Artykuły w czasopismach: „Boron-Nitrogen Systems”

1

Tang, Chengchun, Yoshio Bando, Chunyi Zhi i Dmitri Golberg. "Boron–oxygen luminescence centres in boron–nitrogen systems". Chemical Communications, nr 44 (2007): 4599. http://dx.doi.org/10.1039/b711807d.

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LU, ZHANG-HUI, i QIANG XU. "RECENT PROGRESS IN BORON- AND NITROGEN-BASED CHEMICAL HYDROGEN STORAGE". Functional Materials Letters 05, nr 01 (marzec 2012): 1230001. http://dx.doi.org/10.1142/s1793604712300010.

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Boron- and nitrogen-based chemical hydrogen storage materials, such as metal borohydrides, ammonia borane, hydrazine borane, metal-nitrogen-hydrogen systems, ammonia, and hydrazine, have been extensively investigated in the past years. A variety of methods have been developed to decrease the reaction temperature and enhance the reaction kinetics of these systems. This feature article is to serve as an up to date account of the recent progress in chemical hydrogen storage with the boron- and nitrogen-based materials.

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Ts, Otgontuul. "B(N) redor and B spin echo studies for structural charactreization of Si-B-N precursor ceramics". Физик сэтгүүл 18, nr 397 (15.03.2022): 76–87. http://dx.doi.org/10.22353/physics.v18i397.811.

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A Solid-state NMR spectroscopy is employed for the structural characterization oj precursorderived Si-B-C-N ceramics. Particular emphasis is given to the structural composition of the BNCx phase which plays a key role for the unusual high temperature stability of these materials. In the present work nB('5N) REDOR and B spin echo experiments are presented for two /SN enriched precursor systems, made from substituted polysilazanes and polvsilvlcarbodiimides. which provide interatomic boron-boron and boron-nitrogen distances. The obtained results are compatible with the presence of layered structures as reported for hexagonal boron nitride [h-BJ. The derived boron-nitrogen and boron-boron distances, however, are larger than in h-BN, reflecting some layer distortions. The boron-boron distances are found to decrease with increasing pyrolysis temperature, whereas the boron-nitrogen distances remain practically unaltered at elevated pyrolysis temperatures. On the basis of the present results it is concluded that intercalated BN.and sp2-carbon layers most likely constitute the BNCX. phase. The graphite-like carbon layers are assumed to create some internal pressure, which in turn is responsible for the observed interatomic distance increase in the BN layers. However, other scenarios, like the direct incorporation of small sp1-carbon domains into the BN-sheets, cannot be ruled out completely. Further work along this line appears to be necessary to develop a comprehensive structural model for the BNCxphase in such quarternarv ceramic systems.

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Favaro, M., F. Carraro, M. Cattelan, L. Colazzo, C. Durante, M. Sambi, A. Gennaro, S. Agnoli i G. Granozzi. "Multiple doping of graphene oxide foams and quantum dots: new switchable systems for oxygen reduction and water remediation". Journal of Materials Chemistry A 3, nr 27 (2015): 14334–47. http://dx.doi.org/10.1039/c5ta01561h.

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Mateti, Srikanth, Irin Sultana, Ying Chen, Manikantan Kota i Md Mokhlesur Rahman. "Boron Nitride-Based Nanomaterials: Synthesis and Application in Rechargeable Batteries". Batteries 9, nr 7 (27.06.2023): 344. http://dx.doi.org/10.3390/batteries9070344.

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Conventional boron nitride material is a resistant refractory compound of boron and nitrogen with various crystalline forms. The hexagonal form, which corresponds to graphite, is used as a lubricant and an additive to cosmetic products because of its higher stability and softness. Recently, various nanostructured boron nitride materials, including nanosheets, nanotubes, nanoparticles, and nanocomposites with diverse new properties, have been achieved through the development of advanced synthesis techniques as well as a deeper understanding of the properties and related applications. As nanostructured boron nitride materials exhibit high chemical, thermal and mechanical stability, the incorporation of nanostructured boron nitride materials into the key components (electrolytes, separators, and electrodes) of electrochemical systems can alleviate various inherent problems. This review article systematically summarizes the integration of nanostructured boron nitride into electrolytes, separators, and electrodes of lithium-ion, sodium-ion, and lithium-sulfur batteries. Various structures, synthesis methods, properties, and electrochemical performance of nanostructured boron nitride incorporated electrolytes, separators, and electrodes in rechargeable batteries are discussed. The challenges and possibilities for future application of boron nitride-based nanomaterials in electrochemical energy storage systems are also highlighted.

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Righetti, Timothy L. "Fate of Labeled Nitrogen, Zinc, and Boron in Fruit Orchard Systems". HortScience 32, nr 3 (czerwiec 1997): 556C—556. http://dx.doi.org/10.21273/hortsci.32.3.556c.

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Nitrogen, boron, and zinc are the major deficiencies encountered in Oregon tree fruit production. Much of our current management strategies are based on studies evaluating the uptake and plant mobility of labeled N, Zn, and B. Because mature trees differ from young plants, most of our experiments are conducted on fully bearing trees. Nitrogen strategies emphasize applying minimal amounts to avoid excess vigor and poor fruit quality. Our goal is to produce moderately vigorous trees with low fruit N, while still maintaining adequate tree reserves for early spring growth. Labeled 15N studies suggest that the later N is applied, the less is partitioned into leaves and fruit, with more N incorporated into storage tissues. Postharvest foliar applications of urea can also produce high bud N levels in combination with moderate vigor and low fruit N. Partitioning differences from various timings also result in different utilization efficiencies, especially if one considers N losses from pruning. Early N applications may have smaller efficiencies because pruning losses are greater. Although plant B is thought to be immobile, foliar-applied B is rapidly mobilized out of the leaf. Postharvest foliar B applications are an excellent way to ensure that buds have adequate B levels the following spring. Unlike N and B, Zn is not mobilized out of the leaf where it is applied. Sprays directly to young tissues in the spring are the only practical ways of increasing Zn levels.

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Zang, Chuan Yi, Lun Jian Chen i Li Xue Chen. "HPHT Growth and IR Characterizaton of Large Diamond Crystals in FeNi-C-FeS Systems". Advanced Materials Research 339 (wrzesień 2011): 491–95. http://dx.doi.org/10.4028/www.scientific.net/amr.339.491.

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By temperature gradient method (TGM), with Invar alloy as solvent catalyst, FeS and boron as additives, large diamond crystals are grown under high pressure and high temperature (HPHT) of about 5.4GPa and 1550K. With the content of FeS increased, the colors of grown crystals would be changed from transparent yellow to opaque gray-black, and the quality of diamond crystals could also be destroyed markedly. When both boron and FeS co-doped, the negative effect of FeS on crystal quality could be eliminated somewhat. To a certain content of FeS, with the boron content increased, the crystal color would be changed from opaque gray-black to transparent yellow, and boron content needed is related directly to FeS content in growth systems. The nitrogen content in diamond lattice decreases greatly, with FeS content increased in the growth system, and a 1050cm-1 absorption peak in IR spectrum is also present in diamond crystals grown in FeNi-FeS-C system.

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Enyashin, A. N., Yu N. Makurin i A. L. Ivanovskii. "Quantum chemical study of the electronic structure of new nanotubular systems: α-graphyne-like carbon, boron–nitrogen and boron–carbon–nitrogen nanotubes". Carbon 42, nr 10 (2004): 2081–89. http://dx.doi.org/10.1016/j.carbon.2004.04.014.

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Palmer, Michael H., i John A. Blair-Fish. "Quadrupole Coupling Assignments in Inorganic Periodic Systems by ab initio Calculation of Electric Field Gradients". Zeitschrift für Naturforschung A 49, nr 1-2 (1.02.1994): 137–45. http://dx.doi.org/10.1515/zna-1994-1-222.

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Abstract Ab initio SCF calculations were performed in the unit cell environment, making use of the periodic behaviour to compute a wave-function for the bulk material. Electric field gradient (EFG) calculations were performed on the resulting wave-functions, and these are compared with experimental quadrupole coupling parameters. Examples of inorganic molecular and ionic crystals (nitrogen, chlorine and lithium nitride) and minerals or partially covalent lattice structures (alumina, petalite, α-quartz, boron oxide, boron nitride and sulphur nitride) are described. The effects of the basis set in these calculations are considered, and the limitations imposed by the nature of the calculation are described.

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Hirai, Masato, Naoki Tanaka, Mika Sakai i Shigehiro Yamaguchi. "Structurally Constrained Boron-, Nitrogen-, Silicon-, and Phosphorus-Centered Polycyclic π-Conjugated Systems". Chemical Reviews 119, nr 14 (12.03.2019): 8291–331. http://dx.doi.org/10.1021/acs.chemrev.8b00637.

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ESFARJANI, KEIVAN, KAORU OHNO i YOSHIYUKI KAWAZOE. "ELECTRONIC PROPERTIES OF C58BN HETEROFULLERENES". Surface Review and Letters 03, nr 01 (luty 1996): 747–52. http://dx.doi.org/10.1142/s0218625x96001340.

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Recent studies of electronic structure of solid fullerenes have revealed many interesting properties of these systems. Here, we are interested in the effects of substitution of two carbon atoms by nitrogen and boron. We calculate the electronic structure of the C 58 BN cluster as well as its dispersion relation in the fcc crystalline phase. We consider the two cases where the nitrogen and the boron are neighbors and the case where they are situated far apart. In our all-electron calculation, we adopt the mixed basis approach in which we include the 1s and 2p orbitals in addition to plane waves. We investigate the existence of the donor and acceptor levels in both cases where N and B are neighbors and where they are apart. Furthermore, the electronic density in their neighborhood will be largely affected. The double bond which existed in the C 60 case is now replaced by a single bond. The consequences of substitutional doping, which is to create donor and acceptor levels and to broaden the valence and conduction bands; the anisotropy in the band dispersion; and the eventual relaxation of the nitrogen and boron atoms to a new position are also discussed.

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Liu, Ming-Yang, Qing-Yuan Chen, Tai Ma, Yao He i Chao Cao. "The electronic structure of graphene tuned by hexagonal boron nitrogen layers: Semimetal–semiconductor transition". Modern Physics Letters B 30, nr 13 (18.05.2016): 1650191. http://dx.doi.org/10.1142/s0217984916501918.

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The electronic structure of graphene and hexagonal boron nitrogen (G/h-BN) systems have been carefully investigated using the pseudo-potential plane-wave within density functional theory (DFT) framework. We find that the stacking geometries and interlayer distances significantly affect the electronic structure of G/h-BN systems. By studying four stacking geometries, we conclude that the monolayer G/h-BN systems should possess metallic electronic properties. The monolayer G/h-BN systems can be transited from metallicity to semiconductor by increasing h-BN layers. It reveals that the alteration of interlayer distances 2.50–3.50 Å can obtain the metal–semiconductor–semimetal variation and a tunable band gap for G/h-BN composite systems. The band dispersion along [Formula: see text]–[Formula: see text] direction is analogous to the band of rhombohedral graphite when the G/h-BN systems are semiconducting.

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Sumerin, Victor, Felix Schulz, Martin Nieger, Michiko Atsumi, Cong Wang, Markku Leskelä, Pekka Pyykkö, Timo Repo i Bernhard Rieger. "Experimental and theoretical treatment of hydrogen splitting and storage in boron–nitrogen systems". Journal of Organometallic Chemistry 694, nr 17 (sierpień 2009): 2654–60. http://dx.doi.org/10.1016/j.jorganchem.2009.03.023.

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Ishikawa, Masashi, Toru Nakamura, Masayuki Morita, Yoshiharu Matsuda, Sho-ichi Tsujioka i Tadayuki Kawashima. "Boron-carbon-nitrogen compounds as negative electrode matrices for rechargeable lithium battery systems". Journal of Power Sources 55, nr 1 (maj 1995): 127–30. http://dx.doi.org/10.1016/0378-7753(94)02173-z.

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Fang, Jian Hua, Bo Shui Chen, Jiu Wang i Jiang Wu. "Effect of Boron-Nitrogen Containing Modified Soybean Oil Lubricating Additive on Friction and Wear Behavior of Steel-Steel and Steel-Aluminum Alloy Systems". Applied Mechanics and Materials 380-384 (sierpień 2013): 8–11. http://dx.doi.org/10.4028/www.scientific.net/amm.380-384.8.

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A type of new environmentally friendly lube additive---boron-nitrogen modified soybean oil was synthesized and characterized by infrared spectrum. Its effect on the friction and wear behavior of steel-steel and steel-aluminum alloy systems were investigated with a four-ball machine and an Optimol SRV friction and wear tester respectively. The morphographies of the worn surfaces were analyzed by means of scanning electron microscopy (SEM).The worn surfaces of the 2024Al alloy block were analyzed by means of X-ray photoelectron spectroscopy (XPS).The results show that the type of modified soybean oil as additives can obviously decrease the wear rate and friction coefficient of steel pair and steel-aluminum frictional pair. Its lubrication mechanism is inferred that a high strength adsorption film and/or tribochemistry reaction film on the worn surface of the Al alloy due the carrier effect of a long chain soybean oil, high reaction activities of nitrogen, electron-deficient of boron and their synergisms.

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Yadav, Bhagchand, Anil Kumar Soni, Atma Ram Meena, Mahendra Jakhar i Suman Meena. "Impact of Foliar Boron and Fertilizer Management Systems on Growth, Yield and Quality of Brinjal". International Journal of Environment and Climate Change 13, nr 9 (18.07.2023): 1369–75. http://dx.doi.org/10.9734/ijecc/2023/v13i92366.

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A field experiment was conducted during the rainy season of 2017–18 at Horticulture Farm, S.K.N. Agriculture University, Jobner, Jaipur, Rajasthan to study the role of foliar spray of boron on the growth, yield, and quality of Brinjal (Solanum melongena L.) The study was laid with 18 treatments (TThree replicates of six treatments) viz., INM levels (control, 100% inorganic NPK, 75% inorganic NPK +25%VC (vermicompost), 50% inorganic NPK +50%VC, 25% inorganic NPK +75% VC, and 100%VC and boron levels (control, 100 ppm, and 200 ppm). It was observed that there was a significant (P < 0.05) increase in the plant height and plant spread at 30, 60, and 90 DAT on the application of 75% inorganic NPK +25%VC on the brinjal crop, while the application of inorganic 50% NPK +50%VC significantly (P < 0.05) increased chlorophyll content (mg.g-1), fruit length (cm), fruit weight (g), fruit yield ha-1 (q), Nitrogen and Phosphorus content in fruit (%), as compared to control but statistically at par with 25% inorganic NPK +75%VC. The application of boron (200ppm) significantly (P < 0.05) increased the plant height and plant spread at 30, 60, and 90 DAT(cm), chlorophyll content (mg/g), fruit length (cm), fruit weight (g), fruit yield hectare-1(q), NP content in fruit (%), as compared to control and boron (100 ppm).

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Nowicki, Krzysztof, Piotr Pacholak i Sergiusz Luliński. "Heteroelement Analogues of Benzoxaborole and Related Ring Expanded Systems". Molecules 26, nr 18 (8.09.2021): 5464. http://dx.doi.org/10.3390/molecules26185464.

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The review covers the chemistry of organoboron heterocycles structurally related to benzoxaboroles where one of the carbon atoms in a boracycle or a fused benzene ring is replaced by a heteroelement such as boron, silicon, tin, nitrogen, phosphorus, or iodine. Related ring expanded systems including those based on naphthalene and biphenyl cores are also described. The information on synthetic methodology as well as the basic structural and physicochemical characteristics of these emerging heterocycles is complemented by a presentation of their potential applications in organic synthesis and medicinal chemistry, the latter aspect being mostly focused on the promising antimicrobial activity of selected compounds.

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Flores Díaz, Alicia Amairani, Martha Alicia Velázquez Machuca, Adriana Medina Ramírez, José Luis Montañez Soto, José Venegas González i José Luis Pimentel Equihua. "Boron adsorption on modified zeolites: Effect of modifier and source of water". Revista Internacional de Contaminación Ambiental 39 (2.06.2023): 139–57. http://dx.doi.org/10.20937/rica.54473.

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The removal of boron from drinking water is a concern in various parts of the world due to the toxic effects of this metalloid in high concentrations. In this paper, zeolites LTL and FAU X were synthesized and modified with salts of nickel (NiCl2), iron (FeCl3), and aminopropyltriethoxysilane (APS) in order to promote their affinity for boron species present in aqueous systems. The adsorption capacity of modified zeolites for boron was evaluated in a synthetic boron solution and with groundwater samples for human use. The effect of the pH and zeolite dose was studied in adsorption tests using groundwater. The modified zeolites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen physisorption, and Fourier-transform infrared spectroscopy. Results indicated that the modification of zeolites favors affinity for boron species. The highest adsorption capacity of boron on zeolites was achieved in the synthetic solution. The adsorption capacity of the modified zeolites depended on the pH, the electrical conductivity, the modifying agent, the zeolitic structure, and the dose of adsorbent. The zeolitic structure-modifying agent interaction was decisive for boron adsorption capacity, with LTL-Ni zeolite being the best-performing adsorbent, thanks to its textural properties and nickel’s ability to form complexes with boron species.

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Larkin, Joseph D., John S. Fossey, Tony D. James, Bernard R. Brooks i Charles W. Bock. "A Computational Investigation of the Nitrogen−Boron Interaction ino-(N,N-Dialkylaminomethyl)arylboronate Systems". Journal of Physical Chemistry A 114, nr 47 (2.12.2010): 12531–39. http://dx.doi.org/10.1021/jp1087674.

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Chidchob, P., S. A. H. Jansen, S. C. J. Meskers, E. Weyandt, N. P. van Leest, B. de Bruin, A. R. A. Palmans, G. Vantomme i E. W. Meijer. "Supramolecular Systems Containing B–N Frustrated Lewis Pairs of Tris(pentafluorophenyl)borane and Triphenylamine Derivatives". Organic Materials 03, nr 02 (kwiecień 2021): 174–83. http://dx.doi.org/10.1055/s-0041-1727235.

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The introduction of a chemical additive to supramolecular polymers holds high potential in the development of new structures and functions. In this regard, various donor- and acceptor-based molecules have been applied in the design of these noncovalent polymers. However, the incorporation of boron–nitrogen frustrated Lewis pairs in such architectures is still rare despite their many intriguing properties in catalysis and materials science. The limited choices of suitable boron derivatives represent one of the main limitations for the advancement in this direction. Here, we examine the use of the commercially available tris(pentafluorophenyl)borane with various triphenylamine derivatives to create supramolecular B–N charge transfer systems. Our results highlight the importance of a proper balance between the donor/acceptor strength and the driving force for supramolecular polymerization to achieve stable, long-range ordered B–N systems. Detailed analyses using electron paramagnetic resonance and optical spectroscopy suggest that tris(pentafluorophenyl)borane displays complex behavior with the amide-based triphenylamine supramolecular polymers and may interact in dimers or larger chiral aggregates, depending on the specific structure of the triphenylamines.

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d’Amora, Marta, Adalberto Camisasca, Raul Arenal i Silvia Giordani. "In Vitro and In Vivo Biocompatibility of Boron/Nitrogen Co-Doped Carbon Nano-Onions". Nanomaterials 11, nr 11 (10.11.2021): 3017. http://dx.doi.org/10.3390/nano11113017.

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Boron/nitrogen, co-doped, carbon nano-onions (BN-CNOs) have recently shown great promise as catalysts for the oxygen reduction reaction, due to the improved electronic properties imparted by the dopant atoms; however, the interactions of BN-CNOs with biological systems have not yet been explored. In this study, we examined the toxicological profiles of BN-CNOs and oxidized BN-CNOs (oxi-BN-CNOs) in vitro in both healthy and cancer cell lines, as well as on the embryonic stages of zebrafish (Danio rerio) in vivo. The cell viabilities of both cell lines cells were not affected after treatment with different concentrations of both doped CNO derivatives. On the other hand, the analysis of BN-CNOs and oxidized BN-CNO interactions with zebrafish embryos did not report any kind of perturbations, in agreement with the in vitro results. Our results show that both doped CNO derivatives possess a high biocompatibility and biosafety in cells and more complex systems.

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Rovira, AD. "Dryland mediterranean farming systems in Australia". Australian Journal of Experimental Agriculture 32, nr 7 (1992): 801. http://dx.doi.org/10.1071/ea9920801.

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The mediterranean region of Australia extends from Geraldton in Western Australia across southern Australia into western and northern Victoria. This region experiences hot, dry summers and cool, wet winters, with 300-600 mm annual rainfall. In the dryland farming zone, the cereal-livestock farming system dominates and produces 30-35% of Australia's total agricultural production. The major soils in the region are deep, coarse-textured sands and sandy loams, duplex soils with coarse-textured sands over clay (generally low in nutrients and organic matter), and fine-textured red-brown earths of low hydraulic conductivity. Major soil problems in the region include sodicity, salinity, soil structural degradation, nutrient deficiencies, boron toxicity, acidity, waterlogging, inadequate nitrogen nutrition, water-repellence, and root diseases. These problems have been exacerbated by excessive clearing of trees, increased frequency of cropping, reduced area sown to pastures, declining pasture production, and a decline in nutrient levels. With improved soil management there is potential for increased productivity from dryland farming areas of the region and improved ecological sustainability.

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Dowbysz, Adriana, Mariola Samsonowicz i Bożena Kukfisz. "Modification of Glass/Polyester Laminates with Flame Retardants". Materials 14, nr 24 (20.12.2021): 7901. http://dx.doi.org/10.3390/ma14247901.

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This paper presents a review of flame retardants used for glass/polyester laminates. It concerns flame retardants withdrawn from use such as compounds containing halogen atoms and flame retardants currently used in the industry, such as inorganic hydroxides, phosphorus and nitrogen-containing compounds, antimony, and boron compounds, as well as tin–zinc compounds. Attention is also drawn to the use of nanoclays and the production of nanocomposites, intumescent flame retardant systems, and mats, as well as polyhedral oligomeric silsesquioxanes. The paper discusses the action mechanism of particular flame retardants and presents their advantages and disadvantages.

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Radić-Perić, J. "Thermodynamic Modelling of Boron Nitride Formation in Thermal Plasma". Materials Science Forum 518 (lipiec 2006): 349–54. http://dx.doi.org/10.4028/www.scientific.net/msf.518.349.

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The synthesis of solid BN in thermal plasma is investigated theoretically by computing the equilibrium composition of a gas mixture containing boron, nitrogen, hydrogen and argon. The calculations are done for the temperature range between 500 and 6000 K and the total pressure in the system of 1 bar. They are based on the fact that thermal plasma is in local thermodynamic equilibrium, which makes possible theoretical determination (by employing the Gibbs free energy data for the compounds present in the system) of its equilibrium composition. From the calculated compositions of investigated gas systems, the temperature zones with saturated and/or oversaturated vapour of B and B2N are determined and the formation mechanism of BN in solid state is proposed.

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Yao, Jie, Yanjie Huang, Kanghua Chang, Jianxin Nie, Xueyong Guo, Chen Shen i Shi Yan. "Preparation and Energy Release Properties of nB@F2603@CL-20 Microspheres by Electrospray". Metals 12, nr 10 (15.10.2022): 1727. http://dx.doi.org/10.3390/met12101727.

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Nano-boron, as a potential high-energy additive due to its high calorific value, is widely studied in propellants, explosives, and thermites. However, the unexpected agglomeration of surface oxidation hinders its further application, especially in the casting of energetic materials. The fluorine-modified nano-boron nB@F2603 and nB@F2603@CL-20 preagglomerated microspheres were prepared by electrospray to improve the ignition and combustion reactions and the rheological properties of boron-containing casting systems. Sphericity microspheres could be obtained by controlling the voltage and propulsion rate. The morphology and elemental distribution of the microspheres were characterized by the scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffractometer (XRD). Results showed that the particle size of the microspheres ranged from 4 to 14 µm. Boron, fluorine and nitrogen were uniformly distributed on the surface of the microspheres. XRD results showed that CL-20 in nB@F2603@CL-20 microspheres was β-crystal. The thermal reaction properties were studied by differential scanning calorimetry, thermogravimetry and mass spectrometry (TG-DSC-MS), oxygen bomb calorimeter, laser ignition, and volume combustion cell test. Results showed that F2603 could significantly promote the ignition and combustion of nano-boron, causing higher energy release and pressurization rates, and lower ignition temperature. Adding CL-20 to the microspheres could also greatly promote the reaction rates and energy release. The hydrophobicity and corrosion resistance of the structures were also studied, and results showed that the preagglomerated microspheres had good stabilities. Therefore, fluorine-containing nB@F2603 and nB@F2603@CL-20 microspheres might be used in composite energetic materials, replacing nano-boron.

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Ustun, Oguzhan, Sugra Naz Karadag, Hayrunnisa Mazlumoglu, Asli Yilmaz i Mehmet Yilmaz. "pH-Sensitive Fluorescence Emission of Boron/Nitrogen Co-Doped Carbon Quantum Dots". Coatings 13, nr 2 (17.02.2023): 456. http://dx.doi.org/10.3390/coatings13020456.

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Carbon quantum dots (CQDs) with their strong photoluminescence (PL) activity, high biocompatibility, robust stability, low cytotoxicity, and flexible surface structures have been employed in many fields including chemical sensing, biosensing, photocatalyst, energy storage, and biomedical applications. Of note, CQDs present an intrinsic pH-sensitive PL nature indicating their intense potential for pH-mediated sensing and imaging. Despite the numerous studies performed in the last two decades, the pH-sensitive PL mechanism of CQDs is still under debate and must be clarified to overcome the limitations in practical applications. Therefore, in this report, we performed a systematical study to determine the pH-sensitive PL nature of boron/nitrogen co-doped CQDs (B/N CQDs). In the first part, B/N CQDs with a strong blue emission were fabricated via a hydrothermal synthesis procedure. B/N-CQDs showed a strong blue PL emission with high quantum yield and excitation-dependent nature. Under the low pH conditions (pH 3), B/N-CQDs exhibited a robust green fluorescence emission with a significant red-shift (48 nm) and the loss of the excitation-dependent nature. The change in PL nature originated from the protonation of surface groups, a decrease in negative surface charge (from −20.6 to −1.23 eV), and finally, aggregation of the nanostructure (the size of CQDs from 4.8 to 7.5 nm). However, in the case of alkaline conditions, the deprotonation surface groups significantly enhanced the surface charge and led to the emergence of a negative ‘protective shell’ with a zeta potential of −71.3 eV. In a high pH medium (pH 13), PL spectra showed the loss of excitation-dependent features and a red-shift (35 nm) in emission peak maxima with lower intensity. This report provides significant progress in the clarification of the pH-sensitive PL mechanism of CQDs. We envision that the proposed CQDs would provide unique opportunities in the fabrication of novel pH sensor systems and fluorescence imaging where a wide range of pH sensitivity is required.

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Ali, Sadaqat, Ahmad Majdi Abdul Rani, Riaz Ahmad Mufti, Sri Hastuty, Murid Hussain, Nasir Shehzad, Zeeshan Baig i Abdul Azeez Abdu Aliyu. "An Efficient Approach for Nitrogen Diffusion and Surface Nitriding of Boron-Titanium Modified Stainless Steel Alloy for Biomedical Applications". Metals 9, nr 7 (5.07.2019): 755. http://dx.doi.org/10.3390/met9070755.

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Austenitic 316L stainless steel has been the most widely acceptable biomaterial for producing implants. The downside of this material includes the leaching of nickel ions from the matrix that limits its’ usage in implant manufacturing. In this research, production of stainless steel alloy modified with boron and titanium is investigated. The sintering of the alloy systems is carried out in nitrogen atmosphere for a dwell time of 8 h. The X-Ray diffraction (XRD) analysis reveals that dwell time and alloy composition leads to the formation of strong nitrides and borides. The X-Ray Photoelectron Spectroscopy (XPS) results show the presence of nitrogen on to the surface of sintered specimens. The nitride layer on the surface of the specimens is helpful in the retention of nickel ions in the stainless steel matrix, as indicated in the weight loss measurements. The cytotoxicity assessment indicates that the developed alloys are biocompatible and can be used as implant materials.

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Foder, Jan, Jaka Burja i Grega Klančnik. "Grain Size Evolution and Mechanical Properties of Nb, V–Nb, and Ti–Nb Boron Type S1100QL Steels". Metals 11, nr 3 (16.03.2021): 492. http://dx.doi.org/10.3390/met11030492.

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Titanium additions are often used for boron factor and primary austenite grain size control in boron high- and ultra-high-strength alloys. Due to the risk of formation of coarse TiN during solidification the addition of titanium is limited in respect to nitrogen. The risk of coarse nitrides working as non-metallic inclusions formed in the last solidification front can degrade fatigue properties and weldability of the final product. In the presented study three microalloying systems with minor additions were tested, two without any titanium addition, to evaluate grain size evolution and mechanical properties with pre-defined as-cast, hot forging, hot rolling, and off-line heat-treatment strategy to meet demands for S1100QL steel. Microstructure evolution from hot-forged to final martensitic microstructure was observed, continuous cooling transformation diagrams of non-deformed austenite were constructed for off-line heat treatment, and the mechanical properties of Nb and V–Nb were compared to Ti–Nb microalloying system with a limited titanium addition. Using the parameters in the laboratory environment all three micro-alloying systems can provide needed mechanical properties, especially the Ti–Nb system can be successfully replaced with V–Nb having the highest response in tensile properties and still obtaining satisfying toughness of 27 J at –40 °C using Charpy V-notch samples.

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Bosdet, Michael J. D., i Warren E. Piers. "B-N as a C-C substitute in aromatic systems". Canadian Journal of Chemistry 87, nr 1 (1.01.2009): 8–29. http://dx.doi.org/10.1139/v08-110.

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The substitution of isoelectronic B–N units for C–C units in aromatic hydrocarbons produces novel heterocycles with structural similarities to the all-carbon frameworks, but with fundamentally altered electronic properties and chemistry. Since the pioneering work of Dewar some 50 years ago, the relationship between B–N and C–C and the wealth of parent all-carbon aromatics has captured the imagination of organic, inorganic, materials, and computational chemists alike, particularly in recent years. New applications in biological chemistry, new materials, and novel ligands for transition-metal complexes have emerged from these studies. This review is aimed at surveying activity in the area in the past couple of decades. Its organization is based on ring size and type of the all-carbon or heterocyclic subunit that the B–N analog is derived from. Structural aspects pertaining to the retention of aromaticity are emphasized, along with delineation of significant differences in physical properties of the B–N compound as compared to the C–C parent.Key words: boron-nitrogen heterocycles, aromaticity, organic materials, main-group chemistry.

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30

Liu, Huan, Xingfa Gao i Yuliang Zhao. "Boron and Nitrogen Co-Doping of Graphynes without Inducing Empty or Doubly Filled States in π-Conjugated Systems". Journal of Physical Chemistry C 123, nr 1 (12.12.2018): 625–30. http://dx.doi.org/10.1021/acs.jpcc.8b10684.

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31

Pyykkö, Pekka, i Cong Wang. "Theoretical study of H2splitting and storage by boron–nitrogen-based systems: a bimolecular case and some qualitative aspects". Phys. Chem. Chem. Phys. 12, nr 1 (2010): 149–55. http://dx.doi.org/10.1039/b917840f.

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32

Adhikari, Dipak, Jeewan Panthee, Saurabh Lamsal, Kapil Adhikari, Narayan Prasad Adhikari i Nurapathi Pantha. "First-principles Study of Electronic and Magnetic Properties of Two-dimensional Hexagonal Boron Nitride Doped with Germanium and Tin Atoms". Journal of Institute of Science and Technology 27, nr 1 (24.08.2022): 149–58. http://dx.doi.org/10.3126/jist.v27i1.46717.

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For the study of geometrical structure, stability, and electronic and magnetic properties of Germanium and tin-doped two-dimensional hexagonal boron nitride (h-BN), First-principles calculations have been carried out. Plane-wave pseudo-potential method in association with the density functional theory (DFT) framework used in Quantum ESPRESSO codes has been implemented to perform the calculations. A 3X3 supercell size substitutional doping of a single Boron or Nitrogen atom was carried out for the study. Pristine h-BN showed non-magnetic behavior with comprehensive gap material having an indirect band gap of 4.64eV. The doping effect of Ge and Sn atoms at the B-site was energetically more favorable than N-site. The defected h-BN sheet was found to be severely distorted with remarkable alteration in bond length and angles around the defected sites. Ge doped h-BN showed semiconducting properties with a reduced band gap in comparison to the insulating nature of pristine h-BN, whereas half metallicity was noticed in Sn doped h-BN system. Both the systems showed a magnetic moment of 1.0 µB.

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33

Chen, Shenghu, Ang Xie, Xinliang Lv, Sihan Chen, Chunguang Yan, Haichang Jiang i Lijian Rong. "Tailoring Microstructure of Austenitic Stainless Steel with Improved Performance for Generation-IV Fast Reactor Application: A Review". Crystals 13, nr 2 (3.02.2023): 268. http://dx.doi.org/10.3390/cryst13020268.

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Austenitic stainless steels are selected as candidate materials for in-core and out-of-core components of Generation-IV fast reactors due to their excellent operating experience in light-water reactors over several decades. However, the performance of conventional austenitic stainless steels proves to be inadequate through operation feedback in fast reactors. To withstand the demands for material performance exposure to the extreme operating environment of fast reactors, modified austenitic stainless steels for in-core and out-of-core components have been developed from the first-generation 300-series steels. The design of an appropriate microstructure becomes a top priority for improving material performance, and key metallurgical features including δ-ferrite content, grain size and secondary phase precipitation pertinent to austenitic stainless steel are focused on in this paper. δ-ferrite content and grain size are closely correlated with the fabrication program and their effects on mechanical properties, especially creep and fatigue properties are critically assessed. Moreover, the impacts of some major elements including nitrogen, stabilization elements (Nb, Ti, V), phosphorus and boron on secondary phase precipitation behaviors during aging or creep are reviewed in detail. Based on the role of the aforementioned metallurgical features, the recommended specification of nitrogen content, stabilization ratio, phosphorus content, boron content, δ-ferrite content and grain size are put forward to guarantee the best-expected performance, which could provide reactors designers with attractive options to optimize fast reactor systems.

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34

Ali, Sadaqat, Ahmad Majdi Abdul Rani, Riaz Ahmad Mufti, Farooq I. Azam, Sri Hastuty, Zeeshan Baig, Murid Hussain i Nasir Shehzad. "The Influence of Nitrogen Absorption on Microstructure, Properties and Cytotoxicity Assessment of 316L Stainless Steel Alloy Reinforced with Boron and Niobium". Processes 7, nr 8 (2.08.2019): 506. http://dx.doi.org/10.3390/pr7080506.

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In the past, 316L stainless steel (SS) has been the material of choice for implant manufacturing. However, the leaching of nickel ions from the SS matrix limits its usefulness as an implant material. In this study, an efficient approach for controlling the leaching of ions and improving its properties is presented. The composition of SS was modified with the addition of boron and niobium, which was followed by sintering in nitrogen atmosphere for 8 h. The X-ray diffraction (XRD) results showed the formation of strong nitrides, indicating the diffusion of nitrogen into the SS matrix. The X-ray photoelectron spectroscopy (XPS) analysis revealed that a nitride layer was deposited on the sample surface, thereby helping to control the leaching of metal ions. The corrosion resistance of the alloy systems in artificial saliva solution indicated minimal weight loss, indicating improved corrosion resistance. The cytotoxicity assessment of the alloy system showed that the developed modified stainless steel alloys are compatible with living cells and can be used as implant materials.

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35

Rye, R. R., J. A. Kelber, G. E. Kellogg, K. W. Nebesny i D. L. Lichtenberger. "Localization effects in the Auger spectra of ring nitrogen systems: Pyridine, poly(2‐vinyl)pyridine, borazine, and boron nitride". Journal of Chemical Physics 86, nr 8 (15.04.1987): 4375–83. http://dx.doi.org/10.1063/1.451900.

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SamieiSoofi, Neda, i Majid Monajjemi. "(4n +2)π Huckel’s rule of Bn NnC(8-2n) H8 as anti-cancer heterocyclic systems". Revista de la Universidad del Zulia 11, nr 29 (7.02.2020): 129–50. http://dx.doi.org/10.46925//rdluz.29.09.

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Replacing of Boron and nitrogen atoms in [8] annulene molecule help us for explaining the details of mentioned magnetic mechanism concerning the ring currents of the carbon disappearing in the isoelectronic azabora-hetero-cycles variants (Bn Nn C(8-2n) H82-,n=0,1,2,3 and4 The (4n+2)π systems aromatic on variants of BnNnC(8-2n) H8 (n=0, 1 ,2,3 and 4) via the localized orbital by considering the current density induced have been studied. It has been predicted a four-electron dia-tropic (aromatic) ring current for (4n+2) π aza-bora-hetero-cycles variants of BnNnC (8-2n) H8(n=0,1 ,2,4) and a two-electron para-tropic (anti-aromatic) current for (4n) π. HOMO and LUMO energies and also HOMO/LUMO overlapping in whole space have been calculated. Two forms can be considered, first the HOMO–LUMO transition leads to a para-tropic contribution, and second HOMO–LUMO+1 transitions to the dia-tropic contributions. In addition, the NICS and SNICS values confirm the amounts of aromaticity and anti-aromaticity in those rings.

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37

Silva-Molina, R. A., R. Gámez-Corrales i R. A. Guirado-López. "Experimental and theoretical studies of Boron Nitride Nanotubes: Electric arc discharge and DFT calculations." MRS Proceedings 1479 (2012): 107–10. http://dx.doi.org/10.1557/opl.2012.1606.

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ABSTRACTWe present a joint experimental and theoretical study dedicated to analyze the properties of Boron-Nitride (BN) nanotubes. First, multi-walled boron-nitride (MWBN) nanotubes were prepared by means of a modified electric arc discharge technique using boron-nitride powder. In a first stage, the BN powder was subjected to a ball milling process for about 100 hours in an atmosphere of ammonia. Later on, BN nanoparticle formation took place after the preparation of a pressed pellet at 300 °C to 25 kPa which was sintered in a furnace at approximately 1000 °C in nitrogen atmosphere for 15 hrs. The pellets were subsequently incorporated to the electrical arc discharge set up to obtain the MWBN nanotubes. The as-prepared MWBN nanotubes samples were characterized by scanning electron microscope, X-ray photoelectron spectroscopy, and micro RAMAN spectroscopy. Second, and in order to understand the measured data, extensive density functional theory calculations were performed. We present low energy atomic configurations for model finite-length armchair, zigzag, and chiral single-walled BN nanotubes, as well as for two-dimensional BN sheets. We calculate the vibrational spectra and the optical gap of each one of our considered structures and reveal how precise details of the local atomic environment can be revealed. Finally, we consider BN nanotubes functionalized with NH2, glycine and S-H molecules. We present the structural characteristics of the adsorbed configurations, charge transfer effects, and the electronic behavior. We conclude by underlining the crucial role played by molecular functionalization in order to tune the properties of these kinds of systems.

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Shi, Zhen, i Sheng-Yuan Xia. "First-Principle Study of Rh-Doped Nitrogen Vacancy Boron Nitride Monolayer for Scavenging and Detecting SF6 Decomposition Products". Polymers 13, nr 20 (13.10.2021): 3507. http://dx.doi.org/10.3390/polym13203507.

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The scavenging and detection of sulfur hexafluoride (SF6) decomposition products (SO2, H2S, SO2F2, SOF2) critically matters to the stable and safe operation of gas-insulated switchgear (GIS) equipment. In this paper, the Rh-doped nitrogen vacancy boron nitride monolayer (Rh-VNBN) is proposed as a gas scavenger and sensor for the above products. The computational processes are applied to investigate the configurations, adsorption and sensing processes, and electronic properties in the gas/Rh-VNBN systems based on the first-principle calculations. The binding energy (Eb) of the Rh-VNBN reaches −8.437 eV, while the adsorption energy (Ead) and band gap (BG) indicate that Rh-VNBN exhibits outstanding adsorption and sensing capabilities. The density of state (DOS) analysis further explains the mechanisms of adsorption and sensing, demonstrating the potential use of Rh-VNBN in sensors and scavengers of SF6 decomposition products. This study is meaningful as it explores new gas scavengers and sensors of SF6 decomposition products to allow the operational status assessment of GIS equipment.

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39

Shi, Zhen, i Sheng-Yuan Xia. "First-Principle Study of Rh-Doped Nitrogen Vacancy Boron Nitride Monolayer for Scavenging and Detecting SF6 Decomposition Products". Polymers 13, nr 20 (13.10.2021): 3507. http://dx.doi.org/10.3390/polym13203507.

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The scavenging and detection of sulfur hexafluoride (SF6) decomposition products (SO2, H2S, SO2F2, SOF2) critically matters to the stable and safe operation of gas-insulated switchgear (GIS) equipment. In this paper, the Rh-doped nitrogen vacancy boron nitride monolayer (Rh-VNBN) is proposed as a gas scavenger and sensor for the above products. The computational processes are applied to investigate the configurations, adsorption and sensing processes, and electronic properties in the gas/Rh-VNBN systems based on the first-principle calculations. The binding energy (Eb) of the Rh-VNBN reaches −8.437 eV, while the adsorption energy (Ead) and band gap (BG) indicate that Rh-VNBN exhibits outstanding adsorption and sensing capabilities. The density of state (DOS) analysis further explains the mechanisms of adsorption and sensing, demonstrating the potential use of Rh-VNBN in sensors and scavengers of SF6 decomposition products. This study is meaningful as it explores new gas scavengers and sensors of SF6 decomposition products to allow the operational status assessment of GIS equipment.

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40

Hartman, J. Stephen, Zheng Yuan, Arnold Fox i Anh Nguyen. "Bis- and tris(amidine)fluoroboron cations and mixed tetrahaloborate anions: NMR studies of mixed boron trihalide adduct redistribution reactions involving amidines as strong nitrogen bases". Canadian Journal of Chemistry 74, nr 11 (1.11.1996): 2131–42. http://dx.doi.org/10.1139/v96-242.

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Amidines as strong Lewis bases react with amidine–mixed boron trihalide adduct systems D•BFnCl3−n (n = 0–3) in the presence of excess boron trihalide to give complex mixtures of products including the mixed tetrahaloborate anions BFnCl4−n− and the fluoroboron cations D2BF2+ and D3BF2+, which coexist with the neutral adducts D•BFnCl3−n. Excess amidine rapidly displaces chloride ion from the chlorofluoroborate anions and neutral mixed boron trihalide adducts to give high yields of the fluoroboron cations. The D3BF2+ cations of the amidines 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) and 1,5-diazabicyclo[4,3,0]non-5-ene (DBN) are inert and have been isolated as their hexafluorophosphate salts. (DBN)2BF2+ is inert and has been isolated as its hexafluorophosphate salt, but (DBU)2BF2+ is highly reactive. Key words: amidines, fluoroboron cations, mixed boron trihalide adducts, redistribution reactions, fluorine-19 NMR, boron-11 NMR, 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU), 1,5-diazabicyclo[4,3,0]non-5-ene (DBN)

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41

Makokha, Phabian, Lexa G. Matasyoh, Reuben T. Ssali, Oliver K. Kiplagat, Bramwel W. Wanjala i Jan Low. "Optimization of nutrient media for sweetpotato (Ipomoea batatas L.) vine multiplication in sandponics: Unlocking the adoption and utilization of improved varieties". Gates Open Research 2 (19.11.2018): 59. http://dx.doi.org/10.12688/gatesopenres.12879.1.

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Background: Sweetpotato, being a vegetatively propagated crop is prone to seed degeneration, and a continuous source for high quality sweetpotato seed is critical for an efficient seed system. In most Sub-Saharan African countries, the National Agricultural Research Systems use tissue culture to produce limited quantity of pre-basic sweetpotato seed which is then used as starting material to maintain and produce basic seed in mini-screen houses, net tunnels or open field multiplication in low-virus pressure areas by either the private seed companies or vine multipliers. Soil is the predominant media for pre-basic seed multiplication. Multiplying pre-basic sweetpotato seed in sand with fertigation, also known as ‘sandponics’ is a possible opportunity towards sustainable production of pre-basic sweetpotato seed. It would be beneficial to examine the feasibility and the potential to replace soil system with ‘sandponics’ for growing pre-basic sweetpotato seed. Methods: Pot experiments were conducted to study how sweetpotato vine propagation is affected by sequentially omitting nitrogen, phosphorus, calcium, sulfur and boron from fertilizer applications on cv. Kabode. The experiment was laid in a randomized complete block design with five levels of the factor fertilizer, replicated four times with two blocks. The effect of fertilization of nitrogen at (0, 100, 150, 200 & 250), phosphorus at (0, 30, 60, 90 & 120), calcium at (0, 100, 200, 300 & 400), sulfur at (0, 30, 60, 90 & 120) and boron at (0, 0.1, 0.2, 0.3 & 0.4) ppm on sweetpotato vegetative growth parameters was measured 45 days after planting. Results: The obtained results showed that application of 200, 60, 200, 120 and 0.3 ppm of N, P, Ca, S and B respectively recorded the highest values in sweetpotato vegetative growth parameters. Conclusions: These results imply that pre-basic sweetpotato vine yields in sandponics could be increased by using this optimized media.

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Kwiatkowski, Cezary A., i Elżbieta Harasim. "Chemical Properties of Soil in Four-Field Crop Rotations under Organic and Conventional Farming Systems". Agronomy 10, nr 7 (20.07.2020): 1045. http://dx.doi.org/10.3390/agronomy10071045.

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In agriculture, the farming system significantly affects chemical soil properties. The organic system, which is based among others on the use of natural (organic) fertilizers, promotes increased soil contents of humus, organic C, and micronutrients. The conventional system, in turn, may cause soil acidification if high rates of mineral (particularly nitrogen) fertilization are used. The crop plant species also modifies soil chemistry by providing different (quantitatively and qualitatively) crop residues. The study was conducted over the period 2013–2016 in Czesławice (Lublin Region, Poland). The aim of this study was to determine the content of some chemical components determining the quality of loess soil on which four plant species were grown under organic and conventional farming systems. This research involved the determination of some parameters of the chemical composition of the soil: soil pH, total sorption capacity, humus content, macronutrient (P, K, Mg) and micronutrient (B, Cu, Mn, Zn) content, organic carbon, and total nitrogen content. The content of different forms of nitrogen, N-NO3 and N-NH4, was also determined. The experimental design included two crop rotations (organic and conventional) in which identical plant species were grown: potato—winter wheat—field bean—spring barley. The experiment was established on loess soil with the grain size distribution of silt loam and classified as good wheat soil complex (soil class II). It was carried out as a split-plot design in three replicates, and the area of a single plot was 80 m2. Soil samples were taken using a soil sampling tube from an area of 0.20 m2 (from the 0–25 cm layer) in each plot at the end of the growing season of the specific crops grown. Over the four year study period, it was found that the organic system contributed to an increased soil content of magnesium, boron, copper, manganese, zinc, organic carbon, and total nitrogen. Moreover, organic cropping promoted more favorable soil pH and higher soil humus content. Organic cropping significantly improved the total sorption capacity of the soil compared to conventional cultivation. Moreover, the organic system contributed to a higher soil content of nitrogen in the form of N-NH4 and its lower content in the form of N-NO3. Under the conventional system, in turn, a higher soil phosphorus and potassium content was observed. To sum up, the study confirmed the assumed hypothesis that the organic farming system would contribute to an improvement in the chemical quality indicators of loess soil. Regardless of the cropping system, potato and field bean had the most beneficial effect on soil chemistry, whereas cereal crops showed the weakest effect. Winter wheat and spring barley had an effect on significantly lower total sorption capacity of the soil and a significantly lower soil content of N-NO3 and N-NH4.

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Rakhmanova, Mariana I., Andrey Yu Komarovskikh, Yuri N. Palyanov, Alexander A. Kalinin, Olga P. Yuryeva i Vladimir A. Nadolinny. "Diamonds from the Mir Pipe (Yakutia): Spectroscopic Features and Annealing Studies". Crystals 11, nr 4 (31.03.2021): 366. http://dx.doi.org/10.3390/cryst11040366.

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For this study, 21 samples of colorless octahedral diamonds (weighing 5.4–55.0 mg) from the Mir pipe (Yakutia) were investigated with photoluminescence (PL), infrared (IR), and electron paramagnetic resonance (EPR) spectroscopies. Based on the IR data, three groups of diamonds belonging to types IIa, IaAB, and IaB were selected and their spectroscopic features were analyzed in detail. The three categories of stones exhibited different characteristic PL systems. The type IaB diamonds demonstrated dominating nitrogen–nickel complexes S2, S3, and 523 nm, while they were less intensive or even absent in the type IaAB crystals. The type IIa diamonds showed a double peak at 417.4 + 418.7 nm (the 418 center in this study), which is assumed to be a nickel–boron defect. In the crystals analyzed, no matter which type, 490.7, 563.5, 613, and 676.3 nm systems of various intensity could be detected; moreover, N3, H3, and H4 centers were very common. The step-by-step annealing experiments were performed in the temperature range of 600–1700 °C. The treatment at 600 °C resulted in the 563.5 nm system’s disappearance; the interstitial carbon vacancy annihilation could be considered as a reason. The 676.5 nm and 613 nm defects annealed out at 1500 °C and 1700 °C, respectively. Furthermore, as a result of annealing at 1500 °C, the 558.5 and 576 nm centers characteristic of superdeep diamonds from São Luis (Brazil) appeared. These transformations could be explained by nitrogen diffusion or interaction with the dislocations and/or vacancies produced.

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Mohan, Hugh, Valeria Bincoletto, Silvia Arpicco i Silvia Giordani. "Supramolecular Functionalisation of B/N Co-Doped Carbon Nano-Onions for Novel Nanocarrier Systems". Materials 15, nr 17 (30.08.2022): 5987. http://dx.doi.org/10.3390/ma15175987.

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Boron/nitrogen co-doped carbon nano-onions (BN-CNOs) are spherical nanoparticles that consist of multiple inter-nestled fullerene layers, giving them an onion-like internal structure. They have potential as nanocarriers due to their small size, aqueous dispersibility, and biocompatibility. The non-covalent attachment of a biocompatible polymer to BN-CNOs is a simple and effective method of creating a scaffold for a novel nanocarrier system as it allows for increased aqueous dispersibility whilst preventing the immune system from recognising the particle as a foreign object. The non-covalent approach also preserves the electronic and structural properties of the BN-CNOs. In this study, we attached a hyaluronic acid-phospholipid (HA-DMPE) conjugate polymer to the BN-CNO’s surface to improve its hydrophilicity and provide targetability toward HA-receptor overexpressing cancer cells. To this end, various ratios of HA-DMPE to BN-CNOs were investigated. The resulting supramolecular systems were characterised via UV-Vis absorption and FTIR spectroscopy, dynamic light scattering, and zeta potential techniques. It was found that the HA-DMPE conjugate polymer was permanently wrapped around the BN-CNO nanoparticle surface. Moreover, the resulting BN-CNO/HA-DMPE supramolecular systems displayed enhanced aqueous solubility compared to unfunctionalised BN-CNOs, with excellent long-term stability observed in aqueous dispersions.

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Liu, Chun, Tieling Xing, Bingju Wei i Guoqiang Chen. "Synergistic Effects and Mechanism of Modified Silica Sol Flame Retardant Systems on Silk Fabric". Materials 11, nr 10 (27.09.2018): 1842. http://dx.doi.org/10.3390/ma11101842.

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The nano-silica sol was prepared by sol-gel method, and the boric acid, urea, cyanoguanidine, melamine cyanurate (MCA), 1-hydroxyethane 1,1-diphosphonic acid (HEDP), and 6H-dibenz (C,E) (1,2) oxaphosphorin-6-oxide (DOPO) were added to the silica sol to modify the flame retardant through physical doping and chemical bonding. According to the formula proposed by Lewin, the calculation of flammability parameters were obtained by the limiting oxygen index meter, the micro calorimeter, the vertical burner, and the thermogravimetric analyzer proved that there was a synergistic or additive effect between the B/N/P flame retardant and the silica sol. Fourier transform infrared (FT-IR) spectrum, scanning electron microscopy, and pyrolysis gas chromatography-mass spectrometry were used to characterize the morphology, structure, and pyrolysis products of treated silk fabric and residues after combustion. The results show that the flame retardancy of silica-boron sol is mainly caused by endothermic reaction and melt covering reaction. Silicon-nitrogen sol acts as a flame retardant through endothermic reaction, release of gases, and melting coverage. Silicon-phosphorus sol achieves flame retardancy by forming an acid to promote formation of a carbon layer and melting coverage. Silica sol and other flame retardants show excellent flame retardanty after compounding, and have certain complementarity, which can balance the dosage, performance, and cost of flame retardants, and is more suitable for industrial development.

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46

Ryan, M. H., D. R. Small i J. E. Ash. "Phosphorus controls the level of colonisation by arbuscular mycorrhizal fungi in conventional and biodynamic irrigated dairy pastures". Australian Journal of Experimental Agriculture 40, nr 5 (2000): 663. http://dx.doi.org/10.1071/ea99005.

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The broad-scale factors determining the level of colonisation by arbuscular mycorrhizal fungi in irrigated permanent pasture were investigated using 10 pairs of dairy farms located in northern Victoria, Australia. Each pair consisted of adjacent farms, one under conventional management and the other under biodynamic management. Significant quantities of fertilisers were applied only to the conventional pastures and this was the major difference in inputs between the 2 management systems. Colonisation by arbuscular mycorrhizal fungi of white clover (Trifolium repens L.), perennial ryegrass (Lolium perenne L.) and paspalum (Paspalum dilatatum Poir.) was lower in the conventionally managed pastures than in the biodynamic pastures. On all farms, clover was more highly colonised than the grasses. The level of colonisation in clover exhibited a strong negative relationship with the concentration of phosphorus in the pasture shoots and a weak negative correlation with soil-extractable phosphorus. Similar relationships were evident for the grasses, but these were not as strong. Soil pH, soil organic carbon and the concentration of other soil nutrients (Kjeldahl nitrogen, sulfate, EDTA copper, EDTA zinc, chlorine, and exchangeable potassium, sodium, calcium and magnesium) and pasture shoot nutrients (chlorine, sodium, potassium, calcium, magnesium, manganese, copper, zinc, iron, nitrogen, sulfur and boron) could not account for differences in colonisation levels. On 3 farm pairs, colonisation levels by arbuscular mycorrhizal fungi were monitored over 3.5 years. Colonisation did not vary seasonally. It is concluded that phosphorus levels and host plant will be the major determinants of colonisation levels by arbuscular mycorrhizal fungi in perennial irrigated pasture-based agricultural systems.

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Kurasch, Simon, Jannik C. Meyer, Daniela Künzel, Axel Groß i Ute Kaiser. "Simulation of bonding effects in HRTEM images of light element materials". Beilstein Journal of Nanotechnology 2 (19.07.2011): 394–404. http://dx.doi.org/10.3762/bjnano.2.45.

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The accuracy of multislice high-resolution transmission electron microscopy (HRTEM) simulation can be improved by calculating the scattering potential using density functional theory (DFT) Gemming, T.; Möbus, G.; Exner, M.; Ernst, F.; Rühle, M. J. Microsc. 1998, 190, 89–98. doi:10.1046/j.1365-2818.1998.3110863.xDeng, B.; Marks, L. D. Acta Crystallogr., Sect. A 2006, 62, 208–216. doi:10.1107/S010876730601004X. This approach accounts for the fact that electrons in the specimen are redistributed according to their local chemical environment. This influences the scattering process and alters the absolute and relative contrast in the final image. For light element materials with well defined geometry, such as graphene and hexagonal boron nitride monolayers, the DFT based simulation scheme turned out to be necessary to prevent misinterpretation of weak signals, such as the identification of nitrogen substitutions in a graphene network. Furthermore, this implies that the HRTEM image does not only contain structural information (atom positions and atomic numbers). Instead, information on the electron charge distribution can be gained in addition. In order to produce meaningful results, the new input parameters need to be chosen carefully. Here we present details of the simulation process and discuss the influence of the main parameters on the final result. Furthermore we apply the simulation scheme to three model systems: A single atom boron and a single atom oxygen substitution in graphene and an oxygen adatom on graphene.

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Salahin, Nazmus, Md Khairul Alam, Nirmal Chandra Shil, Abu Taher Mohammad Anwarul Islam Mondol, Md Jahangir Alam, Mohamed I. Kobeasy, Ahmed Gaber i Sharif Ahmed. "Interactive Effects of Tillage Systems and Nitrogen Fertilizer Rates on the Performance of Mustard-Boro-aman Rice Cropping Systems under Conservation Agriculture Practices". Agronomy 12, nr 7 (13.07.2022): 1671. http://dx.doi.org/10.3390/agronomy12071671.

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In intensive crop production systems, sustainable agricultural development strives to find the balance between productivity and environmental impact. To reduce the N fertilizer-associated environmental risks of intensive cropping, sound agronomic and environmentally acceptable management practices are urgently needed. To attain high yields, improve soil health, and ensure economic return and N usage efficiency in conservation-based intensive agriculture, N management must be optimized, which has not yet been studied systematically in the mustard-boro rice-aman rice cropping pattern. During 2016/17, 2017/18, and 2018/19 cropping seasons in Bangladesh, cropping system experiments were conducted to investigate the interactive effects of tillage practices and nitrogen fertilizer rates on soil characteristics, crop productivity, and profitability under conservation agriculture (CA) systems. The trial featured two tillage systems: (i) conventional tillage (CT) and (ii) strip-tillage (ST). It also used three doses of N fertilizer: N1: 75% of the recommended N fertilizer dose (RND); N2: 100% of the RND; and N3: 125% of the RND. Each crop’s experiment was set up in a split-plot design with three replications, with the main plot assigned tillage practices and the sub-plot assigned nitrogen fertilizer rates. For rice, neither the tillage systems nor the interactions between the tillage systems and N levels affected any of the growth parameters, yield, and yield components, but the N levels did. Across the tillage systems, the rice grain and straw yield were similar for the N levels of 100% RND and 125% RND, which were significantly higher than the N level of 75% RND. In mustard, the highest seed yield was recorded from the tillage system ST, with an N level of 125% RND, which was at par with the tillage system ST with 100% RND and CT with 125% RND. The highest system rice equivalent yield (SREY, 14.9 to 15.8 t ha−1) was recorded from the tillage system ST, with an N level of 125% RND, which was at par with the same tillage system with an N level of 100% RND. The soil penetration and bulk density (BD) were higher for the CT than the ST, but soil organic matter (OM), total nitrogen (TN), phosphorus (P), potassium (K), and boron (B) content were higher for the tillage system ST than the CT. Across N levels, the tillage system CT had a 2–4% higher production cost than the ST. Total production cost increased as N levels increased across all tillage systems. The tillage system ST with an N level of 125% RND had the highest system gross return and net profit, which was at par with the same tillage system with 100% RND. This study suggested that farmers should apply slightly higher N for the mustard-boro-aman rice systems for the first couple of years when commencing CA; however, after a few years of consistent CA practice, the N rate may be reduced.

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Rezvani Ghomi, Erfan, Fatemeh Khosravi, Zahra Mossayebi, Ali Saedi Ardahaei, Fatemeh Morshedi Dehaghi, Masoud Khorasani, Rasoul Esmaeely Neisiany i in. "The Flame Retardancy of Polyethylene Composites: From Fundamental Concepts to Nanocomposites". Molecules 25, nr 21 (5.11.2020): 5157. http://dx.doi.org/10.3390/molecules25215157.

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Polyethylene (PE) is one the most used plastics worldwide for a wide range of applications due to its good mechanical and chemical resistance, low density, cost efficiency, ease of processability, non-reactivity, low toxicity, good electric insulation, and good functionality. However, its high flammability and rapid flame spread pose dangers for certain applications. Therefore, different flame-retardant (FR) additives are incorporated into PE to increase its flame retardancy. In this review article, research papers from the past 10 years on the flame retardancy of PE systems are comprehensively reviewed and classified based on the additive sources. The FR additives are classified in well-known FR families, including phosphorous, melamine, nitrogen, inorganic hydroxides, boron, and silicon. The mechanism of fire retardance in each family is pinpointed. In addition to the efficiency of each FR in increasing the flame retardancy, its impact on the mechanical properties of the PE system is also discussed. Most of the FRs can decrease the heat release rate (HRR) of the PE products and simultaneously maintains the mechanical properties in appropriate ratios. Based on the literature, inorganic hydroxide seems to be used more in PE systems compared to other families. Finally, the role of nanotechnology for more efficient FR-PE systems is discussed and recommendations are given on implementing strategies that could help incorporate flame retardancy in the circular economy model.

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Begg, J. S., R. L. Lavigne i P. L. M. Veneman. "Reed beds: constructed wetlands for municipal wastewater treatment plant sludge dewatering". Water Science and Technology 44, nr 11-12 (1.12.2001): 393–98. http://dx.doi.org/10.2166/wst.2001.0857.

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Reed beds are an alternative technology wastewater treatment system that mimic the biogeochemical processes inherent in natural wetlands. The purpose of this project was to determine the effectiveness of a reed bed sludge treatment system (RBSTS) in southern New England after a six-year period of operation by examining the concentrations of selected metals in the reed bed sludge biomass and by determining the fate of solids and selected nutrients. Parameters assessed in both the reed bed influent and effluent: total suspended solids, biochemical oxygen demand, nitrate-nitrogen and total phosphorus. In addition, the following metals were studied in the reed bed influent, effluent and Phragmites plant tissue and the sludge core biomass: boron, cadmium, chromium, copper, iron, lead, manganese, molybdenum, nickel, and zinc. The removal efficiencies for sludge dewatering, total suspended solids and biochemical oxygen demand were all over 90%. Nitrate and total phosphorus removal rates were 90% and 80% respectively. Overall metals removal efficient was 87%. Copper was the only metal in the sludge biomass that exceeded the standards set by the Massachusetts Department of Environmental Protection for land disposal of sludge. The highest metal concentrations, for the most part, tended to be in the lower tier of the sludge profile. The exception was boron, which was more concentrated in the middle tier of the sludge profile. The data and results presented in this paper support the notion that reed bed sludge treatment systems and the use of reed beds provide an efficient and cost effective alternative for municipal sludge treatment.

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