scholarly journals Formation of Nanoclusters in Gold Nucleation

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 382
Author(s):  
Cornelia M. Schneider ◽  
Helmut Cölfen
Keyword(s):  
Analytical Ultracentrifugation ◽  
Gold Nanoclusters ◽  
Ion Concentration ◽  
Atom Number ◽  
Clear Trend ◽  
Stable Clusters ◽  
Gold Precursor ◽  
The Moment ◽  
Gold Ion

Gold nanoclusters consisting of a specific atom number have gained popularity in research in recent years due to their outstanding properties. Due to their molecule-like behavior, their properties depend strongly on their size. Although they represent the link species between atoms and nanoparticles and are the subject of current research, a high-resolution characterization is still missing. Here, we used the band forming experiment in analytical ultracentrifugation (AUC) to characterize the gold nanoclusters in the moment of their generation using thioglycerol as a stabilizer. The concentration variation of the gold precursor, reducing agent, and stabilizer was investigated. The formation of different cluster species from the smallest Au4 up to Au911 could be observed. Very stable clusters of Au55 appear in every experiment and other cluster sizes more rarely. The extracted UV/Vis spectra could additionally be correlated to every cluster. The variation in the concentration of sodium borohydride and the stabilizer did not lead to a clear trend, but the gold ion concentration directed the size of the formed clusters. A decrease seemed to promote the generation of a higher abundance of smaller clusters accompanied by less big clusters, and vice versa. These results present the characterization of the different nanocluster generations directly in the formation process of nanoparticles and therefore are a contribution to the understanding of their formation.

La structure de classes québécoise au 19e siècle et le problème de l'articulation des modes de production

1981 ◽  
Vol 14 (3) ◽  
pp. 487-518
Author(s):  
Gérald Bernier
Keyword(s):  
Census Data ◽  
New France ◽  
Class Structure ◽  
Capitalist Development ◽  
Single Class ◽  
The Moment ◽  
Empirical Demonstration ◽  
Work Done ◽  
The Impact

The study of social classes in the nineteenth century requires the development of conceptual tools able to explain the impact of the Conquest on the pre-existant social structures in determining transformations of the class structure during the subsequent decades.This article examines the work done on this question by Marxist writers. The author criticizes certain conclusions which have been drawn and which suggest deficiencies at a theoretical level. The objections relate to the marked tendency of these conclusions to perceive the structural effects of the Conquest in terms of the formation of a double-class structure characterized by “ethnic origins.” Specifically, the author challenges the notion of the division itself, as well as the criterion on which the division is based.The author proposes that an analysis centred upon the concepts relating to a problem of the transition and linkage of different modes of production permits a more satisfying interpretation, if accompanied by a certain number of considerations of the “upside” and “downside” of the Conquest. To this end, the argument is based on a characterization of New France in terms of the domination of the relations of production of the feudal type and on an analysis of metropolitan centres with intent to evaluate their level of capitalist development at the moment of their respective colonial penetration in Canada. The results of this approach permit one to posit the existence of a single-class structure, characterized principally by the existence of elements connecting diverse modes and forms of production, whose origin reflects the unequal state of economic development in the two metropolitan centres.The empirical demonstration rests on the census data of 1851–1852 and on the complementary information drawn from the works of historians.

scholarly journals One-relator groups and algebras related to polyhedral products

2021 ◽  
pp. 1-20
Author(s):  
Jelena Grbić ◽  
George Simmons ◽  
Marina Ilyasova ◽  
Taras Panov
Keyword(s):  
Homology Group ◽  
Homotopy Theory ◽  
Commutator Subgroup ◽  
Homology Groups ◽  
Homological Characterization ◽  
One Relator Groups ◽  
Combinatorial Condition ◽  
The Moment ◽  
Necessary And Sufficient

We link distinct concepts of geometric group theory and homotopy theory through underlying combinatorics. For a flag simplicial complex $K$ , we specify a necessary and sufficient combinatorial condition for the commutator subgroup $RC_K'$ of a right-angled Coxeter group, viewed as the fundamental group of the real moment-angle complex $\mathcal {R}_K$ , to be a one-relator group; and for the Pontryagin algebra $H_{*}(\Omega \mathcal {Z}_K)$ of the moment-angle complex to be a one-relator algebra. We also give a homological characterization of these properties. For $RC_K'$ , it is given by a condition on the homology group $H_2(\mathcal {R}_K)$ , whereas for $H_{*}(\Omega \mathcal {Z}_K)$ it is stated in terms of the bigrading of the homology groups of $\mathcal {Z}_K$ .

scholarly journals Synthesis, Characterization of a New Polyacrylic Acid Superabsorbent, Some Heavy Metal Ion Sorption, the Adsorption Isotherms, and Quantum Chemical Investigation

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4390
Author(s):  
Sevil Savaskan Yilmaz ◽  
Nuri Yildirim ◽  
Murat Misir ◽  
Yasin Misirlioglu ◽  
Emre Celik
Keyword(s):  
Heavy Metal ◽  
Quantum Chemical ◽  
Metal Ion ◽  
Molecular Mechanic ◽  
Ion Concentration ◽  
Heavy Metal Ion ◽  
Competitive Sorption ◽  
Cross Linker ◽  
The Cross

Poly(acrylic acid/Kryptofix 23-Dimethacrylate) superabsorbent polymer [P (AA/Kry23-DM) SAP] was synthesized by solution polymerization to remove Co, Ni, Cu, Cd, Mn, Zn, Pb, Cr, and Fe ions in water and improve the quality of the water. Kry23-DM cross-linker (1,4,7,13,16-Pentaoxa-10,19 diazo cyclohexene icosane di methacrylate) was synthesized using Kry23 and methacryloyl chloride. The characterization of the molecules was done by FTIR, TGA, DSC, and SEM techniques. The effects of parameters such as pH, concentration, and the metal ion interaction on the heavy metal ions uptaking of SAP was investigated. It was observed that P (AA/Kry23-DM) SAP has maximum water absorption, and the absorption increases with the pH increase. Adsorption rates and sorption capacity, desorption ratios, competitive sorption (qcs), and distribution coefficient (log D) of P(AA/Kry23-DM) SAP were studied as a function of time and pH with the heavy metal ion concentration. Langmuir and Freundlich isotherms of the P (AA/Kry23-DM) SAP were investigated to verify the metal uptake. Molecular mechanic (MM2), Assisted Model Building with Energy Refinement (AMBER), and optimized potentials for liquid simulations (OPLS) methods. were used in quantum chemical calculations for the conformational analysis of the cross-linker and the SAP. ΔH0f calculations of the cross-linker and the superabsorbent were made using Austin Model 1(AM1) method.

scholarly journals Preliminary Characterization of Wild Grapevine Populations (Vitis vinifera ssp. sylvestris) Grown Along the Danube River

2013 ◽  
Vol 41 (2) ◽  
pp. 472 ◽  
Author(s):  
Carmen F. POPESCU ◽  
Liviu C. DEJEU ◽  
Rafael R. OCETE
Keyword(s):  
Vitis Vinifera ◽  
Morphological Analysis ◽  
Danube River ◽  
Vitis Vinifera L ◽  
Meristematic Tissue ◽  
The Danube River ◽  
Wild Grapevine ◽  
The Moment

The individuals belonging to three different groups of wild grapevines populations Vitis vinifera L. ssp. sylvestris (Gmelin) Hegi harvested along, or near the Danube River, were described by means of usual ampelographic methods. The twenty standardized descriptors used for morphological analysis revealed obvious differentiation among analyzed populations. Out of 65 individuals, a half produced flowers with separate sex and a high proportion of them were males (70%). Pollen measurements on light microscope provided information on differences in pollen size among inside wild grapevine populations of V. sylvestris with the polar length varying between 15.3 and 23 μm and the equatorial length between 15.5 and 24.4μm. The in vitro regenerative potential from meristematic tissue tested with each phenotype showed that the moment of differentiation, the aspect of proliferative structures and the rate of multiplication varied inside these wild grapevine populations, without any correlation with the location of harvesting. Our results provided valuable information about these Vitis vinifera ssp. sylvestris populations, possible to be used as starting plant material for research in general and further breeding of cultivars and grapevine rootstocks.

scholarly journals Preliminary magnetic resonance relaxometric analysis of Fricke gel dosimeters produced with polyvinyl alcohol and glutaraldehyde

2017 ◽  
Vol 32 (3) ◽  
pp. 242-249 ◽  
Author(s):  
Salvatore Gallo ◽  
Giorgio Collura ◽  
Giuseppina Iacoviello ◽  
Anna Longo ◽  
Luigi Tranchina ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Polyvinyl Alcohol ◽  
Dose Range ◽  
Relaxation Times ◽  
Ion Concentration ◽  
Nuclear Magnetic Resonance Relaxometry ◽  
New Formulation ◽  
Nuclear Magnetic

This work describes the preliminary analysis of Fricke gels dosimeters characterized by a new formulation making use of a matrix of polyvinyl alcohol cross-linked by adding glutaraldehyde and analyzed by means of nuclear magnetic resonance relaxometry. In previous optical studies, these gels have shown promising dosimetric features in terms of photon sensitivity and low diffusion of ferric ions produced after irradiation. In this work, we used a portable nuclear magnetic resonance relaxometer to measure the relaxation times (which are important for dosimetric applications) of these gel materials. For this purpose, we performed a study for optimizing the acquisition parameters with a nuclear magnetic resonance relaxometer. Gel samples were exposed to clinical 6 MV photons in the dose range between 0 and 20 Gy. Nuclear magnetic resonance relaxometry measurements were per- formed and the sensitivity to photon beams was measured for various values of the Fe2+ ion concentration. The analyses pointed out that the MR signal increases as the Fe2+ content in- creases and the increase is about 75 % when the concentration of Fe2+ ions is increased from 0.5 mM to 2.5 mM. Furthermore, the sensitivity improvement achieved with increasing the Fe2+ concentration is about 60 %. This paper shows that the portable nuclear magnetic resonance relaxometer used for analysis of porous materials can be used for characterization of these dosimetric gels and this study can be considered as the first step for the characterization of these dosimeters which in future could be used for 3-D dose mapping in clinical applications.

The Scope of the Conceptual

2012 ◽  
Author(s):  
Stephen Laurence ◽  
Eric Margolis
Keyword(s):  
Natural Language ◽  
Social Practice ◽  
Donald Davidson ◽  
Human Beings ◽  
Conceptual Content ◽  
Michael Dummett ◽  
Contemporary Philosopher ◽  
Conceptual Thought ◽  
The Moment

This article explains different views on concepts, which are among the most fundamental constructs in cognitive science. Michael Dummett argues that nonhuman animals are not capable of full-fledged conceptual thought but only a diminished form of thought, which he calls, proto-thought. Human beings can remove themselves from the moment and can rise above the confined world of current perceptions because of their linguistic abilities. Donald Davidson, a contemporary philosopher, denies that animals are capable of conceptual thought and claim that conceptual content requires a rich inferential network. Donald Davidson made an argument against animals having conceptual thought. Davidson's original formulation of the argument begins with the claim that having a belief requires having the concept of a belief but adds that having the concept of belief requires possession of a natural language. It follows, then, that to have a belief requires facility with natural language. The characterization of the conceptual/nonconceptual distinction that is implicit in Davidson's metacognitive argument is a complex one involving a capacity for belief about beliefs, a concept of belief, and concepts of truth and falsity. Both Robert Brandom and John McDowell argued that conceptual thought requires more than a capacity for detection. They claim that conceptual thought requires the ability to appreciate the reasons that would justify a given concept's application and use, and this, in turn, is inherently a social practice that is dependent on natural language

Molecular Pathology of Breast Cancer: The Journey From Traditional Practice Toward Embracing the Complexity of a Molecular Classification

2011 ◽  
Vol 135 (5) ◽  
pp. 544-557 ◽  
Author(s):  
Aaron M. Gruver ◽  
Bryce P. Portier ◽  
Raymond R. Tubbs
Keyword(s):  
Molecular Diagnostics ◽  
Treatment Options ◽  
Molecular Classification ◽  
Published Data ◽  
Breast Carcinomas ◽  
Developing Regions ◽  
Traditional Practice ◽  
The Moment

Abstract Context.—Adenocarcinoma of the breast is the most frequent cancer affecting women in both developed and developing regions of the world. From the moment of clinical presentation until the time of pathologic diagnosis, patients affected by this disease will face daunting questions related to prognosis and treatment options. While improvements in targeted therapies have led to increased patient survival, these same advances have created the imperative to accurately stratify patients to achieve maximum therapeutic efficacy while minimizing side effects. In this evolving era of personalized medicine, there is an ever-increasing need to overcome the limitations of traditional diagnostic practice. Objective.—To summarize the molecular diagnostics traditionally used to guide prognostication and treatment of breast carcinomas, to highlight published data on the molecular classification of these tumors, and to showcase molecular assays that will supplement traditional methods of categorizing the disease. Data Sources.—A review of the literature covering the molecular diagnostics of breast carcinomas with a focus on the gene expression and array studies used to characterize the molecular signatures of the disease. Special emphasis is placed on summarizing evolving technologies useful in the diagnosis and characterization of breast carcinoma. Conclusions.—Available and emerging molecular resources will allow pathologists to provide superior diagnostic, prognostic, and predictive information about individual breast carcinomas. These advances should translate into earlier identification and tailored therapy and should ultimately improve outcome for patients affected by this disease.

Typification and taxonomic remarks of Indobanalia (Amaranthaceae) in India

Phytotaxa ◽  
2021 ◽  
Vol 513 (3) ◽  
pp. 265-270
Author(s):  
DUILIO IAMONICO ◽  
SINDHU ARYA ◽  
VENUGOPALAN NAIR SARADAMMA ANIL KUMAR
Keyword(s):  
Sri Lanka ◽  
Endemic Species ◽  
Tamil Nadu ◽  
Andhra Pradesh ◽  
Morphological Characterization ◽  
Herbarium Specimens ◽  
Peninsular India ◽  
Field Surveys ◽  
The Moment

Indobanalia thyrsiflora is an endemic species occurring in peninsular India (Andhra Pradesh, Karnataka, Kerala and Tamil Nadu States) and Sri Lanka. A nomenclatural study of the basionym Banalia thyrsiflora, published by Moquin-Tandon in Candolle’s Prodromus (year 1849), is carried out and the name is lectotypified on a specimen deposited at P (barcode P00609924); isolectotypes are traced at K and CAL. A preliminary morphological characterization of the species is also given, based on field surveys and examination of herbarium specimens. We noted that I. thyrsiflora is highly variable. However, we prefer to avoid, for the moment, taxonomic conclusions about the various morphotypes found, waiting the complete results of this ongoing morphological and molecular investigations.

VII.—A Study of the Fertilisation Membrane in the Echinoderms

1928 ◽  
Vol 47 ◽  
pp. 94-117 ◽  
Author(s):  
A. D. Hobson
Keyword(s):  
Surface Tension ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Essential Factor ◽  
Artificial Membrane ◽  
Asterias Rubens ◽  
Hydrogen Ion Concentration ◽  
Partial Activation ◽  
The Moment ◽  
Artificial Activation

Summary1. The view is confirmed that the zona pellucida is not an essential factor in the formation of the fertilisation membrane (pp. 96–100).2. Partial activation of the eggs of Asterias rubens is described with the formation of Seifriz's “protoplasmic papillæ” (pp. 100, 101).3. Artificial activation of the eggs of Asterias rubens by isotonic solutions of NaCl, KCl, CaCl2, and MgCl2 is described. It was found that decrease in surface tension is not a necessary factor in causing artificial membrane formation (pp. 102–104).4. The influence of the hydrogen ion concentration of the medium on the degree of extrusion of the fertilisation membrane of Echinus miliaris has been examined, and indicates that osmotic pressure due to the presence of a protein within the membrane is responsible for the extrusion (pp. 105–109).5. From a study of the influence of salt concentration on the extrusion of the fertilisation membrane of Echinus miliaris, it is concluded that the fertilisation membrane is, from the moment of its formation, completely permeable to salts (pp. 109–112).6. The origin of the fertilisation membrane has been examined, but in the absence of critical evidence it is concluded that the question cannot be regarded as settled (pp. 112–114).

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