3D simulation of conductive nanofilaments in multilayer h-BN memristors via a circuit breaker approach.

A 3D simulation of conductive nanofilaments (CNFs) in multilayer hexagonal-BN memristors is performed. To do so, a simulation tool based on circuit breakers is developed including for the first time a 3D resistive network. The circuit breakers employed can be modeled with two, three and four resistance states; in addition, a series resistance and a module to account for quantum effects, by means of the quantum point contact model, are also included. Finally, to describe real dielectric situations, regions with a high defect density are modeled with a great variety of geometrical shapes to consider their influence in the resistive switching (RS) process. The simulator has been tuned with measurements of h-BN memristive devices, fabricated with chemical-vapour-deposition grown h-BN layers, which were electrically and physically characterized. We show the formation of CNFs that produce filamentary charge conduction in our devices. Moreover, the simulation tool is employed to describe partial filament rupture in reset processes and show the low dependence of the set voltage on the device area, which is seen experimentally.

Hybrid 2D-CMOS microchips for memristive applications.

Exploiting the excellent electronic properties of two-dimensional (2D) materials to fabricate advanced electronic circuits is a major goal for the semiconductor industry1,2. However, most studies in this field have been limited to the fabrication and characterization of isolated large (more than 1 µm2) devices on unfunctional SiO2-Si substrates. Some studies have integrated monolayer graphene on silicon microchips as a large-area (more than 500 µm2) interconnection3 and as a channel of large transistors (roughly 16.5 µm2) (refs. 4,5), but in all cases the integration density was low, no computation was demonstrated and manipulating monolayer 2D materials was challenging because native pinholes and cracks during transfer increase variability and reduce yield. Here, we present the fabrication of high-integration-density 2D-CMOS hybrid microchips for memristive applications-CMOS stands for complementary metal-oxide-semiconductor. We transfer a sheet of multilayer hexagonal boron nitride onto the back-end-of-line interconnections of silicon microchips containing CMOS transistors of the 180 nm node, and finalize the circuits by patterning the top electrodes and interconnections. The CMOS transistors provide outstanding control over the currents across the hexagonal boron nitride memristors, which allows us to achieve endurances of roughly 5 million cycles in memristors as small as 0.053 µm2. We demonstrate in-memory computation by constructing logic gates, and measure spike-timing dependent plasticity signals that are suitable for the implementation of spiking neural networks. The high performance and the relatively-high technology readiness level achieved represent a notable advance towards the integration of 2D materials in microelectronic products and memristive applications.

Hardware implementation of a true random number generator integrating a hexagonal boron nitride memristor with a commercial microcontroller.

The development of the internet-of-things requires cheap, light, small and reliable true random number generator (TRNG) circuits to encrypt the data-generated by objects or humans-before transmitting them. However, all current solutions consume too much power and require a relatively large battery, hindering the integration of TRNG circuits on most objects. Here we fabricated a TRNG circuit by exploiting stable random telegraph noise (RTN) current signals produced by memristors made of two-dimensional (2D) multi-layered hexagonal boron nitride (h-BN) grown by chemical vapor deposition and coupled with inkjet-printed Ag electrodes. When biased at small constant voltages (≤70 mV), the Ag/h-BN/Ag memristors exhibit RTN signals with very low power consumption (∼5.25 nW) and a relatively high current on/off ratio (∼2) for long periods (>1 hour). We constructed TRNG circuits connecting an h-BN memristor to a small, light and cheap commercial microcontroller, producing a highly-stochastic, high-throughput signal (up to 7.8 Mbit s-1) even if the RTN at the input gets interrupted for long times up to 20 s, and if the stochasticity of the RTN signal is reduced. Our study presents the first full hardware implementation of 2D-material-based TRNGs, enabled by the unique stability and figures of merit of the RTN signals in h-BN based memristors.

Dose-individualization Efficiently Maintains Sufficient Exposure to Methotrexate without Additional Toxicity in High-dose Methotrexate Regimens for Pediatric Acute Lymphoblastic Leukemia.

OBJECTIVE: Methotrexate (MTX) can be safely administered to most patients but may cause severe toxicity in others. This study aimed to summarize the characteristics of high-dose methotrexate (HD-MTX) chemotherapy and to evaluate whether the modified dose-adjustment program was able to improve the maintenance of sufficient MTX exposure levels while minimizing toxicities. METHODS: We evaluated 1172 cycles of high-dose MTX chemotherapy from 294 patients who were treated according to the CCCG-ALL-2015 protocol (clinical trial number: ChiCTR-IPR-14005706) and analyzed the data of actual MTX dosage, MTX concentration, toxicity, and prognosis. We compared data between the dose-adjustment Program 1 (fixed 20% reduction in dose) and the dose-adjustment Program 2 (dose-individualization based on reassessment of the creatine clearance rate and the MTX concentration-monitoring point at 16 h), which were applied if the MTX clearance was delayed in the previous cycle. RESULTS: The patients who used Program 2 had higher actual MTX infusion doses and infusion rates and were able to better maintain the MTX concentration at 44 h at the established target value than those on Program 1 (P<0.001). No significant differences in toxicities were found between these two programs except that abnormal serum potassium levels and prolonged myelosuppression in intermediate-risk/high-risk patients were more frequently observed in patients using Program 2 (P<0.001). No significant correlations were observed between the MTX dose, dose-adjustment programs, or MTX concentrations and relapse-free survival. CONCLUSION: Adjusting the MTX dose using Program 2 is more efficient for maintaining sufficient MTX exposure without significantly increasing the toxicity.

A New Immunosuppressive Therapy for Very Severe Aplastic Anemia in Children with Autoantibodies.

OBJECTIVE: At present, a number of very severe aplastic anemia (VSAA) patients cannot receive hematopoietic stem cell transplantation (HSCT) or standard immunosuppressive therapy (IST) due to the high cost of therapy, shortage of sibling donors, and lack of resources to support the HSCT. In addition, some VSAA patients with autoantibodies have no life-threatening infections or bleeding at the time of initial diagnosis. Considering the disease condition, economics and other factors, the present study designed a new and relatively mild treatment strategy: cyclosporine A plus pulsed high-dose prednisone (CsA+HDP). METHODS: The present study retrospectively analyzed 11 VSAA patients, who were treated with CsA+HDP in our hospital from August 2017 to August 2019. RESULTS: The median follow-up time for these patients was 24.9 months. The overall response rate was 54.5% (6/11) at six months after the initiation of IST and 81.8% (9/11) at deadline. Five patients achieved complete remission and four patients met the criteria for partial response at the last follow-up. The median time to response for responders was 110 days. Three patients underwent HSCT due to the poor effect of CsA+HDP or to find a suitable transplant donor. Recurrence and clonal evolution were not found in any of these patients. The estimated 3-year overall survival rate and 3-year failure-free survival rate were 100.0% and 72.7%, respectively. In addition, the results revealed that the cyclosporine-prednisone-associated toxicity was mild and well-tolerated by most patients. CONCLUSION: The novel CsA+HDP regimen has good therapeutic effect and safety for VSAA patients with autoantibodies, who have no serious life-threatening infections or bleeding at the time of initial diagnosis.

MoS2 Synapses with Ultra-low Variability and Their Implementation in Boolean Logic.

Brain-inspired computing enabled by memristors has gained prominence over the years due to the nanoscale footprint and reduced complexity for implementing synapses and neurons. The demonstration of complex neuromorphic circuits using conventional materials systems has been limited by high cycle-to-cycle and device-to-device variability. Two-dimensional (2D) materials have been used to realize transparent, flexible, ultra-thin memristive synapses for neuromorphic computing, but with limited knowledge on the statistical variation of devices. In this work, we demonstrate ultra-low-variability synapses using chemical vapor deposited 2D MoS2 as the switching medium with Ti/Au electrodes. These devices, fabricated using a transfer-free process, exhibit ultra-low variability in SET voltage, RESET power distribution, and synaptic weight update characteristics. This ultra-low variability is enabled by the interface rendered by a Ti/Au top contact on Si-rich MoS2 layers of mixed orientation, corroborated by transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and X-ray photoelectron spectroscopy (XPS). TEM images further confirm the stability of the device stack even after subjecting the device to 100 SET-RESET cycles. Additionally, we implement logic gates by monolithic integration of MoS2 synapses with MoS2 leaky integrate-and-fire neurons to show the viability of these devices for non-von Neumann computing.

The Status of Pediatric Patients With Hematologic Malignancy During COVID-19 Pandemic in Wuhan City, China.

Data regarding the epidemiologic characteristics and clinical features of pediatric hematologic patients are limited in this corona virus disease 2019 (COVID-19) crisis. We investigated the status of 113 pediatric hematologic patients in Wuhan union hospital during the COVID-19 pandemic from January 23 to March 10, 2020. All the patients had routine blood and biochemical examination, as well as chest computed tomography scans, and the nucleic acid, immunoglobulin G-immunoglobulin M combined antibodies tests for SARS-CoV-2. After admission, all patients were single-room isolated for 5 to 7 days. The results showed that only 1 (0.88%) child with leukemia was confirmed to have SARS-CoV-2 infection and 15 (13.2%) children were considered as suspected cases. Comparing to the nonsuspected patients, the suspected cases had lower white blood cell count, hemoglobin level, neutrophil count, serum calcium ion level and serum albumin concentration, as well as higher levels of C-reactive protein. All the suspected cases were ruled out of SARS-CoV-2 infection by twice negative tests for the virus. Therefore, the incidence of SARS-CoV-2 infection in hematologic malignancy children was low during the COVID-19 pandemic in China. COVID-19 got early detected and the virus spread out in the ward was effectively blocked by increasing test frequency and using single-room isolation for 5 to 7 days after admission.

Defect-Free Metal Deposition on 2D Materials via Inkjet Printing Technology.

2D materials have many outstanding properties that make them attractive for the fabrication of electronic devices, such as high conductivity, flexibility, and transparency. However, integrating 2D materials in commercial devices and circuits is challenging because their structure and properties can be damaged during the fabrication process. Recent studies have demonstrated that standard metal deposition techniques (like electron beam evaporation and sputtering) significantly damage the atomic structure of 2D materials. Here it is shown that the deposition of metal via inkjet printing technology does not produce any observable damage in the atomic structure of ultrathin 2D materials, and it can keep a sharp interface. These conclusions are supported by abundant data obtained via atomistic simulations, transmission electron microscopy, nanochemical metrology, and device characterization in a probe station. The results are important for the understanding of inkjet printing technology applied to 2D materials, and they could contribute to the better design and optimization of electronic devices and circuits.

The influence of MTHFR genetic polymorphisms on methotrexate therapy in pediatric acute lymphoblastic leukemia.

MTHFR is a crucial enzyme in folate metabolism. This study aimed to determine the relationship between MTHFR genetic polymorphism and elimination and toxicities of methotrexate (MTX). To do that, the study enrolled 145 patients diagnosed with acute lymphoblastic leukemia, who received chemotherapy following the Chinese Children's Cancer Group Acute Lymphoblastic Leukemia (CCCG-ALL)-2015 protocol (clinical trial number: ChiCTR-IPR-14005706). We analyzed the effects of MTHFR C677T and A1298C polymorphisms on MTX elimination and toxicities. Patients with the MTHFR C677T TT genotype could tolerate a significantly higher MTX dose than those with the CC/CT genotype. However, patients with C677T TT genotypes had an increased risk of hypokalemia (1.369 to CC and 1.409 to CT types). The MTX infusion rate in patients with the MTHFR A1298C AC genotype was slightly lower than that in those with CC or AA genotypes. Patients with the A1298C AA genotype had a 1.405-fold higher risk of hepatotoxicity than those with the AC genotype (P > 0.05). There was no significant difference between the prevalence of other toxicities among MTHFR C677T or A1298C genotypes (P > 0.05). Neither MTHFR C677T nor A1298C polymorphisms were significantly associated with delayed MTX clearance. To conclude, MTHFR polymorphisms were not good predictors of MTX-related toxicities.

Variability and Yield in h-BN-Based Memristive Circuits: The Role of Each Type of Defect.

In the race of fabricating solid-state nano/microelectronic devices using 2D layered materials (LMs), achieving high yield and low device-to-device variability are the two main challenges. Electronic devices that drive currents in-plane and homogeneously along the 2D-LMs (i.e., transistors, memtransistors) are strongly affected by local defects (i.e., grain boundaries, wrinkles, thickness fluctuations, polymer residues), as they create inhomogeneities and increase the device-to-device variability, resulting in a poor performance at the circuit level. Here, it is shown that memristors are insensitive to most types of defects in 2D-LMs, even when fabricated in academic laboratories that do not meet industrial standards. The reason is that the currents produced in these devices, which flow out-of-plane across the 2D-LM, are always driven locally by the most conductive locations. Consequently, it is concluded that it is much easier to fabricate 2D-LMs-based solid-state nano/microelectronic circuits using memristors than using transistors or memtransistors, not only due to the inherent simpler fabrication process (i.e., less lithography steps) but also because the local defects do not degrade the yield and variability of memristors considerably.

Perceived Stress, Resilience, and Anxiety Among Pregnant Chinese Women During the COVID-19 Pandemic: Latent Profile Analysis and Mediation Analysis.

Objective: The coronavirus disease 2019 (COVID-19) pandemic has posed a major threat to pregnant women's mental health. This study aimed to characterize the patterns of perceived stress in pregnant Chinese women during the COVID-19 pandemic, to examine the profile differences on anxiety and resilience, and to investigate whether the differences in these profiles on anxiety were mediated by resilience. Methods: From February 28, 2020 to April 26, 2020, a sample of 2,116 pregnant Chinese women who participated in online crisis interventions completed an online self-reporting questionnaire assessing their demographic characteristics, perceived stress, resilience, and anxiety. Results: Latent profile analysis (LPA) on two stress dimensions [perceived helplessness (HEL) and perceived self-efficacy (SEL)] indicated four perceived stress profiles: adaptive (33.7% of the sample), resistant (44.6%), insensitive (19.1%), and sensitive (2.6%). The women with both adaptive and insensitive profiles had the lowest levels of anxiety, whereas those with the resistant profile had the lowest levels of resilience. Multicategorical mediation analysis showed that resilience partially mediated the differences in the pregnant women's anxiety between the adaptive/insensitive and resistant profile. Conclusion: This study showed the heterogeneity in the perceived stress patterns of pregnant women during the COVID-19 pandemic, revealing the internal mechanisms of pregnant women's anxiety using a person-centered approach, and provided initial evidence guiding the development of differentiated stress interventions to alleviate pregnant women's anxiety during the pandemic.

A De Novo Mutation in MYH9 in a Child With Severe and Prolonged Macrothrombocytopenia.

Congenital macrothrombocytopenia is a diverse group of hereditary disorders caused by mutations in the MYH9 gene, which encodes the nonmuscle myosin heavy chain-A, an important motor protein in hemopoietic cells. Thus, the term MYH9-related disease has been proposed, but the clinicopathologic basis of MYH9 mutations has been poorly investigated. Here, we report a sporadic case of Epstein syndrome, an MYH9 disorder, in a 4-year-old Chinese boy who presented with macrothrombocytopenia. He had no family history of thrombocytopenia, hearing loss, or renal failure. A de novo heterozygous MYH9 mutation, c.287C>T; p. (Ser96Leu), was found in this patient. Genotype-phenotype analysis of all reported mutations suggested a domain-specific relationship between the location of the MYH9 mutation and the penetrance of the nonhematologic characteristics of MYH9-related disorders. Our study highlights the importance of suspecting MYH9-related disease even in cases of chronic macrothrombocytopenia without a family history or extrahematologic symptoms.

CSF-1R inhibition disrupts the dialog between leukaemia cells and macrophages and delays leukaemia progression.

Research in the last few years has revealed that leukaemic cells can remodel the bone marrow niche into a permissive environment favouring leukaemic stem cell expansion. Tumour-associated macrophages (TAMs) are prominent components of the tumour microenvironment and play an important role in the onset and progression of solid tumours. However, little is known about their role in the development of acute lymphoblastic leukaemia (ALL). Using a unique mouse model of T-ALL induced by injection of EL4 T-cell lymphoma cells to syngeneic C57BL/6 mice, we report herein that ALL leads to the invasion of leukaemia-associated monocyte-derived cells (LAMs) into the bone marrow and spleen of T-ALL mice. Furthermore, we found that leukaemia cells could polarize bone marrow-derived macrophages (BMDMs) into LAMs. In turn, LAMs were able to protect leukaemia cells from drug-induced apoptosis in vitro. Therapies targeted against the TAMs by inhibiting colony stimulating factor-1 receptor (CSF-1R) have emerged as a promising approach for cancer treatment. In this study, we demonstrate that CSF-1R inhibition inhibits the viability of BMDMs, blocks LAMs polarization and reduces the abundance of LAMs in T-ALL mice. In vivo, combination treatment of CSF-1R inhibitor and vincristine (VCR) dramatically increased the survival of T-ALL mice and delayed leukaemia progression compared with VCR monotherapy. Finally, these data reinforce the role of microenvironments in leukaemia and suggest that macrophages are a potential target for the development of novel therapeutic strategies in T-ALL.

Huai Qi Huang-induced Apoptosis via Down-regulating PRKCH and Inhibiting RAF/MEK/ERK Pathway in Ph+ Leukemia Cells.

Imatinib mesylate (IM) is the first-line treatment for Philadelphia (Ph) chromosomal positive leukemia by inhibiting phosphorylation of substrates via binding to the ABL kinase domain. Because of the drug resistance, side effects and the high cost of IM, it is necessary to find anti-cancer drugs with relatively low toxicity and cost, and enhanced efficacy, such as traditional Chinese medicines (TCMs). As one of TCMs, Huai Qi Huang (HQH) was chosen to treat BV173 and K562 cells. Various concentrations of HQH were added to cells for 24-72 h. Co-treatment of HQH and trametinib, an MEK inhibitor, was used to verify the synergistic effects on cell viability and apoptosis. Knockdown and overexpression of mitogen-activated protein kinase kinase 4 (MEK4) were implemented to demonstrate the role of MEK in cell apoptosis. Cell viability and apoptosis were measured by cell counting kit-8 assay (CCK8) and flow cytometry, respectively. Western blotting and real-time quantitative PCR (RT-qPCR) were used to assess protein and mRNA expression levels, respectively. The results showed that HQH inhibited survival and promoted apoptosis of BV173 and K562 cells in a dose-dependent manner, accompanied with down-regulation of PRKCH mRNA as well as CRAF, MEK4, phospho-ERK (pERK) and BCL2 proteins, and up-regulation of cleaved caspase3 protein. Co-treatment of HQH and trametinib had a synergistic effect on inhibiting survival and promoting apoptosis. MEK4 knockdown increased apoptosis, and had a synergistic effect with HQH. In contrast, MEK4 overexpression decreased apoptosis, and had the opposite effect with HQH. Collectively, the results of this study may identify a therapeutic mechanism of HQH on promoting apoptosis, and provide a potential option for treatment of Ph+ leukemia.

Integrated analysis of dysregulated lncRNA expression in fetal cardiac tissues with ventricular septal defect.

Ventricular septal defects (VSD) are the most common form of congenital heart disease, which is the leading non-infectious cause of death in children; nevertheless, the exact cause of VSD is not yet fully understood. Long non-coding RNAs (lncRNAs) have been shown to play key roles in various biological processes, such as imprinting control, circuitry controlling pluripotency and differentiation, immune responses and chromosome dynamics. Notably, a growing number of lncRNAs have been implicated in disease etiology, although an association with VSD has not been reported. In the present study, we conducted an integrated analysis of dysregulated lncRNAs, focusing specifically on the identification and characterization of lncRNAs potentially involving in initiation of VSD. Comparison of the transcriptome profiles of cardiac tissues from VSD-affected and normal hearts was performed using a second-generation lncRNA microarray, which covers the vast majority of expressed RefSeq transcripts (29,241 lncRNAs and 30,215 coding transcripts). In total, 880 lncRNAs were upregulated and 628 were downregulated in VSD. Furthermore, our established filtering pipeline indicated an association of two lncRNAs, ENST00000513542 and RP11-473L15.2, with VSD. This dysregulation of the lncRNA profile provides a novel insight into the etiology of VSD and furthermore, illustrates the intricate relationship between coding and ncRNA transcripts in cardiac development. These data may offer a background/reference resource for future functional studies of lncRNAs related to VSD.