“Nanofiltration” Enabled by Super-Absorbent Polymer Beads for Concentrating Microorganisms in Water Samples

Detection and quantification of pathogens in water is critical for the protection of human health and for drinking water safety and security. When the pathogen concentrations are low, large sample volumes (several liters) are needed to achieve reliable quantitative results. However, most microbial identification methods utilize relatively small sample volumes. As a consequence, a concentration step is often required to detect pathogens in natural waters. Herein, we introduce a novel water sample concentration method based on superabsorbent polymer (SAP) beads. When SAP beads swell with water, small molecules can be sorbed within the beads, but larger particles are excluded and, thus, concentrated in the residual non-sorbed water. To illustrate this approach, millimeter-sized poly(acrylamide-co-itaconic acid) (P(AM-co-IA)) beads are synthesized and successfully applied to concentrate water samples containing two model microorganisms: Escherichia coli and bacteriophage MS2. Experimental results indicate that the size of the water channel within water swollen P(AM-co-IA) hydrogel beads is on the order of several nanometers. The millimeter size coupled with a negative surface charge of the beads are shown to be critical in order to achieve high levels of concentration. This new concentration procedure is very fast, effective, scalable, and low-cost with no need for complex instrumentation

Sunlight-Activated Propidium Monoazide Pretreatment for Differentiation of Viable and Dead Bacteria by Quantitative Real-Time Polymerase Chain Reaction

Polymerase chain reaction (PCR)-based methods have been developed and increasingly used for rapid and sensitive detection of pathogens in water samples to better protect public health. A propidium monoazide (PMA) pretreatment can help to differentiate between viable and dead cells, but the photoactivation of PMA normally requires the use of an energy-consuming halogen light, which is not suitable for off-the-grid applications. Herein, we investigate sunlight as an alternative light source. Our results suggest that sunlight can successfully activate PMA, and the sunlight-activated PMA pretreatment can effectively reduce the amplification of DNA derived from dead cells in PCR assays. Potentially, a sunlight-activated PMA pretreatment unit can be integrated into a lab-on-a-chip PCR device for off-the-grid microbial detection and quantification

Discovery of Potential piRNAs from Next Generation Sequences of the Sexually Mature Porcine Testes

Piwi- interacting RNAs (piRNAs), a new class of small RNAs discovered from mammalian testes, are involved in transcriptional silencing of retrotransposons and other genetic elements in germ line cells. In order to identify a full transcriptome set of piRNAs expressed in the sexually mature porcine testes, small RNA fractions were extracted and were subjected to a Solexa deep sequencing. We cloned 6,913,561 clean reads of Sus Scrofa small RNAs (18–30 nt) and performed functional characterization. Sus Scrofa small RNAs showed a bimodal length distribution with two peaks at 21 nt and 29 nt. Then from 938,328 deep-sequenced small RNAs (26–30 nt), 375,195 piRNAs were identified by a k-mer scheme and 326 piRNAs were identified by homology searches. All piRNAs predicted by the k-mer scheme were then mapped to swine genome by Short Oligonucleotide Analysis Package (SOAP), and 81.61% of all uniquely mapping piRNAs (197,673) were located to 1124 defined genomic regions (5.85 Mb). Within these regions, 536 and 501 piRNA clusters generally distributed across only minus or plus genomic strand, 48 piRNA clusters distributed on two strands but in a divergent manner, and 39 piRNA clusters distributed on two strands in an overlapping manner. Furthermore, expression pattern of 7 piRNAs identified by homology searches showed 5 piRNAs displayed a ubiquitous expression pattern, although 2 piRNAs were specifically expressed in the testes. Overall, our results provide new information of porcine piRNAs and their specific expression pattern in porcine testes suggests that piRNAs have a role in regulating spermatogenesis

Concentrating microorganisms in water samples by super-absorbent polymer beads

Detection and quantification of pathogens in water is crit. for the protection of human health and for drinking water safety and security. When the pathogen concns. are low, large sample vols. (several liters) are needed to achieve reliable quant. results. However, most microbial identification methods utilize relatively small sample vols. As a consequence, a concn. step is often required in order to detect pathogens in natural waters. Herein, we introduce a novel water sample concn. method based on superabsorbent polymer (SAP) beads. When SAP beads swell with water, small mols. can be sorbed within the polymer beads, but large particles are excluded and, thus, concd. in the residual non-sorbed water. To illustrate this approach, millimeter-sized poly(acrylamide-co-itaconic acid) (P(AM-co-IA)) beads are synthesized and successfully applied to conc. water samples contg. two model microorganisms: Escherichia coli (E. coli) and bacteriophage MS2. This new water sample concn. procedure is very fast, effective, scalable, and low-cost with no need for complex instrumentation

Extraction of long time series wetland information based on Google Earth Engine and random forest algorithm for a plateau lake basin – A case study of Dianchi Lake, Yunnan Province, China

Wetlands are transitional zones between terrestrial and aquatic ecosystems. They have the potential to continuously provide human beings with food, raw materials, and other substances. Also, wetland landscape pattern changes have profound impacts on the climate of plateau areas and accelerate the rate of climate change, so it is crucial to extract long time series of plateau wetland information. Concurrent with large-scale urbanization, industrial development and construction, and rapid population increases, the lakeside wetlands in the Dianchi Lake Basin are changing rapidly. However, scholars have not yet extracted long time series wetland information for this area, so the long-term evolution of these wetlands cannot be clarified. In this study, we used the Google Earth Engine (GEE) platform to extract wetland information for the Dianchi Basin from 1988 to 2020 from Landsat data and generated 33 wetland maps by applying a random forest classification model to identify trends and a confusion matrix to assess accuracy. The results showed that the overall trend of wetland area from 1988 to 2020 showed an increasing area, and the total wetland area increased by 31.11 km2 (+9.67 %). Furthermore, the overall accuracy of most years exceeded 80 %, the QADI was no higher than 0.2, the user accuracy and producer accuracy were higher than 80 % and 70 %, respectively, for swamps and water bodies, and the remaining non-wetland categories also achieved robust classification accuracy. Thus, the results of this study can compensate for the lack of information on wetland changes in the region over the past 33 years and provide data support and a scientific basis for sustainable wetland development in the plateau

A Concise Review and Required Precautions for COVID-19 Outbreak in Diagnostic and Interventional Radiology

A global outbreak of a novel coronavirus (COVID-19) pneumonia began in December 2019 in Wuhan, China. The World Health Organization (WHO) announced a pandemic on March 11, 2020. The rapid rise in the case numbers and mortality led to the saturation of hospitals in many countries. COVID-19 patients usually present with fever, fatigue, dry cough, and dyspnea. Given the shortage of diagnostic kits in many countries and very high sensitivity of computed tomography (CT) for diagnosis of COVID-19 in clinically suspicious patients, the chest CT has been implemented among the primary initial methods of diagnosis before the confirmatory laboratory tests. This puts radiologists and radiology staff on the front line of this alarming pandemic. This report summarizes chest CT findings of COVID-19 patients to facilitate diagnosis and reviews a list of necessary precautions and safety measures for diagnostic and interventional radiology personnel. These precautionary plans are extremely important to avoid contamination of the health-care providers, as well as cross-contamination between patients