Gradient heating activated ammonium persulfate oxidation for efficient preparation of high-quality chitin nanofibers.

APS is a cheap and eco-friendly oxidant which enables one-step extraction of nanochitin (NCh) from fishery wastes. However, it is challenging to improve the preparation efficiency and NCh quality simultaneously, owing to the uneven or uncontrollable oxidation. Herein, we propose a simple and controllable way to isolate chitin nanofibers (ChNFs) from squid pen by gradient heating activated (GHA)- ammonium persulfate (APS) oxidation. Compared to the isothermal activated (ITA)-APS oxidation, our strategy reduced the mass ratio of squid pen to APS from 1:45 to 1:6 and reaction time from 15 h to 8 h. Meanwhile, the as-prepared ChNFs exhibited high yield (91.5 %), light transmittance (98 % at 500 nm), crystallinity index (96.9 %), and carboxyl content (1.53 mmol/g). GHA-APS oxidation involved multiple continuous heating and isothermal stages. The former stimulates a moderate activation of APS and enhances the oxidation rate, while the latter provides a duration for surface chemistry. This non-isothermal heating facilitates the continuous decomposition of APS at a relatively high and consistent rate, thereby enhances its oxidation efficiency. Furthermore, green assessments indicate this method is simple, time-saving, eco-friendly and cost-effective. Overall, this work introduces a novel perspective for the industrial extraction of high-efficiency and high-quality nanomaterials.

Hair Product Allergy: A Review of Epidemiology and Management.

Allergy to hair products is an increasingly common issue among people given the exposure to these products on a daily basis. Allergic reactions could be in the form of delayed-type contact dermatitis or the form of immediate-type hypersensitivity reactions. Hair products contain many ingredients and chemicals that patients may have allergies to, but common allergens are hair dyes, fragrances, persulfate salts, ammonium thioglycolate, coconut fatty acid derivatives, and acrylates. Allergy to hair dye is the most common followed by other allergens such as fragrances and persulfate salts. We discussed testing for hair dye allergy along with suggestions for alternative hair dyes that patients may use. Allergy to topical scalp medications is also seen in patients using those products. Allergy to topical minoxidil is seen more often due to the increased use of minoxidil sprays and foams among patients to increase hair growth. We will discuss in this review the diagnosis and alternatives for patients with minoxidil allergy. Hairdressers are at higher risk of allergy to hair products compared to the general population due to prolonged exposure to allergens and specific measures should be implemented to minimize the hazards of exposure.

Synergistic efficacy of ultrasound and ammonium persulfate in inactivating Escherichia coli O157:H7 in buffered peptone water and orange juice.

This study investigated the synergistic effects of ammonium persulfate (PS) and ultrasound (US) on the inactivation of Escherichia coli O157:H7 in buffered peptone water (BPW) and orange juice products. A comprehensive assessment of PS concentrations ranging from 1 to 300 mM, considering not only the statistical significance but also the reliability and stability of the experimental outcomes, showed that 150 mM was the optimal PS concentration for the inactivation of E. coli O157:H7. Additionally, US output intensities varying from 30 % to 60 % of the maximum US intensity were evaluated, and 50 % US amplitude was found to be the optimal US condition. A 50 % amplitude setting on the sonicator corresponds to half of its maximum displacement, approximately 60 µm, based on a maximum amplitude of 120 µm. The inactivation level of E. coli O157:H7 was significantly enhanced by the combined treatment of PS and US, compared to each treatment of PS and US alone. In the BPW, a 10-min treatment with the combination of PS and US resulted in a significant synergistic inactivation, achieving up to a log reduction of 3.86 log CFU/mL. Similarly, in orange juice products, a 5-min treatment with the combination of PS and US yielded a significant synergistic inactivation, with a reduction reaching 5.90 log CFU/mL. Although the treatment caused a significant color change in the sample, the visual differences between the treated and non-treated groups were not pronounced. Furthermore, the combined treatment in orange juice demonstrated significantly enhanced antimicrobial efficacy relative to BPW. Despite identical 5-min treatment periods, the application in orange juice resulted in a substantially higher log reduction of E. coli O157:H7, achieving 7.16 log CFU/mL at a reduced PS concentration of 30 mM, whereas the same treatment in BPW yielded only a 2.89 log CFU/mL reduction at a PS concentration of 150 mM, thereby highlighting its significantly superior antimicrobial performance in orange juice. The mechanism underlying microbial inactivation, induced by the combined treatment of PS and US, was identified as significant cell membrane damage. This damage is mediated by sulfate radicals, generated through the sono-activation of persulfate. In addition, the low pH of orange juice, measured at 3.7, is likely to have further deteriorated the E. coli O157:H7 cells compared to BPW (pH 7.2), by disrupting their cell membranes, proton gradients, and energy metabolism. These findings underscore the effectiveness of PS and US integration as a promising approach for non-thermal pasteurization in the food industry. Further research is needed to optimize treatment parameters and fully explore the practical application of this technique in large-scale food processing operations. Sensory evaluation and nutritional assessment are also necessary to address the limitations of PS.

Synthesis and characterization of a bio-aldehyde-based lignin adhesive with desirable water resistance.

Wood-based panels find widespread application in the furniture and construction industries. However, over 90 % of adhesives used are synthesized with formaldehyde, leading to formaldehyde emission and associated health risks. In this study, an entirely bio-based adhesive (OSL) was innovatively proposed through the condensation of multi-aldehyde derived from the oxidization of sucrose (OS) with sodium lignosulfonate (L). This approach positioned oxidized sucrose (OS) as a viable substitute for formaldehyde, ensuring safety, simplicity, and enhance water resistance upon reaction with L. The optimization of the OSL adhesive preparation process involved determining the oxidant level for high sucrose conversion to aldehyde (13 % based on sucrose), the mass ratio of OS to L (0.8), and hot-pressing temperature (200 °C). Notably, the shear strength of 3-plywood bonded with the developed adhesive (1.04 MPa) increased to 1.42 MPa after being immersed in hot water at 63 ±â€¯3 °C for 3 h. Additionally, the plywood specimens exhibited excellent performance after soaking in boiling water for 3 h, resulting in a shear strength of 1.03 MPa. Chemical analysis using Fourier-transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (NMR), and X-ray photoelectron spectroscopy (XPS) confirmed an addition reaction between L and OS, forming a dense network structure, effectively enhanceing the water resistance of OSL adhesives. Furthermore, compared with lignin-formaldehyde resin adhesive (LF), the OSL adhesive exhibited superior wet shear strength. This study offered an innovative approach for developing lignin-based adhesives utilizing a biomass aldehyde (OS), as a promising substitute for formaldehyde in the wood industry. The findings indicated that this approach may advance lignin-based adhesives, ensuring resistance to strength deterioration under highly humid environmental conditions.

Fabrication of alginate-based hydrogel microparticle via ruthenium-catalyzed photocrosslinking.

In this study, we developed an alginate-based microparticle production process via sodium ruthenium(II) tris-bipyridyl dication (Ru)/ammonium persulfate (SPS)-mediated visible light crosslinking system using a microfluidic device. Microparticles were prepared by crosslinking phenolic-substituted alginate (AlgPh) and incorporated gelatin (GelPh) in an aqueous solution containing SPS, which flowed into an ambient immiscible liquid paraffin-containing Ru using coaxial double orifice microfluidic device. The hydrogel microparticles appeared with the desired geometries and dimensions under optimal conditions. The concentration of AlgPh and light intensity were the most critical parameters for harvesting spherical microparticles with homogeneous size distribution. The physical properties of the prepared AlgPh microparticles were characterized and compared with Alg-Ca microparticles. Cell viability and proliferation preserved on AlgPh/GelPh hydrogel surfaces. Also, encapsulated cells in microparticles were also viable and proliferated well over 13 days after encapsulation. In brief, the results proved the feasibility of fabricating AlgPh vehicles via Ru/SPS-mediated system and visible light irradiation as a simple and efficient three-dimensional platform, which are applicable for various tissue engineering and cell delivery purposes.

Investigating the migration hypothesis: Effects of trypsin-like protease on the quality of muscle proteins of red shrimp (Solenocera crassicornis) during cold storage.

This study aimed to investigate the effect of trypsin-like protease (TLP) on the quality of muscle proteins in red shrimp (Solenocera crassicornis) during cold storage. The results indicated that the activity of TLP decreased significantly in the head of shrimp but increased significantly in the muscle tissues during the cold storage. The myofibril fragmentation index (MFI) value of intact shrimp was significantly higher than that of beheaded shrimp, while the Ca2+-ATPase activity of intact shrimp was significantly lower than that of beheaded shrimp. SDS-PAGE analysis showed that the molecular weight of purified TLP from the shrimp head was about 24 kDa, and the TLP showed high activity at 50 °C and pH 8, indicating that the TLP belongs to the trypsin family. Results from in vitro simulation experiments indicated that the process of TLP incubation significantly reduced the particle size and enlarged the distribution of myofibrillar proteins (MPs) in shrimp muscle tissues. The comparisons were made with respect to the control samples. It can be inferred that TLP migrated from the shrimp head to the muscle tissues during storage and thus promoted the degradation of MPs in red shrimp. The beheading treatment could be an effective mean to maintain better quality and extend the commercialization of shrimp products.

Temperature-Sensitive Aerogel Using Bagasse Carboxylated Cellulose Nanocrystals/N-Isopropyl Acrylamide for Controlled Release of Pesticides.

Temperature-sensitive carboxylated cellulose nanocrystals/N-isopropyl acrylamide aerogels (CCNC-NIPAMs) were developed as novel pesticide-controlled release formulas. Ammonium persulfate (APS) one-step oxidation was used to prepare bagasse-based CCNCs, and then the monomer N-isopropyl acrylamide (NIPAM) was successfully introduced and constructed into the temperature-sensitive CCNC-NIPAMs through polymerization. The results of the zeta potential measurement and Fourier infrared transform spectrum (FTIR) show that the average particle size of the CCNCs was 120.9 nm, the average surface potential of the CCNCs was -34.8 mV, and the crystallinity was 62.8%. The primary hydroxyl group on the surface of the CCNCs was replaced by the carboxyl group during oxidation. The morphology and structure of CCNC-NIPAMs were characterized via electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), compression performance, porosity analysis, and thermogravimetric (TG) analysis. The results demonstrate that CCNC-NIPAM has a high porosity and low density, as well as good thermal stability, which is conducive to loading and releasing pesticides. In the swelling, drug loading, and controlled release process, the CCNC-NIPAM exhibited significant temperature sensitivity. Under the same NIPAM reaction amount, the equilibrium swelling rate of the CCNC-NIPAM first increased and then decreased with increasing temperature, and the cumulative drug release ratio of the CCNC-NIPAM at 39 °C was significantly higher than that at 25 °C. The loading efficiency of the CCNC-NIPAM on the model drug thiamethoxam (TXM) was up to 23 wt%, and the first-order model and Korsmyer-Peppas model could be well-fitted in the drug release curves. The study provides a new method for the effective utilization of biomass and pesticides.

Ammonium Persulfate-Loaded Carboxylic Gelatin-Methacrylate Nanoparticles Promote Cardiac Repair by Activating Epicardial Epithelial-Mesenchymal Transition via Autophagy and the mTOR Pathway.

Restoring damaged myocardial tissue with therapeutic exogenous cells still has some limitations, such as immunological rejection, immature cardiac properties, risk of tumorigenicity, and a low cell survival rate in the ischemic myocardium microenvironment. Activating the endogenous stem cells with functional biomaterials might overcome these limitations. Research has highlighted the multiple differentiation potential of epicardial cells via epithelial-mesenchymal transition (EMT) in both heart development and cardiac regeneration. In our previous research, a carboxylic gelatin-methacrylate (carbox-GelMA) nanoparticle (NP) was fabricated to carry ammonium persulfate (APS), and APS-loaded carbox-GelMA NPs (NPs/APS) could drive the EMT of MCF-7 cells in vitro and promote cancer cell migration and invasion in vivo. The present study explored the roles of functional NPs/APS in the EMT of Wilms' tumor 1-positive (WT1+) epicardial cells and in the repair of myocardial infarction (MI). The WT1+ epicardial cells transformed into endothelial-like cells after being treated with NPs/APS in vitro, and the cardiac functions were improved significantly after injecting NPs/APS into the infarcted hearts in vivo. Furthermore, simultaneous activation of both autophagy and the mTOR pathway was confirmed during the NPs/APS-induced EMT process in WT1+ epicardial cells. Together, this study highlights the function of NPs/APS in the repair of MI.

Extraction of the cellulose nanocrystals via ammonium persulfate oxidation of beaten cellulose fibers.

The effect of beating starting pulp was investigated on the oxidation efficiency of ammonium persulfate (APS), the yield, and the properties of the CNCs. The beaten pulp and the subsequent CNCs were characterized, respectively, by different techniques. The CNCs were classified as CNC1 and CNC2, dependent on ultrasonication. It showed that the beating exposed more free OH groups in the pulp and enhanced the yield and surface charges of CNCs. Compared to the CNC2, the CNC1 had a higher surface charge, higher crystallinity, higher thermal stability, shorter length, smaller length distribution, and slightly larger width. The CNC1 and CNC2 had similar rheological properties. For the beaten pulp with a beating degree of 25°SR, the yields of the CNC1 and the total CNCs reached the maximum, 42.65 and 34.11 %, respectively. The surface charges of the CNC1 and the CNC2 also reached the maximum, -44.5 and - 33.6 mV, respectively. Their crystallinity indexes were 80.07 and 75.42 %, respectively. The lengths of the CNC1 and the CNC2 were 157.31 ± 30.61 and 214.92 ± 65.52 nm, and their widths were 10.13 ± 2.74 and 9.43 ± 2.99 nm, respectively. Therefore, proper beating enhanced the APS oxidation efficiency and influenced the CNCs properties.

Hydrophilic chitosan/graphene oxide composite sponge for rapid hemostasis and non-rebleeding removal.

Hydrophilic hemostatic sponge plays an important role in trauma bleeding control because of its robust coagulant functions. However, its strong tissue adhesion can easily result in wound tear and rebleeding during removing the sponge. Herein, the design of a hydrophilic anti-adhesive chitosan/graphene oxide composite sponge (CSAG) that possesses stable mechanical strength, rapid liquid absorption and strong intrinsic/extrinsic coagulation stimulations, is reported. For one thing, CSAG exhibits outstanding hemostatic performance, which significantly outperforms two commercial hemostats in two in vivo serious bleeding models. For another, CSAG shows low tissue adhesion; its peeling force is approximately 79.3 % lower than the commercial gauze. Moreover, in the peeling process, CSAG triggers partial detachment of the blood scab, because of the exist of bubbles or cavities at the interface, allowing the CSAG to be easily and safely peeled off from the wound without rebleeding. This study opens new avenues in constructing anti-adhesive trauma hemostatic materials.

An uncommon cause of swimmer's rash: Allergic contact dermatitis to persulfates in pools.

Allergic contact dermatitis (ACD) is an important diagnosis to consider in patients with dermatitis following specific exposures. Classically, ACD from persulfates is associated with hair-bleaching products and spa water/swimming pool exposure and is most commonly reported in adult men. We report a case of ACD to potassium peroxymonopersulfate (PPMS), a common pool "shocking" chemical, in a 7-year-old boy presenting with recurrent and diffuse dermatitis triggered by swimming pool exposure.

Production of cellulose nanocrystals extracted from Pennisetum purpureum fibers and its application as a lubricating additive in engine oil.

In the present work, cellulose nanocrystals (CNCs) were successfully produced from the Pennisetum purpureum (PP) fibers through ammonium persulfate (APS) oxidation. The effect of oxidation temperatures (60, 70, and 80 °C) on the properties of CNCs was characterized. In addition, the influence of CNCs addition (0, 0.05, 0.1, and 0.2 wt%) on the lubrication properties of the base oil SAE 40 lubricant was also investigated. The characteristics of the CNCs were determined by using FT-IR, XRD, TEM, and TGA. The lubrication properties were evaluated using kinematic viscosity and viscosity index measurements. The optimal oxidation temperature was found at 60 °C which resulted in the needle-shaped CNCs particles with high crystallinity (66.56%), an average diameter (15 nm), and an average length (79 nm). The resulting CNCs exhibited higher thermal stability than the PP fibers. Both kinematic viscosity and viscosity index did not significantly change by increasing the CNCs contents. However, a slightly higher viscosity index was exhibited for 0.2 wt% CNCs compared to that of neat base oil SAE 40. The CNCs obtained had high potential as a reinforcing agent of nanocomposites and also as a bio-lubricating additive in engine oil.

Influence of the Poly(ethylene Glycol) Methyl Ether Methacrylates on the Selected Physicochemical Properties of Thermally Sensitive Polymeric Particles for Controlled Drug Delivery.

Thermosensitive copolymers P1-P5 of N-isopropylacrylamide (NIPA) and poly(ethylene glycol) methyl ether methacrylates (PEGMEMs) were synthesized via surfactant-free precipitation polymerization (SFPP) using ammonium persulfate (APS) at 70 °C. The polymerization course was evaluated by the conductivity. The hydrodynamic diameters and the polydispersity indexes (PDI) of P1-P5 in the 18-45 °C range, which were assessed via dynamic light scattering (DLS), were at 18° (nm): 26.07 ± 0.54 (PDI 0.65 ± 0.03), 68.00 ± 1.10 (PDI 0.56 ± 0,02), 45.12 ± 0.57 (PDI 0.51 ± 0.03), 62.78 ± 0.40 (PDI 0.53 ± 0.003), and 92.95 ± 1.56 (PDI 0.60 ± 0.04), respectively. The lower critical solution temperatures ranged from 31 to 33 °C. The electrophoretic mobilities estimated the zeta potential in the 18-45 °C range, and at 18 °C, they were (mV): -4.64 ± 1.30, -6.91 ± 2.67, -5.85 ± 3.17, -2.28 ± 0.30, and -3.60 ± 0.96 for P1-P5, respectively. The polymers were characterized by Attenuated Total Reflectance Fourier-Transform Infrared spectroscopy (ATR-FTIR), H nuclear magnetic resonance (1H NMR), thermogravimetric analysis (TGA/DTA), Differential Scanning Calorimetry (DSC), and powder X-ray diffraction analysis (PXRD). Stable amorphous polymers were obtained. We conclude that the length of the co-monomer chain nonlinearly influences the properties of the obtained thermosensitive polymer nanostructures.

Carboxymethyl cellulose assisted polyaniline in conductive hydrogels for high-performance self-powered strain sensors.

Engineering high mass electroactive materials into hydrogel scaffolds remains an enormous challenge in achieving flexible energy storage devices. Herein, carboxymethyl cellulose (CMC) assisted high mass polyaniline (PANI) into an interpenetrating double-network polyethyleneimine/polyacrylamide (PEI/PAAM) hydrogel was developed. With the optimum mass loading of PANI at 9.04 mg/cm2, the all-in-gel CMC-PANI0.8M/PEI/PAAM supercapacitor can deliver a high specific capacitance of 679 mF/cm2, a maximum energy density of 58.82 µWh/cm2 at a power density of 14.69 mW/cm2, and an enhanced capacitance retention of 98 % after 5000 cycles. Such device can withstand severely bending/compressing deformations and operate properly at extreme temperatures (-30-70 °C). The CMC-PANI0.8M/PEI/PAAM hydrogel exhibits high sensitivity and stable electrical performance for wearable strain sensors. By connecting the supercapacitor with the strain sensor, the fabricated self-powered sensing system is capable of monitoring human activities accurately. Therefore, the multifunctional performance of the CMC-PANI0.8M/PEI/PAAM hydrogel is competent in the field of flexible electronics.

Dual-network polyacrylamide/carboxymethyl chitosan-grafted-polyaniline conductive hydrogels for wearable strain sensors.

Conductive, wearable, and flexible hydrogel-based sensors are considered as promising applications in human motion detection and physiological signal monitoring. However, it is still a problem to integrate multiple functions into one material for the next-generation smart devices. Herein, we fabricated an ionic/electronic dual conductive hydrogel by combining the chemically crosslinked polyacrylamide (PAM) and the physically crosslinked carboxymethyl chitosan-grafted-polyaniline (CMCS-g-PANI)/Ag+ network. The double-network hydrogel displays a high stretchability, repeatable adhesiveness, antibacterial activities, and biocompatibility. It also has high sensitivity and stable electrical performance for wearable strain sensors. Furthermore, we assembled a self-powered strain sensor based on the conversion of chemical energy to electrical energy. It can be used for human motion detection even without external power supply. This work provides an avenue for the development of multifunctional hydrogels with outstanding mechanical and electronic performances for application in wearable electronic devices.

Respiratory afflictions during hairdressing jobs: case history and clinical evaluation of a large symptomatic case series.

OBJECTIVES: Respiratory symptoms at work are common among hairdressers. Various working materials, most notably bleaching ingredients such as ammonium persulfate, have been made responsible. The objective of this study is to achieve a better understanding of work-related respiratory symptoms of hairdressers by describing common features in a large affected collective. METHODS: One hundred forty-eight hairdressers with respiratory symptoms at work presenting between 2012 and 2019 were consecutively included in a case series. Anamnestic and diagnostic data including pulmonary function and allergy testing were retrospectively compiled from records and analysed. Additionally, cases were categorised in five groups with respect to occupational causation certainty. RESULTS: 30% of the predominantly female collective had changed jobs or were on longer sick-leave. Besides respiratory symptoms, 10% also reported contact urticaria to blonde dyes. In 60% an obstructive airway disease was confirmed. A specific hypersensitivity reaction to ammonium persulfate was found in 15%. Group 1 with a proven immunological occupational causation showed significantly lower age (p < 0.001) and tenure time (p = 0.001), higher sensitization rates against environmental allergens as well as a higher total IgE (p = 0.015), compared to group 4 (obstructive airway disease, specific occupational causation unlikely). CONCLUSIONS: This case series contributes to a better characterization of work-related respiratory symptoms in hairdressing as one of the largest examined collectives of symptomatic hairdressers. Ammonium persulfate as the most common specific cause showed signs of a type-I-like hypersensitivity reaction with typical risk factors for atopy. Prick testing is recommended in all symptomatic cases. However, a specific occupational causation often cannot be proved.

Extraction of carboxylated nanocellulose from oat husk: Characterization, surface modification and in vitro evaluation of indomethacin drug release.

In this work, the extraction of carboxylated nanocrystalline cellulose from oat husk as an agricultural waste was conducted by ammonium persulfate oxidation. This is a one-step and efficient process for removal of amorphous regions from cellulosic fibers. The mean size of cellulose nanoparticles is about 30 nm with spherical morphology. The comparison of the infrared spectrum of the nanoparticles of cellulose and the primary oat husk evidences the successful elimination of non-cellulosic structures such as hemicellulose, lignin in nanocellulose sample. The X-ray diffraction patterns show higher degree of crystalline index in nanocellulose (57%) compared to the primary oat husk (38%). The comparison of the onsets of temperature degradation of the samples shows nanocellulose is less thermally stable than oat husk. The hydrophilic surface of the nanocellulose was modified using cetyltrimethylammonium bromide (CTAB) cationic surfactant to improve loading capacity of hydrophobic indomethacin drug which has a low bioavailability and poor solubility in water. In vitro release profile of the indomethacin and drug release mechanism was studied. The results show the 67% of drug is released within 12 h and CTAB modified nanocellulose greatly acts as an indomethacin controlled-release carrier. Study of the in vitro drug release kinetics shows driven mechanism is diffusion-controlled release.

A hydrogel spinal dural patch with potential anti-inflammatory, pain relieving and antibacterial effects.

CSFL caused by spinal dural defect is a common complication of spinal surgery, which need repair such as suture or sealants. However, low intracranial pressure symptoms, wound infection and prolonged hospital associated with pin-hole leakage or loose seal effect were often occurred after surgical suture or sealants repair. Stable, pressure resistance and high viscosity spinal dural repair patch in wet environment without suture or sealants was highly needed. Herein, a bioactive patch composed of alginate and polyacrylamide hydrogel matrix cross-linked by calcium ions, and chitosan adhesive was proposed. This fabricated patch exhibits the capabilities of promoting defect closure and good tight seal ability with the bursting pressure is more than 790 mm H2O in wet environment. In addition, the chitosan adhesive layer of the patch could inhibit the growth of bacterial in vitro, which is meaningful for the postoperative infection. Furthermore, the patch also significantly reduced the expression of GFAP, IBA-1, MBP, TNF-α, and COX-2 in early postoperative period in vivo study, exerting the effects of anti-inflammatory, analgesic and adhesion prevention. Thus, the bioactive patch expected to be applied in spinal dural repair with the good properties of withstanding high pressure, promoting defect closure and inhibiting postoperative infection.

Ammonium persulfate treatment on carbohydrate polymers and lignin of wood improved sound absorption capacity.

The rational design of sound absorption boards made of wood materials is an exciting area of research. This article describes a simple and inexpensive method to increase the sound absorptions capacity of Malas hardwood (Homalium foetidum Roxb.) using ammonium persulfate treatment. The reaction parameters such as the concentration of ammonium persulfate and reaction time were optimized. The results of X-ray photoelectron spectroscopy, X-ray diffraction, attenuated total reflectance-Fourier transforms infrared spectroscopy, and scanning electron microscopy demonstrated that ammonium persulfate could significantly affect carbohydrate polymers and lignin of wood by improving oxygen functionalities. The quantitative analysis of carbohydrate polymers (hemicellulose and cellulose) and lignin were evaluated. These changes in carbohydrate polymers and lignin enhanced the air permeability (83.6%) and average sound absorption coefficient at each frequency range 500-1000 Hz (2.6%), 1000-2000 Hz (4.9%), 2000-4000 Hz (17.4%), and overall 500-6400 Hz (20.8%) compared to the control samples. These results could be beneficial for new research and wood-based sound absorption materials to regulate the acoustic environment in houses.

Patch testing with ammonium persulfate: The North American Contact Dermatitis Group Experience, 2015-2018.

BACKGROUND: Ammonium persulfate (APS), an oxidizing agent used in hair products, manufacturing, and pool/spa water, can cause skin reactions, including allergic contact dermatitis. OBJECTIVE: To characterize positive patch test reactions to APS (2.5% petrolatum). METHODS: Retrospective analysis of patients tested to the North American Contact Dermatitis Group screening series from 2015 to 2018. RESULTS: Of 10,526 patients, 193 (1.8%) had positive patch test reactions to APS. Compared with APS-negative patients, APS-positive patients were significantly more likely to be male (43.2% vs 28.0%; P < .0001); have primary hand dermatitis (30.2% vs 22.0%; P = .0064), scattered generalized dermatitis (25.5% vs 17.9%; P = .0064), or trunk dermatitis (8.9% vs 4.9%; P = .0123); and have dermatitis that is occupationally related (22.2% vs 10.9%; P < .0001). More than half of the APS-positive reactions were currently relevant (57.0%); 19 (9.8%) were related to occupation, especially hairdressers (68.4%). Swimming pools/spas (23.3%) and hair care products (19.2%) were the most common sources of APS. LIMITATIONS: Immediate reactions and follow-up testing were not captured. CONCLUSION: The proportion of patients positive to APS was 1.8%. APS positivity was significantly associated with male sex and hand dermatitis. Swimming pool/spa chemicals were important sources of APS exposure.