STM and RHEED study of the Si(001)-c(8x8) surface

The Si(001) surface deoxidized by short annealing at T~925C in the ultrahigh vacuum molecular beam epitaxy chamber has been in situ investigated by high resolution scanning tunnelling microscopy (STM) and reflected high energy electron diffraction (RHEED). RHEED patterns corresponding to (2x1) and (4x4) structures were observed during sample treatment. The (4x4) reconstruction arose at T<600C after annealing. The reconstruction was observed to be reversible: the (4x4) structure turned into the (2x1) one at T>600C, the (4x4) structure appeared again at recurring cooling. The c(8x8) reconstruction was revealed by STM at room temperature on the same samples. A fraction of the surface area covered by the c(8x8) structure decreased as the sample cooling rate was reduced. The (2x1) structure was observed on the surface free of the c(8x8) one. The c(8x8) structure has been evidenced to manifest itself as the (4x4) one in the RHEED patterns. A model of the c(8x8) structure formation has been built on the basis of the STM data. Origin of the high-order structure on the Si(001) surface and its connection with the epinucleation phenomenon are discussed.Comment: 26 pages, 12 figure

Chronic Myeloid Leukemia Patient Registry in the Russian Federation: From Observational Studies to the Efficacy Evaluation in Clinical Practice

Background. Due to the significant increase in life expectancy and the quality of life in patients with chronic myeloid leukemia (CML) as well as the growing need for expensive tyrosine kinase inhibitors (TKI), the analysis of cost-effectiveness and lifelong monitoring of patients is especially important. Aim. We present the results of a multicenter observational study “The Russian Registry of Chronic Myeloid Leukemia in routine clinical practice (2011–2016)”. Materials & Methods. The study included Russian patients with CML, confirmed by the detection of a Ph-chromosome or a BCR-ABL transcript. The statistical analysis (July 1, 2016) included 7609 patients from 80 regions of the Russian Federation (covering 95 % of the population). The annual increase in the number of patients with newly diagnosed CML was 600–650 patients. At the time of the statistical analysis, 6995 (92 %) patients remained under observation, 473 (6 %) died and 141 (2 %) were withdrawn. The registry included 44 % of men and 56 % of women, the median age was 49 years (range 2–94 years). The peak incidence (46.3 %) occurred at the age of 40–60 years. The median disease duration by the time of the analysis was 6 years (range 0.1–30 years). Results. The disease was diagnosed in the chronic phase (CP), acceleration phase, and blast crisis in 6560 (93.8 %), 380 (5.5 %) and 47 (0.7 %) patients, respectively. The proportion of risk groups according to Sokal for low, intermediate and high risk in CP was 49 %, 30 %, and 21 %, respectively. TKI were administered to 6473 (92.5 %) patients. Imatinib and the second generation TKI (TKI2) were administered to 5570 (86 %) and 903 (14 %) patients, respectively. The total of 30.4 % of patients received the increased imatinib dose of 600–800 mg. In the TKI2 group, 558 (61.7 %) patients received nilotinib and 345 (38.2 %) patients received dasatinib. The proportion of patients with completed molecular genetic studies (MGS) in 2014, 2015 and the first 6 months of 2016 amounted to 61 %, 58 % and 23 %, respectively. The proportion of patients with cytogenetic studies (CS) for the same period was 28 %, 26 % and 7 %, respectively. No CS or MGS data were presented for 34 %, 35 % and 63 % of patients during this period. Optimal molecular response and major molecular response (MMR) for TKI therapy were observed in 23 % and 58 % of patients treated 12 months, respectively. When nilotinib was used in the second line, MMR was obtained in 42 % of patients, and a deep molecular response was obtained in 25 % of patients (BCR-ABL < 0.01 %). Conclusion. The high efficacy of TKI therapy was observed in the majority of patients with the possibility of achieving a minimal residual disease. The problems concerning untimely monitoring and suboptimal administration of second line treatment were identified. In general, the CML patient registry allowed the data integration of data and information management of population with CML in Russia

Thermally activated delayed fluorescence emitters in light-emitting electrochemical cells

Thermally activated delayed fluorescence (TADF) represents a very promising singlet harvesting mechanism that permits harvesting of both singlet and triplet excitons in electroluminescent devices. In this chapter, the operating principle of TADF mechanism is introduced. Two major classes of TADF emitters employed in light-emitting electrochemical cell (LEC) devices, small molecule organic compounds, and copper(I) complexes, are discussed in the context of their optoelectronic properties and LEC device performance metrics. A critical outlook for each class of emitters is also provided.</p