Highly bioactive and low cytotoxic Si-based NiOOH nanoflowers targeted against various bacteria, including MRSA, and their potential antibacterial mechanism

With the emergence of new drug-resistant microorganisms, the development of effective antimicrobial agents is urgently required. Core-shell-structured nanomaterials have received considerable attention as antibacterial agents. We prepared a bioactive core-shell-structured silicon-based NiOOH nanoflower (Si@NiOOH) targeted against various bacteria using a modified chemical bath deposition method. Further, we investigated its potential antibacterial mechanism by evaluating electrochemical properties in a redox reaction with ascorbic acid, measuring metal ion release, and analyzing the surface area. The bactericidal rate of Si@NiOOH at 200 μg/mL towards Pseudomonas aeruginosa, Klebsiella pneumoniae, and methicillin-resistant Staphylococcus aureus was as high as 99.9%. Si@NiOOH maintained its original morphology after killing the bacteria and exhibited negligible cytotoxicity towards mouse embryonic fibroblasts. The excellent antibacterial activities of Si@NiOOH are possibly derived from its high surface area, providing a wide active site attached to the cell wall, and the high oxidative potency of the Ni(III) cations existing on its surface. The high antibacterial activity and low cytotoxicity of the nanoflower make it a promising tool for promoting wound healing and for use with medical devices and implants. © 2021 The Korean Society of Industrial and Engineering Chemistry1

Fabrication of Lanthanum Strontium Cobalt Ferrite–Gadolinium-Doped Ceria Composite Cathodes Using a Low-Price Inkjet Printer

In this work, we have successfully fabricated lanthanum strontium cobalt ferrite (LSCF)–gadolinium-doped ceria (GDC) composite cathodes by inkjet printing and demonstrated their functioning in solid oxide fuel cells (SOFCs). The cathodes are printed using a low-cost HP inkjet printer, and the LSCF and GDC source inks are synthesized with fluidic properties optimum for inkjet printing. The composition and microstructure of the LSCF and GDC layers are successfully controlled by controlling the color level in the printed images and the number of printing cycles, respectively. Anode-support type SOFCs with optimized LSCF–GDC composite cathodes synthesized by our inkjet printing method have achieved a power output of over 570 mW cm^–2 at 650 °C, which is comparable to the performance of a commercial SOFC stack. Electrochemical impedance analysis is carried out to establish a relationship between the cell performance and the compositional and structural characteristics of the printed LSCF–GDC composite cathodes

Structural Analyses of Phase Stability in Amorphous and Partially Crystallized Ge-Rich GeTe Films Prepared by Atomic Layer Deposition

The local bonding structures of Ge<i>_x</i>Te_1–<i>x</i> (<i>x</i> = 0.5, 0.6, and 0.7) films prepared through atomic layer deposition (ALD) with Ge­(N­(Si­(CH₃)₃)₂)₂ and ((CH₃)₃Si)₂Te precursors were investigated using Ge K-edge X-ray absorption spectroscopy (XAS). The results of the X-ray absorption fine structure analyses show that for all of the compositions, the as-grown films were amorphous with a tetrahedral Ge coordination of a mixture of Ge–Te and Ge–Ge bonds but without any signature of Ge–GeTe decomposition. The compositional evolution in the valence band electronic structures probed through X-ray photoelectron spectroscopy suggests a substantial chemical influence of additional Ge on the nonstoichiometric GeTe. This implies that the ALD process can stabilize Ge-abundant bonding networks like −Te–Ge–Ge–Te– in amorphous GeTe. Meanwhile, the XAS results on the Ge-rich films that had undergone post-deposition annealing at 350 °C show that the parts of the crystalline Ge-rich GeTe became separated into Ge crystallites and rhombohedral GeTe in accordance with the bulk phase diagram, whereas the disordered GeTe domains still remained, consistent with the observations of transmission electron microscopy and Raman spectroscopy. Therefore, amorphousness in GeTe may be essential for the nonsegregated Ge-rich phases and the low growth temperature of the ALD enables the achievement of the structurally metastable phases

Growth and yield of a tropical rainforest in the Brazilian Amazon 13 years after logging

Successive inventories of a silvicultural experiment in terra firme rain forest within the Tapajós National Forest in the Brazilian Amazon are examined to provide guidelines for operational forest management on a sustainable basis. The experiment was logged in 1979 without additional silvicultural treatment, but included protection from further logging and encroachment (`log and leave'). Thirty six permanent plots established in 1981 were remeasured in 1987 and 1992. Logging changed the canopy structure and altered the composition of the stand, reducing the number of shade tolerant species and stimulating light demanding species. There was a net increase in stem number and stand basal area during the 11 year observation period, and this trend also holds for most of the individual species. The stand basal area 13 years after logging was about 75% of that in a comparable unlogged forest. Logging stimulated growth, but this effect was short lived, lasting only about 3 years, and current growth rates are similar to those in the unlogged forest. Between the first and second remeasures, average diameter increment decreased from 0.4 to 0.2 cm year-1, mortality remained relatively constant at 2.5% year-1, while recruitment (at 5 cm diameter at breast height) decreased from 5 to 2%. Total volume production declined from approximately 6 to 4 m3 ha-1 year-1, while commercial production remained about 0.8 m3 ha-1 year-1. New commercial species increased the commercial volume in 1992 from 18 to 54 m3 ha-1, and the increment to 1.8 m3 ha-1 year-1. Results from this experiment provide the first quantitative information for management planning in the Tapajós Forest, and may guide the choice of cutting cycle and annual allowable cut. Silvicultural treatment to stimulate growth rates in forest areas zoned for timber production should be considered as a viable management option. Extrapolations of these results to an anticipated 30-35 year cutting cycle must be interpreted with caution. Ongoing remeasurement and analysis of these and other plots over the next 30 years or more are necessary to provide a stronger basis for management inferences

EW-7197 eluting nano-fiber covered self-expandable metallic stent to prevent granulation tissue formation in a canine urethral model - Fig 1

<p>Representative optical images of (A) Nanofiber-covered, self-expandable metallic stent and (B) scanning electron micrographs of EW-7197 loaded nanofibers. The scale bars are 30 μm and 10 μm.</p

EW-7197 eluting nano-fiber covered self-expandable metallic stent to prevent granulation tissue formation in a canine urethral model - Fig 5

<p>Representative microscopic images (hematoxylin and eosin staining magnification × 2 [A,B] and Masson’s trichrome staining magnification × 5 [C,D]) of histological sections at 8 weeks after stent placement. The thickness of papillary projection (arrows) was significantly increased in the CS group (A) compared to the DS group (B). Arrowhead = stent struts (A,B). The degree of collagen deposition (arrowheads) was significantly greater in the CS group (C) than the DS group (D). The number of epithelial layers (arrows) in the CS group (C) was significantly higher than the DS group (D). CS: control stent, DS: drug stent.</p

Retrograde urethrographic findings after stent placement in canine urethra.

<p>Retrograde urethrographic findings after stent placement in canine urethra.</p

Locations of tissue sampled for histological examination.

<p>The canine urethra consists of the proximal pelvic urethra (arrows) and the distal cavernous urethra (arrowheads). (A) Retrograde urethrography of the canine urethra immediately after stent placement. (B) Schematic image showing the locations of tissue samples where a stent was present.</p