Journal articles on the topic 'Spherical many-electron systems'
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TOURIGNY, DAVID S. "THE THEORY OF AN ELECTRON ON A LOXODROME." Modern Physics Letters B 26, no. 08 (March 30, 2012): 1250052. http://dx.doi.org/10.1142/s0217984912500522.
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Single-electron models are regularly used in molecular physics to obtain information on the quantum properties of many-atom systems. Examples include applications of a particle contained on a ring to benzene, and an electron on a helix to helical polymers. Here it is shown that the model of an electron on a spherical helix (a loxodrome) is also amenable to such investigation, and may be used to describe an emerging class of molecules known as "molecular apple peels". Moreover, the Schrödinger equation that arises during consideration of this model is solved exactly.
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Shao, Zhifeng. "Probe size and 5th-order aberration." Proceedings, annual meeting, Electron Microscopy Society of America 45 (August 1987): 134–35. http://dx.doi.org/10.1017/s0424820100125609.
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A small electron probe has many applications in many fields and in the case of the STEM, the probe size essentially determines the ultimate resolution. However, there are many difficulties in obtaining a very small probe.Spherical aberration is one of them and all existing probe forming systems have non-zero spherical aberration. The ultimate probe radius is given byδ = 0.43Csl/4ƛ3/4where ƛ is the electron wave length and it is apparent that δ decreases only slowly with decreasing Cs. Scherzer pointed out that the third order aberration coefficient always has the same sign regardless of the field distribution, provided only that the fields have cylindrical symmetry, are independent of time and no space charge is present. To overcome this problem, he proposed a corrector consisting of octupoles and quadrupoles.
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Hussein, Abbas Ibrahim, Zuryati Ab-Ghani, Ahmad Nazeer Che Mat, Nur Atikah Ab Ghani, Adam Husein, and Ismail Ab. Rahman. "Synthesis and Characterization of Spherical Calcium Carbonate Nanoparticles Derived from Cockle Shells." Applied Sciences 10, no. 20 (October 14, 2020): 7170. http://dx.doi.org/10.3390/app10207170.
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Cockle shells are a natural reservoir of calcium carbonate (CaCO3), which is widely used in bone repair, tissue scaffolds, and the development of advanced drug delivery systems. Although many studies report on the preparation of CaCO3, the development of a nanosized spherical CaCO3 precursor for calcium oxide (CaO) that is suitable to be incorporated in dental material was scarce. Therefore, this study aimed to synthesize a nanosized spherical CaCO3 precursor for CaO derived from cockle shells using a sol–gel method. Cockle shells were crushed to powder form and mixed with hydrochloric acid, forming calcium chloride (CaCl2). Potassium carbonate (K2CO3) was then fed to the diluted CaCl2 to obtain CaCO3. The effect of experimental parameters on the morphology of CaCO3, such as volume of water, type of solvents, feeding rate of K2CO3, and drying method, were investigated using field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffractometry (XRD), Brunauer–Emmett–Teller surface area analysis, and thermogravimetric analysis. Optimized CaCO3 was then calcined to form CaO. XRD analysis of CaCO3 nanoparticles was indicative of the formation of a calcite phase. The well-structured spherical shape of CaCO3 was obtained by the optimum condition of the addition of 50 mL of water into CaCl2 in ethanolic solution with a 1 h feeding rate of K2CO3. Less agglomeration of CaCO3 was obtained using a freeze-drying technique with the surface area of 26 m2/g and average particle size of 39 nm. Spherical shaped nanosized CaO (22–70 nm) was also synthesized. The reproducibility, low cost, and simplicity of the method suggest its potential applications in the large-scale synthesis of the nanoparticles, with spherical morphology in an industrial setting.
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Almgren, Mats. "Alexander Lecture 2003: Cubosomes, Vesicles, and Perforated Bilayers in Aqueous Systems of Lipids, Polymers, and Surfactants." Australian Journal of Chemistry 56, no. 10 (2003): 959. http://dx.doi.org/10.1071/ch03049.
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Cryo-Transmission Electron Microscopy (cryoTEM) is a method allowing visualization of many of the delicate structures that form by self-assembly of amphiphilic molecules in aqueous environments. The amphiphiles may be surfactants, lipids, or polymers, alone or in various mixtures. The distinctive feature of the method is that the objects are examined without staining or dehydration: This is achieved by capturing the structures in very thin aqueous films, that are subsequently vitrified at liquid nitrogen temperatures and examined using a microscope. Objects in the size range from 5 to 500 nm are well suited for the method. This includes various emulsion particles, such as liposomes, and more exotic cubosomes and hexasomes. In cryoTEM investigations perforated vesicles were found, an observation that triggered extensive studies of the nature and occurrence of such structures. As a complement to scattering methods, cryoTEM has proven its value in investigations of the size and morphology of various liposomal and vesicular systems. The microscopy studies show what type of structures that are present in the sample: uni- or multilamellar vesicles, open structures or closed defect-free vesicles, whether the form is spherical, tubular, or oblate, and so on. The scattering methods give good measures of size and polydispersity for defined systems.Three main themes are presented here. (a) Morphology of cubosomes and other emulsion particles from dispersed liquid-crystalline phases. (b) Perforated bilayers, their structure, nature, occurrence, and formation. (c) Spontaneous catanionic vesicles and their relationship to vesicles of zwitterionic lipids plus ionic surfactants.
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Jayakodi, Santhoshkumar, Hyunjin Kim, Soumya Menon, Venkat Kumar Shanmugam, Inho Choi, Medidi Raja Sekhar, Rakesh Bhaskar, and Sung Soo Han. "Preparation of Novel Nanoformulation to Enhance Efficacy in the Treatment of Cardiovascular Disease." Biomimetics 7, no. 4 (November 4, 2022): 189. http://dx.doi.org/10.3390/biomimetics7040189.
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Despite many efforts over the last few decades, cardiac-based drug delivery systems are experiencing major problems, such as the effective delivery of the precise amount of a drug. In the current study, an effort has been made to prepare a nano-herbformulation (NHF) to overcome the major problem of conventional intervention. Copper oxide-based NHF was prepared using plant extract of Alternanthera sessilis and characterized using physicochemical techniques such as Transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Dynamic light scattering (DLS), UV-Vis spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). TEM analysis revealed that spherical NHF obtained of size 20–50 nm. In addition, XRD and FTIR confirmed the presence of phytochemicals with biological properties over the surface of copper oxide-based NHF. It was demonstrated that dose-dependent antiapoptotic activity was shown against DOX-induced cardiomyocytes, where ROS levels were significantly reduced to 0.29% from 37.99%. The results of the flow cytometry analysis using PI and Annexin staining further confirmed the antiapoptotic activity of NHF against DOX-induced cardiomyocytes by ROS scavenging. Thus, NHF might be used for cardiovascular disease treatment.
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Carapeto, A. P., A. M. Ferraria, P. A. Carvalho, P. Brogueira, S. Boufi, and A. M. Botelho do Rego. "Hybrid systems of gold and silver nanoparticles generated on cellulose surfaces." Microscopy and Microanalysis 19, S4 (August 2013): 119–20. http://dx.doi.org/10.1017/s1431927613001219.
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Developing methods for immobilizing metallic nanoparticles (NP) onto different surfaces is a subject of fundamental interest, as nanometric structures enable the appearance of novel properties, absent in bulk or even in micrometric dimensions. In fact, the presence of NP with different size and shape on surfaces can induce substantial modifications on their electronic, optical, magnetic, physical or chemical proprieties. This will be very useful for many applications in different areas ranging from electronics to biomedicine.In this work, we use a simple, reproducible and economic method to grow metallic gold and silver NP directly on cellulose surfaces. A prior chemical activation of the alcohol groups on the cellulose surface is needed for grafting amino functions, which will complex silver and gold ions. Therefore, NP nucleation is only allowed and selectively accomplished on these seed coordination sites. The growth of NP is achieved by the interaction of aqueous dilute solutions of AgNO3 or NaAuCl4 with the cellulose surface. The procedure limits the generation of NP only to the cellulose surface, keeping the dispersion medium completely exempt of them. The resulting NP are, consequently chemically immobilized on the cellulose surface. The chemical anchoring of the NP to the surface avoids particle desorption and extends the lifetime of the resulting hybrid materials. Following this procedure, silver and gold NP could be successfully created on cellulose and this was supported by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM).The present AFM (Figure 1) study enabled to characterize the size and shape of silver NP: they are spherical and have a diameter of ~15 nm. SEM image of Ag NP (Figure 2) display the existence of NP agglomerates. Comparison of the two images suggests size and spatial distributions strongly non- uniform. It is now a challenge to deposit nanoparticles in an organized manner, achieving a regular surface functionalization of cellulose. In TEM (Figure 3) we see a sample where Ag and Au salts interacted simultaneously with the cellulose surface. Crossing the images with other information from analytical techniques, it seems that Ag NP and Au NP form mainly separately instead of presenting a core-shell structure. Also, there is evidence that larger NP are the ones made of silver which suggests that the final result is kinetically (and not thermodynamically) controlled.The authors acknowledge FCT for A.M. Ferraria Grant SFRH/BPD/26239/2006, for A. P. Carapeto Grant SFRH/BD/75734/2011 and strategic projects PEst-OE/CTM/LA0024/2011 and PEst-OE/CTM-UI0084/2011.
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Mohamed, HudaElslam, Unal Camdali, Atilla Biyikoglu, and Metin Aktas. "Enhancing the Performance of a Vapour Compression Refrigerator System Using R134a with a CuO/CeO2 Nano-refrigerant." Strojniški vestnik - Journal of Mechanical Engineering 68, no. 6 (June 22, 2022): 395–410. http://dx.doi.org/10.5545/sv-jme.2021.7454.
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Most studies report that dispersing nanoparticles into refrigerants and lubricating oils leads to performance improvements in refrigeration systems, due to improvements in the thermal physics properties of a pure refrigerant, which leads to reduced energy consumption. Using nanoparticles in a refrigeration system is associated with many difficulties, such as the cost of preparing and obtaining a stable and homogeneous mixture with less agglomeration and sedimentation. Most current studies focus on the use of metals, metal oxides, and a hybrid of oxides as nanoparticles in refrigeration systems. In this research, nanoparticles were prepared in an inexpensive and easy way as a single oxide and as a mixture consisting of copper and cerium oxides. The results of nanoparticle preparation using X-ray diffraction and scanning electron microscopy prove that the particles of the samples were spherical in shape, with suitable average diameters ranging from 78.95 nm, 79.9 nm, 44.15 nm and 63.3 nm for copper oxide, cerium oxide, the first mixture, and the second mixture, respectively. Cerium oxide has not been used in a refrigeration system; this study preferred the implementation of a theoretical study using Ansys Fluent software to verify the possibility of improving the performance of the refrigeration system. The results confirmed that copper oxide enhanced the coefficient of performance of the refrigeration system by 25 %, and cerium oxide succeeded in improving the performance of the. system by a lesser value. The mixture containing a higher percentage of copper oxide yielded better results.
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Ali, Muna, Kareem Mosa, Ali El-Keblawy, and Hussain Alawadhi. "Exogenous Production of Silver Nanoparticles by Tephrosia apollinea Living Plants under Drought Stress and Their Antimicrobial Activities." Nanomaterials 9, no. 12 (December 1, 2019): 1716. http://dx.doi.org/10.3390/nano9121716.
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Nanoparticle (NP) synthesis by biological systems is more cost-effective, safe, and environmentally friendly when compared to currently used chemical and physical methods. Although many studies have utilized different plant extracts to synthesize NPs, few studies have incorporated living plants. In this study, silver nanoparticles (AgNPs) were synthesized exogenously by Tephrosia apollinea living plant system under the combined stresses of silver nitrate and different levels of drought stress simulated by Polyethylene glycol (PEG) (0, −0.1, −0.2, and −0.4 MPa for three and six days). Biomass, cell death, and H2O2 content were evaluated to determine the toxicological effect of the treatments on the plant. More severe effects were detected in day 6 plants compared to day 3 plants, and at higher drought levels. UV-visible spectrum, energy dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscope, and Fourier transform infrared spectroscopy were used to detect and characterize the T. apollinea synthesized NPs. The shapes of the NPs were spherical and cubic with different phytochemicals being the possible capping agents. Broth microdilution was used to determine the antimicrobial activity of the NPs against Escherichia coli and Staphylococcus aureus. In this case, antimicrobial activity increased at higher PEG concentrations. Bactericidal effects were observed against E. coli, while only bacteriostatic effects were detected against S. aureus.
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Vu, Tri Thien, Dung Thi Nguyen, Tran Hung Nguyen, Huu Thanh Le, Dinh Duc Nguyen, and Duong Duc La. "One-Step Solution Plasma-Mediated Preparation of Se Nanoplarticles and Evaluating Their Acute Oral Toxicity in Mice." Sustainability 14, no. 16 (August 18, 2022): 10294. http://dx.doi.org/10.3390/su141610294.
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Selenium element is considered as one of the most important micronutrients for many biological systems. It has been well demonstrated that Se nanoparticles (Se NPs) express greater bioavailability, biocompatability, and less toxicity than that of Se in ion form. In this work, the Se NPs were facilely fabricated by a one-step plasma process in the ethanol–water solution mixture. The as-prepared Se NPs were well characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-vis spectroscopy, Raman spectroscopy, and energy dispersive X-ray spectroscopy (EDX). The prepared Se NPs were a light red color with a spherical shape and particle size in the range of 100–200 nm. The average diameter of the Se NPs calculated from the ImageJ software and TEM image was approximately 154 nm. The EDX results showed that the Se NPs prepared by the plasma process in the solution were highly pure and stable. The acute oral toxicity of the obtained Se NPs toward mice was also studied, which revealed that the Se NPs were safe for the human body. The mechanism for the formation of Se NPs from the Se ions under the solution plasma condition was also studied and discussed.
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Elbialy, Nihal S. "Preparation and Characterization of Curcumin Loaded Dextrin Sulfate- Chitosan Nanoparticles for Promoting Curcumin Anticancer Activity." JOURNAL OF ADVANCES IN PHYSICS 16, no. 1 (June 5, 2019): 185–95. http://dx.doi.org/10.24297/jap.v16i1.8276.
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Curcumin as a natural medicinal agent has been proved to kill cancer cells effectively. However, its biomedical applications have been hindered owing to its poor bioavailability. Many nanoparticulate systems have been introduced to overcome this problem. Among this types polymeric-based nanoparticles which exhibit unique properties allowing their use as a efficient drug carrier. Developing a polymeric- blend nanoparticles will offer a promising nanocarrier with excellent biocompatibility, biodegradability and low immunogencity.
In this study, curcumin nano-vehicle has been made up by combining dextren sulfate and chitosan (DSCSNPs). DSCSNPs have been characterized using different techniques. Transmission electron microscopy (TEM) which revealed the spherical, smooth surface of the nano-formulation. Dynamic light scattering (DLS) for measuring DSCSNPs hydrodynamic- diameter. Zeta potential measurements showed nanoparticles high stability. Fourier transform infrared spectroscopy (FTIR) confirmed successful combination between the two polymers and curcumin loading on naoparticles surface. Curcumin release profile out of DSCSNPs showed high drug release in tumor acidic microenvironment. In vitro cytotoxicity measurements demonstrated that curcumin loaded polymeric nanoparticles (DSCSNPs-Cur) have high therapeutic efficacy against colon (HCT-116) and breast (MCF-7) cancer cells compared with free curcumin. DSCSNPs as a combined biopolymers is an excellent candidate for improving curcumin bioavailability allowing its use as anticancer agent.
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Sabino, Marcos A., Onelys Sereno, and Fabio Lins Dantas. "Morphology study of alginate micro/nano particles for the encapsulation of divalents Mg2+ AND Zn2+ IONS." International Journal of Advances in Medical Biotechnology - IJAMB 1, no. 1 (March 3, 2018): 22. http://dx.doi.org/10.25061/2595-3931/ijamb/2018.v1i1.12.
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This research work aimed to promote the formation of alginic acid particles and the encapsulation of divalent ions, such as Zn2+ and Mg2+; but using a combination of internal alginate gelation and micro-emulsification method. Both ions are essential elements of the human body, i.e., they are present in tissues and body fluids and participates in many bodily functions. The influence of different parameters was evaluated relate to the formation of the particles in micro/nano-scale, and their morphology was observed. The concentration of both ions used in the formulation was varied considering [0.075, 0.15 and 0.25] mol/L. It was found in general that the formation of particles in nanoscale, with a spherical shape and smooth surfaces (also by Atomic force microscopy AFM) after characterizing by electron microscopy (Scanning SEM and Transmission TEM) with energy-dispersed analysis of X-rays (SEM/EDX). The only evidence of formation of particles at higher concentrations of the ion ([0.25] mol/L) was found when the magnesium ion was used (MgSO4) while the smallest particles (≤100nm) were formed when ZnSO4 ([0.25] mol/L) was used. The results suggest that these particles can be used as a coat or carrier for essential nutrients for food fortification, for instance, for others applications in biomedicine or charge drugs in delivery systems.
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Nikitin, Anatoly I., Vadim A. Nikitin, Alexander M. Velichko, and Tamara F. Nikitina. "Strange traces of a "strange" radiation." Radioelectronics. Nanosystems. Information Technologies. 14, no. 3 (September 19, 2022): 249–68. http://dx.doi.org/10.17725/rensit.2022.14.249.
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A review of the main works on the study of "strange" radiation is presented - an intense glow that occurs above the explosion chamber during an electric discharge of metal foils in water in it. Photographs of the most diverse structures of tracks-traces of "strange" radiation are presented. Existing hypotheses of particles that leave such traces are outlined: Lochak's magnetic monopole hypothesis, the magneto-toro-electron radiation hypothesis, the tachyon hypothesis, the hypothesis of an intermediate quasi-molecular state of paired electrons, and the "dark" hydrogen hypothesis. Numerical estimates of all discussed hypotheses are given with an explanation of the mechanism of trace formation. The hypothesis of miniature ball lightnings - multiply charged clusters - spherical clusters with a radius of 2.14·10-6 m, having a charge of 4.5·10-12 C is presented. The electric field strength on the surface of such clusters can reach up to 1010 V/m, which is comparable to the electric field strength in an atom. When such a cluster is introduced into the crystal lattice, a strong polarization of the substance is possible, which can facilitate the conditions for the approach of protons and nuclei of elements. This forces us to consider the possibility of nuclear reactions proceeding through the process of overcoming the potential barrier, which lasts for a time that is many orders of magnitude longer than the nuclear collision time in a conventional nuclear process.
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Kardar, Pooneh. "The effect of polyurethane-isophorone microcapsules on self-healing properties of an automotive clearcoat." Pigment & Resin Technology 45, no. 2 (March 7, 2016): 73–78. http://dx.doi.org/10.1108/prt-03-2015-0033.
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Purpose – The purpose of this work was to prepare a catalyst-free microcapsules as self-healing agent in an automotive clearcoat to improve the scratch resistance of coatings. Design/methodology/approach – In this research, microcapsule with isophorone diisocyanate (IDPI) core and polyurethane shell were prepared and used in self-healing coatings. Microcapsules synthesised were characterised by thermal gravimeter and infrared spectra. The microcapsules were dispersed in an acrylic-melamine clearcoat, and the scratch resistance was evaluated. Findings – The triplex product and the formed polyurethane bonds were confirmed by thermal gravimeter and infrared spectra. In addition, smooth spherical particles with a diameter of 1.5 to 1.7 micronmeters were observed by a scanning electron microscope. The microcapsules dispersed in an acrylic-melamine clearcoat increased the scratch resistance of coatings. Also, the self-healing feature of those coatings was proved. Research limitations/implications – The size of microcapsules can affect its dispersion in the clearcoat and consequently affect the properties of the cured films. Practical implications – The self-healing coatings are interested for many industries such as building and automotive industries. The reported data can be used by the formulators working in the R & D departments. Social implications – Self-healing systems are considered as one of the smart coatings. Therefore, the developing of its knowledge can help to extend its usage to different applications. Originality/value – The application of microcapsules in the coating as healing agents is a great challenge, which has been hardly investigated so far. In the current research, the effect of polyurethane-IDPI microcapsules in an automotive clearcoat as a self-healing coating was investigated.
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Singh, Manisha, Ramneek Kaur, Rashi Rajput, Shriya Agarwal, Sachin Kumar, Malvika Sharma, and Aishwarya Sharma. "Analysis of Process and Formulation Variables on Chitosan based Losartan Potassium Nanoparticles: Preparation, Validation and in vitro Release Kinetics." Recent Innovations in Chemical Engineering (Formerly Recent Patents on Chemical Engineering) 13, no. 1 (January 22, 2020): 41–54. http://dx.doi.org/10.2174/2405520412666190502161137.
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Background: Although many potential therapeutic compounds have been discovered and have exhibited a promising recovery, their effective delivery in the human system has always remained questionable with many pharmacological constraints in delivering them. Amidst all this, the concept of nanomedicine has always assured the potential to overcome the drug delivery complications in the present treatment methods. Losartan Potassium (LP) is indicated in the management of hypertension. Owing to its moderate bioavailability (32%) and a number of side effects due to the oral dosage forms of LP thus, nanoparticles based delivery would be beneficial. Objective: The present study is focused to develop a nanoparticle system of Losartan Potassium, an Angiotensin II receptor antagonist and a well-known promising antihypertensive drug, to conquer its limitation of bioavailability and potential adverse effects. Method: LP Loaded Polymeric Nanoparticles (LP-NPs) were developed by ionic gelation method using Chitosan (CH) and Tripolyphosphate (TPP) for cross linkage in various optimising ratios. After the successful optimisation and synthesis of LP-NPs, the optimised formulation was further characterized by Particle Size Analysis (PSA), Polydispersity Index (PDI), Zeta Potential (ZP), TEM analysis with the in vitro cytotoxicity and permeability evaluation. Results: The results showed the average size of 123.5 ± 1.23nm with polydispersibility score of 0.257 ± 0.079 and charge of -2.74 mV respectively. Further, Transmission Electron Microscopy (TEM) images showed the size range in almost conformity with DLS findings, representing the spherical and smooth morphology. In vitro drug release kinetics estimation showed sustained release routine of the drug and the cell viability studies done on Jurkat cell line displayed lesser cytotoxicity of LP-NPs (99.3 ± 2.28% and 98.17 ± 1.86%) in comparison with the LP only (85.3 ± 2.1% and 71.7 ± 1.07%) at different time periods (12 hours and 24 hours). Conclusion: The aforementioned results confirm the effective fabrication of LP-NPs and indicate that it may further, used on higher model systems to investigate the above parameters and their enhanced effectiveness in hypertension.
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Koch, Michel H. J., Patrice Vachette, and Dmitri I. Svergun. "Small-angle scattering: a view on the properties, structures and structural changes of biological macromolecules in solution." Quarterly Reviews of Biophysics 36, no. 2 (May 2003): 147–227. http://dx.doi.org/10.1017/s0033583503003871.
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1. Introduction 1482. Basics of X-ray and neutron scattering 1492.1 Elastic scattering of electromagnetic radiation by a single electron 1492.2 Scattering by assemblies of electrons 1512.3 Anomalous scattering and long wavelengths 1532.4 Neutron scattering 1532.5 Transmission and attenuation 1553. Small-angle scattering from solutions 1563.1 Instrumentation 1563.2 The experimental scattering pattern 1573.3 Basic scattering functions 1593.4 Global structural parameters 1613.4.1 Monodisperse systems 1613.4.2 Polydisperse systems and mixtures 1633.5 Characteristic functions 1644. Modelling 1664.1 Spherical harmonics 1664.2 Shannon sampling 1694.3 Shape determination 1704.3.1 Modelling with few parameters: molecular envelopes 1714.3.2 Modelling with many parameters: bead models 1734.4 Modelling domain structure and missing parts of high-resolution models 1784.5 Computing scattering patterns from atomic models 1844.6 Rigid-body refinement 1875. Applications 1905.1 Contrast variation studies of ribosomes 1905.2 Structural changes and catalytic activity of the allosteric enzyme ATCase 1916. Interactions between molecules in solution 2036.1 Linearizing the problem for moderate interactions: the second virial coefficient 2046.2 Determination of the structure factor 2057. Time-resolved measurements 2118. Conclusions 2159. Acknowledgements 21610. References 216A self-contained presentation of the main concepts and methods for interpretation of X-ray and neutron-scattering patterns of biological macromolecules in solution, including a reminder of the basics of X-ray and neutron scattering and a brief overview of relevant aspects of modern instrumentation, is given. For monodisperse solutions the experimental data yield the scattering intensity of the macromolecules, which depends on the contrast between the solvent and the particles as well as on their shape and internal scattering density fluctuations, and the structure factor, which is related to the interactions between macromolecules. After a brief analysis of the information content of the scattering intensity, the two main approaches for modelling the shape and/or structure of macromolecules and the global minimization schemes used in the calculations are presented. The first approach is based, in its more advanced version, on the spherical harmonics approximation and relies on few parameters, whereas the second one uses bead models with thousands of parameters. Extensions of bead modelling can be used to model domain structure and missing parts in high-resolution structures. Methods for computing the scattering patterns from atomic models including the contribution of the hydration shell are discussed and examples are given, which also illustrate that significant differences sometimes exist between crystal and solution structures. These differences are in some cases explainable in terms of rigid-body motions of parts of the structures. Results of two extensive studies – on ribosomes and on the allosteric protein aspartate transcarbamoylase – illustrate the application of the various methods. The unique bridge between equilibrium structures and thermodynamic or kinetic aspects provided by scattering techniques is illustrated by modelling of intermolecular interactions, including crystallization, based on an analysis of the structure factor and recent time-resolved work on assembly and protein folding.
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Antipina, Liubov Yu, Kristina Yu Kotyakova, Mariya V. Tregubenko, and Dmitry V. Shtansky. "Experimental and Theoretical Study of Sorption Capacity of Hexagonal Boron Nitride Nanoparticles: Implication for Wastewater Purification from Antibiotics." Nanomaterials 12, no. 18 (September 12, 2022): 3157. http://dx.doi.org/10.3390/nano12183157.
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The constant accumulation of antibiotics and their degradation products in wastewater as a result of human activity poses a serious threat to humanity and other living beings. To contribute to solving this important problem, hollow hexagonal boron nitride nanoparticles (BNNPs) with a spherical shape and smooth surface were synthesized, which were characterized as an efficient adsorbent for wastewater treatment from three types of antibiotics: ciprofloxacin (CIP), tetracycline (TC), and benzylpenicillin (BP). As follows from DFT calculations, the interaction of antibiotic molecules (AM) with the BN surface is neither purely physical nor purely chemical, and negative binding energy (BE) indicates that the adsorption process is spontaneous and endothermic. The calculated electron density redistributions at the AM/BN interfaces show that antibiotics interact with BN mainly through oxygen-containing groups. In addition, this interaction causes the BN surface to bend, which increases both the BE and the contact area. The removal efficiency of antibiotics (Re, %) depends on their initial concentration. At an initial concentration of 10 µg/mL, Re50 and Re100 were observed after 24 h and 14 days, respectively. With an increase in the initial concentration to 40 μg/mL, Re50 and Re100 were achieved after 5 and 28 days (with the exception of ciprofloxacin (~80% Re)). The maximum sorption capacity of BNNPs (qe) was determined to be 297.3 mg/g (TC), 254.8 mg/g (BP), and 238.2 mg/g (CIP), which is significantly superior to many other systems. Tetracycline is adsorbed much faster than the other two antibiotics, which is confirmed by both theoretical and experimental data. Based on the results of the DFT analysis, a simple and efficient sorbent regeneration strategy was proposed, which ensures complete removal of antibiotics after 14 (BP), 21 (TC), and 10 (CIP) days. Thus, the obtained results clearly show that BNNPs are promising sorbents for various classes of antibiotics, including aminoglycosides, tetracyclines, and β-lactams.
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Ageeva, E. V., A. Yu Altukhov, S. S. Gulidin, and A. S. Pereverzev. "ELEMENT COMPOSITION COMPARISON OF ELECTRIC-SPARK COATINGS AND ELECTROSPARKSINTERED MATERIAL." Proceedings of the Southwest State University 21, no. 2 (April 28, 2017): 6–15. http://dx.doi.org/10.21869/2223-1560-2017-21-2-6-15.
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One of the promising methods of powder obtaining practically from any conductive material, including hard alloy, characterized by relatively low energy costs and cleanliness of the process, is method electroerosion dispersion (EED). Currently there is no full information on initial composition, regimes and environment impact on the properties of disperse systems and recommendations on the effective technologies providing their sintering and hardening in the scientific and technical literature. Thus this prevents from the use of this method. For sintered parts hardening, it is helpful to use electric spark machining (ESM). ESM is technologically flexibilite, cheap and it helps to obtain coverings with a wide range of properties. However, in many cases the properties of electrospark coatings depend both on the composition, structure and properties of the electrode material, and on the properties of the substrate material. Complex theoretical and experimental studies are required to develop a complex technology for the production of disperse systems using electroerosion dispersion method and their hardening by electric spark machining, charecterised by good stress-related properties and performance. The purpose of this work is to research the elemental composition of electrospark coatings and electroerosion sintered substrates made of high-speed steel. When the experiments were set up, a metal powder was obtained from the waste of high-speed steel grade P6M5 when using a device for electroerosion dispersion of conductive materials. The resulting electroerosion powder consisted of particles of a spherical and elliptical shape measuring from 25 nm to 50 μm. The average particle size of the powder was 19.72 μm, and the specific surface area was 16725.95 cm2 / cm3. The electro-erosion powder was pressed by a hydrostatic method using an EPSI press. The powder was poured into a rubber hermetical mold then it was placed in a hydrostat working chamber where there was a liquid pressure of 300 MPa created by means of a high-lift pump. Nabertherm VHT 8/22 GR. Sintering was held in a vacuum at a temperature of 1050 ° C for 2 hours . Electrospark coatings on sintered sample material made from electroerrosion high-speed steel were produced using VK8 electrodes and UR-121 machine. Using EDAX energy-dispersive X-ray analyzer, built into QUANTA 200 3D scanning electron microscope, spectra of characteristic X-ray radiation were obtained at various points on the surface of the sample and along the cross-section. Based on the conducted studies it was established that the main elements in the electrospark coating are iron, molybdenum and tungsten, and sintering was held in a vacuum at a temperature of 1050 ° C for 2 hours . Electrospark coatings on sintered sample material made from electroerrosion high-speed steel were produced using VK8 electrodes and UR-121 machine. Using EDAX energy-dispersive X-ray analyzer, built into QUANTA 200 3D scanning electron microscope, spectra of characteristic X-ray radiation were obtained at various points on the surface of the sample and along the cross-section. Based on the conducted studies it was established that the main elements in the electrospark coating are iron, molybdenum and tungsten, and in the substrate only iron and molybdenum. the substrate only iron and molybdenum. Based on the conducted studies it was established that the main elements in the electrospark coating are iron, molybdenum and tungsten, and the main elements in the substrate are only iron and molybdenum.
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Goss, Andreas, Manuel Hernández-Pajares, Michael Schmidt, David Roma-Dollase, Eren Erdogan, and Florian Seitz. "High-Resolution Ionosphere Corrections for Single-Frequency Positioning." Remote Sensing 13, no. 1 (December 22, 2020): 12. http://dx.doi.org/10.3390/rs13010012.
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The ionosphere is one of the main error sources in positioning and navigation; thus, information about the ionosphere is mandatory for precise modern Global Navigation Satellite System (GNSS) applications. The International GNSS Service (IGS) and its Ionosphere Associated Analysis Centers (IAAC) routinely provide ionospheric information in terms of global ionosphere maps (final GIM). Typically, these products are modeled using series expansion in terms of spherical harmonics (SHs) with a maximum degree of n=15 and are based on post processed observations from Global Navigation Satellite Systems (GNSS), as well as final satellite orbits. However, precise applications such as autonomous driving or precision agriculture require real-time (RT) information about the ionospheric electron content with high spectral and spatial resolution. Ionospheric RT-GIMs are disseminated via Ntrip protocol using the SSR VTEC message of the RTCM. This message can be streamed in RT, but it is limited for the dissemination of coefficients of SHs of lower degrees only. It allows the dissemination of SH coefficients up to a degree of n=16. This suits to most the SH models of the IAACs, but higher spectral degrees or models in terms of B-spline basis functions, voxels, splines and many more cannot be considered. In addition to the SHs, several alternative approaches, e.g., B-splines or Voxels, have proven to be appropriate basis functions for modeling the ionosphere with an enhanced resolution. Providing them using the SSR VTEC message requires a transfer to SHs. In this context, the following questions are discussed based on data of a B-spline model with high spectral resolution; (1) How can the B-spline model be transformed to SHs in order to fit to the RTCM requirements and (2) what is the loss of detail when the B-spline model is converted to SHs of degree of n=16? Furthermore, we discuss (3) what is the maximum necessary SH degree n to convert the given B-spline model and (4) how can the transformation be performed to make it applicable for real-time applications? For a final assessment, we perform both, the dSTEC analysis and a single-frequency positioning in kinematic mode, using the transformed GIMs for correcting the ionospheric delay. The assessment shows that the converted GIMs with degrees n≥30 coincide with the original B-spline model and improve the positioning accuracy significantly.
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Taranukho, M. P., Yu M. Kovalyshyna, and Ye V. Zaika. "Effect of Viral Infection on the Ultrastructural Organization of Black Currant Leaf Tissue Cells." Mikrobiolohichnyi Zhurnal 84, no. 5 (February 17, 2023): 38–47. http://dx.doi.org/10.15407/microbiolj84.05.038.
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One of the significant reserves for further increasing the yield of berry crops is to protect them from pests and diseases. Among the latter, viral ones are especially dangerous. Therefore, methods of virus diagnostics and especially electron microscopy are of great importance, which makes it possible to see viral particles, determine their shape, size, localization in tissues, and identify anomalies in affected plant cells. Objective. To conduct a comparative study of healthy and diseased blackcurrant leaves in order to determine the degree of influence of the two viruses on the anatomical structure of organelles and inclusions, which can be used in the diagnosis and identifi cation of viruses affecting plants. Methods. The material was blackcurrant plants with symptoms of reversion and green speckles, which are detected visually when examining the plantings of this crop. The morphology of viral particles, the anatomical structure of organelles, and inclusions were studied using the method of electron microscopy of ultrathin sections. Detected ultrastructural changes in cells can be used as diagnostic signs when identifying viruses. Also, viruses were identified by external signs and biological testing. Results. The study of ultrathin sections of leaf tissue and abnormal petals of the blackcurrant flower with symptoms of reversion revealed a bacillus-visible virus (Blackcurrant reversion virus) from the Rabdoviridae family, which is easy to identify due to its large size and appearance, in which it differs from similar features in ordinary cellular components. Typical locations of virus particles are the cytoplasm, nucleus, and perinuclear zone. The size of viral particles on ultrathin sections was 271±7.19 nm long and 78±2.31 nm in diameter. According to electron microscopic methods of studying artificially infected plants of Chenopodium quinoa, an inoculum of affected blackcurrant leaves, virions of Cucumis virus 1 Smith were observed in cells, which were freely located in the cytoplasm of the cell interspersed with ribosomes. Individual areas of the cytoplasm with a high virus concentration were also found in the affected parenchymal cells. Zones surrounded by a double membrane differ in the size and degree of virus saturation. When studying the pathogen morphology in the native preparations, the viral particles had a spherical shape with smparticles showed that they had an average size of 29.6±0.59 nm. During the study of the ultrastructure of blackcurrant plant cells affected by Cucumis virus 1. Smith, myelin-like bodies were found not only in the cytoplasm of affected cells but also in the extra-plasma space. Analysis of the morphology of chloroplasts of blackcurrant plants affected by green speckles and reversion shows that chloroplasts with outgrowths and cup-shaped formations are present in many cells. Under various viral infections, there is a wide variety of mitochondria’s shapes: they are elongated, cup- or club-like, etc. At the same time, their internal structure changes as well. We found that at the stage of the neurotization of a Nicotiana tabacum leaf infected with Cucumis virus 1. Smith, the peroxisome matrix is intensively filled with crystalline inclusions that have an electron-dense surface or are a system of rods with different configurations in the form of rectangles and trapezoids. They completely fill the entire matrix. During the development of viral pathology in the cells of diseased plants, destructive processes also cover the nucleus. As a rule, it takes on a lobed or radially elongated shape. Among the viruses we studied, the Blackcurrant reverse virus causes this trait the most. This may be due to the fact that this virus, accumulated in large quantities, exerts mechanical pressure on the nuclei and thereby accelerates the process of their deformation. A peculiar sign of changes in the nucleus ultrastructure is the content of viral particles. Of the viruses we studied, blackcurrant reversal virus particles were the most common in the nucleus nucleoplasm and perinuclear zone. Conclusions. The intracellular development of viruses and their use of energy systems and components of plant cells for their reproduction lead to signifi cant morphological and structural changes in the latter. In particular, electron microscopic studies of ultrathin tissue sections of diseased blackcurrant plants in comparison with healthy ones revealed the forms of the nucleus, mitochondria, and plastids modified under the infl uence of viral infection, namely Blackcurrant reverse and Cucumber mosaic viruses. Chloroplasts noticeably swelled without the existing content of starch grains, and clumping or the absence of gran thylakoids was observed. Plastids with a highly reduced membrane system were found. The results of studies have shown that the species affiliation of the virus does not cause specific changes in the morphology and structure of mitochondria. Their structural transformations under the influence of the viruses under study were the same: changes in shape and swelling, expansion of crists and a decrease in their number, a decrease in the electron density of their matrix, and so on. It was found that in the nuclei of cells infected with the Blackcurrant reverse virus, chromatin forms small, interconnected granular lumps located in different zones of the matrix. When studying ultrathin sections of Nicotiana tabacum leaf infected with Cucumis virus 1. Smith, rather specific crystal inclusions that fill the entire matrix were detected by the peroxisome. If external anomalies are detected in the form of mosaics, spots that can be caused by many pathogens in the absence of mechanical transmission of the pathogen, it is advisable to use the method of electron microscopy of ultrathin sections.
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ALZUBADI, ALI A., and KHALIL H. ALBAYATI. "CALCULATION OF THEORETICAL ISOTROPIC COMPTON PROFILE FOR MANY PARTICLE SYSTEMS." Modern Physics Letters B 24, no. 14 (June 10, 2010): 1601–14. http://dx.doi.org/10.1142/s0217984910023396.
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Theoretical isotropic (spherically symmetric) Compton profiles (ICP) have been calculated for many particle systems' He , Li , Be and B atoms in their ground states. Our calculations were performed using Roothan–Hartree–Fock (RHF) wave function, HF wave function of Thakkar and re-optimized HF wave function of Clementi–Roetti, taking into account the impulse approximation. The theoretical analysis included a decomposition of the various intra and inter shells and their contributions in the total ICP. A high momentum region of up to 4 a.u. was investigated and a non-negligible tail was observed in all ICP curves. The existence of a high momentum tail was mainly due to the electron–electron interaction. The ICP for the He atom has been compared with the available experimental data and it is found that the ICP values agree very well with them. A few low order radial momentum expectation values 〈pn〉 and the total energy for these atomic systems have also been calculated and compared with their counterparts' wave functions.
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Simpson, D. G., R. L. Price, M. Terracio, L. Terracio, and T. K. Borg. "Confocal and Electron Microscopy of cultured cardiac myocytes." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 364–65. http://dx.doi.org/10.1017/s0424820100147661.
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Early in heart development cardiac myocytes are spherical in shape, intercellular junctions are distributed at irregular intervals around the periphery of the cell, and myofibrillar organization is essentially random. As myocytes mature, they undergo extensive morphogenesis during which the phenotype changes to a tubular rodlike shape, cell junctions congregate at the distal ends of cells to form intercalated disks, and myofibrils become organized in parallel arrays typical of striated muscle. Although not fully understood, it is known that these changes are a result of interactive processes between intracellular components of the cytoskeleton, integrin membrane receptors, and the extracellular matrix (ECM).In vivo studies on the process of cardiac myocyte maturation and myofibrillogenesis are difficult because of the complex biochemical environment of the intact animal and the many extra- and intracellular interactions which are required for proper development and myofibrillogenesis. Unfortunately, in previously available in vitro modelling systems, isolated myocytes spread out over the culture substratum, assume a stellate nonpolar shape, and myofibril organization remains essentially random.
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Souza, Eliane De Fátima, Milton Beltrame Jr., Erika Peterson Gonçalves, and Andreza Ribeiro Simioni. "OBTENÇÃO DE VATERITA ESTABILIZADA PARA APLICAÇÃO EM SISTEMAS DE LIBERAÇÃO CONTROLADA DE FÁRMACOS." Revista Tecnologia e Tendências 11, no. 1 (September 15, 2020): 138. http://dx.doi.org/10.25112/rtt.v11i1.2294.
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RESUMO Nas últimas décadas, avanços no campo das ciências e tecnologias aplicadas têm emergido, com pesquisas na área inovadora e multidisciplinar conhecida como nanobiotecnologia, referindo-se às tecnologias em que a matéria é manipulada às escalas atômica e molecular para criar novos materiais com características funcionais diferentes dos materiais comuns. O desenvolvimento destas tecnologias para aplicação em sistemas biológicos almeja viabilizar a utilização prática desse conhecimento nas áreas da saúde. A Terapia Fotodinâmica (TFD) se configura como uma terapia promissora para o tratamento de diversas doenças, baseado em fotoprocesso onde um fotossensibilizador é ativado por luz visível, em um comprimento de onda adequado, na presença de oxigênio molecular. Essa combinação é responsável por gerar espécies reativas de oxigênio (EROs) e oxigênio singlete, levando a morte do tecido alvo devido a uma cascata de eventos biológicos. Porém, muitos dos fotossensibilizadores apresentam baixa solubilidade em meio fisiológico, deste modo, faz-se necessária a utilização de sistema de liberação controlada. Neste âmbito, destaca-se o processo de síntese das micropartículas precipitadas de carbonato de cálcio (CaCO3) de maneira controlada, buscando favorecer a nucleação e o crescimento de um determinado polimorfo de CaCO3. O objetivo do trabalho foi controlar os parâmetros na síntese das micropartículas, como supersaturação das soluções, agitação, adição de agentes estabilizantes, buscando as condições ideais para a obtenção das micropartículas esféricas na fase de vaterita (µ-CaCO3). A avaliação dos protocolos foi assistida por microscopia eletrônica de varredura a fim de determinar o processo que atingiu a estabilização da fase de vaterita.Palavras-chave: CaCO3. Vaterita. CMC. PSS. Estabilização de fase. ABSTRACTIn the last decades, advances in the field of applied sciences and technologies have emerged, with research in the innovative and multidisciplinary area known as nanobiotechnology, referring to technologies in which matter is manipulated at the atomic and molecular scales to create new materials with different functional characteristics. common materials. The development of these technologies for application in biological systems aims to enable the practical use of this knowledge in the areas of health. Photodynamic Therapy (PDT) is a promising therapy for the treatment of various diseases, based on a photoprocess where a photosensitizer is activated by visible light, at an appropriate wavelength, in the presence of molecular oxygen. This combination is responsible for generating reactive oxygen species (ROS) and singlet oxygen, leading to the death of the target tissue due to a cascade of biological events. However, many of the photosensitizers have low solubility in a physiological environment, so it is necessary to use a controlled release system. In this context, the process of synthesis of precipitated microparticles of calcium carbonate (CaCO3) stands out in a controlled manner, seeking to favor the nucleation and the growth of a specific CaCO3 polymorph. The objective of the work was to control the parameters in the synthesis of microparticles, such as supersaturation of solutions, agitation, addition of stabilizing agents, seeking the ideal conditions for obtaining spherical microparticles in the vaterite phase (µ-CaCO3). The evaluation of the protocols was assisted by scanning electron microscopy in order to determine the process that reached the stabilization of the vaterite phase.Keywords: CaCO3. Vaterite. CMC. PSS. Phase stabilization
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Anand, Deepak, Ashish Singh Sambyal, Rakesh Vaid, and Ajit Khosla. "Fabrication of a Low Cost Triboelectric Nanogenerator (TENG) for Wearable Devices." ECS Meeting Abstracts MA2022-01, no. 57 (July 7, 2022): 2376. http://dx.doi.org/10.1149/ma2022-01572376mtgabs.
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During the last few years, considerable research has been conducted for the design and development of the self-powered devices to supply sustained power to various electronic devices by converting waste mechanical energy into useful electrical energy. Out of many energy sources available in nature, mechanical energy has attracted the researchers due to its availability in abundance. Various methods such as an electromagnetic [1], electrostatic [2] and piezoelectric [3] are being used for converting this waste mechanical energy into useful electrical energy. A novel, eco-friendly and highly reliable triboelectric nanogenerator (TENG) with low cost of fabrication has been considered for fabrication of proposed device [4]. Contact electrification process has been used at the interface of two different materials (metal and a polymer) to generate the electrical energy in the proposed TENG. In order to enhance the surface charge density of the contact electrification process, it is required that the surface area of contact should be increased by surface engineering using micro and nanostructures [5]. Many studies have shown the polymer surface engineering by various processes like template based moldings and plasma treatment [6], surface engineering on the metals like gold nanoparticles (AuNP’s) of different shapes and sizes on the other hand have shown various applications where gold have been used such as in sensors as it is highly robust against the oxygen present in the air and thus it may not get corroded or oxidized unlike other metals. With the deposition of gold nanoparticles on the surface of the metal, an improvement in the output parameters will be observed as compared with the metal without any surface engineering. Another advantage of using gold nanoparticles is that no special protection packaging is required in order to protect the TENG device because of the gold’s robustness against oxygen. The surface stability of gold nanoparticles makes them suitable in various TENG applications. In this paper, we present a very simple technique to fabricate a triboelectric nanogenerator consisting of aluminum and PDMS (Polydimethylsiloxane) layers to harvest mechanical energy present in our surroundings. The proposed TENG device is capable of generating electricity by the process of contact-separation based triboelectrification between the anodic layer of aluminum (metal) and a cathodic layer of PDMS (polymer). To improve the performance of fabricated TENG, spherical shaped gold nanoparticles were synthesized and sprayed on the metallic layer to increase its contact area by increasing the surface roughness. In order to characterize the samples, various characterization techniques has been used like FESEM (Field Emission Scanning Electron Microscopy) and EDS (Energy Dispersive X-ray Spectroscopy). With the application of static weights/ force by hand on the fabricated TENG device, an open circuit voltage of 169 mV, short circuit current of 120.4 µA and maximum output power of 6.006µW has been achieved for an applied load resistance of 68 kΩ. Further the voltage, current and power output performance of the fabricated device has been measured and studied for different load resistances. The fabricated TENG demonstrates its application in the self-powered systems and wearable devices. The deposition of gold nanoparticles (AuNP’s) on the surface of the aluminum metal results in increasing the surface charge density with an increase in the surface area of contact between the metal and the PDMS based polymer layer. The device is sandwiched and force is applied either by fingers or by the use of static weights. With the variations in the force applied, there is a variation in various parameters like open circuit voltage, short circuit current and power. From the results it has been observed that the AuNP’s based TENG generates good results in spite of the fact that the gold has inferior triboelectric coefficient as compared with other metals. The AuNP’s based TENG so fabricated shows high robustness even in very hot and humid environment. References Bin, et al. Electromagnetic Energy Harvesting from Vibrations of Multiple Frequencies. J. Micromechanics Microengineering 19, 035001 (2009). Suzuki, , Miki, D., Edamoto, M. &Honzumi, M.A MEMS Electrets Generator with Electrostatic Levitation for Vibration-Driven Energy-Harvesting Applications. J. Micromechanics Micro engineering 20, 104002 (2010). Seol, M. L. et al. Design Strategy for a Piezoelectric Nanogenerator with a Well Ordered Nano shell ACS Nano 7, 10773–10779 (2013). Li, , Sun, J. & Chen, M. Triboelectric Nanogenerator Using Nano AgInk as Electrode Material. Nano Energy 3, 95–101 (2014). Fan, -R. et al. Transparent Triboelectric Nanogenerators and Self-Powered Pressure Sensors Based on Micro patterned Plastic Films. Nano Lett. 12, 3109–3114(2012). Bai, et al .Integrated Multilayered Triboelectric Nanogenerator for Harvesting Biomechanical Energy from Human Motions. ACS Nano 7, 3713–3719 (2013). Figure 1
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Singh, Sushant, Udit Kumar, David Gittess, Tamil S. Sakthivel, Balaashwin Babu, and Sudipta Seal. "Cerium oxide nanomaterial with dual antioxidative scavenging potential: Synthesis and characterization." Journal of Biomaterials Applications, April 28, 2021, 088532822110134. http://dx.doi.org/10.1177/08853282211013451.
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Many studies have linked reactive oxygen species (ROS) to various diseases. Biomedical research has therefore sought a way to control and regulate ROS produced in biological systems. In recent years, cerium oxide nanoparticles (nanoceria, CNPs) have been pursued due to their ability to act as regenerative ROS scavengers. In particular, they are shown to have either superoxide dismutase (SOD) or catalase mimetic (CAT) potential depending on the ratio of Ce3+/Ce4+ valence states. Moreover, it has been demonstrated that SOD mimetic activity can be diminished by the presence of phosphate, which can be a problem given that many biological systems operate in a phosphate-rich environment. Herein, we report a CNP formulation with both SOD and catalase mimetic activity that is preserved in a phosphate-rich media. Characterization demonstrated a highly dispersed, stable solution of uniform-sized, spherical-elliptical shaped CNP of 12 ± 2 nm, as determined through dynamic light scattering, zeta potential, and transmission electron microscopy. Mixed valence states of Ce ions were observed via UV/Visible spectroscopy and XPS (Ce3+/Ce4+ > 1) (Ce3+∼ 62%). X-ray diffraction and XPS confirmed the presence of oxygen-deficient cerium oxide (CeO2-x) particles. Finally, the CNP demonstrated very good biocompatibility and efficient reduction of hydrogen peroxide under in-vitro conditions.
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Bennett, Gordon M., John P. McCutcheon, Bradon R. MacDonald, Dwight Romanovicz, and Nancy A. Moran. "Differential Genome Evolution Between Companion Symbionts in an Insect-Bacterial Symbiosis." mBio 5, no. 5 (September 30, 2014). http://dx.doi.org/10.1128/mbio.01697-14.
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ABSTRACTObligate symbioses with bacteria allow insects to feed on otherwise unsuitable diets. Some symbionts have extremely reduced genomes and have lost many genes considered to be essential in other bacteria. To understand how symbiont genome degeneration proceeds, we compared the genomes of symbionts in two leafhopper species,Homalodisca vitripennis(glassy-winged sharpshooter [GWSS]) andGraphocephala atropunctata(blue-green sharpshooter [BGSS]) (Hemiptera: Cicadellidae). Each host species is associated with the anciently acquired “CandidatusSulcia muelleri” (Bacteroidetes) and the more recently acquired “CandidatusBaumannia cicadellinicola” (Gammaproteobacteria). BGSS “Ca. Baumannia” retains 89 genes that are absent from GWSS “Ca. Baumannia”; these underlie central cellular functions, including cell envelope biogenesis, cellular replication, and stress response. In contrast, “Ca. Sulcia” strains differ by only a few genes. Although GWSS “Ca. Baumannia” cells are spherical or pleomorphic (a convergent trait of obligate symbionts), electron microscopy reveals that BGSS “Ca. Baumannia” maintains a rod shape, possibly due to its retention of genes involved in cell envelope biogenesis and integrity. Phylogenomic results suggest that “Ca. Baumannia” is derived from the clade consisting ofSodalisand relatives, a group that has evolved symbiotic associations with numerous insect hosts. Finally, the rates of synonymous and nonsynonymous substitutions are higher in “Ca. Baumannia” than in “Ca. Sulcia,” which may be due to a lower mutation rate in the latter. Taken together, our results suggest that the two “Ca. Baumannia” genomes represent different stages of genome reduction in which many essential functions are being lost and likely compensated by hosts. “Ca. Sulcia” exhibits much greater genome stability and slower sequence evolution, although the mechanisms underlying these differences are poorly understood.IMPORTANCEIn obligate animal-bacterial symbioses, bacteria experience extreme patterns of genome evolution, including massive gene loss and rapid evolution. However, little is known about this process, particularly in systems with complementary bacterial partners. To understand whether genome evolution impacts symbiont types equally and whether lineages follow the same evolutionary path, we sequenced the genomes of two coresident symbiotic bacteria from a plant sap-feeding insect and compared them to the symbionts from a related host species. We found that the older symbiont has a highly reduced genome with low rates of mutation and gene loss. In contrast, the younger symbiont has a larger genome that exhibits higher mutation rates and varies dramatically in the retention of genes related to cell wall biogenesis, cellular replication, and stress response. We conclude that while symbiotic bacteria evolve toward tiny genomes, this process is shaped by different selection intensities that may reflect the different ages and metabolic roles of symbiont types.
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YASSIN, GHADA E., REHAM I. AMER, and AHMED M. FAYEZ. "CARBAMAZEPINE LOADED VESICULAR STRUCTURES FOR ENHANCED BRAIN TARGETING VIA INTRANASAL ROUTE: OPTIMIZATION, IN VITRO EVALUATION, AND IN VIVO STUDY." International Journal of Applied Pharmaceutics, May 24, 2019, 264–74. http://dx.doi.org/10.22159/ijap.2019v11i4.33474.
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Objective: Carbamazepine (CBZ) is used as a first line in the treatment of grand mal and partial seizures, but it suffers from many side effects on different systems of the body. The objective of the present study was optimization of CBZ vesicular structures using 23 multifactorial design for the most efficient targeting of CBZ to the brain via the intranasal route.
Methods: The concentration of CBZ (10 and 20%), type of vesicles (niosomes and spanlastics) and speed of rotation (200 and 300 rpm) were considered as the independent variables XA, XB and XC respectively, while the dependent variables were particle size PS (Y1), polydispersity index PDI (Y2), zeta potential ZP (Y3) and entrapment efficiency EE (Y4). The study of the effect of different formulation variables was carried out using Design-Expert ® software. CBZ-loaded spanlastics and noisome were prepared by the ethanol injection method and thin film hydration method, respectively. The optimized formulation was subjected to viscosity measurement, in vitro drug release and physical stability studies. In vivo evaluations in rats for the optimized formulation in comparison to oral CBZ suspension was carried out using behavioral assessment by elevated plus maze test, determination of endothelial nitric oxide synthase (e-NOS), reduced glutathione (GSH) and ELISA estimation of TNFα.
Results: The selected optimized formulation (F0) containing 20% CBZ and spanlastic vesicular structure showed PS, PDI, ZP, and the EE % of 350.09 nm, 0.830, 16.124mV and 82.777%, respectively. In vitro release study of F0 demonstrated the ability of the F0 to increase drug release in the range time from 10-60 min (p<0.05) when compared with CBZ suspension. The viscosity of F0 was nearly uniform (65 cps). The photomicrograph taken by the transmission electron microscopy (TEM) reveals the spherical shape of F0. Good physical stability for six months of storage at 25˚ C was found for F0. The optimized spanlastic formulation F0 showed a decrease in latency time in behavior assessment test using elevated plus Maze test, a decrease in serum eNOS and TNF-α and increase in GSH when compared with the oral CBZ suspension, in addition to the histopathological study that revealed the more CBZ uptake by the brain.
Conclusion: The optimized spanlastic formulation F0 achieved better results when compared with the oral CBZ suspension for targeting the CBZ spanlastics vesicular structure to the brain via the nasal route.