Antibacterial properties of novel Eumelanin-Inspired Phenylene Indolyne derivatives

BACKGROUND: The eumelanin core represents a novel compound having the intrinsic ability to act as scaffolding for functional groups which may possess antibacterial properties. The purpose of this study was to investigate the antibacterial potential of eumelanin-inspired phenylene indolyne (EIPE) derivatives EIPE-1 and EIPE-HCl which are hydrophobic and hydrophilic, respectively.METHODS: A standardized disk agar diffusion bioassay was employed to determine the susceptibility and resistance levels of 12 gram-positive and 13 gram-negative bacteria to nonpolar and polar EIPE derivatives. The bioassay was performed by dissolving the compounds in dimethyl sulfoxide and impregnating filter paper disks which were placed onto Mueller Hinton agar plates spread inoculated in a standardized manner to obtain even cell lawns after incubation for 18±1 hours at 37°C. Zones of growth inhibition were measured with the aid of electronic calipers.RESULTS: Five strains of Staphylococcus aureus, plus Bacillus subtilis and Staphylococcus epidermidis were all found to be susceptible to the hydrophobic derivative EIPE-1, while other gram-positive and all gram-negative organisms exhibited resistant phenotypes at potencies tested. The more polar EIPE-HCl derivative failed to inhibit growth of any of the organisms examined, regardless of gram reactivity.CONCLUSION: Hydrophobic EIPE derivative EIPE-1 clearly possesses a gram-positive antibacterial spectrum, although only certain organisms are susceptible at the potencies employed for this study. The susceptibility of two methicillin-resistant S. aureus strains (SFL 8 and SFL 64) to EIPE-1 suggests that its mechanism of action does not involve the penicillin-binding proteins of peptidoglycan biosynthesis targeted by mainstream B-lactam antibiotics. The uniform resistance of 13 phylogenetically disparate gram-negative bacteria supports the notion that intrinsic outer membrane exclusion properties may play a role in the mechanism underlying their phenotypic resistance to the molecule. The more polar EIPE-HCl possesses no antibacterial properties at the potencies examined here. Future work will include performing minimal inhibitory concentration bioassays to quantitatively describe susceptibly in selected gram-positive bacteria. In addition, batch culture growth kinetics assays will be crucial to learning the cellular and molecular mechanisms responsible for susceptibility and resistance to EIPE-1

Quantum walks can unitarily match random walks on finite graphs

Quantum and random walks were proven to be equivalent on finite graphs by demonstrating how to construct a time-dependent random walk sharing the exact same evolution of vertex probability of any given discrete-time coined quantum walk. Such equivalence stipulated a deep connection between the processes that is far stronger than simply considering quantum walks as quantum analogues of random walks. This article expands on the connection between quantum and random walks by demonstrating a procedure that constructs a time-dependent quantum walk matching the evolution of vertex probability of any given random walk in a unitary way. It is a trivial fact that a quantum walk measured at all time steps of its evolution degrades to a random walk. More interestingly, the method presented describes a quantum walk that matches a random walk without measurement operations, such that the unitary evolution of the quantum walk captures the probability evolution of the random walk. The construction procedure is general, covering both homogeneous and non-homogeneous random walks. For the homogeneous random walk case, the properties of unitary evolution imply that the quantum walk described is time-dependent since homogeneous quantum walks do not converge for arbitrary initial conditionsComment: 9 pages, 1 figur

Global water cycle

This research is the MSFC component of a joint MSFC/Pennsylvania State University Eos Interdisciplinary Investigation on the global water cycle extension across the earth sciences. The primary long-term objective of this investigation is to determine the scope and interactions of the global water cycle with all components of the Earth system and to understand how it stimulates and regulates change on both global and regional scales. Significant accomplishments in the past year are presented and include the following: (1) water vapor variability; (2) multi-phase water analysis; (3) global modeling; and (4) optimal precipitation and stream flow analysis and hydrologic processes

A simulation study of BrachyShade, a shadow-based internal source tracking system for HDR prostate brachytherapy

This paper presents a simulation study of BrachyShade, a proposed internal source-tracking system for real time quality assurance in high dose rate prostate brachytherapy. BrachyShade consists of a set of spherical tungsten occluders located above a pixellated silicon photodetector. The source location is estimated by minimising the mean squared error between a parametric model of the shadow image and acquired images of the shadows projected on the detector plane. A novel algorithm is finally employed to correct the systemic error resulting from Compton scattering in the medium. The worst-case error obtained with BrachyShade for a 13.5 ms image acquisition is less than 1.3 mm in the most distant part of the treatment volume, while for 75% of source locations an error of less than 0.42 mm was achieved

Livestock preference for endophyte-infected or endophyte-free Oxytropis sericea, Ipomoea carnea, and Ipomoea asarifolia

Fungal endophyte-infected forages have been shown to alter herbivore feeding preferences. The objective of this experiment was to compare the preference of cattle, sheep, and goats for plants containing (E+) and not containing (E-) fungal endophytes using freshly harvested Oxytropis sericea, Ipomoea carnea, and Ipomoea asarifolia. Goats and sheep rejected all forage choices regardless of endophyte status except for grass and alfalfa hay. Endophyte status had no influence on cattle forage preferences. Cattle rejected all Oxytropis sericea E+ and E- choices. Cattle discriminated between Ipomoea species, preferring Ipomoea carnea to Ipomoea asarifolia (P = 0.004). In all comparisons, Ipomoea carnea was selected over Ipomoea asarifolia. Cattle did not discriminate between E+ and E- plants of either species (P \u3e 0.33). Cattle preferred E+ Ipomoea carnea over E- Ipomoea asarifolia (P = 0.03), E- Ipomoea carnea over E- Ipomoea asarifolia (P = 0.003), E- Ipomoea carnea over E+ Ipomoea asarifolia (P = 0.001), and E+ Ipomoea carnea over E+ Ipomoea asarifolia (P = 0.01). Nutritional composition, including nonstructural carbohydrate concentrations, did not explain cattle preferences, as Ipomoea asarifolia contained higher total carbohydrate concentrations than did Ipomoea carnea. The presence of ergot and indole diterpene alkaloids in E+ Ipomoea asarifolia, or swainsonine in E+ Oxytropis sericea and E+ Ipomoea carnea did not influence cattle preference because cattle did not discriminate between E- and E+ plants. This study suggests that for these specific toxic plants, endophyte status plays no part in preferences of grazing cattle. For grazing animals, selection by livestock is related to forage scarcity or low nutrient content in the other available forage

Opportunistic dose amplification for proton and carbon ion therapy via capture of internally generated thermal neutrons

This paper presents Neutron Capture Enhanced Particle Therapy (NCEPT), a method for enhancing the radiation dose delivered to a tumour relative to surrounding healthy tissues during proton and carbon ion therapy by capturing thermal neutrons produced inside the treatment volume during irradiation. NCEPT utilises extant and in-development boron-10 and gadolinium-157-based drugs from the related field of neutron capture therapy. Using Monte Carlo simulations, we demonstrate that a typical proton or carbon ion therapy treatment plan generates an approximately uniform thermal neutron field within the target volume, centred around the beam path. The tissue concentrations of neutron capture agents required to obtain an arbitrary 10% increase in biological effective dose are estimated for realistic treatment plans, and compared to concentrations previously reported in the literature. We conclude that the proposed method is theoretically feasible, and can provide a worthwhile improvement in the dose delivered to the tumour relative to healthy tissue with readily achievable concentrations of neutron capture enhancement drugs

Clash of Titans: The Impact of Cluster Mergers in the Galaxy Cluster Red Sequence

Merging of galaxy clusters are some of the most energetic events in the Universe, and they provide a unique environment to study galaxy evolution. We use a sample of 84 merging and relaxed SPT galaxy clusters candidates, observed with the Dark Energy Camera in the $0.11<z<0.88$ redshift range, to build colour-magnitude diagrams to characterize the impact of cluster mergers on the galaxy population. We divided the sample between relaxed and disturbed, and in two redshifts bin at $z = 0.55$. When comparing the high-z to low-z clusters we find the high-z sample is richer in blue galaxies, independently of the cluster dynamical state. In the high-z bin we find that disturbed clusters exhibit a larger scatter in the Red Sequence, with wider distribution and an excess of bluer galaxies compared to relaxed clusters, while in the low-z bin we find a complete agreement between the relaxed and disturbed clusters. Our results support the scenario in which massive cluster halos at $z<0.55$ galaxies are quenched as satellites of another structure, i.e. outside the cluster, while at $z \geq 0.55$ the quenching is dominated by in-situ processes.Comment: 9 pages, 5 figures, paper accepted in MNRA

The conundrum of agenda-driven science in conservation

Conservation biology is a value-laden discipline predicated on conserving biodiversity (Soulé 1985), a mission that does not always sit easily with objective science (Lackey 2007; Pielke 2007; Scott et al. 2007). While some encourage scientists to be responsible advocates for conservation (Garrard et al. 2016), others worry that objectivity in conservation research may suffer (Lackey 2007). At this time, we believe advocacy by scientists is essential for environmental conservation and, indeed, humanity. It is difficult to envision the state of our environment had scientists failed to encourage policy makers and the public to address emerging conservation problems. Nevertheless, conservation scientists must avoid misusing the scientific process to promote specific conservation outcomes (Wilholt 2009); doing so erodes the credibility of science and can produce undesirable consequences (Thomas 1992; Mills 2000; Rohr and McCoy 2010). We consider intentionally engaging in activities outside of professional norms to promote desired outcomes, as part of either the production or dissemination of science, to constitute “agenda-driven science”. The issue of advocacy-related bias in conservation science merits renewed discussion because conservation conflicts in an increasingly polarized world might tempt some to engage in agenda-driven science to “win” a conflict