An organic-based bright white light emitting compound, namely
Tb(H
3
PTC)
3
H
4
PTC = perylene-3,4,9,10-tetracarboxylic acid, able to be used as part of a white diode and as a part of a RGB system ...that can withstand high temperatures (∼700 K), is developed using perylene-3,4,9,10-tetracarboxylic dianhydride (
PTCDA
) and terbium(
iii
) nitrate pentahydrate as precursors by hydrothermal synthesis. Using
PTCDA
as the red emitter and the new derivative of it,
Tb(H
3
PTC)
3
, as the blue-green emitter, along with a common deep blue LED can form a RGB system for display technologies, around room temperature. Temperature-dependent photoluminescence properties of the
Tb(H
3
PTC)
3
compound are also investigated for the involved excitonic-emission processes and the respective recombination lifetimes. The terbium(
iii
) complex was prepared using a procedure that is reproducible, easily modifiable, inexpensive, and environmentally friendly, opening new pathways for its large-scale applications. Unlike
PTCDA
,
Tb(H
3
PTC)
3
has been shown to be soluble in
N
-methyl-2-pyrrolidone (NMP) as well as in dilute aqueous solutions of this organic solvent in a straightforward procedure. The light emission properties are intimately correlated with the molecular structure and electronic properties of
Tb(H
3
PTC)
3
elucidated by experimental results of X-ray Absorption Near Edge Spectroscopy (XANES), Extended X-ray Absorption Fine Structure (EXAFS) and Density Functional Theory (DFT) calculations. A bright fluorescence yield is attained with a small amount of material either in solution or in solid form showing its potential to be used in state-of-the-art organic optoelectronic devices.
Tb(H
3
PTC)
3
PTCDA
An organic-based bright white light emitting compound, namely
Tb(H
3
PTC)
3
, able to be used as part of a WOLED and as a part of a RGB system that can withstand high temperatures (∼700 K), is developed using
PTCDA
and Tb(NO
3
)
3
·5H
2
O as precursors by hydrothermal synthesis.
MoTe2 is an exfoliable transition metal dichalcogenide (TMD) that crystallizes in three symmetries: the semiconducting trigonal-prismatic 2H- or α-phase, the semimetallic and monoclinic 1T′- or ...β-phase, and the semimetallic orthorhombic γ-structure. The 2H-phase displays a band gap of ∼1 eV making it appealing for flexible and transparent optoelectronics. The γ-phase is predicted to possess unique topological properties that might lead to topologically protected nondissipative transport channels. Recently, it was argued that it is possible to locally induce phase-transformations in TMDs, through chemical doping, local heating, or electric-field to achieve ohmic contacts or to induce useful functionalities such as electronic phase-change memory elements. The combination of semiconducting and topological elements based upon the same compound might produce a new generation of high performance, low dissipation optoelectronic elements. Here, we show that it is possible to engineer the phases of MoTe2 through W substitution by unveiling the phase-diagram of the Mo1–x W x Te2 solid solution, which displays a semiconducting to semimetallic transition as a function of x. We find that a small critical W concentration x c ∼ 8% stabilizes the γ-phase at room temperature. This suggests that crystals with x close to x c might be particularly susceptible to phase transformations induced by an external perturbation, for example, an electric field. Photoemission spectroscopy, indicates that the γ-phase possesses a Fermi surface akin to that of WTe2.
Please cite this paper as: Mazzoni A, Althabe F, Liu N, Bonotti A, Gibbons L, Sánchez A, Belizán J. Women’s preference for caesarean section: a systematic review and meta‐analysis of observational ...studies. BJOG 2011;118:391–399.
Background The striking increase in caesarean section rates in middle‐ and high‐income countries has been partly attributed to maternal request. We conducted a systematic review and meta‐analysis of women’s preferences for caesarean section.
Objectives To review the published literature on women’s preferences for caesarean section.
Search strategy A systematic search of MEDLINE, EMBASE, LILACS and PsychINFO was performed. References of all included articles were examined.
Selection criteria We included studies that quantitatively evaluated women’s preferences for caesarean section in any country. We excluded articles assessing health providers’ preferences and qualitative studies.
Data collection and analysis Two reviewers independently screened s of all identified citations, selected potentially eligible studies, and assessed their full‐text versions. We conducted a meta‐analysis of proportions, and a meta‐regression analysis to determine variables significantly associated with caesarean section preference.
Main results Thirty‐eight studies were included (n = 19 403). The overall pooled preference for caesarean section was 15.6% (95% CI 12.5–18.9). Higher preference for caesarean section was reported in women with a previous caesarean section versus women without a previous caesarean section (29.4%; 95% CI 24.4–34.8 versus 10.1%; 95% CI 7.5–13.1), and those living in a middle‐income country versus a high‐income country (22.1%; 95% CI 17.6–26.9 versus 11.8%; 95% CI 8.9–15.1).
Authors’ conclusions Only a minority of women in a wide variety of countries expressed a preference for caesarean delivery. Further research is needed to better estimate the contribution of women’s demand to the rising caesarean section rates.
Background
Hematuria secondary to renal vein entrapment is mentioned only passing in textbooks and reviews.
Methods
We performed a search of the National Library of Medicine database for ...peer-reviewed publications using the terms “renal vein” or “nutcracker” and “hematuria”.
Results
We identified 187 published reports/studies that covered 736 patients, of whom 288 had microscopic hematuria and 448 had macroscopic hematuria. The patient cohort comprised 159 patients aged ≤17 years. Abdominal pain was absent in approximately 65 % of all patients, and a clinically relevant left-sided varicocele was observed in 29 % of the male patients. A normal pre-aortic left renal vein and an anomalous anatomy were noted in 680 and 56 patients, respectively. The body mass index (BMI) was lower in patients with renal vein entrapment than in the controls, with a regression of hematuria correlating with an increase in BMI. A surgical procedure was attempted in 34 % of the patients, of which the most common were endovascular stenting and transposition of the renal vein distally into the vena cava.
Conclusions
In cases of unexplained hematuria with or without abdominal pain, clinicians should consider the diagnosis of renal vein congestion, especially in males with varicocele. Ultrasonic Doppler flow scanning is the recommended initial diagnostic modality in these patients. Expectation management is advised in the great majority of cases.
The discovery of ferroelectricity in two-dimensional van der Waals materials has sparked enormous interest from the scientific community, due to its possible applications in next-generation ...nanoelectronic devices, such as random-access memory devices, digital signal processors, and solar cells, among others. In the present study, we used vapor phase deposition to synthesize ultrathin germanium sulfide nano-flakes on a highly oriented pyrolytic graphite substrate. Nanostructures of variable thicknesses were characterized using scanning tunneling microscopy and spectroscopy. Tunneling currents under forward and backward biases were measured as a function of nano-flake thickness. Remarkably, we clearly observed a hysteresis pattern, which we attributed to surface ferroelectric behavior, consistent with the screening conditions of polarization charges. The effect increases as the number of layers is reduced. This experimental result may be directly applicable to miniaturized memory devices, given the two-dimensional nature of this effect.
The role and function of dentin matrix metalloproteinases (MMPs) are not well-understood, but they may play a key role in dentinal caries and the degradation of resin-bonded dentin matrices. To test ...the null hypothesis that MMP-9 is not found in dentin matrix, we used gelatin zymography to extract and isolate all molecular forms of gelatinolytic MMPs in demineralized mature sound dentin powder obtained from extracted human molars, characterizing and identifying the enzymes by Western blotting. Gelatinolytic MMPs were detected in extracts of demineralized dentin matrix and identified as MMP-2 and MMP-9. Acidic extracts (pH 2.3) yielded 3–8 times more MMP activity than did EDTA (pH 7.4). Their activation may contribute to dentin matrix degradation, which occurs during caries progression and following resin bonding. Inhibition of MMP-2 and -9 proteolytic activity may slow caries progression and increase the durability of resin-dentin bonds.
FOCUS (Fast Monte CarlO approach to Coherence of Undulator Sources) is a new GPU‐based simulation code to compute the transverse coherence of undulator radiation from ultra‐relativistic electrons. ...The core structure of the code, which is written in the language C++ accelerated with CUDA, combines an analytical description of the emitted electric fields and massively parallel computations on GPUs. The combination is rigorously justified by a statistical description of synchrotron radiation based on a Fourier optics approach. FOCUS is validated by direct comparison with multi‐electron Synchrotron Radiation Workshop (SRW) simulations, evidencing a reduction in computation times by up to five orders of magnitude on a consumer laptop. FOCUS is then applied to systematically study the transverse coherence in typical third‐ and fourth‐generation facilities, highlighting peculiar features of undulator sources close to the diffraction limit. FOCUS is aimed at fast evaluation of the transverse coherence of undulator radiation as a function of the electron beam parameters, to support and help prepare more advanced and detailed numerical simulations with traditional codes like SRW.
FOCUS (Fast Monte CarlO approach to Coherence of Undulator Sources), a new GPU‐based code to compute the transverse coherence of X‐ray radiation from undulator sources as a function of the electron beam parameters, is described. FOCUS is validated with the Synchrotron Radiation Workshop (SRW) and SPECTRA codes. Examples of application to coherence studies in third‐ and fourth‐generation light sources are shown.
High-energy particle accelerators have been crucial in providing a deeper understanding of fundamental particles and the forces that govern their interactions. To increase the energy of the particles ...or to reduce the size of the accelerator, new acceleration schemes need to be developed. Plasma wakefield acceleration
, in which the electrons in a plasma are excited, leading to strong electric fields (so called 'wakefields'), is one such promising acceleration technique. Experiments have shown that an intense laser pulse
or electron bunch
traversing a plasma can drive electric fields of tens of gigavolts per metre and above-well beyond those achieved in conventional radio-frequency accelerators (about 0.1 gigavolt per metre). However, the low stored energy of laser pulses and electron bunches means that multiple acceleration stages are needed to reach very high particle energies
. The use of proton bunches is compelling because they have the potential to drive wakefields and to accelerate electrons to high energy in a single acceleration stage
. Long, thin proton bunches can be used because they undergo a process called self-modulation
, a particle-plasma interaction that splits the bunch longitudinally into a series of high-density microbunches, which then act resonantly to create large wakefields. The Advanced Wakefield (AWAKE) experiment at CERN
uses high-intensity proton bunches-in which each proton has an energy of 400 gigaelectronvolts, resulting in a total bunch energy of 19 kilojoules-to drive a wakefield in a ten-metre-long plasma. Electron bunches are then injected into this wakefield. Here we present measurements of electrons accelerated up to two gigaelectronvolts at the AWAKE experiment, in a demonstration of proton-driven plasma wakefield acceleration. Measurements were conducted under various plasma conditions and the acceleration was found to be consistent and reliable. The potential for this scheme to produce very high-energy electron bunches in a single accelerating stage
means that our results are an important step towards the development of future high-energy particle accelerators
.
Experimental results show that hosing of a long particle bunch in plasma can be induced by wakefields driven by a short, misaligned preceding bunch. Hosing develops in the plane of misalignment, ...self-modulation in the perpendicular plane, at frequencies close to the plasma electron frequency, and are reproducible. Development of hosing depends on misalignment direction, its growth on misalignment extent and on proton bunch charge. Results have the main characteristics of a theoretical model, are relevant to other plasma-based accelerators and represent the first characterization of hosing.
Summary
This study deals with the role of texture analysis as a predictive factor of radiation-induced insufficiency fractures in patients undergoing pelvic radiation.
Introduction
This study aims to ...assess the texture analysis (TA) of computed tomography (CT) simulation scans as a predictive factor of insufficiency fractures (IFs) in patients with pelvic malignancies undergoing radiation therapy (RT).
Methods
We performed an analysis of patients undergoing pelvic RT from January 2010 to December 2014, 24 of whom had developed pelvic bone IFs. We analyzed CT-simulation images using ImageJ macro software and selected two regions of interest (ROIs), which are L5 body and the femoral head. TA parameters included mean (
m
), standard deviation (SD), skewness (sk), kurtosis (
k
), entropy (
e
), and uniformity (
u
). The IFs patients were compared (1:2 ratio) with controlled patients who had not developed IFs and matched for sex, age, menopausal status, type of tumor, use of chemotherapy, and RT dose. A reliability test of intra- and inter-reader ROI TA reproducibility with the intra-class correlation coefficient (ICC) was performed. Univariate and multivariate analyses (logistic regression) were applied for TA parameters observed both in the IFs and the controlled groups.
Results
Inter- and intra-reader ROI TA was highly reproducible (ICC > 0.90). Significant TA parameters on paired
t
test included L5
m
(
p
= 0.001), SD (
p
= 0.002),
k
(
p
= 0.006),
e
(p = 0.004), and
u
(
p
= 0.015) and femoral head
m
(
p
< 0.001) and SD (
p
= 0.001), whereas on logistic regression analysis, L5
e
(
p
= 0.003) and
u
(
p
= 0.010) and femoral head
m
(
p
= 0.027), SD (
p
= 0.015), and sex (
p
= 0.044).
Conclusions
In our experience, bone CT TA could be correlated to the risk of radiation-induced IFs. Studies on a large patient series and methodological refinements are warranted.
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