Polyurethane Group Research Articles

Investigation of the Biosafety of Commercially Available Natural Rubber Latex and Synthetic Polyurethane Condom Materials

To investigate the biological safety of commercially available natural rubber latex and synthetic polyurethane condoms. Natural rubber latex condom brands of A1 and A2 and polyurethane condom brands of B1 and B2 were purchased from large chain pharmacies in Chengdu, with three packages randomly selected for each brand. The study assessed the toxic effects of condom extracts on L-929 mouse fibroblasts according to GB/T standards. Gross observation and histopathological evaluation were conducted to assess the irritation reactions of condoms on the vagina and penis of rabbits (3 rabbits were used for each brand), as well as their sensitization effects on guinea pig skin. Additionally, the impact of continuous perfusion of condom extracts of the vaginas of SD rats for 30 days on their reproductive systems was evaluated, following GB/T standards (5 rats were used for each brand). Extracts from natural rubber latex condom brands A1 and A2, at concentrations of 100% and 50%, exhibited significant cytotoxicity, with optical density (OD) values being significantly lower than those of the blank control group and the polyurethane condom brands B1 and B2 (P<0.01). There was no significant difference in cell morphology and OD values between the extracts of B1 and B2 and the blank control group (P>0.05). Vaginal congestion was found in 3 rabbits from A1 group and 1 rabbit from the A2 group, while no obvious congestion was noted in rabbits from the B1 and the B2 groups. Histopathological examination showed scattered inflammatory cell infiltration in the vaginal tissue of 3 rabbits from the A1 group and 2 rabbits from the A2 group, and slight congestion in the blood vessels of the lamina propria. No obvious pathological changes were observed in the vaginal tissue of polyurethane brand rabbits. Two rabbits from the A1 group and 1 rabbit from the A2 group showed transient and mild erythema on the penis during the experiment. Histopathological examination showed that 1 rabbit from A1 group had small foci of pericapillary lymphocytes in the dermis of the penis, while no significant pathological changes were observed in the penile tissue of A2, B1, and B2 groups. After 30 days of continuous vaginal perfusion with condom extract, 3 rats in A1 group and 2 rats in the A2 group had uterine congestion, with the degree of congestion being lower in the A2 group. No significant congestion or pathological changes were observed in the vaginal and penile tissues of rabbits, or in the uterine tissues of rats from the polyurethane groups. None of the 4 groups of guinea pigs showed significant skin allergic reactions to the condom extracts. Significant differences in biosafety exist among condoms of various materials and brands. To ensure product safety, it is crucial to strengthen quality control and regulatory oversight after condoms become commercially available.

The Uniform Distribution of Hydroxyapatite in a Polyurethane Foam-Based Scaffold (PU/HAp) to Enhance Bone Repair in a Calvarial Defect Model

Polyurethane (PU) is a promising material for addressing challenges in bone grafting. This study was designed to enhance the bone grafting capabilities of PU by integrating hydroxyapatite (HAp), which is known for its osteoconductive and osteoinductive potential. Moreover, a uniform distribution of HAp in the porous structure of PU increased the effectiveness of bone grafts. PEG/APTES-modified scaffolds were prepared through self-foaming reactions. A uniform pore structure was generated during the spontaneous foaming reaction, and HAp was uniformly distributed in the PU structure (PU15HAp and PU30HAp) during foaming. Compared with the PU scaffolds, the HAp-modified PU scaffolds exhibited significantly greater protein absorption. Importantly, the effect of the HAp-modified PU scaffold on bone repair was tested in a rat calvarial defect model. The microstructure of the newly formed bone was analyzed with microcomputed tomography (μ-CT). Bone regeneration at the defect site was significantly greater in the HAp-modified PU scaffold group than in the PU group. This innovative HAp-modified PU scaffold improves current bone graft materials, providing a promising avenue for improved bone regeneration.

Nano-SiO2/polyurethane modified unsaturated polyester resin mortar for thin layer repairing on airport pavement

This paper introduces a novel toughened polymer mortar designed for runway repair, featuring outstanding impact resistance, high strength, and cost-effectiveness. To augment the toughness of unsaturated polyester (UP) polymer mortar, nano-SiO2 and polyurethane (PU) were incorporated. Firstly, the optimal dosages of nano-SiO2 and PU were determined through tensile test and impact test. Then, the modification mechanism of nano-SiO2/PU on UP resin was explored by microscopic image technology. In addition, the compression, flexural, fluidity, flexural bond strength and construction time tests were carried out to determine the optimal formula of nano-SiO2/PU modified UP resin mortar. Finally, the durability, impact resistance, impermeability resistance, skid resistance, and interlayer bond strength of modified UP resin mortar were studied and compared with those of pure UP resin mortar and epoxy (EP) resin mortar. Results show that the optimum proportion by mass for nano-SiO2/polyurethane modified UP resin is, UP resin: PU: dibutyltin dilaurate: nano-SiO2: initiator: accelerator: diluent: plasticizer = 1: 0.1: 0.002: 0.01: 0.01: 0.01:0.15:0.01. Furthermore, the mass proportion of modified UP resin to aggregate is 1: 1.2. In nano-SiO2/PU modification of UP resin, the -NCO groups of PU have been involved in chemical interaction with the -OH group of UP, while nano-SiO2 and UP resin are blended physically only. Compared with pure UP resin mortar, the nano-SiO2/PU modified UP resin mortar exhibited a 44% reduction in shrinkage rate, approximately 20% less corrosion loss, a 32% decrease in freeze-thaw loss, a 37% improvement in impact resistance, and increased shear bonding strength, flexural bonding strength, and tensile bonding strength by 44%, 33%, and 47%, respectively. Although the modified UP resin mortar demonstrated slightly lower performance in terms of dry shrinkage, corrosion resistance, skid resistance, and tensile bond strength compared to EP resin mortar, its freeze-thaw durability, impact resistance, flexural bond strength, and shear bond strength surpassed those of EP resin mortar. All three materials exhibited excellent impermeability. Leveraging the advantages of PU and nano-SiO2, the modified UP resin presents a promising repair material for airport pavement with enhanced toughness, high stability, and reduced cost.

The effect of polycaprolactone polyol molecular weight and chain extender type on the physico-mechanical properties and gas permeability of polyurethane thermoplastic elastomer membranes

ABSTRACT In this study, polyurethane thermoplastic elastomers (TPU) were synthesized using isophorone diisocyanate (IPDI), 1,4-butanediol (BDO), and 1,6-hexanediol (HDO) as the chain extenders, and polycaprolactone diol (PCL-diol) with three different molecular weights (2000, 4000, and 10,000 g/mol) as polyols. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) patterns, and differential scanning calorimetry (DSC) were conducted to analyze the chemical microstructure and phase morphology of the prepared samples. The results showed that the change in the chain extender’s type (BDO and HDO) leads to a decrease in the hydrogen bonding index (HBI). Increasing the molecular weight of PCL-diol in BDO-based TPUs has led to an increase in their crystallinity, Young’s modulus, melting temperature, tensile strength, and a decrease in glass transition temperature and elongation at break. Moreover, the increase in the molecular weight of PCL-diol in HDO-based TPUs demonstrated an increase in the crystallinity and elongation at break and tensile strength up to the molecular weight 4000 in PCL-diol, after that, there was a decrease in those properties due to the increase of the soft segments content and change in the chain extender type. Permeability on TPU membranes was performed for N2 and CO2 at three different pressures 3, 6, and 9 atm at room temperature. An increase in pressure led to an increase in membrane permeability due to the increase in gas solubility in TPU based on Henry’s law. The permeability of CO2 is higher than N2 due to the proper interactions of CO2 gas with the polar carbonyl groups of polyurethane. It is observed that the permeability increases in BDO-based samples with an increase in the molecular weight of PCL-diol, while the increase in permeability of HDO-based TPU is up to PCL-diol molecular weight 4000 and after that is decreased. The selectivity of CO2 has decreased with increasing pressure due to the higher rate of dissolution of N2 at higher pressures.

Preparation of Yellowing-Resistant Waterborne Polyurethane Modified with Disulfide Bonds.

Waterborne polyurethane, renowned for its lightweight properties, excellent insulation capabilities, and corrosion resistance, has found extensive application in fields such as construction, automotive, leather, and thermal insulation. Nevertheless, during operational usage, waterborne polyurethane materials, akin to other polymeric substances, are susceptible to oxidative aging manifestations like yellowing, cracking, and diminished mechanical performance, significantly curtailing their utility. Consequently, the synthesis of yellowing-resistant polyurethane assumes pivotal significance. This study integrates dynamic reversible reactions into the synthesis process of polyurethane by introducing the dynamic reversible compound 2-hydroxyethyl disulfide as a chain extender, alongside the incorporation of a UV absorber to enhance the polyurethane's resistance to yellowing. When the disulfide bonds absorb heat, they undergo cleavage, yielding thiols that spontaneously recombine into disulfide bonds at ambient temperatures, allowing for the continuous breaking and reformation of disulfide bonds to absorb heat. Concurrently, in collaboration with the UV absorber, the detrimental effects of ultraviolet radiation on the polyurethane material are mitigated, thereby augmenting its resistance to yellowing. This study scrutinizes the positioning of UV absorber addition, the quantity of UV absorber, and the molar ratio of 1,4-butanediol to 2-hydroxyethyl disulfide, characterizing the functional groups of polyurethane through infrared and Raman spectroscopy. It is observed that the successful preparation of yellowing-resistant polyurethane is achieved, and evaluations on the modified polyurethane through color difference, tensile, and centrifugal tests reveal that the optimal yellowing resistance is attained by adding a UV absorber at a mass fraction of 1% to 3% prior to chain extension, resulting in a color change grade of 2, denoting slight discoloration. Simultaneously, the other properties of polyurethane exhibit relative stability. Notably, when the molar ratio of 1,4-butanediol to 2-hydroxyethyl disulfide is 3:2, the overall performance of the polyurethane remains stable, with exceptional yellowing resistance capabilities attaining a color change grade of 2.

Mechanical Stretch α-Cyclodextrin Pseudopolyrotaxane Elastomer with Reversible Phosphorescence Behavior.

Polyethylene glycol chains in two terminals of the naphthalene functional group are threaded into α-cyclodextrin cavities to form the pseudopolyrotaxane (NPR), which not only effectively induces the phosphorescence of the naphthalene functional group by the cyclodextrin macrocycle confinement, but also provides interfacial hydrogen bonding assembly function between polyhydroxy groups of cyclodextrin and waterborne polyurethane (WPU) chains to construct elastomers. The introduction of NPR endows the elastomer with enhanced mechanical properties and excellent room temperature phosphorescent(RTP) emission (phosphorescence remains in water, acid, alkali, and organic solvents, even at 160 °C high temperatures). Especially, the reversible mechanically responsive room temperature phosphorescence behavior (phosphorescence intensity increased three times under 200% strain) can be observed in the mechanical stretch and recover process, owing to strain-induced microstructural changes further inhibiting the non-radiative transition and the vibration of NPR. Therefore, changing the phosphorescence behavior of supramolecular elastomers through mechanical stretching provides a new approach for supramolecular luminescent materials.

Examining the effect of polyurethane dressing containing silver particles on the rate of diabetic foot ulcer infection in hospitalized patients: A randomized control study.

One of the new types of dressings is the polyurethane dressing containing silver particles. This study was designed to evaluate the effect of polyurethane dressing containing silver particles on the rate of diabetic foot ulcer infection in hospitalized patients in a military hospital. This was a randomized clinical trial study on 48 patients with diabetic foot ulcers who were referred to the wound clinic of Shahid Dr. Chamran Hospital in 2022. The qualified samples were divided into two groups of silver polyurethane dressing and simple sterile dressing based on a randomization block method. The wounds of both groups of patients were initially cleaned with normal saline and in the first round of dressing, and a sample of tissue secretions was collected by the researcher using a sterile swab from the wounds of the patients on two occasions, superficially and deeply. The patients' wounds in the intervention group were dressed with polyurethane foam dressing containing silver particles, while the simple sterile routine dressing was used in the control group. The rate of infection and wound secretions were examined and recorded on the first, seventh, fourteenth, and twenty-first days from the start of dressing in both groups. To collect data, the IDSA tool was used. The rates of wound infection before the intervention showed no significant differences in the two groups (p = 0.242). However, these rates changed on the 7th, 14th, and 21st days after the intervention. Moreover, the infection rate was significantly lower in the polyurethane dressing group containing silver particles (p < 0.001 and F = 30.31). Using polyurethane dressing was proven to be more effective in this study on the rate of diabetic ulcer infection in patients compared to the simple sterile dressing. Thus, nurses can use this dressing for faster treatment of diabetic foot ulcers infection.

Effect of dry-wet cycles on mechanical properties of polyurethane porous mixture

ABSTRACT Polyurethane porous mixture (PUPM) is a novel material with potential to extend the service life of pervious pavement. The porous structure makes the interior of the pavement material inevitably exposed to frequent cyclic action of environmental factors. However, the mechanical property decay behaviour of PUPM under the dry-wet cycles formed by water, air and corrosive ions is still unclear. Therefore, the mechanical properties of PUPM under different dry-wet cycles were characterised by Marshall stability, splitting strength and uniaxial compression strength tests. The variations in the microscopic properties of PUPM were investigated by computed tomography (CT), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. The grey entropy correlation theory was used to analyse the effect of variations in the functional groups of polyurethane on the mechanical properties of PUPM. It was concluded that the ageing of the polyurethane and the disruption of the bond at the binder-aggregate interface are the fundamental reasons for the mechanical property decay of PUPM. The influence of each functional group on the mechanical strength of the PUPM is in this descending order: amino groups linked to the carbonyl groups, carbonyl groups, ether bonds, methylene groups, and amino groups formed hydrogen bonds with water.

Crosslinking of waterborne polyurethane using dibromide as a crosslinker and 1,1,3,3-tetramethylguanidine (TMG) as an esterification promotor

Pursuing high performance and solving the dilemma of existing materials are the driving force of material research. Waterborne polyurethane (WPU) is an environmentally benign material with excellent performance and wide use. However, due to its inherent hydrophilic groups, such as carboxyl, the waterproof and mechanical properties of its corresponding films have been seriously affected. To address this dilemma, herein we proposed a new crosslinking method by using commercialized dibromide as a crosslinker and 1,1,3,3-tetramethylguanidine (TMG) as an esterification promoter, to make the carboxyl groups of waterborne polyurethane and dibromide undergo esterification crosslinking reaction, which reduces the content of carboxyl groups while realizing the crosslinking of WPU films. The results show that the water absorption of WPU films crosslinked by this method is greatly reduced, the hydrophobic property (contact angle) is significantly improved, and the mechanical properties are greatly enhanced. Meanwhile, to facilitate construction and commercial application, we designed a two-component WPU coating, and their corresponding films also show great hydrophobic and mechanical properties. In a word, the crosslinking method has the advantages of low cost, simple operation, high crosslinking efficiency and mild reaction conditions.

Adhesion of Biofilm to Mortar Surface with Protective Coating in Seawater Environment and the Influence on the Mortar Performance

To improve the corrosion resistance and mechanical properties of mortars in seawater, this work explored the evolution of biofilm adhered on mortar surfaces with different protective coatings and the mortar properties in the seawater environment. Sulfur-oxidizing bacteria were selected as experimental strains, and epoxy resin and polyurethane as protective coatings. The performance of each group of samples was tested from the 15th day to the 120th day at intervals of 15 days. The evolution and morphology of the biofilms were measured by scanning electron microscopy (SEM), a common camera, ultraviolet-visible spectroscopy (UV-Vis), and ultra-deep field microscope. The properties and microstructure of the mortars were determined by X-ray diffractometer (XRD), thermogavimetric analyzer (TG), energy dispersive spectroscopy (EDS), and electro-hydraulic pressure laboratory machines. The results show that: (1) In a seawater environment, protective coatings can effectively impede the adhesion of biofilms, and the beginning of the rapid growth period of the biofilms is delayed from day 30 to day 60. (2) On day 120, the highest dehydration rate of 0.61% is for the uncoated specimen. In contrast, the epoxy resin group experienced a dehydration rate of 0.57%, and the polyurethane group a dehydration rate of 0.53%. This indicates that a polyurethane coating can effectively hinder the entrance of corrosive media from the seawater, alleviate the tendency of the mortar to swell, delay the corrosion process of the mortar in the seawater, and provide some degree of protection for the mortar.

In Situ High‐performance Gel Polymer Electrolyte with Dual‐reactive Cross‐linking for Lithium Metal Batteries

Lithium metal batteries have been considered as one of the most promising next‐generation power‐support devices due to their high specific energy and output voltage. However, the uncontrollable side‐reaction and lithium dendrite growth lead to the limited serving life and hinder the practical application of lithium metal batteries. Here, a tri‐monomer copolymerized gel polymer electrolyte (TGPE) with a cross‐linked reticulation structure was prepared by introducing a cross‐linker (polyurethane group) into the acrylate‐based in situ polymerization system. The soft segment of polyurethane in TGPE enables the far migration of lithium ions, and the ‐NH forms hydrogen bonds in the hard segment to build a stable cross‐linked framework. This system hinders anion migration and leads to a high Li+ migration number ( = 0.65), which achieves uniform lithium deposition and effectively inhibits lithium dendrite growth. As a result, the assembled symmetric cell shows robust reversibility over 5500 h at a current density of 1 mA cm−2. The LFP¦¦TGPE¦¦Li cell has a capacity retention of 89.8% after cycling 800 times at a rate of 1C. In summary, in situ polymerization of TGPE electrolytes is expected to be a candidate material for high‐energy‐density lithium metal batteries.

Percutaneous cholecystoduodenal stent as a definite treatment for acute cholecystitis in elderly or comorbid patients: a bicentric retrospective study

To investigate the safety and efficacy of percutaneous cholecystoduodenal stent (CDS) placement to prevent recurrence of acute cholecystitis in patients who were unfit for cholecystectomy. Between April 2016 and January 2022, 46 patients [median age (range) = 81 (37-99) years; men = 15] with acute cholecystitis who were unfit for surgery underwent percutaneous cholecystostomy followed by a CDS placement in two institutions. Plastic stents of three different materials were used [polyethylene, polyurethane (PU), and polycarbonate (PCB)-based PU]. Clinical outcomes, including technical and clinical success rates and early (<30 days) and delayed adverse events, were retrospectively assessed by stent type. CDS placement was technically successful in 39 patients. Clinical success, defined as cholecystostomy catheter removal, was achieved in 35 of 39 patients. Immediate complications, such as acute pancreatitis and peritonitis, occurred in two patients. Two patients experienced recurrent cholecystitis during a 113-day follow-up (range, 3-1,723). Three-stent groups had significantly different delayed complications on Fisher's exact test (P = 0.021). The Bonferroni post-hoc analysis showed the PCB-PU group tended to have fewer complications than the PU group (P = 0.060). CDS placement is applicable in treating acute cholecystitis patients who were initially unfit for surgery, but further investigation is needed. Although it was not statistically significant, a PCB-PU stent can be suitable for this use because it tends to have fewer delayed complications and is equipped with a drawstring and side holes.

Achieving fast and stable Li+ transport in lithium-sulfur battery via a high ionic conduction and high adhesion solid polymer electrolyte

Solid-state lithium (Li)-sulfur (S) batteries are promising secondary batteries because of their high energy density and high safety, but their practical application is severely hindered by poor Li-ions (Li+) transport in batteries due to low ionic conduction of the electrolyte and unstable electrode/electrolyte interface. Here, we address the issue by using a polyurethane (PU)-based electrolyte. The polar urethane/urea groups of PU reduce the hopping energy barrier of Li+, which results in high ionic conductivity of 1.8 × 10-4 S cm-1 (25 °C), high ion transference number of 0.54, and low activation energy of 0.39 eV. In addition, the polar urethane/urea groups endow the electrolyte with high adhesion, which allows the electrode/electrolyte interfaces to self-heal timely after being damaged during cycling. Benefiting from these merits, a symmetric Li||Li cell using the polyolefin-PU-bis(trifluoromethane)sulfonimide lithium salt electrolyte can cycle for approximately 800 h with a stable overpotential (approximately 40 mV), and a solid-state Li-S battery using the electrolyte delivers a specific capacity of approximately 610 mAh g-1 after testing for 125 cycles at a S loading of about 4 mg cm-2. Self-healing of the electrode/electrolyte interfaces during cycling was observed in situ by a laser confocal microscope. This study demonstrates the importance of polar groups in electrolytes in maintaining a fast and stable Li+ transport, which can be applied to other solid-state batteries.

Amphoteric waterborne polyurethane with unsaturated carboxyl group as crosslinker to improve cohesive strength of soybean protein-based adhesive for excellent cold-pressing adhesion

The cold-pressing performance of adhesives is important for the preparation of wood-based panels. Adhesives for wood-based panels must have appropriate viscosity, strong interfacial adhesion to wood substrates with hydration layers, and excellent cohesive strength at ambient temperature for cold-pressing adhesion. However, bio-based adhesives synthesized using conventional modification approaches still struggle to meet these standards. Herein, an amphoteric waterborne polyurethane with an unsaturated carboxyl group (AWPU-UC) is prepared as a crosslinker to modify soybean meal (SM) matrix, and prepare a soybean protein-based adhesive with excellent cold-pressing adhesion and mildew resistance. The unsaturated carboxyl groups form electrostatic interactions with tertiary ammonium groups of polyurethane and amino groups of protein molecules in the SM matrix. These bonds enhance both the cohesion of adhesive molecular network and the interaction between the adhesive and wood surface with “hydration layers”. Consequently, the cold-pressing bonding strength of the adhesives SM/AWPU-UC-4 reaches 271% of that of pure SM adhesive. In addition, the quaternary ammonium structure formed by electrostatic interactions in the AWPU-UC system endows the adhesive with mildew resistance. This study provides a simple and effective method for producing high-performance protein-based adhesives with outstanding cold-pressing adhesion and mildew resistance. • An amphoteric waterborne polyurethane emulsion with unsaturated carboxyl groups was synthesized. • The emulsion facilitated diffusion and creation of interaction of adhesives with the wood substrate. • The electrostatic interaction between unsaturated carboxyl groups and aminos on protein promoted cohesive crosslinking. • The quaternary ammonium structure produced by electrostatic interaction made it possess bactericidal ability. • The bio-adhesives had excellent cold-pressing performance and mildew resistance with AWPU-UC as a crosslinker.

New method for graphitizing polyurethane (PU) prepolymers over cellulose fiber surface and physical properties assessment on cementitious composites

A new method to graft polyurethane groups on cellulose fiber surface in a propylene carbonate medium, followed by a washing step with methylene chloride is proposed. The synthesis process in propylene carbonate solvent medium is an effective and straightforward way to graft polyurethane prepolymers on cellulose fibers. Reaction was carried out in non-pressurized vessels and low temperature (60 °C). The cleaning step proposed with methylene chorine solvent was effective as no signal of isocyanate group (NCO) was found on Fourier-transform infrared spectroscopy performed on grafted fibers. X-ray photoelectron spectroscopy results from cellulose modified fibers show the presence of nitrogen and a corresponding increase in CC bonds on the cellulose surface, which suggests that polyurethane prepolymer was successfully grafted on fiber surfaces. Secondary ion mass spectrometry images collected from polyurethane grafted fibers indicate that the isocyanate is uniformly distributed on the cellulose modified with PAPI™ 27 Polymeric MDI. Application tests carried out on fiber cement composites showed promising results. PAPI™ 27 Polymeric MDI grafted on the cellulose fibers surface has reduced the water absorption on fiber cement composites by approximately 15 % (p < 0.05) compared to composites prepared with non-modified cellulose fibers. Nevertheless, further exploration on fiber cement composite application is required to understand the impact of the cellulose treatment on the mechanical properties, fiber preservation and overall durability aspects.

Treatment of phenols and NH3–N with activated carbon and polyurethane carrier in biological enrichment reactor

Coal pyrolysis wastewater contains a large number of phenols, ammonia, and various monocyclic and polycyclic aromatic compounds. In the study, activated carbon (AC) or polyurethane (PU) suspension carriers were comprehensively compared from efficiency, influencing factors, extracellular polymeric substances, and microbial population distribution to explore the suitable carrier in biological enrichment reactor the treatment of coal pyrolysis wastewater. In the start-up stage, the treatment effect of COD and total phenol (TPh) in the PU group (COD 86%, TPh 75%) was lower than that of the AC group (COD 94%, TPh 88%). However, with the loading of biofilm on PU, the treatment effects in the PU group began to improve. When COD was approximately 1000 mg/L and TPh was 500 mg/L, both the AC group and PU group showed sound treatment effects on COD (≥87%) and TPh (∼99%). Moreover, the PU group showed a higher removal effect of NH3–N (32.22%) and TN (30.85%). HRT should be 24 h to ensure partial degradation of organic matter and save carbon source dosage of the subsequent A/O treatment unit. Moreover, it had a removal effect on NH3–N and TN, which could effectively reduce the load of the subsequent multistage A/O treatment unit. The dominant functional bacteria in the AC and PU groups included Acidovorax, Alicycliphilus, Chryseobacterium, Rhodanobacter, and Thermomonas. Acidovorax, Alicycliphilus, and Chryseobacterium were the main functional bacteria involved in TPh and COD degradation. AC was suitable for rapidly reducing the concentration of pollutants or dealing with sudden increases in pollutants, while PU was more conducive to the long-term and stable operation of the biological enrichment reactor.

Feasibility study on the preparation of novel negative pressure materials for constructing new matrix of full-thickness skin defect wounds in rats

Feasibility study on the preparation of novel negative pressure materials for constructing new matrix of full-thickness skin defect wounds in rats

Polyurethane Versus Calcium Alginate Dressings for Split-Thickness Skin Graft Donor Site: A Systematic Review and Meta-Analysis.

Herein, we compare the outcomes of polyurethane and calcium alginate dressings for split-thickness skin graft (STSG) donor sites.A systematic review and meta-analysis were conducted with a search of electronic databases to identify all randomised controlled trials (RCTs) and observational studies comparing the outcomes of polyurethane dressing versus calcium alginate for STSG donor sites. Primary outcomes were pain intensity, convenience for staff and patients, and adverse effects (namely, excessive exudate, infection rate, and hematoma). Secondary outcome measures included the assessment of healing, dressing changes, cosmetic appearance, and cost. Fixed and random-effect models were used for the analysis.Four RCTs enrolling 127 subjects were identified. There was no significant difference between polyurethane and calcium alginate in terms of pain intensity on Day 1 (mean difference (MD) 0.13, P = 0.80) and Day 5 (MD = 0.20, P = 0.38), as well as the ease of application (odds ratio (OR) = 3.08, P = 0.47). However, there was a statistically significant improvement in patient comfort, favouring the polyurethane group (OR = 44.11, P < 0.00001). In addition, no statistically significant differences were noted in terms of adverse effects between the two dressings. In terms of cost, the calcium gluconate dressing had an overall higher cost compared to polyurethane.Polyurethane is a more favourable dressing compared to calcium alginate for STSG donor sites in terms of patient comfort, healing, and cosmetic outcomes. However, comparable results were noted in terms of pain intensity, ease of application, and adverse effects profile. Cost-effectiveness analysis studies are required to justify its routine use.

Does catheter material affect functional performance of intravenous ports via the superior vena cava?

IntroductionThe catheter is the only intravascular portion of an implanted port and plays a crucial role in catheter related complications. Both polyurethane and silicone are biocompatible materials which are utilized for catheter manufacturing, but their correlation to complications remains controversial. The aim of this study was to try to analyze the relationship between catheter materials and complications.Materials and methodsA total of 3144 patients who underwent intravenous port implantation between March 2012 and December 2018 at Chang Gung Memorial Hospital, Linkou, Taiwan were recruited. Of these, 1226 patients received silicone catheter port implantation and 1679 received polyurethane catheter ports. Case matching was done prior to analysis and catheter related complications and cumulative complication incidence for each group were compared.ResultsIntergroup differences were identified in entry vessel (p = 0.0441), operation year (p < 0.0001), operation method (p = 0.0095), functional period (p < 0.0001), patient follow up status (p < 0.0001), operating time for vessel cutdown (p < 0.0001) and wire assisted approach (p = 0.0008). Stratified by specific entry vessel, no statistical difference was found in complication rate or incidence between the silicone and polyurethane groups. We further compared the cumulative complication incidence of the silicone and polyurethane groups, and also found no statistical difference (p = 0.4451).ConclusionAs long as external stress forces generated by surrounding structures and focused on potential weak points are avoided, both silicone and polyurethane materials provide sufficient structural stability to serve as reliable vascular access for patients.

A novel high mechanical and excellent hydrophilic electrospun polyurethane‐silk‐bioactive glass nanofiber film for rotator cuff injury repair

AbstractRotator cuff injury is the most common muscle injury in bone surgery and there was still enormously challenging to completely repair it. Disturbed by mechanical stability and biocompatibility, most implants have failed to relieve symptoms and prevent the development of osteoarthritis. Herein, we have firstly fabricated novel electrospinned nanofiber membranes by integrating the excellent mechanical properties of polyurethane (PU), the good biocompatibility of silk fibroin with the osteogenesis properties of bioactive glass (PSB). The obtained results have exhibited that the PSB nanofiber film possessed excellent mechanical properties with the tensile stress have reached 14.6 MPa and the tensile strain reached 70%, which had extremely remedied the properties of pure silk film (3.8 MPa and the tensile strain 7.9%). Especially, PSB has shown superior hydrophilicity (WCA) than silk (WCA) and PU (WCA) groups. Furthermore, we have endowed the PSB with osteogenesis by doping bioactive glass (BG) in it. The PSB film can long‐term release functional ions (Si and B ions) that benefit bone tissue repair, and the CCK‐8 and ALP results have also confirmed the excellent biocompatibility and osteogenesis of PSB. Hence, the novel PSB film may provide a new treatment strategy for repairing rotator cuff injury.