.

Methods for the isolation, culture and assessment of the status of anaerobic rumen chytrids in both in vitro and in vivo systems.

PubMed

Rezaeian, Mohammad; Beakes, Gordon W; Parker, David S

2004-10-01

Anaerobic fungi were isolated from both the rumen and faeces of nine sheep and a cow. A reliable and simple method for the isolation of anaerobic fungi using 24 h rumen incubated milled straw as the inoculum source was developed. We also evaluate the use of chitin measurements as an assay of rumen fungal biomass. Chitin levels were determined from various sample sources (milled barley straw used as the fungal culture substrate in vitro; plant particulate digests from the rumen (PLP) and centrifuged strained rumen fluid (CSRF) using both HPLC and colorimetric methods. Both methods were highly correlated and consequently the simpler colorimetric method was adopted for subsequent studies. There was also a high degree of correlation between anaerobic fungal cellulase activities with the assayed chitin content of milled barley straw cultures over 12 d of an in vitro experiment. The colorimetric chitin assay protocol was then used to assess the diurnal variation and abundance of rumen fungi in in vivo assays. We assessed the distribution of chitin (mg g(-1) dry matter) in various fractions of the strained rumen fluid (SRF) and PLP samples from the rumen of sheep. Chitin was detected in all fractions of strained rumen fluid but the main source of chitin in the samples may be attributed to the fungal biomass. We did not detect any significant differences in chitin levels over a 24 h sampling period. Finally, an SEM study on subsamples of milled straw and plant particulate matter used in the chitin assays, revealed that the pattern of the fungal development on substrate material differs from the culture medium to the rumen.

Polymorphism of TS 3'-UTR predicts survival of Chinese advanced gastric cancer patients receiving first-line capecitabine plus paclitaxel.

PubMed

Gao, J; He, Q; Hua, D; Mao, Y; Li, Y; Shen, L

2013-08-01

Capecitabine-containing chemotherapy was widely used in clinic medication. We investigated the association of the thymidylate synthase (TS), methylenetetrahydrofolate reductase (MTHFR), and dihydropyrimidine dehydrogenase (DPD) polymorphisms with the clinical outcome of Chinese advanced gastric cancer patients receiving first-line capecitabine plus paclitaxel. Blood samples were collected prior to treatment from 125 patients with advanced gastric cancer and the TS (two or three repeats of a 28 bp sequence in 5'-untranslated region and 6 bp insertion or deletion in 3'-untranslated region), MTHFR (C677T) and DPD (IVS14+1G > A) polymorphisms were determined using PCR amplification and Sanger sequencing. The median age of 125 patients was 58 years (range, 23-76) with female 42 and male 83, and the response rate, median progression-free survival and overall survival (OS) were 43.2 %, 5.2 and 11.0 months. The median OS in patients with TS ins6/ins6 genotype (6.8 months) was significantly shorter than those in patients with ins6/del6 (11.0 months, P = 0.016) and del6/del6 (11.5 months, P = 0.039) genotypes. Cox multivariate analysis also showed that TS ins6/ins6 genotype was the independent poor OS predictor (P = 0.001, HR = 3.182). No significant associations were found between the polymorphisms of TS 5'-UTR/MTHFR and clinical outcome, and no IVS14+1G > A polymorphism of DPD was found in this study. We first reported that TS 3'-UTR ins6/ins6 genotype could predict the poor survival of advanced gastric cancer patients treated with capecitabine plus paclitaxel, which would be further verified in a large multicenter study.

Variability of collagen crosslinks: impact of sample collection period

NASA Technical Reports Server (NTRS)

Smith, S. M.; Dillon, E. L.; DeKerlegand, D. E.; Davis-Street, J. E.

2004-01-01

Because of the variability of collagen crosslinks, their use as markers for bone resorption is often criticized. We hypothesized that the variability could be reduced by collecting urine for 24 hours (or longer) instead of using single voids, and by not normalizing to creatinine. Urine samples were collected from 22 healthy subjects during two or more 24-hour periods. Each 24-hour pool and each 2nd void of the day were analyzed for N-telopeptide (NTX), pyridinium (PYD), and deoxypyridinoline (DPD) crosslinks. Data were analyzed by using linear regression. For NTX, R2 for the two, 2nd-void samples (n = 38) was 0.55, whereas R2 for the two 24-hour pools was 0.51 or 0.52, expressed per day or per creatinine. For PYD and DPD, R2 for the 2nd-void samples was 0.26 and 0.18, R2 for the 24-hour pools expressed per day was 0.58 and 0.74, and R2 for the 24-hour pools expressed per creatinine was 0.65 and 0.76, respectively. Regression of the 2nd void and the corresponding 24-hour pool, expressed per day, yielded R2 = 0.19, 0.19, and 0.08, for NTX, PYD, and DPD, respectively (n = 76 each). For the 2nd-void sample and its corresponding 24-hour pool, expressed per creatinine, R2 = 0.24, 0.33, and 0.08, respectively. In a separate study, the coefficient of variation for NTX was reduced (P < 0.05) when data from more than one 24-hour collection were combined. Thus, the variability inherent in crosslink determinations can be reduced by collecting urine for longer periods. In research studies, the high variability of single-void collections, compounded by creatinine normalization, may alter or obscure findings.

Amino acid supplementation alters bone metabolism during simulated weightlessness

NASA Technical Reports Server (NTRS)

Zwart, S. R.; Davis-Street, J. E.; Paddon-Jones, D.; Ferrando, A. A.; Wolfe, R. R.; Smith, S. M.

2005-01-01

High-protein and acidogenic diets induce hypercalciuria. Foods or supplements with excess sulfur-containing amino acids increase endogenous sulfuric acid production and therefore have the potential to increase calcium excretion and alter bone metabolism. In this study, effects of an amino acid/carbohydrate supplement on bone resorption were examined during bed rest. Thirteen subjects were divided at random into two groups: a control group (Con, n = 6) and an amino acid-supplemented group (AA, n = 7) who consumed an extra 49.5 g essential amino acids and 90 g carbohydrate per day for 28 days. Urine was collected for n-telopeptide (NTX), deoxypyridinoline (DPD), calcium, and pH determinations. Bone mineral content was determined and potential renal acid load was calculated. Bone-specific alkaline phosphatase was measured in serum samples collected on day 1 (immediately before bed rest) and on day 28. Potential renal acid load was higher in the AA group than in the Con group during bed rest (P < 0.05). For all subjects, during bed rest urinary NTX and DPD concentrations were greater than pre-bed rest levels (P < 0.05). Urinary NTX and DPD tended to be higher in the AA group (P = 0.073 and P = 0.056, respectively). During bed rest, urinary calcium was greater than baseline levels (P < 0.05) in the AA group but not the Con group. Total bone mineral content was lower after bed rest than before bed rest in the AA group but not the Con group (P < 0.05). During bed rest, urinary pH decreased (P < 0.05), and it was lower in the AA group than the Con group. These data suggest that bone resorption increased, without changes in bone formation, in the AA group.

Changes in markers of bone formation and resorption in a bed rest model of weightlessness

NASA Technical Reports Server (NTRS)

Lueken, S. A.; Arnaud, S. B.; Taylor, A. K.; Baylink, D. J.

1993-01-01

To study the mechanism of bone loss in physical unloading, we examined indices of bone formation and bone resorption in the serum and urine of eight healthy men during a 7 day -6 degrees head-down tilt bed rest. Prompt increases in markers of resorption--pyridinoline (PD), deoxypyridinoline (DPD), and hydroxyproline (Hyp)/g creatinine--during the first few days of inactivity were paralleled by tartrate-resistant acid phosphatase (TRAP) with significant increases in all these markers by day 4 of bed rest. An index of formation, skeletal alkaline phosphatase (SALP), did not change during bed rest and showed a moderate 15% increase 1 week after reambulation. In contrast to SALP, serum osteocalcin (OC) began increasing the day preceding the increase in Hyp, remained elevated for the duration of the bed rest, and returned to pre-bed rest values within 5 days of reambulation. Similarly, DPD increased significantly at the onset of bed rest, remained elevated for the duration of bed rest, and returned to pre-bed rest levels upon reambulation. On the other hand, the other three indices of resorption, Hyp, PD, and TRAP, remained elevated for 2 weeks after reambulation. The most sensitive indices of the levels of physical activity proved to be the noncollagenous protein, OC, and the collagen crosslinker, DPD. The bed rest values of both these markers were significantly elevated compared to both the pre-bed rest values and the post-bed rest values. The sequence of changes in the circulating markers of bone metabolism indicated that increases in serum OC are the earliest responses of bone to head-down tilt bed rest.

A biodegradable colorimetric film for rapid low-cost field determination of formaldehyde contamination by digital image colorimetry.

PubMed

Wongniramaikul, Worawit; Limsakul, Wadcharawadee; Choodum, Aree

2018-05-30

A biodegradable colorimetric film was fabricated on the lid of portable tube for in-tube formaldehyde detection. Based on the entrapment of colorimetric reagents within a thin film of tapioca starch, the yellow reaction product was observed with formaldehyde. Intensity of the blue channel from the digital image of yellow product showed a linear relationship in the range of 0-25 mg L -1 with low detection limit of 0.7 ± 0.1 mg L -1 . Inter-day precision of 0.61-3.10%RSD were obtained with less than 4.2% relative error from control samples. The developed method was applied for various food samples in Phuket and formaldehyde concentration range was non-detectable to 1.413 mg kg -1 . The quantified concentrations of formaldehyde in fish and squid samples provided relative errors of -7.7% and +10.8% compared to spectrophotometry. This low cost sensor (∼0.04 USD/test) with digital image colorimetry was thus an effective alternative for formaldehyde detection in food sample. Copyright © 2018 Elsevier Ltd. All rights reserved.

A Simple Assay for Ultrasensitive Colorimetric Detection of Ag⁺ at Picomolar Levels Using Platinum Nanoparticles.

PubMed

Wang, Yi-Wei; Wang, Meili; Wang, Lixing; Xu, Hui; Tang, Shurong; Yang, Huang-Hao; Zhang, Lan; Song, Hongbo

2017-11-02

In this work, uniformly-dispersed platinum nanoparticles (PtNPs) were synthesized by a simple chemical reduction method, in which citric acid and sodium borohydride acted as a stabilizer and reducer, respectively. An ultrasensitive colorimetric sensor for the facile and rapid detection of Ag⁺ ions was constructed based on the peroxidase mimetic activities of the obtained PtNPs, which can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H₂O₂ to produce colored products. The introduced Ag⁺ would be reduced to Ag⁰ by the capped citric acid, and the deposition of Ag⁰ on the PtNPs surface, can effectively inhibit the peroxidase-mimetic activity of PtNPs. Through measuring the maximum absorption signal of oxidized TMB at 652 nm, ultra-low detection limits (7.8 pM) of Ag⁺ can be reached. In addition to such high sensitivity, the colorimetric assay also displays excellent selectivity for other ions of interest and shows great potential for the detection of Ag⁺ in real water samples.

Detection and differentiation of Campylobacter jejuni and Campylobacter coli in broiler chicken samples using a PCR/DNA probe membrane based colorimetric detection assay.

PubMed

O'Sullivan, N A; Fallon, R; Carroll, C; Smith, T; Maher, M

2000-02-01

Campylobacter enteritis in humans has been linked to consumption of poultry meat. Surveys show that 30-100% of poultry harbour Campylobacter as normal flora of the digestive tract which indicates a need to identify prevalent organism types in flocks and trace their epidemiology. In this study we describe a Campylobacter genus specific polymerase chain reaction (PCR) assay, amplifying the 16 S-23 S rRNA intergenic spacer region with an internal Campylobacter genus specific DNA probe and species specific probes for Campylobacter jejuni and Campylobacter coli designed for confirmation of the amplified PCR products by Southern blot and colorimetric reverse hybridization assays. The specificity of this assay was established by testing a range of food pathogens. Broiler chicken samples were tested following presumptive positive identification by the Malthus System V analyser (Malthus Instruments, UK). The combined PCR and colorimetric reverse hybridization assay is easy to perform and faster than conventional methods for confirmation and identification of Campylobacter species. Copyright 2000 Academic Press.

Rapid and selective lead (II) colorimetric sensor based on azacrown ether-functionalized gold nanoparticles

NASA Astrophysics Data System (ADS)

Alizadeh, A.; Khodaei, M. M.; Karami, Ch; Workentin, M. S.; Shamsipur, M.; Sadeghi, M.

2010-08-01

A gold nanoparticle (AuNPs)-based simple and fast colorimetric sensor for selective detecting of Pb(II) in aqueous solution has been developed. Monodisperse AuNPs (approx. 2.0 nm diameter) has been prepared facilely and further modified with an alkanethiol-bearing monoazacrown ether terminus. These AuNPs are shown to selectively sense Pb2 + through color change, which is visually discernible by an appearance of the surface plasmon band (SPB) at 520 nm. The recognition mechanism is attributed to the unique structure of the monoazacrown ether attached to AuNPs and metal sandwich coordination between two azacrown ether moieties that are attached to separate nanoparticles. This inter-particle cross-linking results in an aggregation and apparent color change from brown to purple. Additionally, TEM experiments support the optical absorption data proving the aggregation between azacrown ether-capped gold nanoparticles. This AuNP-based colorimetric assay is a facile and robust method and allows fast detection of Pb2 + at ambient temperatures. More importantly, the developed technique does not utilize enzymatic reactions, light-sensitive dye molecules, lengthy protocols or sophisticated instrumentation.

Naked eye screening of 11 phenolic compounds and colorimetric determination using polydiacetylene vesicles with α-cyclodextrin

NASA Astrophysics Data System (ADS)

Anekthirakun, Pimpimon; Sukwattanasinitt, Mongkol; Tuntulani, Thawatchai; Imyim, Apichat

2013-07-01

The colorimetric response (CR) of poly(10,12-pentacosadiynoic acid) vesicles (PPCDA) induced by α-cyclodextrin (α-CD) in an aqueous solution has been studied. Various parameters affecting the CR, such as response time and concentration were investigated. The blue color of 0.01 mM PPCDA solution became pinkish red with the addition of α-CD at the concentration higher than 3 mM. The inhibition of the color transition from blue to red was investigated using 11 phenolic compounds. The color transition could be inhibited and observed by naked eye in the presence of 4 phenolic compounds, i.e. 4-nitrophenol (4-NP) and 4-bromophenol (4-BP) and 4-chlorophenol (4-CP) and 3-nitrophenol (3-NP). A colorimetric method for the determination of these compounds was validated and applied for surface water analysis. The linear range from the plot of CR against phenolic compounds concentration was in the order of 0.5-2.0 mM with R2 more than 0.99. The recoveries were 90-95% with good precision (1-4%RSD, n = 10).

A colorimetric method for the determination of carboxyhaemoglobin over a wide range of concentrations

PubMed Central

Trinder, P.; Harper, F. E.

1962-01-01

A colorimetric technique for the determination of carboxyhaemoglobin in blood is described. Carbon monoxide released from blood in a standard Conway unit reacts with palladous chloride/arsenomolybdate solution to produce a blue colour. Using 0·5 to 2 ml. of blood, the method will estimate carboxyhaemoglobin accurately at levels from 0·1% to 100% of total haemoglobin and in the presence of other abnormal pigments. A number of methods are available for the determination of carboxyhaemoglobin; none is accurate below a concentration of 1·5 g. carboxyhaemoglobin per 100 ml. but for most clinical purposes this is not important. For forensic purposes and occasionally in clinical use, an accurate determination of carboxyhaemoglobin below 750 mg. per 100 ml. may be required and no really satisfactory method is at present available. Some time ago when it was important to know whether a person who was found dead in a burning house had died before or after the fire had started, we became interested in developing a method which would determine accurately carboxyhaemoglobin at levels of 750 mg. per 100 ml. PMID:13922505

Automated method for study of drug metabolism

NASA Technical Reports Server (NTRS)

Furner, R. L.; Feller, D. D.

1973-01-01

Commercially available equipment can be modified to provide automated system for assaying drug metabolism by continuous flow-through. System includes steps and devices for mixing drug with enzyme and cofactor in the presence of pure oxygen, dialyzing resulting metabolite against buffer, and determining amount of metabolite by colorimetric method.

REDUCTION OF NITRATE THROUGH THE USE OF NITRATE REDUCTASE FOR THE SMARTCHEM AUTOANALYZER

EPA Science Inventory

The standard method for the determination of nitrate in drinking water, USEPA Method 353.2 “Determination of Nitrate-Nitrite by Automated Colorimetry,” employs cadmium as the reductant for the conversion of nitrate to nitrite. The nitrite is then analyzed colorimetrically by way ...

Sol-Gel Matrices For Direct Colorimetric Detection Of Analytes

DOEpatents

Charych, Deborah H.; Sasaki, Darryl; Yamanaka, Stacey

2002-11-26

The present invention relates to methods and compositions for the direct detection of analytes using color changes that occur in immobilized biopolymeric material in response to selective binding of analytes to their surface. In particular, the present invention provides methods and compositions related to the encapsulation of biopolymeric material into metal oxide glass using the sol-gel method.

Sol-gel matrices for direct colorimetric detection of analytes

DOEpatents

Charych, Deborah H.; Sasaki, Darryl; Yamanaka, Stacey

2000-01-01

The present invention relates to methods and compositions for the direct detection of analytes using color changes that occur in immobilized biopolymeric material in response to selective binding of analytes to their surface. In particular, the present invention provides methods and compositions related to the encapsulation of biopolymeric material into metal oxide glass using the sol-gel method.

Highly selective and sensitive colorimetric determination of Cr3 + ion by 4-amino-5-methyl-4H-1,2,4-triazole-3-thiol functionalized Au nanoparticles

NASA Astrophysics Data System (ADS)

Shahrivari, Shima; Faridbod, Farnoush; Ganjali, Mohammad Reza

2018-02-01

In this work, a rapid, selective naked eyes colorimetric chemical probe for the detection of Cr3 + was developed based on functionalization of gold nanoparticles. For this purpose, surface of Au NPs was functionalized using 4-amino-5-methyl-4H-1,2,4-triazole-3-thiol (AMTT). Through colorimetric studies, it was found that in the presence of Cr3 + ions, AMTT-Au NPs instantly aggregated and resulted in a color change of the solution from red to blue. The color change of AMTT-Au NPs due to the aggregation induced by Cr3 + can be seen with even naked eyes and also by UV-Vis spectroscopy with a detection limit of 1.8 μM and 0.1 μM, respectively. AMTT-Au NPs showed excellent selectivity toward Cr3 + compared to other cations tested, including K+, Na+, Cs+, Fe3 +, Ni2 +, Cu2 +, Co2 +, Zn2 +, Ba2 +, Ca2 +, Mg2 +, Cd2 +, Pb2 +, Hg2 + ions and especially all trivalent lanthanide ions. The absorbance ratio (A650/A525) was linear toward Cr3 + concentrations in the range of 0.6-6.1 μM (R2 = 0.996). The best response was achieved over a pH range of 3-5. Furthermore, the proposed colorimetric method based on AMTT-Au NPs was successfully used for Cr3 + ion detection in plasma sample and some water samples.

Colorimetric carbon dioxide detector to determine accidental tracheal feeding tube placement.

PubMed

Howes, Daniel W; Shelley, Eric S; Pickett, William

2005-04-01

To determine the accuracy of colorimetric CO2 detection compared to the reference standard two-step radiological confirmation of feeding tube position. A prospective study was conducted with patients presenting to a 21-bed medical-surgical intensive care unit. An adapter was developed using an endotracheal tube adapter to connect a colorimetric CO2 detector to a feeding tube in an airtight manner. In part I of the study a feeding tube connected to the colorimeter was inserted into the endotracheal tubes of ten ventilated patients to test the device's ability to detect tracheal placement. In part II patients undergoing feeding tube insertion had tube position confirmed with the colorimeter as well as the reference standard two-step x-ray. In phase I the colorimeter correctly identified tracheal placement in all ten patients. In phase II 93/100 procedures ultimately were eligible; the colorimeter had a sensitivity of 0.88 (95% confidence interval: 0.65-1.00) and specificity of 0.99 (0.97-1.00). The device missed one of the eight tracheal placements. Agreement between the colorimeter and two-step x-ray interpretations was excellent (Kappa 0.86; standard error 0.10). We describe a novel, convenient method to confirm esophageal feeding tube placement. The device is easily assembled and inexpensive, but should not be reused. Colorimetric determination of tracheal feeding tube placement with this device has excellent agreement with the reference standard two-step radiological technique.

Smartphone-based colorimetric analysis for detection of saliva alcohol concentration.

PubMed

Jung, Youngkee; Kim, Jinhee; Awofeso, Olumide; Kim, Huisung; Regnier, Fred; Bae, Euiwon

2015-11-01

A simple device and associated analytical methods are reported. We provide objective and accurate determination of saliva alcohol concentrations using smartphone-based colorimetric imaging. The device utilizes any smartphone with a miniature attachment that positions the sample and provides constant illumination for sample imaging. Analyses of histograms based on channel imaging of red-green-blue (RGB) and hue-saturation-value (HSV) color space provide unambiguous determination of blood alcohol concentration from color changes on sample pads. A smartphone-based sample analysis by colorimetry was developed and tested with blind samples that matched with the training sets. This technology can be adapted to any smartphone and used to conduct color change assays.

Simple and Sensitive Paper-Based Device Coupling Electrochemical Sample Pretreatment and Colorimetric Detection.

PubMed

Silva, Thalita G; de Araujo, William R; Muñoz, Rodrigo A A; Richter, Eduardo M; Santana, Mário H P; Coltro, Wendell K T; Paixão, Thiago R L C

2016-05-17

We report the development of a simple, portable, low-cost, high-throughput visual colorimetric paper-based analytical device for the detection of procaine in seized cocaine samples. The interference of most common cutting agents found in cocaine samples was verified, and a novel electrochemical approach was used for sample pretreatment in order to increase the selectivity. Under the optimized experimental conditions, a linear analytical curve was obtained for procaine concentrations ranging from 5 to 60 μmol L(-1), with a detection limit of 0.9 μmol L(-1). The accuracy of the proposed method was evaluated using seized cocaine samples and an addition and recovery protocol.

A new rhodamine-based colorimetric chemosensor for naked-eye detection of Cu2 + in aqueous solution

NASA Astrophysics Data System (ADS)

Hu, Yang; Zhang, Jing; Lv, Yuan-Zheng; Huang, Xiao-Huan; Hu, Sheng-li

2016-03-01

A new colorimetric probe 1 based on rhodamine B lactam was developed for naked-eye detection of Cu2 +. The optical feature of 1 for Cu2 + was investigated by UV-vis absorption spectroscopy. Upon the addition of Cu2 +, the 1 displayed a distinct color change from colorless to pink, which can be directly detected by the naked eye. The stoichiometry of 1 to Cu2 + complex was found to be 1:1 and the naked-eye detection limit was determined as low as 2 μM. The results suggest that the probe 1 may provide a convenient method for visual detection of Cu2 + with high sensitivity.

Hydrogen bonding recognition and colorimetric detection of isoprenaline using 2-amino-5-mercapto-1,3,4-thiadiazol functionalized gold nanoparticles

NASA Astrophysics Data System (ADS)

Khezri, Somayeh; Bahram, Morteza; Samadi, Naser

2018-01-01

In this paper, we describe a rapid, low-cost and highly sensitive colorimetric method for the detection of isoprenaline, based on 2-amino-5-mercapto-1,3,4-thiadiazol (AMTD) functionalized gold nanoparticles (AMTD-AuNPs) as a sensing element. Hydrogen bonding interaction between isoprenaline and AMTD resulted in the aggregation of AuNPs and a consequent color change of AuNPs from red to blue. The concentration of isoprenaline could be detected with the naked eye or a UV-visible spectrometer. Results showed that the absorbance ratio (A650/A524) was linear with isoprenaline concentrations in the range of 0.2 to 2.6 μM (R = 0.997). The detection limit of this method was 0.08 μM. The proposed method is simple, without using complicated instruments and adding salts for enhancing sensitivity. This probe could be successfully applied to the determination of isoprenaline in human serum samples and urine samples after deproteinization.

Improvement of fish freshness determination method by the application of amorphous freeze-dried enzymes.

PubMed

Srirangsan, Paveena; Hamada-Sato, Naoko; Kawai, Kiyoshi; Watanabe, Manabu; Suzuki, Toru

2010-12-08

Alkaline phosphatase (ALP), nucleoside phosphorylase (NP), and xanthine oxidase (XOD) were used in a colorimetric method for evaluation of fish freshness based on the Ki value. Two enzyme mixtures, NP-XOD and ALP-NP-XOD, were prepared with a color developing agent, and stabilities of the enzymes were improved by freeze-drying with glass-forming additives, i.e., sucrose and sucrose-gelatin. As a result, a linear relationship was obtained between the Ki values determined by the developed colorimetric method and a conventional high-performance liquid chromatography with a high correlation coefficient of 0.997. All enzyme samples containing the additive(s) were amorphous, and higher enzymes activities were maintained compared to those freeze-dried without an additive. Sucrose-gelatin/enzyme mixtures showed higher glass transition temperature; consequently, the enzymes were better stabilized than the sucrose/enzyme formulations. Using the sucrose-gelatin/enzyme mixture, Ki values of fish meat could be accurately determined even after 6-month storage of the dried enzymes at 40 °C.

Selective spectrophotometric determination of TNT using a dicyclohexylamine-based colorimetric sensor.

PubMed

Erçağ, Erol; Uzer, Ayşem; Apak, Reşat

2009-05-15

Because of the extremely heterogeneous distribution of explosives in contaminated soils, on-site colorimetric methods are efficient tools to assess the nature and extent of contamination. To meet the need for rapid and low-cost chemical sensing of explosive traces or residues in soil and post-blast debris, a colorimetric absorption-based sensor for trinitrotoluene (TNT) determination has been developed. The charge-transfer (CT) reagent (dicyclohexylamine, DCHA) is entrapped in a polyvinylchloride (PVC) polymer matrix plasticised with dioctylphtalate (DOP), and moulded into a transparent sensor membrane sliced into test strips capable of sensing TNT showing an absorption maximum at 530 nm when placed in a 1-mm spectrophotometer cell. The sensor gave a linear absorption response to 5-50 mg L(-1) TNT solutions in 30% aqueous acetone with limit of detection (LOD): 3 mg L(-1). The sensor is only affected by tetryl, but not by RDX, pentaerythritoltetranitrate (PETN), dinitrotoluene (DNT), and picric acid. The proposed method was statistically validated for TNT assay against high performance liquid chromatography (HPLC) using a standard sample of Comp B. The developed sensor was relatively resistant to air and water, was of low-cost and high specificity, gave a rapid and reproducible response, and was suitable for field use of TNT determination in both dry and humid soil and groundwater with a portable colorimeter.

A colorimetric probe based on desensitized ionene-stabilized gold nanoparticles for single-step test for sulfate ions.

PubMed

Arkhipova, Viktoriya V; Apyari, Vladimir V; Dmitrienko, Stanislava G

2015-03-15

Desensitized ionene-stabilized gold nanoparticles have been prepared and applied as a colorimetric probe for the single-step test for sulfate ions at the relatively high concentration level. The approach is based on aggregation of the nanoparticles leading to the change in absorption spectra and color of the solution. These nanoparticles are characterized by the decreased sensitivity due to both electrostatic and steric stabilization, which allows for simple, and rapid direct single-step determination of sulfate at the relatively high concentration level in real water samples without sample pretreatment or dilution. Influence of different factors (the time of interaction, pH, the concentrations of sulfate ions and the nanoparticles) on the aggregation and analytical performance of the procedure was investigated. The method allows for the determination of sulfate ions in the mass range of 0.2-0.4 mg with RSD of 5% from the sample volume of less than 2 mL. It has a sharp dependence of the colorimetric response on the concentration of sulfate, which makes it prospective for indicating deviations of the sulfate concentration regarding some declared value chosen within the above range. The time of the analysis is 2 min. The method was applied to the analysis of mineral water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Colorimetric test-systems for creatinine detection based on composite molecularly imprinted polymer membranes.

PubMed

Sergeyeva, T A; Gorbach, L A; Piletska, E V; Piletsky, S A; Brovko, O O; Honcharova, L A; Lutsyk, O D; Sergeeva, L M; Zinchenko, O A; El'skaya, A V

2013-04-03

An easy-to-use colorimetric test-system for the efficient detection of creatinine in aqueous samples was developed. The test-system is based on composite molecularly imprinted polymer (MIP) membranes with artificial receptor sites capable of creatinine recognition. A thin MIP layer was created on the surface of microfiltration polyvinylidene fluoride (PVDF) membranes using method of photo-initiated grafting polymerization. The MIP layer was obtained by co-polymerization of a functional monomer (e.g. 2-acrylamido-2-methyl-1-propanesulfonic acid, itaconic acid or methacrylic acid) with N, N'-methylenebisacrylamide as a cross-linker. The choice of the functional monomer was based on the results of computational modeling. The creatinine-selective composite MIP membranes were used for measuring creatinine in aqueous samples. Creatinine molecules were selectively adsorbed by the MIP membranes and quantified using color reaction with picrates. The intensity of MIP membranes staining was proportional to creatinine concentration in an analyzed sample. The colorimetric test-system based on the composite MIP membranes was characterized with 0.25 mM detection limit and 0.25-2.5mM linear dynamic range. Storage stability of the MIP membranes was estimated as at least 1 year at room temperature. As compared to the traditional methods of creatinine detection the developed test-system is characterized by simplicity of operation, small size and low cost. Copyright © 2013 Elsevier B.V. All rights reserved.

Depressive Personality Disorder: A Comparison of Three Self-Report Measures

ERIC Educational Resources Information Center

Miller, Joshua D.; Tant, Adam; Bagby, R. Michael

2010-01-01

Depressive personality disorder (DPD) was included in the appendix of the "Diagnostic and Statistical Manual of Mental Disorders", Fourth Edition ("DSM-IV") for further study. Questions abound regarding this disorder in terms of its distinctiveness from extant diagnostic constructs and clinical significance.This study examines…

Portable and low-cost colorimetric office paper-based device for phenacetin detection in seized cocaine samples.

PubMed

da Silva, Gabriela O; de Araujo, William R; Paixão, Thiago R L C

2018-01-01

An office paper-based colorimetric device is proposed as a portable, rapid, and low-cost sensor for forensic applications aiming to detect phenacetin used as adulterant in illicit seized materials such as cocaine. The proposed method uses white office paper as the substrate and wax printing technology to fabricate the detection zones. Based on the optimum conditions, a linear analytical curve was obtained for phenacetin concentrations ranging from 0 to 64.52µgmL ‒1 , and the straight line was in accordance with the following equation: (Magenta percentage color) = 1.19 + 0.458 (C Phe /µgmL ‒1 ), R 2 = 0.990. The limit of detection was calculated as 3.5µgmL ‒1 (3σ/slope). The accuracy of the proposed method was evaluated using real seized cocaine samples and the spike-recovery procedure. Copyright © 2017 Elsevier B.V. All rights reserved.

Colorimetric analysis of pigmented skin lesions: a pilot study with the Visi-Chroma VC-100 device.

PubMed

Vereecken, P; Mommaerts, M; Duez, C; Petein, M; Laporte, M; Hubinon, J-L; Heenen, M

2006-01-01

Definition of the colour of pigmented skin lesions (PSLs) with the naked eye remains subjective and may be influenced by lighting. This problem underlines the usefulness of instrumental assessments such as epiluminescence microscopy and colorimetric devices. We describe here a new method of colour analysis of PSLs with the Visi-Chroma VC-100 device, which illuminates the surface of the skin with white light-emitting diodes (LEDs) and analyses the reflected light by a red-green-blue (RGB) charge-coupled device (CCD) colour camera. Twenty-one PSLs to be excised for cosmetic or medical reasons were analysed by this device with clinicopathological correlation. This method is feasible and might be useful to assess the colour of PSLs and allow comparisons for changes over time. Further studies are needed to determine the usefulness of this device in clinical practice.

Colorimetric As (V) detection based on S-layer functionalized gold nanoparticles.

PubMed

Lakatos, Mathias; Matys, Sabine; Raff, Johannes; Pompe, Wolfgang

2015-11-01

Herein, we present simple and rapid colorimetric and UV/VIS spectroscopic methods for detecting anionic arsenic (V) complexes in aqueous media. The methods exploit the aggregation of S-layer-functionalized spherical gold nanoparticles of sizes between 20 and 50 nm in the presence of arsenic species. The gold nanoparticles were functionalized with oligomers of the S-layer protein of Lysinibacillus sphaericus JG-A12. The aggregation of the nanoparticles results in a color change from burgundy-red for widely dispersed nanoparticles to blue for aggregated nanoparticles. A detailed signal analysis was achieved by measuring the shift of the particle plasmon resonance signal with UV/VIS spectroscopy. To further improve signal sensitivity, the influence of larger nanoparticles was tested. In the case of 50 nm gold nanoparticles, a concentration of the anionic arsenic (V) complex lower than 24 ppb was detectable. Copyright © 2015 Elsevier B.V. All rights reserved.

The determination of N-nitrosodiethanolamine (NDELA) at trace levels in shampoos and skin creams by a simple, rapid colorimetric method.

PubMed

Telling, G M; Dunnett, P C

1981-10-01

Synopsis A technique is described for the rapid determination of N-nitrosodiethanolamine (NDELA) in shampoos, skin creams and similar products based on aqueous extraction, partition into ethyl acetate and colorimetric determination using the Eisenbrand-Preussman cleavage reaction. Recoveries of NDELA added at levels of 5-100 mug kg(-1) to a range of shampoo and cream types ranged from 90-101%. The limit of determination for the method is 2.5 mug kg(-1). Observations on the application of a thermal energy analyser linked to a gas chromatograph are also reported. Application of the technique to a survey of a wide range of shampoo and skin cream types showed that levels of total N-nitroso compounds were less than 30 mug kg(-1) in < 90% of samples and, in many cases, less than 2.5 mug kg-1.

A Sensitive Microplate Assay for Lipase Activity Measurement Using Olive Oil Emulsion Substrate: Modification of the Copper Soap Colorimetric Method.

PubMed

Mustafa, Ahmad; Karmali, Amin; Abdelmoez, Wael

2016-01-01

The present work involves a sensitive high-throughput microtiter plate based colorimetric assay for estimating lipase activity using cupric acetate pyridine reagent (CAPR). In the first approach, three factors two levels factorial design methodology was used to evaluate the interactive effect of different parameters on the sensitivity of the assay method. The optimization study revealed that the optimum CAPR concentration was 7.5% w/v, the optimum solvent was heptane and the optimum CAPR pH was 6. In the second approach, the optimized colorimetric microplate assay was used to measure lipase activity based on enzymatic hydrolysis of olive oil emulsion substrate at 37°C and 150 rpm. The emulsion substrates were formulated by using olive oil, triton X-100 (10% v/v in pH 8) and sodium phosphate buffer of pH 8 in ratio of 1:1:1 in the case of Candida sp. lipase. While in the case of immobilized lipozyme RMIM, The emulsion substrates were formulated by using olive oil, triton X-100 (1% v/v in pH 8) and sodium phosphate buffer of pH 8 in ratio of 2:1:1. Absorbance was measured at 655 nm. The stability of this assay (in terms of colored heptane phase absorbance readings) retained more than 92.5% after 24 h at 4°C compared to the absorbance readings measured at zero time. In comparison with other lipase assay methods, beside the developed sensitivity, the reproducibility and the lower limit of detection (LOD) of the proposed method, it permits analyzing of 96 samples at one time in a 96-well microplate. Furthermore, it consumes small quantities of chemicals and unit operations.

Site specific solubility improvement using solid dispersions of HPMC-AS/HPC SSL--mixtures.

PubMed

Zecevic, Damir Elmar; Meier, Robin; Daniels, Rolf; Wagner, Karl-Gerhard

2014-07-01

Many upcoming drug candidates are pH-dependent poorly soluble weak bases in the pH range of the gastrointestinal tract. This often leads to a high in vivo variability and bioavailability issues. Aiming to overcome these limitations, the design of solid dispersions for site specific dissolution improvement or maintenance of a potent supersaturation over the entire gastro-intestinal pH-range, is proposed to assure a reliable drug therapy. Solid dispersions containing different ratios of Dipyridamole (DPD) or Griseofulvin (GRI) and the enteric polymer hydroxypropylmethylcellulose-acetate succinate (HPMC-AS) and the water soluble low-viscosity hydroxypropylcellulose (HPC-SSL) were prepared by hot melt extrusion (HME). The solid dispersions were evaluated for their solid state, dissolution characteristics applying a three pH-step dissolution method following an acidic to neutral pH transition and stability. The use of HPMC-AS in binary mixtures with DPD and GRI facilitated increased solubility and supersaturation at pH-controlled release of the preserved amorphous state of the dispersed drug, which even inverted the pH-dependent solubility profile of the weakly basic model drug (Dipyridamole). I.e. a potent site specific delivery system was created. With ternary solid dispersions of API, HPMC-AS and HPC-SSL, tailored release profiles with superior supersaturation over the applied pH-range could be obtained. At the same time, binary and ternary mixtures showed favorable stability properties at a temperature difference between glass transition temperature and the applied storage temperature of down to 16°C. Copyright © 2014 Elsevier B.V. All rights reserved.

Structure and rheology of star polymers in confined geometries: a mesoscopic simulation study.

PubMed

Zheng, Feiwo; Goujon, Florent; Mendonça, Ana C F; Malfreyt, Patrice; Tildesley, Dominic J

2015-11-28

Mesoscopic simulations of star polymer melts adsorbed onto solid surfaces are performed using the dissipative particle dynamics (DPD) method. A set of parameters is developed to study the low functionality star polymers under shear. The use of a new bond-angle potential between the arms of the star creates more rigid chains and discriminates between different functionalities at equilibrium, but still allows the polymers to deform appropriately under shear. The rheology of the polymer melts is studied by calculating the kinetic friction and viscosity and there is good agreement with experimental properties of these systems. The study is completed with predictive simulations of star polymer solutions in an athermal solvent.

Method 366.0 Determination of Dissolved Silicate in Estuarine and Coastal Watersby Gas Segmented Continuous Flow Colorimetric Analysis

EPA Science Inventory

This method provides a procedure for the determination of dissolved silicate concentration in estuarine and coastal waters. The dissolved silicate is mainly in the form of silicic acid, H SiO , in estuarine and 4 4 coastal waters. All soluble silicate, including colloidal silici...

Use of DCPIP in a Colorimetric Method to Investigate Electron Transport in Crude Heart Mitochondrial Extracts.

ERIC Educational Resources Information Center

Myers, Alan

1990-01-01

A method of obtaining a crude mitochondrial extract from sheep and beef heart is described. The respiratory substrates succinate and malate are examined as well as the inhibitory effect of malonate. An interface with a microcomputer for plotting colorimeter results is discussed. (Author/CW)

A comparison of two colorimetric assays, based upon Lowry and Bradford techniques, to estimate total protein in soil extracts.

PubMed

Redmile-Gordon, M A; Armenise, E; White, R P; Hirsch, P R; Goulding, K W T

2013-12-01

Soil extracts usually contain large quantities of dissolved humified organic material, typically reflected by high polyphenolic content. Since polyphenols seriously confound quantification of extracted protein, minimising this interference is important to ensure measurements are representative. Although the Bradford colorimetric assay is used routinely in soil science for rapid quantification protein in soil-extracts, it has several limitations. We therefore investigated an alternative colorimetric technique based on the Lowry assay (frequently used to measure protein and humic substances as distinct pools in microbial biofilms). The accuracies of both the Bradford assay and a modified Lowry microplate method were compared in factorial combination. Protein was quantified in soil-extracts (extracted with citrate), including standard additions of model protein (BSA) and polyphenol (Sigma H1675-2). Using the Lowry microplate assay described, no interfering effects of citrate were detected even with concentrations up to 5 times greater than are typically used to extract soil protein. Moreover, the Bradford assay was found to be highly susceptible to two simultaneous and confounding artefacts: 1) the colour development due to added protein was greatly inhibited by polyphenol concentration, and 2) substantial colour development was caused directly by the polyphenol addition. In contrast, the Lowry method enabled distinction between colour development from protein and non-protein origin, providing a more accurate quantitative analysis. These results suggest that the modified-Lowry method is a more suitable measure of extract protein (defined by standard equivalents) because it is less confounded by the high polyphenolic content which is so typical of soil extracts.

Comparison of colorimetry and electrothermal atomic absorption spectroscopy for the quantification of non-transferrin bound iron in human sera.

PubMed

Jittangprasert, Piyada; Wilairat, Prapin; Pootrakul, Pensri

2004-12-01

This paper describes a comparison of two analytical techniques, one employing bathophenanthrolinedisulfonate (BPT), a most commonly-used reagent for Fe (II) determination, as chromogen and an electrothermal atomic absorption spectroscopy (ETAAS) for the quantification of non-transferrin bound iron (NTBI) in sera from thalassemic patients. Nitrilotriacetic acid (NTA) was employed as the ligand for binding iron from low molecular weight iron complexes present in the serum but without removing iron from the transferrin protein. After ultrafiltration the Fe (III)-NTA complex was then quantified by both methods. Kinetic study of the rate of the Fe (II)-BPT complex formation for various excess amounts of NTA ligand was also carried out. The kinetic data show that a minimum time duration (> 60 minutes) is necessary for complete complex formation when large excess of NTA is used. Calibration curves given by colorimetric and ETAAS methods were linear over the range of 0.15-20 microM iron (III). The colorimetric and ETAAS methods exhibited detection limit (3sigma) of 0.13 and 0.14 microM, respectively. The NTBI concentrations from 55 thalassemic serum samples measured employing BPT as chromogen were statistically compared with the results determined by ETAAS. No significant disagreement at 95% confidence level was observed. It is, therefore, possible to select any one of these two techniques for determination of NTBI in serum samples of thalassemic patients. However, the colorimetric procedure requires a longer analysis time because of a slow rate of exchange of NTA ligand with BPT, leading to the slow rate of formation of the colored complex.

Toward Quantifying the Aesthetic Outcomes of Breast Cancer Treatment: Comparison of Clinical Photography and Colorimetry

PubMed Central

Kim, Min Soon; Rodney, William N.; Cooper, Tara; Kite, Chris; Reece, Gregory P.; Markey, Mia K.

2011-01-01

Rationale, aims and objectives Scarring is a significant cause of dissatisfaction for women who undergo breast surgery. Scar tissue may be clinically distinguished from normal skin by aberrant color, rough surface texture, increased thickness (hypertrophy), and firmness. Colorimeters or spectrophotometers can be used to quantitatively assess scar color, but they require direct patient interaction and can cost thousands of dollars By comparison, digital photography is already in widespread use to document clinical outcomes and requires less patient interaction. Thus, assessment of scar coloration by digital photography is an attractive alternative. The goal of this study was to compare color measurements obtained by digital photography and colorimetry. Method Agreement between photographic and colorimetric measurements of color were evaluated. Experimental conditions were controlled by performing measurements on artificial scars created by a makeup artist. The colorimetric measurements of the artificial scars were compared to those reported in the literature for real scars in order to confirm the validity of this approach. We assessed the agreement between the colorimetric and photographic measurements of color using a hypothesis test for equivalence, the intra-class correlation coefficient (ICC), and the Bland-Altman method. Results Overall, good agreement was obtained for three parameters (L*a*b*) measured by colorimetry and photography from the results of three statistical analyses. Conclusion Color measurements obtained by digital photography were equivalent to those obtained using colorimetry. Thus, digital photography is a reliable, cost-effective measurement method of skin color and should be further investigated for quantitative analysis of surgical outcomes. PMID:19239578

A convenient method for synthesis of glyconanoparticles for colorimetric measuring carbohydrate-protein interactions

PubMed Central

Chuang, Yen-Jun; Zhou, Xichun; Pan, Zhengwei; Turchi, Craig

2009-01-01

Carbohydrate functionalized nanoparticles, i.e., the glyconanoparticles, have wide application ranging from studies of carbohydrate-protein interactions, in vivo cell imaging, biolabeling, etc. Currently reported methods for preparation of glyconanoaprticles require multi-step modifications of carbohydrates moieties to conjugate to nanoparticle surface. However, the required synthetic manipulations are difficult and time consuming. We report herewith a simple and versatile method for preparing glyconanoparticles. This method is based on the utilization of clean and convenient microwave irradiation energy for one-step, site-specific conjugation of unmodified carbohydrates onto hydrazide-functionalized Au nanoparticles. A colorimetric assay that utilizes the ensemble of gold glyconanoparticles and Concanavalin A (ConA) was also presented. This feasible assay system was developed to analyze multivalent interactions and to determine the dissociation constant (Kd) for five kind of Au glyconanoparticles with lectin. Surface plasmon changes of the Au glyconanparticles as a function of lectin-carbohydrate interactions were measured and the dissociation constants were determined based on non-linear curve fitting. The strength of the interaction of carbohydrates with ConA was found to be as follows: Maltose > Mannose > Glucose > Lactose > MAN5. PMID:19698698

[A study of biomechanical method for urine test based on color difference estimation].

PubMed

Wang, Chunhong; Zhou, Yue; Zhao, Hongxia; Zhou, Fengkun

2008-02-01

The biochemical analysis of urine is an important inspection and diagnosis method in hospitals. The conventional method of urine analysis covers mainly colorimetric visual appraisement and automation detection, in which the colorimetric visual appraisement technique has been superseded basically, and the automation detection method is adopted in hospital; moreover, the price of urine biochemical analyzer on market is around twenty thousand RMB yuan (Y), which is hard to enter into ordinary families. It is known that computer vision system is not subject to the physiological and psychological influence of person, its appraisement standard is objective and steady. Therefore, according to the color theory, we have established a computer vision system, which can carry through collection, management, display, and appraisement of color difference between the color of standard threshold value and the color of urine test paper after reaction with urine liquid, and then the level of an illness can be judged accurately. In this paper, we introduce the Urine Test Biochemical Analysis method, which is new and can be popularized in families. Experimental result shows that this test method is easy-to-use and cost-effective. It can realize the monitoring of a whole course and can find extensive applications.

Chlorine Analysis - Wastewater. Training Module 5.125.2.77.

ERIC Educational Resources Information Center

Kirkwood Community Coll., Cedar Rapids, IA.

This document is an instructional module package prepared in objective form for use by an instructor familiar with the laboratory procedures for determining the combined chlorine residual of a wastewater sample. Included are objectives, instructor guides, student handouts, and transparency masters. This module considers the amperometric, DPD,…

Teaching for Change: The Difference, Power, and Discrimination Model

ERIC Educational Resources Information Center

Xing, Jun, Ed.; Li, Judith, Ed.; Roper, Larry D., Ed.; Shaw, Susan M., Ed.

2006-01-01

Over the past three decades, American higher education has witnessed a shift in demographics which has created a more diverse student body. However, many university campuses remain unsupportive or even hostile to minority faculty and students. This anthology introduces to readers the Difference, Power, and Discrimination (DPD) Program, a…

Douglas-fir displays a range of growth responses to temperature, water, and Swiss needle cast in western Oregon, USA

EPA Science Inventory

Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) growth in the Pacific Northwest is affected by climatic, edaphic factors and Swiss needle cast (SNC) disease. We examine Douglas-fir growth responses to temperature, dewpoint deficit (DPD), soil moisture, and SNC ...

Zero- and two-dimensional hybrid carbon phosphors for high colorimetric purity white light-emission.

PubMed

Ding, Yamei; Chang, Qing; Xiu, Fei; Chen, Yingying; Liu, Zhengdong; Ban, Chaoyi; Cheng, Shuai; Liu, Juqing; Huang, Wei

2018-03-01

Carbon nanomaterials are promising phosphors for white light emission. A facile single-step synthesis method has been developed to prepare zero- and two-dimensional hybrid carbon phosphors for the first time. Zero-dimensional carbon dots (C-dots) emit bright blue luminescence under 365 nm UV light and two-dimensional nanoplates improve the dispersity and film forming ability of C-dots. As a proof-of-concept application, the as-prepared hybrid carbon phosphors emit bright white luminescence in the solid state, and the phosphor-coated blue LEDs exhibit high colorimetric purity white light-emission with a color coordinate of (0.3308, 0.3312), potentially enabling the successful application of white emitting phosphors in the LED field.

Colorimetric assay for urinary track infection disease diagnostic on flexible substrate

NASA Astrophysics Data System (ADS)

Safavieh, Mohammadali; Ahmed, Minhaz Uddin; Zourob, Mohammed

2012-10-01

We are presenting cassette as a novel point of care diagnostic device. This device is easy to use, low cost to prepare, high throughput and can analyze several samples at the same time. We first, demonstrate the preparation method of the device. Then, fabrication of the flexible substrate has been presented. The device has been used for detection of the real sample of E.coli bacteria following by colorimetric detection. We have shown that we could detect 30 cfu/ml bacteria and 100 fg/μl of Staphylococous aureus DNA in 1 hr using LAMP amplification technique. This device will be helpful in hospitals and doctor's office for analysis of several patients' samples at the same time.

A new rhodamine-based colorimetric chemosensor for naked-eye detection of Cu(2+) in aqueous solution.

PubMed

Hu, Yang; Zhang, Jing; Lv, Yuan-Zheng; Huang, Xiao-Huan; Hu, Sheng-Li

2016-03-15

A new colorimetric probe 1 based on rhodamine B lactam was developed for naked-eye detection of Cu(2+). The optical feature of 1 for Cu(2+) was investigated by UV-vis absorption spectroscopy. Upon the addition of Cu(2+), the 1 displayed a distinct color change from colorless to pink, which can be directly detected by the naked eye. The stoichiometry of 1 to Cu(2+) complex was found to be 1:1 and the naked-eye detection limit was determined as low as 2 μM. The results suggest that the probe 1 may provide a convenient method for visual detection of Cu(2+) with high sensitivity. Copyright © 2015 Elsevier B.V. All rights reserved.

Multiplexed Colorimetric Solid-Phase Extraction

NASA Technical Reports Server (NTRS)

Gazda, Daniel B.; Fritz, James S.; Porter, Marc D.

2009-01-01

Multiplexed colorimetric solid-phase extraction (MC-SPE) is an extension of colorimetric solid-phase extraction (C-SPE) an analytical platform that combines colorimetric reagents, solid phase extraction, and diffuse reflectance spectroscopy to quantify trace analytes in water. In CSPE, analytes are extracted and complexed on the surface of an extraction membrane impregnated with a colorimetric reagent. The analytes are then quantified directly on the membrane surface using a handheld diffuse reflectance spectrophotometer. Importantly, the use of solid-phase extraction membranes as the matrix for impregnation of the colorimetric reagents creates a concentration factor that enables the detection of low concentrations of analytes in small sample volumes. In extending C-SPE to a multiplexed format, a filter holder that incorporates discrete analysis channels and a jig that facilitates the concurrent operation of multiple sample syringes have been designed, enabling the simultaneous determination of multiple analytes. Separate, single analyte membranes, placed in a readout cartridge create unique, analyte-specific addresses at the exit of each channel. Following sample exposure, the diffuse reflectance spectrum of each address is collected serially and the Kubelka-Munk function is used to quantify each water quality parameter via calibration curves. In a demonstration, MC-SPE was used to measure the pH of a sample and quantitate Ag(I) and Ni(II).

Development, optimization and validation of a rapid colorimetric microplate bioassay for neomycin sulfate in pharmaceutical drug products.

PubMed

Francisco, Fabiane Lacerda; Saviano, Alessandro Morais; Pinto, Terezinha de Jesus Andreoli; Lourenço, Felipe Rebello

2014-08-01

Microbiological assays have been used to evaluate antimicrobial activity since the discovery of the first antibiotics. Despite their limitations, microbiological assays are widely employed to determine antibiotic potency of pharmaceutical dosage forms, since they provide a measure of biological activity. The aim of this work is to develop, optimize and validate a rapid colorimetric microplate bioassay for the potency of neomycin in pharmaceutical drug products. Factorial and response surface methodologies were used in the development and optimization of the choice of microorganism, culture medium composition, amount of inoculum, triphenyltetrazolium chloride (TTC) concentration and neomycin concentration. The optimized bioassay method was validated by the assessment of linearity (range 3.0 to 5.0μg/mL, r=0.998 and 0.994 for standard and sample curves, respectively), precision (relative standard deviation (RSD) of 2.8% and 4.0 for repeatability and intermediate precision, respectively), accuracy (mean recovery=100.2%) and robustness. Statistical analysis showed equivalency between agar diffusion microbiological assay and rapid colorimetric microplate bioassay. In addition, microplate bioassay had advantages concerning the sensitivity of response, time of incubation, and amount of culture medium and solutions required. Copyright © 2014 Elsevier B.V. All rights reserved.

A simplified approach to the determination of N-nitroso glyphosate in technical glyphosate using HPLC with post-derivatization and colorimetric detection.

PubMed

Kim, Manuela; Stripeikis, Jorge; Iñón, Fernando; Tudino, Mabel

2007-05-15

A simple and sensitive HPLC post-derivatization method with colorimetric detection has been developed for the determination of N-nitroso glyphosate in samples of technical glyphosate. Separation of the analyte was accomplished using an anionic exchange resin (2.50mmx4.00mm i.d., 15mum particle size, functional group: quaternary ammonium salt) with Na(2)SO(4) 0.0075M (pH 11.5) (flow rate: 1.0mLmin(-1)) as mobile phase. After separation, the eluate was derivatized with a colorimetric reagent containing sulfanilamide 0.3% (w/v), [N-(1-naphtil)ethilendiamine] 0.03% (w/v) and HCl 4.5M in a thermostatized bath at 95 degrees C. Detection was performed at 546nm. All stages of the analytical procedure were optimized taking into account the concept of analytical minimalism: less operation times and costs; lower sample, reagents and energy consumption and minimal waste. The limit of detection (k=3) calculated for 10 blank replicates was 0.04mgL(-1) (0.8mgkg(-1)) in the solid sample which is lower than the maximum tolerable accepted by the Food and Agriculture Organization of the United Nations.

Biothiols induced colour change of silver nanoparticles: A colorimetric sensing strategy

NASA Astrophysics Data System (ADS)

Thomas, Ambily; Sivasankaran, Unni; Kumar, Krishnapillai Girish

2018-01-01

A sensor for the detection and determination of bio-thiols (glutathione (GSH) and cysteamine (Cyste)) has been developed by integrating the distinguished distance related optical characteristics of silver nanoparticles with the simplicity of colorimetric technique. In presence of these analytes, shift in surface plasmon resonance (SPR) absorption of silver nanoparticles (AgNPs) with change in its colour was observed. Yellow coloured AgNPs solution becomes colourless in presence of GSH and changes to red in presence of Cyste. FTIR, TEM and DLS studies were used to confirm the mechanism. The difference in absorption of AgNPs in the absence and presence of GSH was found to vary linearly in the range 1.00 × 10- 5 M to 5.00 × 10- 7 M concentration range with limit of detection at 3.68 × 10- 7 M. The method can also be applied to quantify Cyste in the range 1.10 × 10- 6 M to 5.00 × 10- 8 M with limit of detection at 1.80 × 10- 8 M. The utility of the proposed colorimetric assay is validated by determination of GSH and Cyste in artificial blood serum.

76 FR 37796 - Notice of Availability of Government-Owned Inventions; Available for Licensing

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-28

... Aircraft Division, Business and Partnership Office, Office of Research and Technology Applications... October 26, 2010 U.S. Patent Application No. 7,839,304 B2: Method and System for Alerting Aircrew to... Application No. 12/868,772: Colorimetric Method for Detection of Biodiesel in Fuel, Navy Case No. PAX37, filed...

Mentha-Stabilized Silver Nanoparticles for High-Performance Colorimetric Detection of Al(III) in Aqueous Systems.

PubMed

Sharma, Rekha; Dhillon, Ankita; Kumar, Dinesh

2018-03-26

The present paper reports a facile and selective colorimetric method for the detection of potential environmental and health hazardous metal ions using green synthesized silver nanoparticles (AgNPs). Here the organic functional groups present in the plant extract (Mentha arvensis) are used as reductants and stabilizers in the synthesis of AgNPs. They also provide a suitable binding site to the (Al(III)) analyte in the detection mechanism. The leaf extract of Mentha arvensis was used to synthesize AgNPs at room-temperature and at 80 °C. The AgNPs synthesized at 80 °C exhibit excellent selective colorimetric detection of Al(III). The as-synthesized AgNPs have been characterized, and the synthesis, stabilization of NPs and detection mechanism has also been illustrated by using UV-vis, XPS, FTIR, TEM, EDX, SEM, AAS, and TGA analytical tools and techniques. The selectivity of detection probe was supported by the reaction between probe and metal ions followed first-order kinetics having the highest value of the regression coefficient (R 2  = 0.99) for Al(III) and the analysis of thermodynamic parameters. The prepared sensor showed a lower limit of detection (LOD) of 1 nM (S/N = 3.2) in real water samples. The proposed method can be successfully utilized for the detection of Al(III) from both drinking and real water samples at the nanomolar level.

Towards quantifying the aesthetic outcomes of breast cancer treatment: comparison of clinical photography and colorimetry.

PubMed

Kim, Min Soon; Rodney, William N; Cooper, Tara; Kite, Chris; Reece, Gregory P; Markey, Mia K

2009-02-01

Scarring is a significant cause of dissatisfaction for women who undergo breast surgery. Scar tissue may be clinically distinguished from normal skin by aberrant colour, rough surface texture, increased thickness (hypertrophy) and firmness. Colorimeters or spectrophotometers can be used to quantitatively assess scar colour, but they require direct patient interaction and can cost thousands of dollars. By comparison, digital photography is already in widespread use to document clinical outcomes and requires less patient interaction. Thus, assessment of scar coloration by digital photography is an attractive alternative. The goal of this study was to compare colour measurements obtained by digital photography and colorimetry. Agreements between photographic and colorimetric measurements of colour were evaluated. Experimental conditions were controlled by performing measurements on artificial scars created by a make-up artist. The colorimetric measurements of the artificial scars were compared with those reported in the literature for real scars in order to confirm the validity of this approach. We assessed the agreement between the colorimetric and photographic measurements of colour using a hypothesis test for equivalence, the intraclass correlation coefficient and the Bland-Altman method. Overall, good agreement was obtained for three parameters (L*a*b*) measured by colorimetry and photography from the results of three statistical analyses. Colour measurements obtained by digital photography were equivalent to those obtained using colorimetry. Thus, digital photography is a reliable, cost-effective measurement method of skin colour and should be further investigated for quantitative analysis of surgical outcomes.

Colorimetric and Fluorescent Dual Mode Sensing of Alcoholic Strength in Spirit Samples with Stimuli-Responsive Infinite Coordination Polymers.

PubMed

Deng, Jingjing; Ma, Wenjie; Yu, Ping; Mao, Lanqun

2015-07-07

This study demonstrates a new strategy for colorimetric and fluorescent dual mode sensing of alcoholic strength (AS) in spirit samples based on stimuli-responsive infinite coordination polymers (ICPs). The ICP supramolecular network is prepared with 1,4-bis(imidazol-1-ylmethyl)benzene (bix) as the ligand and Zn(2+) as the central metal ion in ethanol, in which rhodamine B (RhB) is encapsulated through self-adaptive chemistry. In pure ethanol solvent, the as-formed RhB/Zn(bix) is well dispersed and quite stable. However, the addition of water into the ethanol dispersion of RhB/Zn(bix) destroys Zn(bix) network structure, resulting in the release of RhB from ICP into the solvent. As a consequence, the solvent displays the color of released RhB and, at the meantime, turns on the fluorescence of RhB, which constitutes a new mechanism for colorimetric and fluorescent dual mode sensing of AS in commercial spirit samples. With the method developed here, we could distinguish the AS of different commercial spirit samples by the naked eye within a wide linear range from 20 to 100% vol and by monitoring the increase of fluorescent intensity of the released RhB. This study not only offers a new method for on-spot visible detection of AS in commercial spirit samples, but also provides a strategy for designing dual mode sensing mechanisms for different analytical purposes based on novel stimuli-responsive materials.

Sensitive detection of microRNAs based on the conversion of colorimetric assay into electrochemical analysis with duplex-specific nuclease-assisted signal amplification

PubMed Central

Xia, Ning; Liu, Ke; Zhou, Yingying; Li, Yuanyuan; Yi, Xinyao

2017-01-01

miRNAs have emerged as new biomarkers for the detection of a wide variety of cancers. By employing duplex-specific nuclease for signal amplification and gold nanoparticles (AuNPs) as the carriers of detection probes, a novel electrochemical assay of miRNAs was performed. The method is based on conversion of the well-known colorimetric assay into electrochemical analysis with enhanced sensitivity. DNA capture probes immobilized on the electrode surface and ferrocene (Fc)-labeled DNA detection probes (denoted “Fc-DNA-Fc”) presented in the solution induced the assembly of positively charged AuNPs on the electrode surface through the electrostatic interaction. As a result, a large number of Fc-DNA-Fc molecules were attached on the electrode surface, thus amplifying the electrochemical signal. When duplex-specific nuclease was added to recycle the process of miRNA-initiated digestion of the immobilized DNA probes, Fc-DNA-Fc-induced assembly of AuNPs on the electrode surface could not occur. This resulted in a significant fall in the oxidation current of Fc. The current was found to be inversely proportional to the concentration of miRNAs in the range of 0–25 fM, and a detection limit of 0.1 fM was achieved. Moreover, this work presents a new method for converting colorimetric assays into sensitive electrochemical analyses, and thus would be valuable for design of novel chemical/biosensors. PMID:28761341

Evaluation of colorimetric loop-mediated isothermal amplification assay for visual detection of Streptococcus agalactiae and Streptococcus iniae in tilapia.

PubMed

Suebsing, R; Kampeera, J; Tookdee, B; Withyachumnarnkul, B; Turner, W; Kiatpathomchai, W

2013-10-01

Streptococcus agalactiae and Strep. iniae are bacterial pathogens that cause streptococcosis in many fish species. An accelerated colorimetric loop-mediated isothermal amplification (LAMP) assay with pre-addition of calcein was established, and the transmission and detection of Strep. agalactiae and Strep. iniae in tilapia under natural aquatic environment were investigated. A positive reaction was observed by a colour change from orange to green through the naked eyes after completion at 63°C for 30 min with 10 times higher sensitivity than that of nested PCR assays and without cross-amplification with other fish bacterial pathogens. All sample types of Nile and red tilapia (broodstock, fertilized egg, fry) were Strep. agalactiae- and Strep. iniae positive by this new method, implying that they could be vertically transmitted. With its application for screening broodstock and fry before stocking and for monitoring fish health in grow-out ponds, the method would become very useful in fish farming industry. The application of colorimetric LAMP with pre-addition of calcein offers simple, rapid and sensitive technique with applicability for small field laboratories. This technique explored the possible vertical transmission mode of Strep. agalactiae and Strep. iniae under natural aquatic environment. It could be such preliminary data provided for the screening broodstock before breeding and/or the specific-pathogen-free production. © 2013 The Society for Applied Microbiology.

The effects of colorimetric detection of heavy metal ions based on Au nanoparticles (NPs): size and shape—a case of Co2+

NASA Astrophysics Data System (ADS)

Leng, Yumin; He, Junbao; Li, Bo; Xing, Xiaojing; Guo, Yongming; Ye, Liqun; Lu, Zhiwen

2017-09-01

The different sized and shaped Au NPs have intrigued considerable attention, because they possess different surface plasma resonance (SPR) absorption bands and thus result in many colorimetric Au NP-based detection applications. In this article, four different sized and shaped Au NPs of nanodots/rods were prepared and characterized. The as-prepared Au NPs were modified by the negatively charged anions of [SCH2CO2]2- to investigate both the size and shape effects of modified Au NPs on colorimetric detection of Co2+ and the corresponding SPR absorption properties. The different-shaped Au NPs possess different SPR absorption properties. The Au nanorods appeared to be colorimetric sensitive for Co2+ sensing.

Space station MSFC-DPD-235/DR no. CM-03 specification, modular space station project, Part 1 CEI

NASA Technical Reports Server (NTRS)

1971-01-01

Contract engineering item specifications for the modular space station are presented. These specifications resulted from the development and allocations of requirements which are concise statements of performance or constraints on performance. Specifications contain requirements for functional performance and for the verification of design solutions.

SUNREL Applications | Buildings | NREL

Science.gov Websites

used by the building design team for energy analysis. Zion National Park Visitor's Center Grand Canyon National Park Bookstore NREL Thermal Test Facility NREL Wind Site Entrance Building DPD Office Building Performance Analysis of a High-Mass Residential Building Van Geet residence The Van Geet Off-Grid Home: An

Spectrophotometric, colorimetric and visually detection of Pseudomonas aeruginosa ETA gene based gold nanoparticles DNA probe and endonuclease enzyme.

PubMed

Amini, Bahram; Kamali, Mehdi; Salouti, Mojtaba; Yaghmaei, Parichehreh

2018-06-15

Colorimetric DNA detection is preferred over other methods for clinical molecular diagnosis because it does not require expensive equipment. In the present study, the colorimetric method based on gold nanoparticles (GNPs) and endonuclease enzyme was used for the detection of P. aeruginosa ETA gene. Firstly, the primers and probe for P. aeruginosa exotoxin A (ETA) gene were designed and checked for specificity by the PCR method. Then, GNPs were synthesized using the citrate reduction method and conjugated with the prepared probe to develop the new nano-biosensor. Next, the extracted target DNA of the bacteria was added to GNP-probe complex to check its efficacy for P. aeruginosa ETA gene diagnosis. A decrease in absorbance was seen when GNP-probe-target DNA cleaved into the small fragments of BamHI endonuclease due to the weakened electrostatic interaction between GNPs and the shortened DNA. The right shift of the absorbance peak from 530 to 562nm occurred after adding the endonuclease. It was measured using a UV-VIS absorption spectroscopy that indicates the existence of the P. aeruginosa ETA gene. Sensitivity was determined in the presence of different concentrations of target DNA of P. aeruginosa. The results obtained from the optimized conditions showed that the absorbance value has linear correlation with concentration of target DNA (R: 0.9850) in the range of 10-50ngmL -1 with the limit detection of 9.899ngmL -1 . Thus, the specificity of the new method for detection of P. aeruginosa was established in comparison with other bacteria. Additionally, the designed assay was quantitatively applied to detect the P. aeruginosa ETA gene from 10 3 to 10 8 CFUmL -1 in real samples with a detection limit of 320CFUmL -1 . Copyright © 2018 Elsevier B.V. All rights reserved.

Headspace-Sampling Paper-Based Analytical Device for Colorimetric/Surface-Enhanced Raman Scattering Dual Sensing of Sulfur Dioxide in Wine.

PubMed

Li, Dan; Duan, Huazhen; Ma, Yadan; Deng, Wei

2018-05-01

This study demonstrates a novel strategy for colorimetric/surface-enhanced Raman scattering (SERS) dual-mode sensing of sulfur dioxide (SO 2 ) by coupling headspace sampling (HS) with paper-based analytical device (PAD). The smart and multifunctional PAD is fabricated with a vacuum filtration method in which 4-mercaptopyridine (Mpy)-modified gold nanorods (GNRs)-reduced graphene oxide (rGO) hybrids (rGO/MPy-GNRs), anhydrous methanol, and starch-iodine complex are immobilized into cellulose-based filter papers. The resultant PAD exhibits a deep-blue color with a strong absorption peak at 600 nm due to the formation of an intermolecular charge-transfer complex between starch and iodine. However, the addition of SO 2 induces the Karl Fischer reaction, resulting in the decrease of color and increase of SERS signals. Therefore, the PAD can be used not only as a naked-eye indicator of SO 2 changed from blue to colorless but also as a highly sensitive SERS substrates because of the SO 2 -triggered conversion of Mpy to pyridine methyl sulfate on the GNRs. A distinguishable change in the color was observed at a SO 2 concentration of 5 μM by the naked eye, and a detection limit as low as 1.45 μM was obtained by virtue of UV-vis spectroscopy. The PAD-based SERS method is effective over a wide range of concentrations (1 μM to 2000 μM) for SO 2 , and the detection limit for SO 2 is found to be 1 μM. The HS-PAD based colorimetric/SERS method is applied for the determination of SO 2 in wine, and the detection results match well with those obtained from the traditional Monier-Williams method. This study not only offers a new method for on-site monitoring of SO 2 but also provides a new strategy for designing of paper-based sensing platform for a wide range of field-test applications.

A comparative study of three cytotoxicity test methods for nanomaterials using sodium lauryl sulfate.

PubMed

Kwon, Jae-Sung; Kim, Kwang-Mahn; Kim, Kyoung-Nam

2014-10-01

The biocompatibility evaluation of nanomaterials is essential for their medical diagnostic and therapeutic usage, where a cytotoxicity test is the simplest form of biocompatibility evaluation. Three methods have been commonly used in previous studies for the cytotoxicity testing of nanomaterials: trypan blue exclusion, colorimetric assay using water soluble tetrazolium (WST), and imaging under a microscope following calcein AM/ethidium homodimer-1 staining. However, there has yet to be a study to compare each method. Therefore, in this study three methods were compared using the standard reference material of sodium lauryl sulfate (SLS). Each method of the cytotoxicity test was carried out using mouse fibroblasts of L-929 exposed to different concentrations of SLS. Compared to the gold standard trypan blue exclusion test, both colorimetric assay using water soluble tetrazolium (WST) and imaging under microscope with calcein AM/ethidium homodimer-1 staining showed results that were not statistically different. Also, each method exhibited various advantages and disadvantages, which included the need of equipment, time taken for the experiment, and provision of additional information such as cell morphology. Therefore, this study concludes that all three methods of cytotoxicity testing may be valid, though careful consideration will be needed when selecting tests with regard to time, finances, and the amount of information required by the researcher(s).

Colorimetric Method of Loop-Mediated Isothermal Amplification with the Pre-Addition of Calcein for Detecting Flavobacterium columnare and its Assessment in Tilapia Farms.

PubMed

Suebsing, Rungkarn; Kampeera, Jantana; Sirithammajak, Sarawut; Withyachumnarnkul, Boonsirm; Turner, Warren; Kiatpathomchai, Wansika

2015-03-01

Flavobacterium columnare, the causative agent of columnaris disease in fish, affects many economically important freshwater fish species. A colorimetric method of loop-mediated isothermal amplification with the pre-addition of calcein (LAMP-calcein) was developed and used to detect the presence of F. columnare in farmed tilapia (Nile Tilapia Oreochromis niloticus and red tilapia [Nile Tilapia × Mozambique Tilapia O. mossambicus]) and rearing water. The detection method, based on a change in color from orange to green, could be performed within 45 min at 63°C. The method was highly specific, as it had no cross-detections with 14 other bacterial species, including other fish pathogens and two Flavobacterium species. The method has a minimum detection limit of 2.2 × 10(2) F. columnare CFU; thus, it is about 10 times more sensitive than conventional PCR. With this method, F. columnare was detected in gonad, gill, and blood samples from apparently healthy tilapia broodstock as well as in samples of fertilized eggs, newly hatched fry, and rearing water. The bacteria isolated from the blood were further characterized biochemically and found to be phenotypically identical to F. columnare. The amplified products from the LAMP-calcein method had 97% homology with the DNA sequence of F. columnare.

Ultrasensitive colorimetric detection of heparin based on self-assembly of gold nanoparticles on graphene oxide.

PubMed

Fu, Xiuli; Chen, Lingxin; Li, Jinhua

2012-08-21

A novel colorimetric method was developed for ultrasensitive detection of heparin based on self-assembly of gold nanoparticles (AuNPs) onto the surface of graphene oxide (GO). Polycationic protamine was used as a medium for inducing the self-assembly of citrate-capped AuNPs on GO through electrostatic interaction, resulting in a shift in the surface plasmon resonance (SPR) absorption of AuNPs and exhibiting a blue color. Addition of polyanionic heparin disturbed the self-assemble of AuNPs due to its strong affinity to protamine. With the increase of heparin concentration, the amounts of self-assembly AuNPs decreased and the color changed from blue to red in solution. Therefore, a "blue-to-red" colorimetric sensing strategy based on self-assembly of AuNPs could be established for heparin detection. Compared with the commonly reported aggregation-based methods ("red-to-blue"), the color change from blue to red was more eye-sensitive, especially in low concentration of target. Moreover, stronger interaction between protamine and heparin led to distinguish heparin from its analogues as well as various potentially coexistent physiological species. The strategy was simply achieved by the self-assembly nature of AuNPs and the application of two types of polyionic media, showing it to be label-free, simple, rapid and visual. This method could selectively detect heparin with a detection limit of 3.0 ng mL(-1) in standard aqueous solution and good linearity was obtained over the range 0.06-0.36 μg mL(-1) (R = 0.9936). It was successfully applied to determination of heparin in fetal bovine serum samples as low as 1.7 ng mL(-1) with a linear range of 0-0.8 μg mL(-1).

Determination of colloidal and dissolved silver in water samples using colorimetric solid-phase extraction.

PubMed

Hill, April A; Lipert, Robert J; Porter, Marc D

2010-03-15

The increase in bacterial resistance to antibiotics has led to resurgence in the use of silver as a biocidal agent in applications ranging from washing machine additives to the drinking water treatment system on the International Space Station (ISS). However, growing concerns about the possible toxicity of colloidal silver to bacteria, aquatic organisms and humans have led to recently issued regulations by the US EPA and FDA regarding the usage of silver. As part of an ongoing project, we have developed a rapid, simple method for determining total silver, both ionic (silver(I)) and colloidal, in 0.1-1mg/L aqueous samples, which spans the ISS potable water target of 0.3-0.5mg/L (total silver) and meets the US EPA limit of 0.1mg/L in drinking water. The method is based on colorimetric solid-phase extraction (C-SPE) and involves the extraction of silver(I) from water samples by passage through a solid-phase membrane impregnated with the colorimetric reagent DMABR (5-[4-(dimethylamino)benzylidene]rhodanine). Silver(I) exhaustively reacts with impregnated DMABR to form a colored compound, which is quantified using a handheld diffuse reflectance spectrophotometer. Total silver is determined by first passing the sample through a cartridge containing Oxone, which exhaustively oxidizes colloidal silver to dissolved silver(I). The method, which takes less than 2 min to complete and requires only approximately 1 mL of sample, has been validated through a series of tests, including a comparison with the ICP-MS analysis of a water sample from ISS that contained both silver(I) and colloidal silver. Potential earth-bound applications are also briefly discussed. Copyright (c) 2009 Elsevier B.V. All rights reserved.

A sensitive colorimetric method for the determination of nitrite in water supplies, meat and dairy products using ionic liquid-modified methyl red as a colour reagent.

PubMed

Zhang, Haijuan; Qi, Shengda; Dong, Yalei; Chen, Xiaojiao; Xu, Yinyin; Ma, Yanhua; Chen, Xingguo

2014-05-15

This paper describes a colorimetric approach to determine trace amounts of nitrite in water supplies, meat and dairy products using 1-butyl-3-methylimidazolium-modified methyl red ([BMIM]MR) as a colour reagent. The technique capitalises on the catalytic effect of nitrite on the oxidative degradation of [BMIM]MR by potassium bromate in acidic media. The absorbances were proportional to nitrite concentrations in the range of 8.70×10(-2) to 4.17 μM with a detection limit of 1.64×10(-2) μM. Compared with the method using methyl red as a colour reagent, 60 times improvement of sensitivity was obtained. Activation energy and the apparent rate constant for the catalytic reaction are 61.11 kJ mol(-1) and 1.18×10(4) s(-1), respectively. The proposed method was successfully applied for the analysis of nitrite in Yellow River water, chicken, and milk with recoveries ranging from 96% to 105%. Copyright © 2013 Elsevier Ltd. All rights reserved.

Indirect Determination of Pentaerythritol Tetranitrate (PETN) with a gold nanoparticles-based colorimetric sensor.

PubMed

Üzer, Ayşem; Yalçın, Uğur; Can, Ziya; Erçağ, Erol; Apak, Reşat

2017-12-01

Pentaerythritol tetranitrate (PETN) is the nitrate ester of pentaerythritol, used as an energetic and filling material for military and civilian purposes and rarely for terrorist actions. As there is no reliable nano-colorimetric method for PETN assay, we developed an indirect method based on the determination of nitrite, obtained by reduction of nitrate derived from the alkaline hydrolysis of PETN with H 2 O 2 . We colorimetrically determined the final product, nitrite, by both conventional Griess reaction and a recently developed gold nanoparticle-4-aminothiophenol-N-(1-naphthyl)-ethylenediamine (AuNP-4-ATP+NED) method. Nitramines (RDX and HMX), if present, could be degraded by alkaline hydrolysis, without affecting PETN. The analytical performance characteristics of the developed assays as molar absorptivity (ε), limits of detection (LOD) and quantification (LOQ) were: ɛ=1.06×10 5 L mol -1 cm -1 , LOD=0.03mgL -1 and LOQ=0.11mgL -1 for indirect Griess method; ɛ=1.9×10 4 Lmol -1 cm -1 ; LOD=0.12mgL -1 and LOQ=0.4mgL -1 for AuNP-4-ATP+NED method. Both methods were applied to a 1:1 (w/w) mixture of PETN and TNT (corresponding to the composition of military explosive 'Pentolite'). In order to eliminate the interference from TNT, the Meisenheimer anion of TNT formed in alkaline medium was retained on a strongly basic anion exchange resin column. As PETN had a very low solubility in water, common soil ions could be eliminated by prewashing the sample with water, or in acetone-water mixtures, Ca 2+ , K + , Cl - , SO 4 2- , and NO 3 - could be tolerated at equal (1:1) mass ratios. Soil nitrates and nitrites, at a mass ratio of 50:1, could be separated from PETN with the aid of their insolubilities in acetone and of their retention affinity toward a strongly basic anion-exchange resin. The developed method was statistically validated against a reference GC-MS method. Copyright © 2017 Elsevier B.V. All rights reserved.

Tetramethylbenzidine method for monitoring the free available chlorine and microbicidal activity of chlorite-based sanitizers under organic-matter-rich environments.

PubMed

Yamaoka, H; Nakayama-Imaohji, H; Horiuchi, I; Yamasaki, H; Nagao, T; Fujita, Y; Maeda, H; Goda, H; Kuwahara, T

2016-01-01

Chlorine is a principal disinfectant for food and environmental sanitation. Monitoring of free available chlorine (FAC) is essential for ensuring the efficacy of food disinfection processes that rely on chlorine. N,N-diethyl-p-phenylenediamine (DPD) is commonly used for FAC monitoring. However, here, we show that upon contact with bovine serum albumin (BSA) or broiler carcasses, chlorite (HClO2 )-based sanitizers acquire a pink colour, which can interfere with measurement of oxidized DPD absorbance at 513-550 nm. Alternatively, the pink colour did not interfere with 3,3',5,5'-tetramethylbenzidine (TMB)-based FAC monitoring. The FAC levels of NaClO and weakly acidified chlorous acid water (WACAW) were first adjusted by the TMB method and the killing activity of these sanitizers towards methicillin-resistant Staphylococcus aureus (MRSA) and feline calicivirus (FCV) was compared in the presence or absence of 0·5% BSA. At 200 ppm FAC, NaClO lost its bactericidal activity against MRSA after 10-min incubation with 0·5% BSA. Meanwhile, under the same conditions WACAW reduced the number of bacteria to below the detection limit. Similar results were obtained with FCV, indicating that the chlorite-based WACAW sanitizer is relatively stable under organic-matter-rich conditions. Moreover, TMB is suitable for in situ FAC monitoring of chlorite-based sanitizers in food and environmental disinfection processes. For practical applications of chlorine in food processing, monitoring of FAC is critical to validate disinfection efficacy. In this study we found that chlorite-based sanitizers acquired a pink colour upon contact with BSA or broiler carcasses. This pink colour interfered with FAC monitoring by methods that measure oxidized N,N-diethyl-p-phenylenediamine absorbance between 513-550 nm. Alternatively, FAC levels of chlorite-based sanitizers could be monitored using the absorbance of 3,3',5,5'-tetramethylbenzidine at 650 nm, which does not overlap with the acquired pink colour. These data provide valuable information for safety management of disinfection processes that use chlorite-based sanitizers. © 2015 The Society for Applied Microbiology.

Colorimetric end-tidal CO2 detector for verification of endotracheal tube placement in out-of-hospital cardiac arrest.

PubMed

Hayden, S R; Sciammarella, J; Viccellio, P; Thode, H; Delagi, R

1995-06-01

To evaluate the ability of a disposable, colorimetric end-tidal CO2 detector to verify proper endotracheal (ET) tube placement in out-of-hospital cardiac arrest, and to correlate semiquantitative CO2 measurements with the rate of return of spontaneous circulation (ROSC). Prospective, observational study using a convenience sample of intubated out-of-hospital cardiac arrest patients. A disposable, colorimetric end-tidal CO2 detector was attached to the ET tube after intubation. In the absence of a colorimetric change, the paramedics reassessed the tube placement and could reintubate the patient. Tube placement was verified at the hospital. Paramedics were instructed to contact the base station and report the colorimetric change upon hospital arrival. ROSC was defined as restoration of a self-sustaining pulse until hospital arrival. Between December 1990 and May 1993, ET tubes were placed in 566 victims of out-of-hospital cardiac arrest. 541 of the 566 intubations (95.6%) were associated with a color change. In one case with a color change and out-of-hospital clinical evidence of proper tube placement, the tube was determined to be in the esophagus at the hospital. Correct placement of the remaining 565 of 566 (99.8%) tubes was verified. Of the 566 patients who had a colorimetric change, 91 (16%) had ROSC vs one of 25 (4%) patients who did not have a color change. In one subgroup (n = 179), the degree of color change was highly associated with ROSC (p = 0.004). A disposable, colorimetric end-tidal CO2 detector appears reliable in verifying proper ET tube placement in victims of out-of-hospital cardiac arrest. The degree of color change correlates with the probability of ROSC.

A SIMPLE COLORIMETRIC METHOD TO DETECT BIOLOGICAL EVIDENCE OF HUMAN EXPOSURE TO MICROCYSTINS

EPA Science Inventory

Toxic cyanobacteria are contaminants of surface waters worldwide. Microcystins are some of the most commonly detected toxins. Biological evidence of human exposure may be difficult to obtain due to limitations associated with cost, laboratory capacity, analytic support, and exp...

Gold nanoparticles mediated colorimetric assay for HIV-Tat protein detection

NASA Astrophysics Data System (ADS)

Hashwan, Saeed S. Ba; Ruslinda, A. Rahim; Fatin, M. F.; Gopinath, Subash C. B.; Thivina, V.; Tony, V. C. S.; Arshad, M. K. Md.; Hashim, U.

2016-07-01

Gold-nanoparticle (AuNP) based colorimetric assays have been formulated for different biomolecular interactions. With this assay the probe such as antibody immobilized on the Au surface and in the presence of appropriate binding partner (antigen), will interact with each other on the Au surface. By following this strategy, herein we formulated a detection system with two anti-HIV-Tat antibodies, Mono (McAb) - and polyclonal (PcAb) by immobilizing them independently with different AuNPs. Under this condition, these two antibodies are under dispersed condition, and in the presence of HIV-Tat antigen, these molecules will be connected and forms the aggregation of AuNPs. This strategy yield rapid results, can be monitored by the spectral changes in UV-Vis spectrophotometry. Experiments were performed with two different methods using two anti-HIV-Tats monoclonal and one Polyclonal antibody against the antigen HIV-Tat. Between these methods conjugation of HIV-Tat and McAb on the AuNP followed by addition of PcAb yielded better results.

Mori-Zwanzig theory for dissipative forces in coarse-grained dynamics in the Markov limit

NASA Astrophysics Data System (ADS)

Izvekov, Sergei

2017-01-01

We derive alternative Markov approximations for the projected (stochastic) force and memory function in the coarse-grained (CG) generalized Langevin equation, which describes the time evolution of the center-of-mass coordinates of clusters of particles in the microscopic ensemble. This is done with the aid of the Mori-Zwanzig projection operator method based on the recently introduced projection operator [S. Izvekov, J. Chem. Phys. 138, 134106 (2013), 10.1063/1.4795091]. The derivation exploits the "generalized additive fluctuating force" representation to which the projected force reduces in the adopted projection operator formalism. For the projected force, we present a first-order time expansion which correctly extends the static fluctuating force ansatz with the terms necessary to maintain the required orthogonality of the projected dynamics in the Markov limit to the space of CG phase variables. The approximant of the memory function correctly accounts for the momentum dependence in the lowest (second) order and indicates that such a dependence may be important in the CG dynamics approaching the Markov limit. In the case of CG dynamics with a weak dependence of the memory effects on the particle momenta, the expression for the memory function presented in this work is applicable to non-Markov systems. The approximations are formulated in a propagator-free form allowing their efficient evaluation from the microscopic data sampled by standard molecular dynamics simulations. A numerical application is presented for a molecular liquid (nitromethane). With our formalism we do not observe the "plateau-value problem" if the friction tensors for dissipative particle dynamics (DPD) are computed using the Green-Kubo relation. Our formalism provides a consistent bottom-up route for hierarchical parametrization of DPD models from atomistic simulations.

Development and validation of a rapid and sensitive UPLC-MS/MS method for determination of uracil and dihydrouracil in human plasma.

PubMed

Jacobs, Bart A W; Rosing, Hilde; de Vries, Niels; Meulendijks, Didier; Henricks, Linda M; Schellens, Jan H M; Beijnen, Jos H

2016-07-15

Quantification of the endogenous dihydropyrimidine dehydrogenase (DPD) substrate uracil (U) and the reaction product dihydrouracil (UH2) in plasma might be suitable for identification of patients at risk of fluoropyrimidine-induced toxicity as a result of DPD deficiency. In this paper, we describe the development and validation of a rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay for quantification of U and UH2 in human plasma. Analytes were extracted by protein precipitation, chromatographically separated on an Acquity UPLC(®) HSS T3 column with gradient elution and analyzed with a tandem mass spectrometer equipped with an electrospray ionization source. U was quantified in the negative ion mode and UH2 in the positive ion mode. Stable isotopes for U and UH2 were used as internal standards. Total chromatographic run time was 5min. Validated concentration ranges for U and UH2 were from 1 to 100ng/mL and 10 to 1000ng/mL, respectively. Inter-assay bias and inter-assay precision for U were within ±2.8% and ≤12.4%. For UH2, inter-assay bias and inter-assay precision were within ±2.9% and ≤7.2%. Adequate stability of U and UH2 in dry extract, final extract, stock solution and plasma was demonstrated. Stability of U and UH2 in whole blood was only satisfactory when stored up to 4hours at 2-8°C, but not at ambient temperatures. An accurate, precise and sensitive UPLC-MS/MS assay for quantification of U and UH2 in plasma was developed. This assay is now applied to support clinical studies with fluoropyrimidine drugs. Copyright © 2016 Elsevier B.V. All rights reserved.

Dihydropyrimidine dehydrogenase pharmacogenetics for predicting fluoropyrimidine-related toxicity in the randomised, phase III adjuvant TOSCA trial in high-risk colon cancer patients

PubMed Central

Ruzzo, A; Graziano, F; Galli, Fabio; Galli, Francesca; Rulli, E; Lonardi, S; Ronzoni, M; Massidda, B; Zagonel, V; Pella, N; Mucciarini, C; Labianca, R; Ionta, M T; Bagaloni, I; Veltri, E; Sozzi, P; Barni, S; Ricci, V; Foltran, L; Nicolini, M; Biondi, E; Bramati, A; Turci, D; Lazzarelli, S; Verusio, C; Bergamo, F; Sobrero, A; Frontini, L; Menghi, M; Magnani, M

2017-01-01

Background: Dihydropyrimidine dehydrogenase (DPD) catabolises ∼85% of the administered dose of fluoropyrimidines. Functional DPYD gene variants cause reduced/abrogated DPD activity. DPYD variants analysis may help for defining individual patients’ risk of fluoropyrimidine-related severe toxicity. Methods: The TOSCA Italian randomised trial enrolled colon cancer patients for 3 or 6 months of either FOLFOX-4 or XELOX adjuvant chemotherapy. In an ancillary pharmacogenetic study, 10 DPYD variants (*2A rs3918290 G>A, *13 rs55886062 T>G, rs67376798 A>T, *4 rs1801158 G>A, *5 rs1801159 A>G, *6 rs1801160 G>A, *9A rs1801265 T>C, rs2297595 A>G, rs17376848 T>C, and rs75017182 C>G), were retrospectively tested for associations with ⩾grade 3 fluoropyrimidine-related adverse events (FAEs). An association analysis and a time-to-toxicity (TTT) analysis were planned. To adjust for multiple testing, the Benjamini and Hochberg’s False Discovery Rate (FDR) procedure was used. Results: FAEs occurred in 194 out of 508 assessable patients (38.2%). In the association analysis, FAEs occurred more frequently in *6 rs1801160 A allele carriers (FDR=0.0083). At multivariate TTT analysis, significant associations were found for *6 rs1801160 A allele carriers (FDR<0.0001), *2A rs3918290 A allele carriers (FDR<0.0001), and rs2297595 GG genotype carriers (FDR=0.0014). Neutropenia was the most common FAEs (28.5%). *6 rs1801160 (FDR<0.0001), and *2A rs3918290 (FDR=0.0004) variant alleles were significantly associated with time to neutropenia. Conclusions: This study adds evidence on the role of DPYD pharmacogenetics for safety of patients undergoing fluoropyrimidine-based chemotherapy. PMID:29065426

Pyrazolone as a recognition site: Rhodamine 6G-based fluorescent probe for the selective recognition of Fe3+ in acetonitrile-aqueous solution.

PubMed

Parihar, Sanjay; Boricha, Vinod P; Jadeja, R N

2015-03-01

Two novel Rhodamine-pyrazolone-based colorimetric off-on fluorescent chemosensors for Fe(3+) ions were designed and synthesized using pyrazolone as the recognition moiety and Rhodamine 6G as the signalling moiety. The photophysical properties and Fe(3+) -binding properties of sensors L(1) and L(2) in acetonitrile-aqueous solution were also investigated. Both sensors successfully exhibit a remarkably 'turn-on' response, toward Fe(3+) , which was attributed to 1: 2 complex formation between Fe(3+) and L(1) /L(2) . The fluorescent and colorimetric response to Fe(3+) can be detected by the naked eye, which provides a facile method for the visual detection of Fe(3+) . Copyright © 2014 John Wiley & Sons, Ltd.

A gold nanoparticles-based colorimetric test to detect single nucleotide polymorphisms for improvement of personalized therapy of psoriasis

NASA Astrophysics Data System (ADS)

Marsella, Alessandra; Valentini, Paola; Tarantino, Paolo; Congedo, Maurizio; Pompa, Pier Paolo

2016-04-01

We report a simple, rapid and low-cost test, based on gold nanoparticles, for the naked-eye colorimetric detection of a signature of single nucleotide polymorphisms (SNPs) relevant for the personalized medicine of psoriasis patients. We validated the colorimetric assay on real-world DNA samples from a cohort of 30 psoriasis patients and we compared the results, in double-blind, with those obtained with two state-of-the-art instrumental techniques, namely reverse dot blotting and direct sequencing, finding 100% agreement. We demonstrated high accuracy, sensitivity and specificity of the colorimetric test that can be easily adapted for the genotypization of different SNPs, important for the pharmacogenomics of various diseases, and in other fields, such as food traceability and population structure analysis.

EDTA analysis on the Roche MODULAR analyser.

PubMed

Davidson, D F

2007-05-01

Patient specimens can be subject to subtle interference from cross contamination by liquid-based, potassium-containing EDTA anticoagulant, leading to misinterpretation of results. A rapid method for EDTA analysis to detect such contamination is described. An in-house EDTA assay on the Roche MODULAR analyser was assessed for accuracy and precision by comparison with an adjusted calcium difference measurement (atomic absorption and o-cresolphthalein complexone colorimetry). EDTA method versus adjusted calcium difference showed: slope = 1.038 (95% confidence interval [CI] 0.949-1.131); intercept = 0.073 (95% CI 0.018-0.132) mmol/L; r = 0.914; n = 94. However, inter-assay precision of the calcium difference method was estimated to be poorer (coefficient of variation 24.8% versus 3.4% for the automated colorimetric method at an EDTA concentration of 0.25 mmol/L). Unequivocal contamination was observed at an EDTA concentration of > or =0.2 mmol/L. The automated method showed positive interference from haemolysis and negative interference from oxalate. The method was unaffected by lipaemia (triglycerides <20 mmol/L), icterus (bilirubin <500 micromol/L), glucose (<100 mmol/L), iron (<100 micromol/L), and citrate, phosphate or fluoride (all <2.5 mmol/L). The automated colorimetric assay described is an accurate, precise and rapid (3 min) means of detecting EDTA contamination of unhaemolysed biochemistry specimens.

Sulfuric acid/hydrogen peroxide digestion and colorimetric a collaborative study.

PubMed

Christians, D K; Aspelund, T G; Brayton, S V; Roberts, L L

1991-01-01

Seven laboratories participated in a collaborative study of a method for determination of phosphorus in meat and meat products. Samples are digested in sulfuric acid and hydrogen peroxide; digestion is complete in approximately 10 min. Phosphorus is determined by colorimetric analysis of a dilute aliquot of the sample digest. The collaborators analyzed 3 sets of blind duplicate samples from each of 6 classes of meat (U.S. Department of Agriculture classifications): smoked ham, water-added ham, canned ham, pork sausage, cooked sausage, and hamburger. The calibration curve was linear over the range of standard solutions prepared (phosphorus levels from 0.05 to 1.00%); levels in the collaborative study samples ranged from 0.10 to 0.30%. Standard deviations for repeatability (sr) and reproducibility (SR) ranged from 0.004 to 0.012 and 0.007 to 0.014, respectively. Corresponding relative standard deviations (RSDr and RSDR, respectively) ranged from 1.70 to 7.28% and 3.50 to 9.87%. Six laboratories analyzed samples by both the proposed method and AOAC method 24.016 (14th Ed.). One laboratory reported results by the proposed method only. Statistical evaluations indicated no significant difference between the 2 methods. The method has been adopted official first action by AOAC.

A digital image method of spot tests for determination of copper in sugar cane spirits

NASA Astrophysics Data System (ADS)

Pessoa, Kenia Dias; Suarez, Willian Toito; dos Reis, Marina Ferreira; de Oliveira Krambeck Franco, Mathews; Moreira, Renata Pereira Lopes; dos Santos, Vagner Bezerra

2017-10-01

In this work the development and validation of analytical methodology for determination of copper in sugarcane spirit samples is carried out. The digital image based (DIB) method was applied along with spot test from the colorimetric reaction employing the RGB color model. For the determination of copper concentration, it was used the cuprizone - a bidentate organic reagent - which forms with copper a blue chelate in an alkaline medium. A linear calibration curve over the concentration range from 0.75 to 5.00 mg L- 1 (r2 = 0.9988) was obtained and limits of detection and quantification of 0.078 mg L- 1 and 0.26 mg L- 1 were acquired, respectively. For the accuracy studies, recovery percentages ranged from 98 to 104% were obtained. The comparison of cooper concentration results in sugar cane spirits using the DIB method and Flame Atomic Absorption Spectrometry as reference method showed no significant differences between both methods, which were performed using the paired t-test in 95% of confidence level. Thus, the spot test method associated with DIB allows the use of devices as digital cameras and smartphones to evaluate colorimetric reaction with low waste generation, practicality, quickness, accuracy, precision, high portability and low-cost.

MATRIX DISCRIMINANT ANALYSIS WITH APPLICATION TO COLORIMETRIC SENSOR ARRAY DATA

PubMed Central

Suslick, Kenneth S.

2014-01-01

With the rapid development of nano-technology, a “colorimetric sensor array” (CSA) which is referred to as an optical electronic nose has been developed for the identification of toxicants. Unlike traditional sensors which rely on a single chemical interaction, CSA can measure multiple chemical interactions by using chemo-responsive dyes. The color changes of the chemo-responsive dyes are recorded before and after exposure to toxicants and serve as a template for classification. The color changes are digitalized in the form of a matrix with rows representing dye effects and columns representing the spectrum of colors. Thus, matrix-classification methods are highly desirable. In this article, we develop a novel classification method, matrix discriminant analysis (MDA), which is a generalization of linear discriminant analysis (LDA) for the data in matrix form. By incorporating the intrinsic matrix-structure of the data in discriminant analysis, the proposed method can improve CSA’s sensitivity and more importantly, specificity. A penalized MDA method, PMDA, is also introduced to further incorporate sparsity structure in discriminant function. Numerical studies suggest that the proposed MDA and PMDA methods outperform LDA and other competing discriminant methods for matrix predictors. The asymptotic consistency of MDA is also established. R code and data are available online as supplementary material. PMID:26783371

Two Methods of Determining Total Phenolic Content of Foods and Juices in a General, Organic, and Biological (GOB) Chemistry Lab

ERIC Educational Resources Information Center

Shaver, Lee Alan; Leung, Sam H.; Puderbaugh, Amy; Angel, Stephen A.

2011-01-01

The determination of total phenolics in foods and fruit juices was used successfully as a laboratory experiment in our undergraduate general, organic, and biological (GOB) chemistry course. Two different colorimetric methods were used over three years and comparative student results indicate that a ferrous ammonium sulfate (FAS) indicator…

A simple and rapid creatinine sensing via DLS selectivity, using calix[4]arene thiol functionalized gold nanoparticles.

PubMed

Sutariya, Pinkesh G; Pandya, Alok; Lodha, Anand; Menon, Shobhana K

2016-01-15

A new, simple, ultra-sensitive and selective approach has been reported for the "on spot" colorimetric detection of creatinine based on calix[4]arene functionalized gold nanoparticles (AuNPs) with excellent discrimination in the presence of other biomolecules. The lower detection limit of the method is 2.16nM. The gold nanoparticles and p-tert-butylcalix[4]arene were synthesized by microwave assisted method. Specifically, in our study, we used dynamic light scattering (DLS) which is a powerful method for the determination of small changes in particle size, improved selectivity and sensitivity of the creatinine detection system over colorimetric method. The nanoassembly is characterized by Transmission electron microscopy (TEM), DLS, UV-vis and ESI-MS spectroscopy, which demonstrates the binding affinity due its ability of hydrogen bonding and electrostatic interaction between -NH group of creatinine and pSDSC4. It exhibits fast response time (<60s) to creatinine and has long shelf-life (>5 weeks). The developed pSDSC4-AuNPs based creatinine biosensor will be established as simple, reliable and accurate tool for the determination of creatinine in human urine samples. Copyright © 2015 Elsevier B.V. All rights reserved.

A new colorimetric method to quantify β-1,3-1,6-glucans in comparison with total β-1,3-glucans in edible mushrooms.

PubMed

Nitschke, Jörg; Modick, Hendrik; Busch, Ekkehard; von Rekowski, Reimund Wantoch; Altenbach, Hans-Josef; Mölleken, Helga

2011-07-15

Mushroom β-glucans are known for their activity as biological response modifiers and anticarcinogenic agents. β-1,3-1,6 Branched glucans with a triple helix tertiary structure are recognised as the most potent ones. In the present work, a colorimetric method for β-1,3-1,6-glucan quantification based on the dye Congo red is introduced. This method is specific for β-glucans with a triple helix. The β-1,3-1,6-glucan content of mycelia and fruiting bodies from various mushrooms was determined and compared with the total β-1,3-glucan content, measured by a fluorimetric method. The results show equal amounts of β-1,3-1,6- and total β-1,3-glucans in the analysed species but obvious differences between mycelia and fruiting bodies. On the average, 3% of mycelia and 8% of fruiting body dry mass consist of β-1,3-1,6-glucans. The average percentage of β-1,3-1,6-glucans in the total β-1,3-glucan content differs between mycelia (46%) and fruiting bodies (87%). Copyright © 2011 Elsevier Ltd. All rights reserved.

A novel biphenolic ligand for selective Mg2+ and Zn2+ ions sensing followed by colorimetric, spectroscopic and cell imaging methods.

PubMed

Maheswari, Palanisamy Uma; Renuga, Duraisamy; Henry, Linda Jeeva Kumari; Ruckmani, Kandasamy

2018-04-30

The (E)-2-((2-hydrohy-5-methylphenylimino) methyl) phenol ligand was synthesized. The receptor was characterized by IR, 1 H and 13 C NMR and CHN analysis. The ligand exhibits colorimetric and fluorometric sensing of Zn 2+ and Mg 2+ ions in semi-aqueous medium (DMSO-H2O). The receptor was tested with series of transition metal ions (Cr 2+ , Fe 2+ , Ni 2+ , Co 2+ , Cu 2+ , Zn 2+ ) and heavy metal ions (Sn 2+ , Pd 2+ , Ce 2+ , Hg 2+ , Cd 2+ ) and the essential human body elements like Ca 2+ , Mg 2+ , Na + and K + ions. The naked eye colorimetric sensing was absorbed only for Zn 2+ and Mg 2+ . Both ions (ZnCl 2 and MgCl 2 in H 2 O), when added to the colorless solutions of the receptor of about 1 equivalence in incremental additions turn the solution into bright turmeric yellow. All other ions remain inactive, in colorimetric sensing. Further the Zn 2+ and Mg 2+ ions were probed by absorption and emission spectroscopy through incremental addition of respective metal ions. The in-situ deprotonation of the ligand on both Mg 2+ and Zn 2+ ions binding was confirmed by 1 H NMR titration studies. The imino nitrogen of the receptor is not coordinated to the metal ions. The Job's plot studies reveal the 1:2 binding ratio of metal ions to the receptor. The high fold fluorescence output on metal ions binding was positively used to sense the Zn 2+ and Mg 2+ ions, separately and together in HeLa cancer cells through cell imaging. Copyright © 2018 Elsevier B.V. All rights reserved.

Colorimetric detection of mercury ion based on unmodified gold nanoparticles and target-triggered hybridization chain reaction amplification

NASA Astrophysics Data System (ADS)

Wang, Qing; Yang, Xiaohan; Yang, Xiaohai; Liu, Pei; Wang, Kemin; Huang, Jin; Liu, Jianbo; Song, Chunxia; Wang, Jingjing

2015-02-01

A novel unmodified gold nanoparticles (AuNPs)-based colorimetric strategy for label-free, specific and sensitive mercury ion (Hg2+) detection was demonstrated by using thymine-Hg2+-thymine (T-Hg2+-T) recognition mechanism and hybridization chain reaction (HCR) amplification strategy. In this protocol, a structure-switching probe (H0) was designed to recognize Hg2+ and then propagated a chain reaction of hybridization events between two other hairpin probes (H1 and H2). In the absence of Hg2+, all hairpin probes could stably coexist in solution, the exposed sticky ends of hairpin probes were capable of stabilizing AuNPs. As a result, salt-induced AuNPs aggregation could be effectively prevented. In the presence of Hg2+, thymine bases of H0 could specifically interact with Hg2+ to form stable T-Hg2+-T complex. Consequently, the hairpin structure of H0 probe was changed. As H1/H2 probes were added, the HCR process could be triggered and nicked double-helixes were formed. Since it was difficult for the formed nicked double-helixes to inhibit salt-induced AuNPs aggregation, a red-to-blue color change was observed in the colloid solution as the salt concentration increased. With the elegant amplification effect of HCR, a detection limit of around 30 nM was achieved (S/N = 3), which was about 1-2 orders of magnitudes lower than that of previous unmodified AuNPs-based colorimetric methods. By using the T-Hg2+-T recognition mechanism, high selectivity was also obtained. As an unmodified AuNPs-based colorimetric strategy, the system was simple in design, convenient in operation, and eliminated the requirements of separation processes, chemical modifications, and sophisticated instrumentations.

Detection and Spatial Mapping of Mercury Contamination in Water Samples Using a Smart-Phone

DTIC Science & Technology

2014-01-20

Au NP) and aptamer based colorimetric transmission assay that is implemented in disposable test tubes. With this smart-phone attachment that weighs...detection . colorimetric sensor . gold nanoparticles . aptamers A RTIC LE Terms of Use WEI ET AL. VOL. 8 ’ NO. 2 ’ 1121–1129 ’ 2014 www.acsnano.org 1122...a colorimetric assay utilizing citrate-stabilized plasmonic AuNPs and aptamers (Apt) mixed within disposable test tubes. Due to the shift in the

Integration of Novel Low-Cost Colorimetric, Laser Photometric, and Visual Fluorescent Techniques for Rapid Identification of Falsified Medicines in Resource-Poor Areas: Application to Artemether–Lumefantrine

PubMed Central

Green, Michael D.; Hostetler, Dana M.; Nettey, Henry; Swamidoss, Isabel; Ranieri, Nicola; Newton, Paul N.

2015-01-01

The availability of falsified antimalarial drugs can be reduced with effective drug regulatory agencies and proper enforcement. Fundamental to these agencies taking action, rapid identification must be made as soon as they appear in the market place. Since falsified antimalarials occur mostly in developing countries, performing drug analysis presents itself with unique challenges. A fundamental factor in choosing a useful technique is affordability and simplicity. Therefore, we suggest a three-tiered drug evaluation strategy for identifying a falsified drug in resource-poor areas. Tier I is a simple comparison of a tablet's weight and dimensions with official specifications. Tier II uses inexpensive photometric devices (laser and fluorescence) to evaluate a tablet. Suspicious samples from Tier I and II assessments are then subjected to a colorimetric assay for active ingredients identification and quantification. In this article, we evaluate a novel colorimetric assay for the simultaneous assessment of both lumefantrine and artemether in co-formulated Coartem™ tablets, and integrate the method with two novel, low-cost, fluorescence and laser photometric devices. Image analysis software is used for the assessments. Although artemether–lumefantrine is used as an example, the strategy may be adapted to other medicines. PMID:25897066

A novel colorimetric aptasensor for ultrasensitive detection of cocaine based on the formation of three-way junction pockets on the surfaces of gold nanoparticles.

PubMed

Abnous, Khalil; Danesh, Noor Mohammad; Ramezani, Mohammad; Taghdisi, Seyed Mohammad; Emrani, Ahmad Sarreshtehdar

2018-08-22

Herein, a novel colorimetric aptasensor was introduced for detection of cocaine based on the formation of three-way junction pockets on the surfaces of gold nanoparticles (AuNPs) and the catalytic activity of the surfaces of AuNPs. Simplicity and detection of cocaine in a short time (only 35 min) are some of the unique features of the proposed sensing strategy. In the presence of cocaine, triple-fragment aptamer (TFA) forms on the surfaces of AuNPs, leading to a significant decrease of the catalytic activity of AuNPs and the color of samples remains yellow. In the absence of target, TFA does not form on the surfaces of AuNPs and 4-Nitrophenol, as a colorimetric agent, has more access to the surfaces of AuNPs, resulting in the reduction of 4-Nitrophenol and the color of sample changes from yellow to colorless. The sensing strategy showed good specificity, a limit of detection (LOD) of 440 pM and a dynamic range over 2-100 nM. The sensing method was also successfully applied to detect cocaine in spiked human serum samples with recovery of 94.71-98.63%. Copyright © 2018 Elsevier B.V. All rights reserved.

Integration of novel low-cost colorimetric, laser photometric, and visual fluorescent techniques for rapid identification of falsified medicines in resource-poor areas: application to artemether-lumefantrine.

PubMed

Green, Michael D; Hostetler, Dana M; Nettey, Henry; Swamidoss, Isabel; Ranieri, Nicola; Newton, Paul N

2015-06-01

The availability of falsified antimalarial drugs can be reduced with effective drug regulatory agencies and proper enforcement. Fundamental to these agencies taking action, rapid identification must be made as soon as they appear in the market place. Since falsified antimalarials occur mostly in developing countries, performing drug analysis presents itself with unique challenges. A fundamental factor in choosing a useful technique is affordability and simplicity. Therefore, we suggest a three-tiered drug evaluation strategy for identifying a falsified drug in resource-poor areas. Tier I is a simple comparison of a tablet's weight and dimensions with official specifications. Tier II uses inexpensive photometric devices (laser and fluorescence) to evaluate a tablet. Suspicious samples from Tier I and II assessments are then subjected to a colorimetric assay for active ingredients identification and quantification. In this article, we evaluate a novel colorimetric assay for the simultaneous assessment of both lumefantrine and artemether in co-formulated Coartem™ tablets, and integrate the method with two novel, low-cost, fluorescence and laser photometric devices. Image analysis software is used for the assessments. Although artemether-lumefantrine is used as an example, the strategy may be adapted to other medicines. © The American Society of Tropical Medicine and Hygiene.

A Simple Colorimetric Assay for Specific Detection of Glutathione-S Transferase Activity Associated with DDT Resistance in Mosquitoes

PubMed Central

Rajatileka, Shavanti; Steven, Andrew; Hemingway, Janet; Ranson, Hilary; Paine, Mark; Vontas, John

2010-01-01

Background Insecticide-based methods represent the most effective means of blocking the transmission of vector borne diseases. However, insecticide resistance poses a serious threat and there is a need for tools, such as diagnostic tests for resistance detection, that will improve the sustainability of control interventions. The development of such tools for metabolism-based resistance in mosquito vectors lags behind those for target site resistance mutations. Methodology/Principal Findings We have developed and validated a simple colorimetric assay for the detection of Epsilon class Glutathione transferases (GST)-based DDT resistance in mosquito species, such as Aedes aegypti, the major vector of dengue and yellow fever worldwide. The colorimetric assay is based on the specific alkyl transferase activity of Epsilon GSTs for the haloalkene substrate iodoethane, which produces a dark blue colour highly correlated with AaGSTE2-2-overexpression in individual mosquitoes. The colour can be measured visually and spectrophotometrically. Conclusions/Significance The novel assay is substantially more sensitive compared to the gold standard CDNB assay and allows the discrimination of moderate resistance phenotypes. We anticipate that it will have direct application in routine vector monitoring as a resistance indicator and possibly an important impact on disease vector control. PMID:20824165

Dual-Modal Colorimetric/Fluorescence Molecular Probe for Ratiometric Sensing of pH and Its Application.

PubMed

Wu, Luling; Li, Xiaolin; Huang, Chusen; Jia, Nengqin

2016-08-16

As traditional pH meters cannot work well for minute regions (such as subcellular organelles) and in harsh media, molecular pH-sensitive devices for monitoring pH changes in diverse local heterogeneous environments are urgently needed. Here, we report a new dual-modal colorimetric/fluorescence merocyanine-based molecular probe (CPH) for ratiometric sensing of pH. Compared with previously reported pH probes, CPH bearing the benzyl group at the nitrogen position of the indolium group and the phenol, which is used as the acceptor for proton, could respond to pH changes immediately through both the ratiometric fluorescence signal readout and naked-eye colorimetric observation. The sensing process was highly stable and reversible. Most importantly, the suitable pKa value (6.44) allows CPH to presumably accumulate in lysosomes and become a lysosome-target fluorescent probe. By using CPH, the intralysosomal pH fluctuation stimulated by antimalaria drug chloroquine was successfully tracked in live cells through the ratiometric fluorescence images. Additionally, CPH could be immobilized on test papers, which exhibited a rapid and reversible colorimetric response to acid/base vapor through the naked-eye colorimetric analysis. This proof-of-concept study presents the potential application of CPH as a molecular tool for monitoring intralysosomal pH fluctuation in live cells, as well as paves the way for developing the economic, reusable, and fast-response optical pH meters for colorimetric sensing acid/base vapor with direct naked-eye observation.

Identification of human flavin-containing monooxygenase 3 substrates by a colorimetric screening assay.

PubMed

Catucci, Gianluca; Polignano, Isabelle; Cusumano, Debora; Medana, Claudio; Gilardi, Gianfranco; Sadeghi, Sheila J

2017-04-01

Human hepatic flavin-containing monooxygenase 3 is a phase I drug-metabolizing enzyme that is responsible for the oxidation of a variety of drugs and xenobiotics. This work reports on a high throughput rapid colorimetric assay for the screening of substrates or inhibitors of this enzyme. The method is based on the competition of two substrates for access to the active site of hFMO3 whereby the enzymatic product of the first drug converts nitro-5-thiobenzoate (TNB, yellow) to 5,5'-dithiobis (2-nitrobenzoate) (DTNB, colourless). Upon addition of a competing substrate, the amount of detected DNTB is decreased. The assay is validated testing three known substrates of hFMO3, namely benzydamine, tozasertib and tamoxifen. The latter drugs resulted in 41%-55% inhibition. In addition, two other drugs also classified as doping drugs, selegiline and clomiphene, were selected based on their chemical structure similarity to known substrates of hFMO3. These drugs showed 21% and 60% inhibition in the colorimetric assay and therefore were proven to be hFMO3 substrates. LC-MS was used to confirm their N-oxide products. Further characterisation of these newly identified hFMO3 substrates was performed determining their K m and k cat values that resulted to be 314 μM and 1.4 min -1 for selegiline and, 18 μM and 0.1 min -1 for clomiphene. This method paves the way for a rapid automated high throughput screening of nitrogen-containing compounds as substrates/inhibitors of hFMO3. Copyright © 2017 Elsevier Inc. All rights reserved.

Visualisation of gas-liquid mass transfer around a rising bubble in a quiescent liquid using an oxygen sensitive dye

NASA Astrophysics Data System (ADS)

Dietrich, Nicolas; Hebrard, Gilles

2018-02-01

An approach for visualizing and measuring the mass transfer around a single bubble rising in a quiescent liquid is reported. A colorimetric technique, developed by (Dietrich et al. Chem Eng Sci 100:172-182, 2013) using an oxygen sensitive redox dye was implemented. It was based on the reduction of the colorimetric indicator in presence of oxygen, this reduction being catalysed by sodium hydroxide and glucose. In this study, resazurin was selected because it offered various reduced forms with colours ranging from transparent (without oxygen) to pink (in presence of oxygen). These advantages made it possible to visualize the spatio-temporal oxygen mass transfer around rising bubbles. Images were recorded by a CCD camera and, after post-processing, the shape, size, and velocity of the bubbles were measured and the colours around the bubbles mapped. A calibration, linking the level of colour with the dissolved oxygen concentration, enabled colour maps to be converted into oxygen concentration fields. A rheoscopic fluid was used to visualize the wake of the bubbles. A calculation method was also developed to determine the transferred oxygen fluxes around bubbles of two sizes (d = 0.82 mm and d = 2.12 mm) and the associated liquid-side mass transfer coefficients. The results compared satisfactorily with classical global measurements made by oxygen micro-sensors or from the classical models. This study thus constitutes a striking example of how this new colorimetric method could become a remarkable tool for exploring gas-liquid mass transfer in fluids.

Visualisation of gas-liquid mass transfer around a rising bubble in a quiescent liquid using an oxygen sensitive dye

NASA Astrophysics Data System (ADS)

Dietrich, Nicolas; Hebrard, Gilles

2018-07-01

An approach for visualizing and measuring the mass transfer around a single bubble rising in a quiescent liquid is reported. A colorimetric technique, developed by (Dietrich et al. Chem Eng Sci 100:172-182, 2013) using an oxygen sensitive redox dye was implemented. It was based on the reduction of the colorimetric indicator in presence of oxygen, this reduction being catalysed by sodium hydroxide and glucose. In this study, resazurin was selected because it offered various reduced forms with colours ranging from transparent (without oxygen) to pink (in presence of oxygen). These advantages made it possible to visualize the spatio-temporal oxygen mass transfer around rising bubbles. Images were recorded by a CCD camera and, after post-processing, the shape, size, and velocity of the bubbles were measured and the colours around the bubbles mapped. A calibration, linking the level of colour with the dissolved oxygen concentration, enabled colour maps to be converted into oxygen concentration fields. A rheoscopic fluid was used to visualize the wake of the bubbles. A calculation method was also developed to determine the transferred oxygen fluxes around bubbles of two sizes (d = 0.82 mm and d = 2.12 mm) and the associated liquid-side mass transfer coefficients. The results compared satisfactorily with classical global measurements made by oxygen micro-sensors or from the classical models. This study thus constitutes a striking example of how this new colorimetric method could become a remarkable tool for exploring gas-liquid mass transfer in fluids.

Fabricating a UV-Vis and Raman Spectroscopy Immunoassay Platform.

PubMed

Hanson, Cynthia; Israelsen, Nathan D; Sieverts, Michael; Vargis, Elizabeth

2016-11-10

Immunoassays are used to detect proteins based on the presence of associated antibodies. Because of their extensive use in research and clinical settings, a large infrastructure of immunoassay instruments and materials can be found. For example, 96- and 384-well polystyrene plates are available commercially and have a standard design to accommodate ultraviolet-visible (UV-Vis) spectroscopy machines from various manufacturers. In addition, a wide variety of immunoglobulins, detection tags, and blocking agents for customized immunoassay designs such as enzyme-linked immunosorbent assays (ELISA) are available. Despite the existing infrastructure, standard ELISA kits do not meet all research needs, requiring individualized immunoassay development, which can be expensive and time-consuming. For example, ELISA kits have low multiplexing (detection of more than one analyte at a time) capabilities as they usually depend on fluorescence or colorimetric methods for detection. Colorimetric and fluorescent-based analyses have limited multiplexing capabilities due to broad spectral peaks. In contrast, Raman spectroscopy-based methods have a much greater capability for multiplexing due to narrow emission peaks. Another advantage of Raman spectroscopy is that Raman reporters experience significantly less photobleaching than fluorescent tags 1 . Despite the advantages that Raman reporters have over fluorescent and colorimetric tags, protocols to fabricate Raman-based immunoassays are limited. The purpose of this paper is to provide a protocol to prepare functionalized probes to use in conjunction with polystyrene plates for direct detection of analytes by UV-Vis analysis and Raman spectroscopy. This protocol will allow researchers to take a do-it-yourself approach for future multi-analyte detection while capitalizing on pre-established infrastructure.

On-Board Monitoring of Engine Oil

DTIC Science & Technology

2011-04-01

Viscosity of Transparent and Opaque Liquids at 40°C Infracal Soot Meter Karl Fischer Titration ASTM D 664 Standard Test Method for Acid Number of... methods involve potentiometric and colorimetric titrations, respectively. For both tests, a titration solvent is prepared and added to the oil. The...ASTM D 2896 and ASTM D 4739 [17]. Both methods involve potentiometric titrations. ASTM D 2896 uses a stronger acid and more polar solvent than ASTM D

Colorimetric values of esthetic stainless steel crowns.

PubMed

Hosoya, Yumiko; Omachi, Koichi; Staninec, Michal

2002-01-01

The colorimetric values of two different kinds of esthetic stainless steel crowns were measured and compared with the colorimetric values of primary anterior teeth in Japanese children. The colorimetric values of resin composite-faced stainless steel crowns (Kinder Krown) and epoxy-coated stainless steel crowns (White Steel Crown) were measured with a color difference meter. The Commission Internationale de Eclairage L*, a*, b*, and delta E*ab values and Munsell value, chroma, and hue were calculated. The data were compared with previously reported colorimetric values of Japanese primary anterior teeth measured with the same color difference meter used in this study. Compared to Japanese primary anterior teeth, Kinder Krown Pedo I and Pedo II showed much higher L* values and lower hue; on the other hand, White Steel Crown showed much higher L*, a*, b* values, much higher value and chroma, and much lower hue. Color analysis revealed that the colors of the White Steel Crown and Kinder Krown Pedo I were substantially different from the color of Japanese primary anterior teeth. The color difference between Pedo II crowns and Japanese primary anterior teeth was relatively high, but the color of Pedo II might be acceptable for clinical use.

Colorimetric detection of Cr (VI) based on the leaching of gold nanoparticles using a paper-based sensor.

PubMed

Guo, Jian-Feng; Huo, Dan-Qun; Yang, Mei; Hou, Chang-Jun; Li, Jun-Jie; Fa, Huan-Bao; Luo, Hui-Bo; Yang, Ping

2016-12-01

Herein, we have developed a simple, sensitive and paper-based colorimetric sensor for the selective detection of Chromium (Ⅵ) ions (Cr (VI)). Silanization-titanium dioxide modified filter paper (STCP) was used to trap bovine serum albumin capped gold nanoparticles (BSA-Au NPs), leading to the fabrication of BSA-Au NPs decorated membrane (BSA-Au NPs/STCP). The BSA-Au NPs/STCP operated on the principle that BSA-Au NPs anchored on the STCP were gradually etched by Cr (VI) as the leaching process of gold in the presence of hydrobromic acid (HBr) and hence induced a visible color change. Under optimum conditions, the paper-based colorimetric sensor showed clear color change after reaction with Cr (VI) as well as with favorable selectivity to a variety of possible interfering counterparts. The amount-dependent colorimetric response was linearly correlated with the Cr (VI) concentrations ranging from 0.5µM to 50.0µM with a detection limit down to 280nM. Moreover, the developed cost-effective colorimetric sensor has been successfully applied to real environmental samples which demonstrated the potential for field applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Photonic Crystal Structures with Tunable Structure Color as Colorimetric Sensors

PubMed Central

Wang, Hui; Zhang, Ke-Qin

2013-01-01

Colorimetric sensing, which transduces environmental changes into visible color changes, provides a simple yet powerful detection mechanism that is well-suited to the development of low-cost and low-power sensors. A new approach in colorimetric sensing exploits the structural color of photonic crystals (PCs) to create environmentally-influenced color-changeable materials. PCs are composed of periodic dielectrics or metallo-dielectric nanostructures that affect the propagation of electromagnetic waves (EM) by defining the allowed and forbidden photonic bands. Simultaneously, an amazing variety of naturally occurring biological systems exhibit iridescent color due to the presence of PC structures throughout multi-dimensional space. In particular, some kinds of the structural colors in living organisms can be reversibly changed in reaction to external stimuli. Based on the lessons learned from natural photonic structures, some specific examples of PCs-based colorimetric sensors are presented in detail to demonstrate their unprecedented potential in practical applications, such as the detections of temperature, pH, ionic species, solvents, vapor, humidity, pressure and biomolecules. The combination of the nanofabrication technique, useful design methodologies inspired by biological systems and colorimetric sensing will lead to substantial developments in low-cost, miniaturized and widely deployable optical sensors. PMID:23539027

NAA For Human Serum Analysis: Comparison With Conventional Analyses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oliveira, Laura C.; Zamboni, Cibele B.; Medeiros, Jose A. G.

2010-08-04

Instrumental and Comparator methods of Neutron Activation Analysis (NAA) were applied to determine elements of clinical relevancy in serum samples of adult population (Sao Paulo city, Brazil). A comparison with the conventional analyses, Colorimetric for calcium, Titrymetric for chlorine and Ion Specific Electrode for sodium and potassium determination were also performed permitting a discussion about the performance of NAA methods for clinical chemistry research.

Assessment of Remaining Lubricant Life

DTIC Science & Technology

1986-11-01

tioxidant, inexpensive spectrophotometers are used. However, the greatest advantage of the Mitsubishi chemical stressing technique was the fact that it uses...samples, the method’s main advantage over the thermal stressing techniques is eliminated. The colorimetric method had the advantage over induction period...decrease of 18 torr. The main advantage of defining the induction period in this manner is that it eliminates any need for interpretation by the

Oxalate analysis methodology for decayed wood

Treesearch

Carol A. Clausen; William Kenealy; Patricia K. Lebow

2008-01-01

Oxalate from partially decayed southern pine wood was analyzed by HPLC or colorimetric assay. Oxalate extraction efficiency, assessed by comparing analysis of whole wood cubes with ground wood, showed that both wood geometries could be extracted with comparable efficiency. To differentiate soluble oxalate from total oxalate, three extraction methods were assessed,...

A net fishing enrichment strategy for colorimetric detection of E. coli O157:H7

USDA-ARS?s Scientific Manuscript database

The strict regulatory requirements for pathogen monitoring in food systems to ensure safety demands that the detection method can recognize small numbers of pathogens. Although significant efforts on the development of biosensors have been reported with marked improvement in sensitivity, appropriate...

40 CFR 63.323 - Test methods and monitoring.

Code of Federal Regulations, 2012 CFR

2012-07-01

... downstream from any flow disturbance such as a bend, expansion, contraction, or outlet; downstream from no other inlet; and 2 stack or duct diameters upstream from any flow disturbance such as a bend, expansion... monitoring by inserting the colorimetric detector or PCE gas analyzer tube into the open space above the...

40 CFR 63.323 - Test methods and monitoring.

Code of Federal Regulations, 2014 CFR

2014-07-01

... downstream from any flow disturbance such as a bend, expansion, contraction, or outlet; downstream from no other inlet; and 2 stack or duct diameters upstream from any flow disturbance such as a bend, expansion... monitoring by inserting the colorimetric detector or PCE gas analyzer tube into the open space above the...

40 CFR 63.323 - Test methods and monitoring.

Code of Federal Regulations, 2013 CFR

2013-07-01

... downstream from any flow disturbance such as a bend, expansion, contraction, or outlet; downstream from no other inlet; and 2 stack or duct diameters upstream from any flow disturbance such as a bend, expansion... monitoring by inserting the colorimetric detector or PCE gas analyzer tube into the open space above the...

Rapid quantification of proanthocyanidins (condensed tannins) with a continuous flow analyzer

Treesearch

James K. Nitao; Bruce A. Birr; Muraleedharan G. Nair; Daniel A. Herms; William J. Mattson

2001-01-01

Proanthocyanidins (condensed tannins) frequently need to be quantified in large numbers of samples in food, plant, and environmental studies. An automated colorimetric method to quantify proanthocyanidins with sulfuric acid (H2SO4) was therefore developed for use in a continuous flow analyzer. Assay conditions were...

Characterization of Soil Samples of Enzyme Activity

ERIC Educational Resources Information Center

Freeland, P. W.

1977-01-01

Described are nine enzyme essays for distinguishing soil samples. Colorimetric methods are used to compare enzyme levels in soils from different sites. Each soil tested had its own spectrum of activity. Attention is drawn to applications of this technique in forensic science and in studies of soil fertility. (Author/AJ)

Use of a Simple, Colorimetric Assay to Demonstrate Conditions for Induction of Nitrate Reductase in Plants.

ERIC Educational Resources Information Center

Harley, Suzanne M.

1993-01-01

Nitrate assimilation by plants provides an excellent system for demonstrating control of gene expression in a eukaryotic organism. Describes an assay method that allows students to complete experiments designed around the measurement of nitrate reductase within a three-hour laboratory experiment. (PR)

Considerations on the Analytical Control of Sulfur Traces in Uranium Metal; CONSIDERACIONES SOBRE EL CONTROL ANALITICO DE TRAZAS DE AZUFRE (SULFURO) EN URANIO METAL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cellini, R.F.; Sanchez, L.G.

1956-01-01

Volumetric and colorimetric determinations of sulfur in uranium were carried out by acid treatment and evaluation of SH/sup 2/. According to the experimental results a discussion of both methods was made. (auth)

Reconsideration of the Zincke salt: An efficient colorimetric chemosensor for detection of ethylamines

NASA Astrophysics Data System (ADS)

Kim, Jong H.

2018-03-01

In this work, an efficient colorimetric chemosensor for the detection of ethylamines using a pyridinium salt (the Zincke salt) is reported. Highly sensitive and selective reactivity of the Zincke salt enables colorimetric response of the Zincke salt solution to the ethylamines by showing well-defined visible color changes from colorless to the deep red. Furthermore, the Zincke salt thin film exhibits discernable color changes in response to ethylamine gas as well, which allows fabrication of simple, fast and portable strip- and textile-type ethylamine sensors.

Pyrrole based Schiff bases as colorimetric and fluorescent chemosensors for fluoride and hydroxide anions.

PubMed

Velmathi, Sivan; Reena, Vijayaraghavan; Suganya, Sivalingam; Anandan, Sambandam

2012-01-01

An efficient colorimetric sensor with pyrrole-NH moiety as binding site and nitro group as a signaling unit has been synthesized by a one step procedure and characterized by spectroscopic techniques, which displays excellent selectivity and sensitivity for fluoride and hydroxide ions. The hydrogen bonding with these anions provides remarkable colorimetric responses. (1)H NMR and FT IR studies has been carried out to confirm the hydrogen bonding. UV-vis and fluorescence spectral changes can be exploited for real time and on site application.

Simple, field portable colorimetric detection device for organic peroxides and hydrogen peroxide

DOEpatents

Pagoria, Philip F.; Mitchell, Alexander R.; Whipple, Richard E.; Carman, M. Leslie; Reynolds, John G.; Nunes, Peter; Shields, Sharon J.

2010-11-09

A simple and effective system for the colorimetric determination of organic peroxides and hydrogen peroxide. A peroxide pen utilizing a swipe material attached to a polyethylene tube contains two crushable vials. The two crushable vials contain a colorimetric reagent separated into dry ingredients and liquid ingredients. After swiping a suspected substance or surface the vials are broken, the reagent is mixed thoroughly and the reagent is allowed to wick into the swipe material. The presence of organic peroxides or hydrogen peroxide is confirmed by a deep blue color.

An azodye-rhodamine-based fluorescent and colorimetric probe specific for the detection of Pd(2+) in aqueous ethanolic solution: synthesis, XRD characterization, computational studies and imaging in live cells.

PubMed

Mahapatra, Ajit Kumar; Manna, Saikat Kumar; Maiti, Kalipada; Mondal, Sanchita; Maji, Rajkishor; Mandal, Debasish; Mandal, Sukhendu; Uddin, Md Raihan; Goswami, Shyamaprosad; Quah, Ching Kheng; Fun, Hoong-Kun

2015-02-21

Azodye-rhodamine hybrid colorimetric fluorescent probe (L) has been designed and synthesized. The structure of L has been established based on single crystal XRD. It has been shown to act as a selective turn-on fluorescent chemosensor for Pd(2+) with >40 fold enhancement by exhibiting red emission among the other 27 cations studied in aqueous ethanol. The coordination features of the species of recognition have been computationally evaluated by DFT methods and found to have a distorted tetrahedral Pd(2+) center in the binding core. The probe (L) has been shown to detect Pd up to 0.45 μM at pH 7.4. Furthermore, the probe can be used to image Pd(2+) in living cells.

Colorimetric monitoring of solid-phase aldehydes using 2,4-dinitrophenylhydrazine.

PubMed

Shannon, Simon K; Barany, George

2004-01-01

A simple and rapid method to achieve colorimetric monitoring of resin-bound aldehydes, based on ambient temperature reaction with 2,4-dinitrophenylhydrazine (DNPH) in the presence of dilute acid, has been developed as an adjunct to solid-phase organic synthesis and combinatorial chemistry. By this test, the presence of aldehydes is indicated by a red to dark-orange appearance, within a minute. Alternatively, resins that are free of aldehydes or in which aldehyde functions have reacted completely retain their original color. The DNPH test was demonstrated for poly(ethylene glycol)-polystyrene (PEG-PS), aminomethyl polystyrene (AMP), cross-linked ethoxylate acrylate resin (CLEAR), and acryloylated O,O'-bis(2-aminopropyl)poly(ethylene glycol) (PEGA) supports and gave results visible to the naked eye at levels as low as 18 micromol of aldehyde per gram of resin.

Protein, enzyme and carbohydrate quantification using smartphone through colorimetric digitization technique.

PubMed

Dutta, Sibasish; Saikia, Gunjan Prasad; Sarma, Dhruva Jyoti; Gupta, Kuldeep; Das, Priyanka; Nath, Pabitra

2017-05-01

In this paper the utilization of smartphone as a detection platform for colorimetric quantification of biological macromolecules has been demonstrated. Using V-channel of HSV color space, the quantification of BSA protein, catalase enzyme and carbohydrate (using D-glucose) have been successfully investigated. A custom designed android application has been developed for estimating the total concentration of biological macromolecules. The results have been compared with that of a standard spectrophotometer which is generally used for colorimetric quantification in laboratory settings by measuring its absorbance at a specific wavelength. The results obtained with the designed sensor is found to be similar when compared with the spectrophotometer data. The designed sensor is low cost, robust and we envision that it could promote diverse fields of bio-analytical investigations. Schematic illustration of the smartphone sensing mechanism for colorimetric analysis of biomolecular samples. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Integrating Deoxyribozymes into Colorimetric Sensing Platforms

PubMed Central

Chang, Dingran; Zakaria, Sandy; Deng, Mimi; Allen, Nicholas; Tram, Kha; Li, Yingfu

2016-01-01

Biosensors are analytical devices that have found a variety of applications in medical diagnostics, food quality control, environmental monitoring and biodefense. In recent years, functional nucleic acids, such as aptamers and nucleic acid enzymes, have shown great potential in biosensor development due to their excellent ability in target recognition and catalysis. Deoxyribozymes (or DNAzymes) are single-stranded DNA molecules with catalytic activity and can be isolated to recognize a wide range of analytes through the process of in vitro selection. By using various signal transduction mechanisms, DNAzymes can be engineered into fluorescent, colorimetric, electrochemical and chemiluminescent biosensors. Among them, colorimetric sensors represent an attractive option as the signal can be easily detected by the naked eye. This reduces reliance on complex and expensive equipment. In this review, we will discuss the recent progress in the development of colorimetric biosensors that make use of DNAzymes and the prospect of employing these sensors in a range of chemical and biological applications. PMID:27918487

Transport of diseased red blood cells in the spleen

NASA Astrophysics Data System (ADS)

Peng, Zhangli; Pivkin, Igor; Dao, Ming

2012-11-01

A major function of the spleen is to remove old and diseased red blood cells (RBCs) with abnormal mechanical properties. We investigated this mechanical filtering mechanism by combining experiments and computational modeling, especially for red blood cells in malaria and sickle cell disease (SCD). First, utilizing a transgenic line for 3D confocal live imaging, in vitro capillary assays and 3D finite element modeling, we extracted the mechanical properties of both the RBC membrane and malaria parasites for different asexual malaria stages. Secondly, using a non-invasive laser interferometric technique, we optically measured the dynamic membrane fluctuations of SCD RBCs. By simulating the membrane fluctuation experiment using the dissipative particle dynamics (DPD) model, we retrieved mechanical properties of SCD RBCs with different shapes. Finally, based on the mechanical properties obtained from these experiments, we simulated the full fluid-structure interaction problem of diseased RBCs passing through endothelial slits in the spleen under different fluid pressure gradients using the DPD model. The effects of the mechanical properties of the lipid bilayer, the cytoskeleton and the parasite on the critical pressure of splenic passage of RBCs were investigated separately. This work is supported by NIH and Singapore-MIT Alliance for Science and Technology (SMART).

Experimental research on microhardness and wear resistances of pure Cu subjected to surface dynamic plastic deformation by ultrasonic impact

NASA Astrophysics Data System (ADS)

Chen, Zhaoxia; He, Yangming

2018-04-01

Dynamic plastic deformation (DPD) has been induced in the surface of pure Cu by ultrasonic impact treating (UIT) with the varied impact current and coverage percentage. The microstructures of the treated surface were analyzed by a scanning electron microscope (SEM). And the wear resistance of pure Cu was experimentally researched both with the treated and untreated specimens. The effect of DPD on the hardness was also investigated using microhardness tester. The results show that the grains on the top surfaces of pure Cu are highly refined. The maximum depth of the plastic deformation layer is approximately 1400 µm. The larger the current and coverage percentage, the greater of the microhardness and wear resistance the treated surface layer of pure Cu will be. When the impact current is 2 A and coverage percentage is 300%, the microhardness and wear resistance of the treated sample is about 276.1% and 68.8% higher than that of the untreated specimen, respectively. But the properties of the treated sample deteriorate when the UIT current is 3 A and the coverage percentage is 300% because of the formation of a new phase forms in the treated surface.

Tumor 5-FU-related mRNA Expression and Efficacy of Oral Fluoropyrimidines in Adjuvant Chemotherapy of Colorectal Cancer.

PubMed

Koda, Keiji; Miyauchi, Hideaki; Kosugi, Chihiro; Kaiho, Takashi; Takiguchi, Nobuhiro; Kobayashi, Susumu; Maruyama, Takashi; Matsubara, Hisahiro

2016-10-01

It has not been elucidated whether the clinical efficacy of oral fluoropyrimidines for adjuvant chemotherapy of colorectal cancer varies with tumor biological characteristics. A multicenter randomized trial was performed comparing oral tegafur/gimeracil/oteracil (S-1) and uracil-tegafur/ leucovorin (UFT/LV) as adjuvant therapy for stage III colorectal cancer. Postoperative survival was compared based on the 5-FU-related mRNA levels in cancer tissues. Among patients with tumor expressing dihydropyrimidine dehydrogenase (DPD) mRNA within the 66.7th percentile (lower 2/3) of all cases, overall survival (OS) was significantly better in the S-1 than in the UFT/LV group. In the S-1 group, patients with low DPD-expressing tumors had significantly better OS than those with highly expressing tumors. Patients with low thymidine synthase (TS)-expressing tumors had significantly better OS than those with highly expressing tumors. The efficacy of oral fluoropyrimidines as adjuvant chemotherapy for colorectal cancer may be influenced by the level of 5-FU-related mRNA in cancer tissues. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Therapeutic drug monitoring of antimetabolic cytotoxic drugs

PubMed Central

Lennard, L

1999-01-01

Therapeutic drug monitoring is not routinely used for cytotoxic agents. There are several reasons, but one major drawback is the lack of established therapeutic concentration ranges. Combination chemotherapy makes the establishment of therapeutic ranges for individual drugs difficult, the concentration-effect relationship for a single drug may not be the same as that when the drug is used in a drug combination. Pharmacokinetic optimization protocols for many classes of cytotoxic compounds exist in specialized centres, and some of these protocols are now part of large multicentre trials. Nonetheless, methotrexate is the only agent which is routinely monitored in most treatment centres. An additional factor, especially in antimetabolite therapy, is the existence of pharmacogenetic enzymes which play a major role in drug metabolism. Monitoring of therapy could include assay of phenotypic enzyme activities or genotype in addition to, or instead of, the more traditional measurement of parent drug or drug metabolites. The cytotoxic activities of mercaptopurine and fluorouracil are regulated by thiopurine methyltransferase (TPMT) and dihydropyrimidine dehydrogenase (DPD), respectively. Lack of TPMT functional activity produces life-threatening mercaptopurine myelotoxicity. Very low DPD activity reduces fluorouracil breakdown producing severe cytotoxicity. These pharmacogenetic enzymes can influence the bioavailability, pharmacokinetics, toxicity and efficacy of their substrate drugs. PMID:10190647

A case of squamous cell carcinoma of the head and neck producing granulocyte-colony stimulating factor with marked leukocytosis.

PubMed

Toyoda, Minoru; Chikamatsu, Kazuaki; Sakakura, Koichi; Fukuda, Yoichiro; Takahashi, Katsumasa; Miyashita, Motoaki; Shimamura, Kazuo; Furuya, Nobuhiko

2007-06-01

In squamous cell carcinoma of the head and neck (SCCHN), tumor cells have been shown to secrete detectable amounts of various cytokines, such as interleukin (IL)-6, IL-10, and transforming growth factor (TGF)-beta. These tumor-derived factors might be responsible for promoting malignancy. Here, we describe a SCCHN patient with tumor produced G-CSF and characterized by marked leukocytosis. In this 45-year-old man, severe leukocytosis developed in parallel with aggressive tumor growth. G-CSF production by the tumor was confirmed by immunohistochemistry (IHC). Serum G-CSF levels were elevated. The leukocyte counts and the blood G-CSF level decreased following a course of radiotherapy. Tumor cells were also positive for G-CSF receptor, suggesting autocrine growth regulation by G-CSF. Moreover, the tumor cells were also investigated by IHC with anti-p53, anti-P-glycoprotein (P-gp), anti-thymidylate synthase (TS), and anti-dihydropyrimidine dehydrogenase (DPD), which molecules are thought to contribute the acquisition of therapeutic resistance. The tumor cells were positively stained for TS and DPD, but neither p53 nor P-gp. These results suggest that a variety of molecules may be responsible for acquisition of high malignancy.

The Preemptive Stocker Dispatching Rule of Automatic Material Handling System in 300 mm Semiconductor Manufacturing Factories

NASA Astrophysics Data System (ADS)

Wang, C. N.; Lin, H. S.; Hsu, H. P.; Wang, Yen-Hui; Chang, Y. P.

2016-04-01

The integrated circuit (IC) manufacturing industry is one of the biggest output industries in this century. The 300mm wafer fabs is the major fab size of this industry. The automatic material handling system (AMHS) has become one of the most concerned issues among semiconductor manufacturers. The major lot delivery of 300mm fabs is used overhead hoist transport (OHT). The traffic jams are happened frequently due to the wide variety of products and big amount of OHTs moving in the fabs. The purpose of this study is to enhance the delivery performance of automatic material handling and reduce the delay and waiting time of product transportation for both hot lots and normal lots. Therefore, this study proposes an effective OHT dispatching rule: preemptive stocker dispatching (PSD). Simulation experiments are conducted and one of the best differentiated preemptive rule, differentiated preemptive dispatching (DPD), is used for comparison. Compared with DPD, The results indicated that PSD rule can reduce average variable delivery time of normal lots by 13.15%, decreasing average variable delivery time of hot lots by 17.67%. Thus, the PSD rule can effectively reduce the delivery time and enhance productivity in 300 mm wafer fabs.

The microculture tetrazolium assay (MTA): another colorimetric method of testing Plasmodium falciparum chemosensitivity.

PubMed

Delhaes, L; Lazaro, J E; Gay, F; Thellier, M; Danis, M

1999-01-01

Malarial lactate dehydrogenase (LDH), which uses 3-acetyl pyridine adenine dinucleotide as coenzyme in a reaction leading to the formation of pyruvate from L-lactate, may be used to study the susceptibility of Plasmodium falciparum to a drug in vitro. Several methods to determine the activity of this enzyme are available. One, the colorimetric method of Makler and colleagues, was modified slightly, by using sodium-2,3-bis-[2-methoxy-4-nitro-5-sulphophenyl]-2H-tetrazolium-5 - carboxanilide (XTT) and following the reaction by measuring the optical density at 450 nm. Using two, culture-adapted strains of P. falciparum, this LDH assay was compared with the unmodified Makler's assay and with the isotopic microtest based on the incorporation of tritium-labelled hypoxanthine. Fresh, clinical P. falciparum isolates were also tested in the presence of several drugs, including chloroquine, mefloquine, quinine, halofantrine, atovaquone and qinghaosu derivatives. The results of the three assays were correlated for all the drugs tested except atovaquone. The two enzymatic assays are non-radioactive, rapid, reliable, inexpensive to perform and semi-automatic. However, they do require an initial parasitaemia of 2% with a haematocrit of 1.8%.

Determination of glucose and uric acid with bienzyme colorimetry on microfluidic paper-based analysis devices.

PubMed

Chen, Xi; Chen, Jin; Wang, Fubin; Xiang, Xia; Luo, Ming; Ji, Xinghu; He, Zhike

2012-05-15

In this work, we first employ a drying method combining with the bienzyme colorimetric detection of glucose and uric acid on microfluidic paper-based analysis devices (μPADs). The channels of 3D μPADs are also designed by us to get better results. The color results are recorded by both Gel Documentation systems and a common camera. By using Gel Documentation systems, the limits of detection (LOD) of glucose and uric acid are 3.81 × 10(-5)M and 4.31 × 10(-5)M, respectively one order of magnitude lower than that of the reported methods on μPADs. By using a common camera, the limits of detection (LOD) of glucose and uric acid are 2.13 × 10(-4)M and 2.87 × 10(-4)M, respectively. Furthermore, the effects of detection conditions have been investigated and discussed comprehensively. Human serum samples are detected with satisfactory results, which are comparable with the clinical testing results. A low-cost, simple and rapid colorimetric method for the simultaneous detection of glucose and uric acid on the μPADs has been developed with enhanced sensitivity. Copyright © 2012 Elsevier B.V. All rights reserved.

A novel application of carbon dots for colorimetric determination of fenitrothion insecticide based on the microextraction method

NASA Astrophysics Data System (ADS)

Larki, A.

2017-02-01

In this work, the intrinsic colorimetric property of carbon dots (CDs) was utilized for the determination of fenitrothion by applying dispersive liquid-liquid microextraction (DLLME) method. Label free CDs are extracted into carbon tetrachloride via assistance of trioctylmethylammonium chloride (Aliquat 336), which also acts as a disperser agent in this technique. The enriched CDs show an absorption signal at 365 nm, which increases in the presence of fenitrothion. The absorbance increase of CDs in organic phase was used as an analytical signal for the determination of fenitrothion. The synthesized CDs were characterized by UV-visible, fluorescence, Fourier transform infrared (FT-IR) and transmission electron microscopic (TEM). Under the optimized conditions, beer's law was obeyed in the range of 1.0-250.0 ng mL- 1 of fenitrothion with the limit of detection for fenitrothion was 0.2 ng mL- 1. The relative standard deviation for eight replicate measurements of fenitrothion at concentrations of 25 and 100 ng mL- 1 were calculated to be 1.5 and 3.7%, respectively. The proposed method was successfully applied in the determination of fenitrothion in water samples with satisfactory results.

Selective Distance-Based K+ Quantification on Paper-Based Microfluidics.

PubMed

Gerold, Chase T; Bakker, Eric; Henry, Charles S

2018-04-03

In this study, paper-based microfluidic devices (μPADs) capable of K + quantification in aqueous samples, as well as in human serum, using both colorimetric and distance-based methods are described. A lipophilic phase containing potassium ionophore I (valinomycin) was utilized to achieve highly selective quantification of K + in the presence of Na + , Li + , and Mg 2+ ions. Successful addition of a suspended lipophilic phase to a wax printed paper-based device is described and offers a solution to current approaches that rely on organic solvents, which damage wax barriers. The approach provides an avenue for future alkali/alkaline quantification utilizing μPADs. Colorimetric spot tests allowed for K + quantification from 0.1-5.0 mM using only 3.00 μL of sample solution. Selective distance-based quantification required small sample volumes (6.00 μL) and gave responses sensitive enough to distinguish between 1.0 and 2.5 mM of sample K + . μPADs using distance-based methods were also capable of differentiating between 4.3 and 6.9 mM K + in human serum samples. Distance-based methods required no digital analysis, electronic hardware, or pumps; any steps required for quantification could be carried out using the naked eye.

Colorimetric sensing of oxalate based on its inhibitory effect on the reaction of Fe (III) with curcumin nanoparticles

NASA Astrophysics Data System (ADS)

Pourreza, Nahid; Lotfizadeh, Neda; Golmohammadi, Hamed

2018-03-01

In this research, a new colorimetric method for the determination of oxalate using curcumin nanoparticles (CURNs) in the presence Fe (III) is introduced. The method is based on the inhibitory effect of oxalate ion on the reaction of (CURNs) with Fe (III) in acidic media. This reaction was monitored by measuring the increase in absorbance of CURNs-Fe3 + complex in the presence of oxalate ion at 427 nm. The effect of different parameters such as the pH of the sample solution, concentration of Fe (III), concentration of CURNs and the reaction time was examined and optimized. Under optimum experimental conditions, the absorption intensity was linear with the concentration of oxalate in the range of 0.15 to 1.70 μg mL- 1. The limit of detection (LOD) was 0.077 μg mL- 1 and the relative standard deviations (RSD) for 8 replicate measurements of 0.40 and 1.05 μg mL- 1 of oxalate were 4.20% and 2.74%, respectively. The developed method was successfully employed to the determination of oxalate in water, food and urine samples with satisfactory results.

One-step, room temperature, colorimetric melamine sensing using an in-situ formation of silver nanoparticles through modified Tollens process

NASA Astrophysics Data System (ADS)

Wang, Huiying; Chen, Dinglong; Yu, Longquan; Chang, Ming; Ci, Lijie

2015-02-01

We have developed a rapid, sensitive, one-step, and selective colorimetric detection method for melamine (MEL) in milk powder based upon an in-situ formation of silver nanoparticles (AgNPs) through modified Tollens process at room temperature. The triazine ring N atoms of MEL molecule were strategically designed to complex the Ag+ through electron donor-acceptor interaction. During the AgNPs formation procedure, the MEL molecule, which has been covalently bonded with the Ag+ ions, was adsorbed to the surface of as-prepared AgNPs, resulting in the aggregation of the adjacent AgNPs with detectable decreases of absorption signal. The concentration of MEL can be determined with the naked eye or a UV-vis spectrometer at which the yellow-to-brown color change associated with aggregate enhancement takes place. This method enables rapid (less than 30 min) and sensitive (limit of detection, LOD, 10 nM) detection, and it was also able to discriminate MEL from sixteen other milk relevant coexisting compounds. This assay does not utilize organic cosolvents, enzymatic reactions, light-sensitive dye molecules, lengthy protocols, or sophisticated instrumentation thereby overcoming some of the limitations of conventional methods.

Colorimetric method for the detection of melamine using in-situ formed silver nanoparticles via tannic acid

NASA Astrophysics Data System (ADS)

Alam, Md. Fazle; Laskar, Amaj Ahmed; Ahmed, Shahbaz; Shaida, Mohd. Azfar; Younus, Hina

2017-08-01

Melamine toxicity has recently attracted worldwide attention as it causes renal failure and the death of humans and animals. Therefore, developing a simple, fast and sensitive method for the routine detection of melamine is the need of the hour. Herein, we have developed a selective colorimetric method for the detection of melamine in milk samples based upon in-situ formation of silver nanoparticles (AgNPs) via tannic acid. The AgNPs thus formed were characterized by UV-Visible spectrophotometer, transmission electron microscope (TEM), zetasizer and dynamic light scattering (DLS). The AgNPs were used to detect melamine under in vitro condition and in raw milk spiked with melamine. Under optimal conditions, melamine could be selectively detected in vitro within the concentration range of 0.05-1.4 μM with a limit of detection (LOD) of 0.01 μM, which is lower than the strictest melamine safety requirement of 1 ppm. In spiked raw milk, the recovery percentage range was 99.5-106.5% for liquid milk and 98.5-105.5% for powdered milk. The present method shows extreme selectivity with no significant interference with other substances like urea, glucose, glycine, ascorbic acid etc. This assay method does not utilize organic cosolvents, enzymatic reactions, light sensitive dye molecules and sophisticated instrumentation, thereby overcoming some of the limitations of the other conventional methods.

Characterization analysis for leaves of Leucaena leucocephala by using phytochemical screening assay

NASA Astrophysics Data System (ADS)

Zarina, Z.; Ghazali, C. M. R.; Sam, S. T.

2017-09-01

Leucaena Leucocephala (Lam.) de Wit (Petai Belalang) is a medium plant which belong in group of tropical breed that can survived in hot, dried and warm environment. In Malaysia, the plant is available abundantly. As there are still no commercial used, and no serious intention in finding the benefits of L. Leucocephala, this work come out with the idea to analyze the antioxidants contains in leaves of the plant by undergoes different extraction and chemical testing method. The phytochemical screening assay involved in this study are antioxidant activity by using free radical diphenylpicrylhydrazyl (DPPH) method, total phenolic content by using Folin-Ciocalteu method, total flavonoid content by using colorimetric assay with ascorbic acid and quercetin were used as reference standards while for phosphorus analysis, a molybdenum blue method or also known as ascorbic acid method was used. For antioxidant activity by using free radical diphenylpicrylhydrazyl (DPPH) method, higher concentration was recorded by extraction using methanol (dried sample) which is 8247.0 mg/L, for total phenolic content higher concentration was recorded by extraction using deionized water (dried sample) which is 4276.0 mg/L, for total flavonoid content by using colorimetric assay higher concentration was recorded by extraction using methanol (dried sample) which is 4439.0 mg/L, and for for phosphorus analysis higher concentration was recorded by extraction using methanol (dried sample) which is 71.057 mg/L.

Characterization analysis for leaves of Leucaena Leucocephala by using phytochemical screening assay

NASA Astrophysics Data System (ADS)

Zarina, Z.; Ghazali, C. M. R.; Sam, S. T.

2017-09-01

Leucaena Leucocephala (Lam.) de Wit (Petai Belalang) is a medium plant which belong in group of tropical breed that can survived in hot, dried and warm environment. In Malaysia, the plant is available abundantly. As there are still no commercial used, and no serious intention in finding the benefits of L. Leucocephala, this work come out with the idea to analyze the antioxidants contains in leaves of the plant by undergoes different extraction and chemical testing method. The phytochemical screening assay involved in this study are antioxidant activity by using free radical diphenylpicrylhydrazyl (DPPH) method, total phenolic content by using Folin-Ciocalteu method, total flavonoid content by using colorimetric assay with ascorbic acid and quercetin were used as reference standards while for phosphorus analysis, a molybdenum blue method or also known as ascorbic acid method was used. For antioxidant activity by using free radical diphenylpicrylhydrazyl (DPPH) method, higher concentration was recorded by extraction using methanol (dried sample) which is 8247.0 mg/L, for total phenolic content higher concentration was recorded by extraction using deionized water (dried sample) which is 4276.0 mg/L, for total flavonoid content by using colorimetric assay higher concentration was recorded by extraction using methanol (dried sample) which is 4439.0 mg/L, and for for phosphorus analysis higher concentration was recorded by extraction using methanol (dried sample) which is 71.057 mg/L.

A new cation-exchange method for accurate field speciation of hexavalent chromium

USGS Publications Warehouse

Ball, J.W.; McCleskey, R. Blaine

2003-01-01

A new method for field speciation of Cr(VI) has been developed to meet present stringent regulatory standards and to overcome the limitations of existing methods. The method consists of passing a water sample through strong acid cation-exchange resin at the field site, where Cr(III) is retained while Cr(VI) passes into the effluent and is preserved for later determination. The method is simple, rapid, portable, and accurate, and makes use of readily available, inexpensive materials. Cr(VI) concentrations are determined later in the laboratory using any elemental analysis instrument sufficiently sensitive to measure the Cr(VI) concentrations of interest. The new method allows measurement of Cr(VI) concentrations as low as 0.05 ??g 1-1, storage of samples for at least several weeks prior to analysis, and use of readily available analytical instrumentation. Cr(VI) can be separated from Cr(III) between pH 2 and 11 at Cr(III)/Cr(VI) concentration ratios as high as 1000. The new method has demonstrated excellent comparability with two commonly used methods, the Hach Company direct colorimetric method and USEPA method 218.6. The new method is superior to the Hach direct colorimetric method owing to its relative sensitivity and simplicity. The new method is superior to USEPA method 218.6 in the presence of Fe(II) concentrations up to 1 mg 1-1 and Fe(III) concentrations up to 10 mg 1-1. Time stability of preserved samples is a significant advantage over the 24-h time constraint specified for USEPA method 218.6.

A new diatom growth inhibition assay using the XTT colorimetric method.

PubMed

Jiang, Weina; Akagi, Takuya; Suzuki, Hidekazu; Takimoto, Ayaka; Nagai, Hiroshi

2016-01-01

Marine biofouling, which leads to significant operational stress and economic damage on marine infrastructures, is a major problem in marine related industries. Currently, the most common way to avoid marine biofouling involves the use of biocidal products in surface coatings. However, the need for environmentally friendly antibiofouling compounds has increased rapidly with the recent global prohibition of harmful antifoulants, such as tributyltin (TBT). In particular, periphytic diatoms have been shown to contribute significantly to biofilms, which play an important role in biofouling. Therefore, inhibiting the proliferation of fouling diatoms is a very important step in the prevention of marine biofouling. In this study, we developed a new, rapid, accurate, and convenient growth inhibition assay using the XTT colorimetric method to prevent the growth of the fouling periphytic diatom, Nitzschia amabilis Hidek. Suzuki (replaced synonym, Nitzschia laevis Hustedt). The feasibility of this method was verified by determining the growth inhibition activities of two standard photosynthetic inhibitors, DCMU and CuSO4. However, neither inhibitor had any cytotoxic activities at the range of concentrations tested. Moreover, this method was applied by screening and purification of herbicidic but non-cytotoxic compounds from cyanobacteria extracts. Our results demonstrate the utility of this newly established growth inhibition assay for the identification of marine anti-biofouling compounds. Copyright © 2016 Elsevier Inc. All rights reserved.

Development of a loop-mediated isothermal amplification method for rapid mass-screening of sand flies for Leishmania infection.

PubMed

Nzelu, Chukwunonso O; Gomez, Eduardo A; Cáceres, Abraham G; Sakurai, Tatsuya; Martini-Robles, Luiggi; Uezato, Hiroshi; Mimori, Tatsuyuki; Katakura, Ken; Hashiguchi, Yoshihisa; Kato, Hirotomo

2014-04-01

Entomological monitoring of Leishmania infection in leishmaniasis endemic areas offers epidemiologic advantages for predicting the risk and expansion of the disease, as well as evaluation of the effectiveness of control programs. In this study, we developed a highly sensitive loop-mediated isothermal amplification (LAMP) method for the mass screening of sand flies for Leishmania infection based on the 18S rRNA gene. The LAMP technique could detect 0.01 parasites, which was more sensitive than classical PCR. The method was robust and could amplify the target DNA within 1h from a crude sand fly template without DNA purification. Amplicon detection could be accomplished by the newly developed colorimetric malachite green (MG)--mediated naked eye visualization. Pre-addition of MG to the LAMP reaction solution did not inhibit amplification efficiency. The field applicability of the colorimetric MG-based LAMP assay was demonstrated with 397 field-caught samples from the endemic areas of Ecuador and eight positive sand flies were detected. The robustness, superior sensitivity, and ability to produce better visual discriminatory reaction products than existing LAMP fluorescence and turbidity assays indicated the field potential usefulness of this new method for surveillance and epidemiological studies of leishmaniasis in developing countries. Copyright © 2013 Elsevier B.V. All rights reserved.

Operator-Friendly Technique and Quality Control Considerations for Indigo Colorimetric Measurement of Ozone Residual

EPA Science Inventory

Drinking water ozone disinfection systems measure ozone residual concentration, C, for regulatory compliance reporting of concentration-times-time (CT), and the resultant log-inactivation of virus, Giardia and Cryptosporidium. The indigotrisulfonate (ITS) colorimetric procedure i...

Modeling colorimetric characteristics of ON-OFF behavior of photochromic dyes based on bis-azospiropyrans

NASA Astrophysics Data System (ADS)

Kandi, Saeideh Gorji; Nourmohammadian, Farahnaz

2013-10-01

In the present study, colorimetric characteristics of six photochromic bis-azospiropyrans based dyes are investigated. The colorimetric axes of these dyes in terms of hue, chroma and lightness are considered via UV exposure time. Results showed that, the hue angle of these dyes changes rapidly at the first times of UV irradiation, and then remains almost constant. However, chroma and lightness continuously change till about 80-240 s for different dyes. In addition, it is shown that variations of lightness and chroma by UV exposure time have an exponential trend, which can be modeled mathematically.

Determination of dietary starch in animal feeds and pet food by an enzymatic-colorimetric method: collaborative study

USDA-ARS?s Scientific Manuscript database

Starch, glycogen, maltooligosaccharides, and other alpha-1,4- and alpha-1,6-linked glucose carbohydrates exclusive of resistant starch are collectively termed "dietary starch." This nutritionally important fraction is increasingly measured for use in diet formulation for animals, as it can have posi...

Factors Affecting Accuracy and Time Requirements of a Glucose Oxidase-Peroxidase Assay for Determination of Glucose

USDA-ARS?s Scientific Manuscript database

Accurate and rapid assays for glucose are desirable for analysis of glucose and starch in food and feedstuffs. An established colorimetric glucose oxidase-peroxidase method for glucose was modified to reduce analysis time, and evaluated for factors that affected accuracy. Time required to perform t...

Loop-mediated isothermal amplification for detection of the tomato and potato late blight pathogen, Phytophthora infestans

USDA-ARS?s Scientific Manuscript database

Aims: To design and validate a colorimetric loop-mediated isothermal amplification assay for rapid detection of P. infestans DNA. Methods and Results: Two sets of LAMP primers were designed and evaluated for their sensitivity and specificity for P. infestans. ITSII primers targeted a portion of the ...

Colorimetric Detection of Water Vapor Using Metal-Organic Framework Composites.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allendorf, Mark D.

Purpose: Water vapor trapped in encapsulation materials or enclosed volumes leads to corrosion issues for critical NW components. Sandia National Laboratories has created a new diagnostic to indicate the presence of water in weapon systems. Impact: Component exposure to water now can be determined instantly, without need for costly, time-consuming analytical methods.

Measuring phosphatidic acid phosphatase (EC 3.1.3.4) activity using two phosphomolybdate-based colorimetric methods

USDA-ARS?s Scientific Manuscript database

Phosphatidate phosphatase (3-sn-phosphatidate phosphohydrolase, EC 3.1.3.4), which is also known as PAP, catalyzes the dephosphorylation of phosphatidate (PtdOH) to form diacylglycerol (DAG) and inorganic phosphate. In eukaryotes, PAP driven reaction is the committed step in the synthesis of triacyl...

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR ANALYSIS OF PASSIVE FORMALDEHYDE SAMPLERS (BCO-L-16.0)

EPA Science Inventory

The purpose of this SOP is to describe the methodology used by Air Quality Research (Research Triangle Park, NC) for the analysis of the PF-1 passive formaldehyde samplers using a colorimetric method and chromotropic acid. This procedure was followed to ensure consistent data re...

Quercetin as colorimetric reagent for determination of zirconium

USGS Publications Warehouse

Grimaldi, F.S.; White, C.E.

1953-01-01

Methods described in the literature for the determination of zirconium are generally designed for relatively large amounts of this element. A good procedure using colorimetric reagent for the determination of trace amounts is desirable. Quercetin has been found to yield a sensitive color reaction with zirconium suitable for the determination of from 0.1 to 50?? of zirconium dioxide. The procedure developed involves the separation of zirconium from interfering elements by precipitation with p-dimethylaminoazophenylarsonic acid prior to its estimation with quercetin. The quercetin reaction is carried out in 0.5N hydrochloric acid solution. Under the operating conditions it is indicated that quercetin forms a 2 to 1 complex with zirconium; however, a 2 to 1 and a 1 to 1 complex can coexist under special conditions. Approximate values for the equilibrium constants of the complexes are K1 = 0.33 ?? 10-5 and K2 = 1.3 ?? 10-9. Seven Bureau of Standards samples of glass sands and refractories were analyzed with excellent results. The method described should find considerable application in the analysis of minerals and other materials for macro as well as micro amounts of zirconium.

Giant Gold Nanowire Vesicle-Based Colorimetric and SERS Dual-Mode Immunosensor for Ultrasensitive Detection of Vibrio parahemolyticus.

PubMed

Guo, Zhiyong; Jia, Yaru; Song, Xinxin; Lu, Jing; Lu, Xuefei; Liu, Baoqing; Han, Jiaojiao; Huang, Youju; Zhang, Jiawei; Chen, Tao

2018-05-15

Conventional methods for the detection of Vibrio parahemolyticus (VP) usually need tedious, labor-intensive processes, and have low sensitivity, which further limits their practical applications. Herein, we developed a simple and efficient colorimetry and surface-enhanced Raman scattering (SERS) dual-mode immunosensor for sensitive detection of VP, by employing giant Au vesicles with anchored tiny gold nanowires (AuNW) as a smart probe. Due to the larger specific surface and special hollow structure of giant Au vesicles, silver staining would easily lead to vivid color change for colorimetric analysis and further amplify SERS signals. The t-test was further used to determine if two sets of data from colorimetry and SERS were significantly different from each other. The result shows that there was no significant difference between data from the two methods. Two sets of data can mutually validate each other and avoid false positive and negative detection. The designed colorimetry-SERS dual-mode sensor would be very promising in various applications such as food safety inspection, personal healthcare, and on-site environmental monitoring.

Colorimetric-Solid Phase Extraction Technology for Water Quality Monitoring: Evaluation of C-SPE and Debubbling Methods in Microgravity

NASA Technical Reports Server (NTRS)

Hazen-Bosveld, April; Lipert, Robert J.; Nordling, John; Shih, Chien-Ju; Siperko, Lorraine; Porter, Marc D.; Gazda, Daniel B.; Rutz, Jeff A.; Straub, John E.; Schultz, John R.;

An instrument-free, screen-printed paper microfluidic device that enables bio and chemical sensing.

PubMed

Mohammadi, Saeed; Maeki, Masatoshi; Mohamadi, Reza M; Ishida, Akihiko; Tani, Hirofumi; Tokeshi, Manabu

2015-10-07

This paper describes a simple and instrument-free screen-printing method to fabricate hydrophilic channels by patterning polydimethylsiloxane (PDMS) onto chromatography paper. Clearly recognizable border lines were formed between hydrophilic and hydrophobic areas. The minimum width of the printed channel to deliver an aqueous sample was 600 μm, as obtained by this method. Fabricated microfluidic paper-based analytical devices (μPADs) were tested for several colorimetric assays of pH, glucose, and protein in both buffer and artificial urine samples and results were obtained in less than 30 min. The limits of detection (LODs) for glucose and bovine serum albumin (BSA) were 5 mM and 8 μM, respectively. Furthermore, the pH values of different solutions were visually recognised with the naked eye by using a sensitive ink. Ultimately, it is expected that this PDMS-screen-printing (PSP) methodology for μPADs can be readily translated to other colorimetric detection and hydrophilic channels surrounded by a hydrophobic polymer can be formed to transport fluids toward target zones.

Colorimetric Assay for Determination of Lead (II) Based on Its Incorporation into Gold Nanoparticles during Their Synthesis

PubMed Central

Ding, Nan; Cao, Qian; Zhao, Hong; Yang, Yimin; Zeng, Lixi; He, Yujian; Xiang, Kaixiang; Wang, Guangwei

2010-01-01

In this report, we present a new method for visual detection of Pb2+. Gold nanoparticles (Au-NPs) were synthesized in one step at room temperature, using gallic acid (GA) as reducer and stabilizer. Pb2+ is added during the gold nanoparticle formation. Analysis of Pb2+ is conducted by a dual strategy, namely, colorimetry and spectrometry. During Au-NPs synthesis, addition of Pb2+ would lead to formation of Pb-GA complex, which can induce the aggregation of newly-formed small unstable gold nanoclusters. Consequently, colorimetric detection of trace Pb2+ can be realized. As the Pb2+ concentration increases, the color turns from red-wine to purple, and finally blue. This method offers a sensitive linear correlation between the shift of the absorption band (Δλ) and logarithm of Pb2+ concentration ranging from 5.0 × 10−8 to 1.0 × 10−6 M with a linear fit coefficient of 0.998, and a high selectivity for Pb2+ detection with a low detection limit down to 2.5 × 10−8 M. PMID:22163517

The Biological Effect of the NanoTiO2and Its Toxicity.

PubMed

Xiao-Feng, Pang; Lewei, Liu; Zhi Hong, Liu; Qiang, Zhao

2005-01-01

The proliferation behavior of the person's liver cell under actions of the nanoTiO2has been looked into by 3-(4,5-dimethylthiazol 2-yl)-2,5 diphenyltetrazolium bromide (MTT) colorimetric method of Mosmann. In this case we first give some elementary properties of the nanoTiO2and do further the liver cell cultures, and add the nano TiO2into the cells. In accordance with biological rules we measure the proliferation state of the liver cell in normal condition. The result obtained show that the influence of the nanoTiO2on the proliferation of the person's liver cell is very small, when compared with that of the control group. We found further out the size of the toxicity of the nanoTiO2to the chick embryo fibroblast (CEF) cells by the MTT colorimetric method. Thus we determine the toxicity for the TiO2s of 100nm and of 1000nm by the toxicology which are all first score (or degree).

Gold Nanoparticle-Based Facile Detection of Human Serum Albumin and Its Application as an INHIBIT Logic Gate.

PubMed

Huang, Zhenzhen; Wang, Haonan; Yang, Wensheng

2015-05-06

In this work, a facile colorimetric method is developed for quantitative detection of human serum albumin (HSA) based on the antiaggregation effect of gold nanoparticles (Au NPs) in the presence of HSA. The citrate-capped Au NPs undergo a color change from red to blue when melamine is added as a cross-linker to induce the aggregation of the NPs. Such an aggregation is efficiently suppressed upon the adsorption of HSA on the particle surface. This method provides the advantages of simplicity and cost-efficiency for quantitative detection of HSA with a detection limit of ∼1.4 nM by monitoring the colorimetric changes of the Au NPs with UV-vis spectroscopy. In addition, this approach shows good selectivity for HSA over various amino acids, peptides, and proteins and is qualified for detection of HSA in a biological sample. Such an antiaggregation effect can be further extended to fabricate an INHIBIT logic gate by using HSA and melamine as inputs and the color changes of Au NPs as outputs, which may have application potentials in point-of-care medical diagnosis.

Colorimetric measurement of carbohydrates in biological wastewater treatment systems: A critical evaluation.

PubMed

Le, Chencheng; Stuckey, David C

2016-05-01

Four laboratory preparations and three commercially available assay kits were tested on the same carbohydrate samples with the addition of 14 different interfering solutes typically found in wastewater treatment plants. This work shows that a wide variety of solutes can interfere with these assays. In addition, a comparative study on the use of these assays with different carbohydrate samples was also carried out, and the metachromatic response was clearly influenced by variation in sample composition. The carbohydrate content in the supernatant of a submerged anaerobic membrane bioreactor (SAMBR) was also measured using these assays, and the amount in the different supernatant samples, with and without a standard addition of glucose to the samples, showed substantial differences. We concluded that the carbohydrates present in wastewater measured using these colorimetric methods could be seriously under- or over-estimated. A new analytical method needs to be developed in order to better understand the biological transformations occurring in anaerobic digestion that leads to the production of soluble microbial products (SMPs) and extracellular polymeric substance (EPS). Copyright © 2016 Elsevier Ltd. All rights reserved.

Colorimetric detection of cholesterol based on enzyme modified gold nanoparticles

NASA Astrophysics Data System (ADS)

Nirala, Narsingh R.; Saxena, Preeti S.; Srivastava, Anchal

2018-02-01

We develop a simple colorimetric method for determination of free cholesterol in aqueous solution based on functionalized gold nanoparticles with cholesterol oxidase. Functionalized gold nanoparticles interact with free cholesterol to produce H2O2 in proportion to the level of cholesterol visually is being detected. The quenching in optical properties and agglomeration of functionalized gold nanoparticles play a key role in cholesterol sensing due to the electron accepting property of H2O2. While the lower ranges of cholesterol (lower detection limit i.e. 0.2 mg/dL) can be effectively detected using fluorescence study, the absorption study attests evident visual color change which becomes effective for detection of higher ranges of cholesterol (lower detection limit i.e. 19 mg/dL). The shades of red gradually change to blue/purple as the level of cholesterol detected (as evident at 100 mg/dL) using unaided eye without the use of expensive instruments. The potential of the proposed method to be applied in the field is shown by the proposed cholesterol measuring color wheel.

Intrinsic peroxidase-like activity of rhodium nanoparticles, and their application to the colorimetric determination of hydrogen peroxide and glucose.

PubMed

Choleva, Tatiana G; Gatselou, Vasiliki A; Tsogas, George Z; Giokas, Dimosthenis L

2017-12-05

The intrinsic peroxidase-like activity of rhodium nanoparticles (RhNPs) and their use as catalytic labels for sensitive colorimetric assays is presented. RhNPs catalyze the oxidation of the peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) in the presence of H 2 O 2 to produce a blue reaction product with a maximum absorbance at 652 nm. Kinetic studies show catalysis to follow Michaelis-Menten kinetics and a "ping-pong" mechanism. The calculated kinetic parameters indicate high affinity of RhNPs for both the substrate TMB and H 2 O 2 . In fact, they are better than other peroxidase mimicking nanomaterials and even the natural enzyme horseradish peroxidase. On the other hand, RhNPs exhibit no reactivity towards saccharides, thiols, amino acids and ascorbic acid. Based on these findings, a sensitive and selective colorimetric method was worked out for the determination of H 2 O 2 in real samples with a linear response in the 1-100 μM concentration range. By employing glucose oxidase, the glucose assay has a linear range that covers the 5 to 125 μM glucose concentration range. The detection limits are <0.75 μM for both species. The methods were applied to the determination of H 2 O 2 in spiked pharmaceutical formulations, and of glucose in soft drinks and blood plasma. Figures of merit include (a) good accuracy (with errors of <6%), (b) high recoveries (96.5-103.7%), and (c) satisfactory reproducibility (<6.3%). Graphical abstract Rhodium nanoparticles catalyze the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) in the presence of H 2 O 2 to produce a blue reaction product. The effect is exploited in photometric assays for hydrogen peroxide and glucose.

Sensitive colorimetric assay for uric acid and glucose detection based on multilayer-modified paper with smartphone as signal readout.

PubMed

Wang, Xu; Li, Fang; Cai, Ziqi; Liu, Kaifan; Li, Jing; Zhang, Boyang; He, Jianbo

2018-04-01

In this work, a multilayer-modified paper-based colorimetric sensing platform with improved color uniformity and intensity was developed for the sensitive and selective determination of uric acid and glucose with smartphone as signal readout. In detail, chitosan, different kinds of chromogenic reagents, and horseradish peroxidase (HRP) combined with a specific oxidase, e.g., uricase or glucose oxidase (GOD), were immoblized onto the paper substrate to form a multilayer-modified test paper. Hydrogen peroxide produced by the oxidases (uricase or GOD) reacts with the substrates (uric acid or glucose), and could oxidize the co-immoblized chromogenic reagents to form colored products with HRP as catalyst. A simple strategy by placing the test paper on top of a light-emitting diode lamp was adopted to efficiently prevent influence from the external light. The color images were recorded by the smartphone camera, and then the gray values of the color images were calculated for quantitative analysis. The developed method provided a wide linear response from 0.01 to 1.0 mM for uric acid detection and from 0.02 to 4.0 mM for glucose detection, with a limit of detection (LOD) as low as 0.003 and 0.014 mM, respectively, which was much lower than for previously reported paper-based colorimetric assays. The proposed assays were successfully applied to uric acid and glucose detection in real serum samples. Furthermore, the enhanced analytical performance of the proposed method allowed the non-invasive detection of glucose levels in tear samples, which holds great potential for point-of-care analysis. Graphical abstract ᅟ.

Colorimetric determination of glutathione in human serum and cell lines by exploiting the peroxidase-like activity of CuS-polydopamine-Au composite.

PubMed

Wang, Yanying; Liu, Yaqin; Ding, Fang; Zhu, Xiaoyan; Yang, Li; Zou, Ping; Rao, Hanbing; Zhao, Qingbiao; Wang, Xianxiang

2018-06-07

In this study, we developed a simple colorimetric approach to detect glutathione (GSH). The proposed approach is based on the ability of CuS-PDA-Au composite material to catalytically oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to ox-TMB to induce a blue color with an absorption peak centered at 652 nm. However, the introduction of GSH can result in a decrease in oxidized TMB; similarly, it can combine with Au nanoparticles (Au NPs) on the surface of CuS-PDA-Au composite material. Both approaches can result in a fading blue color and a reduction of the absorbance at 652 nm. Based on this above, we proposed a technique to detect GSH quantitatively and qualitatively through UV-Vis spectroscopy and naked eye, respectively. This approach demonstrates a low detection limit of 0.42 μM with a broad detection range of 5 × 10 -7 -1 × 10 -4  M with the assistance of UV-Vis spectroscopy. More importantly, this approach is convenient and rapid. This method was successfully applied to GSH detection in human serum and cell lines. Graphical abstract A colorimetric approach has been developed by exploiting the peroxidase-like activity of CuS-polydopamine-Au composite for sensitive glutathione detection.

A novel cerium oxide nanoparticles-based colorimetric sensor using tetramethyl benzidine reagent for antioxidant activity assay.

PubMed

Ozdemir Olgun, F Ayca; Üzer, Ayşem; Ozturk, Birsen Demirata; Apak, Reşat

2018-05-15

Antioxidant activity (AOA) assays using nanotechnology are recently developed utilizing nanoparticles of transition metal oxides, especially nanoceria that can switch between trivalent and tetravalent oxidation states of cerium. Cerium oxide nanoparticles (CeO-NPs) may act as both an oxidant and an antioxidant, depending on the preparation method and particle size. A novel colorimetric sensor for AOA assay is proposed with the use of poly(acrylic acid) sodium salt (PAANa)-coated CeO-NPs. PAANa-coated CeO-NPs oxidized tetramethyl benzidine (TMB), a peroxidase substrate, in a slightly acidic solution at pH 4.0 to a blue charge-transfer complex. Antioxidants decreased the color intensity of the nanoceria suspension, and were indirectly determined by absorbance difference. Detection limits, linearity, additivity and precision were calculated, e.g., quercetin quantification with the proposed assay showed a detection limit of 8.25 × 10 -9 mol L -1 . The trolox equivalent antioxidant capacities of hydrophilic and lipophilic antioxidants were compatible with those of conventional antioxidant assays. Potential interferents such as glucose, citric acid, mannitol, sorbitol and benzoic acid did not adversely affect AOA determination. The developed sensor is more sensitive and selective than similar colorimetric sensors relying on the intrinsic color change of nanoceria. The measurement wavelength is sufficiently red-shifted, preventing possible interferences from plant pigments. Copyright © 2018 Elsevier B.V. All rights reserved.

Portable device for the detection of colorimetric assays

PubMed Central

Nowak, E.; Kawchuk, J.; Hoorfar, M.; Najjaran, H.

2017-01-01

In this work, a low-cost, portable device is developed to detect colorimetric assays for in-field and point-of-care (POC) analysis. The device can rapidly detect both pH values and nitrite concentrations of five different samples, simultaneously. After mixing samples with specific reagents, a high-resolution digital camera collects a picture of the sample, and a single-board computer processes the image in real time to identify the hue–saturation–value coordinates of the image. An internal light source reduces the effect of any ambient light so the device can accurately determine the corresponding pH values or nitrite concentrations. The device was purposefully designed to be low-cost, yet versatile, and the accuracy of the results have been compared to those from a conventional method. The results obtained for pH values have a mean standard deviation of 0.03 and a correlation coefficient R2 of 0.998. The detection of nitrites is between concentrations of 0.4–1.6 mg l−1, with a low detection limit of 0.2 mg l−1, and has a mean standard deviation of 0.073 and an R2 value of 0.999. The results represent great potential of the proposed portable device as an excellent analytical tool for POC colorimetric analysis and offer broad accessibility in resource-limited settings. PMID:29291093