Serum Proteins Enhance Dispersion Stability and Influence the Cytotoxicity and Dosimetry of ZnO Nanoparticles in Suspension and Adherent Cancer Cell Models

Agglomeration and sedimentation of nanoparticles (NPs) within biological solutions is a major limitation in their use in many downstream applications. It has been proposed that serum proteins associate with the NP surface to form a protein corona that limits agglomeration and sedimentation. Here, we investigate the effect of fetal bovine serum (FBS) proteins on the dispersion stability, dosimetry, and NP-induced cytotoxicity of cationic zinc oxide nanoparticles (nZnO) synthesized via forced hydrolysis with a core size of 10 nm. Two different in vitro cell culture models, suspension and adherent, were evaluated by comparing a phosphate buffered saline (PBS) nZnO dispersion (nZnO/PBS) and an FBS-stabilized PBS nZnO dispersion (nZnO – FBS/PBS). Surface interactions of FBS on nZnO were analyzed via spectroscopic and optical techniques. Fourier transformed infrared spectroscopy (FTIR) confirmed the adsorption of negatively charged protein components on the cationic nZnO surface through the disappearance of surfaced-adsorbed carboxyl functional groups and the subsequent detection of vibrational modes associated with the protein backbone of FBS-associated proteins. Further confirmation of these interactions was noted in the isoelectric point shift of the nZnO from the characteristic pH of 9.5 to a pH of 6.1.In nZnO – FBS/PBS dispersions, the FBS reduced agglomeration and sedimentation behaviors to impart long-term improvements (\u3e24 h) to the nZnO dispersion stability. Furthermore, mathematical dosimetry models indicate that nZnO – FBS/PBS dispersions had consistent NP deposition patterns over time unlike unstable nZnO/PBS dispersions. In suspension cell models, the stable nZnO – FBS/PBS dispersion resulted in a ~33 % increase in the NP-induced cytotoxicity for both Jurkat leukemic and Hut-78 lymphoma cancer cells. In contrast, the nZnO – FBS/PBS dispersion resulted in 49 and 71 % reductions in the cytotoxicity observed towards the adherent breast (T-47D) and prostate (LNCaP) cancer cell lines, respectively. Presence of FBS in the NP dispersions also increased the reactive oxygen species generation. These observations indicate that the improved dispersion stability leads to increased NP bioavailability for suspension cell models and reduced NP sedimentation onto adherent cell layers resulting in more accurate in vitro toxicity assessments

Delay to Surgical Treatment in Geriatric Hip Fracture Patients

Background: Hip fractures in the geriatric population are frequently encountered. There is increasing focus on minimizing the delay to surgery in these patients. This study was designed to evaluate factors responsible for a delay to surgery in a geriatric hip fracture population and how time to surgery affects mortality. Methods: A retrospective cohort of patients sustaining low energy geriatric hip fractures in either an American College of Surgeons (ACS) verified Level 1 trauma center or a local university affiliated community teaching hospital were reviewed. The following variables were evaluated as independent risk factors for delay to surgery: demographic data, surgical details, use of cardiology resources, treatment center, and comorbidities. As a secondary objective, the effect of time to surgery on 1 year mortality was analyzed. Results: 1157 patients met inclusion criteria. The following factors increased the risk of delay to surgery greater than 48 hours: male sex, treatment in a community hospital (versus trauma center), older age, multiple comorbidities (eg, cardiovascular-related conditions or other fractures), cardiology consultation, and an American Society of Anesthesiologists physical status score of 3 or 4. Cardiology consultation was the strongest independent predictor of risk for delay to surgery of >48 hours (odds ratio, 6.68; 95% confidence interval, 4.40 to 10.14; P Conclusion: The presence of cardiovascular comorbidities and cardiology consultations can delay surgical treatments for hip fractures in patients greater than 65 years old, but the delay did not influence 1-year all-cause mortality. Level of Evidence: Level IV.</p

Neutron Radiographic Study of the Effect of Heat-Driven Water Transport on the Tensile Strength of Bentonite-Bonded Moulding Sand

Wet tensile testing is a common method to assess the stability of bentonite bonded moulding sands. For wet tensile testing, a specimen is first heated from above in order to simulate heat-driven moisture transport induced by the casting process. Then, tensile stress is applied until rupture. In this study, neutron radiography imaging was applied to moulding sands in-situ during heating and wet tensile testing in order to investigate the effects of water kinematics on the tensile strength. Neutron radiography allowed the localization of the rupture plane and the quantitative determination of the local water content with sub-mm resolution. Quantification of the temperature at the rupture plane and of the heat kinematics within the specimen was accomplished by temperature measurements both in-situ and ex-situ. In this way, experimental data correlating the wet tensile strength with the specific conditions of moulding sands at the rupture plane were obtained for the first time. Series of experiments with different initial sand moisture contents were conducted. The results show that the weakest location within a sand profile can be pinpointed at the interface between evaporation and condensation zone (i.e., at the 100 °C isotherm), where water vaporisation starts and the water bridges connecting the sand grains collapse. This weakest location has maximum strength, if the local water content at the rupture plane is between 5 and 9 wt.%. Less water leads to a strong decrease of wet tensile strength. More water requires an initial water content above 5 wt.%, which leads to a decrease of the tensile strength of the unheated sand

Effective thermodynamics of strongly coupled qubits

Interactions between a quantum system and its environment at low temperatures can lead to violations of thermal laws for the system. The source of these violations is the entanglement between system and environment, which prevents the system from entering into a thermal state. On the other hand, for two-state systems, we show that one can define an effective temperature, placing the system into a `pseudo-thermal' state where effective thermal laws are upheld. We then numerically explore these assertions for an n-state system inspired by the spin-boson environment.Comment: 9 pages, 3 figure

Enhancement of the helium resonance lines in the solar atmosphere by suprathermal electron excitation II: non-Maxwellian electron distributions

In solar EUV spectra the He I and He II resonance lines show unusual behaviour and have anomalously high intensities compared with other transition region lines. The formation of the helium resonance lines is investigated through extensive non-LTE radiative transfer calculations. The model atmospheres of Vernazza, Avrett & Loeser are found to provide reasonable matches to the helium resonance line intensities but significantly over-estimate the intensities of other transition region lines. New model atmospheres have been developed from emission measure distributions derived by Macpherson & Jordan, which are consistent with SOHO observations of transition region lines other than those of helium. These models fail to reproduce the observed helium resonance line intensities by significant factors. The possibility that non-Maxwellian electron distributions in the transition region might lead to increased collisional excitation rates in the helium lines is studied. Collisional excitation and ionization rates are re-computed for distribution functions with power law suprathermal tails which may form by the transport of fast electrons from high temperature regions. Enhancements of the helium resonance line intensities are found, but many of the predictions of the models regarding line ratios are inconsistent with observations. These results suggest that any such departures from Maxwellian electron distributions are not responsible for the helium resonance line intensities.Comment: 23 pages, 11 figures, accepted to appear in MNRAS, LaTeX uses mn.st