Chirality is widely expressed in organic materials, perhaps most notably in biological molecules such as DNA, and in proteins, owing to the homochirality of their components (d-sugars and l-amino ...acids). But the occurrence of large-scale chiral pores in inorganic materials is rare. Although some progress has been made in strategies to synthesize helical and chiral zeolite-like materials, the synthesis of enantiomerically pure mesoporous materials is a challenge that remains unsolved. Here we report the surfactant-templated synthesis of ordered chiral mesoporous silica, together with a general approach for the structural analysis of chiral mesoporous crystals by electron microscopy. The material that we have synthesized has a twisted hexagonal rod-like morphology, with diameter 130-180 nm and length 1-6 µm. Transmission electron microscopy combined with computer simulations confirm the presence of hexagonally ordered chiral channels of 2.2 nm diameter winding around the central axis of the rods. Our findings could lead to new uses for mesoporous silica and other chiral pore materials in, for example, catalysis and separation media, where both shape selectivity and enantioselectivity can be applied to the manufacturing of enantiomerically pure chemicals and pharmaceuticals.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background
Acquired digital fibrokeratoma (ADFK) is an uncommon benign fibro‐epithelioma, which is rarely reported in China.
Aims
To analysis the clinical features of ADFK in Chinese people from ...current cases.
Methods
From December 2019 to October 2021, there were 21 patients diagnosed with ADFK, we made a retrospective analysis on the clinical features of skin lesions in them. To summarize the clinical morphology, location, and surgical follow‐up of ADFK.
Results
We concluded that ADFK is more common in females than males on the hands (7:3), while the male‐to‐female ratio is largely the same in feet (6:5). It occurs more frequently on the third finger (60%) and first toe (45.5%). As to clinical morphology, it is typically rod‐shaped (52.4%), followed by dome‐shaped (42.8%) and wart‐shaped (4.8%). It is typically dome‐shaped on the hands (80%) and rod‐shaped on the feet (81.8%). In terms of location on the fingers (toes), such skin lesions are most common at the proximal nail fold (52.4%), which can also occur at the nail matrix (14.3%), periungual area (23.8%), and subungual area (9.5%). Nevertheless, this ratio also varies on the hands and feet. All patients got surgical excision of the skin lesion, who were followed up for 6–12 months, without recurrence.
Conclusions
Most ADFKs are associated with trauma, whose clinical features are related to location and gender. ADFKs on the hands are different from those on the feet regarding clinical morphology and location on fingers (toes), and surgery is effective in treating this condition.
Hedychium coronarium Koen is a perennial flowering plant that has ornamental, nutritional and medicinal value. In October 2019, root rot symptoms were observed in fields of H. coronarium in Yunnan ...Province, China. Fungal isolates were obtained from the diseased samples and the pathogenicity was confirmed by fulfilling Koch's postulates using wounded and unwounded plant inoculations. The pathogen was identified as Ceratobasidium sp. (binucleate Rhizoctonia) through morphological characterization and anastomosis grouping as well as sequence analysis of both rDNA-ITS and EF-1α. To our knowledge, this is the first report of Ceratobasidium sp. AG-I (binucleate Rhizoctonia) causing root rot on H. coronarium.
We have used environmental scanning electron microscope to observe vapor condensation and liquid water morphology and breakthrough in porous layers of polymer electrolyte membrane fuel cell. These ...suggest presence of large droplets and high liquid saturation at interface of the catalyst layer (CL) and gas diffusion layer (GDL), due to jump in pore size. We develop a model for morphology of liquid phase across multiple porous layers by use of both continuum and breakthrough (percolation) treatments. Using the results of this model we show the liquid morphologies deteriorate the efficiency of electrochemical reactions in CL and increase the water saturation in GDL. Then we show that inserting a microporous layer between CL and GDL reduces both the droplet size and liquid saturation and improves the cell performance.
Cast films of a high molecular weight linear polypropylene (L-PP) were prepared by extrusion followed by stretching using a chill roll. An air knife was employed to supply air to the film surface ...right at the exit of the die. The effects of air cooling conditions, chill roll temperature, and draw ratio on the crystalline orientation, morphology, mechanical and tear properties of the PP cast films were investigated. The crystallinity and crystal size distribution of the films were studied using differential scanning calorimetry (DSC). It was found that air blowing on the films contributed significantly to the uniformity of the lamellar structure. The orientation of crystalline and amorphous phases was measured using wide angle X-ray diffraction (WAXD) and Fourier transform infrared (FTIR). The amount of lamellae formation and long period spacing were obtained via small angle X-ray scattering (SAXS). The results showed that air cooling and the cast roll temperature have a crucial role on the orientation and amount of lamellae formation of the cast films, which was also confirmed from scanning electron microscopy (SEM) images of the films. Tensile properties and tear resistance of the cast films in machine and transverse directions (MD and TD, respectively) were evaluated. Significant increases of the Young modulus, yield stress, tensile strength, and tensile toughness along MD and drastic decreases of elongation at break along TD were observed for films subjected to air blowing. Morphological pictograms are proposed to represent the molecular structure of the films obtained without and upon applying air cooling for different chill roll temperatures. Finally, microporous membranes were prepared from annealed and stretched films to illustrate the effect of the PP cast film microstructure on the morphology and permeability of membranes. The observations of SEM surface images and water vapor transmission rate of the membranes showed higher pore density, uniform pore size, and superior permeability for the ones obtained from the precursor films prepared under controlled air cooling.
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CaSnO3 nanopowders had been successfully synthesized via a reverse microemulsion method. The effects of hexadecyltrimethylammonium bromide and polyoxyethylene octyl phenyl ether as surfactants on the ...size and morphology of the particles were also investigated. The synthesized products were systematically studied by X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (DTA–TG), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The results showed that the kind of surfactants has an important effect on the average size and morphology of the particles.
► We highlight current knowledge on the lithium iron phosphate (LiFePO4). ► We analyze the methods used, and situations in which LiFePO4 have been investigated. ► Approaches to improve the ...performance of LiFePO4 is discussed. ► Future research on LiFePO4 cathode material is pointed out.
The cathode materials of lithium-ion batteries are developing towards the direction of high energy density, long cycle life, low cost and environment friendly. As a potential ‘green’ cathode material for lithium-ion power batteries in the 21st century, olivine-type lithium iron phosphate (LiFePO4) become more attractive recently for its high theoretical capacity (170mAhg−1), stable voltage plateau of 3.5V vs. Li/Li+, good stability both at room temperature and high temperature, excellent cycling performance, high safety, low raw material cost, no pollution, and rich source of raw materials, etc. This paper introduces the research progress in recent years on the structure and performance, synthesizing methods, carbon-coating, ion-doping and particle size control. Furthermore, the prospect of LiFePO4 cathode material for the lithium-ion batteries is reviewed. (i) Preparation process of LiFePO4 (including high temperature solid-phase method, sol–gel method, microwave method, hydrothermal method, carbothermal reduction method, spray pyrolysis method and other synthesis routes). (ii) Progress on modification of LiFePO4 (three modification strategies including carbon coating, metal particle or ion doping and the optimization of the particle size and morphology). (iii) Finally, the trend of research and development of LiFePO4 is also pointed out (the follow-up studies should be directed at the theoretical study and process improvement).
•Grassmann manifold–angular central Gaussian distribution for signal segmentation.•A new wavelet transform – ensemble empirical mode decomposition is designed.•An unsupervised feature fusion method ...is proposed to reduce the feature dimension.•An effective fault classification framework is proposed and validated by experiments.
Accurate and efficient rotating machinery fault diagnosis is crucial for industries to guarantee the productivity and reduce the maintenance cost. This paper systematically proposes a new fault diagnosis approach including signal processing techniques and pattern recognition method. In order to reveal more useful details in a fault residing signal, a novel automatic signal segmentation method named Grassmann manifold – angular central Gaussian distribution is proposed to divide a raw signal into several segments, resulting in a significant improvement of diagnosis accuracy. An improved empirical mode decomposition, wavelet transform – ensemble empirical mode decomposition, is also designed which could adequately solve the problems of mode mixing and end effects. Moreover, a morphological method usually used in image processing is investigated and adopted to change the shape of the intrinsic mode functions to further reveal the faulty impulses. In order to reduce the high dimension of the extracted features and improve the computational efficiency and accuracy, a deep belief network is designed to conduct information fusion, and compared with widely adopted kernel principal component analysis. For classification, a pairwise coupling strategy is proposed and combined with sparse Bayesian extreme learning machine. The experiments conducted using the proposed approach demonstrate the effectiveness of the proposed system.
Polyethersulfone (PES) membranes are prevalent in the field of water treatment owing to their exceptional separation efficiency, robust mechanical properties, and resistance to chemical degradation. ...Nevertheless, these membranes are prone to fouling, resulting in a decrease in both flux and ultrafiltration efficiency. In the present study, PES membranes are blended with poly (3‐Sulfopropyl Methacrylate) (PSPMA) in various weight percentages (0%–3%) to improve their antifouling and ultrafiltration properties. The physicochemical properties of the blended membranes, including surface morphology, contact angle, hydrophilicity and surface energy are evaluated. The findings indicate that incorporation PSPMA results in an enhancement of the hydrophilic properties and surface charge of the PES membranes, assessed by employing Bovine Serum Albumin (BSA) as a representative protein. Modified blended membranes display greater Flux Recovery Ratio (FRR%) and exhibit superior fouling resistance. Under the same experimental conditions (0.2 MPa applied pressure), a pure water flux of 154.18 L·m−2·h−1 for PES/PSPMA membrane found substantially greater than pure PES membrane (103.52 L·m−2·h−1) along with Total Fouling Ratio (TFR) of 36% and 64.9% respectively. Exceptional antimicrobial efficacy for modified membranes is revealed against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) using disc diffusion technique rendering them well‐suited for water treatment applications.
