Antibiotic resistance characterization, virulence factors and molecular characteristics of Bacillus species isolated from probiotic preparations in China.

OBJECTIVES: The aim of this study was to determine the phenotypic and molecular characteristics of antibiotic-resistant Bacillus spp. isolated from probiotic preparations in China. METHODS: Bacillus strains were isolated from probiotic preparations and then identified using 16S rDNA sequencing. Drug sensitivity tests were conducted to determine their susceptibility to seven antibiotics. Whole genome sequencing was performed on the most resistant strains, followed by analysis of their molecular characteristics, resistance genes, and virulence factors. RESULTS: In total, we isolated 21 suspected Bacillus species from seven compound probiotics, which were identified by 16S rDNA as 12 Bacillus licheniformis, six Bacillus subtilis and three Bacillus cereus. The determination of antimicrobial susceptibility showed widespread resistance to chloramphenicol (95.2%), erythromycin (85.7%) and gentamicin (42.9%). Whole genome sequencing of seven resistant strains revealed that J-6-A (Bacillus subtilis) and J-7-A (Bacillus cereus) contained a plasmid. The resistance gene analysis revealed that each strain contained more than ten resistance genes, among which J-7-A was the most. The streptomycin resistance gene strA was detected in all strains. The chloramphenicol resistance genes ykkC and ykkD were found in J-1-A to J-5-A and were first reported in Bacillus subtilis. The erythrocin resistance gene ermD was detected in strains J-1-A to J-4-A. There were also more than 15 virulence factors and gene islands (GIs) involved in each strain. CONCLUSIONS: These results confirm the potential safety risks of probiotics and remind us to carefully select probiotic preparations containing strains of Bacillus species, especially Bacillus cereus, to avoid the potential spread of resistance and pathogenicity.

Reduction of Backward Scatterings at the Low-Coherence Kunwu Laser Facility.

We report the first experimental observation on the reduction of backward scatterings by an instantaneous broadband laser with 0.6% bandwidth in conditions of interest for inertial confinement fusion at the low-coherence Kunwu laser facility. The backscatter of stimulated Brillouin scattering (SBS) was robustly reduced by half at intensities of 1-5×10^{14} W/cm^{2} with the 0.53-µm broadband laser in comparison with the monochromatic laser. As SBS dominates energy loss of laser-plasma interactions, the reduction of that demonstrates the enhancement of laser-target coupling by the use of broadband laser. The mitigation of filamentation leads to the reduction of stimulated Raman backscattering at low intensities. In addition, the three-halves harmonic emission was reduced with the broadband laser as well.

Antibiotic Resistance Characterization and Molecular Characteristics of Enterococcus Species Isolated from Combination Probiotic Preparations in China.

Enterococci can act as reservoirs for antibiotic-resistant genes that are potentially at risk of being transferred to other bacteria that inhabit in the gastrointestinal tract. The aim of this study was to determine the phenotypic and molecular characteristics of antibiotic-resistant enterococci isolated from probiotic preparations. In total, we isolated 15 suspected Enterococcus species from 5 compound probiotics, which were identified by 16S rDNA as 12 Enterococcus faecium and 3 Enterococcus faecalis. Determination of antimicrobial susceptibility by the microdilution broth method showed widespread resistance to sulfamethoxazole (100%), norfloxacin (99.3%), azithromycin (99.3%), gentamicin (86.7%), and chloramphenicol (20%). Whole genome sequencing of five resistant strains revealed that all had circular DNA chromosomes and that E. faecium J-1-A to J-4-A contained a plasmid, while E. faecalis J-5-A did not. The results of the resistance gene analysis revealed that each strain contained approximately 30 resistance genes, with the antibiotic resistance genes and the multidrug resistance efflux pump genes mdtG, lmrC, and lmrD detected in all strains. The chloramphenicol resistance genes ykkC and ykkD were first identified in E. faecalis. And there were 21, 19, 21, 21, and 29 virulence factors involved in strains, respectively. Further analysis of the gene islands (GIs) revealed that each strain contained more than 10 GIs. The above results confirm the existence of hidden dangers in the safety of probiotics and remind us to carefully select probiotic preparations containing enterococcal strains to avoid the potential spread of resistance and pathogenicity.

Study on the Gamma Irradiation Characteristics of a Carbon Nanotube Sponge/Polydimethylsiloxane/Tungsten Oxide Flexible Force-Sensitive Structure.

This paper proposes a new type of flexible force-sensitive structure that is resistant to gamma radiation and is made of tungsten oxide (WO3) powder, polydimethylsiloxane (PDMS), and carbon nanotube (CNT) sponge. The thickness of the sample was 2.2 mm, the middle interlayer was composed of a carbon nanotube (CNT) sponge and PDMS to form a conductive layer, and the upper and lower layers were made of tungsten oxide and PDMS, which formed a gamma-ray shielding layer. When the particle size of the tungsten oxide powder was 50 nm, 100 nm, and 1 µm, the composite force-sensitive structure exhibited better force-sensitive performance. The composite force-sensitive structure was irradiated with doses of 5, 20, 50, and 100 KGy through 60Co- rays with an energy of 1.25 MeV. The results showed that the force-sensitive characteristics changed little in significance after irradiation by different doses of gamma rays, indicating that the force-sensitive structure has good resistance to gamma radiation. This flexible stress sensor can be used in soft robots and health inspection, even in harsh environments without significant performance loss.

Research on the High Sensitivity Detection Method of Carbon Nanotube/Polydimethylsiloxane Composites Structure.

In this paper, a carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite force-sensitive structure with good flexibility is proposed and fabricated, and the measurement of scanning electron microscopy (SEM) and Raman are carried out. The equivalent circuit of force-sensitive test of structure is performed and analyzed under direct current (DC) and alternating current (AC) conditions. Under AC conditions, experimental results further show that the sensitivity and sensitivity factors of force-sensitive structures are 0.15 KPa-1 and 2.17 in the pressure range of 600-1000 KPa compressive stress and 20-50% tensile stress, respectively. These results are increased by 36.4% and 38.2% compared to the results of compressive stress (0.11 KPa-1) and tensile stress (1.57) under DC conditions, respectively. It shows that the carbon nanotube/PDMS composite has higher test accuracy under AC conditions.

Double-spherically bent crystal scheme of stigmatic x ray monochromatic backlit imaging.

We propose an aberration-free monochromatic x ray backlit imaging scheme using a combination of convex and concave spherically bent crystals. This configuration works with a wide range of Bragg angles, satisfying the conditions for stigmatic imaging at a particular wavelength. However, the assembly accuracy of the crystals must meet the Bragg relation criteria for spatial resolution to increase the detection efficiency. Here, we develop a collimator prism with a cross reference line engraved on a plane mirror to adjust a matched pair of Bragg angles as well as the intervals between the two crystals and the object to be coupled with the detector. We explore the realization of monochromatic backlighting imaging with a concave Si-533 crystal and a convex α-Quartz-2023 crystal, obtaining a spatial resolution of approximately 7 µm and a field of view of at least 200 µm. To the best of our knowledge, this is the best spatial resolution of monochromatic images of a double-spherically bent crystal to date. Our experimental results are presented to demonstrate the feasibility of this imaging scheme with x rays.

Research on the Force-Sensitive Characteristic of InAs QD Embedded in HEMT.

A force-sensitive structure of an InAs Quantum Dot (QD) embedded in a high electron mobility transistor (HEMT) is presented in this paper. The size of an InAs QD is about 30 nm prepared by the S-K growth mode, and the force-sensitive structure is fabricated by molecular beam epitaxy (MBE). The force-sensitivity characteristic of the QD HEMT is studied by the electrical and mechanical properties. The electrical characteristics show that the InAs QD-HEMT has linear, cut-off, and saturation operating states, and produces different output currents under different gate voltages, which shows that the structure is reasonable. Furthermore, the results of the output characteristics under different pressure show that the output voltage of the QD-HEMT decreases with the increase in pressure, which indicates that the InAs QD-HEMT has a vital mechanical-electrical coupling characteristic. The output voltage of the InAs QD-HEMT in the range of 0-100 kPa shows that the sensitivity was 1.09 mV/kPa.

Determining Surface Shape of Translucent Objects with the Combination of Laser-Beam-Based Structured Light and Polarization Technique.

In this study, we focus on the 3D surface measurement and reconstruction of translucent objects. The proposed approach of surface-shape determination of translucent objects is based on the combination of the projected laser-beam-based sinusoidal structured light and the polarization technique. The theoretical analyses are rigorously completed in this work, including the formation, propagation, and physical features of the generated sinusoidal signal by the designed optical system, the reflection and transmission of the projected monochromatic fringe pattern on the surface of the translucent object, and the formation and the separation of the direct-reflection and the global components of the surface radiance of the observed object. The results of experimental investigation designed in accordance with our theoretical analyses have confirmed that accurate reconstructions can be obtained using the one-shot measurement based on the proposed approach of this study and Fourier transform profilometry, while the monochromaticity and the linearly-polarized characteristic of the projected sinusoidal signal can be utilized by using a polarizer and an optical filter simultaneously for removing the global component, i.e., the noised signal contributed by multiply-scattered photons and the background illuminance in the frame of our approach. Moreover, this study has also revealed that the developed method is capable of getting accurate measurements and reconstructions of translucent objects when the background illumination exists, which has been considered as a challenging issue for 3D surface measurement and reconstruction of translucent objects.

Excavation Equipment Recognition Based on Novel Acoustic Statistical Features.

Excavation equipment recognition attracts increasing attentions in recent years due to its significance in underground pipeline network protection and civil construction management. In this paper, a novel classification algorithm based on acoustics processing is proposed for four representative excavation equipments. New acoustic statistical features, namely, the short frame energy ratio, concentration of spectrum amplitude ratio, truncated energy range, and interval of pulse are first developed to characterize acoustic signals. Then, probability density distributions of these acoustic features are analyzed and a novel classifier is presented. Experiments on real recorded acoustics of the four excavation devices are conducted to demonstrate the effectiveness of the proposed algorithm. Comparisons with two popular machine learning methods, support vector machine and extreme learning machine, combined with the popular linear prediction cepstral coefficients are provided to show the generalization capability of our method. A real surveillance system using our algorithm is developed and installed in a metro construction site for real-time recognition performance validation.

Design of a TDOA location engine and development of a location system based on chirp spread spectrum.

Location based services (LBS) provided by wireless sensor networks have garnered a great deal of attention from researchers and developers in recent years. Chirp spread spectrum (CSS) signaling formatting with time difference of arrival (TDOA) ranging technology is an effective LBS technique in regards to positioning accuracy, cost, and power consumption. The design and implementation of the location engine and location management based on TDOA location algorithms were the focus of this study; as the core of the system, the location engine was designed as a series of location algorithms and smoothing algorithms. To enhance the location accuracy, a Kalman filter algorithm and moving weighted average technique were respectively applied to smooth the TDOA range measurements and location results, which are calculated by the cooperation of a Kalman TDOA algorithm and a Taylor TDOA algorithm. The location management server, the information center of the system, was designed with Data Server and Mclient. To evaluate the performance of the location algorithms and the stability of the system software, we used a Nanotron nanoLOC Development Kit 3.0 to conduct indoor and outdoor location experiments. The results indicated that the location system runs stably with high accuracy at absolute error below 0.6 m.

Evaluation of gastric fundic and oesophageal varices by 64-row multidetector computed tomography before and after transjugular intrahepatic portosystemic shunt with concurrent left gastric vein embolization.

OBJECTIVE: To determine the utility of 64-row multidetector computed tomography (MDCT) in assessing the changes of gastric fundic and oesophageal varices before and after transjugular intrahepatic portosystemic shunt (TIPS) with concurrent left gastric vein embolization. METHODS: Twenty-eight consecutive patients with gastric fundic and oesophageal varices resulted from posthepatitic cirrhosis, clinically confirmed with endoscopy, were enrolled into our study. All the patients underwent thoracicoabdominal triphasic enhancement scans with 64-row MDCT 2 weeks before TIPS along with embolizing left gastric vein, and 6 months after the therapy. Before and after the therapy, the varices shown on multiplanar reconstruction (MPR) were compared by Fisher's exact test to evaluate the changes. RESULTS: Gastric fundic and oesophageal varices were shown in 26 patients (92.9%) and 25 (89.3%) on MPR before the therapy, respectively. After the therapy, these varices diminished markedly, and were illustrated in six (21.4%) and 10 patients (35.7%), respectively (all P<0.05). As for the main inflowing vessel of the varices (left gastric vein), it was illustrated in 28 patients (100.0%) on preoperative CT-MPR. After the embolization, the left gastric vein had been completely occluded on postoperative CT-MPR. CONCLUSION: Significant eradication of gastric fundic and oesophageal varices on follow-up CT-MPR portography can be considered to assess the changes of gastric fundic and oesophageal varices before and after TIPS with concurrent left gastric vein embolization, and 64-row MDCT can be an effective modality to evaluate the changes.

Evaluation of entire gastric fundic and esophageal varices secondary to posthepatitic cirrhosis: portal venography using 64-row MDCT.

BACKGROUND: There are no reports regarding entire gastric fundic and esophageal varices evaluated with 64-row multidetector CT (MDCT). We attempt to clarify the feasibility of portal venography with this scanner in evaluation of these varices. METHODS: A total of 33 patients, with clinically confirmed gastric fundic and esophageal varices secondary to posthepatitic cirrhosis, underwent thoracicoabdominal triphasic enhancement scans using 64-row MDCT along with conventional angiographic portography. CT portography and conventional portography were compared by statistical agreement to determine whether CT maximum intensity projection (CT-MIP) portography is useful in evaluation of entire gastric fundic and esophageal varices. RESULTS: CT-MIP portography demonstrated gastric fundic and esophageal varices, and the inflowing and outflowing vessels of the varices. Gastric fundic varices were shown in 32 cases (97.0%), and esophageal varices were in 27 (81.8%). The inflowing vessels including the left gastric vein and posterior gastric vein/short gastric vein were illustrated in 31 (94.0%) and 17 (51.5%) cases, respectively. The outflowing vessels including the azygos vein, hemiazygos vein, and gastro-renal shunts were seen in 30 (90.9%), 8 (24.2%), and 12 (36.4%) cases, respectively. Findings of CT-MIP portography and conventional angiographic portography were in close agreement (Kappa value ranged from 0.621 to 1.000). CONCLUSION: CT-MIP venography with 64-row MDCT could be considered as a method for detecting entire gastric fundic and esophageal varices developed from posthepatitic cirrhosis.

[Clinical value of 64-slice CT angiography in detecting coronary artery anomalies].

OBJECTIVE: To determine the clinical value of 64-slice computed tomography angiography (CTA) in the diagnosis of coronary artery anomalies. METHODS: The coronary artery imaging data of 852 patients who underwent 64-slice CTA from July 2006 to May 2007 were retrieved. The imaging features of coronary artery anomalies confirmed by selective coronary angiography were reviewed. RESULTS: Eight (0.9%) coronary artery anomalies were found in the patients, which included 3 cases of anomalous aortic origin of coronary arteries, 3 cases of anomalous origin of the left main coronary artery from pulmonary artery, 1 case of coronary fistula from the right coronary artery to right atrium, and 1 case of coronary aneurysm. CONCLUSION: The 64-slice CTA can detect coronary anomalies and delineate the anatomic relationships among the peripheral structures, which can be considered as an early screening for coronary anomalies.