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Objective: The objective of this study was to determine the uptake and distribution of zinc ions (Zn2+) in two freshwater organisms, Moina macrocopaand Rheocricotopuslarvae using a high-affinity low-molecular-weight Zn2+-ion-selective fluorescence probe. Methods: M. macrocopaand Rheocricotopuslarvae were exposed separately to dissolved Zn2+(0.1 and 1 mg/L) for 12, 24, and 48 h in three replicates along with a control. Later, the organisms were incubated with the fluorescence probe in six-well plates in the dark at room temperature. At the end of the incubation period, the organisms were washed with a phosphate buffer solution (0.01 M). The live organisms were then imaged using a fluorescence microscope and the fluorescence intensities of the images were determined. Results: The results revealed that the Zn2+ions are uptaken and internalized into the bodies of the organisms exposed to Zn2+ion concentrations, as indicated by a significant increase in the fluorescence intensities of the fluorescence images of the organisms. According to the fluorescence images, the Zn2+ions were mainly localized in the lower gut region of M. macrocopaat the end of 48 h. However, in Rheocricotopuslarvae, the Zn2+ions were detected in the midgut region of the digestory tube after 48 h of exposure. Therefore, this was dependent upon both the Zn2+concentration in the exposure media and the exposure duration. Conclusion: Taken together, the distribution of Zn2+ions in different aquatic species is species-specific. Furthermore, the present study provides insight into the potential use of high-affinity low-molecular-weight Zn2+-ion-selective fluorescence probes to detect labile Zn2+in aquatic organisms and the toxicological implications of zinc pollution in aquatic environments.

Deep-learning side-channel attacks, applying deep neural networks to side-channel attacks, are known that can easily attack some existing side-channel attack countermeasures such as masking and random jitter. While there have been many studies on profiled deep-learning side-channel attacks, a new approach that involves applying deep learning to non-profiled attacks was proposed in 2018. In our study, we investigate the structure of multi-layer perceptrons and points of interest for non-profiled deep-learning side-channel attacks using the ANSSI database with a masking countermeasure. The results of investigations indicate that it is better to use a simple network model, apply regularization to prevent over-fitting, and select a wide range of power traces that contain side-channel information as the points of interest. We also implemented AES-128 software implementation protected with the Rotating Sboxes Masking countermeasure, which has never been attacked by non-profiled deep-learning side-channel attacks, on the Xmega128 microcontroller and carried out non-profiled deep-learning side-channel attacks against it. Non-profiled deep-learning side-channel attacks successfully recovered all partial keys while the conventional power analysis could not. The attack results also showed that the least significant bit is the adequate selection for successful non-profiled deep-learning side-channel attacks, but the best labeling method may vary depending on the implementation of the countermeasure algorithm. We conducted two experimental analyses to clarify that deep-learning side-channel attacks learn mask values used in the masking countermeasure. One is the gradient visualization used in previous studies, and the other is a new analysis method using partial removal of power traces.

Monocytic acute myeloid leukemia (AML) responds poorly to current treatments, including venetoclax-based therapy. We conducted in vivoand in vitroCRISPR-Cas9 library screenings using a mouse monocytic AML model and identified SETDB1 and its binding partners (ATF7IP and TRIM33) as crucial tumor promoters in vivo. The growth-inhibitory effect of Setdb1depletion in vivois dependent mainly on natural killer (NK) cell-mediated cytotoxicity. Mechanistically, SETDB1depletion upregulates interferon-stimulated genes and NKG2D ligands through the demethylation of histone H3 Lys9 at the enhancer regions, thereby enhancing their immunogenicity to NK cells and intrinsic apoptosis. Importantly, these effects are not observed in non-monocytic leukemia cells. We also identified the expression of myeloid cell nuclear differentiation antigen (MNDA) and its murine counterpart Ifi203 as biomarkers to predict the sensitivity of AML to SETDB1depletion. Our study highlights the critical and selective role of SETDB1 in AML with granulo-monocytic differentiation and underscores its potential as a therapeutic target for current unmet needs.

Arsenic (As) contamination of groundwater is one of the main obstacles preventing people from having easy access to potable water. Gypsum-based a porous filter media block (PFMB) made with moringa bark was proposed to remove arsenic (III) from aqueous solutions. The adsorption isotherms using Langmuir (R2= 0.976) and Freundlich (R2= 0.967) and kinetics using pseudo-first and second order and intraparticle diffusion models were achieved. The removal rates of PFMB using 10 g/L in batch experiments were found to be 98.4 % and 94.2 % for 0.50 and 1.0 ppm, respectively. The efficiency was evaluated by varying the material composition, pH, and experimental conditions using a machine learning model with an R2= 0.95. A new approach to forecasting adsorption capacity based on material composition and experimental data allows the effective determinate to be found from a wider perspective. The model explanation with shapley additive value (SHAP) and partial dependence plots (PDP) showed the initial concentration, and time were the most influential factors in the adsorption process. Arsenic (III) adsorption on the innovative composite material appears promising, which will ensure the reuse and effective disposal of solid waste. ANN can be used to evaluate and predict new conditions without lab experimentation.

Physically unclonable functions (PUFs) are assumed to provide high tamper resistance against counterfeiting and hardware attacks since PUFs extract inherent physical properties from random and uncontrollable variations in manufacturing. Recent studies have reported on the vulnerabilities of PUFs to physical and mathematical attacks. This paper focuses on the security evaluation of a ring-oscillator PUF (RO PUF) against electromagnetic analysis (EMA) attacks. We designed an RO PUF with a 180-nm CMOS process to evaluate the threats of EMA attacks. The power consumption of this RO PUF is reduced as much as possible to reduce EM leaks, and EMA resistance is enhanced in the layout design. We present the results of EMA attacks on our RO PUF and discuss the threats of such attacks on the application-specific integrated circuit implementation of RO PUFs. We also propose an EMA attack based on geometric leak (Sugawara in: Cryptographic Hardware and Embedded Systems-CHES 2013—15th International Workshop, Santa Barbara, CA, USA, August 20–23, 2013, Proceedings, 2013. https://doi.org/10.1007/978-3-642-40349-1_10) for RO PUFs. All components of an RO PUF are usually arranged in a matrix or array. The geometric periodicity in the layout of RO PUFs leaks secret PUF responses. Though previous studies required identifying oscillation frequency of each RO from measured EMA traces, the proposed attack, called simple EMA attack based on geometric leak, reveals a PUF response from one measured EM trace directly. This attack correctly predicted 94.2% of PUF responses of our RO PUF. We present how a PUF response is revealed from a measured EM trace, suggesting that such an attack poses a serious threat to RO PUFs.

Micro and nano plastics (MNPs) have emerged as significant environmental pollutants globally, with numerous research findings extensively addressing the environmental and biohazards resulting from the bioavailability of contaminants. Rice, serving as the staple carbohydrate source for more than half of the global population, demands a concrete understanding of MNPs' toxicity in rice plants. However, the literature pertaining to the impact of MNPs on rice plant growth and development is limited and the future research scope related to MNPs exposure in rice plants is poorly defined. Thus, this review aims to synthesize current research findings regarding MNPs exposure in rice plants and identify existing research gaps. Furthermore, this review article comprehensively discusses up-to-date findings on various impacts on rice plant growth and development, covering key areas such as morphological, biochemical, physiological, metabolic, molecular, and microbial alterations. In addition, it explores MNP sources, uptake and translocation mechanisms, potential health risks, and available remedial approaches to alleviate MNPs bioavailability in rice plants. The review concludes that addressing the current research gaps related to MNPs in paddy fields requires further studies in the future. This would contribute to a more comprehensive understanding of the impact of MNPs on rice plants and aid in developing effective mitigation strategies.

The process of leaf litter breakdown is essential as a main energy source for aquatic life in stream ecosystems. This process is complicated due to the interaction among the stream's physical, chemical, and biological characteristics as well as the composition of litter. This study investigated the variation of litter breakdown rates with different water qualities and microbial activities influenced by dam operation. Litter bags were installed along Nakatsugawa River, which is regulated by Takizawa Dam, and Arakawa River in Saitama Prefecture, central Japan, during autumn and winter. Three dominant leaf species were studied, namely Quercus serrata, Carpinus cordata, and Acer mono. The factors possibly affecting the litter breakdown process were: (1) a 4 °C higher water temperature downstream than upstream of the dam in the Nakatsugawa; (2) high bacterial productivity in the Nakatsugawa; (3) high silt deposition on the litters in the Arakawa; and (4) low contents of Dissolved Organic Carbon (DOC) and nutrients in the Arakawa. In the Nakatsugawa, neither a contribution of the dam to a higher breakdown rate nor recovery of the rate to upstream conditions far downstream was found. However, the breakdown rate was lower in the Arakawa than in the Nakatsugawa. Inorganic deposition on litter, DOC, Na+, Mg2+, Ca2+and NO3−were believed to play a main role in litter breakdown.

Additional sex combs like 1 (ASXL1) is frequently mutated in myeloid malignancies and clonal hematopoiesis of indeterminate potential (CHIP). Although loss of ASXL1 promotes hematopoietic transformation, there is growing evidence that ASXL1 mutations might confer an alteration of function. In this study, we identify that physiological expression of a C-terminal truncated Asxl1 mutant in vivo using conditional knock-in (KI) results in myeloid skewing, age-dependent anemia, thrombocytosis, and morphological dysplasia. Although expression of mutant Asxl1 altered the functions of hematopoietic stem cells (HSCs), it maintained their survival in competitive transplantation assays and increased susceptibility to leukemic transformation by co-occurring RUNX1 mutation or viral insertional mutagenesis. KI mice displayed substantial reductions in H3K4me3 and H2AK119Ub without significant reductions in H3K27me3, distinct from the effects of Asxl1 loss. Chromatin immunoprecipitation followed by next-generation sequencing analysis demonstrated opposing effects of wild-type and mutant Asxl1 on H3K4me3. These findings reveal that ASXL1 mutations confer HSCs with an altered epigenome and increase susceptibility for leukemic transformation, presenting a novel model for CHIP.

ASXL1 plays key roles in epigenetic regulation of gene expression through methylation of histone H3K27, and disruption of ASXL1 drives myeloid malignancies, at least in part, via derepression of posterior HOXA loci. However, little is known about the identity of proteins that interact with ASXL1 and about the functions of ASXL1 in modulation of the active histone mark, such as H3K4 methylation. In this study, we demonstrate that ASXL1 is a part of a protein complex containing HCFC1 and OGT; OGT directly stabilizes ASXL1 by O-GlcNAcylation. Disruption of this novel axis inhibited myeloid differentiation and H3K4 methylation as well as H2B glycosylation and impaired transcription of genes involved in myeloid differentiation, splicing, and ribosomal functions; this has implications for myelodysplastic syndrome (MDS) pathogenesis, as each of these processes are perturbed in the disease. This axis is responsible for tumor suppression in the myeloid compartment, as reactivation of OGT induced myeloid differentiation and reduced leukemogenecity both in vivo and in vitro. Our data also suggest that MLL5, a known HCFC1/OGT-interacting protein, is responsible for gene activation by the ASXL1–OGT axis. These data shed light on the novel roles of the ASXL1–OGT axis in H3K4 methylation and activation of transcription.

Acute myeloid leukemia (AML) with monocytic differentiation (monocytic AML) responds poorly to current treatments, including venetoclax-based therapy. To identify novel therapeutic targets in monocytic AML, we conducted in vivoand in vitroCRISPR/Cas9 library screens using a pooled sgRNA library targeting epigenetic regulators with a mouse monocytic AML model driven by SETBP1and ASXL1mutations (cSAM: combined expression of SETBP1 and ASXL1 Mutations). We ranked all the epigenetic genes according to the in vivospecific essentiality, and selected several candidates which were more depleted in mice rather than in cell cultures. The top-ranked gene was Setdb1, which encodes a histone H3 lysine 9 (H3K9) methyltransferase. In addition, several H3K9 trimethylation (H3K9me3) regulators, ATF7IP and TRIM33, were also more important in vivothan in vitroin our screens. ATF7IP is a cofactor of SETDB1 to enhance its enzymatic activity. TRIM33 is also involved in H3K9me3 modification. These data suggest the critical role of the SETDB1-ATF7IP-TRIM33 H3K9 methyltransferase complex in the development of AML in vivo.

Chemical modifications of RNA are regulated by a series of readers, writers, and erasers that dictate gene expression. Two new studies in Cell Stem Cell1,2identify roles for the N6-methyladenosine (m6A) methyltransferase METTL16 and the m6A reader IGF2BP2 in leukemia-initiating cells, illuminating exciting new therapeutic targets for leukemia.

A successful detection of the stealthy dopant-level circuit (trojan), proposed by Becker et al. at CHES 2013 (LNCS 8086:197–214, 2013), is reported. Contrary to an assumption made by Becker et al. dopant types in active region are visible with either scanning electron microscopy (SEM) or focused ion beam (FIB) imaging. The successful measurement is explained by a technique called the passive voltage contrast (Rosenkranz J Mater Sci Mater Electron 22(10):1523–1535, 2011) which is used to analyze failures in large-scale integration (LSI). The experiments are conducted by measuring a dedicated chip. The chip uses the diffusion programmable device (Shiozaki et al. Diffusion programmable device: a device to prevent reverse engineering, IACR Cryptology ePrint Archive 2014/109 2014): an anti-reverse engineering technique by the same principle as the stealthy dopant-level trojan. The chip is delayered down to the contact layer, and images are taken with (1) an optical microscope, (2) SEM, and (3) FIB. As a result, the four possible dopant–well combinations, namely (i) p+/n-well, (ii) p+/p-well, (iii) n+/n-well and (iv) n+/p-well are distinguishable in the SEM images. Partial but sufficient detection is also achieved with FIB. Although the stealthy dopant-level circuits are visible, they potentially make a detection harder. That is because the contact layer should be measured. We show that imaging the contact layer is at most 16 times more expensive than that of a metal layer in terms of the number of images.

In current countermeasure design trends against differential power analysis (DPA), security at gate level is required in addition to the security algorithm. Several dual-rail pre-charge logics (DPL) have been proposed to achieve this goal. Designs using ASIC can attain this goal owing to its backend design restrictions on placement and routing. However, implementing these designs on field programmable gate arrays (FPGA) without information leakage is still a problem because of the difficulty involved in the restrictions on placement and routing on FPGA.This article describes our novel masked dual-rail pre-charged memory approach, called “intra-masking dual-rail memory (IMDRM) on LUT”, and its implementation on FPGA for Side-Channel Attack-resistant (SCA-resistant) AES. In the proposed design, all unsafe nodes, such as unmasking and masking, and parts of dual-rail memory with unsafe buses (buses that are not masked) are packed into a single LUT. This makes them balanced and independent of the placement and routing tools. Inputs and outputs of all LUTs are masked, and so can be considered safe signals. Several LUTs can be combined to create a safe SBox. The design is independent of the cryptographic algorithm, and hence, it can be applied to available cryptographic standards such as DES or AES as well as future standards. It requires no special placement or route constraints in its implementation. A correlation power analysis (CPA) attack on 1,000,000 traces of AES implementation on FPGA showed that the secret information is well protected against first-order side-channel attacks. Even though the number of LUTs used for memory in this implementation is seven times greater than that of the conventional unprotected single-rail memory table-lookup AES and three times greater than the implementation based on a composite field, it requires a smaller number of LUTs than all other advanced SCA-resistant implementations such as the wave dynamic differential logic, masked dual-rail pre-charge logic, and threshold.

Leaks inside semi-custom application-specific integrated circuit design primitives are rigorously investigated. The study is conducted by measuring a dedicated test element group chip with a small magnetic field probe on the chip surface. Measurement targets are standard cells and a memory macro cell. Leaks inside the primitives are focused, as many of conventional countermeasures place measurability boundaries on these primitives. Firstly, it is shown that the current-path leak: a leak based on input-dependent active current path within a standard cell (Takahashi 2012; Takahashi and Matsumoto IEICE Electron Express 9:458–463, 2012) is measurable. Major gate-level countermeasures [Random Switching Logic (RSL), MDPL, and WDDL] become vulnerable if the current-path leak is considered. Secondly, it is shown that the internal-gate leak: a leak based on non-linear sub-circuit within an XOR cell is measurable. It can be exploited to bias the distribution of the random mask. Thirdly, it is shown that the geometric leak: a leak based on geometric layout of the memory matrix structure is measurable. It is a leak correlated to integer representation (cf. Hamming weight) of the memory address. We also show that a ROM-based countermeasure (dual-rail RSL memory; Hashimoto et al. 2012) becomes vulnerable with the geometric leak. A general transistor-level design method to counteract the current-path and internal-gate leaks is also shown.

AbstractThis study has confirmed the performance of a recycled gypsum composite mortar (RGCM) foundation, developed for the foundation work of a single-family house using a raw material recycled from waste gypsum boards generated from the construction of new buildings or the demolition of old buildings, equivalent or superior to that of existing foundation work methods. The compressive strength of an RGCM core sample depends on water content and the mixing cement ratio. It is 158 kN/m2for a high water/composite ratio (115%) sample after 28-days of air-drying, which is more than the maximum load of the sleeping foundation (50 kN/m2). The stress of the sleeping foundation can be transferred to the foundation ground. The hardening surface of the RGCM is smooth and there are no problems related to marking and joinability. Even when the excavated surface is rough, the RGCM can be used to fill the gaps resulting from its high fluidity, similarly to the SL material. Thus, the RGCM is integrated with the foundation ground. The RGCM foundation is advantageous from the viewpoints of environmental friendliness (recyclability), and is expected to be used as the foundation footing of houses.

Supercapacitors can store and deliver energy by a simple charge separation, and thus they could be an attractive option to meet transient high energy density in operating fuel cells and in electric and hybrid electric vehicles. To achieve such requirements, intensive studies have been carried out to improve the volumetric capacitance in supercapacitors using various types and forms of carbons including carbon nanotubes and graphenes. However, conventional porous carbons are not suitable for use as electrode material in supercapacitors for such high energy density applications. Here, we show that edge‐enriched porous carbons are the best electrode material for high energy density supercapacitors to be used in vehicles as an auxiliary powertrain. Molten potassium hydroxide penetrates well‐aligned graphene layers vertically and consequently generates both suitable pores that are easily accessible to the electrolyte and a large fraction of electrochemically active edge sites. We expect that our findings will motivate further research related to energy storage devices and also environmentally friendly electric vehicles.

Imbalanced biomass allocation patterns in emergent aquatic plants to above and below-ground structures as a response to climatic variations and water depth were investigated on the basis of observation of three stable homogeneous populations established under different water regimes and climatic environments in Goulburn and Ourimbah, New South Wales, Australia, from August 2003 to December 2004. The growth of shoots depended on water inundation-drawdown patterns and climatic variations. Shoot density was greater in shallow water but with shorter shoot length and less maximum above-ground biomass density than for plant stands in deep water. Deep-water populations attained higher below-ground biomass with higher above to below-ground biomass ratio than for the shallow-water population. Translocation of carbohydrate reserves between above and below-ground organs in deep-water populations were mostly downward throughout the year whereas the depletion–recharge pattern varied seasonally in shallow water populations. Shoots of deep-water populations grew year-round whereas in shallow water shoots died off after recession of the water level with no re-growth afterward, showing that Eleocharis sphacelatais better adapted to deep water and is stressed under shallow-water conditions. A mathematical model was formulated to describe the growth patterns of E. sphacelataand subsequently to predict the effect of water depth on production. Model simulations are in satisfactory agreement with observed patterns of growth. The model also predicts that maximum production decreases sharply with increasing water depth.Imbalanced biomass allocation patterns in emergent aquatic plants to above and below-ground structures as a response to climatic variations and water depth were investigated on the basis of observation of three stable homogeneous populations established under different water regimes and climatic environments in Goulburn and Ourimbah, New South Wales, Australia, from August 2003 to December 2004. The growth of shoots depended on water inundation-drawdown patterns and climatic variations. Shoot density was greater in shallow water but with shorter shoot length and less maximum above-ground biomass density than for plant stands in deep water. Deep-water populations attained higher below-ground biomass with higher above to below-ground biomass ratio than for the shallow-water population. Translocation of carbohydrate reserves between above and below-ground organs in deep-water populations were mostly downward throughout the year whereas the depletion–recharge pattern varied seasonally in shallow water populations. Shoots of deep-water populations grew year-round whereas in shallow water shoots died off after recession of the water level with no re-growth afterward, showing that Eleocharis sphacelatais better adapted to deep water and is stressed under shallow-water conditions. A mathematical model was formulated to describe the growth patterns of E. sphacelataand subsequently to predict the effect of water depth on production. Model simulations are in satisfactory agreement with observed patterns of growth. The model also predicts that maximum production decreases sharply with increasing water depth.

Activated graphitizing carbons, mesophase carbons prepared by alkaline activation for electrochemical Capacitors (Electric double-layer capacitors; EDLCs) with organic liquid electrolytes showed larger specific capacitance per unit volume (F/cm 3 ) than those of conventional activated carbon materials. The physical characteristic is lower specific surface area, compared with a conventional activated carbon. It has been supposed that the electric double-layer interfaces of alkaline activated mesophase carbon which have high density per unit volume were dominated by the edge plane of hexagonal lattice, compared with those of conventional activated carbon material.

The biotransformation of (RS)-1-phenylethanol with cultured cells of Catharanthus roseusgave its vicianoside [a-L-arabinopyranosyl-(1-6)-ß-D-glucopyranoside], primeveroside [ß-D-xylopyranosyl-(1-6)-ß-D-glucopyranoside] and gentiobioside [ß-D-glucopyranosyl-(1-6)-ß-D-glucopyranoside] via the corresponding glucoside. It was found that primeveroside and gentiobioside were enantioselectively composed of only (R)-1-phenylethanol as its aglycone moiety.

SummaryThe structure of the middle lamella in Pinus thunbergiihas been studied by the rapid-freeze deep-etching (RFDE) technique in combination with transmission electron microscopy (TEM). The ultrastructure of the compound middle lamella was studied in the early phases of the development of woody tissue in the cambial and differentiating xylem, before the heavy incrustation with lignin had occurred. Lignified middle lamella in the xylem was studied both directly and after delignification. It was found that the structure of the unlignified middle lamella in the cambium/developing xylem consists of a fine irregular network probably containing pectin and hemicellulose. As a result of lignin incrustation, the middle lamella becomes increasingly dense and the surface structure of the fully lignified middle lamella appeared to be compact and partly covered with globular structures. After delignification of the lignified middle lamella a thin network with a different structure was revealed. This network probably mainly consists of hemicellulose. No microfibrils of the type that occurs in the primary and secondary walls were found in the middle lamella.

Paraspeckles are membraneless organelles formed through liquid-liquid phase separation and consist of multiple proteins and RNAs, including NONO, SFPQ, and NEAT1. The role of paraspeckles and the component NONO in hematopoiesis remains unknown. In this study, we show histone modifier ASXL1 is involved in paraspeckle formation. ASXL1 forms phase-separated droplets, upregulates NEAT1expression, and increases NONO-NEAT1interactions through the C-terminal intrinsically disordered region (IDR). In contrast, a pathogenic ASXL mutant (ASXL1-MT) lacking IDR does not support the interaction of paraspeckle components. Furthermore, paraspeckles are disrupted and Nono localization is abnormal in the cytoplasm of hematopoietic stem and progenitor cells (HSPCs) derived from ASXL1-MT knockin mice. Nono depletion and the forced expression of cytoplasmic NONO impair the repopulating potential of HSPCs, as does ASXL1-MT. Our study indicates a link between ASXL1 and paraspeckle components in the maintenance of normal hematopoiesis.

Quiescent hematopoietic stem cells (HSCs) are typically dormant, and only a few quiescent HSCs are active. The relationship between “dormant” and “active” HSCs remains unresolved. Here we generate a G0marker (G0M) mouse line that visualizes quiescent cells and identify a small population of active HSCs (G0Mlow), which are distinct from dormant HSCs (G0Mhigh), within the conventional quiescent HSC fraction. Single-cell RNA-seq analyses show that the gene expression profiles of these populations are nearly identical but differ in their Cdk4/6 activity. Furthermore, high-throughput small-molecule screening reveals that high concentrations of cytoplasmic calcium ([Ca2+]c) are linked to dormancy of HSCs. These findings indicate that G0M separates dormant and active adult HSCs, which are regulated by Cdk4/6 and [Ca2+]c. This G0M mouse line represents a useful resource for investigating physiologically important stem cell subpopulations.

Paraspeckles are sub-nuclear structures found in the interchromatin space of mammalian cells. The core paraspeckle components include a lncRNA NEAT1 and members of the DBHS family of proteins: NONO, SFPQ, and PSPC1. Paraspeckles and their components play diverse roles in gene regulatory networks, including transcription, alternative RNA splicing, nuclear retention of RNA, and DNA repair. Although a previous study showed the presence of paraspeckles in hematopoietic stem and progenitor cells (HSPCs), their roles in normal and malignant hematopoiesis remain largely unknown.

Ogawa: Qiagen Corporation: Patents & Royalties; RegCell Corporation: Equity Ownership; Asahi Genomics: Equity Ownership; ChordiaTherapeutics, Inc.: Consultancy, Equity Ownership; Dainippon-Sumitomo Pharmaceutical, Inc.: Research Funding; Kan Research Laboratory, Inc.: Consultancy.

No relevant conflicts of interest to declare.

Somatic mutations of the ASXL1gene are recurrently detected in age-related clonal hematopoiesis (CH). However, how ASXL1 mutations causes CH are not understood. Here, using knockin (KI) mice expressing a C-terminally truncated form of ASXL1-mutant (ASXL1-MT), we investigated the effect of ASXL1-MT on physiological aging in hematopoietic stem cells (HSCs).

This article describes the improvement of a self-consistent proximity effect correction to fabricate 1:1 X-ray masks. The present method has two features; the first is the change of sampling point from pattern edges to the center. This is effictive in saving on the calculation time, and it is theoretically shown that the deposited energy intensity at the edge is equal to that obtained with the conventional method. The other is to combine the pattern shape and additional dose modulations for finer patterns (?4?f, ?fis the forward scattering range of electrons) with the ordinary dose modulation method. The algorithm is verified by experiments and simulations, and is found to be effective in reproducing 0.1 µ m patterns with high accuracy.

Electron beam direct writing technologies for 0.3-µm devices are studied in this paper. In order to prevent charging effects, TQV, which is a varnish consisting of 7, 7, 8, 8-tetracyano quino dimethane complex salt, has been coated on the top layer of a trilayer resist system. The effectiveness of TQV coating is indicated by the experimental results obtained from test patterns. A proximity effect correction system with several strategies to reduce the correction time and output data volume has been developed. These technologies have been adopted for the fabrication of ULSI circuit patterns with the dimension of about 0.3 µm. The calculation time and the output data volume of a proximity effect correction are reduced considerably by using new methods. It is revealed that 0.3-µm ULSI patterns can be precisely fabricated by these new technologies.

X-ray mask fabrication techniques, which are used in X-ray lithography for 0.25-µm devices, are studied in this paper. Initially, the process latitude for both the single- and trilayer processes is discussed according to the simulation results. The bottom layer thickness in the trilayer process was optimized to reduce the influence of backscattered electrons, and a proximity effect correction was introduced for the 0.25-µm pattern fabrication. In order to suppress membrane heating, a reverse-side polyvinyl alcohol (PVA) coating method was developed. The temperature was monitored with a special thermometer, and the effectiveness of the PVA coating was examined.

Novel techniques for electron beam (EB) direct writing are established for the development of sub-quarter micron devices. These techniques include 1) use of highly stable processes for positive and negative chemical amplification resists, 2) precise pattern size control by way of proximity effect correction using the pattern-area-density method, 3) a practical improvement technique for pattern size error at the exposure-field boundary, and 4) a novel alignment technique for a substrate covered with a heavy metal film. Successful fabrication of sub-quarter-micron test devices indicates that variable-shaped EB direct writing using these techniques is the best tool for research and development of advanced devices.

The influence of buried oxide thickness on short-channel effects in silicon-on-insulator metal-oxide-semiconductor field-effect transistors (SOI MOSFET's) is investigated. It is shown by analytical modeling and numerical simulation that, although a thin buried oxide helps to reduce the charge-sharing component of source and drain electric fields through the oxide layer, substrate depletion underneath the thin buried oxide counteracts the oxide thinning. Although this effect is desired below the source and drain regions to maintain the SOI inherent low junction capacitances, it is detrimental to short-channel-effect suppression. The calculated results are experimentally confirmed on 0.1 µm SOI MOSFET's fabricated on both standard and low-dose separation-by-implanted-oxygen (SIMOX) substrates. A new structure for 0.15 µm SOI MOSFET applications on a thin buried oxide substrate is proposed in which substrate depletion below the channel-forming region can be suppressed locally using self-aligned deep ion implantation.

Proximity effect correction for electron beam (EB) direct writing is studied in this paper. An iterative calculation of exposure-dose modulation by equalizing the deposited energy of all figures requires an extremely long calculation time, especially in the case of high EB acceleration voltage. Therefore it is not practical for the correction of LSI. The correction method using pattern-area density, however, could realize the high-speed proximity effect correction. In this paper, this method is first investigated from the standpoint of the correction accuracy. Next, the applicability of this method to two critical cases is examined. One is the patterning on a heavy-metal substrate, on which backscattering yield of electrons is high. The other is the application to the cell-projection exposure, in which it is impossible to modulate exposure dose inside the cell. Lastly, the calculation time of the proximity effect correction is evaluated for 64 Mbit dynamic random access memories (MbDRAMs).

An X-ray mask fabrication technology using a tungsten (W) absorber with a chromium (Cr) mask and indium titanium oxide (ITO) stopper was developed. When SF6was used as the dry etching gas, substantial side etching occurred because the F radical reacts with W on the sidewall. In order to prevent side etching, a SF6and CHF3gas mixture was applied; however, the ratio of dry etching rate of W to that of resist is low. Furthermore, the underlying layer such as that of silicon dioxide (SiO2), which was used as the etching stopper, was easily damaged. Instead of a resist mask and SiO2stopper, a Cr layer as the etching mask and ITO layer as the stopper layer were applied. By the use of these structures and etching procedures, high aspect ratio W patterns with vertical sidewalls have been successfully fabricated.

The electron beam (EB) direct writing technique for the hole pattern of quarter-micron devices was developed. The resist structure used in this technique was EB resist (0.5 µm)/"buffered tungsten (W) layer" (0.05 µm)/SiO2/Si substrate. The "buffered W layer" was dry-etched using an EB resist mask, then SiO2was dry-etched using the "buffered W layer" as the dry-etching mask. The alignment mark structure was TiN (0.035 µm)/"alignment W layer" (0.085 µm)/Al (0.4 µm) multilayered metallization which was used for metal wiring beneath the SiO2layer. The thicknesses of the "alignment W layer" and "buffered W layer" have a strong influence on alignment mark detection and were optimized using computer simulation. Due to this structure and process sequence, high resolution was attained without using a trilayer resist process. In addition to this resist structure, proximity effect correction with data undersizing was applied in order to fabricate patterns as designed.

Properties of DC-sputtered W-Ti absorber films such as internal stress, density and microstructure were systematically investigated for X-ray mask application. Smooth, stress-free amorphous W-Ti films with a comparatively high density of 16.5-17.0 g/cm3were obtained by optimizing several conditions: gas pressure, N2content in the working gas, DC power density and annealing temperature. The reproducibility of the film stress was about ±5×107Pa. Reproducibility was found to be mainly determined by the degree to which the sputtering tool used could be controlled. Furthermore, it was confirmed that the optimized absorber films offered good stability under stress within 1×107Pa when stored in an air atmosphere for more than 250 days.