Progress in the experimental and computational methods of work function evaluation of materials: A review.

The work function, which determines the behaviour of electrons in a material, remains a crucial factor in surface science to understand the corrosion rates and interfacial engineering in making photosensitive and electron-emitting devices. The present article reviews the various experimental methods and theoretical models employed for work function measurement along with their merits and demerits are discussed. Reports from the existing methods of work function measurements that Kelvin probe force microscopy (KPFM) is the most suitable measurement technique over other experimental methods. It has been observed from the literature that the computational methods that are capable of predicting the work functions of different metals have a higher computational cost. However, the stabilized Jellium model (SJM) has the potential to predict the work function of transition metals, simple metals, rare-earth metals and inner transition metals. The metallic plasma model (MPM) can predict polycrystalline metals, while the density functional theory (DFT) is a versatile tool for predicting the lowest and highest work function of the material with higher computational cost. The high-throughput density functional theory and machine learning (HTDFTML) tools are suitable for predicting the lowest and highest work functions of extreme material surfaces with cheaper computational cost. The combined Bayesian machine learning and first principle (CBMLFP) is suitable for predicting the lowest and highest work functions of the materials with a very low computational cost. Conclusively, HTDFTML and CBMLFP should be used to explore the work functions and surface energy in complex materials.

Orthopaedic applications of bone graft & graft substitutes: a review.

Treatment of delayed union, malunion, and nonunion is a challenge to the orthopaedic surgeons in veterinary and human fields. Apart from restoration of alignment and stable fixation, in many cases adjunctive measures such as bone-grafting or use of bone-graft substitutes are of paramount importance. Bone-graft materials usually have one or more components: an osteoconductive matrix, which acts as scaffold to new bone growth; osteoinductive proteins, which support mitogenesis of undifferentiated cells; and osteogenic cells, which are capable of forming bone in the appropriate environment. Autologous bone remains the "gold standard" for stimulating bone repair and regeneration, but its availability may be limited and the procedure to harvest the material is associated with complications. Bone-graft substitutes can either substitute autologous bone graft or expand an existing amount of autologous bone graft. We review the currently available bone graft and graft substitutes for the novel therapeutic approaches in clinical setting of orthopaedic surgery.

Theoretical investigation of estimation of steady and pulsatile blood flow and blood vessel cross section by CW NMR excitation.

In this paper we show theoretically that when a magnetised blood bolus enters a CW NMR excitor coil of length Le at resonance and the signal from the T2-decaying, processing transverse magnetisation of the flowing blood spins is subsequently detected by a detector coil of length L separated from the excitor coil by a distance delta l, then by recording CW NMR signals at three positions such as delta l = 0, 0.5 and 1.0 cm one can eliminate the static tissue signal and measure non-invasively the steady component V0 as well as the total vessel cross section, beta accurately. The time dependent part of the CW NMR signal which depends on Vpulse(t), is also dependent on V0 non-linearly unless both L and Le are greater than 50 cm and delta l is zero. Finally, methods of obtaining true Vpulse(t) from the CW NMR signal after applying proper correction due to the steady flow are discussed.