PBAT/lignin-ZnO composite film for food packaging: Photo-stability, better barrier and antibacterial properties.

When PBAT used as film, stability deteriorates under sunlight exposure, the poor barrier and antibacterial properties are also limiting its application. In this work, lignin-ZnO nanoparticles were prepared by hydrothermal method, as additives to fill the PBAT matrix. In addition, PBAT-lignin-ZnO composite films were successfully prepared by melting and hot-pressing method. It is found that lignin could well dispersed the ZnO when its implantation into PBAT films, and lignin-ZnO not only maintaining tensile strength and thermal stability, but also could prompt PBAT's crystallinity. Especially, P-L-ZnO-2 composite films have good photostability. After 60 h aging, it can still maintain good molecular weight, chemical structure and mechanical properties. Besides, these composite films have improved hydrophobicity, barrier and antibacterial properties, could prevent mildew and significantly reduce the weight loss rate, color difference and hardness changes of strawberries during storage. This work provides a potential film material for outdoor applications and food packaging.

Synthesis and its biological activity of carboxymethyl hemicellulose p-hydroxybenzoate (P-CMHC).

Hemicellulose extracted from ecalyptus APMP pulping waste liquor and undergoes etherification modification to produce carboxymethyl hemicellulose (CMHC). Subsequently, CMHC undergoes esterification reaction with p-hydroxybenzoic acid to synthesize a novel polysaccharide-based preservative known as carboxymethyl hemicellulose p-hydroxybenzoate (P-CMHC). The synthesis conditions of P-CMHC were optimized using the response surface methodology, resulting in an optimal esterification condition that achieved a degree of substitution of 0.232. P-CMHC exhibits excellent antioxidant activity, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging activities. Additionally, it demonstrates favorable hygroscopic and moisturizing properties. Thiazole blue (MTT) experiments evaluating cell proliferation rate indicate that P-CMHC possesses negligible cytotoxicity, making it a promising, safe, and healthy preservative. Consequently, it can be considered as a new material for applications in the fields of biomedicine, food, and cosmetics.

Application strategy and effect analysis of nutritional support nursing for critically ill patients in intensive care units.

We investigate nutritional support and nursing status of critical patients in intensive care units (ICUs) to understand the latest nutritional support guidelines' implementation by clinical medical staff; identify problems in nutritional support and nursing for these patients, analyze causes, and present suggestions; and provide a clinical/theoretical bases to improve nutritional support implementation and nursing strategies for them. Clinical case information of 304 critically ill ICU patients admitted from July 2017 to July 2021 was analyzed. They were divided into the experimental (nutritional support) and control (no nutritional support) groups to compare their laboratory indicators, 28-day case fatality rate, and infection incidence. Least significant difference was used for postanalysis of statistically significant items to obtain pairwise comparisons. Nutrition support strategies for ICU patients are consistent with guidelines but have an implementation gap. No statistically significant differences were found in hemoglobin (HB), total serum protein (TP), serum albumin (ALB), transferrin (TF), prealbumin (PA), and total lymphocyte count (TLC) in experimental group patients compared with the control group within 24 hours (before nutritional support, P > .05). No statistically significant differences were also found in HB, TP, TLC, and ALB between the enteral nutrition + parenteral nutrition (EN + PN), total EN (TEN), total PN (TPN), and control groups on admission day 7 (after nutritional support, P > .05), while statistically significant differences existed between PA and TF (P < .05). TF of patients supported by TEN was higher (statistically significant difference, P < .05). PA in patients receiving TEN and EN + PN support was higher than in control group patients (statistically significant difference, P < .05). Compared with the control group, in experimental group patients, infection incidence was significantly lower (40.2% vs 62.9%, P < .05); incidence of complications was lower, but not statistically significant (40.2% vs 57.1%, P > .05); and 28-day mortalities were significantly lower (26.7% vs 45.7%, P < .05). Nutritional support can reduce hospitalization complications and 28-day mortality in critical patients, but its implementation must be standardized. Especially for patients with gastrointestinal dysfunction, personalized/standardized nutrition strategies and nursing procedures are needed when PN support is applied, and training of clinical medical staff should be strengthened to improve nutrition support's efficiency.

Carboxymethylation modification, characterization, antioxidant activity and anti-UVC ability of Sargassum fusiforme polysaccharide.

Taking the degree of substitution (DS) as the index, the carboxymethylation conditions of Sargassum fusiforme polysaccharide (SFP) were studied. According to the single factor experiment results, the optimum experimental conditions were obtained: sodium hydroxide concentration, 15% (20 mL); alkalization temperature, 50 °C; dosage of chloroacetic acid 1.5 g; etherification time, 2 h, and the Carboxymethyl Sargassum fusiforme polysaccharide (CSFP) with the highest DS (0.635) was obtained. And then, the physicochemical properties, structural information and bioactivity of SFP and CSFP were characterized. The SFP and CSFP were composed of four monosaccharides, with a small amount of protein, and their molecular weights to 780.2 kDa and 386.3 kDa respectively. The results of FTIR and NMR showed that the carboxymethyl was successfully grafted onto the C-4 and C-6 of sugar chain. The results of anti UVC experiment showed that SFP and CSFP had a certain negative effect on cell activity, and the degree of damage caused by UVC radiation was weakened, and the anti UVC performance of CSFP was better than that of SFP.

The Trans-Superior Articular Process Approach Utilizing Visual Trephine: A More Time-Saving and Effective Percutaneous Endoscopic Transforaminal Lumbar Discectomy for Migrated Lumbar Disc Herniation.

AIM: To introduce, and to evaluate the efficacy of the trans-superior articular process (trans-SAP) approach utilizing visual trephine in percutaneous endoscopic transforaminal lumbar discectomy (PETLD) for migrated lumbar disc herniation. MATERIAL AND METHODS: This study included 98 patients, 50 patients were in trans-SAP PETLD group and 48 patients were in conventional PETLD group. Visual analogue scale (VAS), Oswestry disability index (ODI), gender, age, blood loss, operation time, the frequency of X-ray fluoroscopy and the percentage of highly migrated herniation were evaluated and compared between the trans-SAP PETLD and conventional PETLD group. RESULTS: In both trans-SAP PETLD and conventional PETLD group, VAS and ODI were decreased at postoperative 1 day and 3 months compared with preoperative (p < 0.001). What's more, the VAS and ODI of postoperative 3 months were lower than postoperative 1 day (p < 0.001). There was no difference in gender, age, blood loss after the operation, and VAS during operation between trans-SAP group and conventional group (p > 0.05). The blood loss during the operation of trans-SAP group was higher (p < 0.05), but the operation time and frequency of X-ray fluoroscopy were lower than conventional group (p < 0.001). Last, trans-SAP group had a higher percentage of highly migrated herniation (p < 0.001). CONCLUSION: Both the conventional way and trans-SAP approach can achieve excellent surgical results. But, in trans-SAP group, the operation time is shorter, and X-ray fluoroscopy is less. PETLD with visual trephine has more advantages in highly migrated herniation and maybe easier to be mastered by young surgeons.

Carboxymethylation of polysaccharide isolated from Alkaline Peroxide Mechanical Pulping (APMP) waste liquor and its bioactivity.

In recent years, the biological activity of polysaccharides and their derivatives has been widely studied. However, in addition to the natural polysaccharides directly extracted from plants and animals, there are rich polysaccharides in the pulping waste liquor that have not been fully utilized. The extracted polysaccharide from eucalyptus Alkaline Peroxide Mechanical Pulping (APMP) waste liquor was used as a raw material. For the production of carboxymethyl polysaccharide, the effects of temperature (T), the amount of alkali (NaOH) and the amount of etherifying agent (ClCH2COOH) on the degree of substitution (DS) were investigated, the optimal preparation conditions are: reaction time 2 h, temperature 75 °C, and the molar ratio of polysaccharide, NaOH and ClCH2COOH is 1:1:2, the highest DS is 1.47; FT-IR, NMR and GPC were used to characterize the structure and Molecular weight, the results show that the polysaccharide of APMP waste liquor is rich in xylan, and it was proved that the carboxymethyl substitution was successful and the positions of the substituent group were determined. The characterization and biological activity research of xylan polysaccharide (XP) and carboxymethyl xylan polysaccharide (CMXP), such as antioxidation, moisture absorption/retention, bacteriostatic action and cytotoxicity were discussed. CMXP shows better effects compared with XP.

Synthesis and characterization of temperature/pH dual sensitive hemicellulose-based hydrogels from eucalyptus APMP waste liquor.

In this investigation, a variety of innovative temperature/pH-sensitive hydrogels consisting of hemicellulose (extracted from APMP waste liquor) and acrylic acid/acrylamide monomers were synthesized via free radical polymerization for water retention agents and controlled release. The results showed that the hydrogel polymer was chemically cross-linked and entangled to form a three-dimensional network structure, and the monomer successfully grafted on the hemicellulose chain. The content of crosslinkers and monomers had obvious effects on the swelling ratio of hydrogel. The sensitivity of the hydrogel was determined according to the change of the swelling ratio of the hydrogel under different temperature and pH conditions, combined with the chemical structure analysis of the hydrogel, and explain its sensitivity mechanism. Finally, after 6 days at 25 °C and pH 6, the swelled hydrogel still retained 79.46 % of the moisture, which proved that it has high water retention ability.

Biomedical Applications of Hemicellulose-Based Hydrogels.

BACKGROUND: Hydrogel has a three-dimensional network structure that is able to absorb a large amount of water/liquid and maintain its original structure. Hemicellulose (HC) is the second most abundant polysaccharide after cellulose in plants and a heterogeneous polysaccharide consisting of various saccharide units. The unique physical and chemical properties of hemicellulose make it a promising material for hydrogels. METHODS: This review first summarizes the three research hotspots on the hemicellulose-based hydrogels: intelligence, biodegradability and biocompatibility. It also overviews the progress in the fabrication and applications of hemicellulose hydrogels in the drug delivery system and tissue engineering (articular cartilage, cell immobilization, and wound dressing). RESULTS: Hemicellulose-based hydrogels have many unique properties, such as stimuliresponsibility, biodegradability and biocompatibility. Interpenetrating networking can endow appropriate mechanical properties to hydrogels. These properties make the hemicellulose-based hydrogels promising materials in biomedical applications such as drug delivery systems and tissue engineering (articular cartilage, cell immobilization, and wound dressing). CONCLUSION: Hydrogels have been widely used in biomedicine and tissue engineering areas, such as tissue fillers, drug release agents, enzyme encapsulation, protein electrophoresis, contact lenses, artificial plasma, artificial skin, and tissue engineering scaffold materials. This article reviews the recent progress in the fabrication and applications of hemicellulose-based hydrogels in the biomedical field.

Characterization of liquefied products from corn stalk and its biomass components by polyhydric alcohols with phosphoric acid.

The hemicellulose, cellulose and lignin were directly separated from corn stalk, and their liquefaction processes were investigated via acid-catalyzed solvolysis treatment with 1,2-propylene glycol (PG) and diethylene glycol (DEG) to produce bio-oil and residues. The main components, functional groups and organics structure of bio-oil were analyzed by the FTIR, 1H-NMR, 13C-NMR, GCMS, and TGA. It was found that there had a similar tendency in the liquefaction processes of cellulose, hemicellulose and lignin. Corn stalk and its biomass components were degraded and formed plentiful low-molecular polymers by acid catalysis, prior to polymers were converted into corresponding PG/DEG-derivatives. Finally, low-molecular weight soluble substances and insoluble residues were generated by decomposition and polymerization. Additionally, more than 80% compounds' carbon number in four bio-oils was below 25. The residues were mostly stemmed from macromolecules produced by degradation products and PG/DEG or re-polymerization between degraded small molecules.

The study of inhibitory effects and mechanism of carboxylate chitooligomer on melanin, prepared by laccase/TEMPO system.

A carboxylate chitooligomer (C-COS) containing carboxyl groups attached to chitooligomer (COS) molecules has been prepared by laccase/2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) system, which is a green-chemistry method. Several experiments were designed to evaluate inhibition effects on melanin and mechanisms of C-COS. The results indicated that C-COS exhibited more distinct anti-melanogenic effects compared to COS. C-COS inhibits melanin production with tyrosine (Tyr) and DOPA as the substrate of melanin formation, and the inhibition rates are, respectively, 89.07% and 84.45%, which reach 1.4-2 times those of COS. UV-vis spectroscopy was used to elucidate the interaction mechanism between C-COS and tyrosinase (TYR). It is C-COS chelating with metal Cu ions in tyrosinase (TYR) that decreases the enzyme activity. Half-maximal inhibitory concentrations (IC50) of C-COS were calculated as 13.49 and 4.07 mg/mL for monophenolase (cresolase) and diphenolase (catecholase), respectively.

The hydration mechanism and hydrogen bonding structure of 6-carboxylate chitooligosaccharides superabsorbent material prepared by laccase/TEMPO oxidation system.

6-carboxylate chitooligosaccharides (6-CCOS), as a superabsorbent material, were prepared by way of the laccase/TEMPO oxidation system. It exhibited a higher moisture-absorption ability and stronger affinity for water. To understand the real reasons for this, the hydrogen bonding structure of 6-CCOS and the hydration mechanism of the molecule were investigated using infrared (IR), differential scanning calorimetry (DSC), and nuclear magnetic resonance (NMR). It was found that the introduction of a strongly hydrophilic carboxylate ion on the C6 site of chitooligosaccharides molecule was conducive to the enhancement of the interaction between polysaccharide polymers and water molecules. The most important was the formation of hydrogen bonds connected between carboxylate ion and residual water. In addition, the hydration mechanism of 6-CCOS molecules was presumed to be that more water molecules from outside were incorporated into the already embedded water molecules within the polymer. The whole molecule was woven into a huge water-polymer network structure through intermolecular hydrated hydrogen bonds.

Catalytic Liquefaction of Corn Stalk under Atomosphere Prssure and the Analysis of Liquefaction Products.

With concentrated phosphoric acid as catalyst and various organic solvents as liquefying agents, corn stalk powder was liquefied into bio-oil in an autoclave, under the condition of 170 ℃. Analysis was conducted to throw light on the liquefying effects of three different agents; they are glycerol triacetate with ethylene carbonate, glycerol with ethylene carbonate and polyethylene glycol with ethylene carbonate(6∶1 ω/ω), and the properties of the biomass liquefaction oil products. FT-IR was applied to examine raw material and residues, whose chemical compositions were further analyzed with the use of GC-MS. The results of experiments indicated that the liquefaction yield of polyethylene glycol was 97.84%, the yield of glycerol triacetate was 80.20%, the yield of glycerol were36.97%. FT-IR analysis showed that the functional groups of cellulose, hemicelluloses and lignin was disappeared and liquefaction is best when polyethylene glycol with ethylene carbonate was used as the liquefaction agent. GC-MS analysis showed that the oil composition produced in this way is complex, contains organic acids and ketones, alcohols and ethers, aromatic, sugars and esters compounds.

Production of furfural from waste aqueous hemicellulose solution of hardwood over ZSM-5 zeolite.

This study aimed to produce furfural from waste aqueous hemicellulose solution of a hardwood kraft-based dissolving pulp production processing in a green method. The maximum furfural yield of 82.4% and the xylose conversion of 96.8% were achieved at 463K, 1.0g ZSM-5, 1.05g NaCl and organic solvent-to-aqueous phase ratio of 30:15 (V/V) for 3h. The furfural yield was just 51.5% when the same concentration of pure xylose solution was used. Under the optimized condition, furfural yield was still up to 67.1% even after the fifth reused of catalyst. Catalyst recycling study showed that ZSM-5 has a certain stability and can be efficiently reused.

Furfural formation from the pre-hydrolysis liquor of a hardwood kraft-based dissolving pulp production process.

This study aimed to produce furfural from the PHL. Results showed best furfural yield of 32.8% and the furfural selectivity of 37.7% in the monophase system (170 °C, 100 min), while they were 60.1% and 69.8%, respectively in the biphase system. The lower furfural selectivity in the monophase system was explained by more side reactions, such as fragmentation, condensation reactions, resinification and others. Model compounds such as: xylose, furfural, syringaldehyde, were used to confirm/identify these side reactions. The addition of dilute sulfuric acid/acetic acid in the system under the same conditions decreased the recovery of furfural. The addition of syringaldehyde into the PHL also led to a decrease in the furfural yield, supporting the conclusion that lignin structures in the PHL may also be involved in the side reactions, thus decreasing the furfural yield.

[Spectra analysis of lignin small molecular guaiacyl coniferyl alcohol biological modification treated by laccase].

The enzymatic modification mechanism of lignin small molecular lignin guaiacyl coniferyl alcohol existing in softwood and hardwood treated by laccase was studied. Gas chromatography-mass spectrometry (GC-MS), gel permeation chromatography (GPC), FTIR spectrum and PCD(particle charge detector) etc were used for the measurement. GC-MS could not detect the coniferyl alcohol monomer after treated by laccase, so it was speculated that coniferyl alcohol participated in the reaction totally, and the structure of coniferyl alcohol was changed. GPC demonstrated that the molecular weight of coniferyl alcohol increased when it was treated by laccase, and coniferyl alcohol was polymerized. FTIR spectrum determined the reaction point of coniferyl alcohol when treated by laccase, and it is mainly phenolic hydroxyl, aromatic ring side chain substituent such as methoxy, double bound in side chain, beta-carbonyl groups, and gamma-carbonyl groups. PCD gave a result that the cationic demandv(CD) decreased by 88.38%.