Space–time transformation acoustics

A recently proposed analogue transformation method has allowed the extension of transformation acoustics to general space–time transformations. We analyze here in detail the differences between this new analogue transformation acoustics (ATA) method and the standard one (STA). We show explicitly that STA is not suitable for transformations that mix space and time. ATA takes as starting point the acoustic equation for the velocity potential, instead of that for the pressure as in STA. This velocity-potential equation by itself already allows for some transformations mixing space and time, but not all of them. We explicitly obtain the entire set of transformations that leave its form invariant. It is for the rest of transformations that ATA shows its true potential, allowing for building a transformation acoustics method that enables the full range of space–time transformations. We provide an example of an important transformation which cannot be achieved with STA. Using this transformation, we design and simulate an acoustic frequency converter via the ATA approach. Furthermore, in those cases in which one can apply both the STA and ATA approaches, we study the different transformational properties of the corresponding physical quantities.     

Synthesis and cytotoxicity evaluation of a novel justicidin G analogue and its phosphate ester

The novel justicidin G analogue 13 and its phosphate ester 15 were synthesized as potential anticancer agents in several steps starting from commercially available methyl gallate and veratraldehyde. The cytotoxicity of the intermediates was tested against HCT-8, BEL-7402, KETR3, HELA, BGC-823, KB and MCF-7 cell lines by the MTT test, and compound 15 exhibited significant cytotoxicity in HELA and KB cell lines.     

Design of millimeter-wave fiber-wireless downlink with remote local-oscillator delivery by using dual-electrode Mach-Zehnder modulators configured for optical single-sideband modulations

An optical fiber-wireless system operating in millimeter-wave (MMW) bands may include numerous optical remote access points (RAPs) of which the cost is critical to implement such systems in real market. In this paper, we design an optical fiber communication system for MMW optical fiber downlink transmission with remote MMW local-oscillator (LO) delivery for intermediate frequency (IF) fiber uplink transmission. The new design is based on two dual-electrode Mach-Zehnder modulators in parallel both configured for optical single-sideband modulations. By using the proposed design, a conventional RAP can be simplified in structure to reduce the cost. Our numerical results show that, with the proposed design, 1-Gbit/s binary-phase-shift-keying (BPSK) data at a 42-GHz sub-carrier frequency can be transmitted over a 20-km standard single-mode optical fiber followed by a wireless transmission of several kilometers. Moreover, a MMW LO at 37-GHz frequency can be remotely delivered over tens of kilometers of a standard single-mode fiber with acceptable deterioration in the LO phase noise for IF uplink fiber transmission.     

Application of copper(II)-mediated radical cross-dehydrogenative coupling to prepare spirocyclic oxindoles and to a formal total synthesis of Satavaptan

Application of radical cross-dehydrogenative coupling (CDC) procedures to prepare a range of novel spirocyclic oxindoles and to a formal total synthesis of the vasopressin V₂ receptor antagonist Satavaptan is reported. The key step involves a copper-mediated oxidative cyclisation of a simple linear anilide precursor to give the spirocyclic oxindole core. This synthetic approach was also used to prepare novel Satavaptan scaffolds and analogues.     

“Pore-Hopping” Ion Transport in Cellulose-Based Separator Towards High-Performance Sodium-Ion Batteries

Sodium-ion batteries (SIBs) have great potential for large-scale energy storage. Cellulose is an attractive material for sustainable separators, but some key issues still exist affecting its application. Herein, a cellulose-based composite separator (CP@PPC) was prepared by immersion curing of cellulose-based separators (CP) with poly(propylene carbonate) (PPC). With the assistance of PPC, the CP@PPC separator is able to operate the cell stably at high voltages (up to 4.95 V). The “pore-hopping” ion transport mechanism in CP@PPC opens up extra Na⁺ migration paths, resulting in a high Na⁺ transference number (0.613). The separator can also tolerate folding, bending and extreme temperature under certain circumstances. Full cells with CP@PPC reveal one-up capacity retention (96.97 %) at 2C after 500 cycles compared to cells with CP. The mechanism highlights the merits of electrolyte analogs in separator modification, making a rational design for durable devices in advanced energy storage systems.     

罂粟花粉十三肽类似物的合成及其结构与抗肿瘤活性关系研究

罂粟花粉十三肽对人肝癌和人乳腺癌肿瘤细胞具有明显的抑制作用,以其为先导化合物,设计并合成了5个类似物和5个片段,结合CD谱测定的二级结构及它们对人肝癌和人乳腺癌肿瘤细胞的抑制作用测定结果,研究并讨论了该肽结构与抗肿瘤活性的关系.     

微管菌素类似物的合成及抗肿瘤活性

以微管菌素为先导化合物, 设计合成了一系列类似物; 所有化合物的结构均经¹H NMR, ¹³C NMR及HRMS确证, 均为新化合物. 采用噻唑蓝(MTT)法对其抗肿瘤活性进行了初步筛选, 结果表明, 化合物Ⅱb具有一定的抗肿瘤活性.     

新型异烟酸类蚜虫报警信息素类似物的设计、合成及生物活性

以蚜虫报警信息素[(E)-β-farnesene,EBF]为先导,通过活性亚结构拼接和生物电子等排原理,设计合成了一系列结构新颖的异烟酸类EBF类似物.以香叶醇为原料,经4步反应制得20个目标化合物(19个未见文献报道),其结构经~1H NMR,~(13)C NMR,IR及HRMS确证.初步生物活性测定结果表明,所有化合物对桃蚜有驱避活性和杀死活性,其中化合物7d,8f和8n表现出较好的桃蚜驱避活性,对桃蚜的驱避率分别为62.6%,62.0%和61.0%;化合物8a,8b和8d对桃蚜的致死率分别为73.6%,81.1%和70.2%.初步构效关系分析发现,酯基的引入对桃蚜的驱避活性有利;酰胺基的引入对杀蚜活性有利;N烷基取代的链长及支链数量影响驱避活性.     

Analogue transformation acoustics and the compression of spacetime

A recently developed technique known as analogue transformation acoustics has allowed the extension of the transformational paradigm to general spacetime transformations under which the acoustic equations are not form invariant. In this paper, we review the fundamentals of analogue transformation acoustics and show how this technique can be applied to build a device that increases the density of events within a given spacetime region by simultaneously compressing space and time.