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Surrogate PHFGMC micromechanical models for multiscale analysis: AI-enhanced low-velocity impact analysis of hat-stiffened composite panels

The Parametric High-Fidelity Generalized Method of Cells (PHFGMC) has been established as an advanced micromechanical approach well-suited for analyzing the material nonlinearity and failure behavior of diverse periodic composite materials. In order to overcome the prohibitive computational cost of integrating micromechanical models into multiscale structural analyses as constitutive models, a proxy-surrogate modeling approach has been proposed by implementing a reduction modeling approach with deep Artificial Neural Networks (DNNs or ANNs). The PHFGMC-ANN approach has been employed to investigate the low velocity impact (LVI) analyses of hat-stiffened laminated composite panels under impact loading at various locations and energies with two different support conditions. Subsequent analysis of stiffened panels under compression loading has been conducted to understand the failure behavior of impacted panels. Further investigation was conducted into the separation between the skin and the stiffener, focusing on a single hat-stiffened coupon subjected to LVI. The analysis results have been compared against the experimental tests, and the comparison of interlaminar delamination has been used to demonstrate the efficacy of the new framework in integrating refined nonlinear micromechanical models within a multiscale analysis.

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Investigation of cutting forces of glass sphere reinforced polymer composites

AbstractIn this study, the effects of reinforcement ratio, drill bit material, and drilling process parameters on the cutting forces generated during the drilling of glass sphere‐reinforced polypropylene composites were investigated experimentally. Test specimens were produced by conventional injection‐moulding of glass sphere reinforced polypropylene composite materials at 5 %, 10 % and 20 % wt. ratios. High speed steel, titanium‐coated high‐speed steel, and carbide drill bits with 4 mm diameter were preferred for drilling. In addition, the drilling process was carried out on a 3‐axis computer numeric control milling machine. Three different feed rates of 0.05 mm/rev, 0.10 mm/rev, and 0.15 mm/rev and cutting speeds of 12 m⋅min−1, 16 m⋅min−1, and 20 m⋅min−1 were determined for the drilling process. In addition, Taguchi experimental optimization method, analysis of variance and scanning electron microscopy were used to investigate the morphology of the drilled surface and the wear mechanisms occurring on the drill bit due to the drilling process. The test findings showed that the maximum torque value was 54.64 N⋅mm and the maximum thrust force was 100.43 N. The optimum test parameter for cutting forces was observed as C1D3FR1CS3. Drill parameter had an effect of 40.96 % on thrust force and 36.11 % on torque.

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Fully aminated <i>p</i>‐polyaramid effectively strengthen and toughen <scp>B</scp>isphenol <scp>A</scp> epoxy resin and its warp‐knitted carbon fiber composites

AbstractStemming from the cost‐effectiveness and broad applicability, many modification researches on Bisphenol A epoxy resin (DGEBA) and its carbon fiber composites have been done extensively. Here, following the concept of molecular composite, we prepared fully aminated p‐polyaramid with reactive amino side groups by polycondensation and reduction reaction, aiming to construct a molecular distribution of the reinforcement within the resin matrix and achieve a satisfactory enhancement effect. Among them, after adding 1 wt% fully aminated p‐polyaramid, Young's modulus and tensile toughness of the DGEBA epoxy resin (EP) increased significantly to 2.34 ± 0.03 GPa (+68.3%) and 4402 ± 213 kJ/m3 (+30.5%), the flexural modulus and toughness reached 4.14 ± 0.04 GPa (+42.8%) and 0.44 ± 0.01 J (+83.3%). Moreover, the Tg of EP was only decreased by 2.7°C. In addition, their warp‐knitted bidirectional carbon fiber composites also have enhancements in both flexural properties and interlaminar shear strength (all improved by more than 20%). What is noticeable is that the preparation and blending of fully aminated p‐polyaramid are simpler and more effective than most other micro‐ or nanofillers, and the dispersion is more uniform. Thus, it can act as a highly effective reinforcement and strengthen the properties of DGEBA and its carbon fiber composite materials significantly.Highlights Fully aminated p‐polyaramid is uniformly dispersed in EP by chemical bonds. DGEBA is strengthened and toughened without a significant decrease in Tg. The tensile and flexural modulus of EP is increased by 68.3% and 42.8%. Fully aminated p‐polyaramid can reinforce warp‐knitted carbon fiber composite.

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Divergent Regioselective Synthesis of Functionalized 1,2,3-1H-Triazoles from Nitriles and Arylazides Under Metal-Free and/or Solvent-Free Conditions.

Highly selective and divergent syntheses, which are crucial in both organic synthesis and medicinal chemistry, involve significant advancements in compound accessibility. By modifying α-cyano esters into α-cyano ketones, the synthesis pathway broadens to include a diverse range of 4-CN, 5-amino, and 5-arylamino derivatives of 1,2,3-triazoles, which are achieved notably through the Dimroth rearrangement. This versatility extends further with the potential for a triple cascade reaction, leading to the production of carboximidamide compounds, which are facilitated by the Cornforth rearrangement. Advancements in compound accessibility not only expand the repertoire of synthesized molecules but also open new avenues for potential pharmacological agents. Building on these findings, we have developed an innovative and efficient method for the divergent synthesis of functionalized 1,2,3-triazoles. This method strategically utilizes α-cyanocarbonyls and arylazides by harnessing their reactivity and compatibility to orchestrate a variety of molecular transformations. By optimizing these substrates, our goal is to simplify synthetic routes, improve product yields, and accelerate the discovery and development of new chemical entities with promising biological activities.

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Advances in the Synthesis and Biological Applications of Enoxacin-Based Compounds

A comprehensive review of advances in the synthesis and biological applications of enoxacin (1, referred to as ENX)-based compounds is presented. ENX, a second-generation fluoroquinolone (FQ), is a prominent 1,8-naphthyridine containing compounds studied in medicinal chemistry. Quinolones, a class of synthetic antibiotics, are crucial building blocks for designing multi-biological libraries due to their inhibitory properties against DNA replication. Chemical modifications at positions 3 and 7 of the quinolone structure can transform antibacterial FQs into anticancer analogs. ENX and its derivatives have been examined for various therapeutic applications, including anticancer, antiviral, and potential treatment against COVID-19. Several synthetic methodologies have been devised for the efficient and versatile synthesis of ENX and its derivatives. This review emphasizes all-inclusive developments in the synthesis of ENX derivatives, focusing on modifications at C3 (carboxylic acid, Part A), C7 (piperazinyl, Part B), and other modifications (Parts A and B). The reactions considered were chosen based on their reproducibility, ease of execution, accessibility, and the availability of the methodology reported in the literature. This review provides valuable insights into the medicinal properties of these compounds, highlighting their potential as therapeutic agents in various fields.

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High‐Performance Supercapacitor Electrodes Based on Porosity‐Controllable Carbon Paper by Centrifugal Spinning

Carbon paper is widely utilized in supercapacitors primarily for its notable attributes, including high specific surface area, commendable electrical conductivity, and excellent chemical stability. Then investigate the effect of carbon paper with different porosities as supercapacitor substrates on the electrochemical performance of electrodes. Meanwhile, tungsten oxide is grown on the surface of carbon paper using the hydrothermal method to test the electrochemical performance of the composite electrode. The prepared carbon paper and oxygen‐deficient tungsten oxide (WOx) composite electrode (CP@WOx) exhibit an area‐specific capacitance of 915.8 mF/cm² at a current density of 5 mA/cm². In addition, the electrode exhibits good cycling stability. After 20,000 cycles, the capacitance remains 104.1% of the original capacity at 50 mA/cm² current density. Solid‐state symmetric supercapacitors assembled using CP@WOx electrode exhibit excellent performance in terms of surface energy density of 6.25 µWh/cm2(at a power density of 0.6 mW/cm2) and maintain 100.4% of their original capacity after 7000 charge/discharge cycles. Relying on the higher productivity advantage of centrifugal spinning technology over electrostatic spinning technology and other preparation processes, this study develops a new way of thinking for the large‐scale production of composite electrode materials, which has more considerable potential for large‐scale development.

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Autonomous mobile robots for exploratory synthetic chemistry.

Autonomous laboratories can accelerate discoveries in chemical synthesis, but this requires automated measurements coupled with reliable decision-making1,2. Most autonomous laboratories involve bespoke automated equipment3-6, and reaction outcomes are often assessed using a single, hard-wired characterization technique7. Any decision-making algorithms8 must then operate using this narrow range of characterization data9,10. By contrast, manual experiments tend to draw on a wider range of instruments to characterize reaction products, and decisions are rarely taken based on one measurement alone. Here we show that a synthesis laboratory can be integrated into an autonomous laboratory by using mobile robots11-13 that operate equipment and make decisions in a human-like way. Our modular workflow combines mobile robots, an automated synthesis platform, a liquid chromatography-mass spectrometer and a benchtop nuclear magnetic resonance spectrometer. This allows robots to share existing laboratory equipment with human researchers without monopolizing it or requiring extensive redesign. A heuristic decision-maker processes the orthogonal measurement data, selecting successful reactions to take forward and automatically checking the reproducibility of any screening hits. We exemplify this approach in the three areas of structural diversification chemistry, supramolecular host-guest chemistry and photochemical synthesis. This strategy is particularly suited to exploratory chemistry that can yield multiple potential products, as for supramolecular assemblies, where we also extend the method to an autonomous function assay by evaluating host-guest binding properties.

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Exceptions, Paradoxes, and Their Resolutions in Chemical Reactivity.

Progress in chemistry has primarily been framed through inductive processes, leading to the frequent emergence of exceptions and unexpected reactivities. These anomalies─ranging from surprising reactivity trends and paradoxical understandings to unanticipated parameter influences and unexpected successes or failures in synthetic methods─offer valuable insights that can drive scientific discovery. While it is commonly accepted that such exceptions can drive progress, many have been passively accepted without being explored for opportunities. Although numerous chemists have addressed exceptions and refined chemical models and theories, employing a systematic framework for actively exploring and understanding the underlying causes of exceptions could resolve paradoxes in broader contexts and create a greater impact than treating anomalies as isolated occurrences. This perspective demonstrates a proactive epistemic approach to uncovering the opportunities presented by exceptions and promotes deliberate, thoughtful engagement with paradoxes and anomalies. While the examples primarily focus on physical organic chemistry, the concepts are broadly applicable across various fields in chemical science. The thinking framework presented here is neither exhaustive nor prescriptive, but it outlines one of many potentially possible ways to inspire further development in how these anomalies could be harnessed for advancement.

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