Presence Of Inorganic Particles Research Articles

In-situ monitoring of multi-physical dynamics in ceramic additive manufacturing

Ceramic additive manufacturing is an innovative technology for developing complex ceramic structures, while a direct understanding of the physical phenomena occurring in sequential layers remains challenging, affected by the material design such as the presence of inorganic particles and their contents. This study provides a direct analysis of how the ceramic particles influence fabrication behavior utilizing an in-situ monitoring system. The force profile provides immediate feedback on fractures and geometric design, with the fluctuation in force directly corresponding to specific structural characteristics and stability during the fabrication. Furthermore, the multi-physical dynamics was investigated with a unit signal based on the effect of ceramic on the rheological-curing-mechanical behavior. For example, the mechanical behavior was characterized in real-time, as shown through an intensified peak of 6.6 kPa during the manufacturing of a ceramic composite, a 5.6 times increase compared to pure resin. The monitored data quantified the geometric dynamics and the multi-physical mechanism in real-time, achieved from the data on the overall fabrication status and the unit signal analysis of continuous manufacturing. This method can improve the reliability of ceramic additive manufacturing by providing insight into how ceramics impact fabrication behavior on sequential layers in real-time.

Imparting Photocatalytic and Antioxidant Properties to Electrospun Poly(L-lactide-co-D,L-lactide) Materials.

The focus of the present study is on the fabrication of effective and eco-friendly hybrid electrospun materials based on poly(L-lactide-co-D,L-lactide) (PLDLLA), Fe3O4 and ZnO with an appropriate design for antioxidant and photocatalytic performance. The design of the fibrous materials was purposely tailored in one step by electrospinning and simultaneous electrospinning/electrospraying. Electrospinning of PLDLLA and its mixture with Fe3O4 resulted in the fabrication of materials with design type "in". Furthermore, the surface of the electrospun PLDLLA and Fe3O4-in-PLDLLA was decorated with ZnO particles by simultaneous electrospraying, thus materials with design type "on" were obtained. In this case, quaternized N,N,N-trimethyl chitosan iodide (QCOS) was used as a sticking agent of ZnO particles onto the fiber's surface. Different structures and morphologies of the electrospun materials were observed by SEM equipped with EDX and TEM. TGA and XRD analyses show that the presence of inorganic particles had an impact on the thermal properties and crystallinity of the electrospun materials. Furthermore, the material type "on" showed improved wettability with a water contact angle less than 90° compared to the material type "in" with an angle larger than 90°. In particular, the presence of Fe3O4 imparts complementary magnetic properties, while ZnO considerably increased the antioxidant activity of the fibrous materials. Materials with design type "on" displayed over 70% radical scavenging capacity in contrast to the material type "in" with less than 20% capacity within 30 min of contact. Moreover, the purposely tailored design type "on" materials provided excellent photocatalytic degradation of model organic pollutant methylene blue dye under UV light irradiation even after 5-fold use, and at the end of the fifth cycle these materials degraded more than 90% of the dye. These results reveal not only a strategy for the fabrication of electrospun hybrid bio-based materials with targeted design but also provide a promising, simple and effective way for mitigating water pollution.

Efficient Removal of Tetracyclines and Quinolones Enabled by Polyphenol-Mediated Supramolecular Coagulation.

Ubiquitous antibiotics threaten human health and ecosystem sustainability, and existing removal strategies, especially conventional multistep water treatments, are primarily limited by the antibiotic-specific removal capability. Here, we explore the natural biomass, plant polyphenols, in the capture of various antibiotics with a facile treatment─polyphenol-mediated antibiotic-independent supramolecular coagulation (PMAC). The PMAC shows a superior performance in removing five tetracyclines and quinolones (up to 98.54%), even under complex environmental parameters, including different pH, the presence of inorganic particles and ionic strength, and the presence of conventional colloid-associated contaminants. Our mechanistic studies suggested that PMAC is capable of exerting multiple molecular interactions with various antibiotics, and the coordination-driven self-assembly further destabilizes the phenolic-antibiotic nanocomplexes, enabling an antibiotic-independent coagulation. Collectively, the combination of efficient remediation with inexpensive biomass suggests a simple and scalable method for the sustainable removal of antibiotics. Our strategy shows great promise as a cost-effective, facile approach to eliminate antibiotics capable of being integrated into the currently existing water treatment systems.

Combining atomic force microscopy and nanoindentation helps characterizing in-situ mechanical properties of organic matter in shale

The quantification of mechanical properties of organic matter in shale is of significance for the fine prediction and characterization of shale reservoir's mechanical properties. Due to the micron-sized and dispersed distribution of organic matter particles in shale, the accurate evaluation of the actual mechanical response remains challenging. This work focuses on shale from Wufeng-Longmaxi Formation, which is the main shale gas exploration and development formation in China. A method based on atomic force microscopy (AFM) with an optical microscope (i.e., in-situ AFM technique) is presented to locate the organic matter in-situ and then visualize and quantify its mechanical properties using AFM Young's modulus mapping. The merits and limitations for determining the mechanical properties of organic matter in shale between the AFM and the more conventional nanoindentation technique are discussed. Results show that combining in-situ nanoindentation and in-situ AFM mapping provides more accurate description of the mechanical properties of organic matter in shale than traditional grid indentation methods with low spatial resolution. The Young's moduli of organic matter calculated from nanoindentation are around twice smaller than those obtained from AFM measurements mainly because the elasto-plastic deformation zone of organic matter in nanoindentation tests is larger and can be additionally affected by the presence of inorganic particles and/or larger micro-pores in organic matter. The Young's modulus and hardness of graptolite in the shale obtained by nanoindentation are slightly larger than those of solid bitumen at the same thermal maturity. Both in-situ AFM and in-situ nanoindentation results show that the mechanical strength of organic matter increases with increasing maturity. Overall, the presented approach shows a great potential for accurate and in-situ measurement of the mechanical properties of organic matter in shale at the nanoscale, which may be beneficial to the development of rock mechanical models for the accurate evaluation of the actual mechanical properties of shale.

Variability of scattering and backscattering of marine particles in relation to particle concentration, size distribution, and composition off the eastern hainan coast in the south China sea

The light scattering and backscattering coefficients of particles (bp(λ) and bbp(λ)) and their association with particle concentration, size distribution, and composition off the eastern Hainan coast in the South China Sea (SCS) were analyzed between August and September 2013. Variations in bp(532) and bbp(532) were correlated to changes in the LISST-based total cross-sectional area and volume concentration of particles (AC and VC). Two significantly different covariations between bbp(λ) and bp(λ) and chlorophyll a concentration (Chla) were observed, and all samples were clearly separated into two groups (Group A and Group B) using the threshold relationship between bbp and Chla. Samples in Group B, most of which were collected in the nepheloid layer, showed higher bp/AC and bbp/AC than those in Group A. This indicates the presence of inorganic particles with higher np in Group B than in Group A. The relationship between bbp and Chla for Group A could be well fitted by a published model involving a constant backscattering background independent of Chla. A significant relationship (R2 = 0.85) was observed between bbp and Chla in the Chla maximum layer, which was different from that in other layers. This finding might imply that both an increase in the micro-phytoplankton community and a decrease in the contribution of background backscattering to bbp at the Chla maximum layer. Understanding this variability of beam-scattering properties off the eastern Hainan coast can improve our understanding of marine biogeochemical processes at a regional scale, and can also promote the application of these regional bio-optical relationships for ocean color.

Prolonged proliferation and delayed senescence of the adipose-derived stem cells grown on the electrospun composite nanofiber co-encapsulated with TiO2 nanoparticles and metformin-loaded mesoporous silica nanoparticles

This study was aimed to investigate the effects of the Poly-ε-Caprolactone/Gelatin nanofibers (PCL/GEL NFs) co-encapsulated with TiO2 nanoparticles (nTiO2) and metformin-loaded mesoporous silica nanoparticles (MET@MSNs) on prolonging the in vitro expansion of human adipose-derived stem cells (hADSCs) without inducing cellular senescence and aging. FTIR, BET, FE-SEM, and TEM were applied to characterize the fabricated MET@MSNs and electrospun composite NFs. The presence of inorganic particles, nTiO2 and MSNs, in the scaffolds improved their mechanical properties and led to a more sustained release of MET with almost the lack of the initial burst release from nTiO2/MET@MSNs-loaded NFs. The enhanced adhesion, metabolic activity, and proliferation rate of the hADSCs grown on nTiO2/MET@MSNs-loaded NFs were demonstrated via FE-SEM images, MTT test and PicoGreen assay, respectively, over 28 days of culture. Furthermore, the irregular nanofibrillar structures and the impact of sustained release of MET led to a significant upregulation in the mRNA levels of autophagy (Atg-5, Atg-7, Atg-12, and Beclin-1) and stemness (Nanog3, Sox-2, and Oct-4) markers as well as a considerable down-regulation of p16INK4A senescence marker. Further, the upregulation of hTERT, enhanced activity of telomerase, and increased telomere length were more pronounced in the hADSCs cultured on nTiO2/MET@MSNs-loaded NFs as compared to other types of NFs. Overall, our findings demonstrated the potential of the fabricated nanocomposite platform for counteracting cellular senescence and achieving sufficient quantities of fresh hADSCs with preserved stemness for various stem cell-based regenerative medicine purposes.

Fabrication of hydrophobic PP/CH3SiO2 composite hollow fiber membrane for membrane contactor application

Polymeric membrane wetting by liquid absorbent is one of the major challenges of the gas- liquid membrane contactors. In order to overcome this issue, composite polypropylene (PP) hollow fiber membranes were prepared by incorporation of methyl grafted silica nanoparticles (CH3-g-silica NPs) via two treatment approaches including blending the NPs with dope solution before membrane fabricating (approach 1), and also coating the NPs on the surface of the prepared membrane (approach 2). The fabricated membranes were characterized by using ATR-FTIR, FESEM, TEM, AFM, porosity, contact angle, mechanical strength, breakthrough pressure, wetting resistance and gas permeation test. The obtained results from ATR-FTIR spectra confirmed the successful formation of the PP-CH3SiO2 composite hollow fiber membranes. It was seen that for composite membranes fabricated with approaches 1 and 2 the average contact angle increased from 124° to 145° and 168°, respectively. The fabricated membranes were also investigated for CO2 absorption process in gas- liquid membrane contactors. As a result, the gentle decrease in flux of composite membranes compare to the sharp flux drop of neat one confirmed the effective improvement in the non-wetting property of the membranes in the presence of inorganic particles.

Crystallization kinetics of PCL and PCL–glass composites for additive manufacturing

The non-isothermal crystallization kinetics of polycaprolactone (PCL) and PCL–glass composites, used in fused filament fabrication (FFF), was investigated. Films of PCL and PCL reinforced with powders of a bioactive glass, from the CaO·P2O5·MgO·SiO2 system, were prepared by solvent casting process. Crystal structure of the samples was examined by X-ray diffraction (XRD), and thermal properties were assessed by differential scanning calorimetry (DSC), at different cooling rates (5, 10, 15 and 20 °C min−1). The DSC curves of non-isothermal crystallization showed a significant dependence of crystallinity (Xc) on the cooling rate. The relevant crystallization kinetic parameters were determined from DSC traces applying a combination of Avrami and Ozawa methods (Mo’s method), Jeziorny method and Friedman method. It was observed that the presence of inorganic particles within the polymeric matrix clearly influenced the composite crystallization. The addition of glass particles allowed a decrease in Xc and accelerated the PCL crystallization rate. The slower cooling rates tested proved to be suitable for the biofabrication of PCL–glass composites by FFF techniques.

Studies on the Deterioration of Ancient Thai Manuscripts

Various Thai manuscripts, commonly made from Khoi, suffer the severe deterioration primarily from the degradation of cellulose. Temperature, light, humidity, oxygen, pollution, and microorganisms are the main environmental factors for the conditions of manuscript collections. The degree of the cellulose deterioration can be studied by scanning electron microscopy (SEM), attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD). The morphology of the sample was revealed by Scanning Electron Microscopy. The fiber disintegration and the presence of inorganic particles can be found on the paper surface. The ATR-FTIR results showed the characteristic functional groups of cellulose as follows: nOH (3650–3100 cm-1), nCH (3000–2850 cm-1), dOH (~1640 cm-1), dCH (1420-1300 cm-1), nC-O-C of the b-glucosidic linkage (~1100 cm-1), and dCO or CC (~910 cm cm-1). The presence of inorganic filling, CO32- salt (~1400 cm-1) could not be determined explicitly due to the signal overlap with dCH. The relative intensities of the absorption peaks in dCH of the ancient paper samples are different to those of the new khoi paper. The X-ray diffraction of each sample showed the characteristic peaks of crystalline fraction at 2q between 22.0º and 23.0º and the amorphous fraction at 2q between 15.0º and 16.0º. However, the intensity ratio of the crystalline and amorphous phases for the ancient paper is less than that of the new paper.

Poly(para‐dioxanone)/inorganic particle composites as a novel biomaterial

In this work, poly(para-dioxanone) (PPDO) was mixed with 1% (by weight) calcium carbonate (CaCO(3)), beta-tricalcium phosphate (beta-TCP), or calcium sulphate dihydrate (CSD) by solution co-precipitation. Samples were compression molded into bars using a platen-vulcanizing press. The morphology, thermal and mechanical properties, and crystalline structure of the composites were investigated using differential scanning calorimetry, polarized optical microscopy, scanning electron microscopy, and X-ray diffraction. All results suggest that three types of inorganic particle in this system promote the crystallinity of PPDO and act as an effective nucleating agent: the relative degree of crystallinity of PPDO increased from 30.74% to 100%, and the crystallization temperature of PPDO was increased by 18 degrees C. On the other hand, the mechanical properties of PPDO were changed by the presence of inorganic particles: the tensile strength of PPDO/CSD increased by 11.46%.

In-vivo short- and long-term evaluation of the interaction material-blood

Through an innovative electron microscopy technique, thrombi and fibrotic tissue taken from 14 explanted vena cava filters were observed. Twelve cases showed the presence of micro-and nano-sized inorganic, non biodegradable nor biocompatible particles which did not belong to the metal the device was made of and which could be the sole cause or, more likely, a pre-existing cause for thrombosis. In two cases, those debris activated immunological reactions typical of a foreign body. The presence of inorganic particles in the blood was never detected before and their effects on human health are hardly known. Their thrombogenicity should be added to the Virchow's Triad as a fourth factor and could be the explanation to many of the cases of pulmonary embolism where no thrombotic focus could be demonstrated.

Surface Assisted Nucleation and Growth of Polymer Latexes on Organically‐Modified Inorganic Particles

AbstractSummary: Polymer latex particles were synthesized in the presence of inorganic particles, which had been organically‐modified to promote favorable interactions with growing macromolecules. The organic modification was performed using three different routes: (1) surface covalent grafting of vinyl trialkoxysilanes, (2) surface adsorption of polyethylene glycol‐based macromonomers, and (3) bulk modification through ion exchange with cationic monomers or cationic initiators. Two types of mineral particles were studied: commercial and self‐prepared silica particles (with diameters from 80 nm to 1 µm), and commercial laponite clay particles with a cation exchange capacity of 0.75 meq · g−1. Emulsion polymerization was performed in the presence of styrene or butyl acrylate monomers. The morphologies of the nanocomposite particles were observed by (cryogenic) transmission electron microscopy and correlated to the organic modification procedure.

Vibratory shear enhanced processing membrane filtration applied for the removal of natural organic matter from surface waters

In this study, the performance of a vibratory shear enhanced unit (termed hereafter as VSEP) was evaluated for the removal of humic acids in the presence of inorganic particles (clays) from synthetic aqueous dispersions, simulating contaminated surface waters. For this purpose, several major parameters were examined, such as the specific membrane type, the feed quality (i.e. the concentration of main components in the feed, as well as the pH value) and the vibration amplitude. It was found that the permeate flux was stabilized after certain operation (filtration) time regardless of feed quality for each membrane process. The percentage recovery of liquid volume during the performed semi-batch laboratory-scale experiments exceeded 90%. The increase of pH value from 6 to 9, during microfiltration (MF), resulted in 30% decrease of permeate flux and 20% enhancement of HA rejection, indicating that the form of HA in solutions, as well as their interactions with ions and/or inorganic clay particles may play an important role in the filtration process. Although clay particles were removed almost completely during all the examined filtration processes, HA molecules removal exceeded 99% only during nanofiltration (NF), while for the other processes the removal did not exceed 95%. The permeate flux was affected by the respective feed quality and membranes’ type (pore diameters), but also by the applied vibration amplitude as well, especially during ultrafiltration (UF), using the 10 kDa molecular weight cut-off (MWCO) membrane and NF processes. The permeate flux was found to be proportional to γ ¯ w 0 .21 for UF and to γ ¯ w 0 .31 for NF of humic acids solutions, where γ ¯ w is the mean (induced) shear rate at the membrane surface. Finally, although the operating pressures, especially for MF and UF were relatively high, when compared with other commercially available membrane treatment systems, the examined VSEP unit presented rather stable hydrodynamic behavior, enabling the efficient treatment of surface waters.

Binder removal from injection moulded zirconia ceramics

Binder removal from a wax-based zirconia ceramic moulding has been investigated in terms of solid content of the mouldings (45–55 vol%), heating rate (0.5–5°C min −1), sample form (powder and block), and sample thickness (0.5–5 mm). Experimental results show that the samples with lower surface-to-volume ratio or more solid content has greater restriction to binder transport which reduces binder removal kinetics to a significant extent. Such a transport restriction can be minimised or eliminated by using the sample in a powdered configuration. The behaviour of binder pyrolysis is considerably modified by the presence of inorganic particles, which may be considered as a result of catalytic reaction. Activation energy of pyrolysis of the binder is evaluated directly based on the existing kinetics models through the use of the resulting weight loss–temperature curve. The activation energy for evaporation obtained is smaller than that for thermal degradation suggesting that for the binder with low molecular weight currently employed, evaporation may be considered as a dominant mechanism for binder removal. This finding is also in well agreement with literature results.