scholarly journals Modification of Clays by Sol-Gel Reaction and Their Use in the EthyleneIn SituPolymerization for Obtaining Nanocomposites

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
E. Moncada ◽  
R. Quijada ◽  
P. Zapata
Keyword(s):  
Phase 1 ◽  
Sol Gel ◽  
Metallocene Catalyst ◽  
Polymerization Reaction ◽  
Second Phase ◽  
Clay Particles ◽  
Nanoparticle Morphology ◽  
Two Phases ◽  
Made In

The nanocomposites formation byin situpolymerization used a metallocene catalyst (butyl-2-cyclopentadienyl zirconium 2-chlorines) and a hectorite synthetic clay type which is discussed. This research was carried out in two phases. The first phase consisted of mixing the components of the metallocenic polymerization reaction (metallocene-methylaluminoxane-ethylene) with clay in a reactor. In the second phase, the metallocenic catalytic system was supported by clay particles and then a polymerization reaction was made. In this second phase, the clay particles were modified using a sol-gel reaction with different pH values: pH = 3, pH = 8, and pH = 12. The results were compared in terms of the catalytic activity in the different systems (phase 1 and phase 2) and the nanoparticle morphology of nanocomposites generated in this study.

LinkedIn and recruitment: how profiles differ across occupations

2014 ◽  
Vol 36 (5) ◽  
pp. 583-604 ◽  
Author(s):  
Julie Zide ◽  
Ben Elman ◽  
Comila Shahani-Denning
Keyword(s):  
New York ◽  
Social Networking Sites ◽  
Personal Information ◽  
Phase 1 ◽  
Small Sample ◽  
Research Approach ◽  
Second Phase ◽  
Content Type ◽  
Two Phases ◽  
Group Member

Purpose – The purpose of this paper is to identify the elements of a LinkedIn profile that hiring professionals focus on most, and then examine LinkedIn profiles in terms of these identified elements across different industries. Design/methodology/approach – The methodology was comprised of two phases. In the first phase, researchers interviewed hiring professionals to determine their usage of LinkedIn. In the second phase, LinkedIn group member profiles from three industries – HR, sales/marketing and industrial/organizational (I/O) psychology – were compared on the 21 variables identified in Phase 1 (n=288). Findings – χ2 and ANOVA tests showed significant differences with respect to ten of the LinkedIn variables in how people presented themselves across the three groups. There were also several gender differences found. Research limitations/implications – A general limitation was the use of a qualitative research approach. A limitation of Phase 1 was that only a small sample of New York City-based hiring professionals was interviewed. Perhaps a wider, more diverse sample would have yielded different variables. In terms of Phase 2, it is possible that just utilizing the second connections of the researchers limited the generalizability of findings. Practical implications – User unwillingness to fully complete the LinkedIn profile suggests that it may not have replaced the traditional resume yet. Sales/marketing professionals were more likely than HR and I/O psychology professionals to complete multiple aspects of a LinkedIn profile. Women were also less likely than men to provide personal information on their profiles. Originality/value – Most of the empirical research on social networking sites has focussed on Facebook, a non-professional site. This is, from the knowledge, the first study that systematically examined the manner in which people present themselves on LinkedIn – the most popular professional site used by applicants and recruiters worldwide.

scholarly journals Hierarchical Multi-User Detection for Highly Overloaded Uplink Grant-Free NOMA

2021 ◽  
Author(s):  
Shah Mahdi Hasan ◽  
Kaushik Mahata ◽  
Md Mashud Hyder
Keyword(s):  
Phase 1 ◽  
Sparse Recovery ◽  
Second Phase ◽  
Sensing Matrix ◽  
Recovery Algorithm ◽  
Spreading Sequence ◽  
Active User ◽  
Machine Type Communication ◽  
Two Phases ◽  
Limited Spectrum

Grant-Free Non Orthogonal Multiple Access (NOMA) offers promising solutions to realize uplink (UL) massive Machine Type Communication (mMTC) using limited spectrum resources, while reducing signalling overhead. Because of the sparse, sporadic activities exhibited by the user equipments (UE), the active user detection (AUD) problem is often formulated as a compressive sensing problem. In line of that, greedy sparse recovery algorithms are spearheading the development of compressed sensing based multi-user detectors (CS-MUD). However, for a given number of resources, the performance of CS-MUD algorithms are fundamentally limited at higher overloading of NOMA. To circumvent this issue, in this work, we propose a two-stage hierarchical multi-user detection framework, where the UEs are randomly assigned to some pre-defined clusters. The active UEs split their data transmission frame into two phases. In the first phase an UE uses the sinusoidal spreading sequence (SS) of its cluster. In the second phase the UE uses its own unique random SS. At phase 1 of detection, the active clusters are detected, and a reduced sensing matrix is constructed. This matrix is used in Phase 2 to recover the active UE indices using some sparse recovery algorithm. Numerical investigations validate the efficacy of the proposed algorithm in highly overloaded scenarios.

Effect of mass transport along interfaces and grain boundaries on copper interconnect degradation

2004 ◽  
Vol 812 ◽  
Author(s):  
Ehrenfried Zschech ◽  
Moritz A. Meyer ◽  
Eckhard Langer
Keyword(s):  
Mass Transport ◽  
Grain Boundaries ◽  
Void Formation ◽  
Degradation Process ◽  
Copper Interconnects ◽  
Second Phase ◽  
Copper Interconnect ◽  
Void Evolution ◽  
Two Phases

AbstractIn-situ SEM electromigration studies were performed at fully embedded via/line interconnect structures to visualize the time-dependent void evolution in inlaid copper interconnects. Void formation, growth and movement, and consequently interconnect degradation, depend on both interface bonding and copper microstructure. Two phases are distinguished for the electromigration-induced interconnect degradation process: In the first phase, agglomerations of vacancies and voids are formed at interfaces and grain boundaries, and voids move along weak interfaces. In the second phase of the degradation process, they merge into a larger void which subsequently grows into the via and eventually causes the interconnect failure. Void movement along the copper line and void growth in the via are discontinuous processes, whereas their step-like behavior is caused by the copper microstructure. Directed mass transport along inner surfaces depends strongly on the crystallographic orientation of the copper grains. Electromigration lifetime can be drastically increased by changing the copper/capping layer interface. Both an additional CoWP coating and a local copper alloying with aluminum increase the bonding strength of the top interface of the copper interconnect line, and consequently, electromigration-induced mass transport and degradation processes are reduced significantly.

scholarly journals Polypropylene Nanocomposites Obtained byIn SituPolymerization Using Metallocene Catalyst: Influence of the Nanoparticles on the Final Polymer Morphology

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Paula Zapata ◽  
Raúl Quijada
Keyword(s):  
Catalytic System ◽  
Sol Gel ◽  
Metallocene Catalyst ◽  
Particle Morphology ◽  
Polymer Particle ◽  
Silica Nanospheres ◽  
Sem Images ◽  
Transmission Electron ◽  
Polypropylene Nanocomposites

Polypropylene nanocomposites containing silica nanospheres based on the sol-gel methods were produced viain situpolymerization using a rac-Et(Ind)2ZrCl2/methylaluminoxane (MAO) system. Two different routes were used depending on the interaction between the silica nanoparticles with the catalytic system. In route 1 the nanoparticles were added together with the catalytic system (rac-Et(Ind)2ZrCl2)/(MAO) directly into the reactor, and in route 2 the metallocene rac-Et(Ind)2ZrCl2was supported on silica nanospheres pretreated with (MAO). SEM images show that when the nanospheres were added by both routes, they were replicated in the final polymer particle morphology; this phenomenon was more pronounced for PP obtained by route 2. The polypropylene (PP) nanocomposites obtained by both routes had a slightly higher percent crystallinities and crystallinity temperatures than pure PP. Transmission electron microscopy (TEM) images show that the nanospheres were well dispersed into the polypropylene matrix, particularly in the nanocomposites obtained by the support system (route 2).

scholarly journals Hospital mealtimes: action research for change?

2005 ◽  
Vol 64 (3) ◽  
pp. 269-275 ◽  
Author(s):  
Angela Dickinson ◽  
Carol Welch ◽  
Laurie Ager ◽  
Aileen Costar
Keyword(s):  
Action Research ◽  
Phase 1 ◽  
Hospital Setting ◽  
Phase Changes ◽  
Research Approach ◽  
Second Phase ◽  
Action Research Approach ◽  
Three Phase ◽  
Two Phases ◽  
Patients Experience

Poor nutritional care within the hospital setting continues despite decades of work chronicling and measuring the problems. To address the problem changes in practice have been attempted to improve the patients’ experience of mealtimes. In order to implement patient-centred mealtimes for older patients by changing the focus from institutional convenience to one that focuses on the requirements of the patients, an action research approach has been used that focuses on action and change, and thus appears to have much to offer those who seek to change practice. The present paper focuses on the first two phases in a three-phase approach. In phase one the nature of everyday mealtime care and the wider context are explored using focus groups, interviews and observations. The data fall into three main themes that all impact on patients’ experiences of mealtimes: institutional and organisational constraints; mealtime care and nursing priorities; eating environment. Following feedback of phase 1 findings to staff and identification of areas of concern a model of practice development was selected to guide the change process of the second phase. Changes to mealtime nursing practice and the ward environment have been made, indicating that action research has the potential to improve the mealtime care of patients.

scholarly journals Scientific Need for Space Astronomy

1980 ◽  
Vol 5 ◽  
pp. 63-68
Author(s):  
L. Goldberg
Keyword(s):  
High Altitude ◽  
Phase 1 ◽  
Satellite Orbit ◽  
Earth Satellite ◽  
Second Phase ◽  
National Academy Of Sciences ◽  
Space Astronomy ◽  
Small Satellites ◽  
Time Space ◽  
Two Phases

Many scientific justifications for space astronomy have been prepared by individuals and committees during the past three decades or more. The first such report that I am aware of, called “Astronomical Advantages of an Extraterrestrial Observatory”, was written by Lyman Spitzer in September 1946, and although its goals were extremely modest by today’s standards, the report did dwell with enthusiasm on the ultimate goal of a large reflecting telescope 4-6 meters in diameter with diffraction-limited optics put into earth-satellite orbit. The latest study, from which I shall quote liberally, has just been published by the Astronomy Committee of the U. S. National Academy of Sciences, and provides the scientific foundation for space astronomy in the 1980’s. Space Astronomy was initiated about one month after the date of publication of Spitzer’s report, when the first high-altitude rocket was launched to observe the sun’s ultraviolet radiation. Since that time, space astronomy has completed two phases and is about to embark on a third. In Phase 1, which lasted until the beginning of Sputnik, observations were made for a few minutes at a time from high-altitude rockets. In the second phase, which is just ending, observations were made with relatively small instruments in earth-orbiting satellites. The observing programs carried out with rockets and small satellites were called experiments because their capabilities and objectives were limited and their lifetimes were short -from a few minutes to about a year.

scholarly journals Abstract P-3: The Structure of Self-Assembled Surfactant Micellar Networks by in situ Cryo-Electron Tomography

2021 ◽  
Vol 11 (Suppl_1) ◽  
pp. S12-S12
Author(s):  
Yury Chesnokov ◽  
Andrey Shibaev ◽  
Roman Kamyshinsky ◽  
Vyacheslav Kralin ◽  
Olga Philippova ◽  
...  
Keyword(s):  
Electron Tomography ◽  
Ion Beam ◽  
Phase 1 ◽  
Persistence Length ◽  
Wormlike Micelles ◽  
Second Phase ◽  
Dense Network ◽  
Cryo Electron Tomography ◽  
Self Assembled

Background: Surfactant molecules can form various self-assembled structures in aqueous solutions, including spherical and cylindrical micelles, lamellae, vesicles, etc. Elongated cylindrical (wormlike) micelles can entangle and form a dense network. The study of the un-perturbed native structure of wormlike micelles in such networks presents a great challenge, since the micelles are formed due to weak non-covalent interactions and may easily break when external conditions are changed. In this work in situ cryo-electron tomography (cryo-ET) was applied to reveal the relaxed structure of such entangled systems. Methods: To prepare samples for the cryo-ET study 1 µl of the aqueous surfactant-containing solution was applied to the glow discharged grid, blotted with filter paper for 10 sec, drained for 60 sec to allow for the relaxation of the system and plunge-frozen with Vitrobot Mark IV. The vitrified sample was transferred to Versa 3D cryo-focused ion beam / scanning electron microscope (cryo-FIB/SEM) to prepare thin (100-150 nm) sections of the sample. Cryo-ET study was conducted using Titan Krios. IMOD and Avizo software packages were used for data processing. Results: In this work, wormlike micelles formed by a mixture of an anionic and a cationic surfactant were investigated at the excess of the anionic surfactant. Cryo-ET study of the obtained lamellae demonstrated the formation of two different phases, consisting of straight rods oriented along the grid substrate (phase 1) and isotropic network formed by wormlike micelles (phase 2) above it. The topology of the second phase corresponded to the branched saturated network or entangled network depending on cation/anion ratio of the sample. However, the analysis of the thin samples obtained without cryo-FIB demonstrated only the presence of the metastable phase (phase 1), which could lead to false conclusions regarding the morphology of the micelles. Conclusion: Here we discuss the influence of different sample preparation approaches on the sample structure and demonstrate that the native un-perturbed conformation of charged cylindrical surfactant micelles in the dense network is that of a slightly bent rod or a wormlike chain with high persistence length.

Gastric H+-K+-ATPase in situ: evidence for compartmentalization

1989 ◽  
Vol 257 (4) ◽  
pp. G539-G547
Author(s):  
S. J. Hersey ◽  
A. Perez ◽  
S. Matheravidathu ◽  
G. Sachs
Keyword(s):  
Atpase Activity ◽  
Proton Transport ◽  
Second Phase ◽  
Irreversible Inhibitor ◽  
Gastric Glands ◽  
Dependent Component ◽  
Gradient Formation ◽  
Orange Fluorescence ◽  
Two Phases

Gastric glands, isolated from rabbit, were permeabilized with digitonin to permit measurement of H+-K+-adenosinetriphosphatase (ATPase) activity and proton transport in situ. Measurement of proton gradient formation using acridine orange fluorescence showed two phases of ATP-driven proton accumulation; one phase occurs spontaneously in KCl medium and one phase requires the K+ ionophore valinomycin. Valinomycin was found to increase H+-K+-ATPase activity, indicating that the second phase is because of increased proton transport rather than a decrease in proton leak rate. The acid-activated, irreversible inhibitor, omeprazole, was used to selectively eliminate the H+-K+-ATPase molecules associated with the spontaneous component of proton transport. After omeprazole treatment a residual, valinomycin-dependent component of proton transport could be demonstrated. These results are interpreted as evidence for two compartments of H+-K+-ATPase, separated by a barrier that prevents K+ diffusion and pH equilibration. The two compartments may be separated also on the basis of anion selectivity. The spontaneously active compartment was found to be functional with various anions, including sulfate and isethionate, whereas the valinomycin-dependent component is highly selective for chloride. The proportion of H+-K+-ATPase that exists in each compartment was quantitated by measuring the fraction of total ATPase activity that could be inhibited by omeprazole in the absence and presence of valinomycin. For glands that were preconditioned with cimetidine, approximately 30% of the inhibitable enzyme was found associated with the spontaneous compartment, and this fraction increased to approximately 70% with histamine preconditioning.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Succession of Internal Sulfur Cycles and Sulfur-Oxidizing Bacterial Communities in Microaerophilic Wastewater Biofilms

2005 ◽  
Vol 71 (5) ◽  
pp. 2520-2529 ◽  
Author(s):  
Satoshi Okabe ◽  
Tsukasa Ito ◽  
Kenichi Sugita ◽  
Hisashi Satoh
Keyword(s):  
In Situ Hybridization ◽  
Sulfur Cycle ◽  
Rrna Gene ◽  
Second Phase ◽  
Sulfate Reducing ◽  
Sulfur Oxidizing ◽  
Reducing Activity ◽  
Two Phases ◽  
Microelectrode Measurements

ABSTRACT The succession of sulfur-oxidizing bacterial (SOB) community structure and the complex internal sulfur cycle occurring in wastewater biofilms growing under microaerophilic conditions was analyzed by using a polyphasic approach that employed 16S rRNA gene-cloning analysis combined with fluorescence in situ hybridization, microelectrode measurements, and standard batch and reactor experiments. A complete sulfur cycle was established via S0 accumulation within 80 days in the biofilms in replicate. This development was generally split into two phases, (i) a sulfur-accumulating phase and (ii) a sulfate-producing phase. In the first phase (until about 40 days), since the sulfide production rate (sulfate-reducing activity) exceeded the maximum sulfide-oxidizing capacity of SOB in the biofilms, H2S was only partially oxidized to S0 by mainly Thiomicrospira denitirificans with NO3 − as an electron acceptor, leading to significant accumulation of S0 in the biofilms. In the second phase, the SOB populations developed further and diversified with time. In particular, S0 accumulation promoted the growth of a novel strain, strain SO07, which predominantly carried out the oxidation of S0 to SO4 2− under oxic conditions, and Thiothrix sp. strain CT3. In situ hybridization analysis revealed that the dense populations of Thiothrix (ca. 109 cells cm−3) and strain SO07 (ca. 108 cells cm−3) were found at the sulfur-rich surface (100 μm), while the population of Thiomicrospira denitirificans was distributed throughout the biofilms with a density of ca. 107 to 108 cells cm−3. Microelectrode measurements revealed that active sulfide-oxidizing zones overlapped the spatial distributions of different phylogenetic SOB groups in the biofilms. As a consequence, the sulfide-oxidizing capacities of the biofilms became high enough to completely oxidize all H2S produced by SRB to SO4 2− in the second phase, indicating establishment of the complete sulfur cycle in the biofilms.

scholarly journals Hierarchical Multi-User Detection for Highly Overloaded Uplink Grant-Free NOMA

2021 ◽  
Author(s):  
Shah Mahdi Hasan ◽  
Kaushik Mahata ◽  
Md Mashud Hyder
Keyword(s):  
Phase 1 ◽  
Sparse Recovery ◽  
Second Phase ◽  
Sensing Matrix ◽  
Recovery Algorithm ◽  
Spreading Sequence ◽  
Active User ◽  
Machine Type Communication ◽  
Two Phases ◽  
Limited Spectrum

Grant-Free Non Orthogonal Multiple Access (NOMA) offers promising solutions to realize uplink (UL) massive Machine Type Communication (mMTC) using limited spectrum resources, while reducing signalling overhead. Because of the sparse, sporadic activities exhibited by the user equipments (UE), the active user detection (AUD) problem is often formulated as a compressive sensing problem. In line of that, greedy sparse recovery algorithms are spearheading the development of compressed sensing based multi-user detectors (CS-MUD). However, for a given number of resources, the performance of CS-MUD algorithms are fundamentally limited at higher overloading of NOMA. To circumvent this issue, in this work, we propose a two-stage hierarchical multi-user detection framework, where the UEs are randomly assigned to some pre-defined clusters. The active UEs split their data transmission frame into two phases. In the first phase an UE uses the sinusoidal spreading sequence (SS) of its cluster. In the second phase the UE uses its own unique random SS. At phase 1 of detection, the active clusters are detected, and a reduced sensing matrix is constructed. This matrix is used in Phase 2 to recover the active UE indices using some sparse recovery algorithm. Numerical investigations validate the efficacy of the proposed algorithm in highly overloaded scenarios.

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