807 research outputs found
Efficacy of single pass UVC air treatment for the inactivation of coronavirus, MS2 coliphage and Staphylococcus aureus bioaerosols
Publication history: Accepted - 20 April 2022; Published online - 26 April 2022There is strong evidence that SARS-CoV-2 is spread predominantly by airborne transmission, with high viral loads released into the air as respiratory droplets and aerosols from the infected subject. The spread and persistence of SARS-CoV-2 in diverse indoor environments reinforces the urgent need to supplement distancing and PPE based approaches with effective engineering measures for microbial decontamination – thereby addressing the significant risk posed by aerosols. We hypothesized that a portable, single-pass UVC air treatment device (air flow 1254 L/min) could effectively inactivate bioaerosols containing bacterial and viral indicator organisms, and coronavirus without reliance on filtration technology, at reasonable scale. Robust experiments demonstrated UVC dose dependent inactivation of Staphylococcus aureus (UV rate constant (k) = 0.098 m2/J) and bacteriophage MS2, with up to 6-log MS2 reduction achieved in a single pass through the system (k = 0.119 m2/J). The inclusion of a PTFE diffuse reflector increased the effective UVC dose by up to 34% in comparison to a standard Al foil reflector (with identical lamp output), resulting in significant additional pathogen inactivation (1-log S. aureus and MS2, p < 0.001). Complete inactivation of bovine coronavirus bioaerosols was demonstrated through tissue culture infectivity (2.4-log reduction) and RT-qPCR analysis – confirming single pass UVC treatment to effectively deactivate coronavirus to the limit of detection of the culture-based method. Scenario-based modelling was used to investigate the reduction in risk of airborne person-to-person transmission based upon a single infected subject within the small room. Use of the system providing 5 air changes per hour was shown to significantly reduce airborne viral load and maintain low numbers of RNA copies when the infected subject remained in the room, reducing the risk of airborne pathogen transmission to other room users. We conclude that the application of single-pass UVC systems (without reliance on HEPA filtration) could play a critical role in reducing the risk of airborne pathogen transfer, including SARS-CoV2, in locations where adequate fresh air ventilation cannot be implemented.This research was partly funded through the Invest Northern Ireland Innovation Voucher Programme (IV130218200 and IV130232906). We are grateful to the Global Challenges Research Fund (GCRF) UK Research and Innovation (SAFEWATER; EPSRC Grant Reference EP/P032427/1) for supporting Mr Arsalan Afkhami, Dr William J Snelling and Dr Jeremy W.J. Hamilton. Research at AFBI is funded by US-Ireland Research and Development Partnership in Agriculture grants BRDC-Seq and BRDC-URTMVP. We wish to thank Jonathan McMaw at AFBI for acquisition of images
Structural identification and biological activity of 7-methyl-10,11-ethylenedioxy-20(S)-camptothecin, a photodegradant of lurtotecan
An additional chromatographic peak was observed in plasma samples of
patients receiving NX 211, a liposomal formulation of the topoisomerase I
inhibitor lurtotecan. We have isolated and purified this product by
sequential solid-phase extractions, and we report its structure and
cytotoxicity relative to lurtotecan and related agents. Nuclear magnetic
resonance data indicate that cleavage of the piperazino moiety occurred at
the N-C bond of the B-ring, yielding
7-methyl-10,11-ethylenedioxy-20(S)-camptothecin (MEC). Tests of the growth
inhibition potential of MEC in seven human tumor cell lines showed that
the compound was approximately 2-18-fold more cytotoxic than lurtotecan,
topotecan, and 7-ethyl-10-hydroxy-20(S)-camptothecin (SN-38).
Subsequently, we found that MEC was the product of rapid photolysis of
lurtotecan, with the rate of degradation inversely proportional to NX 211
concentrations, and greatly depends on light intensity. Furthermore, MEC
concentrations were found to increase significantly in plasma samples
exposed to laboratory light but not in blood. MEC was not produced from NX
211 in the presence of human liver microsomes, suggesting that it is not a
product of cytochrome P-450 metabolism. Using a validated analytical
method, trace levels of MEC were quantitated in blood samples of two
patients. These observations confirm that the precautions for protection
from light currently specified for preparation and administration of NX
211 dose solutions are critical. Procedures to minimize formation of MEC,
by the use of amber vials for NX 211 and by preparation of dilutions
immediately before clinical use in a fashion completely protected from
light, are now being routinely implemented
Large-scale periodicity in the distribution of QSO absorption-line systems
The spatial-temporal distribution of absorption-line systems (ALSs) observed
in QSO spectra within the cosmological redshift interval z = 0.0--4.3 is
investigated on the base of our updated catalog of absorption systems. We
consider so called metallic systems including basically lines of heavy
elements. The sample of the data displays regular variations (with amplitudes ~
15 -- 20%) in the z-distribution of ALSs as well as in the eta-distribution,
where eta is a dimensionless line-of-sight comoving distance, relatively to
smoother dependences. The eta-distribution reveals the periodicity with period
Delta eta = 0.036 +/- 0.002, which corresponds to a spatial characteristic
scale (108 +/- 6) h(-1) Mpc or (alternatively) a temporal interval (350 +/- 20)
h(-1) Myr for the LambdaCDM cosmological model. We discuss a possibility of a
spatial interpretation of the results treating the pattern obtained as a trace
of an order imprinted on the galaxy clustering in the early Universe.Comment: AASTeX, 13 pages, with 9 figures, Accepted for publication in
Astrophysics & Space Scienc
Field-testing solutions for drinking water quality monitoring in low- and middle-income regions and case studies from Latin American, African and Asian countries
Funding Information: This study is part of SAFEWATER Devices Translation and Implementation project supported by the Global Challenges Research Fund ( GCRF ) Global Research Translation Awards, UK Research and Innovation ( SAFEWATER Translate, EPSRC Grant Reference EP/T015470/1 ).Peer reviewedPublisher PD
Efficacy of single pass UVC air treatment for the inactivation of coronavirus, MS2 coliphage and Staphylococcus aureus bioaerosols
Publication history: Accepted - 20 April 2022; Published online - 26 April 2022There is strong evidence that SARS-CoV-2 is spread predominantly by airborne transmission, with high viral loads released into the air as respiratory droplets and aerosols from the infected subject. The spread and persistence of SARS-CoV-2 in diverse indoor environments reinforces the urgent need to supplement distancing and PPE based approaches with effective engineering measures for microbial decontamination – thereby addressing the significant risk posed by aerosols. We hypothesized that a portable, single-pass UVC air treatment device (air flow 1254 L/min) could effectively inactivate bioaerosols containing bacterial and viral indicator organisms, and coronavirus without reliance on filtration technology, at reasonable scale. Robust experiments demonstrated UVC dose dependent inactivation of Staphylococcus aureus (UV rate constant (k) = 0.098 m2/J) and bacteriophage MS2, with up to 6-log MS2 reduction achieved in a single pass through the system (k = 0.119 m2/J). The inclusion of a PTFE diffuse reflector increased the effective UVC dose by up to 34% in comparison to a standard Al foil reflector (with identical lamp output), resulting in significant additional pathogen inactivation (1-log S. aureus and MS2, p < 0.001). Complete inactivation of bovine coronavirus bioaerosols was demonstrated through tissue culture infectivity (2.4-log reduction) and RT-qPCR analysis – confirming single pass UVC treatment to effectively deactivate coronavirus to the limit of detection of the culture-based method. Scenario-based modelling was used to investigate the reduction in risk of airborne person-to-person transmission based upon a single infected subject within the small room. Use of the system providing 5 air changes per hour was shown to significantly reduce airborne viral load and maintain low numbers of RNA copies when the infected subject remained in the room, reducing the risk of airborne pathogen transmission to other room users. We conclude that the application of single-pass UVC systems (without reliance on HEPA filtration) could play a critical role in reducing the risk of airborne pathogen transfer, including SARS-CoV2, in locations where adequate fresh air ventilation cannot be implemented.This research was partly funded through the Invest Northern Ireland Innovation Voucher Programme (IV130218200 and IV130232906). We are grateful to the Global Challenges Research Fund (GCRF) UK Research and Innovation (SAFEWATER; EPSRC Grant Reference EP/P032427/1) for supporting Mr Arsalan Afkhami, Dr William J Snelling and Dr Jeremy W.J. Hamilton. Research at AFBI is funded by US-Ireland Research and Development Partnership in Agriculture grants BRDC-Seq and BRDC-URTMVP. We wish to thank Jonathan McMaw at AFBI for acquisition of images
Extended M1 sum rule for excited symmetric and mixed-symmetry states in nuclei
A generalized M1 sum rule for orbital magnetic dipole strength from excited
symmetric states to mixed-symmetry states is considered within the
proton-neutron interacting boson model of even-even nuclei. Analytic
expressions for the dominant terms in the B(M1) transition rates from the first
and second states are derived in the U(5) and SO(6) dynamic symmetry
limits of the model, and the applicability of a sum rule approach is examined
at and in-between these limits. Lastly, the sum rule is applied to the new data
on mixed-symmetry states of 94Mo and a quadrupole d-boson ratio
is obtained in a largely
parameter-independent wayComment: 19 pages, 3 figures, Revte
A Model for the Development of the Rhizobial and Arbuscular Mycorrhizal Symbioses in Legumes and Its Use to Understand the Roles of Ethylene in the Establishment of these two Symbioses
We propose a model depicting the development of nodulation and arbuscular mycorrhizae. Both processes are dissected into many steps, using Pisum sativum L. nodulation mutants as a guideline. For nodulation, we distinguish two main developmental programs, one epidermal and one cortical. Whereas Nod factors alone affect the cortical program, bacteria are required to trigger the epidermal events. We propose that the two programs of the rhizobial symbiosis evolved separately and that, over time, they came to function together. The distinction between these two programs does not exist for arbuscular mycorrhizae development despite events occurring in both root tissues. Mutations that affect both symbioses are restricted to the epidermal program. We propose here sites of action and potential roles for ethylene during the formation of the two symbioses with a specific hypothesis for nodule organogenesis. Assuming the epidermis does not make ethylene, the microsymbionts probably first encounter a regulatory level of ethylene at the epidermis–outermost cortical cell layer interface. Depending on the hormone concentrations there, infection will either progress or be blocked. In the former case, ethylene affects the cortex cytoskeleton, allowing reorganization that facilitates infection; in the latter case, ethylene acts on several enzymes that interfere with infection thread growth, causing it to abort. Throughout this review, the difficulty of generalizing the roles of ethylene is emphasized and numerous examples are given to demonstrate the diversity that exists in plants
Dark Energy and Gravity
I review the problem of dark energy focusing on the cosmological constant as
the candidate and discuss its implications for the nature of gravity. Part 1
briefly overviews the currently popular `concordance cosmology' and summarises
the evidence for dark energy. It also provides the observational and
theoretical arguments in favour of the cosmological constant as the candidate
and emphasises why no other approach really solves the conceptual problems
usually attributed to the cosmological constant. Part 2 describes some of the
approaches to understand the nature of the cosmological constant and attempts
to extract the key ingredients which must be present in any viable solution. I
argue that (i)the cosmological constant problem cannot be satisfactorily solved
until gravitational action is made invariant under the shift of the matter
lagrangian by a constant and (ii) this cannot happen if the metric is the
dynamical variable. Hence the cosmological constant problem essentially has to
do with our (mis)understanding of the nature of gravity. Part 3 discusses an
alternative perspective on gravity in which the action is explicitly invariant
under the above transformation. Extremizing this action leads to an equation
determining the background geometry which gives Einstein's theory at the lowest
order with Lanczos-Lovelock type corrections. (Condensed abstract).Comment: Invited Review for a special Gen.Rel.Grav. issue on Dark Energy,
edited by G.F.R.Ellis, R.Maartens and H.Nicolai; revtex; 22 pages; 2 figure
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
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