Scanning Electron Microphotography Research Articles

Polyurethane Foam Residue Biodegradation through the Tenebrio molitor Digestive Tract: Microbial Communities and Enzymatic Activity

Polyurethane (PU) is a widely used polymer with a highly complex recycling process due to its chemical structure. Eliminating polyurethane is limited to incineration or accumulation in landfills. Biodegradation by enzymes and microorganisms has been studied for decades as an effective method of biological decomposition. In this study, Tenebrio molitor larvae (T. molitor) were fed polyurethane foam. They degraded the polymer by 35% in 17 days, resulting in a 14% weight loss in the mealworms. Changes in the T. molitor gut bacterial community and diversity were observed, which may be due to the colonization of the species associated with PU degradation. The physical and structural biodegradation of the PU, as achieved by T. molitor, was observed and compared to the characteristics of the original PU (PU-virgin) using Fourier Transform InfraRed spectroscopy (FTIR), Thermal Gravimetric Analysis (TGA), and Scanning Electron Microphotography (SEM).

Optimization of tetracycline adsorption onto zeolitic–imidazolate framework-based carbon using response surface methodology

This study investigated the fabrication of zeolitic–imidazolate framework (ZIF-8) and ZIF-8-derived porous carbon and their application in the adsorptive removal of tetracycline from water. The materials were analysed by X-ray photoelectron spectroscopy, scanning electron microphotography, and the measurement of pH point of zero charge. The results indicated the presence of N-doped carbon network and functional groups on ZIF-8-derived porous carbon. Response surface methodology was used for statistical analysis. The effect of operating parameters involving tetracycline concentration (25–100 mg/L), dose (0.05–0.75 g/L), and pH (4–10) were conducted. The results indicated that the quadratic regression models were statistically significant and the parameters of tetracycline concentration and adsorbent dose profoundly affected the adsorption capacity. The optimum conditions for adsorption of tetracycline were suggested and verified. The highest tetracycline actual adsorption capacity obtained by ZIF-8 and ZIF-8-derived porous carbon were 171.3, and 339.06 mg/g, respectively. The study proposed the participation of hydrogen bonding and π–π interactions as main mechanism. With the high suitability, the response surface methodology can be an efficient optimization tool.

Characterization Study of Cytotoxicity of Green Synthesized ZnO Nanoparticles Loaded with Anti‐Cancer Doxorubicin Drug

AbstractThe green synthesized zinc oxide nanoparticle (ZnO) was filled with a commercially available anti‐cancer drug, Doxorubicin (DoX). The loading of the drug into ZnO was validated using UV‐Visible and Raman spectroscopy. X‐ray diffraction data showed the wurtzite structure of the nanoparticles of ZnO. Scanning electron microphotography images detected the encapsulation of DoX drugs into ZnO nanoparticles. Fourier transformer infrared spectrum of DoX loaded ZnO showed a single band at 478 cm−1 attributed to the ZnO vibrational band and the carbonyl group peak at 1578 cm−1, suggesting the loading of DoX into ZnO. In addition, in vitro cytotoxicity of DoX, ZnO and ZnO‐DoX against HeLa cells was studied using the MTT colorimetric cell viability assay, which showed 99.4 % inhibition of ZnO‐DoX cells at a concentration of 100 μg/mL. The findings thus provide compelling evidence for green biosynthesized ZnO, which could serve as a promising nano‐drug carrier for the targeted drug delivery system.

A New Species of Ormocerus Walker (Hymenoptera: Pteromalidae) from North America and a Range Expansion for Ormocerus latus Walker.

Abstract. Ormocerus dirigoius Morin & Gates, n. sp. is described and compared to the North American O. americanus Dzhanokmen and Grissell and European species O. latus Walker and O. vernalis Walker. A range expansion into the Nearctic is reported for O. latus, previously only known from the Palearctic. Specimens were collected in Harpswell, Maine during a study of the parasitic Hymenoptera community associated with Operophtera brumata Linnaeus (Lepidoptera: Geometridae), an invasive species. The species are keyed and illustrated using macrophotography and scanning electron microphotography.

Role of amino acids on electrodeposition and characterisation of zinc from alkaline zincate solutions

Amino acid-based addition agents have been employed in an alkaline zincate plating electrolyte to modify corrosion resistance, crystal size, surface morphology, and adhesion of deposits. These addition agents such as guanine, histidine and glutamic acid are recommended in zincate solution to improve the corrosion resistance, crystal size and adhesion of the deposits. The XRD pattern obtained for electrodeposited zinc from such baths shows a polycrystalline hexagonal close-packed (hcp) structure. The crystal size was calculated using the Scherrer formula. A uniform and pore-free surface was observed under scanning electron microphotography (SEM) analysis. The corrosion resistance behaviour of the zinc deposits was analysed by potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS). Histidine appears to show most promise in enhancing corrosion resistance and grain refining.

In Vitro Analysis of Post-fatigue Reverse-Torque Values at the Dental Abutment/Implant Interface for a Unitarian Abutment Design

This study analyzed baseline and post-fatigue reverse-torque values (RTVs) for a specific brand control abutment relative to a third party compatible abutment. The purpose of this study was to compare the abutments' fatigue resistance to simulated function, using RTVs as an indication of residual preload at the implant/abutment interface. Forty Straumann tissue-level implants were mounted in resin and divided into four groups (n = 10). Forty abutments were seated, 20 control and 20 third-party abutments, according to manufacturer guidelines. Ten abutments from each manufacturer were evaluated for RTV without fatigue loading, using a calibrated digital torque gauge to provide a baseline RTVs. Fatigue loading was carried out on the remaining ten specimens from each manufacturer according to ISO 14801 guidelines. A moving-magnet linear motor was used to load one specimen per sequence, alternating from 10 to 200 N at 15 Hz for 5×10(6) cycles. RTV was recorded post-fatigue loading. The results were subjected to two-sample t-testing and two-way ANOVA. Scanning electron microphotography was carried out on three specimens from both manufacturers at baseline and post-fatigue cycling to visualize thread geometry and the abutment/implant interface. The data indicated that mean post-fatigue RTV observed for the control group was significantly higher than the third-party group (RTV 42.65 ± 6.70 N vs. 36.25 ± 2.63 N, p= 0.0161). Visual differences at the macro/microscopic level were also apparent for thread geometry, with third-party abutments demonstrating considerably greater variation in geometrical architecture than control specimens. Within the limitations of this in vitro model, the effect of component manufacturer resulted in a significantly higher RTV in the control group (two-way ANOVA, p= 0.0032) indicating greater residual preload; however, there was no significant decrease in post-fatigue RTV for either manufacturer compared to baseline.

Modification of Cotton Textiles with Nanostructural Zinc Particles

In this work, zinc nanoparticles were prepared by wet chemical method. The particles were examined by particle size analyzer, their morphology and micro structure were observed and elementally detected through scanning electron microphotography. Antimicrobial properties were evaluated using soil burial test. The effect of zinc nanoparticle treatment on physical properties and dyeing performance of cotton was evaluated. The work opened up a new avenue of manufacturing a new generation cotton nanocomposites with barrier properties against microbe with improved physical as well as dyeing performances.

Improvement in the dyeability of viscose

The effect of alkaline pretreatment with sodium hydroxide and sodium zincate on the dyeability of viscose has been studied. Both agents could enhance the dye accessibility to viscose, but sodium hydroxide was found to be more effective compared with sodium zincate. The maximum exhaustion of different reactive dyes was found with 7.5% w/v sodium hydroxide pretreated samples. Both the rate of dyeing and final dyebath exhaustion of viscose was significantly improved after such pretreatment. The pretreatment could also effectively replace the electrolyte requirement for some reactive dyes. The alkaline pretreatment also generated higher colour depth on the printed fabric. The change in surface morphology of the fibre as a result of sodium hydroxide treatment was examined through scanning electron microphotography. The weight loss as a result of this treatment was critically studied. 10% w/v sodium hydroxide was found to cause maximum loss in weight of the viscose fibre.

Effect of organic and inorganic acids on chitosan/glycerophosphate thermosensitive hydrogel

The influence of organic and inorganic acids on chitosan/glycerophosphate (CS/GP) hydrogel has been investigated by dissolving chitosan in different acids. The results of gelation showed that all of the chitosan dissolved in monovalent acid solutions (i.e., formic, acetic, propionic, butyric, isobutyric, lactic, nitric, hydrochloric, and chloroacetic acid), when neutralized by GP solution, could transform into hydrogel after 2–5 min at 37 °C, while those dissolved in multivalent acids failed in gel formation. The inner structures of CS/GP hydrogels prepared with monovalent acids depended on the ionic strength and chain length of acids. Morphological examination by scanning electron microphotography demonstrated that large pores occurred during the gel-forming process, and the aperture size was also related to different acids. The cytotoxicity studies indicated that CS/GP systems prepared by dissolving chitosan in tested acids except chloroacetic acid were nontoxic to mouse embryonic fibroblasts and Hela cells.

Morphological Conversion of Calcium Oxalate Crystals Into Stones Is Regulated by Osteopontin in Mouse Kidney

An important process in kidney stone formation is the conversion of retentive crystals in renal tubules to concrete stones. Osteopontin (OPN) is the major component of the kidney calcium-containing stone matrix. In this study, we estimated OPN function in early morphological changes of calcium oxalate crystals using OPN knockout mice: 100 mg/kg glyoxylate was intra-abdominally injected into wildtype mice (WT) and OPN knockout mice (KO) for a week, and 24-h urine oxalate excretion showed no significant difference between WT and KO. Kidney crystal depositions were clearly detected by Pizzolato staining but not by von Kossa staining in both genotypes, and the number of crystals in KO was significantly fewer than in WT. Morphological observation by polarized light optical microphotography and scanning electron microphotography (SEM) showed large flower-shaped crystals growing in renal tubules in WT and small and uniform crystals in KO. X-ray diffraction detected the crystal components as calcium oxalate monohydrate in both genotypes. Immunohistochemical staining of OPN showed that the WT crystals contained OPN protein but not KO crystals. We concluded that OPN plays a crucial role in the morphological conversion of calcium oxalate crystals to stones in mouse kidneys.

Preparation of Thermosensitive Chitosan Formulations Containing 5-Fluorouracil/Poly-3-hydroxybutyrate Microparticles Used as Injectable Drug Delivery System

The auto-gelling and drug release properties of the thermosensitive chitosan-β-glycerophosphate formulation were investigated. According to rheological study, gelation lag time of chitosan/β-glycerophosphate (GP) solutions varied from 2 to 60min with different deacetylation degree of chitosan, pH, gelation temperature, and the particles in the sol. The gelation properties were also found to influence the release profiles of a hydrophilic drug, 5-fluorouracil (5-FU). Morphological examination by scanning electron microphotography demonstrated that large “pores” occurred during the gel-forming process, which created hydrophilic environment and led to the rapid initial release of the drug (85% in first 8h). Poly-3-hydroxybutyrate (PHB), a biodegradable material, was applied here as scaffold to capture 5-FU into microparticles with high encapsulation efficiency by solvent-nonsolvent method. Combination of these microparticles into the chitosan-β-GP formulation could drop the rapid initial release from 85% down to 29% in the optimized PHB content (75%, by mass). The release could sustain for about 10 months. This study provided an understanding of the potential of injectable implant using thermosensitive chitosan-β-GP formulation containing PHB based particles for the water soluble drugs that need the property of long-term delivery.

On the misidentification of chalcid (Hymenoptera: Chalcidoidea) parasitoids of the cabbage seedpod weevil (Coleoptera: Curculionidae) in North America

AbstractPrevious identifications in North America ofTrichomalus perfectus(Walker, 1835) andMesopolobus morys(Walker, 1848) (Chalcidoidea: Pteromalidae), the principal chalcid parasitoids of the cabbage seedpod weevil (Ceutorhynchus obstrictusMarsham, 1802) in Europe, are shown to be misidentifications ofTrichomalus lucidus(Walker, 1835) andMesopolobus(Xenocrepis)moryoidessp. nov., respectively.Necremnus duplicatusGahan, 1941 (Chalcidoidea: Eulophidae) is synonymized formally underNecremnus tidius(Walker, 1839)syn. nov., confirming a previous, tentative synonymy. Both sexes ofN. tidius,M. moryoides, andT. lucidusare illustrated and compared with those of similar species using macrophotography and scanning electron microphotography. Hypotheses are offered to explain why the principal chalcid parasitoids of the cabbage seedpod weevil differ between North America and Europe and how the three treated species came to be in North America.

Rapid crystallization of amorphous silicon at room temperature

Abstract A way in which thin films of hydrogenated amorphous silicon (a-Si: H) can be instantaneously crystallized at room temperature is reported. The metal-induced solid-phase crystallization (MISPC) method with nickel surface coverage is used. In comparison with previous reports on the MISPC of a-Si: H, the crystallization temperature is reduced by more than 350°C. This is achieved by introducing two novel technological steps: firstly, we use hydrogen-rich a-Si: H films (hydrogen content between 20 and 45at.% H) and, secondly, we apply a high transverse electric field. Polycrystalline silicon islands as large as 3 mm across appear instantaneously after having reached a threshold electric field of about 105Vcm−1. We report macroscopic visualization of the crystallization process as well as microscopic investigation (micro-Raman measurements and scanning electron microphotography) of the crystallized films. We have found that appropriate patterning of the nickel electrode helps to increase homogeneity of the resulting polycrystalline silicon.

A novel sustained-release formulation of insulin with dramatic reduction in initial rapid release

To ensure a strictly controlled release of insulin, a preparation method for insulin-loaded microcapsules was designed. Microcapsules were prepared with an injectable, biodegradable polymer composed of co-poly( d, l-lactic/glycolic) acids (PLGA) (mean molecular weight 6600, LA/GA ratio 50:50). Morphological examination using scanning electron microphotography demonstrated spherical particles with a main diameter of 15–30 μm. When 3% insulin-loaded PLGA microcapsules were administered subcutaneously as a single dose (250 U/kg) to streptozotocin-induced hyperglycemic rats, plasma insulin levels increased and were sustained at levels showing hypoglycemic effects. When glycerin, ethanol, or distilled water was used throughout the preparation procedure, the resultant microcapsules dramatically reduced the initial burst. The formulation in which glycerin was added to an oil phase containing PLGA, insulin, and ZnO increased plasma insulin levels to 86.7, 108.4, and 84.9 μU/ml at 1, 2, and 6 h, respectively. The levels remained at 36.2–140.7 μU/ml from day 1 to day 9. The AUC 0–24 h/AUC 0–336 h ratio was calculated to be 9.7%. The formulation prepared without additives gave such a rapid insulin release that animals receiving it became transiently hypoglycemic.

Gas permeation properties of poly(amide-6-b-ethylene oxide)–silica hybrid membranes

The organic–inorganic hybrids of poly(amide-6-b-ethylene oxide) (PEBAX ®) and silica were prepared via in situ polymerization of tetraethoxysilane (TEOS) using the sol–gel process and their gas transport properties were studied. The nanodispersed inorganic network produced in the organic matrix was characterized by solid-state 29 Si NMR, Fourier transform infrared (FT-IR), dynamic light scattering (DLS) and field emission scanning electron microphotography (FE-SEM). Wide angle X-ray diffraction (WAXD) patterns and differential scanning calorimetry (DSC) thermograms of PEBAX ® and hybrid materials revealed that the incorporation of silica induced the structural modification of polymer chains. Gas permeation measurements were accomplished at various temperatures with He, CO 2, O 2 and N 2. These hybrid membranes exhibited higher gas permeability coefficients and permselectivities than PEBAX ®, particularly at an elevated temperature. Activation energy of CO 2 permeation through the hybrid membranes decreased due to the large contribution of heat of sorption while that of N 2 increased resulting from the increase of tortuosity and restricted chain mobility. All these results were explained by the increase of sorption ability of hybrids, attributed to the strong interaction between CO 2 molecules and SiO 2 domains, additional sorption sites in polyamide block in PEBAX ® and the organic/inorganic interphase.

Selective permeation of CO 2 through pore-filled polyacrylonitrile membrane with poly(ethylene glycol)

Pore-filling concept was applied to prepare high permselective composite membranes for CO 2 separation. The membrane is composed of two polymeric materials: a porous substrate and filling polymers that fills the pore of the substrate. In this study, asymmetric polyacrylonitrile (PAN) membrane was used for a substrate and methoxy poly(ethylene glycol) acrylate (MePEGA, M w=454) was used for a photoinitiated graft polymer. The analysis of graft membrane by Fourier transform infrared and attenuated total reflection (FT-IR, FT-IR/ATR), electron spectroscopy for chemical analysis (ESCA) and field emission scanning electron microphotography (FE-SEM) revealed that the graft polymer filled the pores of the substrate. High CO 2/N 2 permselectivity was shown by this pore-filling membrane: carbon dioxide permeation flux, J CO 2 =5.65 GPU (10 −6 cm 3(STP)/cm 2 s cmHg) and selectivity of CO 2 over N 2, J CO 2 / J N 2 =32.4 at 30°C, measured by the time-lag method. The high permselectivity of the present pore-filling membrane is attributed to the high solubility selectivity due to the affinity of CO 2 to PEO segment.

Preparation by Spray Drying of Amphotericin B-Phospholipid Composite Particles and Their Anticellular Activity

As a potent drug carrier for systemic fungal infections, amphotericin B(AmB)-phospholipid composite particles (APCPs) were prepared by the spray drying method. AmB and egg phosphatidylcholine, co-dissolved in methanol (0.0425-0.45 mg AmB/ml, 0.17-1.8 mg lipid/ml), was nebulized at 2 ml/min. The aerosol produced was carried by air at 1000 ml/min to the inner tubes of a serially connected distilling column system, of which the outer tubes were supplied with circulating water of 95°C. The particles, by scanning electron microphotography,are spherical and submicronsized. Upon hydration of the particles in phosphate-buffered saline for 30 min at room temperature, liposome-like bilayer vesicles were formed along with AmB-phospholipid complexes, evidenced by the transmission electron microphotographs and the positive peak around 330 nm of the circular dichroism spectrum, respectively. The hemolytic abilities of the APCPs were lower than those of free drug, without loss of the antifungal activity. The suppressed hemolysis could be ascribed to the liposomes and to the complexes that are reconstituted by hydration of APCPs. The dry composite particles could circumvent the inherent instability of liposomal formulations.

Synthesis and characterisation of boron-selective porous condensate cation exchanger

Several porous condensate cation exchangers were synthesised by catechol-phenolparaformaldehyde polycondensation using suitable porogenic agents. They were characterised for water content, ion-exchange capacity, dye uptake, surface area and the uptake of boron from sea water. A selected cation exchanger was studied further for solvent uptake, apparent density, pH titration curve, ion-exchange rate, boron uptake rate, boron selectivity, and by scanning electron microphotography. The uptake of boron from sea water by this selected cation exchanger was also studied under dynamic conditions. For comparison purposes a conventional gel-type product and a commercially available boron-selective ion-exchange resin, Amberlite XE-243, were also studied. The results clearly indicated that the modified products have higher pore volume, higher surface area, lower apparent density and good kinetics for ion exchange and boron uptake as compared with the conventional gel-type cation exchanger. The porous condensate cation exchanger shows selectivity for boron, and boron uptake is found to be reversible. It removed boron from a fairly large volume of sea water and gave out boron in the form of concentrated solution of comparatively small volume.

Clinical evaluation of four amalgam alloys: A five-year report

In this study 96 teeth of 12 patients were restored with either the conventional alloy Premix, the blended non-gamma 2 amalgam Dispersalloy, or one of the spherical alloys Sybraloy and Tytin. To ascertain an objective comparison of the clinical performance of these alloys, two different alloys were used in each of at least two dental arch quadrants in the same patient and consequently were placed in the same oral environment. Clinical performance of the restorations was evaluated by macrophotography and scanning electron microphotography of replicas made after placement and 2, 3, and 5 years thereafter. Standard criteria were used for the evaluation of anatomic form, surface condition, and marginal adaptation of the fillings. In addition, the filling-enamel interface was assessed from the microphotographs. The three high-copper alloys performed better clinically than the conventional alloy, and the spherical alloys had the best qualifications. In addition to visual examination and photographic evaluation of restorations, the micrometric assessment of replica photographs from the scanning electron microscope may render clinical trials of amalgam alloys measurable and less subjective.