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<jats:p>We present a room temperature nonlinear mass sensing based on a hybrid spin-nanoresonator system with the microwave pump–probe technique and the spin readout technique, which includes a single spin of nitrogen–vacancy (NV) center in diamond and a nanomechanical cantilever. The resonance frequency of the nanoresonator can be measured with the nolinear Kerr spectrum, and the parameters that influence the nolinear Kerr spectrum are also investigated. Further, according to the relationship between frequency shifts and variable mass attached on the nanoresonator, this system can also be used to detect the mass of DNA molecules with the nolinear Kerr spectrum. Benefiting from the single spin of the NV center in diamond has a long coherence time at 300 K, the hybrid system can realize room temperature mass sensor, and the mass response rate can reach 2600 zg/Hz.</jats:p>

<jats:p>We investigate the mechanical and microstructural changes of the densified silica glass under uniaxial loading-unloading via atomistic simulations with a modified BKS potential. The stress–strain relationship is found to include three respective stages: elastic, plastic and hardening regions. The bulk modulus increases with the initial densification and will undergo a rapid increase after complete densification. The yield pressure varies from 5 to 12 GPa for different densified samples. In addition, the Si–O–Si bond angle reduces during elastic deformation under compression, and 5-fold Si will increase linearly in the plastic deformation. In the hardening region, the peak splitting and the new peak are both found on the Si–Si and O–O pair radial distribution functions, where the 6-fold Si is increased. Instead, the lateral displacement of the atoms always varies linearly with strain, without evident periodic characteristic. As is expected, the samples are permanently densified after release from the plastic region, and the maximum density of recovered samples is about 2.64 g/cm<jats:sup>3</jats:sup>, which contains 15 % 5-fold Si, and the Si–O–Si bond angle is less than the ordinary silica glass. All these findings are of great significance for understanding the deformation process of densified silica glass.</jats:p>

<jats:p>Nanodiamonds have outstanding mechanical properties, chemical inertness, and biocompatibility, which give them potential in various applications. Current methods for preparing nanodiamonds often lead to products with impurities and uneven morphologies. We report a two-step high-pressure high-temperature (HPHT) method to synthesize nanodiamonds using naphthalene as the precursor without metal catalysts. The grain size of the diamonds decreases with increasing carbonization time (at constant pressure and temperature of 11.5 GPa and 700 °C, respectively). This is discussed in terms of the different crystallinities of the carbon intermediates. The probability of secondary anvil cracking during the HPHT process is also reduced. These results indicate that the two-step method is efficient for synthesizing nanodiamonds, and that it is applicable to other organic precursors.</jats:p>

<jats:p>The equilibrium distribution of a polymer chain between two interconnected spherical cavities (a small one with radius <jats:italic>R</jats:italic> <jats:sub>s</jats:sub> and a large one with radius <jats:italic>R</jats:italic> <jats:sub>l</jats:sub>) is studied by using Monte Carlo simulation. A conformational transition from a double-cavity-occupation (DCO) state to a single-cavity-occupation (SCO) state is observed. The dependence of the critical radius of the small cavity (<jats:italic>R</jats:italic> <jats:sub>sC</jats:sub>) where the transition occurs on <jats:italic>R</jats:italic> <jats:sub>l</jats:sub> and the polymer length <jats:italic>N</jats:italic> can be described by <jats:inline-formula> <jats:tex-math> <?CDATA ${R}_{{\rm{sC}}}\propto {N}^{1/3}{R}_{{\rm{l}}}^{1-1/3\nu }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>R</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">sC</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∝</mml:mo> <mml:msup> <mml:mi>N</mml:mi> <mml:mrow> <mml:mn>1</mml:mn> <mml:mo>/</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> <mml:msubsup> <mml:mi>R</mml:mi> <mml:mi mathvariant="normal">l</mml:mi> <mml:mrow> <mml:mn>1</mml:mn> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> <mml:mo>/</mml:mo> <mml:mn>3</mml:mn> <mml:mi>ν</mml:mi> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_29_10_108201_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> with <jats:italic>ν</jats:italic> being the Flory exponent, and meanwhile the equilibrium number (<jats:italic>m</jats:italic> <jats:sub>s</jats:sub>) of monomers in the small cavity for the DCO phase can be expressed as <jats:italic>m</jats:italic> <jats:sub>s</jats:sub> = <jats:italic>N</jats:italic>/((<jats:italic>R</jats:italic> <jats:sub>l</jats:sub>/<jats:italic>R</jats:italic> <jats:sub>s</jats:sub>)<jats:sup>3</jats:sup> + 1), which can be quantitatively understood by using the blob picture. Moreover, in the SCO phase, the polymer is found to prefer staying in the large cavity.</jats:p>

<jats:p>The techniques for oceanographic observation have made great progress in both space-time coverage and quality, which make the observation data present some characteristics of big data. We explore the essence of global ocean dynamic via constructing a complex network with regard to sea surface temperature. The global ocean is divided into discrete regions to represent the nodes of the network. To understand the ocean dynamic behavior, we introduce the Gaussian mixture models to describe the nodes as limit-cycle oscillators. The interacting dynamical oscillators form the complex network that simulates the ocean as a stochastic system. Gaussian probability matching is suggested to measure the behavior similarity of regions. Complex network statistical characteristics of the network are analyzed in terms of degree distribution, clustering coefficient and betweenness. Experimental results show a pronounced sensitivity of network characteristics to the climatic anomaly in the oceanic circulation. Particularly, the betweenness reveals the main pathways to transfer thermal energy of El Niño–Southern oscillation. Our works provide new insights into the physical processes of ocean dynamic, as well as climate changes and ocean anomalies.</jats:p>

<jats:p>The formation of cavities in silicon carbide is vitally useful to “smart-cut” and metal gettering in semiconductor industry. In this study, cavities and extended defects formed in helium (He) ions implanted 6H-SiC at room temperature (RT) and 750 °C followed by annealing at 1500 °C are investigated by a combination of transmission electron microscopy and high-resolution electron microscopy. The observed cavities and extended defects are related to the implantation temperature. Heterogeneously distributed cavities and extended defects are observed in the helium-implanted 6H-SiC at RT, while homogeneously distributed cavities and extended defects are formed after He-implanted 6H-SiC at 750 °C. The possible reasons are discussed.</jats:p>

<jats:p>A high performance fast-Fourier-transform (FFT) spectrum analyzer, which is developed for measure spin noise spectrums, is presented in this paper. The analyzer is implemented with a field-programmable-gate-arrays (FPGA) chip for data and command management. An analog-to-digital-convertor chip is integrated for analog signal acquisition. In order to meet the various requirements of measuring different types of spin noise spectrums, multiple operating modes are designed and realized using the reprogrammable FPGA logic resources. The FFT function is fully managed by the programmable resource inside the FPGA chip. A 1 GSa/s sampling rate and a 100 percent data coverage ratio with non-dead-time are obtained. 30534 FFT spectrums can be acquired per second, and the spectrums can be on-board accumulated and averaged. Digital filters, multi-stage reconfigurable data reconstruction modules, and frequency down conversion modules are also implemented in the FPGA to provide flexible real-time data processing capacity, thus the noise floor and signals aliasing can be suppressed effectively. An efficiency comparison between the FPGA-based FFT spectrum analyzer and the software-based FFT is demonstrated, and the high performance FFT spectrum analyzer has a significant advantage in obtaining high resolution spin noise spectrums with enhanced efficiency.</jats:p>

<jats:p>An all-fiber dumbbell-shaped dual-amplifier mode-locked Er-doped laser that can function in dissipative soliton resonance (DSR) regime is demonstrated. A nonlinear optical loop mirror (NOLM) and a nonlinear amplifying loop mirror (NALM) are employed to initiate the mode-locking pulses. Unlike conventional single-amplifier structure, the output peak power of which remains unchanged when pump power is varied, the proposed structure allows its output peak power to be tuned by changing the pump power of the two amplifiers while the pulse duration is directly determined by the amplifier of nonlinear amplifying loop mirror. The entire distribution maps of peak power and pulse duration clearly demonstrate that the two amplifiers are related to each other, and they supply directly a guideline for designing tunable peak power DSR fiber laser. Pulse width can change from 800 ps to 2.6 ns and peak power varies from 13 W to 27 W. To the best of our knowledge, the peak power tunable DSR pulse is observed for the first time in dumbbell-shaped Er-doped all-fiber mode-locked lasers.</jats:p>

<jats:p>Two-dimensional (2D) materials received large amount of studies because of the enormous potential in basic science and industrial applications. Monolayer Pd<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> is a fascinating 2D material that was predicted to possess excellent thermoelectric, electronic, transport, and optical properties. However, the fabrication of large-scale and high-quality monolayer Pd<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> is still challenging. Here, we report the synthesis of large-scale and high-quality monolayer Pd<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> on graphene-SiC (0001) by a two-step epitaxial growth. The atomic structure of Pd<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> was investigated by scanning tunneling microscope (STM) and confirmed by non-contact atomic force microscope (nc-AFM). Two subgroups of Se atoms have been identified by nc-AFM image in agreement with the theoretically predicted atomic structure. Scanning tunneling spectroscopy (STS) reveals a bandgap of 1.2 eV, suggesting that monolayer Pd<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> can be a candidate for photoelectronic applications. The atomic structure and defect levels of a single Se vacancy were also investigated. The spatial distribution of STS near the Se vacancy reveals a highly anisotropic electronic behavior. The two-step epitaxial synthesis and characterization of Pd<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> provide a promising platform for future investigations and applications.</jats:p>