Composition, organization and mechanisms of the transition zone, a gate for the cilium.

The cilium evolved to provide the ancestral eukaryote with the ability to move and sense its environment. Acquiring these functions required the compartmentalization of a dynein-based motility apparatus and signaling proteins within a discrete subcellular organelle contiguous with the cytosol. Here, we explore the potential molecular mechanisms for how the proximal-most region of the cilium, termed transition zone (TZ), acts as a diffusion barrier for both membrane and soluble proteins and helps to ensure ciliary autonomy and homeostasis. These include a unique complement and spatial organization of proteins that span from the microtubule-based axoneme to the ciliary membrane; a protein picket fence; a specialized lipid microdomain; differential membrane curvature and thickness; and lastly, a size-selective molecular sieve. In addition, the TZ must be permissive for, and functionally integrates with, ciliary trafficking systems (including intraflagellar transport) that cross the barrier and make the ciliary compartment dynamic. The quest to understand the TZ continues and promises to not only illuminate essential aspects of human cell signaling, physiology, and development, but also to unravel how TZ dysfunction contributes to ciliopathies that affect multiple organ systems, including eyes, kidney, and brain.

A strategy of enhancing the ionic conductivity of Li7La3Zr2O12 under accurate sintering conditions.

Garnet-type Li7La3Zr2O12 (LLZO) oxide solid electrolytes are spotlighted as solid electrolytes for lithium-ion secondary batteries due to their high thermal and electrochemical stability. However, LLZO has a low ionic conductivity compared to liquid electrolytes, which is one of the biggest problems hindering the commercialization of all-solid-state batteries (ASSBs). Essential conditions for improving the ionic conductivity can be classified into two factors: (1) formation of a cubic LLZO phase related to bulk ionic conductivity and (2) formation of grain boundaries for low interfacial resistance. In this work, cubic LLZO phase formation conditions were first confirmed by TGA-DTA analysis. The LLZO phase was pre-formed via a holding range of furnace temperature profile (HRFTP) found by TGA-DTA analysis. The pre-formed LLZO phase could stabilize the cubic LLZO phase after a sintering process. This was confirmed by XRD analysis. Stabilized cubic LLZO under HRFTP conditions could enhance the bulk ionic conductivity, the main factor affecting the total ionic conductivity. In addition, to confirm the characteristics of sintering temperature changes, the grain boundaries of LLZO surfaces and the color of LZO pellets were investigated by SEM in detail. By setting the holding time process at 600 °C, the pre-formed LLZO phase stabilized the cubic LLZO phase formation after the sintering process. By optimizing the sintering temperature, both bulk and grain boundary ionic conductivities were improved. As a result, an ionic conductivity of 1.87 × 10-4 S cm-1 of the cubic LLZO phase was confirmed by EIS analysis. These results provide an insight into the reproducibility of the facile synthesis of LLZO. This strategy can be successfully applied to next-generation ASSBs.

An Efficient Indoor Positioning Method Based on Wi-Fi RSS Fingerprint and Classification Algorithm.

Wi-Fi received signal strength (RSS) fingerprint-based indoor positioning has been widely used because of its low cost and universality advantages. However, the Wi-Fi RSS is greatly affected by multipath interference in indoor environments, which can cause significant errors in RSS observations. Many methods have been proposed to overcome this issue, including the average method and the error handling method, but these existing methods do not consider the ever-changing dynamics of RSS in indoor environments. In addition, traditional RSS-based clustering algorithms have been proposed in the literature, but they make clusters without considering the nonlinear similarity between reference points (RPs) and the signal distribution in ever-changing indoor environments. Therefore, to improve the positioning accuracy, this paper presents an improved RSS measurement technique (IRSSMT) to minimize the error of RSS observation by using the number of selected RSS and its median values, and the strongest access point (SAP) information-based clustering technique, which groups the RPs using their SAP similarity. The performance of this proposed method is tested by experiments conducted in two different experimental environments. The results reveal that our proposed method can greatly outperform the existing algorithms and improve the positioning accuracy by 89.06% and 67.48%, respectively.

l-Tryptophan: Antioxidant as a Film-Forming Additive for a High-Voltage Cathode.

l-tryptophan (TrP) was investigated as a functional film-forming additive on a lithium-rich layered oxide cathode because it has a much lower oxidation potential than other common carbonate-based electrolytes. Owing to its prior oxidation to a base electrolyte, an artificial cathode-electrolyte interphase (CEI) was formed on the cathode surface, which could be confirmed via X-ray photoelectron spectroscopy and scanning electron microscopy and verified through density functional theory calculations. The functional film formed on the cathode surface suppressed the side reactions between the cathode and electrolyte during cell cycling. As a result, the film prevented CEI thickening and performance deterioration. The optimum weight of TrP was determined to be 0.4 wt % for obtaining the best performance.

MKS5 and CEP290 Dependent Assembly Pathway of the Ciliary Transition Zone.

Cilia have a unique diffusion barrier ("gate") within their proximal region, termed transition zone (TZ), that compartmentalises signalling proteins within the organelle. The TZ is known to harbour two functional modules/complexes (Meckel syndrome [MKS] and Nephronophthisis [NPHP]) defined by genetic interaction, interdependent protein localisation (hierarchy), and proteomic studies. However, the composition and molecular organisation of these modules and their links to human ciliary disease are not completely understood. Here, we reveal Caenorhabditis elegans CEP-290 (mammalian Cep290/Mks4/Nphp6 orthologue) as a central assembly factor that is specific for established MKS module components and depends on the coiled coil region of MKS-5 (Rpgrip1L/Rpgrip1) for TZ localisation. Consistent with a critical role in ciliary gate function, CEP-290 prevents inappropriate entry of membrane-associated proteins into cilia and keeps ARL-13 (Arl13b) from leaking out of cilia via the TZ. We identify a novel MKS module component, TMEM-218 (Tmem218), that requires CEP-290 and other MKS module components for TZ localisation and functions together with the NPHP module to facilitate ciliogenesis. We show that TZ localisation of TMEM-138 (Tmem138) and CDKL-1 (Cdkl1/Cdkl2/Cdkl3/Cdlk4 related), not previously linked to a specific TZ module, similarly depends on CEP-290; surprisingly, neither TMEM-138 or CDKL-1 exhibit interdependent localisation or genetic interactions with core MKS or NPHP module components, suggesting they are part of a distinct, CEP-290-associated module. Lastly, we show that families presenting with Oral-Facial-Digital syndrome type 6 (OFD6) have likely pathogenic mutations in CEP-290-dependent TZ proteins, namely Tmem17, Tmem138, and Tmem231. Notably, patient fibroblasts harbouring mutated Tmem17, a protein not yet ciliopathy-associated, display ciliogenesis defects. Together, our findings expand the repertoire of MKS module-associated proteins--including the previously uncharacterised mammalian Tmem80--and suggest an MKS-5 and CEP-290-dependent assembly pathway for building a functional TZ.

The synergistic effect of inert oxide and metal fluoride dual coatings on advanced cathode materials for lithium ion battery applications.

The effect of Al2O3/LiF dual coatings on the electrochemical performance of over-lithiated layered oxide (OLO) has been investigated. A uniform coating of Al2O3 and LiF is obtained on the surface of the layered pristine material. The OLO with a dual Al2O3/LiF coating with a ratio of 1 : 1.5 exhibits excellent electrochemical performance. An initial discharge capacity of 265.66 mA h g(-1) is obtained at a C-rate of 0.1C. This capacity is approximately 15 mA h g(-1) higher than that of pristine OLO. The capacity retention (92.8% at the 50th cycle) is also comparable to that of pristine OLO (91.4% at the 50th cycle). Coating the cathode with a dual layer comprising Al2O3 and LiF leads to improved charging and discharging kinetics, and prevents direct contact between the cathode and the electrolyte.

Enhancement in the electrochemical performance of zirconium/phosphate bi-functional coatings on LiNi0.8Co0.15Mn0.05O2 by the removal of Li residuals.

The effect of bi-functional coatings consisting of Zr and phosphate (P) on the electrochemical performance of Li1.0Ni0.8Co0.15Mn0.05O2 (NCM) has been investigated. The presence of various types of Zr and P compounds such as oxides (ZrO2 and Li2ZrO3) and phosphates (Zr2P2O9, ZrP2O7 and LiZr2(PO4)3) in the coating was confirmed by experiments as well as density functional theory (DFT) calculations. When the NCM samples were coated with the Zr/P hybrid material, the cycle retention and the amount of removed Li residuals (LiOH, Li2CO3) were enhanced by the synergistic effect from Zr and P. The NCM sample coated with a Zr/P layer with a Zr/P ratio of 1 : 1 exhibited an increase in the initial capacity (209.3 mA h g-1) compared to the pristine sample (207.4 mA h g-1) at 0.1C, owing to the formation of the coating layer. The capacity retention of the Zr/P coated sample (92.4% at the 50th cycle) was also improved compared to that of the pristine NCM sample (90.6% at the 50th cycle). Moreover, the amount of Li residuals in the Zr/P coated NCM sample was greatly reduced from 3693 ppm (pristine NCM) to 2525 ppm (Zr/P = 5 : 5).

Dissecting stop transfer versus conservative sorting pathways for mitochondrial inner membrane proteins in vivo.

Mitochondrial inner membrane proteins that carry an N-terminal presequence are sorted by one of two pathways: stop transfer or conservative sorting. However, the sorting pathway is known for only a small number of proteins, in part due to the lack of robust experimental tools with which to study. Here we present an approach that facilitates determination of inner membrane protein sorting pathways in vivo by fusing a mitochondrial inner membrane protein to the C-terminal part of Mgm1p containing the rhomboid cleavage region. We validated the Mgm1 fusion approach using a set of proteins for which the sorting pathway is known, and determined sorting pathways of inner membrane proteins for which the sorting mode was previously uncharacterized. For Sdh4p, a multispanning membrane protein, our results suggest that both conservative sorting and stop transfer mechanisms are required for insertion. Furthermore, the sorting process of Mgm1 fusion proteins was analyzed under different growth conditions and yeast mutant strains that were defective in the import motor or the m-AAA protease function. Our results show that the sorting of mitochondrial proteins carrying moderately hydrophobic transmembrane segments is sensitive to cellular conditions, implying that mitochondrial import and membrane sorting in the physiological environment may be dynamically tuned.

HNF4A guides the MLL4 complex to establish and maintain H3K4me1 at gene regulatory elements.

Hepatocyte nuclear factor 4A (HNF4A/NR2a1), a transcriptional regulator of hepatocyte identity, controls genes that are crucial for liver functions, primarily through binding to enhancers. In mammalian cells, active and primed enhancers are marked by monomethylation of histone 3 (H3) at lysine 4 (K4) (H3K4me1) in a cell type-specific manner. How this modification is established and maintained at enhancers in connection with transcription factors (TFs) remains unknown. Using analysis of genome-wide histone modifications, TF binding, chromatin accessibility and gene expression, we show that HNF4A is essential for an active chromatin state. Using HNF4A loss and gain of function experiments in vivo and in cell lines in vitro, we show that HNF4A affects H3K4me1, H3K27ac and chromatin accessibility, highlighting its contribution to the establishment and maintenance of a transcriptionally permissive epigenetic state. Mechanistically, HNF4A interacts with the mixed-lineage leukaemia 4 (MLL4) complex facilitating recruitment to HNF4A-bound regions. Our findings indicate that HNF4A enriches H3K4me1, H3K27ac and establishes chromatin opening at transcriptional regulatory regions.

Synergistic Effect of Calcination and Sintering on the Reduction of Grain Boundary Resistance of LATP Solid Electrolyte.

The NASICON-type Li1.4Al0.4Ti1.6(PO4)3 (LATP) solid electrolyte is a promising candidate for next-generation lithium-ion batteries due to its high stability in air and moisture, as well as high bulk ion conductivity. However, the grain boundary resistance of LATP limits its overall ionic conductivity, which remains a major obstacle to the commercialization of all-solid-state batteries. In this study, we made efforts to solve the problem by promoting the minimization of voids and the formation of well-defined grain boundaries by controlling the temperature of two heat treatments during the synthesis process. The crystallization temperature was confirmed through thermogravimetric analysis/DTA analysis, and the degree of crystallization was confirmed using XRD analysis. The formation of grain boundaries and the presence of voids were evaluated by cross-sectional SEM images after sintering. After sintering, the LA_900 °C sample, characterized by a high degree of crystallization and well-formed grain boundaries without voids, demonstrated a low bulk and grain boundary resistance, which was confirmed by electrochemical impedance spectroscopy analysis. The result was an ionic conductivity of 1.72 × 10-4 S/cm. These results provide valuable insights into the facile synthesis of LATP.

IFT trains overcome an NPHP module barrier at the transition zone.

Cilia harbor diffusion barriers for soluble and membrane proteins within their proximal-most transition zone (TZ) region and employ an intraflagellar transport (IFT) system to form dynamic motile and signaling compartments. In this issue, De-Castro and colleagues (2021. J. Cell Biol.https://doi.org/10.1083/jcb.202010178) uncover a long-suspected role for the TZ in gating IFT particles.

A Synergistic Effect of Na+ and Al3+ Dual Doping on Electrochemical Performance and Structural Stability of LiNi0.88Co0.08Mn0.04O2 Cathodes for Li-Ion Batteries.

The synergistic effect of Na+/Al3+ dual doping is investigated to improve the structural stability and electrochemical performance of LiNi0.88Co0.08Mn0.04O2 cathodes for Li-ion batteries. Rietveld refinement and density functional theory calculations confirm that Na+/Al3+ dual doping changes the lattice parameters of LiNi0.88Co0.08Mn0.04O2. The changes in the lattice parameters and degree of cation mixing can be alleviated by maintaining the thickness of the LiO6 slab because the energy of Al-O bonds is higher than that of transition metal (TM)-O bonds. Moreover, Na is an abundant and inexpensive metal, and unlike Al3+, Na+ can be doped into the Li slab. The ionic radius of Na+ (1.02 Å) is larger than that of Li+ (0.76 Å); therefore, when Na+ is inserted into Li sites, the Li slab expands, indicating that Na+ serves as a pillar ion for the Li diffusion pathway. Upon dual doping of the Li and TM sites of Ni-rich Ni0.88Co0.08Mn0.04O2 (NCM) with Na+ and Al3+, respectively, the lattice structure of the obtained NNCMA is more ideal than those of bare NCM and Li+- and Na+-doped NCM (NNCM and NCMA, respectively). This suggests that NNCMA with an ideal lattice structure presents several advantages, namely, excellent structural stability, a low degree of cation mixing, and favorable Li-ion diffusion. Consequently, the rate capability of NNCMA (83.67%, 3 C/0.2 C), which presents favorable Li-ion diffusion because of the expanded Li sites, is higher than those of bare NCM (78.68%), NNCM (81.15%), and NCMA (83.18%). The Rietveld refinement, differential capacity analysis, and galvanostatic intermittent titration technique results indicate that NNCMA exhibits low polarization, favorable Li-ion diffusion, and a low degree of cation mixing; moreover, its phase transition is hindered. Consequently, NNCMA demonstrates a higher capacity retention (84%) than bare NCM (79%), NNCM (82%), and NCMA (82%) after 50 cycles at 1 C. This study provides insight into the fabrication of Ni-rich NCMs with excellent electrochemical performance.

CDKL kinase regulates the length of the ciliary proximal segment.

Cilia are organelles found throughout most unicellular eukaryotes and different metazoan cell types. To accomplish their essential roles in cell motility, fluid flow, and signaling, cilia are divided into subcompartments with variable structures, compositions, and functions. How these specific subcompartments are built remains almost completely unexplored. Here, we show that C. elegans CDKL-1, related to the human CDKL kinase family (CDKL1/CDKL2/CDKL3/CDKL4/CDKL5), specifically controls the length of the proximal segment, a ciliary subdomain conserved in evolution from Tetrahymena motile cilia to C. elegans chemosensory, mammalian olfactory, and photoreceptor non-motile cilia. CDKL-1 associates with intraflagellar transport (IFT), influences the distribution of the IFT anterograde motors heterotrimeric kinesin-II and homodimeric OSM-3-kinesin/KIF17 in the proximal segment, and shifts the boundary between the proximal and distal segments (PS/DS boundary). CDKL-1 appears to function independently from several factors that influence cilium length, namely the kinases DYF-5 (mammalian CILK1/MAK) and NEKL-1 (NEK9), as well as the depolymerizing kinesins KLP-13 (KIF19) and KLP-7 (KIF2). However, a different kinase, DYF-18 (CCRK), is needed for the correct localization and function of CDKL-1 and similarly influences the length of the proximal segment. Loss of CDKL-1, which affects proximal segment length without impairing overall ciliary microtubule structural integrity, also impairs cilium-dependent processes, namely cGMP-signaling-dependent body length control and CO2 avoidance. Collectively, our findings suggest that cilium length is regulated by various pathways and that the IFT-associated kinase CDKL-1 is essential for the construction of a specific ciliary compartment and contributes to development and sensory physiology.

Different roles of DosS and DosT in the hypoxic adaptation of Mycobacteria.

The DosS (DevS) and DosT histidine kinases form a two-component system together with the DosR (DevR) response regulator in Mycobacterium tuberculosis. DosS and DosT, which have high sequence similarity to each other over the length of their amino acid sequences, contain two GAF domains (GAF-A and GAF-B) in their N-terminal sensory domains. Complementation tests in conjunction with phylogenetic analysis showed that DevS of Mycobacterium smegmatis is more closely related to DosT than DosS. We also demonstrated in vivo that DosS and DosT of M. tuberculosis play a differential role in hypoxic adaptation. DosT responds to a decrease in oxygen tension more sensitively and strongly than DosS, which might be attributable to their different autooxidation rates. The different responsiveness of DosS and DosT to hypoxia is due to the difference in their GAF-A domains accommodating the hemes. Multiple alignment analysis of the GAF-A domains of mycobacterial DosS (DosT) homologs and subsequent site-directed mutagenesis revealed that just one substitution of E87, D90, H97, L118, or T169 of DosS with the corresponding residue of DosT is sufficient to convert DosS to DosT with regard to the responsiveness to changes in oxygen tension.

The regulator RamA influences cmytA transcription and cell morphology of Corynebacterium ammoniagenes.

RamA plays a regulatory role for acetate utilization and S-layer biosynthesis in Corynebacterium glutamicum. Looking for any additional role, the function of RamA was analyzed in Corynebacterium ammoniagenes, which is closely related to C. glutamicum. In this study, we showed that the DeltaramA mutant constructed by a markerless knockout strategy possessed increased cell surface hydrophobicity, leading to the formation of aggregated cell masses in liquid media. In addition, the mutant exhibited an elongated cell shape as observed by SEM, suggesting that cell wall-associated proteins might be influenced. Furthermore, cell surface proteome analysis revealed that the expression of cmytA gene encoding corynomycoloyl transferase required for cell wall biosynthesis was down-regulated in the mutant, supporting the regulatory role of RamA in cell wall assembly. These studies support a novel regulatory role of RamA in inducing the expression of proteins required for cell wall assembly.

High-Ni cathode material improved with Zr for stable cycling of Li-ion rechargeable batteries.

The Zr solvent solution method, which allows primary and secondary particles of LiNi0.90Co0.05Mn0.05O2 (NCM) to be uniformly doped with Zr and simultaneously to be coated with an Li2ZrO3 layer, is introduced in this paper. For Zr doped NCM, which is formed using the Zr solvent solution method (L-NCM), most of the pinholes inside the precursor disappear owing to the diffusion of the Zr dopant solution compared with Zr-doped NCM, which is formed using the dry solid mixing method from the (Ni0.90Co0.05Mn0.05)(OH)2 precursor and the Zr source (S-NCM), and Li2ZrO3 is formed at the pinhole sites. The mechanical strength of the powder is enhanced by the removal of the pinholes by the formation of Li2ZrO3 resulting from diffusion of the solvent during the mixing process, which provides protection from cracking. The coating layer functions as a protective layer during the washing process for removing the residual Li. The electrochemical performance is improved by the synergetic effects of suitable coatings and the enhanced structural stability. The capacity-retentions for 2032 coin cells are 86.08%, 92.12%, and 96.85% at the 50th cycle for pristine NCM, S-NCM, and L-NCM, respectively. The superiority of the liquid mixing method is demonstrated for 18 650 full cells. In the 300th cycle in the voltage range of 2.8-4.35 V, the capacity-retentions for S-NCM and L-NCM are 77.72% and 81.95%, respectively.

Sink-oriented Dynamic Location Service Protocol for Mobile Sinks with an Energy Efficient Grid-Based Approach.

Sensor nodes transmit the sensed information to the sink through wireless sensor networks (WSNs). They have limited power, computational capacities and memory. Portable wireless devices are increasing in popularity. Mechanisms that allow information to be efficiently obtained through mobile WSNs are of significant interest. However, a mobile sink introduces many challenges to data dissemination in large WSNs. For example, it is important to efficiently identify the locations of mobile sinks and disseminate information from multi-source nodes to the multi-mobile sinks. In particular, a stationary dissemination path may no longer be effective in mobile sink applications, due to sink mobility. In this paper, we propose a Sink-oriented Dynamic Location Service (SDLS) approach to handle sink mobility. In SDLS, we propose an Eight-Direction Anchor (EDA) system that acts as a location service server. EDA prevents intensive energy consumption at the border sensor nodes and thus provides energy balancing to all the sensor nodes. Then we propose a Location-based Shortest Relay (LSR) that efficiently forwards (or relays) data from a source node to a sink with minimal delay path. Our results demonstrate that SDLS not only provides an efficient and scalable location service, but also reduces the average data communication overhead in scenarios with multiple and moving sinks and sources.

EFHC1, implicated in juvenile myoclonic epilepsy, functions at the cilium and synapse to modulate dopamine signaling.

Neurons throughout the mammalian brain possess non-motile cilia, organelles with varied functions in sensory physiology and cellular signaling. Yet, the roles of cilia in these neurons are poorly understood. To shed light into their functions, we studied EFHC1, an evolutionarily conserved protein required for motile cilia function and linked to a common form of inherited epilepsy in humans, juvenile myoclonic epilepsy (JME). We demonstrate that C. elegans EFHC-1 functions within specialized non-motile mechanosensory cilia, where it regulates neuronal activation and dopamine signaling. EFHC-1 also localizes at the synapse, where it further modulates dopamine signaling in cooperation with the orthologue of an R-type voltage-gated calcium channel. Our findings unveil a previously undescribed dual-regulation of neuronal excitability at sites of neuronal sensory input (cilium) and neuronal output (synapse). Such a distributed regulatory mechanism may be essential for establishing neuronal activation thresholds under physiological conditions, and when impaired, may represent a novel pathomechanism for epilepsy.

Machine learning assisted optimization of electrochemical properties for Ni-rich cathode materials.

Optimizing synthesis parameters is the key to successfully design ideal Ni-rich cathode materials that satisfy principal electrochemical specifications. We herein implement machine learning algorithms using 330 experimental datasets, obtained from a controlled environment for reliability, to construct a predictive model. First, correlation values showed that the calcination temperature and the size of the particles are determining factors for achieving a long cycle life. Then, we compared the accuracy of seven different machine learning algorithms for predicting the initial capacity, capacity retention rate, and amount of residual Li. Remarkable predictive capability was obtained with the average value of coefficient of determinant, R2 = 0.833, from the extremely randomized tree with adaptive boosting algorithm. Furthermore, we propose a reverse engineering framework to search for experimental parameters that satisfy the target electrochemical specification. The proposed results were validated by experiments. The current results demonstrate that machine learning has great potential to accelerate the optimization process for the commercialization of cathode materials.

High-Performance and Industrially Feasible Ni-Rich Layered Cathode Materials by Integrating Coherent Interphase.

For developing the industrially feasible Ni-rich layered oxide cathode with extended cycle life, it is necessary to mitigate both the mechanical degradation due to intergranular cracking between primary particles and gas generation from the reaction between the electrolyte and residual Li in the cathode. To simultaneously resolve these two issues, we herein propose a simple but novel method to reinforce the primary particles in LiNi0.91Co0.06Mn0.03O2 by providing a Li-reactive material, whose spinel interphase is coherent with the surface of the cathode. The modified structure significantly outperforms analogous bare samples: they conserve more than 90% of the initial capacity after 50 cycles and also exhibit a greater rate capability. By tracking the same particle location during cycling, we confirmed that the current method significantly reduces crack generation because the provided coating material can penetrate inside the grain boundary of the secondary particle and help maintain the volume of the primary particle. Finally, first-principles calculations were implemented to determine the role of this spinel material, i.e., having intrinsically isotropic lattice parameters, superior mechanical properties, and only a small volume change during delithiation. We believe that the proposed method is straightforward and cost-effective; hence, it is directly applicable for the mass production of Ni-rich cathode material to enable its commercialization.