Episodic crustal growth in the Tanzania Craton:evidence from Nd isotope compositions

The analysis of available Nd isotope data from the Tanzania Craton places important constraints on the crest-mantle separation ages,and events marking juvenile crustal addition and crustal recycling.Nd model ages date the oldest crust extraction to 3.16 Ga in the Tanzania Craton,although a rock record of such antiquity is yet to be found there.The most significant period of juvenile crustal addition as well as crustal recycling is 2.7-2.6 Ga.The Nd isotopes of marie samples show that chemical heterogeneity existed in the mantle beneath the Tanzania Craton,with some samples originating from significantly depleted mantle, and most samples originating from the mixture of primitive mantle and depleted mantle.The Nd isotope section reveals significant differences in Nd isotopes between the north eraton and central craton;compared to the north craton,the central craton yields a Nd model age that is approximately 100 Ma older, and its εNd(t)values are more negative,indicating that the two parts of the craton have different mantle source regions.Different types of granitoids are distributed in the Tanzania Craton,such as high-K and low-Al granite,ealc-alkaline granite,peraluminous granite and transitional types of tonalite-trondhjemite- granodiorites (TTGs).Most of the granitoids formed later than the marie rocks in syn-collision and postcollision events.

Numerical study on magneto-Rayleigh–Taylor instabilities for thin liner implosions on the primary test stand facility

The thin aluminum liners with an aspect ratio R/?r 1 have been imploded on the primary test stand(PTS) facility,where R is the outer radius of the liner and ?r is the thickness. The x-ray self-emission images present azimuthally correlated perturbations in the liner implosions. The experiments show that at-10 ns before the stagnation, the wavelengths of perturbation are about 0.93 mm and 1.67 mm for the small-radius and large-radius liners, respectively. We have utilized the resistive magnetohydrodynamic code PLUTO to study the development of magneto-Rayleigh–Taylor(MRT) instabilities under experimental conditions. The calculated perturbation amplitudes are consistent with the experimental observations very well. We have found that both mode coupling and long implosion distance are responsible for the more developed instabilities in the large-radius liner implosions.

Discussion on the dextral movement and its effect in continental China and adjacent areas since Cenozoic

Continental China has moved dextral Eastward since Cenozoic time,driven by the collision of the Indian with the Eurasian plate.Evidence for this comes from landscape evolution,the distribution of earthquake epicenters,Cenozoic sedimentary and volcanic rocks,and the measurement of GPS velocity vectors,the distribntion of crustal stress,paleomagnetic data,and deep mantle structure,among others.This movement commenced around 40 Ma,coupled with thickened lithosphere and widespread stress release along strikeslip faults that bound the continental Chinese block.Because of continued Northward subduction of the Indian plate,manifestation of the dextral movement has intensified since 25 Ma.Far-reaching effects include extensive strike-slip movement on the Tan-Lu fault in Eastern China,formation of the Dabie ultrahigh pressure metamorphic terrane,extensive thrust faults in East China,delamination and thickening of the lithosphere of South China,a possible tectonic doubling of the Middle-Lower Yangtze Valley metallogenic belt,and the formation of the Japan,Huanghai (East China),and South China Sea.

Strategies and challenges in the treatment of chronic venous leg ulcers

Evaluating patients with chronic venous leg ulcers(CVLUs)is essential to find the underlying etiology.The basic tenets in managing CVLUs are to remove the etiological causes,to address systemic and metabolic conditions,to examine the ulcers and artery pulses,and to control wound infection with debridement and eliminating excessive pressure on the wound.The first-line treatments of CVLUs remain wound care,debridement,bed rest with leg elevation,and compression.Evidence to support the efficacy of silver-based dressings in healing CVLUs is unavailable.Hydrogen peroxide is harmful to the growth of granulation tissue in the wound.Surgery options include a high ligation with or without stripping or ablation of the GSVs depending on venous reflux or insufficiency.Yet,not all CVLUs are candidates for surgical treatment because of comorbidities.When standard care of wound for 4 wk failed to heal CVLUs effectively,use of advanced wound care should be considered based on the available evidence.Negative pressure wound therapy facilitates granulation tissue development,thereby helping closure of CVLUs.Autologous split-thickness skin grafting is still the gold standard approach to close huge CVLUs.Hair punch graft appears to have a better result than traditional hairless punch graft for CVLUs.Application of adipose tissue or placenta-derived mesenchymal stem cells is a promising therapy for wound healing.Autologous platelet-rich plasma provides an alternative strategy for surgery for safe and natural healing of the ulcer.The confirmative efficacy of current advanced ulcer therapies needs more robust evidence.

A new pattern of the tectonic units and metallogenic belts in Africa continent in terms of lithosphere

Based on the comprehensive study of geology and geophysics in African continent,three types of lithosphere(craton-type,orogenic-type and rift-type)can be identified.Considering lithosphere discontinuities as the boundary,two first-order tectonic units(mainly cratonic-type in the west and rift-type in the east)are proposed.Different types of lithosphere can be divided into secondary-order and third-order structural units,and the blocks within lithosphere can be further divided into fourth-order structural units.The geological history,the formation process and significance of different types of lithosphere in African continent are briefly discussed.