Fe(III) grafted MoO3 nanorods for effective electrocatalytic fixation of atmospheric N2 to NH3

Electrocatalytic nitrogen reduction reaction (ENRR) offers a carbon-neutral process to fix nitrogen into ammonia, but its feasibility depends on the development of highly efficient electrocatalysts. Herein, we report that Fe ion grafted on MoO₃ nanorods synthesized by an impregnation technique can efficiently enhance the electron harvesting ability and the selectivity of H⁺ during the NRR process in neutral electrolyte. In 0.1 M Na₂SO₄ solution, the electrocatalyst exhibited a remarkable NRR activity with an NH₃ yield of 9.66 μg h^?1 mg^?1_cat and a Faradaic efficiency (FE) of 13.1%, far outperforming the ungrafted MnO₃. Density functional theory calculations revealed that the Fe sites are major activation centers along the alternating pathway.     

Reactive Oxygen and Nitrogen Species in Defense/Stress Responses Activated by Chitosan in Sycamore Cultured Cells

Chitosan (CHT) is a non-toxic and inexpensive compound obtained by deacetylation of chitin, the main component of the exoskeleton of arthropods as well as of the cell walls of many fungi. In agriculture CHT is used to control numerous diseases on various horticultural commodities but, although different mechanisms have been proposed, the exact mode of action of CHT is still unknown. In sycamore (Acer pseudoplatanus L.) cultured cells, CHT induces a set of defense/stress responses that includes production of H₂O₂ and nitric oxide (NO). We investigated the possible signaling role of these reactive molecules in some CHT-induced responses by means of inhibitors of production and/or scavengers. The results show that both reactive nitrogen and oxygen species are not only a mere symptom of stress conditions but are involved in the responses induced by CHT in sycamore cells. In particular, NO appears to be involved in a cell death form induced by CHT that shows apoptotic features like DNA fragmentation, increase in caspase-3-like activity and release of cytochrome c from the mitochondrion. On the contrary, reactive oxygen species (ROS) appear involved in a cell death form induced by CHT that does not show these apoptotic features but presents increase in lipid peroxidation.     

Application of differential evolution for cascaded multilevel VSI with harmonics elimination PWM switching

Harmonic elimination pulse width modulation (HEPWM) method has been widely applied to multilevel voltage source inverter (MVSI) to remove low frequency harmonics from its output voltage. However, the computation of the HEPWM switching angles for MVSI is very challenging due to several constraints, namely angle sequencing, very tight angular spacing and the numerous possibilities of angles distribution ratio. Realizing the potential of Differential Evolution (DE) to handle complex problems, this work proposes its application to solve the HEPWM problem for cascaded MVSI. Its emphasis is on improving the availability of HEPWM for higher output voltage by extending the maximum range of modulation index (M). It also removes the discontinuities in the switching angles and reduces the number of distribution ratio required to obtain the required solution. Compared to the most advanced (similar) work, i.e., 7-level MVSI with seventeen switching angles, DE covers a wider range of M; the maximum achievable M is 2.80. Furthermore, it exhibits very low second order distortion factor (DF₂): for the worst case, the value of DF₂ is 0.0014%. To verify the viability of the proposed algorithm, simulation is carried out and hardware prototype is constructed. Both results show very good agreement with the theoretical prediction.     

Quantum Sensing in a Physiological‐Like Cell Niche Using Fluorescent Nanodiamonds Embedded in Electrospun Polymer Nanofibers

Fluorescent nanodiamonds (fNDs) containing nitrogen vacancy (NV) centers are promising candidates for quantum sensing in biological environments. This work describes the fabrication and implementation of electrospun poly lactic‐co‐glycolic acid (PLGA) nanofibers embedded with fNDs for optical quantum sensing in an environment, which recapitulates the nanoscale architecture and topography of the cell niche. A protocol that produces uniformly dispersed fNDs within electrospun nanofibers is demonstrated and the resulting fibers are characterized using fluorescent microscopy and scanning electron microscopy (SEM). Optically detected magnetic resonance (ODMR) and longitudinal spin relaxometry results for fNDs and embedded fNDs are compared. A new approach for fast detection of time varying magnetic fields external to the fND embedded nanofibers is demonstrated. ODMR spectra are successfully acquired from a culture of live differentiated neural stem cells functioning as a connected neural network grown on fND embedded nanofibers. This work advances the current state of the art in quantum sensing by providing a versatile sensing platform that can be tailored to produce physiological‐like cell niches to replicate biologically relevant growth environments and fast measurement protocols for the detection of co‐ordinated endogenous signals from clinically relevant populations of electrically active neuronal circuits.     

Zinc doped Fe2O3 for boosting Electrocatalytic Nitrogen Fixation to ammonia under mild conditions

Artificial nitrogen fixation is emerging as a promising approach for synthesis of ammonia at mild conditions. Inspired by biological nitrogen fixation based on bacteria containing iron, zinc doped Fe₂O₃ nanoparticles are proposed as an efficient and earth abundant electrocatalyst for converting N₂ to NH₃. In neutral media, it achieves a maximum Faradaic efficiency (FE) of 10.4% and a large NH₃ yield rate of 15.1 μg h^?1 mg^?1_cat. at ?0.5 V vs. reversible hydrogen electrode. This catalyst also exhibits excellent selectivity and stability. Theoretical calculations suggest the reaction follows the associative enzymatic mechanism and it has a barrier of as low as 0.68 eV.     

含氮化合物对NiW体系催化剂芳烃加氢性能的影响

以γ-Al2O3、B改性的γ-Al2O3、F改性的γ-Al2O3、SiO2-Al2O3为载体制备Ni、W含量相同的四种催化剂，通过程序升温还原表征考察活性金属与不同载体的相互作用。利用氮含量不同、四氢萘含量相同的四种原料考察含氮化合物对同种NiW体系催化剂四氢萘加氢的影响以及对活性金属与载体相互作用不同的催化剂四氢萘加氢的影响。结果表明，以γ-Al2O3或SiO2-Al2O3载体制备的催化剂的金属组分与载体相互作用较强，B或F改性的γ-Al2O3能显著削弱活性金属与载体的相互作用；含氮化合物对四氢萘加氢具有强烈的抑制作用，使四氢萘加氢反应的表观活化能增加；在实验研究的四种催化剂中，金属组分与载体相互作用较弱的催化剂受含氮化合物的抑制较强。     

双室充氮包装机的技术改进

分析了原机型的性能特点和不足之处,介绍了改进方案。     

The GENIUS-test-facility—first results on background from Rn daughters

GENIUS-TF (Nucl. Instr. and Meth. A 511 (2003) 341; Nucl. Instr. and Meth. A 481 (2002) 149.) is a test-facility for the GENIUS project (GENIUS-Proposal, 20 November 1997; Z. Phys. A 359 (1997) 351; CERN Courier, November 1997, 16; J. Phys. G 24 (1998) 483; Z. Phys. A 359 (1997) 361; in: H.V. Klapdor-Kleingrothaus, H. Pas. (Eds.), First International Conference on Particle Physics Beyond the Standard Model, Castle Ringberg, Germany, 8–14 June 1997, IOP Bristol (1998) 485 and in Int. J. Mod. Phys. A 13 (1998) 3953; in: H.V. Klapdor-Kleingrothaus, I.V. Krivosheina (Eds.), Proceedings of the Second International Conference on Particle Physics Beyond the Standard Model BEYOND’ 99, Castle Ringberg, Germany 6–12 June 1999, IOP Bristol (2000) 915), a proposed large scale underground observatory for rare events which is based on operation of naked germanium detectors in liquid nitrogen for an extreme background reduction. Operation of naked Ge crystals in liquid nitrogen has been applied routinely already for more than 20 years by the CANBERRA Company for technical functions tests (CANBERRA Company, private communication, 5 March 2004.), but it never had found entrance into basic research. Only in 1997 first tests of application of this method for nuclear spectroscopy have been performed, successfully, in Heidelberg (Klapdor-Kleingrothaus et al., 1997, 1998; J. Hellmig and H.V. Klapdor-Kleingrothaus, 1997).

On May 5, 2003 the first four naked high-purity germanium detectors (total mass 10.52 kg) were installed in liquid nitrogen in the GENIUS Test Facility at the Gran Sasso underground laboratory. Since then the experiment has been running continuously, testing for the first time the novel technique in an underground laboratory and for a long-lasting period.

In this work, we present the first analysis of the GENIUS-TF background after the completion of the external shielding, which took place in December 2003. We focus especially on the background coming from ²²²Rn daughters. This is found to be at present by a factor of 200 higher than expected from simulation. It is still compatible with the scientific goal of GENIUS-TF, namely to search for cold dark matter by the modulation signal, but on the present level would cause serious problems for a full GENIUS—like experiment using liquid nitrogen.     

现代电弧炉流程钢液氮控制的试验研究

通过生产试验研究了电弧炉冶炼过程、LF精炼过程及连铸过程钢液氮的控制。研究表明，电弧炉冶炼过程主要是电弧区增氮，LF过程及连铸过程钢液增氮主要是钢液与大气接触，LF供电制度也对钢液吸氮有影响。     

Maximum Cardinality Search for Computing Minimal Triangulations of Graphs

We present a new algorithm, called MCS-M, for computing minimal triangulations of graphs. Lex-BFS, a seminal algorithm for recognizing chordal graphs, was the genesis for two other classical algorithms: LEX M and MCS. LEX M extends the fundamental concept used in Lex-BFS, resulting in an algorithm that not only recognizes chordality, but also computes a minimal triangulation of an arbitrary graph. MCS simplifies the fundamental concept used in Lex-BFS, resulting in a simpler algorithm for recognizing chordal graphs. The new algorithm MCS-M combines the extension of LEX M with the simplification of MCS, achieving all the results of LEX M in the same time complexity.