Phytochemicals Analysis, Antioxidant Capacities and Antimicrobial Properties of Ethyl Acetate Extract of Stem Bark of the Garlic Tree Scorodocarpus borneensis Becc.

The objective of this study was to examine the phytochemical components, antioxidant activity and antibacterial property of ethyl acetate extract of the stem bark of garlic tree （Scorodocarpus borneensis）. The dried stem bark of S. borneensis were collected and homogenized after drying at room temperature （32℃） for 30 d. The stem barks were extracted by macerated method using 95% ethanol and then fractionated with ethyl acetate. The dried ethyl acetate extract was subjected to phytoehemical screening to determine the presence of bioactive components using gas chromatography-mass spectrometry （GC-MS）. Antioxidant activity of the extract in vitro was examined by 2,2-diphenyl-l-picryl-hydrazyl （DPPH） radical scavenging assay. The antibacterial activity against gram-positive bacteria Staphylococcus aureus and gram-negative bacteria Escherichia coli was performed by disc diffusion assay. GCMS results revealed the presence of 14 different phytocompounds, viz, tetratriacontyl trifluoroacetate （41.61%）, 2-pentanone （13.65%）, oxacyclotetradecane-2,11-done （7.87%）, cinnamic acid （7.53%）, 10-octadecanoic acid （6.50%）, 1,2-benzeno dicarboxylix acid （4.99%）, octadecanoic acid （4.51%）, hexadecanoic acid （4.16%）, beta tumerone （3.01%）, 9-octadecenoic acid （1.70%）, tricosanol （1.38%）, hexadecano-phenone （1.36%）, 1-nonadecanol （0.93%） and n-nonadecanol （0.82%）. In vitro antioxidant activity （IC50） was found at 55.524 ppm as high powerful. The results of agar diffusion method showed that the ethyl acetate extracts had an antibacterial activity of 6.687 ± 0.800 mm againts S. aureus at 10% （w/v） and 7.500 ± 0.735 mm against E. coli at 10% （w/v） as moderate category. These findings suggest that S. borneensis stem bark is a valuable sources of bioactive compounds with promising as antioxidant and antibacterial sources.

Antimicrobial Properties of Copper and d-Orbital Capture

The purpose of this note is to stimulate interest in measuring and characterizing the emitted ultraviolet frequencies in antimicrobial copper materials. Antimicrobial sanitizing materials are urgently needed to limit the spread of COVID-19 virus. In the current pandemic, ultraviolet radiation is often used for sterilization. It is shown that 3 d-orbital capture in copper can result in radiation generated by copper materials. Since ultraviolet radiation is known to be effective in antimicrobial sterilization, it is logical to assume that the radiation formed by copper occurs in the ultraviolet region. Electron transitions in 3 d-orbital capture are expected to occur in this region. A description of the 3 d-orbital capture process, and the origin of the associated frequency, is given. It is shown that for Group 1B elements the strength of electron affinity in the d-orbital capture process increases with increasing Periodic Table period number, n. This is the opposite of other electron affinity properties for atoms that decrease wth an increase in n. A brief discussion of the relationship of d-orbital capture to the chemical inertness of gold is given. The same type of d-orbital capture process that occurs in antimicrobial copper occurs in high temperature superconducting cuprates.

Synthesis of coral-like structures of Pr-Yb co-doped YIG: Structural,optical, magnetic and antimicrobial properties

Coral-like structures of the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12),(0.00 ≤ x ≤ 0.04, 0.00 ≤ y ≤ 0.02) compound were synthesized using the sol-gel method. Structural investigation certified the YIG cubic crystal structure formation, without any secondary phase. It is shown that, the relatively large ionic radius of the dopant cations results in an expansion of the lattice parameter, variations in the Iona-O-Iondangle, Iona-O,Iond-O and Ionc-O bond distances and decrease in the average crystallite size. Fourier transform infrared(FTIR) and Raman measurements are essential to testify the single-phase formation of YIG crystal structure and are observed changes in the stretching and vibrational modes, respectively. The morphological study, energy dispersive spectroscopy(EDS) spectra and textural properties show corallike structures, peaks associated with Pr^(3+) and Yb^(3+) atoms and the effect of dopants on surface area,diameter, and pore volume, respectively. The optical analysis from diffuse reflectance spectra witnessed an increase in the optical gap band, a decrease in Urbach energy and blue shift in the charge transfer,correlated with the expansion of the unit cell due to the dopant's insertion in the YIG structure. A typical ferrimagnetic behavior is exhibited by the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12)compound. The saturation magnetization(M_(s)), cubic anisotropy constant(K_(1)) and coercive field(H_(c)) increase with the Pr^(3+)cations content, as consequence of their magnetic nature and distribution around of Fe^(3+)ions due to the coexistence with the Yb^(3+). Finally, for the first time, antibacterial tests by mean of the direct contact method were performed for YIG co-doped with Pr^(3+)and Yb^(3+)and it is shown that, relatively high dosages of Pr^(3+) cations favored the activity against S. aureus, therefore, a new biological property for YIG doped with rare earths is presented.

Ultraviolet Resistance and Antimicrobial Properties of ZnO in the Polypropylene Materials:A Review

ZnO is a multifunctional material with UV-blocking,antimicrobial,photo-catalytic activity and selfcleaning properties.The application of ZnO has become an interesting subject both in science and industries in the polymer materials.A great number of investigation indicated that introduction of ZnO can improve ultraviolet resistance and endow antimicrobial properties of polypropylene(PP) materials to broaden the application range and prolong the usage life of polypropylene materials.This mini-review contains examples of recent research advances on ultraviolet resistance and antimicrobial properties of ZnO in the filled polypropylene materials.It is found that ultraviolet resistance and antimicrobial properties of ZnO supported on the surface of other inorganic particles are higher than those of nanoand micro-ZnO particles,which may inspire further developments of filled PP and its copolymer materials with high ultraviolet resistance and antimicrobial properties.

Influence of stabilizers on the antimicrobial properties of silver nanoparticles introduced into natural water

Physical, chemical and biochemical properties of silver nanoparticles （AgNPs） depend to a great extent on their size, shape, size distribution, and stabilizers located on their surface. This study focused on two typical stabilizers, namely citrates （cit）, low molecular ions protecting nanoparticles by electrostatic repulsion, and polyvinylpyrrolidone （PVP）, a hydrophilic, neutral, high molecular polymer protecting nanoparficles by steric stabilization. Natural bacterioplankton was collected from a eutrophic, downtown lake and exposed to five concentrations （0.1-5 mg/L） of AgNPs-PVP and AgNPs-cit. Responses were monitored after 1, 3, 5 and 7 days of exposure, by evaluating the survival rate of bacteria, their respiratory activity, and the general activity of extracellular esterases. A significantly better （greater） survival rate of bacterioplankton was observed in water with an addition of AgNPs-cit. The inhibition of extracellular esterases was observed only in samples containing AgNPs-PVP. The inhibitory effect increased proportionally to the concentration of AgNPs-PVP applied. Within the studied concentration range, there was no statistically significant inhibition of bacterioplankton respiratorv activity bv AgNPs-PVP and AgNPs-cit.

Chitosan as A Preservative for Fruits and Vegetables:A Review on Chemistry and Antimicrobial Properties

Chitosan,derived from chitin,a major constituent(in quantity)of crustaceans,is a unique aminopolysaccharide with emerging commercial potential in agriculture,food,pharmaceuticals and nutraceuticals due to its nontoxic,biodegradable and biocompatable properties.Chitosan coating on fruits and vegetables has been found to be effective for the reduction of a variety of harmful micro-organims and extend the shelf-life of these products.In this review,our focus is on the antimicrobial properties of chitosan and its application as a natural preservative for fresh products.We detailed the key properties that are related to food preservation,the molecular mechanism of the antimicrobial activity of chitosan on fungi,gram-positive and gram-negative bacteria,coating methods for using chitosan and its formulation for preserving fruits and vegetables,as well as the radiation method of producing chitosan from chitin.Understanding the economic and scientific factors of chitosan’s production and efficiency as a preservative will open its practical application for fruits and vegetable preservation.

Preparation and physicochemical/antimicrobial characteristics of asparagus cellulose

Due to the increased potential for application of natural biopolymers in the food industry,the goal of this study was to prospectively produce antimicrobial films using asparagus residue.In this study,cellulose was extracted from asparagus residue,and then 3 cellulose solutions of 0.008,0.01 and 0.025 g/mL were applied to prepare films using a phase inversion process.Films were characterized by Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),thermal gravimetric analysis(TGA)and scanning electron microscopy(SEM).The film produced by 0.01 g/mL asparagus cellulose solution exhibited a swelling ratio of 125.4%and excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus using the disk agar diffusion method.This study presents a promising method for producing antimicrobial films with asparagus residue.

Single Step Microwave Assisted Synthesis and Antimicrobial Activity of Silver, Copper and Silver-Copper Nanoparticles

Copper and silver nanoparticles were synthesized and characterized in two minutes at 175°C in a one-step synthesis using a modified polyol (ethylene glycol) method and a microwave heating process. We successfully synthesized spherical Silver (Ag) and Copper nanoparticles (CuNP) with a crystallite size of less than 10 nm, as well as irregular silver-copper nanoparticles (AgCuNP) with a crystallite size of less than 15 nm, as confirmed by X-Ray Diffraction (XRD) and High-Resolution Transmission Electron Microscopy (HRTEM). The successful synthesis of AgCuNP with 1:1 molar ratio and constituted by 51.74% of copper and 48.26% of silver was corroborated using the Energy Dispersive X-ray (EDX) mapping technique. The AgNP and AgCuNP exhibited more stability in suspension, in comparison to CuNP, as observed by continuously monitoring the absorbance with UV-Vis spectroscopy for 12 days. Furthermore, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of AgNP, CuNP, and AgCuNP were determined, against Gram-negative and Gram-positive bacteria, and yeast. The obtained MIC and MBC values indicate that AgCu nanoparticles exhibited bactericidal properties greater than its constituents. On the contrary, antifungal activity of AgCuNP against yeast was not observed.

Antimicrobial Property of 2-Hydroxypropane-1,2,3-Tricarboxylic Acid Isolated from Citrus microcarpa Extract

This article described antimicrobial property and structure analysis of 2-hydroxypropane-1,2,3-tricarboxylic acid isolated from the crude extract of Citrus microcarpa. Presently, there was no report on compound from C. microcarpa that possessed antimicrobial property against fish pathogenic bacteria. Therefore, in this study, the bioactive principle in C. microcarpa extract was isolated using thin layer chromatography. It＇s structure was elucidated based on nuclear magnetic resonance （NMR） spectroscopic data, such as proton NMR （1HNMR）, correlation spectroscopy, carbon 13 NMR, and heteronuclear multiple bond correlation data. This study showed that the bioactive compound isolated from C. microcarpa was 2-hydroxypropane-1,2,3-tricarboxylic acid monohydrate. The minimum inhibitory concentration （MIC） values of crude C. microcarpa extract and its bioactive component, 2-hydroxypropane-1,2,3-tricarboxylic acid as well as commercially available synthetic 2-hydroxypropane-1,2,3-tricarboxylic acid, were determined against 18 isolates of Edwardsiella tarda and 7 bacterial reference strains, namely, Escherichia coli （ATCC 25922）, Citrobacter freundii （ATCC 8090）, Aeromonas hydrophila （ATCC 49140）, Pseudomonas aeruginosa （ATCC 35032）, Streptococcus agalatiae （ATCC 13813）, E. tarda （ATCC 15947）, and Yersinia enterocolitica （ATCC 23715）, using two-fold microdilution method. The MIC values for both the natural 2-hydroxypropane-1,2,3-tricarboxylic acid and the synthetic one were ranging from 15.6 to 62.5 mg mL-1, whereas that of the crude extract was ranging from 7.8 to 31.3 mg mL-1. These findings showed that both the crude extract and its bioactive component might have potential as antimicrobial agent for aquaculture use.

Comparative study between three carbonaceous nanoblades and nanodarts for antimicrobial applications

The design of nanostructured materials occupies a privileged position in the development and management of affordable and effective technology in the antibacterial sector.Here,we discuss the antimicrobial properties of three carbonaceous nanoblades and nanodarts materials of graphene oxide(GO),reduced graphene oxide(RGO),and single-wall carbon nanotubes(SWCNTs)that have a mechano-bactericidal effect,and the ability to piercing or slicing bacterial membranes.To demonstrate the significance of size,morphology and composition on the antibacterial activity mechanism,the designed nanomaterials have been characterized.The minimum inhibitory concentration(MIC),standard agar well diffusion,and transmission electron microscopy were utilized to evaluate the antibacterial activity of GO,RGO,and SWCNTs.Based on the evidence obtained,the three carbonaceous materials exhibit activity against all microbial strains tested by completely encapsulating bacterial cells and causing morphological disruption by degrading the microbial cell membrane in the order of RGO>GO>SWCNTs.Because of the external cell wall structure and outer membrane proteins,the synthesized carbonaceous nanomaterials exhibited higher antibacterial activity against Gram-positive bacterial strains than Gram-negative and fungal microorganisms.RGO had the lowest MIC values(0.062,0.125,and 0.25 mg/mL against B.subtilis,S.aureus,and E.coli,respectively),as well as minimum fungal concentrations(0.5 mg/mL for both A.fumigatus and C.albicans).At 12 hr,the cell viability values against tested microbial strains were completely suppressed.Cell lysis and death occurred as a result of severe membrane damage caused by microorganisms perched on RGO nanoblades.Our work gives an insight into the design of effective graphene-based antimicrobial materials for water treatment and remediation.

Soy Protein Isolate Film by Incorporating Mandelic Acid as Well as Through Fermentation Mediated by Bacillus Subtilis

Soy protein isolate(SPI)biopolymeric films were prepared by adding different contents of mandelic acid(1 to 5%wrt SPI)to glycerol plasticized SPI by solution casting method.Also,SPI was fermented by Bacillus subtilis to get fermented SPI films by solution casting.Molecular mass determination of mandelic acid incorporated and fermented SPI films was carried out by sodium dodecyl sulphate-polyacrylamide gel electrophoresis(SDS-PAGE).Mandelic acid incorporated and fermented SPI films were characterized by Fourier-transform infrared spectroscopy(FT-IR),dynamic mechanical analysis(DMA),tensile strength,water uptake and optical transmittance studies.Results indicated that incorporation of mandelic acid in SPI resulted in high tensile strength(8.03 MPa)and highα-relaxation(Tα)as well as low water uptake.On the other hand,films cannot be prepared from fermented SPI with SPI contents of 8%and 12%.However,film from fermented SPI with 16%SPI content could be prepared but it exhibited low tensile strength(3.18 MPa)and low Tαas well as high water uptake.The resulting mandelic acid incorporated SPI films were also subjected to antimicrobial studies.At all the concentration of mandelic acid,we can easily observe the antimicrobial effect in mandelic acid incorporated SPI films unlike fermented SPI films.This work will be helpful in fabricating antimicrobial SPI film from renewable resources.

ZnSe Nanoparticles Reinforced Biopolymeric Soy Protein Isolate Film

ZnSe nanoparticles have been synthesized by microwave assisted method by using zinc chloride,selenium powder and ethylene diamine.The synthesized nanoparticles have been characterized structurally by FT-IR and XRD as well as morphological characterization was done by scanning electron microscope(SEM).The crystallite size after synthesis was obtained around 30 nm for pure ZnSe nanocrystallites.However,from SEM micrograph,agglomerated ZnSe nanoparticles of irregular shapes were observed.The as-synthesized ZnSe nanoparticles at different contents(1 to 5%w/w w.r.t SPI)were incorporated into soy protein isolate(SPI)to produce reinforced SPI films by solution casting method.The ZnSe nanoparticles incorporated SPI suspensions were subjected to molecular mass and specific conductivity studies.Neat and ZnSe nanoparticles incorporated SPI films were structurally and mechanically characterized by FT-IR and tensile properties,respectively.Transmittance and water uptake studies were also carried out for ZnSe nanoparticles incorporated SPI films.The tensile strength and modulus increased from 5.80 MPa to 10.06 MPa and 18.84 MPa to 94.70 MPa with the increase in the contents of ZnSe nanoparticles from 0 to 5%.Moreover,the results also revealed a good antibacterial effect in ZnSe nanoparticles incorporated SPI film.The main application of nanoparticles incorporated SPI film will be in the area of biodegradable packaging.

Health promoting activities and corresponding mechanism of(–)-epicatechin-3-gallate

(–)-Epicatechin-3-gallate(ECG),a bioactive polyphenolic compound,has contributed a lot to the health benefits of green tea.Great attention has been focused on(–)-epigallocatechin-3-gallate(EGCG),but limited research has been performed towards ECG.Like EGCG,ECG also possesses various pharmacological and physiological properties,such as mediation of antioxidant activities,anti-inflammation response,regulation of cell proliferation and apoptosis,as well as anticancer properties during angiogenesis,invasion and metastasis stages.Nontoxic ECG has various molecular targets within the cells,including CYP enzymes,phaseⅡdetoxification and antioxidant enzymes,as well as pro-inflammatory mediators.The antineoplastic mechanism contains inhibition of phase 1 CYP enzymes,induction of phaseⅡdetoxification and antioxidant enzymes,high anti-inflammatory efficacy,arrest of cell cycle progression,regulation of apoptosis,as well as mediation of metastasis processes.In particular,the gallate moiety of ECG is critical for mediating inhibitory effects towards cancer cells.Besides regulation of intracellular signaling pathways,ECG also inhibits RNase A and matrix metalloproteinase enzymatic activity via chelating metals(copper and zinc)in cancer cells.This review has summarized recent studies on pharmacological properties of ECG,and discussed corresponding mechanism on modulation of cellular signaling events by ECG,hoping to broaden its multiple usage.

Fabricating a reactive surface on the fibroin film by a room-temperature plasma jet array for biomolecule immobilization

A simple dielectric barrier discharge（DBD） jet array was designed with a liquid electrode and helium gas.The characteristics of the jet array discharge and the preliminary polymerization with acrylic acid（AA） monomer were presented.The plasma reactor can produce a cold jet array with a gas temperature lower than 315 K,using an applied discharge power between 6 W and 30 W（V dis × I dis）.A silk fibroin film（SFF） was modified using the jet array and AA monomer,and the treated SFF samples were characterized by atomic force microscopy（AFM）,scanning electron microscopy（SEM）,Fourier transform infrared spectroscopy（FTIR）,and contact angle（CA）.The deposition rate of the poly acrylic acid（PAA） was able to reach 300 nm/min,and the surface roughness and energy increased with the AA flow rate.The FTIR results indicate that the modified SFF had more carboxyl groups（-COOH） than the original SFF.This latter characteristic allowed the modified SFF to immobilize more quantities of antimicrobial peptide（AP,LL-37） which inhibited the Escherichia coli（E.Coli） effectively.

Effect of PLA/ZnO Packaging and Gamma Radiation on the Content of Listeria innocua, Escherichia coil and Salmonella enterica on Ham during Storage at 4℃

The effect of ZnO and low y-radiation on PLA based-films was investigated to be used for food packaging application. Ham slices were inoculated with E. coli, L. innocua and S. enterica and then covered with PLA and PLA/5% ZnO films. The samples were irradiated with a y-radiation dose of 0.3 kGy at dose rate of 13.5 kGy/h. Microbiological analysis was performed at 0, 1 and 5 days on samples stored at 4 ℃. Results showed that no consistent reduction of bacteria was obtained, even at the fifth day of storage, when the ham was covered with PLA/5% ZnO film and no γ-radiation was performed. The use of γ-radiation results necessary to reduce the bacteria growth. In fact E. coli and S. enterica were not detected after 5 days of storage; whereas in the case of test with L. innocua a reduction of 1.3 log CFU/g was observed after 5 days of storage. The antibacterial results indicate that the presence of ZnO in PLA film is effective only for E. coll. The differences of the results obtained here with those reported in literature （where ZnO particles are reported to be very effective as antimicrobial material） are accounted for the different methodologies used. In conclusion considering the positive results, even if small, obtained here at least only for the E. Coli and considering that PLA/5% ZnO film shows, compared to plain PLA film, good tensile properties （especially Young＇s modulus and stress at yielding） and good permeability （to O2 and CO2） induce to consider the PLA/5% ZnO composite film usable for food packaging when long shelf life and food safety are required, considering also that it is biodegradable and compostable.

CHEMICAL VARIATION OF ESSENTIAL OILCONSTITUENTS OF OCIMUM GRATISSIMUM LINN FROM BENIN AND INFLUENCE ON ANTIMICROBIAL AND ANTIPARASITIC PROPERTIES

Previous work has shown great variations in the chemical composition of Ocimum gratissimum Linn essential oils(EOs).Our aim was to study the influence of this variation on their antimicrobial,anti-parasitic effects and toxicity.Methods:EOs from aerial part collected in two vegetative stages and three moments of harvest were isolated by hydrodistillation and analysed by GC/MS and GC/FID.

Green synthesis,characterization and antimicrobial activity of silver nanoparticles using methanolic root extracts of Diospyros sylvatica

The current research study focuses to formulate the biosynthesized silver nanoparticles for the first time from silver acetate using methanolic root extracts of Diospyros sylvatica,a member of family Ebenaceae. TEM analysis revealed the average diameter of Ag NPs around 8 nm which is in good agreement with the average crystallite size（10 nm）calculated from X-ray Diffraction（XRD）analysis. Further the study has been extended to the antimicrobial activity against test pathogenic Gram（＋）ve,Gram（-）ve bacterial and fungal strains. The bioinspired Ag-NP showed promising activity against all the tested bacterial strains and the activity was enhanced with increased dosage levels

Effect of Cu Addition in Pipeline Steels on Microstructure,Mechanical Properties and Microbiologically Influenced Corrosion

In the present study, Cu-modified pipeline steels were fabricated to mitigate MIC by the antimicrobial ability of Cu element. The microstructure, mechanical properties and the antimircobial performance of the Cu-modified steel were systematically investigated. The Cu-modified steels showed good antimicrobial performance with remarkable strength enhancement by nanoscale Cu-rich precipitates and good impact toughness without changing the original base microstructures after the optimal aging treatment of 500 °C/1 h.

Achieving higher performances without an external curing agent in natural magnolol-based epoxy resin

Bio-based epoxy thermoset prepared from renewable biomass raw materials can alleviate fossil energy crisis and reduce environmental pollution,which satisfies the needs of sustainable social development.In this study,a bio-based epoxy thermoset precursor(MGOL-EP) was synthesized from a naturally occurring magnolol through a facile and efficient one-step process.And the fully bio-based epoxy thermoset(MGOL-EP-SC) was obtained by self-curing without adding any other hardener.MGOL-EP-SC revealed an extremely high glass-transition temperature(T_(g)) of 265℃ and char yield of 53.2%(in N;),which were at the highest level among the fully bio-based epoxy thermosets reported so far.In addition,when the MGOL-EP was cured with 4,4’-methylenedianiline(DDM),T_(g)of the MGOL-EP/DDM was decreased by 61℃ and the other comprehensive performance had also been decreased,which was due to a reduction in biphenyl structure content and cross-linking density by adding the external curing agents.Moreover,the MGOL-EP-SC presented certain killing rate(48.4%) to Staphylococcus aureus.These findings provide a new design strategy for engineering high-performance and functional epoxy thermoset with high biomass content.

A self-crosslinking,double-functional group modified bacterial cellulose gel used for antibacterial and healing of infected wound

Cellulose/chitosan composite,as a mature commercial antibacterial dressing,is an important type of wound repair material.However,how to achieve the perfect compound of two components and improve antibacterial activity is a major,lingering issue.In this study,a bifunctional group modified bacterial cellulose(DCBC)was prepared by carboxymethylation and selective oxidation.Further,the chitosan(CS)was compounded in the network of DCBC by self-crosslinking to form dialdehyde carboxymethyl bacterial cellulose/chitosan composites(S-DCBC/CS).The aldehyde group can react with amino of CS by Schiff base reaction.The carboxyl group of DCBC and the amorphous distribution of CS molecular chains increase the antimicrobial properties of com-posites.The bacteriostatic rate of composites could be higher than 95%.Bacteria can be attracted onto the surface of composites,what we call it“directional adhesion antibacterial effects”.In particular,a kind of large animal wound model,deep II degree infected scald of Bama miniature pig,was used to research the antimicrobial and healing properties of materials.The S-DCBC/CS can effectively inhibit bacterial proliferation of wound and kill the bacteria.The wound healing rate of S-DCBC/CS was up to 80%after three weeks.The composites show better antibacterial and promoting concrescence effects than traditional chitosan dressings.