CoNi nanoparticles anchored inside carbon nanotube networks by transient heating:Low loading and high activity for oxygen reduction and evolution

Transitional metal alloy and compounds have been developed as the low cost and efficient bifunctional electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).However,a high mass loading of these catalysts is commonly needed to achieve acceptable catalytic performance,which could cause such problems as battery weight gain,mass transport blocking,and catalyst loss.We report herein the preparation of fine CoNi nanoparticles(5-6 nm)anchored inside a nitrogendoped defective carbon nanotube network(CoNi@N-DCNT)by a transient Joule heating method.When utilized as an electrocatalyst for oxygen reduction and evolution in alkaline media,the CoNi@N-DCNT film catalyst with a very low mass loading of 0.06 mg cm^(-2) showed excellent bifunctional catalytic performance.For ORR,the onset potential(Eonset)and the half-wave potential(E_(1/2))were 0.92 V versus reversible hydrogen electrode(vs.RHE)and 0.83 V(vs.RHE),respectively.For OER,the potential at the current density(J)of 10 mA cm^(-2)(E_(10))was 1.53 V,resulting in an overpotential of 300 mV much lower than that of the commercial RuO_(2) catalyst(320 mV).The potential gap between E_(1/2) and E_(10) was as small as 0.7 V.Considering the low mass loading,the mass activity at E_(10) reached at 123.2 A g^(-1),much larger than that of the RuO_(2) catalyst and literature results of transitional metal-based bifunctional catalysts.Moreover,the CoNi@N-DCNT film catalyst showed very good long-term stability during the ORR and OER test.The excellent bifunctional catalytic performance could be attributed to the synergistic effect of the bimetal alloy.

Process Adaption of a Small WWTP Operated at Low Loading Conditions for Substantial Energy Savings

The very long tradition of the activated sludge treatment model within the water industry has demonstrated very versatile possibilities to adopt the operation mode for different enhancements. By looking into other treatment models within the activated sludge family it is possible to find alternatives for the operation. This paper concentrates on the possibilities to improve even small WWTP with respect to energy savings. The small plant in Northern Sweden, called Rosvik WWTP, is given as an example. Some important findings related to the intermittent aeration mode may be summarized as follows: 1) An energy savings for the operation of the small WWTP with respect to aeration needs that resulted in a decrease of the energy power supply by more than 35%, as compared with the previous operation based on continuous aeration;2) The up to date effluent levels with respect to the main pollutants have remained at very good levels in 2020, P-level averages 0.16 mg P/l versus consent level < 0.5 mg P/l;COD-level 40 versus < 70 mg/l and BOD7 9 versus < 15 mg/l;3) Sometimes, also improved sludge settling characteristics have been observed, thus providing improved discharge figures;4) The potential to develop an enhanced biological phosphorus removal. There are however some needed conditions to accomplish these improvements: 1) Reliable on-line probes for both oxygen control, SS-concentration control and optionally also for nitrogen control;2) A flexible automation system that allows the needed process modifications to take place;3) And finally, very important dedicated and competent plant operators, with the needed curiosity for operation improvements.

Process Adaption and Modifications of a Nutrient Removing Wastewater Treatment Plant in Sri Lanka Operated at Low Loading Conditions

The Sri Lankan national water authority, that is The National Water Supply and Drainage Board (NWS&DB) has taken a new wastewater treatment plant into operation at Ja Ela, North of Colombo. The plant has been in operation since September 2011. In April 2012, it was concluded how a test of the aeration efficiency and a performance test should be carried out. The tests have been based on the actual loading of the plant and the analysis results from the daily process control. The evaluation of the aeration efficiency is not reported in this paper. The paper presents the overall performance of the water treatment part of the plant during start-up conditions, from fall 2011 through the first five months of 2012. The results from the operation are found in Table 1. An important circumstance at the plant is the current very low loading in comparison with the design load. This fact has resulted in an introduction of an intermittent mode of the aeration (nitrification) reactor. Based on operation figures, during more than a month (May 2012), it has been possible to give a realistic assessment of the overall performance. The most striking results are summarized as follows: 1) The intermittent operation has enabled an energy efficient operation of the plant. By the introduction of the intermittent aeration, the energy consumption has been reduced by around 75%, compared with the continuous operation mode;2) The plant performance during the intermittent operation has been improved with respect to virtually all important pollution variables. The most striking improvement is the discharge total P level, reflecting that a substantial enhanced biological phosphorus removal takes. The typical discharge levels found during May 2012, were compared with the earlier obtained values. It is important to underline that the loading on the plant has slightly increased during May as compared with the previous operation period.

Hydroarylation of terminal alkynes with arylboronic acids catalyzed by low loadings of palladium

The hydroarylation reaction of terminal alkynes with arylboronic acids catalyzed by low(400 ppm) loadings of palladium has been developed. The reaction is broad in scope and high-yielding, even on multigram scale. It is suitable for the synthesis of alkenes labeled with deuterium, and for the late-stage modification of bioactive molecules.

Dynamic performance of angle-steel concrete columns under low cyclic loading-II:parametric study

Tests of nine angle-steel concrete column （ASCC） specimens under low cyclic loading are described in a companion paper （Zheng and Ji, 2008）. In this paper, the skeleton curves from the numerical simulation are presented, and show good agreement with the test results. Furthermore, parametric studies are conducted to explore the influence of factors such as the axial compression ratio, shear steel plate ratio, steel ratio, prismatic concrete compression strength, yield strength of angle steel and shear span ratio, etc., on the monotonic load-displacement curves of the ASCCs. Based on a statistical analysis of the calculated results, hysteretic models for load-displacement and moment-curvature are proposed, which agree well with the test results. Finally, some suggestions concerning the conformation of ASCCs are proposed, which could be useful in engineering practice.

Ballistic Properties of Some Low Solid Loading Butalites Formulations

The ballistic properties of a low solid loading composite solid propellant family （Butalites） was studied experimentally by using propellant formulations based on hydroxy-terminated polybutadiene pre-polymer （HTPB） as fuel binder main backbone, mono and bi-modal system ammonium perchlorate oxidizer （AP）, copper chromite （CC） as burning rate accelerator and aluminum powder （A1） as metallic fuel. Higher pressures and AP contents as well as smaller AP particle size were found to increase burning rate. The same behavior verified with AI and CC addition. A significant increase of burning rate was recorded when CC added to the aluminized formulations compared with the non-aluminized of the same oxidizer solid loading and particle size.

Lightweight Design of Automobile Drive Shaft Based on the Characteristics of Low Amplitude Load Strengthening

There are two kinds of internationally recognized approaches in terms of lightweight design.One is based on fatigue accumulated damage theory to achieve better reliability by optimal structural design; another is to use high performance lightweight materials.The former method takes very few considerations on the structural strengthening effects caused by the massive small loads in service.In order to ensure safety,the design is usually conservative,but the strength potential of the component is not fully exerted.In the latter method,cost is the biggest obstacle to lightweight materials in automotive applications.For the purpose of light weighting design on a fuel cell vehicle,the new design method is applied on drive shafts.The method is based on the low amplitude load strengthening characteristics of the material,and allows the stress,corresponding to test load,to enter into the strengthened range of the material.Under this condition,the light weighting design should assure that the reliability of the shaft is not impaired,even maximizes the strength potential of machine part in order to achieve the weight reduction and eventually to reduce the cost.At last,the feasibility of the design is verified by means of strength analysis and modal analysis based on the CAD model of light weighted shaft.The design applies to the load case of half shaft in independent axle,also provides technological reference for the structural lightweight design of vehicles and other machineries.

An effective oxygen electrode based on Ir0.6Sn0.4O2 for PEM water electrolyzers

An effective oxygen evolution electrode with Ir0.6Sn0.4O2 was designed for proton exchange membrane(PEM)water electrolyzers.The anode catalyst layer exhibits a jagged structure with smaller particles and pores,which provide more active sites and mass transportation channels.The prepared IrSn electrode showed a cell voltage of 1.96 V at 2.0 A cm^-2 with Ir loading as low as 0.294 mg cm^-2.Furthermore,Ir Sn electrode with different anode catalyst loadings was investigated.The IrS n electrode indicates higher mass current and more stable cell voltage than the commercial Ir Black electrode at low loading.

Pt/Mo chalcogenide composite deriving from Pt-Mo_(6)S_8 by high temperature shock for enhanced HER performance

Highly efficient catalysts for electrolysis of water are crucial to the development of hydrogen energy which is helpful to carbon neutralization.Recently,high temperature shock(HTS),with advantage of rapid speed,universality and scalable production,has been a promising method in synthesis of nanomaterials.In this paper,HST was used to treat low Pt loading Mo_(6)S_(8)for enhanced water splitting performance.Impressively,the optimized MoS_(2)/MoO_(2)/Mo_(6)S_(8)nano-composite with low Pt mass loading(~4%)displays well hydrogen evolution reaction(HER)electrochemical performance.The overpotential is 124 mV to reach 10 mA/cm^(2)and the corresponding Tafel slope is 88 mV/dec in acidic electrolyte.Its mass activity is 6.2 mA/μg_(Pt)at-124 mV vs.RHE,which is almost 2 times relative to 20%Pt/C.Moreover,it presents distinguished stability even after 2000 cycles.This work will broaden the way of catalysts preparation and the application of hydrogen evolution.

Influence of Low Load Truncation Level on Crack Growth for Al 2324-T39 and Al 7050-T7451

Tests with middle-crack tension （M（T）） specimens made of Al 2324-T39 and Al 7050-T7451 are conducted to investigate the influence of low load truncation level on fatigue crack growth. The six different truncated spectra are obtained by removing the small cycles of which amplitudes are less than the specified percentages of the maximum amplitude in the basic flight-by-flight loading spectrum and the remainder of the spectrum is untouched. The tests indicate that the mean level of fatigue crack growth life （FCGL） increases as the load truncation level is enhanced. Considering both the time saving and the influence on FCGL, there is an applicable choice （i.e. spectrum S2 or spectrum S3 in this investigation） for full scale fatigue test. The scatter of FCGL becomes much larger than that under the basic spectrum when the load truncation level is increased to a specified high level, mainly due to the occurrence of crack slanting and branching under the high level truncated loading spectra.

A approach for generating high precision digitaltime-delay with low computational load

In this paper a novel method to generate high-precision and continuously adjustable digital time-delay by utilizing the linear phase of a FIR filter is presented. The generated time-delay can be continuously changed by adjusting the filter weights. The time-delay is pre cise and valid for wide-band, while the computational load is low. The proposed approach can find applications in wide-band digital beamforming, adaptive delay estimation, temporal analy sis of reflected waveform, etc.. In the paper, the basic principle, design steps and simulation re sults are given. Also shown are some typical practical applications.

Lateral shear performance of sheathed post-and-beam wooden structures with small panels

Sheathed post-and-beam wooden structures are distinct from light-wood structures.They allow for using sheathing panels that are smaller(0.91 m×1.82 m)than standard-sized panels(1.22 m×2.44 m or 2.44 m×2.44 m).Evidence indicates that nail spacing and panel thickness determine the lateral capacity of the wood frame shear walls.To verify the lateral shear performance of wood frame shear walls with smaller panels,we subjected 13 shear walls,measuring 0.91 m in width and 2.925 m in height,to a low-cycle cyclic loading test with three kinds of nail spacing and three panel thicknesses.A nonlinear numerical simulation analysis of the wall was conducted using ABAQUS finite element(FE)software,where a custom nonlinear spring element was used to simulate the sheathing-frame connection.The results indicate that the hysteretic performance of the walls was mainly determined by the hysteretic performance of the sheathing-frame connection.When same nail specifications were adopted,the stiffness and bearing capacity of the walls were inversely related to the nail spacing and directly related to the panel thickness.The shear wall remained in the elastic stage when the drift was 1/250 rad and ductility coefficients were all greater than 2.5,which satisfied the deformation requirements of residential structures.Based on the test and FE analysis results,the shear strength of the post-and-beam wooden structures with sheathed walls was determined.

Pomegranate micro/nano hierarchical plasma structure for superior microwave absorption

Inspired by the pomegranate natural artful structure,pomegranate micro/nano hierarchical plasma configuration of Fe/Fe3C@graphitized carbon(FFC/pCL)was constructed based on the green sol-gel method and in-situ chemical vapor deposition(CVD)synthesis protocol.Pomegranate-like FFC/pCL successfully overcame the agglomeration phenomenon of magnetic nanoparticles with each seed of the pomegranate consisting of Fe/Fe_(3)C as cores and graphitized carbon layers as shells.The high-density arrangement of magnetic nanoparticles and the design of pomegranate-like heterostructures lead to enhanced plasmon resonance.Thus,the pomegranate-like FFC/pCL achieved a great electromagnetic wave(EMW)absorbing performance of 6.12 GHz wide band absorption at a low mass adding of only 16.7 wt.%.Such excellent EMW performance can be attributed to its unique pomegranate hierarchical plasma configuration with separated nanoscale iron cores,surface porous texture,and good carbon conductive network.This investigation provides a new paradigm for the development of magnetic/carbon based EMW absorbing materials by taking advantage of pomegranate hierarchical plasma configuration.