Fourier Transform Infrared Absorption Spectra Research Articles

Selenium loaded sodium alginate/polyvinyl alcohol nanocomposite film as wound dressing: structural, optical, mechanical, antimicrobial properties and biocompatibility

In the current research, synthesized Se-NPs were loaded into sodium alginate/polyvinyl alcohol SA/PVA blend, 1:2 (w:w), with different proportions to form nanocomposite films by using the solution casting method. The main goal is to enhance the physical and antibacterial properties of the polymer blend; therefore, it can be utilized for wound dressing applications. The physical aspects of the prepared films were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), atomic force microscope (AFM), scanning electron microscope (SEM), Energy dispersive X-ray (EDX), UV–Vis spectroscopic technique, and mechanical analysis to show the effect of increasing the concentration of Se-NPs from zero to 0.5 wt% on their properties. Regarding the XRD analysis, the calculated values of lattice strain (ε\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varepsilon$$\\end{document}) increased from 0.005 to 0.013. The FTIR absorption spectrum recorded an intensity reduction and position shift in the main characteristic peaks of SA/PVA. The morphology of Se-NPs revealed a spherical shape with a mean diameter of 131.76 nm, as revealed by transmission electron microscopy (TEM). The surface morphological images showed the appearance of a few cracks; besides, the average roughness increased from 1.59 to 2.08 nm. According to the UV–Vis spectroscopic analysis, the optical band gap reduces (from 5.425 to 5.216 eV) for the direct transition and from (5.07–4.78 eV) for the indirect transition, which is an indication of the interaction between Se-NPs and SA/PVA blend. Young’s modulus, tensile strength, and yield strength of the films increased with the addition of selenium nanoparticles. On the other hand, the amount of selenium release significantly increased with enhancing the concentration of Se-NPs in SA/PVA blend film from 0.1 to 0.5 wt%. Additionally, the inclusion of Se-NPs supplied the polymer blend with excellent antimicrobial activity, which would remove the possibility of microbial infection at the wound site. Moreover, the prepared SA/PVA/Se nanocomposite films have good biocompatibility with Human Skin Fibroblast (HSF). The results suggest the potential of this nanocomposite to be used in wound dressing applications.

Effects of Artemisia dracunculus powder on dough rheology and quality properties as a novel ingredient in bread formulation.

Tarragon has a great potential to be a healthy functional food ingredient thanks to its rich antioxidant, phenolic compounds, and nutrient content. The possibility of enriching bread with tarragon was investigated. For this aim, tarragon powder was used at the rates of 0, 2, 4 and 6% instead of wheat flour. In this study, the effects of substitution on the rheological properties of bread dough and color, total phenolic content, antioxidant activity, texture, sensory, and Fourier transform infrared (FT-IR) analysis of bread samples were performed. The composition of tarragon powder showed significant protein (23.16%), crude fiber (7.4%), antioxidant (48.22 ± 0.11%), and total phenolic content (511.66 ± 1.56 mg GAE/100 g). Bread samples with increased fiber and protein content were obtained by adding tarragon powder to the bread formulation. The major differences in the FT-IR absorbance spectra for the bread samples were not observed. Additionally, tarragon powder significantly increased the antioxidative properties of breads (p < 0.05). Adding up to 4% tarragon powder to the bread formulation increased the sensory scores of the breads.

Predicting the physical and chemical properties of sustainable aviation fuels using elastic-net-regularized linear models based on extended-wavelength FTIR spectra

A Fourier transform infrared (FTIR) spectra-based prescreening approach was developed for estimating nine important physical and chemical properties of sustainable aviation fuels (SAFs): molecular weight (MW), hydrogen-to-carbon (H/C) ratio, density, net heat of combustion (NHC), derived cetane number (DCN), threshold sooting index (TSI), initial boiling point (IBP), flash point, and kinematic viscosity (KV). A training dataset containing the vapor-phase FTIR absorption spectra of pure hydrocarbons spanning four molecular classes, blends of neat hydrocarbons, conventional jet fuels and SAFs, across the 2–15.38 μm wavelength range, was compiled. The physical and chemical properties of the fuels in the training dataset were sourced either from experimental data reported in the literature or calculated using relevant property blending correlations. Elastic-net-regularized linear models were trained for each property by optimizing the model parameters using a cross-validated grid search. The results from these models were compared with the results from previous models (Lasso-regularized linear models developed previously by Wang et al. at Stanford), which were trained on FTIR absorption spectra across the limited wavelength range of 3.3–3.55 μm. Use of the extended wavelength range and the new model-parameter optimization strategy results in significant improvement in predictive performance of the current models compared to the previous models for all nine properties. The model performance is also evaluated on three candidate SAFs. The current models are found to achieve higher property prediction accuracy than the previous models for these test fuels. Overall, this work demonstrates the utility of predictive models based on extended-wavelength FTIR spectra and their potential use as a low-volume prescreening method for characterizing properties of new sustainable aviation fuel candidates.

Formulation, Characterization, and Optimization of a Topical Gel Containing Tranexamic Acid to Prevent Superficial Bleeding: In Vivo and In Vitro Evaluations.

Tranexamic acid (TXA) is used systemically to stop bleeding, but it can lead to thromboembolism. Trials have revealed the efficacy of topical TXA on local hemorrhages. However, there is a need for an efficient delivery system that can keep the drug at the site of action. To develop a gel containing TXA (3%) optimized in terms of viscosity and dispersibility, the central composite design based on two factors-three levels [carbopol 940 and hydroxypropyl methylcellulose (HPMC), 1-1.5% and 1-2%, respectively] was applied. The spreadability and viscosity were assessed using glass slide and rheometer, respectively. To confirm the compatibility of TXA with the gel, fourier transform-infrared (FTIR) spectroscopy was performed. Drug content uniformity was analyzed by a spectroscopy method. An ex vivo mice model using Franz cells was applied to evaluate the permeation of TXA through the skin. To investigate the effect of topical TXA gel on bleeding time, IVY human method was performed. HPMC/carbopol 940 (1:1, w/w) gel showed the highest quality in terms of viscosity and dispersibility (3.982 ± 17.6 and 6.052 ± 3.562, respectively). FTIR absorption spectrum showed that all the TXA index peaks appeared without displacement. The complete-encapsulated TXA content was uniformly dispersed throughout the gel. In vitro TXA cumulative release reached 90% in 4 h. The bleeding time determined in vivo for TXA gel was significantly lower than that for TXA solution and control. The results confirm the importance of further studies on this formulation as a potential medication to stop acute superficial bleeding.

Crystal Structure, Raman, FTIR, UV-Vis Absorption, Photoluminescence Spectroscopy, TG-DSC and Dielectric Properties of New Semiorganic Crystals of 2-Methylbenzimidazolium Perchlorate.

Single crystals of 2-methylbenzimidazolium perchlorate were prepared for the first time with a slow evaporation method from an aqueous solution of a mixture of 2-methylbenzimidazole (MBI) crystals and perchloric acid HClO4. The crystal structure was determined by single crystal X-ray diffraction (XRD) and confirmed by XRD of powder. Angle-resolved polarized Raman and Fourier-transform infrared (FTIR) absorption spectra of crystals consist of lines caused by molecular vibrations in MBI molecule and ClO4- tetrahedron in the region ν = 200-3500 cm-1 and lattice vibrations in the region of 0-200 cm-1. Both XRD and Raman spectroscopy show a protonation of MBI molecule in the crystal. An analysis of ultraviolet-visible (UV-Vis) absorption spectra gives an estimation of an optical gap Eg~3.9 eV in the crystals studied. Photoluminescence spectra of MBI-perchlorate crystals consist of a number of overlapping bands with the main maximum at Ephoton ≅ 2.0 eV. Thermogravimetry-differential scanning calorimetry (TG-DSC) revealed the presence of two first-order phase transitions with different temperature hysteresis at temperatures above room temperature. The higher temperature transition corresponds to the melting temperature. Both phase transitions are accompanied by a strong increase in the permittivity and conductivity, especially during melting, which is similar to the effect of an ionic liquid.

Investigation of thermal, mechanical and dielectrical properties of LiYO2 filled poly(lactic acid) nanocomposites

In recent years, the development of portable electronic devices has increased considerably. Polymers and polymer composites are employed in a variety of industries, from structural materials to electronics, as well as in our daily lives. PLA@LiYO2 nanocomposites films were subsequently fabricated by a simple solution casting at various concentrations for the development of electronic materials. The effective doping and homogeneous dispersion of nanoparticles in PLA polymer is characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM), Fourier Transform InfraRed (FTIR) spectrophotometer, Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), elastic and dielectric properties of PLA composites films. XRD analysis showed that the crystalline characteristics of the nanocomposites increases with increase in dopant concentration. The FTIR absorption spectra of neat PLA and PLA@LiYO2 nanocomposites are almost equivalent to each other, from TGA analysis there will be less percentage of weight loss in the composite’s films as the concentration of the nanocomposites increased into PLA matrix, Moreover, a significant increase in Tg with an increase in NPs content from 0 to 4 wt% was also observed, the different elastic moduli such as E, K and G of PLA + LiYO2 films are indirectly proportional to the addition of LiYO2 in to PLA matrix. The doped PLA nanocomposites exhibit unique negative dielectric constant and AC conductivity.

Durable polyolefin encapsulants in aged photovoltaic modules

We investigated the long-term durability of thermoplastic polyolefin (TPO) encapsulants in crystalline-silicon (c-Si) photovoltaic (PV) modules that were exposed for up to approximately 10 years or damp-heat (DH)-exposed at 85 °C and 85% relative humidity (RH). No significant degradation was observed in c-Si PV module based on the TPO encapsulant after a long-term DH test at 85 °C/85% RH for 8000 h. The Fourier transform-infrared absorption spectrum indicated that oxidative degradation of the TPO encapsulant in the module occurred on the glass side after the DH test, whereas the oxidative products of the TPO encapsulant did not decrease the PV performance of the module. No significant oxidative degradation of the TPO encapsulant in the module was observed after approximately 9 years of outdoor exposure by Raman spectroscopic measurements. Our results indicate that TPO is a promising alternative encapsulation material for enhancing the long-term durability of c-Si PV modules furthermore.

Synthesis, characterization and antimicrobial study of cinnamic acid functionalized Ag nanoparticles

In order to improve the antimicrobial activity of Ag nanomaterial and minimum their toxicity, cinnamic acid has been utilized as both reducing agent and protecting ligand to synthesis of silver (Ag) nanoparticles (NPs). The synthesized cinnamic acid (CA) functionalized Ag nanoparticles (CA-AgNPs) have been characterized by Ultraviolet-visible spectrophotometry (UV), Fourier transform infrared absorption spectra (FTIR), Atomic force microscope (AFM), Transmission electron microscope (TEM). UV absorption results indicated that a strong absorption band peaked at 452 nm which can be ascribed to the surface plasmon resonance (SPR) of AgNPs. FTIR results of CA-AgNPs indicated that cinnamic acid was indeed bound on the AgNPs. TEM measurements indicated that the products are round spherical NPs with the average particle size of 52.8 nm. Antimicrobial activity tests revealed that CA-AgNPs have significant inhibitory effects on E. coli and C. albicans. The CA-AgNPs prepared in this study are expected to be developed as efficient antimicrobial agents.

Structural studies on varied concentrations of europium doped strontium phosphate glasses

In this study, the conventional melt quenching method was used to prepare pure and the europium-doped strontium phosphate-based glasses. This study aims to discover the effect of the europium content on the structural properties of synthesized glasses. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) absorption spectra were employed to examine the structural characterization of these prepared samples. XRD analysis shows that all samples of undoped and europium-doped phosphate glasses have amorphous phases. The FTIR absorption spectra demonstrated that various structural phosphate groups have been represented in the synthesized samples. The europium-doped strontium phosphate glasses can be used in many applications such as laser, optoelectronics, LED display, solar cells, and photonic devices. [Copyright information to be updated in production process].

Effect of ultrasonic thawing on the physicochemical properties, freshness, and protein-related properties of frozen large yellow croaker (Pseudosciaena crocea).

Ultrasonic treatment (UT) was used to thaw large yellow croaker in this study, and the effect of various ultrasonic power levels on the quality of large yellow croaker was evaluated after thawing. The effects of ultrasonic on water holding capacity (WHC), moisture distribution, thiobarbituric acid-reactive substance (TBARs), total volatile base nitrogen (TVB-N), ATP degradation (related to K value), surface color change, free amino acid (FAA) content, total sulfhydryl group (SH) content, Fourier transform infrared absorption spectra (FT-IR), fluorescence emission spectra, and microscopic observations of large yellow croaker myofibrillar proteins were investigated. The thawing times of the control sample, 200UT, 240UT, 280UT, and 320UT samples were 1750, 1190, 810, 580, and 570 s, respectively, which indicated that ultrasonic radiation could improve thawing efficiency. Additionally, ultrasonic thawing maintained better freshness and color and inhibited lipid oxidation. Compared with fresh samples, the TVB-N of large yellow croaker thawed by ultrasonication increased by 12.68%, and the K value increased by 0.9%. The 240UT sample had tightly arranged myofibrils and fewer changes in the structures of myogenic fibrillar proteins than the fresh samples, and the SH content of 240UT was decreased by 8.17%. Use of excessive ultrasonic power (320 W) damaged the protein microstructure and the microstructure of large yellow croaker. In conclusion, sample 240UT maintained the quality of large yellow croaker better with minimal damage, which is recommended for rapid thawing. PRACTICAL APPLICATION: Ultrasonic waves improve the thawing efficiency of large yellow croaker and maintain the freshness and color of the fish. According to results, sample 240UT exhibited slight changes in the structure of the myofibril protein, but excessive ultrasonic power destroyed the microstructure and protein structure. Appropriate ultrasonic treatment to the thawing of fish has good prospects.

Normal mode calculation and infrared spectroscopy of proteins in water solution: Relationship between amide I transition dipole strength and secondary structure

Dipole Strength (DS) of the amides has gained a renewed interest in chemical physics since it provides an important tool to disclose the on-site vibrational energy distributions. Apart from earlier experimental efforts on polypeptides, little is still known about DS in complex proteins. We accurately measured the Fourier Transform Infrared absorption spectra of nine proteins in water solution obtaining their Molar Extinction Coefficient in the amide I and II spectral region. Our results show that the amide I DS value depends on the protein secondary structure, being that of the α-rich and unstructured proteins lower by a factor of 2 than that of the β-rich proteins. The average DS for amino acids in α and β secondary structures confirms this finding. Normal Mode calculation and Molecular Dynamics were performed and used as tools for data analysis and interpretation. The present outcomes corroborate the hypothesis that antiparallel β-sheet environment is more prone to delocalize the on-site CO stretching vibration through coupling mechanisms between carbonyl groups, whereas α-helix structures are energetically less stable to permit vibrational mode delocalization.

Plumbing the depths of the graphene wetting controversy

Plumbing the depths of the graphene wetting controversy

Loss of chemical bonds induced by high doses of γ-radiation in a PADC polymer film: The influence of dose and dose rate on radiation chemical yields

The effects of gamma rays on molecular properties of a poly allyl diglycol carbonate (PADC) polymer, commercially named as CR-39, have been studied. PADC films were exposed to gamma rays at doses ranging from 0.5 to 3 MGy. Gamma exposure induces considerable molecular modifications in PADC films. These modifications were analyzed using Fourier transform infrared (FT-IR) spectroscopy. FT-IR absorption spectra of the gamma irradiated samples show a change in the intensity and the shape of the absorption bands of the chemical groups forming the PADC polymer relative to the pristine one. We have determined G-values for the loss of carbonate ester and ether chemical moieties within PADC. By comparing our G-values with those from other studies, we show that dose rate and dose significantly affect the radiation chemical yields and play an important role of molecular bond kinematics.

Spectroscopic investigation of long-term outdoor-exposed crystalline silicon photovoltaic modules

Degradations of an encapsulant of a random copolymer of ethylene and vinyl acetate (EVA), in long-term outdoor-exposed (OE) crystalline silicon (c-Si) photovoltaic (PV) modules were investigated by Raman and Fourier transform-infrared (FT-IR) spectroscopy measurements. Two predominant chemical and photochemical degradations, discoloration (yellow-browning) and formation of acetic acid (AcOH), were observed in EVA encapsulants in c-Si PV modules exposed outdoors for approximately 27 years in Japan (Kirishima module). The yellow-browning of the encapsulants was suggested to be due to reaction of additives, such as UV absorbers that were incorporated in the encapsulants, because no marked degradation of EVA itself was observed in the FT-IR absorption spectrum. Contrastingly, the absorption intensity of C = O of the colorless EVA in the Kirishima module decreased to 70 %, which was similar to that for the encapsulant in a damp-heat-tested (DHT) module at 85 °C with 85 % relative humidity for 4000 h (68 %), suggesting that AcOH was formed from EVA. The degradation mechanisms of the EVA encapsulants in long-term OE and DHT c-Si PV modules were explored by spectroscopy and other analyses.

Rapid intraoperative diagnosis of gynecological cancer by ATR-FTIR spectroscopy of fresh tissue biopsy.

A rapid and reliable intraoperative diagnostic technique to support clinical decisions was developed using Fourier-transform infrared (FTIR) spectroscopy. Twenty-six fresh tissue samples were collected intraoperatively from patients undergoing gynecological surgeries. Frozen section (FS) histopathology aimed to discriminate between malignant and benign tumors was performed, and attenuated total reflection (ATR) FTIR spectra were collected from these samples. Digital dehydration and principal component analysis and linear discriminant analysis (PCA-LDA) models were developed to classify samples into malignant and benign groups. Two validation schemes were employed: k-fold and "leave one out." FTIR absorption spectrum of a fresh tissue sample was obtained in less than 5 minutes. The fingerprint spectral region of malignant tumors was consistently different from that of benign tumors. The PCA-LDA discrimination model correctly classified the samples into malignant and benign groups with accuracies of 96% and 93% for the k-fold and "leave one out" validation schemes, respectively. We showed that a simple tissue preparation followed by ATR-FTIR spectroscopy provides accurate means for very rapid tumor classification into malignant and benign gynecological tumors. With further development, the proposed method has high potential to be used as an adjunct to the intraoperative FS histopathology technique.

Deposition pressure dependent structural and optoelectronic properties of ex-situ boron-doped poly-Si/SiOx passivating contacts based on sputtered silicon

Among common methods to form polycrystalline silicon (poly-Si) films for passivating-contact solar cells, physical vapor deposition, in particular sputtering, is the safest one as it does not require any toxic gaseous precursors. One of the critical parameters to control the properties of sputtered silicon films is their deposition pressure. In this work, structural and optoelectronic characteristics of ex-situ boron-doped poly-Si/SiOx passivating contacts, formed from sputtered intrinsic amorphous silicon (a-Si) deposited at different pressures on top of SiOx/c-Si substrates and subjected to a high-temperature boron diffusion step, are investigated. The deposition rate and density of the as-deposited a-Si films increase with reducing pressure. Low-temperature photoluminescence spectra captured from the as-deposited samples at different pressures do not show typical emissions from hydrogenated a-Si. Meanwhile, their Fourier-transform infrared absorption spectra all show Si–H stretching modes, indicating that hydrogen had been initially incorporated into the chemical SiOx layers and eventually hydrogenated the a-Si/SiOx interfaces during the sputtering process. After the high-temperature boron-diffusion step, all hydrogen-related peaks disappear. Lower pressure films (1.5 and 2.5 mTorr) show more consistent improved performance after hydrogen treatments, compared to higher pressure films (4 and 5 mTorr). The resultant passivating contacts at 2.5 mTorr achieve a low single-side recombination current density Jo of ~9 fA/cm2, whereas their contact resistivity is still low at 15 mΩ cm2.

Nanoceramics and novel functionalized silicate-based magnetic nanocomposites as substitutional disinfectants for water and wastewater purification.

Herein, we successfully synthesized nano-porous Co2O3/Cu2O3: Al2O3: SiO2 ((0, 5, 7, 9) Co-CAS) using the acidic sol-gel approach and calcined at 800°C for 4h. The crystallization behavior and spectroscopic properties were investigated using X-ray diffraction, field emission-scanning electron microscopy, and Fourier-transform infrared absorption spectra analysis. The antibiotic properties of the nano-porous CAS, 5Co-CAS, and 9Co-CAS magnetic nanocomposites was studied against some potentially pathogenic bacteria in water and wastewater samples. The bacteria tested included Escherichia coli, Salmonella enterica, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, and Bacillus subtilis. Incorporating Co2O3 resulted in the identification of three peaks at 2θ = 10.2°, 13.4°, and 15°. The introduction of cobalt nanoparticles created a ferromagnetic behavior in the CAS nanoceramic, with the magnetic moment and saturation values increasing with increased Co2O3 doping. 9Co-CAS was most potent against all the tested pathogens with minimum inhibitory concentrations of 25mg/L within 40min for E. coli and P. aeruginosa and 50mg/L within 10min for S. enterica; the lowest antibacterial activity was observed with the unmodified CAS. The findings revealed that the manufactured nanocomposite materials were potent disinfectants with a promising application for water and wastewater treatment.

Identification of Salmonella Serovars before and after Ultraviolet Light Irradiation by Fourier Transform Infrared (FT-IR) Spectroscopy and Chemometrics

Vibrational properties and structural behavior upon ultraviolet (UV) irradiation are reported here for DNAs isolated from three serovars of Salmonella bacteria, respectively (S. enteritidis, S. infantis and S. typhimurium) by using Fourier transform infrared spectroscopy (FT-IR). The FT-IR absorbance spectra were recorded for bacterial DNAs, control and UV irradiated samples (30 min, 1 h, 1 h 30 min), respectively, and are presented in the wavenumber ranges from 800 to 1800 cm−1 and from 3000 to 4000 cm−1, respectively. Molecular specific structural information has been found based on DNA marker bands, which were monitored primarily in terms of intensity changes. As a general remark, a serovar’s dependent nonlinear behavior has been detected for some FT-IR band intensities corresponding to Salmonella DNAs, as a function of irradiation time. Particularly, alterations in DNA functional groups and molecular geometry have been observed. Chemometric analysis such as principal component analysis (PCA) and hierarchical clustering analysis (HCA) were successfully applied for the identification of inter- and intra- serovar differences between DNA spectra, before and after UV irradiation. The elucidation of the main spectral features characteristic to pathogenic bacterial DNAs offers further opportunity for bacteria identification and for establishing the mechanisms of infections, leading to the development of innovative diagnosis tools and more effective therapies. Particularly, DNA-damaging agents are most effective in cancer therapy.

Biosorption of lanthanum and samarium by viable and autoclaved mycelium of Botryosphaeria rhodina MAMB-05.

The ascomycetous fungus, Botryosphaeria rhodina MAMB-05, secretes a (1→3)(1→6)-β-D-glucan, and the scaled-up production of this β-glucan results in large amounts of mycelial biomass being produced that represent a potentially cost-effective biosorbent for rare-earth elements. High sorption capacities for both La(III) and Sm(III) were demonstrated for viable and autoclaved lyophilized fungal mycelium. Fourier-transformed infra-red absorption spectra and the point of zero charge (PZC) were similar for the viable and inactive fungal mycelia. The rare-earth lanthanide elements (La and Sm) binding increased at initial pH values greater than 5.0, which was also observed for the PZC determination. The maximum La(III) uptake capacity was observed at lower amounts of La(III) ions in solution, decreasing from 100.0 to 25.3% when the initial lanthanide concentration increased from 15 to 100 mg/L. Lanthanide biosorption by B. rhodina MAMB-05 mycelia followed the Langmuir model, and the affinity of biosorbent functional groups was similar for La(III) and Sm(III).

Efficient Degradation of High-Molecular-Weight Hyaluronic Acid by a Combination of Ultrasound, Hydrogen Peroxide, and Copper Ion

Hyaluronic acid (HA) was depolymerized by a combination of ultrasound, hydrogen peroxide and copper ion. The structures of high-molecular-weight hyaluronic acid (HMW-HA) and low-molecular-weight hyaluronic acid (LMW-HA) were determined by Fourier transform infrared (FTIR) spectroscopy, circular dichroism (CD) spectroscopy, and UV-VIS absorption spectroscopy. The degradations of HMW-HA using a physical method, a chemical method, and a combination of physical and chemical method were compared. The results show that HA can be effectively degraded by a combinatorial method involving ultrasound, hydrogen peroxide, and copper ion. Under the degradation conditions of 50 mM H2O2, 5.0 μM CuCl2, 160 W, pH 4.0, and reaction at 50 °C for 30 min, the content of glucuronic acid was 36.56%, and the yield of LMW-HA was 81.71%. The FTIR, CD, and UV-VIS absorption spectra of HA did not change with the decrease in molecular weight, indicating that the structure of HA remained intact during the degradation.