Viable medical waste chain network design by considering risk and robustness

Medical waste management (MWM) is an important and necessary problem in the COVID-19 situation for treatment staff. When the number of infectious patients grows up, the amount of MWMs increases day by day. We present medical waste chain network design (MWCND) that contains health center (HC), waste segregation (WS), waste purchase contractor (WPC), and landfill. We propose to locate WS to decrease waste and recover them and send them to the WPC. Recovering medical waste like metal and plastic can help the environment and return to the production cycle. Therefore, we proposed a novel viable MWCND by a novel two-stage robust stochastic programming that considers resiliency (flexibility and network complexity) and sustainable (energy and environment) requirements. Therefore, we try to consider risks by conditional value at risk (CVaR) and improve robustness and agility to demand fluctuation and network. We utilize and solve it by GAMS CPLEX solver. The results show that by increasing the conservative coefficient, the confidence level of CVaR and waste recovery coefficient increases cost function and population risk. Moreover, increasing demand and scale of the problem makes to increase the cost function.

Viable closed-loop supply chain network by considering robustness and risk as a circular economy

The viable closed-loop supply chain network (VCLSCND) is a new concept that integrates sustainability, resiliency, and agility into a circular economy. We suggest a hybrid robust stochastic optimization by minimizing the weighted expected, maximum, and entropic value at risk (EVaR) of the cost function for this problem. This form considers robustness against demand disruption. Finally, CLSC components are located, and quantity flows are determined in the automotive industry. The results show that the VCLSCND cost is less than not considering viability and has a - 0.44% gap. We analyze essential parameters. By increasing the conservative coefficient, confidence level, and the scale of the main model, decreasing the allowed maximum energy, the cost function, time solution, and energy consumption grow. We suggested applying the Fix-and-Optimize algorithm for producing an upper bound for large-scale. As can be seen, the gap between this algorithm and the main problem for cost, energy, and time solution is approximately 6.10%, - 8.28%, and 75.01%.

The cultivable microbiota of the human distal ileum

OBJECTIVES

The existing literature on the microbiota of the ileum is inconsistent. To further characterize the microbiota, we analysed samples obtained directly from resected ileums used for urinary diversion after radical cystectomy.

METHODS

We included 150 patients with bladder cancer operated on from March 2016 to March 2019. Samples obtained by rubbing a swab against the ileal mucosa 25 cm from the ileocecal valve were cultivated at the local laboratory. Microbial colonies were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF).

RESULTS

The microbial density of the distal ileum was low. Among our samples, 79% (95% confidence interval (CI) 71%, 84%) harboured less than 1.6 × 10⁴ cfu/mL, whereas 36% (95% CI 28%, 44%) harboured less than 1.6 × 10³ cfu/mL. The flora was dominated by viridans streptococci, Candida, Actinomyces, Rothia and Lactobacillus species. Colon-related bacteria i.e. strict anaerobic bacteria, Enterobacteriales and enterococci, were recovered from 14% of the samples. Constipation was associated with increased recovery of colon-related bacteria. Antibiotic treatment prior to surgical procedures did not affect culture results. Increased age was significantly associated with more substantial fungal growth and use of proton pump inhibitors seemed to increase both bacterial and fungal growth.

CONCLUSIONS

The microbiota of the human distal ileum is sparse and differs significantly from the colonic microbiota both quantitatively and by composition. These findings contradict recent metagenomics studies based on samples collected by retrograde colonoscopy and emphasize the crucial importance of adequate sampling techniques.

A novel method for rapid and sensitive detection of viable Escherichia coli cells using UV-induced PMA-coupled quantitative PCR

We report a specific and sensitive method to improve the coupling of propidium monoazide (PMA) with DNA derived from killed cells of Escherichia coli using UV light of 365 nm. UV light of three different intensities mainly 2.4 × 10³, 4.8 × 10³, and 7.2 × 10³ μJ/cm² was applied to E. coli cells each for 1, 3, and 5 min. PMA was found to be successfully cross-linked with the DNA from killed cells of E. coli at 4.8 × 10³ μJ/cm² in 3 min leading to the complete inhibition of PCR amplification of DNA derived from PMA-treated heat-killed cells. In spiked phosphate-buffered saline and potable water samples, the difference of the Cq values between PMA-treated viable cells and PMA-untreated viable cells ranged from -0.17 to 0.2, demonstrating that UV-induced PMA activation had a negligible effect on viable cells. In contrast, the difference of the Cq values between PMA-treated heat-killed cells and PMA-untreated heat-killed cells ranged from 8.9 to 9.99, indicating the ability of PMA to inhibit PCR amplification of DNA derived from killed cells to an equivalent as low as 10⁰ CFU. In conclusion, this UV-coupled PMA-qPCR assay provided a rapid and sensitive methodology to selectively detect viable E. coli cells in spiked water samples within 4 h.

Viability Detection of Foodborne Bacterial Pathogens in Food Environment by PMA-qPCR and by Microscopic Observation

Foodborne pathogens are responsible of foodborne diseases and food poisoning and thus pose a great threat to food safety. These microorganisms can adhere to surface and form a biofilm composed of an extracellular matrix. This extracellular matrix protects bacterial cells from industrial environmental stress factors such as cleaning and disinfection operations. Moreover, during these environmental stresses, many bacterial species can enter a viable but nonculturable (VBNC) state. VBNC cells are characterized by a loss of cultivability on conventional bacteriological agar. This leads to an underestimation of total viable cells in environmental samples, and thus poses a risk for public health. In this chapter, we present a method to detect viable population of foodborne pathogens in industrial environmental samples using a molecular method with a combination of propidium monoazide (PMA) and quantitative PCR (qPCR) and a fluorescence microscopic method associated with the LIVE/DEAD BacLight™ viability stain.

Biotin-exposure-based immunomagnetic separation coupled with nucleic acid lateral flow biosensor for visibly detecting viable Listeria monocytogenes

Infectious diseases caused by Listeria monocytogenes pose a great threat to public health worldwide. Therefore, a rapid and efficient method for L. monocytogenes detection is needed. In this study, a biotin-exposure-based immunomagnetic separation (IMS) method was developed. That is, biotinylated antibody was first targeted to L. monocytogenes. Then, streptavidin-functionalized magnetic nanoparticles were added and anchored onto L. monocytogenes cells indirectly through the strong noncovalent interaction between streptavidin and biotin. Biotin-exposure-based IMS exhibited an excellent capability to enrich L. monocytogenes. Specifically, more than 90% of L. monocytogenes was captured when the bacterial concentration was lower than 10⁴ colony-forming units (CFU)/mL. Importantly, the antibody dosage was reduced by 10 times of that in our previous study, which used antibody direct-conjugated magnetic nanoparticles. Propidium monoazide (PMA) treatment prior to PCR amplification could eliminate the false-positive results from dead bacteria and detected viable L. monocytogenes sensitively and specifically. For viable L.monocytogenes detection, enriched L. monocytogenes was treated with PMA prior to asymmetric PCR amplification. The detection limits of the combined IMS with nucleic acid lateral flow (NALF) biosensor for viable L. monocytogenes detection were 3.5 × 10³ CFU/mL in phosphate buffer solution and 3.5 × 10⁴ CFU/g in lettuce samples. The whole assay process of recognizing viable L. monocytogenes was completed within 6 h. The proposed biotin-exposure-mediated IMS combined with a disposable NALF biosensor platform posed no health risk to the end user, and possessed potential applications in the rapid screening and identification of foodborne pathogens.

Grazing of particle-associated bacteria-an elimination of the non-viable fraction

Quantification of bacteria being grazed by microzooplankton is gaining importance since they serve as energy subsidies for higher trophic levels which consequently influence fish production. Hence, grazing pressure on viable and non-viable fraction of free and particle-associated bacteria in a tropical estuary controlled mainly by protist grazers was estimated using the seawater dilution technique. In vitro incubations over a period of 42h showed that at the end of 24h, growth coefficient (k) of particle-associated bacteria was 9 times higher at 0.546 than that of free forms. Further, 'k' value of viable cells on particles was double that of free forms at 0.016 and 0.007, respectively. While bacteria associated with particles were grazed (coefficient of removal (g)=0.564), the free forms were relatively less grazed indicating that particle-associated bacteria were exposed to grazers in these waters. Among the viable and non-viable forms, 'g' of non-viable fraction (particle-associated bacteria=0.615, Free=0.0086) was much greater than the viable fraction (particle-associated bacteria=0.056, Free=0.068). Thus, grazing on viable cells was relatively low in both the free and attached states. These observations suggest that non-viable forms of particle-associated bacteria were more prone to grazing and were weeded out leaving the viable cells to replenish the bacterial standing stock. Particle colonization could thus be a temporary refuge for the "persistent variants" where the viable fraction multiply and release their progeny.

Recovery of Neisseria gonorrhoeae from 4 commercially available transport systems

Four commercial transport systems for the recovery of Neisseria gonorrhoeae were evaluated in support of the need to obtain culture isolates for the detection of antimicrobial resistance. Bacterial recovery from the InTray GC system was superior with minimal loss of viability in contrast to non-nutritive transport systems.

The early acquisition of viable knowledge: A use of recursive model as an analytical devise (methodolosocial)

In nurse education typically, information is presented to students within the classroom and then applied within a clinical situation. Acquisition of the knowledge required to inform the student's early practice is the focus of this research. This paper centres upon the construction of a cognitive model that is recursive in nature, and forms an integral part of a qualitative research study. The primary study investigated how first year student nurses use the information received in the classroom to underpin their early practice. Data were collected from 10 students and 4 of their lecturers, via blogs and interviews and used iteratively to create a model that is recursive in nature. Recursion is a process of repeatedly revisiting the same thing, in this case the data, which are considered in an iterative or progressive way. Recursion thus facilitated the development of a model, which was seen to change and develop in sophistication as more data were considered and evaluated. Visual devices were used throughout to bring clarity during the construction of the model. This visual process was pivotal to the analysis. This paper chronicles the development of an analytical device through the medium of the study presented. Viable knowledge is represented as the synthesis of concepts, as presented in the classroom, and practice, as experienced within the clinical area. It illustrates how conceptual material delivered within the classroom has become embedded within an individual student's consciousness and is used during a clinical placement to make sense of a specific situation. The study identifies how students use information and makes recommendations as to how appropriate curricula integrate all the facets of the recursive model. The process of recursive modelling is thus offered as an analytical devise, which may be applied by researchers to other qualitative data.

Differentiation between Viable and Dead Cryptosporidium Oocysts Using Fluorochrome Staining

The use of nucleic acid staining with a fluorochrome dye to differentiate viable and dead (heat-killed) Cryptosporidium oocysts was assessed. The specificities (percentage of unstained viable oocysts) and sensitivities (percentage of stained dead oocysts) of the seven tested dyes (SYTO-17® and SYTO-59® to 64®) ranged from 65 to 76% (average 71%) and 83 to 95% (average 91%), respectively. SYTO-59 and SYTO-17 imparted greater color (4+) intensity than the other dyes (2+ or less). Of these two dyes, SYTO-17 exhibited more brightness and slower discoloration and was selected for use in further experiments. The optimum staining time for SYTO-17 at 37℃ was one hour or more (sensitivity of 96%). Dye concentrations of 20 and 30 µM resulted in maximal color intensity, and no further improvement was observed with further increases in dye concentration. Staining a mixture of viable and dead oocysts (1:1 ratio) with 20 µM dye at 37℃ for one hour yielded the expected results (approximately 50%), but no remarkable increase in the percent staining with time (up to 8 hours) was observed. In this study, no ghost oocysts were observed. The present study indicated that the fluorogenic nucleic acid dye SYTO-17 could be used to discriminate between live and dead Cryptosporidium oocysts.

Semi-nested polymerase chain reaction for detection of toxigenic Vibrio cholerae from environmental water samples

A rapid and sensitive direct cell semi-nested PCR assay was developed for the detection of viable toxigenic V. cholerae in environmental water samples. The semi-nested PCR assay amplified cholera toxin (ctxA2B) gene present in the toxigenic V. cholerae. The detection sensitivity of direct cell semi-nested PCR was 2 × 10(3) CFU of V. cholerae whereas direct cell single-step PCR could detect 2 × 10(4) CFU of V. cholerae. The performance of the assay was evaluated using environmental water samples after spiking with known number of Vibrio cholerae O1. The spiked water samples were filtered through a 0.22 micrometer membrane and the bacteria retained on filters were enriched in alkaline peptone water and then used directly in the PCR assay. The semi-nested PCR procedure coupled with enrichment could detect less than 1 CFU/ml in ground water and sea water whereas 2 CFU/ml and 20 CFU/ml could be detected in pond water and tap water, respectively. The proposed method is simple, faster than the conventional detection assays and can be used for screening of drinking water or environmental water samples for the presence of toxigenic V. cholerae.