scholarly journals Chiral Separation of rac-Propylene Oxide on Penicillamine Coated Gold NPs

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1716
Author(s):  
Nisha Shukla ◽  
Zachary Blonder ◽  
Andrew J. Gellman
Keyword(s):  
Propylene Oxide ◽  
Room Temperature ◽  
Adsorption Properties ◽  
Time Dependent ◽  
Prior Work ◽  
Au Nps ◽  
The Past ◽  
Racemic Mixtures ◽  
Enantioselective Adsorption ◽  
Gold Nps

The surfaces of chemically synthesized spherical gold NPs (Au-NPs) have been modified using chiral L- or D-penicillamine (Pen) in order to impart enantioselective adsorption properties. These chiral Au-NPs have been used to demonstrate enantioselective adsorption of racemic propylene oxide (PO) from aqueous solution. In the past we have studied enantioselective adsorption of racemic PO on L- or D-cysteine (Cys)-coated Au-NPs. This prior work suggested that adsorption of PO on Cys-coated Au-NPs equilibrates within an hour. In this work, we have studied the effect of time on the enantioselective adsorption of racemic PO from solution onto chiral Pen/Au-NPs. Enantioselective adsorption of PO on chiral Pen/Au-NPs is time-dependent but reaches a steady state after ~18 h at room temperature. More importantly, L- or D-Pen/Au-NPs are shown to adsorb R- or S-PO enantiospecifically and to separate the two PO enantiomers from racemic mixtures of RS-PO.

Growth of Au Nanoparticles Stimulate Spectroscopic Properties of Er3+ Doped TeO2-ZnO-Na2O Glasses

2014 ◽  
Vol 895 ◽  
pp. 254-259 ◽  
Author(s):  
Asmahani Awang ◽  
Sib Krishna Ghoshal ◽  
M.R. Sahar ◽  
M. Reza Dousti ◽  
Fakhra Nawaz
Keyword(s):  
Heat Treatment ◽  
Optical Absorption ◽  
Room Temperature ◽  
Au Nanoparticles ◽  
Optical Band Gap ◽  
Urbach Energy ◽  
Spectroscopic Properties ◽  
Au Nps ◽  
Amorphous Nature ◽  
Gold Nps

The changes in optical properties of 70TeO2-20ZnO-10Na2O-0.5Er2O3-0.2Au glass system are stimulated by varying the heat treatment duration. The XRD data reveals broad humps in range of 25-35 degree representing the amorphous nature of the glass materials. The optical absorption edge at room temperature is used to estimate the direct (Edir), indirect (Eindir) optical band gap and the Urbach energy (EU). The value of Edirlies between 2.937 to 2.943 eV, while the value of Eindirlies within 2.478 to 2.502 eV. The value of EUis found to increase with longer time of heat treatment and lies between 0.409 to 0.424 eV. The characteristic surface plasmon resonance (SPR) band of Au nanoparticles (NPs) was observed at ~630 nm of optical absorption spectra. The strong and medium green upconversion (UC) fluorescence from Er3+centred at 547 and 533 nm were observed at room temperature, in addition to a weak red UC fluorescence from Er3+centred at 637 nm. The SPR stimulated by the presence of Au NPs enhanced the luminescence intensity by four and five folds for 1 and 4 hours heat treatment, respectively. The results indicate that there is a large influence of growth of gold NPs on the optical and spectroscopic properties of glass samples. Our results may be useful for the fabrication of nanophotonic materials.

Time-dependent changes of adsorption and wetting properties of pillared montmorillonites

Clay Minerals ◽  
2000 ◽  
Vol 35 (5) ◽  
pp. 763-769 ◽  
Author(s):  
I. Dékány ◽  
V. Seefeld ◽  
G. Lagaly
Keyword(s):  
Room Temperature ◽  
Total Pore Volume ◽  
Adsorption Properties ◽  
Time Dependent ◽  
Basal Spacing ◽  
Wetting Properties ◽  
Surface Character ◽  
Activated Bentonite ◽  
Pillared Montmorillonites ◽  
Enthalpy Of Immersion

AbstractThe changes of adsorption properties of uncalcined Al-pillared montmorillonite were studied. A soda-activated bentonite from Slovakia was reacted with polymeric hydroxoaluminium salt solutions. During storagein air at room temperature for three years, the basal spacing decreased by 0.15–0.2 nm; the specific surface area was reduced by 80% and the total pore volume by 40–60%. Adsorption experiments from ethanol-cyclohexane mixtures revealed the decreasing adsorption capacity and the increasing hydrophobicity. The changing surface character was also evident in the decrease in enthalpy of immersion in ethanol from 65.3 J/g to 8.3 J/g (sample B) and from 37.8 J/g to 5.2 J/g (sample C). The alteration probably arises from gradual formation of gibbsite-like interlayers and the redistribution of charges.

Granular bainite or granular ferrite? A preliminary TEM investigation of an HSLA-100 steel

1991 ◽  
Vol 49 ◽  
pp. 584-585
Author(s):  
R. Varughese ◽  
S. W. Thompson ◽  
P. R. Howell
Keyword(s):  
Room Temperature ◽  
Transformation Products ◽  
Accurate Description ◽  
Granular Bainite ◽  
Preliminary Results ◽  
The Past ◽  
Light Micrograph ◽  
Multiphase Reaction ◽  
Detailed Nature

Ever since Habraken and Economopoulos first employed the term granular bainite to classify certain unconventional transformation products in continuously cooled steels, the term has been widely accepted and used, despite the lack of a clear consensus as to the detailed nature of the transformation products which constitute granular bainite. This paper presents the preliminary results of a TEM investigation of an 0.04 wt% C, copper-containing steel (designated HSLA-100). It is suggested that the term granular ferrite rather than granular bainite is a more accurate description of this multiphase reaction product.Figure 1 is a light micrograph of a sample which had been air-cooled from 900°C to room temperature. The microstructure is typical of that which has been termed granular bainite in the past and appears to consist of equiaxed ferritic grains together with other minor transformation products. In order to examine these structures in more detail, both continuously cooled and isothermally transformed and quenched materials have been examined with TEM. Granular bainite has been found in virtually all samples.

Organophotoredox-Catalyzed C–H Alkylation of Imidazoheterocycles with Malonates: Total Synthesis of Zolpidem

Synthesis ◽  
2020 ◽  
Author(s):  
Narendra R. Chaubey ◽  
Anant R. Kapdi ◽  
Biswanath Maity
Keyword(s):  
Total Synthesis ◽  
Room Temperature ◽  
Drug Molecule ◽  
Bond Functionalization ◽  
First Report ◽  
Mild Conditions ◽  
The Past ◽  
Hypnotic Drug ◽  
Free Environment

AbstractOrganophotocatalytic C–H bond functionalization has attracted a lot of attention in the past several years due to the possibility of catalyzing reactions in a metal- and peroxide-free environment. Continuing on these lines, an organophotoredox-catalyzed C–H functionalization of imidazo[1,2-a]pyridines and related heterocycles with bromomalonates under mild conditions is reported, providing excellent yields of the products at room temperature. This is the first report involving malonates as coupling partners leading to the synthesis of a range of functionalized products including total synthesis of zolpidem, a sedative­-hypnotic drug molecule.

scholarly journals A Facile Co-crystallization Approach to Fabricate Two-component Carbon Dots Composites Showing Time-Dependent Evolutive Room Temperature Phosphorescence Colors

2021 ◽  
Author(s):  
Jian Qu ◽  
Xin Zhang ◽  
Zhong-Jie Wang ◽  
Shuyan Zhang ◽  
Yejian Yu ◽  
...  
Keyword(s):  
Carbon Dots ◽  
Room Temperature ◽  
Data Encryption ◽  
Time Dependent ◽  
Security Level ◽  
Room Temperature Phosphorescence ◽  
Two Component ◽  
Carbon Based

Time-dependent evolutive afterglow materials can increase the security level by providing additional encryption modes in anti-counterfeiting and data encryption. The design of carbon-based materials with dynamic afterglow colors is attractive...

Carbon Capture Performance of Amino-Modified MIL-101 at Room Temperature

2013 ◽  
Vol 395-396 ◽  
pp. 637-640
Author(s):  
Yi Yang ◽  
Zheng Ping Wang ◽  
Ling Meng ◽  
Lian Jun Wang
Keyword(s):  
Carbon Dioxide ◽  
Specific Surface ◽  
Pore Structure ◽  
Carbon Capture ◽  
Room Temperature ◽  
Ambient Pressure ◽  
Metal Organic Framework ◽  
Adsorption Properties ◽  
Carbon Dioxide Adsorption ◽  
Before And After

MIL-101, a metal-organic framework material, was synthesized by the high-temperature hydrothermal method. Triethylenetetramine (TETA) modification enabled the effective grafting of an amino group onto the surface of the materials and their pore structure. The crystal structure, micromorphology, specific surface area, and pore structure of the samples before and after modification were analyzed with an X-ray diffractometer, scanning electron microscope, specific surface and aperture tester, and infrared spectrometer. The carbon dioxide adsorption properties of the samples were determined by a thermal analyzer before and after TETA modification. Results show that moderate amino modification can effectively improve the microporous structure of MIL-101 and its carbon dioxide adsorption properties. After modification, the capacity of MIL-101 to adsorb carbon dioxide decreased only by 0.61 wt%, and a high adsorption capacity of 9.45 wt% was maintained after six cycles of adsorption testing at room temperature and ambient pressure.

Increase in Cell Number as a Factor in the Growth of the Organs and Tissues of the Young Male Rat

Development ◽  
1962 ◽  
Vol 10 (4) ◽  
pp. 530-562
Author(s):  
M. Enesco ◽  
C. P. Leblond
Keyword(s):  
Body Weight ◽  
Weight Gain ◽  
Room Temperature ◽  
Young Male ◽  
Cell Number ◽  
The Body ◽  
Male Rat ◽  
The Past ◽  
Old Rats ◽  
Young Rat

While the organs and tissues of the young rat are known to increase in size with age (Donaldson, 1924), little is known of the role played by the component cells in this increase. There is evidence that cells enlarge (Levi, 1906; Plenk, 1911) and new cells are added (Strasburger, 1893), but we do not know to what extent the enlargement and proliferation of the cells cause the growth of organs and tissues. The present work is an attempt to clarify this problem. In the past, the growth of organs and tissues has often been measured by weight gain (Donaldson, 1924). However, this approach might be misleading, since the body-weight may increase in the absence of growth, for instance as a result of fat-storage in old rats, of pregnancy in females, and even of changes in room temperature.

Feasibility Study of a New Fabrication Method for the Li4SiO4 Pebbles

2018 ◽  
Author(s):  
R. Lo Frano ◽  
M. Puccini ◽  
E. Stefanelli ◽  
M. Luppichini ◽  
C. Grima ◽  
...  
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Power Reactor ◽  
Fabrication Method ◽  
Fusion Power ◽  
Spray Process ◽  
The Past ◽  
Experimental Apparatus ◽  
Standard Solution ◽  
Lithium Orthosilicate

In the past decades many R&D efforts have been spent in the development of a suitable Li4SiO4 fabrication method (e.g., melt spray process, graphite bed method, capillary-based microfluidic wet method etc.), nevertheless we are still far from an “industrial standard solution”. The aim of the paper is to develop a new fabrication method capable to produce stable and well-sized pebbles of lithium orthosilicate (Li4SiO4) based on the drip casting. This method is mainly based on the dripping at room temperature, which is novel in the framework of available fabrication processes requiring high temperature: this latter is demonstrated to affect the final product characteristics. It is worthy to remark that the Li4SiO4 is a candidate material for the breeding blanket material of the fusion power reactor. In the paper we will describe the experimental apparatus, designed and built at DICI - University of Pisa with the collaboration of Bitossi Industries, and the procedure adopted in order to produce pebbles of Li4SiO4.

Making Memories Unavailable

2007 ◽  
Vol 215 (1) ◽  
pp. 4-11 ◽  
Author(s):  
Karl-Heinz Bäuml
Keyword(s):  
Memory Representation ◽  
Prior Work ◽  
Experimental Paradigm ◽  
Memory Tests ◽  
Inhibitory Processes ◽  
The Past ◽  
Wide Range ◽  
Extended Range ◽  
Subsequent Recall ◽  
Retrieval Blocking

Abstract. Research from the past decades has shown that cuing and retrieval are not always beneficial for episodic memory and can also be detrimental. Prior work assumed that these detrimental effects are caused by retrieval blocking, in which cuing and retrieval strengthen material and the repeated involuntary sampling of the strengthened material hinders subsequent recall of nonstrengthened targets. Using a new experimental paradigm and an extended range of memory tests, recent research indicates that the detrimental effects of retrieval and cuing occur across a wide range of memory tests and are likely to be the result of inhibitory processes. These inhibitory processes impair the nonretrieved and noncue items' memory representation and make these items unavailable in memory. The recent results and the new theory are reviewed and discussed.

scholarly journals Artifacts associated with mithramycin fluorescence in the clinical detection and quantitation of aneuploidy by flow cytometry.

1982 ◽  
Vol 30 (4) ◽  
pp. 317-322 ◽  
Author(s):  
R E Cunningham ◽  
K S Skramstad ◽  
A E Newburger ◽  
S E Shackney
Keyword(s):  
Flow Cytometry ◽  
Room Temperature ◽  
Human Melanoma ◽  
Time Dependent ◽  
Clinical Samples ◽  
Fixation Time ◽  
C Cells ◽  
Temperature Dependent ◽  
Clinical Detection

Ethanol-fixed cells stored at 4 degrees C exhibit fixation time-dependent hyperchromatism in comparison with freshly fixed cells when stained with mithramycin and examined by flow cytometry. This hyperchromatism has been found to be temperature-dependent, developing fully within 72 hr at room temperature, and within 2 hr at 37 degrees C. Cells from normal donors that are stained with mithramycin exhibit spurious aneuploid peaks. These spurious aneuploid peaks can be eliminated by incubating ethanol-fixed cells at 37 degrees C for 2 hr prior to staining; true aneuploidy is not affected by this procedure. In rare instances, cytoplasmic fluorescence can be observed in mithramycin-stained cells. In addition, unexplained hypochromatism and hyperchromatism can be observed in some clinical samples, particularly in human melanoma. The effects of these unexplained staining artifacts can be minimized or eliminated by adopting strict criteria for the clinical detection of aneuploidy by flow cytometry.

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