Eco-Friendly Synthesis of Silver Nanoparticles Using Pulsed Plasma in Liquid: Effect of Surfactants

Silver (Ag) nanoparticles were successfully prepared by using the in-liquid pulsed plasma technique. This method is based on a low voltage, pulsed spark discharge in a dielectric liquid. We explore the effect of the protecting ligands, specifically Cetyl Trimethylammonium Bromide (CTAB), Polyvinylpyrrolidone (PVP), and Sodium n-Dodecyl Sulphate (SDS), used as surfactant materials to prevent nanoparticle aggregation. The X-Ray Diffraction (XRD) patterns of the samples confirm the face-centered cubic crystalline structure of Ag nanoparticles with the presence of Ag2O skin. Scanning Transmission Electron Microscopy (STEM) reveals that spherically shaped Ag nanoparticles with a diameter of 2.2 ± 0.8 nm were synthesised in aqueous solution with PVP surfactant. Similarly, silver nanoparticles with a peak diameter of 1.9 ± 0.4 nm were obtained with SDS surfactant. A broad size distribution was found in the case of CTAB surfactant

Characterization and Fungicide Screening of a New Pathogen That Causes Leaf Spot on Rehmannia glutinosa

Outbreaks of leaf spot disease occurred in Rehmannia glutinosa fields in Henan Province, China, in 2019, with the incidence ranging from 20% to 40%. R. glutinosa plants with diseased leaves were collected, and 25 isolates were obtained. Pathogenicity tests, morphological observations, and phylogenetic analyses were conducted to identify the pathogens, and the biological characteristics and control agents of the pathogens were studied. Five isolates of pathogenic fungi were isolated. Three isolates were identified as Fusarium equiseti, which is a new pathogen causing R. glutinosa leaf disease; the other two isolates were identified as Fusarium acuminatum. The mycelia of F. equiseti grew fastest on Czapek medium, and the optimal temperature and pH were 25 °C and 10.0, respectively. The mycelia of F. equiseti grew from 5 °C t o 35 °C, and the lethal temperature was 55 °C. The optimal carbon and nitrogen sources were soluble starch and peptone, respectively. Eight fungicides had inhibitory effects on the mycelial growth of F. equiseti and F. acuminatum. Prochloraz had higher activities against F. equiseti and F. acuminatum, with EC50 values of 0.139 mg·L−1 and 0.123 mg·L−1, respectively. These results provide useful information that will aid the development of management strategies to control leaf diseases of R. glutinosa caused by F. equiseti and F. acuminatum

Characterization and Fungicide Screening of a New Pathogen That Causes Leaf Spot on <i>Rehmannia glutinosa</i>

Outbreaks of leaf spot disease occurred in Rehmannia glutinosa fields in Henan Province, China, in 2019, with the incidence ranging from 20% to 40%. R. glutinosa plants with diseased leaves were collected, and 25 isolates were obtained. Pathogenicity tests, morphological observations, and phylogenetic analyses were conducted to identify the pathogens, and the biological characteristics and control agents of the pathogens were studied. Five isolates of pathogenic fungi were isolated. Three isolates were identified as Fusarium equiseti, which is a new pathogen causing R. glutinosa leaf disease; the other two isolates were identified as Fusarium acuminatum. The mycelia of F. equiseti grew fastest on Czapek medium, and the optimal temperature and pH were 25 °C and 10.0, respectively. The mycelia of F. equiseti grew from 5 °C t o 35 °C, and the lethal temperature was 55 °C. The optimal carbon and nitrogen sources were soluble starch and peptone, respectively. Eight fungicides had inhibitory effects on the mycelial growth of F. equiseti and F. acuminatum. Prochloraz had higher activities against F. equiseti and F. acuminatum, with EC50 values of 0.139 mg·L−1 and 0.123 mg·L−1, respectively. These results provide useful information that will aid the development of management strategies to control leaf diseases of R. glutinosa caused by F. equiseti and F. acuminatum.</i

Measurements of jet quenching using semi-inclusive hadron+jet distributions in pp and central Pb−-Pb collisions at sNN=5.02\sqrt{s_{\rm NN}}=5.02 TeV

The ALICE Collaboration reports measurements of the semi-inclusive distribution of charged-particle jets recoiling from a high transverse momentum (high $p_{\rm T}$) charged hadron, in pp and central Pb$-$Pb collisions at center of mass energy per nucleon$-$nucleon collision $\sqrt{s_{\rm NN}}=5.02$ TeV. The large uncorrelated background in central Pb$-$Pb collisions is corrected using a data-driven statistical approach, which enables precise measurement of recoil jet distributions over a broad range in $p_{\rm T,ch\,jet}$ and jet resolution parameter $R$. Recoil jet yields are reported for $R=0.2$, 0.4, and 0.5 in the range $7 < p_{\rm T,ch\, jet} < 140$ GeV$/c$ and $\pi/2<\Delta\varphi<\pi$, where $\Delta\varphi$ is the azimuthal angular separation between hadron trigger and recoil jet. The low $p_{\rm T,ch\,jet}$ reach of the measurement explores unique phase space for studying jet quenching, the interaction of jets with the quark-gluonnplasma generated in high-energy nuclear collisions. Comparison of $p_{\rm T,ch\,jet}$ distributions from pp and central Pb$-$Pb collisions probes medium-induced jet energy loss and intra-jet broadening, while comparison of their acoplanarity distributions explores in-medium jet scattering and medium response. The measurements are compared to theoretical calculations incorporating jet quenching.The ALICE Collaboration reports measurements of the semi-inclusive distribution of charged-particle jets recoiling from a high transverse momentum (high $p_{\rm T}$) charged hadron, in pp and central Pb$-$Pb collisions at center of mass energy per nucleon$-$nucleon collision $\sqrt{s_{\rm NN}}=5.02$ TeV. The large uncorrelated background in central Pb$-$Pb collisions is corrected using a data-driven statistical approach, which enables precise measurement of recoil jet distributions over a broad range in $p_{\rm T,ch\,jet}$ and jet resolution parameter $R$. Recoil jet yields are reported for $R=0.2$, 0.4, and 0.5 in the range $7 < p_{\rm T,ch\, jet} < 140$ GeV$/c$ and $\pi/2<\Delta\varphi<\pi$, where $\Delta\varphi$ is the azimuthal angular separation between hadron trigger and recoil jet. The low $p_{\rm T,ch\,jet}$ reach of the measurement explores unique phase space for studying jet quenching, the interaction of jets with the quark-gluonnplasma generated in high-energy nuclear collisions. Comparison of $p_{\rm T,ch\,jet}$ distributions from pp and central Pb$-$Pb collisions probes medium-induced jet energy loss and intra-jet broadening, while comparison of their acoplanarity distributions explores in-medium jet scattering and medium response. The measurements are compared to theoretical calculations incorporating jet quenching

Dielectron production in central Pb−-Pb collisions at sNN\sqrt{s_\mathrm{NN}} = 5.02 TeV

International audienceThe first measurement of the e$^+$e$^-$ pair production at midrapidity and low invariant mass in central Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV at the LHC is presented. The yield of e$^+$e$^-$ pairs is compared with a cocktail of expected hadronic decay contributions in the invariant mass ($m_{\rm ee}$) and pair transverse momentum ($p_{\rm T,ee}$) ranges $m_{\rm ee} < 3.5$ GeV$/c^2$ and $p_{\rm T,ee} < 8$ GeV$/c$. For $0.18 < m_{\rm ee} < 0.5$ GeV$/c^2$ the ratio of data to the cocktail of hadronic contributions without $\rho$ mesons amounts to $1.42 \pm 0.12 \ ({\rm stat.}) \pm 0.17 \ ({\rm syst.}) \pm 0.12 \ ({\rm cocktail})$ and $1.44 \pm 0.12 \ ({\rm stat.}) \pm 0.17 \ ({\rm syst.}) ^{+0.17}_{-0.21} \ ({\rm cocktail})$, including or not including medium effects in the estimation of the heavy-flavor background, respectively. It is consistent with predictions from two different models for an additional contribution of thermal e$^+$e$^-$ pairs from the hadronic and partonic phases. In the intermediate-mass range ($1.2 < m_{\rm ee} < 2.6$ GeV$/c^2$), the pair transverse impact parameter of the e$^+$e$^-$ pairs (DCA$_{\rm ee}$) is used for the first time in Pb$-$Pb collisions to separate displaced dielectrons from heavy-flavor hadron decays from a possible (thermal) contribution produced at the interaction point. The data are consistent with a suppression of e$^+$e$^-$ pairs from ${\rm c\overline{c}}$ and an additional prompt component. Finally, the first direct-photon measurement in the 10% most central Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV is reported via the study of virtual direct photons in the transverse momentum range $1 < p_{\rm T} < 5$ GeV$/c$. A model including prompt photons, as well as photons from the pre-equilibrium and fluid-dynamic phases, can reproduce the result, while being at the upper edge of the data uncertainties

System size dependence of hadronic rescattering effect at LHC energies

International audienceThe first measurements of $\mathrm{K^{*}(892)^{0}}$ resonance production as a function of charged-particle multiplicity in Xe$-$Xe collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.44 TeV and pp collisions at $\sqrt{s}=$ 5.02 TeV using the ALICE detector are presented. The resonance is reconstructed at midrapidity ($|y|< 0.5$) using the hadronic decay channel $\mathrm{K^{*0}} \rightarrow \mathrm{K^{\pm} \pi^{\mp}}$. Measurements of transverse-momentum integrated yield, mean transverse-momentum, nuclear modification factor of $\mathrm{K^{*0}}$, and yield ratios of resonance to stable hadron ($\mathrm{K^{*0}}$/K) are compared across different collision systems (pp, p$-$Pb, Xe$-$Xe, and Pb$-$Pb) at similar collision energies to investigate how the production of $\mathrm{K^{*0}}$ resonances depends on the size of the system formed in these collisions. The hadronic rescattering effect is found to be independent of the size of colliding systems and mainly driven by the produced charged-particle multiplicity, which is a proxy of the volume of produced matter at the chemical freeze-out. In addition, the production yields of $\mathrm{K^{*0}}$ in Xe$-$Xe collisions are utilized to constrain the dependence of the kinetic freeze-out temperature on the system size using HRG-PCE model

Measurement of inclusive charged-particle jet production in pp and p-Pb collisions at sNN=5.02\sqrt{s_{\rm NN}}=5.02 TeV

International audienceMeasurements of inclusive charged-particle jet production in pp and p-Pb collisions at center-of-mass energy per nucleon-nucleon collision $\sqrt{s_{\rm NN}} = 5.02$ TeV and the corresponding nuclear modification factor $R_{\rm pPb}^{\rm ch\,jet}$ are presented, using data collected with the ALICE detector at the LHC. Jets are reconstructed in the central rapidity region $|\eta_{\rm jet}| < 0.5$ from charged particles using the anti-$k_{\rm T}$ algorithm with resolution parameters $R = 0.2$, 0.3, and 0.4. The $p_{\rm T}$-differential inclusive production cross section of charged-particle jets, as well as the corresponding cross-section ratios, are reported for pp and p-Pb collisions in the transverse momentum range $10 < p^{\rm ch}_{\rm T,jet} < 140$ GeV/$c$ and $10 < p^{\rm ch}_{\rm T,jet} < 160$ GeV/$c$, respectively, together with the nuclear modification factor $R_{\rm pPb}^{\rm ch\,jet}$ in the range $10 < p^{\rm ch}_{\rm T,jet} < 140$ GeV/$c$. The analysis extends the $p_{\rm T}$ range of the previously-reported charged-particle jet measurements by the ALICE Collaboration. The nuclear modification factor is found to be consistent with one and independent of the jet resolution parameter with the improved precision of this study, indicating that the possible influence of cold nuclear matter effects on the production cross section of charged-particle jets in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV is smaller than the current precision. The obtained results are in agreement with other minimum bias jet measurements available for RHIC and LHC energies, and are well reproduced by the NLO perturbative QCD POWHEG calculations with parton shower provided by PYTHIA8 as well as by JETSCAPE simulations

Studying strangeness and baryon production mechanisms through angular correlations between charged Ξ\Xi baryons and identified hadrons in pp collisions at s\sqrt{s} = 13 TeV

International audienceThe angular correlations between charged $\Xi$ baryons and associated identified hadrons (pions, kaons, protons, $\Lambda$ baryons, and $\Xi$ baryons) are measured in pp collisions at $\sqrt{s} = 13$ TeV with the ALICE detector to give insight into the particle production mechanisms and balancing of quantum numbers on the microscopic level. In particular, the distribution of strangeness is investigated in the correlations between the doubly-strange $\Xi$ baryon and mesons and baryons that contain a single strange quark, K and $\Lambda$. As a reference, the results are compared to $\Xi\pi$ and $\Xi\mathrm{p}$ correlations, where the associated mesons and baryons do not contain a strange valence quark. These measurements are expected to be sensitive to whether strangeness is produced through string breaking or in a thermal production scenario. Furthermore, the multiplicity dependence of the correlation functions is measured to look for the turn-on of additional particle production mechanisms with event activity. The results are compared to predictions from the string-breaking model PYTHIA 8, including tunes with baryon junctions and rope hadronisation enabled, the cluster hadronisation model HERWIG 7, and the core-corona model EPOS-LHC. While some aspects of the experimental data are described quantitatively or qualitatively by the Monte Carlo models, no one model can match all features of the data. These results provide stringent constraints on the strangeness and baryon number production mechanisms in pp collisions

Common femtoscopic hadron-emission source in pp collisions at the LHC

International audienceThe femtoscopic study of pairs of identical pions is particularly suited to investigate the effective source function of particle emission, due to the resulting Bose-Einstein correlation signal. In small collision systems at the LHC, pp in particular, the majority of the pions are produced in resonance decays, which significantly affect the profile and size of the source. In this work, we explicitly model this effect in order to extract the primordial source in pp collisions at $\sqrt{s} = 13$ TeV from charged $\pi$-$\pi$ correlations measured by ALICE. We demonstrate that the assumption of a Gaussian primordial source is compatible with the data and that the effective source, resulting from modifications due to resonances, is approximately exponential, as found in previous measurements at the LHC. The universality of hadron emission in pp collisions is further investigated by applying the same methodology to characterize the primordial source of K-p pairs. The size of the primordial source is evaluated as a function of the transverse mass ($m_{\rm T}$) of the pairs, leading to the observation of a common scaling for both $\pi$-$\pi$ and K-p, suggesting a collective effect. Further, the present results are compatible with the $m_{\rm T}$ scaling of the p-p and p$-\Lambda$ primordial source measured by ALICE in high multiplicity pp collisions, providing compelling evidence for the presence of a common emission source for all hadrons in small collision systems at the LHC. This will allow the determination of the source function for any hadron--hadron pairs with high precision, granting access to the properties of the possible final-state interaction among pairs of less abundantly produced hadrons, such as strange or charmed particles