Tribological and corrosion performance of the plasma-sprayed conformal ceramic coating on selective laser melted CoCrMo alloy.

Ceramic implants have superior performance due to the excellent wear resistance and biocompatibility. However, the poor machinability limits their applications. Plasma sprayed ceramic coating on the additively manufactured metal substrate not only provides a 3-dimensional conformal implant coating and but also forms a highly wear-resistant surface layer. In this paper, three types of ceramic coatings of Al2O3, ZrO2, and Al2O3-ZrO2 composite have been fabricated by atmosphere plasma spray on the CoCrMo alloy substrate prepared by selective laser melting (SLM). It has been found that the Al2O3-ZrO2 composite coating has better corrosion and wear resistance compared with the ceramic coating (Al2O3, ZrO2) and the CoCrMo substrate. The adhesion strength between the Al2O3-ZrO2 composite coating and the substrate reaches 238 MPa. In addition, the wear and corrosion resistance increase with wear progression for all the fabricated ceramic coatings. The highly dense microstructure, fewer microcracks, and the amorphous phases are deterministic factors responsible for the superior tribological and corrosion performance of the Al2O3-ZrO2 composite coating. The fabrication route has been proved very promising to manufacture high-performance implants with ceramic coating.

Inverse Doppler Effects in Pipe Instruments.

Music is older than language, and for most of human history music holds our culture together. The pipe instrument is one of the most popular musical instruments of all time. Built on the foundation of previous flute and flute-like acoustic metamaterial models, we herein report the experimental results of the inverse Doppler effects discovered in two common pipe instruments - recorder and clarinet. Our study shows that the inverse Doppler effects can be detected at all seven pitches of an ascending musical scale when there is a relative motion between a microphone (observer) and abovementioned two pipe instruments (source). The calculated effective refractive indices of these two pipe instruments are negative and varying across a set of pitches, exhibiting a desired characteristic of broadband acoustic metamaterials. This study suggests that recorder and clarinet may be the earliest man-made acoustic metamaterials known so far, offering a new explanation why pipe instruments have enjoyed wide popularity in Europe and Asia over the past hundreds and thousands years. This newly discovered phenomenon would also offer a clue into designing next-generation smart broadband double-negative acoustic metamaterials with varying refractive index.

Inverse Doppler Effects in Broadband Acoustic Metamaterials.

The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with 'flute-like' acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe.

SLC2A2 mutations can cause neonatal diabetes, suggesting GLUT2 may have a role in human insulin secretion.

AIMS: The gene SLC2A2 encodes GLUT2, which is found predominantly in pancreas, liver, kidney and intestine. In mice, GLUT2 is the major glucose transporter into pancreatic beta cells, and biallelic Slc2a2 inactivation causes lethal neonatal diabetes. The role of GLUT2 in human beta cells is controversial, and biallelic SLC2A2 mutations cause Fanconi-Bickel syndrome (FBS), with diabetes rarely reported. We investigated the potential role of GLUT2 in the neonatal period by testing whether SLC2A2 mutations can present with neonatal diabetes before the clinical features of FBS appear. METHODS: We studied SLC2A2 in patients with transient neonatal diabetes mellitus (TNDM; n = 25) or permanent neonatal diabetes mellitus (PNDM; n = 79) in whom we had excluded the common genetic causes of neonatal diabetes, using a combined approach of sequencing and homozygosity mapping. RESULTS: Of 104 patients, five (5%) were found to have homozygous SLC2A2 mutations, including four novel mutations (S203R, M376R, c.963+1G>A, F114LfsX16). Four out of five patients with SLC2A2 mutations presented with isolated diabetes and later developed features of FBS. Four out of five patients had TNDM (16% of our TNDM cohort of unknown aetiology). One patient with PNDM remains on insulin at 28 months. CONCLUSIONS: SLC2A2 mutations are an autosomal recessive cause of neonatal diabetes that should be considered in consanguineous families or those with TNDM, after excluding common causes, even in the absence of features of FBS. The finding that patients with homozygous SLC2A2 mutations can have neonatal diabetes supports a role for GLUT2 in the human beta cell.

Protein crystal growth in microgravity.

Protein crystal growth is quite important for the determination of protein structures which are essential to the understanding of life at molecular level as well as to the development of molecular biotechnology. The microgravity environment of space is an ideal place to study the complicated protein crystallization and to grow good-quality protein crystals. A number of crystal-growth experiments of 10 different proteins were carried out in August, 1992 on the Chinese re-entry satellite FSW-2 in space using a tube crystallization equipment made in China. A total of 25 samples from 6 proteins produced crystals, and the effects of microgravity on protein crystal growth were observed, especially for an acidic phospholipase A2 and henegg-white lysozyme which gave better crystals in space than earth-grown crystals in ground control experiments. The results have shown that the microgravity in space favors the improvement of the size, perfection, morphology and internal order of the grown protein crystals.

Protein crystallization in space.

The microgravity environment of space is an ideal place to study the complicated protein crystallization process and to grow good-quality protein crystals. A series of crystal growth experiments of 10 different proteins was carried out in space on a Chinese re-entry satellite FSW-2 in August, 1992. The experiments were performed for about two weeks at a temperature of 18.5 +/- 0.5 degrees C using a tube-like crystallization apparatus made in the Shanghai Institute of Technical Physics, Academia Sinica. More than half of 48 samples from 6 proteins produced crystals, and the effects of microgravity on protein crystal growth were observed, especially for hen-egg white lysozyme and an acidic phospholipase A2 from the venom of Agkistrodon halys Pallas. Analyses of the crystallization of these two enzymes in this mission showed that the microgravity environment in space may be beneficial to improve size, external perfection, morphology, internal order, and nucleation of protein crystals. Some of these positive microgravity effects were also demonstrated by the growth of protein crystals in gelled solution with the above two enzymes. A structural analysis of the tetragonal lysozyme crystal grown in space is in progress.

Computer model of an inhomogeneous human torso.

Based on the atlas of sectional human anatomy, a three dimensional computer model of a human torso, including four cavities of the heart (LV, RV, LA, RA), two lobes of the lung and the body surface, and a three dimensional model of the myocardium is introduced. The torso model, with more than 10,000 surface triangles, depicts the structures and appropriate proportions of the internal organs, especially of the heart. Algorithms for the model construction are given in detail and the validity of the models for the purpose of simulation research into the electrocardiogram is discussed.