First Direct Detection Constraints on Planck-Scale Mass Dark Matter with Multiple-Scatter Signatures Using the DEAP-3600 Detector

Dark matter with Planck-scale mass (≃10^{19}  GeV/c^{2}) arises in well-motivated theories and could be produced by several cosmological mechanisms. A search for multiscatter signals from supermassive dark matter was performed with a blind analysis of data collected over a 813 d live time with DEAP-3600, a 3.3 t single-phase liquid argon-based detector at SNOLAB. No candidate signals were observed, leading to the first direct detection constraints on Planck-scale mass dark matter. Leading limits constrain dark matter masses between 8.3×10^{6} and 1.2×10^{19}  GeV/c^{2}, and ^{40}Ar-scattering cross sections between 1.0×10^{-23} and 2.4×10^{-18}  cm^{2}. These results are interpreted as constraints on composite dark matter models with two different nucleon-to-nuclear cross section scalings.

Pulse-shape discrimination against low-energy Ar-39 beta decays in liquid argon with 4.5 tonne-years of DEAP-3600 data

The DEAP-3600 detector searches for the scintillation signal from dark matter particles scattering on a 3.3 tonne liquid argon target. The largest background comes from 39 Ar beta decays and is suppressed using pulse-shape discrimination (PSD). We use two types of PSD estimator: the prompt-fraction, which considers the fraction of the scintillation signal in a narrow and a wide time window around the event peak, and the log-likelihood-ratio, which compares the observed photon arrival times to a signal and a background model. We furthermore use two algorithms to determine the number of photons detected at a given time: (1) simply dividing the charge of each PMT pulse by the mean single-photoelectron charge, and (2) a likelihood analysis that considers the probability to detect a certain number of photons at a given time, based on a model for the scintillation pulse shape and for afterpulsing in the light detectors. The prompt-fraction performs approximately as well as the log-likelihood-ratio PSD algorithm if the photon detection times are not biased by detector effects. We explain this result using a model for the information carried by scintillation photons as a function of the time when they are detected.

The novel Mechanical Ventilator Milano for the COVID-19 pandemic

This paper presents the Mechanical Ventilator Milano (MVM), a novel intensive therapy mechanical ventilator designed for rapid, large-scale, low-cost production for the COVID-19 pandemic. Free of moving mechanical parts and requiring only a source of compressed oxygen and medical air to operate, the MVM is designed to support the long-term invasive ventilation often required for COVID-19 patients and operates in pressure-regulated ventilation modes, which minimize the risk of furthering lung trauma. The MVM was extensively tested against ISO standards in the laboratory using a breathing simulator, with good agreement between input and measured breathing parameters and performing correctly in response to fault conditions and stability tests. The MVM has obtained Emergency Use Authorization by U.S. Food and Drug Administration (FDA) for use in healthcare settings during the COVID-19 pandemic and Health Canada Medical Device Authorization for Importation or Sale, under Interim Order for Use in Relation to COVID-19. Following these certifications, mass production is ongoing and distribution is under way in several countries. The MVM was designed, tested, prepared for certification, and mass produced in the space of a few months by a unique collaboration of respiratory healthcare professionals and experimental physicists, working with industrial partners, and is an excellent ventilator candidate for this pandemic anywhere in the world.

First Results from the DEAP-3600 Dark Matter Search with Argon at SNOLAB

This Letter reports the first results of a direct dark matter search with the DEAP-3600 single-phase liquid argon (LAr) detector. The experiment was performed 2 km underground at SNOLAB (Sudbury, Canada) utilizing a large target mass, with the LAr target contained in a spherical acrylic vessel of 3600 kg capacity. The LAr is viewed by an array of PMTs, which would register scintillation light produced by rare nuclear recoil signals induced by dark matter particle scattering. An analysis of 4.44 live days (fiducial exposure of 9.87 ton day) of data taken during the initial filling phase demonstrates the best electronic recoil rejection using pulse-shape discrimination in argon, with leakage <1.2×10^{-7} (90% C.L.) between 15 and 31  keV_{ee}. No candidate signal events are observed, which results in the leading limit on weakly interacting massive particle (WIMP)-nucleon spin-independent cross section on argon, <1.2×10^{-44}  cm^{2} for a 100  GeV/c^{2} WIMP mass (90% C.L.).

Crystal Structures of Peptide Deformylase from Rice Pathogen Xanthomonas oryzae pv. oryzae in Complex with Substrate Peptides, Actinonin, and Fragment Chemical Compounds

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight on rice; this species is one of the most destructive pathogenic bacteria in rice cultivation worldwide. Peptide deformylase (PDF) catalyzes the removal of the N-formyl group from the N-terminus of newly synthesized polypeptides in bacterial cells and is an important target to develop antibacterial agents. We determined crystal structures of Xoo PDF (XoPDF) at up to 1.9 Å resolution, which include apo, two substrate-bound (methionine-alanine or methionine-alanine-serine), an inhibitor-bound (actinonin), and six fragment chemical-bound structures. Six fragment chemical compounds were bound in the substrate-binding pocket. The fragment chemical-bound structures were compared to the natural PDF inhibitor actinonin-bound structure. The fragment chemical molecules will be useful to design an inhibitor specific to XoPDF and a potential pesticide against Xoo.

Measurement of day and night neutrino energy spectra at SNO and constraints on neutrino mixing parameters

The Sudbury Neutrino Observatory (SNO) has measured day and night solar neutrino energy spectra and rates. For charged current events, assuming an undistorted 8B spectrum, the night minus day rate is 14.0%+/-6.3%(+1.5%)(-1.4%) of the average rate. If the total flux of active neutrinos is additionally constrained to have no asymmetry, the nu(e) asymmetry is found to be 7.0%+/-4.9%(+1.3%)(-1.2%). A global solar neutrino analysis in terms of matter-enhanced oscillations of two active flavors strongly favors the large mixing angle solution.

Direct evidence for neutrino flavor transformation from neutral-current interactions in the Sudbury Neutrino Observatory

Observations of neutral-current nu interactions on deuterium in the Sudbury Neutrino Observatory are reported. Using the neutral current (NC), elastic scattering, and charged current reactions and assuming the standard 8B shape, the nu(e) component of the 8B solar flux is phis(e) = 1.76(+0.05)(-0.05)(stat)(+0.09)(-0.09)(syst) x 10(6) cm(-2) s(-1) for a kinetic energy threshold of 5 MeV. The non-nu(e) component is phi(mu)(tau) = 3.41(+0.45)(-0.45)(stat)(+0.48)(-0.45)(syst) x 10(6) cm(-2) s(-1), 5.3sigma greater than zero, providing strong evidence for solar nu(e) flavor transformation. The total flux measured with the NC reaction is phi(NC) = 5.09(+0.44)(-0.43)(stat)(+0.46)(-0.43)(syst) x 10(6) cm(-2) s(-1), consistent with solar models.

Observation of Kossel and Kikuchi lines in thermal neutron incoherent scattering

In this Letter we report the observation of K lines (representing collectively, Kossel and Kikuchi lines) produced by monochromatic thermal neutrons interacting with a KDP (potassium dihydrogen phosphate) single crystal. Since K lines contain phase information, these observations establish the experimental basis for direct crystallographic phasing of atomic structures containing incoherent scatterers, such as hydrogen, via thermal neutron "inside source" holography.

Atomic structure holography using thermal neutrons

The idea of atomic-resolution holography has its roots in the X-ray work of Bragg and in Gabor's electron interference microscope. Gabor's lensless microscope was not realized in his time, but over the past twelve years there has been a steady increase in the number of reports on atomic-resolution holography. All of this work involves the use of electrons or hard X-rays to produce the hologram. Neutrons are often unique among scattering probes in their interaction with materials: for example, the relative visibility of hydrogen and its isotopes is a great advantage in the study of polymers and biologically relevant materials. Recent work proposed that atomic-resolution holography could be achieved with thermal neutrons. Here we use monochromatic thermal neutrons, adopting the inside-source concept of Szöke, to image planes of oxygen atoms located above and below a single hydrogen atom in the oxide mineral simpsonite.

Measurement of the rate of nu(e) + d --> p + p + e(-) interactions produced by (8)B solar neutrinos at the Sudbury Neutrino Observatory

Solar neutrinos from (8)B decay have been detected at the Sudbury Neutrino Observatory via the charged current (CC) reaction on deuterium and the elastic scattering (ES) of electrons. The flux of nu(e)'s is measured by the CC reaction rate to be straight phi(CC)(nu(e)) = 1.75 +/- 0.07(stat)(+0.12)(-0.11)(syst) +/- 0.05(theor) x 10(6) cm(-2) s(-1). Comparison of straight phi(CC)(nu(e)) to the Super-Kamiokande Collaboration's precision value of the flux inferred from the ES reaction yields a 3.3 sigma difference, assuming the systematic uncertainties are normally distributed, providing evidence of an active non- nu(e) component in the solar flux. The total flux of active 8B neutrinos is determined to be 5.44+/-0.99 x 10(6) cm(-2) s(-1).

Survey of termite-inhabited soil and mosquito breeding sites in Lucknow, India for potential mycopathogens of Anopheles stephensi

During a short survey of soil and mosquito breeding sites in Lucknow, India for potential mycopathogen from a period of August-October 1996, 11 species of fungi in 5 genera were isolated using live mosquito larvae as host, Aspergillus flavus, A. fumigatus and Fusarium semitectum were the most frequently isolated species. Other fungi recorded were A. niger, A. ochraceus, A. terreus, A. versicolor, Geotrichum candidum, Penicillium verrucosum, Paecilomyces sp. and Fusarium sp. (Liseola/Elegans complex). Insect cell walls are known to contain chitin, so fungal isolates were tested for their chitinase activity on semi synthetic medium containing colloidal chitin. High chitinolytic activities were observed with A. flavus and A. ochraceus. Chitinase producers can be considered as potential pathogens. However, the higher incidence of F. semitectum could not be explained by inability to utilize chitin.

On the inhibitory activities of a new boron compound and ultrasound against the mouse ascites tumour

The inhibitory effects of a new boron compound, dihydroxy (oxybiguanido) boron (III) hydrochloride monohydrate (HB), and ultrasound (US) of a frequency 25 kHz on the growth of ascites tumour in female Swiss mice were studied by monitoring the survival, weight of tumour-associated material, tumour cell count, serum alkaline phosphatase activity and the haematological parameters of the treated animals. 5-Fluorouracil (5-FU), a well-known anticancer agent, was used as positive control. While HB exhibited a very significant antitumour action, US alone produced a small but significant inhibitory effect. The combination of US with HB or 5-FU produced an extra antitumour action as compared to the actions of these chemicals used singly. The mechanisms of action of the new boron compound (HB) and US are discussed.

On the possible use of a new boron compound, hydroxysalicylhydroxamato boron(III), and ultrasound in the treatment of female mice bearing the Ehrlich ascites carcinoma cells

The inhibitory effects of a new boron compound, hydroxy salicylhydroxamato boron (III) (SHB) and ultrasound of frequency 25 KHz (US) on the growth of ascites tumor in female Swiss mice were studied by monitoring the survival and the tumor growth in the treated tumor bearing mice and also the transplantability and the DNA synthesis in the treated tumor (Ehrlich ascites carcinoma) cells. While SHB alone produced a highly significant antitumor activity, US alone produced a small but significant effect. The combination of SHB and US produced significantly greater antitumor activity than SHB alone. The mechanisms of SHB and US actionary are discussed.

A new boron compound (guanidine biboric acid adduct) as an antitumour agent against Ehrlich ascites carcinoma in mice

The inhibitory effects of a new boron compound of guanidine biboric acid adduct (GB) and guanidium chloride (L1) on the growth of ascites tumour in female Swiss mice were studied by monitoring the survival, tumour weight, tumour cell count, transplantability of Ehrlich ascites cells, precursor incorporation and the haematological parameters of the treated mice. 5-Fluorouracil, a known anticancer drug, was used as a positive control. The most important parameter was the survival time, which increased significantly when tumour-bearing mice were treated with the boron compound. Haematological parameters of the treated animals showed minimum toxic effects when boron was coupled with guanidine.

Antitumor properties of boron complexes with hydroxy biguanide and salicyl hydroxamic acid against Ehrlich ascites carcinoma

A new derivative of hydroxamic acid, hydroxy biguanido hydrochloride monohydrate and its boron derivative, dihydroxy-oxybiguanido boron (III) hydrochloride monohydrate were synthesized. Another boron compound, hydroxo-salicyl-hydroxamato boron (III) was synthesized from known salicyl hydroxamic acid. Antitumor properties of all the compounds evaluated against Ehrlich ascites carcinoma in mice show enhanced survival time when boron is incorporated in the compounds. Hematological parameters, alkaline phosphatase in serum of the treated animals show minimum toxic effects after boron is coupled with their respective hydroxamic acids.

Chloroaceto hydroxamic acid as antitumor agent against Ehrlich ascites carcinoma in mice

In vivo cell growth inhibition of Ehrlich ascites carcinoma (EAC) has been evaluated with chloroacetohydroxamic acid, (CHA), having -CH2 Cl, for the -NH2 group of hydroxyurea (HU). The inhibitory character of CHA against EAC in mice model has been found to be comparable with that of HU. Cell growth inhibition by CHA is accompanied by inhibitions of DNA and protein synthesis of the treated cells. The transplantability of EAC cells treated with a single dose of (100 mg/kg) CHA is found to be reduced. Enhanced intraperitoneal macrophage is observed in normal mice following CHA (100 mg/kg) treatment. Deviations of hematological parameters and alkaline phosphatase (ALKP) activity consequent to tumor growth are found to be recovered in tumor bearing mice treated with CHA. All these studies suggest the importance of CHA for further trial as a potent antitumor agent.

5-Nitrofuran derivatives of fatty acid hydrazides induce differentiation in human myeloid leukaemic cell lines

Compounds formed by 5-nitrofuran with hydrazides of formic, acetic and propionic acids, hereafter respectively known as SBF, SBA and SBP have been used to evaluate the differentiation-inducing properties on two established myeloid leukaemic cell lines ML-2 and EOL-1. SBP is found to be the most effective as an antineoplastic agent amongst the three. Induction of differentiation observed are in the order SBP > SBA > SBF, as assessed by morphology, NBT-reducing activity and surface marker antigens of the treated cells. Induction of differentiation of ML-2 and EOL-1 cells by the most effective compound, SBP (3 microM), is accompanied by perturbation of the cell cycle, with most of the cells accumulating in the G0-G1, phase. Inhibition of DNA synthesis occurs while protein and RNA synthesis remain practically unchanged.

Studies on the antineoplasticity of Schiff bases containing 5-nitrofuran and pyrimidine

Antineoplastic properties of different Schiff bases obtained by the interaction of 5-nitrofuran with substituted pyrimidines have been examined both in vitro and in vivo. In vitro studies on L 5178Y/asparaginase sensitive, HL 60 and P 388 cell lines and in vivo studies on the P 388 cell line indicate that all the compounds are potential antineoplastic agents. However, 2-(5-nitro-2-furfurylidene-amino)-pyrimidine (SBP1) is the most effective, and 2-(5-nitro-2-furfurylidene-amino)-6-hydroxypyrimidine (SBP3) is the least effective agent. Doubling time, rates of protein and DNA synthesis inhibition and LD50 values-1,000 mg/kg body weight for SBP1 and 1,275 mg/kg body weight for 2-(5-nitro-2-furfurylidene-amino)-4- methylpyrimidine (SBP2)- in the oral route support the activity and use of SBP1 and SBP2 as future anticancer agents.

Impact of freeze drying on drug resistance pattern of few Escherichia coli strains

Drug resistant strains of E. coli were freeze dried for long term preservation. Certain drug resistance markers were maintained after freeze drying while others were not. Streptomycin and sulphonamide resistance markers resisted freeze drying. Ampicillin, cephelaxin and neomycin resistances developed very frequently and except gentamicin all the markers were lost in varying percentage after freeze drying.

Effect of liposomal encapsulation of cis-platinum diamminodichloride in the treatment of Ehrlich ascites carcinoma

cis-Platinum diamminodichloride (II) encapsulated in neutral liposomes has been used to enhance the activity of the drug on Ehrlich ascites carcinoma in mice. Both in vitro and in vivo experiments have revealed that better regression in tumor growth and cure, could be achieved with a lower dose, having apparently no toxic effect, by liposomal encapsulation of the drug.

Keratinophilic fungi from Orissa, India, II: Isolations from feathers of wild birds and domestic fowls

Feather samples from 117 birds, representing 11 species, were examined for keratinophilic fungi. Of these, 63 (53.8%) were found to be positive. Nine species of fungi classified in 6 genera were isolated: Aphanoascus terreus (1.7%), Chrysosporium indicum (26.4%), Chrys. tropicum (11.1%) the Chrysosporium state of Aphanoascus spp. (2.5%), the Chrysosporium state of Arthroderma tuberculatum (3.4%), Ctenomyces serratus (0.8%), Gymnoascoideus petalosporus (7.6%), Malbranchea spp. (6.8%), Rollandina hyalinospora (6.8%). Passer domesticus (the house sparrow) harboured the largest varieties of keratinophilic fungi: the Chrysosporium state of Arthroderma tuberculatum was found to be associated with it selectively. The associations of these keratinophilic fungi with birds were non-clinical in nature.

Keratinophilic fungi from Orissa, India, I: Isolation from soils

Results of a preliminary survey of keratinophilic fungi in soils collected from five districts of Orissa, India, are reported. A total of 80 soil samples were examined, of which 51 samples (63.7%) were positive for keratinophilic fungi. Twelve species of fungi classified in seven genera were isolated: Aphanoascus reticulisporus (2.4%), Aph. terreus (1.2%), Chrysosporium state of Arthroderma tuberculatum (4.8%), Chrysosporium indicum (31.3%), Chrys. tropicum (18.0%), Chrys. evolceanui (1.2%), Gymnoascoideus petalosporus (9.6%), Microsporum gypseum (20.4%), Nannizzia spp. (3.6%), Pseudoarachniotus flavoluteus (3.6%), Pseudoarachniotus sp. (1.2%) and a new genus of gymnoascaceae (2.4%). Our isolation of Aph. reticulisporus is the first recorded in India.