Tetrakis Hydroxymethyl Phosphonium Chloride Research Articles

Elevated water transport of polyamide nanofiltration membranes via aqueous organophosphorus mediated interfacial polymerization

As interfacial polymerization (IP) is a reaction-diffusion process, rational regulation of diamine diffusion rate is effective to heighten the nanofiltration (NF) performance of polyamide (PA) membranes. Herein, we propose an aqueous organophosphorus-regulated IP strategy that promotes the formation of thinner and moderately crosslinked films toward improved water transport. Two similar compounds tetrakis (hydroxymethyl) phosphonium chloride (THPC) and tetrakis (hydroxymethyl) phosphonium sulfate (THPS) were utilized as functional additives to physically interact with piperazine via hydrogen bonding and thus retard piperazine diffusion rate during an IP process. The resultant polyamide membranes have been analyzed in terms of surface morphologies, chemical structures, hydrophilicity, and separation performance in detail. Surface temperature monitoring results revealed that heat release from regulated IP was less than that from unmodified IP, which was ascribed to retard monomer diffusion toward organic boundary in the presence of THPC or THPS. Molecular dynamics simulation further confirmed that the addition of THPC and THPS could efficiently decline the monomer diffusion rate via hydrogen bonds and increased solution viscosity. The modified PA membranes exhibited a reduced film thickness, moderate crosslinking degree, as well as increased average pore size, as revealed by a series of characterizations. Furthermore, the incorporation of THPC or THPS resulted the PA membranes with higher surface hydrophilicity and stronger negative charges. These improved physicochemical features synergically conferred a two-fold water permeance while maintaining a high divalent salt rejection (THPC-0.01: 18.3 L m-2 h−1 bar−1, 99.0 %, THPS-0.015: 20.2 L m−2 h−1 bar−1, 98 %). This aqueous organophosphorus regulated IP offers a simple and feasible approach to the preparation of low-transport-resistance PA membranes for enhanced NF performance.

Ultrafast gelling bioadhesive based on blood plasma and gelatin for wound closure and healing

Tissue adhesives offer a plethora of advantages in achieving efficient wound closure over conventional sutures and staples. Such materials are of great value, especially in cases where suturing could potentially damage tissues or compromise blood flow or in cases of hard-to-reach areas. Besides providing wound closure, the tissue adhesives must also facilitate wound healing. Previously, plasma-based tissue adhesives and similar bioinspired strategies have been utilized to aid in wound healing. Still, their application is constrained by factors such as high cost, diminished biocompatibility, prolonged gelation times, inadequate swelling, quick resorption, as well as short-term and inconsistent efficacy. To address these limitations, we report the development of a highly biocompatible and ultrafast-gelling tissue adhesive hydrogels. Freeze-dried platelet-rich plasma, heat-denatured freeze-dried platelet-poor plasma, and gelatin were utilized as the base matrix. Gelation was initiated by adding tetrakis hydroxymethyl phosphonium chloride. The fabricated gels displayed rapid gelation (3–4 s), low swelling, increased proliferation, and migration against L929 cells and had porcine skin tissue adhesion strength similar to that of plasma-based commercial glue (Tisseel®).

A highly bioactive THPC-crosslinked recombinant collagen hydrogel implant for aging skin rejuvenation

Skin aging, a complex physiological progression marked by collagen degradation, poses substantial challenges in dermatology. Recombinant collagen emerges as a potential option for skin revitalization, yet its application is constrained by difficulties in forming hydrogels. We have for the first time developed a highly bioactive Tetrakis(hydroxymethyl) phosphonium chloride (THPC)-crosslinked recombinant collagen hydrogel implant for aging skin rejuvenation. THPC demonstrated superior crosslinking efficiency compared to traditional agents such as EDC/NHS and BDDE, achieving complete recombinant collagen crosslinking at minimal concentrations and effectively inducing hydrogel formation. THPC's four reactive hydroxymethyl groups facilitate robust crosslinking with triple helical recombinant collagen, producing hydrogels with enhanced mechanical strength, excellent injectability, increased stability, and greater durability. Moreover, the hydrogel exhibited remarkable biocompatibility and bioactivity, significantly promoting the proliferation, adhesion, and migration of human foreskin fibroblast-1. In photoaged mice skin models, the THPC-crosslinked collagen hydrogel implant notably improved dermal density, skin elasticity, and reduced transepidermal water loss, creating a conducive environment for fibroblast activity and healthy collagen regeneration. Additionally, it elevated superoxide dismutase (SOD) activity and displayed substantial anti-calcification properties. The THPC-crosslinked recombinant collagen hydrogel implant presents an innovative methodology in combating skin aging, offering significant promise in dermatology and tissue engineering.

Hydrogen Production from Hydrous Hydrazine Decomposition Using Ir Catalysts: Effect of the Preparation Method and the Support

Herein, Ir/CeO2 catalysts were prepared using the deposition–precipitation method with NaOH or urea as the precipitating agent or using sol immobilization with tetrakis(hydroxymethyl)phosphonium chloride (THPC) as the protective and reducing agent. The effect of the preparation method on Ir catalyst activity was evaluated in the liquid-phase catalytic decomposition of hydrous hydrazine to hydrogen. Ir/CeO2 prepared using sol immobilization and DP NaOH showed the best activity (1740 h−1 and 1541 h−1, respectively) and yield of hydrogen (36.6 and 38.9%). Additionally, the effect of the support was considered, using TiO2 and NiO in addition to CeO2. For this purpose, the sol immobilization of preformed nanoparticles technique was considered because it allows the same morphology of the immobilized particles to be maintained, regardless of the support. Ir deposited on NiO resulted in the most selective catalyst with a H2 yield of 83.9%, showing good stability during recycling tests. The catalysts were characterized using different techniques: X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with an X-ray detector (EDX) and inductively coupled plasma–mass spectroscopy (ICP-MS).

Revisiting the phosphonium salt chemistry for P-doped carbon synthesis: toward high phosphorus contents and beyond the phosphate environment.

The introduction of phosphorus and nitrogen atoms in carbo-catalysts is a common way to tune the electronic density, and thereby the reactivity, of the material, as well as to introduce surface reactive sites. Numerous environments are reported for the N atoms, but the P-doping chemistry is less explored and focuses on surface POx groups. A one-step synthesis of P/N-doped carbonaceous materials is presented here, using affordable and industrially available urea and tetrakis(hydroxymethyl)phosphonium chloride (THPC) as the N and P sources, respectively. In contrast to most of the synthetic pathways toward P-doped carbonaceous materials, the THPC precursor only displays P-C bonds along the carbon backbone. This resulted in unusual phosphorus environments for the materials obtained from direct thermal treatment of THPC-urea, presumably of type C-P-N according to 31P NMR and XPS. Alternatively, the in situ polymerization and calcination of the precursors were run in calcium chloride hydrate, used as a combined reaction medium and porogen agent. Following this salt-templating strategy led to particularly high phosphorus contents (up to 18 wt%), associated with porosities up to 600 m2 g-1. The so-formed P/N-doped porous materials were employed as metal-free catalysts for the mild oxidative dehydrogenation of N-heterocycles to N-heteroarenes at room temperature and in air.

Sensitivity of a bone-equivalent polymer gel dosimeter for measuring the dose to bone during radiation therapy.

Treatment planning systems that use the Monte Carlo algorithm can calculate the dose to the medium (Dm) in non-water-equivalent tissues such as bones. However, Dm cannot be verified using actual measurements; therefore, it is necessary to develop tissue-equivalent dosimeters. In this study, we developed a bone-equivalent polymer gel dosimeter (BPGD) that can measure the dose absorbed by the bone and investigated its sensitivity. The BPGDs were prepared by adding 3.0mol of calcium hydrogen phosphate dihydrate as a component of bone to an improved dose-sensitive polyacrylamide gelatin and tetrakis hydroxymethyl phosphonium chloride (iPAGAT). One day after preparation, the BPGDs were irradiated with a field size of 15 × 15 cm2 using a 10 MV X-ray beam to evaluate the dose sensitivity, dose-rate dependence, and dose-integration dependence. One day after dose exposure, the BPGDs were scanned using a 0.4T MRI APERTO Eterna (Hitachi, Tokyo, Japan) to obtain R2 values. The difference between the R2 values of 6Gy and 0Gy was up to 5s-1, and the R2 curve plateaued in the high-dose region. Moreover, the BPGD did not depend on the integration of the dose and dose rates. Therefore, the BPGDs that we developed can determine the radiation dose to bones.

Biocompatible and bioactive hydrogels of recombinant fusion elastin with low transition temperature for improved healing of UV-irradiated skin.

Prolonged exposure to UV radiation can cause severe photodamage to the skin, leading to abnormal fragmentation of elastin fibers. As one of the main protein components of the dermal extracellular matrix, elastin plays a critical role in the mechanical behavior and physiological function of the skin. Animal-derived elastin has attracted extensive attention in tissue engineering, however it suffers from severe drawbacks such as a risk of virus transmission, ready degradation, and challenging quality control. Herein, we have for the first time developed a novel recombinant fusion elastin (RFE) and its cross-linked hydrogel for improved healing efficacy for UV-irradiated skin. RFE showed temperature-sensitive aggregation behavior similar to natural elastin. Compared with recombinant elastin without the fusion V-foldon domain, RFE showed a much more ordered secondary structure and lower transition temperature. Furthermore, Native-PAGE results indicated that the addition of the V-foldon domain triggered the formation of remarkable oligomers in RFE, which may result in a more ordered conformation. Tetrakis Hydroxymethyl Phosphonium Chloride (THPC) cross-linking of RFE led to the production of a fibrous hydrogel with uniform three-dimensional porous nanostructures and excellent mechanical strength. The RFE hydrogel showed superior cellular activity, significantly promoting the survival and proliferation of human foreskin fibroblast-1 (HFF-1). Studies of mice models of UV-irradiated skin demonstrated that the RFE hydrogel pronouncedly accelerated their healing process by inhibiting epidermal hyperplasia as well as boosting the regeneration of collagen and elastin fibers. The highly biocompatible and bioactive recombinant fusion elastin and its cross-linked hydrogel provide a potent treatment for photodamaged skin, which may have promising applications in dermatology and tissue engineering.

Ionic liquid modified COF nanosheet interlayered polyamide membranes for elevated nanofiltration performance

Presently, advanced Thin-film nanocomposite (TFN) nanofiltration membranes fabricated using microporous materials displayed distinctly enhanced separation performance. Herein, tetrakis(hydroxymethyl) phosphonium chloride (THPC)-modified COF nanosheets (termed as IL@COF-367 NSs) were designed as the intermediate layer to construct a high-hydrophilic membrane support, with the purpose of regulating interfacial polymerization (IP) to optimize the physicochemical characters of polyamide films. Due to the high hydrophilicity and favored dispersion of IL@COF-367 NSs in aqueous phase, the as-fabricated COF nanosheet interlayer not only promotes uniform distribution of amine monomers, but also slows down their diffusion toward the organic interface. Compared pristine thin-film composite (TFC) membranes, the IC-TFN membranes yield a nodular polyamide film with a higher surface roughness (from 14.5 to 54.5 nm) and a lower film thickness (from 95 to 30 nm). Introducing IL@COF-367 NSs additionally improves the pore size (from 0.31 to 0.47 nm) of the functionalized TFN membrane revealed by the MWCO measurement. Consequently, IL@COF-367 NSs-interlayer polyamide (IC-TFN) membrane manifests a high permeability of 36.5 L m−2 h−1 bar−1 and satisfactory Na2SO4 rejection of 98.5 %. The usage of 2D hydrophilic COF nanosheet as an interlayer to optimize the polyamide membranes offers a guideline for the design of high-performance TFN membrane.

Phosphonium Modified Nanocellulose Membranes with High Permeate Flux and Antibacterial Property for Oily Wastewater Separation

Nanocellulose membranes could efficiently separate oily wastewater because of their super-hydrophilic and underwater super-oleophobic property and nano-porous structure. However, the practical application and storage of nanocellulose membranes is limited by their low water permeation flux and easy corrosion by bacteria, respectively. Herein, nanocellulose membranes with high permeate flux and antibacterial property were fabricated by grafting tetrakis(hydroxymethyl) phosphonium chloride (THPC) onto the surface of TEMPO-oxidized tunicate cellulose nanofibers (TCNFs) via esterification reaction. The introduction of THPC groups with tetrahedral structure on the surface of TCNFs significantly improved the pore size and interlayer space of nanocellulose membranes, resulting in an increase in water permeation flux. These THPC@TCNF membranes were super-hydrophilic and underwater super-oleophobic, which could effectively separate various oil/water nano-emulsions. Moreover, THPC@TCNF membranes possessed excellent durability, mechanical stability and cycling performance. Due to the presence of positively charged phosphonium groups, THPC@TCNF membranes exhibited excellent antibacterial property against B. subtilis, a typical Gram-positive bacterium presenting in oily wastewater. This work provides a simple method to endow nanocellulose membrane with high permeate flux and antibacterial property.

Positively charged membranes for dye/salt separation based on a crossover combination of Mannich reaction and prebiotic chemistry

With the advent of increasingly loose nanofiltration membranes for dye desalination, synthesis methods based on interfacial polymerization and bio-inspired materials such as polydopamine (pDA) have been investigated. However, the long polymerization time of pDA greatly limits the synthesis and application of fast dye/salt separation membranes. In this work, prebiotic chemistry-inspired aminomalononitrile (AMN) was used as a binder to co-deposit the Mannich reaction of tetrakis(hydroxymethyl)phosphonium chloride (THPC) and polyethyleneimine (PEI) to form the positively charged selective layer rapidly. The optimum membrane had a water permeance of 30.7 LMH bar-1 and a rejection of positively charged Victoria blue B (VBB, 200 ppm) and Na2SO4 (1 g/L) of 99.5 % and 9.9 %, respectively. Moreover, the results of a practical application test showed that it had excellent separation performance towards various positively charged dyes and salts. In addition, the actual application test results show that the membrane has good long-term stability during application. In terms of antifouling and antibacterial, the membrane has excellent antibacterial and antifouling properties., Further antibacterial tests were carried out, and the inactivation effect of the membrane on E. coli was also confirmed. The preparation method proposed in this work provides technical support for developing new dye/salt separation membranes.

Mouthpiece polymer-gel dosimeter for in vivo oral dosimetry during head and neck radiotherapy

In this study, we developed a mouthpiece-type gel dosimeter to prevent the oral mucositis caused by the perturbation effect of dental alloys in the radiotherapy of the head and neck regions and to enable in vivo dosimetry. Understanding the dose distribution in the oral cavity during radiotherapy helps identify the possible site for oral mucositis during treatment. Here agarose, which has a higher melting point than gelatin, was added as a coagulant to stabilize the shape of the dosimeter. The strength and dose response of the dosimeter were investigated. The strength was measured at room temperature, 20°C–40 °C, which is higher than the intraoral temperature. The dose–response curves were obtained by magnetic resonance imaging with R2 ranging from 0 to 25 Gy. The strength and dose response of the mouthpiece-type gel dosimeter were approximately 4 and 2.1 times higher than those of polyacrylamide gel and tetrakis hydroxymethyl phosphonium chloride dosimeters commonly used in the prescribed doses per fraction of treatment. The dosimeter is composed of 4 wt% MgCl2 and 1.5 wt% agarose; thus, it can retain the water equivalence. Through in vivo oral dosimetry in three dimensions for head and neck radiotherapy with dental alloys using the mouthpiece-type gel dosimeter, we obtained three-dimensional dose distributions in the dosimeter. The properties of the dosimeter show that it can be used in the clinic, depending on the prescribed dose.

Coral-like hierarchically nanostructured membrane with high free volume for salt-free solar-enabled water purification

Solar evaporation presents a sustainable means to alleviate global water shortages. Varying photothermal materials have been designed to enhance evaporation performance. However, the critical technology gap is their low efficiency due to the severe salt crystallization and organic pollution. Here, we proposed a coral-like polypyrrole (PPy)-based photothermal membrane by the interface modification of d-glucitol (DG) and tetrakis (hydroxymethyl)phosphonium chloride (THPC). The designed PPy@DG/THPC membrane exhibited a wide range of sunlight absorption capacity with an efficiency of ∼97.6% due to its hierarchical nanostructure. Moreover, this membrane displayed superhydrophilicity and rich charges, giving it a superior salt-resistance property. Furthermore, molecular dynamics simulations indicated that this membrane exhibited a high free volume to inhibit salt crystallization. Hence, the evaporation rate of the PPy@DG/THPC membrane reached 1.46 ± 0.02 kg/m2/h in simulated brine (3.5 wt% NaCl) under 1-sun illumination. Besides, it exhibited exceptional anti-fouling ability under the synergy of hydration and charge effects. Overall, this membrane can achieve effective and sustainable solar evaporation to produce freshwater water to meet drinking-water standards. This work will offer a new approach to developing efficient solar evaporation for water remediation.

A PEI/TMC membrane modified with an ionic liquid with enhanced permeability and antibacterial properties for the removal of heavy metal ions

Heavy metal ions in drinking water severely threaten public health in various places worldwide. Nanofiltration (NF) membrane technology is an attractive option for heavy metal ions removal; however, improving NF membrane filtration performance is required to make their industrial application viable. In this study, a positively charged THPC/PEI-TMC NF membrane was designed via simple one-step incorporation of Tetrakis (hydroxymethyl) phosphonium chloride (THPC) biocide on the surface of PEI-TMC membranes, significantly optimizing surface morphology, roughness, hydrophilicity, and zeta potential of PEI-TMC membranes. It was found that the pure water permeability (11.6 Lm−2h−1bar−1) of the THPC modified membrane was three times larger than that of the original PEI-TMC membrane (3.4 Lm−2h−1bar−1) while maintaining a high level of ion rejections (around 95% for Zn2+, Cd2+, Ni2+, Cu2+ and about 90% for Pb2+). Additionally, the incorporation of the THPC on the original PEI-TMC membrane surface also conferred good antibacterial properties, which protect the organic membrane from bacterial growth and prolong the lifespan of the membrane.

Bright green emission non-conjugated polymer dots: pH trigged hydrogel for specific adsorption of anionic dyes and visual detection of tert-butylhydroquinone

In recent years, non-conjugated polymer dots (PDs) have attracted considerable interests due to their fundamental importance and potential applications in diverse areas. Herein, we synthesized the green emissive non-conjugated PT PDs with polyethyleneimine (PEI) and tetrakis(hydroxymethyl)phosphonium chloride (THPC) as precursors in one-pot at room temperature with the quantum yield at 25%. Surprisingly, PT PDs solutions could be transformed to hydrogels by pH alteration. By characterization, PT PDs hydrogels performed porous structure with large surface area and positively charged functional groups. Anionic dyes could be easily adsorbed into PT PDs hydrogels through multiple electrostatic interactions. In addition, PT PDs could specifically detect tert-butylhydroquinone (TBHQ) with a low detection limit (27 µM), suggesting their high sensitivity. More importantly, the developed method was successfully applied the detection of TBHQ in the peanut oil, implicating their practical application.

Constructing oxidized carbon spheres-based heterogeneous membrane with high surface energy for energy-free water purification

Producing affordable freshwater becomes increasingly essential. Membrane separation technology offers an unprecedented opportunity, but they typically use fuel energy during the separation process. Therefore, it is a severe challenge to construct an advanced membrane for energy-free water purification. Herein, for the first time, we reported a heterogeneous membrane for pressure-free water purification. Oxidized carbon spheres (OCS) membrane was optimized by the coordinated modification of polydopamine (PDA) and tetrakis(hydroxymethyl)phosphonium chloride (THPC). Remarkably, the [email protected] membrane was progressively hydroxylated due to the THPC’s superb water-binding ability. Therefore, the [email protected]/THPC membrane demonstrated higher surface free energy and better hydrophilic capacity than the other membranes. Under the combined effect of abundant porous geometry and strong charge interaction, this membrane presented a splendid screening performance for various dye molecules without extra pressure. In addition, its separation throughput can be improved by regulating the external temperature. This work may offer a straightforward manner to handle the relationship between membrane structure and performance for pressure-free water purification.

Influence of reducing agents on in situ synthesis of gold nanoparticles and scaffold conductivity with emphasis on neural differentiation

BackgroundRecorded advancements in nerve tissue regeneration have still not provided satisfactory results, and complete physiological recovery is not assured. The engineering of nanofibrous scaffolds provides a suitable platform for stem cell transplantation by controlling cell proliferation and differentiation to replace lost cells. In this study, a conductive scaffold was fabricated by in situ synthesis of gold nanoparticles (Au-NPs) on electrospun polycaprolactone/chitosan nanofibrous scaffolds and its effect on neural differentiation of mesenchymal stem cells was investigated. MethodThe conductive scaffold was prepared using polycaprolactone/chitosan solution containing soluble Au ions by electrospinning approach. In situ synthesis of Au-NPs was conducted using two reducing agents, Tetrakis(hydroxymethyl)phosphonium chloride (THPC) as an organophosphorus compound and formaldehyde, and also different reduction times. Morphology and distribution of the Au-NPs on the nanofibrous scaffolds were assessed using field emission scanning electron microscopy (FE-SEM) and energy dispersed X-ray spectroscopy (EDX). The hydrophilicity and biocompatibility of the scaffolds were determined by water contact angle and MTT assays respectively. The characterization of the scaffolds was proceeded by testing the porosity, tensile strength and electrical conductivity. Also, the scaffold's ability to support neural differentiation of mesenchymal stem cells was evaluated by immune-staining/blotting of Beta tubulin III. Results & conclusionFE-SEM and EDX results demonstrated the uniform distribution of Au-NPs on electrospun nanofibers made of a combination of polycaprolactone and chitosan (PCL/CS). We found that electrical conductivity of the scaffolds fabricated using THPC for 4 days and formaldehyde for 7 days was in the range of electrical conductivity of the scaffolds suitable for nerve regeneration. Contact angle measurements showed the effect of Au-NPs on the hydrophilic properties of the scaffolds, where the scaffold showed the porosity of 50% in the presence of Au-NPs. Au-NPs decoration on the scaffold decreased the mechanical properties with the ultimate strength of 14 (MPa). In vitro assessment demonstrated the potential of the fabricated conductive scaffold to enhance the attachment and proliferation of fibroblast cells, and differentiation potential of mesenchymal stem cells toward neuron-like cells. This designed scaffold holds promise as a future carrier and delivery platform in nerve tissue engineering.

One step synthesis of an amino acid derived particles, poly(L‐Arginine) and its biomedical application

AbstractHerein, single step synthesis of poly(L‐Arginine) (p(L‐Arg)) particles was reported for the first time via microemulsion crosslinking method using tetrakis(hydroxymethyl) phosphonium chloride (THPC) as the crosslinking agent. The C‐P vibrational FT‐IR peaks of the p(L‐Arg) particles observed at 1035 cm−1 as well as elemental analysis results corroborated the successful crosslinking of native L‐Arg molecules with THCP. Spherical‐shaped p(L‐Arg) particles visualized by SEM analysis ranged 1–10 μm in size in dry state. The important parameters of p(L‐Arg) particles affecting their biomedical potential use such as degradability, blood compatibility, antioxidant and antimicrobial properties were thoroughly investigated. Accordingly, 49.2 ± 6.7%, 68.1 ± 4.8%, and 62.5 ± 7.1% of the p(L‐Arg) particles were degraded at pH 5.4, 7.4, and 9.0, respectively, in about 200 h. The p(L‐Arg) particles exhibited fascinating blood compatibility with less than 4% hemolysis induction and more than 95% blood clotting index at 2 mg/mL concentration. The antioxidant activity of p(L‐Arg) particles was measured as 0.66 ± 0.06 μM Trolox equivalent g−1 by means of TEAC assay. Moreover, the antimicrobial activity of L‐Arg amino acid against Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 10145, gram‐positive Staphylococcus aureus ATCC 6538, B. subtilis ATCC 6633 bacteria, and Candida albicans ATCC 10231 yeast strains was significantly enhanced in the form of p(L‐Arg) particles. Furthermore, drug loading and release performances of p(L‐Arg) particles were also investigated using naproxen and riboflavin as active pharmaceuticals. Based on drug release studies performed in PBS at pH 7.4, 73.9 ± 12.6% of loaded naproxen was released in 90 min, whereas 62.1 ± 4.6% of loaded riboflavin was released in 135 min.

Basic features of VIC-T dosimeter with spiral CT readout, CT scanning conditions and data processing with a new polyGeVero-CT software package

This work reports on the results obtained for VIC-T dosimeter for radiotherapy dosimetry (17 % (w/v) N-vinylpyrrolidone, 8 % (w/v) N,N′-methylenebisacrylamide, 12 % (w/v) tert-butyl alcohol, 5 % (w/v) gelatine, 0.02 % (w/v) hydroquinone and 14 mM tetrakis (hydroxymethyl) phosphonium chloride (THPC)) measured with a spiral computed tomography (CT). Optimal spiral CT protocol, CT measurements conditions and image processing are provided. Basic features of VIC-T are discussed such as a calibration relation and dose resolution with respect to former N-vinylpyrrolidone containing dosimeters. Both adopted data processing performed with a new polyGeVero®-CT software package and its features are reported.

Effect of Metal Nanoparticle Aggregate Structure on the Thermodynamics of Oxidative Dissolution.

Here, we compare the electrochemical oxidation potential of 15 nm diameter citrate-stabilized Au NPs aggregated by acid (low pH) to those aggregated by tetrakis(hydroxymethyl) phosphonium chloride (THPC). For acid-induced aggregation, the solution changes to a blue-violet color, the localized surface plasmon resonance (LSPR) band of Au NPs at 520 nm decreases along with an increase in absorbance at higher wavelengths (600-800 nm), and the peak oxidation potential (Ep) in anodic stripping voltammetry (ASV) obtained in bromide has a positive shift by as large as 200 mV. For THPC-induced aggregation (Au/THPC mole ratio = 62.5), the solution changes to a blue color as the LSPR band at 520 nm decreases and a new distinct peak at 700 nm appears, but the Ep does not exhibit a positive shift. Scanning transmission electron microscopy (STEM) images reveal that acid-induced aggregates are three-dimensional with strongly fused Au NP-Au NP contacts, while THPC-induced aggregates are linear or two-dimensional with ∼1 nm separation between Au NPs. The surface area-to-volume ratio (SA/V) decreases for acid-aggregated Au NPs due to strong Au NP-Au NP contacts, which leads to lower surface free energy and a higher Ep. The SA/V does not change for THPC-aggregated Au NPs since space remains between them and their SA is fully accessible. These findings show that metal NP oxidative stability, as determined by ASV, is highly sensitive to the details of the aggregate structure.

Environmentally-benign, water-based covalent polymer network for flame retardant cotton

Relatively simple flame retardant finishing technologies for cotton are greatly desired in a variety of fire-sensitive applications (e.g., transportation, workwear, etc.). Many current industrial processes take advantage of halogen-containing flame retardants or require complicated processing. This study demonstrates a simple and halogen-free flame retardant treatment for cotton, which proceeds via a spontaneous Mannich-type reaction between branched polyethylenimine (PEI) and tetrakis(hydroxymethyl)phosphonium chloride (THPC). A polymer network deposited using 5 wt% THPC and 10 wt% PEI endows cotton fabric with self-extinguishing behavior during vertical flame testing. The treated cotton maintains high flame retardancy after simulated washing. This coating promotes formation of a continuous intumescent char layer, effectively protecting the cellulose matrix from fire and inhibiting the production of flammable volatiles during pyrolysis and burning. The simplicity and efficacy of this relatively environmentally-benign treatment makes it attractive for replacing halogen-containing and more complex flame-retardant finishing processes.