Deterministic Role of Collision Cascade Density in Radiation Defect Dynamics in Si

The formation of stable radiation damage in solids often proceeds via complex dynamic annealing (DA) processes, involving point defect migration and interaction. The dependence of DA on irradiation conditions remains poorly understood even for Si. Here, we use a pulsed ion beam method to study defect interaction dynamics in Si bombarded in the temperature range from ∼-30 °C to 210 °C with ions in a wide range of masses, from Ne to Xe, creating collision cascades with different densities. We demonstrate that the complexity of the influence of irradiation conditions on defect dynamics can be reduced to a deterministic effect of a single parameter, the average cascade density, calculated by taking into account the fractal nature of collision cascades. For each ion species, the DA rate exhibits two well-defined Arrhenius regions where different DA mechanisms dominate. These two regions intersect at a critical temperature, which depends linearly on the cascade density. The low-temperature DA regime is characterized by an activation energy of ∼0.1  eV, independent of the cascade density. The high-temperature regime, however, exhibits a change in the dominant DA process for cascade densities above ∼0.04 at.%, evidenced by an increase in the activation energy. These results clearly demonstrate a crucial role of the collision cascade density and can be used to predict radiation defect dynamics in Si.

Search for Tensor, Vector, and Scalar Polarizations in the Stochastic Gravitational-Wave Background

The detection of gravitational waves with Advanced LIGO and Advanced Virgo has enabled novel tests of general relativity, including direct study of the polarization of gravitational waves. While general relativity allows for only two tensor gravitational-wave polarizations, general metric theories can additionally predict two vector and two scalar polarizations. The polarization of gravitational waves is encoded in the spectral shape of the stochastic gravitational-wave background, formed by the superposition of cosmological and individually unresolved astrophysical sources. Using data recorded by Advanced LIGO during its first observing run, we search for a stochastic background of generically polarized gravitational waves. We find no evidence for a background of any polarization, and place the first direct bounds on the contributions of vector and scalar polarizations to the stochastic background. Under log-uniform priors for the energy in each polarization, we limit the energy densities of tensor, vector, and scalar modes at 95% credibility to Ω_{0}^{T}<5.58×10^{-8}, Ω_{0}^{V}<6.35×10^{-8}, and Ω_{0}^{S}<1.08×10^{-7} at a reference frequency f_{0}=25  Hz.

In Situ Monitoring of MicroRNA Replacement Efficacy and Accurate Imaging-Guided Cancer Therapy through Light-Up Inter-Polyelectrolyte Nanocomplexes

Replacement of downregulated tumor-suppressive microRNA (Ts-miRNA) is recognized as an alternative approach for tumor gene therapy. However, in situ monitoring of miRNA replacement efficacy in a real-time manner via noninvasive imaging is continually challenging. Here, glutathione (GSH)-activated light-up peptide-polysaccharide-inter-polyelectrolyte nanocomplexes are established through self-assembly of carboxymethyl dextran with disulfide-bridged ("S-S") oligoarginine peptide (S-Arg4), in which microRNA-34a (miR-34a) and indocyanine green (ICG) are simultaneously embedded and the nanocomplexes are subsequently stabilized by intermolecular cross-linking. Upon confinement within the robust nanocomplexes, the near-infrared fluorescence (NIRF) of ICG is considerably quenched ("off") due to the aggregation-caused quenching effect. However, after intracellular delivery, the disulfide bond in S-Arg4 can be cleaved by intracellular GSH, which leads to the dissociation of nanocomplexes and triggers the simultaneous release of miR-34a and ICG. The NIRF of ICG is concomitantly activated through dequenching of the aggregated ICG. Very interestingly, a good correlation between time-dependent increase in NIRF intensity and miR-34a replacement efficacy is found in nanocomplexes-treated tumor cells and tumor tissues through either intratumoral or intravenous injections. Systemic nanocomplexes-mediated miR-34a replacement significantly suppresses the growth of HepG-2- and MDA-MB-231-derived tumor xenografts, and provides a pronounced survival benefit in these animal models.

Adhesive and Stimulus-Responsive Polydopamine-Coated Graphene Oxide System for Pesticide-Loss Control

Pesticide carrier systems are highly desirable in achieving the effective utilization of pesticides and reduction of their loss. In order to increase utilization and enhance pesticide adhesion to harmful targets, adhesive and stimulus-responsive nanocomposites were prepared using graphene oxide (GO) and polydopamine (PDA). The results demonstrated that graphene oxide with a layer of PDA had a high hymexazol-loading capacity. The release curve of hymexazol from the nanocomposite showed that the release was NIR-laser-dependent and pH-dependent. The adhesion-performance investigation demonstrated that Hy-GO@PDA exhibited greater hymexazol persistence than a hymexazol solution after a simulated-rainwash experiment, and it also left more hymexazol residue than a hymexazol solution with a surfactant under high concentrations. Finally, the bioactivity of the prepared hymexazol-loaded nanocomposite was measured against Fusarium oxysporum f. sp. cucumebrium Owen, and it showed an inhibition activity similar to that of the hymexazol solution. All of these revealed that GO with a PDA layer could serve as pesticide carrier to solve low-utilization and wash-off problems, especially for water-soluble pesticides.

Nucleosome-inspired nanocarrier obtains encapsulation efficiency enhancement and side effects reduction in chemotherapy by using fullerenol assembled with doxorubicin

Chemodrugs have been widely used to treat cancer; however, the chemotherapy usually leads to serious side effects and failure. Various nanomaterials and strategies have been explored for drug delivery to improve the efficacy of chemodrugs. One key to loading chemodrugs onto a nano-delivery system is enhancement of the encapsulation efficiency, especially for polymeric nanoparticles being loaded with hydrophilic drugs. Inspired by the ability of eukaryote to package millions of genes in the nucleus wrapping and condensing DNA around histones to form chromosomes, here we developed a karyon-like hybrid nanoparticle to achieve ultra-high encapsulation of doxorubicin (Dox) with reduced side effects. We utilized fullerenol as a "histone", packaged a great number of Dox, and used PEG-PLGA as the "karyotheca" coating the "nucleosome" (fullerenol and Dox complex) to stabilize the complex. It is noteworthy that the encapsulation efficiency of Dox in the polymeric micelles was increased from ∼5% to ∼79%. What's more, the biomimetic-inspired delivery system significantly reduced the chemodrug side effects by utilizing the radical scavenging ability of fullerenol. This novel drug-delivery design approach provides useful insights for improving the applicability of fullerenol in drug delivery systems for cancer therapy.

GW170817: Implications for the Stochastic Gravitational-Wave Background from Compact Binary Coalescences

The LIGO Scientific and Virgo Collaborations have announced the event GW170817, the first detection of gravitational waves from the coalescence of two neutron stars. The merger rate of binary neutron stars estimated from this event suggests that distant, unresolvable binary neutron stars create a significant astrophysical stochastic gravitational-wave background. The binary neutron star component will add to the contribution from binary black holes, increasing the amplitude of the total astrophysical background relative to previous expectations. In the Advanced LIGO-Virgo frequency band most sensitive to stochastic backgrounds (near 25 Hz), we predict a total astrophysical background with amplitude Ω_{GW}(f=25  Hz)=1.8_{-1.3}^{+2.7}×10^{-9} with 90% confidence, compared with Ω_{GW}(f=25  Hz)=1.1_{-0.7}^{+1.2}×10^{-9} from binary black holes alone. Assuming the most probable rate for compact binary mergers, we find that the total background may be detectable with a signal-to-noise-ratio of 3 after 40 months of total observation time, based on the expected timeline for Advanced LIGO and Virgo to reach their design sensitivity.

Photosensitive Nanoparticles Combining Vascular-Independent Intratumor Distribution and On-Demand Oxygen-Depot Delivery for Enhanced Cancer Photodynamic Therapy

In drug delivery, the poor tumor perfusion results in disappointing therapeutic efficacy. Nanomedicines for photodynamic therapy (PDT) greatly need deep tumor penetration due to short lifespan and weak diffusion of the cytotoxic reactive oxygen species (ROS). The damage of only shallow cells can easily cause invasiveness and metastasis. Moreover, even if the nanomedicines enter into deeper lesion, the effectiveness of PDT is limited due to the hypoxic microenvironment. Here, a deep penetrating and oxygen self-sufficient PDT nanoparticle is developed for balanced ROS distribution within tumor and efficient cancer therapy. The designed nanoparticles (CNPs/IP) are doubly emulsified (W/O/W) from poly(ethylene glycol)-poly(ε-caprolactone) copolymers doped with photosensitizer IR780 in the O layer and oxygen depot perfluorooctyl bromide (PFOB) inside the core, and functionalized with the tumor penetrating peptide Cys-Arg-Gly-Asp-Lys (CRGDK). The CRGDK modification significantly improves penetration depth of CNPs/IP and makes the CNPs/IP arrive at both the periphery and hypoxic interior of tumors where the PFOB releases oxygen, effectively alleviating hypoxia and guaranteeing efficient PDT performance. The improved intratumoral distribution of photosensitizer and adequate oxygen supply augment the sensitivity of tumor cells to PDT and significantly improve PDT efficiency. Such a nanosystem provides a potential platform for improved therapeutic index in anticancer therapy.

Global land-water nexus: Agricultural land and freshwater use embodied in worldwide supply chains

As agricultural land and freshwater inextricably interrelate and interact with each other, the conventional water and land policy in "silos" should give way to nexus thinking when formulating the land and water management strategies. This study constructs a systems multi-regional input-output (MRIO) model to expound global land-water nexus by simultaneously tracking agricultural land and freshwater use flows along the global supply chains. Furthermore, land productivity and irrigation water requirements of 160 crops in different regions are investigated to reflect the land-water linkage. Results show that developed economies (e.g., USA and Japan) and major large developing economies (e.g., mainland China and India) are the overriding drivers of agricultural land and freshwater use globally. In general, significant net transfers of these two resources are identified from resource-rich and less-developed economies to resource-poor and more-developed economies. For some crops, blue water productivity is inversely related to land productivity, indicating that irrigation water consumption is sometimes at odds with land use. The results could stimulus international cooperation for sustainable land and freshwater management targeting on original suppliers and final consumers along the global supply chains. Moreover, crop-specific land-water linkage could provide insights for trade-off decisions on minimizing the environmental impacts on local land and water resources.

A peculiar low-luminosity short gamma-ray burst from a double neutron star merger progenitor

Double neutron star (DNS) merger events are promising candidates of short gamma-ray burst (sGRB) progenitors as well as high-frequency gravitational wave (GW) emitters. On August 17, 2017, such a coinciding event was detected by both the LIGO-Virgo gravitational wave detector network as GW170817 and Gamma-Ray Monitor on board NASA’s Fermi Space Telescope as GRB 170817A. Here, we show that the fluence and spectral peak energy of this sGRB fall into the lower portion of the distributions of known sGRBs. Its peak isotropic luminosity is abnormally low. The estimated event rate density above this luminosity is at least \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$190_{ - 160}^{ + 440}$$\end{document}190-160+440 Gpc⁻³ yr⁻¹, which is close to but still below the DNS merger event rate density. This event likely originates from a structured jet viewed from a large viewing angle. There are similar faint soft GRBs in the Fermi archival data, a small fraction of which might belong to this new population of nearby, low-luminosity sGRBs.

A short-duration gamma-ray burst was detected along with a double neutron start merger gravitational wave by LIGO-Virgo on August 17th 2017. Here, the authors show that the fluence and spectral peak energy of this event fall into the lower portion of the distribution of known short-duration gamma-ray bursts.

First Search for Nontensorial Gravitational Waves from Known Pulsars

We present results from the first directed search for nontensorial gravitational waves. While general relativity allows for tensorial (plus and cross) modes only, a generic metric theory may, in principle, predict waves with up to six different polarizations. This analysis is sensitive to continuous signals of scalar, vector, or tensor polarizations, and does not rely on any specific theory of gravity. After searching data from the first observation run of the advanced LIGO detectors for signals at twice the rotational frequency of 200 known pulsars, we find no evidence of gravitational waves of any polarization. We report the first upper limits for scalar and vector strains, finding values comparable in magnitude to previously published limits for tensor strain. Our results may be translated into constraints on specific alternative theories of gravity.

GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral

On August 17, 2017 at 12∶41:04 UTC the Advanced LIGO and Advanced Virgo gravitational-wave detectors made their first observation of a binary neutron star inspiral. The signal, GW170817, was detected with a combined signal-to-noise ratio of 32.4 and a false-alarm-rate estimate of less than one per 8.0×10^{4}  years. We infer the component masses of the binary to be between 0.86 and 2.26  M_{⊙}, in agreement with masses of known neutron stars. Restricting the component spins to the range inferred in binary neutron stars, we find the component masses to be in the range 1.17-1.60  M_{⊙}, with the total mass of the system 2.74_{-0.01}^{+0.04}M_{⊙}. The source was localized within a sky region of 28  deg^{2} (90% probability) and had a luminosity distance of 40_{-14}^{+8}  Mpc, the closest and most precisely localized gravitational-wave signal yet. The association with the γ-ray burst GRB 170817A, detected by Fermi-GBM 1.7 s after the coalescence, corroborates the hypothesis of a neutron star merger and provides the first direct evidence of a link between these mergers and short γ-ray bursts. Subsequent identification of transient counterparts across the electromagnetic spectrum in the same location further supports the interpretation of this event as a neutron star merger. This unprecedented joint gravitational and electromagnetic observation provides insight into astrophysics, dense matter, gravitation, and cosmology.

Dynamic annealing in Ge studied by pulsed ion beams

The formation of radiation damage in Ge above room temperature is dominated by complex dynamic annealing processes, involving migration and interaction of ballistically-generated point defects. Here, we study the dynamics of radiation defects in Ge in the temperature range of 100-160 °C under pulsed beam irradiation with 500 keV Ar ions when the total ion fluence is split into a train of equal square pulses. By varying the passive portion of the beam duty cycle, we measure a characteristic time constant of dynamic annealing, which rapidly decreases from ~8 to 0.3 ms with increasing temperature. By varying the active portion of the beam duty cycle, we measure an effective diffusion length of ~38 nm at 110 °C. Results reveal a major change in the dominant dynamic annealing process at a critical transition temperature of ~130 °C. The two dominant dynamic annealing processes have an order of magnitude different activation energies of 0.13 and 1.3 eV.

Effect of antibiotic, probiotic, and human rotavirus infection on colonisation dynamics of defined commensal microbiota in a gnotobiotic pig model

We developed a gnotobiotic (Gn) pig model colonised with defined commensal microbiota (DMF) to provide a simplified and controlled system to study the interactions between intestinal commensals, antibiotics (ciprofloxacin, CIP), probiotics (Escherichia coli Nissle 1917, EcN) and virulent human rotavirus (VirHRV). The DMF included seven gut commensal species of porcine origin that mimic the predominant species in the infant gut. Gn piglets were divided into four groups: DMF control (non-treated), DMF+CIP (CIP treated), DMF+CIP+EcN (CIP/EcN treated), DMF+EcN (EcN treated) and inoculated orally with 10⁵ cfu of each DMF strain. The pig gut was successfully colonised by all DMF species and established a simplified bacterial community by post-bacteria colonisation day (PBCD) 14/post-VirHRV challenge day (PCD) 0. Overall, Bifidobacterium adolescentis was commonly observed in faeces in all groups and time points. At PCD0, after six days of CIP treatment (DMF+CIP), we observed significantly decreased aerobic and anaerobic bacteria counts especially in jejunum (P<0.001), where no DMF species were detected in jejunum by T-RFLP. Following HRV challenge, 100% of pigs in DMF+CIP group developed diarrhoea with higher diarrhoea scores and duration as compared to all other groups. However, only 33% of pigs treated with EcN plus CIP developed diarrhoea. EcN treatment also enhanced the bacterial diversity and all seven DMF species were detected with a higher proportion of Bifidobacterium longum in jejunum in the DMF+CIP+EcN group on PBCD14/PCD0. Our results suggest that EcN increased the proportion of B. longum especially in jejunum and mitigated adverse impacts of antibiotic use during acute-infectious diarrhoea. The DMF model with a simplified gut commensal community can further our knowledge of how commensals and probiotics promote intestinal homeostasis and contribute to host health.

GW170814: A Three-Detector Observation of Gravitational Waves from a Binary Black Hole Coalescence

On August 14, 2017 at 10∶30:43 UTC, the Advanced Virgo detector and the two Advanced LIGO detectors coherently observed a transient gravitational-wave signal produced by the coalescence of two stellar mass black holes, with a false-alarm rate of ≲1 in 27 000 years. The signal was observed with a three-detector network matched-filter signal-to-noise ratio of 18. The inferred masses of the initial black holes are 30.5_{-3.0}^{+5.7}M_{⊙} and 25.3_{-4.2}^{+2.8}M_{⊙} (at the 90% credible level). The luminosity distance of the source is 540_{-210}^{+130}  Mpc, corresponding to a redshift of z=0.11_{-0.04}^{+0.03}. A network of three detectors improves the sky localization of the source, reducing the area of the 90% credible region from 1160   deg^{2} using only the two LIGO detectors to 60  deg^{2} using all three detectors. For the first time, we can test the nature of gravitational-wave polarizations from the antenna response of the LIGO-Virgo network, thus enabling a new class of phenomenological tests of gravity.

[Association between the types of obesity and the 10-year-coronary heart disease risk, in Tibet Autonomous Region and Xinjiang Uygur Autonomous Region]

Objective: To investigate the association between types of obesity and the 10-year-coronary heart disease risk in Tibet and Xinjiang of China. Methods: Using the multi-stage random sampling method, 7 631 participants aged 35 or older were examined under the International Standardized Examination process but with only 5 802 were eligible for analysis, in the 2015-2016 season. Results: The prevalence rates of general obesity, central obesity, visceral obesity and compound obesity were 0.53%, 12.62%, 10.08% and 42.35%, respectively. Out of all the compound obesity cases, 58.65% (1 441/2 457) of them appeared as having all types of obesity in our study. Risk related to the 10-year-coronary heart disease was higher in men than in women [(3.05±4.14)% vs. (1.42±2.37) %, P<0.000 1. Compound obesity (30.16%) showed the highest proportion on the risk of 10-year-coronary heart disease than central obesity (28.01%), visceral obesity (18.46%) or the general obesity (19.35%). After adjustment for confounding factors, results from the multivariate analysis showed the risk in compound obesity was higher than central obesity, visceral obesity or general obesity and was associated with the highest risk on the 10-year-coronary heart disease (OR=2.889, 95%CI: 2.525-3.305). People with anomalous BMI and WC seemed to have had the higher risk (OR=3.168, 95%CI: 2.730-3.677). Conclusions: Obesity was popular in the residents of Tibet and Xinjiang areas of China. Men and people with compound obesity (especially both BMI and WC were abnormal) seemed to carry greater risk on the 10-year-coronary heart disease.

The use of susceptibility-weighted imaging to detect cerebral microbleeds after lacunar infarction

OBJECTIVE

To study the value of susceptibility-weighted imaging (SWI) technology to detect cerebral microbleeds (CMBs) in senile cerebral lacunar infarction patients; and to evaluate the complicated cerebral hemorrhage risk after patients with CMBs took aspirin, an antiplatelet medication or received anticoagulant therapy.

PATIENTS AND METHODS

MRI scanning, using GRE-T2*WI, SWI and FSE sequences (T1WI, T2WI, and T2FLAIR), was performed on the three groups: (1) a cerebral lacunar infarction group; (2) cerebral lacunar infarction with cerebral microbleeds (CMBs) group; and (3) a healthy elderly group. A total of 60 cases were in each group (180 total patients). In addition, the lacunar infarction group and lacunar infarction with CMBs groups were both treated with formal antiplatelet or anticoagulant therapy, according to medical guidelines. Patients were followed for 12 months, during which time their cerebral hemorrhages and post-event effects were observed. The relativity of CMBs, antiplatelet therapy, anticoagulant therapy and cerebral hemorrhage transformation was analyzed and defined. The two groups of research patients with lacunar infarctions were scanned with relevant sequences.

RESULTS

The SWI scanning sequence showed the highest positive rate of CMBs, followed by GRE-T2*WI and other conventional scanning sequences. T1WI, T2WI and T2FLAIR showed a relatively lower positive rate of CMBs. In the cerebral lacunar infarction group and healthy elderly group, 34 cases in the SWI sequence showed 84 positive sites; 18 cases in the GRE-T2*WI sequence showed 40 positive sites; 2 cases in the T1WI sequence showed 4 positive sites; and 6 cases in the T2WI sequence showed 11 positive sites. After a chi-squared test, the differences between the sequences were statistically significant (p < 0.05). In the lacunar infarction group, 26 cases (43.33%) exhibited microbleeding lesions, while the normal control group represented 8 cases (13.33%). The lacunar infarction group exhibited mild, moderate and severe cases, the three types of CMBs. The normal control group only showed mild hemorrhaging. The degree of lacunar infarction was significantly related to the severity of CMBs (p < 0.05). After patients with CMBs had received formal antiplatelet therapy and anticoagulation therapy, one case in the lacunar infarction with microbleeds group showed cerebral hemorrhaging, but this had no statistical significance (p > 0.05).

CONCLUSIONS

The SWI scanning sequence is more sensitive than the GRE-T2*WI sequence. The GRE-T2*WI sequence is more sensitive than the conventional FSE sequence. SWI is highly sensitive and specific to the diagnosis of CMBs. It is an accurate and effective method for the analysis and diagnosis of CMBs. If patients with CMBs caused by lacunar infarction are treated with antiplatelet and anticoagulant therapy, the risk of cerebral hemorrhagic transformation is relatively smaller within 12 months. However, this needs to be observed further to define possible long-term risks.

[Association between body fat percentage, visceral fat index and cardiometabolic risk factor clustering among population aged 35 year old or over, in Tibet Autonomous Region and Xinjiang Uygur Autonomous Region]

Objective: To investigate the association between body fat percentage (BFP), visceral fat index (VFI) and Cardiometabolic Risk Factor Clustering (CRFC), among population aged 35 or older in Tibet and Xinjiang areas. Methods: Using the stratified multi-stage random sampling method, 7 571 residents aged 35 or above were examined with international standardized examination between 2015 and 2016. Of the eligible 5 643 participants, association of BFP and VFI with CRFC was defined as having two or more of the four risk factors: hypertension, diabetes mellitus, high TG and low HDL-C, at the same time. Logistic regression analysis and receiver operating characteristic (ROC) curve analysis were employed to further explore the relationships. Results: The overall prevalence of CRFC among aged 35 and older population in Tibet and Xinjiang areas was 9.78%. BFP and VFI were divided into four groups by quartile. After adjustment for age, gender, race, cigarette smoking, alcohol consumption, education attainments, and altitude of residence, ORs of CRFC seemed to have increased with BFP and VFI. Compared with people having BFP of 5.0%-27.0%, the OR(95% CI) were 1.15(0.86-1.54), 1.48(1.05-2.07) and 1.72(1.10-2.68) for the ones who presented 27.1%-31.7%, 31.8%-36.6% and 36.7%-50.0% of BFP. Compared to people of having 1-6 of VFI, with OR (95%CI) as 1.20(0.81-1.79), 1.91(1.30-2.80) and 3.91(2.64-5.77) for the ones having 7-9, 10-13 and 14-30 of VFI. Areas under the curve (AUC) of CRFC appeared as 0.55 for BFP and 0.70 for VFI, respectively, with statistically significant difference (P<0.01). Conclusion: Both BFP and VFI levels were closely associated with CRFC while VFI seemed to have a better predictive value than the BFP.

Hybrid Prodrug Nanoparticles with Tumor Penetration and Programmed Drug Activation for Enhanced Chemoresistant Cancer Therapy

Despite nanomedicine having shown great potential for reversing cancer cell resistance, the suboptimal transport across multiple biological obstacles seriously impedes its reaching targets at an efficacious level, which remains a challenging hurdle for clinical success in resistant cancer therapy. Here, a lipid-based hybrid nanoparticle was designed to efficiently deliver the therapeutics to resistant cells and treat resistant cancer in vivo. The hybrid nanoparticles (D-NPs/tetrandrine (TET)) are composed of a pH-responsive prodrug 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE)-doxorubicin (DOX), an efflux inhibitor TET, and a surfactant DSPE-[methoxy (poly(ethylene glycol))-2000] (DSPE-mPEG₂₀₀₀), which hierarchically combatted the sequential physiological and pathological barriers of drug resistance and exhibited prolonged blood circulation, high tumor accumulation, and deep tumor parenchyma penetration. In the meantime, the programmed stepwise activation of encapsulated TET and DOX suppressed the function of resistance-related P-glycoprotein in a timely manner and facilitated the DOX sustained accommodation in tumor cells. Through systematic studies, the results show that such a nanosystem dramatically enhances drug potency and significantly overcomes the DOX resistance of breast cancer with negligible systemic toxicities. These findings provide new strategies to systemically combat chemoresistant cancers.

GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2

We describe the observation of GW170104, a gravitational-wave signal produced by the coalescence of a pair of stellar-mass black holes. The signal was measured on January 4, 2017 at 10∶11:58.6 UTC by the twin advanced detectors of the Laser Interferometer Gravitational-Wave Observatory during their second observing run, with a network signal-to-noise ratio of 13 and a false alarm rate less than 1 in 70 000 years. The inferred component black hole masses are 31.2_{-6.0}^{+8.4}M_{⊙} and 19.4_{-5.9}^{+5.3}M_{⊙} (at the 90% credible level). The black hole spins are best constrained through measurement of the effective inspiral spin parameter, a mass-weighted combination of the spin components perpendicular to the orbital plane, χ_{eff}=-0.12_{-0.30}^{+0.21}. This result implies that spin configurations with both component spins positively aligned with the orbital angular momentum are disfavored. The source luminosity distance is 880_{-390}^{+450}  Mpc corresponding to a redshift of z=0.18_{-0.07}^{+0.08}. We constrain the magnitude of modifications to the gravitational-wave dispersion relation and perform null tests of general relativity. Assuming that gravitons are dispersed in vacuum like massive particles, we bound the graviton mass to m_{g}≤7.7×10^{-23}  eV/c^{2}. In all cases, we find that GW170104 is consistent with general relativity.

Abstract P3-03-14: ERα propelled drug-resistance-facilitating global DNA hypermethylation by promoting the DNMT1 gene expression

This abstract was not presented at the symposium.

Improved frame-based estimation of head motion in PET brain imaging

PURPOSE

Head motion during PET brain imaging can cause significant degradation of image quality. Several authors have proposed ways to compensate for PET brain motion to restore image quality and improve quantitation. Head restraints can reduce movement but are unreliable; thus the need for alternative strategies such as data-driven motion estimation or external motion tracking. Herein, the authors present a data-driven motion estimation method using a preprocessing technique that allows the usage of very short duration frames, thus reducing the intraframe motion problem commonly observed in the multiple frame acquisition method.

METHODS

The list mode data for PET acquisition is uniformly divided into 5-s frames and images are reconstructed without attenuation correction. Interframe motion is estimated using a 3D multiresolution registration algorithm and subsequently compensated for. For this study, the authors used 8 PET brain studies that used F-18 FDG as the tracer and contained minor or no initial motion. After reconstruction and prior to motion estimation, known motion was introduced to each frame to simulate head motion during a PET acquisition. To investigate the trade-off in motion estimation and compensation with respect to frames of different length, the authors summed 5-s frames accordingly to produce 10 and 60 s frames. Summed images generated from the motion-compensated reconstructed frames were then compared to the original PET image reconstruction without motion compensation.

RESULTS

The authors found that our method is able to compensate for both gradual and step-like motions using frame times as short as 5 s with a spatial accuracy of 0.2 mm on average. Complex volunteer motion involving all six degrees of freedom was estimated with lower accuracy (0.3 mm on average) than the other types investigated. Preprocessing of 5-s images was necessary for successful image registration. Since their method utilizes nonattenuation corrected frames, it is not susceptible to motion introduced between CT and PET acquisitions.

CONCLUSIONS

The authors have shown that they can estimate motion for frames with time intervals as short as 5 s using nonattenuation corrected reconstructed FDG PET brain images. Intraframe motion in 60-s frames causes degradation of accuracy to about 2 mm based on the motion type.

Two-Step Assembling of Near-Infrared "OFF-ON" Fluorescent Nanohybrids for Synchronous Tumor Imaging and MicroRNA Modulation-Based Therapy

Theranostic nanoparticles with combined imaging and therapy functions show great promise in cancer precision medicine. In this study, we constructed near-infrared (NIR) "OFF-ON" fluorescent nanohybrids (F-PNDs) for synchronous tumor imaging and microRNA (miRNA) modulation therapy against esophageal cancer. Nanodiamond clusters (NDs) were first functionalized for protamine sulfate immobilization (PNDs) on their surfaces via a noncovalent self-assembling approach and simultaneous encapsulation of NIR emitting fluorescence dye cyanine 5 (Cy-5) (F-PNDs). Tumor suppressor miRNA-203 (miR-203) was then adsorbed onto the surface of F-PNDs to form miR-203/F-PNDs via electrostatic interactions. The size, morphology, photophysical and stability properties of miR-203/F-PNDs were analyzed. We found that the NIR fluorescence of miR-203/F-PNDs could be activated to the "ON" state in intracellular environment while remaining in the "OFF" state in extracellular or blood environment. Furthermore, in vivo live imaging experiments showed that miR-203/F-PNDs could be predominantly accumulated in tumor tissues and image the tumor sites 24 h postintravenous injection. In addition, intravenous and intratumoral injection of miR-203/F-PNDs could efficiently inhibit tumor growth through down-regulation of the expressions of oncogenes Ran and Δp63. Our study indicated that miRNA/F-PNDs could serve as a promising theranostic platform for synchronous tumor imaging and miRNA-based modulation therapy against cancer.

Mesoporous Silica Coated Polydopamine Functionalized Reduced Graphene Oxide for Synergistic Targeted Chemo-Photothermal Therapy

The integration of different therapies into a single nanoplatform has shown great promise for synergistic tumor treatment. Herein, mesoporous silica (MS) coated polydopamine functionalized reduced graphene oxide (pRGO) further modified with hyaluronic acid (HA) (pRGO@MS-HA) has been utilized as a versatile nanoplatform for synergistic targeted chemo-photothermal therapy against cancer. A facile and green chemical method is adopted for the simultaneous reduction and noncovalent functionalization of graphene oxide (GO) by using mussel inspired dopamine (DA) to enhance biocompatibility and the photothermal effect. Then, it was coated with mesoporous silica (MS) (pRGO@MS) to enhance doxorubicin (DOX) loading and be further modified with the targeting moieties hyaluronic acid (HA). The pH-dependent and near-infrared (NIR) laser irradiation-triggered DOX release from pRGO@MS(DOX)-HA is observed, which could enhance the chemo-photothermal therapy effect. In vitro experimental results confirm that pRGO@MS(DOX)-HA exhibits good dispersibility, excellent photothermal property, remarkable tumor cell killing efficiency, and specificity to target tumor cells. In vivo antitumor experiments further demonstrated that pRGO@MS(DOX)-HA could exhibit an excellent synergistic antitumor efficacy, which is much more distinct than any monotherapy. This work presents a novel nanoplatform which could load chemotherapy drugs with high efficiency and be used as light-mediated photothermal cancer therapy agent.

The role of Frenkel defect diffusion in dynamic annealing in ion-irradiated Si

The formation of stable radiation damage in crystalline solids often proceeds via complex dynamic annealing processes, involving migration and interaction of ballistically-generated point defects. The dominant dynamic annealing processes, however, remain unknown even for crystalline Si. Here, we use a pulsed ion beam method to study defect dynamics in Si bombarded in the temperature range from -20 to 140 °C with 500 keV Ar ions. Results reveal a defect relaxation time constant of ~10-0.2 ms, which decreases monotonically with increasing temperature. The dynamic annealing rate shows an Arrhenius dependence with two well-defined activation energies of 73 ± 5 meV and 420 ± 10 meV, below and above 60 °C, respectively. Rate theory modeling, bench-marked against this data, suggests a crucial role of both vacancy and interstitial diffusion, with the dynamic annealing rate limited by the migration and interaction of vacancies.