scholarly journals Opposing Effects of Additives in Dry Milling and Tableting of Organic Particles

Pharmaceutics ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1434
Author(s):  
Lina Miethke ◽  
Paul Prziwara ◽  
Jan Henrik Finke ◽  
Sandra Breitung-Faes
Keyword(s):  
Fine Particles ◽  
Material Behavior ◽  
Process Efficiency ◽  
Disperse Flow ◽  
Positive Effects ◽  
Surface Energies ◽  
Grinding Aids ◽  
Powder Properties ◽  
Opposing Effects ◽  
Ground Material

Applying additives and excipients during the dry processing of fine particles is a common measure to control the particle–particle interactions, to specifically influence the powder properties and to enhance the process efficiency or product quality. In this study, the impacts of a particulate lubricant, a nano-disperse flow additive and liquid grinding aids on the dry fine milling and subsequent tableting of the ground material were investigated for three different organic model compounds. It is presented that the three additive classes cause varying and partly opposing effects during these process steps. Especially the lubricant and the grinding aids were shown to increase the efficiency of the milling process as well as the product fineness of the ground material, and to avoid critical product adhesions on the machine surfaces. Thereby, stable and efficient grinding conditions were partially not possible without the addition of such additives. However, as these positive effects are attributed to a reduction of the adhesive forces between the particles, much lower tablet strengths were achieved for these additives. This propagation of powder, and in turn, final product properties over whole process chains, has not been studied in detail so far. It was further revealed that the material behavior and the microstructure of the product particles is decisive for the processing as well, which is why additive effects may be product-specific and can even be suppressed under certain processing conditions. In comparison to the process performances, the powder properties and surface energies of the product particles were less influenced by the additives. On the contrary, particle-based morphologies or deformation behavior seem to play a major role in comparison to inorganic materials. Thus, it can be stated that global bulk properties and surface energies provide first indications of powder behavior and susceptibility. However, additional specific properties need to be evaluated to more clearly understand the influences of additives.

Creating in the Crucibles of Nature’s Fury: Associational Diversity and Local Social Entrepreneurship after Natural Disasters in California, 1991–2010

2016 ◽  
Vol 62 (3) ◽  
pp. 443-483 ◽  
Author(s):  
Sunasir Dutta
Keyword(s):  
Natural Disasters ◽  
Human Services ◽  
Racial Diversity ◽  
Aggregate Size ◽  
Organizational Challenges ◽  
Positive Effects ◽  
Collective Goods ◽  
Negative Effect ◽  
Human Services Organizations ◽  
Opposing Effects

This paper examines foundings of human services organizations after natural disasters such as floods, earthquakes, wildfires, hurricanes, and tsunamis and explains why only some communities bounce back by founding appropriate collective-goods organizations. Using natural disasters in California counties from 1990 to 2010 as shocks that exogenously impose a need for collective goods over and above the level endogenous to the community, this paper shows that a geographic community’s local organizing capacity rests on the richness of its repertoire of voluntary organizing models as reflected in the diversity of its voluntary associations. Such diversity is even more critical when the type of natural disaster is more unexpected or complex (e.g., both a wildfire and an earthquake) in an area, and the organizational challenges posed are thus more novel for the community. Associational diversity has positive effects on both the numbers and aggregate size of foundings of local (non-branch, secular) human services organizations, and the effects are generalizable to other endogenous demand conditions such as poverty. Results also show how different kinds of variety can have opposing effects on organizing capacity after a disaster, with associational diversity having a positive effect, political diversity having a negative effect, and racial diversity having no significant effect, net of other factors. The paper concludes with a call for treating community resilience as a matter of enhancing local organizing capacity over centralized planning efforts when the environment is rapidly changing.

Study on Grinding Aids of Different Organic Group

2012 ◽  
Vol 476-478 ◽  
pp. 1702-1708
Author(s):  
Hai Yan Lin ◽  
Yong Fu Yang ◽  
Yu Jiang Wang
Keyword(s):  
Particle Size Analysis ◽  
Absorption Capacity ◽  
Repulsive Force ◽  
Hydroxyl Group ◽  
Size Analysis ◽  
Cement Pastes ◽  
Organic Group ◽  
Grinding Aids ◽  
Monohydric Alcohols ◽  
Powder Properties

Organic substances containing hydroxyl group and alcohol amine group were chosen in this paper and the effects of different organic group on powder properties and physical performance of cement pastes were studied using various methods of analysis, such as particle size analysis, fluidness analysis and XRD. The results show that monohydric alcohols have a neglectable aid-grinding effect. For Polyhydric alcohols and ethanol amine, the absorption capacity of the hydroxyl group or amido on the surface of the powder may increase in relation to the increase in groups, which can increase fineness but cannot improve the fluidity. For Diethanolamine and Triethanolamine, the absorption on the powder mainly depends on the hydroxyl group, but the amido has a strong electrostatic repulsive force, so the dispersion of the powder not only comes from high steric hindrance effect, but also the electrostatic repulsive force, which can improve the powder’s dispersity, reduce sieve residue and increase the fluidity. This research paper provides a theoretical guide for the application of grinding aids.

Effect of Grinding Aids on the Particles Characteristics of Cement and Analysis of Action Mechanism

2014 ◽  
Vol 936 ◽  
pp. 1404-1408
Author(s):  
Ji Hui Zhao ◽  
Dong Min Wang ◽  
Xue Guang Wang ◽  
Shu Cong Liao ◽  
Hui Lin
Keyword(s):  
Particle Size ◽  
Lattice Distortion ◽  
Fine Particles ◽  
Particle Morphology ◽  
Angle Of Repose ◽  
Chemical Bonds ◽  
Action Mechanism ◽  
Grinding Aids ◽  
Grinding Mechanism ◽  
Grinding Time

Effects of triethanolamine grinding aids on the angle of repose, fineness, particle morphology and particle size distribution of cement are studied, and the action mechanism of grinding aids is discussed by surface tension and Zeta potential. The results show that the powder fluidity and particle circularity of cement are improved and the particle size and grinding time of cement are effectively reduced by grinding aids. And Grinding aids improve the particles content in the range of 3-32μm particle size by 6.63% and promote destruction of the chemical bonds and lattice distortion of cement mineral during the grinding process. The dispersion grinding mechanism of grinding aids is that they can reduce the surface free energy of powder to prevent fine particles from closing each other and shield or neutralize the particles surface partial charge to prevent facture surface from healing and promoting the cracks to extend easily.

Abstract 15547: Sfrp2 Mediates Ipsc to Cardiomyocyte Differentiation via Competing Actions on Wnts

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Ying-chang Hsueh ◽  
Conrad Hodgkinson ◽  
Richard E Pratt ◽  
Victor J Dzau
Keyword(s):  
Ips Cells ◽  
Cardiomyocyte Differentiation ◽  
Blocking Antibody ◽  
Positive Effects ◽  
Wnt Proteins ◽  
Induced Pluripotent ◽  
Opposing Effects ◽  
Blocking Antibodies

Induced pluripotent stem (iPS) cells provide a novel avenue to investigate how precursors differentiate into cardiomyocytes. In this study we examined our hypothesis that iPS differentiation is regulated by a balance between cardiogenic and inhibitory Wnt proteins. Recently, we have discovered that iPS cells differentiate into cardiomyocytes in response to Sfrp2 (control: 0% cardiomyocytes; Sfrp2 treated: 25% cardiomyocytes. N=3. P<0.01). Since Sfrp2 mediates its effects by binding to Wnt proteins, we hypothesized that Sfrp2 promotes cardiomyocyte differentiation by binding to a Wnt that prevents iPS cells from differentiating into cardiomyocytes. To identify the inhibitory Wnt protein, we studied the effects of Wnt blocking antibodies on iPS and differentiation into cardiomyocytes. We observed that in control iPS cells or iPS cells incubated with a Wnt5 blocking antibody no cardiomyocytes appeared. In contrast, iPS cells incubated with a Wnt3a blocking antibody spontaneously and robustly differentiated into cardiomyocytes (40%, N=5, P<0.001). Co-immunoprecipitation experiments demonstrated that Sfrp2 binds to Wnt3a (N=3, P<0.001). Furthermore, Sfrp2 binding to Wnt3a inhibited b-catenin activation in iPS cells (80% active b-catenin in control cells; 10% active b-catenin in Sfrp2 and Wnt3a blocking antibody treated cells. N=3. P<0.05). To identify the cardiogenic Wnt, we again screened iPS differentiation following incubation with various Wnt blocking antibodies. Through this process, we found that the positive effects of Sfrp2 or Wnt3a blocking antibodies were completely lost when the iPS were co-cultured with Wnt11 blocking antibodies (Wnt3a blocking antibody alone: 40% cardiomyocytes; Wnt3a plus Wnt11 blocking antibody: 0% cardiomyocytes). Interestingly, in iPS cells incubated with Wnt11 blocking antibody, b-catenin was re-activated (control cells: 10% active b-catenin; cells incubated with Wnt11 blocking antibody: 60% active b-catenin. N=3. P<0.05). In summary, iPS cells do not spontaneously differentiate into cardiomyocytes because of opposing effects of Wnt3a and Wnt11. Sfrp2 promotes cardiomyocyte differentiation by binding to Wnt3a, allowing Wnt11 to induce iPS cells to differentiate into cardiomyocytes.

Polymer-Coated Ultra-Fine Particles

2005 ◽  
Vol 896 ◽  
Author(s):  
Patrick Brousseau ◽  
Charles Dubois
Keyword(s):  
Energetic Materials ◽  
Fine Particles ◽  
Energetic Material ◽  
Relative Viscosity ◽  
Accelerated Ageing ◽  
Coated Particles ◽  
Metallic Particles ◽  
Positive Effects ◽  
Coating Methods ◽  
Ultra Fine Particles

AbstractUltra-fine metallic particles have demonstrated recently their potential in tailoring the performance of energetic materials. DRDC Valcartier has explored methods to create controllable nanometric coatings on metallic particles and has opted to use polymers to treat the particles. Those coatings can have multiple positive effects. For example, in the case of aluminium, small particles are very reactive and tend to cause interations with the surrounding media. One example is the ageing of aluminium nanoparticles in the presence of air and humidity. Ultra-fine particles age much faster than micron-size particles. The long-term stability of energetic material mixes containing ultra-fine particles will be affected by this reactivity, and coatings would help to solve this problem. Another example is the interaction of aluminium nanoparticles with nitramines that causes gassing. Three coating methods will be presented: by thermoplastics using a Ziegler-Natta reaction, by thermosets through a polycondensation reaction initiated at the surface of the particles, and in-situ coating of particles by on-line polymerization during the plasma production of powders. The results of coating experiments using those methods will be presented. It will be shown that, for aluminium particles, adequate dispersion is a challenge and affects the results of the coating experiments. To assess the performance of the coating methods, ageing tests were carried out on coated and uncoated nanoparticles. The results of ageing tests with those methods will be presented and compared. It will be shown that the polymer coatings reduce significantly the loss of active metal content during accelerated ageing tests. Since the purpose of the powders is to be used in energetic materials, a study on the rheological effects of the coated particles in polymeric solutions will be presented as well. Coated particles increase the relative viscosity of HTPB-Al solutions by a factor of 100 at low shear rates, but much less with PPG.

Effect of Nanotechnology on Physical Properties of Concrete

2017 ◽  
Vol 733 ◽  
pp. 71-75
Author(s):  
Leila Remache ◽  
Nacerddine Djermane
Keyword(s):  
Fly Ash ◽  
Large Volume ◽  
Lower Cost ◽  
Material Behavior ◽  
The Self ◽  
Bridge Piers ◽  
Early Age ◽  
Self Healing ◽  
Positive Effects ◽  
Green Additive

The focus of this paper is the study of effect of nanotechnology on the concrete. It shows that:The control of moisture in buildings is key to their durability, functionality, health and efficiency. Concrete which is thoroughly soaked with water is less rigid in compression than concrete with is thoroughly dried out. Use of nano SiO2 could significantly increase the compressive for concrete, containing large volume fly ash, at early age and improve size distribution. The self-healing polymer could be especially applicable to fix the microcraking in bridge, piers and columns. With the hycrete waterproofing system, concrete is batched with hycrete liquid admixture to achieve hydrophobic performance. Concrete treated by hycrete shows less than 1% absorption. This product has positive effects on the environment. Green additive has lower cost than the materials they replace. Finally, two solutions are given to have appropriate material behavior: nanotechnology and green additive.

scholarly journals Spheroidisation of Stainless Steel Powder for Additive Manufacturing

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1081
Author(s):  
Silethelwe Chikosha ◽  
Lerato C. Tshabalala ◽  
Hertzog Bissett ◽  
Miltia Lesufi ◽  
Ndumiso K. Mnguni ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Additive Manufacturing ◽  
Fine Particles ◽  
Steel Powder ◽  
304 Stainless Steel ◽  
Aisi 304 Stainless Steel ◽  
Aisi 304 ◽  
Plasma Spheroidization ◽  
Powder Characteristics ◽  
Powder Properties

In additive manufacturing, powder characteristics play an important role in terms of flowability and densification, which can be improved by the use of spherical powders. In this study, irregular powder was spheroidised by plasma treatment, and the powder properties were measured. Powder characterisation was conducted to determine the morphology, particle size and distribution as well as the flowability. Spherical AISI 304 stainless steel powders were produced by plasma spheroidization, and the efficiency of the spheroidisation process was evaluated. The spheroidisation process resulted in 93% efficiency with a decrease of fine particles (<63 µm) by 22%, while the all the flowability parameters of the powder improved significantly.

scholarly journals The effect of spaceflight on mouse olfactory bulb volume, neurogenesis, and cell death indicates the protective effect of novel environment

2014 ◽  
Vol 116 (12) ◽  
pp. 1593-1604 ◽  
Author(s):  
Sarah E. Latchney ◽  
Phillip D. Rivera ◽  
Xiao W. Mao ◽  
Virginia L. Ferguson ◽  
Ted A. Bateman ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
Space Shuttle ◽  
Region Of Interest ◽  
Space Missions ◽  
Structure And Function ◽  
Apoptotic Cells ◽  
Positive Effects ◽  
Cell Layers ◽  
And Function ◽  
Opposing Effects

Space missions necessitate physiological and psychological adaptations to environmental factors not present on Earth, some of which present significant risks for the central nervous system (CNS) of crewmembers. One CNS region of interest is the adult olfactory bulb (OB), as OB structure and function are sensitive to environmental- and experience-induced regulation. It is currently unknown how the OB is altered by spaceflight. In this study, we evaluated OB volume and neurogenesis in mice shortly after a 13-day flight on Space Shuttle Atlantis [Space Transport System (STS)-135] relative to two groups of control mice maintained on Earth. Mice housed on Earth in animal enclosure modules that mimicked the conditions onboard STS-135 (AEM-Ground mice) had greater OB volume relative to mice maintained in standard housing on Earth (Vivarium mice), particularly in the granule (GCL) and glomerular (GL) cell layers. AEM-Ground mice also had more OB neuroblasts and fewer apoptotic cells relative to Vivarium mice. However, the AEM-induced increase in OB volume and neurogenesis was not seen in STS-135 mice (AEM-Flight mice), suggesting that spaceflight may have negated the positive effects of the AEM. In fact, when OB volume of AEM-Flight mice was considered, there was a greater density of apoptotic cells relative to AEM-Ground mice. Our findings suggest that factors present during spaceflight have opposing effects on OB size and neurogenesis, and provide insight into potential strategies to preserve OB structure and function during future space missions.

scholarly journals Opposing effects of input control and clan control for sellers on e-marketplace platforms

2021 ◽  
Author(s):  
Evgheni Croitor ◽  
Dominick Werner ◽  
Martin Adam ◽  
Alexander Benlian
Keyword(s):  
Behavioral Intentions ◽  
Behavioral Outcomes ◽  
Perceived Usefulness ◽  
Control Mechanisms ◽  
Positive Effects ◽  
Input Control ◽  
Negative Effect ◽  
Opposing Effects ◽  
Clan Control

AbstractE-marketplace platforms focus on attracting and retaining sellers to secure the platform’s long-term viability and success. Although sellers’ behavioral intentions have been linked to control modes deployed on e-marketplace platforms, little is known about how and why perceptions of input control and clan control affect sellers’ crucial behavioral outcomes. Drawing on IS control literature, we conducted two online surveys with sellers on Amazon (n = 286) and Etsy (n = 185). Our results revealed that perceived input control had a negative effect on sellers’ perceived usefulness, satisfaction, and continuance intentions, whereas positive effects were observed with perceived clan control. In addition, we find that intrinsic motivation mediates the observed direct effects. Our study contributes to the literature by introducing control modes in the context of e-marketplace platforms and examining the effects of input control and clan control on sellers’ beliefs, attitudes, and behavioral intentions. Furthermore, our study has important practical implications for platform providers in how to apply different control mechanisms and increase complementors’ willingness to keep contributing to e-marketplace platforms, thereby nurturing platform health and sustainability.

scholarly journals Creating in the Crucibles of Nature's Fury

2019 ◽  
Author(s):  
Sunasir Dutta
Keyword(s):  
Natural Disasters ◽  
Human Services ◽  
Racial Diversity ◽  
Aggregate Size ◽  
Organizational Challenges ◽  
Positive Effects ◽  
Collective Goods ◽  
Negative Effect ◽  
Human Services Organizations ◽  
Opposing Effects

This paper examines foundings of human services organizations after natural disasters such as floods, earthquakes, wildfires, hurricanes, and tsunamis and explains why only some communities bounce back by founding appropriate collective-goods organizations. Using natural disasters in California counties from 1990 to 2010 as shocks that exogenously impose a need for collective goods over and above the level endogenous to the community, this paper shows that a geographic community’s local organizing capacity rests on the richness of its repertoire of voluntary organizing models as reflected in the diversity of its voluntary associations. Such diversity is even more critical when the type of natural disaster is more unexpected or complex (e.g., both a wildfire and an earthquake) in an area, and the organizational challenges posed are thus more novel for the community. Associational diversity has positive effects on both the numbers and aggregate size of foundings of local (non-branch, secular) human services organizations, and the effects are generalizable to other endogenous demand conditions such aspoverty. Results also show how different kinds of variety can have opposing effects onorganizing capacity as observed after a disaster, with associational diversity having a positive effect, political diversity having a negative effect, and racial diversity having no significant effect, net of other factors. The paper concludes with a call for treating community resilience as a matter of enhancing local organizing capacity over centralized planning efforts when the environment is rapidly changing.

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