bluuebunny/crossref_metadata_2025 huggingface dataset:
Does Sacral Nerve Stimulation Improve Continence Through Enhanced Sensitivity of the Anal Canal? A Pilot Study
Authors: Haas S. , Brock C. , Krogh K. , Gram M. , Lundby L. , Drewes A. M. , Laurberg S.
Published: October 2016

BACKGROUND:

It has been suggested that the effects of sacral nerve stimulation against fecal incontinence involve neuromodulation at spinal or supraspinal levels.

OBJECTIVE:

This study aims to investigate the afferent sensory pathways from the anorectum before and during sacral nerve stimulation.

DESIGN:

This is an explorative study.

PATIENTS:

Fifteen women with idiopathic fecal incontinence (mean age, 58 ± 12.2 years) were selected.

INTERVENTIONS:

Cortical evoked potentials were recorded during repeated rapid balloon distension of the rectum and the anal canal both before and during temporary sacral nerve stimulation. Stimuli applied were individualized according to the subjective urge to defecate.

MAIN OUTCOME MEASURES:

The main outcomes measured were 1) stimulus intensity, 2) latencies and amplitudes of cortical evoked potentials, and 3) spectral content in predefined frequency bands of cortical evoked potentials.

RESULTS:

The median Wexner fecal incontinence score improved from 15.5 ± 3.6 before to 6.7 ± 5 during sacral nerve stimulation (p < 0.001). Sacral nerve stimulation did not affect the threshold for urge to defecate during rectal distension (p = 0.64) but reduced the threshold from stimulation of the anal canal by 50% (p = 0.03). No statistically significant differences were found in latencies, amplitudes, or spectral analysis.

LIMITATIONS:

This is a pilot study of limited size.

CONCLUSIONS:

In patients with idiopathic fecal incontinence, sacral nerve stimulation reduced the threshold for urge to defecate elicited from the anal canal, whereas supraspinal responses remained unaltered. This may suggest that sacral nerve stimulation, at least in part, acts via somatic afferent fibers enhancing anal sensation.
The role of the gut microbiota in food allergy
Authors: Rachid Rima , Chatila Talal A.
Published: October 2016

Purpose of review

The rise in the prevalence of food allergy over the past decades has focused attention of factors that may impact disease development, most notably the gut microbiota. The gut microbial communities play a crucial role in promoting oral tolerance. Their alteration by such factors as Cesarean section delivery, diet and antibiotics may influence disease development. This review highlights recent progress in our understanding of the role of the gut microbiota in the development of food allergy.

Recent findings

Food allergy is associated with alterations in the gut microbiota or dysbiosis early in life that may be predictive of disease persistence versus tolerance acquisition. Evidence for the benefits of adjunct therapy with probiotics for the prevention of food allergies and for potentiating oral immunotherapy remains circumstantial, with further studies needed to validate its use. Studies in murine models of food allergy suggest that microbial therapy with protolerogenic bacteria such as certain Clostridial species holds promise in future applications for prevention or therapy of food allergy.

Progress in understanding the role of dysbiosis in food allergy and the factors that promote its development, such as antibiotic therapy, diet, modes of infant delivery, and environmental exposures, offer windows of opportunity for both preventive and therapeutic interventions to stem the rising tide of the food allergy epidemic.
Atlantoaxial Rotatory Subluxation
Authors: Kinon Merritt D. , Nasser Rani , Nakhla Jonathan , Desai Rupen , Moreno Jessica R. , Yassari Reza , Bagley Carlos A.
Published: October 2016

Pediatric emergency physicians must have a high clinical suspicion for atlantoaxial rotatory subluxation (AARS), particularly when a child presents with neck pain and an abnormal head posture without the ability to return to a neutral position. As shown in the neurosurgical literature, timely diagnosis and swift initiation of treatment have a greater chance of treatment success for the patient. However, timely treatment is complicated because torticollis can result from a variety of maladies, including: congenital abnormalities involving the C1-C2 joint or the surrounding supporting muscles and ligaments, central nervous system abnormalities, obstetric palsies from brachial plexus injuries, clavicle fractures, head and neck surgery, and infection. The treating pediatrician must discern the etiology of the underlying problem to determine both timing and treatment paradigms, which vary widely between these illnesses. We present a comprehensive review of AARS that is intended for pediatric emergency physicians. Management of AARS can vary widely bases on factors, such as duration of symptoms, as well as the patient's history. The goal of this review is to streamline the management paradigms and provide an inclusive review for pediatric emergency first responders.
Performance of Bedside Lung Ultrasound by a Pediatric Resident
Authors: Zhan Chen , Grundtvig Natalia , Klug Bent Helmuth
Published: October 2016

Objectives

Recent studies suggest that lung ultrasound is a good, radiation-free alternative to chest radiography in children with pneumonia. We investigated how bedside lung ultrasound performed by a pediatric resident compared with chest radiography in children with suspected pneumonia.

Methods

This was a prospective study comparing bedside lung ultrasound to chest radiography as the reference standard. Children aged 0 to 15 years with suspected pneumonia at a pediatric emergency department were included and underwent chest radiography and lung ultrasound. A pediatric resident with minimal practical ultrasound experience and with no access to supervision performed the bedside lung ultrasound and was blinded to the patients' medical evaluation.

Results

A total of 82 children underwent both chest radiography and lung ultrasound (57% boys; median [interquartile range] age, 1.5 [1.1–2.5] years). The lung ultrasound took 7 to 20 minutes to perform, and 10% were of suboptimal quality due to an uneasy child. The prevalence of consolidations by chest radiography was 50%. Lung ultrasound had a sensitivity of 40% (95% confidence interval [CI], 30%–51%), specificity of 91% (95% CI, 83%–96%), positive likelihood ratio of 4.71 (95% CI, 2.21–10.04), and negative likelihood ratio of 0.65 (95% CI, 0.54–0.79).

Conclusions

Bedside lung ultrasound is a useful tool, with a good specificity, to find lung consolidations in children even when the sonologist has minimal practical ultrasound experience and no access to supervision. We suggest the use of bedside lung ultrasound as a diagnostic tool in children with suspected pneumonia.
Seizures in Preterm Infants
Authors: Jacobs Julia , Spelbrink Emily M.
Published: October 2016

Infants born prematurely are highly vulnerable to brain injury and susceptible to seizures in the first weeks of life. Many neonatal seizures occur without reliable clinical signs and are detectable only on electroencephalogram (EEG); understanding EEG findings in these neonates is crucial for providing appropriate care. This can be challenging, as EEG background activity and patterns vary considerably with gestational age. Some physiologic preterm EEG patterns, such as rhythmic temporal theta activity or delta brushes, may be sharply contoured and appear similar to epileptic EEG patterns later in life. Moreover, ictal patterns in preterms are of lower voltage and frequency than in full-term neonates. This article reviews current data on incidence of seizures in preterms and their typical ictal EEG patterns. It also identifies the pitfalls of EEG analysis in a neonatal intensive care unit environment and gives examples of typically observed artifacts. It then discusses the impact of seizures on long-term outcome of preterms, independent of other variables such as gestational age and brain injury. Finally, it suggests future directions for research in preterm seizures.
A Randomized Prospective Comparison of Ultrasound-Guided and Landmark-Guided Steroid Injections for Carpal Tunnel Syndrome
Authors: Eslamian Fariba , Eftekharsadat Bina , Babaei-Ghazani Arash , Jahanjoo Fateme , Zeinali Mojgan
Published: October 2016

Purpose:

The aim of this study was to compare the clinical and electrodiagnostic efficacy of ultrasound (US)-guided versus landmark (LM)-guided steroid injections in patients with carpal tunnel syndrome (CTS).

Methods:

This randomized clinical trial included 47 patients (60 affected hands) with moderate CTS (30 hands in each group). All clinically suspected patients with CTS who met the inclusion criteria confirmed by electrodiagnostic tests were enrolled. The subjects received 40 mg of methylprednisolone either with the US-guide or the LM-guided injection technique. They were evaluated using the Boston Carpal Tunnel Questionnaire (symptom/function/total) and 6 electrodiagnostic findings at the baseline and 12 weeks after injection.

Results:

Symptom severity scores and functional status scores and electrodiagnostic parameters were significantly improved within each group at week 12 after treatment (P < 0.05), except for compound muscle action potential amplitude and motor nerve conduction velocity (P > 0.05). The improvement in symptom severity scores and functional status scores in the US-guided group was more than in the LM-guided group after 12 weeks, but there was no statistically significant difference (P = 0.79 and 0.64). The mean changes in electrodiagnostic parameters were also not different between groups except for the higher sensory nerve action potential amplitude in LM-guided group (P = 0.003).

Conclusions:

Both US-guided and LM-guided steroid injections were effective in reducing the symptoms, improving the function and electrodiagnostic findings of CTS. Although there was better symptomatic improvement with US-guided injections and better increase in sensory nerve action potential amplitude with LM-guided injection, a significant difference was not generally observed between US-guided and LM-guided CTS injections.
Orientation of tyrosine side chain in neurotoxic Aβ differs in two different secondary structures of the peptide
Authors: Das Swagata , Das Supriya , Roy Anupam , Pal Uttam , Maiti Nakul C.
Published: October 2016

Amyloid β (Aβ) peptide is present as a major component in amyloid plaque that is one of the hallmarks of Alzheimer's disease. The peptide contains a single tyrosine residue and Aβ has a major implication in the pathology of the disease progression. Current investigation revealed that the tyrosine side chain attained two different critical stereo orientations in two dissimilar conformational states of the peptide. The extended α-helical structure of the peptide observed in an apolar solvent or methanol/water mixture became disordered in aqueous medium and the radius of gyration decreased. In aqueous medium, the torsional angle around C
α
–C
β
of tyrosine group became −60°. However, in its α-helical conformation in an apolar system, the measured angle was 180° and this rotameric state may be reasoned behind stronger tyrosine fluorescence compared with the disordered state of the peptide. Molecular dynamics simulation analyses and spectroscopic studies have helped us to understand the major structural changes in the secondary structure of the peptide in the two conformational states. A conformational clustering indicated that the compact state is more stable with tyrosine residue attaining the torsion angle value of −60°, whereas the native state (in HFIP/water mixture) is prevalent at a torsion angle value of −180°. High solvent accessibility has possibly stabilized the particular rotameric state (−60°) of the tyrosine residue and could be the reason behind decrease in fluorescence of the sole tyrosine residue in an aqueous buffer solution (pH 7.4) compared with its fluorescence in the α-helical structure in the micellar environment.
Variable wing venation inAgathiphaga(Lepidoptera: Agathiphagidae) is key to understanding the evolution of basal moths
Authors: Schachat Sandra R. , Gibbs George W.
Published: October 2016

Details of the ancestral groundplan of wing venation in moths remain uncertain, despite approximately a century of study. Here, we describe a 3-branched subcostal vein, a 5-branched medial vein and a 2-branched cubitus posterior vein on the forewing ofAgathiphaga vitiensisDumbleton 1952 from Vanuatu. Such veins had not previously been described in any Lepidoptera. Because wing veins are typically lost during lepidopteran evolutionary history, rarely—if ever—to be regained, the venation ofA. vitiensisprobably represents the ancestral character state for moths. Wing venation is often used to identify fossil insects as moths, because wing scales are not always preserved; the presence of a supposedly trichopteran 3-branched subcostal vein in crown Lepidoptera may decrease the certainty with which certain amphiesmenopteran fossils from the Mesozoic can be classified. And because plesiomorphic veins can influence the development of lepidopteran wing patterns even if not expressed in the adult wing, the veins described here may determine the location of wing pattern elements in many lepidopteran taxa.
Sex roles, parental care and offspring growth in two contrasting coucal species
Authors: Goymann Wolfgang , Safari Ignas , Muck Christina , Schwabl Ingrid
Published: October 2016

The decision to provide parental care is often associated with trade-offs, because resources allocated to parental care typically cannot be invested in self-maintenance or mating. In most animals, females provide more parental care than males, but the reason for this pattern is still debated in evolutionary ecology. To better understand sex differences in parental care and its consequences, we need to study closely related species where the sexes differ in offspring care. We investigated parental care in relation to offspring growth in two closely related coucal species that fundamentally differ in sex roles and parental care, but live in the same food-rich habitat with a benign climate and have a similar breeding phenology. Incubation patterns differed and uniparental male black coucals fed their offspring two times more often than female and male white-browed coucals combined. Also, white-browed coucals had more ‘off-times’ than male black coucals, during which they perched and preened. However, these differences in parental care were not reflected in offspring growth, probably because white-browed coucals fed their nestlings a larger proportion of frogs than insects. A food-rich habitat with a benign climate may be a necessary, but—perhaps unsurprisingly—is not a sufficient factor for the evolution of uniparental care. In combination with previous results (Goymannet al. 2015J. Evol. Biol.28, 1335–1353 (doi:10.1111/jeb.12657)), these data suggest that white-browed coucals may cooperate in parental care, because they lack opportunities to become polygamous rather than because both parents were needed to successfully raise all offspring. Our case study supports recent theory suggesting that permissive environmental conditions in combination with a particular life history may induce sexual selection in females. A positive feedback loop among sexual selection, body size and adult sex-ratio may then stabilize reversed sex roles in competition and parental care.
A new Miocene baleen whale from the Peruvian desert
Authors: Marx Felix G. , Kohno Naoki
Published: October 2016

The Pisco-Ica and Sacaco basins of southern Peru are renowned for their abundance of exceptionally preserved fossil cetaceans, several of which retain traces of soft tissue and occasionally even stomach contents. Previous work has mostly focused on odontocetes, with baleen whales currently being restricted to just three described taxa. Here, we report a new Late Miocene rorqual (family Balaenopteridae),
Incakujira anillodefuego
gen. et sp. nov., based on two exceptionally preserved specimens from the Pisco Formation exposed at Aguada de Lomas, Sacaco Basin, southern Peru.
Incakujira
overall closely resembles modern balaenopterids, but stands out for its unusually gracile ascending process of the maxilla, as well as a markedly twisted postglenoid process of the squamosal. The latter likely impeded lateral (omega) rotation of the mandible, in stark contrast with the highly flexible craniomandibular joint of extant lunge-feeding rorquals. Overall,
Incakujira
expands the still meagre Miocene record of balaenopterids and reveals a previously underappreciated degree of complexity in the evolution of their iconic lunge-feeding strategy.
Kinetics of intercalation of fluorescent probes in magnesium–aluminium layered double hydroxide within a multiscale reaction–diffusion framework
Authors: Saliba Daniel , Al-Ghoul Mazen
Published: October 2016

We report the synthesis of magnesium–aluminium layered double hydroxide (LDH) using a reaction–diffusion framework (RDF) that exploits the multiscale coupling of molecular diffusion with chemical reactions, nucleation and growth of crystals. In an RDF, the hydroxide anions are allowed to diffuse into an organic gel matrix containing the salt mixture needed for the precipitation of the LDH. The chemical structure and composition of the synthesized magnesium–aluminium LDHs are determined using powder X-ray diffraction (PXRD), thermo-gravimetric analysis, differential scanning calorimetry, solid-state nuclear magnetic resonance (SSNMR), Fourier transform infrared and energy dispersive X-ray spectroscopy. This novel technique also allows the investigation of the mechanism of intercalation of some fluorescent probes, such as the neutral three-dimensional rhodamine B (RhB) and the negatively charged two-dimensional 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS), using
in situ
steady-state fluorescence spectroscopy. The incorporation of these organic dyes inside the interlayer region of the LDH is confirmed via fluorescence microscopy, solid-state lifetime, SSNMR and PXRD. The activation energies of intercalation of the corresponding molecules (RhB and HPTS) are computed and exhibit dependence on the geometry of the involved probe (two or three dimensions), the charge of the fluorescent molecule (anionic, cationic or neutral) and the cationic ratio of the corresponding LDH.

This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’.
Microscopic and continuum descriptions of Janus motor fluid flow fields
Authors: Reigh Shang Yik , Huang Mu-Jie , Schofield Jeremy , Kapral Raymond
Published: October 2016

Active media, whose constituents are able to move autonomously, display novel features that differ from those of equilibrium systems. In addition to naturally occurring active systems such as populations of swimming bacteria, active systems of synthetic self-propelled nanomotors have been developed. These synthetic systems are interesting because of their potential applications in a variety of fields. Janus particles, synthetic motors of spherical geometry with one hemisphere that catalyses the conversion of fuel to product and one non-catalytic hemisphere, can propel themselves in solution by self-diffusiophoresis. In this mechanism, the concentration gradient generated by the asymmetric catalytic activity leads to a force on the motor that induces fluid flows in the surrounding medium. These fluid flows are studied in detail through microscopic simulations of Janus motor motion and continuum theory. It is shown that continuum theory is able to capture many, but not all, features of the dynamics of the Janus motor and the velocity fields of the fluid.

This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’.
A perspective on bridging scales and design of models using low-dimensional manifolds and data-driven model inference
Authors: Tegnér Jesper , Zenil Hector , Kiani Narsis A. , Ball Gordon , Gomez-Cabrero David
Published: October 2016

Systems in nature capable of collective behaviour are nonlinear, operating across several scales. Yet our ability to account for their collective dynamics differs in physics, chemistry and biology. Here, we briefly review the similarities and differences between mathematical modelling of adaptive living systems versus physico-chemical systems. We find that physics-based chemistry modelling and computational neuroscience have a shared interest in developing techniques for model reductions aiming at the identification of a reduced subsystem or slow manifold, capturing the effective dynamics. By contrast, as relations and kinetics between biological molecules are less characterized, current quantitative analysis under the umbrella of bioinformatics focuses on signal extraction, correlation, regression and machine-learning analysis. We argue that model reduction analysis and the ensuing identification of manifolds bridges physics and biology. Furthermore, modelling living systems presents deep challenges as how to reconcile rich molecular data with inherent modelling uncertainties (formalism, variables selection and model parameters). We anticipate a new generative data-driven modelling paradigm constrained by identified governing principles extracted from low-dimensional manifold analysis. The rise of a new generation of models will ultimately connect biology to quantitative mechanistic descriptions, thereby setting the stage for investigating the character of the model language and principles driving living systems.

This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’.
Evaluating dispersion forces for optimization of van der Waals complexes using a non-empirical functional
Authors: Arabi Alya A.
Published: October 2016

Modelling dispersion interactions with traditional density functional theory (DFT) is a challenge that has been extensively addressed in the past decade. The exchange-dipole moment (XDM), among others, is a non-empirical add-on dispersion correction model in DFT. The functional PW86+PBE+XDM for exchange, correlation and dispersion, respectively, compromises an accurate functional for thermochemistry and for van der Waals (vdW) complexes at equilibrium and non-equilibrium geometries. To use this functional in optimizing vdW complexes, rather than computing single point energies, it is necessary to evaluate accurate forces. The purpose of this paper is to validate that, along the potential energy surface, the distance at which the energy is minimum is commensurate with the distance at which the forces vanish to zero. This test was validated for 10 rare gas diatomic molecules using various integration grids and different convergence criteria. It was found that the use of either convergence criterion, 10
−6
or 10
−8
, in Gaussian09, does not affect the accuracy of computed optimal distances and binding energies. An ultra-fine grid needs to be used when computing accurate energies using generalized gradient approximation functionals.

This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’.
Probing the mechanisms for the selectivity and promiscuity of methyl parathion hydrolase
Authors: Purg Miha , Pabis Anna , Baier Florian , Tokuriki Nobuhiko , Jackson Colin , Kamerlin Shina Caroline Lynn
Published: October 2016

Diverse organophosphate hydrolases have convergently evolved the ability to hydrolyse man-made organophosphates. Thus, these enzymes are attractive model systems for studying the factors shaping enzyme functional evolution. Methyl parathion hydrolase (MPH) is an enzyme from the metallo-β-lactamase superfamily, which hydrolyses a wide range of organophosphate, aryl ester and lactone substrates. In addition, MPH demonstrates metal-ion-dependent selectivity patterns. The origins of this remain unclear, but are linked to open questions about the more general role of metal ions in functional evolution and divergence within enzyme superfamilies. Here, we present detailed mechanistic studies of the paraoxonase and arylesterase activities of MPH complexed with five different transition metal ions, and demonstrate that the hydrolysis reactions proceed via similar pathways and transition states. However, while it is possible to discern a clear structural origin for the selectivity between different
substrates
, the selectivity between different
metal ions
appears to lie instead in the distinct electrostatic properties of the metal ions themselves, which causes subtle changes in transition state geometries and metal–metal distances at the transition state rather than significant structural changes in the active site. While subtle, these differences can be significant for shaping the metal-ion-dependent activity patterns observed for this enzyme.

This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’.
Chimaera simulation of complex states of flowing matter
Authors: Succi S.
Published: October 2016

We discuss a unified mesoscale framework (
chimaera
) for the simulation of complex states of flowing matter across scales of motion. The chimaera framework can deal with each of the three macro–meso–micro levels through suitable ‘mutations’ of the basic mesoscale formulation. The idea is illustrated through selected simulations of complex micro- and nanoscale flows.

This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’.
Thermodynamics of adaptive molecular resolution
Authors: Delgado-Buscalioni R.
Published: October 2016

A relatively general thermodynamic formalism for adaptive molecular resolution (AMR) is presented. The description is based on the approximation of local thermodynamic equilibrium and considers the alchemic parameter λ as the conjugate variable of the potential energy difference between the atomistic and coarse-grained model
Φ
=
U
(1)
−
U
(0)
. The thermodynamic formalism recovers the relations obtained from statistical mechanics of H-AdResS (Español
et al
.,
J. Chem. Phys.
142
, 064115, 2015 (
doi:10.1063/1.4907006
)) and provides relations between the free energy compensation and thermodynamic potentials. Inspired by this thermodynamic analogy, several generalizations of AMR are proposed, such as the exploration of new Maxwell relations and how to treat λ and
Φ
as ‘real’ thermodynamic
variables
.

This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’.
Lattice Boltzmann accelerated direct simulation Monte Carlo for dilute gas flow simulations
Authors: Di Staso G. , Clercx H. J. H. , Succi S. , Toschi F.
Published: October 2016

Hybrid particle–continuum computational frameworks permit the simulation of gas flows by locally adjusting the resolution to the degree of non-equilibrium displayed by the flow in different regions of space and time. In this work, we present a new scheme that couples the direct simulation Monte Carlo (DSMC) with the lattice Boltzmann (LB) method in the limit of isothermal flows. The former handles strong non-equilibrium effects, as they typically occur in the vicinity of solid boundaries, whereas the latter is in charge of the bulk flow, where non-equilibrium can be dealt with perturbatively, i.e. according to Navier–Stokes hydrodynamics. The proposed concurrent multiscale method is applied to the dilute gas Couette flow, showing major computational gains when compared with the full DSMC scenarios. In addition, it is shown that the coupling with LB in the bulk flow can speed up the DSMC treatment of the Knudsen layer with respect to the full DSMC case. In other words, LB acts as a DSMC accelerator.

This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’.
Reduced CREB3L2 expression is associated with resistance to sorafenib and poor prognosis in ER-positive breast cancer
Authors: Mullarkey Sean , Arabkari Vahid , Hossain Muhammad Mosaraf , Gupta Sanjeev , Gupta Ananya
Published: October 2016

Sorafenib is a multikinase inhibitor that acts by inhibiting tumour growth and disrupting tumour microvasculature through anti-proliferative, anti-angiogenic, and pro-apoptotic effects. However, development of resistance to sorafenib often prevents its long-term efficacy. No validated biomarkers currently exist for appropriately selecting patients with cancer for sorafenib treatment. In the present study, we report that CREB3L2 expression in human breast cancer cell lines is a marker of response to sorafenib. Analysis of human breast cancer cell lines using Oncomine database and Genomics of Drug Sensitivity in Cancer (GDSC) database revealed an association between reduced expression of CREB3L2 and sensitivity to sorafenib. Wet lab experiment in five human breast cancer cell lines confirmed the association between reduced expression of CREB3L2 and sensitivity to sorafenib. Further, reduced expression of CREB3L2 was associated with poor Reccurence Free Survival in Luminal breast cancer. Our results suggest that CREB3L2 expression is a biomarker of response to sorafenib and outcome in breast cancer.
Formation and structure of the first metal complexes comprising amidinoguanidinate ligands
Authors: Sroor Farid M. , Liebing Phil , Hrib Cristian G. , Gräsing Daniel , Hilfert Liane , Edelmann Frank T.
Published: October 2016

The first metal complexes comprising amidinoguanidinate ligands have been prepared and structurally characterized, namely bis[μ-N,N′,N′′,N′′′-tetraisopropyl-1-(1-butylamidinato)guanidinato-κ3
N
1,N
2:N
2]bis[(tetrahydrofuran)lithium], [Li2(C18H37N4)2(C4H8O)2], (2), and [bis(tetrahydrofuran)lithium]-di-μ-chlorido-{(N,N′-dicyclohexyl-1-butylamidinato-κ2
N
1,N
2)[N,N′,N′′,N′′′-tetracyclohexyl-1-(1-butylamidinato)guanidinato-κ2
N
1,N
2]holmate(III)}, [HoLiCl2(C4H8O)2(C17H31N2)(C30H53N4)], (3). The novel lithium amidinoguanidinate precursors Li[
n
BuC(=NR)(NR)C(NR)2] [1: R = Cy (cyclohexyl), 2: R =
i
Pr) were obtained by treatment of N,N′-diorganocarbodiimides, R—N=C=N—R (R =
i
Pr, Cy), with 0.5 equivalents of n-butyllithium under well-defined reaction conditions. An X-ray diffraction study of 2 revealed a ladder-type dimeric structure in the solid state. Reaction of anhydrous holmium(III) chloride with in situ-prepared 2 afforded the unexpected holmium `ate' complex [
n
BuC(=NCy)(NCy)C(NCy)2]Ho[
n
BuC(NCy)2](μ-Cl)2Li(THF)2 (3) in 71% yield. An X-ray crystal structure determination of 3 showed that this complex contains both an amidinate ligand and the new amidinoguanidinate ligand.
1-(Pyridin-4-yl)-3-(2,4,6-trichlorophenyl)benz[4,5]imidazo[1,2-d][1,2,4]triazin-4(3H)-one
Authors: Abu Thaher Bassam , Schollmeyer Dieter , Qeshta Basem , Wahedy Kanan M. , Almasri Ihab M. , Morjan Rami Y. , Deigner Hans-Peter
Published: October 2016

In the title compound, C20H10Cl3N5O, the 13-membered ring system makes dihedral angles of 78.64 (9)° with the trichlorophenyl ring and 62.60 (10)° with the pyridine ring. The crystal packing is dominated by π–π interactions between the 13-membered ring systems [centroid–centroid distance = 3.6655 (11)°].
Mesoscale imaging with cryo‐light and X‐rays: Larger than molecular machines, smaller than a cell
Authors: Ekman Axel A. , Chen Jian‐Hua , Guo Jessica , McDermott Gerry , Le Gros Mark A. , Larabell Carolyn A.
Published: October 2016

In the context of cell biology, the term mesoscale describes length scales ranging from that of an individual cell, down to the size of the molecular machines. In this spatial regime, small building blocks self‐organise to form large, functional structures. A comprehensive set of rules governing mesoscale self‐organisation has not been established, making the prediction of many cell behaviours difficult, if not impossible. Our knowledge of mesoscale biology comes from experimental data, in particular, imaging. Here, we explore the application of soft X‐ray tomography (SXT) to imaging the mesoscale, and describe the structural insights this technology can generate. We also discuss how SXT imaging is complemented by the addition of correlative fluorescence data measured from the same cell. This combination of two discrete imaging modalities produces a 3D view of the cell that blends high‐resolution structural information with precise molecular localisation data.
Effect of In-Hole Roughness on Film Cooling From a Shaped Hole
Authors: Schroeder Robert P. , Thole Karen A.
Published: October 2016

While much is known about how macrogeometry of shaped holes affects their ability to successfully cool gas turbine components, little is known about the influence of surface roughness on cooling hole interior walls. For this study, a baseline-shaped hole was tested with various configurations of in-hole roughness. Adiabatic effectiveness measurements at blowing ratios up to 3 showed that the in-hole roughness caused decreased adiabatic effectiveness relative to smooth holes. Decreases in area-averaged effectiveness grew more severe with larger roughness size and with higher blowing ratios for a given roughness. Decreases of more than 60% were measured at a blowing ratio of 3 for the largest roughness values. Thermal field and flowfield measurements showed that in-hole roughness caused increased velocity of core flow through the hole, which increased the jet penetration height and turbulence intensity resulting in an increased mixing between the coolant and the mainstream. Effectiveness reductions due to roughness were also observed when roughness was isolated to only the diffused outlet of holes, and when the mainstream was highly turbulent.
Solutions for Sustainable Machining
Authors: Uhlmann Eckart , Peukert Bernd , Thom Simon , Prasol Lukas , Fürstmann Paul , Sammler Fiona , Richarz Sebastian
Published: October 2016

The manufacturing industry contributes over 19% to the world's greenhouse gas emissions (U.S. Energy Information Administration, 2008, “Rep: Annual Energy Review 2008,” Report No. DOE/EIA-0384; Diaz et al., 2010, “Environmental Analysis of Milling Machine Tool Use in Various Manufacturing Environments,” 2010 IEEE International Symposium on Sustainable Systems and Technology.) and 31% of the total energy consumed annually in the U.S. (Herzog, T., 2005, “World Greenhouse Gas Emissions in 2005,” World Resources Institute, Washington, DC 2; Diaz et al., 2010, “Environmental Analysis of Milling Machine Tool Use in Various Manufacturing Environments,” 2010 IEEE International Symposium on Sustainable Systems and Technology.). There is therefore an increasing demand for sustainable solutions for the production technology industry. At the Technische Universitat (TU) Berlin, Germany, a collaborative research center (CRC) is focusing on new solutions for the sustainable machining of high performance alloys, with developments from machine tool frames to cutting tool technology being undertaken. An innovative machine tool concept with a modular frame, which allows a high level of flexibility, has been developed. Furthermore, add-on upgrading systems for older machine tools, which are particularly relevant for developing countries, have been developed. These systems allow the accuracy of outdated machine tools to be increased, thus making the machine tools comparable to modern systems. Finally the cutting process also requires solutions for dry machining, as the use of cooling lubricant is environmentally damaging and a significant cost contributor in machining processes. Two solutions are being developed at the TU Berlin: an internally cooled cutting tool and a heating concept for ceramic tools to allow dry machining of high temperature alloys, for example, for the aerospace industry.
Numerical Study on the Effects of Freestream Turbulence on Antivortex Film Cooling Design at High Blowing Ratio
Authors: Repko Timothy W. , Nix Andrew C. , Uysal Can , Heidmann James D.
Published: October 2016

An advanced, high-effectiveness film cooling design, the antivortex hole (AVH) has been investigated by several research groups and shown to mitigate or counter the vorticity generated by conventional holes and increase film effectiveness at high blowing ratios and low freestream turbulence levels. The effects of increased turbulence on an AVH geometry were previously investigated in a preliminary steady computational fluid dynamics (CFD) study by Hunley et al. on the film effectiveness and net heat flux reduction (NHFR) at high blowing ratio. The current paper presents the results of an extended numerical parametric study, which attempts to separate the effects of turbulence intensity and length scale on film cooling performance of the AVH concept at high blowing ratio (2.0) and density ratio (2.0). In this extended study, steady Reynolds-averaged Navier–Stokes (RANS) analysis was performed with turbulence intensities of 5, 10, and 20% and length scales based on cooling hole diameter of Λx/dm = 1, 3, and 6. Increasing turbulence intensity was shown to increase the centerline, span-averaged, and area-averaged adiabatic film cooling effectiveness and NHFR. Larger turbulent length scales in the steady RANS analysis were shown to have little to no effect on the centerline, span-averaged, and area-averaged adiabatic film cooling effectiveness and NHFR at lower turbulence levels, but moderate effect at the highest turbulence levels investigated. Heat transfer results were in good agreement with the findings from adiabatic cases from previous work. Unsteady RANS results also provided supplementary flow visualization for the AVH film cooling flow under varying turbulence levels.
Effect of Nanoparticles on the Fuel Properties and Spray Performance of Aviation Turbine Fuel
Authors: Kannaiyan Kumaran , Anoop Kanjirakat , Sadr Reza
Published: October 2016

The influence of nanoparticles' dispersion on the physical properties of aviation fuel and its spray performance has been investigated in this work. To this end, the conventional Jet A-1 aviation fuel and its mixtures with alumina nanoparticles (nanofuel) at different weight concentrations are investigated. The key fuel physical properties such as density, viscosity, and surface tension that are of importance to the fuel atomization process are measured for the base fuel and nanofuels. The macroscopic spray features like spray cone angle and sheet breakup length are determined using the shadowgraph technique. The microscopic spray characteristics such as droplet diameter, droplet velocity, and their distributions are also measured by employing phase Doppler anemometry (PDA) technique. The spray performance is measured at two nozzle injection pressures of 0.3 and 0.9 MPa. The results show that with the increase in nanoparticle concentrations in the base fuel, the fuel viscosity and density increase, whereas the surface tension decreases. On the spray performance, the liquid sheet breakup length decreases with increasing nanoparticle concentrations. Furthermore, the mean droplet diameters of nanofuel are found to be lower than those of the base fuel.
User-Guided Visual Analysis of Cyber-Physical Production Systems
Authors: Post Tobias , Ilsen Rebecca , Hamann Bernd , Hagen Hans , Aurich Jan C.
Published: October 2016

Modern cyber-physical production systems (CPPS) connect different elements like machine tools and workpieces. The constituent elements are often equipped with high-performance sensors as well as information and communication technology, enabling them to interact with each other. This leads to an increasing amount and complexity of data that requires better analysis tools to support system refinement and revision performed by an expert. This paper presents a user-guided visual analysis approach that can answer relevant questions concerning the behavior of cyber-physical systems. The approach generates visualizations of aggregated views that capture an entire production system as well as specific characteristics of individual data features. To show the applicability of the presented methodologies, an exemplary production system is simulated and analyzed.
A Novel Approach to Design Lesion-Specific Stents for Minimum Recoil
Authors: Farhan Khan Muhammad , Brackett David , Ashcroft Ian , Tuck Christopher , Wildman Ricky
Published: October 2016

Stent geometries are obtained by topology optimization for minimized compliance under different stenosis levels and plaque material types. Three levels of stenosis by cross-sectional area, i.e., 30%, 40%, and 50% and three different plaque material properties, i.e., calcified, cellular, and hypocellular, were studied. The raw optimization results were converted to clear design concepts and their performance was evaluated by implanting them in their respective stenosed artery types using finite element analysis. The results were compared with a generic stent in similar arteries, which showed that the new designs showed less recoil. This work provides a concept that stents could be tailored to specific lesions in order to minimize recoil and maintain a patent lumen in stenotic arteries.
Modeling of Underwater Laser Drilling of Alumina
Authors: Shen Hong , Feng Decai , Yao Zhenqiang
Published: October 2016

Laser drilling of alumina is a noncontact material processing method, which has great advantages over the traditional mechanical machining. However, the quality of laser drilling is still a challenge. In this study, a 2D transient model is developed to simulate the underwater laser drilling of alumina, considering the recoil pressure which is generated by adjusting the density of water. The distributions of the temperature, pressure, and velocity during the drilling process are examined. The numerical results show that the underwater-drilled hole with smaller taper is obtained compared with that in air, which is attributed to the recoil pressure, higher specific heat capacity, and heat transfer coefficient of water. The experimental results validate the phenomenon in numerical simulation.
Estimates of Running Ground Reaction Force Parameters from Motion Analysis
Authors: Pavei Gaspare , Seminati Elena , Storniolo Jorge L.L. , Peyré-Tartaruga Leonardo A.
Published: October 2016

We compared running mechanics parameters determined from ground reaction force (GRF) measurements with estimated forces obtained from double differentiation of kinematic (K) data from motion analysis in a broad spectrum of running speeds (1.94–5.56 m⋅s–1). Data were collected through a force-instrumented treadmill and compared at different sampling frequencies (900 and 300 Hz for GRF, 300 and 100 Hz for K). Vertical force peak, shape, and impulse were similar between K methods and GRF. Contact time, flight time, and vertical stiffness (kvert) obtained from K showed the same trend as GRF with differences < 5%, whereas leg stiffness (kleg) was not correctly computed by kinematics. The results revealed that the main vertical GRF parameters can be computed by the double differentiation of the body center of mass properly calculated by motion analysis. The present model provides an alternative accessible method for determining temporal and kinetic parameters of running without an instrumented treadmill.
Identification of Functions Affecting Predator-Prey Interactions between Myxococcus xanthus and Bacillus subtilis
Authors: Müller Susanne , Strack Sarah N. , Ryan Sarah E. , Shawgo Mary , Walling Abigail , Harris Susanna , Chambers Chris , Boddicker Jennifer , Kirby John R.
Published: October 2016

Soil bacteria engage each other in competitive and cooperative ways to determine their microenvironments. In this study, we report the identification of a large number of genes required for
Myxococcus xanthus
to engage
Bacillus subtilis
in a predator-prey relationship. We generated and tested over 6,000 individual transposon insertion mutants of
M. xanthus
and found many new factors required to promote efficient predation, including the specialized metabolite myxoprincomide, an ATP-binding cassette (ABC) transporter permease, and a clustered regularly interspaced short palindromic repeat (CRISPR) locus encoding bacterial immunity. We also identified genes known to be involved in predation, including those required for the production of exopolysaccharides and type IV pilus (T4P)-dependent motility, as well as chemosensory and two-component systems. Furthermore, deletion of these genes confirmed their role during predation. Overall,
M. xanthus
predation appears to be a multifactorial process, with multiple determinants enhancing predation capacity.

IMPORTANCE
Soil bacteria engage each other in complex environments and utilize multiple traits to ensure survival. Here, we report the identification of multiple traits that enable a common soil organism,
Myxococcus xanthus
, to prey upon and utilize nutrients from another common soil organism,
Bacillus subtilis
. We mutagenized the predator and carried out a screen to identify genes that were required to either enhance or diminish capacity to consume prey. We identified dozens of genes encoding factors that contribute to the overall repertoire for the predator to successfully engage its prey in the natural environment.
Comparing submarine and fluvial channel kinematics: Implications for stratigraphic architecture
Authors: Jobe Zane R. , Howes Nick C. , Auchter Neal C.
Published: October 2016

Submarine and fluvial channels exhibit qualitatively similar geomorphic patterns, yet produce very different stratigraphic records. We reconcile these seemingly contradictory observations by focusing on the channel belt scale and quantifying the time-integrated stratigraphic record of the belt as a function of the scale and trajectory of the geomorphic channel, applying the concept of stratigraphic mobility. By comparing 297 submarine and fluvial channel belts from a range of tectonic settings and time intervals, we identify channel kinematics (trajectory) rather than channel morphology (scale) as the primary control on stratigraphic architecture and show that seemingly similar channel forms (in terms of scaling) have the potential to produce markedly different stratigraphy. Submarine channel belt architecture is dominated by vertical accretion (aggradational channel fill deposits), in contrast to fluvial systems that are dominated by lateral accretion (point bar deposits). This difference is best described with the channel belt aspect ratio, which is 9 for submarine systems and 72 for fluvial systems. Differences in channel kinematics and thus stratigraphic architecture between the two environments appear to result from markedly different coupling between channel aggradation and overbank deposition. The methodology and results presented here are also applicable to interpreting channelized stratigraphy on other planets and moons.
Peak intervals of equatorial Pacific export production during the middle Miocene climate transition
Authors: Carter Samantha C. , Griffith Elizabeth M. , Penman Donald E.
Published: October 2016

The middle Miocene climate transition (MMCT) is characterized by an abrupt 1‰ increase in benthic foraminiferal oxygen isotopes at ca. 13.8 Ma, marking expansion of the Antarctic Ice Sheet and transition of Earth’s climate to a cooler, relatively stable glacial state. Also occurring during this period is a globally recognized positive carbon isotope excursion (16.9–13.5 Ma) in benthic and planktonic foraminifera with shorter carbon isotope maxima (CM) events, linking hypotheses for climate change at the time with the carbon cycle. In order to test whether export production in the eastern equatorial Pacific is related to the largest such event (CM6), coincident with Antarctic Ice Sheet expansion, a high-resolution (<5 k.y.) record of export production at Integrated Ocean Drilling Program Site U1337 spanning the MMCT (14.02–13.43 Ma) was produced using marine pelagic barite mass accumulation rates. Export production is elevated with an extended period of more than double present-day values. These variations are not orbitally paced and provide evidence for a reorganization of nutrients supplied to the eastern equatorial Pacific in the Miocene and intensification of upwelling. If such changes are representative of the entire region, then this mechanism could sequester enough carbon to have a significant effect on atmospheric pCO2. However, continual delivery of nutrients to the surface waters of the eastern equatorial Pacific is required in order to sustain export production without depleting the surface ocean of limiting nutrients. This might be accomplished by a change in ocean circulation or a combination of other processes requiring further study.