Temperature-Dependent Paracrystalline Nucleation in Atomically Disordered Diamonds.

Atomically disordered diamonds with medium-range order realized in recent experiments extend our knowledge of atomic disorder in materials. However, the current understanding of amorphous carbons cannot answer why paracrystalline diamond (p-D) can be formed inherently different from other tetrahedral amorphous carbons (ta-Cs), and the emergence of p-D seems to be easily hindered by inappropriate temperatures. Herein, we performed atomistic-based simulations to shed light on temperature-dependent paracrystalline nucleation in atomically disordered diamonds. Using metadynamics and two carefully designed collective variables, reversible phase transitions among different ta-Cs can be presented under different temperatures, evidenced by corresponding local minima on the free energy surface and reaction path along the free energy gradient. We found that p-D is preferred in a narrow range of temperatures, which is comparable to real experimental temperatures under the Arrhenius framework. The insights and related methods should open up a perspective for investigating other amorphous carbons.

Correlation Between TRAb and Early Onset Hypothyroidism After 131I Treatment for Graves' Disease.

The aim of the study was to explore the clinical features related to early hypothyroidism and the relationship between the changes of thyrotropin receptor antibodies (TRAb) and early hypothyroidism in the course of 131I treatment for Graves' disease. This study was a retrospective observation, including 226 patients who received the first 131I treatment. The general information and laboratory tests were collected before and after 131I treatment, and the laboratory data affecting the difference in disease outcome were analyzed. According to the changes of antibodies in the third month, whether the changes of antibodies were involved in the occurrence of early-onset hypothyroidism was analyzed. Early onset hypothyroidism occurred in 165 of 226 patients, and the results showed that the incidence of early hypothyroidism was higher in patients with low baseline TRAb level (p=0.03) and increased TRAb after treatment (p=0.007). Both baseline TRAb levels (p<0.001) and the 24-hour iodine uptake rate (p=0.004) are significant factors influencing the changes in TRAb. The likelihood of a rise in TRAb was higher when the baseline TRAb was less than 18.55 U/l and the 24-hour iodine uptake level exceeded 63.61%. Low baseline and elevated post-treatment levels of TRAb were significantly associated with early-onset hypothyroidism after 131I treatment. Monitoring this index during RAI treatment is helpful in identifying early-onset hypothyroidism and mastering the clinical outcome and prognosis of Graves' disease.

Discontinuous phase diagram of amorphous carbons.

The short-range order and medium-range order of amorphous carbons demonstrated in experiments allow us to rethink whether there exist intrinsic properties hidden by atomic disordering. Here we presented six representative phases of amorphous carbons (0.1-3.4 g/cm3), namely, disordered graphene network (DGN), high-density amorphous carbon (HDAC), amorphous diaphite (a-DG), amorphous diamond (a-D), paracrystalline diamond (p-D), and nano-polycrystalline diamond (NPD), respectively, classified by their topological features and microstructural characterizations that are comparable with experiments. To achieve a comprehensive physical landscape for amorphous carbons, a phase diagram was plotted in the sp3/sp2 versus density plane, in which the counterintuitive discontinuity originates from the inherent difference in topological microstructures, further guiding us to discover a variety of phase transitions among different amorphous carbons. Intriguingly, the power law, log(sp3/sp2) ∝ ρn, hints at intrinsic topology and hidden order in amorphous carbons, providing an insightful perspective to reacquaint atomic disorder in non-crystalline carbons.