Artificial Magnetic Bacteria: Living Magnets at Room Temperature

Biogenic magnetite is a fascinating example of how nature can generate functional magnetic nanostructures. Inspired by the magnetic bacteria, an attempt is made to mimic their magnetic properties, rather than their structures, to create living magnets at room temperature. The non‐magnetic probiotic bacteria Lactobacillus fermentum and Bifidobacteria breve are used as bioplatforms to densely arrange superparamagnetic nanoparticles on their external surfaces, thus obtaining the artificial magnetic bacteria. Magnetic probiotic bacteria can be produced by using superparamagnetic maghemite nanoparticles assembled at their surfaces. They present a collective ferromagnetic phase at room temperature. The blocking temperature of these maghemite nanoparticles increases more than 100 K when assembled at the artificial magnetic bacteria.     

Combining Data Longevity with High Storage Capacity—Layer‐by‐Layer DNA Encapsulated in Magnetic Nanoparticles

In this paper the practical density of long‐term DNA storage is increased. Specifically, the DNA weight loading of silica sphere DNA storage is increased to 3.4 wt%, a ten‐fold increase compared to the previous state‐of‐the‐art. By applying a Layer‐by‐Layer (LbL) design with alternating layers of DNA and a polycationic molecule, namely polyethyleneimine (PEI), another dimension to DNA surface binding onto magnetic nanoparticles is added. A protective silica layer is grown on top of the multilayered nanoparticles to shield the DNA from external sources of damage. Accelerated aging experiments of the nanoparticles and the subsequent quantification of DNA stability via qPCR show a significantly lower degradation rate compared to unprotected DNA. The novel material is compared to previous DNA storage technologies, outperforming those in DNA storage density as well as stability. Finally, the storage of an 83 kB digital file in DNA through a successful readout of a 4991 oligonucleotide pool is demonstrated from particle encapsulation, through accelerated aging, to sequencing.     

未来数据储存技术与硬盘的发展

走过了半个世纪的磁储存技术,小型化牵动着数据储存和计算机硬盘到达了从未有过的高度。正在研究发展的热辅助记录技术和图形媒介技术将会给磁记录硬盘带来更高的面密度,从而使小型化在磁储存的框架内还将有一段路可走。但由于其物理限制,磁硬盘无法永远继续小下去,人们正在寻找新的出路。因此除了对磁储存正在发展的两项新技术之外,特别是对完全另辟新路的非磁数据储存技术,如纳米机械AFM数据储存技术、全息光储存技术以及原子储存技术进行了论述,以显示当前该领域前沿科技的发展概貌。     

Multianchored Glycoconjugate‐Functionalized Magnetic Nanoparticles: A Tool for Selective Killing of Targeted Bacteria via Alternating Magnetic Fields

New technologies that do not rely on antibiotics are urgently needed to treat bacterial infections caused by multidrug‐resistant bacteria. Herein, the feasibility of using alternating magnetic field (AMF) to selectively kill enterotoxigenic Escherichia coli strain K99 (EC K99) in the presence of multianchored glycoconjugate‐functionalized magnetic nanoparticles is explored. Poly(ethylene oxide)‐poly(acrylic acid)‐dopamine functionalized magnetic nanoparticles (PEO‐MNPs) are synthesized and functionalized with bacteria‐specific glycoconjugate Neu5Ac(α2‐3)‐Gal‐(β1‐4)Glcβ‐sp (GM3‐MNPs) for specific adherence to EC K99. When such mixtures are exposed to an alternate magnetic field (31 kA m^?1, 207 KHz), an ≈3‐log reduction in colony forming units of EC K99 is achieved in 120 min. Moreover, in a mixed‐bacterial culture environment, targeted killing of EC K99 is achieved with minimal damage to nontargeted bacterium. Electron microscopy images along with live/dead staining assays demonstrate visible membrane damage of EC K99 cells in the presence of GM3‐MNPs and AMF. Additionally, intracellular adenosine triphosphate (ATP) levels of EC K99 are significantly diminished in the presence of GM3‐MNPs and AMF. These results suggest that specific glycoconjugate‐functionalized magnetic nanoparticles when mediated by AMF can be potentially used as a novel nonantibiotic treatment platform to inactivate/kill targeted bacterial pathogens, with minimal impact on normal microflora and the affected body region/tissue.     

无线传感器网络中数据存储与访问研究进展

 无线传感器网络集感知、计算和无线通信为一体,是以数据为中心的网络,因此数据存储与访问是无线传感器网络研究中的重要问题.本文围绕无线传感器网络以数据为中心这一条主线,对其中数据存储与访问的国内外研究进展进行了综述.首先概述了无线传感器网络中的数据存储与访问的概念与技术;然后详细探讨了各种数据存储策略,重点分析了分布式数据存储和信息中介;其次详细介绍了查询的分类、查询处理模型以及优化策略;最后对无线传感器网络中数据存储与访问技术进行了展望.     

When Nanoparticles Meet Poly(Ionic Liquid)s: Chemoresistive CO2 Sensing at Room Temperature

Tetraalkylammonium‐based poly(ionic liquid)s (PILs) are able to absorb particularly large amounts of CO₂; thus are considered up‐and‐coming materials in applications ranging from sensing, separation, to storage of CO₂. To meet the requirements of practical usage, their chemical activity has to be combined with other functionalities, for example, by fabricating composite materials. Poly[(p‐vinylbenzyl)trimethylammonium hexafluorophosphate] and La₂O₂CO₃ nanoparticles—both of which are intrinsically insulating materials—are utilized as building blocks, taking full advantage of the electrostatic interaction at their interface to boost the overall conductivity of composites at room temperature. To rationalize this unique behavior, the charge transport mechanism is studied using impedance spectroscopy. It is found find that, for the composites with La₂O₂CO₃ content of 60–80 wt%, the interfacial effect becomes dominant and leads to the formation of conduction channels with increased mobility of [PF₆]^? anions. These composites show further increase of the conductivity when exposed to pulses of CO₂ between 150 and 2400 ppm at room temperature in a relative humidity of 50%. This work therefore provides a simple strategy to achieve an enhancement of the electrical properties required for the utilization of PILs‐based CO₂ sensors, but in the future this concept can be easily extended to other electronic devices.     

Quantitative Recovery of Magnetic Nanoparticles from Flowing Blood: Trace Analysis and the Role of Magnetization

Magnetic nanomaterials find increasing application as separation agents to rapidly isolate target compounds from complex biological media (i.e., blood purification). The responsiveness of the used materials to external magnetic fields (i.e., their saturation magnetization) is one of the most critical parameters for a fast and thorough separation. In the present study, magnetite (Fe₃O₄) and non‐oxidic cementite (Fe₃C) based carbon‐coated nanomagnets are characterized in detail and compared regarding their separation behavior from human whole blood. A quantification approach for iron‐based nanomaterials in biological samples with strong matrix effects (here, salts in blood) based on platinum spiking is shown. Both materials are functionalized with polyethyleneglycol (PEG) to improve cytocompatibility (confirmed by cell toxicity tests) and dispersability. The separation performance is tested in two setups, namely under stationary and different flow‐conditions using fresh human blood. The results reveal a superior separation behavior of the cementite based nanomagnets and strongly suggest the use of nanomaterials with high saturation magnetizations for magnetic retention under common blood flow conditions such as in veins.     

Facile Generation of L10‐FePt Nanodot Arrays from a Nanopatterned Metallopolymer Blend of Iron and Platinum Homopolymers

Hard ferromagnetic (L1₀ phase) FePt alloy nanoparticles (NPs) with extremely high magnetocrystalline anisotropy are considered to be one of the most promising candidates for the next generation of ultrahigh‐density data storage system. The question of how to generate ordered patterns of L1₀‐FePt NPs and how to transform the technology for practical applications represents a key current challenge. Here the direct synthesis of L1₀ phase FePt NPs by pyrolysis of Fe‐containing and Pt‐containing metallopolymer blend without post‐annealing treatment is reported. Rapid single‐step fabrication of large‐area nanodot arrays (periodicity of 500 nm) of L1₀‐ordered FePt NPs can also be achieved by employing the metallopolymer blend, which possesses excellent solubility in most organic solvents and good solution processability, as the precursor through nanoimprint lithography (NIL). Magnetic force microscopy (MFM) imaging of the nanodot pattern indicates that the patterned L1₀ phase FePt NPs are capable of exhibiting decent magnetic response, which suggests a great potential to be utilized directly in the fabrication of bit patterned media (BPM) for the next generation of magnetic recording technology.     

NEAX61E交换机局数据可用内存的扩充

描述了ＮＥＡＸ６１Ｅ程控交换机内存储器的管理、扩充方法和注意事项。通过举例说明了扩充内存的具体步骤。     

Spray‐Coating Magnetic Thin Hybrid Films of PS‐b‐PNIPAM and Magnetite Nanoparticles

Spray coating is employed to fabricate magnetic thin films composed of the diblock copolymer polystyrene‐block‐poly(N‐isopropylacrylamide) and Fe₃O₄ magnetic nanoparticles (MNPs) functionalized with hydrophobic coatings. The kinetics of structure formation of the hybrid films is followed in situ with grazing incidence small angle X‐ray scattering during the spray deposition. To gain a better understanding of the influence of MNPs on the overall structure formation, the pure polymer film is also deposited as a reference via an identical spray protocol. At the initial spraying stage, the hybrid film (containing 2 wt% of MNPs) exhibits a faster formation process of a complete film as compared to the reference. The existence of MNPs depresses the dewetting behavior of polymer films on the substrate at macroscale and simultaneously alters the polymer microphase separation structure orientation from parallel to vertical. As spraying proceeds, MNPs aggregate into agglomerates with increasing sizes. After the spray deposition is finished, both samples gradually reach an equilibrium state and magnetic films with stable structures are achieved in the end. Superconducting quantum interference device investigation reveals the superparamagnetic property of the sprayed hybrid film. Consequently, potential application of sprayed films in fields such as magnetic sensors or data storage appears highly promising.     

Mechano‐ and Photochromism from Bulk to Nanoscale: Data Storage on Individual Self‐Assembled Ribbons

A Pt(II) complex, bearing an oligo‐ethyleneoxide pendant, is able to self‐assemble in ultralong ribbons that display mechanochromism upon nanoscale mechanical stimuli, delivered through atomic force microscopy (AFM). Such observation paves the way to fine understanding and manipulation of the mechanochromic properties of such material at the nanoscale. AFM allows quantitative assessment of nanoscale mechanochromism as arising from static pressure (piezochromism) and from shear‐based mechanical stimuli (tribochromism), and to compare them with bulk pressure‐dependent luminescence observed with diamond‐anvil cell (DAC) technique. Confocal spectral imaging reveals that mechanochromism only takes place within short distance from the localized mechanical stimulation, which allows to design high‐density information writing with AFM nanolithography applied on individual self‐assembled ribbons. Each ribbon hence serves as an individual microsystem for data storage. The orange luminescence of written information displays high contrast compared to cyan native luminescence; moreover, it can be selectively excited with visible light. In addition, ribbons show photochromism, i.e., the emission spectrum changes upon exposure to light, in a similar way as upon mechanical stress. Photochromism is here conveniently used to conceal and eventually erase information previously written with nanolithography by irradiation.     

Superparamagnetic Hyperbranched Polyglycerol‐Grafted Fe3O4 Nanoparticles as a Novel Magnetic Resonance Imaging Contrast Agent: An In Vitro Assessment

Hyperbranched polyglycerol‐grafted, magnetic Fe₃O₄ nanoparticles (HPG‐grafted MNPs) are successfully synthesized by surface‐initiated ring‐opening multibranching polymerization of glycidol. Reactive hydroxyl groups are immobilized on the surface of 6–9 nm Fe₃O₄ nanoparticles via effective ligand exchange of oleic acid with 6‐hydroxy caproic acid. The surface hydroxyl groups are treated with aluminum isopropoxide to form the nanosized macroinitiators. The successful grafting of HPG onto the nanoparticles is confirmed by infrared and X‐ray photoelectron spectroscopy. The HPG‐grafted MNPs have a uniform hydrodynamic diameter of (24.0 ± 3.0) nm, and are very stable in aqueous solution, as well as in cell culture medium, for months. These nanoparticles have great potential for application as a new magnetic resonance imaging contrast agent, as evidenced by their lack of cytotoxicity towards mammalian cells, low uptake by macrophages, excellent stability in aqueous medium and magnetic fields, and favorable magnetic properties. Furthermore, the possibility of functionalizing the hydroxyl end‐groups of the HPG with cell‐specific targeting ligands will expand the range of applications of these MNPs.     

基于SATA的高速CCD存储方案设计

航测图像具有分辨率高、数据量大等特点,为了将高帧频、高分辨率CCD相机的航测图像数据实时存储下来,当前的多PC机并行存储方法,已无法满足实时存储的要求,根据串行硬盘接口SATA协议,在可编程逻辑门阵列FPGA内实现了一种CCD图像数据的高速实时存储方案.此方案可以将数据采集、存储集成在单片FPGA内实现.利用V5FX70系列FPGA中的高速收发器GTX实现了SATA2.6协议,单盘速度可达到94.6 MB/S,若将多个盘组成硬盘阵列RAID,可以将CCD数据并行存储到SATA硬盘上.此方案单片FPGA最多可实现16个SATA硬盘接口,具有可高速、实时、稳定、便携等优点.