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Termites are believed to have evolved in a way that optimizes their foraging efficiency, which involves both searching for food and transporting it efficiently. Although the search efficiency has been well-studied through tunnel pattern analysis, transport efficiency has received limited attention due to the challenges of directly observing behavior that is highly influenced by environmental conditions. In this study, we introduce an individual-based model to simulate transport behavior and examine transport efficiency (E) by considering the tunnel surface irregularities and curvature, which are critical environmental factors. The model is characterized by four control variables: tunnel curvature (k1), termite stopping time at irregularity sites (k2), irregularity distribution (k3), and irregularity density (k4). The simulation results indicate that as k1 increases, E decreases, while k3 has little impact on E. The impact of k4 on E is decisive; when k4 ≤ 6, an increase in k4 results in increased traffic jam frequency and a faster reduction in E. However, when k4 > 6, the jamming frequency is not significantly affected, reducing the decrease in E. k2 strongly contributes to reducing E without significantly affecting the frequency. In the discussion section, we explore potential mechanisms that termites use to maintain transport efficiency in heterogeneous soils, and discuss how to improve the model to better reflect real-termite systems.

We developed a spatiotemporal proximity photo-crosslinking by visible light activation (Spotlight) method to capture protein–protein interactions in live systems.

Control over chemo- and regioselectivity is a critical issue in the heterobiaryl synthesis via C–H oxidative coupling. To address this challenge, a strategy to invert the normal polarity of indoles was developed.

Site-selective modification of oligonucleotides serves as an indispensable tool in many fields of research including research of fundamental biological processes, biotechnology, and nanotechnology. Here we report chemo- and regioselective modification of oligonucleotides based on rhodium(I)-carbene catalysis in a programmable fashion. Extensive screening identifies a rhodium(I)-catalyst that displays robust chemoselectivity toward base-unpaired guanosines in single and double-strand oligonucleotides with structurally complex secondary structures. Moreover, high regioselectivity among multiple guanosines in a substrate is achieved by introducing guanosine-bulge loops in a duplex. This approach allows the introduction of multiple unique functional handles in an iterative fashion, the utility of which is exemplified in DNA-protein cross-linking in cell lysates., The methods for investigation of DNA-binding proteins require site-selective chemical modifications to be introduced into oligonucleotides. Here, the authors report a chemo- and regioselective method for the modification of unpaired guanosines in single- and double-stranded oligonucleotides, based on Rh(I)-carbene catalysis.

In this study, the branch-length similarity entropy profile is estimated by mapping the time-series signal to the circumference of the time circle, and the self-similarity is defined based on the profile. To explore the self-similarity property, the effect of the distance between two signals, “0” and “1”, on the entropy value for signal “1” is investigated. Furthermore, two application problems are addressed: quantification of the mixing state of fragments and clusters, and characterization of the behavioral trajectory of an organism. The results indicate that use of the self-similarity property solves both the problems. Additionally, the problems that must be addressed to broaden the applicability of self-similarity are discussed.

Sphingosine kinase1 (SphK1) is an acetyl-CoA dependent acetyltransferase which acts on cyclooxygenase2 (COX2) in neurons in a model of Alzheimer’s disease (AD). However, the mechanism underlying this activity was unexplored. Here we show that N-acetyl sphingosine (N-AS) is first generated by acetyl-CoA and sphingosine through SphK1. N-AS then acetylates serine 565 (S565) of COX2, and the N-AS-acetylated COX2 induces the production of specialized pro-resolving mediators (SPMs). In a mouse model of AD, microglia show a reduction in N-AS generation, leading to decreased acetyl-S565 COX2 and SPM production. Treatment with N-AS increases acetylated COX2 and N-AS-triggered SPMs in microglia of AD mice, leading to resolution of neuroinflammation, an increase in microglial phagocytosis, and improved memory. Taken together, these results identify a role of N-AS in the dysfunction of microglia in AD., Neuronal sphingosine kinase 1 (SphK1) acetylates COX2 which is needed for microglial phagocytosis activity, and release of pro-resolving mediators (SPMs) from neurons. Here the authors examine how SphK1-mediates COX2 acetylation, and how this leads to increased secretion of SPMs from neurons in the context of Alzheimer’s disease models.

Titanium oxide (TiO2) has received growing attention in photocatalyst is owing to its chemical stability and ecofriendly nature. Among the different phases of TiO2, pure anatase and mixed-phase TiO2 (Degussa P25) have been recognized as superior photocatalysts. Indeed, the mechanism of photocatalysis and the roles of various parameters in the process have been well documented for pure anatase TiO2 and Degussa P25. However, the pure rutile phase remains unexplored in the context of photocatalytic applications. Thus, herein, we report a one-pot method to modify the surface of pure rutile TiO2 and examine the factors that affect its photocatalytic performance. This modification was achieved by treating rutile TiO2 with H2O2 under microwave irradiation, which led to the formation of core-shell rutile TiO2 with a crystalline core and an amorphous shell bearing Ti3+ and Ti–OH species on the surface. The photocatalytic performance of this modified TiO2 species was enhanced threefold compared with that of unmodified rutile TiO2. This basic understanding of how to improve the photocatalytic performance of rutile phase TiO2 will play a crucial role in enhancing the catalytic performance of other metal oxides.

Multivariate quadratic (MQ) equations-based cryptography is one of the most promising alternatives for currently used public-key cryptographic algorithms in the post-quantum era. It is important to design practical public-key signature schemes on embedded processors and resource-constrained devices for emerging applications in Internet of Things. The MQ-signature schemes are suitable for low-cost constrained devices since they require only modest computational resources. In this paper, we propose an efficient MQ-signature scheme, SOV, using sparse polynomials with a shorter secret key and give its security analysis against known algebraic attacks. Compared to Rainbow, the secret key of SOV has reduced by a factor of 90% without increasing the public key size. In particular, SOV requires signatures of 52 bytes, while ECDSA-256 requires signatures of 64 bytes.

A nanostructured FeSn2/SnO2 composite was directly synthesized using a simple solid-state ball milling synthesis method by exploiting the disproportionation reaction of SnO and the thermodynamically stable formation of FeSn2. The as-synthesized FeSn2/SnO2 composite comprised small (∼10–20 nm) FeSn2 and SnO2 nanocrystallites, and as a lithium-ion battery anode, it exhibited better electrochemical performance than FeSn2 and SnO2. Furthermore, we prepared a C-decorated FeSn2/SnO2 (FeSn2/SnO2/C) composite. Compared to FeSn2/SnO2, FeSn2/SnO2/C contained smaller nanocrystallites of FeSn2 (∼10 nm) and SnO2 (∼5 nm), which were present in the amorphous C matrix and provided enhanced electrochemical performance. The FeSn2/SnO2/C composite had a high reversible initial capacity of 843 mAh·g−1, a stable capacity retention of above 80% after 100 cycles, and a high C-rate performance of ∼610 mAh·g−1 at 3C rate. Moreover, its electrochemical reaction mechanism during lithium insertion/extraction was determined by ex situ extended X-ray absorption fine structure analysis. Owing to their high electrochemical performance, FeSn2/SnO2/C composites are promising as a new high-performance anode material for lithium-ion batteries.

The most common screening techniques to diagnose a patient’s illness are blood collection and intravenous procedures. To find a collection or injection site, conventional blood collection support tools, such as latex tubing and buckle-type tourniquets, are generally used to compress the patient’s blood vessels. This conventional passive method has significant problems such as latex allergy, vulnerability to site contamination and potential bloodstream infection, and physical damage due to improper use. To overcome the disadvantages of conventional blood collection support tools, an automatic tourniquet with a high-elasticity biocompatible strap was constructed. The automatic tourniquet is designed to automatically adjust the strap length using a motor to control the pressure according to the body dimensions of patients. In order to evaluate the performance of the automatic tourniquet, blood flow characteristics were analyzed using an ultrasound measurement system. The results demonstrated that the automatic tourniquet showed better performance compared with those of other blood collection support tools.

Branch length similarity (BLS) entropy is defined in a network consisting of a single node and branches. In this study, we mapped the binary time-series signal to the circumference of the time circle so that the BLS entropy can be calculated for the binary time-series. We obtained the BLS entropy values for “1” signals on the time circle. The set of values are the BLS entropy profile. We selected the local maximum (minimum) point, slope, and inflection point of the entropy profile as the characteristic features of the binary time-series and investigated and explored their significance. The local maximum (minimum) point indicates the time at which the rate of change in the signal density becomes zero. The slope and inflection points correspond to the degree of change in the signal density and the time at which the signal density changes occur, respectively. Moreover, we show that the characteristic features can be widely used in binary time-series analysis by characterizing the movement trajectory of Caenorhabditis elegans. We also mention the problems that need to be explored mathematically in relation to the features and propose candidates for additional features based on the BLS entropy profile.

Antimony selenide and its carbon composite were synthesized through a mechanochemical process and investigated as anode materials for sodium-ion secondary batteries. X-ray diffraction (XRD) with rietveld refinement and transmission electron microscopy (TEM) analyses confirm that Sb2Se3 were composed of agglomerated highly crystalline nanocrystallites and the Sb2Se3/C composite consisted of nanocrystalline Sb2Se3 dispersed homogeneously throughout an amorphized carbon matrix. The initial Coulombic efficiency, rate capability, and cycle performance of the Sb2Se3/C composite were superior to those of Sb, or Sb2Se3. The Sb2Se3/C composite, in particular, showed excellent cycle stability, with 98.2% of initial capacity at 200 mA g−1 after 200 cycles. Based on the reaction potentials, ex situ XRD patterns and ex situ HR-TEM analysis of the Sb2Se3/C composite electrode revealed the structural changes which occurred reversibly within the Sb2Se3/C composite by conversion and recombination reaction during sodiation and desodiation process. Furthermore, XPS analysis study was carried out for identifying the surface films formed on both the electrodes and their effects on the performances.

A simple melt-spinning/chemical-etching process is developed to create porous carbon-free SnSb anodes. Sodium ion batteries (SIBs) incorporating these anodes exhibit excellent electrochemical performances by accomodating large volume changes during repeated cycling. The porous carbon-free SnSb anode produced by the melt-spinning/chemical-etching process shows a high reversible capacity of 481 mAh g−1, high ICE of 80%, stable cyclability with a high capacity retention of 99% after 100 cycles, and a fast rate capability of 327 mAh g−1 at 4C-rate. Ex-situ X-ray diffraction and high resolution-transmission electron microscopy analyses demonstrate that the synthesized porous carbon-free SnSb anodes involve the highly reversible reaction with sodium through the conversion and recombination reactions during sodiation/desodiation process. The novel and simple melt-spinning/chemical-etching synthetic process represents a technological breakthrough in the commercialization of Na alloy-able anodes for SIBs.

The Unbalanced Oil and Vinegar signature scheme (UOV) is one of multivariate quadratic public key cryptosystems and remains unbroken. In Inscrypt 2015, Tan and Tang proposed variants of UOV, Matrix-based UOV, to reduce the size of the secret key and generate signature faster. We show that Matrix-based UOV is entirely broken by finding equivalent keys in polynomial-time. In practice, we can forge Matrix-based UOV signature at 80 and 100 security levels in less than 0.37 seconds and 0.53 seconds, respectively.

A simple, inexpensive, and scalable method for transforming phosphorous pentoxide (P2O5) into black phosphorus (BP)-based composites was developed. The BP-based composites of BP@MgO, BP@Al2O3, and BP@TiO2 synthesized by a one-pot mechanochemical reduction of P2O5 using Mg, Al, or Ti were composed of nanocrystalline BP within the metal oxide matrices of MgO, Al2O3, or TiO2, respectively. Subsequently, the potential of these composites as anode materials in rechargeable Li-ion batteries (LIBs) was investigated. BP@TiO2 showed the highest electrochemical performance among the BP-based composites. Specifically, the BP@TiO2 exhibited a high reversible capacity over 510 mAh g−1 after 300 cycles and a fast rate capability of ~ 400 mAh g−1 at the 3C rate. The superior electrochemical performance of BP@TiO2 was attributed to the well-dispersed nanocrystalline BP and the Li-reactive TiO2 matrix. Additionally, the formation of LixTiO2 in the Li-reactive TiO2 matrix during Li cycling increased the electrochemical Li-ion conductivity and diffusivity, contributing to the enhanced electrochemical performance. Therefore, the BP@TiO2 synthesized by the one-pot mechanochemical reduction has high potential as a superior LIB anode.

Two-dimensional quantum dots (2D QDs) comprising PtS2 with low Pt loading (0.002 wt.%) distributed on a distinctive CVD-grown titanium carbide substrate (PtS2/TiC) was successfully synthesized and employed for a hydrogen evolution reaction (HER). Notably, despite the low loading of the former component, PtS2/TiC showed excellent HER activity with a superior overpotential (55 mV at 10 mA/cm−2) to that of commercial Pt/C (50 mV at 10 mA/cm−2). The Faraday efficiency of PtS2/TiC was found to be 92.5 %, revealing the superior properties of hydrogen production. The In-situ Raman spectra reveal the important role of S atoms in PtS2 as the active sites for HER, as evidenced by S H bonding formation at 2532 cm-1 during the HER process. This study provides a fundamental understanding essential for the design of more efficient catalysts in the field of electrochemical applications.

Vanadium diphosphide (VP2) and its graphite-modified composite (VP2@G) were fabricated using a fast and simple solid-state manner, and evaluated as Li-ion battery (LIB) anodes. The electrochemical Li-mechanism of VP2 was investigated using various ex situ tools. During Li-insertion, VP2 underwent a topotactic-reaction by the formation of LixVP2 (x ≤ 1.5), and then was converted to Li3P and V phases with a partially unconverted LixVP2 phase at the Li-inserted state of 0 V via a partial conversion reaction. Conversely, during Li-extraction, Li3P, V, and unconverted LixVP2 phases recombined fully into VP2. First, when VP2 was used the topotactic-reaction between LixVP2 and VP2 (potential region: 0.3–2.0 V), stable cycling performance with a high volumetric-capacity (595 mAh cm–3 after 100 cycles) and fast rate performance (~555 mAh cm–3 at 2 C and ~530 mAh cm–3 at 3 C) were attained. Additionally, the graphite-modified composite VP2@G (potential region: 0–2.0 V) also exhibited stable cycling performance with a high gravimetric-capacity (602 mAh g−1 after 100 cycles) and fast rate performance (~530 mAh g−1 at 1 C and ~470 mAh g−1 at 2 C), which was attributed to the well-dispersed nanocrystalline (~10–20 nm) VP2 in the Li-buffering graphite matrix. Therefore, the VP2 and VP2@G have high potential as a superior LIB anode.

Public-Key Cryptography (PKC) based on multivariate quadratic equations is one of the most promising alternatives for classical PKC after the eventual coming of quantum computers. Recently, Shen and Tang proposed a new MQ-signature scheme, RGB, based on three types of variables, Red( r ), Green( g ) and Blue( b ). They claimed that signing for RGB is faster than that of UOV and Rainbow. At ACISP 2016, Tang et al. implemented RGB on S5PV210 and MT6582 microprocessors at 64, 80, 96, 118 and 128-bit security levels for practical use. Their results are much more efficient than other MQ-signature schemes, so RGB is very appealing for resource-limited devices. We show that RGB with their suggested parameters at 64, 80, 96, 118 and 128 security levels are entirely broken by key recovery attacks using good keys. From a practical point of view, we are able to break their parameters at 64, 80, 96, 118 and 128 security levels in less than 0.48 seconds, 1.7 seconds, 90.68 seconds, 11 minutes and 6.82 hours, respectively. Consequently, we show that signing and the key sizes for RGB with secure parameter sets are much slower and larger than those of UOV and Rainbow.

Given a number field $L$, we define the degree of an algebraic number $v \in L$ with respect to a choice of a primitive element of $L$. We propose the question of computing the minimal degrees of algebraic numbers in $L$, and examine these values in degree $4$ Galois extensions over $\mathbb{Q}$ and triquadratic number fields. We show that computing minimal degrees of non-rational elements in triquadratic number fields is closely related to solving classical Diophantine problems such as congruent number problem as well as understanding various arithmetic properties of elliptic curves., Comment: Accepted to International Journal of Number Theory

Carbon black (CB) is an inexpensive and widely used carbonaceous material. However, the reversibility between CB and Li or Na is very poor, and the initial coulombic efficiency (ICE) is so low that it cannot be used as an electrode material for rechargeable batteries. In this study, we successfully designed superior CB as a high-performance conducting additive for Li-ion batteries (LIBs) and Na-ion batteries (NIBs) using a simple two-step strategy: amorphization and pre-lithiation/sodiation. The Li- and Na-reversible capacities of amorphized CB increased significantly from 213 to 564 mAh g−1 for LIB and from 92 to 209 mAh g−1 for NIB; however, the corresponding ICEs of 61.5% for LIB and 33.5% for NIB are poor. The poor ICEs are supplemented via pre-lithiation/sodiation in the amorphized CB, which show over 100% ICEs with high Li- and Na-reversible capacities. Specifically, the modified CB has highly reversible capacities (>500 mAh g−1 for LIB, >300 mAh g−1 for NIB) with exceptionally high ICEs (133% ICE for LIB, 160% ICE for NIB), stable reversible capacities for over 100 cycles (470 mAh g−1 for LIB, 278 mAh g−1 for NIB), fast rate capabilities with highly reversible capacities at a 3C rate (~330 mAh g−1 for LIB, ~190 mAh g−1 for NIB), and excellent cycling behavior for over 300 cycles at a 1C rate. When used as a conducting additive, this CB contributes to high electrical conductivity and increase of ICE and the reversible capacity for LIB and NIB anode materials. These results are expected to have a significant impact on LIBs and NIBs.

To achieve high-performance Sb-based anodes for Na-ion battery (NIB), various approaches for obtaining amorphous C-containing Sb composite (Sb@C), Sb-based intermetallic compounds (TiSb2 and NbSb2), and Na-inactive metal carbide and amorphous C-containing Sb composites (Sb@TiC@C and Sb@NbC@C) have been introduced. First, Sb@C was prepared using a simple solid-state ball-milling, and then its potential as a NIB anode material was investigated. The electrochemical phase change mechanism of Sb during the sodiation/desodiation of Sb@C was investigated using various ex situ analytical techniques. Sb was found to sequentially transform into NaSb and Na3Sb during sodiation and NaSb and Sb during desodiation. Second, as another trial to further improve the electrochemical performance of Sb, Sb-based intermetallic compounds of TiSb2 and NbSb2 were synthesized by alloying reaction via a simple solid state heat-treatment and their potential as NIB anode materials was investigated. Lastly, the Sb@TiC@C and Sb@NbC@C nanocomposites comprising tiny (~3–5 nm) Sb nanocrystallites and Na-inactive metal carbide (TiC/NbC) matrix embedded in buffering amorphous C were synthesized by alloying and dealloying reaction. The Sb@TiC@C and Sb@NbC@C demonstrated highly reversible, stable capacity (Sb@TiC@C: 746 mAh cm−3, Sb/NbC/C: 726 mAh cm−3 after 100 cycles) and fast rate capability with exceptional capacity retentions after 400 cycles (Sb@TiC@C: ~710 mAh cm−3 at 2 C rate, Sb@NbC@C: ~680 mAh cm−3 at 2 C rate). Therefore, the Sb-based nanocomposites synthesized by alloying and dealloying are considered to be possible new anode materials for use in high-performance NIBs.

A simple synthetic method for the mechanochemically induced transformation of cobalt oxyhydroxides (CoO(OH)) into cobalt oxide (Co3O4) nanoparticles is developed. Using this method, extremely small and well-dispersed Co3O4 (3–5 nm) nanoparticles are synthesized and their use as a high-performance anode for Li-ion batteries is evaluated. The Co3O4 nanoparticle electrode shows excellent electrochemical performances such as a highly reversible capacity of 1023 mA h g−1 with excellent cycling behavior over 100 cycles and a superior rate capability of 760 mA h g−1 at an extremely fast current rate of 3C. This simple mechanochemically induced transformation method for extremely small and well-dispersed cobalt oxide nanoparticles is highly applicable to the preparation of other metal oxide nanoparticles for obtaining highly reversible Li storage characteristics.

The electrochemical reaction mechanism of ZnO is investigated to understand its Li insertion/extraction behavior using ex situ X-ray diffraction, extended X-ray absorption fine structure, and high-resolution transmission electron microscopy. Based on these analyses, an interesting partial recombination reaction of ZnO is discovered, which demonstrates that Li2O formed during Li insertion is partially reversible. Additionally, we discover that the control of the partial recombination reaction of the metal oxide is very important for improving reversibility in the first cycle, which is a key finding for realization of highly reversible oxide-based electrode materials. In addition, to enhance the electrochemical performance of the ZnO electrode, a nanostructured ZnO/C composite is prepared by a simple high-energy mechanical milling process. This process allows the electrochemical performance of the ZnO electrode to be evaluated as an anode for rechargeable Li-ion batteries. Electrochemical tests show that the nanocomposite electrode exhibits a high initial charge capacity of 682 mAh g−1, fast rate capability of 371 mAh g−1 at 2 C, and excellent cyclability over 200 cycles.

Energy cost of transmitting a single bit of information is approximately the same as that needed for processing a thousand operations in a typical sensor node. Thus, a practical way to prolong a wireless sensor network lifetime is to reduce the sensor energy consumption in data transmissions. Data aggregation is an efficient way to minimize energy consumption on sensors. In this paper, we propose a practical secure data aggregation scheme, Sen-SDA , based on an additive homomorphic encryption scheme, an identity-based signature scheme, and a batch verification technique with an algorithm for filtering injected false data. We then investigate the feasibility of our scheme using low-cost microcontrollers choosing two popular IEEE 802.15.4-compliant wireless sensor network hardware platforms, MICAz and Tmote Sky, used in real-life deployments.