Avermectins are major antiparasitic agents used commercially in animal health, agriculture and human infections. To improve the fermentation efficiency of avermectins, for the first time a plasma jet ...generated by a novel atmospheric pressure glow discharge (APGD) was employed to generate mutations in Streptomyces avermitilis. The APGD plasma jet, driven by a radio frequency (RF) power supply with water-cooled and bare-metallic electrodes, was used as a new mutation method to treat the spores of S. avermitilis. The plasma jet yielded high total (over 30%) and positive (about 21%) mutation rates on S. avermitilis, and a mutated strain, designated as G1-1 with high productivity of avermectin B1a and genetic stability, was obtained. Because of the low jet temperature, the high concentrations of the chemically reactive species and the flexibility of its operation, the RF APGD plasma jet has a strong mutagenic effect on S. avermitilis. This is a proof-of-concept study for the use of an RF APGD plasma jet for inducing mutations in microbes. We have shown that the RF APGD plasma jet could be developed as a promising and convenient mutation tool for the fermentation industry and for use in biotechnology research.
Observation of ψ ( 3770 ) → η J / ψ Achasov, M. N.; Ahmed, S.; Amoroso, A. ...
Physical review. D,
05/2023, Letnik:
107, Številka:
9
Journal Article
Recenzirano
Odprti dostop
Using a data sample collected with the BESIII detector operating at the BEPCII storage ring, the Born cross section of the process e+e- → ηJ/ψ at a center-of-mass energy s=3.773 GeV is measured to be ...( 8.88±0.87±0.42 ) pb . We fit the cross section line shape before correcting for the initial state radiation from s=3.773 to 4.600 GeV to obtain the branching fraction B ( ψ ( 3770 ) → ηJ/ψ ) . We obtain B ( ψ ( 3770 ) → ηJ/ψ ) = ( 11.3±5.9±1.1 ) ×10-4 when the ψ ( 3770 ) decay amplitude is added coherently to the other contributions, and ( 8.7±1.0±0.8 ) ×10-4 when it is added incoherently. Here the quoted uncertainties are statistical and systematic, respectively. In both cases, the statistical significance of ψ ( 3770 ) resonance is above 7σ . This is the first time the decay ψ ( 3770 ) → ηJ/ψ is observed with a statistical significance greater than 5σ .
Air pollution is a major environmental concern during all seasons in the megacity of Beijing, China. Here we present the results from a winter study that was conducted from 21 November 2011 to 20 ...January 2012 with an Aerodyne Aerosol Chemical Speciation Monitor (ACSM) and various collocated instruments. The non-refractory submicron aerosol (NR-PM1) species vary dramatically with clean periods and pollution episodes alternating frequently. Compared to summer, wintertime submicron aerosols show much enhanced organics and chloride, which on average account for 52% and 5%, respectively, of the total NR-PM1 mass. All NR-PM1 species show quite different diurnal behaviors between summer and winter. For example, the wintertime nitrate presents a gradual increase during daytime and correlates well with secondary organic aerosol (OA), indicating a dominant role of photochemical production over gas–particle partitioning. Positive matrix factorization was performed on ACSM OA mass spectra, and identified three primary OA (POA) factors, i.e., hydrocarbon-like OA (HOA), cooking OA (COA), and coal combustion OA (CCOA), and one secondary factor, i.e., oxygenated OA (OOA). The POA dominates OA during wintertime, contributing 69%, with the other 31% being SOA. Further, all POA components show pronounced diurnal cycles with the highest concentrations occurring at nighttime. CCOA is the largest primary source during the heating season, on average accounting for 33% of OA and 17% of NR-PM1. CCOA also plays a significant role in chemically resolved particulate matter (PM) pollution as its mass contribution increases linearly as a function of NR-PM1 mass loadings. The SOA, however, presents a reverse trend, which might indicate the limited SOA formation during high PM pollution episodes in winter. The effects of meteorology on PM pollution and aerosol processing were also explored. In particular, the sulfate mass is largely enhanced during periods with high humidity because of fog processing of high concentration of precursor SO2. In addition, the increased traffic-related HOA emission at low temperature is also highlighted.
The focal plane camera is the core component of the Wide Field-of-view Cherenkov/fluorescence Telescope Array (WFCTA) of the Large High-Altitude Air Shower Observatory (LHAASO). Because of the ...capability of working under moonlight without aging, silicon photomultipliers (SiPM) have been proven to be not only an alternative but also an improvement to conventional photomultiplier tubes (PMT) in this application. Eighteen SiPM-based cameras with square light funnels have been built for WFCTA. The telescopes have collected more than 100 million cosmic ray events and preliminary results indicate that these cameras are capable of working under moonlight. The characteristics of the light funnels and SiPMs pose challenges (e.g. dynamic range, dark count rate, assembly techniques). In this paper, we present the design features, manufacturing techniques and performances of these cameras. Finally, the test facilities, the test methods and results of SiPMs in the cameras are reported here.
Aim To investigate the potential of iodine concentration (IC) determined using virtual monochromatic spectral computed tomography (CT) to predict the response of gastric carcinomas to preoperative ...neoadjuvant chemotherapy (NC). Materials and methods A total of 20 patients were enrolled who underwent two spectral CT examinations (1 week before and two cycles after NC). The percentage change in tumour thickness (%ΔCWT) and in IC on the arterial phase (%ΔIC-a) and venous phase (%ΔIC-v) after NC were calculated and compared for different histopathological regression grades and response groups. The diagnostic efficacies to discriminate good response (GR) and poor response (PR) of the above three parameters were evaluated using receiver operating characteristic (ROC) curves. Results The decrease rate of %ΔIC-a for the GR group was higher than that for the PR group (−0.59 −0.76, −0.20 versus −0.11 −0.75, 0.92, p =0.012). There was no significant difference in the %ΔIC-v and %ΔCWT values between the GR and PR groups ( p =0.076 and p =0.779, respectively). The areas under the ROC curve (AUC) values were 0.857, 0.762, and 0.542 for %ΔIC-a, %ΔIC-v, and %ΔCWT, respectively, in the response prediction. The cut-off value for identifying PR was a decrease rate of <52.9% for %ΔIC-a, and the sensitivity and specificity values were 0.857 and 0.833. Conclusion Changes in the IC for gastric carcinomas following NC were detected using spectral CT and correlated with histopathological regression. The prediction efficacy for IC was better than that for tumour thickness, with IC on the arterial phase being a better predictor than IC on the venous phase.
Using a data sample of
e
+
e
−
collision data corresponding to an integrated luminosity of
19
fb
−
1
collected with the BESIII detector at the BEPCII collider, we search for the production of ...deuterons and antideuterons via
e
+
e
−
→
p
p
π
−
d
¯
+
c
.
c
.
for the first time at center-of-mass energies between 4.13 and 4.70 GeV. No significant signal is observed and the upper limit of the
e
+
e
−
→
p
p
π
−
d
¯
+
c
.
c
.
cross section is determined to be from 9.0 to 145 fb depending on the center-of-mass energy at the 90% confidence level.
Published by the American Physical Society
2024
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