Epitaxial Growth of Branched α‐Fe2O3/SnO2 Nano‐Heterostructures with Improved Lithium‐Ion Battery Performance

We report the synthesis of a novel branched nano‐heterostructure composed of SnO₂ nanowire stem and α‐Fe₂O₃ nanorod branches by combining a vapour transport deposition and a facile hydrothermal method. The epitaxial relationship between the branch and stem is investigated by high resolution transmission electron microscopy (HRTEM). The SnO₂ nanowire is determined to grow along the [101] direction, enclosed by four side surfaces. The results indicate that distinct crystallographic planes of SnO₂ stem can induce different preferential growth directions of secondary nanorod branches, leading to six‐fold symmetry rather than four‐fold symmetry. Moreover, as a proof‐of‐concept demonstration of the function, such α‐Fe₂O₃/SnO₂ composite material is used as a lithium‐ion batteries (LIBs) anode material. Low initial irreversible loss and high reversible capacity are demonstrated, in comparison to both single components. The synergetic effect exerted by SnO₂ and α‐Fe₂O₃ as well as the unique branched structure are probably responsible for the enhanced performance.     

Non‐Lithographic Fabrication of All‐2D α‐MoTe2 Dual Gate Transistors

As one of the emerging new transition‐metal dichalcogenides materials, molybdenum ditelluride (α‐MoTe₂) is attracting much attention due to its optical and electrical properties. This study fabricates all‐2D MoTe₂‐based field effect transistors (FETs) on glass, using thin hexagonal boron nitride and thin graphene in consideration of good dielectric/channel interface and source/drain contacts, respectively. Distinguished from previous works, in this study, all 2D FETs with α‐MoTe₂ nanoflakes are dual‐gated for driving higher current. Moreover, for the present 2D dual gate FET fabrications on glass, all thermal annealing and lithography processes are intentionally exempted for fully non‐lithographic method using only van der Waal's forces. The dual‐gate MoTe₂ FET displays quite a high hole and electron mobility over ≈20 cm² V^?1 s^?1 along with ON/OFF ratio of ≈10⁵ in maximum as an ambipolar FET and also demonstrates high drain current of a few tens‐to‐hundred μA at a low operation voltage. It appears promising enough to drive organic light emitting diode pixels and NOR logic functions on glass.     

Self‐Assembling Nanotubes Consisting of Rigid Cyclic γ‐Peptides

Self‐assembling cyclic peptide nanotubes (SPNs) have been extensively studied due to their potential applications in biology and material sciences. Cyclic γ‐peptides, which have a larger conformational space, have received less attention than the cyclic α‐ and β‐peptides. The self‐assembly of cyclic homo‐γ‐tetrapeptide based on cis‐3‐aminocyclohexanecarboxylic acid (γ‐Ach) residues, which can be easily synthesized by a one‐pot process is investigated. Fourier transform infrared (FTIR) and NMR analysis along with density functional theory (DFT) calculations indicate that the cyclic homo‐γ‐tetrapeptide, with a non‐planar conformation, can self‐assemble into nanotubes through hydrogen‐bond‐mediated parallel stacking. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) experiments reveal the formation of bundles of nanotubes in CH₂Cl₂/hexane, but individual nanotubes and bundles of only two nanotubes are obtained in water. The integration of TEG (triethylene glycol) monomethyl ether chains and cyclopeptide backbones may allow the control of width of single nanotubes.     

Silica Nanodepletors: Targeting and Clearing Alzheimer's β‐Amyloid Plaques

Abnormal accumulation of β‐amyloid (Aβ) peptide aggregates in the brain is a major hallmark of Alzheimer's disease (AD). Aβ aggregates interfere with neuronal communications, ultimately causing neuronal damage and brain atrophy. Much effort has been made to develop AD treatments that suppress Aβ aggregate formation, thereby attenuating Aβ‐induced neurotoxicity. Here, the design of Aβ nanodepletors consisting of ultralarge mesoporous silica nanostructures and anti‐Aβ single‐chain variable fragments, with the goal of targeting and eliminating aggregative Aβ monomers, is reported. The Aβ nanodepletors impart a notable decline in Aβ aggregate formation, resulting in significant mitigation of Aβ‐induced neurotoxicity in vitro. Furthermore, stereotaxic injections of Aβ nanodepletors into the brain of an AD mouse model system successfully suppress Aβ plaque formation in vivo up to ≈30%, suggesting that Aβ nanodepletors can serve as a promising antiamylodoisis material.     

Short Synthetic β‐Sheet Forming Peptide Amphiphiles as Broad Spectrum Antimicrobials with Antibiofilm and Endotoxin Neutralizing Capabilities

Although naturally occurring membrane lytic antimicrobial peptides (AMPs) and their analogs hold enormous promise for antibiotics‐resistant infectious disease therapies, significant challenges such as systemic toxicities, long peptide sequences, poor understanding of structure‐activity relationships, and the potential for compromising innate host defense immunity have greatly limited their clinical applicability. To improve the clinical potential of AMPs, a facile approach is adopted to design a series of short synthetic β‐sheet folding peptide amphiphiles comprised of short recurring (X₁Y₁X₂Y₂)_n‐NH₂ sequences, where X₁ and X₂: hydrophobic residues (Val, Ile, Phe or Trp), Y₁ and Y₂: cationic residues (Arg or Lys), and n: number of repeat units; with systematic variations to the cationic and hydrophobic residues to obtain optimized AMP sequences bearing minimal resemblance to naturally occurring sequences. The designed β‐sheet forming peptides exhibit broad spectrum antimicrobial activities against various clinically relevant microorganisms, including Gram‐positive Staphylococcus epidermidis and Staphylococcus aureus, Gram‐negative Escherichia coli and Pseudomonas aeruginosa, and yeast Candida albicans, with excellent selectivities for microbial membranes. Optimal synthetic peptides with n = 2 and n = 3 repeat units, i.e., (IRIK)₂‐NH₂ and (IRVK)₃‐NH₂, efficiently inhibit sessile biofilm bacteria growth leading to biomass reduction. Additionally, sequences with n = 3 repeat units effectively neutralize endotoxins while causing minimal cytotoxicities. Taken together, these findings clearly demonstrate that the rationally designed synthetic β‐sheet folding peptides are highly selective, non‐cytotoxic at antimicrobial levels and have tremendous potential for use as broad spectrum antimicrobial agents to overcome multidrug resistance in a wide range of localized, systemic, or external therapeutic applications.     

Carbonyl‐β‐Cyclodextrin as a Novel Binder for Sulfur Composite Cathodes in Rechargeable Lithium Batteries

As one of the essential components in electrodes, the binder affects the performance of a rechargeable battery. By modifying β‐cyclodextrin (β‐CD), an appropriate binder for sulfur composite cathodes is identified. Through a partial oxidation reaction in H₂O₂ solution, β‐CD is successfully modified to carbonyl‐β‐cyclodextrin (C‐β‐CD), which exhibits a water solubility ca. 100 times that of β‐CD at room temperature. C‐β‐CD possesses the typical properties of an aqueous binder: strong bonding strength, high solubility in water, moderate viscosity, and wide electrochemical windows. Sulfur composite cathodes with C‐β‐CD as the binder demonstrate a high reversible capacity of 694.2 mA h g_(composite)^?1 and 1542.7 mA h g_(sulfur)^?1, with a sulfur utilization approaching 92.2%. The discharge capacity remains at 1456 mA h g_(sulfur)^?1 after 50 cycles, which is much higher than that of the cathode with unmodified β‐CD as binder. Combined with its low cost and environmental benignity, C‐β‐CD is a promising binder for sulfur cathodes in rechargeable lithium batteries with high electrochemical performance.     

Robust Non‐negative Matrix Factorization with β‐Divergence for Speech Separation

This paper addresses the problem of unsupervised speech separation based on robust non‐negative matrix factorization (RNMF) with β‐divergence, when neither speech nor noise training data is available beforehand. We propose a robust version of non‐negative matrix factorization, inspired by the recently developed sparse and low‐rank decomposition, in which the data matrix is decomposed into the sum of a low‐rank matrix and a sparse matrix. Efficient multiplicative update rules to minimize the β‐divergence‐based cost function are derived. A convolutional extension of the proposed algorithm is also proposed, which considers the time dependency of the non‐negative noise bases. Experimental speech separation results show that the proposed convolutional RNMF successfully separates the repeating time‐varying spectral structures from the magnitude spectrum of the mixture, and does so without any prior training.     

Outage probability bound of decode and forward two‐way full‐duplex relay employing spatial modulation over cascaded α − μ channels

The system performance of mobile‐to‐mobile (D2D) cooperative communication has been improved by utilizing spatial modulation (SM) in this paper. The proposed system employs decode and forward (DF) relaying technique along with physical layer network coding (PLNC); hence, it has been named as SM‐based decode and forward two‐way relay (DFTWR). It enables full‐duplex communication thereby enhancing the system efficiency. Information bits are exchanged between the two bidirectional nodes. For two bits of information exchange, the antenna index is conveyed by the least significant bit (LSB) of the data symbol while the most significant bit (MSB) carries the message. The system performance has been investigated by analyzing certain performance metrics like lower and upper bounds of outage probability and average data rate for N‐α‐μ cascaded fading channels. The change in the system performance by varying certain parameters like relative geometrical gain, fading coefficients, and number of cascaded components has also been put forth in this paper.     

“Naked” Magnetically Recyclable Mesoporous Au–γ‐Fe2O3 Nanocrystal Clusters: A Highly Integrated Catalyst System

Naked magnetically recyclable mesoporous Au–γ‐Fe₂O₃ clusters, combining the inherent magnetic properties of γ‐Fe₂O₃ and the high catalytic activity of Au nanoparticles (NPs), are successfully synthesized. Hydrophobic Au–Fe₃O₄ dimers are first self‐assembled to form sub‐micrometer‐sized Au–Fe₃O₄ clusters. The Au–Fe₃O₄ clusters are then coated with silica, calcined at 550 °C, and finally alkali treated to dissolve the silica shell, yielding naked‐Au–γ‐Fe₂O₃ clusters containing Au NPs of size 5–8 nm. The silica protection strategy serves to preserve the mesoporous structure of the clusters, inhibit the phase transformation from γ‐Fe₂O₃ to α‐Fe₂O₃, and prevent cluster aggregation during the synthesis. For the reduction of p‐nitrophenol by NaBH₄, the activity of the naked‐Au–γ‐Fe₂O₃ clusters is ≈22 times higher than that of self‐assembled Au–Fe₃O₄ clusters. Moreover, the naked‐Au–γ‐Fe₂O₃ clusters display vastly superior activity for CO oxidation compared with carbon‐supported Au–γ‐Fe₂O₃ dimers, due to the intimate interfacial contact between Au and γ‐Fe₂O₃ in the clusters. Following reaction, the naked‐Au–γ‐Fe₂O₃ clusters can easily be recovered magnetically and reused in different applications, adding to their versatility. Results suggest that naked‐Au–γ‐Fe₂O₃ clusters are a very promising catalytic platform affording high activity. The strategy developed here can easily be adapted to other metal NP–iron oxide systems.     

Music/Voice Separation Based on Kernel Back‐Fitting Using Weighted β‐Order MMSE Estimation

Recent developments in the field of separation of mixed signals into music/voice components have attracted the attention of many researchers. Recently, iterative kernel back‐fitting, also known as kernel additive modeling, was proposed to achieve good results for music/voice separation. To obtain minimum mean square error (MMSE) estimates of short‐time Fourier transforms of sources, generalized spatial Wiener filtering (GW) is typically used. In this paper, we propose an advanced music/voice separation method that utilizes a generalized weighted β‐order MMSE estimation (WbE) based on iterative kernel back‐fitting (KBF). In the proposed method, WbE is used for the step of mixed music signal separation, while KBF permits kernel spectrogram model fitting at each iteration. Experimental results show that the proposed method achieves better separation performance than GW and existing Bayesian estimators.     

Improved Thermoelectric Performance of Eco‐Friendly β‐FeSi2–SiGe Nanocomposite via Synergistic Hierarchical Structuring,Phase Percolation,and Selective Doping

A β‐FeSi₂–SiGe nanocomposite is synthesized via a react/transform spark plasma sintering technique, in which eutectoid phase transformation, Ge alloying, selective doping, and sintering are completed in a single process, resulting in a greatly reduced process time and thermal budget. Hierarchical structuring of the SiGe secondary phase to achieve coexistence of a percolated network with isolated nanoscale inclusions effectively decouples the thermal and electrical transport. Combined with selective doping that reduces conduction band offsets, the percolation strategy produces overall electron mobilities 30 times higher than those of similar materials produced using typical powder‐processing routes. As a result, a maximum thermoelectric figure of merit ZT of ≈0.7 at 700 °C is achieved in the β‐FeSi₂–SiGe nanocomposite.     

Triphenylphosphonium‐Conjugated Poly(ε‐caprolactone)‐Based Self‐Assembled Nanostructures as Nanosized Drugs and Drug Delivery Carriers for Mitochondria‐Targeting Synergistic Anticancer Drug Delivery

For mitochondria‐targeting delivery, a coupling reaction between poly(ε‐caprolactone) diol (PCL diol) and 4‐carboxybutyltriphenylphosphonium (4‐carboxybutyl TPP) results in the synthesis of amphiphilic TPP‐PCL‐TPP (TPCL) polymers with a bola‐like structure. In aqueous environments, the TPCL polymer self‐assembled via cosolvent dispersion and film hydration, resulting in the formation of cationic nanoparticles (NPs) less than 50 nm in size with zeta‐potentials of approximately 40 mV. Interestingly, different preparation methods for TPCL NPs result in various morphologies such as nanovesicles, nanofibers, and nanosheets. In vitro cytotoxicity results with TPCL NPs indicate IC₅₀ values of approximately 10–60 μg mL^?1, suggesting their potential as anticancer nanodrugs. TPCL NPs can be loaded both with hydrophobic doxorubicin (Dox) and its hydrophilic salt form (Dox·HCl), and their drug loading contents are approximately 2–10 wt% depending on the loading method and the hydrophilicity/hydrophobicity of the drugs. Although Dox·HCl exhibits more cellular and nuclear uptake, resulting in greater antitumor effects than Dox, most drug‐loaded TPCL NPs exhibit higher mitochondrial uptake and approximately 2–7‐fold higher mitochondria‐to‐nucleus preference than free drugs, resulting in superior (approximately 7.5–18‐fold) tumor‐killing activity for most drug‐loaded TPCL NPs compared with free drugs. In conclusion, TPCL‐based nanoparticles have potential both as antitumor nanodrugs themselves and as nanocarriers for chemical therapeutics.     

Novel Composites of α‐Fe2O3 Tetrakaidecahedron and Graphene Oxide as an Effective Photoelectrode with Enhanced Photocurrent Performances

Novel composites composed of α‐Fe₂O₃ tetrakaidecahedrons and graphene oxide have been easily fabricated and demonstrated to be efficient photoelectrodes for photoelectrochemical water splitting reaction with superior photocurrent response. α‐Fe₂O₃ tetrakaidecahedrons are facilely synthesized in a green manner without any organic additives and then modified with graphene oxide. The morphological and structural properties of α‐Fe₂O₃/graphene composite are intensively investigated by several means, such as X‐ray diffraction, field‐emission scanning electron microscope, transmission electron microscope, X‐ray photoelectron spectroscopy, Fourier Transform infrared spectroscopy, and Raman spectroscopy. The tetrakaidecahedronal hematite particles have been indicated to be successfully coupled with graphene oxide. Systematical photoelectrochemical and impedance spectroscopy measurements have been carried out to investigate the favorable performance of α‐Fe₂O₃/graphene composites, which are found to be effective photoanodes with rapid, steady, and reproducible feature. The coupling of graphene with α‐Fe₂O₃ particles has greatly enhanced the photoelectrochemical performance, resulting in higher photocurrent and lower onset potential than that of pure α‐Fe₂O₃. This investigation has provided a feasible method to synthesize α‐Fe₂O₃ tetrakaidecahedron and fabricate an efficient α‐Fe₂O₃/graphene photoelectrode for photoelectrochemical water oxidation, suggesting a promising route to design noble metal free semiconductor/graphene photocatalysts.     

Well‐Defined Functional Linear Aliphatic Diblock Copolyethers: A Versatile Linear Aliphatic Polyether Platform for Selective Functionalizations and Various Nanostructures

Low‐temperature anionic ring‐opening homopolymerizations and copolymerizations of two glycidol derivatives (allyl glycidyl ether (AGE) and ethoxyethyl glycidyl ether (EEGE)) are studied using a metal‐free catalyst system, 3‐phenyl‐1‐propanol (PPA) (an initiator) and 1‐tert‐butyl‐4,4,4‐tris(dimethylamino)‐2,2‐bis[tris‐(dimethylamino)phosphoranylidenamino]‐2Λ⁵,4Λ⁵‐catenadi(phosphazene) (t‐Bu‐P₄) (a promoter) in order to obtain well‐defined functional linear polyethers and diblock copolymers. With the aid of the catalyst system, AGE is found to successfully undergo anionic ring‐opening polymerization (ROP) even at room temperature (low reaction temperature) without any side reactions, producing well‐defined linear AGE‐homopolymer in a unimodal narrow molecular weight distribution. Under the same conditions, EEGE also undergoes polymerization, producing a linear EEGE‐homopolymer in a unimodal narrow molecular‐weight distribution. In this case, however, a side reaction (i.e., chain‐transfer reaction) is found to occur at low levels during the early stages of polymerization. The chemical properties of the monomers in the context of the homopolymerization reactions are considered in the design of a protocol used to synthesize well‐defined linear diblock copolyethers with a variety of compositions. The approach, anionic polymerization via the sequential step feed of AGE and EEGE as the first and second monomers, is found to be free from side reactions at room temperature. Each block of the obtained linear diblock copolymers undergoes selective deprotection to permit further chemical modification for selective functionalization. In addition, thermal properties and structures of the polymers and their post‐modification products are examined. Overall, this study demonstrates that a low‐temperature metal‐free anionic ROP using the PPA/t‐Bu‐P₄ catalyst system is suitable for the production of well‐defined linear AGE‐homopolymers and their diblock copolymers with the EEGE monomer, which are versatile and selectively functionalizable linear aliphatic polyether platforms for a variety of post‐modifications, nanostructures, and their applications.     

Short‐Chain Ligand‐Passivated Stable α‐CsPbI3 Quantum Dot for All‐Inorganic Perovskite Solar Cells

Cubic phase CsPbI₃ (α‐CsPbI₃) perovskite quantum dots (QDs) have received extensive attention due to their all‐inorganic composition and suitable band gap (1.73 eV). However, α‐CsPbI₃ QDs might convert to δ‐CsPbI₃ (orthorhombic phase with indirect band gap of 2.82 eV) due to easy loss of surface ligands. In addition, commonly used long‐chain ligands (oleic acid, OA, and oleylamine, OLA) hinder efficient charge transport in optoelectronic devices. In order to relieve these drawbacks, OA, OLA, octanoic acid, and octylamine are used as capping ligands for synthesizing high‐quality α‐CsPbI₃ QDs. The results indicate that these QDs exhibit excellent optical properties and long‐term stability compared to QDs capped only with OA and OLA. Moreover, QDs with shorter ligands exhibit an enhanced charge transport rate, which improves the power conversion efficiency of photovoltaic devices from 7.76% to 11.87%.     

Bit error probability of the M‐QAM scheme under η‐μ fading and impulsive noise in a communication system using spatial diversity

This paper presents a new and exact expression for the bit error probability (BEP) of the square M‐ary quadrature amplitude modulation (M‐QAM) scheme, with the channel under double gated additive white Gaussian noise (G²AWGN) and η‐μ fading in a communication system using the spatial diversity technique. The expression for the BEP is written in terms of the Appell function. The BEP curves are presented under different values of the number of branches of the maximum ratio combining (MRC) receiver, order of the constellation M, and parameters that characterize mathematically the channel, corroborated by simulations performed with Monte Carlo method.     

Fabrication of Chitosan‐18β‐Glycyrrhetinic Acid Modified Titanium Implants with Nanorod Arrays for Suppression of Osteosarcoma Growth and Improvement of Osteoblasts Activity

Surgery has been combined with chemotherapy to treat osteosarcoma. However, the recovery rate of osteosarcoma patients is still low. To prevent post‐operative recurrence of the osteosarcoma, developing an alternative biomaterial is essential. 18β‐Glycyrrhetinic acid (GA) has shown potential anticancer activity in various malignancies. Here it is proposed that GA can induce osteosarcoma cell apoptosis, and a polydopamine‐mediated titanium oxide nanorod (TiO₂NR) surface is functionalized by covalently grafting the chitosan‐18β‐glycyrrhetinic acid conjugate (CS–GA). In vitro and in vivo biological tests indicate that the CS–GA modified surface shows significant antiproliferation and apoptosis in osteosarcoma cells (MG63). Additionally, this modified surface with nanoarray structure stimulation and chitosan supplementation significantly promotes osteoblast (MC3T3‐E1) adhesion and proliferation in vitro. This dual‐functional, Ti‐based implant with balanced antitumor and biocompatibility properties represents an effective strategy for the surgical treatment of osteosarcoma.     

Hierarchical Engineering of Porous P2‐Na2/3Ni1/3Mn2/3O2 Nanofibers Assembled by Nanoparticles Enables Superior Sodium‐Ion Storage Cathodes

Layered transition metal oxides (TMOs) are appealing cathode candidates for sodium‐ion batteries (SIBs) by virtue of their facile 2D Na⁺ diffusion paths and high theoretical capacities but suffer from poor cycling stability. Herein, taking P2‐type Na_2/3Ni_1/3Mn_2/3O₂ as an example, it is demonstrated that the hierarchical engineering of porous nanofibers assembled by nanoparticles can effectively boost the reaction kinetics and stabilize the structure. The P2‐Na_2/3Ni_1/3Mn_2/3O₂ nanofibers exhibit exceptional rate capability (166.7 mA h g^?1 at 0.1 C with 73.4 mA h g^?1 at 20 C) and significantly improved cycle life (≈81% capacity retention after 500 cycles) as cathode materials for SIBs. The highly reversible structure evolution and Ni/Mn valence change during sodium insertion/extraction are verified by in operando X‐ray diffraction and ex situ X‐ray photoelectron spectroscopy, respectively. The facilitated electrode process kinetics are demonstrated by an additional study using the electrochemical measurements and density functional theory computations. More impressively, the prototype Na‐ion full battery built with a Na_2/3Ni_1/3Mn_2/3O₂ nanofibers cathode and hard carbon anode delivers a promising energy density of 212.5 Wh kg^?1. The concept of designing a fibrous framework composed of small nanograins offers a new and generally applicable strategy for enhancing the Na‐storage performance of layered TMO cathode materials.