Improvement in Electrochemical Performance of Waste Sugarcane Bagasse-Derived Carbon via Hybridization with SiO2 Nanospheres.

Sugar industries generate substantial quantities of waste biomass after the extraction of sugar water from sugarcane stems, while biomass-derived porous carbon has currently received huge research attention for its sustainable application in energy storage systems. Hence, we have investigated waste sugarcane bagasse (WSB) as a cheap and potential source of porous carbon for supercapacitors. The electrochemical capacitive performance of WSB-derived carbon was further enhanced through hybridization with silicon dioxide (SiO2) as a cost-effective pseudocapacitance material. Porous WSB-C/SiO2 nanocomposites were prepared via the in situ pyrolysis of tetraethyl orthosilicate (TEOS)-modified WSB biomass. The morphological analysis confirms the pyrolytic growth of SiO2 nanospheres on WSB-C. The electrochemical performance of WSB-C/SiO2 nanocomposites was optimized by varying the SiO2 content, using two different electrolytes. The capacitance of activated WSB-C was remarkably enhanced upon hybridization with SiO2, while the nanocomposite electrode demonstrated superior specific capacitance in 6 M KOH electrolyte compared to neutral Na2SO4 electrolyte. A maximum specific capacitance of 362.3 F/g at 0.25 A/g was achieved for the WSB-C/SiO2 105 nanocomposite. The capacitance retention was slightly lower in nanocomposite electrodes (91.7-86.9%) than in pure WSB-C (97.4%) but still satisfactory. A symmetric WSB-C/SiO2 105//WSB-C/SiO2 105 supercapacitor was fabricated and achieved an energy density of 50.3 Wh kg-1 at a power density of 250 W kg-1, which is substantially higher than the WSB-C//WSB-C supercapacitor (22.1 Wh kg-1).

Dynamic Treatment Regimes Using Bayesian Additive Regression Trees for Censored Outcomes.

To achieve the goal of providing the best possible care to each individual under their care, physicians need to customize treatments for individuals with the same health state, especially when treating diseases that can progress further and require additional treatments, such as cancer. Making decisions at multiple stages as a disease progresses can be formalized as a dynamic treatment regime (DTR). Most of the existing optimization approaches for estimating dynamic treatment regimes including the popular method of Q-learning were developed in a frequentist context. Recently, a general Bayesian machine learning framework that facilitates using Bayesian regression modeling to optimize DTRs has been proposed. In this article, we adapt this approach to censored outcomes using Bayesian additive regression trees (BART) for each stage under the accelerated failure time modeling framework, along with simulation studies and a real data example that compare the proposed approach with Q-learning. We also develop an R wrapper function that utilizes a standard BART survival model to optimize DTRs for censored outcomes. The wrapper function can easily be extended to accommodate any type of Bayesian machine learning model.

Manganese cobalt-MOF@carbon nanofiber-based non-enzymatic histamine sensor for the determination of food freshness.

Early detection of histamine in foodstuffs/beverages could be useful in preventing various diseases. In this work, we have prepared a free-standing hybrid mat based on manganese cobalt (2-methylimodazole)-metal organic frameworks (Mn-Co(2-MeIm)MOF) and carbon nanofibers (CNFs) and explored as a non-enzymatic electrochemical sensor for determining the freshness of fish and bananas based on histamine estimation. As-developed hybrid mat possesses high porosity with a large specific surface area and excellent hydrophilicity those allow easy access of analyte molecules to the redox-active metal sites of MOF. Furthermore, the multiple functional groups of the MOF matrix can act as active adsorption sites for catalysis. The Mn-Co(2-MeIm)MOF@CNF mat-modified GC electrode demonstrated excellent electrocatalytic activities toward the oxidation of histamine under acidic conditions (pH = 5.0) with a faster electron transfer kinetics and superior fouling resistance. The Co(2-MeIm)MOF@CNF/GCE sensor exhibited a wide linear range from 10 to 1500 µM with a low limit of detection (LOD) of 89.6 nM and a high sensitivity of 107.3 µA mM-1 cm-2. Importantly, as-developed Nb(BTC)MOF@CNF/GCE sensor is enabled to detect histamine in fish and banana samples stored for different periods of time, which thus indicates its practical viability as analytical histamine detector.

Recent Advances in Anode Electrocatalysts for Direct Formic Acid Fuel Cells - Part I - Fundamentals and Pd Based Catalysts.

Direct formic acid fuel cells (DFAFCs) have gained immense importance as a source of clean energy for portable electronic devices. It outperforms other fuel cells in several key operational and safety parameters. However, slow kinetics of the formic acid oxidation at the anode remains the main obstacle in achieving a high power output in DFAFCs. Noble metal-based electrocatalysts are effective, but are expensive and prone to CO poisoning. Recently, a substantial volume of research work have been dedicated to develop inexpensive, high activity and long lasting electrocatalysts. Herein, recent advances in the development of anode electrocatalysts for DFAFCs are presented focusing on understanding the relationship between activity and structure. This review covers the literature related to the electrocatalysts based on noble metals, non-noble metals, metal-oxides, synthesis route, support material, and fuel cell performance. The future prospects and bottlenecks in the field are also discussed at the end.

Hybrid support vector regression and crow search algorithm for modeling and multiobjective optimization of microalgae-based wastewater treatment.

Microalgae-based wastewater treatment (and biomass production) is an environmentally benign and energetically efficient technique as compared to traditional practices. The present study is focused on optimization of the major treatment variables such as temperature, light-dark cycle (LD), and nitrogen (N)-to-phosphate (P) ratio (N/P) for the elimination of N and P from tertiary municipal wastewater utilizing Chlorella kessleri microalgae species. In this regard, a hybrid support vector regression (SVR) technique integrated with the crow search algorithm has been applied as a novel modeling/optimization tool. The SVR models were formulated using the experimental data, which were furnished according to the response surface methodology with Box-Behnken Design. Various statistical indicators, including mean absolute percentage error, Taylor diagram, and fractional bias, confirmed the superior performance of SVR models as compared to the response surface methodology (RSM) and generalized linear model (GLM). Finally, the best SVR model was hybridized with the crow search algorithm for single/multi-objective optimizations to acquire the global optimal treatment conditions for maximum N and P removal efficiencies. The best-operating conditions were found to be 29.3°C, 24/0 h/h of LD, and 6:1 of N/P, with N and P elimination efficiencies of 99.97 and 93.48%, respectively. The optimized values were further confirmed by new experimental data.

Ornamental fish: a potential source of pathogenic and multidrug-resistant motile Aeromonas spp.

Aeromonas spp. are ubiquitous bacteria that cause diseases in fish and other aquatic animals. They are the natural inhabitants of different aquatic environments, such as freshwater, brackishwater and marinewater. Extrinsic stressors, such as crowding, unhygienic handling, poor water quality, polluted feeding and inadequate nutrition, can predispose fish to Aeromonas infection. In ornamental fish, motile Aeromonas spp. are known as aetiological agents of motile aeromonad infections, which cause significant mortality in fish and economic loss in the ornamental fish industry. The existence of different virulence factors leads to the virulence potential of motile Aeromonas spp. There are several antimicrobials used to treat bacterial infections in ornamental fish. However, the extensive use of antimicrobials in the ornamental fish industry causes multidrug resistance. This article reviewed a multitude of virulence factors that are related to the ornamental fish-borne Aeromonas pathogenicity and the antimicrobial resistance determinants related to the multidrug resistance phenotypes of motile Aeromonas spp. in ornamental fish.

Genetic gain for rice yield in rainfed environments in India.

The complexity of genotype × environment interactions under drought reduces heritability, which determines the effectiveness of selection for drought tolerance and development of drought tolerant varieties. Genetic progress measured through changes in yield performance over time is important in determining the efficiency of breeding programmes in which test cultivars are replaced each year on the assumption that the new cultivars will surpass the older cultivars. The goal of our study was to determine the annual rate of genetic gain for rice grain yield in a drought-prone rainfed system in a series of multi-environment trials conducted from 2005 to 2014 under the Drought Breeding Network of Indian sites in collaboration with the International Rice Research Institute (IRRI). Our results show a positive trend in grain yield with an annual genetic yield increase of about 0.68 % under irrigated control, 0.87 % under moderate reproductive stage drought stress and 1.9 % under severe reproductive stage drought stress due to breeding efforts. The study also demonstrates the effectiveness of direct selection for grain yield under both irrigated control as well as managed drought stress screening to improve yield in typical rainfed systems. IRRI's drought breeding programme has exhibited a significant positive trend in genetic gain for grain yield over the years under both drought stress as well as favorable irrigated control conditions. Several drought tolerant varieties released from the programme have outperformed the currently grown varieties under varied conditions in the rainfed environments on farmers' fields.

Species identification, virulence markers and antimicrobial resistance profiles of Aeromonas sp. isolated from marketed hard-shelled mussel (Mytilus coruscus) in Korea.

Hard-shelled mussel (Mytilus coruscus) is a popular seafood in Korea. This study aimed to determine the virulence markers and antimicrobial resistance patterns of 33 Aeromonas strains isolated from mussels. The isolates were identified as A. salmonicida (n = 14), A. veronii (n = 9), A. enteropelogenes (n = 4), A. caviae (n = 3), A. allosaccharophila (n = 2) and A. bivalvium (n = 1) by gyrB gene sequencing. The sequence divergence between and within the species ranged from 3·70 to 10·40% and 0-1·50% respectively. Every species formed a distinct group in a neighbour-joining phylogenetic tree. The DNase, gelatinase, caseinase, ß-haemolysis, biofilm and lipase activities were observed in 33 (100·00%), 31 (93·93%), 30 (90·90%), 27 (81·81%), 21 (63·63%) and 17 (51·51%) isolates respectively. The virulence genes were detected by PCR in the following frequencies: fla (90·09%), aer (87·88%), hlyA (87·88%), ahyB (81·19%), gcaT (75·76%), ser (69·70%), lip (66·67%), alt (57·58%), ast (51·51%) and act (21·21%). Every isolate was resistant to at least three of 18 antimicrobials in the disk diffusion test. The multiple antimicrobial resistance index values ranged from 0·11 to 0·44 among the isolates. Our study suggests that mussels can be a potential reservoir of virulent and multidrug-resistant Aeromonas sp. SIGNIFICANCE AND IMPACT OF THE STUDY: Aeromonas sp. are known as common pathogenic bacteria isolated from seafood. The virulence factors and antimicrobial resistance profiles of mussel-borne Aeromonas sp. are poorly understood. This study demonstrated for the first time the existence of virulence markers and antimicrobial resistance of Aeromonas sp. from mussels in Korea. Majority of the isolates were positive for phenotypic virulence characteristics and harboured several virulence genes which reveal the potential virulence of mussel-borne Aeromonas sp. Multiple antimicrobial resistance was also observed among the isolates. Our study highlights the importance of food safety standards in mussel consumption.

Prevalence of virulence and antimicrobial resistance genes in Aeromonas species isolated from marketed cockles (Tegillarca granosa) in Korea.

This study aimed to examine incidence, virulence and antimicrobial properties in Aeromonas spp. isolated from cockles (Tegillarca granosa) in Korea. Firstly, genomic DNA was extracted from 32 Aeromonas spp. isolates, and PCR screening for virulence, antimicrobial resistance genes was carried out. The disk diffusion assay was used to examine antimicrobial susceptibility. Aeromonas spp. isolates comprised, A. hydrophila (n = 8), A. veronii (n = 15), A. media (n = 2), A. salmonicida (n = 2), A. allosaccharophila (n = 1), A. bestiarum (n = 1), A. culicicola (n = 1), A. enteropelogenes (n = 1) and A. rivipollensis (n = 1). High prevalence of virulence-related genes reported as; act (69%), alt (47%), ast (41%), aerA (56%), lip (50%), ahyB (47%), ser (28%), fla (66%), gcat (44%), ascV (50%) and hlyA (72%). All isolates were multidrug resistant, while highest resistance level observed for ampicillin (100%), followed by imipenem (81%), rifampicin (78%), cephalothin (72%), piperacillin (47%) and Colistin sulfate (31%). The presence of blaSHV , blaCTX , tetE, aac(6')-Ib, strA-strB, qnrS, qnrB and IntI1 genes were reported in varying combinations. Nevertheless, blaTEM , blaIMP , tetA, tetB, qnrA, qnrB and aphAI-IAB genes and the class1 integron were not detected. The high occurrence of virulence and antimicrobial resistance genes in cockles reveals that it can be a potential health risk source for consumers.

Phylogenetic relationships, virulence and antimicrobial resistance properties of Klebsiella sp. isolated from pet turtles in Korea.

Klebsiella sp. are responsible for a multitude of infectious diseases in both humans and animals. In this study, phylogenetic relationships, virulence and antimicrobial resistance gene properties of 16 Klebsiella sp. isolated from 49 pet turtles were investigated. The isolates including Klebsiella oxytoca (n = 13) and Klebsiella pneumoniae (n = 3) were identified using 16S rRNA gene sequencing and each species formed distinct clusters in the neighbour-joining phylogenetic tree. The prevalence of virulence genes including ureC (100%) and kfu (68·75%) was observed among the isolates using Polymerase chain reaction (PCR) assay. The fimH, mrkD and rmpA genes were detected in all K. pneumoniae while these were absent in every K. oxytoca isolate. In antimicrobial susceptibility testing, high resistance rates were observed against ampicillin (100%) and cephalothin (62·50%). The resistance rates against imipenem, tetracycline, trimethoprim/sulfamethoxazole, nalidixic acid and ciprofloxacin were 12·50, 12·50, 12·50, 6·25 and 6·25% respectively. The presence of antimicrobial resistance genes such as plasmid-mediated quinolone resistance (PMQR) [qnrB (37·50%), qnrA (31·25%), qnrS (12·50%) and aac(6')-Ib-cr (12·50%)], extended-spectrum ß-lactamase (ESBL) [blaCTX-M (18·75%)], ß-lactamase [blaSHV-1 (18·75%)] and tetracycline resistance [tetE (12·50%)] was observed. The results revealed that pet turtle-borne Klebsiella sp. may carry different types of virulence and antimicrobial resistance genes which represents a potential threat to public health. SIGNIFICANCE AND IMPACT OF THE STUDY: Klebsiella sp. are nonmotile Gram-negative bacteria that are found in different environments. The virulence and antimicrobial resistance properties of pet turtle-borne Klebsiella sp. have not been studied before. Phylogenetic relationships, virulence traits and antimicrobial resistance profiles of pet turtle-borne Klebsiella sp. were characterized for the first time in Korea. Multiple virulence and antimicrobial resistance genes were observed among the isolates. The occurrence of virulence and antimicrobial resistance determinants in Klebsiella sp. may represent a potential threat to public health.

Prevalence of virulence and extended-spectrum ß-lactamase (ESBL) genes harbouring Vibrio spp. isolated from cockles (Tegillarca granosa) marketed in Korea.

The present study aimed to investigate the incidence, virulence and antibiotic properties in Vibrio spp. isolated from cockles (Tegillarca granosa) marketed in Korea. A total of 32 Vibrio spp. isolates including V. parahaemolyticus (n = 4), V. alginolyticus (n = 11), V. diabolicus (n = 14) and V. harveyi (n = 3) were detected using gyrB sequencing. The phenotypic pathogenicity revealed that the DNase, amylase and phospholipase activities were 100%, while lipase, slime production, gelatinase and caseinase were detected in 72, 88, 88 and 81% of the isolates respectively. The PCR amplification for the detection of V. parahaemolyticus species-specific tdh, tlh, trh and toxR genes were positive in 4 (13%), 16 (50%), 0 (0%) and 4 (13%) isolates respectively. The V. alginolytuicus species-specific tdh, tlh, trh, toxR and vac genes were carried by 15 (47%), 29 (91%), 0 (0%), 15 (47%) and 25 (78%) of the isolates respectively. In addition, multidrug resistance was observed by 27 (84%) isolates, whereas higher resistant rates were observed against ampicillin, piperacillin, streptomycin and cephalothin. The occurrence of blaCTX (78%), blaTEM (40%), blaSHV (22%) and aac(6')-Ib (94%) were prevalent, while strAB, tetB, aphAI-IAB, intl1 and aadA1 gene cassettes were also detected. The results signify the potential health risks resulting from the consumption of raw cockles in Korea. SIGNIFICANCE AND IMPACT OF THE STUDY: Vibrios are well known to cause human infections following consumption of raw or undercooked seafood. This phenomenon has undoubtedly increased the number of health issues over the past few years in Korea. Among the identified Vibrio spp., we could detect V. diabolicus and V. harveyi for the first time in marketed cockles in Korea. The presence of species-specific genes (tdh-VA, tlh-VP, tlh-VA and toxR-VA) in V. diabolicus exhibits the close genetic affinity among V. parahaemolyticus and V. alginolyticus. Furthermore, the prevalence of extended-spectrum ß-lactamases (ESBLs) and other antibiotic resistance genes along with multidrug resistance signifies the potential threat for consumers.

Manila clam (Ruditapes philippinarum) marketed in Korea as a source of vibrios harbouring virulence and ß-lactam resistance genes.

The present study assessed the occurrence, virulence determinants and antimicrobial susceptibility patterns of Vibrio spp. isolated from live Manila clam (Ruditapes philippinarum). A total of 31 Vibrio spp. including 27 V. diabolicus, two V. fluvialis, one V. alginolyticus and one V. antiquarius were isolated and identified. Phenotypic detection of DNase, lipase, phospholipase, amylase and caseinase activities was 100%; and 87% gelatinase, 45% slime production and 6% haemolysin activities were also observed. The prevalence of toxin-related virulence genes for collagenase (94%), toxR (100%), tlh (68%), and VPI (71%) was detected by PCR. Additionally, two V. fluvialis isolates carried F-toxR and hupo genes. Moreover, 61% of the isolates showed multiple antimicrobial resistance indices >0·2. The resistance rates of ampicillin, piperacillin, colistin sulfate, rifampicin, and cephalothin were 100, 81, 71, 77 and 68% respectively. The prevalence of blaCTX-M (87%), blaTEM (55%) and Int1 (90%) genes was observed, whereas blaSHV, strA-strB, tetA, tetB, and aadA2 gene cassette were reported in varying combinations. However, armA, aac(3)-IIa and quinolone resistance genes (qnrA, qnrB, qnrS) were not amplified. Thus, the virulence along with extended-spectrum ß-lactamases (ESBLs) and other antimicrobial resistance genes in multidrug-resistant Manila clam-borne vibrios may pose a public health threat for consumers. SIGNIFICANCE AND IMPACT OF THE STUDY: In Korea, eating raw seafood is considered a great delicacy. This has negatively affected the public by increasing health issues over the years due to the ingestion of vibrios. For the first time, we could identify Vibrio diabolicus and Vibrio antiquarius in marketed Manila clams in Korea. The prevalent Vibrio diabolicus isolates demonstrated the Vibrio parahaemolyticus and Vibrio cholerae homologous virulence genes (toxR, tlh, and VPI). Additionally, the abundance of extended-spectrum ß-lactamases (ESBLs) and integron (IntI1) harboured by Manila clam-borne vibrios elucidate the potential health risk for consumers and may complicate health treatments in the case of infection.

An Efficient Key Management Technique for the Internet of Things.

The Internet of Things (IoT) has changed our lives drastically. Customers, regulatory bodies, and industrial partners are driving us to use IoT. Although IoT provides new opportunities, security remains a key concern while providing various services. It is especially challenging how the data generated from IoT devices can be protected from potential security attacks and how to safeguard the exchange of these data while transiting through different nodes and gateways. In this research, we aim to ensure a safe IoT environment by proposing an efficient key management technique that uses a combination of symmetric and asymmetric cryptosystem to obtain the speed of the former as well as the security benefits of the latter. Our proposal considers a set of Smart Objects (SO) capable of key registration, generation and distribution for IoT data transmission. We used the open-source Message Queuing Telemetry Transport (MQTT) protocol to facilitate communications between the source and the destination nodes. The suitability of the proposed approach is measured experimentally and the results are comparable to existing works with respect to key conversion time, algorithm execution time, number of reuse connections, and bandwidth utilization.

Surface-Acoustic-Wave-Based Lab-on-Chip for Rapid Transport of Cryoprotectants across Cell Membrane for Cryopreservation with Significantly Improved Cell Viability.

Cryopreservation is essential to effectively extend the shelf life of delicate biomaterials while maintaining proper levels of cell functions. Cryopreservation requires a cryoprotective agent (CPA) to suppress intracellular ice formation during freezing, but it must be removed prior to clinical use due to its toxicity. Conventional multistep CPA loading and unloading approaches are time consuming, often creating osmotic shocks and causing mechanical injuries for biological samples. An efficient surface-acoustic-wave- (SAW-) based lab-on-a-chip (LoC) for fast loading and removal of CPAs is presented here. With the SAW-based multistep CPA loading/removal approach, high concentration (3 m) CPA can be successfully loaded and removed in less than 1 min. Results show that the technique causes the least harm to umbilical cord matrix mesenchymal stem cells as compared to conventional method, and an average of 24% higher cell recovery rate is achieved, while preserving the integrity and morphology of the cells. This device is the first of its kind to combine high loading/unloading efficiency, high cell viability, and high throughput into one LoC device, offering not only a more efficient and safer route for CPA loading and removal from cells, but also paving the way for other cryopreservation-dependent applications.

Antibiotic and heavy metal resistance genes in Aeromonas spp. isolated from marketed Manila Clam (Ruditapes philippinarum) in Korea.

AIMS: Manila clam (Ruditapes philippinarum) is one of the most popular seafood in Korea, owing to their unique taste and nutritional value. This study aimed to disclose the antibiotic and heavy metal resistance characteristics of Aeromonas spp. isolated from marketed Manila clam in Korea. METHODS AND RESULTS: A total of 36 Aeromonas spp. strains were isolated and subjected to two tests: an antibiotic disk diffusion test to determine their resistance to antibiotics, and a broth dilution test to determine their resistance to heavy metals. PCR-based amplification was performed to detect the resistance genes. A high level of resistance to ampicillin (100%) and cephalothin (89%) was observed, while 42, 39, 36 and 36% of the isolates were resistant to oxytetracycline, imipenem, nalidixic acid and tetracycline respectively. In addition, among the tested heavy metals, cadmium (Cd) recorded the highest resistance rate (61%), followed by chromium (Cr) (50%), lead (Pb) (47%) and copper (Cu) (37%). However, mercury (Hg) resistance was not observed. PCRs revealed the occurrence of blaTEM , blaSHV , blaCTX-M , qnrS, tetB, tetE, aac(6')-Ib, strA-strB and intI1 genes among 100, 31, 31, 78, 78, 89, 25, 50 and 72% of the isolates respectively. Moreover, heavy metal resistance genes, copA, merA and czcA were detected in 25, 47 and 61% of the isolates respectively. CONCLUSIONS: The results suggest the importance of multi-drug and heavy metal-resistant aeromonads in Manila clam to assess the consumer safety and public health. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first to elaborate on the importance of multi-drug and heavy metal-resistant aeromonads in Manila clam. Particularly, the presence of extended-spectrum-ß-lactamase genes and other antibiotic resistance genes intensifies the possible health risks and may complicate therapeutic treatments upon infection, while heavy metal resistance suggests possible heavy metal exposure.

Aeromonas spp. from marketed Yesso scallop (Patinopecten yessoensis): molecular characterization, phylogenetic analysis, virulence properties and antimicrobial susceptibility.

AIMS: Yesso scallop (Patinopecten yessoensis) is a popular seafood in Korea. Aeromonas spp., well-known pathogenic bacteria, has been reported in some molluscan shellfish, but it has not been studied in scallops so far. Therefore, we aimed to isolate, identify and characterize the Aeromonas spp. isolated from marketed Yesso scallops to estimate their potential risk to public health. METHODS AND RESULTS: Thirty-two Aeromonas spp. including A. hydrophila (n = 13), A. salmonicida (n = 11), A. media (n = 3), A. caviae (n = 2), A. veronii (n = 2) and A. enteropelogenes (n = 1) were isolated from 105 marketed scallops and tested for phenotypic pathogenicity, virulence genes and antimicrobial susceptibility. Mean total bacterial count of scallop meat was 1·34 × 104 CFU per gram. Slime production and lipase tests were positive in 97% of the isolates while DNase, protease, gelatinase, phospholipase and haemolysis were shown by 88, 88, 81, 88 and 72% of the isolates respectively. Eleven virulence genes were detected among Aeromonas spp. (act (75%), alt (59%), ast (47%), aerA (78%), lip (59%), ahyB (94%), ser (75%), hlyA (75%), fla (64%), gcat (84%) and ascV (23%)), and exu was negative in all isolates. Aeromonas hydrophila and A. salmonicida harboured ≥7 virulence genes and positive for enterotoxin genes, act, alt and ast. All the isolates were multidrug resistant and 100% resistant to ampicillin, colistin, vancomycin and cephalothin. Also, 30, 31, 20, 21, 29, 24, 27 and 27 of the isolates were resistant to piperacillin, clindamycin, erythromycin, nalidixic acid, imipenem, meropenem, trimethoprim-sulfamethoxazole and rifampicin respectively. CONCLUSIONS: It is obvious with our results that the Aeromonas spp. isolated from Yesso scallops are highly virulent and potentially pathogenic, whereas the multidrug resistance further expedite their importance. SIGNIFICANCE AND IMPACT OF THE STUDY: To our knowledge, this is the first study reporting Aeromonas spp. in scallop. This implies that not only the common varieties like oysters, but other bivalves can also harbour potentially pathogenic aeromonads which may have impacts on consumer health.

Multidrug resistant Aeromonas spp. isolated from zebrafish (Danio rerio): antibiogram, antimicrobial resistance genes and class 1 integron gene cassettes.

Aeromonas spp. are Gram-negative opportunistic bacteria which have been commonly associated with fish diseases. In this study, antibiogram, antimicrobial resistance genes and integrons of 43 zebrafish-borne Aeromonas spp. were studied. The isolates were identified as six Aeromonas species (A. veronii biovar veronii (n = 26), A. veronii biovar sobria (n = 3), A. hydrophila (n = 8), A. caviae (n = 3), A. enteropelogenes (n = 2) and A. dhakensis (n = 1)). Antibiogram of the isolates indicated that most of them were resistant to amoxicillin (100·00%), nalidixic acid (100·00%), oxytetracycline (100·00%), ampicillin (93·02%), tetracycline (74·42%), rifampicin (67·44%) and imipenem (65·15%). Multiple antimicrobial resistance (MAR) index values ranged from 0·19-0·44 to 90·70% isolates showed multidrug resistance. PCR of antimicrobial resistance genes revealed that the tetracycline resistance gene (tetA) was the most predominant (67·44%) among the isolates. The qnrS (53·49%), tetB (30·23%), tetE (30·23%), qnrB (23·26%) and aac(6')-Ib-cr (4·65%) genes were also detected. Class 1 integrase (IntI1) gene was found in 46·51% of the isolates. Two types of class 1 integron gene cassette profiles (qacG-aadA6-qacG and drfA1) were identified. The results showed that zebrafish-borne aeromonads can harbour different types of antimicrobial resistance genes and class 1 integrons. SIGNIFICANCE AND IMPACT OF THE STUDY: Aeromonas spp. are important pathogens found in diverse environments. Antimicrobial resistance genes and integrons of ornamental fish-borne Aeromonas spp. are not well studied. The antibiogram, antimicrobial resistance genes and class 1 integrons of Aeromonas spp. isolated from zebrafish were characterized for the first time in Korea. The prevalence of tetracycline resistance genes, plasmid-mediated quinolone resistance genes and class 1 integron gene cassettes were observed among the isolates. The qacG-aadA6-qacG gene cassette was identified for the first time in Aeromonas spp. The results suggest that the wise use of antimicrobials is necessary for the better management of the ornamental fish.

Incidence of antimicrobial resistance genes and class 1 integron gene cassettes in multidrug-resistant motile Aeromonas sp. isolated from ornamental guppy (Poecilia reticulata).

Aeromonas sp. are opportunistic pathogenic bacteria which are associated with various diseases in ornamental fish, aquaculture raised species and wild fisheries. In our study, antimicrobial resistance patterns, antimicrobial resistance genes and class 1 integron gene cassettes of 52 guppy-borne Aeromonas sp. were examined. The isolates were identified as A. veronii (n = 34), A. dhakensis (n = 10), A. hydrophila (n = 3), A. caviae (n = 3) and A. enteropelogenes (n = 2) by gyrB gene sequencing. Every isolate was resistant to at least four antimicrobials in disc diffusion test. The resistance to amoxicillin, nalidixic acid and oxytetracycline was 100% among the tested isolates. 92·30, 76·92, 71·15, 51·92, 51·92 and 50·00% of the isolates were resistant to ampicillin, rifampicin, imipenem, cephalothin, tetracycline and trimethoprim respectively. The multiple antibiotic resistance index values ranged from 0·28 to 0·67. PCR amplification of antimicrobial resistance genes implied the occurrence of tetracycline resistance (tetA (65·39%), tetE (25·00%) and tetB (15·38%)), plasmid-mediated quinolone resistance (qnrS (26·92%) and qnrB (17·31%)) and aminoglycoside resistance (aphaAI-IAB (7·69%) and aac (6')-Ib (3·84%)) genes in the isolates. The IntI gene was positive for 36·54% of the isolates and four class 1 integron gene cassette profiles (aadA2, qacE2-orfD, aadA2-catB2 and dfrA12-aadA2) were identified. These data suggest that ornamental guppy can be a reservoir of multidrug-resistant Aeromonas sp. which comprise different antimicrobial resistance genes and class 1 integrons. SIGNIFICANCE AND IMPACT OF THE STUDY: Antimicrobial resistance genes and integron gene cassettes of ornamental fish-borne aeromonads are poorly studied. The antimicrobial resistance patterns, antimicrobial resistance genes and class 1 integron gene cassettes of Aeromonas sp. isolated from ornamental guppy were characterized for the first time in Korea. The incidence of different antimicrobial resistance genes and class 1 integron gene cassettes were observed in multidrug-resistant Aeromonas isolates. This result suggests that better management practices are necessary to prevent and address the serious consequences of indiscriminate and inappropriate antimicrobial use, and the distribution of multidrug-resistant bacteria.

A Simple and Reliable Cooling Approach for the Cryopreservation of Hematopoietic Stem Cells: the Passive Cooling Rate-controlled Technique.

BACKGROUND: Cryopreservation of hematopoietic stem cells (HSCs) has widely been used in stem cell transplantation and cellular therapy treating various human diseases. However, the current conventional cooling approach for the cryopreservation of HSCs has the following potential problems: (1) requirement of a very expensive computer-programmed liquid nitrogen freezer (LNF) for the cooling rate control, (2) a large consumption of liquid nitrogen, (3) periodic breakdown of the LNF due to the mechanical failure of the liquid nitrogen valves (i.e., magnetic-solenoid valves) inside the LNF, and (4) constant monitoring of the LNF operation during the HSCs cooling process. OBJECTIVE: To test and evaluate a simple and reliable approach for the cryopreservation of HSCs using the passive cooling technique. MATERIALS AND METHODS: A passive cooling-rate-controlled device (PCD) was developed and used to cryopreserve HSCs. The PCD is inexpensive, simple, and user-friendly, which needs only the minimum maintenance and no consumption of liquid nitrogen. The PCD was compared to the LNF for the cryopreservation of HSCs in the present study through experiments. The cell viability and functionality were evaluated after cryopreservation. RESULTS: In comparison with the LNF method, the PCD approach enabled high cell viability/survival, recovery rate, and functionality after cryopreservation processes. CONCLUSION: The PCD offers a cost-effective, simple, and reliable approach for the optimal cryopreservation of HSCs.

High Performance Bi-2212 Round Wires Made with Recent Powders.

Multifilamentary Bi2Sr2CaCu2Ox (Bi-2212) wire made by the powder-in-tube technique is the only high temperature superconductor made in the round shape preferred by magnet builders. The critical current density (J C ) of Bi-2212 round wire was improved significantly by the development of overpressure heat treatment in the past few years. Bi-2212 wire is commercially available in multiple architectures and kilometer-long pieces and a very promising conductor for very high field NMR and accelerator magnets. We studied the effects of precursor powder and heat treatment conditions on the superconducting properties and microstructure of recent Bi-2212 wires. Short samples of recent wire with optimized overpressure processing showed J C (4.2 K, 15 T) = 6640 A/mm2 and J C (4.2 K, 30 T) = 4670 A/mm2, which correspond to engineering critical current densities J E (4.2 K, 15 T) = 1320 A/mm2 and J E (4.2 K, 30 T) = 930 A/mm2.