High-Spin and Reactive Fe13 Cluster with Exposed Metal Sites

Atomically defined large metal clusters have applications in new reaction development and preparation of materials with tailored properties. Expanding the synthetic toolbox for reactive high nuclearity metal complexes, we report a new class of Fe clusters, Tp*₄W₄Fe₁₃S₁₂ , displaying a Fe₁₃ core with M−M bonds that has precedent only in main group and late metal chemistry. M₁₃ clusters with closed shell electron configurations can show significant stability and have been classified as superatoms. In contrast, Tp*₄W₄Fe₁₃S₁₂ displays a large spin ground state of S=13. This compound performs small molecule activations involving the transfer of up to 12 electrons resulting in significant cluster rearrangements.     

Extraction and characterization of highly pure alumina (α, γ, and θ) polymorphs from waste beverage cans: A viable waste management approach

The recycling and recovery of important materials from inexpensive feedstock has now become an intriguing area and vital from commercial and environmental viewpoints. In the present work, extraction of different single phases of alumina (α, γ, θ-Al₂O₃) having high purity (>99.5 %) from locally available waste beverage cans (～95 % Al) through facile precipitation route calcined at distinct temperatures has been reported. The optimization of process technology was done by a variety of different synthesis parameters, and the production cost was estimated between 84.47-87.45 USD per kg of alumina powder. The as prepared alumina fine particles have been characterized using different sophisticated techniques viz. TG-DTA, WD-XRF, XRD, FT-IR, SEM, DLS-based particle size analysis (PSA) with zeta (ζ) potential measurement and UV–Visible Spectroscopy. X-ray diffractogram confirms the formation of γ-, θ-, and α-alumina at 500–700 °C, 900–1000 °C, and 1200 °C respectively and crystallite size, crystallinity, strain, dislocation density, and specific surface area were measured using major X-ray diffraction peaks which varies with temperature. The SEM studies showed that the as prepared alumina particles were agglomerated, irregular-shaped with particle size (0.23–0.38 µm), pore size, and porosity were calculated from SEM image. ζ-potentials at different pH values as well as isoelectric point (IEP) of α, γ, and θ alumina were calculated in an aqueous medium which changes with temperature. The direct band gap (E_g) energies were found between 4.09 and 5.19 eV of alumina obtained from different calcination temperatures. The synthesized materials can be used in sensors, ceramics, catalysis, and insulation applications.     

新型低共熔溶剂的制备、表征及物性研究

以氯化1-丁基-3-甲基咪唑鎓([Bmim]Cl)和二元羧酸为原料,由不同摩尔比混合制备了一类新型低共熔溶剂,采用红外光谱对[Bmim]Cl和二元羧酸之间的作用进行了分析。分别测定了其粘度、电导率、密度、折射率等物理性质,并研究了温度、二元羧酸结构和摩尔比对这些物理性质的影响。结果表明,新型低共熔溶剂的粘度随温度的升高而降低,电导率随温度的升高而增加。温度对两者的影响可以采用VTF方程进行精确地拟合。新型低共熔溶剂的密度随温度的升高而呈线性下降。对新型低共熔溶剂的过量摩尔体积进行计算的结果表明,过量摩尔体积均为正值,二元羧酸对过量摩尔体积的贡献远大于[BMIM]Cl,而结构特性的贡献多于物理作用。折射率和密度随二元羧酸碳数的变化趋势基本相似。     

Bioanalytical chemistry of cytokines – A review

Cytokines are bioactive proteins produced by many different cells of the immune system. Due to their role in different inflammatory disease states and maintaining homeostasis, there is enormous clinical interest in the quantitation of cytokines. The typical standard methods for quantitation of cytokines are immunoassay-based techniques including enzyme-linked immusorbent assays (ELISA) and bead-based immunoassays read by either standard or modified flow cytometers. A review of recent developments in analytical methods for measurements of cytokine proteins is provided. This review briefly covers cytokine biology and the analysis challenges associated with measurement of these biomarker proteins for understanding both health and disease. New techniques applied to immunoassay-based assays are presented along with the uses of aptamers, electrochemistry, mass spectrometry, optical resonator-based methods. Methods used for elucidating the release of cytokines from single cells as well as in vivo collection methods are described.     

Analytical potential of a laser ablation–glow discharge–optical emission spectrometry system for the analysis of conducting and insulating materials

The analytical capabilities of a glow discharge (GD) as a secondary source for excitation/ionization of the material provided by laser ablation (LA) have been compared to conventional laser induced breakdown spectroscopy (LIBS). In LA–GD both sources can be independently adjusted to optimize the sampling process and then its subsequent excitation. This could involve a number of analytical performance advantages, such as reduced matrix dependence, greater precision and sensitivity than those encountered in LIBS. For such purpose, an ablation chamber design including two electrodes to generate the GD discharge has been built and assayed. A comparison between LIBS and LA–GD–OES has been carried out, both, under reduced argon and helium atmospheres. Different sets of samples (conducting reference materials, glass and fluorine pellets) have been used to evaluate the novel coupled technique. The LA–GD coupled system has shown to provide lower detection limits. In addition, best linear correlations between intensities and concentrations and lower matrix effects have also been found using the coupled system. Moreover, special advantages of the LA–GD–OES have also been demonstrated for the analysis of fluorine.     

A new device for in-line colorimetric quantification of polypropylene degradation under multiple extrusions

An in-line colorimeter that is able to quantify color changes in real time during extrusion was developed and validated. It is composed of LEDs emitting at three different wavelengths and a photocell that measures the intensity of the light transmitted through the polymer melt flow. The colorimeter was validated at the bench by employing colored aqueous solutions and in-line during the extrusion of a colored polypropylene. Furthermore, it was used to in-line quantify the color changes in a polypropylene as generated over multiple extrusions due to thermo-mechanical degradation. The technique was proved to be fast and suitable to measure color changes in real time during extrusion.     

Tough and transparent blends of polylactide with block copolymers of ethylene glycol and propylene glycol

In order to modify its physical properties, particularly the drawability and toughness, polylactide (PLA) was melt blended with a set of PEG-b-PPG-b-PEG block copolymers with varying ratio of the hydrophilic (PEG) and hydrophobic (PPG) blocks. Miscibility of the copolymers with PLA depended on their molar mass and PEG content. Interestingly, the best drawability was achieved in the case of partially miscible blends, in which fine liquid inclusions of the modifier were dispersed in PLA rich matrix with glass transition temperature only moderately decreased, to about 50 °C. About 37 fold increase of the elongation at break and about 1.5 fold increase of the tensile impact strength with respect to neat PLA were reached at small content (10 wt.%) of the modifier. Despite the phase separation, the blends remained transparent. In addition, the barrier properties for oxygen were improved.     

Assessment of nanoparticle loading and dispersion in polymeric materials using optical wavefront correlation

Small concentrations (≤5 wt. %) of nanoparticles in polymeric materials can potentially result in improvements in material properties and functionality. However, poor or non-uniform particle dispersion resulting in clustering (agglomeration) in polymer nanocomposites (PNCs) limits the potential for property enhancement. Achieving good dispersion is considered essential for large-scale production and commercialization of PNCs. New and effective measurement techniques capable of quantitatively characterizing particle loading and dispersion would significantly contribute towards understanding and optimizing the material performance of PNCs and, consequently, play a pivotal role in product development. This paper presents the results of a study using a static light scattering technique, optical wavefront correlation (OWC), for discriminating between different particle loadings and levels of dispersion. The technique has been applied to a range of PNCs, including epoxy resins reinforced with nanoclay platelets or silica microspheres, and zinc oxide and lithium aluminate reinforced polypropylene.     

Active learning for OPM in FMF systems

Optical performance monitoring (OPM) is essential to guarantee the robust and reliable operation of few-mode fiber (FMF)-based transmission. The available OPM methods including the analytical models such as the enhanced Gaussian noise model provide high accuracy along with high computational complexity which makes them improper for real-time implementations. As an alternative approach, machine learning (ML)-based OPM removes this barrier at the cost of leveraging a large training dataset. However, generating a field or synthetic dataset for FMF-based transmission is very hard and time-consuming. As a specific ML deployment, active learning (AL) is designed to work with a small training dataset, therefore, in this paper, we employ AL for OPM in FMF-based transmission. Results indicate that the proposed AL-based OPM can properly estimate the generalized signal-to-noise ratio by using a very small training dataset and achieve the root mean squared error similar to that obtained by working on large training datasets.     

Effects of High Pressure on the Surface Plasmon Resonance of Copper and Silver Nanocrystals

We used a diamond anvil cell(DAC) to control the deformation of synthesized copper nanorods and silver nanoparticles. And we measured the surface plasmon resonance of copper nanorods and silver nanoparticles, which exhibit redshifts or blueshifts. The surface plasmon resonance shows an abnormal blue shift for both copper nanorods and silver nanoparticles. The solvents of copper nanorods and silver nanoparticles are n-hexane and water, where the pressure loads include quasi-hydrostatic and non-hydrostatic.