bluuebunny/crossref_metadata_2025 huggingface dataset:
Sharing Teaching Ideas: Discovering New Trigonometric Identities
Authors: Gordon Sheldon P.
Published: November 2020

For most of our students, trigonometric identities appear as if by magic. A recent class activity gave me the rare opportunity to lead my students to discover what appears to be a new trigonometric identity by using a combination of graphical, numerical, and algebraic tools. In this article, I demonstrate this result and then show how it can be extended to a wider class of apparently new identities that are all extensions of the Pythagorean identity.
Sound Off!: To Include More Students, Don't Focus on Contests: Prepare for Mathematics!
Authors: Belcastro Sarah-Marie
Published: November 2020

I DON'T LIKE MATHEMATICS CONTESTS. I PARTICIPATED in some local contests in high school, was unaware of the existence of regional and national contests, and avoided the Putnam in college. My general philosophical bent is toward cooperation rather than competition and toward mathematical enrichment rather than acceleration in the calculus stream. However, I also have nonemotional reasons for disliking contests, which I give in this article. Additionally, I will relate efforts to diversify participation in contests to efforts to make extracurricular mathematics more welcoming to all students. Finally, inspired by the Hampshire College Summer Studies in Mathematics program (www.hcssim.org), I have some suggestions for more-inclusive high school mathematical activities.
Activities for Students: Discovering and Exploring Mandelbrot Set Points with a Graphing Calculator
Authors: Ford Roger
Published: November 2020

The Mandelbrot set is one of the most beautiful and complicated objects in all of mathematics. The border of the set is infinite; no matter how many times you magnify the set, dazzling new images appear. Mandelbrot's discovery of the set and his subsequent work on fractals and recursive functions would not have been possible without the aid of the computer. Although the mathematics behind the Mandelbrot set is simple, creating the Mandelbrot set images involves millions of calculations.
Developing Mathematical Power by Using Explicit and Recursive Reasoning
Authors: Lannin John K.
Published: November 2020

The use of a variety of tasks that encourage students to examine the advantages and limitations of recursive and explicit reasoning. The authors discuss the reasoning for employing different types of reasoning and how to encourage students to justify their thinking.
Benjamin Banneker and the Law of Sines
Authors: Mahoney John F.
Published: November 2020

Benjamin Banneker (1731–1806), the son of a freed slave from Guinea and a black woman, born free in the territory of Maryland, was a self–taught mathematician, surveyor, and astronomer. He lived and worked on the farm he owned with his father near Baltimore. His grandmother, an Englishwoman who had come to the colonies as an indentured servant, taught Banneker how to read and write. She arranged for him to go to a local oneroom school, which was attended by several white and a few black children. The Quaker schoolmaster may have lent Banneker some books then, and later, a neighbor lent him some books on mathematics and astronomy. From these books he learned mathematics as far as double–position as well as surveying and astronomy. He began publishing annual almanacs containing his astronomical observations and predictions. He kept his notes in journals, but only one of the journals is preserved. This journal served as his notebook for astronomical observations, his diary, and his mathematics notebook. The mathematics in his journal consisted of six puzzles and two pages of mathematical writing.
Coloring Formulas for Growing Patterns
Authors: Meeks Roebuck Kay I.
Published: November 2020

Recognition and extension of patterns is a recurrent theme in the algebra strand of Principles and Standards for School Mathematics (NCTM 2000). Work with repeating patterns begins as early as prekindergarten, with students learning to extend patterns. Later, they recognize that the same pattern may be shown in different ways, and they translate patterns from one form to another, for example, changing ABABAB to * ∧ * ∧ * ∧. Such pattern activities allow students to develop logical reasoning skills, make conjectures, and test their ideas about them. As children become older, work with repeating patterns continues; but experiences with growing patterns, in which each element of the pattern is an extension of previous elements, become increasingly important. Geometric growing patterns can often be translated into number relationships and can thus be used to introduce ideas related to functions. A common method of introducing
On Enlarging the Focal Point of a Parabola
Authors: Dence Thomas P.
Published: November 2020

The traditional and most common way of defining a parabola is the algebraic approach, which defines a parabola as the set of points (x, y) that are equidistant from a given point, the focus, and a line, the directrix. Thus, in figure 1, with the focus F placed at the point (0, p), with p > 0, and the directrix at y = −p, the distance d1 between an arbitrary point (x, y) on the curve and the focus must equal the distance d2 between the point (x, y) and the directrix.
Providing Meaningful Fieldwork for Preservice Mathematics Teachers: A College-School Collaboration
Authors: Curcio Frances R. , Artzt Alice F. , Porter Merna
Published: November 2020

One of the greatest challenges for secondary mathematics teacher-educators is preparing future teachers to support reform efforts that lead to high–quality teaching. In particular, careful lesson planning, anticipation of student misconceptions, and constructive reflection on a lesson after instruction are critical concerns not only for novice teachers but also for experienced teachers. One way to help preservice teachers begin to appreciate the importance of planning and reflecting entails college faculty collaborating with exemplary school teachers in integrating and connecting learning theories with teaching practice.
Sharing Teaching Ideas: Understanding Functions without Using the Vertical Line Test
Authors: Fernández Eileen
Published: November 2020

Since I started teaching precalculus eighteen years ago, I have struggled with how to convey a function's definition so that its importance and usefulness comes across to students. This is especially the case with the Vertical Line Test (VLT), a mechanism for testing whether the graph of a relation is a function. (Vertical lines are drawn through the graph. If every vertical line intersects the graph in exactly one point, the relation is a function.) In this era of “learning mathematics with understanding” (NCTM 2000, p. 20), the Vertical (and Horizontal) Line Tests present a challenge. I find that once students are introduced to these devices, they tend to disregard the concepts that the devices are testing and instead mechanically apply the tests. This rote application limits not only the students' understanding of the concepts but also their ability to work within and across representations to solve problems related to identifying functions.
Quilt Blocks: Writing in the Geometry Classroom
Authors: Gibson Michelle , Thomas Timothy G.
Published: November 2020

Mathematics teachers are finding that they can increase the effectiveness of their instruction by employing classroom writing strategies. These strategies invite students to generate products for real-world audiences—authentic tasks that carry students' understanding beyond many standardized assignments.
Making Quilts without Sewing: Investigating Planar Symmetries in Southern Quilts
Authors: Anthony Holly Garrett , Hackenberg Amy J.
Published: November 2020

An activity for “making quilts without sewing” that enables high school students to develop their understanding of planar symmetries and wallpaper patterns. This activity incorporates the culture and traditions of quilting into the study of geometry. From the same block, students can make quilts with different patterns by using various combinations of transformations, in addition to the possible combinations of transformations that might have been used to create a quilt or wallpaper pattern. Students may also reflect upon the cultural activity of quilt makers and the art of quilt making.
Using the Dynamic Power of Microsoft Excel to Stand on the Shoulders of Giants
Authors: Donovan John E.
Published: November 2020

This article shows how Microsoft Excel's ability to vary parameters with sliders allows students to “stand on the shoulders of giants” and discover characteristics of polynomial functions. The article presents several problems and shows how they can be better understood from a graphical approach using Excel. Includes problems with possible solutions and follow up questions that lead students to an in-depth understanding of polynomials.
Discovering Relationships Involving Baravelle Spirals
Authors: Wanko Jeffrey J.
Published: November 2020

When designing a mathematics capstone course for preservice teachers entitled 'Mathematical Patterns and Structures through Inquiry,” I wanted to include contexts in which mathematics provides the underlying structure for various visual and performing arts. The book Mathematical Quilts: No Sewing Required (Venters and Ellison 1999, p. 78) looks at a number of ways that mathematical concepts—such as the golden ratio, logarithmic spirals, Pythagorean triples, and Penrose tiles—are useful to know when designing various quilt patterns.
Activities for Students: Introducing Parametric Equations through Graphing Calculator Explorations
Authors: Herman Marlena
Published: November 2020

The Algebra Standard of Principles and Standards for School Mathematics (NCTM 2000) suggests that the mathematics curriculum for grades 9–12 include the use of “a variety of symbolic representations, including recursive and parametric equations, for functions and relations” (p. 296). Parametric equations are very useful for representing graphs of curves that cannot otherwise be expressed as functions that define y in terms of x. The underlying idea of working with parametric equations is to express both x and y as functions of a third variable, called the parameter. The parametric equations are those functions assigned to x and y. The variable, typically t for time, makes parametric equations practical for modeling situations involving motion of an object along a given path by providing the coordinates of positions (x, y) of the object over time.
Geochemistry of tetrahedrite group minerals and associated silver paragenesis in the Boguszów baryte deposit, Poland
Authors: Mederski Sławomir , PRSEK Jaroslav , Niemasz Żaneta
Published: November 2020

Primary ore mineralization in the abandoned Boguszów baryte-polymetallic deposit, located in the Intra-Sudetic Depression, was studied by reflected light microscopy and electron microprobe. Ore minerals, occurring as veinlets, irregular aggregates and lenses in baryte veins are hosted by the Upper Carboniferous Chełmiec rhyodacite laccolith. They are dominated by galena, sphalerite (with Cd up to 0.04 apfu) and tetrahedrite group minerals (TGM). Four generations of the TGM were distinguished according to textural features and Ag content: (1) low-Ag tetrahedrite-(Zn) (Ag: 0.22–0.6 apfu), (2) Ag-enriched tetrahedrite-(Zn) and Ag-enriched tetrahedrite-(Fe) (Ag: 0.71–1.45 apfu), (3) members of the freibergite series: “freibergite-(Fe)” and “freibergite-(Zn)” (Ag: 3.21–3.48 apfu; Hg: up to 0.75 apfu), (4) member of the “freibergite-(Fe)” series (Ag: 5.32–5.78 apfu). Several elongated inclusions of Ag-bearing sulphosalts within galena crystals were observed (members of the series “freibergite-(Fe)” and “freibergite-(Zn)”, pyrargyrite and polybasite). These polymetallic silver-bearing ores were mined in Boguszów from the 15th to the 19th century. Additionally, small grains of cobalt-enriched löllingite and gersdorffite were observed, which were formed from fluids sourced from the ultramafic basement. The textural characteristics of the ore, the mineral paragenesis and the chemical composition of individual ore minerals indicate low-temperature crystallization conditions.
The evolution of the Carpathian Foredeep Basin during the latest Badenian and Sarmatian (Middle Miocene): inferences from micropalaeontological data
Authors: DUMITRIU Simina Dumitriţa , DUBICKA Zofia , LOGHIN Sergiu , MELINTE-DOBRINESCU Mihaela Carmen , PARUCH-KULCZYCKA Jolanta
Published: November 2020

Seven Middle Miocene (Upper Badenian to Lower Sarmatian) sedimentary sections of the Central Paratethys, two from the Polish Carpathian Foredeep Basin (PCFB) and five from the Eastern Carpathian Foreland Basin (ECFB) of Romania and the Republic of Moldova have been analysed micropalaeontologically to better constrain the Badenian-Sarmatian Extinction Event, characterized by significant taxonomic impoverishment of both foraminifers and ostracods. Our studies show significant palaeoenvironmental changes in the basin including depth, salinity, oxygenation, and organic matter flux. The occurrence of moderately diverse planktonic foraminifera (Globigerina, Globigerinita, Globorotalia, Trilobatus, Orbulina, Velapertina) in the Upper Badenian deposits of the PCFB as well as in the ECFB and their rarity in the lowermost Sarmatian indicate an almost fully marine environment during the latest Badenian, followed by a significant regression and possible appearance of much more restricted marine conditions across the boundary. The taxonomic composition of the Sarmatian foraminifera, ostracoda and calcareous nannofossils indicate that during this interval the salinity fluctuated strongly, with the water regime varying from brackish to normal marine. In addition, the identified micropalaeontological assemblages identified show palaeoenvironmental similarity across different basins of the Central Paratethys. This supports a hypothesis of possible connections during the latest Badenian between different areas of the Central Paratethys, as well as of the existence of a gateway between the Central Paratethys and the Mediterranean realm
Simulated research on displacement damage of gallium nitride radiated by different neutron sources
Authors: Xie Fei , Zang Hang , Liu Fang , He Huan , Liao Wen-Long , Huang Yu ,   School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049, China
Published: November 2020

Gallium nitride (GaN), one of the third-generation wide-bandgap semiconductors, offers significant application for advanced electronic devices utilized in neutron irradiation environments, like the defense, space, and aerospace, etc. In these applications, neutron irradiation-induced defects affect the properties of GaN and eventually degrade the performance of devices. In this work, neutron transport process in GaN is simulated by using the Monte Carlo-based code, Geant4 toolkit under four different irradiation conditions, e.g. high flux isotope reactor, high temperature gas-cooled reactor, pressurized water reactor, and atmospheric neutron irradiation. The energy spectra of primary knock-on atoms (PKA) in GaN and the corresponding weighted spectra under those irradiation conditions are analyzed. It is found that there is one unusual “peak” at around 0.58 MeV in the Primary recoil spectrum, regardless of the irradiation conditions. This peak is attributed to the neutron reaction of hydrogen nucleus, i.e., (n, p). Because of the remarkable (n,p) reaction cross-section of low-energy neutron, the intensity of this peak is related to the ratio of low-energy neutron to the total neutron spectrum. By comparing these PKA energy spectra in GaN, we can see that the PKA energy spectrum created under atmospheric neutron irradiation is similar to that in the high flux isotopic reactor. Specifically, the energy distribution of PKA is wide, and the magnitude of energy is lower than those under fission neutron irradiation conditions. In combination with the effects of nuclear reaction products on electrical properties, the high flux isotopic reactor is more suitable for simulating the irradiation of GaN in an atmospheric neutron energy spectrum environment. These above results can provide not only some insights into the evaluation of the degradation of GaN-based electronic devices under neutron irradiation, but also dataset for the study of radiation damage effect of GaN in simulated neutron environment.
ON THE MATRIX THEORY OF CONTINUOUS BEAMS ON ELASTIC FOUNDATION
Authors: HU HAI-CHANG  ,   中国科学院数学研究所
Published: November 2020

In this paper, we employ the theory of matrices and continued fractions for the solution of the bending problem of continuous beams on elastic foundation with unyielding supports. End moments are obtained in explicit expressions. Accurate numerical results may be calculated from these expressions directly without salving simultaneous equations.
Stabilization of Clayey Soils by Using the Organic Waste-Material
Authors: Yarba Necmi , Kalkan Ekrem
Published: November 2020

Soil stabilization known as the process of improving the engineering properties of soils is a method applied when the engineering properties of soil are not suitable for purpose. There are several methods of soil stabilization that could be implemented to improve the physical characteristics of the soil. In this study, the pine tree sawdust as an organic material wase used as additive material for stabilization of clayey soils and the influence of pine tree sawdust on the geotechnical properties of clayey soil was investigated in terms of strength behaviors. The pine tree sawdust is an organic waste resulting from the mechanical milling or processing of timber (wood) into various standard shapes and useable sizes. The strength properties of the clayey soil when blended with pine tree sawdust indicates that the pine tree sawdust is a good stabilization material for this problematic soil. As a result, it is concluded that the pine tree sawdust material as an organic material can be successfully used for the reinforce of clayey soils in the geotechnical applications.
Desafíos para el mantenimiento de una esfera pública democrática en la sociedad digital
Authors: Martinez Otero Juan María
Published: November 2020

El presente trabajo se propone analizar cómo el creciente protagonismo de las redes sociales en el debate público puede implicar –de forma contraintiutiva- serios riesgos para la construcción y el mantenimiento de una esfera pública democrática. Para ello, en primer lugar, se identificarán las que hasta ahora han sido consideradas como características esenciales de una esfera pública democrática, exponiendo cómo dichas características han sido reconocidas y protegidas en los ordenamientos jurídicos –tomando como referencia el ordenamiento jurídico español. Enumeradas estas características, el trabajo analiza cómo la dinámica de las redes sociales puede poner en jaque cada una de ellas. Presentados los peligros que un mal uso de las redes comporta para la esfera pública, el estudio concluye ofreciendo un catálogo de medidas que poderes públicos, industria y usuarios de Internet pueden adoptar con el fin de sortear los riesgos apuntados y contribuir a la preservación de un espacio público libre y robusto, presupuesto irrenunciable de toda democracia.
Compressive Properties of 316L Stainless Steel Topology‐Optimized Lattice Structures Fabricated by Selective Laser Melting
Authors: Xu Yangli , Li Tingting , Cao Xuanyang , Tan Yuanqiang , Luo Peihui
Published: November 2020

Some lattice structures with different relative densities (0.15–0.5) are designed by topology optimization and fabricated by selective laser melting. The temperature history of lattice structures is monitored experimentally to reveal the forming reason of the deviation of relative densities. The effect of relative densities on compressive properties of lattice structures, including mechanical properties, failure mechanism, and energy absorption capabilities, are systematically investigated. The results show that compressive properties of lattice structures vary dramatically with the changing of relative densities. Due to the existence of surface‐shaped struts, the compressive strength of topology‐optimized lattice structures has superior performance comparing to most of the other structures with rod‐shaped struts. The failure mechanism of lattice structures can be changed from shear‐ to bending‐dominated when increasing relative densities as a result of decreasing the thickness of struts. A systematic investigation of the fracture generation of struts is conducted through both deformation analysis and the finite element method. The fitting curves are established successfully to predict the mechanical properties of designed lattice structures. The aforementioned results verify the feasibility of designing high‐performance cellular structures via topology optimization. Moreover, herein a comprehensive solution to tailor desired properties for satisfying the requirements of functional components is provided.
Soft Electronics Based on Stretchable and Conductive Nanocomposites for Biomedical Applications
Authors: Llerena Zambrano Byron , Renz Aline F. , Ruff Tobias , Lienemann Samuel , Tybrandt Klas , Vörös János , Lee Jaehong
Published: November 2020

Research on the field of implantable electronic devices that can be directly applied in the body with various functionalities is increasingly intensifying due to its great potential for various therapeutic applications. While conventional implantable electronics generally include rigid and hard conductive materials, their surrounding biological objects are soft and dynamic. The mechanical mismatch between implanted devices and biological environments induces damages in the body especially for long‐term applications. Stretchable electronics with outstanding mechanical compliance with biological objects effectively improve such limitations of existing rigid implantable electronics. In this article, the recent progress of implantable soft electronics based on various conductive nanocomposites is systematically described. In particular, representative fabrication approaches of conductive and stretchable nanocomposites for implantable soft electronics and various in vivo applications of implantable soft electronics are focused on. To conclude, challenges and perspectives of current implantable soft electronics that should be considered for further advances are discussed.
Enhancement of Anticancer Efficacy and Tumor Penetration of Sorafenib by Ionic Liquids
Authors: Shi Yujie , Zhao Zongmin , Peng Kevin , Gao Yongsheng , Wu Debra , Kim Jayoung , Mitragotri Samir
Published: November 2020

Ionic liquids (ILs) possess unique solvation and biological properties for drug delivery. Choline and geranic acid (CAGE) in particular, has been successfully formulated to orally deliver insulin and hydrophobic therapeutics such as sorafenib (SRF). However, relatively little is known about the effect of CAGE on intracellular delivery of drugs. Here the effect of low‐concentration CAGE (<2 mg mL−1) on the delivery of SRF into cancer cells (4T1, PANC‐1, and HT29) as well as intestine epithelium cells (Caco‐2) is studied. The anti‐cancer effect of SRF is enhanced by up to fivefold in the presence of CAGE (0.5 mg mL−1). The effect is mediated not by enhancing the cellular uptake of SRF but by improving intracellular SRF retention by inhibiting exocytosis. Moreover, CAGE improves the anti‐tumor effect of SRF by increasing apoptosis and blocking cell‐cycle progression. Moreover, CAGE significantly enhances the penetration of SRF into and across multicellular constructs with multiple mechanisms involved. Collectively, the administration of ILs such as CAGE combined with SRF may offer a novel therapy to better inhibit tumor progression.
Machine Learning Predictions of Block Copolymer Self‐Assembly
Authors: Tu Kun‐Hua , Huang Hejin , Lee Sangho , Lee Wonmoo , Sun Zehao , Alexander‐Katz Alfredo , Ross Caroline A.
Published: November 2020

Directed self‐assembly of block copolymers is a key enabler for nanofabrication of devices with sub‐10 nm feature sizes, allowing patterning far below the resolution limit of conventional photolithography. Among all the process steps involved in block copolymer self‐assembly, solvent annealing plays a dominant role in determining the film morphology and pattern quality, yet the interplay of the multiple parameters during solvent annealing, including the initial thickness, swelling, time, and solvent ratio, makes it difficult to predict and control the resultant self‐assembled pattern. Here, machine learning tools are applied to analyze the solvent annealing process and predict the effect of process parameters on morphology and defectivity. Two neural networks are constructed and trained, yielding accurate prediction of the final morphology in agreement with experimental data. A ridge regression model is constructed to identify the critical parameters that determine the quality of line/space patterns. These results illustrate the potential of machine learning to inform nanomanufacturing processes.
Effects of External Stimulators on Engineered Skeletal Muscle Tissue Maturation
Authors: Mueller Claudia , Trujillo‐Miranda Mairon , Maier Michael , Heath Daniel E. , O'Connor Andrea J. , Salehi Sahar
Published: November 2020

Engineering functional skeletal muscle tissue is an ongoing challenge because of the complexity of the in vivo microenvironment and the various factors that contribute to the development and maintenance of the native tissue. However, the growing understanding of the natural skeletal muscle's microenvironment in vivo, as well as the ability to successfully reproduce these factors in vitro, are contributing to the formation of engineered skeletal muscle tissues (SMTs) with greater biomimetic structure and function. This review first summarizes the structure of skeletal muscle tissue. The role of various hydrogels, biomaterials, and scaffolds as building blocks of complex skeletal muscle structures is then explored. Additionally, the role of external stimuli and regulators that can be applied during in vitro culture that lead to the formation of SMT models with higher functionality is examined. These include various physical, biochemical, electrical, mechanical, and magnetic stimulations, as well as biological stimulation through coculture with fibroblasts, endothelial, or neuronal cells. Finally, examples of recently developed functional tissue models that have been developed for in vitro and in vivo applications and the future outlook for this field are discussed.
Widely Tunable Optical Vortex Array Generator Based on Grid Patterned Liquid Crystal Cell
Authors: Lee Doyeon , Lee Heesu , Migara L. K. , Kwak Keumcheol , Panov Vitaly P. , Song Jang‐Kun
Published: November 2020

Since optical vortex (OV) beams possess an additional degree of freedom, orbital angular momentum, the beams can be utilized to enhance signal modulation in optical communication technologies by mode division multiplexing and information encoding. In particular, tunable OV devices with wavelength adjustment and channel switching generate wide interest among researchers. This paper demonstrates tunable OV generator based on a grid‐patterned liquid crystal (GPLC) cell. The device, which is capable of producing an array of OV beams, offers an electrically controllable conversion between scalar vortices and vector vortices and controllable optical vortex density. In addition, the GPLC device is tunable to optimize its performance over a broad range of wavelengths.
Waveguiding and Lasing in 2D Organic Semiconductor Znq2
Authors: Lin Shenghuang , Li Tenghao , Yuan Jian , Liao Liangsheng , Tao Jin , Kan Ruifeng , Xu Xuhui , Bao Qiaoliang
Published: November 2020

Organic semiconductors have been proven as emerging platforms for exploring strong light–matter interactions and quantum optics so as to develop coherent and quantum photonic devices. Though there has been abundant research on organic semiconductors, lasing action is rarely reported in individual 2D organic semiconductor waveguides or nanocavities. Herein, a strong optical waveguiding phenomenon is observed not only in the individual 2D organic semiconductor Znq2 nanosheet with micrometer size area, but also in the interconnecting or neighboring Znq2 nanosheets. The optical propagation loss coefficient of the interconnecting Znq2 sheets is ≈800 dB cm−1. More importantly, the phenomenon of optically pumped lasing in 2D Znq2 nanosheets is demonstrated, as evidenced by a sudden increase in emission intensity at a threshold pump pulse fluence of 49.9 W cm−2 at 480 nm. As verified by numerical FDTD simulations, the Znq2 nanosheet constitutes a microcavity that supports whisper gallery mode, providing suffcient feedback for laser oscillations. Herein, the coexistence of low‐loss waveguiding and excellent lasing in 2D organic semiconductor nanosheets are revealed, which open up a new pathway for photonics and quantum optics based on 2D organic semiconductors.
Inorganic Nanomaterials for Photothermal‐Based Cancer Theranostics
Authors: Wen Huang , Tamarov Konstantin , Happonen Emilia , Lehto Vesa‐Pekka , Xu Wujun
Published: November 2020

Inorganic photothermal agents (PTAs) have attracted considerable attention in cancer theranostics due to their unique features such as high photothermal conversion efficacy, excellent photothermal stability, and straightforward functionalization. The first part of this Review summarizes progress in methods for synthesizing PTAs, then considers in vitro photothermal evaluations, as well as in vivo photothermal‐based applications that attempt to overcome different barriers in cancer theranostics. Next, a clinical trial with an inorganic PTA is described. The final part of the Review examines the challenges and possibilities for successful transfer of inorganic PTAs from the laboratory to the clinic.
Influence of soybean management decisions on the subsequent rice crop's response to nitrogen
Authors: Ortel Carrie C. , Roberts Trenton L. , Hoegenauer Kyle A. , Hardke Jarrod T.
Published: November 2020

Little is known about the effects of soybean [Glycine max (L.) Merr.] management practices on the success of the subsequent rice (Oryza sativa L.) crop. A study was initiated to determine how rice was affected by the preceding soybean crop's maturity group (MG) and planting date when grown in rotation on silt loam and clay soils. Optimum and late soybean planting dates and MGs (3.5, 4.7, 5.4, and 5.6) were followed by a rice crop. The results differed by soil texture, with the planting date and MG selection of the previous soybean crop more influential to the rice crop produced on a silt loam soil than a clay soil. Rice grown on a clay soil produced a higher grain yield when following a 5.4 MG soybean, whereas the planting date of a previous soybean crop influenced the soil‐N credits measured at rice emergence. On a silt loam soil, the interaction of both planting date and MG of the previous soybean crop influenced the maximal grain yield achieved by the rice crop. When soybean is planted during an optimum planting date, soybean MG has little effect on the successive rice crop. However, when the soybean crop is planted late, a determinate MG should be selected to achieve the highest rice crop total N uptake, maximal grain yield, and reduce the rate of fertilizer‐N needed to achieve 95% relative grain yield. Management techniques should be considered when implementing a soybean–rice rotation to maximize rice grain yield and overall farm profitability.
Dimer Organization of Membrane‐Associated NS5A of Hepatitis C Virus as Determined by Highly Sensitive 1H‐Detected Solid‐State NMR
Authors: Jirasko Vlastimil , Lends Alons , Lakomek Nils‐Alexander , Fogeron Marie‐Laure , Weber Marco E. , Malär Alexander A. , Penzel Susanne , Bartenschlager Ralf , Meier Beat H. , Böckmann Anja
Published: November 2020

The Hepatitis C virus nonstructural protein 5A (NS5A) is a membrane‐associated protein involved in multiple steps of the viral life cycle. Direct‐acting antivirals (DAAs) targeting NS5A are a cornerstone of antiviral therapy, but the mode‐of‐action of these drugs is poorly understood. This is due to the lack of information on the membrane‐bound NS5A structure. Herein, we present the structural model of an NS5A AH‐linker‐D1 protein reconstituted as proteoliposomes. We use highly sensitive proton‐detected solid‐state NMR methods suitable to study samples generated through synthetic biology approaches. Spectra analyses disclose that both the AH membrane anchor and the linker are highly flexible. Paramagnetic relaxation enhancements (PRE) reveal that the dimer organization in lipids requires a new type of NS5A self‐interaction not reflected in previous crystal structures. In conclusion, we provide the first characterization of NS5A AH‐linker‐D1 in a lipidic environment shedding light onto the mode‐of‐action of clinically used NS5A inhibitors.
Asymmetric Total Synthesis of Dankasterones A and B and Periconiastone A Through Radical Cyclization
Authors: Chen Pengquan , Wang Cheng , Yang Rui , Xu Hongjin , Wu Jinghua , Jiang Huanfeng , Chen Kai , Ma Zhiqiang
Published: November 2020

We describe herein the assembly of the cis‐decalin framework through radical cyclization initiated by metal‐catalyzed hydrogen atom transfer (MHAT), further applied it in the asymmetric synthesis of dankasterones A and B and periconiastone A. Position‐selective C−H oxygenation allowed for installation of the necessary functionality. A radical rearrangement was adopted to create 13(14→8)abeo‐8‐ergostane skeleton. Interconversion of dankasterone B and periconiastone A was realized through biomimetic intramolecular aldol and retro‐aldol reactions. The MHAT‐based approach, serves as a new dissection means, is complementary to the conventional ways to establish cis‐decalin framework.
α‐Cyclodextrin Encapsulation of Bicyclo[1.1.1]pentane Derivatives: A Storable Feedstock for Preparation of [1.1.1]Propellane
Authors: Matsunaga Tadafumi , Kanazawa Junichiro , Ichikawa Tomohiro , Harada Mei , Nishiyama Yusuke , Duong Nghia Tuan , Matsumoto Takashi , Miyamoto Kazunori , Uchiyama Masanobu
Published: November 2020

The bicyclo[1.1.1]pentane (BCP) scaffold is useful in medicinal chemistry, and many protocols are available for synthesizing BCP derivatives from [1.1.1]propellane. Here, we report (1) the α‐cyclodextrin (α‐CD) encapsulation of BCP derivatives, affording a stable, readily storable material from which BCPs can be easily and quantitatively recovered and (2) new and simple protocols for deiodination reaction of 1,3‐diiodo BCP to afford [1.1.1]propellane in protic/aprotic/polar/non‐polar solvents. The combination of these methodologies enables simple, on‐demand preparation of [1.1.1]propellane in various solvents under mild conditions from α‐CD capsules containing 1,3‐diiodo BCP.
Monitoring of whitening agent for skin analysis using tyrosinase gold nanoparticle‐based colorimetric assay
Authors: Siddiqui Mohd Farhan , Jeon Sojeong , Kim Moon‐Moo
Published: November 2020

Arbutin is a potential depigmenting agent that reduces melanin production by inhibiting tyrosinase activity and predicts the risk of whitening of the skin. Despite wide acceptance in routine laboratory tests, the conventional methods for whitening agent analysis have been of limited use because of high cost and lower signal sensitivity. Gold nanoparticles have gained considerable interest in improving the sensitivity and signals for the detection of proteins. Inspiring from these strategies, we have designed a tyrosinase enzyme gold nanoparticles (tyrosinase–AuNPs) method for the evaluation of arbutin with improved signals. The developed assay has been tested for tyrosine spiked samples to derive the standard graph. And then the performance of the assay is validated by testing arbutin on inhibiting tyrosinase activity. A detection limit of 13.70 μM with R2 of 0.982 is confirmed. Compared with the conventional method, the proposed assay represented the improved sensitivity, and signals are enhanced by five times that can be easily visualized through the naked eyes. Moreover, our method is beneficial because of the low cost and avoiding the need for expensive instruments. We believe that this method for arbutin evaluation will provide a foundation for the screening of other whitening agents, paving the way for future advances in the field of cosmetics.
Controllable synthesis of cellulose/methylene bisacrylamide aerogels for enhanced adsorption performance
Authors: Song Yibei , Zhou Shuang , Li He , Xie Fei , Yang Hui , Yuan Zhihao , Li Wenjiang
Published: November 2020

Cellulose‐based aerogels have been regarded as potential adsorbent materials because of their unique structural features and chemical stability. Herein, we prepared the composite aerogels containing cellulose and N,N′‐methylene bisacrylamide (MBA) using N‐methylmorpholine‐N‐oxide (NMMO) as a green solvent via a freeze‐drying process. Owing to the strong chemical interaction between CC bonds of MBA and the functional groups of cellulose, as‐obtained cellulose/MBA aerogels present favorable MBA‐induced thermal/mechanical stable three‐dimensional network structure, in which the abundant macroporous structure, low density and high porosity lead to a significantly enhanced adsorption capacity (260.31 mg∙g−1) toward congo red dye in aqueous solution compared with the pure cellulose aerogels. Moreover, the effect of the cellulose concentration and cross‐linking degree on the morphology and adsorption properties for cellulose/MBA aerogels was systematically investigated. This present work provides a low‐cost and environmental‐friendly synthesis method for designing the functionalization of cellulose‐based aerogel, which may be achieved the advanced performance in wastewater treatment.
High‐refractive index polythiourethane resin based on 2,3‐bis((2‐mercaptoethyl) thio)‐1‐propanethiol and 1,3‐bis(isocyanantomethyl) cyclohexane using tertiary amine catalyst
Authors: Zhang Youwei , Wang Yansong , Chen Yuanyu , Yang Zhao , Chen Mingyue , Qin Zongyi
Published: November 2020

High‐refractive index (RI) polythiourethane (PTU) resin with good thermal, optical, and mechanical properties was synthesized via thiol‐isocynanate click reaction of 2,3‐bis((2‐mercaptoethyl)thio)‐1‐propanethiol and 1,3‐bis(isocyanantomethyl) cyclohexane using a new tertiary amine catalyst N,N,N′,N′‐tetramethyl‐1,4‐diaminobutane (TMDB). Curing behavior of PTU resin was studied by dynamic differential scanning calorimetry (DSC) technique. Curing technology parameters were optimized by combined use of DSC and fourier transform infrared spectrometry (FTIR). The results indicate that TMDB exhibits higher catalytic activity than commonly used dibutyltin dichloride (DBTC). The Kissinger apparent activation energies at a dosage of 150 ppm TMDB and 150 ppm DBTC are 31.7 and 43.2 kJ mol−1, respectively. PTU resin with a full conversion of thiol and isocynanate was prepared, which exhibited better thermal, optical, and mechanical properties than that reported previously. The resin displays a glass transition temperature of 102 and 129°C determined by DSC and dynamic thermomechanical analysis (DMA), respectively, a 5% weight loss temperature of 279°C in nitrogen, a light transmittance of 87% in the wavelength range of 410–900 nm, a water contact angle of 100°, a high‐RI of 1.617, and an Abbe number of 38. The resin was successfully applied in ophthalmic lenses.
Non‐xenogeneic expansion and definitive endoderm differentiation of human pluripotent stem cells in an automated bioreactor
Authors: Jacobson Elena F. , Chen Zijing , Stoukides Demetrios M. , Nair Gopika G. , Hebrok Matthias , Tzanakakis Emmanuel S.
Published: November 2020

Scalable processes are requisite for the robust biomanufacturing of human pluripotent stem cell (hPSC)‐derived therapeutics. Toward this end, we demonstrate the xeno‐free expansion and directed differentiation of human embryonic and induced pluripotent stem cells to definitive endoderm (DE) in a controlled stirred suspension bioreactor (SSB). Based on previous work on converting hPSCs to insulin‐producing progeny, differentiation of two hPSC lines was optimized in planar cultures yielding up to 87% FOXA2+/SOX17+ cells. Next, hPSCs were propagated in an SSB with controlled pH and dissolved oxygen. Cultures displayed a 10‐ to 12‐fold increase in cell number over 5–6 days with the maintenance of pluripotency (>85% OCT4+) and viability (>85%). For differentiation, SSB cultures yielded up to 89% FOXA2+/SOX17+ cells or ~ 8 DE cells per seeded hPSC. Specification to DE cell fate was consistently more efficient in the bioreactor compared to planar cultures. Hence, a tunable strategy is established that is suitable for the xeno‐free manufacturing of DE cells from different hPSC lines in scalable SSBs. This study advances bioprocess development for producing a wide gamut of human DE cell‐derived therapeutics.
Discovery and Engineering of a Novel Baeyer‐Villiger Monooxygenase with High Normal Regioselectivity
Authors: Zhang Guang‐Xiang , You Zhi‐Neng , Yu Jia‐Mei , Liu Yuan‐Yang , Pan Jiang , Xu Jian‐He , Li Chun‐Xiu
Published: November 2020

Baeyer‐Villiger monooxygenases (BVMOs) are remarkable biocatalysts for the Baeyer‐Villiger oxidation of ketones to generate esters or lactones. The regioselectivity of BVMOs is essential for determining the ratio of the two regioisomeric products (“normal” and “abnormal”) when catalyzing asymmetric ketone substrates. Starting from a known normal‐preferring BVMO sequence from Pseudomonas putida KT2440 (PpBVMO), a novel BVMO from Gordonia sihwensis (GsBVMO) with higher normal regioselectivity (up to 97/3) was identified. Furthermore, protein engineering increased the specificity constant (kcat/KM) 8.9‐fold to 484 s−1 mM−1 for 10‐ketostearic acid derived from oleic acid. Consequently, by using the variant GsBVMOC308L as an efficient biocatalyst, 10‐ketostearic acid was efficiently transformed into 9‐(nonanoyloxy)nonanoic acid, with a space‐time yield of 60.5 g L−1 d−1. This study showed that the mutant with higher regioselectivity and catalytic efficiency could be applied to prepare medium‐chain ω‐hydroxy fatty acids through biotransformation of long‐chain aliphatic keto acids derived from renewable plant oils.
Morpholine‐Substituted Rhodamine Analogue with Multi‐Configurational Switches for Optical Sensing of pH Gradient under Extreme Acidic Environments
Authors: Koga Natsumi , Tanioka Masaru , Kamino Shinichiro , Sawada Daisuke
Published: November 2020

Superior pH‐responsive molecules are required for the development of functional materials applicable to advanced molecular technologies. Despite having been widely developed, many rhodamine‐based pH‐responsive molecules exhibit a single configurational switch for “turn‐on”. Herein, we report a new type of rhodamine‐based pH‐responsive molecule with multi‐configurational switches displaying stable two‐step structural and color conversion in response to pH. This rhodamine analogue could be successfully applied to optical sensing of pH gradient under extreme acidic environments both in solution and on hydrogel through high‐contrast color change. We demonstrated that this multi‐responsive character enabled optical memory of different pH information.
Reversible Speed Regulation of Self‐Propelled Janus Micromotors via Thermoresponsive Bottle‐Brush Polymers
Authors: Fiedler Christine , Ulbricht Christoph , Truglas Tia , Wielend Dominik , Bednorz Mateusz , Groiss Heiko , Brüggemann Oliver , Teasdale Ian , Salinas Yolanda
Published: November 2020

This work reports a reversible braking system for micromotors that can be controlled by small temperature changes (≈5 °C). To achieve this, gated‐mesoporous organosilica microparticles are internally loaded with metal catalysts (to form the motor) and the exterior (partially) grafted with thermosensitive bottle‐brush polyphosphazenes to form Janus particles. When placed in an aqueous solution of H2O2 (the fuel), rapid forward propulsion of the motors ensues due to decomposition of the fuel. Conformational changes of the polymers at defined temperatures regulate the bubble formation rate and thus act as brakes with considerable deceleration/acceleration observed. As the components can be easily varied, this represents a versatile, modular platform for the exogenous velocity control of micromotors.
The effect of left atrial remodeling after cryoballoon ablation and radiofrequency ablation for paroxysmal atrial fibrillation
Authors: Wang Xule , Song Beibei , Qiu Chunguang , Han Zhanying , Wang Xi , Lu Wenjie , Chen Xiaojie , Chen Yingwei , Pan Liang , Sun Guoju , Qin Xiaofei , Li Ran
Published: November 2020

Background

Cryoballoon ablation (CBA) and radiofrequency ablation (RFA) are the most common procedures used to treat refractory atrial fibrillation (AF) and are performed through pulmonary vein isolation (PVI). Studies have shown that CBA can approximately match the therapeutic effects of RFA against AF. However, few studies have investigated the difference between CBA and RFA of the effects on left atrial remodeling for paroxysmal AF.

Objective

Atrial remodeling is considered pivotal to the occurrence and development of AF, therefore we sought to assess the influence of atrial remodeling in patients with paroxysmal AF after CBA and RFA in this study.

Methods

In this nonrandomized retrospective observational study, we enrolled 328 consecutive patients who underwent CBA or RFA for refractory paroxysmal AF in May 2014 to May 2017 in our hospital. After propensity score matching, 96 patients were included in the CBA group, and 96 were included in the RFA group. Patients were asked to undergo a 12‐lead electrocardiogram, a 24‐h Holter monitor, and an echocardiogram and to provide their clinical history and symptoms at 6 months and 1, 2, and 3 years postprocedurally. Electrical remodeling of the left atrium was assessed by P wave dispersion (Pdis); structural remodeling was assessed by the left atrium diameter (LAD) and left atrial volume index (LAVI) during scheduled visits.

Results

As of January 2020, compared with baseline, at 1 year, 2 years, and 3 years after ablation, the average changes in Pdis (∆Pdis), LAD (∆LAD), and LAVI (∆LAVI) were significant in both the CBA and RFA groups. Six months after ablation, ∆Pdis, ∆LAD, and ∆LAVI were greater in the CBA group than in the RFA group. There was no significant difference between the two groups in AF/flutter recurrence, but the AF/flutter‐free survival time of CBA group may be longer than RFA group after 2 years after ablation. A higher ∆Pdis, ∆LAD, or ∆LAVI at 1 year after ablation may increase AF/flutter‐free survival.

Conclusions

Although CBA and RFA are both effective in left atrial electrical and structural reverse‐remodeling in paroxysmal AF, CBA may outperform RFA for both purposes 6 months after ablation. However, during long‐term follow‐up, there was no significant intergroup difference.