bluuebunny/crossref_metadata_2025 huggingface dataset:
Isotropic morphometry and multicomponent T1ρ mapping of human knee articular cartilage in vivo at 3T
Authors: Baboli Rahman , Sharafi Azadeh , Chang Gregory , Regatte Ravinder R.
Published: May 2018

Background

The progressive loss of hyaline articular cartilage due to osteoarthritis (OA) changes the functional and biochemical properties of cartilage. Measuring the T1ρ along with the morphological assessment can potentially be used as noninvasive biomarkers in detecting early‐stage OA. To correlate the biochemical and morphological data, submillimeter isotropic resolution for both studies is required.

Purpose

To implement a high spatial resolution 3D‐isotropic‐MRI sequence for simultaneous assessment of morphological and biexponential T1ρ relaxometry of human knee cartilage in vivo.

Study Type

Prospective.

Population

Ten healthy volunteers with no known inflammation, trauma, or pain in the knee.

Field Strength/Sequence

Standard FLASH sequence and customized Turbo‐FLASH sequence to acquire 3D‐isotropic‐T1ρ‐weighted images on a 3T MRI scanner.

Assessment

The mean volume and thickness along with mono‐ and biexponential T1ρ relaxations were assessed in the articular cartilage of 10 healthy volunteers.

Statistical Tests

Nonparametric rank‐sum tests. Bland–Altman analysis and coefficient of variation.

Results

The mean monoexponential T1ρ relaxation was 40.7 ± 4.8 msec, while the long and short components were 58.2 ± 3.9 msec and 6.5 ± 0.6 msec, respectively. The mean fractions of long and short T1ρ relaxation components were 63.7 ± 5.9% and 36.3 ± 5.9%, respectively. Statistically significant (P ≤ 0.03) differences were observed in the monoexponential and long components between some of the regions of interest (ROIs). No gender differences between biexponential components were observed (P > 0.05). Mean cartilage volume and thickness were 25.9 ± 6.4 cm3 and 2.2 ± 0.7 mm, respectively. Cartilage volume (P = 0.01) and thickness (P = 0.03) were significantly higher in male than female participants across all ROIs. Bland–Altman analysis showed agreement between two morphological methods with limits of agreement between –1000 mm3 and +1100 mm3 for volume, and −0.78 mm and +0.46 mm for thickness, respectively.

Data Conclusion

Simultaneous assessment of morphological and multicomponent T1ρ relaxation of knee joint with 0.7 × 0.7 × 0.7 mm isotropic spatial resolution is demonstrated in vivo. Comparison with a standard method showed that the proposed technique is suitable for assessing the volume and thickness of articular cartilage.

Level of Evidence: 2

Technical Efficacy: Stage 1

J. Magn. Reson. Imaging 2018;48:1707–1716
Improvement of liver stiffness measurement, acoustic radiation force impulse measurements, and noninvasive fibrosis markers after direct‐acting antivirals for hepatitis C virus G4 recurrence post living donor liver transplantation: Egyptian cohort
Authors: Alem Shereen Abdel , Said Mohamed , Anwar Ismail , Abdellatif Zeinab , Elbaz Tamer , Eletreby Rasha , AbouElKhair Mahmoud , El‐Serafy Magdy , Mogawer Sherif , El‐Amir Mona , El‐Shazly Mostafa , Hosny Adel , Yosry Ayman
Published: May 2018

Progression of recurrent hepatitis C is accelerated in liver transplant (LT) recipients. Direct‐acting antivirals (DAAs) have recently emerged as a promising therapeutic regimen for the treatment of hepatitis C virus infection. Rates of sustained virological response (SVR) have drastically improved since the introduction of DAAs. The aim is to elucidate the changes in liver stiffness measurement (LSM) by transient elastography (TE) as well as acoustic radiation force impulse (ARFI) elastography and fibrosis scores after DAA treatment in LT recipients with hepatitis C virus recurrence. A single‐center, prospective study including 58 LT recipients with hepatitis C recurrence who received different sofosbuvir‐based treatment regimens. Transient elastography and ARFI elastography values were recorded as well as fibrosis 4 score (FIB‐4) and aspartate aminotransferase‐to‐platelet ratio index were calculated at baseline and SVR at week 24 (SVR24). The outcome was improvement in LSM and at least a 20% decrease in LSM at SVR24 compared with baseline. The sustained virological response was 98.1%. There was improvement of platelet counts, alanine aminotransferase, and aspartate aminotransferase, which in turn caused improvement in fibrosis scores at SVR24. LSM by TE and ARFI elastography decreased from the baseline median value of 6.3 kPa (interquartile range [IQR]; 4.6 to 8.8 kPa) and 1.28 m/s (IQR; 1.07 to 1.53 m/s) to an SVR24 median value of 6.2 kPa (IQR; 4.85 to 8.9 kPa) and 1.12 (IQR; 0.97 to 1.30 m/s), respectively. Logistic regression analysis showed that baseline viral load was the only significant predictor of improvement in LS after DAA therapy at SVR24. Sofosbuvir‐based treatment resulted in an early improvement in parameters of liver fibrosis in post‐LT patients with hepatitis C recurrence.
Design of Freeform Illumination Optics
Authors: Wu Rengmao , Feng Zexin , Zheng Zhenrong , Liang Rongguang , Benítez Pablo , Miñano Juan C. , Duerr Fabian
Published: May 2018

Freeform optics constitutes a new technology that is currently driving substantial changes in illumination design. It liberates designers and engineers from restrictions of optical surface geometry, enabling them to achieve compact, lightweight, and efficient illumination systems with excellent optical performance. Freeform optics is currently used widely for both fundamental research and practical applications. This Review focuses on the design of freeform illumination optics, which is a key factor in advancing the development of illumination engineering. The design methods of freeform illumination optics can be divided into two groups: zero‐étendue algorithms based on ideal source assumption and design algorithms for extended light sources. The zero‐étendue algorithms include ray mapping method, Monge–Ampère equation method, and supporting quadric method. The algorithms for extended sources include illumination optimization, feedback design, and simultaneous multiple surfaces method. The characteristics and limitations of these design methods are illustrated and a summary of these methods with future outlooks is also given.
Graphene‐Oxide‐Decorated Microporous Polyetheretherketone with Superior Antibacterial Capability and In Vitro Osteogenesis for Orthopedic Implant
Authors: Ouyang Ling , Deng Yi , Yang Lei , Shi Xiuyuan , Dong Taosheng , Tai Youyi , Yang Weizhong , Chen Zhi‐Gang
Published: May 2018

Due to its similar elastic modulus of human bones, polyetheretherketone (PEEK) has been considered as an excellent cytocompatible material. However, the bioinertness, poor osteoconduction, and weak antibacterial activity of PEEK limit its wide applications in clinics. In this study, a facile strategy is developed to prepare graphene oxide (GO) modified sulfonated polyetheretherketone (SPEEK) (GO‐SPEEK) through a simple dip‐coating method. After detailed characterization, it is found that the GO closely deposits on the surface of PEEK, which is attributed to the π–π stacking interaction between PEEK and GO. Antibacterial tests reveal that the GO‐SPEEK exhibits excellent suppression toward Escherichia coli. In vitro cell attachment, growth, differentiation, alkaline phosphatase activity, quantitative real‐time polymerase chain reaction analyses, and calcium mineral deposition all illustrate that the GO‐SPEEK substrate can significantly accelerate the proliferation and osteogenic differentiation of osteoblast‐like MG‐63 cells compared with those on PEEK and SPEEK groups. These results suggest that the GO‐SPEEK has an improved antibacterial activity and cytocompatibility in vitro, showing that the developed GO‐SPEEK has a great potential as the bioactive implant material in bone tissue engineering.
Steepest‐descent proximal point algorithms for a class of variational inequalities in Banach spaces
Authors: Buong Nguyen
Published: May 2018

In this paper, we present a new approach to the problem of finding a common zero for a system of m‐accretive mappings in a uniformly convex Banach space with a uniformly Gâteaux differentiable norm. We propose an implicit iteration method and two explicit ones, based on compositions of resolvents with the steepest‐descent method. We show that our results contain some iterative methods in literature as special cases. An extension of the Xu's regularization method for the proximal point algorithm from Hilbert spaces onto Banach ones under simple conditions of convergence and a new variant for the method of alternating resolvents are obtained. Numerical experiments are given to affirm efficiency of the methods.
Self‐Assembly of Diblock Molecular Polymer Brushes in the Spherical Confinement of Nanoemulsion Droplets
Authors: Steinhaus Andrea , Pelras Théophile , Chakroun Ramzi , Gröschel André H. , Müllner Markus
Published: May 2018

Understanding the self‐assembly behavior of polymers of various topologies is key to a reliable design of functional polymer materials. Self‐assembly under confinement conditions emerges as a versatile avenue to design polymer particles with complex internal morphologies while simultaneously facilitating scale‐up. However, only linear block copolymers have been studied to date, despite the increasing control over macromolecule composition and architecture available. This study extends the investigation of polymer self‐assembly in confinement from regular diblock copolymers to diblock molecular polymer brushes (MPBs). Block‐type MPBs with polystyrene (PS) and polylactide (PLA) compartments of different sizes are incorporated into surfactant‐stabilized oil‐in‐water (chloroform/water) emulsions. The increasing confinement in the nanoemulsion droplets during solvent evaporation directs the MPBs to form solid nano/microparticles. Microscopy studies reveal an intricate internal particle structure, including interpenetrating networks and axially stacked lamellae of PS and PLA, depending on the PS/PLA ratio of the brushes.
Genetic Dystonia‐ataxia Syndromes: Clinical Spectrum, Diagnostic Approach, and Treatment Options
Authors: Rossi Malco , Balint Bettina , Millar Vernetti Patricio , Bhatia Kailash P. , Merello Marcelo
Published: May 2018

Background

Dystonia and ataxia are manifestations of numerous disorders, and indeed, an ever‐expanding spectrum of genes causing diseases that encompass dystonia and ataxia are discovered with the advances of genetic techniques. In recent years, a pathophysiological link between both clinical features and the role of the cerebellum in the genesis of dystonia, in some cases, has been proposed. In clinical practice, the genetic diagnosis of dystonia‐ataxia syndromes is a major issue for genetic counseling, prognosis and, occasionally, specific treatment.

Methods

For this pragmatic and educational review, we conducted a comprehensive and structured literature search in Pubmed, OMIM, and GeneReviews using the key words “dystonia” and “ataxia” to identify those genetic diseases that may combine dystonia with ataxia.

Results

There are a plethora of genetic diseases causing dystonia and ataxia. We propose a series of clinico‐radiological algorithms to guide their differential diagnosis depending on the age of onset, additional neurological or systemic features, and imaging findings. We suggest a sequential diagnostic approach to dystonia‐ataxia syndromes. We briefly highlight the pathophysiological links between dystonia and ataxia and conclude with a review of specific treatment implications.

Conclusions

The clinical approach presented in this review is intended to improve the diagnostic success of clinicians when faced with patients with dystonia‐ataxia syndromes.
Clinical Rating Scales for Urinary Symptoms in Parkinson Disease: Critique and Recommendations
Authors: Pavy‐Le Traon Anne , Cotterill Nikki , Amarenco Gerard , Duerr Susanne , Kaufmann Horacio , Lahrmann Heinz , Tison François , Wenning Gregor K. , Goetz Christopher G. , Poewe Werner , Sampaio Cristina , Schrag Anette , Rascol Olivier , Martinez‐Martin Pablo , Stebbins Glenn T. ,   the Members of the MDS Committee on Rating Scales Development
Published: May 2018

Background

The prevalence of lower urinary tract symptoms (LUTS) is high in Parkinson's disease (PD). These problems negatively affect quality of life and include both storage and voiding problems. The International Parkinson and Movement Disorder Society established a task force to review clinical rating scales/questionnaires for the assessment of urinary symptoms in PD.

Methods

According to prespecified criteria, these scales/questionnaires were classified as “Recommended” or “Recommended with caveats” when clinimetric properties were satisfactory for Recommended status but had not been assessed specifically in PD, “Suggested” or “Listed.” These assessments were applied to rate scales as screening tools for the diagnosis of LUTS and for the rating of symptom severity.

Results

Among scales that included LUTS but focused on overall autonomic or non‐motor symptoms in PD, no scale reached the clinimetric rigor to be designated as Recommended or Recommended with caveats, but some were Suggested for either diagnostic screening tools or severity measures. Among primary urological scales, most are well validated in urological setting, but none was validated specifically in PD. DAN‐PSS (Danish PSS), ICIQ (International Consultation for Incontinence Questionnaire)‐MLUTS (Male Lower Urinary Tract Symptoms), OABq, OABq‐SF (ICIQ‐OABqol), OAB‐V8 (as screening tool), and OABSS (OAB Symptom Score) met criteria for Recommended with caveats.

Conclusion

The Task Force does not recommend the development of a new scale. However, all above‐mentioned questionnaires need to be studied further and specifically validated in PD.
The facial artery perforator flap for intraoral reconstruction of a mouth floor defect
Authors: Horta Ricardo , Teixeira Sergio , Nascimento Ricardo , Silva Alvaro , Amarante Jose
Published: May 2018

Facial artery perforator flaps have been recently reported by different authors for perioral, nasal alar and cheek defects, but not for intraoral reconstruction. We have extended the use of the facial artery perforator flap in a 56‐year‐old man with a squamous cell carcinoma of left mouth floor, who was submitted to tumor resection with marginal mandibulectomy and left supraomohyoid neck dissection. The flap was designed according to the size of the defect (5 × 3 cm), centered on the perforator to create a symmetric flap and was tunnelled intraorally by means of a 90° rotation. The postoperative period was uneventful, allowing timely initiation of adjuvant radiotherapy. After 8 months, there were no signs of local recurrence or wound dehiscence, and functional outcomes were satisfactory. The main advantages of this flap in this case were the reduction in morbidity at the donor site with preservation of nerves, muscles and facial artery, and it allowed greater freedom. To the best of the authors' knowledge, this technique has not been reported before. It may constitute an important reconstructive option when dealing with similar defects, if our results are confirmed in larger series.
Asynchronous CDX2 expression and polarization of porcine trophoblast cells reflects a species‐specific trophoderm lineage determination progress model
Authors: Liu Shichao , Bou Gerelchimeg , Zhao Jianchao , Guo Shimeng , Guo Jia , Weng Xiaogang , Yin Zhi , Liu Zhonghua
Published: May 2018

Upregulation of Cdx2 expression in outer cells is a key event responsible for cell lineage segregation between the inner cell mass and the trophoderm (TE) in mouse morula‐stage embryos. In TE cells, polarization can regulate Hippo and Rho‐associated kinase (Rho‐ROCK) signaling to induce the nuclear location of YAP, which has been demonstrated to further induce the expression of Cdx2. However, we found that CDX2 expression could not be detected in the outer cells of porcine morula‐stage embryos but only in some TE cells at the early blastocyst stage. The biological significance and the regulation mechanism of this species‐specific CDX2 expression pattern have still not been determined. We show here that an asynchronous CDX2 expression pattern exists in porcine TE cells during the development of the blastocyst. We demonstrate that CDX2 expression in porcine TE cells depends on the nuclear localization of YAP and polarization of the embryo through Y27632 treatment. We found that the polarization process in the morula to the late blastocyst stage porcine embryos was asynchronous, which was revealed by the apical localization of phosphorylated EZRIN staining. Artificially enhancing the number of polarized blastomeres by culturing the separated blastomeres of four‐cell stage porcine embryos resulted in increased CDX2‐positive cell numbers. These results indicate that the mechanism of CDX2 expression regulation is conserved, but the polarization progress is not conserved between the pig and the mouse, and results in a species‐specific trophoblast determination progress model.
Regularien: Reach und andere Gemeinheiten
Authors: Cleuvers Michael
Published: May 2018

Ende Mai endet wieder eine Registrierungsdeadline zur europäischen Chemikaliengesetzgebung. Hersteller, Importeure und Exporteure haben zudem weltweit weitere Regulierungen zu beachten.
Portrait Roald Hoffmann: "Gute Gedichte schreiben und gute Wissenschaft machen"
Authors: Remenyi Christian
Published: May 2018

Es war der bewegendste Moment des GDCh‐Wissenschaftsforums in Berlin. Minutenlang applaudierte das Publikum bei der Eröffnungsveranstaltung Roald Hoffmann, der soeben den neu gestifteten Primo‐Levi‐Preis erhalten hatte. Die Nachrichten aus der Chemie fragten ihn, was ihn mit Primo Levi verbindet und warum er seine Studenten in der Grundvorlesung Levis Buch „Das Periodische System“ lesen ließ.
Bilanz 2017: Covestro
Authors: Bulmahn Maren
Published: May 2018

Covestro hat im zweiten Jahr seiner Selbstständigkeit den Umsatz prozentual zweistellig erhöht. Dazu trugen Polyurethane mehr als die Hälfte bei.
Bilanz 2017: Österreich
Authors: Pummer Johann
Published: May 2018

Nach vier Jahren der Stagnation ist die Stimmung in der österreichischen Chemiebranche nun wieder besser.
Pro Elektroauto: Der Aufstieg des Elektroautos hat begonnen
Authors: Winter Martin
Published: May 2018

Der Systemwechsel zu mehr Elektromobilität ist sinnvoll. Denn nur mit fossilen Kraftstoffen ist es nicht möglich, die Klimaschutzziele zu erreichen und die Energieversorgung zu sichern, meint Martin Winter.
Unternehmensführung: digital und agil
Authors: Hundertmark Stephan
Published: May 2018

Mittelständische Unternehmen in der Spezial‐ und Feinchemie sind oft erfolgreich. Zum Erfolgsrezept gehört mehr als eine bestimmte Unternehmensgröße.
Der Kohlenstoffgehalt im Reinstwasser
Authors: Hupach Sascha , Bayerl Arno
Published: May 2018

Viele Industriezweige benötigen Reinstwasser, etwa die Pharmaproduktion oder die Chipherstellung. Um zu prüfen, ob das Wasser konstant die gewünschte Qualität aufweist, sind regelmäßige Kontrollen auf den Gehalt an organischem Kohlenstoff erforderlich.
Development of completely bio‐based epoxy networks derived from epoxidized linseed and castor oil cured with citric acid
Authors: Sahoo Sushanta K. , Khandelwal Vinay , Manik Gaurav
Published: May 2018

Bio‐based epoxy resins were synthesized from nonedible resources like linseed oil and castor oil. Both the oils were epoxidized through in situ method and characterized via Fourier transform infrared and 1H‐NMR. These epoxidized oils were crosslinked with citric acid without using any catalyst and their properties compared with diglycidyl ether of bisphenol A‐epoxy. The tensile strength and modulus of epoxidized linseed oil (ELO) were found to be more than those of epoxidized castor oil (ECO)‐based network. However, elongation at break of ECO was significantly higher than that of both ELO and epoxy, which reveals its improved flexibility and toughened nature. Thermogravimetric analysis revealed that the thermal degradation of ELO‐based network is similar to that of petro‐based epoxy. Dynamic mechanical analysis revealed moderate storage modulus and broader loss tangent curve of bio‐based epoxies confirming superior damping properties. Bioepoxies exhibit nearly similar contact angle as epoxy and display good chemical resistant. The preparation method does not involve the use of any toxic catalyst and more hazardous solvents, thus being eco‐friendly.
Thermal behaviors and characteristics of polylactide/poly(butylene succinate) blend films via reactive compatibilization and plasticization
Authors: Phetwarotai Worasak , Maneechot Hnungruthai , Kalkornsurapranee Ekwipoo , Phusunti Neeranuch
Published: May 2018

Polylactide (PLA)/poly(butylene succinate) (PBS) blend films modified with a compatibilizer and a plasticizer were hot‐melted through a twin screw extruder and prepared by hydraulic press. Toluene diisocyanate (TDI) and polylactide‐grafted‐maleic anhydride (PLA‐g‐MA) were used as compatibilizers, while triethyl citrate and tricresyl phosphate acted as plasticizers. The effects of the type and content of compatibilizer and plasticizer on the mechanical characteristics, thermal properties, crystallization behavior, and phase morphology of the PLA/PBS blend films were investigated. Reactive compatibilization at increasing levels of TDI improved the compatibility of the PLA and PBS, affecting the toughness of the films. As evidenced by scanning electron microscope, the addition of TDI enhanced the interfacial adhesion of the blends, leading to the appearance of many elongated fibrils at the fracture surface. Furthermore, PLA/PBS blending with both TDI and PLA‐g‐MA led to an acceleration of the cold crystallization rate and an increment of the degree of crystallinity (). Toluene diisocyanate could be a more effective compatibilizer than PLA‐g‐MA for PLA/PBS blend films. The synergistic combination of compatibilizer and plasticizer brought a significant improvement in elongation at break and tensile‐impact toughness of the PLA/PBS blends, compared with neat PLA. Their failure mode changed from brittle to ductile due to the improved compatibility and molecular segment mobility of the PLA and PBS phases. Differential scanning calorimeter results revealed that the plasticizers triethyl citrate and tricresyl phosphate changed the thermal behavior ofTccandTm, affectingα′ andαcrystal formations. However, these plasticizers only slightly improved the thermal stability of the films.
Structure‐property relationship, rheological behavior, and thermal degradability of poly(lactic acid)/fulvic acid amide composites
Authors: Liu Panyu , Zhen Weijun
Published: May 2018

Fulvic acid amide (FAA) was synthesized with fulvic acid (FA) and urea. The structure of FAA was characterized by X‐ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Poly(lactic acid)/fulvic acid amide (PLA/FAA) composites were prepared by melt blending and compression molding. The nucleation effect of FAA on PLA was investigated by differential scanning calorimetry and polarized optical microscopy. Structure‐property relationship of PLA/FAA composites showed that FAA accelerated crystallization rate of PLA and improved toughness of PLA. Rotational rheological behavior of PLA/FAA composites showed that FAA increased the storage modulus of PLA. Capillary rheological analysis showed that the apparent viscosities of PLA composites were highly increased after the introduction of the FAA nucleating agent. Moreover, thermogravimetric analysis demonstrated that thermal degradability of PLA/FAA composites has been increased significantly compared with the neat PLA.
A phase 1 study of eribulin mesylate (E7389), a novel microtubule‐targeting chemotherapeutic agent, in children with refractory or recurrent solid tumors: A Children's Oncology Group Phase 1 Consortium study (ADVL1314)
Authors: Schafer Eric S. , Rau Rachel E. , Berg Stacey , Liu Xiaowei , Minard Charles G. , D'Adamo David , Scott Rachael , Reyderman Larisa , Martinez Gresel , Devarajan Sandhya , Reid Joel M. , Fox Elizabeth , Weigel Brenda J. , Blaney Susan M.
Published: May 2018

Background

Eribulin mesylate is a novel anticancer agent that inhibits microtubule growth, without effects on shortening, and promotes nonproductive tubulin aggregate formation. We performed a phase 1 trial to determine the dose‐limiting toxicities (DLTs), maximum tolerated or recommended phase 2 dose (MTD/RP2D), and pharmacokinetics (PK) of eribulin in children with refractory or recurrent solid (excluding central nervous system) tumors.

Methods

Eribulin was administered intravenously on days 1 and 8 in 21‐day cycles. Three dose levels (1.1, 1.4, and 1.8 mg/m2/dose) were evaluated using the rolling six design with additional patients enrolled into a PK expansion cohort at the MTD. PK samples were obtained following the day 1, cycle 1 dose.

Results

Twenty‐three patients, ages 3–17 (median 14) years were enrolled; 20 were evaluable for toxicity. DLTs occurred in 0/6 and 1/6 subjects at the 1.1 and 1.4 mg/m2/dose, respectively. One subject at the 1.4 mg/m2/dose had grade 4 neutropenia and grade 3 fatigue. At the 1.8 mg/m2/dose, 2/5 subjects experienced dose‐limiting (grade 4) neutropenia. Grade 3/4 non‐DLTs included lymphopenia and hypokalemia, while low‐grade toxicities included anorexia and nausea. No episodes of grade > 2 corrected QT interval prolongation or peripheral neuropathy were reported. Eribulin pharmacokinetic parameters were highly variable; the median elimination half‐life was 39.6 (range 24.2–96.4) hr. A partial response was observed in one patient (Ewing sarcoma).

Conclusions

Eribulin was well tolerated in children with refractory or recurrent solid tumors with neutropenia identified as the primary DLT. The RP2D of eribulin is 1.4 mg/m2/dose on days 1 and 8 of a 21‐day cycle.
Nanoindentation study on mechanical properties and curing depth of dental resin nanocomposites
Authors: Zha Chao , Hu Jianhua , Li Ainong , Huang Shangyu , Liu Hanxing , Chen Gang , Zhang Zuoqi , Li Bei , Wang Zhengzhi
Published: May 2018

Mechanical properties and curing depth of bisphenol‐α‐glycidyl methacrylate/triethylene glycol dimethacrylate‐based dental composites were systematically investigated by site‐specific nanoindentation tests. Effects of filler (20‐nm silica nanoparticle) content on the nanohardness and elastic modulus of the composites were studied in comparison with micromechanics theoretical models. Results showed that the incorporation of the silica nanoparticles at low contents (up to 5.66 vol%) significantly increases the hardness and elastic modulus of the dental composites by up to 65% and 30%, respectively. It was found that the Counto model gave good predictions for the composite modulus as a function of filler content. For the specific composites studied here, the depth of cure increases approximately linearly with the filler content, which may be ascribed to the stronger reinforcement effect of the silica nanoparticles on the dental composites at a higher particle content. These results combined demonstrate the effectiveness of silica nanoparticles as the reinforcement for dental restorative materials even at small volume fractions. POLYM. COMPOS., 40:1473–1480, 2019. © 2018 Society of Plastics Engineers
Elektrochrome Bauteile für zukünftige Mikrooptiken
Authors: Oesterschulze Egbert , Kortz Carsten , Hein Alexander
Published: May 2018

Elektrochrome Bauelemente besitzen das Potenzial, ultrakompakte Abbildungssysteme beispielsweise in Mobilgeräten zu vollwertigen Kamerasystemen aufzuwerten. Ihr sehr geringer Platzbedarf, gepaart mit einer geringen elektrischen Leistungsaufnahme, erlauben es, nicht‐mechanische Blenden (Iriden) und schaltbare optische Filter mit Funktionen zu integrieren, die bisher nicht realisierbar waren.
Geometrical Means, Medians and Variances for Samples of Particles
Authors: Stoyan Dietrich
Published: May 2018

A geometrical approach for the statistical analysis of samples of planar particle images is suggested. Using ideas of the theory of random sets it yields figures which have the meaning of sample means or medians and numbers which play the role of sample variances. Various geometrical sample summaries are presented which may serve for the description of particle samples in an illustrative way.
Characterizing the Flowability of a Powder Using the Concepts of Fractal Geometry and Chaos Theory
Authors: Kaye Brian H.
Published: May 2018

Avalanching powder is a non‐linear system which falls within a branch of the modern science known as deterministic chaos. The pattern of events generated by an avalanching powder can be described using the concepts of fractal geometry. The basic theory of these new techniques for characterizing the flowability of a powder by avalanching studies is outlined. Two different instruments: a ramp for flow studies and a rotating disc for studying avalanches are described. Data characterizing the effect of particle size, humidity, and flowagents on the flowability of powders is presented. The usefulness of angle of repose measurements is discussed.
Boundary Fractal Dimensions from Sections of a Particle Profile
Authors: Chan Leonard C. Y. , Page Neil W.
Published: May 2018

The fractal dimension of particles is commonly evaluated from complete particle boundaries. In this work, a study has been made of the self‐similar nature of complete and incomplete boundary profiles of a range of morphologically different copper powders. Boundary images were captured from SEM micrographs of particle boundaries at a range of magnifications up to nearly 14000X. An algorithm was developed to compute the fractal dimension of boundary segments. This algorithm was tested against the Koch Island fractal, and was found to give excellent estimates of the fractal dimension. For the particle system studied, the boundary fractal was found to be sensitive to magnification with appreciable drops in value at high magnification. This demonstrates that the particles studied did not have true fractal boundaries and the use of fractal theory to study particle surface roughness must be used with caution.
A CONTIN‐Based Approach Towards the Data Analysis of Particle Sizing Experiments by Centrifugal Photosedimentometry
Authors: Putman Bruno , Van der Meeren Paul , Vanderdeelen Jan
Published: May 2018

In order to analyse the output data of centrifugal photosedimentation experiments using CONTIN software, a mathematical model has been derived. This model is based on Fick's second law and describes the sedimentation behaviour of monomodal particles in a centrifugal field: it predicts that the extinction at the detection point decays exponentially until the particles are sedimented past the detection point, which gives a sharp drop of the curves to the baseline. In practice, however, a more fluently decaying profile was obtained. Simulations revealed that the polydispersity of the sample was responsible for this behaviour. When centrifugal photosedimentation data for effective monomodal and bimodal samples of fairly monodispersed PMMA lattices were analysed with CONTIN, using the model proposed, accurate particle size distributions were obtained, provided that the sample cell was completely filled. This was imperative in order to minimize the deviations of the practical application as compared with the theoretical model.
Shadow Doppler Velocimetry for Simultaneous Size and Velocity Measurements of Irregular Particles in Confined Reacting Flows
Authors: Maeda Masanobu , Morikita Hiroshi , Prassas Ilias , Taylor Alexander M. K. P. , Whitelaw Jim H.
Published: May 2018

We report the application of the Shadow Doppler Velocimeter (SDV) for spatial precise, simultaneous measurement of the size and velocity to assess the particle retention performance of a laboratory, 1/6 scale, 10 kW vertically‐fired atmospheric model of the pressurised pulverised‐coal furnace of Reichert et al. [1]. The SDV is based on the imaging of a conventional LDV probe volume onto a linear photodiode array and has the advantage over other sizing methods for irregular particles that it is tolerant of the optical misalignment and fouling which are inevitable when passing laser beams through windows in such furnaces. The size and two components of velocity of burning coal particles were measured in the present geometry which has 172 mm furnace diameter and 40 mm lateral exit duct diameter and a calculated exit bulk velocity of 4 m/s, evaluated at 300 K. The Sauter mean diameter of the particles is, within the experimental error, uniform at about 40 μm in the vertical profile normal to the axis of the exhaust pipe, 34.5 mm upstream of the exit. Coal particle velocities in the near‐exit region are directed towards the exit, closely following the gas‐phase velocities. Both these observations imply that particle retention efficiency due to streamline curvature is low and extrapolation suggests that there will be even less at large scales.
Experimental and Theoretical Study of Sprays Produced by Ultrasonic Atomisers
Authors: Sindayihebura Daniel , Cousin Jean , Dumouchel Christophe
Published: May 2018

The atomisation of liquids by means of low‐frequency ultrasonic atomisers results from unstable surface waves generated on the free surface of a thin liquid film. These unstable waves are obtained from the tuning of the amplitude and the frequency of an imposed oscillation. The thin liquid film develops as the liquid spreads over the atomising surface of the atomiser. This paper focuses on a systematic experimental analysis of the sprays produced by low‐frequency ultrasonic atomisers. The thickness of the liquid film was measured and its effects on the drop diameter were studied together with the effects of both the liquid's physical properties and the ultrasonic atomiser's characteristics. The relationship between the mean drop diameter and the surface wave wavelength was accurately determined and introduced into a mathematical approach based on the maximum entropy formalism to predict the drop size distribution of the spray. Within the range of working conditions tested, the application of this formalism is successful and provides a procedure for the prediction of spray drop size distributions from calculations only.
On‐Line Particle Size Analysis Using Ultrasonic Velocity Spectrometry
Authors: Coghill Peter J. , Millen Michael J. , Sowerby Brian D.
Published: May 2018

A new method is described for the determination of particle size distribution of slurries based on ultrasonic velocity spectrometry combined with gamma‐ray transmission. This method shares the advantages of ultrasonic attenuation spectroscopy of being capable of analyzing highly concentrated samples without dilution. However the ultrasonic velocity method is better suited to fine particles of diameter from about 0.1 to 30 μm, a greater volume of slurry is analysed and therefore sampling errors are reduced, and precise theoretical models are readily available to permit the accurate determination of size distribution by inversion of ultrasonic velocity measurements. The method can also be used to accurately determine particle size cut points by linear correlation. Using either inversion or correlation methods, the accuracy of particle size information from ultrasonic velocity spectroscopy is significantly enhanced by the independent measurement of solids loading by gamma‐ray transmission. In addition, larger sizes can be measured by combining the ultrasonic velocity method with ultrasonic attenuation measurements. The method has been tested in the laboratory on a wide variety of mineral and paint slurries. The method determined the size distribution of single component silica and alumina samples in water in agreement with laser diffraction measurements and the method successfully distinguished well and poorly dispersed TiO2 suspensions. For composite samples the method discriminated separate TiO2 and CaCO3, components and determined their proportions to within 0.25% volume. In addition the method, in combination with ultrasonic attenuation measurements, determined the size fractions of iron ore slurries below 10 and 30 μm to within 1.3% and 1.0% relative respectively, when compared with laser diffraction measurement of particle size. The CSIRO is presently designing an industrial gauge which will be manufactured and installed in an industrial slurry stream in 1997.
Phase‐Doppler Particle Sizing with Off‐Axis Angles in Alexander's Darkband
Authors: Willmann Michael , Glahn Axel , Wittig Sigmar
Published: May 2018

A promising optical layout for standard phase‐Doppler particle sizing instruments for use in two‐phase flows with extremely limited optical access is presented. When applied to turbine oil of variable temperature and therefore refractive index (1.40< n < 1.46), the layout procedure leads to several suitable off‐axis configurations. From these, a backscatter angle of ϕ = 125° is chosen owing to several geometrical restrictions. Although this angle lies in Alexander's darkband and therefore the intensities are low, the theoretical analysis indicates that this configuration is extremely insensitive to Gaussian‐beam defects, which usually aggravate backscatter applications.

Monosized droplet experiments confirmed the application of the configuration and showed an acceptable accuracy of the measurements. Experiments in a bearing chamber test rig gave reliable results and for the first time allowed an insight into the flow phenomena of this highly complex technical two‐phase flow.
Low‐Concentration Photon Correlation Spectroscopy
Authors: Willemse Alexander W. , Marijnissen Jan C. M. , van Wuyckhuyse Arjan L. , Roos Rein , Merkus Henk G. , Scarlett Brian
Published: May 2018

Photon correlation spectroscopy (PCS) is a technique to measure rapidly particle size in the sub‐micrometre region. The use of PCS is, however, limited by concentration. The upper limit is due to multiple scattering of the incident light and the lower limit is determined by the fact that fluctuations of the number of particles in the measuring zone have a significant influence on the apparent diffusion coefficient. In this paper a signal processing method is described which differentiates this influence. With this system the lower limit is no longer limited to about 100 particles in the measuring volume corresponding to a concentration of 109 particles/cm3. The limitation is now the intensity of the scattered light, which becomes too weak at a concentration of about 50 particles/cm3. As a consequence of this work, a revision to the basic theory of PCS may be necessary. Moreover, the new processing method also permits the measurement of the particle concentration in the sample.
Cylindrical Fibre Orientation Analysis by Light Scattering. Part 1: Numerical Aspects
Authors: Girasole Thierry , Bultynck Hervé , Gouesbet Gérard , Gréhan Gérard , Le Meur François , Le Toulouzan Jean Noël , Mroczka Janusz , Ren Kuan F. , Rozé Claude , Wysoczanski Dariusz
Published: May 2018

The scattering of a finite beam by an ensemble of infinite cylinders, with a spatial orientation function of the depth, is simulated by using a Monte Carlo type code, including multiple scattering effects. The properties of the scattered light collected by detectors, such as the spatial distribution of intensities, are predicted, taking into account the polarization dependence.
The Simulation of Phase‐Doppler Anemometry by the Multiple Multipole Method
Authors: Dahl Holger , Wriedt Thomas
Published: May 2018

When applying phase‐Doppler anemometry (PDA) to measurements of mass flux, one has to deal with errors caused by multiple scattering effects within a PDA measurement volume. Theoretical research on the influence of multiple scattering effects on PDA is more promising than experimental work, because each error source can be treated separately. Therefore, we have simulated multiple scattering effects occurring in the measurement volume by extending a method for light scattering calculations to Gaussian beams: the multiple multipole method (MMP). The current version of our computer program is able to simulate PDA with any set‐up consisting of Gaussian beams, using one or more homogeneous particles with arbitrary shape and movement and two detectors at any position and with an arbitrarily shaped aperture. In this paper we have concentrated on multiple scattering effects caused by two equally sized spheres, a case which is frequently found in atomizalion.
Optical Particle Sizer: A New Development with Mathematical Correction of Spread Measurement Data
Authors: Mühlenweg Heike , Weichert Reiner
Published: May 2018

The development of an optical particle sizer for aerosols is described which is based on the principle of light scattering by single particles. The instrument is appropriate for simultaneous measurements of broad particle size distributions and allows applications in hot gases. The main topic concerns the evaluation of the particle size distribution from measured data, i.e. a mathematical correction for the influence of inhomogeneous illumination and of particle shape. Irregularly shaped and randomly orientated particles which also might be illuminated inhomogeneously (laser light, border zone) deliver different signal amplitudes, which finally results in a spreading of the measured particle size distribution. Assuming a specific distribution of signal amplitudes related to every particle size and shape, the spreading of the measured data can be corrected. The mathematical procedure requires the solution of a Fredholm integral equation, i.e. the inversion of a linear equation set whose coefficients are based on a correction function to be determined by a preceding calibration. A new inversion method has been developed combining the well known regularizalion according to Phillips and Twomey and the non‐negative least‐squares method according to Lawson and Hanson.
The Effect of Shape on Intermethod Correlation of Techniques for Characterizing the Size Distribution of Powder. Part 1: Correlating the Size Distribution Measured by Sieving, Image Analysis, and Diffractometer Methods
Authors: Kaye Brian H. , Alliet David , Switzer Laurie , Turbitt‐Daoust Cherie
Published: May 2018

In recent years, powder technologists have been increasingly concerned with powder systems having irregular grain shape and texture. Of particular concern is the effect of the shape of the powder grains on the size distribution data generated by characterization methods based on various physical principles. In particular, as many laboratories switched to modern procedures based on analysis of diffraction patterns, the need to know the effect of particle shape on the data generated by the newer methods, as compared to information gathered using classical methods such as sieving or image analysis, has grown. In this study comparative data generated by sieving, image analysis, and diffractometer studies of four iron powders, arc reported and discussed.
Very low asthma death incidence among Finnish children from 1999 to 2015
Authors: Kivistö Juho E. , Karjalainen Jussi , Kivelä Laura , Huhtala Heini , Protudjer Jennifer L. P.
Published: May 2018

Background

The most recent reports concerning asthma fatalities in Finnish children are from 1998. Since that time, asthma care has improved and asthma‐related hospitalizations have decreased. Yet, it is unknown whether pediatric asthma deaths have similarly decreased.

Objective

To investigate the epidemiology of asthma deaths in the Finnish pediatric population from 1999 onward and to describe the details of fatal asthma exacerbations.

Methods

We obtained copies of the death certificates from Statistics Finland of all Finnish children aged 0‐19 years who died from asthma between 1999 and 2015. After analyzing the death certificates, the medical records of those with possible asthma death were evaluated in detail to confirm the diagnosis. Incidence rates (IR) of asthma deaths were estimated per 1 000 000 person‐years by dividing the number of asthma deaths by the total number of person‐years.

Results

Between 1999‐2015, there were 6845 deaths among 0‐19 year‐old children, of which 21 were possible asthma deaths. Based on patient records and pathological findings, we identified four convincing asthma deaths: aged 7 months, 1 year, 2.5 years, and 19 years. None had known allergies or regularly used inhaled corticosteroids. No pre‐school or school‐aged children died from asthma in Finland between 1999 and 2015. The cumulative incidence of pediatric asthma deaths was 0.19 per million person‐years.

Conclusion

Four Finnish children died from asthma between 1999 and 2015. This corresponds to a total incidence of 0.19 per million person‐years. No pre‐school or school‐aged children died from asthma in Finland during the study period.
Performance of synthetic storm technique in estimating fade dynamics in equatorial Malaysia
Authors: Jong Siat Ling , Riva Carlo , D'Amico Michele , Lam Hong Yin , Yunus Mawarni Mohamed , Din Jafri
Published: May 2018

In this paper, the synthetic storm technique (SST) is applied to 1‐minute rainfall rate collected from a rain gauge to predict the fade dynamics of the signal in an earth‐to‐satellite link in an equatorial climate location without the needs of satellite beacon measurements. The obtained results are compared with the statistics calculated from measured rain attenuation and with the ITU recommendation model. As for fade duration, a good agreement with measurements has been found together with a significant improvement in terms of prediction errors with respect to the ITU‐R model. Synthetic storm technique is also able to predict fade slope statistics fairly well and has equivalent performance of ITU‐R model.
Time series analysis of fMRI data: Spatial modelling and Bayesian computation
Authors: Teng Ming , Johnson Timothy D. , Nathoo Farouk S.
Published: May 2018

Time series analysis of fMRI data is an important area of medical statistics for neuroimaging data. Spatial models and Bayesian approaches for inference in such models have advantages over more traditional mass univariate approaches; however, a major challenge for such analyses is the required computation. As a result, the neuroimaging community has embraced approximate Bayesian inference based on mean‐field variational Bayes (VB) approximations. These approximations are implemented in standard software packages such as the popular statistical parametric mapping software. While computationally efficient, the quality of VB approximations remains unclear even though they are commonly used in the analysis of neuroimaging data. For reliable statistical inference, it is important that these approximations be accurate and that users understand the scenarios under which they may not be accurate. We consider this issue for a particular model that includes spatially varying coefficients. To examine the accuracy of the VB approximation, we derive Hamiltonian Monte Carlo (HMC) for this model and conduct simulation studies to compare its performance with VB in terms of estimation accuracy, posterior variability, the spatial smoothness of estimated images, and computation time. As expected, we find that the computation time required for VB is considerably less than that for HMC. In settings involving a high or moderate signal‐to‐noise ratio (SNR), we find that the 2 approaches produce very similar results suggesting that the VB approximation is useful in this setting. On the other hand, when one considers a low SNR, substantial differences are found, suggesting that the approximation may not be accurate in such cases and we demonstrate that VB produces Bayes estimators with larger mean squared error. A comparison of the 2 computational approaches in an application examining the hemodynamic response to face perception in addition to a comparison with the traditional mass univariate approach in this application is also considered. Overall, our work clarifies the usefulness of VB for the spatiotemporal analysis of fMRI data, while also pointing out the limitation of VB when the SNR is low and the utility of HMC in this case.