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Least Squares Regression (LSR) is a powerful machine learning method for image classification and feature selection. In this study, a framework approach is introduced for the multi-classification problem based on the $L_{2,p}$ -norm, utilizing more general loss functions and regularization terms, which is a robust sparse kernel-free quadratic surface least squares regression (RSQSLSR). The nonlinear relationship between features is addressed using a quadratic kernel-free technique combined with $\epsilon $ -dragging technology and manifold regularization to learn soft labels, which can achieve the goal of feature selection and classification, simultaneously. This model utilizes K quadratic surfaces mapping samples from the input space to the label space, preserving the local structure of the samples. To enhance practical applications, such as image classification, a simplified version of the method is proposed. An iterative algorithm for RSQSLSR is designed and its convergence is proved theoretically. The salient features and theoretical analysis of our proposed method are comprehensively discussed in this paper. Extensive experiments on synthetic and real datasets validate the effectiveness of our method, surpassing other state-of-the-art methods in terms of classification accuracy and feature selection performance.

Abstract $$\nu$$ -one-class support vector classification ( $$\nu$$ -OCSVC) has garnered significant attention for its remarkable performance in handling single-class classification and anomaly detection. Nonetheless, the model does not yield a unique decision boundary, and potentially compromises learning performance when the training data is contaminated by some outliers or mislabeled observations. This paper presents a novel C-parameter version of bounded one-class support vector classification (C-BOCSVC) to determine a unique decision boundary. The distance from the origin to decision boundary is the geometrical margin in the space $$\hat{\mathcal {H}}$$ (higher 1-dimension than feature space), and its maximization corresponds to the structural risk minimization (SRM) principle inscribed by an $$L_2$$ -norm regularization term both on the normal direction and bias of the decision boundary. To enhance the anti-noise and anti-outlier abilities of C-BOCSVC, the alternative robust version (C-RBOCSVC) is also developed, which incorporates the k-nearest neighbor relative density to assign varying weights to observations and mitigate the negative impact of outliers on the optimal decision boundary. The theoretical properties of the proposed method are successively derived, including the relationship between the solutions to the primal and dual problems, the connections between our C-BOCSVC and $$\nu$$ -OCSVC and the computational complexity. Experimental results over massive datasets demonstrate the feasibility and reliability of our C-BOCSVC, and highlight the superior performance of C-RBOCSVC compared to other state-of-the-art one-class classifiers when data is contaminated. The demo code of this work is publicly available at https://github.com/Zhangmath1122/C-RBOCSVC .

This paper introduces a novel phenolic resin-coated silica stationary phase grafted from the surface of amino-functionalized porous silica microspheres through copolymerization of 1,5-dihydroxynaphthalene and 1,3,5-trioxane in the dispersed state, followed by low-temperature calcination at 200 °C. The new material was identified by scanning electron microscopy, elemental analysis, thermogravimetric analysis and Fourier-transform infrared spectroscopy. The new column has the capability to separate different types of compounds. When utilizing hydrophilic interaction liquid chromatography, sulfonamide drugs and nucleosides/nucleobases could be separated with good resolution even if there were no buffer salts in the eluent. In reversed-phase liquid chromatography, the column indicated satisfactory separation abilities for positional isomers, alkylbenzenes as well as polycyclic aromatic hydrocarbons (PAHs). The selectivity and retention of the new column for PAHs were higher than those for alkylbenzene, which may be affected by the π–π forces between the PAH analytes and naphthalene ring from the surface of the silica. Depending on the retention mode, the elution order can be reversed using this column. Thus, the stationary phase was intended as a novel mixed-mode column. Meanwhile, the retention and selectivity can be adjusted very flexibly by changing the chromatographic conditions.

Chiral glutamide-derived lipids form self-assembled fibrous molecular gels that can be used as HPLC organic phases. In this study, HPLC separation efficiency was improved through the addition of branched amphiphilic glutamide lipids to the side chains of a terminally immobilized flexible polymer backbone. Poly(4-vinylpyridine) with a trimethoxysilyl group at one end was grafted onto the surface of porous silica particles (Sil−VP15, polymerization degree = 15), and the pyridyl side chains were quaternized with a glutamide lipid having a bromide group (BrG). Elemental analysis indicated that the total amount of the organic phase of the prepared stationary phase (Sil−VPG15) was 38.0 wt%, and the quaternization degree of the pyridyl groups was determined to be 32.5%. Differential scanning calorimetric analysis of a methanol suspension of Sil−VPG15 indicated that the G moieties formed a highly ordered structure below the phase transition temperature even on the silica surface, and the ordered G moieties exhibited a gel-to-liquid crystalline phase transition. Compared with a commercially available octadecylated silica column, the Sil−VPG15 stationary phase showed high selectivity toward polycyclic aromatic hydrocarbons, and particularly excellent separations were obtained for geometrical and positional isomers. Sil−VPG15 also showed highly selective separation for phenol derivatives, and bio-related molecules containing phenolic groups such as steroids were successfully separated. These separation abilities are probably due to multiple interactions between the elutes and the highly ordered functional groups, such as the pyridinium and amide groups, on the highly ordered molecular gel having self-assembling G moieties.

A one-pot solution process is devised for preparing colloidal [Bi.sub.2][Te.sub.3]-Te heterogeneous nanostructures (HNs) that comprise [Bi.sub.2][Te.sub.3] nanoplates and Te nanorods. The synthesis of [Bi.sub.2][Te.sub.3]-Te HNs has provided opportunities for producing thermoelectric materials with enhanced performance.

Fe-Cr-C-B wear-resistant steels are widely used as wear-resistant alloys in harsh environments. The M3X (M = Fe, Cr; X = C, B) cementite-type material is a commonly used strengthening phase in these alloys. This study investigated the mechanical properties of cementite (Fe, Cr)3(C, B) using the first-principle density functional theory. We constructed crystal structures of (Fe, Cr)3(C, B) with different concentrations of Cr and B. The bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and hardness of the material were calculated, and a comprehensive mechanical property database based on CALPHAD modeling of the full composition was established. The optimal concentrations of the (Fe, Cr)3(C, B) phase were systematically evaluated across its entire composition range. The material exhibited the highest hardness, shear modulus, and Young’s modulus at Cr and B concentrations in the range of 70–95 at% and 40 at%, respectively, rendering it difficult to compress and relatively poor in machinability. When the B content exceeded 90 at%, and the Cr content was zero, the shear modulus and hardness were low, resulting in poor resistance to deformation, reduced stiffness, and ease of plastic processing. This study provides an effective alloying strategy for balancing the brittleness and toughness of (Fe, Cr)3(C, B) phases.

A unified set of emulsion polymerization processes for the synthesis of a series of spherical and nonspherical magnetite-polystyrene composite colloids is reported. It presents the uniform size, complex shapes and structures, and superparamagnetic properties make these colloidal particles ideal building blocks for the fabrication of novel functional devices and materials.

We report that fully alloyed Ag/Au nanospheres with high compositional homogeneity ensured by annealing at elevated temperatures show large extinction cross sections, extremely narrow bandwidths, and remarkable stability in harsh chemical environments. Nanostructures of Ag are known to have much stronger surface plasmon resonance than Au, but their applications in many areas have been very limited by their poor chemical stability against nonideal chemical environments. Here we address this issue by producing fully alloyed Ag/Au nanospheres through a surface-protected annealing process. A critical temperature has been found to be around 930 °C, below which the resulting alloy nanospheres, although significantly more stable than pure silver nanoparticles, can still gradually decay upon extended exposure to a harsh etchant. Nanospheres annealed above the critical temperature show a homogeneous distribution of Ag and Au, minimal crystallographic defects, and the absence of structural and compositional interfaces, which account for the extremely narrow bandwidths of the surface plasmon resonance and may enable many plasmonic applications with high performance and long lifetime, especially for those involving corrosive species. [ABSTRACT FROM AUTHOR]

Understanding the concept is one aspect that is needed and must be owned by students in learning mathematics. This research aims to make learning media assisted by hawgent dynamic mathematics software on understanding the absolute value in grade 10 Senior high school to help teachers explain the concepts and assist students in finding and understanding the basic concepts of absolute value topic. The development model used in this research is ADDIE development model. ADDIE is an abridgment of Analyze, Design, Develop and Evaluation. Researchers the learning media Hawgent can help students to understand and find the concept of absolute value. Based on several aspects, clearly and attractively with an average of 78.9% in the excellent category. It is concluded that the development of learning media Hawgent dynamic mathematics software can be used on the subject of understanding the concept of absolute value and with the help of this software it can help teachers explain the concept of absolute value and the students are also very interested in this ICT-based learning media. This conclusion is related to the validation results of media experts and material experts, where the validation results from media experts on the use of learning media are in good categories.

Controlled assembly of nanoparticles into asymmetric configurations is of great interest due to their novel properties and promising applications. In this Article, we report a generic strategy for the synthesis of dimer nanoclusters and asymmetric nanoassemblies by using magnetic colloidal substrates, on which tailored surface modification and controlled physical confinement are applied. The modularity of our approach facilitates the fabrication of asymmetric nanostructures with varying sizes, shapes, compositions, surface chemistry, and surface hydrophobicity. Success in the syntheses sheds a light on the versatility of our strategy in rationally designing and synthesizing asymmetric nanostructures with tailored properties and functionalities. [ABSTRACT FROM AUTHOR]

Interparticle magnetic dipole force has been found to drive the formation of dynamic superparamagnetic colloidal particle chains that can lead to the creation of photonic nanostructures with rapidly and reversibly tunable structural colors in the visible and near-infrared spectrum. Although most studies on magnetic assembly utilize simple permanent magnets or electromagnets, magnetic fields, in principle, can be more complex, allowing the localized modulation of assembly and subsequent creation of complex superstructures. To explore the potential applications of a magnetically tunable photonic system, we study the assembly of magnetic colloidal particles in the complex magnetic field produced by a nonideal linear Halbach array. We demonstrate that a horizontal magnetic field sandwiched between two vertical fields would allow one to change the orientation of the particle chains, producing a high contrast in color patterns. A phase transition of Fe3O4@SiO2particles from linear particle chains to three-dimensional crystals is found to be determined by the interplay of the magnetic dipole force and packing force, as well as the strong electrostatic force. While a color pattern with tunable structures and diffractions can be instantly created when the particles are assembled in the form of linear chains in the regions with vertical fields, the large field gradient in the horizontal orientation may destabilize the chain structures and produces a pattern of 3D crystals that compliments that of initial chain assemblies. Our study not only demonstrates the great potential of magnetically responsive photonic structures in the visual graphic applications such as signage and security documents but also points out the potential challenge in pattern stability when the particle assemblies are subjected to complex magnetic fields that often involve large field gradients. [ABSTRACT FROM AUTHOR]

Silver nanoplates with an extremely high aspect ratio (up to over 400) and a widely tunable surface plasmon resonance (SPR) band have been successfully synthesized by combining the concepts of selective ligand adhesion and seeded growth. Citrate ligands are used as the sole surfactant to effectively block overgrowth on the basal {111} facets and only allow growth in the lateral direction. By slowing down the reaction rate using Ag−citrate complex as precursor, the thin nature of Ag nanoplates is maintained with the edge length grown up to 4 μm, which ensures the high aspect ratio and the widely tunable SPR band. We also observe a size distribution focusing effect that helps to produce uniform nanoplates as well as narrow SPR bands over a wide range, which is important in many practical applications. [ABSTRACT FROM AUTHOR]

We report the rapid formation of photonic crystal structures by assembly of uniform nonmagnetic colloidal particles in ferrofluids using external magnetic fields. Magnetic manipulation of nonmagnetic particles with size down to a few hundred nanometers, suitable building blocks for producing photonic crystals with band gaps located in the visible regime, has been difficult due to their weak magnetic dipole moment. Increasing the dipole moment of magnetic holes has been limited by the instability of ferrofluids toward aggregation at high concentration or under strong magnetic field. By taking advantage of the superior stability of highly surface-charged magnetite nanocrystal-based ferrofluids, in this paper we have been able to successfully assemble 185 nm nonmagnetic polymer beads into photonic crystal structures, from 1D chains to 3D assemblies as determined by the interplay of magnetic dipole force and packing force. In a strong magnetic field with large field gradient, 3D photonic crystals with high reflectance (83%) in the visible range can be rapidly produced within several minutes, making this general strategy promising for fast creation of large-area photonic crystals using nonmagnetic particles as building blocks. [ABSTRACT FROM AUTHOR]

Copper(l) sulfide (Cu2S) nanodisks with controllable size and aspect ratio have been synthesized by using a one-pot colloidal process, in which no pre-prepared organometallic precursors are required. The reaction involves the injection of dodecanethiol into a hot solution containing copper salt, surfactants, and a high boiling-point organic solvent. Copper thiolate forms at the beginning at the reaction which effectively acts as a precursor whose decomposition leads to further nucleation and growth of Cu2S nanocrystals. The nanocrystals begin as small nanodots in the early stages ot the reaction, gradually turning into nanodisks with aspect ratios (average disk diameter divided by thickness) up to 2.0, while the band gap ot the nanocrystals decreases accordingly. As the growth ot nanocrystals follows the monomer addition mechanism, the diameter, thickness, aspect ratio, and optical property of the Cu2S nanodisks can be tuned systematically by changing the reaction time, the amount ot surfactants, and the concentration of the precursors. This synthesis provides a simple and highly reproducible method for the preparation at Cu2S nanocrystals that may find potential applications in the fabrication of photovoltaic devices. [ABSTRACT FROM AUTHOR]

Superparamagnetic Fe3O4colloids with highly charged surfaces have been assembled into ordered structures in water in response to external magnetic fields. The colloids form chainlike structures with regular interparticle spacings of a few hundred nanometers along the direction of the external field so that the system strongly diffracts visible light. The balance between attractive (in this case, magnetic) and repulsive (electrostatic) forces dictates interparticle spacing and therefore optical properties. By changing the relative strength of these two forces, one can tune the peak diffraction wavelength over the entire visible spectrum. We were able to optimize the diffraction intensity and the tuning range through studying their dependence on variables such as the size distribution and concentration of the Fe3O4colloids or ionic strength of the solutions. The fast, reversible response and the feasibility for miniaturization impart these photonic materials great potential in applications such as optoelectronic devices, sensors, and color displays. [ABSTRACT FROM AUTHOR]

A self-templated approach has been developed for the synthesis of TiO2microcapsules with tunable size and wall thickness by heating sol−gel derived TiO2microspheres with poly(acrylic acid) (PAA) in a diethylene glycol (DEG) solution. PAA plays a crucial role in the formation of microcapsules by crosslinking the surface TiO2nanoparticles and preventing them from dissolution by DEG. Hollow microcapsules form when DEG molecules penetrate the outer layer and remove the core materials by forming soluble titanium glycolate. [ABSTRACT FROM AUTHOR]

Clusters of Au-tipped CdSe nanorods have been synthesized through nanorod polymerization driven by the controlled welding of the Au tips. The efficient collection of energetic electrons in the Au nanoparticles leads to a significant enhancement in catalysing multiple-electron reduction reactions by using methylene blue as the redox indicator. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane (PDMS) rubber can be thermally decomposed in air to produce silica vapor species which can deposit on porous anodic aluminum oxide (AAO) templates to produce silica nanotubes with a smooth surface and highly controllable thickness. [ABSTRACT FROM AUTHOR]

A one-pot solution process has been devised to synthesize colloidal Bi2Te3-Te heterogeneous nanostructures (HNs) that comprise Bi2Te3 nanoplates and Te nanorods. By controlling the reaction kinetics, the reaction of TeO32- and Bi2Te3 in the presence of hydrazine first produces uniform Te nanorods and then grows Bi2Te3 nanoplates on the tips and surfaces of these Te nanorods, forming various shapes including "nails", "barbells", "syringes", and "accordions". The specific topological arrangement realized arises from the peculiar anisotropic reactivity of the first formed Te nanorods, whose tips are subsequently exploited to seed the heterogeneous nucleation of Bi2Te3 as enabled by the similar crystal structure and the small lattice mismatch between Te and Bi2Te3. Three important processes, heterogeneous nucleation of Bi2Te3 on the tips and/or surface of Te nanorods, homogeneous nucleation of Bi2Te3, and the direct reaction of a Bi precursor and Te nanorods to form hollow structures via the Kirkendall Effect, occur under various conditions. The manipulation of these processes provides a robust means for the fine shape control of Bi2Te3-Te HNs. It is envisioned that the tailored synthesis of Bi2Te3-Te HNs may promise unique opportunities for producing thermoelectric materials with greatly enhanced performance. [ABSTRACT FROM AUTHOR]