scholarly journals Heteroleptic Pt(II)-dithiolene-based Colorimetric Chemosensors: Selectivity Control for Hg(II) Ion Sensing

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1385
Author(s):  
Hyokyung Jeon ◽  
Hwahui Ryu ◽  
Inho Nam ◽  
Dong-Youn Noh
Keyword(s):  
Stokes Shift ◽  
Reference Signal ◽  
Internal Reference ◽  
Simple Method ◽  
Precise Control ◽  
Ion Sensing ◽  
The Central Nervous System ◽  
Dmit Ligand ◽  
Selectivity Control ◽  
End Group

Hg2+ ions can accumulate in the natural environment and in organisms, where they cause damage to the central nervous system. Therefore, the detection of Hg2+ ions is essential for monitoring environmental contamination and human health. Herein, we demonstrate a simple method for tuning chemosensor signal ratios that significantly increased chemosensor selectivity for Hg2+ detection. Selectivity tuning was accomplished for chemosensors of the type (diphosphine)Pt(dmit), bearing the two different terminal groups 1,2-bis(diphenylphosphino)ethane (dppe) and 1,2-bis[bis(pentafluorophenyl)phosphino]ethane) (dfppe) due to the modulation of specific intermolecular interactions between the dmit ligand and Hg2+ ion. The structure exhibited a large pseudo-Stokes shift, which was advantageous for the internal reference signal and for eliminating potential artifacts. Straightforward chain-end manipulation enabled the tuning of chemosensor properties without additional chemical alterations. Based on these findings, we propose a new platform for improving the selectivity and sensitivity of colorimetric cation sensors. The results of this study will facilitate the designing of organic materials whose certain properties can be enhanced through precise control of the materials’ chemical hybridization by simple functional end-group manipulation.

KINETIC ASPECTS OF THE COPOLYMERIZATION OF TETRAHYDROFURAN WITH PROPYLENE OXIDE. I

1966 ◽  
Vol 44 (22) ◽  
pp. 2679-2689 ◽  
Author(s):  
L. P. Blanchard ◽  
J. Singh ◽  
M. D. Baijal
Keyword(s):  
Vapor Pressure ◽  
Propylene Oxide ◽  
Chemical Reduction ◽  
Group Analysis ◽  
Vapor Pressure Osmometry ◽  
Hydroxyl Groups ◽  
Internal Reference ◽  
Boron Fluoride ◽  
Co Catalysts ◽  
End Group

Tetrahydrofuran and propylene oxide were copolymerized in the presence of the catalyst boron fluoride ethyl ether, and various co-catalysts, such as 1,2-propanediol, 1,3-propanediol, and 1,4-butanediol. Ethylene chloride was used as a solvent and as an internal reference for analytical purposes. Reactions were carried out at 0 °C and at atmospheric pressure. Monomer concentrations were determined by vapor phase chromatography, and copolymer molecular structure analyses were carried out by physical and chemical methods including infrared spectroscopy, vapor pressure osmometry, hydroxyl end-group analysis, and chemical reduction of unsaturated linkages.The homopolymerization of tetrahydrofuran did not take place, whereas that of propylene oxide proceeded at a rapid rate. In the copolymerization of tetrahydrofuran with propylene oxide, the rate of disappearance of tetrahydrofuran was found to be independent of its concentration, but varied directly with the concentration of propylene oxide. Under similar conditions, the rate of disappearance of propylene oxide was found to be (a) proportional to the square of its concentration, and (b) inversely proportional to the concentration of tetrahydrofuran.Reactivity ratios varied between 1.3 and 1.8 for propylene oxide and between 0.1 and 0.6 for tetrahydrofuran. Molecular weights obtained by vapor pressure osmometry ranged between 460 and 740, and those obtained by hydroxyl end-group analysis ranged between 520 and 1 660. Infrared spectra confirmed the presence of hydroxyl groups and ether linkages in the copolymers prepared. Results on terminal unsaturation were negative.

scholarly journals Controlling fluid flow to improve cell seeding uniformity

2018 ◽  
Author(s):  
Paul M. Reynolds ◽  
Camilla Holzmann Rasmussen ◽  
Mathias Hansson ◽  
Martin Dufva ◽  
Mathis O. Riehle ◽  
...  
Keyword(s):  
Cell Density ◽  
Embryonic Stem ◽  
Local Variation ◽  
Seeding Density ◽  
Cell Seeding ◽  
Simple Method ◽  
Precise Control ◽  
Seeding Method ◽  
Macro Scale ◽  
The Impact

AbstractStandard methods for seeding monolayer cell cultures in a multiwell plate or dish do not uniformly distribute cells on the surface. With traditional methods, users find aggregation around the circumference, in the centre, or a combination of the two. This variation is introduced due to the macro scale flow of the cell seeding suspension, and movement of the dish before cells can settle and attach to the surface. Reproducibility between labs, users, and experiments is hampered by this variability in cell seeding. We present a simple method for uniform and user-independent cell seeding using an easily produced uniform cell seeder (UCS) device. This allows precise control of cell density in a reproducible manner. By containing the cell seeding suspension in a defined volume above the culture surface with the UCS, fluctuations in cell density are minimised. Seeding accuracy, as defined by the actual cell density versus the target seeding density is improved dramatically across users with various levels of expertise. We go on to demonstrate the impact of local variation in cell density on the lineage commitment of human embryonic stem cells (hESCs) towards pancreatic endoderm (PE). Variations in the differentiation profile of cells across a culture well closely mirror variations in cell density introduced by seeding method – with the UCS correcting variations in differentiation efficiency. The UCS device provides a simple and reproducible method for uniform seeding across multiple culture systems.

scholarly journals Qki regulates myelinogenesis through Srebp2-dependent cholesterol biosynthesis

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Xin Zhou ◽  
Seula Shin ◽  
Chenxi He ◽  
Qiang Zhang ◽  
Matthew N Rasband ◽  
...  
Keyword(s):  
Rna Binding ◽  
Cholesterol Biosynthesis ◽  
Oligodendrocyte Precursor Cells ◽  
Canonical Function ◽  
Oligodendrocyte Differentiation ◽  
Precise Control ◽  
The Central Nervous System ◽  
Oligodendrocyte Precursor ◽  
Underlying Mechanisms ◽  
Myelin Assembly

Myelination depends on timely, precise control of oligodendrocyte differentiation and myelinogenesis. Cholesterol is the most abundant component of myelin and essential for myelin membrane assembly in the central nervous system. However, the underlying mechanisms of precise control of cholesterol biosynthesis in oligodendrocytes remain elusive. In the present study, we found that Qki depletion in neural stem cells or oligodendrocyte precursor cells in neonatal mice resulted in impaired cholesterol biosynthesis and defective myelinogenesis without compromising their differentiation into Aspa+Gstpi+ myelinating oligodendrocytes. Mechanistically, Qki-5 functions as a co-activator of Srebp2 to control transcription of the genes involved in cholesterol biosynthesis in oligodendrocytes. Consequently, Qki depletion led to substantially reduced concentration of the cholesterol in mouse brain, impairing proper myelin assembly. Our study demonstrated that Qki-Srebp2–controlled cholesterol biosynthesis is indispensable for myelinogenesis and highlights a novel function of Qki as a transcriptional co-activator beyond its canonical function as an RNA-binding protein.

scholarly journals An Electrophysiological Correlate of Visual Motion Awareness in Man

1998 ◽  
Vol 10 (4) ◽  
pp. 464-471 ◽  
Author(s):  
Thomas Haarmeier ◽  
Peter Thier
Keyword(s):  
Eye Movement ◽  
Smooth Pursuit ◽  
Visual Processing ◽  
Retinal Image ◽  
Visual Motion ◽  
Reference Signal ◽  
Subjective Perception ◽  
Internal Reference ◽  
Signal Encoding ◽  
Physical Attributes

It is usually held that perceptual spatial stability, despite smooth pursuit eye movements, is accomplished by comparing a signal reflecting retinal image slip with an internal reference signal, encoding the eye movement. The important consequence of this concept is that our subjective percept of visual motion reflects the outcome of this comparison rather than retinal image slip. In an attempt to localize the cortical networks underlying this comparison and therefore our subjective percept of visual motion, we exploited an imperfection inherent in it, which results in a movement illusion. If smooth pursuit is carried out across a stationary background, we perceive a tiny degree of illusionary background motion (Filehne illusion, or FI), rather than experiencing the ecologically optimal percept of stationarity. We have recently shown that this illusion can be modified substantially and predictably under laboratory conditions by visual motion unrelated to the eye movement. By making use of this finding, we were able to compare cortical potentials evoked by pursuit-induced retinal image slip under two conditions, which differed perceptually, while being identical physically. This approach allowed us to discern a pair of potentials, a parieto-occipital negativity (N300) followed by a frontal positivity (P300), whose amplitudes were solely determined by the subjective perception of visual motion irrespective of the physical attributes of the situation. This finding strongly suggests that subjective awareness of visual motion depends on neuronal activity in a parietooccipito-frontal network, which excludes the early stages of visual processing.

Dimesitylboryl-containing polydiphenylacetylene with a large Stokes shift, high fluorescence efficiency, and fluoride ion sensing ability

Polymer ◽  
2018 ◽  
Vol 148 ◽  
pp. 310-315 ◽  
Author(s):  
Young-Jae Jin ◽  
Daichi Araki ◽  
Masahiro Teraguchi ◽  
Toshiki Aoki ◽  
Giseop Kwak
Keyword(s):  
Stokes Shift ◽  
Fluoride Ion ◽  
Large Stokes Shift ◽  
Ion Sensing ◽  
Fluorescence Efficiency ◽  
High Fluorescence

Analysis of Pointing Errors Reveals Properties of Data Representations and Coordinate Transformations Within the Central Nervous System

2000 ◽  
Vol 12 (12) ◽  
pp. 2823-2855 ◽  
Author(s):  
J. McIntyre ◽  
F. Stratta ◽  
J. Droulez ◽  
F. Lacquaniti
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Reference Frames ◽  
Target Location ◽  
Motor Command ◽  
Coordinate Transformations ◽  
Internal Reference ◽  
Internal Representations ◽  
Pointing Task ◽  
The Central Nervous System

The execution of a simple pointing task invokes a chain of processing that includes visual acquisition of the target, coordination of multimodal proprioceptive signals, and ultimately the generation of a motor command that will drive the finger to the desired target location. These processes in the sensorimotor chain can be described in terms of internal representations of the target or limb positions and coordinate transformations between different internal reference frames. In this article we first describe how different types of error analysis can be used to identify properties of the internal representations and coordinate transformations within the central nervous system. We then describe a series of experiments in which subjects pointed to remembered 3D visual targets under two lighting conditions (dim light and total darkness) and after two different memory delays (0.5 and 5.0 s) and report results in terms of variable error, constant error, and local distortion. Finally, we present a set of simulations to help explain the patterns of errors produced in this pointing task. These analyses and experiments provide insight into the structure of the underlying sensorimotor processes employed by the central nervous system.

Direct growth of few layer graphene on SiO2 substrate by low energy carbon ion implantation

RSC Advances ◽  
2016 ◽  
Vol 6 (103) ◽  
pp. 101347-101352 ◽  
Author(s):  
P. Dharmaraj ◽  
P. Sundara Venkatesh ◽  
Pravin Kumar ◽  
K. Asokan ◽  
K. Jeganathan
Keyword(s):  
Ion Implantation ◽  
Low Energy ◽  
Simple Method ◽  
Sio2 Substrate ◽  
Precise Control ◽  
Si Substrates ◽  
Layer Graphene ◽  
Direct Fabrication ◽  
Direct Growth ◽  
Few Layer Graphene

A simple method that enables the direct fabrication of few layer graphene on SiO2/Si substrates with precise control of layer thickness by implantation of C ions is explored.

A Rapid and Simple Method for the Separation of Four Molecular Forms of Human Plasminogen

1989 ◽  
Vol 61 (02) ◽  
pp. 208-210 ◽  
Author(s):  
W Nieuwenhuizen ◽  
D W Traas
Keyword(s):  
Molecular Forms ◽  
Terminal Amino Acid ◽  
Simple Method ◽  
Efficient Procedure ◽  
Carbohydrate Analysis ◽  
Amino Terminal ◽  
Human Plasminogen ◽  
Terminal Amino ◽  
Differential Affinity ◽  
End Group

SummaryAt least four molecular forms of plasminogen are known. Two of those forms have glutamic acid at their amino-terminal end, and are designated as glu-plasminogen. The other two have lysine, methionine and/or valine as amino-terminal amino acid and are collectively designated as lys-plasminogen. Two subforms (I and II) each of glu- and lys-plasminogen exist. The I-forms are glycosylated at asn-288 and thr-345, whereas the II-forms are only glycosylated at thr-345. In a previous publication (Thromb Haemostas 1984; 52: 347-349) we have described the separation of the I- and II-forms of plasminogen in lysine-Sepharose in phosphate buffers. Now we have combined those findings with the differential affinity of glu- and lys-plasminogen for aminohexyl-Sepharose through their aminohexyl-sites, recently described by Christensen (Biochem J 1984; 223: 431-421). Acid/urea electrophoresis, end-group determination and carbohydrate analysis show that the combination of affinity chromatography on lysine-Sepharose in phosphate buffers, and on aminohexyl-Sepharose provides an efficient procedure to separate the four molecular forms of plasminogen.

Silver embedded nanostars for SERS with internal reference (SENSIR)

2015 ◽  
Vol 3 (28) ◽  
pp. 7319-7324 ◽  
Author(s):  
Andrew M. Fales ◽  
Tuan Vo-Dinh
Keyword(s):  
Reference Signal ◽  
Internal Reference ◽  
Silver Shell

Reference dye labeled nanostars are embedded in a partial silver shell, retaining the sharp gold tips for non-aggregated SERS of external analytes while providing an internal reference signal.

Molecular Complexes, V [1, 2] 1H NMR Investigation of the Caffeine Benzene Complex Followed by AUS Correction of Experimental Data Structural Requirements for Substances to Serve as Internal Reference in Investigations of Weak Complexes

1981 ◽  
Vol 36 (12) ◽  
pp. 1618-1627 ◽  
Author(s):  
Helmut Stamm ◽  
Jürgen Stafe
Keyword(s):  
Reference Group ◽  
Reference Signal ◽  
Molecular Complexes ◽  
Complex Model ◽  
Range Shifts ◽  
Nonlinear Behaviour ◽  
Internal Reference ◽  
External Reference ◽  
Weak Complexes ◽  
Scatchard Plots

Abstract The 4 proton signals of caffeine, dissolved in carbon tetrachloride, were investigated as functions of benzene concentrations in a very large concentration range. Shifts of the 4 signals were measured relative to both internal and external reference. Scatchard plots of the internally referenced data were curved downwards, the degree of curving increasing from 7-methyl/8-H to 3-methyl to 1-methyl. The 1-methyl plot even showed a maximum in the observed relative shifts ⊿oi which turned to negative values for high benzene concentrations. Scatchard plots of the externally referenced data were curved upwards.Applying AUS corrections [1, 8] to both sets of data furnished linear Scatchard plots for ah signals. The plots for the 4 protons were parallel to one another in case of the externally referenced data and not parallel for the internally referenced data. Equilibrium quotients K calculated from the externally referenced data for each of the 4 different protons were essentially the same. This gives evidence that the system behaves in accord with the pure 1:1 complex model and does not demand the assumption of simultaneous occurence of higher complexes. The values for K (= .115 l/mol), for the 4 apparent complex shifts (Icpt/K) and for the 4 nuclei specific AUS coefficients a 2 [1, 8] could be confirmed and somewhat improved by a Creswell-Allred processing of the data including AUS correction.The failure of the AUS correction in producing parallel Scatchard plots from internally referenced shifts is caused by the nonlinear floating with the donor concentration of the internal reference signal. The cause of this nonlinear behaviour is analyzed, and arguments are presented that it can be prevented by use of reference substances with only one single reference group per molecule, i.e. the signal of such an internal reference must not have its origin in two or more equivalent nuclei groups within the reference molecule.

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