scholarly journals Catalysis by Metallic Nanoparticles in Solution: Thermosensitive Microgels as Nanoreactors

2018 ◽  
Vol 232 (5-6) ◽  
pp. 773-803 ◽  
Author(s):  
Rafael Roa ◽  
Stefano Angioletti-Uberti ◽  
Yan Lu ◽  
Joachim Dzubiella ◽  
Francesco Piazza ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Kinetic Data ◽  
Metallic Nanoparticles ◽  
Cold Water ◽  
Volume Transition ◽  
Polymeric Carriers ◽  
Salient Points ◽  
The Subject ◽  
Work Done ◽  
Colloidal Carrier

Abstract Metallic nanoparticles have been used as catalysts for various reactions, and the huge literature on the subject is hard to overlook. In many applications, the nanoparticles must be affixed to a colloidal carrier for easy handling during catalysis. These “passive carriers” (e.g. dendrimers) serve for a controlled synthesis of the nanoparticles and prevent coagulation during catalysis. Recently, hybrids from nanoparticles and polymers have been developed that allow us to change the catalytic activity of the nanoparticles by external triggers. In particular, single nanoparticles embedded in a thermosensitive network made from poly(N-isopropylacrylamide) (PNIPAM) have become the most-studied examples of such hybrids: immersed in cold water, the PNIPAM network is hydrophilic and fully swollen. In this state, hydrophilic substrates can diffuse easily through the network, and react at the surface of the nanoparticles. Above the volume transition located at 32°C, the network becomes hydrophobic and shrinks. Now hydrophobic substrates will preferably diffuse through the network and react with other substrates in the reaction catalyzed by the enclosed nanoparticle. Such “active carriers”, may thus be viewed as true nanoreactors that open new ways for the use of nanoparticles in catalysis. In this review, we give a survey on recent work done on these hybrids and their application in catalysis. The aim of this review is threefold: we first review hybrid systems composed of nanoparticles and thermosensitive networks and compare these “active carriers” to other colloidal and polymeric carriers (e.g. dendrimers). In a second step we discuss the model reactions used to obtain precise kinetic data on the catalytic activity of nanoparticles in various carriers and environments. These kinetic data allow us to present a fully quantitative comparison of different nanoreactors. In a final section we shall present the salient points of recent efforts in the theoretical modeling of these nanoreactors. By accounting for the presence of a free-energy landscape for the reactants’ diffusive approach towards the catalytic nanoparticle, arising from solvent-reactant and polymeric shell-reactant interactions, these models are capable of explaining the emergence of all the important features observed so far in studies of nanoreactors. The present survey also suggests that such models may be used for the design of future carrier systems adapted to a given reaction and solvent.

Two Models of Public Opinion: Bacon's ‘New Logic’ and Diotima's ‘Tale of Love’ (The Prothero Lecture)

1974 ◽  
Vol 24 ◽  
pp. 79-96
Author(s):  
Samuel H. Beer
Keyword(s):  
United States ◽  
Public Policy ◽  
Eighteenth Century ◽  
Public Opinion ◽  
Theoretical Approach ◽  
Democratic Theory ◽  
The United States ◽  
Representative Government ◽  
The Subject ◽  
Work Done

It is appropriate that an American should address himself to the subject of public opinion. For, in terms of quantity, Americans have made the subject peculiarly their own. They have also invested it with characteristically American concerns. Most of the work done on the subject in the United States is oriented by a certain theoretical approach. This approach is democratic and rationalist. Both aspects create problems. In this paper I wish to play down the democratic problem, viz., how many of the voters are capable of thinking sensibly about public policy, and emphasize rather the difficulties that arise from modern rationalism. Here I take a different tack from most historians of the concept of public opinion, who, taking note of the origin of the term in the mid-eighteenth century, stress its connection with the rise of representative government and democratic theory.

scholarly journals The Kodak research laboratories

1948 ◽  
Vol 135 (879) ◽  
pp. 133-147
Keyword(s):  
New York ◽  
Research Laboratory ◽  
New Materials ◽  
General Electric Company ◽  
Electric Company ◽  
Light Filters ◽  
University College London ◽  
The Subject ◽  
Work Done ◽  
Dark Room

In 1880 George Eastman commenced the manufacture and sale of gelatin photographic dry plates in Rochester, New York. From that undertaking, the Eastman Kodak Company, incorporated as an American company in 1902, has developed. In 1912 Mr Eastman decided to organize a laboratory, independent of the factory laboratories, which should carry out work on both the science and practice of photography. He was influenced by his observation of the success of industrial research under Dr Whitney’s direction at the research laboratory of the General Electric Company in Schenectady, New York, U. S. A. and of the laboratories of the great German dye works. He had been particularly impressed by the work done by the Bayer Company at Elberfeld. In 1906 I had completed my thesis for the doctorate of science at University College, London, the subject being the theory of the photographic process, and had joined the old-established but very small firm of Wratten and Wainwright, Ltd., of Croydon as joint managing director. At Croydon both the conduct of research on photography and its application to the manufacture of photographic materials were continued actively, so that by 1912 many new materials had been introduced, especially panchromatic plates and the light filters and dark-room safe-lights required for their use; and the little firm was flourishing.

scholarly journals Some Problems of Perspective Planning in Pakistan

1964 ◽  
Vol 4 (2) ◽  
pp. 193-202
Author(s):  
Said Hasan
Keyword(s):  
Policy Making ◽  
Time Horizon ◽  
Close Relation ◽  
The Third ◽  
Preceding Period ◽  
The Subject ◽  
Perspective Planning ◽  
Economic Future ◽  
Work Done

The growing confidence of Pakistan's planners in the nation's economic future is indicated by the boldness of their successive plans and by the lengthening of their time horizon. As far as the latter is concerned, the First Five-Year Plan did not reflect any thinking on economic and social development beyond a specific five-year period; the Second Plan, however, contained some remarks on long-term growth; the Third Plan is being prepared in close relation to the work being done on the Perspective Plan. What fifteen years ago would have been regarded as a waste of time is now considered to be of basic import¬ance for sound planning. What nobody dared think about in the earlier days is now the subject of serious analysis and policy-making. The need for a Perspective Plan is there not only from an economic angle but there are also sound political reasons for it. From the economic angle, we realized that the five-year periods chosen for our plans are only arbitrary periods in a process stretching over a much longer time. Our decisions and policies during one plan influence the pattern of growth in the next one, and influence also the effectiveness of established policies. Therefore, any particular five-year plan has to be part of a whole chain of plans, all fitting together and building further on the work done in the preceding period.

scholarly journals Objektivnost različitih načina procjenjivanja školskih pisanih zadaća

2018 ◽  
Vol 29 (6) ◽  
Author(s):  
Tomislav Grgin ◽  
Bogdana Marinković
Keyword(s):  
Middle School ◽  
Third Graders ◽  
School Work ◽  
The Third ◽  
School Subjects ◽  
The Subject ◽  
Work Done

The investigation was conducted In order to evaluate the objecitivily of the three ways of grading school work: classical way which is used most in schools, then grading with the help of "standard notebook" lor the grade "C" and the grading of work comparatively in pairs. The subject of evaluation was the school work of the third-graders in middle school. Subjects were history and biology, The independent graders were the teachers of these subjects from different middle schools.The results showed that all of these ways of grading do not ensure the same objectivity of grades. The least objective is the classical way, more reliable is one with "standard notebook" and relatively most reliable is the comparison of school work done in pairs.

scholarly journals Smart Advisor: An Intelligent Inventory Prediction Based On Regression Model

2018 ◽  
Vol 2 (3) ◽  
pp. 86-94
Author(s):  
Ömer Küçük ◽  
Farzad Kiani
Keyword(s):  
Regression Model ◽  
Inventory Management ◽  
Raw Material ◽  
Accurate Estimation ◽  
Stock Management ◽  
Accurate Analysis ◽  
Academic Literature ◽  
For Profit ◽  
The Subject ◽  
Work Done

Today one of the biggest expense items of the enterprises is raw material and stock amounts. Therefore, proper inventory management is very important for the profitability of the enterprises. Products that are not purchased on time cause interruptions in production and products left over because the expiration date has passed will also cause losses for businesses. Therefore, proper inventory management is critical for profit / loss situations of businesses. In this paper we presented a model to predict the demand of certain stock items by using a regression model. Our model can analysis and computer the prediction results on agiven dataset. We evaluate our model on sample dataset and provide the analysis as well calculations over the existing inventory. Accurate analysis of stock consumption enables accurate estimation of the amount of stock to be consumed in the future. Accurate forecasting of stock consumption helps to take corrective steps in decision making. That is, it only allows you to buy in sufficient quantity when necessary. These stages are critical for economic stock management. For this reason, robust and adaptable approaches that can provide models ensure that stock consumption can be managed properly. It is difficult to find previously written sources on estimating the direction of stock movements. One of the most important reasons for this is the lack of incentive to make such studies in the academic literature. As a result, articles written about the subject and the work done have been limited, the results have not reached the reproducible level.

scholarly journals Evaluación y desarrollo de la competencia digital de futuros maestros en la Universidad de Murcia

2016 ◽  
Vol 6 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Isabel Gutiérrez Porlán ◽  
José Luis Serrano Sánchez
Keyword(s):  
First Year ◽  
Self Perception ◽  
Initial Task ◽  
Initial Questionnaire ◽  
The Subject ◽  
Digital Competencies ◽  
Faculty Of Education ◽  
The One ◽  
The University ◽  
Work Done

<p class="AbstractText">This paper presents the findings of a study carried out in the academic year 2014-2015 at the faculty of Education of the University of Murcia with first year degree students in Primary Education studying Research and ICT. The study started with the application of the DIGCOM questionnaire to analyze the digital competences of 134 students. The questionnaire served as an initial task to help students reflect on their digital competences. The subject was developed around tasks which adopted a transversal approach and used the nature of the contents itself to direct and improve students’ digital competencies. Finally, the initial questionnaire was reformulated and run in order to ascertain the students’ self-perception of their improvement in these competencies through the tasks they had performed.</p> <p class="AbstractText">Below we present the tasks carried out, the organization of each subject and the most relevant data regarding the self-perception of digital competencies of the future primary school teachers enrolled at the University of Murcia. The data reveal, on the one hand, that the students participating consider themselves to be competent in the most basic aspects of digital competencies and, on the other, their perception that the work done in the subject has helped them quite a lot in improving their competencies.</p>

Closed-Cycle OTEC Systems

1994 ◽  
Author(s):  
William H. Avery ◽  
Chih Wu
Keyword(s):  
Thermal Equilibrium ◽  
Constant Pressure ◽  
Cold Water ◽  
Heat Engine ◽  
Heat Removal ◽  
Working Fluid ◽  
Closed Cycle ◽  
Work Done ◽  
Heat Engine Cycle ◽  
Design Pressure

The Rankine closed cycle is a process in which beat is used to evaporate a fluid at constant pressure in a “boiler” or evaporator, from which the vapor enters a piston engine or turbine and expands doing work. The vapor exhaust then enters a vessel where heat is transferred from the vapor to a cooling fluid, causing the vapor to condense to a liquid, which is pumped back to the evaporator to complete the cycle. A layout of the plantship shown in Fig. 1-2. The basic cycle comprises four steps, as shown in the pressure-volume (p—V) diagram of Fig. 4-1. 1. Starting at point a, heat is added to the working fluid in the boiler until the temperature reaches the boiling point at the design pressure, represented by point b. 2. With further heat addition, the liquid vaporizes at constant temperature and pressure, increasing in volume to point c. 3. The high-pressure vapor enters the piston or turbine and expands adiabatically to point d. 4. The low-pressure vapor enters the condenser and, with heat removal at constant pressure, is cooled and liquefied, returning to its original volume at point a. The work done by the cycle is the area enclosed by the points a,b,c,d,a. This is equal to Hc–Hd, where H is the enthalpy of the fluid at the indicated point. The heat transferred in the process is Hc–Ha Thus the efficiency, defined as the ratio of work to heat used, is: . . . efficiency(η)=Hc–Hd/Hc–Ha (4.1.1) . . . Carnot showed that if the heat-engine cycle was conducted so that equilibrium conditions were maintained in the process, that the efficiency was determined solely by the ratio of the temperatures of the working fluid in the evaporator and the condenser. . . . η=TE–Tc/TE (4.1.2) . . . The maximum Carnot efficiency can be attained only for a cycle in which thermal equilibrium exists in each phase of the process; however, for power to be generated a temperature difference must exist between the working fluid in the evaporator and the warm-water heat source, and between the working fluid in the condenser and the cold-water heat sink.

A Proposed Template for the Evaluation of Web Design Strategies

2009 ◽  
pp. 293-317 ◽  
Author(s):  
Dimitrios Xanthidis ◽  
David Nicholas ◽  
Paris Argyrides
Keyword(s):  
Web Sites ◽  
Web Site ◽  
Web Design ◽  
International Literature ◽  
Design Strategies ◽  
The World ◽  
The Subject ◽  
Work Done ◽  
The Web

This chapter is the result of a two years effort to design a template aiming at standardizing, as much as such a task is feasible, the evaluation of Web sites. It is the product of a few publications in international conferences and journals. A thorough review of the international literature on the subject led the authors to conclude there is a very large number of opinions, thoughts and criteria from different professionals involved, directly or indirectly, with the process of designing a good Web site. To make matters even more complicated there are a number of different terms used by various scholars, scientists and professionals around the world that often refer to similar, if not the same, attributes of a Web site. However, it seems that all these differences could boil down to a systematic approach, here called evaluation template, of 53 points that the design strategies of the Web sites should be checked against. This template was tested on a significant number (232) of Web sites of Greek companies and proved it can be used to evaluate the quality of Web sites not only by technology experts but by non-experts alike. The evaluation template, suggested here, is by no means the solution to the problem of standardizing the process of evaluating a Web site but looking at other work done on the subject worldwide it is a step ahead.

scholarly journals Design of a dry inorganic substances dispenser

2019 ◽  
Vol 126 ◽  
pp. 00012
Author(s):  
Dmitry A. Filippov ◽  
Arkadiy V. Moiseev
Keyword(s):  
Technological Process ◽  
Patent Analysis ◽  
Optimal Flow ◽  
Inorganic Substances ◽  
Main Tendency ◽  
The Subject ◽  
Work Done

The article is devoted to the introduction of dry inorganic substances, mixtures, complex solids on field surface or on the object of treatment by a universal dispenser. The article has a research character which is expressed in the fact that the analysis of methods and means for the introduction of dry inorganic substances as well as extracts from the works of leading scientists on the subject are given, promising scientific developments in the form of patent analysis which provide optimal flow of the technological process are shown, their shortcomings and solutions to these problems are pointed. There was justified the main tendency of development of dispensers and improvement of their designs for advancing the quality rates of their work. Also, there was shown the type of the proposed design, its description and the flow of the technological process. As a result of the work done, there was obtained the design of the dispenser of dry inorganic substances with proposed working elements. The conclusions set out the main results achieved so far.

scholarly journals Mechanistic Study of Silane Alcoholysis Reactions with Self-Assembled Monolayer-Functionalized Gold Nanoparticle Catalysts

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 908
Author(s):  
Katsuhiro Isozaki ◽  
Tomoya Taguchi ◽  
Kosuke Ishibashi ◽  
Takafumi Shimoaka ◽  
Wataru Kurashige ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Metallic Nanoparticles ◽  
Molecular Structures ◽  
Critical Parameters ◽  
Mechanistic Study ◽  
Self Assembled Monolayer ◽  
Mechanistic Investigation ◽  
Self Assembled ◽  
20 Nm ◽  
Silane Alcoholysis

The self-assembled monolayer (SAM)-modified metallic nanoparticles (MNPs) often exhibit improved chemoselectivity in various catalytic reactions by controlling the reactants’ orientations adsorbed in the SAM; however, there have been a few examples showing that the reaction rate, i.e., catalytic activity, is enhanced by the SAM-modification of MNP catalysts. The critical parameters that affect the catalytic activity, such as the supports, nanoparticle size, and molecular structures of the SAM components, remain uninvestigated in these sporadic literature precedents. Here, we report the mechanistic investigation on the effects of those parameters on the catalytic activity of alkanethiolate SAM-functionalized gold nanoparticles (AuNPs) toward silane alcoholysis reactions. The evaluation of the catalytic reaction over two-dimensionally arrayed dodecanethiolate SAM-functionalized AuNPs with different supports revealed the electronic interactions between AuNPs and the supports contributing to the rate enhancement. Additionally, an unprecedented size effect appeared—the AuNP with a 20 nm radius showed higher catalytic activity than those at 10 and 40 nm. Infrared reflection–absorption spectroscopy revealed that the conformational change of alkyl chains of the SAM affects the entrapment of reactants and products inside the SAM, and therefore brings about the acceleration effect. These findings provide a guideline for further applying the SAM-functionalization technique to stereoselective organic transformations with designer MNP catalysts.

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