Direct electrochemical generation of supercooled sulfur microdroplets well below their melting temperature.

Supercooled liquid sulfur microdroplets were directly generated from polysulfide electrochemical oxidation on various metal-containing electrodes. The sulfur droplets remain liquid at 155 °C below sulfur's melting point (Tm = 115 °C), with fractional supercooling change (Tm - Tsc)/Tm larger than 0.40. In operando light microscopy captured the rapid merging and shape relaxation of sulfur droplets, indicating their liquid nature. Micropatterned electrode and electrochemical current allow precise control of the location and size of supercooled microdroplets, respectively. Using this platform, we initiated and observed the rapid solidification of supercooled sulfur microdroplets upon crystalline sulfur touching, which confirms supercooled sulfur's metastability at room temperature. In addition, the formation of liquid sulfur in electrochemical cell enriches lithium-sulfur-electrolyte phase diagram and potentially may create new opportunities for high-energy Li-S batteries.

A Two-Dimensional MoS2 Catalysis Transistor by Solid-State Ion Gating Manipulation and Adjustment (SIGMA).

A variety of methods including tuning chemical compositions, structures, crystallinity, defects and strain, and electrochemical intercalation have been demonstrated to enhance the catalytic activity. However, none of these tuning methods provide direct dynamical control during catalytic reactions. Here we propose a new method to tune the activity of catalysts through solid-state ion gating manipulation and adjustment (SIGMA) using a catalysis transistor. SIGMA can electrostatically dope the surface of catalysts with a high electron concentration over 5 × 1013 cm-2 and thus modulate both the chemical potential of the reaction intermediates and their electrical conductivity. The hydrogen evolution reaction (HER) on both pristine and defective MoS2 were investigated as model reactions. Our theoretical and experimental results show that the overpotential at 10 mA/cm2 and Tafel slope can be in situ, continuously, dynamically, and reversibly tuned over 100 mV and around 100 mV/dec, respectively.

Gate-Induced Metal-Insulator Transition in MoS2 by Solid Superionic Conductor LaF3.

Electric-double-layer (EDL) gating with liquid electrolyte has been a powerful tool widely used to explore emerging interfacial electronic phenomena. Due to the large EDL capacitance, a high carrier density up to 1014 cm-2 can be induced, directly leading to the realization of field-induced insulator to metal (or superconductor) transition. However, the liquid nature of the electrolyte has created technical issues including possible side electrochemical reactions or intercalation, and the potential for huge strain at the interface during cooling. In addition, the liquid coverage of active devices also makes many surface characterizations and in situ measurements challenging. Here, we demonstrate an all solid-state EDL device based on a solid superionic conductor LaF3, which can be used as both a substrate and a fluorine ionic gate dielectric to achieve a wide tunability of carrier density without the issues of strain or electrochemical reactions and can expose the active device surface for external access. Based on LaF3 EDL transistors (EDLTs), we observe the metal-insulator transition in MoS2. Interestingly, the well-defined crystal lattice provides a more uniform potential distribution in the substrate, resulting in less interface electron scattering and therefore a higher mobility in MoS2 transistors. This result shows the powerful gating capability of LaF3 solid electrolyte for new possibilities of novel interfacial electronic phenomena.

[Study on the effect of alginate impression spray disinfection process on model accuracy].

PURPOSE: To investigate the effect of a new cleaning and disinfection process of oral impressions on the accuracy of alginate dental impression. METHODS: Sixteen young volunteers were selected to make alginate oral impression (2 times for each upper and lower jaw) and oral scandata acquisition (1 time for each upper and lower jaw) to obtain STL data. The 2 pairs of alginate impressions of each subject were numbered group 1, group 2, inwhich group 1 was not sterilized and the oral impression film in group 2 was treated with the method and steps of new oral impression cleaning and disinfection. All the oral impressions of the subjects were perfused with plaster models in the same standard way and demoulded. The obtained plaster models were examined and scanned after appropriate trimming and grinding. The plaster model data obtained from each group of each patient after warehouse scanning were compared with the orally scanned model data for alignment analysis, and root mean square(RMS) was used as a parameter to evaluate the deviation between the test model and the standard model. The chromatograms of the deviations were saved for visualization and analysis to observe the differences in model accuracy from several dimensions. Statistical analysis was performed with SPSS 23.0 software package. RESULTS: The differences in RMS of model accuracy of maxillary dental series of alginate impressions were statistically significant, in which the RMS of the group disinfecting the maxillary oral impression film with a new oral impression cleaning and disinfection process was significantly higher than that of the nonsterilized group (P=0.006), while the difference between model accuracy RMS of the mandibular disinfection group and non-disinfection group was not statistically significant(P=0.874). CONCLUSIONS: The new technical specifications for cleaning and disinfection of dental impressions recommended by the Chinese Stomatological Association have certain effects on the accuracy of dental impressions made of alginate material,and the details in its process should be further improved.

IL-23/IL-17 immune axis mediates the imiquimod-induced psoriatic inflammation by activating ACT1/TRAF6/TAK1/NF-κB pathway in macrophages and keratinocytes.

The interleukin-23 (IL-23)/IL-17 immune axis has been linked to the pathology of psoriasis, but how this axis contributes to skin inflammation in this disease remains unclear. We measured inflammatory cytokines associated with the IL-23/IL-17 immune axis in the serum of patients with psoriasis using enzyme-linked immunosorbent assays. Psoriasis was induced in male C57BL/6J mice using imiquimod (IMQ) cream, and animals received intraperitoneal injections of recombinant mouse anti-IL-23A or anti-IL-17A antibodies for 7 days. The potential effects of the IL-23/IL-17 immune axis on skin inflammation were assessed based on pathology scoring, hematoxylin-eosin staining of skin samples, and quantitation of inflammatory cytokines. Western blotting was used to evaluate levels of the following factors in skin: ACT1, TRAF6, TAK1, NF-κB, and pNF-κB. The serum of psoriasis patients showed elevated levels of several cytokines involved in the IL-23/IL-17 immune axis: IL-2, IL-4, IL-8, IL-12, IL-17, IL-22, IL-23, and interferon-γ. Levels of IL-23p19 and IL-17 were increased in serum and skin of IMQ-treated mice, while ACT1, TRAF6, TAK1, NF-κB, and pNF-κB were upregulated in the skin. A large proportion of NF-κB p65 localized in nucleus of involucrin+ cells in the epidermis and in F4/80+ cells of the dermis of psoriatic lesional skin. Treating these animals with anti-IL-23 or anti-IL-17 antibodies improved pathological score and immune imbalance, mitigated skin inflammation and downregulated ACT1, TRAF6, TAK1, NF-κB, and pNF-κB in skin. Our results suggest that skin inflammation mediated by the IL-23/IL-17 immune axis in psoriasis involves activation of the ACT1/TRAF6/TAK1/NF-κB pathway in keratinocytes and macrophage.

Structures of human MST3 kinase in complex with adenine, ADP and Mn2+.

The MST family is a subclass of mammalian serine/threonine kinases that are related to the yeast sterile-20 protein and are implicated in regulating cell growth and transformation. The MST3 protein contains a 300-residue catalytic domain and a 130-residue regulatory domain, which can be cleaved by caspase and activated by autophosphorylation, promoting apoptosis. Here, five crystal structures of the catalytic domain of MST3 are presented, including a complex with ADP and manganese, a unique cofactor preferred by the enzyme, and a complex with adenine. Similar to other protein kinases, the catalytic domain of MST3 folds into two lobes: the smaller N lobe forms the nucleotide-binding site and the larger C lobe recognizes the polypeptide substrate. The bound ADP and Mn(2+) ions are covered by a glycine-rich loop and held in place by Asn149 and Asp162. A different orientation was observed for the ligand in the MST3-adenine complex. In the activation loop, the side chain of Thr178 is phosphorylated and is sandwiched by Arg143 and Arg176. Comparison of this structure with other similar kinase structures shows a 180 degrees rotation of the loop, leading to activation of the enzyme. The well defined protein-ligand interactions also provide useful information for the design of potent inhibitors.

[A comparative study of silicon rubber impression and intraoral scanning impression in oral clinical teaching].

PURPOSE: The aim of this study was to assess and compare patient satisfaction and time required between silicon rubber impression and intraoral scanning impression. METHODS: Six undergraduates participated in this study. silicon rubber impression and intraoral scanning impression were taken, the time required to obtain the impressions and the scores of visual analog scale(VAS) were recorded. SPSS 23.0 software package was used for statistical analysis. RESULTS: The time and patients satisfaction of silicon rubber impression were better than intraoral scanning impressions, and there were significant differences between the two groups(P<0.05). CONCLUSIONS: Using silicon rubber impression, the patient experience is better. To use intraoral scanning impression technology, dentists should be more skilled. With the role-playing method,dental interns can learn the operation key points and precautions of different impression-taking methods even better.

Electrochemical generation of liquid and solid sulfur on two-dimensional layered materials with distinct areal capacities.

It has recently been shown that sulfur, a solid material in its elementary form S8, can stay in a supercooled state as liquid sulfur in an electrochemical cell. We establish that this newly discovered state could have implications for lithium-sulfur batteries. Here, through in situ studies of electrochemical sulfur generation, we show that liquid (supercooled) and solid elementary sulfur possess very different areal capacities over the same charging period. To control the physical state of sulfur, we studied its growth on two-dimensional layered materials. We found that on the basal plane, only liquid sulfur accumulates; by contrast, at the edge sites, liquid sulfur accumulates if the thickness of the two-dimensional material is small, whereas solid sulfur nucleates if the thickness is large (tens of nanometres). Correlating the sulfur states with their respective areal capacities, as well as controlling the growth of sulfur on two-dimensional materials, could provide insights for the design of future lithium-sulfur batteries.

Fast lithium growth and short circuit induced by localized-temperature hotspots in lithium batteries.

Fast-charging and high-energy-density batteries pose significant safety concerns due to high rates of heat generation. Understanding how localized high temperatures affect the battery is critical but remains challenging, mainly due to the difficulty of probing battery internal temperature with high spatial resolution. Here we introduce a method to induce and sense localized high temperature inside a lithium battery using micro-Raman spectroscopy. We discover that temperature hotspots can induce significant lithium metal growth as compared to the surrounding lower temperature area due to the locally enhanced surface exchange current density. More importantly, localized high temperature can be one of the factors to cause battery internal shorting, which further elevates the temperature and increases the risk of thermal runaway. This work provides important insights on the effects of heterogeneous temperatures within batteries and aids the development of safer batteries, thermal management schemes, and diagnostic tools.

Spatially controlled doping of two-dimensional SnS2 through intercalation for electronics.

Doped semiconductors are the most important building elements for modern electronic devices 1 . In silicon-based integrated circuits, facile and controllable fabrication and integration of these materials can be realized without introducing a high-resistance interface2,3. Besides, the emergence of two-dimensional (2D) materials enables the realization of atomically thin integrated circuits4-9. However, the 2D nature of these materials precludes the use of traditional ion implantation techniques for carrier doping and further hinders device development 10 . Here, we demonstrate a solvent-based intercalation method to achieve p-type, n-type and degenerately doped semiconductors in the same parent material at the atomically thin limit. In contrast to naturally grown n-type S-vacancy SnS2, Cu intercalated bilayer SnS2 obtained by this technique displays a hole field-effect mobility of ~40 cm2 V-1 s-1, and the obtained Co-SnS2 exhibits a metal-like behaviour with sheet resistance comparable to that of few-layer graphene 5 . Combining this intercalation technique with lithography, an atomically seamless p-n-metal junction could be further realized with precise size and spatial control, which makes in-plane heterostructures practically applicable for integrated devices and other 2D materials. Therefore, the presented intercalation method can open a new avenue connecting the previously disparate worlds of integrated circuits and atomically thin materials.

Reversible and selective ion intercalation through the top surface of few-layer MoS2.

Electrochemical intercalation of ions into the van der Waals gap of two-dimensional (2D) layered materials is a promising low-temperature synthesis strategy to tune their physical and chemical properties. It is widely believed that ions prefer intercalation into the van der Waals gap through the edges of the 2D flake, which generally causes wrinkling and distortion. Here we demonstrate that the ions can also intercalate through the top surface of few-layer MoS2 and this type of intercalation is more reversible and stable compared to the intercalation through the edges. Density functional theory calculations show that this intercalation is enabled by the existence of natural defects in exfoliated MoS2 flakes. Furthermore, we reveal that sealed-edge MoS2 allows intercalation of small alkali metal ions (e.g., Li+ and Na+) and rejects large ions (e.g., K+). These findings imply potential applications in developing functional 2D-material-based devices with high tunability and ion selectivity.

Atomic structure of sensitive battery materials and interfaces revealed by cryo-electron microscopy.

Whereas standard transmission electron microscopy studies are unable to preserve the native state of chemically reactive and beam-sensitive battery materials after operation, such materials remain pristine at cryogenic conditions. It is then possible to atomically resolve individual lithium metal atoms and their interface with the solid electrolyte interphase (SEI). We observe that dendrites in carbonate-based electrolytes grow along the <111> (preferred), <110>, or <211> directions as faceted, single-crystalline nanowires. These growth directions can change at kinks with no observable crystallographic defect. Furthermore, we reveal distinct SEI nanostructures formed in different electrolytes.

A dual-mode textile for human body radiative heating and cooling.

Maintaining human body temperature is one of the most basic needs for living, which often consumes a huge amount of energy to keep the ambient temperature constant. To expand the ambient temperature range while maintaining human thermal comfort, the concept of personal thermal management has been recently demonstrated in heating and cooling textiles separately through human body infrared radiation control. Realizing these two opposite functions within the same textile would represent an exciting scientific challenge and a significant technological advancement. We demonstrate a dual-mode textile that can perform both passive radiative heating and cooling using the same piece of textile without any energy input. The dual-mode textile is composed of a bilayer emitter embedded inside an infrared-transparent nanoporous polyethylene (nanoPE) layer. We demonstrate that the asymmetrical characteristics of both emissivity and nanoPE thickness can result in two different heat transfer coefficients and achieve heating when the low-emissivity layer is facing outside and cooling by wearing the textile inside out when the high-emissivity layer is facing outside. This can expand the thermal comfort zone by 6.5°C. Numerical fitting of the data further predicts 14.7°C of comfort zone expansion for dual-mode textiles with large emissivity contrast.

A Stretchable Graphitic Carbon/Si Anode Enabled by Conformal Coating of a Self-Healing Elastic Polymer.

A high-capacity stretchable graphitic carbon/Si foam electrode is enabled by a conformal self-healing elastic polymer coating. The composite electrode exhibits high stretchability (up to 88%) and endures 1000 stretching-releasing cycles at 25% strain with detrimental resistance increase. Meanwhile, the electrode delivers a high reversible specific capacity of 719 mA g(-1) and good cycling stability with 81% capacity retention after 100 cycles.

Quantitative evaluation of severity of behavioral and psychological symptoms of dementia in patients with vascular dementia.

To quantitatively evaluate severity of behavioral and psychological symptoms of dementia (BPSD) for vascular dementia (VD). Changes of 51 patients with VD in BPSD between the first and 24th week were assessed using the Neuropsychiatric Inventory (NPI) and the behavioral pathology in Alzheimer's disease (BEHAVE-AD) rating scale, in detrended fluctuation analysis (DFA) represented by diurnal activity (DA), evening activity (EA), and nocturnal activity (NA), and the relationships were analyzed. The subscores of activity disturbances, diurnal rhythm disturbances, and anxieties and phobias in the BEHAVE-AD score, and that of agitation, irritability, and sleep disorder in the NPI score were significantly increased compared with the first week, as was for the changes for EA in the DFA value. A linear correlation was observed between the changes of activity disturbances plus anxieties and phobias, and those of DA, and between the development of diurnal rhythm and those of EA, the vehement and autism scores and those of DA, and the difference in sleep disorder scores and those of EA, respectively. Analysis of DA, NA, and EA may reflect the fluctuational degrees of VD-BPSD, can provide a useful assessment of VD-BPSD accompanied by clinical scores for VD.

[Evaluation of C-reactive protein levels in serum and gingival crevicular fluid in type 2 diabetes patients with periodontitis].

PURPOSE: To observe the relationship of the C-reactive protein (CRP) levels and the severity of the periodontal inflammation and the diabetes glycemic control. METHODS: The CRP levels in serum and in gingival crevicular fluid(GCF) in type 2 diabetes patients with chronic periodontitis, patients with periodontitis alone, patients with type 2 diabetes alone and healthy people were assayed. Glycosylated hemoglobin (HbAlc) in serum was detected. Probing depth (PD) and sulcus bleeding index (SBI) were recorded. The data were analyzed by non-paired t test and Spearman correlation analysis with SPSS 10.0 software package. RESULTS: The serum CRP levels in type 2 diabetes patients with periodontitis and periodontitis and type 2 diabetes were significantly higher than those in healthy group(P<0.01). Serum CRP levels in type 2 diabetes patients with periodontitis were the highest and were significantly higher than that in periodontitis group(P<0.01) and type 2 diabetes group(P<0.05). However, the CRP levels in GCF in each group were far lower than those in serum and no difference was detected in the four groups (P>0.05). The CRP levels in serum didn't correlate to the CRP levels in GCF (P>0.05).The CRP levels in serum correlated to PD, SBI and HbAlc(P<0.01). CONCLUSION: CRP may be involved in the interaction of chronic periodontitis and type 2 diabetes. The CRP levels in GCF could not reflect the inflammation of the periodontitis or the condition of diabetes.

[The studies on osteoblasts' mineralization and attachment affected by enamel matrix proteins].

OBJECTIVE: Investigate the effects of enamel matrix proteins(EMPs) on the mineralization and attachment of osteoblasts, to explore the possible mechanism of alveolar bone regeneration induced by enamel matrix proteins(EMPs). METHODS: MC3T3-E1 osteoblasts were cultured in vitro and EMPs was added to medium in several concentrations. Cell's mineralizing ability was detected by Von-Kossa stain and attachment ability was detected by counting cells number. RESULTS: The results manifested that EMPs promote more mineral nodules formation (P<0.01). But MC3T3-E1 cells' attachment ability was not improved (P>0.05). CONCLUSION: EMPs enhanced the mineralizing function of osteoblasts, had no effects on implanting on root surface of osteoblasts, which may play an important role in the regeneration of alveolar bone.