The Fate of Chromium in Weathered Ultramafic Rocks and Their Derivitative Soils in Cuba: Clues from Spectroscopic Studies

In its cationic,trivalent form,Chromium(Cr)it is a micronutrient,and exhibits low environmental mobility.In hexavalent form,however,it is a human carcinogen and also highly mobile.Climate is a key environmental factor controlling weathering rates and stability of primary and secondary Cr-bearing minerals.Knowledge of Cr oxidation state and mineral residence is therefore essential to estimating the risk posed by Cr in serpentinites,chromite mine wastes,and soils developed on these parent materials.X-ray absorption spectroscopy(XAS)is currently the best available technique for determination of the relative abundance of Cr(III)and Cr(VI)in situ(that is,without digestion of solid phases).A brief review of relevant XAS studies of is presented below,focusing on studies in tropical climates1,as they will be most relevant to eastern Cuba’s extensively serpentinized ophiolite belt.Cr(III)-bearing spinels are usually the dominant and most refractory Cr host in ultramafic rocks.Previous XAS studies2 indicate that in tropical climates,Cr-spinels weather rapidly to form Cr(III)-bearing secondary Fe(III)(hydr)oxides(goethite,hematite).Manganese(Mn)is also enriched in ultramafic rocks2;as Mn(IV),it can also co-precipitate with Fe(III)(hydr)oxides,or form its own secondary(hydr)oxides.A previous study found up to 20%Cr(VI)in in a tropical,serpentine soil that contained substantial Mn,and a strong correlation between the*amounts of Cr(VI)and Mn(IV)in the soil profile2.Theresults of several XAS studies suggest that a close association of Mn(IV)and Cr(III)in secondary Fe(hydr)oxides is necessary for oxidation of Cr(III)to Cr(VI)via electron transfer reactions with Mn(IV);however,additional XAS studies have shown that organic matter3and Cr-bearing aluminosilicates4 may also be important sources of Cr(III)to the environment under specific conditions.The stability and fate of Cr has not been studied in detail for these two host phase types,to the best of our knowledge.Access to XAS facilities to perform Cr geochemical experiments is limited and will only become more so in the future.We are working to develop and apply(micro)Raman spectroscopy to evaluate Cr oxidation state and mineral residence(in crystalline and amorphous materials).In addition to standard Raman scattering,we are employing resonance Raman(785 nm laser)to enhance signal from Cr(VI)-bearing phases and laser-stimulated photoluminescence to identify Cr(III)associated with Al-rich alteration products

Hsp83 regulates the fate of germline stem cells in Drosophila ovary

In adult tissues,stem cells are defined by their unique capacity to self-renew and produce differentiated cells to maintain tissue homeostasis.Drosophila ovarian germline stem cells（GSCs）provide a powerful model for investigating the regulatory mechanisms underlying stem cell fate determination in vivo（Chen and Mckearin.

CRISPR-based riboswitches for redirecting the fate of cancer cells

With the support by the National Natural Science Foundation of China,the research team led by Dr.Liu Yuchen(刘宇辰)at the State Engineering Laboratory of Medical Key Technologies Application of Synthetic Biology,Shenzhen Second People’s Hospital,the First Affiliated Hospital of Shenzhen University,developed a type of CRISPR-based riboswitch,which was published in Nature Methods(2016,doi:10.

Should a Click of the Mouse Decide the Fate Of a Criminal Suspect?

Computers have been programmed to do just about anything today and very little they do still raises eyebrows. Well, that was until a software program was developed to decide the fate of suspects on trial in a court of law within minutes. Zichuan People's Court, Zibo City,

Analysis of Dynamical Behavior of One-Dimensional Real Maps: An Executable Dynamical Programming Software Approach

The dynamical behavior of real-world phenomena is implausible graphically due to the complexity of mathematical coding. The present article has mainly focused on some one-dimensional real maps’ dynamical behavior irrespective of using coding. In continuation, linear, quadratic, cubic, higher-order, exponential, logarithmic, and absolute value maps have been used to scrutinize their dynamical behavior, including the characteristics of the orbit of points. Dynamical programming software (DPS.exe) will be proposed as a new technique to ascertain the dynamical behavior of said maps. Thus, a mathematician can automatically determine one-dimensional real maps’ dynamical behavior apart from complicated programming code and analytical solutions.