Sheet-like Structures Research Articles

Role of Sterically Bulky Azobenzenes in the Molecular Assembly of Pyrene Derivatives: Rectangular Sheet-like Structures and Their Emission Characteristics.

The development of pyrene-based fluorescent assembled systems with desirable emission characteristics by reducing conventional concentration quenching and/or aggregation-induced quenching (ACQ) is highly desirable. In this investigation, we designed a new azobenzene-functionalized pyrene derivative (AzPy) in which sterically bulky azobenzene is linked to pyrene. Absorption and fluorescence spectroscopic results before and after molecular assembly indicate that even in a dilute N,N-dimethylformamide (DMF) solution (~10 μM), AzPy molecules experienced significant concentration quenching, whereas the emission intensities of AzPy DMF-H2O turbid suspensions containing self-assembled aggregates were slightly enhanced and showed similar values regardless of the concentration. The shape and size of sheet-like structures, from incomplete flakes less than one micrometer in size to well-completed rectangular microstructures, could be adjusted by changing the concentration. Importantly, such sheet-like structures exhibit concentration dependence of their emission wavelength from blue to yellow-orange. Comparison with the precursor (PyOH) demonstrates that the introduction of a sterically twisted azobenzene moiety plays an important role in converting the spatial molecular arrangements from H- to J-type aggregation mode. Thus, AzPy chromophores grow into anisotropic microstructures through inclined J-type aggregation and high crystallinity, which are responsible for their unexpected emission characteristics. Our findings provide useful insight into the rational design of fluorescent assembled systems.

Spitz nevus and melanoma: evaluation with dermoscopy and reflectance confocal microscopy.

Spitz nevi (SN) include a wide range of benign melanocytic nevi, which are controversial due to their morphologic resemblance to melanoma (MM). To describe dermoscopic and reflectance confocal microscopic (RCM) features of SN compared to MM and assess the RCM utility in the differential diagnosis. We performed a multicentre retrospective analysis of MM and SN evaluated with dermoscopy and reflectance confocal microscopy. Three RCM mosaics were obtained for each lesion. Nine dermoscopic and twenty-one microscopic features were assessed for each lesion. A total of 26 lesions (15 SN and 11 MM) were included. Dermoscopically, most SN showed a "starburst" pattern. Asymmetry was marked in 8 MM. There were 6 dermoscopic features significantly more prevalent in MM than in SN. RCM showed that an atypical honeycomb pattern, atypical infiltration, and disarray of the epidermis were significant for MM. SN mostly revealed a typical honeycomb pattern. At the DEJ, most of SN had a meshwork pattern; MM revealed an atypical meshwork pattern. Atypical cells and sheet-like structures were observed in most MM. A combined approach using dermoscopy and RCM supports the differential diagnosis of SN and MM. Although our study showed some significant differences between SN and MM in RCM, further research on a larger group should be considered.

Construction of porous carbon nanosheets by dual-template strategy for zinc ion hybrid capacitor

Carbonaceous zinc ion hybrid capacitors (CZHCs) have attracted numerous interests thank to the advantages of large energy density of zinc-ion battery and excellent security and high power density of supercapacitors. Nevertheless, the preparation of carbon cathode is relatively complex, and it is urgent to develop a simple and efficient preparation method. Herein, the porous carbon nanosheets (C-Xs) were prepared by dual-template strategy combined K2CO3 activation from anthracene molecules, which present unique layered sheet-like structures and high surface area, displaying excellent zinc storage properties as cathode for Zn‖C-X ZHCs. Zn‖C-800 ZHC achieves high discharge capacity of 121.7 mAh g−1, maximum energy density and power density of 109.3 Wh kg−1 and 15.6 kW kg−1 in 3 M ZnSO4 electrolyte, respectively. Moreover, the capacity retention of 96.2% and coulombic efficiency of ∼100% is obtained after 30,000 cycles. This work opens up a simple and efficient rout for the synthesis of carbon nanosheet cathode by dual-template strategy for ZHC.

Production of poly-(R)-3-hydroxybutyrate from halophilic bacterium Salinivibrio sp. utilizing palm oil mill effluent as a carbon source

The accumulation of plastic waste has become an emerging threat to the ecosystem. Reducing plastic waste can be overcome by replacing petrochemical-based plastics with biodegradable ones, such as poly-(R)-3-hydroxybutyrate (PHB). In the present study, we have successfully isolated, characterized, and optimized the PHB yield produced by halophilic bacteria isolated from salt lake Gili Meno, Lombok, Indonesia, utilizing palm oil mill effluent (POME) as the carbon source. Bacterial screening found that isolated bacteria from the bottom of the lake produced the highest PHB yield, mainly when the bacterial isolate was grown in the medium containing 15% (v/v) POME, 5% (w/v) NaCl, as well as 0.1% (w/v) yeast, and 0.1% (w/v) ammonium sulfate. The highest PHB yield produced by the bacterial isolate in this medium was about 5.0 ± 0.8 mg/L. Ribotyping has identified the bacterial isolate as Salinivibrio sp. with 99.9% similarity to the 16S rRNA gene of Salinivibrio sp. YCSC6 (GenBank accession no. CP039516.1). Scanning electron microscope images of the produced PHB exhibited the morphology of sheet-like structures. Thermal analysis revealed that the produced PHB has maximum decomposition and degradation temperatures at 442.4 °C and 282.9 °C, respectively. Therefore, Salinivibrio sp. is a potential bacterial isolate for producing high-yield PHB with high thermal stability. In addition, this bacterial strain is also a productive bacterium in bio-converting POME into PHB, thereby resolving the environmental issue of liquid waste from palm oil industries.

2D layered MXene/TiO2 nano-heterostructures for photocatalytic H2 generation

It is known that 2D MXene can be oxidized in air to form heterostructures of carbides, carbon, and oxides. We prepared MXene/TiO2 nano-heterostructures by in-situ thermal processing of MXene (Ti3C2Tx) at 250–400 °C temperature range in air. The structural studies by x-ray diffraction indicate the formation of MXene/TiO2 nano-heterostructures with increasing the annealing temperature above 300 °C and the resulting structure became mostly TiO2 after 400 °C annealing with no detectable MXene peaks in XRD patterns. The diffuse reflectance UV–Visible absorbance spectroscopy shows the blue shift in the absorbance profile of MXene from 720 to 380 nm by increasing the temperature. Photoluminescence spectra shows two emission peaks, the emission at 370 nm and 470 nm corresponds to band edge emission and oxygen defect, respectively. Raman analysis also supports the formation of MXene and TiO2 nano-heterostructures. Scanning and transmission microscopy results depict the formation-layered structures of MXene transformed into exfoliated sheet-like structures due to etching. The photocatalytic activity of formed nano-heterostructures was investigated for H2 generation via water splitting and aqueous methylene blue dye degradation. The nano-heterostructure formed at 350 °C conferred highest H2 production (366 μmol/0.1 g) as compared to other prepared compositions having apparent quantum yield (AQY) of 5.9% and shows MB degradation rate of 13.16 × 10–3 min−1.The formation of nano-heterostructures, particle morphology, higher surface area, the presence of remaining MXene might be responsible for higher photocatalytic activity. These MXene-based nano-heterostructures will have potentials along with other semiconductors for enhanced hydrogen production.Graphical abstract Schematic presentation of photocatalytic water splitting using Ti3C2Tx/TiO2 nano-heterostructure.

The local energy flux surrogate in turbulent open-channel flows

We present a local analysis of turbulence in open-channel flows, using time-series velocity measurements. The method is based on a local form of the Kolmogorov “4/3-law” of homogeneous turbulence for the third-order moment of velocity increments. Following the Duchon and Robert [“Inertial energy dissipation for weak solutions of incompressible Euler and Navier–Stokes equations,” Nonlinearity 13, 249 (2000)] idea, which envisions turbulence dissipation as a lack of smoothness of the Navier–Stokes solutions, we estimate the local energy flux in a laboratory experiment with natural bed flows. Taking advantage of one-dimensional filtering techniques, under reasonable hypothesis, simple expressions of a surrogate of the energy flux are provided. The local energy flux surrogate reveals that, independently of the geometry, turbulence dissipation is highly intermittent. Among a variety of eddies that populate turbulence, dissipative singularities appear in sheet-like, tube, and filament structures, with large amplitude variations and rotations. This simplified technique can be applied to any measurement of hydrodynamic turbulence.

Early biomineralization and exceptional preservation of the first thrombolite reefs with archaeocyaths in the lower Cambrian of the western Anti-Atlas, Morocco

AbstractThrombolite reefs with archaeocyaths are common in the subtidal limestones of the lower Cambrian in the western Anti-Atlas of Morocco. The Igoudine Formation of the Tata Group recorded the first replacement of the microbial consortium (stromatolite-dominated) by thrombolite reefs with archaeocyaths and shelly metazoans. In order to better understand the role of the microbial community in the formation of thrombolite reefs with archaeocyaths across this critical transition, the macro-, micro- and ultra-fabric of thrombolites have been studied in detail. Three major components are identified within the first thrombolytic reef: archaeocyaths, calcimicrobes and micritic matrix. The studied thrombolites are typically dominated by the calcimicrobe Renalcis with subordinate Epiphyton and Girvanella. Scanning electron microscopy of the dark micrite of the Renalcis chambers showed amorphous translucent sheet-like structures interpreted as extracellular polymeric substances, closely associated with organominerals including nanoglobules and polyhedrons. Exceptionally well-preserved Renalcis chambers contain bacterial fossils similar to those described in modern microbialites, including microspherical coccoid fossils and filamentous bacteria that are either spaced or in close associations forming colonies. These organomineralization-related features suggest a bacterial origin for the Renalcis calcimicrobe. The matrices between the Renalcis chambers consist predominantly of clotted peloidal micrite. Mineralization of Renalcis microframes may involve two major biomineralization processes: (1) replacement of organic matter by organominerals resulting from anaerobic degradation of extracellular polymeric substances and bacterial sheaths and (2) encrustation of bacterial sheaths and extracellular polymeric substances due to increasing alkalinity of the microenvironment. These mechanisms played a crucial role in the early diagenetic cementation and preservation of the studied reefs.

Folding Coarse-Grained Oligomer Models with PyRosetta.

Non-biological foldamers are a promising class of macromolecules that share similarities to classical biopolymers such as proteins and nucleic acids. Currently, designing novel foldamers is a non-trivial process, often involving many iterations of trial synthesis and characterization until folded structures are observed. In this work, we aim to tackle these foldamer design challenges using computational modeling techniques. We developed CG PyRosetta, an extension to the popular protein folding python package, PyRosetta, which introduces coarse-grained (CG) residues into PyRosetta, enabling the folding of toy CG foldamer models. Although these models are simplified, they can help explore overarching physical hypotheses about how oligomers can form. Through systematic variation of CG parameters in these models, we can investigate various folding hypotheses at the CG scale to inform the design process of new foldamer chemistries. In this study, we demonstrate CG PyRosetta's ability to identify minimum energy structures with a diverse structural search over a range of simple models, as well as two hypothesis-driven parameter scans investigating the effects of side-chain size and internal backbone angle on secondary structures. We are able to identify several types of secondary structures from single- and double-helices to sheet-like and knot-like structures. We show how side-chain size and backbone bond angle both play an important role in the structure and energetics of these toy models. Optimal side-chain sizes promote favorable packing of side chains, while specific backbone bond angles influence the specific helix type found in folded structures.

Antimicrobial nano-assemblies of tryptocidine C, a tryptophan-rich cyclic decapeptide, from ethanolic solutions

Tryptocidine C (TpcC), a Trp-rich cyclodecapeptide is a minor constituent in the antibiotic tyrothricin complex from Brevibacillus parabrevis. TpcC possesses a high tendency to oligomerise in aqueous solutions and dried TpcC forms distinct self-assembled nanoparticles. High-resolution scanning electron microscopy revealed the influence of different ethanol:water solvent systems on TpcC self-assembly, with the TpcC, dried from a high concentration in 15% ethanol, primarily assembling into small nanospheres with 24.3 nm diameter and 0.05 polydispersity. TpcC at 16 μM, near its CMC, formed a variety of structures such as small nanospheres, large dense nanospheroids and facetted 3-D-crystals, as well as sheets and coarse carpet-like structures which depended on ethanol concentration. Drying 16 μM TpcC from 75% ethanol resulted in highly facetted 3-D crystals, as well as small nanospheres, while those in 10% ethanol preparation had less defined facets. Drying from 20 to 50% ethanol led to polymorphic architectures with a few defined nanospheroids and various small nanoparticles, imbedded in carpet- and sheet-like structures. These polymorphic surface morphologies correlated with maintenance of fluorescence properties and the surface-derived antibacterial activity against Staphylococcus aureus over time, while there was a significant change in fluorescence and loss in activity in the 10% and 75% preparations where 3-D crystals were observed. This indicated that TpcC oligomerisation in solutions with 20–50% ethanol leads to metastable structures with a high propensity for release of antimicrobial moieties, while those leading to crystallisation limit active moieties release. TpcC nano-assemblies can find application in antimicrobial coatings, surface disinfectants, food packaging and wound healing materials.

Ni/Co-MOF@aminated MXene hierarchical electrodes for high-stability supercapacitors

Owing to the instability and poor electronic conductivity of redox-active metal–organic frameworks (MOFs), the redox-active MOFs as a direct electrode for achieving fast and high-stability supercapacitors is a significant challenge. Herein, highly redox-active bimetallic Ni/Co metal–organic frameworks (Ni/Co-MOF) is in-situ stabilizied by 2D thin-layer aminated Ti3C2Tx to construct promising hierarchical heterostructural electrodes with superior wettability for high-performance supercapacitors. Benefitting from high conductivity and the good wettability with electrolyte of aminated MXene, the bimetallic Ni/Co-MOF can be uniformly in-situ stabilizied on the aminated MXene surface, thus guaranteeing the superior electronic and ionic transmission from the redox active center of Ni/Co-MOF, and good interfacial compatibility and large contact area. The modified MXene is beneficial to slow down the van der Waals interactions between functional groups to exfoliate the sheet-like structures. For the rapid redox reactions whereas the synergy of highly redox-active Ni/Co in bimetallic Ni/Co-MOF provides a fast redox reaction for Faradaic capacitance. Therefore, as-obtained Ni/Co-MOF@TCT-NH2 presents an ultra-high specific capacitance of 1924 F·g−1 at 0.5 A·g−1 and an ultra-long cycling stability with 10,000 cycles at 10 A·g-1 in a three-electrode system. Besides, the assembled Ni/Co-MOF@TCT-NH2//AC asymmetrical devices exhibit a maximum specific energy density of 98.1 Wh·kg−1 at 600 W·kg−1 and superior rate stability with 15,600 cycles. Such superior electrochemical performance demonstrates that the heterojunction construction of thin-layer aminated MXene to stabilize highly redox-active bimetallic MOFs is an effective strategy for MOFs as a direct electrode to enhance the energy storage.

Swift generator for three-dimensional magnetohydrodynamic turbulence.

Magnetohydrodynamic turbulence is central to laboratory and astrophysical plasmas, and is invoked for interpreting many observed scalings. Verifying predicted scaling law behavior requires extreme-resolution direct numerical simulations (DNS), with needed computing resources excluding systematic parameter surveys. We here present an analytic generator of realistically looking turbulent magnetic fields, that computes three-dimensional (3D) O(1000^{3}) solenoidal vector fields in minutes to hours on desktop computers. Our model is inspired by recent developments in 3D incompressible fluid turbulence theory, where a Gaussian white noise vector subjected to a nonlinear transformation results in an intermittent, multifractal random field. Our B×C model has only few parameters that have clear geometric interpretations. We directly compare a (costly) DNS with a swiftly B×C-generated realization, in terms of its (1) characteristic sheetlike structures of current density, (2) volume-filling aspects across current intensity, (3) power-spectral behavior, (4) probability distribution functions of increments for magnetic field and current density, structure functions, and spectra of exponents, and (5) partial variance of increments. The model even allows to mimic time-evolving magnetic and current density distributions and can be used for synthetic observations on 3D turbulent data cubes.

Characterization and morphometric study of household settled dust: A case study in Dhanbad, the coal capital of India

This study is designed to determine the morphology, elemental composition, and identification of various minerals and functional groups in household dust in multiple locations in Dhanbad, India. Household dust samples were collected from different locations, and samples had been sieved for particle sizes of <75 μm for analysis. For indoor air quality, active PM sampling for each sampling site was done and concentrations of PM10, PM2.5, and PM1 were observed in the range of 31–137, 23–82, and 17–52 μg/m3, respectively. The morphology (FESEM) and elemental analysis (EDX) confirmed the existence of particles with different shapes and compositions in different households. Spherical shape and chain-like structures are indicative of coal combustion inside houses. In contrast, irregular-shaped structures with sharp-edged and sheet-like structures suggest mineral-rich crustal dust in LPG-based houses. Also, soot agglomerates were found in houses nearby roadside from outside vehicular emissions. Energy-dispersive X-ray spectroscopy (EDX) confirmed the relative distribution of elements varied between households and reported that C, O, Mg, Ca, Al, and Si were the primary elements in dust samples collected from various households. The Fourier Transform Infrared (FTIR) peaks for functional groups at various wavelengths such as –C–H, –CC, –CO, –C-X indicates coal dust and their combustion whereas –NH2, –NH4+, –R-SO3− suggests the influence of walking, cleaning, and other household activities. X-ray diffraction (XRD) confirms that minerals such as calcite, vaterite, and quartz were found majorly in roadside houses whereas dolomite, quartz, and hematite were in other sites.

Structure of a subnanometer-sized semiconductor Cd14Se13 cluster

Structure of a subnanometer-sized semiconductor Cd14Se13 cluster

Synthesis and application of MoS2 quantum dots-decorated ZnO nanoparticles for the fabrication of loose nanofiltration membranes with improved filtration, anti-fouling, and photocatalytic performance

MoS2 quantum dots (MoS2 QDs) have recently attracted extremely high consideration owing to their exclusive qualities related to both sheet-like structures and QDs. Doping MoS2 QDs with other semiconductors, such as ZnO nanoparticles (ZnO NPs), has provided superior synergistic effects on their performances. Herein, we constructed mixed matrix loose nanofiltration polyethersulfone (PES) membranes decorated with MoS2 QDs, ZnO NPs, and MoS2 QDs@ ZnO NPs (MNQs) separately, prepared by phase inversion method, for a comprehensive study of filtration, antifouling, and photocatalytic properties. Among all the prepared membranes, the MNQ0.5 membrane provides enhanced properties such as high permeation (15.46 ± 0.75 L/m.2 h. bar which is 11 times greater than control PES), significant rejection performance against Rhodamine B (Rh. B) (˃95 %), excellent photocatalytic activity (2.5 times greater than control PES), and outstanding anti-fouling features (FRR=93.14 %, reversible fouling ratios (Rr)= 39.17 %, irreversible fouling ratio (Rir)= 6.85 %, and total fouling ratio (Rt)= 46.02 %). Besides, the best anti-fouling performance was obtained by the MNQ0.5 membrane in comparison to that of the bare PES one, confirmed via BSA protein permeance.

Three-Dimensional Investigations of Virus-Associated Structures in the Nuclei with White Spot Syndrome Virus (WSSV) Infection in Red Swamp Crayfish (Procambarus clarkii).

Simple SummaryInfections of white spot syndrome virus could be a lethal disease in shrimp culture systems. The 3D structures of the virus-associated structures were obtained through electron tomography. The relationships between the mature and immature particles were connected by the localizations of viral proteins. Our study provided new structural information on the virus through 3D, which extends the limited 2D knowledge of pathogen assembling in the white spot disease, further contributing to the development of a strategy for therapy or prevention.White spot syndrome virus (WSSV) has been reported to cause severe economic loss in the shrimp industry. With WSSV being a large virus still under investigation, the 3D structure of its assembly remains unclear. The current study was planned to clarify the 3D structures of WSSV infections in the cell nucleus of red swamp crayfish (Procambarus clarkii). The samples from various tissues were prepared on the seventh day post-infection. The serial sections of the intestinal tissue were obtained for electron tomography after the ultrastructural screening. After 3D reconstruction, the WSSV-associated structures were further visualized, and the expressions of viral proteins were confirmed with immuno-gold labeling. While the pairs of sheet-like structures with unknown functions were observed in the nucleus, the immature virions could be recognized by the core units of nucleocapsids on a piece of the envelope. The maturation of the particle could include the elongation of core units and the filling of empty nucleocapsids with electron-dense materials. Our observations may bring to light a possible order of WSSV maturation in the cell nucleus of the crayfish, while more investigations remain necessary to visualize the detailed viral–host interactions.

Simultaneous removal of NO and elemental mercury from coal-fired flue gas using natural ferruginous manganese ore at low temperature

Natural ferruginous manganese ore (FMO) was developed as a cost-effective NH3-SCR catalyst for the simultaneous removal of NO and elemental mercury (Hg0) from coal-fired flue gas. The chemical composition, pore structure, crystal structure and surface chemistry of FMO were characterized by different methods. The results showed that FMO was constructed with sheet-like structures. There were massive slit-shaped pores in the FMO. Manganese and iron oxides existed in an amorphous form. After calcination, the NO removal performance of FMO was obviously decreased due to the decomposition of MnO2. A high NH3/NO ratio was conductive to NO removal but excessive NH3 was unnecessary for NO removal. NO could promote Hg0 removal whereas Hg0 had little effect on NO removal. The effects of different SCR atmosphere (inlet, middle layer, and outlet), reaction temperature (100 °C–400 °C), and flue gas composition (O2 and SO2) on NO/Hg0 removal was also studied. At the optimal temperature (200 °C), the NO removal efficiency was greater than 80% and the Hg0 removal efficiency was close to 100%. To some extent, FMO presented preferable SO2 poisoning resistance probably because of the presence of iron oxide. The mechanism of NO/Hg0 removal over FMO was further described. Both fast SCR and conventional SCR reactions happened over FMO during NO removal. Mn4+, Fe3+, and lattice oxygen were first consumed and then replenished by gaseous O2. FMO served as a catalyst for Hg0 oxidation during a long period of denitration process.

Polarization power spectra and dust cloud morphology

Context In the framework of studying cosmic microwave background polarization and characterizing its Galactic foregrounds, the angular power spectrum analysis of the thermal dust polarization map has led to intriguing evidence of an E/B asymmetry and a positive TE correlation. The interpretation of these observations is the subject of theoretical and simulation-driven studies in which the correlation between the density structure of the interstellar medium (ISM) and the magnetic field appears to be a key aspect. In this context, and when the magnetized ISM structures are modeled in three dimensions, dust clouds are generally considered to be filamentary structures only, but both filamentary and sheet-like shapes are supported by observational and theoretical evidence. Aims. We aim to study the influence of the cloud shape and its connection to the local magnetic field, as well as the influence from the viewing angle, on the angular power spectra measured on thermal dust polarization maps; we specifically focus on the dependence of the E/B power asymmetry and TE correlation. Methods. To this end, we simulated realistic interstellar clouds with both filament-like and sheet-like shapes using the software Asterion, which also allowed us to generate synthetic maps of thermal dust polarized emission with an area of 400 square degrees. Then, we computed their polarization power spectra in the multipole range ℓ ϵ [100, 500] and focused on the E/B power asymmetry, quantified through the ℛEB ratio, and the correlation coefficient rTE between Τ and Ε modes. We quantified the dependence of ℛEB and rTE values on the offset angle (between the longest cloud axis and local magnetic field lines) and inclination angle (between the line of sight and the magnetic field) for both types of cloud shapes, either embedded in a regular magnetic field or coupled to a nonregular field to mimic turbulence. Results. We find that both types of cloud shapes cover the same regions of the (ℛEB, rTE) parameter space. The dependence on the inclination and offset angles is similar for both shapes, although sheet-like structures generally show larger scatter than filamentary structures. In addition to the known dependence on the offset angle, we find a strong dependence of ℛEB and rTE on the inclination angle. Conclusions. The very fact that filament-like and sheet-like structures may lead to polarization power spectra with similar (ℛEB,rTE) values complicates their interpretation. We argue that interpreting them solely in terms of filament characteristics is risky, and in future analyses, this degeneracy should be accounted for, as should the connection to the magnetic field geometry. Our results based on maps of 400 square degrees clarify that the overall geometrical arrangement of the magnetized ISM surrounding the observer leaves its marks on polarization power spectra.

The Peel-Blot Technique: A Cryo-EM Sample Preparation Method to Separate Single Layers from Multi-Layered or Concentrated Biological Samples.

The peel-blot cryo-EM grid preparation technique is a significantly modified back-injection method with the objective of achieving a reduction in layers of multi-layered samples. This removal of layers prior to plunge freezing can aid in reducing sample thickness to a level suitable for cryo-EM data collection, improving sample flatness, and facilitating image processing. The peel-blot technique allows for the separation of multilamellar membranes into single layers, of layered 2D crystals into individual crystals, and of stacked, sheet-like structures of soluble proteins to likewise be separated into single layers. The high sample thickness of these types of samples frequently poses insurmountable problems for cryo-EM data collection and cryo-EM image processing, especially when the microscope stage must be tilted for data collection. Furthermore, grids of high concentrations of any of these samples can be prepared for efficient data collection since sample concentration prior to grid preparation can be increased and the peel-blot technique adjusted to result in a dense distribution of single-layered specimen.

Proof of Concept: Interface of Recyclable Organogels with Embedded Palladium Nanoparticles Catalyzing Suzuki-Miyaura Coupling in Water at Room Temperature.

A sustainable approach for C–C cross-coupling reaction at room temperature in water has been developed to avoid tedious Pd separation, reduce the carbon footprint, and save energy. Another important aspect is the catalyst recycling and easy product separation. α,γ-Hybrid peptides were designed to selectively use as a ligand for C–C cross-coupling catalysts as well as to form organogels. The peptides form antiparallel sheet-like structures in the solid state. The peptide containing m-aminobenzoic acid, glycine, and dimethylamine forms a whitish gel in toluene, and co-gelation with Pd(OAc)2 results in light brown gel, which acts as a biphasic catalyst for Suzuki–Miyaura cross-coupling at room temperature in water by mild shaking. The organic–inorganic hybrid gel was characterized by rheology, field-emission scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray analyses. On completion of the cross-coupling reaction, the basic aqueous layer (containing products) above the gel can be simply decanted and the intact organic–inorganic hybrid gel can be recycled by topping-up fresh reactants multiple times. The reaction permitted a range of different substitution patterns for aryl and heterocyclic halides with acid or phenol functional groups. Both electron-donating- and electron-withdrawing-substituted substrates exhibited good results for this transformation. The findings inspire toward a holistic green technology for Suzuki–Miyaura coupling reaction and an innovative avenue for catalyst recycling and product isolation.

Kraft lignin-derived carbon sheets produced by molten salt-assisted thermal treatment – Graphitization behavior of the sheet structures

The synthesis of high-value carbon materials from lignin-based feedstocks to variable applications has been under intensive research. Production of well ordered crystalline carbon as 2H-graphite has been challenging due to the generally poor graphitizability of lignins. Herein, we produced kraft-lignin-derived carbon materials and studied their graphitization behavior. We show that the use of a LiCl-KCl molten salt mixture promoted the formation of sheet-like carbon structures. Furthermore, these structures indicated improved crystallinity after annealing at 700 °C. This was not observed in the case of kraft-lignin annealed without the presence of a salt mixture. These structures were further thermally post-treated at 1900 °C and 2400 °C in an argon atmosphere by induction annealing to study their graphitization tendency. The high-temperature treatment further emphasized the crystalline structure difference between the LiCl-KCl salt-treated and non-LiCl-KCl-treated kraft lignin samples.