RESUMO
Two-dimensional heterostructures formed by stacking layered materials play a significant role in condensed matter physics and materials science due to their potential applications in high-efficiency nanoelectronic and optoelectronic devices. In this paper, the structural, electronic, and optical properties of SiC/CrS2van der Waals heterostructure (vdWHs) have been investigated by means of density functional theory calculations. It is confirmed that the SiC/CrS2vdWHs is energetically and thermodynamically stable indicating its great promise for experimental realization. We find that the SiC/CrS2vdWHs has a direct-band gap and type-II (staggered) band alignment, which can effectively separate the photo-induced electrons and holes pairs and extend their life time. The carrier mobilities of electrons and holes along the armchair and zigzag directions are as high as 6.621 × 103and 6.182 × 104 cm2 V-1 s-1, respectively. Besides, the charge difference and potential drop across the interface can induce a large built-in electric field across the heterojunction, which will further hinder the electron and hole recombination. The SiC/CrS2vdWHs has enhanced optical absorption capability compared to individual monolayers. This study demonstrates that the SiC/CrS2vdWHs is a good candidate for application in the nanoelectronic and optoelectronic devices.
RESUMO
In order to investigate the effect of autologous dendritic cells (DCs) activating bone marrow cells and purging bone marrow from chronic myelogenous leukemia (CML) patients, DCs were separated by negative selection system of human cells from bone marrow mononuclear cells (BMMNCs) of 2 CML patients in hematological remission and harvested after 3 days of culture in IMDM containing autologous plasma, rhGM-CSF and rhTNFalpha at 37 degrees C, 5% CO(2) humidified atmosphere. BMMNCs from the patients were also used to set up long-term culture (LTC) system in T-25 plastic flasks. The LTCs included three groups, i.e., control, addition of rhIL-2, and co-culture with autologous DCs. Half of non-adherent cells were collected, counted and assayed for CFU-GM weekly. Then, equivalent volume of fresh medium was replaced to maintain the culture. The culture was discontinued if the non-adherent cells count was less than 2 x 10(5). Adherent cells were collected for CFU-GM assay and flow cytometry for CD34 and P210. The colonies originating from the adherent cells were picked up under the inverted microscope. RNA was extracted, and BCR/ABL measured by nested reverse transcription polymerase chain reaction (RT-PCR). The results showed that the CFU-GM yields of non-adherent cells declined after 1 to 2 weeks co-cultured with autologous DCs, and it paralleled with group with rhIL-2. P210(+) cell percentage was also decreased. From the third week on, however, the decrease of CFU-GM yields slowed down, while CFU-GM in the system with rhIL-2 continued to fall. In system co-cultured with autologous DCs, the adherent cells contained the least percentagcs of CD34(+) cells and P210(+) cells percentage. However, the expression of BCR/ABL in CFU-GM colonies derieved from the adherent cells of DCs co-cultured had no significant difference with those from the culture without DCs. Our results suggest that co-culture of marrow cells with autologous DCs could significantly diminish the leukemic progenitors cells including both mature and primitive progenitor cells. Autologous dendritic cells might be used for ex vivo purging of CML marrow.
