Multivariate optimization and comparison between conventional extraction (CE) and ultrasonic-assisted extraction (UAE) of carotenoid extraction from cashew apple

Carotenoids are an essential component of cashew and can be used in pharmaceuticals, cosmetics, natural pigment, food additives, among other applications. The present work focuses on optimizing and comparing conventional and ultrasound-assisted extraction methods. Every optimization step took place with a 1:1 (w:w) mixture of yellow and red cashew apples lyophilized and ground in a cryogenic mill. A Simplex-centroid design was applied for both methods, and the solvents acetone, methanol, ethanol, and petroleum ether were evaluated. After choosing the extractor solvent, a central composite design was applied to optimize the sample mass (59–201 mg) and extraction time (6–34 min). The optimum conditions for the extractor solvent were 38% acetone, 30% ethanol, and 32% petroleum ether for CE and a mixture of 44% acetone and 56% methanol for UAE. The best experimental conditions for UAE were a sonication time of 19 min and a sample mass of 153 mg, while the CE was 23 min and 136 mg. Comparing red and yellow cashews, red cashews showed a higher carotenoid content in both methodologies. The UAE methodology was ca. 21% faster, presented a more straightforward composition of extracting solution, showed an average yield of superior carotenoid content in all samples compared to CE. Therefore, UAE has demonstrated a simple, efficient, fast, low-cost adjustment methodology and a reliable alternative for other applications involving these bioactive compounds in the studied or similar matrix.     

A note on the finite fractal dimension of the global attractors for dissipative nonlinear Schrödinger‐type equations

In this article, we present, throughout two basic models of damped nonlinear Schrödinger (NLS)–type equations, a new idea to bound from above the fractal dimension of the global attractors for NLS‐type equations. This could answer the following open issue: consider, for instance, the classical one‐dimensional cubic nonlinear Schrödinger equation $$u_t+i{u}_{xx}+i|u{|}^{2}u+\gamma u=f,f\in {\mathrm{??}}^2(?).$$ “How can we bound the fractal dimension of the associate global attractor without the need to assume that the external forcing term f has some decay at infinity (that is belonging to some weighted Lebesgue space)?”     

Mg,N掺杂β-Ga2O3光电性质的第一性原理计算

通过基于密度泛函理论的第一性原理计算,研究了Mg单掺杂、N单掺杂和不同浓度的Mg-N共掺杂β-Ga₂O₃的结构性质、电子性质和光学性质,以期获得性能比较优异的p型β-Ga₂O₃材料。建立了五种模型:Mg单掺杂、N单掺杂、1个Mg-N共掺杂、2个Mg-N共掺杂和3个Mg-N共掺杂β-Ga₂O₃。经过计算,3个Mg-N共掺杂β-Ga₂O₃体系的结构最稳定。此外,在5种模型中,3个Mg-N共掺杂β-Ga₂O₃体系的禁带宽度是最小的,并且N 2p和Mg 3s贡献的占据态抑制了氧空位的形成,从而增加了空穴浓度。因此,3个Mg-N共掺杂β-Ga₂O₃体系表现出优异的p型性质。3个Mg-N共掺杂体系的吸收峰出现明显红移,在太阳盲区的光吸收系数较大,这归因于导带Ga 4s、Ga 4p、Mg 3s向价带O 2p、N 2p的带间电子跃迁。本工作将为p型β-Ga₂O₃日盲光电材料的研究和应用提供理论指导。     

基于有序介孔碳的氯离子选择性电极的制备及其在手持传感系统中的应用

以有序介孔碳(OMC)球为离子-电子转换层,制备了固态氯离子选择性电极,构建了基于离子敏感的场效应晶体管(ISFET)的手持式传感系统,用于检测人体血清中的氯离子。优化了OMC前驱体的碳化温度,探究了OMC形貌结构对电极传感性能的影响;电极柔性化制备后考察了其在手持系统中对氯离子的检测效果。结果表明,最优条件下,电极在5.12×10^-4~1.02 mol/L的浓度范围呈现线性响应,响应斜率为60 mV/decade。该柔性电极在手持传感系统中展现出高灵敏度和重现性,可用于人体血清样品中氯离子的检测,其回收率为96.3%~104.9%。     

Air-Stable Hexagonal Bipyramidal Dysprosium(III) Single-Ion Magnets with Nearly Perfect D6h Local Symmetry

Eight-coordinated Dy^III centres with D_6h symmetry are expected to act as high-performance single-molecule magnets (SMMs) due to the simultaneous fulfilment of magnetic axiality and a high coordination number (a requisite for air stability). But the experimental realization is challenging due to the requirement of six coordinating atoms in the equatorial plane of the hexagonal bipyramid; this is usually too crowded for the central Dy^III ion. Here a hexaaza macrocyclic Schiff base ligand and finetuned axial alkoxide/phenol-type ligands are used to show that a family of hexagonal bipyramidal Dy^III complexes can be isolated. Among them, three complexes possess nearly perfect D_6h local symmetry. The highest effective magnetic reversal barrier is found at 1338(3) K and an open hysteresis temperature of 6 K at the field sweeping rate of 1.2 mT s⁻¹; this represents a new record for D_6h SMMs.     

Weighted estimates for the multilinear maximal function on the upper half‐spaces

For a general dyadic grid, we give a Calderón–Zygmund type decomposition, which is the principle fact about the multilinear maximal function on the upper half‐spaces. Using the decomposition, we study the boundedness of . We obtain a natural extension to the multilinear setting of Muckenhoupt's weak‐type characterization. We also partially obtain characterizations of Muckenhoupt's strong‐type inequalities with one weight. Assuming the reverse Hölder's condition, we get a multilinear analogue of Sawyer's two weight theorem. Moreover, we also get Hytönen–Pérez type weighted estimates.     

Multiple positive solutions for Schrödinger‐Poisson system involving singularity and critical exponent

In this paper, the existence and multiplicity of positive solutions is established for Schrödinger‐Poisson system of the form where 0 ∈ Ω is a smooth bounded domain in , , and λ > 0 is a real parameter. Combining with the variational method and Nehari manifold method, two positive solutions of the system are obtained.     

On concentration of solution to a Schrödinger logarithmic equation with deepening potential well

In this work, we prove the existence of positive solution for the following class of problems where λ>0 and is a potential satisfying some conditions. Using the variational method developed by Szulkin for functionals, which are the sum of a C¹ functional with a convex lower semicontinuous functional, we prove that for each large enough λ>0, there exists a positive solution for the problem, and that, as λ→+∞, such solutions converge to a positive solution of the limit problem defined on the domain Ω=int(V^?1({0})).     

Synthetic studies toward swinhoeisterol A,a novel steroid with an unusual carbon skeleton

Swinhoeisterol A is a novel steroid with unusual 6/6/5/7 tetracyclic skeleton. The model compound with BCD rings is constructed by Friedel–Crafts acylation and an oxidative dearomatization as key steps.     

Tuning the Reactivity of Cyclopropenes from Living Ring‐Opening Metathesis Polymerization (ROMP) to Single‐Addition and Alternating ROMP

Ring‐opening metathesis polymerization (ROMP) has become one of the most important living polymerizations. Cyclopropenes (CPEs) remain underexplored for ROMP. Described here is that the simple swap of 1‐methyl to 1‐phenyl on 1‐(benzoyloxymethyl)CPEs elicited strikingly different modes of reactivity, switching from living polymerization to either selective single‐addition or living alternating ROMP. The distinct reactivity stems from differences in steric repulsions at the Ru alkylidene after CPE ring opening. Possible olefin or oxygen chelation from ring‐opened CPE substituents was also observed to significantly affect the rate of propagation. These results demonstrate the versatility of CPEs as a new class of monomers for ROMP, provide mechanistic insights for designing new monomers with rare single‐addition reactivity, and generate a new functionalizable alternating copolymer scaffold with controlled molecular weight and low dispersity.