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From samples of moldy wall paint and damaged water-based paint, we isolated and quantified the density of microorganisms present in the samples and determined the morphology of the isolates; thereby, identifying the genera of the bacteria and mold strains. The results showed that the density of the strains collected from the wall paint samples was much higher than that of the water-based paint samples (106 CFU/mL and 104 CFU/mL, respectively). In the wall paint samples, only mold colonies were observed, not bacterial colonies, while in the water-based paint samples both mold and bacterial colonies appeared, although mold colonies were still predominant. Based on the observation of colony formation and microscopic morphology of molds, we classified six mold strains into five genera: Aspergillus sp., Cladosporum sp., Acremoium sp., Chaetomium sp., and Fusarium sp. The frequency of strains belonging to the genus Aspergillus sp. accounted for the majority in both wall and water-based paint samples. Among the three bacterial strains isolated, we identified two bacterial strains as G (-) and one strain as G (+).

Rice husk is one of the most abundant biomass resources in the world, yet it is not effectively used. This study focuses on the sustainably rice-husk-extracted lignin, nano-lignin (n-Lignin), lignin-capped silver nanoparticles (LCSN), n-Lignin-capped silver nanoparticles (n-LCSN), and lignin-capped silica-silver nanoparticles (LCSSN), and using them for antibacterial activities. The final n-Lignin-based products had a sphere-like structure, of which the size varied between 50 and 80 nm. We found that while n-Lignin and lignin were less effective against Escherichia coli than against Staphylococcus aureus, n-Lignin/lignin-based hybrid materials, i.e., n-LCSN, LCSN, and LCSSN, were better against E. coli than against S. aureus. Interestingly, the antimicrobial behaviors of n-LCSNs could be further improved by decreasing the size of n-Lignin. Considering the facile, sustainable, and eco-friendly method that we have developed here, it is promising to use n-Lignin/lignin-based materials as highly efficient antimicrobials without environmental concerns.

This study studied the content and composition of the total lipid, lipid classes and fatty acids in 13 brown seaweed Sargassum species collected from Con Dao and Van Phong, Vietnam. The total lipid has a low content and varies among species from 0.10–1.70% of the fresh weight. From 13 species, seven lipid classes including polar lipid (Pol), free fatty acids (FFA), sterol (ST), hydrocarbon and wax (HW), triacylglycerol (TG), diacylglycerol (DG), and monoalkydiacylglycerol (MADG). Using the GC-FID technique, we have identified 29 fatty acids classified into 3 groups of saturated fatty acid, monounsaturated fatty acids, polyunsaturated fatty acids with an average content of 44.93%, 24.57% and 27.44%, respectively. Among those, many value fatty acids have been detected with high content such as C18:3n-3, C20:4n-6, 20:5n-3, and 22:6n-3. The lipid of 13 brown seaweed Sargassum species also fully contains omega-3,6,9 fatty acids with the content of 9.28%, 16.28% and 16.63%, respectively.

Antibacterial materials have been developed for a long time but bacteria adapt very quickly and become resistant to these materials. This study focuses on the synthesis of a hybrid material system from lignin and silver/silica nanoparticles (Lig@Ag/SiO

Alginate lyase is an enzyme that degrades alginate to create bioactive oligoalginate for application in medicine, industry, agriculture... In this study, cultural conditions of marine bacteria, Bacillus velezensis AlgSm1 have been investigated for producing alginate lyase with high content and activity. The nutritional components such as carbon source, nitrogen source, initial pH value, and cultural time were investigated. The results showed that the cultural conditions of B. velezensis AlgSm1 to biosynthesize alginate lyase with high activity were 5 mg/ml alginate, 0.8 mg/ml yeast extract; pH 5.5 and 18-hours fermentation at 28-30°C.

In this study, MCM-41 mesoporous silica nanoparticles were successfully synthesized by the condensation of a tetraorthosilicate precursor on a template self-assembled by cetyltrimethylammonium bromide in alkaline. The small-angle x-ray diffraction patterns of MCM-41 indicate that silica nanoparticles possess hexagonal structures with a high degree of structural ordering. Transmission electron microscopy images show that the size of the MCM-41 particles is around 100-120 nm, and the pore sizes range from 2 nm to 4 nm. In addition, the specific surface area of MCM-41 obtained by Brunauer–Emmett–Teller analysis is as high as 987 m2.g−1 and the pore size extracted from nitrogen physical adsorption isotherms is in accordance with the TEM result. Thermogravimetric analysis, Fourier-transform infrared spectroscopy, Zeta potential measurements and photoluminescence measurements show that 3-aminopropyltriethoxysilane (APTES) and doxorubicin were grafted and loaded successfully onto MCM-41 nanoparticles. An assay on fibroblasts, A549 and doxorubicin-resistant A549/DOX cells indicates that the prepared MCM41 grafting APTES nanoparticles are safe to normal cells and toxic to cancer cells in vitro.

Lobophora sp., belonging to brown macro algae phylum, is found in coral reefs. In this study, the fatty acid composition, lipid classes, polar lipid molecular forms, and bioactivities of this algae have been determined. It follows that five classes including polar lipid (Pol), sterol (ST), free fatty acids (FFA), triacylglycerol (TAG), and hydrocarbon and wax (HW), 23 fatty acids containing 5 PUFAs (ALA, GLA, AA, EPA, and DHA) and 157 molecular types of polar lipid group containing 48 phospholipid molecular forms belonging to 4 subclasses (PI (11), PC (14), PG (22), PA (1)), 45 glycolipid molecular forms classified into 3 subclasses of MGDG (8), DGDG (1), SQDG (36), and 64 betaine lipid molecular forms belonging to 2 subclasses (DGTA (37), DGTS (27)) have been identified for the first time from this algae. Furthermore, both polar lipid (PL) and unpolar lipid (UPL) show the NO inhibition activities with values of IC50 ranging from 52.10 to 66.21 µg/mL. Thus, lipid of this brown algae could promise to be a potential source for application in food, cosmetic, and pharmaceutic industry.

Two new glycosylated alkylresorcinols, resorcinosides A (1) and B (2), were isolated from a strain of the fungus Penicillium janthinellum derived from a marine sediment sample collected from Cu Lao Cham Island, Vietnam. The structures of 1 and 2 were established by interpretation of 1D and 2D NMR and high-resolution ESIMS data, and their absolute configurations were confirmed by the coupling constant of the anomeric proton, acid hydrolysis, subsequent HPLC analysis, Mosher's method, and quantum-mechanics-based computational analysis of NMR chemical shifts. The structure elucidation indicated that 1 and 2 are new alkylresorcinols with d-glucose, and 2 has an α-pyrone moiety attached to the aromatic ring. Compound 1 exhibited cytotoxic activity against the NUGC-3 cancer cell line with a GI50 value of 9.3 μM.

Measuring solution concentration plays an important role in chemical, biochemical, clinical diagnosis, environmental monitoring, and biological analyses. In this work, we develop a transmission-mode localized surface plasmon resonance sensor chip system and convenient method which is highly efficient, highly sensitive for detection sensing using multimode fiber. The plasmonically active sensor’s surface AuNPs with high-density NPs were decorated onto 1 cm sensing length of various clad-free fiber in the form of homogeneous monolayer utilizing a self-assembly process for immobilization of the target molecule. The carboxyl bond is formed through a functional reaction on the sensor head. Using the significance in the refractive index difference and numerical aperture, which is caused by a variation in the concentration of measuring bovine serum albumin (BSA) protein which can be accurately measured by the output signal. The refractive index variation of the medium analyte layer can be converted to signal output power change at the He–Ne wavelength of 632.8 nm. The sensor detection limit was estimated to be 0.075 ng ml−1 for BSA protein which shows high sensitivity compared to other types of label-free optical biosensors. This also leads to a possibility of finding the improvement in the sensitivity label-free biosensors. The conventional method should allow multimode fiber biosensors to become a possible replacement for conventional biosensing techniques based on fluorescence.

This computational and experimental work aims to elucidate physicochemical and photophysical natures of free radical scavenging and ultraviolet radiation (UVR) filtering activities of five terpenoids available in the extract of marine fungus. The antioxidant activities of ochraceopone F (C1), aspertetranone D (C2), cycloechinulin (C3), wasabidienone E (C4), and mactanamide (C5) are evaluated by using density functional theory (DFT) at the M05-2X/6-311++G(d,p) level of theory in the gas phase, water, and pentyl ethanoate (PEA). Double antioxidant mechanisms allowing the second (H+/e-) donation such as double hydrogen atom transfer (dHAT), double single electron transfer-proton transfer (dSET-PT), and double sequential proton loss-electron transfer (dSPL-ET) are considered. Reaction enthalpies (ΔrH0), standard Gibbs free energies (ΔrG0) and potential energy surfaces of reactions toward HOO• radical are then established to evaluate the hydrogen transfer (HT) and radical adduct formation (RAF) mechanisms. The computational results are supported by DPPH• and ABTS•+ antioxidant essays. Results show that all compounds C1-C5 are able to scavenge two free radicals via dHAT, dSET-PT, and dSPL-ET mechanisms. Among the compounds, C3 and C4 represent the most potential antioxidants, especially via HAT and RAF mechanisms in all the reaction media. Their rate constants for both HAT and RAF reactions are remarkably higher than that of Trolox and ascorbic acid. The kinetic calculations on activation Gibbs free energies (ΔG⧧) and rate constants (kTST) based on conventional transition state theory (TST) reveal that HAT and RAF processes are in competition in solvents. Photophysical processes occurring during UVR exposure are investigated using the time dependent density functional theory (TD-DFT) combined with UV-vis experiments. The obtained results highlight the promising activities of C1-C5 in UVR absorption in the ranges of UVA and UVB. Among them, C3 and C4 also show better UV absorption properties with the easiest excitations (band gaps equal to 4.06 and 3.65 eV). This study suggests the natural candidates possibly used in organic sunscreen.

The structure of sulfated polysaccharides extracted from green seaweed Ulva lactuca has been determined using NMR experiments. The obtained results indicate that this natural product is mainly composed of disaccharide A3S: [→4)-β-d-GlcA-(1 → 4)-α-l-Rha3S-(1→] and B3S: [→4)-α-l-IdoA-(1 → 4)-α-l-Rha3S-(1→]. The computational calculations using density functional theory (DFT) at the B3LYP/6–311+G(2d,p)//B3LYP/6–311G(d,p) model chemistries were also investigated to analyze the obtained structures based on the comparison of 1H and 13C NMR chemical shifts. The DFT results also confirm that the A3S structure is more dominating than the B3S one with the mean absolute error of 1H and 13C NMR chemical shifts, respectively, equal to 0.46 and 4.98 ppm for the A3S and to 2.07 and 5.03 ppm for the B3S.

The title compound, C24H29NO4, is the product of a Petrenko–Kritchenko condensation of 1,5-bis(2-formylphenoxy)-3-oxapentane, pentan-3-one and methylammonium acetate in ethanol. The molecule has mirror symmetry. The aza-14-crown-3 ether ring adopts abowlconformation stabilized by a weak intramolecular C—H...O hydrogen bond. The conformation of the C—O—C—C—O—C—C—O—C polyether chain is t–g+–t–t–g−–t (t =trans, 180°; g =gauche, ±60°). The dihedral angle between the benzene rings fused to the aza-14-crown-4-ether moiety is 72.68 (4)°. The piperidinone ring adopts achairconformation. The nitrogen atom has a trigonal–pyramidal geometry, the sum of the bond angles being 335.9°. In the crystal, the molecules are linked by weak C—H...O interactions, forming zigzag chains propagating along the [100] direction.

Two new glycosylated alkylresorcinols, resorcinosides A (

The title compound, C

The brown alga Hormophysa cuneiformis collected from the coastal waters of Vietnam was used to isolate a mixture of sulfated polysaccharides FHC, which was fractionated further by anion-exchange chromatography on DEAE-Sephacel. The main fraction F3 eluted with 1.5 M NaCl contained essentially l-fucose, d-galactose and sulfate and has very complex NMR spectra. Desulfation to obtain F3deS followed by Smith degradation to obtain F3deS-Sm was used to simplify the structure of F3, and all these preparations were characterized by methylation analysis and NMR spectra. A linear (1 → 3)-linked backbone built up of α-l-fucopyranose residues was identified as the main structural motif of molecules. Some fucose residues attached to position 4 of its 3-linked neighbor were found as branches. Galactose residues having both α- and β-configurations were found mostly at the periphery of molecules. They are present as (1 → 6)-linked disaccharide of two β-d-Galp attached to position 4 of the backbone or as single α-d-Galp attached to the same position. Sulfate groups in F3 may probably occupy any positions of the molecule. F3 acts as anticoagulant and is about half as active as the standard low-molecular mass heparin (enoxaparin). FHC was practically inactive in cytotoxicity test against six human cancer cell lines.

The aim of this study is to elucidate the structure and investigate the antimicrobial activity of an ulvan obtained by water extraction from green seaweed Ulva reticulata collected at Nha Trang sea of Vietnam by using IR, NMR, SEC-MALLS and SAXS methods. The ulvan is composed of rhamnose, galactose, xylose, manose and glucose (mole ratio Rha: Gal: Xyl: Man: Glu = 1:0.12:0.1:0.06:0.03), uronic acid (22.5%) and sulphate groups (17.6%). Chemically structural determination showed that the ulvan mainly composed of disaccharide [→4)β-D-GlcA(1→4)α-L-Rha3S-(1→]. The results from SAXS indicated that ulvan under study has a rod-like bulky chain conformation. Ulvan from U. reticulata showed high antimicrobial activity, with inhibition zone diameter of 20 mm against Enterobacter cloace and 18 mm against Escherichia coli.

A fucoidan preparation named FSA was isolated from the brown alga Sargassum aquifolium collected from the coastal waters of Vietnam. l-Fucose, d-galactose, d-mannose, d-glucuronic acid, d-xylose, and sulfate were found to be the main constituents of FSA. The preparation was fractionated by anion-exchange chromatography on DEAE-Sephacel eluted stepwise with 0.5, 1.0, 1.5, and 2.0 M NaCl to give four fractions differing in monosaccharide composition and degree of sulfation. Their NMR spectra were too complex to be completely interpreted. Fractions 1.0 M and 1.5 M were analyzed by methylation before and after desulfation. In addition, desulfated 1.0 M was fractionated by anion-exchange chromatography into six fractions according to the uronic acid content. They were characterized by methylation and NMR spectral data, and three structurally different polysaccharides were identified. One of them has a core of alternating 2-linked α-d-Manp and 4-linked β-d-GlcpA residues, about a half of the former bearing single α-l-Fucp or β-d-Xylp at position 3. The second polymer is a (1 → 3)-β-d-glucopyranuronan partially substituted with single β-d-Xylp or single α-l-Fucp at position 4. The third polysaccharide is a xylo(fuco)galactan having a linear core of alternating 4-linked α-d-Gal and 3-linked β-d-Gal residues. The latter bear single β-d-Xylp or a short chain of 4-linked β-d-Xyl, 6-linked β-d-Gal, and variously linked α-l-Fuc. In FSA, these polysaccharides are sulfated at different positions and devoid of regularity. Fractions of FSA possess anticoagulant, cytotoxic, and antitumor activities, which increase with the degree of sulfation. The most sulfated fraction 2.0 M that contains mainly a sulfated fucogalactan, is about half as active as anticoagulant as the standard low-molecular mass heparin (enoxaparin).

The thermal spray has been commonly used in several applications to replace the plating technology due to high adhesion, low cost, and environmental pollution. The thermal coating is usually used to rehibilitate the small disrepair of the crankshaft but the dimension and mechanical properties of such parts are still maintaned. Commonly, the microstructure and mechanical properties are greatly affected by depth of thermal coating, and thermal coating needs to be conducted the heat treatment to homogenize the microstructure between metals of coating and base metals as well as to improve the adhesion, hardness, and wear intensity. In this work, the effects of heat treatment on the microstructure and mechanical properties of the coating layer based on 80Ni-20Cr onto the surface of CT38 steel were conducted. SEM images and EDS analysis were used to determine the distribution of elements before and after heat treatment. In addition, mechanical properties such as Vicker hardness (HV), wear intensity, and adhesion were practically measured. As a result, after heat treatment by annealing under 1100oC during 8h, HV and adhesion were significantly higher than the case of non-heat treatment; meanwhile, wear intensity was found with 3 times lower compared to the unheated sample. The strong bi-lateral diffusion between Cr from coating layer and C from CT38 steel component to form carbide along with a formation of bond Ni-Fe was thought to be the main cause resulting in the improvement of mechanical properties and was demonstrated in this study.

Macrocyclic 22,24,25-trimethyl-8,11,14-trioxa-25-aza­tetra­cyclo­[19.3.1.02,7.015,20]penta­cosa-2,4,6,15 (20),16,18-hexaen-23-one obtained by a Petrenko–Kritchenko condensation of 1,5-bis­(2-formyl­phen­oxy)-3-oxa­pentane, pentan-3-one and methyl­ammonium acetate has been studied by X-ray structural analysis., The title compound, C24H29NO4, is the product of a Petrenko–Kritchenko condensation of 1,5-bis­(2-formyl­phen­oxy)-3-oxa­pentane, pentan-3-one and methyl­ammonium acetate in ethanol. The mol­ecule has mirror symmetry. The aza-14-crown-3 ether ring adopts a bowl conformation stabilized by a weak intra­molecular C—H⋯O hydrogen bond. The conformation of the C—O—C—C—O—C—C—O—C polyether chain is t–g+–t–t–g−–t (t = trans, 180°; g = gauche, ±60°). The dihedral angle between the benzene rings fused to the aza-14-crown-4-ether moiety is 72.68 (4)°. The piperidinone ring adopts a chair conformation. The nitro­gen atom has a trigonal–pyramidal geometry, the sum of the bond angles being 335.9°. In the crystal, the mol­ecules are linked by weak C—H⋯O inter­actions, forming zigzag chains propagating along the [100] direction.

The structure of an ulvan obtained by water extraction from green seaweed Ulva lactuca was elucidated by using IR, NMR, SEC-MALL and ESIMS methods. The ulvan was also evaluated for its cytotoxic effects on three human cancer cell lines. The results showed that the ulvan was composed of rhamnose, galactose, xylose, manose, glucose (with a mole ratio of Rha: Gal: Xyl: Man: Glu equal to 1: 0.03: 0.07: 0.01: 0.06), uronic acid (21.5%) and sulfate content (18.9%) with a molecular weight of 347000. This ulvan mainly consists of disaccharide [→4)-β-d-GlcA-(1→4)-α-l-Rha3S-(1→] and other minor disaccharide β-GlcA-(1→2)-α-Xyl and β-GlcA-(→2)-α-Rha. The ulvan showed a significant cytotoxic activity against hepatocellular carcinoma (IC50 29.67±2.87μg/ml), human breast cancer (IC50 25.09±1.36μg/ml), and cervical cancer (IC50 36.33±3.84μg/ml).

The silver embedded silica powders (Ag/SiO2) have been successfully prepared by sol-gel method. Ag nanoparticles were formed from the thermal decomposition of the silver nitrate. X-ray diffraction shows that the silver nanocrystals have appeared after a heat-treatment at 600 °C. TEM images show that the spherical silver particles with an average size around 30 nm dispersed homogeneously in silica matrix. The data of XRD, Raman and FTIR spectroscopy prove that the formation of the silver nanocrystals influent on the structural evolution of the silica matrix. The presence of metal nanocrystals leads to remarkable decrease in crystallizing temperature of SiO2. In addition, the adsorption-desorption analysis indicated that the growth of Ag particles makes the pores in silica structure widen.