Reducing contact resistance of MoS2-based field effect transistors through uniform interlayer insertion via atomic layer deposition.

Molybdenum disulfide (MoS2), a semiconducting two-dimensional layered transition metal dichalcogenide (2D TMDC), with attractive properties enables the opening of a new electronics era beyond Si. However, the notoriously high contact resistance (RC) regardless of the electrode metal has been a major challenge in the practical applications of MoS2-based electronics. Moreover, it is difficult to lower RC because the conventional doping technique is unsuitable for MoS2 due to its ultrathin nature. Therefore, the metal-insulator-semiconductor (MIS) architecture has been proposed as a method to fabricate a reliable and stable contact with low RC. Herein, we introduce a strategy to fabricate MIS contact based on atomic layer deposition (ALD) to dramatically reduce the RC of single-layer MoS2 field effect transistors (FETs). We utilize ALD Al2O3 as an interlayer for the MIS contact of bottom-gated MoS2 FETs. Based on the Langmuir isotherm, the uniformity of ALD Al2O3 films on MoS2 can be increased by modulating the precursor injection pressures even at low temperatures of 150 °C. We discovered, for the first time, that film uniformity critically affects RC without altering the film thickness. Additionally, we can add functionality to the uniform interlayer by adopting isopropyl alcohol (IPA) as an oxidant. Tunneling resistance across the MIS contact is lowered by n-type doping of MoS2 induced by IPA as the oxidant in the ALD process. Through a highly uniform interlayer combined with strong doping, the contact resistance is improved by more than two orders of magnitude compared to that of other MoS2 FETs fabricated in this study.

Investigation on Contact Properties of 2D van der Waals Semimetallic 1T-TiS2/MoS2 Heterojunctions.

Two-dimensional transition metal dichalcogenides (2D TMDCs) are considered promising alternatives to Si as channel materials because of the possibility of retaining their superior electronic transport properties even at atomic body thicknesses. However, the realization of high-performance 2D TMDC field-effect transistors remains a challenge owing to Fermi-level pinning (FLP) caused by gap states and the inherent high Schottky barrier height (SBH) within the metal contact and channel layer. This study demonstrates that high-quality van der Waals (vdW) heterojunction-based contacts can be formed by depositing semimetallic TiS2 onto monolayer (ML) MoS2. After confirming the successful formation of a TiS2/ML MoS2 heterojunction, the contact properties of vdW semimetal TiS2 were thoroughly investigated. With clean interfaces of the TiS2/ML MoS2 heterojunctions, atomic-layer-deposited TiS2 can induce gap-state saturation and suppress FLP. Consequently, compared with conventional evaporated metal electrodes, the TiS2/ML MoS2 heterojunctions exhibit a lower SBH of 8.54 meV and better contact properties. This, in turn, substantially improves the overall performance of the device, including its on-current, subthreshold swing, and threshold voltage. Furthermore, we believe that our proposed strategy for vdW-based contact formation will contribute to the development of 2D materials used in next-generation electronics.

Role of a cyclopentadienyl ligand in a heteroleptic alkoxide precursor in atomic layer deposition.

Alkoxide precursors have been highlighted for depositing carbon-free films, but their use in Atomic Layer Deposition (ALD) often exhibits a non-saturated growth. This indicates no self-limiting growth due to the chain reaction of hydrolysis or ligand decomposition caused by ß-hydride elimination. In the previous study, we demonstrated that self-limiting growth of ALD can be achieved using our newly developed precursor, hafnium cyclopentadienyl tris(N-ethoxy-2,2-dimethyl propanamido) [HfCp(edpa)3]. To elucidate the growth mechanism and the role of cyclopentadienyl (Cp) ligand in a heteroleptic alkoxide precursor, herein, we compare homoleptic and heteroleptic Hf precursors consisting of N-ethoxy-2,2-dimethyl propanamido (edpa) ligands with and without cyclopentadienyl ligand-hafnium tetrakis(N-ethoxy-2,2-dimethyl propanamido) [Hf(edpa)4] and HfCp(edpa)3. We also investigate the role of a Cp ligand in growth characteristics. By substituting an alkoxide ligand with a Cp ligand, we could modify the surface reaction during ALD, preventing undesired reactions. The last remaining edpa after Hf(edpa)4 adsorption can undergo a hydride elimination reaction, resulting in surface O-H generation. In contrast, Cp remains after the HfCp(edpa)3 adsorption. Accordingly, we observe proper ALD growth with self-limiting properties. Thus, a comparative study of different ligands of the precursors can provide critical clues to the design of alkoxide precursors for obtaining typical ALD growth with a saturation behavior.

Long-term follow-up results of cytarabine-containing chemotherapy for acute promyelocytic leukemia.

BACKGROUND/AIMS: We evaluated the feasibility and long-term efficacy of the combination of cytarabine, idarubicin, and all-trans retinoic acid (ATRA) for treating patients with newly diagnosed acute promyelocytic leukemia (APL). METHODS: We included 87 patients with newly diagnosed acute myeloid leukemia and a t(15;17) or promyelocytic leukemia/retinoic acid receptor alpha (PML-RARα) mutation. Patients received 12 mg/m2/day idarubicin intravenously for 3 days and 100 mg/m2/day cytarabine for 7 days, plus 45 mg/m2/day ATRA. Clinical outcomes included complete remission (CR), relapse-free survival (RFS), overall survival (OS), and the secondary malignancy incidence during a 20-year follow-up. RESULTS: The CR, 10-year RFS, and 10-year OS rates were 89.7%, 94.1%, and 73.8%, respectively, for all patients. The 10-year OS rate was 100% for patients that achieved CR. Subjects were classified according to the white blood cell (WBC) count in peripheral blood at diagnosis (low-risk, WBC < 10,000/mm3; high-risk, WBC ≥ 10,000/mm3). The low-risk group had significantly higher RFS and OS rates than the high-risk group, but the outcomes were not superior to the current standard treatment (arsenic trioxide plus ATRA). Toxicities were similar to those observed with anthracycline plus ATRA, and higher than those observed with arsenic trioxide plus ATRA. The secondary malignancy incidence after APL treatment was 2.7%, among the 75 patients that achieved CR, and 5.0% among the 40 patients that survived more than 5 years after the APL diagnosis. CONCLUSION: Adding cytarabine to anthracycline plus ATRA was not inferior to anthracycline plus ATRA alone, but it was not comparable to arsenic trioxide plus ATRA. The probability of secondary malignancy was low.

Hydrogen Barriers Based on Chemical Trapping Using Chemically Modulated Al2O3 Grown by Atomic Layer Deposition for InGaZnO Thin-Film Transistors.

In this study, the excellent hydrogen barrier properties of the atomic-layer-deposition-grown Al2O3 (ALD Al2O3) are first reported for improving the stability of amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs). Chemical species in Al2O3 were artificially modulated during the ALD process using different oxidants, such as H2O and O3 (H2O-Al2O3 and O3-Al2O3, respectively). When hydrogen was incorporated into the H2O-Al2O3-passivated TFT, a large negative shift in Vth (ca. -12 V) was observed. In contrast, when hydrogen was incorporated into the O3-Al2O3-passivated TFT, there was a negligible shift in Vth (ca. -0.66 V), which indicates that the O3-Al2O3 has a remarkable hydrogen barrier property. We presented a mechanism for trapping hydrogen in a O3-Al2O3 via various chemical and electrical analyses and revealed that hydrogen molecules were trapped by C-O bonds in the O3-Al2O3, preventing the inflow of hydrogen to the a-IGZO. Additionally, to minimize the deterioration of the pristine device that occurs after a barrier deposition, a bi-layered hydrogen barrier by stacking H2O- and O3-Al2O3 is adopted. Such a barrier can provide ultrastable performance without degradation. Therefore, we envisioned that the excellent hydrogen barrier suggested in this paper can provide the possibility of improving the stability of devices in various fields by effectively blocking hydrogen inflows.

Crohn's disease and smoldering multiple myeloma: a case report and literature review.

Crohn's disease (CD) is a chronic inflammatory bowel disease (IBD) that presents with abdominal pain, weight loss, and diarrhea. Although the etiology has not been fully elucidated, both environmental and genetic causes are known to be involved. In chronic inflammatory conditions such as IBD, B lymphocytes are chronically stimulated, and they induce monoclonal expansion of plasma cells, sometimes resulting in monoclonal gammopathy of undetermined significance. Immunomodulators that are commonly used to control inflammation, such as tumor necrosis factor-α (TNF-α) blockers could increase the possibility of hematologic malignancy. The pathogenesis of multiple myeloma in association with TNF-α inhibitor therapy is attributed to decreased apoptosis of plasma cell populations. Here, we describe a case of a 36-year-old male patient who was diagnosed with immunoglobulin A subtype smoldering multiple myeloma during the treatment for CD with infliximab and adalimumab. We report this case along with a review of the literature on cases of multiple myeloma that occurred in conjunction with CD.

Prognostic value and their clinical implication of 89-gene signature in glioma.

Gliomas are the most common and aggressive primary tumors in adults. The current approaches, such as histological classification and molecular genetics, have limitation in prediction of individual therapeutic outcomes due to heterogeneity within the tumor groups. Recent studies have proposed several gene signatures to predict glioma's prognosis. However, most of the gene expression profiling studies have been performed on relatively small number of patients and combined probes from diverse microarray chips. Here, we identified prognostic 89 common genes from diverse microarray chips. The 89-gene signature classified patients into good and bad prognostic groups which differed in the overall survival significantly, reflecting the biological characteristics and heterogeneity. The robustness and accuracy of the gene signature as an independent prognostic factor was validated in three microarray and one RNA-seq data sets independently. By incorporating into histological classification and molecular marker, the 89-gene signature could further stratify patients with 1p/19q co-deletion and IDH1 mutation. Additionally, subset analyses suggested that the 89-gene signature could predict patients who would benefit from adjuvant chemotherapy. Conclusively, we propose that the 89-gene signature would have an independent and accurate prognostic value for clinical use. This study also offers opportunities for novel targeted treatment of individual patients.

Cytogenetic profiles of 2806 patients with acute myeloid leukemia-a retrospective multicenter nationwide study.

The cytogenetic and molecular data is recognized as the most valuable prognostic factor in acute myeloid leukemia (AML). Our aim was to systemically analyze the cytogenetics of Korean AML patients and to compare the cytogenetic profiles of various races to identify possible geographic heterogeneity. We retrospectively reviewed medical records of 2806 AML patients diagnosed at 11 tertiary teaching hospitals in Korea between January 2007 and December 2011. The most common recurrent chromosomal abnormality was t(8;21) (8.8 %, 238/2717), but t(15;17) showed an almost same number (8.6 %,235/2717). Among de novo AML, the most frequent aberrations were t(15;17), observed in 229 (10.7 %). The most common French-American-British (FAB) classification type was M2 (32.2 %), and recurrent cytogenetic abnormalities correlated with the FAB subtypes. Among 283 secondary AML cases, myelodysplastic syndrome was the most common predisposing factor. About 67.1 % of the secondary AML cases were associated with chromosomal aberrations, and chromosome 7 abnormalities (n = 45, 15.9 %) were most common. The incidence of FLT3 internal tandem duplication mutation was relatively low at 15 %. Our study reports certain similarities and differences in comparison to previous reports. Such discrepancies call for extensive epidemiological studies to clarify the role of genetic as well as geographic heterogeneity in the pathogenesis of AML.

Azacitidine Pre-Treatment Followed by Reduced-Intensity Stem Cell Transplantation in Patients with Higher-Risk Myelodysplastic Syndrome.

Azacitidine (AZA) is commonly used in patients with myelodysplastic syndrome (MDS). To determine the role of AZA before allogeneic stem cell transplantation (allo-SCT), we conducted a prospective study of AZA pre-treatment followed by allo-SCT in patients with higher-risk MDS. Twenty-one patients who were scheduled for their third to sixth cycle of AZA pre-treatment followed by allo-SCT were enrolled. AZA pre-treatment was interrupted early in 3 patients (14.3%) because of leukaemic transformation or death. The overall response rate to AZA pre-treatment was 57.1%. There were 2 cases of complete remission, 1 case of partial remission, and 9 cases of haematologic improvement. Fourteen patients (66.7%) received the planned allo-SCT and 5 patients were alive at the last follow-up. Three-year progression-free survival (PFS) and 3-year overall survival (OS) in the 14 patients who received allo-SCT were 30.0% (95% CI 3.3-56.7) and 42.9% (95% CI 17.1-68.7), respectively. PFS and OS were not influenced by response to AZA pre-treatment (p > 0.05). In this study, AZA had a role as a bridge therapy to prevent leukaemic transformation prior to selection of a donor for allo-SCT and showed low toxicity. It may be considered in patients with higher-risk MDS.

Thyroid cancer and T lymphoblastic leukemia in Crohn disease: a case report and literature review.

The effectiveness of the tumor necrosis-α (TNF-α) blockade has changed the treatment of several chronic inflammatory diseases, including inflammatory bowel disease; however, this treatment also has disadvantages. The use of immunosuppressants in combination with infliximab has been associated with greater risk of developing malignant neoplasms. Herein, we report the case of a 33-year-old ethnic Korean man with Crohn disease (CD) who developed papillary thyroid carcinoma (PTC) and, subsequently, T-cell acute lymphoblastic leukemia (ALL) after approximately 16.0 years of immunosuppressant therapy and 5.5 years of infliximab therapy. To our knowledge, this is the first case described in the literature of 2 different malignant neoplasms, 1 of hematologic origin and the other involving the solid organs, in a patient with CD. Through a systematic literature review, we found 28 cases of acute leukemia in adult patients with CD, of whom 22 had myeloid leukemia and 6 had lymphoid leukemia. Half of the patients with ALL underwent TNF-α-blocker therapy in combination with thiopurines.

Role of induction and consolidation chemotherapy in elderly acute myeloid leukemia patients.

The present study sought to elucidate the role of induction and consolidation therapy in elderly patients. We retrospectively collected data of 477 patients who were aged over 60 years at the time of acute myeloid leukemia (AML) diagnosis. The median overall survival (OS) was 339 days in the induction group (n = 266) and 86 days in the best supportive care group (n = 211) (P < 0.001). In the induction group, the complete remission (CR) rate was 58.3 %, and treatment-related death was 15.4 %. Successful induction was related to good performance [Eastern Cooperative Oncology Group (ECOG <2)] [hazard ratio (HR) 3.215; P = 0.002]. Mortality correlated with failure to achieve CR (HR 4.059; P < 0.001) and poor performance status (ECOG >2) (HR 2.731; P = 0.035). In CR patients, poor karyotype and absence of consolidation (HR 2.313; P = 0.003) correlated with mortality. More than one cycle of consolidation was associated with better OS (P < 0.001). Lack of salvage therapy was associated with mortality in patients who did not achieve CR (HR 3.223; P = 0.005). Intensive induction in patients with good performance and >1 cycle of consolidation after CR may be the best strategy for improving OS in elderly AML patients.

Lotus japonicus SUNERGOS1 encodes a predicted subunit A of a DNA topoisomerase VI that is required for nodule differentiation and accommodation of rhizobial infection.

A symbiotic mutant of Lotus japonicus, called sunergos1-1 (suner1-1), originated from a har1-1 suppressor screen. suner1-1 supports epidermal infection by Mesorhizobium loti and initiates cell divisions for organogenesis of nodule primordia. However, these processes appear to be temporarily stalled early during symbiotic interaction, leading to a low nodule number phenotype. This defect is ephemeral and near wild-type nodule numbers are reached by suner1-1 at a later point after infection. Using an approach that combined map-based cloning and next-generation sequencing we have identified the causative mutation and show that the suner1-1 phenotype is determined by a weak recessive allele, with the corresponding wild-type SUNER1 locus encoding a predicted subunit A of a DNA topoisomerase VI. Our data suggest that at least one function of SUNER1 during symbiosis is to participate in endoreduplication, which is an essential step during normal differentiation of functional, nitrogen-fixing nodules.

A case series of autoimmune diseases accompanied by incidentally diagnosed monoclonal gammopathy: is there a link between the two diseases?

AIM: Although the etiology of plasma cell dyscrasia is poorly understood, there is evidence for immune dysregulation or sustained immune stimulation playing a pivotal role in the pathogenesis of these diseases, including chronic infection and autoimmune disorders. In this study, we report four autoimmune disease cases where monoclonal gammopathy (MG) was incidentally found during follow-up. METHODS: We retrospectively reviewed the medical charts and laboratory test results in the following four cases: neuromyelitis optica, Kikuchi disease, Sjögren syndrome and ankylosing spondylosis. RESULTS: The four patients were older than 55 years and the male-to-female ratio was 2 : 2. The autoimmune disease in each case developed differently because two patients had coincidental detection of MG, whereas MG was detected 2 years and 10 years after diagnosis in the other two patients. The amount of M-components in the blood for two cases was ≤ 1 g/dL. For the other two subjects, M-components were ≥ 3 g/dL. CONCLUSION: A high prevalence of MG of undetermined significance (MGUS) has been noted in a series of patients with immune disorders, suggesting a possible association with MG. Further studies should focus on determining how MG relates to various clinical information and laboratory parameters, such as disease duration, disease activity and higher sedimentation rate. In the future, we also need to identify which stimuli, such as cytokine types and levels, can induce lymphocyte clonal transformation and the production of monoclonal antibodies.

Deferasirox improves hematologic and hepatic function with effective reduction of serum ferritin and liver iron concentration in transfusional iron overload patients with myelodysplastic syndrome or aplastic anemia.

BACKGROUND: Transfusional iron overload and its consequences are challenges in chronically transfused patients with myelodysplastic syndromes (MDSs) or aplastic anemia (AA). STUDY DESIGN AND METHODS: This was a prospective, multicenter, open-label study to investigate the efficacy of deferasirox (DFX) by serial measurement of serum ferritin (S-ferritin) level, liver iron concentration (LIC) level using relaxation rates magnetic resonance imaging, and other laboratory variables in patients with MDS or AA. RESULTS: A total of 96 patients showing S-ferritin level of at least 1000 ng/mL received daily DFX for up to 1 year. At the end of the study, S-ferritin level was significantly decreased in MDS (p=0.02366) and AA (p=0.0009). LIC level was also significantly reduced by more than 6.7 mg Fe/g dry weight from baseline. Hemoglobin level and platelet counts were significantly increased from baseline (p=0.002 and p=0.025, respectively) for patients showing significant anemia or thrombocytopenia. Elevated alanine aminotransferase was also significantly decreased from baseline. CONCLUSIONS: This study shows that DFX is effective in reducing S-ferritin and LIC level in transfusional iron overload patients with MDS or AA and is well tolerated. In addition, positive effects in hematologic and hepatic function can be expected with DFX. Iron chelation treatment should be considered in transfused patients with MDS and AA when transfusion-related iron overload is documented.

Laboratory tools for oligo-secretory myeloma diagnosis: capillary electrophoresis versus free light chain assay.

BACKGROUND: To investigate how capillary electrophoresis (CE) works in oligo-secretory myeloma (OSM), we report a case here of OSM using multiple diagnostic methods including gel electrophoresis (GE), CE, and free light chain assay (sFLC). Also, we provide a brief review of laboratory methods to compare their diagnostic utilities in OSM. METHODS: A 72 year-old Korean male suffering from low back pain during the past 6 months was transferred to the department of neurosurgery in order to evaluate abnormal findings in an imaging study, suggesting plasma cell myeloma (PCM) with multiple bone metastasis. CE showed no suspicious M-component; however, it showed increased Kappa components and skewing Kappa/Lambda ratio (K/L). Bone marrow examination revealed plasma cells observed up to 70%, which were compatible with sFLC results. RESULTS: Based on these results, the diagnosis turned out to be OSM with multiple bone metastases. Thereafter, the patient started the first cycle of chemotherapy accompanied by palliative radiation therapy. CONCLUSIONS: In our case, sFLC showed abnormal Kappa and K/L results from both serum and urine specimen. Therefore, it seems to be more sensitive and appropriate than both GE and CE to diagnose OSM.