1,997 research outputs found
Alkaline pretreatment of walnut shells increases pore surface hydrophilicity of derived biochars
The surface chemistry and morphology of biochars produced by pyrolysis of walnut shells affects their utility for adsorption applications. Yet, little is known about surface interactions in the pores of these materials, mostly due to the challenging nature of accessing information at this length scale in a non-destructive manner. Here, for the first time, the relative adsorption strengths of solvents comprising different functional groups to internal (pore) surfaces of walnut shells and derived biochars were investigated using low-field nuclear magnetic resonance (NMR) relaxation time measurements to non-destructively probe interactions of fluids with pore surfaces. Carbon bonding state compositions of these materials with respect to distance from the particle surface were determined using X-ray photoelectron spectroscopy coupled with ion beam etching. Alkaline pretreatment was found to increase the hydrophilicity of both walnut shells and derived biochars. It was found to increase surface interactions with hydroxyl groups, and to decrease those with methyl groups. Results were contextualised by thermogravimetric analysis, scanning electron microscopy, and previous in-situ X-ray imaging results. Taken together, results showed that alkaline pretreatment may be used to modulate responses to pyrolysis temperature of several factors that affect adsorption properties including surface hydrophilicity, particle size, porosity, pore accessibility, and surface texture
Simultaneous targeting of Eph receptors in glioblastoma
Eph tyrosine kinase receptors are frequently overexpressed and functional in many cancers, and they are attractive candidates for targeted therapy. Here, we analyzed the expression of Eph receptor A3, one of the most up-regulated factors in glioblastoma cells cultured under tumorsphere-forming conditions, together with EphA2 and EphB2 receptors. EphA3 was overexpressed in up to 60% of glioblastoma tumors tested, but not in normal brain. EphA3 was localized in scattered areas of the tumor, the invasive ring, and niches near tumor vessels. EphA3 co-localized with macrophage/leukocyte markers, suggesting EphA3 expression on tumor-infiltrating cells of bone marrow origin. We took advantage of the fact that ephrinA5 (eA5) is a ligand that binds EphA3, EphA2 and EphB2 receptors, and used it to construct a novel targeted anti-glioblastoma cytotoxin. The eA5-based cytotoxin potently and specifically killed glioblastoma cells with an IC(50) of at least 10(−11) M. This and similar cytotoxins will simultaneously target different compartments of glioblastoma tumors while mitigating tumor heterogeneity
Representational task formats and problem solving strategies in kinematics and work
Previous studies have reported that students employed different problem solving approaches when presented with the same task structured with different representations. In this study, we explored and compared students’ strategies as they attempted tasks from two topical areas, kinematics and work. Our participants were 19 engineering students taking a calculus-based physics course. The tasks were presented in linguistic, graphical, and symbolic forms and requested either a qualitative solution or a value. The analysis was both qualitative and quantitative in nature focusing principally on the characteristics
of the strategies employed as well as the underlying reasoning for their applications. A comparison was also made for the same student’s approach with the same kind of representation across the two topics.
Additionally, the participants’ overall strategies across the different tasks, in each topic, were considered. On the whole, we found that the students prefer manipulating equations irrespective of the representational format of the task. They rarely recognized the applicability of a ‘‘qualitative’’ approach to solve the
problem although they were aware of the concepts involved. Even when the students included visual representations in their solutions, they seldom used these representations in conjunction with the
mathematical part of the problem. Additionally, the students were not consistent in their approach for interpreting and solving problems with the same kind of representation across the two topical areas. The representational format, level of prior knowledge, and familiarity with a topic appeared to influence their
strategies, their written responses, and their ability to recognize qualitative ways to attempt a problem. The nature of the solution does not seem to impact the strategies employed to handle the problem
Isotopic composition of fragments in multifragmentation of very large nuclear systems: effects of the chemical equilibrium
Studies on the isospin of fragments resulting from the disassembly of highly
excited large thermal-like nuclear emitting sources, formed in the ^{197}Au +
^{197}Au reaction at 35 MeV/nucleon beam energy, are presented. Two different
decay systems (the quasiprojectile formed in midperipheral reactions and the
unique source coming from the incomplete fusion of projectile and target in the
most central collisions) were considered; these emitting sources have the same
initial N/Z ratio and excitation energy (E^* ~= 5--6 MeV/nucleon), but
different size. Their charge yields and isotopic content of the fragments show
different distributions. It is observed that the neutron content of
intermediate mass fragments increases with the size of the source. These
evidences are consistent with chemical equilibrium reached in the systems. This
fact is confirmed by the analysis with the statistical multifragmentation
model.Comment: 9 pages, 4 ps figure
Misura tridimensionale dei tempi di rilassamento longitudinali (spin - reticolo) di un dosimetro Fricke mediante una apparecchiatura di diagnostica RMN da 1.5 T
Statistical evolution of isotope composition of nuclear fragments
Calculations within the statistical multifragmentation model show that the
neutron content of intermediate mass fragments can increase in the region of
liquid-gas phase transition in finite nuclei. The model predicts also
inhomogeneous distributions of fragments and their isospin in the freeze-out
volume caused by an angular momentum and external long-range Coulomb field.
These effects can take place in peripheral nucleus-nucleus collisions at
intermediate energies and lead to neutron-rich isotopes produced in the
midrapidity kinematic region.Comment: 14 pages with 4 figures. GSI preprint, Darmstadt, 200
Development and Validation of a Computerized Assessment Form to Support Nursing Diagnosis
PURPOSE: Describe the development and validation of the Nursing Assessment Form (NAF), within a clinical nursing information system, to support nurses in the identification of nursing diagnoses.
METHODS: Content validity and consensus on NAF contents were established using a panel of experts in nursing diagnosis and Delphi rounds.
FINDINGS: Expert consensus was achieved to validate an instrument to support nurses in the process of nursing diagnoses identification.
CONCLUSIONS: The use of the NAF can help nurses in diagnostic reasoning, facilitating the identification of the more suitable nursing diagnoses, and provide a basis for the best nursing interventions and outcomes.
IMPLICATIONS FOR NURSING PRACTICE:
The use of computerized decision support can improve the implementation of standardized terminology and the accuracy of nursing diagnosis
Bacterial biofilms on biopolymeric sorbent supports for environmental bioremediation
Bioremediation encompasses a broad range of environmental biotechnology, which require
multidisciplinary approaches through implementation of innovative tools to the natural biological
process occurring in soil, water and air. Immobilization of hydrocarbon-degrading microorganisms
on biodegradable sorbent supports significantly promotes bioremediation processes. Recently
ecofriendly, low cost bioremediation devices based on polylactic acid (PLA) and polycaprolactone
(PCL) membranes hosting a biodegrading bacterial biofilms were obtained[1]. This work
investigates the higher effectiveness of immobilizing hydrocarbon-degrading bacteria compared to
that of planktonic cells. Soil hydrocarbon (HC) degrading Actinobacteria Nocardia cyriacigeorgica
strain SoB, Gordonia amicalis strain SoCg[2], and the marine hydrocarbonoclastic Alcanivorax
borkumensis strain AU3-AA-7[3] were immobilized on PLA and PCL membranes and tested on
hexadecane. The capacity of adhesion and proliferation of these biodegrading biofilms within
the biopolymers were evaluated at various time points (5, 10, 15, and 30 incubation days) using
scanning electron microscopy (SEM). The SEM images revealed that PLA and PCL nanofibers
were nearly completely covered by a complex three-dimensional bacterial film for all tested
strains. Quantification of total biomass (estimated as total dsDNA) confirmed biofilm growth up to
30 days of incubation. Crude oil biodegradation ability of biofilms-membranes systems, assessed
by Gas Chromatography-FID analysis, demonstrated the removal of over 60% of the oil after 5
days of incubation, outperforming free-living bacteria by 24%. Viable plate counts showed that
bacterial biofilms adsorbed on biopolymers were still viable after 30 days, indicating their potential
for long-term applications
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