EarlyView Articles

High‐throughput deterministic single‐cell encapsulation and droplet pairing, fusion, and shrinkage in a single microfluidic device

Published: Sep 19, 2013

Author(s): Rogier M. Schoeman, Evelien W.M. Kemna, Floor Wolbers, Albert Berg

Journal: ELECTROPHORESIS

In this article, we present a microfluidic device capable of successive high‐yield single‐cell encapsulation in droplets, with additional droplet pairing, fusion, and shrinkage. Deterministic single‐cell encapsulation is realized using Dean‐coupled inertial ordering of cells in a Yin‐Yang‐shaped curved microchannel using a double T‐junction, with a frequency over 2000 Hz, followed by controlled droplet pairing with a 100% success rate....

Variability of microchip capillary electrophoresis with conductivity detection

Published: Sep 19, 2013

Author(s): Ratna Tantra, Kenneth Robinson, Aneta Sikora

Journal: ELECTROPHORESIS

Microfluidic CE with conductivity detection platforms could have an impact on the future development of smaller, faster and portable devices. However, for the purpose of reliable identification and quantification, there is a need to understand the degree of irreproducibility associated with the analytical technique. In this study, a protocol was developed to remove baseline drift problems sometimes observed in such devices. The protocol,...

Treatment of long‐term stored DNA—Comparison between different methods to obtain high‐quality material

Published: Sep 19, 2013

Author(s): Máira Pedroso Almeida, Carlos Souza do Nascimento, Iuri Viotti Périssé, Marcio Souza Duarte, Renata Veroneze, Simone E. Facioni Guimarães

Journal: ELECTROPHORESIS

Long‐term stored DNA can be sometimes the only source of genetic material of an organism that does not exist anymore, but a research interest still persists. However, there is a lack of information about useful methods to improve quality from such type of material. In this study, we compared four different protocols using DNA samples collected in 1998. Fresh DNA was also tested aiming to check the differences between these two material...

Improved 2 D‐HPLC of red wine by incorporating pre‐process signal‐smoothing algorithms

Published: Sep 18, 2013

Author(s): Paul G. Stevenson, Danielle N. Bassanese, Neil W. Barnett, Xavier A. Conlan

Journal: Journal of Separation Science

Two multidimensional HPLC separations of an Australian red wine are presented, >70% of the available separation space was used. A porous graphitic carbon (PGC) stationary phase was used as the first dimension in both separations with both RP core–shell and hydrophilic interaction chromatography fully porous columns used separately in the second dimension. To overcome peak analysis problems caused by signal noise and low detection...

Improved ultra‐performance liquid chromatography with electrospray ionization quadrupole‐time‐of‐flight high‐definition mass spectrometry method for the rapid analysis of the chemical constituents of a typical medical formula: Liuwei Dihuang Wan

Published: Sep 18, 2013

Author(s): Ping Wang, Hai tao Lv, Ai hua Zhang, Hui Sun, Guang li Yan, Ying Han, Xiu hong Wu, Xi jun Wang

Journal: Journal of Separation Science

Liuwei Dihuang Wan (LDW), a classic Chinese medicinal formula, has been used to improve or restore declined functions related to aging and geriatric diseases, such as impaired mobility, vision, hearing, cognition, and memory. It has attracted increasing attention as one of the most popular and valuable herbal medicines. However, the systematic analysis of the chemical constituents of LDW is difficult and thus has not been well...

GC–MS/MS method for the quantification of α‐cedrene in rat plasma and its pharmacokinetic application

Published: Sep 18, 2013

Author(s): Joo Yeon Hong, Byung Ho Lee, Tae Hwan Kim, Jongki Hong, Kyoung Mee Lee, Sun Dong Yoo, Hye Suk Lee

Journal: Journal of Separation Science

α‐Cedrene is a pharmacologically active ingredient isolated from the essential oil of cedar. A selective and sensitive GC–MS/MS method was developed for the quantification of α‐cedrene in rat plasma for the first time. α‐Cedrene was extracted from rat plasma using ethyl acetate at neutral pH. The analytes were determined in selective reaction monitoring mode using MS/MS: m/z 204.3→119.0 for α‐cedrene and m/z 146.0→111.0 for...

Separation of aromatic amines by an open‐tubular capillary electrochromatography method

Published: Sep 18, 2013

Author(s): Bingbing Sun, Li Qi, Yaping Li, Juan Qiao, Minglin Wang

Journal: Journal of Separation Science

A new and simple open‐tubular CEC (OT‐CEC) method with a novel diblock copolymer poly(butyl methacrylate)71‐block‐poly(glycidyl methacrylate)9 as the coating based on its self‐assembled properties has been developed. Compared with the bare capillary, this coating could act as a surfactant and improve the separation efficiency of aromatic amines. Meanwhile, the effects of pH value, buffer concentration, and the copolymer block ratio on the separation...

Surface‐enhanced Raman scattering within silver‐nanoparticle‐decorated nanometric apertures

Published: Sep 18, 2013

Author(s): Bei Nie, Chaolan He, Lijuan Liu

Journal: Journal of Raman Spectroscopy

An analytical approach using enhanced Raman spectroscopy to record molecular vibrations and associated molecular images within nanometric apertures is presented, which can essentially rival or surpass its counterparts, i.e. fluorescence microscopy, by providing unique structure‐specific information forward to chemical identification and structure elucidation. Utilizing a precise nanolithographic technology and the following chemically...

Solution‐based SERS method to detect dithiocarbamate fungicides in different real‐world matrices

Published: Sep 18, 2013

Author(s): Benjamin Saute, Radha Narayanan

Journal: Journal of Raman Spectroscopy

Surface‐enhanced Raman scattering (SERS) has become a valuable tool for the characterization of trace quantities of environmental toxins. Utilizing established wet chemical synthetic protocols, dogbone‐shaped colloidal gold nanoparticle substrates with sharp features were prepared with regions that exhibit significant SERS enhancement due to the lightning rod effect. These highly enhancing substrates were utilized for the quantitative...

Graphene as an efficient sorbent for the SPE of organochlorine pesticides in water samples coupled with GC–MS

Published: Sep 17, 2013

Author(s): Qiang Han, Zonghua Wang, Jianfei Xia, Linhua Xia, Sha Chen, Xiaoqiong Zhang, Mingyu Ding

Journal: Journal of Separation Science

The determination of organochlorine pesticides in water samples, which are harmful to humans, is very important for environmental risk assessment. Based on the excellent adsorption properties of graphene, an SPE coupled with GC–MS method for the monitoring of organochlorines (four hexachlorcyclohexanes and four dichlorodiphenyltrichloroethanes) was developed. Owing to the hydrophobic interaction and π–π stacking interaction between the...

A general variance model in methods comparison

Published: Sep 17, 2013

Author(s): Douglas M. Hawkins

Journal: Journal of Chemometrics

Valid statistical tests of paired data require correct models of how measurement variance depends on analyte concentration. One often‐used assumption is that the variance is constant across the range; another is that the coefficient of variation is constant. But in many data sets, neither of these holds. A variance model containing both a constant variance and a constant coefficient of variation term is recommended as an often‐useful...

Linear quantification calibration of crystallinity based on a simple univariate analysis of binary chemical images by selecting a threshold to define the sampling depth in Raman mapping

Published: Sep 17, 2013

Author(s): Jianping Wu

Journal: Journal of Raman Spectroscopy

ABSTRACT It is common belief that in Raman mapping, the sampling depth from which Raman signal is collected originates from a probe laser spot size of approximately 1–5 µm3. Actually, the active pharmaceutical ingredient (API) crystals detected by mapping on the sample surface distribute from surface to over a few tens to hundreds of microns into the sample, as determined by z‐slices mapping in this context. It was also found that the score of...

The improvement of InAs/GaAs quantum dot properties capped by Graphene

Published: Sep 17, 2013

Author(s): Kamel Rezgui, Riadh Othmen, Antonella Cavanna, Hosni Ajlani, Ali Madouri, Meherzi Oueslati

Journal: Journal of Raman Spectroscopy

InAs self‐assembled quantum dots (QDs) were grown by molecular beam epitaxy on (001) GaAs substrate. Uncapped and capped QDs with GaAs and graphene layers were studied using atomic force microscopy and Raman spectroscopy. Graphene multi‐layer was grown by chemical vapor deposition and transferred on InAs/GaAs QDs. It is well known that the presence of a cap layer modifies the size, shape, and density of the QDs. According to the atomic...

The temperature dependence of the Raman spectra of chromium‐doped titanite (CaTiOSiO ₄ )

Published: Sep 17, 2013

Author(s): Anton M. Heyns, Peter M. Harden

Journal: Journal of Raman Spectroscopy

Summary The temperature dependence of the Raman bands of Cr4+ modes which show enhanced intensities due to pre‐resonance effects is reported from 293 to 673 K in chromium‐doped titanite (CaTiOSiO4). Some aspects of the temperature dependence of Raman bands in pure, synthetic titanite which have not been previously published are also included in this study. Two Raman‐active components of Ag and Bg symmetry, respectively, of the symmetric Si–O...

Chemical approaches to detect and analyze protein sulfenic acids

Published: Sep 17, 2013

Author(s): Cristina M. Furdui, Leslie B. Poole

Journal: Mass Spectrometry Reviews

Abstract Orchestration of many processes relying on intracellular signal transduction is recognized to require the generation of hydrogen peroxide as a second messenger, yet relatively few molecular details of how this oxidant acts to regulate protein function are currently understood. This review describes emerging chemical tools and approaches that can be applied to study protein oxidation in biological...

Modeling of the diffusion MR signal in calibrated model systems and nerves

Published: Sep 16, 2013

Author(s): Darya Morozov, Leah Bar, Nir Sochen, Yoram Cohen

Journal: NMR in Biomedicine

Diffusion NMR is a powerful tool for gleaning microstructural information on opaque systems. In this work, the signal decay in single‐pulsed‐field gradient diffusion NMR experiments performed on a series of phantoms of increasing complexity, where the ground truth is known a priori, was modeled and used to identify microstructural features of these complex phantoms. We were able to demonstrate that, without assuming the number of...

Tissue‐ and column‐specific measurements from multi‐parameter mapping of the human cervical spinal cord at 3 T

Published: Sep 16, 2013

Author(s): R. S. Samson, O. Ciccarelli, C. Kachramanoglou, L. Brightman, A. Lutti, D. L. Thomas, N. Weiskopf, C. A. M. Wheeler‐Kingshott

Journal: NMR in Biomedicine

The aim of this study was to quantify a range of MR parameters [apparent proton density, longitudinal relaxation time T1, magnetisation transfer (MT) ratio, MT saturation (which represents the additional percentage MT saturation of the longitudinal magnetisation caused by a single MT pulse) and apparent transverse relaxation rate R2*] in the white matter columns and grey matter of the healthy cervical spinal cord. The cervical cords of 13 healthy volunteers ...

Influence of different mass absorption coefficient datasets on PIXE yields

Published: Sep 16, 2013

Author(s): Rainer Siegele, David D. Cohen

Journal: X-Ray Spectrometry

Tabulated mass absorption coefficient data from the XCOM, Chantler and ion beam analysis (IBA) Handbook are compared, and differences are shown against X‐ray energy and target atomic number. Over the X‐ray energy range 1–40 keV systematic differences of several tens of percent are noted between these datasets, particularly for the earlier IBA Handbook dataset. The influence of these different mass absorption coefficients on the X‐ray...

Response to Professor Kawai's review on forensic synchrotron X‐ray fluorescence analysis of arsenic poisoning in Japan

Published: Sep 16, 2013

Author(s): Izumi Nakai

Journal: X-Ray Spectrometry

Process analytical chemistry and chemometrics, Bruce Kowalski's legacy at The Dow Chemical Company

Published: Sep 16, 2013

Author(s): Randy J. Pell, Mary Beth Seasholtz, Kenneth R. Beebe, Mel V. Koch

Journal: Journal of Chemometrics

With the passing of Bruce R. Kowalski in 2012, a true visionary for chemometrics and process analytical chemistry has been lost. Bruce made significant contributions in the area of chemometrics and process analytical chemistry when he was a professor of chemistry at the University of Washington. He developed new and innovative chemometrics technology and founded the Center for Process Analytical Chemistry. He inspired many students and...