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Background A subset of hospitalized patients will require critical care after their gastrointestinal endoscopy (GIE) and predicting which patients are at high risk of requiring critical care remains an important challenge. Purpose To identify protective and aggravating clinical risk factors associated with critical care involvement within 7 days of inpatient GIE in adults and to develop a tool that could assist in risk-stratifying patients at high risk of requiring critical care post-endoscopy. Method This was a single-centre retrospective case-control study of adult patients who underwent inpatient GIE while admitted to ward-level care at Toronto General Hospital from years 2015 to 2019. Cases were defined by inpatients who required critical care response team and/or critical care admission within 7 days of GIE, compared to control patients who did not require critical care throughout admission. Chart review and linked secondary sources were used with defined inclusion and exclusion criteria. Both univariate and multivariate analyses were performed comparing patient baseline, clinical history (including cardiovascular, respiratory, other co-morbidities) and endoscopy characteristics. Result(s) We identified a total of 275 patients with 302 endoscopies as cases and 2069 patient controls who satisfied inclusion criteria. Critical care involvement was most commonly due to cardiovascular-related complications (n=175, 58%) followed by respiratory complications (n=117, 39%). Amongst cases, death occurred in 9 (3%), 25 (9%) and 67 (22%) within 72 hours, 7 days and 30 days respectively post endoscopy. The strongest associations with critical care involvement within 7 days after GIE included a history of discharge from critical care (OR 2.29 CI 1.70-3.04) and/or recent mechanical ventilatory support (OR 2.27 CI 1.30-3.91) in the 30 days prior to endoscopy, having several co-morbidities involving major organ systems (elevated troponin OR 3.20 CI 2.26-4.52, cirrhosis OR 2.5 CI 1.80-3.46, renal dysfunction 2.09 CI 1.57-2.78) and patients admitted under surgical (OR 3.82 CI 2.54-5.71) or transplant services (OR 4.63 CI 2.94-7.26). The majority of adverse events among cases were not found to be complications directly related to GIE (64% unlikely, 20% possible, 9% probable, 7% definite). Patients with a history of pulmonary hypertension (OR 5.68 CI 0.53-60.70) and ASA score III/IV (OR 3.28 CI 1.01-10.73) had the highest odds of probable or definite endoscopy-related adverse events. Conclusion(s) This study is the largest to date to examine risk factors associated with critical care requirements post GIE in the tertiary care inpatient setting. The risk factors we have identified can be used to create a tool to determine which inpatients may benefit from anesthesia consultation and support during their endoscopic procedure. Please acknowledge all funding agencies by checking the applicable boxes below None Disclosure of Interest None Declared

The 7D Surgical Machine-vision Image-Guided Surgery (IGS) (MvIGS) system provides surgical guidance to spinal and cranial procedures where high navigation accuracy is required. By leveraging machine vision technologies, the 7D Surgical MvIGS System has the advantage of allowing surgeons to quickly achieve image registration and start navigation without the need for intraoperative radiation-emitting devices or laborious traditional point matching techniques. The 7D Surgical MvIGS System uses an all-optical nonionizing structured light to acquire a three-dimensional (3D) surface scan of the patient. Advanced machine vision algorithms are then used to register the 3D surface to a preoperative scan of the patient. This approach reduces the need for intraoperative X-rays, significantly reducing the surgeon’s, the staff’s, and the patient’s exposure to radiation. By leveraging the intraoperative high-resolution optical surface data acquired from the patient and machine vision algorithms, the 7D Surgical MvIGS System significantly reduces the steps required to set up and operate an IGS system leading to an unprecedentedly fast workflow which we call Flash Registration. Fewer required user interactions with the system also allow for a short learning curve. These innovations have resulted in an IGS system that is more accessible to a broader user base, while providing a radiation-free surgical environment for surgeons, hospital staff, and patients.

Intraoperative image-guided surgical navigation for craniospinal procedures has significantly improved accuracy by providing an avenue for the surgeon to visualize underlying internal structures corresponding to the exposed surface anatomy. Despite the obvious benefits of surgical navigation, surgeon adoption remains relatively low due to long setup and registration times, steep learning curves, and workflow disruptions. We introduce an experimental navigation system utilizing optical topographical imaging (OTI) to acquire the 3D surface anatomy of the surgical cavity, enabling visualization of internal structures relative to exposed surface anatomy from registered preoperative images. Our OTI approach includes near instantaneous and accurate optical measurement of >250,000 surface points, computed at >52,000 points-per-second for considerably faster patient registration than commercially available benchmark systems without compromising spatial accuracy. Our experience of 171 human craniospinal surgical procedures, demonstrated significant workflow improvement (41 s vs. 258 s and 794 s, p

Collective memory studies have emphasized how people can utilize important historical events as analogies to make sense of current happenings. This article argues that the invocation of historical analogies may, under certain circumstances, become an occasion for people to negotiate and contest the significance of the historical events. Focusing on Hong Kong’s Umbrella Movement in 2014, this article analyzes how references to the 1989 Tiananmen Incident emerged in the news as a dominant historical analogy when the movement began, foregrounding the possibility of state violence. But when state violence did not materialize, the authorities, young protesters, and radical activists started to contest the relevance of Tiananmen. The analogy was largely abandoned by the movement’s end. The analysis illustrates the recursive character of the relationship between past and present events: after the past is invoked to aid interpretations of the present, present developments may urge people to reevaluate the past.

Obese patients have lower sepsis mortality termed the "obesity paradox." We hypothesized that lipopolysaccharide, known to be carried within lipoproteins such as very low density lipoprotein, could be sequestered in adipose tissue during sepsis; potentially contributing a survival benefit.Retrospective analysis.University research laboratory.Vldlr knockout mice to decrease very low density lipoprotein receptors, Pcsk9 knockout mice to increase very low density lipoprotein receptor, and Ldlr knockout mice to decrease low density lipoprotein receptors. Differentiated 3T3-L1 adipocytes. Caucasian septic shock patients.We measured lipopolysaccharide uptake into adipose tissue 6 hours after injection of fluorescent lipopolysaccharide into mice. Lipopolysaccharide uptake and very low density lipoprotein receptor protein expression were measured in adipocytes. To determine relevance to humans, we genotyped the VLDLR rs7852409 G/C single-nucleotide polymorphism in 519 patients and examined the association of 28-day survival with genotype.Lipopolysaccharide injected into mice was found in adipose tissue within 6 hours and was dependent on very low density lipoprotein receptor but not low density lipoprotein receptors. In an adipocyte cell line decreased very low density lipoprotein receptor expression resulted in decreased lipopolysaccharide uptake. In septic shock patients, the minor C allele of VLDLR rs7852409 was associated with increased survival (p = 0.010). Previously published data indicate that the C allele is a gain-of-function variant of VLDLR which may increase sequestration of very low density lipoprotein (and lipopolysaccharide within very low density lipoprotein) into adipose tissue. When body mass index less than 25 this survival effect was accentuated and when body mass index greater than or equal to 25 this effect was diminished suggesting that the effect of variation in very low density lipoprotein receptor function is overwhelmed when copious adipose tissue is present.Lipopolysaccharide may be sequestered in adipose tissue via the very low density lipoprotein receptor and this sequestration may contribute to improved sepsis survival.

Previous studies have shown lipopolysaccharide from Gram-negative bacteria is cleared from the circulation via LDL receptors on hepatocytes, which are downregulated by PCSK9. Whether clearance of Gram positive bacterial lipoteichoic acid (LTA) shows similar dependence on PCSK9, and whether this is clinically relevant in Gram positive human sepsis, is unknown. We examined survival data from three cohorts of patients who had Gram positive septic shock (n = 170, n = 130, and n = 59) and found that patients who carried a PCSK9 loss-of-function (LOF) allele had significantly higher 28-day survival (73.8%) than those with no LOF alleles (52.8%) (p = 0.000038). Plasma clearance of LTA was also found to be increased in PCSK9 knockout mice compared to wildtype control mice (p = 0.002). In addition, hepatocytes pre-treated with recombinant wildtype PCSK9 showed a dose-dependent decrease in uptake of fluorescently-labeled LTA (p

In this paper, we provide an introduction to machine learning tasks that address important problems in genomic medicine. One of the goals of genomic medicine is to determine how variations in the DNA of individuals can affect the risk of different diseases, and to find causal explanations so that targeted therapies can be designed. Here we focus on how machine learning can help to model the relationship between DNA and the quantities of key molecules in the cell, with the premise that these quantities, which we refer to as cell variables, may be associated with disease risks. Modern biology allows high-throughput measurement of many such cell variables, including gene expression, splicing, and proteins binding to nucleic acids, which can all be treated as training targets for predictive models. With the growing availability of large-scale data sets and advanced computational techniques such as deep learning, researchers can help to usher in a new era of effective genomic medicine.

High-density cholesterol (HDL-C) levels are influenced by genetic variation in several genes. Low levels of HDL-C have been associated with increased risk of acute kidney injury (AKI). We investigated whether genetic polymorphisms in ten genes known to regulate HDL-C levels are associated with both HDL-C levels and AKI development during sepsis. Two cohorts were retrospectively analyzed: Derivation Cohort (202 patients with sepsis enrolled at the Emergency Department from 2011 to 2014 in Vancouver, Canada); Validation Cohort (604 septic shock patients enrolled into the Vasopressin in Septic Shock Trial (VASST)). Associations between HDL-related genetic polymorphisms and both HDL-C levels, and risk for clinically significant sepsis-associated AKI (AKI KDIGO stages 2 and 3) were evaluated. In the Derivation Cohort, one genetic variant in the Cholesteryl Ester Transfer Protein (CETP) gene, rs1800777 (allele A), was strongly associated with lower HDL-C levels (17.4 mg/dL vs. 32.9 mg/dL, P = 0.002), greater CETP mass (3.43 µg/mL vs. 1.32 µg/mL, P = 0.034), and increased risk of clinically significant sepsis-associated AKI (OR: 8.28, p = 0.013). Moreover, the same allele was a predictor of sepsis-associated AKI in the Validation Cohort (OR: 2.38, p = 0.020). Our findings suggest that CETP modulates HDL-C levels in sepsis. CETP genotype may identify patients at high-risk of sepsis-associated AKI.

Background Patients with sepsis with a high ratio of visceral adipose tissue (VAT) to subcutaneous adipose tissue (SAT) have increased mortality. Our goal was to investigate the mechanism of this effect, noting that low LDL levels are also associated with increased sepsis mortality. Accordingly we tested for association between VAT/SAT, low-density lipoprotein (LDL) levels, and mortality. Then we examined the effect of statin treatment, which decreases LDL production, and the effect of PCSK9 genotype, which increases LDL clearance. Methods We performed retrospective analysis of a cohort of patients with sepsis from a tertiary care adult intensive care unit in Vancouver, Canada, who underwent abdominal computed tomography (CT) (n = 75) for clinical reasons. We compared LDL levels in patients with sepsis according to high versus low VAT/SAT and 90-day survival. We next examined the effects of statin therapy and PCSK9 loss-of-function genotype on survival. Results Patients with a low VAT/SAT had increased 90-day survival and were relatively protected against low LDL levels in sepsis compared to high VAT/SAT. Statin treatment abrogated the beneficial effects of low VAT/SAT; eliminating the difference in LDL levels and survival between patients with low and high VAT/SAT. PSCK9 loss-of-function genotype similarly eliminated the increased LDL levels in low VAT/SAT patients but, in contrast, increased the survival advantage of low VAT/SAT compared to high VAT/SAT. Conclusions Low LDL levels per se are not simply associated with decreased sepsis survival because lowering LDL levels by inhibiting LDL production (statin treatment) is associated with adverse outcomes, while increased LDL clearance (PCSK9 loss-of-function genotype) is associated with improved outcomes in patients with low VAT/SAT. Electronic supplementary material The online version of this article (10.1186/s13054-018-1985-1) contains supplementary material, which is available to authorized users.

Previous work has shown that lipid nanoparticles (LNP) composed of an ionizable cationic lipid, a poly(ethylene glycol) (PEG) lipid, distearoylphosphatidylcholine (DSPC), cholesterol, and small interfering RNA (siRNA) can be efficiently manufactured employing microfluidic mixing techniques. Cryo-transmission electron microscopy (cryo-TEM) and molecular simulation studies indicate that these LNP systems exhibit a nanostructured core with periodic aqueous compartments containing siRNA. Here we examine first how the lipid composition influences the structural properties of LNP-siRNA systems produced by microfluidic mixing and, second, whether the microfluidic mixing technique can be extended to macromolecules larger than siRNA. It is shown that LNP-siRNA systems can exhibit progressively more bilayer structure as the proportion of bilayer DSPC lipid is increased, suggesting that the core of LNP-siRNA systems can exhibit a continuum of nanostructures depending on the proportions and structural preferences of component lipids. Second, it is shown that the microfluidic mixing technique can also be extended to encapsulation of much larger negatively charged polymers such mRNA (1.7 kb) or plasmid DNA (6 kb). Finally, as a demonstration of the generality of the microfluidic mixing encapsulation process, it is also demonstrated that negatively charged gold nanoparticles (5 nm diameter) can also be efficiently encapsulated in LNP containing cationic lipids. Interestingly, the nanostructure of these gold-containing LNP reveals a "currant bun" morphology as visualized by cryo-TEM. This structure is fully consistent with LNP-siRNA structure predicted by molecular modeling.

This article analyses the rise and development of alternative Internet radio in Hong Kong in the past decade in tandem with the changing status of press freedom and contentious politics in the city. The article illustrates that alternative Internet radio first emerged a decade ago as the self-defence of the civil society against political encroachments on the media. Cognisant of the political potential of alternative Internet radio, pro-democracy radical political parties and social activists have subsequently appropriated this new medium to facilitate and engage in contentious politics. In the face of tightening political control of mainstream media in recent years, alternative Internet radio has become a “safe haven” for the exited rebel voices. Despite the considerable political significance of alternative Internet radio (and alternative Internet media in general) at this moment, its prospect remains uncertain due to potential regulatory control and increasing political pressures on Internet media in t...

Over the past decade in Hong Kong, net radio stations have served as alternative media safeguarding freedom of speech. Using the historical case of one pioneering alternative net radio station, the People's Radio Hong Kong (2004–2007), this article traces the historical emergence and development of alternative net radio in this democratizing city. The historical legacy of this exemplary station will also be discussed through the lens of recent developments. This case study aims to contribute to net radio research by exploring its political potential in terms of challenging the political-economic status quo.

The mortality rate in patients with haemodynamically unstable pelvic fractures is as high as 40–60%. Despite the new advances in trauma care which are in phase in trauma centres in Hong Kong, the management of haemodynamically unstable pelvic fracture is still heterogeneous. The aim of this study is to review the results of management of haemodynamically unstable pelvic fracture patients in Hong Kong over a five year period. This is a retrospective multi-centred cohort study of patients with haemodynamic and mechanically unstable pelvic fractures from 1 January 2010 to 31 December 2014. The primary outcome investigated is mortality of patients (including overall, 30-day, 7-day and 24-hour mortalities). Implementation of three-in-one pelvic damage control protocol was identified to be a significant independent predictive factor for overall, 30-day, seven-day and 24-hour mortalities. The overall in-hospital and 30-day mortality rates for patients managed with three-in-one protocol was 12.5%, while it was 11% for seven day mortality and 6% for 24 hour mortality. There were no significant differences in demographic characteristics, physiological measurements, types of pelvic fracture, severity and mechanism of injury between patients managed with or without three-in-one protocol. Implementation of the multidisciplinary three-in-one pelvic damage control protocol reduces mortality and therefore should be highly recommended. The results are convincing as it has eliminated the limitations of our previous single-centred trial.

Processing of transcripts at the 3’-end involves cleavage at a polyadenylation site followed by the addition of a poly(A)-tail. By selecting which polyadenylation site is cleaved, alternative polyadenylation enables genes to produce transcript isoforms with different 3’-ends. To facilitate the identification and treatment of disease-causing mutations that affect polyadenylation and to understand the underlying regulatory processes, a computational model that can accurately predict polyadenylation patterns based on genomic features is desirable. Previous works have focused on identifying candidate polyadenylation sites and classifying sites which may be tissue-specific. What is lacking is a predictive model of the underlying mechanism of site selection, competition, and processing efficiency in a tissue-specific manner. We develop a deep learning model that trains on 3’-end sequencing data and predicts tissue-specific site selection among competing polyadenylation sites in the 3’ untranslated region of the human genome.Two neural network architectures are evaluated: one built on hand-engineered features, and another that directly learns from the genomic sequence. The hand-engineered features include polyadenylation signals, cis-regulatory elements, n-mer counts, nucleosome occupancy, and RNA-binding protein motifs. The direct-from-sequence model is inferred without prior knowledge on polyadenylation, based on a convolutional neural network trained with genomic sequences surrounding each polyadenylation site as input. Both models are trained using the TensorFlow library.The proposed polyadenylation code can predict site selection among competing polyadenylation sites in different tissues. Importantly, it does so without relying on evolutionary conservation. The model can distinguish pathogenic from benign variants that appear near annotated polyadenylation sites in ClinVar and inspect the genome to find candidate polyadenylation sites. We also provide an analysis on how different features affect the model’s performance.

This paper describes the testing of wind turbine blades with tubercles in two different ways: outdoor testing and flow visualization. In the outdoor testing, the tubercle pitch was varied for turbine blade lengths of 30 cm, 40 cm, and 50 cm. The pitch-to-length ratio of approximately 1/10 to 1/16 produced the most power output. In flow visualization, both tubercle pitch and amplitude were varied. Vortices created behind the tubercles were shown to increase lift by minimizing flow separation.

Motivation: Alternative splicing (AS) is a regulated process that directs the generation of different transcripts from single genes. A computational model that can accurately predict splicing patterns based on genomic features and cellular context is highly desirable, both in understanding this widespread phenomenon, and in exploring the effects of genetic variations on AS. Methods: Using a deep neural network, we developed a model inferred from mouse RNA-Seq data that can predict splicing patterns in individual tissues and differences in splicing patterns across tissues. Our architecture uses hidden variables that jointly represent features in genomic sequences and tissue types when making predictions. A graphics processing unit was used to greatly reduce the training time of our models with millions of parameters. Results: We show that the deep architecture surpasses the performance of the previous Bayesian method for predicting AS patterns. With the proper optimization procedure and selection of hyperparameters, we demonstrate that deep architectures can be beneficial, even with a moderately sparse dataset. An analysis of what the model has learned in terms of the genomic features is presented. Contact: frey@psi.toronto.edu Supplementary information: Supplementary data are available at Bioinformatics online.

Background contextComputer-assisted navigation (CAN) may guide spinal instrumentation, and requires alignment of patient anatomy to imaging. Iterative closest-point (ICP) algorithms register anatomical and imaging surface datasets, which may fail in the presence of geometric symmetry (congruence), leading to failed registration or inaccurate navigation. Here we computationally quantify geometric congruence in posterior spinal exposures, and identify predictors of potential navigation inaccuracy.MethodsMidline posterior exposures were performed from C1-S1 in four human cadavers. An optically-based CAN generated surface maps of the posterior elements at each level. Maps were reconstructed to include bilateral hemilamina, or unilateral hemilamina with/without the base of the spinous process. Maps were fitted to symmetrical geometries (cylindrical/spherical/planar) using computational modelling, and the degree of model fit quantified based on the ratio of model inliers to total points. Geometric congruence was subsequently assessed clinically in 11 patients undergoing midline exposures in the cervical/thoracic/lumbar spine for posterior instrumented fusion.ResultsIn cadaveric testing, increased cylindrical/spherical/planar symmetry was seen in the high-cervical and subaxial cervical spine relative to the thoracolumbar spine (pConclusionsGeometric congruence is most evident at C1 and the subaxial cervical spine, warranting greater vigilance in navigation accuracy verification. At all levels, inclusion of the base of the spinous process in unilateral registration decreases the likelihood of geometric symmetry and navigation error. This work is important to allow the extension of line-of-sight based registration techniques to minimally-invasive unilateral approaches.

We present theoretical and experimental investigations on the growth of SnS van der Waals epitaxies (vdWEs) on graphene buffer layer (GBL). Local density approximation (LDA) was used to evaluate the bond length disorder, binding energies, and growth orientations for SnS deposited on crystalline semiconductor substrates with and without the GBL. Strong bond length disorder is observed for SnS deposited directly on GaAs substrates, whereas in the case where a GBL is used the disorder is substantially reduced. First-principle calculations indicate two favored growth orientations for SnS deposited on GBL resulting in 12 distinct peaks in the azimuthal hard X-ray diffraction (HXRD) scan due to the structural symmetry of the GBL. The results stipulate formation of strong chemical bonds at the GaAs/SnS interface while the interaction between SnS and the underlying GBL is dominated by vdW force. Nevertheless this vdW force is shown to be strong enough to induce favored nucleation orientations for the SnS and is e...

Au-seeded amorphous SiO 2 layer with crystalline GaN dot windows was fabricated on c -plane sapphire wafer. In order to compare the growth of ZnO nanostructures on amorphous SiO 2 with that on crystalline GaN directly, the Au-seeded SiO 2 –GaN co-substrates were used for the growth of ZnO nanowires by the vapor transport and deposition (VTD) technique. As-prepared ZnO nanowires were characterized by a scanning electron microscope (SEM) and a transmission electron microscope (TEM). The results show that there is an Au particle on the grown ZnO nanowire and the formation of ZnO nanowire on crystalline GaN is easier than that on amorphous SiO 2 . The experimental results were explained by the change of Zn contents in an Au–Zn droplet with the co-substrate positions during VTD process and ZnO epitaxial growth.

Driven by ever-changing business environment, technological innovations and changes of supply / demand markets are very common nowadays. These may create either risks or opportunities to power business operators. CLP Power Hong Kong Limited (CLPP), a power utility in Hong Kong, has therefore developed a systematic approach to ensure high reliability o f the High Vo ltage (HV) cable system wh ile driving the cost down. This paper shares CLPP's approach in three key parts, namely prudent design procedures, strategic sourcing of suppliers and installation management. Riding on the technology advancement of cable industry, HV s limCross-linked Polyethylene(XLPE) cable system is well proven learnt fro m the sound experience in Extra High Voltage (EHV) cable industry. The reduced cable size is beneficial for cable transportation, ergonomics and environ mental protection. The Co mpany's 2-level Strategic Sourcing Model helps source price co mpetit ive yet quality suppliers. W ith in-depth investigation in suppliers' long-term sustainability, the suppliers selected through this model created significant saving to the Co mpany without sacrificing system reliability. Together with the optimised installation and co mmissioning practices, the approach has delivered significant contributions to CLPP, such as maintaining high reliability, saving cost, securing cable material supply, and achieving high safety, health, environ ment and quality (SHEQ) performance.

In this paper we present systematic investigations on the growth of SnS van der Waals epitaxies (vdWEs) on different substrates, including crystalline and layered substrates, by molecular beam epitaxy (MBE). Experimental growth of SnS on conventional 3D substrates, such as GaAs, indicates strong interaction between the SnS layer and the substrate resulting in poor crystallinity in general. Substantial improvement in the film crystallinity can be obtained when the deposition is made on layered substrates, with saturated surface bonds, as observed in SnS films deposited on mica and crystalline substrates with a graphene buffer layer. Crystal size as large as one micron and rocking curve FWHM of 0.118° was observed despite the large lattice mismatches. This represents significant improvement over the reported value of ∼3°. Several symmetric growth orientations are observed for films grown on mica substrates. The results indicate that weak vdW interactions between the saturated bonds of the substrate surface and the SnS unit layer which is an important factor for achieving high quality epitaxy layered materials.

The detection of boldenone, nandrolone, 5(10)-estrene-3β,17α-diol, and 4-estrene-3,17-dione in a urine sample collected from a gelding having been treated with testosterone (500 mg 'Testosterone Suspension 100', single dose, injected intramuscularly) in 2009 led the authors' laboratory to suspect that these 'testicular' steroids could be minor metabolites of testosterone in geldings. Administration trials on six castrated horses with Testosterone Suspension 100 confirmed that low levels of boldenone, nandrolone, 5(10)-estrene-3β,17α-diol, and 4-estrene-3,17-dione could indeed be detected and confirmed in the early post-administration urine samples from all six geldings. Although boldenone has been reported to be present in urine after testosterone administration, there has been no direct evidence reported that boldenone, nandrolone, 5(10)-estrene-3β,17α-diol, and 4-estrene-3,17-dione are metabolites of testosterone in geldings. Subsequent in vitro experiments involving the incubation of testosterone with horse liver microsomes, liver, adipose and muscle tissues, and adrenal cortex homogenates failed to provide evidence that these four substances are minor metabolites of testosterone. An administration trial using 'Testosterone Suspension 100' supplemented with

Anabolic steroids are banned substances in equine sports. Gas chromatography-mass spectrometry (GC-MS) has been the traditional technique for doping control analysis of anabolic steroids in biological samples. Although liquid chromatography-mass spectrometry (LC/MS) has become an important technique in doping control, the detection of saturated hydroxysteroids by LC-MS remains a problem due to their low ionization efficiency under electrospray. The recent development in fast-scanning gas-chromatography-triple-quadrupole mass spectrometry (GC-MS/MS) has provided a better alternative with a significant reduction in chemical noise by means of selective reaction monitoring. Herein, we present a sensitive and selective method for the screening of over 50 anabolic steroids in equine urine using gas chromatography-tandem mass spectrometry (GC-MS/MS). Copyright © 2016 John WileySons, Ltd.

Lipid nanoparticles (LNP) containing ionizable cationic lipids are the leading systems for enabling therapeutic applications of siRNA; however, the structure of these systems has not been defined. Here we examine the structure of LNP siRNA systems containing DLinKC2-DMA(an ionizable cationic lipid), phospholipid, cholesterol and a polyethylene glycol (PEG) lipid formed using a rapid microfluidic mixing process. Techniques employed include cryo-transmission electron microscopy, (31)P NMR, membrane fusion assays, density measurements, and molecular modeling. The experimental results indicate that these LNP siRNA systems have an interior lipid core containing siRNA duplexes complexed to cationic lipid and that the interior core also contains phospholipid and cholesterol. Consistent with experimental observations, molecular modeling calculations indicate that the interior of LNP siRNA systems exhibits a periodic structure of aqueous compartments, where some compartments contain siRNA. It is concluded that LNP siRNA systems formulated by rapid mixing of an ethanol solution of lipid with an aqueous medium containing siRNA exhibit a nanostructured core. The results give insight into the mechanism whereby LNP siRNA systems are formed, providing an understanding of the high encapsulation efficiencies that can be achieved and information on methods of constructing more sophisticated LNP systems.

This study investigated the secondary electron production from a gold nanoparticle (GNP) irradiated by monoenergetic electron beams using Monte Carlo (MC) simulation. Spherical GNPs with diameters of 2, 50 and 100 nm in water were irradiated by monoenergetic electron beams with energies equal to 50 keV, 250 keV, 1 MeV and 4 MeV. MC simulations were performed using the Geant4 toolkit to determine the energy of the secondary electrons emitted from the GNPs. The mean effective range and deflection angle of the secondary electrons were tracked. Energy depositions inside and outside the nanoparticles due to the secondary electrons were also calculated. For comparisons, simulations were repeated by replacing the GNPs with water. Our results show that the mean effective range of secondary electrons increased with an increase of the GNP size and electron beam energy. For the electron beam energy and GNP size used in this study, the mean effective range was 0.5-15 µm outside the nanoparticle, which is approximately within the dimension of a living cell. The mean deflection angles varied from 78 to 83 degrees as per our MC results. The proportion of energy deposition inside the GNP versus that outside increased with the GNP size. This is different from the results obtained from a previous study using photon beams. The secondary electron energy deposition ratio (energy deposition for GNP/energy deposition for water) was found to be highest for the smallest GNP of 2 nm diameter in this study. For the energy deposited by the secondary electron, we concluded that the addition of GNPs can increase the secondary electron energy deposition in water, though most of the energy was self-absorbed by the large nanoparticles (50 and 100 nm). In addition, an electron source in the presence of GNPs does not seem to be better than photons as the yield of secondary electrons per unit mass of gold is less than water.

Quantum dot (QD) contrast-enhanced molecular imaging has potential for early cancer detection and image guided treatment, but there is a lack of quantitative image contrast data to determine optimum QD administered doses, affecting the feasibility, risk and cost of such procedures, especially in vivo. Vascular fluorescence contrast-enhanced imaging is performed on nude mice bearing dorsal skinfold window chambers, injected with 4 different QD solutions emitting in the visible and near infrared. Linear relationships are observed among the vascular contrast, injected contrast agent volume, and QD concentration in blood. Due primarily to differential light absorption by blood, the vasculature is optimally visualized when exciting in the 435-480 nm region in 81% of the cases (89 out of 110 regions of interest in 22 window chambers). The threshold dose, defined here as the quantity of injected nanoparticles required to yield a vascular target-to-autofluorescence ratio of 2, varies from 10.6 to 0.15 pmol g(-1) depending on the QD emission wavelength. The wavelength optimization maximum and broadband gain, defined as the ratio of threshold doses estimated for optimal and suboptimal (worst wavelength or broadband) spectral illumination, has average values of 4.5 and 1.9, respectively. This study demonstrates, for the first time, optimized QD imaging in vivo. It also proposes and validates a theoretical framework for QD dose estimation and quantifies the effects of blood absorption, QD emission wavelength, and vessel diameter relative to the threshold dose.

Limit size systems are defined as the smallest achievable aggregates compatible with the packing of the molecular constituents in a defined and energetically stable structure. Here we report the use of rapid microfluidic mixing for the controlled synthesis of two types of limit size lipid nanoparticle (LNP) systems, having either polar or nonpolar cores. Specifically, limit size LNP consisting of 1-palmitoyl, 2- oleoyl phosphatidylcholine (POPC), cholesterol and the triglyceride triolein were synthesized by mixing a stream of ethanol containing dissolved lipid with an aqueous stream, employing a staggered herringbone micromixer. Millisecond mixing of aqueous and ethanol streams at high flow rate ratios (FRR) was used to rapidly increase the polarity of the medium, driving bottom-up synthesis of limit size LNP systems by spontaneous assembly. For POPC/triolein systems the limit size structures consisted of a hydrophobic core of triolein surrounded by a monolayer of POPC where the diameter could be rationally engineered over the range 20−80 nm by varying the POPC/triolein ratio. In the case of POPC and POPC/cholesterol (55/45; mol/mol) the limit size systems achieved were bilayer vesicles of approximately 20 and 40 nm diameter, respectively. We further show that doxorubicin, a representative weak base drug, can be efficiently loaded and retained in limit size POPC LNP, establishing potential utility as drug delivery systems. To our knowledge this is the first report of stable triglyceride emulsions in the 20−50 nm size range, and the first time vesicular systems in the 20−50 nm size range have been generated by a scalable manufacturing method. These results establish microfluidic mixing as a powerful and general approach to access novel LNP systems, with both polar or nonpolar core structures, in the sub-100 nm size range.

ZnO nanowires were grown on Au-coated GaN layer on c-plane sapphire by chemical vapor deposition (CVD). As-prepared ZnO oxides were characterized by a scanning electron microscope (SEM) and a transmission electron microscope (TEM). The results show that the growth of ZnO nanowires strongly depends on the location of GaN/sapphire substrates. The diameters of the resulting nanowires were in the range 60 nm with typical length about 10μm. The formation of ZnO nanowires with different morphologies at various positions of the substrate is explained by the mechanisms of vapor-solid and vapor-liquid-solid, respectively.

We report investigations on the hot-electron hardness of GaN-based multiple quantum wells (MQWs) fabricated on nanoscale epitaxial lateral overgrown (NELO) GaN layers. This layer was deposited using a SiO 2 growth mask with nanometer-scale windows. The active regions of the devices consist of five-period GaN/InGaN MQWs. Structural analyses of the material indicate significant reduction in the threading dislocation density of the devices compared to the control which were fabricated without the use of the NELO GaN layers. The hot-electron degradation of the devices due to the application of a large dc. current was characterized by detailed examination of the electroluminescence (EL), I – V , thermoreflectance and the current noise power spectra of the devices as a function of the stress time. Significant improvements in the hot-electron hardness were observed in the device compared to the control.

Fabricated on nanoscale epitaxial lateral overgrown (NELO) GaN layers (type N) by metal-organic chemical vapor deposition using a SiO 2 layer with nanometer scale windows as the growth mask. Transmission electron microscopy (TEM) results clearly demonstrate coherent growth of GaN in the window regions while lateral growth is observed over the SiO 2 layer. Based on the TEM and atomic force microscopy measurements, we observed substantial reduction in the threading dislocation density for the type N GaN films. Experimental results on electroluminescence (EL) measurement indicate substantial improvement in the EL intensity as well as a 15 nm blue shift in the EL peak wavelength. High resolution X-ray diffraction and reciprocal space mapping characterizations clearly indicate significant reduction in strain generation in the MQWs grown on NELO GaN layers compared to the control samples (type C). Such reduction in strain generation in the MQW gives rise to the reduction in the quantum-confined Stark effect. This is also consistent with the observed blue-shift in the EL peak. Detailed analyses of the optoelectronic properties of the devices indicate significant improvements in the internal quantum efficiency, η i , and the extraction efficiency, η e , by as much as 55.8 and 57.3%, respectively, compared to the type C devices. The improvement in η i is attributed to reductions in both the nonradiative recombination centers and the quantum-confined Stark effect in the type N devices and the improvement in the extraction efficiency is attributed to the texturing of the GaN layer due to the incorporation of the SiO 2 layer with nanometer scale windows.

High-quality GaN/InGaN multiple quantum wells (MQWs) were fabricated on nano-scale epitaxial lateral overgrown (NELO) GaN layers. To grow the NELO layer first a 200 nm-thick SiO 2 was deposited on a 2 μm-thick undoped GaN layer. A 10 nm-thick Ni layer was then deposited on the SiO 2 film followed by an annealing process to form nano-scale Ni clusters. These Ni clusters will serve as a dry etch mask for the underlying SiO 2 layer, resulting in the formation of SiO 2 islands of diameter and inter-distance of 300 and 200 nm, respectively. Undoped NELO GaN layer of thickness 2 μm was grown on the template with SiO 2 growth mask using metal organic chemical vapor deposition technique. A 2 μm-thick n-GaN epilayer and a 5-period GaN/InGaN MQWs were grown on top of the NELO layer. It is found that the overgrown GaN epilayers exhibit a significant reduction in threading dislocation (TD). From the atomic force microscopy characterizations, the TD density reduces from 3 × 10 8 to 6 × 10 7 cm ―2 by utilizing the NELO technique. Optical properties of the MQWs deposited on the NELO layer (type N) were characterized by temperature-dependent photoluminescence (PL). The results are compared to a control structure (type C) grown in the same growth run as the type N structures but without the NELO layer. It is found that type N sample exhibits three-fold improvement in PL intensity at room temperature. The increase in external quantum efficiency arises from both enhanced extraction efficiency and internal quantum efficiency. Detailed temperature-dependent PL studies were conducted to evaluate the relative improvement in internal quantum efficiency to account for the improved material quality when MQWs were grown on top of NELO epilayers.

Purpose: The aim of this study is to understand the characteristics of secondary electrons generated from the interaction of gold nanoparticles (GNPs) with x-rays as a function of nanoparticle size and beam energy and thereby further the understanding of GNP-enhanced radiotherapy. Methods: The effective range, deflection angle, dose deposition, energy, and interaction processes of electrons produced from the interaction of x-rays with a GNP were calculated by Monte Carlo simulations. The GEANT4 code was used to simulate and track electrons generated from a 2, 50, and 100 nm diameter GNP when it is irradiated with a 50 kVp, 250 kVp, cobalt-60, and 6 MV photon beam in water. Results: When a GNP was present, depending on the beam energies used, secondary electron production was increased by 10- to 2000-fold compared to an absence of a GNP. Low-energy photon beams were much more efficient at interacting with the GNP by two to three orders of magnitude compared to MV energies and increased the deflection angle. GNPs with larger diameters also contributed more dose. The majority of the energy deposition was outside the GNP, rather than self-absorbed by the nanoparticle. The mean effective range of electron tracks for the beams tested rangedmore » from approximately 3 {mu}m to 1 mm. Conclusions: These simulated results yield important insights concerning the spatial distributions and elevated dose in GNP-enhanced radiotherapy. The authors conclude that the irradiation of GNP at lower photon energies will be more efficient for cell killing. This conclusion is consistent with published studies.« less

The phylogenetically-conserved vertebrate transcription factor, NFIB, is an orchestrator of glial differentiation in the developing mammalian central nervous system. We found NFIB expression to be reduced in glioblastoma (GBM), the commonest and most lethal primary adult brain cancer, so investigated what effect increased expression of NFIB had on GBM. Increased expression of NFIB in primary GBM cell lines induced expression of markers of glial differentiation, inhibited cell proliferation, reduced stem/progenitor cell growth, altered cell cycle progression and inhibited tumor growth in murine models of GBM. We thus identified NFIB to be a novel tumor suppressor gene in GBM.

Purpose: The impact of photon beam energy and tissue heterogeneities on dose distributions and dosimetric characteristics such as point dose, mean dose, and maximum dose was investigated in the context of small-animal irradiation using Monte Carlo simulations based on the EGSnrc code. Methods: Three Monte Carlo mouse phantoms, namely, heterogeneous, homogeneous, and bone homogeneous were generated based on the same mouse computed tomography image set. These phantoms were generated by overriding the tissue type of none of the voxels (heterogeneous), all voxels (homogeneous), and only the bone voxels (bone homogeneous) to that of soft tissue. Phase space files of the 100 and 225 kVp photon beams based on a small-animal irradiator (XRad225Cx, Precision X-Ray Inc., North Branford, CT) were generated using BEAMnrc. A 360 deg. photon arc was simulated and three-dimensional (3D) dose calculations were carried out using the DOSXYZnrc code through DOSCTP in the above three phantoms. For comparison, the 3D dose distributions, dose profiles, mean, maximum, and point doses at different locations such as the isocenter, lung, rib, and spine were determined in the three phantoms. Results: The dose gradient resulting from the 225 kVp arc was found to be steeper than for the 100 kVp arc. Themore » mean dose was found to be 1.29 and 1.14 times higher for the heterogeneous phantom when compared to the mean dose in the homogeneous phantom using the 100 and 225 kVp photon arcs, respectively. The bone doses (rib and spine) in the heterogeneous mouse phantom were about five (100 kVp) and three (225 kVp) times higher when compared to the homogeneous phantom. However, the lung dose did not vary significantly between the heterogeneous, homogeneous, and bone homogeneous phantom for the 225 kVp compared to the 100 kVp photon beams. Conclusions: A significant bone dose enhancement was found when the 100 and 225 kVp photon beams were used in small-animal irradiation. This dosimetric effect, due to the presence of the bone heterogeneity, was more significant than that due to the lung heterogeneity. Hence, for kV photon energies of the range used in small-animal irradiation, the increase of the mean and bone dose due to the photoelectric effect could be a dosimetric concern.« less

In this work, we report the growth of Copper Zinc Tin Sulfide (CZTS) nano-rods on CZTS thin films. The nano-structures were fabricated using an anodized aluminum oxide (AAO) growth mask. The metallic constituents of CZTS were co-electrodeposited within the AAO nano-pores using a choline-based ionic liquid as the electrolyte. Sulfurization was performed in elementary sulfur vapor environment at 450°C for 4 hours in nitrogen ambient. The properties of the CZTS thin film grown in the process were studied by X-ray diffraction (XRD) analysis. The results indicated that the film has a stannite structure with preferred grain orientation along (112). The nano-rods fabricated using this technique show that the diameters of the rods can be easily varied from 150–250 nm by changing the potential in the anodization process. The morphology and crystal structure of CZTS nano-rods were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).