bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigations on absolute portal dosimetry for the verification of static and dynamic dose delivery in radiotherapy (in English)
Authors: Keller Harald
Published: July 2002

New in vivo dosimetry procedures using electronic portal imaging devices (EPIDs) either compare measured to predicted transmission dose, or infer patient dose from measured transmission dose images. These procedures demand a careful calibration of the portal imager. The EPID used in this research was a scanning liquid ionization chamber (SLIC). The first investigation was to see if a dose calibration of the EPID, performed on the central axis, is sufficiently accurate to estimate the dose for off‐axis points. The incident photon energy fluence distribution generated from the phase space of a linear accelerator was first convolved with Monte Carlo calculated dose spread kernels in water, which serves as the reference medium, and then in the detector. The kernels in water and the detector differ considerably at photon energies lower than 1 MeV or higher than 6 MeV. Transmission doses were then calculated in the SLIC‐EPID and in water. The dose differences are due to changing beam quality. It is shown that depending on the type of calibration, the difference can be as large as 5%, which is unacceptable for accurate transmission dose measurements. To investigate the applicability of the EPID for dynamic dose delivery techniques, the dose response to a photon beam with variable intensity was measured and theoretically modeled. It was found that the accuracy using the detector for verification of the dose from intensity modulated treatment fields delivered by a dynamically modulated multileaf technique is limited. This is due to the detector's nonlinear response. However, under certain acquisition conditions, the leaf movement during delivery can be precisely verified.
Modeling dose response in the presence of spatial variations in dose rate
Authors: Ebert Martin A. , Zavgorodni Sergei F.
Published: July 2002

Nonuniform dose rates are an inevitability in treatments involving internal sources, arising from electronic disequilibrium effects as well as nonuniformity in activity distribution. These dose‐rate nonuniformities are of consequence for protracted treatments (when dose‐delivery times are of the order of cell‐repair times). The influence of nonuniform dose rates on tumor control probability (TCP) has thus been considered. A model for TCP has been developed by merging established (linear‐quadratic based) TCP models for dose nonuniformity, with dose‐rate effects as influenced by cell repair and proliferation capacities. This model has been examined by considering treatment of spherical tumors of varying sizes filled with uniform distributions of several beta‐emitting isotopes. Dose (or dose‐rate) volume histograms (DVHs) were calculated for the combinations of tumor size and isotope, and applied to the developed TCP model. Comparison of the results identified several characteristics of the effect of nonuniform dose rate, including the balance between minimum dose and cell number as they vary with tumor size, the dominance of minimum dose (dose rate) on TCP, and the influence of cell‐proliferation effects on effective delivered dose (and the effective DVH). The model was also used to determine TCPs for simulated ‐labeled microsphere treatments of liver metastases using both uniform and clustered‐microsphere models for activity distributions, and for varying tumor size. Despite significantly higher doses being achieved via clustered (nonuniform) activity distributions, the minimum dose for clustered distributions is consistently lower than that of the corresponding uniform distributions, and TCP is always higher for the uniform distributions.
Slit x‐ray beam primary dose profiles determined by analytical transport of Compton recoil electrons
Authors: van't Veld A. A. , van Luijk P. , Praamstra F. , van der Hulst P. C.
Published: July 2002

Accurate measurement of radiation beam penumbras is essential for conformal radiotherapy. For this purpose a detailed knowledge of the dosimeter's spatial response is required. However, experimental determination of detector spatial response is cumbersome and restricted to the specific detector type and beam spectrum used. A model has therefore been developed to calculate in slit beam geometry both dose profiles and detector response profiles. Summations over representative photon beam spectra yield profiles for polyenergetic beams. In the present study the model is described and resulting dose profiles verified. The model combines Compton scattering of incident photons, transport of resulting electrons by Fermi–Eyges small‐angle multiple scattering theory, and functions to limit electron transport. This analytic model thus yields line spread kernels of primary dose in a water phantom. It is shown that the spatial response of an ideal point detector to a primary photon beam can be well described by the model; the calculations are verified by measurements with a diamond detector in a telescopic slit geometry in which all dose contributions except for the primary dose can be excluded. Effects of photon detector behavior, source size of the linear accelerator (linac) and detector size are studied. Measurements show that slit dose profiles calculated by means of the kernel are accurate within 0.1 mm of the full‐width at half‐maximum. For a theoretical point source and point detector combined with a 0.2 mm wide slit, the full‐width half‐maximum values of the slit beam dose profiles are calculated as 0.37 mm and 0.42 mm in a 6 MV and 25 MV x‐ray beam, respectively. The present study shows that the model is adequate to calculate local dose effects that are dominated by approximately mono‐directional, primary photon fluence. The analytic model further provides directional electron fluence information and is designed to be applied to various detectors and linac beam spectra.
A manual algorithm for computing dwell times for two‐catheter endobronchial treatments using HDR brachytherapy
Authors: Ezzell Gary A.
Published: July 2002

A method has been developed to permit the calculation of dwell times for endobronchial high dose rate (HDR) brachytherapy treatment using two catheters, without using a dedicated treatment planning system. Worksheets were developed to guide a user through manual calculations, and a computer program was written to automate the process. This empirical algorithm produces dose distributions that are clinically safe and reasonable. The total dwell times match those predicted by individually optimized distributions to within a few percent. The method has been used most frequently as a quality assurance check on optimized plans produced by a commercial treatment planning system, but it can serve as a back‐up method should the commercial system fail. [Worksheets with example calculations may be retrieved using anonymous ftp from the American Institute of Physics, Electronic Physics Auxillary Publication Service (EPAPS).]
Biological modeling of pelvic radiotherapy: Potential gains from conformal techniques
Authors: Fenwick John
Published: July 2002

Models have been developed to describe the dose and volume dependences of various long‐term rectal complications of radiotherapy; assumptions underlying the models are consistent with clinical and experimental descriptions of complication pathogenesis. In particular, rectal bleeding—perhaps the most common complication of modern external beam prostate radiotherapy, and which might be viewed as its principal dose‐limiting toxicity—has been modeled as a parallel‐type complication. Rectal dose‐surface‐histograms have been calculated for 79 patients treated, in the course of the Royal Marsden trial of pelvic conformal radiotherapy, for prostate cancer using conformal or conventional techniques; rectal bleeding data are also available for these patients. A maximum‐likelihood fit of the parallel bleeding model to the dose‐surface‐histograms and complication data shows that the complication status of the patients analyzed (most of whom received reference point doses of 64 Gy) was significantly dependent on, and almost linearly proportional to, the volume of highly dosed rectal wall. Over the range of highly‐dosed fractional wall volumes available for analysis (2.5%–6.5%), the rate of RTOG grade 1,2,3 bleeding falls by about 1.1% [95% confidence interval (0.04%, 2.2%)] for each 1% (absolute) reduction in the fraction of rectal wall receiving a dose of 57 Gy or more. The parallel model fit to the bleeding data is only marginally biased by uncertainties in the calculated dose‐surface‐histograms (due to setup errors, rectal wall movement, and absolute rectal surface area variability), causing the gradient of the observed volume‐response curve to be slightly lower than that which would be seen in the absence of these uncertainties. An analysis of published complication data supports these single‐center findings and indicates that the reductions in highly dosed rectal wall volumes obtainable using conformal radiotherapy techniques can be exploited to allow escalation of the dose delivered to the prostate target volume, the level of dose‐escalation achievable being quite sensitive to the exact conformal technique used.
Quantum erasure in double-slit interferometers with which-way detectors
Authors: Englert Berthold-Georg , Scully Marlan O. , Walther Herbert
Published: July 2002

Recently, Mohrhoff [Am. J. Phys. 64, 1468–1475 (1996)] has analyzed a thought experiment of ours [Nature (London) 351, 111–116 (1991)] where a double-slit interferometer for atoms is supplemented by a pair of which-way detectors. Owing to the quantum nature of these detectors, the experimenter can choose between acquiring which-way knowledge and observing an interference pattern. The latter option makes use of a procedure called “quantum erasure.” Mohrhoff (along with other bright colleagues who have made similar statements) claims erroneously that the experimenter has to make this choice before the atom hits the screen. We readdress this issue here and demonstrate that our original assertion was correct: The experimenter can choose between which-way knowledge and quantum erasure at any time, even after the atom has left its mark on the screen.
Inquiry experiences as a lecture supplement for preservice elementary teachers and general education students
Authors: Marshall Jill A. , Dorward James T.
Published: July 2002

The study reported here was designed to substantiate the findings of previous research on the use of inquiry-based laboratory activities in introductory college physics courses. The authors sought to determine whether limited use of inquiry activities as a supplement to a traditional lecture and demonstration curriculum would improve student achievement in introductory classes for preservice teachers and general education students. Achievement was measured by responses to problems designed to test conceptual understanding as well as overall course grades. We analyzed the effect on selected student outcome measures in a preliminary study in which some students engaged in inquiry activities and others did not, and interviewed students about their perceptions of the inquiry activities. In the preliminary study, preservice elementary teachers and female students showed significantly higher achievement after engaging such activities, but only on exam questions relating directly to the material covered in the exercises. In a second study we used a common exam problem to compare the performance of students who had engaged in a revised version of the inquiry activities with the performance of students in algebra and calculus-based classes. The students who had engaged in inquiry investigations significantly outperformed the other students.
Complex multipole beam approach to acoustic scattering problems
Authors: Boag Amir , Boag Alona , Michielssen Eric
Published: July 2002

A novel approach to reducing the matrix size associated with the boundary element/moment method solution of the problem of acoustic scattering from arbitrarily shaped closed bodies is presented in this paper. The key step in this approach is to represent the scattered field in terms of a series of beams produced by multipole sources located in a complex space. On the scatterer boundary, the fields generated by these multipole sources resemble the Gabor basis functions. By utilizing the properties of the Gabor series, guidelines for selecting the orders as well as locations of the multipole sources are developed. The present approach not only reduces the number of unknowns, but also generates a generalized impedance matrix with a banded structure. The accuracy of the proposed method is verified by using internal accuracy checks and by comparing the numerical results with the analytic solutions for spherical scatterers.
Optimal and wavelet-based shock wave detection and estimation
Authors: Sadler Brian M. , Pham Tien , Sadler Laurel C.
Published: July 2002

Detection and estimation of aeroacoustic shock waves generated by supersonic projectiles are considered. The shock wave is an N-shaped acoustic wave emanating in the form of an acoustic cone trailing the projectile. An optimal detection/estimation scheme is considered based on a parametric signal plus white Gaussian noise model. To gain robustness and reduce complexity, we then focus on gradient estimators for shock wave edge detection, exploiting the very fast shock rise and fall times. The approach is cast in terms of a wavelet transform where the level of smoothing corresponds to scale. A multiscale analysis is described, consisting of multiscale products, to enhance edge detection and estimation. This method is effective and robust with respect to unknown environmental interference that will generally not exhibit singularities as sharp as the N-wave edges. Experimental results are presented for discriminating N waves in the presence of vehicle noise. Results are also shown, as a function of miss distance, for gradient-based detection of simulated small projectile shocks inserted into recorded tank noise.
Boundary-variation solutions for bounded-obstacle scattering problems in three dimensions
Authors: Bruno Oscar P. , Reitich Fernando
Published: July 2002

Rigorous formalisms are presented for the numerical solution of problems of acoustic scattering by bounded obstacles in three dimensions. These methods are based on a perturbative technique recently demonstrated in problems of diffraction by gratings. Like those grating solvers, these new bounded-obstacle algorithms can produce highly accurate solutions for a wide variety of scattering geometries.
Time-evolution modeling of seafloor scatter. I. Concept
Authors: Pouliquen E. , Bergem O. , Pace N. G.
Published: July 2002

A time-series model for acoustic seafloor backscattering is described. The method analytically expresses the elementary time-backscattered response of every seafloor surface and every seafloor volume infinitesimal element. For chosen geometric, acoustical, and acquisition parameters, they are summed to produce in the time domain a realization of the reverberation time-pressure field received at the source. The approach is based on the Kirchhoff approximation for the seafloor interface backscattering and on the Small Perturbation theory for the seafloor volume. It only accounts for single backscattering mechanisms of the compressional wave with the seafloor. The model is implemented using calculated height fields for the water-sediment interface and distributed seafloor volume inhomogeneities. The analytical description of the model and its limitations is described in this paper.
A sound judgment depending on the urban visual setting?
Authors: Viollon Stephanie , Lavandier Catherine
Published: July 2002

In a number of experiments carried out in the experimental psychology field, audition and vision proved to provide information which interacted each other. What about the audio–visual interactions in the city? The first aim of this research was to develop an experimental procedure involving methodological parameters best suitable to test the influence of the visual setting on the sound judgment in the complex sound environment. The second one was to apply it to various urban situations. In a series of simulation tests, participants rated some urban sound stimuli and this, under different visual conditions varying according to the degree of urbanization. An artificial audio–visual environment was specifically created. The experimental methods were based on three types, involving different structures of presentation of the audio–visual combinations. For each of them (except for the completely random one), two types of orders of presentation of both the visual and sound sequences were defined. The results for all the experiments were commented on and compared. The best suitable experimental method was validated. The present results point out that the visual influence was many sided. Some clusters of sound stimuli and sound variables were defined according to the visual influence exerted.
Temperature dependence of collective phonon relaxation time and acoustic attenuation in pure GaAs
Authors: Lambade S. D. , Sahasrabudhe G. G.
Published: July 2002

In this paper, the temperature dependence of collective phonon-relaxation time in pure GaAs in the range 80–300 K was investigated using a refined numerical approach in which the interaction of the acoustic wave with the complete spectrum of phonon modes is taken into consideration. These are further used to evaluate the acoustic attenuation for longitudinal waves along the [110] and [111] directions and for shear waves along the [110] direction with polarizations along [110] and [001]. The calculations are performed using Mason’s pure-mode scheme, Mason’s theory with refinement suggested by Merkulov et al., and also using Nava’s modified formulation of Woodruff’s theory. The results obtained using this computational scheme show better agreement with the experiment than those obtained using Mason’s pure-mode scheme in most of the cases studied.
Relations between Certain Non-Viscometric and Viscometric Material Functions
Authors: Huilgol R. R.
Published: July 2002

Noll established that in all motions with constant stretch history, the history of the right relative Cauchy-Green tensor is given by (exp−sLT) exp (−sL). He showed that there were three types of such motions depending on whether L is nilpotent of order two, or of order three and not two, or not nilpotent. The case of nilpotency of order two has been studied extensively as viscometric flows and the case of a symmetric L has been examined as elongational flows. Recently, examples of motions with L being nilpotent of order three and not two, and not nilpotent and not symmetric were given by the author. It is the purpose of this paper to select an example of a motion from each of these two categories and to relate the material functions in these two non-viscometric motions with constant stretch history to the viscometric material functions of the incompressible simple fluid, by treating the flows as nearly viscometric flows in the sense of Pipkin and Owen. The response of the incompressible simple fluid in these two flows is then compared to that of the BKZ fluid.
Rheology of thermotropic liquid crystalline copolyester Vectra E
Authors: Karis T. E. , Park O. O. , Yoon D. Y.
Published: July 2002

The melt rheology of a new liquid crystalline copolyester Vectra E from Hoechst-Celanese Corp. was investigated. A Rheometrics mechanical spectrometer was used to characterize the change in melt rheology produced by annealing below the melting temperature with dynamic, step shear rate, and step strain tests. The coupled relaxation model was employed in analyzing the step strain test data. Typically, thermotropic liquid crystalline copolyesters exhibit a reversible annealing effect which is erased by heating above the melting transition followed by rapid cooling. The unique feature of Vectra E is an irreversible annealing phenomenon. The unannealed copolyester melts near 330 °C, above which the viscosity decreases by at least two orders of magnitude. After annealing at 300 °C for 16 h, the copolyester exhibits a large increase in the melting transition temperature to 380 °C. Furthermore, upon melting the annealed sample the shear relaxation modulus and viscosity of the melt remain 2–3 orders of magnitude greater than those for the unannealed sample. These observations are consistent with a significant increase in the molecular weight of the Vectra E copolyester during annealing in the solid state at 300 °C.
Viscoelastic properties of colloidal gels
Authors: Rueb C. J. , Zukoski C. F.
Published: July 2002

The microstructure and scaling of mechanical properties of dense colloidal gels were investigated as a function of volume fraction and strength of interparticle attraction. Gels were reversibly formed by cooling suspensions of octadecyl silica particles in decalin or tetradecane. Shear history independence of mechanical properties was ensured by preshearing the suspensions in the gelled state. Gelation resulted in suspensions with apparent fractal dimensions of 1.4. Shear densification resulted in an apparent fractal dimension of 2.5 for structures containing many particles. When the gelled suspension was presheared, just after the shear rate was set to zero, elastic moduli were small. Over time, the moduli recovered to a time independent value, G∞′, at a rate α. When measured over a wide range of volume fraction, φ, and strength of interparticle attraction, G∞′, α, and the strain limiting the extent of linear response to oscillatory deformations, γM, fell onto master curves when plotted as a function of φ/φG for 1.1<φ/φG<5. Here φG is the gel volume fraction that varied from 0.11 to 0.59 for temperatures studied.
The two-way interaction between anisotropic flow and fiber orientation in squeeze flow
Authors: Ericsson K. A. , Toll S. , Månson J.-A. E.
Published: July 2002

The rheology of a discontinuous fiber filled polypropylene in squeeze flow between parallel plates is studied. The material has an initial anisotropic fiber orientation distribution and therefore displays a strongly anisotropic in-plane flow behavior with predominant flow transverse to the axis of principal orientation. The kinematic field is computed using a linear, orthotropic constitutive model, where the fibers are assumed to move affinely with the surrounding fluid. The fiber orientation distribution is updated in each timestep thus coupling orientation and flow. Two different orientation descriptions are evaluated: orientation tensors with closure approximations, and a technique based on direct solution of the orientation of a set of test fibers. The two methods are first compared to exact solutions of the orientation distribution function in simple shear and pure extension; the direct solution is exact within numerical error, whereas the methods based on orientation tensors and quadratic and hybrid closure fail to correctly describe any transient fiber orientation evolution. Finally, the orientation representations are implemented in the kinematic model and compared to the experimental data; the direct solution method is found to give a very accurate prediction of the observed flow kinematics, whereas the other techniques result in substantial errors.
NNK from tobacco smoking enhances pancreatic cancer cell stemness and chemoresistance by creating a β2AR‐Akt feedback loop that activates autophagy
Authors: Chen Xin , Zhang Weifan , Liu Rujuan , Zhu Zeen , Gong Mengyuan , Wang Qiqi , Qian Weikun , Wu Zheng , Ma Qingyong , Wang Zheng
Published: May 2022

Low responsiveness to chemotherapy is an important cause of poor prognosis in pancreatic cancer. Smoking is a high‐risk factor for pancreatic cancer and cancer resistance to gemcitabine; however, the underlying mechanisms remain unclear. 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanone (NNK) is the main metabolite of tobacco burning and has been shown to be associated with cancer development and chemoresistance. However, in pancreatic cancer, its mechanism remains poorly understood. In this study, we found that NNK promoted stemness and gemcitabine resistance in pancreatic cancer cell lines. Moreover, NNK increased autophagy and elevated the expression levels of the autophagy‐related markers autophagy‐related gene 5 (ATG5), autophagy‐related gene 7 (ATG7), and Beclin1. Furthermore, the results showed that NNK‐promoted stemness and gemcitabine resistance was partially dependent on the role of NNK in cell autophagy, which is mediated by the β2‐adrenergic receptor (β2AR)‐Akt axis. Finally, we proved that NNK intervention could not only activate β2AR, but also increase its expression, making β2AR and Akt form a feedback loop. Overall, these findings show that the NNK‐induced β2AR‐Akt feedback loop promotes stemness and gemcitabine resistance in pancreatic cancer cells.
Pathological and Ultrastructural Characterization of an Edwardsiella ictaluri Triple hemR Mutant
Authors: Ibrahim Iman , Abdelhamed Hossam , Baumgartner Wes , Wills Robert W. , Awadin Walaa , Elbegawy Mahmoud , Lawrence Mark L. , Karsi Attila
Published: May 2022

Enteric septicemia of catfish, which is caused by Edwardsiella ictaluri, is detrimental to farmed Channel Catfish Ictalurus punctatus. The hemin receptor HemR is involved in binding and uptake of heme into bacteria. Here, we explored pathological and ultrastructural changes in catfish fry that were immunized with a triple hemR mutant of E. ictaluri and challenged with wild-type E. ictaluri (EiWT) 28 d after immunization. Following immunization, pathological changes in the triple hemR-immunized fry were less severe compared to the EiWT-exposed control fry. Widely disseminated bacteria and severe necrosis in most organs, especially the kidney and spleen, were detected in both groups at days 4, 5, and 6. Multifocal granulomatous encephalitis with bacteria was seen in hemR-immunized fry at days 21 and 28 and in EiWT-exposed control fry at day 14. Phagocytic cells in the kidney and spleen of EiWT-exposed control fry contained more replicating bacteria compared to hemR-immunized fry. During the EiWT challenge of immunized fry, a robust immune response was observed in the triple hemR-immunized fry compared to the sham-vaccinated group. Many activated phagocytic cells were detected in the kidney and spleen with fragmented or no bacteria in the triple hemR-immunized fry. Our data suggested that virulence of triple hemR was lower and the onset of the lesions was delayed compared to EiWT. Additionally, triple hemR-immunized fry could mount an immune response and had milder lesions compared to the sham control after EiWT exposure.
Experimental dosimetry of EDR2 films in scanning carbon‐ion irradiation
Authors: Wang Weiwei , Deng Yu , Huang Zhijie
Published: May 2022

Purpose

To investigate the dose‐sensitometric response of extended dose range (EDR2) films to scanning carbon‐ion beams and to evaluate the applications of the obtained response curves to carbon‐ion dose distributions.

Methods

EDR2 films were irradiated by mono‐energetic scanning carbon‐ion beams with different doses to obtain sensitometric curves at different integrated depth doses (DDDs). Six different DDDs were generated by using a proper buildup for each mono‐energetic beam and were used to investigate the energy dependence. The sensitometric curves were obtained by fitting the net optical density (netOD) to dose at different DDDs. The dose difference between the value converted from the netOD and that calculated in the treatment planning system (TPS) was investigated to evaluate the application scope of the sensitometric curve.

Results

Digitizing the EDR2 film with a resolution of 0.36 (72 dpi) provided a good signal‐to‐noise ratio, and the sensitometric curve was linear at all DDDs of clinically relevant incident kinetic energies in the netOD range of 0.02–1.70 for carbon‐ion film dosimetry. The factors used to convert the netOD to absorbed dose were expressed as a linear function of DDDs, with which the depth dose difference between converted and TPS was less than 3% in the proximal area for incident kinetic energies lower than 307.5 MeV/u.

Conclusion

The EDR2 film is a feasible tool for scanning carbon‐ion beam profile measurements by directly evaluating the netOD distribution with proper digitizing resolution and netOD range. By applying the conversion factors, the EDR2 film can also be employed to perform the percentage depth dose consistency checking and linear energy transfer comparison of carbon‐ion lower than 307.5 MeV/u.
Sigmoid model analysis of breast dynamic contrast‐enhanced MRI: Distinguishing between benign and malignant breast masses and breast cancer subtype prediction
Authors: Koori Norikazu , Miyati Tosiaki , Ohno Naoki , Kawashima Hiroko , Nishikawa Hiroko
Published: May 2022

Dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) is performed to distinguish between benign and malignant lesions by evaluating the changes in signal intensity of the acquired image (kinetic curve). This study aimed to verify whether the existing breast DCE‐MRI analyzed by the sigmoid model can accurately distinguish between benign and invasive ductal carcinoma (IDC) and predict the subtype.

A total of 154 patients who underwent breast MRI for detailed breast mass examinations were included in this study (38 with benign masses and 116 with IDC. The sigmoid model involved the acquisition of images at seven timepoints in 1‐min intervals to determine the change in signal intensity before and after contrast injection. From this curve, the magnitude of the increase in signal intensity in the early phase, the time to reach the maximum increase, and the slopes in the early and late phases were calculated. The Mann–Whitney U‐test was used for the statistical analysis.

The IDC group exhibited a significantly larger and faster signal increase in the early phase and a significantly smaller rate of increase in the late phase than the benign group (P < 0.001). The luminal A‐like group demonstrated a significantly longer time to reach the maximum signal increase rate than other IDC subtypes (P < 0.05).

The sigmoid model analysis of breast DCE‐MRI can distinguish between benign lesions and IDC and may also help in predicting luminal A‐like breast cancer.
Clinicopathological correlates of pyramidal signs in multiple system atrophy
Authors: Lin Chi‐Ying R. , Viswanathan Anisha , Chen Tiffany X. , Mitsumoto Hiroshi , Vonsattel Jean P. , Faust Phyllis L. , Kuo Sheng‐Han
Published: May 2022

Objective

Pyramidal signs are common but often under‐recognized in multiple system atrophy (MSA). The clinicopathological correlates of pyramidal signs in MSA are not well characterized. The present study aims to understand the role of pyramidal signs in MSA.

Methods

We examined 40 autopsy‐confirmed MSA cases in New York Brain Bank. The pyramidal signs were quantified by an established rating scale, summarized as the pyramidal score. We assessed whether pyramidal scores are associated with autonomic, parkinsonism, and cerebellar features and survival. We also examined whether the density of glial cytoplasmic inclusions (GCIs) in the motor cortex and its underlying white matter is associated with the pyramidal score.

Results

MSA parkinsonian type cases have higher pyramidal scores compared to cerebellar type cases (p = 0.017). MSA cases with high pyramidal scores are more likely to have laryngeal stridor (OR = 4.89, p = 0.022), but less likely to have orthostatic hypotension (OR = 0.11, p = 0.006) and erectile dysfunction (OR = 0.05, p = 0.018). MSA cases with high pyramidal scores do not differ from those with low pyramidal scores in terms of bowel dysfunction, dry eyes and mouth, and survival. Finally, MSA cases with more GCIs in the motor cortex have higher pyramidal scores compared to those with few GCIs (p = 0.017).

Interpretation

Pyramidal signs in MSA are associated with the parkinsonian subtype, laryngeal stridor, and certain autonomic dysfunction.
Corrosion Properties of Ni60/WC Coating with Abrasion‐Resistant Microdimples Ablated by Nanosecond Laser
Authors: Zhong Lin , Wang Zixuan , Wang Guorong , He Xia , Wei Gang , Chen Linyan , Wu Xiaolong , Luo Minmin , Kang Guirong , Li Zhichao
Published: May 2022

Herein, the influence of laser‐ablated cracks in microdimples on the corrosion properties of Ni60/tungsten carbide (WC) coating is investigated. It is based on the dimension parameters of circular microdimples, which is optimized by unit and full‐size friction‐wear experiments for a textured plunger and sealed‐disk assembly element. The Poisson distribution is used to perform the statistical and characterization analyses of the microcrack defects on the surface of Ni60/WC coating with the circular microdimples ablated by the nanosecond laser. The key process parameters of laser machining in groups with a high and a low ratio of apparent microcrack are selected, and are compared with the nontextured group on the coating surface through immersion–corrosion and electrochemical–corrosion tests. It finds the high and low apparent‐microcrack groups under the action of static corrosion, and the coating has the similar corrosion behavior with the nontextured group. When apparent microcrack does not extend to the substrate, the nanosecond‐laser ablation of microdimples does not change the coating corrosion properties. Moreover, the corrosion properties of the coating are improved by laser ablation recrystallization. The experimental support is provided in the results for the application of microdimples on the surface of fracturing‐pump plunger coating in acidic environments.
Comment on “Interplay of Structural and Optoelectronic Properties in Formamidinium Mixed Tin‐Lead Triiodide Perovskites”
Authors: Baranovskii Sergei D. , Höhbusch Pauline , Nenashev Alexey V. , Dvurechenskii Anatolii V. , Gerhard Marina , Hertel Dirk , Meerholz Klaus , Koch Martin , Gebhard Florian
Published: May 2022

Studying optoelectronic properties in FAPb1−xSnxI3 and in FA0.83Cs0.17Pb1−xSnxI3 perovskites as a function of the lead:tin content, Parrott et al. (2018) and Savill et al. (2020) observed the broadest luminescence linewidth and the largest Stokes shift in mixed compositions with Sn <25% and with >85%. It is in contrast to the intuitive expectation of the largest effects of alloy disorder for the 50:50 composition. This comment addresses the alloy disorder caused by statistical local spatial fluctuations of the alloy composition and shows that the largest effects of alloy disorder for perfectly random fluctuations in FAPb1−xSnxI3 and FA0.83Cs0.17Pb1−xSnxI3 are, in fact, expected for x < 0.25 and for x > 0.85. It can be one of the reasons why Pb‐rich and Sn‐rich Sn‐Pb perovskites typically show shorter photoluminescence (PL) lifetimes, broader emission, increased Stokes shifts, reduced PL quantum yield, and higher Urbach tails, compared with their lead‐only counterparts.
Charge Balance in Red QLEDs for High Efficiency and Stability via Ionic Liquid Doping
Authors: Li Yunfei , Fan Xi , Shen Cai , Shi Xixiu , Li Pengcheng , Hui Kwun Nam , Fan Junpeng , Kang Kai , Zhang Ting , Qian Lei
Published: May 2022

Colloidal quantum dot light‐emitting diodes (QLEDs) simultaneously exhibiting high external quantum efficiency (EQE) and operation stability are achieved via a simple solution processing. A silver bis(trifluoromethane‐sulfonyl)imide treatment that is used to chemically dope the poly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PEDOT:PSS) hole injection layer (HIL) is proposed. The ionic liquid salt acts as an effective p‐dopant for high charge concentrations; and it raises the work functions and surface potentials of the PEDOT:PSS HIL for an interface energy band alignment. Benefiting from a raised hole mobility and a better charge mobility balance, the processing‐simple colloidal red QLEDs yielded the highest EQE of up to 17.4%. In particular, a very broad plateau of EQE values over 16.5% in the brightness of 400–10 000 cd m−2 is obtained. Moreover, the packaged QLEDs exhibit an excellent operation stability in ambient air. The T95 (time for the device brightness to decrease to 95% of its initial brightness) at an initial brightness of 1000 cd m−2 is 4160 h. The work highlights a promising ionic liquid strategy to guide the development of high‐performance and cost‐effective QLEDs.
Carbon Dioxide Valorization via Formate Electrosynthesis in a Wide Potential Window
Authors: Sui Peng‐Fei , Gao Min‐Rui , Liu Subiao , Xu Chenyu , Zhu Meng‐Nan , Luo Jing‐Li
Published: May 2022

The electrochemical CO2 reduction reaction (CO2RR) is a promising strategy to convert CO2 to carbon‐based fuels and to simultaneously reduce the emission of greenhouse gases into the atmosphere. In this work, the bismuth subcarbonate nanoflowers (BOC NFs) are facilely prepared through a one‐pot synthesis method for efficient formate electrosynthesis through CO2RR. Benefiting from the crystal structure and sheet‐stacked morphology, the in situ measurements and theoretical calculation results reveal the self‐reinforced CO2 adsorption properties and rapid CO2 adsorption–desorption kinetics on the catalyst surface, which significantly facilitate the CO2RR process. As a result, the desirable Faradaic efficiencies of over 90%, with a maximum value of 98.9%, toward formate formation, are achieved in a wide potential window from −0.8 to −1.4 V in an H‐type cell. Moreover, in a flow cell, the superior intrinsic activity of BOC NFs guarantees the high throughput electrocatalytic performance of CO2RR and the FEformate of over 90% with high current density is achieved in a potential range as wide as 1200 mV, demonstrating the great potential of BOC NFs for practical CO2RR applications. These results underscore the effectiveness of designing electrocatalysts with self‐reinforced CO2 adsorption properties to improve electrocatalytic performance for efficient CO2RR.
Patterned Calcite Microneedle Arrays formed on Mollusk Shells via Oriented Dissolution and Their Application for Transdermal and Intracellular Delivery
Authors: Li Jiangfeng , Song Ningjing , Li Baosheng , Pan Ercai , Ma Yurong
Published: May 2022

Transdermal delivery through the skin barriers is an important medical procedure to transfer drugs into the human body. However, there is an urgent requirement to design microneedle‐based transdermal delivery systems with superior delivery efficiency, low toxicity, excellent mechanical property, and simple synthetic process. Herein, perpendicular calcite microneedle arrays with a length of about 8 µm are synthesized on the prism layer of mollusk shells via oriented dissolution while dextran sulfate sodium is applied as an additive. Ordered patterns of long calcite microneedles with a length about 45 µm are synthesized in a large scale for the first time on mollusk prism layers via oriented dissolution while circular masks are covered on the prism layers during the dissolution process. The long calcite microneedle arrays with the ordered pattern are found to be efficient for transdermal delivery of dexamethasone and for therapy of ear psoriasis in mice. The calcite microneedle arrays are also applied to transport Cy3 fluorescent biomolecules through cell membranes in this work. These calcite microneedle arrays can be applied as efficient transportation substrates for both transdermal and intracellular delivery, which exhibit advantages such as high drug loading capacity, superior biocompatibility, nontoxicity, high mechanical properties, and easy synthesis strategy.
Donor N‐Substitution as Design Principle for Fast and Blue Luminescence in Carbene‐Metal‐Amides
Authors: Reponen Antti‐Pekka M. , Chotard Florian , Lempelto Aku , Shekhovtsev Vitalii , Credgington Dan , Bochmann Manfred , Linnolahti Mikko , Greenham Neil C. , Romanov Alexander S.
Published: May 2022

A series of gold‐centered carbene‐metal‐amide (CMA) complexes are synthesized with the carbazole donor ligand modified by substitution with nitrogen atoms in varying positions. The luminescence of new aza‐CMA complexes shows a significant blueshift depending on the position of the N atom, to provide bright blue‐green (500 nm), sky‐blue (478 nm), blue (450 nm) and deep‐blue (419 nm) light‐emitters. The impact of the electron‐withdrawing aza‐group on the nature of the luminescence and the excited state energies of the locally excited (LE) or charge transfer (CT) states have been interpreted with the help of transient absorption, in‐depth photoluminescence experiments and theoretical calculations. By considering the orbital characters of the lowest CT and LE states, we develop a new concept for simultaneous energy tuning for both of these states with a single aza‐substitution, allowing for fast and blue CT emission. This concept allows the interference of 3LE phosphorescence to be avoided at room temperature. The approach is extended to two N substitutions at the optimal location in the 3‐ and 6‐positions of the carbazole skeleton. These results suggest a practical molecular design towards the development of bright and deep‐blue emitting CMA materials to tackle the stability problem of energy‐efficient deep‐blue OLEDs.
Direct Thioamination of Cyclohexanones via Difunctionalization with Thiophenol and Aniline
Authors: Tang Minli , Zhang Li , Mao Guojiang , Xiao Fuhong , Shao Wen , Deng Guo‐Jun
Published: May 2022

A synthetic method of o‐sulfanylanilines from cyclohexanones, amines, and thiophenols under transition‐metal‐free conditions is disclosed. This is the first report on the direct thioamination of cyclohexanones via N‐iodosuccinimide (NIS) promoted oxidative dehydroaromatization. Non‐aromatic cyclohexanones were smoothly dehydrogenated, and acted as an aryl source using oxygen as a green oxidant. The capacity of the resultant o‐sulfanylanilines for synthesis of N‐arylphenothiazines has been further demonstrated.

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Metallfreie N−H‐Bindungsaktivierung mit Phospha‐Wittig Reagenzien**
Authors: Dankert Fabian , Siewert Jan‐Erik , Gupta Priyanka , Weigend Florian , Hering‐Junghans Christian
Published: May 2022

N‐haltige Moleküle werden meist ausgehend von Ammoniak (NH3) dargestellt. Die Ammoniakaktivierung wurde sowohl für individuelle Übergangsmetallzentren als auch für niedervalente Hauptgruppenspezies gezeigt. Phosphinidene, einfach koordinierte Phosphorspezies, können durch Phosphine, in sogenannten Phosphanylidenphosphoranen vom Typ RP(PR′3), stabilisiert werden. Wir demonstrieren hier die einfache, metallfreie NH3‐Aktivierung mit ArP(PMe3), wodurch zum ersten Mal isolierbare sekundäre Aminophosphine des Typs ArP(H)NH2 entstehen. DFT‐Studien zeigen, dass zwei NH3‐Moleküle zusammenwirken, um einen Austausch von PMe3 gegen NH3 zu ermöglichen. Außerdem wurde die Aktivierung von H2NR und HNR2 nachgewiesen.
Poly‐cardanol as plasticizer and compatibilizer on styrene butadiene rubber with improved processability and silica dispersion
Authors: Qian Wei , Gao Yu , Wang Peng , Lu Xiaoyu , Zheng Yanyan , Chen Qinhui
Published: May 2022

Natural products used as plasticizer can inhibit its migration in rubber and improve the dispersion of inorganic power. Herein, styrene butadiene rubber (SBR) was plasticized by poly‐cardanol (PCA) originated from the Friedel–Crafts alkylation without solvent of cardanol which was extracted from abandoned cashew nut shell. Results show that the Mooney viscosity of SBR/PCA compounds decreases from 45.8 to 34.7 and Tg from −52°C to −56.3°C when PCA is added from 0 to 30 phr. Moreover, the elongation at break of SBR contained 30 phr PCA increases by 515% compared with SBR. PCA also shows amphiphilic, which is verified by the improved dispersion of SiO2 in SBR/PCA compounds. The swelling ratio of SBR/PCA/SiO2 vulcanized rubber decreases and the crosslinking density increases. Meanwhile, the elongation at break of SBR70‐40 vulcanized rubber is 17.3%, which is higher than that of SBR100‐40 vulcanized rubber. PCA, acted as plasticizer and compatibilizer, provides a simple and green way for the application of natural products in the rubber industry.
Regulating the dissolving system of ultra‐high molecular weight polyethylene to enhance the high‐strength and high‐modulus properties of resultant fibers
Authors: Wang Yi , Fu Jiabin , Song Qingquan , Yu Junrong , Wang Yan , Hu Zuming
Published: May 2022

The molecular weight loss of ultra‐high molecular weight polyethylene (UHMWPE) fibers is extremely serious in comparison with raw materials due to the high temperature and strong shearing during dissolving process. In this study, decalin was introduced as preswelling solvent and the dissolving system was regulated to improve the solubility of UHMWPE in paraffin oil without severe degradation so as to prepare UHMWPE fibers with high molecular weight retention and low entanglement. UHMWPE was preswelling in decalin with different content, the mass ratio of decalin to UHMWPE were 1:1, 1.5:1, 2:1, 2.5:1, and 3:1. All UHMWPE fibers were prepared by gel‐spinning and hot‐drawing. UHMWPE fibers possess the highest molecular weight after preswelling of UHMWPE in decalin (with a mass ratio of 3:1 to UHMWPE, namely UPE/dec‐s‐3 sample). What's more, the entanglement of UHMWPE fibers gained from UPE/dec‐s‐3 sample has been observably diluted in comparation to that from UPE‐neat and other swollen samples. More importantly, the tensile strength and modulus of UHMWPE fibers obtained from UPE/dec‐s‐3 sample can reach 31.41 and 1446.26 cN/dtex, increased by 15.1% and 14.3% compared with UPE‐neat fibers, respectively. Besides, the thermal and crystallization behavior of UHMWPE fibers prepared from swollen UHMWPE have also been boosted.
Impact energy absorption of block copolymer/tackifier blends: Effect of compatibility, viscoelasticity, and laminate structures
Authors: Kishi Hajime , Nomura Yutaka , Hamano Ryota , Yamada Ryota , Matsuda Satoshi , Kakibe Takeshi , Oka Yoshihiro , Urahama Yoshiaki
Published: May 2022

This work studied the effects of tackifiers on the impact energy absorption properties of block copolymers (BCPs) comprising poly(styrene)‐b‐poly(isoprene)‐b‐poly(styrene) (SIS) and poly(methyl methacrylate)‐b‐poly(n‐butyl acrylate)‐b‐poly(methyl methacrylate) (MAM). A rosin ester resin (RE) and an aliphatic petroleum resin (C5PR) were compared as the tackifiers. Analyses of Hansen solubility parameters and observations using electron microscopy indicated that both tackifiers were highly compatible with the poly(isoprene) component of the SIS, while the RE also showed good compatibility with the poly(n‐butyl acrylate) phase of the MAM. The impact energy absorption characteristics of laminates made by applying layers of BCP/tackifier blends to cured epoxy substrates were evaluated using a pendulum impactor. The extent of energy absorption by these laminates was found to increase within specific tackifier concentration ranges. However, the C5PR showed poor compatibility with the MAM and had almost no effect on the energy absorption of the laminates. The energy absorption of the laminates could be described based on the calculated loss factor,η, determined using the RUK equation including the viscoelastic parameters (both tanδand storage modulus) for the BCP/tackifier blends, considering the time–temperature superposition principle, and for the laminate structures.
The Markov discrete time δ‐shock reliability model and a waiting time problem
Authors: Chadjiconstantinidis Stathis , Eryilmaz Serkan
Published: May 2022

‐shock model is one of the widely studied shock models in reliability theory and applied probability. In this model, the system fails due to the arrivals of two consecutive shocks which are too close to each other. That is, the system breaks down when the time between two successive shocks falls below a fixed threshold δ. In the literature, the δ‐shock model has been mostly studied by assuming that the time between shocks have continuous distribution. In the present paper, the discrete time version of the model is considered. In particular, a proper waiting time random variable is defined based on a sequence of two‐state Markov dependent binary trials and the problem of finding the distribution of the system's lifetime is linked with the distribution of the waiting time random variable, and we study the joint as well as the marginal distributions of the lifetime, the number of shocks and the number of failures associated with these binary trials.