Stainless Steel Grid Research Articles

Characterization of Electrochemically Active Bacteria Utilizing Redox Response in Microbial Electrolysis Cell

This study focuses on micro-electrochemical screening to select microbial strains capable of directly transfer electrons to the working electrode dependent on specific enzymatic machinery. The main objective of this work is to select and identify promising strains for allow the bioelectrolysis production of hydrogen. To achieve this goal, microbial composites (artificial biofilms), have been developed using Escherichia coli CGE1 from LCPME. CNRS Fransh, Pseudomonas putrifisciens (CIP 69.13) (CIP, Collection Institut Pasteur, Fransh). Shewanella oneidensis MR-1 (ATCC 700550), and Thiobacillus denitrificans, from (ATCC, American Type Culture Collection), each one enclosed in a matrix carbon nanotubes and protamine matrix, forming an artificial biofilm on buckypaper. Cyclic Voltammetry (CV) measurements were performed over a potential range of +0.4 to -0.7V at 5mV/s under 30°C, using a saturated KCl Ag/AgCl reference electrode and a stainless-steel grid counter electrode. For E. coli and P. putrifisciens, the measurement focused on the oxidation of 20mM glucose, while the former bacteria were growth with and without O2. For S. oneidensis and T. denitrificans the focus was on the reduction of fumarate and 20 mM of NaNOH3+, respectively. As results, E. coli and P. putrifisciens species show no notable electrochemical activity, with no signal of glucose oxidation, due to the absence of type C cytochromes in the cytoplasmic membrane, unlike S. oneidensis and T. denitrificans, that demonstrate a direct electron transfer.

Enhanced Electrochemical Performance in Supercapacitors through KCu-Cy Based Metal-Organic Framework Electrodes.

In the realm of electronics and electric energy storage, the convergence of organic and metallic materials has yielded promising outcomes. In this study, we introduce a novel metal-organic polymer synthesized from Cyamelurate and copper (KCu-Cy) and explore its application as an electrode for a supercapacitor. This material was pressed onto a stainless-steel grid as a thin film and synthesized on nickel foam. Comprehensive characterization was carried out to confirm the synthesis, ensure phase purity, and investigate atomic interactions. Single Crystal X-ray Diffraction (SCXRD) and Powder X-ray Diffraction (PXRD) analyses verified the synthesis and phase purity, shedding light on atomic arrangements. Fourier Transform Infrared Spectroscopy (FTIR) analyses provided insights into characteristic peaks within the material. Thermal Gravimetric Analysis (TGA) gauged stability and durability. Electrochemical performance was assessed through cyclic voltammetry. Notably, the nickel-supported electrodes, devoid of binders, exhibited exceptional specific capacity, reaching 1210.89 F/g at a scan rate of 5 mV/s, in contrast to 363.73 F/g for the pressed thin film on the stainless-steel grid, which incorporated a conductive agent and binder. Cu-Cy displayed impressive cyclization resistance, with a capacity retention of 90 % even after 11000 cycles. These findings underline the promise of Cu-Cy as a high-performance electrode material for supercapacitors, particularly in binder-free configurations, and suggest its potential in advanced energy storage applications.

Визначення швидкості корозії основного конструкційного матеріалу сіток капілярних розділювачів фаз

The subject of this study is the corrosion processes that occur in the fuel tanks of spacecraft with a long service life, the engines of which operate on chemically aggressive fuel components (FC): nitrogen tetroxide (NT) and asymmetric dimethylhydrazine (NDMH). The goal is to determine the reduction of wire diameters and the increase of cell sizes of capillary phase separator grids (PSG) because of the corrosion effect of the main structural material of the 12X18H10T stainless steel grid. Task: establishing the presence, type, and rate of corrosion of the main structural material of the PSG nets. The methods used are as follows: to determine the presence of corrosion by studying the composition of substances found on the surface of the grids – X- ray fluorescence, X- ray structural, atomic absorption, potentiometric, turbodimetric, infrared spectroscopy, and chromato-mass spectrometry; to determine the type of corrosion-metallographic studies of mesh samples; to determine the rate of corrosion-measuring the geometric dimensions of mesh samples. The following results were obtained. The metal cations detected on the surface of the mesh samples correspond to the elements that make up the alloy of aluminum and steel - the main structural materials of the fuel tanks of launch vehicles; 12Х18Н10Т steel is not susceptible to local types of corrosion (pitting, intercrystalline, dot, contact, crevice, and stress corrosion cracking) in high-pressure and low-pressure tanks; the presence of a continuous (uniform) corrosion effect on the surface of the grid wires was established; dependences of changes in the main geometric parameters of the grids (wire diameters and cell sizes) over time were obtained, according to which the limits of the corrosion rates of stainless steel grade 12X18N10T in the liquid phase of NT and NDMG and in the gas phase were established; and coefficients of the maximum corrosion rate were calculated. Conclusions. The scientific novelty of the obtained results is as follows: for the first time, the presence, type, and rate of corrosion of the main structural material of the PSG grids because of their long-term operation (14...31 years) in the liquid phase of AT and NDMH and in the gas phase were determined using cross-methods.

Seismic retrofitting of RC columns using stainless steel grid-reinforced UHPC jackets in plastic hinge zone

This study aims to propose a new seismic retrofitting method for reinforced concrete (RC) columns in buildings with insufficient or flawed design in early standards by locally using stainless steel grid-reinforced ultra-high performance concrete (UHPC) jackets in the plastic hinge zone. For this purpose, pseudo-static loading tests were conducted on four rectangular columns with economical reinforcement ratios, including three retrofitted columns and one traditional RC column, and the effects of the number of stainless steel grid layers and the height of UHPC jackets were investigated. Additionally, a fiber-based finite element model was developed for the retrofitted columns and its accuracy was verified. The influence of other parameters not considered in the experiment, such as the axial compression ratio, UHPC jacket thickness and concrete compressive strength on the seismic performance of the retrofitted columns were also analyzed. The results demonstrated that the proposed retrofitting method effectively improves the seismic behavior of RC columns in a quick and cost-effective manner. The combination of stainless steel grids and UHPC jackets provided stable confinement for the internal RC columns, significantly reducing the damage in the plastic hinge zone and the residual displacements. Compared with the RC column, the ductility, bearing capacity and energy dissipation of the retrofitted columns were enhanced. Especially, the ductility coefficient of the specimens using a two-layer stainless steel grid increased by 27.19 %–36.56 %.

Flame synthesis of Fe3O4/Fe2O3 on stainless steel grid surfaces to improve anodic electrochemical properties

Flame synthesis of Fe3O4/Fe2O3 on stainless steel grid surfaces to improve anodic electrochemical properties

Assessment of nanoplastic extraction from natural samples for quantification purposes

Plastic pollution poses an increasing threat to the whole ecosystem. Scientists recently realized that this pollution also occurs at the nanoscale. Nanoplastic monitoring is a real challenge and published data are scarce. Above the use of appropriate analytical instrument, one main obstacle is to quantitatively isolate the nanoplastic from larger particles in real samples. We propose a method based on the monitoring of polystyrene nanospheres following the polystyrene intrinsic fluorescence to assess the losses. Polymer-based membranes were tested for filtration, ultrafiltration and dialysis; important losses were observed. The isolation of the colloidal fraction is proposed using stainless steel grid with reduction of the losses. The ability of glass fiber filters to trap the nanoplastic was also evaluated as a mean to transfer the particle to the analytical instrument. As an illustration, a river sample was processed with the recommended protocol and the colloidal content monitored by nanoparticle tracking analysis. As a conclusion, we insist on the fact that it is absolutely necessary to evaluate nanoplastic extraction efficiencies for quantification purposes and we give recommendations to limit losses.

A 3D Printed Device for In Vitro Generation of Stratified Epithelia at the Air-Liquid Interface.

Air-liquid interface (ALI) cultures are used to produce stratified epithelial tissues in vitro, notably for the production of oral mucosal equivalents. Currently, there are few purpose-built devices, which aim to enhance the ease and reproducibility of generating such tissue. Most ALI cultures utilize stainless steel grids or cell culture inserts to elevate the matrix or scaffold to the surface of the culture media. In this study, a novel buoyant epithelial culture device (BECD) was designed to both contain a fibroblast-seeded collagen hydrogel and float in culture media, thereby automatically maintaining the ALI without further user intervention. BECDs aim to mitigate several issues associated with ALI culture; reducing the chance of media flooding the epithelial layer from physical disturbance, reducing technique sensitivity for less-experienced users, and improving the reproducibility of the epithelia generated. H400 oral squamous cell carcinoma cells cultured in BECDs for 7, 14, and 21 days showed continuous increase in epithelial tissue thickness with expected localization of epithelial differentiation markers: cytokeratin 5, involucrin, and E-cadherin. Fused filament fabrication three-dimensional printing with polypropylene used in BECD production allows for rapid turnover and design iteration, presenting a versatile, adaptable, and useful tool for application in in vitro cell culture.

Hydrogel Microencapsulation Enhances Cryopreservation of Red Blood Cells with Trehalose.

Cryopreservation of red blood cells (RBCs) plays a vital role in preserving rare blood and serologic testing, which is essential for clinical transfusion medicine. The main difficulties of the current cryopreservation technique are the high glycerol concentration and the tedious deglycerolization procedure after thawing. In this study, we explored a microencapsulation method for cryopreservation. RBC-hydrogel microcapsules with a diameter of approximately 2.184 ± 0.061 mm were generated by an electrostatic spraying device. Then, 0.7 M trehalose was used as a cryoprotective agent (CPA), and microcapsules were adhered to a stainless steel grid for liquid nitrogen freezing. The results show that compared with the RBCs frozen by cryovials, the recovery of RBCs after microencapsulation is significantly improved, up to a maximum of more than 85%. Additionally, the washing process can be completed using only 0.9% NaCl. After washing, the RBCs maintained their morphology and adenosine 5'-triphosphate (ATP) levels and met clinical transfusion standards. The microencapsulation method provides a promising, referenceable, and more practical strategy for future clinical transfusion medicine.

Characterization of Stainless-Steel Grids Dedicated to Cost-Effective Metal-Supported IT-SOFC

Metal-Supported Solid Oxide Fuel Cells (MS-SOFCs) have gained significant interest due to their potential advantages (low-cost, tolerance to redox and thermal cycling, robust and manufacturing) over conventional fuel cells. This work focuses on studying corrosion and electrical conductivity of porous metallic supports (stainless steel 316L and FeCrAl alloy) under different temperatures and atmospheres considering physical, chemical and electrical characterizations. Within the studied operating temperature range (500 °C–700 °C), the FeCrAl support resists to corrosion under air and H2. At temperatures higher than 700 °C it forms a layer of alumina. The FeCrAl resistivity generally remains stable under H2 and slowly increases under air. In contrast, the 316L support is only stable at 500 °C under air and at 500 °C and 600 °C under H2. Above these temperatures, the 316L support shows severe corrosion. The resistivity is stable up to 600 °C, increases strongly for the support under air and slightly for the support under H2 with the temperature increase.

Longitudinal Intravital Imaging Through Clear Silicone Windows.

Intravital microscopy (IVM) enables visualization of cell movement, division, and death at single-cell resolution. IVM through surgically inserted imaging windows is particularly powerful because it allows longitudinal observation of the same tissue over days to weeks. Typical imaging windows comprise a glass coverslip in a biocompatible metal frame sutured to the mouse's skin. These windows can interfere with the free movement of the mice, elicit a strong inflammatory response, and fail due to broken glass or torn sutures, any of which may necessitate euthanasia. To address these issues, windows for long-term abdominal organ and mammary gland imagingwere developed from a thin film of polydimethylsiloxane (PDMS), an optically clear silicone polymer previously used for cranial imaging windows. These windows can be glued directly to the tissues, reducing the time needed for insertion. PDMS is flexible, contributing to its durability in mice over time-up to 35 days have been tested. Longitudinal imaging is imaging of the same tissue region during separate sessions. A stainless-steel grid was embedded within the windows to localize the same region, allowing the visualization of dynamic processes (like mammary gland involution) at the same locations, days apart. This silicone window also allowed monitoring of single disseminated cancer cells developing into micro-metastases over time. The silicone windows used in this study are simpler to insert than metal-framed glass windows and cause limited inflammation of the imaged tissues. Moreover, embedded grids allow for straightforward tracking of the same tissue region in repeated imaging sessions.

Development of a Continuous Photo-catalytic/Ozonation System: Application on Amido Black Removal from Water

ABSTRACT A continuous system for photo-catalytic/ozonation was designed at laboratory scale and evaluated for water treatment using Amido Black 10B dye (AB) as a pollutant model. The effect of single ozonation (O3), photolytic ozonation (UV/O3) and combined photocatalytic/ozonation treatment (UV/O3/TiO2) were investigated. TiO2 nanocatalysts films were coated on stainless steel grids (AISI 304) by Atomic Layer Deposition technique (ALD) at 350 °C. An experimental hydrodynamic study of the designed reactor was conducted based on dry and total pressure drop. Three flow regimes were observed by increasing the total pressure drop against gas load factor (Fs). Depollution experiments conducted on the developed reactor showed that reaction rates and efficiency of studied processes were dependent on the studied operational parameters (initial dye concentration, ozone dose, pH). The maximum AB dye ([AB]0 = 100 mg. L−1) conversion efficiency, using the designed (UV/O3/TiO2) system, was about 40.3% of initial TOC and 100% AB color removal was achieved within 10 min at an optimal ozone dose of 132 mg. L−1. A significant improvement in AB removal using UV/TiO2/O3 process (koverall = 0.056 min−1, 40.3%) compared to O3 alone (koverall = 0.032 min−1, 26.87). Results shows also that the addition of tert-butanol (TB), as radical scavenger ([TB] = 0.2 M and 0.4 M), greatly affects the reaction mechanisms of a photocatalytic ozonation process within 5 min of reaction, by decreasing the Amido Black conversion from 99.67% ([TB] = 0 M) to 74.63% and 31.35%, respectively, in presence of 0.2 M and 0.4 M of tert-butanol. The remarkable decrease in AB removal rate observed in the presence of a radical scavenger expresses that there was an obvious enhancement of hydroxyl radical OH• generation due to the synergetic effect between ozone and photocatalytic processes.

Photocatalytic ozonation in an immersion rotary body reactor for the removal of micro-pollutants from the effluent of wastewater treatment plants

Abstract Carrier-bound titanium dioxide catalysts were used in a photocatalytic ozonation reactor for the degradation of micro-pollutants in real wastewater. A photocatalytic immersion rotary body reactor with a 36-cm disk diameter was used, and was irradiated using UV-A light-emitting diodes. The rotating disks were covered with catalysts based on stainless steel grids coated with titanium dioxide. The dosing of ozone was carried out through the liquid phase via an external enrichment and a supply system transverse to the flow direction. The influence of irradiation power and ozone dose on the degradation rate for photocatalytic ozonation was investigated. In addition, the performance of the individual processes photocatalysis and ozonation were studied. The degradation kinetics of the parent compounds were determined using liquid chromatography tandem mass spectrometry. First-order kinetics were determined for photocatalysis and photocatalytic ozonation. A maximum reaction rate of the reactor was determined, which could be achieved by both photocatalysis and photocatalytic ozonation. At a dosage of 0.4 mg /mg DOC, the maximum reaction rate could be achieved using 75% of the irradiation power used for sole photocatalysis, allowing increases in the energetic efficiency of photocatalytic wastewater treatment processes. The process of photocatalytic ozonation is suitable to remove a wide spectrum of micro-pollutants from wastewater.

Abstract LB250: Development of organoid raft cultures of cervical, breast and glioblastoma tumors as quick economical ex vivo human cancer models for pre-clinical drug evaluation

Abstract Background: In the past few years, 3D organoid cultures of patient-derived tumors or patient-derived xenografts have gained significant attention as faster and more economical ex vivo alternatives to animal models for the pre-clinical evaluation of therapeutics. We reported previously that raft cultures of ex vivo epithelial warts, normal human epithelia from various anatomic sites, as well as cancer cell lines (cervical and melanoma) grown at the liquid:air interface recapitulate parental tissue phenotypes. Here we describe adaptation of the above technique to develop Organoid Raft Culture (ORC) of tumors of various origin and validation as preclinical models for drug evaluation. Methods: A stromal equivalent (SE) consisting of buffered rat-tail collagen and J2 mouse fibroblasts was prepared in 24-well tissue culture plates. Freshly harvested tumors from patients or patient-derived xenografts of cervical cancers were minced to <2 mm pieces, mixed with buffered rat tail collagen mixture, assembled on the SE and cultured submerged for 2 days in simple raft culture media (DMEM, F12, 10% FBS, growth factors). This assembly was then raised on stainless steel grids in a 6-well plate and cultured at liquid:air interface for variable times (10 days to over 2-3 months). Tumors were harvested, formalin-fixed and paraffin-embedded for analyses by histology and immunohistochemistry. Results: The cervical ORCs maintained the heterogeneity of the parental tumor or xenografts. We evaluated cytotoxicity of vorinostat and CFI402257 on ORCs of cervical cancer-derived PDX models by TUNEL assays and immunohistochemistry. The ex-vivo data was validated in experiments with the in vivo PDXs of cervical cancers. We also successfully developed ORCs of mouse xenografts of syngeneic breast tumor cell lines, and organoids from glioblastomas. Conclusions: Organoid Raft Cultures of patient- or mouse-derived tumors and xenografts of cervical, breast and glioblastoma, recapitulate the morphology of parent tumors, can be passaged multiple times, are suitable for bio-banking and expedite drug evaluation. This method does not require costly growth components and multiple cultures could be easily performed. The PDX derived ORC platform would allow rapid evaluation of drug candidates against many types of solid tumors. Acknowledgement: R21CA216789 grant to NSB. Citation Format: Nilam Sanjib Banerjee, Dianne W. Moore, Abhisek Gangrade, Donald J. Buchsbaum, Luise Burt Nabors, Thomas R. Broker, Louise T. Chow. Development of organoid raft cultures of cervical, breast and glioblastoma tumors as quick economical ex vivo human cancer models for pre-clinical drug evaluation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB250.

Abstract LB249: Development of 3D organoid raft cultures of colon cancer as a model to screen the therapeutic efficacy of PRIMA-1Met (APR-246)

Abstract Background: Cancer is among the leading causes of death worldwide. Hence, new drugs and faster screening models are needed. However, costly experiments for determining the therapeutic efficacy of drugs in animals before they reach clinical trials make the process difficult. To address this issue, we developed an alternative strategy to screen drugs against human tumors. 3D tumor organoids are termed Organoid Raft Cultures (ORCs) due to the strategy involved in culturing tumors ex vivo on collagen beds with grid supports to maintain their morphological structure and molecular makeup. Methodology: After receiving informed consent of patients and IRB approval at the University of Alabama at Birmingham, patients with histologically confirmed colon cancers were recruited. Portions of collected colon tumors were then implanted into the flanks of mice to generate Patient-Derived Xenografts (PDXs). Once their volumes reached 2000 mm2, tumors were excised, and ORCs were generated. This approach addresses two concerns: 1) how well are the morphological features retained when the tumors are grown ex vivo, and 2): can we accomplish faster screening of the efficacy of drugs. In the present study, we used a tumor in which we identified, by DNA-sequencing, a TP53 missense mutation at amino acid R248Q (a change from arginine to glutamine). We tested PRIMA-1Met (APR-246), an agent that reactivates mutant p53 by causing a conformational change and restores its function as a tumor suppressor. Excised xenograft tumor tissue was cut into small pieces and seeded on mucosa-stromal equivalent consisting of buffered collagen and fibroblasts in 24-well plates and allowed to grow for 2-3 days. Next, the tissue assembly was detached and placed on raft shaped stainless steel grids in 6-well plates containing ORC media. These cultures, termed ORCs, were then divided into groups of APR-246 treated and untreated. After 7 days, tissues were formalin fixed, and slides of 5-micron thickness were cut for Hematoxylin and eosin (H&E), p53 and TUNEL staining. Results: H&E staining of PDXs and ORCs showed the normal glandular morphology of colon cancers. This conventional characteristic of adenocarcinoma was retained along with other morphologic features, indicating the usefulness of ORCs. Additionally, comparisons of p53 and TUNEL staining of untreated vs APR-246-treated ORCs showed that lack of nuclear accumulation of mutant p53 in this p53 mutant tissue and induced apoptosis by APR-246 treatment, indicating the efficacy of the drug and the usefulness of the ORCs as alternative screening model. Conclusion: ORCs are economical and will be useful for screening new drugs/therapies ex vivo, allowing faster drug screening and thus moving new agents to clinical trials. This work was supported in part by the ELKUS foundation. (*Equal contributing first coauthors) Citation Format: Sanjib Nilam Banerjee, Prachi Bajpai, Amr Elkholy, Dianne W. Moore, Hyung Gyoon Kim, Sumit Agarwal, Michael Behring, Sameer Al Diffalha, Upender Manne. Development of 3D organoid raft cultures of colon cancer as a model to screen the therapeutic efficacy of PRIMA-1Met (APR-246) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB249.

Damage-based finite-element modelling of in-plane loaded masonry walls repaired with FRCM

An empirical study of masonry wall repair is presented in the current work. The textile reinforced mortar used for repair comprises a stainless-steel grid embedded in a cement matrix. This composite was applied locally and along the cracks, on a previously damaged unreinforced masonry wall. The repaired wall was then subjected to a pushover load until its maximal strength was reached. Results of the damaged and repaired configurations indicate that recovery, and even a gain of initial stiffness and strength, was achieved. Finite-element simulations of the unreinforced and repaired walls were then carried out with an innovative approach to the repair modelling. The main features of the experimental Unreinforced Masonry Wall were reproduced. Finally, simulations of the repaired wall were generated to assess the gain in strength for several degrees of wall damage. Using this model, the crack patterns were investigated and the effects of different repair configurations are discussed.

New Composite Material for Masonry Repair: Mortar Formulations and Experimental Studies.

The need for retrofitting existing masonry structures is progressively becoming more important due to their continuous deterioration or need to meet the current design requirements of Eurocodes. Textile-Reinforced Mortar (TRM) composite systems have emerged as a sustainable repair methodology suitable for structure retrofitting. Nevertheless, their mechanical performance is still far from being fully investigated. This paper presents an experimental study on the tensile and bond behaviors of a new mortar-based composite consisting of mineral additives, blended cement mortar, and stainless-steel grid. Three different mineral additives (silica fume, fly ash, and blast furnace slag), in binary and ternary systems were used. The experimental study included uniaxial tensile coupon testing on composite specimens and bond tests on composite material applied to clay-brick substrate. The results obtained with the different textile-reinforced cement-based mortars were compared and are discussed here. It was found that, for mortar formulations containing mineral additives—such as fly ash or blast-furnace slag—with high tensile and bond strengths, an adequate adherence between the constituents was obtained. The developed mortar presents mechanical performances equivalent to traditional mortars without additives. The study contributes to the existing knowledge regarding the structural behavior of TRM and promotes the development of a low impact carbon cementitious matrix.

Surface barrier discharge pre-sowing treatment of winter wheat seeds in a three-electrode arrangement with dc bias

In the present work, the experimental results of reaction of morphological indicators (sprout and root length, number of roots, 3-day germination) of seedlings of high quality winter wheat seeds treated by plasma byproducts in the three-electrode system of surface dielectric barrier discharge with dc bias on the third electrode in humid air of atmospheric pressure at different polarity of the bias voltage are shown. The treatment was carried out for 15 min in a strip electrode system (eight 1 mm width strips with 4 mm distance between them, a sinusoidal voltage of 2.7 kV (rms) with a frequency 23 kHz) made on a corundum ceramic barrier (1 mm thickness) with the additional third electrode which is a stainless steel grid distant 10 mm from the surface of the dielectric barrier. Direct-current bias of 8 kV of positive or negative polarity was applied to the third electrode. Seeds were located on the surface of the third electrode. The treatment was also carried out with vibration of the system (the imitation of seeds movement along the third electrode). It is shown that the efficiency of treatment depends on the month of carrying it out. It was succeeded to get a reliable stimulation with weak control. With strong control (potential sowing months) it was not obtained. The imposing of dc bias in any considered case is less efficient than plasma products affection without bias. The vibration of electrode system leads to seeds damage during the treatment and notable germination reduction.

Antibacterial Efficiency of Stainless-Steel Grids Coated with Cu-Ag by Thermionic Vacuum Arc Method

Autonomous smart natural ventilation systems (SVS) attached to the glass façade of living quarters and office buildings can help reducing the carbon footprint of city buildings in the future, especially during warm seasons and can represent an alternative to the conventional mechanical ventilation systems. The work performed in this manuscript focuses on the investigation of bacteria trapping and killing efficiency of stainless steel grids coated with a mixed layer of Cu-Ag. These grids are to be employed as decontamination filters for a smart natural ventilation prototype that we are currently building in our laboratory. The tested grids were coated with a mixed Cu-Ag layer using thermionic vacuum arc plasma processing technology. The fixed deposition geometry allowed the variation of Cu and Ag atomic concentration in coated layers as a function of substrate position in relation to plasma sources. The test conducted with air contaminated with a pathogen strain of staphylococcus aureus indicated that the filtering efficiency is influenced by two parameters: the pore size dimension and the coating layer composition. The results show that the highest filtering efficiency of 100% was obtained for fine pore (0.5 × 0.5 mm) grids coated with a mixed metallic layer composed of 65 at% Cu and 35 at% Ag. The second test performed only on reference grids and Cu-Ag (65–35 at%) under working conditions, confirm a similar filtering efficiency for the relevant microbiological markers. This particular sample was investigated from morphological, structural, and compositional point of view. The results show that the layer has a high surface roughness with good wear resistance and adhesion to the substrate. The depth profiles presented a uniform composition of Cu and Ag in the layer with small variations caused by changes in deposition rates during the coating process. Identification of the two metallic phases of the Cu and Ag in the layers evidences their crystalline nature. The calculated grain size of the nanocrystalline was in the range 14–21 nm.

Zirconia implants with improved attachment to the gingival tissue.

Gingival tissue attachment is known to be important for long-term prognosis of implants. This in vitro study evaluated the gingival attachment to zirconia implants and zirconia implants modified with sol-gel derived TiO2 coatings. Zirconia endodontic posts (n=23) were used to function as implants that were inserted into the center of full-thickness porcine gingival explants (n=31). The tissue/implant specimens were then individually placed at an air/liquid interface on a stainless-steel grid in cell culture wells containing a nutrient solution. The tissue cultures were incubated at 37°C in a 5% CO2 environment and at days 7 and 14, the specimens were harvested and analyzed by dynamic mechanical analysis (DMA) measurements under dynamic loading conditions mimicking natural mastication. Specimens were also analyzed by immunohistochemical staining identifying the laminin (Ln) γ2 chain specific for Ln-332, which is known to be a crucial molecule for the proper attachment of epithelium to tooth/implant surface. Tissue attachment to TiO2 -coated zirconia demonstrated higher dynamic modulus of elasticity and higher creep modulus, meaning that the attachment is stronger and more resistant to damage during function over time. Laminin γ2 was identified in the attachment of epithelium to TiO2 -coated zirconia. Both DMA and histological analysis support each other, so the gingival tissue is more strongly attached to sol-gel derived TiO2 -coated zirconia than uncoated zirconia. Immunohistochemical staining showed that TiO2 coating may enhance the synthesis and deposition of Ln-332 in the epithelial attachment to the implant surface.

Axial behavior of reinforced concrete column with ultra-high performance concrete stay-in-place formwork

This paper presents the experimental and numerical study on the axial compressive behavior of a novel composite column that consists of a prefabricated grid-reinforced ultra-high performance concrete (UHPC) stay-in-place (SIP) formwork and post-cast concrete. Eight specimens, including six composite columns and two reinforced concrete columns were tested. The test variables included the type and number of grid layers as well as the thickness of UHPC formwork. According to the test results, the composite columns showed both higher axial load carrying capacity and elastic modulus, whereas the brittle nature of UHPC caused a decrease in ductility and toughness. The use of carbon fiber reinforced polymer (CFRP) grid could provide a more sufficient lateral confinement than stainless steel (SS) grid to achieve a strain hardening behavior and thus increased the ductility and toughness of the specimens. The use of more layers of SS grids could also have a positive effects on brittleness reduction. Furthermore, an analytical model was developed using a finite element (FE) program to simulate axial compressive response of the column. The whole failure process of the composite column and almost all the key characteristics of the load-strain curves were reasonably captured, and a good agreement was found between the calculated and measured load-strain curves, indicating the capability of the proposed FE model to predict the axial compressive behavior of the composite columns.