Magnetic Fe3O4 embedded chitosan-crosslinked-polyacrylamide composites with enhanced removal of food dye: Characterization, adsorption and mechanism

The water solubility in acid solution, relative low adsorption capacities and unsatisfactory separation performance limit application of traditional chitosan-based adsorbents in wastewater treatment. To break the limitation, a hydrophilic magnetic Fe₃O₄ embedded chitosan-crosslinked-polyacrylamide composites (abbreviated as m-CS-c-PAM) were prepared by a two-step method. The m-CS-c-PAM composites were systematically characterized using SEM, XRD, FTIR, VSM, TGA and BET. Sunset yellow (SY) was selected as model food dye to investigate adsorption kinetics and thermodynamic parameters of food dye adsorption onto m-CS-c-PAM. Compared with magnetic Fe₃O₄/chitosan, m-CS-c-PAM can adapt to a wider range of pH (2-10) and resist the presence of inorganic salts. m-CS-c-PAM was proved to have high adsorption capacity (359.71 mg g^-1) for SY dye at 298 K, much higher than magnetic Fe₃O₄/chitosan and many reported adsorbents. Moreover, m-CS-c-PAM could be rapidly and efficiently separated from treated solution within 15 s by an external magnet and regenerated by NaOH solution. With its excellent adsorption capacity, pH-independent adsorption capability for food dye, easy and convenient separation ability, satisfactory reusability, m-CS-c-PAM can be a promising material for food wastewater treatment.

Photoresponsive Hydrogels for Studying Mechanotransduction of Cells

Hydrogels are important platform materials for in vitro cellular studies. Mechanistic studies on durotaxis, the directional movement of a cell affected by a spatial gradient of stiffness of the underlying substrate, requires materials such as polyacrylamide, polyethylene glycol, or PDMS, in which the stiffness can be controlled in a spatiotemporal manner. Here, we describe the synthesis of an o-nitrobenzyl-based photocleavable cross-linker and its incorporation into a polyacrylamide hydrogel to render it photoresponsive. Precise control over the physical properties of the gel allows observation of glioblastoma durotaxis under surface stiffness conditions relevant to the actual brain environment.

Silk fibroin based interpenetrating network hydrogel for corneal stromal regeneration

There is a need to develop tissue engineering based approaches to address the shortage of donor corneas worldwide for transplantation. To do this a novel approach to fabricate three-dimensional hydrogels using free-radical polymerization was investigated to generate constructs for corneal stromal tissue regeneration. Different ratios of silk fibroin (SF) to polyacrylamide (PA) were used to fabricate semi-interpenetrating hydrogels. Scanning electron micrograph displayed the interconnectivity of pores within the fabricated hydrogels. Pore sizes ranged from 25 to 66 μm. Scaffolds with increasing concentration of SF had enhanced β-sheet structure (verified by Fourier transform infrared spectroscopy). The biological response of human corneal stromal cells to these hydrogels was examined using cellular adhesion, proliferation, cytoskeleton organization, gene expression and immunocytochemical analysis. The fabricated hydrogels possess rapid gelation (∼3 min) at 37 °C, 84 % porosity facilitating keratocyte migration during healing, improved cellular adhesion and no cytotoxicity, indicating their efficiency for in-situ corneal tissue regeneration. Presence of SF in semi-interpenetrating network hydrogel enhanced cellular proliferation, elevated GAG deposition, and increased expression of keratocyte genes, normally associated with healthy corneal stromal tissue. This study acts as an initial step towards fabricating SF based semi-interpenetrating network hydrogels for developing clinically applicable ocular implants.

Comparison of physical, mechanical and biological effects of leucocyte-PRF and advanced-PRF on polyacrylamide nanofiber wound dressings: In vitro and in vivo evaluations

Platelet-rich fibrin (PRF) is extracted from the blood without biochemical interference and, also, with the ability of a long-term release of growth factors that can stimulate tissue repair and regerenation. Here, leucocyte- and platelet-rich fibrin (L-PRF) and advanced platelet-rich fibrin (A-PRF) were extracted and utilized for the creation of nanofibers containing polyacrylamide (PAAm), PAAm / L-PRF and PAAm / A-PRP through electrospinning processing technique. The effect of the type of PRF on the physical, mechanical and biological properties of the resultant nanofiberous wound dressings are thoroughly evaluated. The results presented in the current study reveals that the fiber diameter is grealtly reduced through the utilization of L-PRF. In addition, mechanical property is also positively affected by L-PRF and the degradation rate is found to be higher compared to A-PRF group. The L929 cells proliferation and adhesion, angiogenesis potential and wound healing ability was significantly higher in PAAm/A-PRF nanofibers compared to pure PAAm and PAAm/L-PRF nanofibers owed to the release of vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF). Overall, the utilization of L-PRF or A-PRF can improve the physical, mechanical and biological behavior of nanofiber making them an ideal candidate for wound dressings, with the emphasis on the skin tissue repair and regeneration applications.

Enhancement of soil physical properties and soil water retention with biochar-based soil amendments

The soil physical properties are deteriorating due to changing rainfall patterns and intensities, as well as climate change-induced temperature fluctuations. Pot experiments were carried out to examine the impacts of synthesized soil amendments on soil water retention and plant growth. Soil amendments (biochar, polyacrylamide (PAM), and moringa) were used at different rates (0 (control), 2.1, 4.2, and 8.3 g kg^-1) to improve the physical properties of the soil. As a result of soil amendment application, it was found that the mean weight diameter of soil aggregate increased by 188% during the 8.3 g kg^-1 treatment, forming stable soil particles. Soil water retention improved by up to 128.9% during the 8.3 g kg^-1 treatment, and it was analyzed that it was due to the high surface area of biochar, porosity, and high molecular weight of PAM. Pellet treatment increased all plant growth parameters (height, stem diameter, leaf number, and fresh and dry weight) for both beans and maize. The dry weight of beans (C₃ plant) and maize (C₄ plant) increased by 92.9 and 146.4%, respectively in an 8.3 g kg^-1 pot. The soil physical condition was stabilized by the high carbon content of biochar and the improvement of soil coagulation between PAM and moringa. This had a positive effect on the C₄ plant. The findings of this study indicate that if the soil amendments are properly mixed and applied based, they will improve soil stability and plant productivity.

Ultrastretchable and adhesive agarose/Ti3C2Tx-crosslinked-polyacrylamide double-network hydrogel for strain sensor

A novel agarose/Ti₃C₂T_x-crosslinked-polyacrylamide (AG/T-PAM) double-network (DN) hydrogel is synthesized by combining heating-cooling and γ-ray radiation-induced polymerization. The AG/T-PAM DN hydrogel possesses excellent mechanical properties with 4250% stretchability, and good adhesion to different substrates, such as an adhesive strength of 1148 kPa to copper at 30 °C. The resultant hydrogel also exhibits excellent tensile and compression sensing properties due to the variation of conductive network within hydrogel. The flexible and wearable strain sensor composed of the AG/T-PAM DN hydrogel presents rapid response to strain withstand 1000 cycles, and can monitor various movements of human body with a high sensibility. The AG/T-PAM DN hydrogel-based strain sensor will have broad application in large-scale strain detection scenarios requiring high sensitivity and adhesion.

Enhanced precipitation performance for treating high-phosphorus wastewater using novel magnetic seeds from coal fly ash

Magnetic coagulation is a promising approach for treating high phosphorous (high-P) wastewater by enhancing precipitation efficiency using magnetic particles. In this study, a cost-effective and environmentally friendly magnetic seed from coal fly ash (MS-CFA) was used as an alternative material for Fe₃O₄ magnetic seed (MS) coagulation. The potential effect of MS-CFA was explored to reduce the settling time and the dosage of coagulant aid of polyacrylamide (PAM) in treating high-phosphorous (high-P) simulated wastewater at 100 and 200 mg P/L. The physicochemical characteristics of MS-CFA were analysed through particle size distribution (20-100 μm), pore size distribution (14-30 nm), specific surface area (1.654 m²/g), X-ray diffraction (XRD), specific gravity (4.2), and magnetic induction intensity (49.8 emu/g). The characteristics met the requirements as magnetic coagulation material. MS-CFA was combined with polyaluminum chloride (PAC) and polyacrylamide (PAM) to improve phosphorous precipitation performance. The synergised magnetic coagulation effect using MS-CFA and PAM reduced the settling time of flocs to less than 1 min due to the high specific gravity. This represents a reduction of 90% of the settling time compared to the control using PAM alone (15 min) without MS-CFA. MS-CFA efficiently reduced PAM dosage by 83% and 87% for treating 100 and 200 mg P/L, respectively. The presence of PAM (1 mg/L for 100 mg P/L and 2 mg/L for 200 mg P/L) was imperative for binding the MS-CFA and flocs, hence increasing the particle size of the magnetic flocs. The characteristics of the magnetic flocs were analysed through microscopy, particle size distribution, zeta potential measurements, and magnetic induction intensity. The characteristics of the magnetic flocs confirmed that MS-CFA could be an alternative material for Fe₃O₄ as the magnetic seeds in the magnetic coagulation process for treating high-P wastewater.

Hypoxemia as the mechanism of acute cationic polymer toxicity in rainbow trout and prevention of toxicity using an anionic neutralizing polymer

Industrial operations such as surface mining, road building, and aggregate washing result in high concentrations of suspended particles (Total Suspended Solids; TSS) in surface waters which must be treated prior to discharge into fish-bearing waters. A common industrial practice is to add flocculants to improve the efficacy and speed of TSS sedimentation. A significant environmental issue even small amounts of uncomplexed cationic polymer coagulant/flocculant remaining in treated water is highly toxic to fish at very low concentrations (LC₅₀ ∼ 0.3 mg L^-1). Fingerling trout (Oncorhynchus mykiss) were exposed to (1) a cationic flocculant (Water Lynx 800 (WL800), (2) a Clearflow neutralizing polymer (CN369), and (3) a combination of WL800 and CN369 at various ratios with measured LC₅₀ as an index of toxicity. Acute toxicity was entirely reversed by addition of the neutralizing polymer at WL800:CN369 ratios >1:1.5 mg/L. Furthermore, we demonstrate that the proximal mechanism of acute cationic polymer toxicity is hypoxemia due to accumulation of polymer on the gill epithelia rather than gill damage. Exposure of 0.5 mg/L WL800 reduced oxygen consumption by >50% reduction by 12 h and this was accompanied by significantly increased blood, brain, and liver [lactate] and [glucose]. The development of an inexpensive amelioration technique preventing cationic polymer toxicity is a significant advancement in surface and industrial water treatment to prevent cationic polymer mediated fish kills.

Photoacoustic imaging phantoms for assessment of object detectability and boundary buildup artifacts

Standardized phantoms and test methods are needed to accelerate clinical translation of emerging photoacoustic imaging (PAI) devices. Evaluating object detectability in PAI is challenging due to variations in target morphology and artifacts including boundary buildup. Here we introduce breast fat and parenchyma tissue-mimicking materials based on emulsions of silicone oil and ethylene glycol in polyacrylamide hydrogel. 3D-printed molds were used to fabricate solid target inclusions that produced more filled-in appearance than traditional PAI phantoms. Phantoms were used to assess understudied image quality characteristics (IQCs) of three PAI systems. Object detectability was characterized vs. target diameter, absorption coefficient, and depth. Boundary buildup was quantified by target core/boundary ratio, which was higher in transducers with lower center frequency. Target diameter measurement accuracy was also size-dependent and improved with increasing transducer frequency. These phantoms enable evaluation of multiple key IQCs and may support development of comprehensive standardized test methods for PAI devices.

Preparation and characterization of multi-network hydrogels based on sodium alginate/krill protein/polyacrylamide-Strength, shape memory, conductivity and biocompatibility

Sodium alginate/krill protein/polyacrylamide (SA/AKP/PAM) hydrogel with "covalent bond-ion complex-hydrogen bond" multi-network structure was prepared by covalent cross-linking and complexion ion crosslinking using SA, AKP, and acrylamide (AM) as raw materials. The effects of ion species (Fe³⁺, Ba²⁺, Sr²⁺, Ca²⁺, and Zn²⁺) on the structure, morphology, and properties of multi-network hydrogels were studied in detail. The results showed that the mechanical strength of ionic cross-linked hydrogels increased significantly. The compressive strength of Fe³⁺ cross-linked hydrogels was 5.56 MPa, 16.13 times that of non-ionic crosslinked hydrogels. The results of ionic conductivity measurements showed that hydrogels had significant ionic conductivity and were sensitive to external forces. Interestingly, the hydrogel can be used as a capacitive pen in mobile phone writing, painting and dialing numbers. Moreover, ionic cross-linked hydrogels had a unique three-dimensional porous structure with gradient distribution, excellent shape memory effect, and good biocompatibility. Fe³⁺, Ba²⁺, Sr²⁺, and Ca²⁺ cross-linked hydrogels were nontoxic and conducive to the adhesion and growth of Schwann cells. These excellent properties of ionic cross-linked SA/AKP/PAM hydrogels have broad applications prospects in flexible electronic devices, sensors, soft electronic skins, and tissue engineering.

Optimizing treatment of alcohol vinasse using a combination of advanced oxidation with porous α-Fe2O3 nanoparticles and coagulation-flocculation

This study utilizes a novel method, namely the combination of advanced oxidation processes with synthesized highly porous α-Fe2O3 nanoparticles and coagulation-flocculation with polyacrylamide, to investigate the effects on COD removal in alcohol vinasse. Highly porous α-Fe2O3 nanoparticles were prepared via a chemical precipitation technique. The characteristic of the synthesized α-Fe2O3 nanoparticles were determined by FT-IR, Raman spectroscopy, XRD, SEM, and N2 adsorption-desorption isotherms. The effect of different α-Fe2O3 nanoparticles loading for chemical oxygen demand (COD) removal efficiency was investigated. The results revealed that at α-Fe2O3 nanoparticle dose of 3000 ppm had the highest COD removal for vinasse. Then, central composite design (CCD) was used to optimize the operating variables such as pH, time, oxidant dosage, and coagulant dosage, and their optimum values were determined to be pH:7.36, 90 min, 17.89 wt% oxidant dosage, and 1.6 wt% coagulant dosage, to achieve a high COD removal efficiency in 70 ℃ for alcohol vinasse (98.64%). Based on optimal conditions, the porous α-Fe2O3 nanoparticles possess superior catalytic activity in the advanced oxidation process compared to other treating methods. Also, the mechanism of the catalytic oxidation reaction is evaluated.

Comparing pH-responsive nanogel swelling in dispersion and inside a polyacrylamide gel using photoluminescence spectroscopy and small-angle neutron scattering

Nanosized probes that report their changes in dimensions within networks in response to environmental stimuli are potentially important for applications such as drug delivery, load-supporting hydrogels and soft robotics. Recently, we developed a fluorescent pH-responsive nanogel (NG) that used Förster-resonance energy transfer (FRET) to report changes in the probe separation and NG swelling within hydrogels using photoluminescence (PL) spectroscopy. However, FRET cannot measure nanoparticle dimensions and is subject to artefacts. Here, we report the use of small-angle neutron scattering (SANS) to study both the NGs in dispersion and in polyacrylamide (PAAm) gels as a function of pH. We compare the PL and SANS data for both systems and as a function of pH. The SANS data for the dispersed NGs indicate that they have a core-shell structure with a swollen mesh size of ∼1.0 nm. We hypothesized that the NGs inside the PAAm gel would show the same general changes in scattering as the pH is increased, as observed for the dispersed NGs, and this is confirmed by the data. In summary, the data confirm that PL is a suitable (accessible) method for reporting internal environmental changes within gels using NG probes.

Lignin grafted hydroxyapatite entrapped in polyacrylamide: Characterization and adsorptive features for Th4+ and bovine serum albumin

Water-soluble sulfolignin (SL) was grafted onto hydroxyapatite (Hap) by using epichlorohydrin. SLgHap was then entrapped in cross-linked polyacrylamide by in situ polymerizations of acrylamide and N, N'-methylenebisacrylamide to obtain the composite of PSLgHap. The composite was characterized by FT-IR, BET- porosity, XRD, EDXRF, SEM-EDX, TGA-DTG, PZC, CEC, and swelling tests. The adsorptive features of PSLgHAP were investigated for Th⁴⁺ and BSA in view of its dependence on pH, ionic intensity, concentration, temperature, and time. The results of characterization tests confirmed the formation of PSLgHap. The grafting efficiency concerning sulfur contents of PSLgHap was 96% by EDXRF. The isotherms were best represented by the Sips model, Langmuir adsorption capacities were 369 and 390 mg g_SLgHap^-1 for BSA and Th⁴⁺. The enthalpy and entropy changes were positive whilst Gibbs energy was negative by entropy controlled. The adsorption kinetics of both species was obeyed to pseudo second-order model, whereas it was first-order for BSA and hybrid-order for Th⁴⁺ of Langmuir model.

Surface rainfall erosion resistance and freeze-thaw durability of bio-cemented and polymer-modified loess slopes

Microbially induced calcite precipitation (MICP) has been shown to mitigate sand erosion; however, few studies have applied MICP on loess soils. In this study, polyacrylamide (PAM) was added to the cementation solution, and combined MICP-PAM treatment was applied to improve the surface erosion resistance of loess-slopes. The freeze-thaw (FT) durability of MICP-PAM treated loess slopes was also studied. The obtained results showed that MICP-PAM treatment improved erosion resistance and addition of 1.5 g/L PAM achieved the best erosion control and highest surface strength. The high erosion resistance of MICP-PAM treated slopes could be attributed to the stable spatial structure of precipitation, and PAM addition conveyed stronger resistance to tension or shear force. With increasing number of FT cycles, the surface strength of MICP-PAM treated loess slopes decreased; however, slopes subjected to 12 FT cycles still only lost little soil. In MICP-PAM treated loess slopes, cracks and pores evolved with increasing number of FT cycles. With increasing number of FT cycles, porosity and fractal dimension increased, pore ellipticity decreased slightly, and the percentage of various pores changed slightly. The number of FT cycles had less effect on MICP-PAM treated loess slopes than on untreated slopes. MICP-PAM treatment significantly mitigated surface erosion of loess-slopes and improved FT weathering resistance, thus presenting promising potential for application in the field. In addition, based on the linear correlations between surface strength and rainfall-erosion resistance, surface strength could be measured to evaluate the rainfall-erosion resistance for MICP-PAM treated slopes in practical engineering applications.

Effects of cellulose nanofibrils and starch compared with polyacrylamide on fundamental properties of pulp and paper

Bio-based additives received significant attention in pulp and paper properties improvement. For this, the most cited biochemical Cellulose Nano Fibrils (CNFs) and Cationic Starch (CS) were experimentally compared with the most declared synthetic chemical, Cationic Polyacrylamide (CPAM). SEM images showed better paper surface filling by the utilization of the chemicals. The three studied polymers, in solely or combination mechanism, improved mainly bagasse pulp and paper properties compared to the blank sample, except for pulp drainage, which decreased by CNFs to lower volumes presumably due to its intrinsic characteristics. Cationic polymers (CP) compared to CP/CNFs approaches increased pulp retention and drainage but decreased paper density and strengths. The best pulp retention and drainage achieved by CS followed by CPAM, while paper air persistency, density, and strength properties evaluated highest by CP/CNFs followed by CNFs. Generally, CS revealed a more significant improvement in pulp and paper properties than CPAM either with or without CNFs.

A Double-Blinded Positive Control Study Comparing the Relative Efficacy of 2.5% Polyacrylamide Hydrogel (PAAG) Against Triamcinolone Acetonide (TA) And Sodium Hyaluronate (HA) in the Management of Middle Carpal Joint Lameness in Racing Thoroughbreds

The purpose of this prospective double-blinded positive control study was to compare the efficacy of 2.5% polyacrylamide hydrogel (2.5% PAAG) in the management of middle carpal joint lameness in Thoroughbreds against treatments of triamcinolone acetonide (TA) or sodium hyaluronate (HA). A total of 31 flat-racing Thoroughbreds with lameness (grade 1-3/5) localized to the carpus by intra-articular analgesia were selected. Following a radiological assessment of the carpi confirming the absence of fragment/fracture, the horses were randomly assigned for intra-articular treatment with either 2 ml of 2.5% PAAG, 12 mg TA or 20 mg HA (followed by two further intravenous treatments of 40 mg, at weekly intervals in the HA group only), by a treating veterinarian. All horses were rested for 48 hours post-treatment and then re-entered an unaltered training regimen. Subsequent examinations at 2, 4, and 6 weeks were performed by a blinded examining veterinarian for all groups, while horses treated with 2.5% PAAG were monitored for 12 weeks for recurrence of lameness. Significantly more joints treated with 2.5% PAAG were lame free (83%) at 6 weeks compared to TA (27%; P = .007) and to HA (40%; P = .04). There was no significant difference between TA and HA groups at any time. All the joints treated within 2.5% PAAG that were lame free at 6 weeks (10/12) were still lame-free at 12 weeks. In conclusion, treatment with 2.5% PAAG led to statistically superior results compared to TA and HA in the management of selected middle carpal joint lameness in flat-racing Thoroughbreds, with therapeutic effects persisting up to 12 weeks.

Improvement of palmoplantar pustulosis after excision of polyacrylamide injected into the nasal region

We report a patient in whom polyacrylamide hydrogel injected into the nasal region caused palmoplantar pustulosis. We report this case because few cases of autoimmune syndrome induced by adjuvants caused by polyacrylamide have been reported.

RNA electroelution: Comparing two electroeluter models

RNA represents a vibrant area of research and many studies use techniques that require large amounts of purified RNA. One common purification method involves slicing a section of a polyacrylamide gel containing the RNA of interest and eluting the RNA out of the gel using electroelution. Various electroeluter models are available but sometimes a given model becomes discontinued, compelling researchers to choose a different model. Here, we have compared two electroeluters with different chamber designs for their ability to recover RNA from gel pieces. Our results show that both electroeluters are effective and recover comparable amounts of purified RNA.

A Novel Method to Make Polyacrylamide Gels with Mechanical Properties Resembling those of Biological Tissues

Studies characterizing how cells respond to the mechanical properties of their environment have been enabled by the use of soft elastomers and hydrogels as substrates for cell culture. A limitation of most such substrates is that, although their elastic properties can be accurately controlled, their viscous properties cannot, and cells respond to both elasticity and viscosity in the extracellular material to which they bind. Some approaches to endow soft substrates with viscosity as well as elasticity are based on coupling static and dynamic crosslinks in series within polymer networks or forming gels with a combination of sparse chemical crosslinks and steric entanglements. These materials form viscoelastic fluids that have revealed significant effects of viscous dissipation on cell function; however, they do not completely capture the mechanical features of soft solid tissues. In this report, we describe a method to make viscoelastic solids that more closely mimic some soft tissues using a combination of crosslinked networks and entrapped linear polymers. Both the elastic and viscous moduli of these substrates can be altered separately, and methods to attach cells to either the elastic or the viscous part of the network are described. Graphic abstract: Polyacrylamide gels with independently controlled elasticity and viscosity.

Efficient degradation of polyacrylamide using a 3-dimensional ultra-thin SnO2-Sb coated electrode

Polyacrylamide (PAM) is widely used in polymer flooding processes to increase oil recovery while the byproduct of PAM-containing wastewater is a serious environmental issue. In this study, electrochemical oxidation process (EAOP) was applied for treating PAM wastewater using a new type of 3-dimensional ultra-thin SnO₂-Sb electrode. Nano-sized catalysts were evenly dispersed both on the surface and inside of a porous Ti filter forming nano-thickness catalytic layer that enhances the utilization and bonding of catalysts. This porous Ti electrode showed 20% improved OH· production and 16.3 times increased accelerated service life than the planar Ti electrode. Using this electrode to treat 100 mg L^-1 PAM, the TOC removal efficiency reached over 99% within 3 h under current density of 20 mA cm^-2. The EAOP could fastly break the long-chain PAM molecules into small molecular intermediates. With the porous electrode treating 5 g L^-1 PAM under current density of 30 mA cm^-2, EAOP reduced 94.2% of average molecular weight in 1 h and 92.0% of solution viscosity in 0.5 h. Moreover, the biodegradability of PAM solution was significantly improved as the solution BOD₅/COD ratio raised from 0.05 to 0.41 after 4 h treatment. The degradation pathway of PAM was also investigated.

Does polyacrylamide-based adjuvant actually reduce primary drift of airborne pesticides?

Atmospheric drift of pesticides sprayed outside treated fields may pose serious environmental and health concerns. Chemical adjuvants, among other techniques, reduce drift by modifying the physicochemical properties of the pesticide solution, which presumably produces larger droplets upon spraying that are less prone to drift. Previous studies, that have addressed the effect of adjuvants on drift reduction, mainly rely on measurements of droplet sedimentation while ignoring the presence of pesticides in the forms of small aerosols and vapor. Such forms are expected to be highly susceptible to atmospheric drift that may pose human health risk via inhalation exposure. The present study examines the effect of a polymer-based adjuvant on airborne-pesticide drift using active air sampling in two field campaigns. Surprisingly, these measurements indicate higher primary drift (PD) of airborne pesticides in the presence of adjuvant in the spraying solution. The results are further supported by comparing measured drifts to those calculated using a modified Gaussian puff dispersion model, which enabled to evaluate the impact of varying meteorological conditions during the field experiments. In addition, the adjuvant effect on droplet size distribution generated by common nozzles, was tested in a wind tunnel. The resulting size-distributions demonstrated that while the addition of adjuvant resulted in a desired shift of the volumetric distribution towards larger droplets, it also led to a significant increase in the number concentration of fine droplets. Such trends can explain how the addition of polymeric adjuvant can yield both, a reduction in sedimenting drift outside treated areas and an increase in airborne PD intensity, as observed in the present study. This study demonstrates the complex effect of chemical adjuvants and the urgent need to further explore and understand their environmental impact.

Periurethral injection with polyacrylamide after previous TVT surgery

INTRODUCTION AND HYPOTHESIS

The aim of this registry study was to assess the clinical utility of using periurethral bulking with polyacrylamide hydrogel in women with stress urinary incontinence (SUI) after previous midurethral sling surgery.

METHODS

The study period was 2007 through 2019. Using data from the Norwegian Female Incontinence Registry we included 57 women who had received Bulkamid® because of insufficient improvement or recurrent SUI after previous retropubic TVT surgery. The primary outcome was cure of SUI, and secondary outcomes were patient satisfaction, degree of leakage, change in urgency incontinence (UUI), free flow rate, postvoid residual volume, and complications. Descriptive statistics were used to characterize data and Wilcoxon signed-rank test to compare pre- and postoperative results for pairs, with level of significance at p < 0.05.

RESULTS

Pure SUI was seen in 19 (33.3%) while 38 (66.7%) had mixed incontinence. Postoperatively 72.9% had a negative stress test and 73.7% were satisfied with treatment. There was only 1 complication in 67 injections (1.5%). De novo UUI occurred in five patients, corresponding to 8.8% of the whole study group, but 26.3% among those with no preoperative UUI problems. Among the patients with preoperative UUI, 39.5% were cured of this problem and a further 36.8% were improved.

CONCLUSIONS

The cure rate and satisfaction rate of periurethral bulking with polyacrylamide after previous MUS are favorable and complications are rare. There seems to be a risk of overactive bladder symptoms developing in women with no such symptoms preoperatively.

Polyacrylamide hydrogel phantoms for performance evaluation of multispectral photoacoustic imaging systems

As photoacoustic imaging (PAI) begins to mature and undergo clinical translation, there is a need for well-validated, standardized performance test methods to support device development, quality control, and regulatory evaluation. Despite recent progress, current PAI phantoms may not adequately replicate tissue light and sound transport over the full range of optical wavelengths and acoustic frequencies employed by reported PAI devices. Here we introduce polyacrylamide (PAA) hydrogel as a candidate material for fabricating stable phantoms with well-characterized optical and acoustic properties that are biologically relevant over a broad range of system design parameters. We evaluated suitability of PAA phantoms for conducting image quality assessment of three PAI systems with substantially different operating parameters including two commercial systems and a custom system. Imaging results indicated that appropriately tuned PAA phantoms are useful tools for assessing and comparing PAI system image quality. These phantoms may also facilitate future standardization of performance test methodology.

Injection of Aquafilling® for Breast Augmentation Causes Inflammatory Responses Independent of Visible Symptoms

Background

A major concern related to modern surgery is to evaluate and address the complications associated with breast enlargement using Aquafilling^® injection. This study aimed to assess the effect of Aquafilling^® injection on immune response in such patients.

Methods

For four patients who consulted a surgeon after receiving Aquafilling^® injection, medical history of the patients was taken; based on imaging examinations, Aquafilling^® was removed. Samples were processed for histopathological and immunohistochemical examination. For detecting tissue antigens in histopathological samples, monoclonal antibodies against CD3 (lymphocytes T), CD 20 (lymphocytes B), and CD68 (macrophages) were used. By analyzing the images, the number of immune cells (lymphocytes T, lymphocytes B, and macrophages) and immunohistochemical reaction area were semiquantitatively evaluated.

Results

Different clinical features were observed in each patient after receiving Aquafilling^® injection. In samples obtained from four patients, lymphocytes T (CD3), lymphocytes B (CD20), and macrophages (CD68) tissue expressions were observed. Statistically significant variations in the number of lymphocytes B (CD20) and macrophages (CD68), and differentiation of immunohistochemical reaction area for lymphocytes T (CD3) and lymphocytes B (CD20) were observed.

Conclusions

Inflammation is elevated in patients who received Aquafilling^® injection. Medical imaging should be carried out in all such patients even if there are no visible symptoms. Removal of Aquafilling^® can reduce the inflammation and risk of neoplastic progression in the patients. The influence of time elapsed since Aquafilling^® injection and intensity of immune response requires further validation.

Level of Evidence IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Combination of biochar and immobilized bacteria accelerates polyacrylamide biodegradation in soil by both bio-augmentation and bio-stimulation strategies

Polyacrylamide (PAM) has been used extensively due to its well-known stable chemical properties, but limited information is available on the biodegradation of soil-containing PAM. In this work, sufficient degradation of PAM was achieved via the addition of the Klebsiella sp. PCX-biochar composite to PAM-containing soil, due to the synergic effect of bio-augmentation and bio-stimulation. The optimal degradation rate of 69.1% over 30-day period was observed under the following conditions: the addition of immobilized bacteria at 0.07 g/g, pH 6.6, and temperature at 38.0 °C. In this study, we showed that PAM was successfully hydrolyzed by amidase, and ammonia in the hydrolysis product was then oxidized by the nitrifying bacteria. The decrease of water-extractable organic carbon (WEOC) also demonstrated the chain cleavage in PAM. PAM was utilized as a carbon source not only by Klebsiella sp. PCX but also by some taxa from indigenous bacteria. Last but not least, it was shown in this study that biochar, even though immobilized with exogenous microorganisms, actually enhanced bacterial diversity and stimulated the growth of some indigenous PAM-degrading taxa. Based on the above observations, we concluded that PAM biodegradation via the addition of bacteria-immobilized biochar was a synergy of both bio-augmentation and bio-stimulation strategies.