Research Progress on Circular RNA in Glioma

The discovery of circular RNA (circRNA) greatly complements the traditional gene expression theory. CircRNA is a class of non-coding RNA with a stable cyclic structure. They are highly expressed, spatiotemporal-specific and conservative across species. Importantly, circRNA participates in the occurrence of many kinds of tumors and regulates the tumor development. Glioma is featured by limited therapy and grim prognosis. Cancer-associated circRNA compromises original function or creates new effects in glioma, thus contributing to oncogenesis. Therefore, this article reviews the biogenesis, metabolism, functions and properties of circRNA as a novel potential biomarker for gliomas. We elaborate the expression characteristics, interaction between circRNA and other molecules, aiming to identify new targets for early diagnosis and treatment of gliomas.

[2.2.2.2]Paracyclophanetetraenes (PCTs): cyclic structural analogues of poly(p‑phenylene vinylene)s (PPVs)

Background: Poly(p-phenylene vinylene)s (PPVs) and [2.2.2.2]paracyclophanetetraene (PCT) are both composed of alternating π-conjugated para-phenylene and vinylene units. However, while the former constitute a class of π-conjugated polymers that has been used in organic electronics for decades, the latter is a macrocycle that only recently revealed its potential for applications such as organic battery electrodes. The cyclic structure endows PCT with unusual properties, and further tuning of these may be required for specific applications. Methods: In this article, we adopt an approach often used for tuning the properties of PPVs, the introduction of alkoxy (or alkylthio) substituents at the phenylene units, for tuning the optoelectronic properties of PCT. The resulting methoxy- and methylthio-substituted PCTs, obtained by Wittig cyclisation reactions, are studied by UV-vis absorption, photoluminescence, and cyclic voltammetry measurements, and investigated computationally using the visualisation of chemical shielding tensors (VIST) method. Results: The measurements show that substitution leads to slight changes in terms of absorption/emission energies and redox potentials while having a pronounced effect on the photoluminescence intensity. The computations show the effect of the substituents on the ring currents and chemical shielding and on the associated local and global (anti)aromaticity of the macrocycles, highlighting the interplay of local and global aromaticity in various electronic states. Conclusions: The study offers interesting insights into the tuneability of the properties of this versatile class of π-conjugated macrocycles.

Two Public-Key Cryptosystems Based on Expanded Gabidulin Codes

This paper presents two public-key cryptosystems based on the so-called expanded Gabidulin codes, which are constructed by expanding Gabidulin codes over the base field. Exploiting the fast decoder of Gabidulin codes, we propose an efficient algorithm to decode these new codes when the noise vector satisfies a certain condition. Additionally, these new codes have an excellent error-correcting capability because of the optimality of their parent Gabidulin codes. Based on different masking techniques, we give two encryption schemes by using expanded Gabidulin codes in the McEliece setting. According to our analysis, these two cryptosystems can both resist the existing structural attacks. Furthermore, our proposals also have an obvious advantage in public-key representation without using the cyclic or quasi-cyclic structure compared to some other code-based cryptosystems. To achieve the security of 256 bits, for instance, a public-key size of 37005 bytes is enough for our first proposal, while around 1044992 bytes are needed for Classic McEliece selected as a candidate of the third round of the NIST PQC project.

Discourse Strategies and Narrative Repetition in the Qurʾān: A Special Reference to al-Shuʿarāʾ

This paper attempts to explain some discursive strategies in relation to the cyclic structure of narratives in the Qurʾānic context of Sūrat “al-Shuʿarāʾ.” To that end, the paper works on three essential interrelated aspects of study. First, it detects the cyclic structure that interconnects the seven prophets’ narratives within the Sūrah. Second, it investigates the cross-Sūrah interconnections by examining the (re)occurrence of each prophet’s narrative in the preceding and following sūrahs. Third, it discusses how such coherent interrelationships among the relevant sūrahs can reveal certain discourse strategies such as narrative extension, intention, expansion, juxtaposition, and inversion among these sūrahs. Another, yet interrelated, aspect of the study is to explain the “Us/Them” distinction counted in the Qurʾānic narratives involved, and to show how such dichotomy is realized through the use of referential and predicational strategies. The study adopts and adapts Reisigl and Wodak’s strategies to address this aspect. Within this analytical approach, the narratives are examined on the basis of two strategies; namely, “despatialization” (actionyms, perceptionyms, anthroponyms, and metaphors of spatiality) and “collectivization” (pronouns and possessive determiners). The analysis of data reveals some striking findings that can be summarized in two major points: first, each of the narrative’s topoi in the social actors representation evinces the dominance of predicational strategies; second, the Qurʾānic discourse is bias-free and is, thereby, drastically distinguished from other types of discourse such as political discourse.

Impact of Mistuned Underplatform Dampers On the Nonlinear Vibration of Bladed Disks

Before the final experimental validation and certification of a turboengine, designers perform a numerical simulation of its vibratory properties, among other things, in order to estimate its lifespan and adjust the design in an optimization process. One possible practical solution to decrease the vibratory response is to add underplatform dampers to the system. These components dissipate energy by friction and are widely employed in turbomachinery. However, a specific underplatform damper is usually efficient only for a specific mode. The purpose of this work is to investigate the possibility of adding different kinds of underplatform dampers to the cyclic structure in order to decrease the vibratory energy over a larger panel of modes. Different methods exist to determine the vibrations of nonlinear cyclic symmetric systems, but creating a robust methodology to account for the additional effect of mistuning remains a big challenge in the community. In this paper, the structure is mistuned through the friction coefficient of the dampers and not by altering its geometry, as is usually done in the literature. First, assuming a cyclic symmetric structure, the performance of the dampers is assessed for specific modes. Then, employing a method recently developed, the efficiency of an intentional mistuning pattern of underplatform dampers is studied and an optimal pattern proposed.

Impact of Mistuned Underplatform Dampers on the Nonlinear Vibration of Bladed Disks

Before the final experimental validation and certification of a turboengine, designers perform a numerical simulation of its vibratory properties, among other things, in order to estimate its lifespan and adjust the design in an optimization process. One possible practical solution to decrease the vibratory response is to add underplatform dampers to the system. These components dissipate energy by friction and are widely employed in turbomachinery. However, a specific underplatform damper is usually efficient only for a specific mode. The purpose of this work is to investigate the possibility of adding different kinds of underplatform dampers to the cyclic structure in order to decrease the vibratory energy over a larger panel of modes. Different methods exist to determine the vibrations of nonlinear cyclic symmetric systems, but creating a robust methodology to account for the additional effect of mistuning remains a big challenge in the community. In this paper, the structure is mistuned through the friction coefficient of the dampers and not by altering its geometry, as is usually done in the literature. First, assuming a cyclic symmetric structure, the performance of the dampers is assessed for specific modes. Then, employing a method recently developed, the efficiency of an intentional mistuning pattern of underplatform dampers is studied and an optimal pattern proposed.

LIQUID-PHASE HYDROGENATION OF CYCLOPENTADIENE ON MODIFIED SKELETAL NICKEL CATALYSTS

This paper presents the results of a study on the hydrogenation of cyclopentadiene on modified skeletal nickel catalysts. It is shown that the activity of multicomponent skeletal nickel catalysts in the hydrogenation of cyclopentadiene is largely due to the nature of the additives introduced into the initial alloy. The introduction of Cu, Pb, Ta, Zn, Mo-Cu, Bi and Mo into the alloy leads to an increase in the activity (W = 14-280 cm3/min g Ni) and selectivity (Ks = 0.93-0.99) of cyclopentadiene hydrogenation, additions of Cr, Ti, Sn and Cr-Cu have no significant effect. As a result, when cyclopentadiene is hydrogenated, an intermediate alkene, cyclopentene, is formed. This is due to the cyclic structure of cyclopentadiene, which causes the formation of identical cycloalkene molecules when hydrogen is added to any position. The saturation of cyclopentadiene is completely completed upon absorption of 1 mole of hydrogen, and cyclopentene can be obtained in high yield.

Accelerated polymerization of N-carboxyanhydrides catalyzed by crown ether

The recent advances in accelerated polymerization of N-carboxyanhydrides (NCAs) enriched the toolbox to prepare well-defined polypeptide materials. Herein we report the use of crown ether (CE) to catalyze the polymerization of NCA initiated by conventional primary amine initiators in solvents with low polarity and low hydrogen-bonding ability. The cyclic structure of the CE played a crucial role in the catalysis, with 18-crown-6 enabling the fastest polymerization kinetics. The fast polymerization kinetics outpaced common side reactions, enabling the preparation of well-defined polypeptides using an α-helical macroinitiator. Experimental results as well as the simulation methods suggested that CE changed the binding geometry between NCA and propagating amino chain-end, which promoted the molecular interactions and lowered the activation energy for ring-opening reactions of NCAs. This work not only provides an efficient strategy to prepare well-defined polypeptides with functionalized C-termini, but also guides the design of catalysts for NCA polymerization.