Ferroelectric PVDF nanofiber membrane for high-efficiency PM0.3 air filtration with low air flow resistance

The significant public health concerns related to particulate matter (PM) air pollutants and the airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have led to considerable interest in high-performance air filtration membranes. Highly ferroelectric polyvinylidene fluoride (PVDF) nanofiber (NF) filter membranes are successfully fabricated via electrospinning for high-performance low-cost air filtration. Spectroscopic and ferro-/piezoelectric analyses of PVDF NF show that a thinner PVDF NF typically forms a ferroelectric β phase with a confinement effect. A 70-nm PVDF NF membrane exhibits the highest fraction of β phase (87%) and the largest polarization behavior from piezoresponse force microscopy. An ultrathin 70-nm PVDF NF membrane exhibits a high PM_0.3 filtration efficiency of 97.40% with a low pressure drop of 51 Pa at an air flow of 5.3 cm/s owing to the synergetic combination of the slip effect and ferroelectric dipole interaction. Additionally, the 70-nm PVDF NF membrane shows excellent thermal and chemical stabilities with negligible filtration performance degradation (air filtration efficiency of 95.99% and 87.90% and pressure drop of 55 and 65 Pa, respectively) after 24 h of heating at 120 °C and 1 h immersion in isopropanol.

A highly efficient nanofibrous air filter membrane fabricated using electrospun amphiphilic PVDF-g-POEM double comb copolymer

Current global emergencies, such as the COVID-19 pandemic and particulate matter (PM) pollution, require urgent protective measures. Nanofibrous air filter membranes that can capture PM_0.3 and simultaneously help in preventing the spread of COVID-19 are essential. Therefore, a highly efficient nanofibrous air filter membrane based on amphiphilic poly(vinylidene fluoride)-graft-poly(oxyethylene methacrylate) (PVDF-g-POEM) double comb copolymer was fabricated using atomic transfer radical polymerization (ATRP) and electrospinning. Fourier transform infrared spectroscopy, X-ray diffraction, proton nuclear magnetic resonance, transmission electron microscopy, differential scanning calorimetry, and thermogravimetric analysis were employed to successfully characterize the molecular structure of the fabricated amphiphilic PVDF-g-POEM double comb copolymer. The nanofibrous air filter membrane based on amphiphilic PVDF-g-POEM double comb copolymer achieved a low air resistance of 4.69 mm H₂O and a high filtration efficiency of 93.56 % due to enhanced chemical and physical adsorption properties.

Influenza B burden during seasonal influenza epidemics in France

CONTEXT

Seasonal flu outbreaks are linked to the circulation of influenza virus type A or B. Special attention has always been paid to influenza A epidemics; but recently, several studies have investigated the impact of influenza B virus epidemics, particularly as, since the 1980s, two antigenically different influenza B lineages co-circulate, raising the issue of vaccine matching.

OBJECTIVES

We present the results of influenza B burden during nine influenza seasons (2003-2013) and vaccine matching of the circulating lineages.

PATIENTS AND METHODS

Clinical and virological influenza surveillance data, collected by the Regional Groups for Influenza Surveillance Network in France, allows for studying the burden of influenza in the practice of the population of ambulatory care physicians.

RESULTS AND CONCLUSION

Our analysis is based on 37,801 samples, of which 12,036 were virologically confirmed influenza cases (31.8%), including 3576 cases of influenza B (29.7% of influenza cases). Influenza B viruses significantly circulated during six seasons. For each season, the influenza B epidemic peaked later than the influenza A epidemic. Influenza B is very common in children of school age but also affects other age groups. Finally, more than one-third of the analyzed influenza B viruses belonged to a different lineage than the one used in the composition of the trivalent vaccine. Our results are comparable to those described in other countries.

Recurrent tuberculosis in Houston, Texas: a population-based study

OBJECTIVE

To determine the predictors of recurrence of tuberculosis (TB), the drug resistance pattern of Mycobacterium tuberculosis strains recovered from recurrent TB patients, and the frequency of re-infection with a new M. tuberculosis strain among patients with recurrent disease.

DESIGN

A population-based, retrospective case-control study using the Houston Tuberculosis Initiative database.

RESULTS

We found that, among 100 patients with recurrent TB who completed adequate therapy for a first episode of TB, not receiving directly observed therapy, pulmonary disease, HIV/AIDS diagnosis, not having a family physician, being unemployed and using public transportation were predictors of recurrent disease. There was a significant increase in drug-resistant M. tuberculosis strains in the second episode of disease compared to the first episode (21.3% vs. 8.2%, P = 0.04). Exogenous re-infection with a new strain of M. tuberculosis was found to cause 24-31% of recurrent TB.

CONCLUSION

Recurrent TB in Houston is associated with a significant increase in drug-resistant M. tuberculosis strains. Re-infection with a new M. tuberculosis strain causes a significant proportion of recurrent TB in an area of low TB incidence. Patients with HIV/AIDS constitute a population at increased risk of disease recurrence.

Extra-pulmonary manifestations in a large metropolitan area with a low incidence of tuberculosis

BACKGROUND

The increases in extra-pulmonary tuberculosis (EPTB) have been largely due to human immunodeficiency virus co-infection. The rates of EPTB have remained constant despite the decline in pulmonary tuberculosis (PTB) cases.

OBJECTIVE

To evaluate covariates associated with EPTB.

METHODS

A 4-year cohort of EPTB patients was compared with PTB cases. Enrollees were assessed for TB risk, medical records were reviewed, and Mycobacterium tuberculosis isolates were fingerprinted.

RESULTS

We identified 538 EPTB cases (28.6%) in a total of 1878 enrollees. The most common sites of infection were lymph nodes (43%) and pleura (23%). EPTB cases included 320 (59%) males, 382 (71%) patients were culture-positive, and 332 (86.9%) patient isolates were fingerprinted. Fewer EPTB than PTB patients belonged to clustered M. tuberculosis strains (58% vs. 65%; P = 0.02). A multivariate model identified an increased risk for EPTB among African Americans (OR = 1.9, P = 0.01), HIV-seropositive (OR = 3.1, P < 0.01), liver cirrhosis (OR = 2.3, P = 0.02), and age <18 years (OR = 2.0, P = 0.04). Patients with concomitant pulmonary and extra-pulmonary infections were more likely to die within 6 months of TB diagnosis (OR = 2.3, P < 0.01).

CONCLUSIONS

African American ethnicity is an independent risk factor for EPTB. Mortality at 6 months is partly due to the dissemination of M. tuberculosis and the severity of the underlying co-morbidity.

Additional bacillus Calmette-Guérin therapy for recurrent transitional cell carcinoma after an initial complete response

OBJECTIVES

To determine the success of additional bacillus Calmette-Guérin (BCG) therapy for transitional cell carcinoma recurring after a complete response (CR) to the initial treatment course of BCG.

METHODS

All patients treated with BCG with a minimum follow-up of 5 years were reviewed to identify complete responders who subsequently recurred and received additional BCG therapy. The duration of initial response and the incidence and duration of a second CR were recorded.

RESULTS

Of 11 patients with an initial CR to a 6-week course of BCG, 9 (82%) achieved a second CR and 5 of the 9 (42%) maintained tumor-free status beyond 5 years of follow-up (median 87 months, range 64 to 110). Patients who again recurred after the second CR did not benefit from further BCG therapy.

CONCLUSIONS

A repeat course of BCG is a reasonable option of therapy for transitional cell carcinoma that has recurred after a CR to a prior course of BCG. Careful monitoring by cytology, cystoscopy, and biopsy is mandatory to direct nonresponders to prompt alternative therapy and to ensure continued disease-free status among responders.