Electronic properties and topological phases in graphene-based van der waals heterostructures

Master'sMASTER OF SCIENC

The circadian rhythms regulated by Cx43-signaling in the pathogenesis of Neuromyelitis Optica

IntroductionNeuromyelitis Optica (NMO) is an inflammatory demyelinating disease of the central nervous system (CNS). NMO manifests as selective and severe attacks on axons and myelin of the optic nerve and spinal cord, resulting in necrotic cavities. The circadian rhythms are well demonstrated to profoundly impact cellular function, behavior, and disease. This study is aimed to explore the role and molecular basis of circadian rhythms in NMO.MethodsWe used an Aquaporin 4(AQP4) IgG-induced NMO cell model in isolated astrocytes. The expression of Cx43 and Bmal1 were detected by real-time PCR and Western Blot. TAT-Gap19 and DQP-1105 were used to inhibit Cx43 and glutamate receptor respectively. The knockdown of Bmal1 were performed with the shRNA containing adenovirus. The levels of glutamate, anterior visual pathway (AVP), and vasoactive intestinal peptide (VIP) were quantified by ELISA kits.ResultsWe found that Bmal1 and Clock, two essential components of the circadian clock, were significantly decreased in NMO astrocytes, which were reversed by Cx43 activation (linoleic acid) or glutamate. Moreover, the expression levels of Bmal1 and Clock were also decreased by Cx43 blockade (TAT-Gap19) or glutamate receptor inhibition (DQP-1105). Furthermore, adenovirus-mediated Bmal1 knockdown by shRNA (Ad-sh-Bmal1) dramatically decreased the levels of glutamate, AVP, and VIP from neurons, and significantly down-regulated the protein level of Cx43 in NMO astrocytes with Cx43 activation (linoleic acid) or glutamate treatment. However, Bmal1 knockdown did not alter these levels in normal astrocytes with Cx43 blockade (TAT-Gap19) or glutamate receptor inhibition (DQP-1105).DiscussionCollectively, these results suggest that Cx43-glutamate signaling would be a critical upstream regulator that contributes to the NMO-induced rhythmic damage in SCN astrocytes

Formation, influencing factors, and applications of internal channels in starch: A review

Starch, a natural polymer, has a complex internal structure. Some starches, such as corn and wheat starches, have well-developed surface pores and internal channels. These channel structures are considered crucial in connecting surface stomata and internal cavities and have adequate space for loading guest molecules. After processing or modification, the starch-containing channel structures can be used for food and drug encapsulation and delivery. This article reviews the formation and determination of starch internal channels, and the influence of different factors (such as starch species and processing conditions) on the channel structure. It also discusses relevant starch preparation methods (physical, chemical, enzymatic, and synergistic), and the encapsulation effect of starch containing internal channels on different substances. In addition, the role of internal channels in regulating the starch digestion rate and other aspects is also discussed here. This review highlights the significant multifunctional applications of starch with a channel structure

Identification and transcriptome analysis of the R2R3-MYB gene family in Haloxylon ammodendron

The MYB transcription factor family is widespread in plants and plays an important role in plant growth and development as well as in plant responses to stress. The MYB transcription factor family has been identified in a variety of organisms; however, it has not been identified and analysed in the desert plant Haloxylon ammodendron. In this study, R2R3-MYB genes were identified and analysed using a bioinformatic approach. A total of 78 R2R3-MYB genes were identified and named according to their position on the chromosome. The R2R3-MYB genes were unevenly distributed on nine chromosomes. Phylogenetic analysis showed that the HaMYB genes were all divided into 31 subfamilies. Covariance analysis revealed the presence of three pairs of fragmentary duplicated genes in H. ammodendron (HaMYB54 and HaMYB17, HaMYB44 and HaMYB36, HaMYB42 and HaMYB27). Gene structure and conserved structural domain analysis revealed different subgroups with different orders of magnitude of variation in gene structures and conserved structural domains. Analysis of cis-elements showed that the cis-acting elements of HaMYBs were mainly associated with hormone and abiotic stress responses. Real-time quantitative PCR was used to detect the expression levels of HaR2R3-MYB genes, and six HaR2R3-MYB genes were found to respond to salt stress and six HaR2R3-MYB genes to drought stress, with HaMYB22 and HaMYB27 showing upregulated expression under both stresses. Transcriptome analysis showed that HaMYB63 was significantly differentially expressed in the assimilated branches of H. ammodendron, and the subcellular localization of this protein showed that it was located in the nucleus and had transcriptional self-activating activity. These results provide a theoretical basis for further studies on the functions of the R2R3-MYB gene family and the molecular mechanisms of resistance in H. ammodendron

Phenol-Catalyzed Discharge in the Aprotic Lithium-Oxygen Battery

Discharge in the lithium‐O2 battery is known to occur either by a solution mechanism, which enables high capacity and rates, or a surface mechanism, which passivates the electrode surface and limits performance. The development of strategies to promote solution‐phase discharge in stable electrolyte solutions is a central challenge for development of the lithium‐O2 battery. Here we show that the introduction of the protic additive phenol to ethers can promote a solution‐phase discharge mechanism. Phenol acts as a phase‐transfer catalyst, dissolving the product Li2O2, avoiding electrode passivation and forming large particles of Li2O2 product—vital requirements for high performance. As a result, we demonstrate capacities of over 9 mAh cm−2areal, which is a 35‐fold increase in capacity compared to without phenol. We show that the critical requirement is the strength of the conjugate base such that an equilibrium exists between protonation of the base and protonation of Li2O2

Membrane anchoring stabilizes and favors secretion of New Delhi metallo-β-lactamase

Carbapenems, 'last-resort' β-lactam antibiotics, are inactivated by zinc-dependent metallo-β-lactamases (MBLs). The host innate immune response withholds nutrient metal ions from microbial pathogens by releasing metal-chelating proteins such as calprotectin. We show that metal sequestration is detrimental for the accumulation of MBLs in the bacterial periplasm, because those enzymes are readily degraded in their nonmetallated form. However, the New Delhi metallo-β-lactamase (NDM-1) can persist under conditions of metal depletion. NDM-1 is a lipidated protein that anchors to the outer membrane of Gram-negative bacteria. Membrane anchoring contributes to the unusual stability of NDM-1 and favors secretion of this enzyme in outer-membrane vesicles (OMVs). OMVs containing NDM-1 can protect nearby populations of bacteria from otherwise lethal antibiotic levels, and OMVs from clinical pathogens expressing NDM-1 can carry this MBL and the bla[subscript NDM] gene. We show that protein export into OMVs can be targeted, providing possibilities of new antibacterial therapeutic strategies.Kinship Foundation. Searle Scholars ProgramMassachusetts Institute of Technology. Department of Chemistr

Athenoxat-1, Night Vision Experiments in LEO

On 16th December 2015 Athenoxat-1 was launched by a PSLV from India in to Equatorial Orbit. Athenoxat-1 has been developed by Microspace Rapid Pte Ltd to demonstrate the feasibility of night vision imaging on a 3U Cubesat. The night vision payload is based on a high sensitive CCD and, in combination with the large optical aperture allows for very fast imaging of Earth surface in the night with 25m resolution. In addition to the main payload, Athenoxat-1 is equipped with 4 optical payloads for wide angle and horizon imaging. Sensor placement allows capturing a synchronized view of Earth and Space across almost 4Pi steradians thereby allowing various ADCS experiments such as Nadir determination and Moon tracking. Attitude control is achieved by magnetorquers and reaction wheels specifically developed for this mission. The talk will focus on the mission achievements, difficulties and challenges and, while discussing the lessons learned, will trace a roadmap for future work