Chromic Acid Etching of Polyethylene

1973 ◽  
Vol 31 ◽  
pp. 72-73
Author(s):  
J. D. Muzzy ◽  
R. D. Hester ◽  
J. L. Hubbard
Keyword(s):  
Chromic Acid ◽  
Low Cost ◽  
Acid Etching ◽  
Crystalline Morphology ◽  
Bulk Specimen ◽  
Morphological Studies ◽  
Perfect Form ◽  
Molecular Length ◽  
Lamellar Texture ◽  
Cost Studies

Polyethylene is one of the most important plastics produced today because of its good physical properties, ease of fabrication and low cost. Studies to improve the properties of polyethylene are leading to an understanding of its crystalline morphology. Polyethylene crystallized by evaporation from dilute solutions consists of thin crystals called lamellae. The polyethylene molecules are parallel to the thickness of the lamellae and are folded since the thickness of the lamellae is much less than the molecular length. This lamellar texture persists in less perfect form in polyethylene crystallized from the melt.Morphological studies of melt crystallized polyethylene have been limited due to the difficulty of isolating the microstructure from the bulk specimen without destroying or deforming it.

Morphology Controlled Flower-Like ZnO Particles Synthesized by Low Cost High Pressure Cooker

2014 ◽  
Vol 608 ◽  
pp. 159-163
Author(s):  
Pat Sooksaen ◽  
Malin Rapp ◽  
Thipwipa Sirinakorn ◽  
Phatthraporn Meepanya ◽  
Pawanan Leangthammarat
Keyword(s):  
High Pressure ◽  
Hydrothermal Method ◽  
Metal Ion ◽  
Low Cost ◽  
Hexagonal Wurtzite Structure ◽  
Nitrate Hexahydrate ◽  
Sem Images ◽  
Hydrothermal Temperature ◽  
Morphological Studies ◽  
Zno Particles

ZnO is a good candidate material for many optical and optoelectronic applications. ZnO with various shapes and sizes can be prepared via chemical methods such as precipitation, microwave heating and hydrothermal method. Generally ZnO synthesized by hydrothermal method uses autoclave which is expensive and gives low % yield. This research applied a low cost high pressure cooker which replaced the use autoclave to synthesize ZnO as its concept is similar to hydrothermal method. In this study, it was found that the size and shape of the synthesized ZnO particles were affected by several factors such as Zn2+/OH- ratio, temperature and time. Zinc nitrate hexahydrate, Zn(NO3)2.6H2O and sodium hydroxide, NaOH were used as metal ion sources in the precursor solutions. Structural and morphological studies were performed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The effect of Zn2+/OH- ion ratios, hydrothermal temperature and time on the size and morphology of ZnO were discussed in detail. All the synthesized conditions yielded hexagonal wurtzite structure of ZnO confirmed by XRD, without calcinations process. SEM images showed plate-like structure for Zn2+/OH- ratio = 1:7.5 and 1:15 and flower structure for Zn2+/OH- ratio = 1:20. Sizes of the synthesized ZnO particles decreased with increasing hydrothermal temperature from 120to 200°C. The longer the synthesized time period the larger the ZnO particles obtained.

scholarly journals β-Cyclodextrin-Polyacrylamide Hydrogel for Removal of Organic Micropollutants from Water

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 5031
Author(s):  
Xia Song ◽  
Nana Nyarko Mensah ◽  
Yuting Wen ◽  
Jingling Zhu ◽  
Zhongxing Zhang ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Low Cost ◽  
Inclusion Complexation ◽  
Radical Copolymerization ◽  
Pollutant Removal ◽  
Toxic Substances ◽  
Organic Micropollutants ◽  
Thermal Regeneration ◽  
Free Radical Copolymerization ◽  
Morphological Studies

Water pollution by various toxic substances remains a serious environmental problem, especially the occurrence of organic micropollutants including endocrine disruptors, pharmaceutical pollutants and naphthol pollutants. Adsorption process has been an effective method for pollutant removal in wastewater treatment. However, the thermal regeneration process for the most widely used activated carbon is costly and energy-consuming. Therefore, there has been an increasing need to develop alternative low-cost and effective adsorption materials for pollutant removal. Herein, β-cyclodextrin (β-CD), a cheap and versatile material, was modified with methacrylate groups by reacting with methacryloyl chloride, giving an average degree of substitution of 3 per β-CD molecule. β-CD-methacrylate, which could function as a crosslinker, was then copolymerized with acrylamide monomer via free-radical copolymerization to form β-CD-polyacrylamide (β-CD-PAAm) hydrogel. Interestingly, in the structure of the β-CD-PAAm hydrogel, β-CD is not only a functional unit binding pollutant molecules through inclusion complexation, but also a structural unit crosslinking PAAm leading to the formation of the hydrogel 3D networks. Morphological studies showed that β-CD-PAAm gel had larger pore size than the control PAAm gel, which was synthesized using conventional crosslinker instead of β-CD-methacrylate. This was consistent with the higher swelling ratio of β-CD-PAAm gel than that of PAAm gel (29.4 vs. 12.7). In the kinetic adsorption studies, phenolphthalein, a model dye, and bisphenol A, propranolol hydrochloride, and 2-naphthol were used as model pollutants from different classes. The adsorption data for β-CD-PAAm gel fitted well into the pseudo-second-order model. In addition, the thermodynamic studies revealed that β-CD-PAAm gel was able to effectively adsorb the different dye and pollutants at various concentrations, while the control PAAm gel had very low adsorption, confirming that the pollutant removal was due to the inclusion complexation between β-CD units and pollutant molecules. The adsorption isotherms of the different dye and pollutants by the β-CD-PAAm gel fitted well into the Langmuir model. Furthermore, the β-CD-PAAm gel could be easily recycled by soaking in methanol and reused without compromising its performance for five consecutive adsorption/desorption cycles. Therefore, the β-CD-PAAm gel, which combines the advantage of an easy-to-handle hydrogel platform and the effectiveness of adsorption by β-CD units, could be a promising pollutant removal system for wastewater treatment applications.

scholarly journals Approximately self-consistent ensemble density functional theory: toward inclusion of all correlations

2020 ◽  
Author(s):  
Tim Gould
Keyword(s):  
Density Functional Theory ◽  
Excited States ◽  
Density Functional ◽  
Low Cost ◽  
Recent Theory ◽  
Functional Theory ◽  
Effective Potentials ◽  
Simple Theories ◽  
Promising Tool ◽  
Cost Studies

Recent theory developments in ensemble density functional theory (EDFT) promise to bring decades of work for ground-states to the practical resolution of excited-states - provided newly-discovered "density-driven correlations" can be dealt with and adequate effective potentials can be found. This Letter introduces simple theories for both; and shows that EDFT using these theories outperforms ΔSCF DFT and time-dependent DFT for low-lying gaps in most of the small atoms and molecules tested, even when all use the same density functional approximations. It thus establishes EDFT as a promising tool for low-cost studies of excited states; and provides a clear route to practical EDFT implementation of arbitrary functional approximations.<br><br>

scholarly journals Zeolite-Assisted Shear Exfoliation of Graphite into Few-Layer Graphene

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 377 ◽  
Author(s):  
Gabriela Tubon Usca ◽  
Cristian Vacacela Gomez ◽  
Marco Guevara ◽  
Talia Tene ◽  
Jorge Hernandez ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Low Cost ◽  
Great Promise ◽  
Layer Graphene ◽  
Morphological Studies ◽  
Transmission Electron ◽  
Potential Applications ◽  
Novel Method ◽  
Inorganic Layered Materials ◽  
Few Layer Graphene

A novel method is presented to prepare few-layer graphene (FLG) in N-methyl-2-pyrrolidinone (NMP) by using a simple, low-cost and energy-effective shear exfoliation assisted by zeolite and using a cappuccino mixer to produce shear. We propose that the exfoliation of natural graphite flakes can be achieved using inelastic collisions between graphite flakes and zeolite particles in a dynamic colloidal fluid. To confirm the exfoliation of FLG, spectroscopy and morphological studies are carried out using Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Additionally, the obtained graphene shows a linear flow of current and low resistance. The proposed method shows great promise for the industrial-scale synthesis of high-quality graphene with potential applications in future graphene-based devices, and furthermore, this method can be extended to exfoliate inorganic layered materials such as BN and MoS2.

Submicron Patterns on Sapphire Substrate Produced by Dual Layer Photoresist Complimentary Lithography

2013 ◽  
Vol 284-287 ◽  
pp. 334-341
Author(s):  
Chun Ming Chang ◽  
Ming Hua Shiao ◽  
Don Yau Chiang ◽  
Chin Tien Yang ◽  
Mao Jung Huang ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Low Cost ◽  
Semiconductor Industry ◽  
Chemical Properties ◽  
High Yield ◽  
Acid Etching ◽  
Direct Write ◽  
Etching Solution ◽  
Inductively Coupled ◽  
Aqueous Acid

In this study, the combined technologies of dual-layer photoresist complimentary lithography (DPCL), inductively coupled plasma-reactive ion etching (ICP-RIE) and laser direct-write lithography (LDL) are applied to produce the submicron patterns on sapphire substrates. The inorganic photoresist has almost no resistance for chlorine containing plasma and aqueous acid etching solution. However, the organic photoresist has high resistance for chlorine containing plasma and aqueous acid etching solution. Moreover, the inorganic photoresist is less etched by oxygen plasma etching process. The organic and inorganic photoresists deposit sequentially into a composite photoresist on a substrate. The DPCL takes advantages of the complementary chemical properties of organic and inorganic photoresists. We fabricated two structures with platform and non-platform structure. The non-platform structure featured structural openings, the top and bottom diameters and the depth are approximately 780 nm, 500 nm and 233 nm, respectively. The platform structure featured structural openings, the top and bottom diameters and the depth are approximately 487 nm, 288 nm and 203 nm, respectively. The precision submicron or nanoscale patterns of large etched area and patterns with high aspect ratio can be quickly produced by this technique. This technology features a low cost but high yield production technology. It has the potential applications in fabrication of micro-/nanostructures and devices for the optoelectronic industry, semiconductor industry and energy industry.

scholarly journals 245 Equine research programs: Where are they going?

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 21-22
Author(s):  
Brian D Nielsen
Keyword(s):  
Low Cost ◽  
Federal Funding ◽  
Junior Faculty ◽  
Limited Resources ◽  
Quality Research ◽  
Funding Agencies ◽  
On Line ◽  
Fundamental Research ◽  
Horse Industry ◽  
Cost Studies

Abstract Those in the equine community have a strong desire for knowledge in the quest to provide the best care for their horses. Unfortunately, they often seek out advice through on-line sources and are quick to take anecdotal evidence or testimonials as fact. While those in the scientific community would encourage decisions to be made based upon quality research, often there are insufficient data available to answer questions posed by the industry. One of the reasons for this is limited resources. In the past it was common to have departmental-funded assistantships for graduate students. However, those assistantships have disappeared in many departments and now students are often supported through grants. Likewise, there is additional pressure by administrators for federal funding though “horse research” is often considered less important to such funding agencies as horses are viewed as recreational animals as opposed to being a food-producing animals. Hence, much funded equine research would fall under the category of product-testing. While somewhat limited in scope, such research may provide the opportunity to answer other research questions if projects are appropriately planned. However, such “side-projects” are only useful if adequate subject numbers and controls are in place. Reduced animal availability and increased costs of utilizing horses in research may necessitate using other animal models for horses to answer fundamental questions and, if appropriately designed, may allow projects to be competitive for federal funding. Especially as it pertains to junior faculty, collaborative research utilizing colleagues with specialized skills can be important in terms of promoting competitive and fundamental research proposals. While limited resources may increase the appeal for low-cost studies, there is still a need for well-designed studies that answer questions critical to the horse industry and doing quality research is important to enhance the reputation of equine research.

scholarly journals Approximately self-consistent ensemble density functional theory: toward inclusion of all correlations

2020 ◽  
Author(s):  
Tim Gould
Keyword(s):  
Density Functional Theory ◽  
Excited States ◽  
Density Functional ◽  
Low Cost ◽  
Recent Theory ◽  
Functional Theory ◽  
Effective Potentials ◽  
Simple Theories ◽  
Promising Tool ◽  
Cost Studies

Recent theory developments in ensemble density functional theory (EDFT) promise to bring decades of work for ground-states to the practical resolution of excited-states - provided newly-discovered "density-driven correlations" can be dealt with and adequate effective potentials can be found. This Letter introduces simple theories for both; and shows that EDFT using these theories outperforms ΔSCF DFT and time-dependent DFT for low-lying gaps in most of the small atoms and molecules tested, even when all use the same density functional approximations. It thus establishes EDFT as a promising tool for low-cost studies of excited states; and provides a clear route to practical EDFT implementation of arbitrary functional approximations.<br><br>

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