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1. Rheological Investigation of Pre-Crosslinked Hybrid Hydrogels for 3D Bio-printing Processes.

   Tuladhar, Slesha; Nelson, Cartwright; Habib, Ahasan (May 2022, Proceedings for IISE Annual Conference & Expo 2022)

   Ellis, K; Ferrell, W; Knapp, J. (Ed.)

   Despite being a very popular topic and researched by several scientists, the entire 3D bioprinting process is still subjected to several challenges like geometric fidelity, mechanical complexities, cell viability, and proliferation. Rheological investigations along with the proper design of experiments help to explore the physical and mechanical properties of biomaterials and 3D printed scaffolds that are directly associated with their geometric fidelity. To ensure post-printed structural integrity, viscosity thickeners and crosslinkers were used in this research. Mixtures of Carboxymethyl Cellulose (CMC, viscosity enhancer), Alginate, and CaCl2 and CaSO4 (crosslinkers) were prepared at various concentrations maintaining minimum solid content. For each composition, a set of rheological tests was performed in form of flow, thixotropic, amplitude, and frequency tests. This research presents an overview of controlling the rheological properties of various bio-inks that are viscosity enhancer and pre-crosslinkers dependent, which opens doors to looking at 3D bioprinting in a very different way. 

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2. On Functional Processes with Multiple Discontinuities

   https://doi.org/10.1111/rssb.12493  

   Li, Jialiang; Li, Yaguang; Hsing, Tailen (March 2022, Journal of the Royal Statistical Society Series B: Statistical Methodology)

   Abstract We consider the problem of estimating multiple change points for a functional data process. There are numerous examples in science and finance in which the process of interest may be subject to some sudden changes in the mean. The process data that are not in a close vicinity of any change point can be analysed by the usual nonparametric smoothing methods. However, the data close to change points and contain the most pertinent information of structural breaks need to be handled with special care. This paper considers a half-kernel approach that addresses the inference of the total number, locations and jump sizes of the changes. Convergence rates and asymptotic distributional results for the proposed procedures are thoroughly investigated. Simulations are conducted to examine the performance of the approach, and a number of real data sets are analysed to provide an illustration. 

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3. Network Properties of Electrically Coupled Bursting Pituitary Cells

   https://doi.org/10.3389/fendo.2022.936160  

   Fazli, Mehran; Bertram, Richard (July 2022, Frontiers in Endocrinology)

   The endocrine cells of the anterior pituitary gland are electrically active when stimulated or, in some cases, when not inhibited. The activity pattern thought to be most effective in releasing hormones is bursting, which consists of depolarization with small spikes that are much longer than single spikes. Although a majority of the research on cellular activity patterns has been performed on dispersed cells, the environment in situ is characterized by networks of coupled cells of the same type, at least in the case of somatotrophs and lactotrophs. This produces some degree of synchronization of their activity, which can be greatly increased by hormones and changes in the physiological state. In this computational study, we examine how electrical coupling among model cells influences synchronization of bursting oscillations among the population. We focus primarily on weak electrical coupling, since strong coupling leads to complete synchronization that is not characteristic of pituitary cell networks. We first look at small networks to point out several unexpected behaviors of the coupled system, and then consider a larger random scale-free network to determine what features of the structural network formed through gap junctional coupling among cells produce a high degree of functional coupling, i.e., clusters of synchronized cells. We employ several network centrality measures, and find that cells that are closely related in terms of their closeness centrality are most likely to be synchronized. We also find that structural hubs (cells with extensive coupling to other cells) are typically not functional hubs (cells synchronized with many other cells). Overall, in the case of weak electrical coupling, it is hard to predict the functional network that arises from a structural network, or to use a functional network as a means for determining the structural network that gives rise to it. 

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4. Structural analysis of MALAT1 long noncoding RNA in cells and in evolution

   https://doi.org/10.1261/rna.079388.122  

   Monroy-Eklund, Anais; Taylor, Colin; Weidmann, Chase A.; Burch, Christina L.; Laederach, Alain (April 2023, RNA)

   Although not canonically polyadenylated, the long noncoding RNA MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) is stabilized by a highly conserved 76-nt triple helix structure on its 3′ end. The entire MALAT1 transcript is over 8000 nt long in humans. The strongest structural conservation signal in MALAT1 (as measured by covariation of base pairs) is in the triple helix structure. Primary sequence analysis of covariation alone does not reveal the degree of structural conservation of the entire full-length transcript, however. Furthermore, RNA structure is often context dependent; RNA binding proteins that are differentially expressed in different cell types may alter structure. We investigate here the in-cell and cell-free structures of the full-length human and green monkey (Chlorocebus sabaeus) MALAT1 transcripts in multiple tissue-derived cell lines using SHAPE chemical probing. Our data reveal levels of uniform structural conservation in different cell lines, in cells and cell-free, and even between species, despite significant differences in primary sequence. The uniformity of the structural conservation across the entire transcript suggests that, despite seeing covariation signals only in the triple helix junction of the lncRNA, the rest of the transcript's structure is remarkably conserved, at least in primates and across multiple cell types and conditions. 

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5. Existence results for fractional order functional differential equations with infinite delay in the sense of the deformable derivative

   Etefa, Mesfin; N'guérékata, Gaston M. (January 2022, Analele Universităţii din Oradea Fascicula Matematică)

   In this article, we discuss the existence and uniqueness of solutions for initial value problems of fractional order functional and neutral functional differential equations with infinite delay. We use the deformable derivative introduced in 2017 by Zulfeqarr et. al (see [21]). Our results are obtained using the Banach fixed point theorem and the nonlinear alternative Leray-Schauder type theorem. We provide an example as an illustration of the main results. 

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