Progress in Analytical Methods of Halogenated Disinfection By-Products

Ensuring the health and safety of drinking water is crucial for both nations and their citizens.Since the 20th century,the disinfection of drinking water,effectively controlling pathogens in water sources,has become one of the significant advances in public health.However,the disinfectants used in the process,such as chlorine and chlorine dioxide,react with natural organic matter in the water to produce disinfection by-products(DBPs).Most of these DBPs contain chlorine,and if the source water contains bromine or iodine,brominated or iodinated DBPs,collectively referred to as Halogenated disinfection byproducts(X-DBPs),are formed.Numerous studies have found that X-DBPs pose potential risks to human health and the environment,leading to widespread concern.Mass spectrometry has become an important means of discovering new types of X-DBPs.This paper focuses on the study of methods for analyzing X-DBPs in drinking water using mass spectrometry.

Construction of all-organic low dielectric polyimide hybrids via synergistic effect between covalent organic framework and cross-linking structure

Polyimide(PI)is a promising electronic packaging material,but it remains challenging to obtain an all-organic PI hybrid film with decreased dielectric constant and loss without modifying the monomer.Herein,a series of allorganic PI hybrid films were successfully prepared by introducing the covalent organic framework(COF),which could induce the formation of the cross-linking structure in the PI matrix.Due to the synergistic effects of the COF fillers and the cross-linking structure,the PI/COF hybrid film containing 2 wt%COF exhibited the lowest dielectric constant of 2.72 and the lowest dielectric loss(tanδ)of 0.0077 at 1 MHz.It is attributed to the intrinsic low dielectric constant of COF and a large number of mesopores within the PI.Besides,the cross-linking network of PI prevents the molecular chains from stacking and improves the fraction of free volume(FFV).The molecular dynamics simulation results are well consistent with the dielectric properties data.Furthermore,the PI/COF hybrid film with 5 wt%COF showed a significant enhancement in breakdown strength,which increased to 412.8 kV/mm as compared with pure PI.In addition,the PI/COF hybrid film achieve to reduce the dielectric constant and thermal expansion coefficient(CTE).It also exhibited excellent thermal,hydrophobicity,and mechanical performance.The all-organic PI/COF hybrid films have great commercial potential as next-generation electronic packaging materials.

Cross-Linking of Sago Starch with Furan and Bismaleimide via the Diels-Alder Reaction

This research paper describes the synthesis of thermo-reversible cross-linking of sago starch by grafting a furan pendant group(methyl 2-furoate)onto the starch backbone,followed by a Diels-Alder(DA)reaction of the furan functional group with 1,1′-(methylenedi-4,1-phenylene)bismaleimide(BM).The proof of principles was provided by FTIR and 1H-NMR analyses.The relevant FTIR peaks are the carbonyl peak(υC=O sym)at 1721 cm^(−1);the two peaks appeared after DA cross-linking,i.e.,at 1510 cm^(−1)(corresponding toυCH=CH BM aromatic rings,stretching vibrations),and at 1173 cm^(−1)(assigned to cycloadduct(C-O-C,δDA ring))while the^(1)H-NMR result shows evidence for the presence of a furan ring in the starch matrices(in the range ofδ6.3-7.5 ppm).The crosslinked starch product is indeed thermally reversible,as is evident from the appearance of exothermal(DA,temperature range of 50℃-70℃)and endothermal(retro DA,temperature range of 125℃-150℃)transitions in the DSC thermograms.This paper not only proves the thermal reversibility but also demonstrates that the final product properties(chemical,morphology,and thermal stability)can be tuned by varying the annealing temperature,BM intake,and reaction time.

Mechanism of high Li-ion conductivity in poly(vinylene carbonate)-poly(ethylene oxide)cross-linked network based electrolyte revealed by solid-state NMR

Solid polymer electrolytes(SPEs)have become increasingly important in advanced lithium-ion batteries(LIBs)due to their improved safety and mechanical properties compared to organic liquid electrolytes.Cross-linked polymers have the potential to further improve the mechanical property without trading off Li-ion conductivity.In this study,focusing on a recently developed cross-linked SPE,i.e.,the one based on poly(vinylene carbonate)-poly(ethylene oxide)cross-linked network(PVCN),we used solid-state nuclear magnetic resonance(NMR)techniques to investigate the fundamental interaction between the chain segments and Li ions,as well as the lithium-ion motion.By utilizing homonuclear/heteronuclear correlation,CP(cross-polarization)kinetics,and spin-lattice relaxation experiments,etc.,we revealed the structural characteristics and their relations to lithium-ion mobilities.It is found that the network formation prevents poly(ethylene oxide)chains from crystallization,which could create sufficient space for segmental tumbling and Li-ion co nductio n.As such,the mechanical property is greatly improved with even higher Li-ion mobilities compared to the poly(vinylene carbonate)or poly(ethylene oxide)based SPE analogues.

Residual alkali-evoked cross-linked polymer layer for anti-air-sensitivity LiNi_(0.89)Co_(0.06)Mn_(0.05)O_(2)cathode

High-energy density lithium-ion batteries(LIBs)with layered high-nickel oxide cathodes(LiNi_(x)Co_(y)Mn_(1-x-y)O_(2),x≥0.8)show great promise in consumer electronics and vehicular applications.However,LiNi_(x)Co_(y)Mn_(1-x-y)O_(2)faces challenges related to capacity decay caused by residual alkalis owing to high sensitivity to air.To address this issue,we propose a hazardous substances upcycling method that fundamentally mitigates alkali content and concurrently induces the emergence of an anti-air-sensitive layer on the cathode surface.Through the neutralization of polyacrylic acid(PAA)with residual alkalis and then coupling it with 3-aminopropyl triethoxysilane(KH550),a stable and ion-conductive cross-linked polymer layer is in situ integrated into the LiNi_(0.89)Co_(0.06)Mn_(0.05)O_(2)(NCM)cathode.Our characterization and measurements demonstrate its effectiveness.The NCM material exhibits impressive cycling performance,retaining 88.4%of its capacity after 200 cycles at 5 C and achieving an extraordinary specific capacity of 170.0 mA h g^(-1) at 10 C.Importantly,this layer on the NCM efficiently suppresses unfavorable phase transitions,severe electrolyte degradation,and CO_(2)gas evolution,while maintaining commendable resistance to air exposure.This surface modification strategy shows widespread potential for creating air-stable LiNi_(x)Co_(y)Mn_(1-x-y)O_(2)cathodes,thereby advancing high-performance LIBs.

Effects of molasses on the fermentation characteristics of mixed silage prepared with rice straw, local vegetable by-products and alfalfa in Southeast China

This experiment was conducted to study the effect of molasses on the fermentation characteristics of mixed silage ensiled rice straw and vegetable by-products with alfalfa.Mixture（202 g kg^-1 dry matter（DM））consisting of rice straw,broccoli residue and alfalfa at the ratio of 5：4：1 was ensiled with three experimental treatments：（1）no additives（control）;（2）molasses at 2.5%（M1）;（3）molasses at 5%（M2）on a fresh matter basis of mixture,respectively.All treatments were packed into laboratory-scale silos,and three silos per treatment were sampled on days 1,3,5,14 and 30.The result showed that the p H value of all mixed silages decreased gradually with the time of ensiling except for the control silage,in which a significant increase（P〈0.05）on day 30 occurred.The lactic acid content increased gradually with the time of ensiling and reached the highest value on day 14,and a marked decrease（P〈0.05）was found in the control silage on day 30.The changes of acetic acid content showed similar pattern with lactic acid content.A trace amount of propionic and butyric acid contents were found in the three mixed silages during the fermentation period.Comparing to the control,M1 and M2 treatments improved the fermentation quality of mixed silages as indicated by higher（P〈0.05）lactic acid contents and lower（P〈0.05）p H and ammonia-N contents.The Flieg points also showed that M1 and M2 silages were well preserved,whereas the control silage had a bad quality.Overall,the findings of this study suggested that adding molasses could improve fermentation quality of mixed silage,and M1 was more suitable for practical application.

Simultaneous Control of Microorganisms and Disinfection By-products by Sequential Chlorination

Objective To introduce a new sequential chlorination disinfection process in which short-term free chlorine and chloramine are sequentially added. Methods Pilot tests of this sequential chlorination were carried out in a drinking water plant. Results The sequential chlorination disinfection process had the same or better efficiency on microbe （including virus） inactivation compared with the free chlorine disinfection process. There seemed to be some synergetic disinfection effect between free chlorine and monochloramine because they attacked different targets. The sequential chlorination disinfection process resulted in 35.7%-77.0% TTHM formation and 36.6%-54.8% THAA5 formation less than the free chlorination process. The poorer the water quality was, the more advantage the sequential chlorination disinfection had over the free chlorination. Conclusion This process takes advantages of free chlorine＇s quick inactivation of microorganisms and chloramine＇s low disinfection by-product （DBP） yield and long-term residual effect, allowing simultaneous control of microbes and DBPs in an effective and economic way.

PERVAPORATION PROPERTIES OF PDMS MEMBRANES CURED WITH DIFFERENT CROSS-LINKING REAGENTS FOR ETHANOL CONCENTRATION FROM AQUEOUS SOLUTIONS

Ethanol perm-selective PDMS/PVDF composite membranes were prepared by curing polydimethylsiloxane (PDMS) with various cross-linking reagents,such as tetraethoxylsilane(TEOS),γ-aminopropyltriethoxylsilane(APTEOS), phenyltrimethoxylsilane(PTMOS) and octyltrimethoxylsilane(OTMOS) as well.The cross-linking density and surface properties of the PDMS active layer were adjusted by varying cross-linking reagents.The pervaporation performance of PDMS membranes cured with different cross-linking reagents was investig...

Experimental study on the treatment of rabbit corneal melting after alkali burn with Collagen cross-linking

AIM: To evaluate the effect of Collagen cross-linking on the prevention of melting in rabbit corneas after alkali burn. METHODS: Twenty New Zealand white rabbits were randomly divided into model control group and collagen cross-linking treatment group. The second group of rabbits received collagen cross linked treatment. Both groups were applied with antibiotic eye drops to prevent infection. The corneas were evaluated for melting, opacity, pathological and immunohistochemistry, record the changes when 28 days after the animals were killed. RESULTS: In the control group, 6 out of 8 rabbits showed corneal melting after injury (14 +/- 4) days, while two corneal perforated. In collagen cross-linking treatment group, one rabbit showed corneal melting after injury 23 days, without corneal perforation; corneal dissolution rate between the two groups was significantly different (P <0.05). Pathological examination suggested that in the treatment group, mild corneal edema, mild damage to collagen fibers, inflammatory cell infiltration was significantly less than the control group. Immunohistochemistry showed that corneal collagen fibers arranged in neat rows in the control group. CONCLUSION: Collagen cross-linking treatment not only can prevent and delay the corneal melting after alkali burn, but also can reduce the destruction of corneal collagen fibers and infiltration of inflammatory cells in the corneal tissue.

A short-term study of corneal collagen cross-linking with hypo-osmolar riboflavin solution in keratoconic corneas

AIM: To report the 3mo outcomes of collagen crosslinking(CXL) with a hypo-osmolar riboflavin in thin corneas with the thinnest thickness less than 400 μm without epithelium.METHODS: Eight eyes in 6 patients with age 26.2±4.8y were included in the study. All patients underwent CXL using a hypo-osmolar riboflavin solution after its de-epithelization. Best corrected visual acuity, manifest refraction, the thinnest corneal thickness, and endothelial cell density were evaluated before and 3mo after the procedure.RESULTS: The mean thinnest thickness of the cornea was 408.5 ±29.0 μm before treatment and reduced to369.8 ±24.8 μm after the removal of epithelium. With the application of the hypo-osmolar riboflavin solution, the thickness increased to 445.0 ±26.5 μm before CXL and recover to 412.5 ±22.7 μm at 3mo after treatment, P =0.659). Before surgery, the mean K-value of the apex of the keratoconus corneas was 57.6 ±4.0 diopters, and slightly decreased(54.7±4.9 diopters) after surgery(P =0.085). Mean best-corrected visual acuity was 0.55 ±0.23 logarithm of the minimal angle of resolution, and increased to 0.53±0.26 logarithm after surgery(P =0.879).The endothelial cell density was 2706.4 ±201.6 cells/mm2 before treatment, and slightly decreased( 2641. 2 ±218.2 cells/mm2) at last fellow up(P =0.002).CONCLUSION: Corneal collagen cross-linking with a hypo-osmolar riboflavin in thin corneas seems to be a promising treatment. Further study should be done to evaluate the safety and efficiency of CXL in thin corneas for the long-term.

Systematic review and Meta-analysis comparing modified cross-linking and standard cross-linking for progressive keratoconus

AIM：To compare the effectiveness and safety between modified cross-linking（MC）and standard cross-linking（SC）in mild or moderate progressive keratoconus.METHODS：Eligible studies were retrieved from four electronic databases,including CENTRAL,Clinical Trials gov,Pup Med and OVID MEDLINE.We set post-surgical maximum K value（Kmax）as the primary outcome.In addition,uncorrected and corrected distant visual acuity（UDVA and UDVA）,spherical equivalent（SE）,endothelial cell density（ECD）,central cornea thickness（CCT）and depth of demarcation line（DDL）were Meta-analyzed as secondary outcomes.Mean differences for these outcomes were pooled through either a random-effect model or fixed-effect model according to data heterogeneity.RESULTS：Twenty-four comparative studies either on accelerated cross-linking（AC）compared with SC or on transepithelial cross-linking（TC）compared with SC were included and pooled for analysis.The results indicated that MC was significantly inferior to SC at delaying Kmax deterioration[AC vs SC 0.49（95%CI：0.04-0.94,I2=75%,P=0.03）;TC vs SC 1.15（95%CI：0.54-1.75,I2=50%,P=0.0002）].SE decreased significantly for SC when compared to AC[0.62（95%CI：0.38-0.86,I2=22%,P〈0.00001）].DDL of SC was more significantly deeper than that of TC[-133.49（95%CI：-145.94 to-121.04,I2=33%,P〈0.00001）].Other outcomes demonstrated comparable results between MC and SC.CONCLUSION：SC is more favorable at halting the progression of keratoconus,but visual acuity improvement showed comparable results between MCs and SC.

Corneal collagen cross-linking and liposomal amphotericin B combination therapy for fungal keratitis in rabbits

AIM： To observe the therapeutic effect of corneal collagen cross-linking（CXL） in combination with liposomal amphotericin B in fungal corneal ulcers.METHODS： New Zealand rabbits were induced fungal corneal ulcers by scratching and randomly divided into 3groups, i.e. control, treated with CXL, and combined therapy of CXL with 0.25% liposomal amphotericin B（n =5 each）. The corneal lesions were documented with slit-lamp and confocal microscopy on 3, 7, 14, 21 and 28 d after treatment. The corneas were examined with transmission electron microscopy（TEM） at 4wk.RESULTS： A rabbit corneal ulcer model of Fusarium was successfully established. The corneal epithelium defect areas in the two treatment groups were smaller than that in the control group on 3, 7, 14 and 21d（P 〈0.05）. The corneal epithelium defect areas of the combined group was smaller than that of the CXL group（P 〈0.05） on 7 and 14 d, but there were no statistical differences on 3, 21 and 28 d. The corneal epithelium defects of the two treatment groups have been healed by day 21. The corneal epithelium defects of the control group were healed on 28 d. The diameters of the corneal collagen fiber bundles（42.960 ±7.383 nm in the CXL group and 37.040±4.160 nm in the combined group） were thicker than that of the control group（24.900±1.868 nm）,but there was no difference between the two treatment groups. Some corneal collagen fiber bundles were distorted and with irregular arrangement, a large number of fibroblasts could be seen among them but no inflammatory cells in both treatment groups. CONCLUSION： CXL combined with liposomal amphotericin B have beneficial effects on fungal corneal ulcers. The combined therapy could alleviate corneal inflammattions, accelerate corneal repair, and shorten the course of disease.

Radiation-induced cross-linking:a novel avenue to permanent 3D modification of polymeric membranes

Membrane fouling is always the biggest problem in the practice of membrane separation technologies,which strongly impacts their applicability,separation efficiency,cost effectiveness,and service lifespan.Herein,a simple but effective 3D modification approach was designed for permanently functionalizing polymeric membranes by directly cross-linking polyvinyl alcohol(PVA)under gamma-ray irradiation at room temperature without any additives.After the modification,a PVA layer was constructed on the membrane surface and the pore inner surface of polyvinylidene fluoride(PVDF)membranes.This endowed them with good hydrophilicity,low adsorption of protein model foulants,and easy recoverability properties.In addition,the pore size and distribution were customized by controlling the PVA concentration,which enhanced the rejection ability of the resultant membranes and converted them from microfiltration to ultrafiltration.The crosslinked PVA layer was equipped with the resultant membranes with good resistance to chemical cleaning by acidic,alkaline,and oxidative reagents,which could greatly prolong the membrane service lifetime.Furthermore,this approach was demonstrated as a universal method to modify PVDF membranes with other hydrophilic macromolecular modifiers,including polyethylene glycol,sodium alginate,and polyvinyl pyrrolidone.This modification of the membranes effectively endowed them with good hydrophilicity and antifouling properties,as expected.

A Facile Route for the Large Scale Fabrication of Graphene Oxide Papers and Their Mechanical Enhancement by Cross-linking with Glutaraldehyde

A facile route for the large scale production of graphene oxide(GO) papers and their mechanical enhancement has been presented in this work. The novel paper-like GO made from individual GO sheets in aqueous suspension can be achieved in large scale by a simple drop casting method on hydrophobic substrates.Significant enhancement in mechanical stiffness(341%) and fracture strength(234%) of GO paper have been achieved upon modification with a small amount(less than 10 wt%) of glutaraldehyde(GA). The cross-linking reaction takes place between hydroxyl groups on the surface of GO and aldehyde groups of GA, through forming hemiacetal structure, which can result in distinct mechanical enhancement of the GO papers.

Comparison of corneal biological parameters between transepithelial and epithelium-off corneal cross-linking in keratoconus

AIM:To evaluate the differences in corneal biological parameters between transepithelial and epithelium-off corneal cross-linking in keratoconus.METHODS:In our prospective clinical trial,40 patients(60 eyes)with progressive keratoconus were randomized to undergo corneal cross-linking with transepithelial(TE group,n=30)or epithelium-off(EO group,n=30)keratoconus.Examinations comprised topography,corneal biomechanical analysis and specular microscopy at 6 mo postoperatively.RESULTS:The keratometer values were not significantly different between the TE and EO corneal cross-linked groups in different periods(each P>0.05).The corneal thickness of the EO group was greater than that of the TE group at 1 wk after the operation(each P<0.05).Regarding corneal biomechanical responses,the EO group showed a longer second applanation length than TE group(P=0.003).Regarding the corneal endothelial function,standard deviation of the endothelial cell size,and coefficient of variation in the cell area,the values of EO group were larger than those of TE group at 1 wk(P=0.011,0.026),and the percentage of hexagonal cells in EO group was lower than that in TE group at 1 and 6 mo(P=0.018,0.019).CONCLUSION:Epithelium-off corneal cross-linking may strengthen corneal biomechanics better than TE procedure can.However,the TE procedure with a lower ultraviolet-A irradiation intensity would be safer for corneal endothelial function.

Neem by-products in the fight against mosquito-borne diseases:Biotoxicity of neem cake fractions towards the rural malaria vector Anopheles culicifacies(Diptera:Culicidae)

Objective: To evaluate the ovicidal, larvicidal and adulticidal potential of neem cake fractions of different polarity against the rural malaria vector Anopheles culicifacies(An.culicifacies).Methods: Neem cake fractions' total methanol extract(NTMeOH), total ethyl acetate extract(NTAc OEt), ethyl acetate fraction after repartition with NTMe OH(NRAc OEt),butanol fraction after repartition with NTMeOH(NRBuOH), and aqueous fraction after repartition of NTMeOH(NRH2O) were tested against An. culicifacies eggs, fourth instar larvae and adults.Results: In larvicidal experiments, NTMeOH, NTAcOEt, NRAcOEt, NRBuOH and NRH2O achieved LC50 values of 1.32, 1.50, 1.81, 1.95 and 2.54 mg/L, respectively. All fractions tested at 150 mg/L were able to reduce egg hatchability of more than 50%, with the exception of NTAc OEt and NRAc OEt. In adulticidal assays, NTMeOH, NTAcOEt,NRAcOEt, NRBuOH and NRH2O achieved LC50 values of 3.01, 2.95, 3.23, 3.63 and3.00 mg/L, respectively.Conclusions: Overall, this study suggests that the methanolic fractions of neem cake may be considered as a new and cheap source of highly effective compounds against the rural malaria vector An. culicifacies.

Comprehensive utilization of corn starch processing by-products:A review

Corn is a high starchy cereal crop with the highest production and provides over 85%of the starch produced worldwide.Various by-products,differentiated by technological process features such as steep liquor,corn germ,corn bran,gluten,are created largely during corn starch processing.They are inexpensive,nutrient-rich,and vary widely in chemical composition such as proteins,oils,carbohydrates,and minerals.In an increasingly resource-constrained modern world,the utilization approach of these by-products for non-starch industrial processing is attractive widely considering both nutritive value and economic aspects.In fact,at present,applications of these by-products can often be found in feed,fermentation,nutrient extraction and other industries.For example,protein-rich corn gluten can be used as a good animal feed,and corn germ can be used as a raw material for the high-quality edible oil industry.Undoubtedly,increasing utilization means that these by-products will no longer be treated as waste but will be transformed into high value-added products.In this work,the separation process and chemical composition of several main by-products of the corn starch industry is briefly described,and the application in many industrial fields of these by-products over the last ten years are discussed in particular.This review attempts to summarize all aspects of the application and research of these by-products.For the by-products of the corn starch industry,the most promising way is to be utilized in high value and used to produce high value-added products.According to the characteristics of their chemical composition,they have a better application prospect and research significance in the industries directly related to human beings,such as medicine,green food and health care products.In fact,in recent years,some researchers have recognized this and carried out the research.It is clear fromthese studies that the main issues to be faced nowand in the future are how to produce efficiently while maintaining the quality of the product and using it effectively.The retrospective discussions also provide some ideas for other grain and oilseed crops to be fully utilized.

Investigation of the efficiency of intrastromal ring segments with cross-linking using different sequence and timing for keratoconus

· AIM: To evaluate and compare the efficacy and stability of intrastromal corneal ring segment(ICRs)implantation with cross-linking(CXL) using different sequence and timing.· METHODS: In this single retrospective study, 86 keratoconic eyes subjected the ICRs implantation. We analyzed only 41 eyes that had complete follow-ups.They were divided into three groups: ICRs implantation was applied only(group normal), ICRs first followed by CXL immediately(group CXL-S), CXL first followed by ICRs long after(group CXL-B). The visual acuity,refractive results, keratometry were compared preoperatively and 1y postoperatively. Their differences among the three groups were also analyzed.·RESULTS: Group normal comprised 25 eyes, group CXL-S 8 eyes, and group CXL-B 8 eyes. There were improvements in the mean uncorrected distance visual acuity(UDVA) and the mean corrected distance visual acuity(CDVA) compared preoperatively and 1y postoperatively [UDVA: 0.31(P =0.030) logarithmic minimum angle of resolution(log MAR) group normal, 0.4(P =0.020) group CXL-S, 0.45(P =0.001) group CXL-B;CDVA : 0. 21 log MAR( P = 0. 013) group normal, 0. 30(P =0.036) group CXL-S; 0.26(P =0.000) group CXL-B].The refractive and topographic outcomes also showed improvements. In terms of comparisons among the three groups, all the P values were above 0.05, showing no significant difference. But only group CXL-B had improvement in UDVA and CDVA for all the patients.·CONCLUSION: With safety and good visual outcomes,ICRs implantation is a viable alternative for keratoconus.No significant difference was found among these three groups.

Synthesis and Applications of Tetra- functional Branched Poly(ethylene glycol) Derivative for the Decellularized Valve Leaflets Cross-linking

To investigate the effects of polyethylene glycol cross-linking on the mechanical properties, 80 porcine aortic valves were harvested, decellularized, and introduced with sulflaydryl. Then the valves were randomly assigned into 5 experimental groups and 1 control group （n=16）. For the valves in those experimental groups, branched polyethylene glycol diacrylate （PEG） of 5 different molecular weights （3.4, 8, 12, 20, 40 kDa） were synthesized and cross-linked with them respectively. The efficiency of the cross-linking was determined by measuring the amount of residual thiol group and the mechanical properties of the cross-linked valve leaflets were assessed by uni-axial planar tensile testing. The efficiency of the PEG 20 kDa group was 70.72±2.33%, obviously superior to that of the other groups （p〈0.05）. Tensile test proved that branched PEG cross-linking can significantly enhance the mechanical behaviors of the deeellularized valve leaflet and the Young＇s modulus of each group was positively correlated with the molecular weight of PEG. It was concluded that branched PEG with the molecular weight of 20 kDa can effectively cross-link the decellularized porcine aortic valves and improve their mechanical properties, which makes it a promising cross-linker that can be used in the modification of decellularized tissue engineering valves.

Study on Various Compositions of Polyvinyl Alcohol and Starch Blends by Cross-Linking with Glyoxal

The aim of this study is to analyze the various compositions of polyvinyl alcohol (PVA) and starch blends. The blends have been cross-linked with glyoxal to enhance its properties. The hydroxyl groups of PVA and starch react with glyoxal via formation of acetal bonds;hence crosslinking could take place. The cross-linking of glyoxal is observed in various analytical methods such as DSC and FTIR. The cross-linked blends showed better thermal and mechanical properties. Viscosity, tensile shear strength, pencil hardness and ultimate stress were evaluated to estimate the changes due to cross-linking. It was observed that the cross-linking is directly proportional to starch, since the starch hydroxyl groups are easily accessible for reacting. The cross-linked blend showed better cohesion between its chains, thereby increasing glass transition temperature. It was reflected in the subsequent increase in tensile strength properties.