Scanning Electron Microcopy Images Research Articles

Enhancing steel corrosion resistance in 1.0 M HCl medium through the synthesized and characterized mixed pyrophosphates BMnP2O7 (B = Ni, Co, and Cd)

In this study, we synthesized three diphosphate materials NiMnP2O7, CoMnP2O7, and CdMnP2O7 intended for use as corrosion inhibitors for carbon steel. The crystallinity of the obtained compounds was analyzed using X-ray diffraction (XRD), and a vibrational analysis was carried out by infrared (IR) and Raman (Ra). The corrosion inhibition properties of steel with these materials in 1.0 M HCl solution were investigated using three important techniques. The electrochemical parameters were obtained via electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves (PDP) and the surface of the substrate was analyzed, using the scanning electron microscopy (SEM). Our findings indicate that the optimal concentration for NiMnP2O7, CoMnP2O7, and CdMnP2O7 was 10−3 mol/L, with inhibition efficiencies reaching to 87.5 %, 91.04 %, and 92.22 %, respectively. These phosphates also act as a mixed-type inhibitors, imparting high resistance to corrosion, and their inhibition efficiency (η%) increased with the augmentation of the inhibitor concentration. The scanning electron microcopy (SEM) images revealed that the inhibitors form a protective layer against acid attack, preventing carbon steel from being destroyed.

Remineralizing Potential of Bioactive Glass–Ceramic over White Spot Lesions

Abstract Objective This study evaluated the effect of incorporating biosilicate (Bio) particles into experimental toothpaste (ET) on their abrasiveness and remineralization capacity for white spot lesions (WSLs). Materials and Methods Thirty-two fragments of bovine teeth (6 × 6 × 2 mm) were obtained. Initial microhardness (Knoop hardness number [KHN], HMV Microhardness Meter, Shimadzu) and surface roughness (Rugosimeter Surfcorder SE 1700) readouts were performed. Fragments were submitted to a cariogenic challenge to simulate WSLs and then divided into four groups: Control, conventional toothpaste (Colgate Smiles, Colgate-Palmolive Company); ETF, ET with fluoride (carboxymethylcellulose + glycerol + thickening silica + fluoride); ETB, ET with Bio; BS, biosuspension (10 in weight% Bio). Toothpaste treatments were performed through simulated toothbrushing (Pepsodent, MAVTEC, 14,600 cycles). BS was applied by immersion for 8 hours followed by 16 hours in artificial saliva at 37°C for 60 days, totalizing 1,440 cycles. After treatments, final KHN and surface roughness readings were performed, and scanning electron microcopy (SEM) was conducted (Jeol JSM-6610LV) for morphological analysis. Data were analyzed with one-way analysis of variance, Tukey's test (p < 0.05). Results BS produced the least surface roughness change, different (p < 0.05) from all the other groups. ETB caused higher KHN than ETF (p < 0.05). SEM images revealed that ETB and BS resulted in abraded surfaces with deposition of particles. Conclusion ETB resulted in similar abrasiveness to the control group, and it caused higher microhardness than the ETF. Practical Implication Considering its higher KHN, ETB could be considered a proper alternative for the treatment of WSLs.

The synergistic effect of polyorganosilicon and sulfonic groups functionalized graphene oxide on the performance of sulfonated poly (ether ether ketone ketone) polyelectrolyte material

It is a challenge to simultaneously improve proton conductivity, methanol resistance and physicochemical stability of polymer electrolyte membranes (PEMs) used in direct methanol fuel cell (DMFC). In response to this situation, the crosslinked nanocomposite membranes are prepared by introducing polyorganosilicon with various functional groups and sulfonic groups functionalized graphene oxide (SFGO) to the sulfonated poly (ether ether ketone ketone) in this paper. Based on our knowledge, no such PEM materials have been designed and prepared by this method. Scanning electron microcopy images demonstrate that there are good compatibility and connectivity between the matrix and fillers. The combination of polyorganosilicon and SFGO significantly improves the comprehensive performance of membrane, including mechanical property, dimensional stability, proton conductivity, methanol resistance, selectivity, oxidative and hydrolytic stabilities, cell performance, etc. Especially, the nanocomposite membrane with 3 wt% SFGO shows the highest conductivity (0.074 S cm−1 at 25 °C) and lowest methanol diffusion coefficient (3.56 × 10−7 cm2 S−1), which result in the optimal selectivity (2.08 × 105 Ss cm−3). In addition, the maximum power density (73.76 mW cm−2) of the membrane with 3wt% SFGO is higher than that of commercial Nafion@ 117 (61.59 mW cm−2) under identical experimental conditions. These results indicate that the crosslinked nanocomposite membranes will be new alternative to substitute the expensive Nafion® 117 for DMFC application.

Revealing the charge carrier kinetics in perovskite solar cells affected by mesoscopic structures and defect states from simple transient photovoltage measurements

This report shows that, by using simple transient photovoltage (TPV) measurements, we can reveal a significant correlation between the TPV decay characteristics and the performance of these perovskite solar cells. TPV decay seems to be composed of a rising part in a short interval after photoexcitation and a long decaying part that extends up to tens of milliseconds. These decay behaviors look different depending on the mesoscopic structures and the perovskite morphology formed therein, as seen from their Scanning Electron Microcopy images and X-ray diffraction patterns. The decay part can be fitted with a three-exponential decay, which reflects different kinetics of electrons in the perovskite/TiO2 layer. On the other hand, the rising part must be fit by a decay equation derived by employing the convolution theorem, where the rising part can be assigned to the electron transport process inside the perovskite layer and the decaying part can be assigned to electron back-transfer. The characteristics can be then understood by considering the effect of crystal defects and trap states in the perovskite grains and perovskite interface with its transport layer, which is TiO2 in this study. Although the TPV decay occurs in a time range much longer than the primary process of photoexcitation as commonly observed in transient photoluminescence spectroscopy, the processes involved in this TPV strongly correlates with the performance of these perovskite solar cells.

Enhancement of the Start-Up Time for Microliter-Scale Microbial Fuel Cells (µMFCs) via the Surface Modification of Gold Electrodes.

Microbial Fuel Cells (MFCs) are biological fuel cells based on the oxidation of fuels by electrogenic bacteria to generate an electric current in electrochemical cells. There are several methods that can be employed to improve their performance. In this study, the effects of gold surface modification with different thiol molecules were investigated for their implementation as anode electrodes in micro-scale MFCs (µMFCs). Several double-chamber µMFCs with 10.4 µL anode and cathode chambers were fabricated using silicon-microelectromechanical systems (MEMS) fabrication technology. µMFC systems assembled with modified gold anodes were operated under anaerobic conditions with the continuous feeding of anolyte and catholyte to compare the effect of different thiol molecules on the biofilm formation of Shewanella oneidensis MR-1. Performances were evaluated using polarization curves, Electrochemical Impedance Spectroscopy (EIS), and Scanning Electron Microcopy (SEM). The results showed that µMFCs modified with thiol self-assembled monolayers (SAMs) (cysteamine and 11-MUA) resulted in more than a 50% reduction in start-up times due to better bacterial attachment on the anode surface. Both 11-MUA and cysteamine modifications resulted in dense biofilms, as observed in SEM images. The power output was found to be similar in cysteamine-modified and bare gold µMFCs. The power and current densities obtained in this study were comparable to those reported in similar studies in the literature.

The effective methanol-blocking and proton conductivity membranes based on sulfonated poly (ether ether ketone ketone) and polyorganosilicon with functional groups

To solve the conflict between high proton conductivity and low methanol crossover of pristine sulfonated aromatic polymer membranes, the polyorganosilicon doped sulfonated poly (ether ether ketone ketone) (SPEEKK) composite membranes were prepared by introducing polyorganosilicon additive with various functional groups into SPEEKK in this study. Scanning electron microcopy (SEM) images showed the obtained membranes were compact. No apparent agglomerations, cracks and pinholes were observed in the SEM images of composite membranes. The good compatibility between polymer and additive led to the interconnection, thus producing new materials with great characteristics and enhanced performance. Besides, the dual crosslinked structure could be formed in composite membranes through the condensation of silanols and the strong interaction between matrix and additive. The formation of dual crosslinked structure optimized the water absorption, enhanced the hydrolytic stability and oxidative stability of membranes. Especially, the incorporation of additive improved the strength and flexibility of composite membranes at the same time, meaning that the life of the composite membranes might be extended during the fuel cell operation. Meanwhile, the proton conductivity improved with increasing additive content due to the loading of more available acidic groups. It is noteworthy that at 25% additive loading, the proton conductivity reached a maximum value of 5.4 × 10−2 S cm−1 at 25 °C, which exceeded the corresponding value of Nafion@ 117 (5.0 × 10−2 S cm−1) under same experimental conditions. The composite membrane with 20 wt% additive was found to produce the highest selectivity (1.22 × 105 S cm−3) with proton conductivity of 4.70 × 10−2 S cm−1 and methanol diffusion coefficient of 3.85 × 10−7 cm2 s−1, suggesting its best potential as proton exchange membrane for direct methanol fuel cell application. The main novelty of our work is providing a feasible and environment-friendly way to prepare the self-made polyorganosilicon with various functional groups and introducing it into SPEEKK to fabricate the dual crosslinked membranes. This design produces new materials with outstanding performance.

Thyroxine-loaded chitosan/carboxymethyl cellulose/hydroxyapatite hydrogels enhance angiogenesis in in-ovo experiments

Angiogenesis is one of the most important processes in repair and regeneration of many tissues and organs. Blood vessel formation also play a major role in repair of dental tissue(s) after ailments like periodontitis. Here we report the preparation of chitosan/carboxymethyl cellulose/hydroxyapatite based hydrogels, loaded with variable concentrations of thyroxin i.e., 0.1 μg/ml, 0.5 μg/ml and 1 μg/ml. Scanning electron microcopy images (SEM) showed all hydrogels were found to be porous and solution absorption study exhibited high swelling potential in aqueous media. FTIR spectra confirmed that the used materials did not change their chemical identity in synthesized hydrogels. The synthesized hydrogels demonstrated good bending, folding, rolling and stretching abilities. The hydrogels were tested in chick chorioallantoic membrane (CAM) assay to investigate their angiogenic potential. Hydrogel containing 0.1 μg/ml of thyroxine showed maximum neovascularization. For cytotoxicity analyses, preosteoblast cells (MC3T3-E1) were seeded on these hydrogels and materials were found to be non-toxic. These hydrogels with pro-angiogenic activity possess great potential to be used for periodontal regeneration.

Tannin of Acacia mearnsii as green corrosion inhibitor for AA7075‐T6 alluminum alloy in acidic medium

The inhibition performance of Acacia mearnsii bark tannin was investigated as eco‐friendly green inhibitor on the corrosion of AA7075‐T6 aluminum alloy in 0.1 M HCl solution by potentiodynamic polarization technique, electrochemical impedance spectroscopy (EIS) and scanning electron microcopy (SEM). Polarization curves showed that this tannin acts predominantly as a cathodic inhibitor. High corrosion inhibition performance was achieved with inhibition efficiencies of 95% and 97% at 14 g L−1 as obtained by polarization and EIS electrochemical techniques, respectively. The SEM images revealed that localized attack initiated at intermetallic particles causing local dissolution of the matrix due to potential differences between them. EIS results and SEM images confirmed the protection of AA7075‐T6 aluminum alloy by A. mearnsii bark tannin, evidencing the formation of an adsorbed film on the metal surface that attenuate the aluminum dissolution reaction.

Monitoring the changes in the microstructure and the elastic and transport properties of Eagle Ford marl during maturation

Organic-rich marl is one of the best unconventional reservoirs because of its high calcite and low clay content leading to relatively high permeability and fracability. However, how its stiff pores and relatively high permeability affect the changes in its microstructure and elastic and transport properties during maturation remains a research interest. We have induced ex situ maturation of organic-rich marl core plugs by conducting confined pyrolysis in fine steps across the maturity windows from immature through the early-peak oil, late oil, wet gas, and finally, the dry gas window. This was performed under high and low confining pressures on different samples to investigate the role of confining pressure during maturation. After each pyrolysis, we monitored the changes in microstructure, porosity, velocity, permeability, and geochemical properties. The results indicate increasing porosity, decreasing velocity, and increasing permeability as the maturation progresses. The time-lapse scanning electron microcopy images reveal the progressive development of secondary organic porosity at the expense of kerogen volume. Most of the changes in the acoustic velocity and permeability occur in the late oil window and are concurrent with the generation of connected secondary organic porosity. The total organic carbon (TOC) and Rock-Eval results indicate that most of the generated hydrocarbons immediately exit the samples during pyrolysis so that the generation of microcracks from pore-pressure buildup is unlikely. Rather, secondary organic porosity is the main microstructural change, and the amount of depleted TOC can be used as a proxy to predict the increase in porosity and the changes in the velocity and permeability. Finally, confining pressure plays a minor role in the evolution of the elastic and transport properties of organic-rich marl.

Facile preparation of CuWO4 porous films and their photoelectrochemical properties

In this study, the structure and photoelectrochemical properties of CuWO4 porous films synthesized by a co-precipitation method followed by a hydrothermal treatment were investigated. The film was deposited on fluorine-doped tin oxide (FTO)-conducting glass, from a suspension containing polyethylene glycol, and heat-treated at 500°C for 30min. X-ray diffraction patterns, the Rietveld refinement data, and the micro-Raman spectrum showed that the CuWO4 film has a triclinic structure. The optical band gap energy of the film was estimated to be 2.45eV by the Tauc plot. Field emission scanning electron microcopy images of the films indicated that they are about 4.0±0.5μm thick. The photoelectrochemical properties of the film were investigated in a Na2SO4 aqueous solution, in the absence of light and under polychromatic irradiation. The CuWO4 film exhibited photoelectrochemical behavior of a n-type semiconductor, with a negative photopotential and an anodic photocurrent density of 68μAcm−2 at 0.73V vs. Ag/AgCl (1.23V vs. RHE). The n-type photoelectrochemical behavior was confirmed by a chronoamperometry measurement biased condition at+0.7V, at different pH values. From these studies, it was noted that when the pH values increased from 3 to 11, the photocurrent density increased about 9 times. Also, the flat band potential (Efb) of the semiconductor was estimated by the Butler-Gärtner model at+0.34V, which was utilized to calculate the conduction band edge. The studies presented here reveal that the CuWO4 porous film is a promising candidate to be applied as a photoanode in photocatalytic processes under irradiation by visible light.

Effect of Compound Surface Treatment on the Performance of Poly(butylene succinate)/Chemithermomechanical Pulp Fiber Composites

ABSTRACTChemithermomechanical pulp fiber was pretreated by alkali solution to alter the surface characteristics of fibers. The untreated and treated fibers were used to prepare poly(butylene succinate)/chemithermomechanical pulp fiber composites with or without the incorporation of cellulose fatty acid ester (hydroxyethyl cellulose lauric acid ester). X-ray photoelectron spectrum analysis shows that the O/C ratio on the fiber surface increased after alkali treatment, indicating that part of lignin was removed during alkali treatment process. Scanning electron microcopy images indicate that the fiber surface was changed to rough after alkali treatment. The modification effect of hydroxyethyl cellulose lauric acid ester reflects as the improvement of fiber order in matrix, together with the enhancement of interfacial bonding, whereas, the modification effect of alkali treatment is mainly due to the enhancement of interfacial bonding. The integrated mechanical properties of composite prepared by alkali-treated fibers are superior to those of composite prepared by hydroxyethyl cellulose lauric acid ester-treated fibers. The combination of these two modification methods favors the enhancement of tensile and impact strengths of composite. However, in comparison with the composite prepared only by alkali treatment, the flexural strength and modulus would be despaired in a certain degree. When fibers were alkali treated, the shear viscosity of composite exhibited a larger increase, whereas the shear viscosity of composite prepared fibers with hydroxyethyl cellulose lauric acid ester treatment exhibits a slight decrease.

Effects of picosecond laser repetition rate on ablation of Cr12MoV cold work mold steel

In this paper, the effects of pulse repetition rate on ablation efficiency and quality of Cr12MoV cold work mold steel have been studied using a picosecond (ps) pulse Nd:YVO4 laser system at λ=1064nm. The experimental results of area ablation on target surface reveal that laser repetition rate plays a significant role in controlling ablation efficiency and quality. Increasing the laser repetition rate, while keeping a constant mean power improves the ablation efficiency and quality. For each laser mean power, there is an optimal repetition rate to achieve a higher laser ablation efficiency with low surface roughness. A high ablation efficiency of 42.29, 44.11 and 47.52μm3/mJ, with surface roughness of 0.476, 0.463 and 0.706μm could be achieved at laser repetition rate of 10MHz, for laser mean power of 15, 17 and 19W, respectively. Scanning electron microcopy images revels that the surface morphology evolves from rough with numerous craters, to flat without pores when we increased the laser repetition rate. The effects of laser repetition rate on the heat accumulation, plasma shield and ablation threshold were analyzed by numerical simulation, spectral analysis and multi-laser shot, respectively. The synergetic effects of laser repetition rate on laser ablation rate and machining quality were analyzed and discussed systemically in this paper.

Evaluation of high-temperature creep behavior in Inconel-713C nickel-based superalloy considering effects of stress levels

In this article, high-temperature creep behavior of the Inconel-713C nickel-based superalloy, which has been utilized in turbine blades, has been investigated. Creep testing was carried out on standard specimens at 850°C and under different stress levels. Experimental data demonstrated that the applied stress caused a reduction in the creep lifetime, as a power law. Besides, scanning electron microcopy images showed that the mentioned material had a brittle fracture with cleavage marks on the fracture surface of samples. In addition, optical microscopy images indicated the high effect of the applied stress on the carbides morphology. During higher the creep lifetime, the length of carbides increased parallel to the force direction and caused to produce the trans-granular fracture. Then also, the amount of the γ, phase enhanced in the γ matrix, which caused to strengthen the creep resistance of the material.

Synthesis and Thermoelectric Properties of SnSe by Mechanical Alloying and Spark Plasma Sintering Method

The bulks of polycrystalline SnSe materials were successfully prepared by the mechanical alloying (MA) and spark plasma sintering (SPS) method. X-ray powder diffraction analysis showed that pure Sn and Se powders were synthesized into the SnSe phase by MA, and after SPS under 30–120 MPa, the single phase bulks of SnSe materials were successfully prepared. Scanning electron microcopy images displayed that the grain size of SnSe shows refinement with higher pressure. The electrical properties of the sintered samples increased with increasing sintering pressure. The thermal conductivity results show that the thermal conductivity remained low, in the range of 0.50–0.85 W m−1 K−1, with the different sintering pressure. The samples sintered under 100 MPa have the best thermoelectric properties; the dimensionless figure of merit ZT reached 0.71 at 873 K.

Effect of 1,4-bis(3-dodecylimidazolium-1-yl) butane bromide on channel form of gramicidin vesicles

The present work is a brief overview of technical applications of surfactant that involves membrane interactions, and surfactant-based protocols to study biological systems. Herein, we investigate the effect of ionic liquid type gemini surfactant [C12-4-C12im]Br2, (1,4-bis(3-dodecylimidazolium-1-yl) butane bromide) on the channel form of gramicidin vesicle. Gramicidin is a linear pentadecapeptide antibiotic that adopts a wide range of environment dependent conformations. Gemini surfactants are a novel class of surfactants possessing better physicochemical properties than conventional surfactants. Several spectroscopic approaches viz. fluorescence, time resolved fluorescence, circular dichroism (CD) and red edge excitation shift (REES) were employed to elucidate the interaction between gramicidin vesicle and [C12-4-C12im]Br2. Fluorescence and time-resolved fluorescence studies confirmed the quenching and accessibility of gramicidin fluorescence by [C12-4-C12im]Br2 through static quenching mechanism. CD results show the change in orientation of tryptophan within gramicidin vesicle on the addition of [C12-4-C12im]Br2. REES results suggested the possible interaction between gramicidin and [C12-4-C12im]Br2. In order to further validate our results, we exploited techniques like dynamic light scattering (DLS), dynamic surface tension (DST) and scanning electron microcopy (SEM). DLS results reveal increase in the size of gramicidin vesicles upon interaction with [C12-4-C12im]Br2. To our surprise, the DST shows the surface activity of gramicidin vesicles decreases with increase in concentration of [C12-4-C12im]Br2, suggesting possible interaction and complex formation between gramicidin and [C12-4-C12im]Br2. SEM images of gramicidin vesicle with different concentrations of [C12-4-C12im]Br2 differ markedly showing aggregation on the surface of vesicles, again supporting the above results. Docking results provide deep molecular insight into the probable interaction between tryptophan and D-leucine residues of gramicidin with [C12-4-C12im]Br2 through hydrophobic interactions. This work has prime importance in future to design ionic liquids based biomaterials for drug/gene delivery.

Effect of trace metal‐limited growth on the postmortem dissolution of the marine diatom Pseudo‐nitzschia delicatissima

AbstractWe investigated the effects of iron (Fe) and copper (Cu) limitations on biogenic silica (bSiO2) dissolution kinetics of the marine diatom Pseudo‐nitzschia delicatissima during a 3 week batch dissolution experiment. The dissolution of this species was faster during the first week than thereafter. Modeling results from four dissolution models and scanning electron microcopy images suggested the successive dissolution of two phases of bSiO2, with two different dissolution constants. Micronutrient limitation during growth affected the respective proportion of the two phases and their dissolution constants. After 3 weeks of dissolution, frustules from micronutrient‐limited diatoms were better preserved than those of replete cells. Our results also confirm that micronutrient‐limited cells may export more Si relative to N than replete cells and may increase the silicate pump: This may not only be due to a higher degree of silicification of the live cells but also to a decoupling between the recycling of Si and N during dissolution. We suggest that a mechanistic understanding of the evolution of the dissolution constant during dissolution is needed. This would improve the parameterization of dissolution in ecosystem models, and ultimately their predictions on the amount of bSiO2 that dissolves in the photic zone, and the amount of bSiO2 that is exported to the seafloor.

Performance enhancement of poly(butylene succinate)/chemithermomechanical pulp fiber composites by debonder treatment

Debonder, a kind of weak combination reagent usually used in the production process of fluff pulp, was used as interfacial modifier in poly(butylene succinate)/chemithermomechanical pulp fiber composites. Physical properties of handsheets prepared by treated fibers indicated that the bonding strength between fibers was sharply decreased by the debonder treatment. The mechanical performance of composites prepared from treated fiber showed significant enhancement. In comparison with untreated one, the tensile strength, impact strength, and bending strength of composite containing 40 wt% of chemithermomechanical pulp fiber treated with 0.5 wt% debonder increased by 21.9, 22.3, and 35.4%, respectively. Furthermore, the data of rheological behavior measurement exhibited that the incorporation of debonder lowered the shear viscosity of composite and favored the processing process of composite. Besides, debonder played a role of hydrophobic agent in composites. A significant increase in storage modulus (E’) was observed upon the incorporation of treated chemithermomechanical pulp fiber. Scanning electron microcopy images showed that the interfacial bonding between treated fibers and poly(butylene succinate) matrix was improved.

Rietveld refinement, cluster modelling, growth mechanism and photoluminescence properties of CaWO4:Eu3+microcrystals

CaWO4:Eu3+ microcrystals (with 0, 1, 2 and 4 mol% Eu3+) were synthesized by a co-precipitation (CP) method and grown in a microwave-assisted hydrothermal (MAH) system at 130 °C for 30 min. X-ray diffraction (XRD), Rietveld refinement, X-ray absorption near edge spectroscopy (XANES), Fourier-transform Raman (FT-Raman) and Fourier-transform infrared (FT-IR) spectroscopy indicated that all of the microcrystals have a scheelite-type tetragonal structure without deleterious phases. Structural refinement data were employed to model the [CaO8], [EuO8] and [WO4] clusters. XANES spectra confirmed that the presence of deltahedral [EuO8] clusters promotes small distortions of neighbouring tetrahedral [WO4] clusters in a global tetragonal lattice. Field emission scanning electron microcopy (FE-SEM) images revealed that the replacement of Ca2+ by Eu3+ ions changed the particles' shapes, resulting in the different morphologies of the microcrystals. UV-vis diffuse reflectance spectra indicated a reduction in the optical band gap with the replacement of Ca2+ by Eu3+ ions. The photoluminescence (PL) properties of the Eu3+ ions in CaWO4 were studied as well as the chromaticity coordinates and lifetimes of these compounds.

Synthesis and characterization of CaCO3–biopolymer hybrid nanoporous microparticles for controlled release of doxorubicin

Doxorubicin (Dox) is a hydrophilic drug extensively used for treatment of breast, lung, and ovarian cancer, among others; it is highly toxic and can cause serious side effects on nontargeted tissues. We developed and studied a hybrid nanoporous microparticle (hNP) carrier based on calcium carbonate and biopolymers derivatized with folic acid (FA) and containing Dox as a chemotherapeutic drug model. The hNPs were characterized by X-ray diffraction, and Raman and Fourier transform infrared (FTIR) spectroscopies. The X-ray diffraction patterns of calcium carbonate particles showed about 30–70% vaterite–calcite polymorphisms and up to 95% vaterite, depending on the absence or the presence of biopolymers as well as their type. Scanning electron microcopy images revealed that all types of hNPs were approximately spherical and porous with average diameter 1–5μm, and smaller than CaCO3 microparticles. The presence of biopolymers in the matrices was confirmed after derivatization with a fluorescein isothiocyanate probe by means of confocal microscopy and FTIR synchrotron beamline analysis. In addition, the coupling of lambda carrageenan (λ-Car) to FA in the microparticles (FA–λ-Car-hNPs) increased the cancer-cell targeting and also extended the specific surface area by up to ninefold (26.6m2g−1), as determined by the Brunauer–Emmett–Teller isotherm. A nanostructured porous surface was found in all instances, and the FA–λ-Car-hNP pore size was about 30nm, as calculated by means of the Barrett–Joyner–Halenda adsorption average. The test of FA–λ-Car-hNP anticancer activity on human osteosarcoma MG-63 cell line showed cell viabilities of 13% and 100% with and without Dox, respectively, as determined by crystal violet staining after 24h of incubation.

First record of Holothuria (Theelothuria) notabilis (Holothuroidea: Aspidochirotida) from the Beibu Gulf: northward range expansion in the South China Sea

The sea cucumber Holothuria (Theelothuria) notabilis for the first time is reported from the Beibu Gulf, South China Sea. A morphological description of this new record with colour figures and scanning electron microcopy images of its ossicles are provided. This finding widens the geographical range of H. (T.) notabilis and indicates that this species may expand northwards in the South China Sea. With our new record, the subgenus theelothuria is now represented by three species in China.