Quantum Mechanical Investigation of the Oxidative Cleavage of the C–C Backbone Bonds in Polyethylene Model Molecules

Recalcitrant plastic waste has caused serious global ecological problems. There is an urgent need to develop environmentally friendly and efficient methods for degrading the highly stable carbon skeleton structure of plastics. To that end, we used a quantum mechanical calculation to thoroughly investigate the oxidative scission of the carbon-carbon (C–C) backbone in polyethylene (PE). Here, we studied the reaction path of C–C bond oxidation via hydroxyl radical in PE. The flexible force constants and fuzzy bond orders of the C–C bonds were calculated in the presence of one or more carbocations in the same PE carbon chain. By comparison, the strength of the C–C bond decreased when carbocation density increased. However, the higher the density of carbocations, the higher the total energy of the molecule and the more difficult it was to be generated. The results revealed that PE oxidized to alcohol and other products, such as carboxylic acid, aldehyde and ketone, etc. Moreover, the presence of carbocations was seen to promote the cleavage of C–C backbones in the absence of oxygen.

Mechanical Calculation of Flexible Wires Taking into Account Taps to Electrical Apparatuses

A method is proposed for the mechanical calculation of flexible wires of substation in the presence of one tap to an electrical apparatus located in the middle of the span, taking into account its real location. The technique takes into account the presence of tension insulators strings, different heights of the suspension of wires. The loads on the conductor and tap depend on the climatic regime and take into account wind and icy conditions, as well as temperature changes. The transition to another climatic regime is performed by solving the equation of state, taking into account the coefficients of the horizontal and vertical load of the given and initial regimes. Formulas are given for calculating load factors that take into account weight, wind and ice cover loads on wires and insulator strings, as well as the slope of the span. They are calculated for each climatic mode based on the actual location of the tap to the electrical apparatus and the forces from it to the busbar. It is shown that the calculation results are in good agreement with the proposed method and the computer program. Formulas are given for calculating the sag and horizontal deviations of the wires when the tap is located in the middle of the span. A method is proposed for calculating the components of the forces on the busbar from the tap, taking into account its real location in substation. Formulas for calculating these components are given for different variants of the tap orientation. Knowledge of the values of the components of concentrated forces from the tap allows to increase the accuracy of calculating the sag and tension of the substation wires. Formulas are given for calculating the coefficients of increasing the sag, taking into account the components of the forces from the tap.

Wheelchair Size and Material Application in Human-machine System Model

Based on investigation of existing folding wheelchairs’ usage, this paper analyzed wheelchair size and material in human-machine system model. The importance of new environmentally friendly materials’ application on wheelchair component producing in recent years was also explained. On the basis of strength and stiffness theory and calculation, applied materials were determined and rod mechanical calculation were carried out. The calculated results will have certain theoretical significance for wheelchair research and design.

First Fruits

Anderson thrives in graduate school where he begins a career-long friendly rivalry with Walter Kohn. He consciously chooses not to work with superstar theorist Julian Schwinger and pursues a PhD supervised by John Van Vleck. His thesis problem is a quantum mechanical calculation of the microwave absorption spectrum of small molecules. His social time is spent almost exclusively with non-physics graduate students, including the mathematician-comedic songwriter Tom Lehrer. He meets Joyce Gothwaite during a vacation trip home and only a short time passes before they marry in Boston and she becomes pregnant. Daughter Susan is born and Anderson completes his thesis work quickly. Money is tight.

Can Local Electric Field be a Descriptor of Catalytic Activity? A Case Study on Chorismate Mutase

The current theoretical perception of enzymatic activity is highly reliant on the determination of activation energy of the reactions which is often calculated using a computational demanding quantum mechanical calculation....

Failure Analysis of the Guyed-V Tower Link Plate Deformation of a 500 kV Transmission Line

Component analysis, mechanical property test, field survey and finite element mechanical calculation were used to analyse and evaluate the deformation failure of the Guyed-V Tower link plate of a 500 kV transmission line. The results show that the main cause of the failure is the relaxation of the guy after right front guy or wire is subjected to a large impact towards the large side. The weak design of the link plate structure and the misfitting of angle steel are the indirect causes of the failure. The construction angle of anchor cable is larger than the design value, and the tension of anchor cable is low, which has a certain impact.

Mechanical Calculation of Flexible Wires in the Presence of Horizontal Concentrated Loads

The linear wind load on the wires and cables acting perpendicular to the wire depends on the angle between the direction of the wind and the axis of the overhead line. In the methodology of mechanical calculation of wires and cables, it is recommended to take the wind directed at an angle of 90° to the axis of span and it is not specified which side the wind blows from. For spans of air, this is not so much significant as for switchgear spans, where the deviations of the wires depend on the direction of action of the taps to the electrical apparatus. The article discusses various options for the location of taps and their effect on the wire, as well as changing the direction of the wind. An algorithm for calculating the horizontal deviation of a flexible wire and its increase coefficients in the presence of horizontal concentrated loads due to the action of windon spacers, barriers, taps to electrical apparatuses and other structural elements of substations and overhead lines is given. In the absence of wind, horizontal concentrated loads and deviations occur when an arrangement of the taps is non-keel. The formulas for calculating the horizontal component of the load coefficient to solve the equation of state in the presence of horizontal concentrated forces acting in any direction have been derived. The results of the mechanical calculation are obtained for the cases of one and two horizontal concentrated forces, differently oriented with respect to the distributed wind load. In design practice it is recommended to take the wind flow in the direction of the action of horizontal concentrated forces, since in this case the greatest horizontal deviations and load factors are obtained. The reduction in the coefficients of the horizontal load occurs when the current lead is unloaded because of the opposite directions of the wind and horizontal concentrated forces. In the absence of wind, it is proposed to use the formulas for calculating horizontal deviations and load after finding the product of the coefficient of increase in horizontal deviations and the horizontal component of the coefficient of load per linear load.