silicon dioxide nanoparticles – Page 2 – Silver Nanoparticles Antimicrobial,Copper Oxide Nanoparticles,Gold Nanopowder

June 30, 2015

Do You Know Gold Nanoparticles?

Ultrasmall, crystalline, and dispersible NiO nanoparticles are prepared for the first time, and it is shown that they are promising candidates as catalysts for electrochemical water oxidation. Using a solvothermal reaction in tert-butanol, very small nickel oxide nanocrystals can be made with sizes tunable from 2.5 to 5 nm and a narrow particle size distribution. The crystals are perfectly dispersible in ethanol even after drying, giving stable transparent colloidal dispersions. The structure of the nanocrystals corresponds to phase-pure stoichiometric nickel(ii) oxide with a partially oxidized surface exhibiting Ni(iii) states. The 3.3 nm nanoparticles demonstrate a remarkably high turn-over frequency of 0.29 s–1 at an overpotential of g = 300 mV for electrochemical water oxidation, outperforming even expensive rare earth iridium oxide catalysts. The unique features of these NiO nanocrystals provide great potential for the preparation of novel composite materials with applications in the field of (photo)electrochemical water splitting. The dispersed colloidal solutions may also find other applications, such as the preparation of uniform hole-conducting layers for organic solar cells.

Gold has always been the one precious material people like best. Due to its intrinsic value, buying the yellow metal has been seen as a good way of securing one’s money. Big players on the market prefer it in the form of bullion, whereas small investors settle themselves with purchasing fine pieces of gold jewelry. In modern times though, gold has ceased to be merely a safe investment opportunity or exchange currency. As a result of extensive research and continuous development, it has been discovered that gold can be used successfully for scientific purposes as well.

One of these special uses of gold refers to what is called ‘nanogold’, ‘colloidal gold’ or ‘gold nanoparticles’, i.e. sub-micrometer-sized particles of gold dispersed in a fluid, usually water. The existence of these special gold particles has been known to people since ancient times, yet it was in 1850s that scientists focused their full attention on them. The main reasons behind this interest for gold nanoparticles are their extraordinary optical, electronic and molecular-recognition properties. These properties allow for the gold nanoparticles to have applications in various fields, including electron microscopy, electronics,Nickel Oxide Nanoparticles,nanotechnology and materials science.

Biological electronic microscopy is one of the areas where gold nanoparticles have been extensively used as contrast agents. They can be associated with many traditional biological probes such as antibodies, lectins, superantigens, glycans, nucleic acids and receptors. Because gold particles having various sizes can be easily spotted in electron micrographs, it is possible for multiple experiments to be conducted simultaneously.

In what concerns the domain of health and medical applications, gold nanoparticles have been successfully used as part of the treatment for some diseases. Rheumatoid arthritis was among the first conditions where use of gold was part of the therapy since it has been found that gold particles implanted near the arthritic hip joints relieve pain. There have also been some in vitro experiments which have proved that gold nanoparticles combined with microwave radiation can destroy the beta-amyloid fibrils and plaque which are characteristic for Alzheimer’s disease. But perhaps the most important medical purpose for which gold nanoparticles can be used is the localization and treatment of cancer. It has already been shown that by directing gold nanoparticles into the nuclei of cancer cells, they can only not hinder them from multiplying, but also kill them.

As we can see, for the modern society of today gold has become more than just merchandise and by buying it we do not just secure our investments, but our health as well. With the help of science, researchers have been able to explore the great latent potential gold has. Just like the professionals in the business whose opinion is of great value for the buyers, specialists in important areas such as medicine can testify about gold’s benefits too.

June 25, 2015

Standards For Nano-Enabled Industries

Single-walled Carbon Nanotubes (SWNTs) are nanometer-diameter cylinders consisting of a single graphene sheet wrapped up to form a tube. Since their discovery in the early 1990s[1, 2], there has been intense activity exploring the electrical properties of these systems and their potential applications in electronics. Experiments and theory have shown that these tubes can be either metals or semiconductors, and their electrical properties can rival, or even exceed, the best metals or semiconductors known. Particularly illuminating have been electrical studies of individual nanotubes and nanotube ropes (small bundles of individual nantoubes). The first studies on metallic tubes were done in 1997[3, 4] and the first on semiconducting tubes in 1998[5]. In the intervening five years, a large number of groups have constructed and measured nanotube devices, and most major universities and industrial laboratories now have at least one group studying their properties. These electrical properties are the subject of this review. The data presented here are taken entirely from work performed by the authors (in collaboration with other researchers), but they can be viewed as representative of the field.

Like the California gold rush of 1849, the emergence of nanotechnology presents both an enormous opportunity and enormous risks. Just as new techniques, rewards, and challenges emerged during the gold rush era, nanotechnology exploration will inevitably lead to the development of new tools to achieve new breakthroughs, the opportunity for creating enormous wealth, and unfortunately, the potential for environmental, health, and safety disasters. Although Single-walled Carbon Nanotubes undoubtedly will create disruptive technologies that will spin off many new jobs, it also has the potential for displacing existing workers unprepared to take on these new technologies.

The first fruits of nano R&D are already being harvested as disciplines as diverse as materials, electronics, biotechnology, and computing rush to exploit nanotechnology’s potential. Many consumers have already become familiar with nano-derived products, such as improved types of cosmetics, fabrics, paints, plastics, or personal electronics.

Nanotechnology offers all-but-unlimited opportunities for those who can develop the next exotic material or electronic component that is cheaper, better, and faster than today’s CMOS devices. It also holds huge promise for those who will create the tools needed to produce these materials and devices. Despite the recession, corporate and government labs around the world continue to invest billions in nanoscience research. Unfortunately, unless the public and private sectors work in cooperation to develop standardized test methods and guidelines, the transition from the laboratory to the marketplace could create many of the same problems as the California gold rush did, particularly for the environment. However, with careful planning, we can have the appropriate terminology, test measurement methods, reporting, and environmental, safety, and health safeguards in place early enough to ward off serious consequences.

Why Are Standards So Important?

Very simply, standards are crucial to achieving a high degree of interoperability, creating order in the marketplace, simplifying production requirements, managing the potential for adverse environmental impacts, and most important, ensuring the safety and health of those developing and using the next generation of materials and devices.

Standards for nano terminology, materials, devices, systems, and processes will help establish order in the marketplace. For R&D researchers and engineers, standards make it possible to make measurements and report data consistently in a way that others can understand clearly. Those responsible for developing standards will be at the forefront in understanding the need for, and creation of, new characterization tools, processes, components, and products to help jump-start this emerging field. This kind of approach can represent a competitive tool in global markets. Creating a standard in advance of the release of a new technology allows both manufacturers and consumers to gain greater confidence in it, promoting greater acceptance and faster adoption.

The following examples illustrate the importance of early standards development.

Carbon Nanotubes

Although some of the more sophisticated electronics and medical advances scientists have envisioned are still years down the road, the development of some nanoscale raw materials, particularly carbon nanotubes (CNTs), is already well underway. Years before CNTs were commercially available, industry observers heard how they would bring significant performance advantages to electronics, enhance materials to make them stronger and lighter, and might even be part of the solution to our energy problems. This industry buzz, plus the massive private and public sector investments in nano research, built interest at every level. In 2000, the late Dr. Richard Smalley spun off his work to form Carbon Nanotechnologies Inc. (now Unidym) with the goal of commercializing his method of producing large batches of high-quality nanotubes. Unfortunately, at that point, there were no manufacturing standards or guidelines for ensuring the reproducibility of the company’s manufacturing process. There were also no known test and measurement guidelines for verifying the reproducibility and proving results on a large scale. Given this, how would the company have assured its customers of the quality of its products? Or just as important, how could customers choose confidently among various manufacturers’ CNTs based on their product description?

Buying carbon nanotubes isn’t like buying baseballs or bananas-it’s impossible to judge their quality just by looking at them. En masse, CNTs basically look like a pile of soot. How can incoming inspectors verify what they have received? How do they know whether they are single-walled or multi-walled tubes? Given the different species of carbon nanotubes now available (tubes that are metal or semiconducting, based on their chirality), most companies looking to purchase nanotubes would have had no basis on which to ensure that what they received is what they ordered. However, with a standard in place, customers have the tools needed to verify the materials they are purchasing.

June 15, 2015

Do You Know Antibacterial Silver Nanoparticles?

The antimicrobial activity of Silver Nanoparticles Antimicrobial against E. coli was investigated as a model for Gram-negative bacteria. Bacteriological tests were performed in Luria–Bertani (LB) medium on solid agar plates and in liquid systems supplemented with different concentrations of nanosized silver particles. These particles were shown to be an effective bactericide. Scanning and transmission electron microscopy (SEM and TEM) were used to study the biocidal action of this nanoscale material. The results confirmed that the treated E. coli cells were damaged, showing formation of “pits” in the cell wall of the bacteria, while the silver nanoparticles were found to accumulate in the bacterial membrane. A membrane with such a morphology exhibits a significant increase in permeability, resulting in death of the cell. These nontoxic nanomaterials, which can be prepared in a simple and cost-effective manner, may be suitable for the formulation of new types of bactericidal materials.

There are some bacteria that are not effectively killed by the conventional antibiotics including many strains of gram-negative bacteria. However the innovative world of science and the need of developing an effective way to cope with this situation has lead scientist to manage a new technology in this regard.

Rani Pattabi and her colleagues at Mangalore University, explains in the international journal of nanoparticles that an electron beam when blasted on a silver nitrate solution can generate nanoparticles.

These particles are shown to be effective against gram-negative species that are not affected by conventional antibacterial agents.

The researchers in India also pointed that these silver nanoparticles are effective against gram-positive bacteria, such as resistant strains of Staphylococcus aureus and Streptococcus pneumoniae and also effective for treating gram-negative Escherichia coli and Pseudomonas aeruginosa.The problem that is threatening human health is resistance to the existing conventional antibiotics. Therefore the chemists all around the world are desperately trying to develop newer compounds that can easily be bactericidal for strains such as MRSA (methicillin or multiple-resistant Staphylococcus aureus) and E. coli O157.

Since the ancient times, silver has been renowned for its bactericidal activities.

Therefore a technological advancement in the use of silver means a major step forward and a promise for a wide range of applications of silver as anti bacterial agent in the times where antibiotic resistance is proving to be an obstacle for anti bacterial use. Thus the emergence of silver nanoparticles and other such bacteriostatic agents have become a new industrial revolution.

The experimentation involving the radiations to split the silver compounds to release silver ions that will clump together and form nanoparticles, have been taken as a challenge by the researchers. The target was in fact to get a new approach that avoids the need for costly and hazardous reducing agents and that these can be used to get particles of a controlled size that controls its properties as well.

So Pattabi and colleagues used electron beam technology to irradiate silver nitrate solutions in a biocompatible polymer that was polyvinyl alcohol, to form silver nanoparticles.

The Preliminary tests have shown that silver nanoparticles produced by this straightforward, non-toxic method are indeed highly active against S. aureus, E. coli, and P. aeruginosa.

Now we can imagine that our shoes, socks or even the keyboard we are using may be impregnated with silver nanoparticles that can kill some bacteria and might as well prevent the spread of infection among computer users.

These can be the frontline defenses such as these environmentally benign and cost-effective antibacterial compounds and these can prevent spreading the infections through contact with computer keyboard, phones and other devices.

May 26, 2015

Types of Chemical Heater and Silicon Carbide Whisker

Silicon Carbide is the only chemical compound of carbon and silicon. It was originally produced by a high temperature electro-chemical reaction of sand and carbon. Silicon carbide is an excellent abrasive and has been produced and made into grinding wheels and other abrasive products for over one hundred years. Today the material has been developed into a high quality technical grade ceramic with very good mechanical properties.It is used in abrasives,refractories,ceramics,and numerous high-performance applications. Silicon carbide whisker can also be made an electrical conductor and has applications in resistance heating, flame igniters and electronic components. Structural and wear applications are constantly developing.

Chemical heater and etch process are important terms that must be learned by people and businesses in the semiconductor industry. In this article, I am sharing about the types of chemical heaters used in the wet process system as well as the silicon nitride etch process.

Types of chemical heater

Quartz – Gas Heater — a system that is designed to meet the growing demand for heated high purity gasses. It has the capacity of heating a wide range of gases including: Ammonia (NH3), Helium (He), Argon (Ar), Hydrogen (H2), Arsine (AsH3),Hydrogen Bromide (HBr), Boron Trichloride (BCl3),Hydrogen Chloride (HCl), Carbon Dioxide (CO2), Nitrogen (N2),Carbon Monoxide (CO), Chlorine (Cl2), Nitrous Oxide (N2O), Oxygen (O2),Disilane (Si2H6), Sulfur Dioxide (SO2),Methylsilane (SiH3CH3)

Quartz – Fluid Heater — used in the semiconductor industry and its traditional application includes recirculation loop, either as the sole head source or a combination of a heated quartz tank.

SiC – HF & KOH Heater — designed for heating HF (hydrofluoric acide), KOH (potassium hydroxide), and other high PH chemistries. It uses high purity Silicon Carbide (SiC) as a heat transfer material because it has excellent heat transfer properties and eliminates the risk of contamination due to Teflon breakdown.
Interesting Facts about the Silicon Nitride Etch process

To be able to achieve the greatest etch rates and best selectivity, the phosphoric acid should have the highest ratio of water at a given temperature. For as long as the boil point is maintained, the etch rate of both Si3N4 and SiO2 can be precisely controlled.

Maintaining a boiling solution is one of the challenges in the etch process. When phosphoric acid is heated, the water solution begins boiling off. When temperature is not maintained, it affects the etching process as the acid concentration increase. Wet etch companies use a standard temperature controller to maintain temperature, but the water concentration will decrease and will change the etch rates. As a solution, wet etch process engineers use water addition system.

A technology called closed “reflux” system is used and it is created above the bath using condensing collar and a lid – this is to minimize water addition.

The chemical fumes and high temperatures that Nitride Etch tanks are subjected to are known to decrease bath life substantially by attacking the sealant that prevents liquid and fumes from entering the heater area. This problem has been addressed through the use of aquaseal.

Quartz Nitride Reflux system is engineered to address the unique needs of the silicon nitride etch process. It gives the following benefits to customers: process uniformity, lot-to-lot repeatability, prevents stratification.