Role of water shear force for microplastics fragmentation into nanoplastics.

Wastewater treatment plants (WWTPs) are major recipients of microplastics (MPs) that break down into nanoplastics (NPs) during wastewater treatment through physical, chemical, and biological processes. In particular, mechanical stress induced by the mixing process commonly used in WWTPs is thought to play a crucial role in the production of secondary MPs/NPs, which are then discharged into the open water environment through the WWTP effluent. This study investigated the fragmentation of 250 and 106 µm-sized pristine and weathered polystyrene (PS) particles using a four-blade mechanical impeller. At an energy density level of 100 kJ/L, the 250 and 106 µm-sized pristine PS particles were broken down into mean sizes of 120.6 ± 19.1 and 95.6 ± 16.8 nm, respectively. The smallest sizes were found to be 90.9 ± 17.8 and 72.4 ± 19.6 nm due to the breakdown of 250 and 106 µm-sized weathered PS particles, respectively. The morphology of the PS particles after fragmentation also demonstrated the initiation of surface damage, such as cracks, pores and rough structures. This surface crack propagation, caused by mechanically induced water shear force, was identified as the primary mechanism of MP fragmentation into NPs. It was also found that NP levels significantly increased after 40 min of mixing, with at least a 28-fold increase in water solution at an energy density of 32 kJ/L. These results clearly show that the breakdown of MPs into NPs is a continuous process during wastewater treatment, posing a significant threat to the water environment through NP release by WWTP effluents.

Construction and Validation of LEA Hindi Chart: A Multicenter Study.

SIGNIFICANCE: This study explains the construction and validation of a chart in Hindi language, one of the commonly spoken languages in the world. The new visual acuity chart is called LEA Hindi chart. The calligraphy construction method described here can help develop other such acuity charts. PURPOSE: The purpose of this study was to construct and validate a new logMAR Hindi visual acuity chart (LEA Hindi chart) using principles similar to that of LEA symbols acuity chart. METHODS: A multicenter (three centers) study was conducted in two phases. The first phase consisted of identifying and constructing the Hindi optotypes using calligraphy techniques. The Hindi optotypes were calibrated against the Landolt C optotypes by measuring the threshold distance for visual acuity. In the second phase, the newly constructed LEA Hindi chart was validated against the Early Treatment Diabetic Retinopathy Study (ETDRS) and Landolt C visual acuity charts. Sixty participants were enrolled for the first phase (centers 1 and 2) and for the second phase of the study (centers 1 and 3). Additional 15 participants were enrolled (center 1) for testing repeatability. RESULTS: Four Hindi optotypes were identified and used for the construction of the chart (first phase). In the second phase, the LEA Hindi chart was found to be comparable with both the Landolt C, (logMAR acuity difference, 0.03 ± 0.13; P > .18) and ETDRS (logMAR acuity difference, -0.02 ± 0.09; P > .25) charts. All the three charts were also found to be repeatable (95% limits of agreement within 0.24 logMAR). CONCLUSIONS: The newly constructed LEA Hindi visual acuity chart gave comparable levels of visual acuity as that measured in an ETDRS or Landolt C charts. The repeatability was also similar to the standard charts. The LEA Hindi visual acuity chart can be used for patients comfortable with Hindi language and also in studies requiring multiple measurements of visual acuity, to avoid familiarity to a given chart.

Trackable Liposomes for In Vivo Delivery Tracing toward Personalized Medicine Care under NIR Light on Skin Tumor.

We report an near-infrared (NIR)-trackable and therapeutic liposome with skin tumor specificity. Liposomes with a hydrodynamic diameter of ∼20 nm are tracked under the vein visualization imaging system in the presence of loaded paclitaxel and NIR-active agents. The ability to track liposome nanocarriers is recorded on the tissue-mimicking phantom model and in vivo mouse veins after intravenous administration. The trackable liposome delivery provides in vitro and in vivo photothermal heat (∼40 °C) for NIR-light-triggered area-specific chemotherapeutic release. This approach can be linked with a real-time vein-imaging system to track and apply area-specific local heat, which hitchhikes liposomes from the vein and finally releases them at the tumor site. We conducted studies on mice skin tumors that indicated the disappearance of tumors visibly and histologically (H&E stains). The ability of nanocarriers to monitor after administration is crucial for improving the effectiveness and specificity of cancer therapy, which could be achieved in the trackable delivery system.

Nano and microplastics occurrence in wastewater treatment plants: A comprehensive understanding of microplastics fragmentation and their removal.

Nano/microplastic (NP/MP) pollution is a growing concern for the water environment. Wastewater treatment plants (WWTPs) are considered the major recipients of MP before discharging into local waterbodies. MPs enter WWTPs mainly from synthetic fibers through washing activities and personal care products. To control and prevent NP/MP pollution, it is essential to have a comprehensive understanding of their characteristics, fragmentation mechanisms, and the effectiveness of the current treatment processes used in WWTPs for NP/MP removal. Therefore, the objectives of this study are to (i) understand the detailed mapping of NP/MP in the WWTP, (ii) understand the fragmentation mechanisms of MP into NP, and (iii) investigate the removal efficiency of NP/MP by existing processes in the WWTP. This study found that fiber is the dominant shape of MP, and polyethylene, polypropylene, polyethylene terephthalate, and polystyrene are the major polymer type of MP in wastewater samples. Crack propagation and mechanical breakdown of MP due to water shear forces induced by treatment facilities (e.g., pumping, mixing, and bubbling) could be the major causes for NP generation in the WWTP. Conventional wastewater treatment processes are ineffective for the complete removal of MPs. Although these processes are capable of removing ∼95% of MPs, they tend to accumulate in sludge. Thus, a significant number of MPs may still be released into the environment from WWTPs on a daily basis. Therefore, this study suggested that using DAF process in the primary treatment unit can be an effective strategy to control MP in the initial stage before it goes to the secondary and tertiary stage.

Identification, classification and quantification of microplastics in road dust and stormwater.

Microplastics (MP) have become a major emerging class of pollutants representing significant eco-toxicological risks for ecosystems and marine environments. The aim of this study was to identify, classify and quantify MP present in both road dust and stormwater samples. A significantly higher level of MPs within road dust samples was detected from industrial area (1130 particles/kg of dust) than from residential area (520 particles/kg of dust), while stormwater samples from industrial and residential sites yielded 26 particles/L and 17 particles/L, respectively. Fiber-like shape accounted for 53% and 74% in road dust and stormwater samples, respectively. The main polymeric materials collected for both road dust and stormwater samples were, in order of occurrence (i) low-density polyethylene, (ii) high-density polyethylene, (iii) polypropylene, (iv) polyethylene terephthalate, (v) polystyrene, (vi) polyester and (vii) poly (amide). Most of the MP had an average maximum dimension smaller than 2 mm for both road dust and stormwater samples. The results from this study demonstrates that road dust is a significant contributor to MP pollution through direct polymeric materials wear off and transfer through stormwater, which eventually will end up in open water ways and broader ecological niches.

Understanding the fragmentation of microplastics into nano-plastics and removal of nano/microplastics from wastewater using membrane, air flotation and nano-ferrofluid processes.

Nano/microplastics (NPs/MPs), a tiny particle of plastic pollution, are known as one of the most important environmental threats to marine ecosystems. Wastewater treatment plants can act as entrance routes for NPs/MPs to the aquatic environment as they breakdown of larger fragments of the plastic component during the treatment process; therefore, it is necessary to remove NPs/MPs during the wastewater treatment process. In this study, understanding the effect of water shear force on the fragmentation of larger size MPs into smaller MPs and NPs and their removal by air flotation and nano-ferrofluid (i.e., magnetite and cobalt ferrite particle as a coagulant) and membrane processes were investigated as a proof-of-concept study. It is found that a two-blade mechanical impeller could fragment MPs from 75, 150 and 300 µm into mean size NPs/MPs of 0.74, 1.14 and 1.88 µm, respectively. Results showed that the maximum removal efficiency of polyethylene, polyvinyl chloride and polyester was 85, 82 and 69%, respectively, in the air flotation process. Increasing the dose of behentrimonium chloride surfactant from 2 to 10 mg/L improved the efficiency of the air flotation process for NPs/MPs removal. It is also found that the removal efficiency of NPs/MPs by the air flotation system depends on solution pH, size, and types of NPs/MPs. This study also found a less significant removal efficiency of NPs/MPs by both types of ferrofluid used in this study with an average removal of 43% for magnetite and 55% for cobalt ferrite. All three plastics tested had similar removal efficiency by the nano-ferrofluid particles, meaning that this removal technique does not rely on the plastic component type. Among all the process tested, both ultrafiltration and microfiltration membrane processes were highly effective, removing more than 90% of NPs/MPs fragment particles. Overall, this study has confirmed the effectiveness of using air flotation and the membrane process to remove NPs/MPs from wastewater.

Causes of Missed Referrals to Low-Vision Rehabilitation Services: Causes in a Tertiary Eye Care Setting.

PURPOSE: To identify the referral pattern and identify causes of missed referrals to low-vision services in a tertiary eye care center. METHODS: A retrospective review of all the hospital records of patients seen from September-December 2012 was done to identify patients with visual impairment. Low vision was defined as has a best-corrected visual acuity (BCVA) in the better eye of <20/60 to light perception (as per WHO definition); or a visual field of <20° from the point of fixation. The frequency of referrals in this database was used to identify referral patterns of physicians and also causes for missed referrals for these patients. RESULTS: Of 14,938 hospital medical records reviewed during the period, 499 patients missed low-vision services with a mean age of 46 ± 18.2 years, including 158 females. Among those missed, 12.07% were in the age group 0-15 years, while 30.9% of the patients were >60 years, with 157 requiring rehabilitative services and training. Causes for missed referrals were clear misses or non-referrals by the physician (39%), non-acceptance of services by the patient (53%), loss from appointment desks (4.5%), and loss to follow-up (3.5%). CONCLUSION: Missed referral to low-vision services in tertiary centers can be considerable; these need to be identified for optimal utilization and delivery of these services to patients with low vision.

Degree, duration, and causes of visual impairment in eyes affected with ocular tuberculosis.

BACKGROUND: Ocular tuberculosis (TB) can affect nearly every ocular tissue, leading to a variety of vision-threatening clinical manifestations. The goal of this study is to estimate the degree, duration, and causes of visual impairment in eyes affected by ocular TB. RESULTS: This was a retrospective study of patients diagnosed as ocular TB based on polymerase chain reaction (PCR) for Mycobacterium tuberculosis complex. We applied the World Health Organization definition of visual impairment (VI) to affected eye(s), instead of better-seeing eye. Best-corrected visual acuity (BCVA) of <6/18 and ≥6/60 in the affected eye was classified as moderate VI and <6/60 and ≥3/60 as severe VI. Data collected included presenting and final BCVA of affected eyes and the worst BCVA during the study period. Sixty-one eyes of 40 patients were analyzed. Twenty-five patients (52.1%) had bilateral disease. The mean worst BCVA and mean final BCVA (logMAR) were 1.26 ± 0.87 and 0.61 ± 0.85, respectively, and their difference was highly significant (p < 0.0001, Friedman test). The median worst and final BCVA results were 1.30 (range 0.0 to 3.0) and 0.20 (range 0.0 to 3.0), respectively. The mean duration of follow-up was 98.34 ± 81.81 weeks. Moderate and severe VIs were seen in 14 (22.9%) and 12 (19.7%) eyes, respectively, during the course of follow up. Twenty eyes (32.8%) had BCVA of <3/60. Moderate VI or worse was most commonly seen in eyes with multifocal serpiginoid choroiditis (n = 6; 100%), retinal vasculitis (n = 25; 80.6%), and panuveitis (n = 12; 80%). The mean duration of visual loss was 25.2 ± 42.37 weeks (median 6.43 weeks, range 0 to 206.42 weeks). Vitreous hemorrhage, complicated cataract, and macular scarring were the common causes of VI. CONCLUSION: Ocular TB can result in prolonged visual impairment, more commonly in patients with posterior uveitis or panuveitis.