Acid and Glutathione Dual-Responsive, Injectable and Self-Healing Hydrogels for Controlled Drug Delivery.

Considering the complexity of physiological microenvironments and the risks of surgical infection, there still remains critical demand to develop a hydrogel as a drug release platform with multifunctional properties, including good neutral stability and sensitive multiple stimuli-responsive behaviors, as well as injectable and self-healing properties. Herein, we present a facile preparation of injectable, self-healing hydrogels with acid and glutathione (GSH) dual-responsiveness for controlled drug delivery. Initially, the anticancer drug camptothecin (CPT) was premodified with disulfide bonds and attached to poly(ethylenimine) (PEI) via the Schiff base reaction, resulting in PEI-CPT. Subsequently, OSA-IR780 was synthesized through the Schiff base reaction involving IR780 with amine groups (IR780-NH2) and oxidized sodium alginate with aldehyde groups (OSA). The formation of PEI-CPT/OSA-IR780 hydrogels with various solid contents occurred rapidly within 40 s through a simple mixing process of the aqueous solution of PEI-CPT and OSA-IR780. These hydrogels exhibited remarkable stability under neutral conditions and controlled release of CPT upon exposure to simulated tumor environments characterized by acidic conditions and elevated GSH concentrations. Furthermore, they had significant injectable and self-healing properties due to the dynamically imine-cross-linked networks. In addition, the prepared hydrogels exhibited long-term biodegradability and biocompatibility. Collectively, these features indicate the great potential of PEI-CPT/OSA-IR780 hydrogels as therapeutic delivery vehicles.

Assessing the External Exposome Using Wearable Passive Samplers and High-Resolution Mass Spectrometry among South African Children Participating in the VHEMBE Study.

Children in low- and middle-income countries are often exposed to higher levels of chemicals and are more vulnerable to the health effects of air pollution. Little is known about the diversity, toxicity, and dynamics of airborne chemical exposures at the molecular level. We developed a workflow employing state-of-the-art wearable passive sampling technology coupled with high-resolution mass spectrometry to comprehensively measure 147 children's personal exposures to airborne chemicals in Limpopo, South Africa, as part of the Venda Health Examination of Mothers, Babies, and Their Environment (VHEMBE). 637 environmental exposures were detected, many of which have never been measured in this population; of these 50 airborne chemical exposures of concern were detected, including pesticides, plasticizers, organophosphates, dyes, combustion products, and perfumes. Biocides detected in wristbands included p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT), p,p'-dichlorodiphenyldichloroethane (p,p'-DDD), p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), propoxur, piperonyl butoxide, and triclosan. Exposures differed across the assessment period with 27% of detected chemicals observed to be either higher or lower in the wet or dry seasons.

Emerging and Legacy Per- and Polyfluoroalkyl Substances in an Elderly Population in Jinan, China: The Exposure Level, Short-Term Variation, and Intake Assessment.

Human exposure to per- and polyfluoroalkyl substances (PFASs) has gained worldwide attention due to their widespread presence in the environment and adverse health effects, but the exposure assessment in the elderly is still lacking. This study aimed to assess exposures to 3 emerging PFASs (chlorinated polyfluoroalkyl ether sulfonic acids, Cl-PFESAs) and 15 legacy PFASs. The temporal variability of internal exposures and intake amounts of these PFASs were evaluated among a population of 76 healthy elderly adults (age: 60-69) in Jinan, China over 5 consecutive months. Fifteen PFASs were detected in whole blood with the mean total concentration (ΣPFAS) at 20.1 ng/mL (range: 5.0-135.9 ng/mL) dominated by perfluorooctanoic acid (PFOA) (9.0 ng/mL), perfluorooctanesulfonic acid (PFOS) (5.3 ng/mL), and 6:2 Cl-PFESA (1.6 ng/mL). Across the 5 month assessment period, significant variation was only observed for short-chain (C4-C7) perfluoroalkyl carboxylic acids, and their variations ranged from 53 to 334%. The median intake of PFOA and PFOS was estimated to be 1.46 and 0.92 ng/kg bw/day, respectively. Regression analysis showed that dietary ingestion, especially fish, was likely an important exposure pathway for PFASs among the elderly adults. Various pathways (e.g., dietary, water, air, and dust) should thus be considered to fully understand human exposure to PFASs.

Head, Shoulders, Knees, and Toes: Placement of Wearable Passive Samplers Alters Exposure Profiles Observed.

Chemical exposures are a major risk factor for many diseases. Comprehensive characterization of personal exposures is necessary to highlight chemicals of concern and factors that influence these chemical exposure dynamics. For this purpose, wearable passive samplers can be applied to assess longitudinal personal exposures to airborne contaminants. Questions remain regarding the impact of sampler placement at different locations of the body on the exposure profiles observed and how these placements affect the monitoring of seasonal dynamics in exposures. This study assessed personal air contaminant exposure using passive samplers worn in parallel across 32 participant's wrists, chest, and shoes over 24 h. Samplers were analyzed by thermal desorption gas chromatography high-resolution mass spectrometry. Personal exposure profiles were similar for about one-third of the 275 identified chemicals, irrespective of sampler placement. Signals of certain semivolatile organic compounds (SVOCs) were enhanced in shoes and, to a lesser extent, wrist samplers, as compared to those in chest samplers. Signals of volatile organic compounds were less impacted by sampler placement. Results showed that chest samplers predominantly captured more volatile exposures, as compared to those of particle-bound exposures, which may indicate predominant monitoring of chemicals via the inhalation route of exposure for chest samplers. In contrast, shoe samplers were more sensitive to particle-bound SVOCs. Seventy-one chemicals changed across participants between winter and summer in the same manner for two or more different sampler placements on the body, whereas 122 chemicals were observed to have seasonal differences in only one placement. Hence, the placement in certain cases significantly impacts exposure dynamics observed. This work shows that it is essential in epidemiological studies undertaking exposure assessment to consider the consequence of the placement of exposure monitors.

Characterizing the external exposome using passive samplers-comparative assessment of chemical exposures using different wearable form factors.

BACKGROUND: Organic contaminants are released into the air from building materials/furnishings, personal care, and household products. Wearable passive samplers have emerged as tools to characterize personal chemical exposures. The optimal placement of these samplers on an individual to best capture airborne exposures has yet to be evaluated. OBJECTIVE: To compare personal exposure to airborne contaminants detected using wearable passive air samplers placed at different positions on the body. METHODS: Participants (n = 32) simultaneously wore four passive Fresh Air samplers, on their head, chest, wrist, and foot for 24 hours. Exposure to 56 airborne organic contaminants was evaluated using thermal desorption gas chromatography high resolution mass spectrometry with a targeted data analysis approach. RESULTS: Distinct exposure patterns were detected by samplers positioned on different parts of the body. Chest and wrist samplers were the most similar with correlations identified for 20% of chemical exposures (Spearman's Rho > 0.8, p < 0.05). In contrast, the greatest differences were found for head and foot samplers with the weakest correlations across evaluated exposures (8% compounds, Spearman's Rho > 0.8, p < 0.05). SIGNIFICANCE: The placement of wearable passive air samplers influences the exposures captured and should be considered in future exposure and epidemiological studies. IMPACT STATEMENT: Traditional approaches for assessing personal exposure to airborne contaminants with active samplers presents challenges due to their cost, size, and weight. Wearable passive samplers have recently emerged as a non-invasive, lower cost tool for measuring environmental exposures. While these samplers can be worn on different parts of the body, their position can influence the type of exposure that is captured. This study comprehensively evaluates the exposure to airborne chemical contaminants measured at different passive sampler positions worn on the head, chest, wrist, and foot. Findings provide guidance on sampler placement based on chemicals and emission sources of interest.

Performance and mechanism analysis of gel immobilized anammox bacteria in treating different proportions of domestic wastewater: a valid alternative to granular sludge.

The treatment performance of anaerobic ammonia oxidation (anammox) immobilized filler on different proportions of domestic wastewater was evaluated. The results showed that, in comparison to synthetic wastewater, 50% domestic wastewater promoted the anammox reaction of immobilized filler, while 100% domestic wastewater had no significant effect on the anammox activity of immobilized filler but the total nitrogen removal efficiency (TNRE) was improved through enhanced denitrification. The TNRE of the immobilized filler was 82.5%, which was significantly higher than that of AnGS (69.7%), and its average anammox contribution rate was more than 90%. This was because the encapsulated anammox biomass could better maintain competitive advantages and coordinate the symbiotic relationship with denitrifying bacteria. Moreover, lower NH4+-N concentration resulted in greater influence of C/N ratio on anammox performance than COD concentration, while the opposite was true at high NH4+-N concentration. This study verified that anammox immobilized filler is effective for mainstream applications.

Wearing time and respiratory volume affect the filtration efficiency of masks against aerosols at different sizes.

Face masks are critical in preventing the spread of respiratory infections including coronavirus disease 2019 (COVID-19). Different types of masks have distinct filtration efficiencies (FEs) with differential costs and supplies. Here we reported the impact of breathing volume and wearing time on the inward and outward FEs of four different mask types (N95, surgical, single-use, and cloth masks) against various sizes of aerosols. Specifically, 1) Mask type was an important factor affecting the FEs. The FEs of N95 and surgical mask were better than those of single-use mask and cloth mask; 2) As particle size decreased, the FEs tended to reduce. The trend was significantly observed in FEs of aerosols with particle size < 1 µ m ; 3) After wearing N95 and surgical masks for 0, 2, 4, and 8 h, their FEs (%) maintained from 95.75 ± 0.09 to 100 ± 0 range. While a significant decrease in FEs were noticed for single-use masks worn for 8 h and cloth masks worn >2 h under deep breathing (30 L/min); 4) Both inward and outward FEs of N95 and surgical masks were similar, while the outward FEs of single-use and cloth masks were higher than their inward FEs; 5) The FEs under deep breathing was significantly lower than normal breathing with aerosol particle size <1 µ m. In conclusion, our results revealed that masks have a critical role in preventing the spread of aerosol particles by filtering inhalation, and FEs significantly decreased with the increasing of respiratory volume and wearing time. Deep breathing may cause increasing humidity and hence decrease FEs by increasing the airflow pressure. With the increase of wearing time, the adsorption capacity of the filter material tends to be saturated, which may reduce FEs. Findings may be used to provide information for policies regarding the proper use of masks for general public in current and future pandemics.

Denitrification performance and bacterial flora analysis of immobilized denitrification filler in industrial wastewater.

The study aimed at evaluating the nitrogen removal performance of the immobilized denitrification filler, and the influence of shock loading on the high-rate denitrification process. A pilot scale reactor was operated for treatment of aniline production wastewater. The nitrogen removal activity significantly increased in the continuous feed experiments, reaching 5.23 kg N m-3 day-1 on day 31 (30 °C) at Hydraulic Retention Time (HRT) = 10 h. In the impact experiment, the denitrification filler was inhibited by Free Nitrite Acid (FNA) when the shock load flowed 1.5 times into the bioreactor and recovered after the load was restored for 20 h. The high-throughput results demonstrated that the dominant position of the denitrifying bacteria further enhanced in a micro toxic and high-salinity environment, providing a basis for the dominance of the composite denitrifying bacteria and the efficacy of the immobilization technology.

Prevalence and Implications of Per- and Polyfluoroalkyl Substances (PFAS) in Settled Dust.

PURPOSE OF REVIEW: Per- and polyfluoroalkyl substances (PFAS) are a family of more than 7,000 fluorinated compounds. The carbon-fluorine bond of PFAS provides desirable hydrophobic and oleophobic properties and stability that has led to widespread usage in consumer products and industrial applications. The strength of the carbon-fluorine bond also prevents appreciable degradation once released into the environment. Consequently, various household products can release volatile and nonvolatile PFAS into the indoor environment that often concentrate in dust. We discuss the diversity of PFAS in settled dust, emission sources of these chemicals, changes in PFAS profiles in dust over the past century, and the implications for human health. RECENT FINDINGS: Sources of PFAS found in dust include building materials and furnishings and consumer products used in typical indoor spaces. Daycares and workplaces are emphasized as locations with widespread exposure due to the presence of treated carpeting and industrial-strength cleaners. Comparison and interpretation of findings across studies are complicated by the different ways in which PFAS are screened across studies. We further discuss recent developments in non-targeted software for the comprehensive annotation of PFAS in indoor dust and emphasize the need for comprehensive and harmonized analytical workflows. We highlight the detection and diversity of PFAS in settled dust collected from various indoor spaces, including locations with vulnerable subpopulations. There are opportunities for future research to leverage settled dust as a sentinel environmental matrix to evaluate the link between inhalation and ingestion routes of PFAS exposure to adverse health.

Analysis of rapid culture of high-efficiency nitrifying bacteria and immobilized filler application for the treatment of municipal wastewater.

Activated sludge from the A2/O process in a wastewater treatment plant (WWTP) was used as the seed sludge for enrichment to achieve faster growth of nitrifying bacteria and higher nitrification efficiency of the filler made by nitrifying bacteria. The bacterial community was enriched in a self-circulating bacteria culture tank by a continuous ammonia feeding mode. The study found that the nitrifying bacteria community was enriched in 38 days with the ammonia oxidation rate of approximately 275.58 mg (L h)-1. High-throughput sequencing demonstrated that Nitrosomonas belonging to ammonia-oxidizing bacteria (AOB) was predominant in the sludge after 38 days at a ratio extending from 0.43% to 61.91%. The enriched sludge was used as the bacterial source and the immobilization was carried out with polyvinyl alcohol (PVA). After the recovery culture, the ammonia oxidation rate of the filler was up to 44.61 mg (L h)-1 for the treatment of municipal wastewater, and the effluent ammonia was below 1 mg L-1, indicating that the immobilized filler is effective for municipal wastewater nitrification. Scanning electron microscope (SEM) observations showed that immobilized fillers were highly porous and bacteria adhered to the network structure, demonstrating that the filler provided a good growth microenvironment for microorganisms.

[Research on Denitrification Performance of Enhanced Secondary Effluent by Embedded Denitrification Filler and Pilot Application].

The use of an embedded broad-spectrum high-efficiency denitrification filler to treat secondary effluent from municipal wastewater treatment plants can effectively reduce total nitrogen (TN) concentration of the effluent. This study consists of two parts. The D1 stage studies the adaptability of the secondary effluent based on the embedded denitrification, removal effect of total nitrogen, stable working conditions, and backwashing conditions; In the D2 stage, the change in the nitrogen removal performance of the filler under the condition of a year-long stable operation was studied. The variation in the microbial population before and after the operation of the embedded packing was studied by high-throughput sequencing and real-time quantitative PCR detecting system real-time (qPCR). In this research, the embedded denitrification filler had a water temperature of (24±1)℃, pH:7.1, hydraulic retention time (HRT):1 h, and filling rate:10%. Sodium acetate was added to ensure stable operation for seven days. Under adequate carbon source conditions, the filler can adapt to the quality of secondary effluent water and achieve effluent TN<5mg·L-1. By comparing and studying the effect of different HRT on the removal of filler TN, it is concluded that HRT is 30 min and the filling rate is 10%. After a year of stable operation under 7.2 m3·d-1influent conditions, the TN removal rate can reach 90.42%, and the total nitrogen in the effluent can be stabilized below 5 mg·L-1. In comparison with the backwashing effect, the backwashing strength was 5.2 L·(m2·s)-1, and the cycle is three days long. High-throughput sequencing and real-time quantitative PCR analysis results show that the abundance and copy number of denitrifying functional genus in the filler before and after the operation exhibited significant changes, which indicated that the bacteria could achieve good self-growth under embedding conditions.