Sasidharan M.,Saga University |
Sasidharan M.,niversity |
Nakashima K.,Saga University
Accounts of Chemical Research | Year: 2014
Hollow, inorganic nanoscale capsules have many applications, from the delivery of encapsulated products for cosmetic and medicinal purposes to use as lightweight composite materials. Early methods for producing inorganic hollow nanospheres using hard templates suffered from low product yield and shell weakness upon template removal. In the past decade, researchers have turned to amphiphilic copolymers to synthesize hollow nanostructures and ordered mesoporous materials.Amphiphilic molecules self-assemble into well-defined nanostructures including spherical micelles. Micelles formed from simple, two-component AB diblock and ABA triblock copolymers, however, have been difficult to work with to construct inorganic hollow nanoparticles, because the corona of the micelle, which serves as the template for the shell, becomes unstable as it absorbs inorganic shell precursors, causing aggregates to form.Newly developed, three-component ABC triblock copolymers may solve this problem. They provide nanoassemblies with more diverse morphological and functional features than AB diblock and ABA triblock copolymers. Micelles formed from ABC triblock copolymers in selective solvents that dissolve only one or two of the blocks provide templates for these improved nanoassemblies. By manipulating individual polymer blocks, one can "encode" additional features at the molecular level. For instance, modifying the functional groups or substitution patterns of the blocks allows better morphological and size control. Insights into polymer self-assembly gained over years of work in our group have set the stage to systematically engineer inorganic spherical hollow nanoparticles using ABC triblock copolymers.In this Account, we report our recent progress in producing diverse, inorganic hollow spherical nanospheres from asymmetric triblock copolymeric micelles with core-shell-corona architecture as templates. We discuss three classes of polymeric micelles - with neutral, cationic, and anionic shell structures - that allow fabrication of a variety of hollow nanoparticles. Importantly, we synthesized all of these particles in water, avoiding use of hazardous organic solvents. We have designed the precursor of the inorganic material to be selectively sorbed into the shell domain, leaving the corona free from the inorganic precursors that would destabilize the micelle. The core, meanwhile, is the template for the formation of the hollow void. By rationally tailoring experimental parameters, we readily and selectively obtained a variety of hollow nanoparticles including silica, hybrid silicas, metal-oxides, metal-carbonates, metal-sulfates, metal-borates, and metal-phosphates.Finally, we highlight the state-of-the-art techniques we used to characterize these nanoparticles, and describe experiments that demonstrate the potential of these hollow particles in drug delivery, and as anode and cathode materials for lithium-ion batteries. © 2013 American Chemical Society.
Comunicata Scientiae | Year: 2014
A field experiment was conducted during winter seasons of 2003-04 and 2004-05 at Kanpur, India to study the effect of winter maize (Zea mays L.) based intercropping systems on maize yield, associated weeds and economics under irrigated condition of central Uttar Pradesh. Thirteen maize-based cropping systems such as maize sole, potato (Solanum tuberosum L.) sole, mustard [Brassica juncea (L.) Czernj. & Cosson] sole, toria (Brassica campestris var. toria) sole, pea (Pisum sativum L.) sole, linseed (Linum usitatissimum L.) sole, wheat (Triticum aestivum L. emend. Fiori and Paol.) sole, maize + potato (1:1),maize + mustard (1:1), maize + toria (1:2), maize + pea (1:2), maize + linseed (1:2) and maize + toria (1:2), were tested in randomized block design with three replications. Maize + potato system recorded higher yield attributes and grain yield of maize followed by maize + pea than sole stand of maize. potato was showed most compatible intercrop planted with winter maize as it gave higher maize-equivalent yield, land-equivalent ratio, productivity, monetary returns and lowered weed population, weed dry-biomass and highest weed-control efficiency under irrigated conditions of central Uttar Pradesh. Pea was the next best intercrop with winter maize.
Kirstein F.,University of Cape Town |
Horsnell W.G.C.,University of Cape Town |
Kuperman D.A.,Northwestern University |
Huang X.,University of Melbourne |
And 4 more authors.
Journal of Allergy and Clinical Immunology | Year: 2010
Background: Airflow in the lungs of patients with allergic asthma is impaired by excessive mucus production and airway smooth muscle contractions. Elevated levels of the cytokines IL-4 and IL-13 are associated with this pathology. In vitro studies have suggested that IL-4 receptor a (IL-4Rα) signaling on smooth muscle cells is critical for airway inflammation and airway hyperresponsiveness. Objective: To define the contribution of IL-4 and IL-13 to the onset of asthmatic pathology, the role of their key receptor creIL-4Rα-logx in smooth muscle cells was examined in vivo. Methods: By using transgenic smooth muscle myosin heavy Chaincre IL-4Rα-/lox mice deficient in IL-4Rα in smooth muscle cells, in vivo effects of impaired creIL-4Rα-logx signaling in smooth muscle cells on the outcome of asthmatic disease were investigated for the first time. Allergic asthma was introduced in mice by repeated sensitization with ovalbumin/aluminum hydroxide on days 0, 7, and 14, followed by intranasal allergen challenge on days 21 to 23. Mice were investigated for the presence of airway hyperresponsiveness, airway inflammation, allergen-specific antibody production, TH2-type cytokine responses, and lung pathology. Results: Airway hyperresponsiveness, airway inflammation, mucus production, TH2 cytokine production, and specific antibody responses were unaffected in smooth muscle myosin heavy chaincre IL-4Rα-/lox mice compared with control animals. Conclusion: The impairment of IL-4Rα on smooth muscle cells had no effect on major etiologic markers of allergic asthma. These findings suggest that IL-4Rα responsiveness in airway smooth muscle cells during the early phase of allergic asthma is not, as suggested, necessary for the outcome of the disease. © 2010 American Academy of Allergy, Asthma & Immunology.
U niversity of Illinois engineers have found an energy-efficient material for removing salt from seawater that could provide a rebuttal to poet Samuel Taylor Coleridge’s lament, “Water, water, every where, nor any drop to drink.” The material, a nanometer-thick sheet of molybdenum disulfide (MoS2) riddled with tiny holes called nanopores, is specially designed to let high volumes of water through but keep salt and other contaminates out, a process called desalination. In a study published in the journal Nature Communications, the Illinois team modeled various thin-film membranes and found that MoS2 showed the greatest efficiency, filtering through up to 70 percent more water than graphene membranes. “Even though we have a lot of water on this planet, there is very little that is drinkable,” said study leader Narayana Aluru, a U. of I. professor of mechanical science and engineering. “If we could find a low-cost, efficient way to purify sea water, we would be making good strides in solving the water crisis. A computer model of a nanopore in a single-layer sheet of MoS2 shows that high volumes of water can pass through the pore using less pressure than standard plastic membranes. Salt water is shown on the left, fresh water on the right. “Finding materials for efficient desalination has been a big issue, and I think this work lays the foundation for next-generation materials. These materials are efficient in terms of energy usage and fouling, which are issues that have plagued desalination technology for a long time,” said Aluru. Most available desalination technologies rely on a process called reverse osmosis to push seawater through a thin plastic membrane to make fresh water. The membrane has holes in it small enough to not let salt or dirt through, but large enough to let water through. They are very good at filtering out salt, but yield only a trickle of fresh water. Although thin to the eye, these membranes are still relatively thick for filtering on the molecular level, so a lot of pressure has to be applied to push the water through. “Reverse osmosis is a very expensive process,” Aluru said. “It’s very energy intensive. A lot of power is required to do this process, and it’s not very efficient. In addition, the membranes fail because of clogging. So we’d like to make it cheaper and make the membranes more efficient so they don’t fail as often. We also don’t want to have to use a lot of pressure to get a high flow rate of water.” One way to dramatically increase the water flow is to make the membrane thinner, since the required force is proportional to the membrane thickness. Researchers have been looking at nanometer-thin membranes such as graphene. However, graphene presents its own challenges in the way it interacts with water. Aluru’s group has previously studied MoS2 nanopores as a platform for DNA sequencing and decided to explore its properties for water desalination. Using the Blue Waters supercomputer at the National Center for Supercomputing Applications at the U. of I., they found that a single-layer sheet of MoS2 outperformed its competitors thanks to a combination of thinness, pore geometry and chemical properties. A MoS2 molecule has one molybdenum atom sandwiched between two sulfur atoms. A sheet of MoS2, then, has sulfur coating either side with the molybdenum in the center. The researchers found that creating a pore in the sheet that left an exposed ring of molybdenum around the center of the pore created a nozzle-like shape that drew water through the pore. “MoS2 has inherent advantages in that the molybdenum in the center attracts water, then the sulfur on the other side pushes it away, so we have much higher rate of water going through the pore,” said graduate student Mohammad Heiranian, the first author of the study. “It’s inherent in the chemistry of MoS2 and the geometry of the pore, so we don’t have to functionalize the pore, which is a very complex process with graphene.” In addition to the chemical properties, the single-layer sheets of MoS2 have the advantages of thinness, requiring much less energy, which in turn dramatically reduces operating costs. MoS2 also is a robust material, so even such a thin sheet is able to withstand the necessary pressures and water volumes. The Illinois researchers are establishing collaborations to experimentally test MoS2 for water desalination and to test its rate of fouling, or clogging of the pores, a major problem for plastic membranes. MoS2 is a relatively new material, but the researchers believe that manufacturing techniques will improve as its high performance becomes more sought-after for various applications. “Nanotechnology could play a great role in reducing the cost of desalination plants and making them energy efficient,” said Amir Barati Farimani, who worked on the study as a graduate student at Illinois and is now a postdoctoral fellow at Stanford University. “I’m in California now, and there’s a lot of talk about the drought and how to tackle it. I’m very hopeful that this work can help the designers of desalination plants. This type of thin membrane can increase return on investment because they are much more energy efficient.”
Hemalatha S.,niversity |
Margret Anouncia S.,niversity
International Journal of Pharmacy and Technology | Year: 2016
Biometrics play an important role in solving security issues related to human identification system. Human recognition requires a robust feature set to discriminate individuals, for which, unique features are to be identified and processed. Fingerprint matching is the most sophisticated method of the different biometric techniques because fingerprints are unique and reliable. Fingerprint matching systems are and validated through many applications. Most of the existing system is automated and provides acceptable performance. These systems address level 1, level 2 and level 3 features such as pores, ridge contours and minutiae. Sometimes they lack accuracy due to the poor quality of the images. This paper provides a review of various fingerprint matching systems and then discusses an automated, simple and robust fingerprint matching system with a hierarchical matching method. © 2016, International Journal of Pharmacy and Technology. All Rights Reserved.