Minimum Level of Unemployment and Public Policy

Examines the government\u27s efforts to cope with permanent unemployment resulting from structural changes to the economy.https://research.upjohn.org/up_press/1156/thumbnail.jp

Dimensions of the Problem

Examines the government\u27s efforts to cope with permanent unemployment resulting from structural changes to the economy.https://research.upjohn.org/up_press/1156/thumbnail.jp

Surface modification of copper-based alloys in antimicrobial application

Copper and its alloys have exhibited very beneficial properties as regard to the contact killing of bacteria [1],[2]. In course of this research, surfaces of various copper-based alloys will be modified with ultrashort pulsed (USP) laser systems to understand its influence on the antimicrobial properties. Direct laser interference patterning (DLIP) is the method used in this study to produce periodic line structures on the sample surface. The periodicity chosen here is according to the dimension of the bacteria, that will be tested later (see Fig.1). The influence of alloying on topography of the sample will be investigated and analyzed. The effect of surface modification on the antibacterial and wetting properties of the samples will be tested. A series of wettability and contact killing tests is performed to determine the correlation between the structures produced via USP-DLIP and the antibacterial as well as the wetting properties. The obtained results will also be beneficial for understanding the effect of alloying on the antibacterial efficiency

Tailor the antibacterial efficiency of copper alloys by oxidation: when to and when not to

Copper and its relevant species, such as oxides and many alloys, have been recognised as potential antibacterial surfaces. Despite the relatively low antibacterial efficacy of cuprous oxide (Cu2O) compared to pure copper, it is still worth consideration in some scenarios. Taking copper-nickel co-sputtered thin films with two copper contents (55 and 92 at.%) as examples, this work inves tigated the potential of oxidation in altering the antibacterial behaviour of copper alloy surfaces. By heat treatment at 200–250 C for 20–24 h, a layer mainly composed of Cu2O was successfully fabricated on the top of the Cu-Ni alloys. Antibacterial efficiency against Escherichia coli in 1 h was obtained by the droplet method and further compared. The coupons with 92 at.% copper became less effective after oxidation: the reduction rate declines from 97.0 to 74.3%; whereas the coupons with 55 at.% copper showed a large increase after oxidation, rising from 15.0 to 66.8%. The experiments described herein reveal a promising concept of oxidation in enhancing the less effective copper alloy surfaces for antibacterial applications

Optimization of the performances of textured segmented solar cells: achievements and challenges

International audienceTransparent electrodes transmit light and conduct electrical current simultaneously especially in the visible range [1]. They are used in many applications such as flat panel displays, light emitting diodes and solar cells which is the application of interest in this work. Textured or complex surfaces, in comparison to smooth surfaces, present better properties that once combined with the properties of transparent electrodes can amount to great results; for example, textured cells deliver more photocurrent than planar cells, even at oblique angles [2]. Zinc oxide (ZnO) and Al doped ZnO (AZO) are widely used as transparent electrodes due to the abundance and low cost of Zn and Al compared with Sn and In found in indium tin oxide (ITO) in addition to their high optical and electrical properties [1]. An important technique for depositing (AZO) films is the High Impulse Magnetron Sputtering (HiPIMS) method that allows us to deposit highly conductive and transparent films on large surfaces and at low temperature [3]. Another important technique is the Atomic Laser Deposition (ALD) wich is used for depositing high quality thin films due to the self-limiting growth mechanism wich enables an excellent surface coverage and conformal deposition on high aspect ratio structures; this method enables us to combine metallic Cu films with semiconductor oxides (ZnO, Cu2O, or both) leading to many applications in different fields related with optoelectronics, catalysis, gas sensing and photovoltaics [4]. Cuprous oxide (Cu2O) is a direct-gap semiconductor with a band gap energy of approximately 2.1 eV [5] also used as a transparent electrode. The fabrication of segmented p-Cu2O/n-ZnO nano-junctions desired in this work is facilitated by (ALD). In this presentation we report on the strategy we are developing to produce segmented textured solar cells based on Cu2O/ZnO junctions, the applications, achievements and challenges to overcome

Quantitation of Aortic Valvular Insufficiency Using Radioactive Tracers: An Experimental Study In Vitro

A method has been developed in vitro for quantitation of aortic valvular insufficiency (Al) based on the use of ladioactive traceis lo genei-ate graphic recordings of the movement of blood out of the ventricle and back again. The regurgitant fraction of stroke volume (peirent of Al) is read from this recording. The method was evaluated in a mechanical heart model by comparing Al values read from the istope recordings and Al values determined volumetrically. The recordings gave excellent agreement with the volumetric results (Corr. Coeff. .9). These in vitro results are of such quality that clinical trials seem justified