bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron-Accepting π-Conjugated Compound Containing Cyano-Substituted Naphthobisthiadiazole as Nonfullerene Acceptor in Organic Solar Cells
Authors: Ie Yutaka , Jinnai Seihou , Oi Ayumi , Seo Takuji , Moriyama Taichi , Minami Ryunosuke , Higashida Suguru
Published: June 2021

The incorporation of electron-accepting units into π-conjugated systems can allow the modulation of the physical properties and frontier orbital energy levels of the molecules. An electron-accepting π-conjugated compound (CNNTz-TR) containing cyano-substituted naphthobisthiadiazole (CNNTz) was synthesized via a nucleophilic substitution reaction as the key step. Owing to the presence of the cyano groups, CNNTz-TR affords a low-lying lowest unoccupied molecular orbital energy level. Organic solar cells based on the blend films of CNNTz-TR and a low-bandgap donor exhibited moderate power conversion efficiencies. The results showed that embedding the CNNTz unit into the π-conjugated backbone is an effective approach for designing electron-accepting semiconducting materials.
The Sensorineural Hearing Loss Related to a Rare Infratentorial Developmental Venous Angioma: A Case Report and Review of Literature
Authors: Ebrahimzadeh Kaveh , Tavassol Hesameddin Hoseini , Mousavinejad Seyed Ali , Ansari Mohammad , Kazemi Reyhaneh , Bahrami-Motlagh Hooman , Jalili Khoshnoud Reza , Sharifi Guive , Samadian Mohammad , Rezaei Omidvar
Published: June 2021

Background Developmental venous anomaly (DVA) is a benign venous abnormality draining normal brain parenchyma. It is mostly asymptomatic; however, rare complications such as hemorrhage may lead to symptomatic conditions. Headache and seizure are the most common symptoms. Hearing loss is an extremely rare presentation of DVA. To our knowledge, only five cases of DVA, presenting with hearing loss, had been reported so far.

Case Presentation We report the case of a 27-year-old woman who presented with a sensorineural hearing loss followed by facial paresis. Magnetic resonance imaging (MRI) and computed tomography (CT) angiography revealed hematoma with adjacent converging veins showing a typical “caput medusa” sign in the left middle cerebellar peduncle, in favor of DVA. Due to the compression effect of hematoma, she underwent surgery. Hearing loss and facial paresis improved significantly during the postoperative follow-up.

Conclusion Although DVA is mostly benign and asymptomatic, complications such as hemorrhage rarely occur. Hearing loss is an extremely rare presentation that can be attributable to the compression effect on the cranial nerve VII to VIII complex. In the case of compression effect or progression of symptoms, surgical intervention is necessary. A good clinical outcome could be expected postoperatively.
Tandem Autologous Hematopoietic Stem Cell Transplantation in Very Young Patients with Multiple Myeloma
Authors: Naithani Rahul , Dayal Nitin , Rai Reeta
Published: June 2021

Introduction Multiple myeloma (MM) in very young patients is uncommon, and no treatment guidelines exist for these patients.

Patients and Methods We performed a retrospective analysis of five very young myeloma patients who underwent tandem autologous hematopoietic stem cell transplantation (HSCT).

Results The median age was 37 years (range = 34–40 years). A median of two leukapheresis was performed (range = 1–4). The median number of hematopoietic stem cells collected was 5.4 × 106/kg (4.4–8.2 × 106/kg). During first transplant, four patients received melphalan of 200 mg/m2 and one patient received melphalan of 140 mg/m2 (due to renal failure) as conditioning regimen. Second transplant conditioning was melphalan of 200 mg/m2 for one patient and melphalan of 140 mg/m2 for remaining four patients. Two patients were in complete remission, and two were in very good partial remission and one patient progressed to active disease at the time of tandem autologous bone marrow transplant. All patients developed significant mucositis. Neutrophil and platelet recovery was longer in tandem autologous hematopoietic stem cell transplant. More viral infections were seen in tandem transplant. Day 30 and day 100 mortality was nil.

Conclusion We present data on tandem autologous HSCTs in very young patients with MM in India. Responses continued to improve in this small series.
Distinct Behavior of Traumatic versus Nontraumatic Intracerebral Hematomas: Different Biology or Impact of Age?
Authors: Gousias Konstantinos , Pleger Burkhard , Markou Markella , Grözinger Martin , Sedaghat Sam , Pintea Bogdan , Schildhauer Thomas A. , Martinez Ramon , Hamsen Uwe
Published: June 2021

Background and Study Aims Patients with large intracerebral hematomas (ICH) may demonstrate different demographics and underlying brain and systemic diseases, as well as different radiologic courses and distinct outcomes. It remains unclear whether their different behavior attributes to a different biology of the ICH or to the asymmetric characteristics of the two populations. To analyze and adjust for potential sources of selection and treatment bias, our study compared age-matched patients with traumatic and nontraumatic ICH in a single cohort diagnosed and treated in the same surgical department.

Material and Methods We analyzed 135 consecutive patients with traumatic (n = 90) or spontaneous ICH (n = 45) undergoing treatment at a surgical intensive care unit of an urban university hospital. We documented their differences before and after adjustment for age in terms of demographics, the therapies applied, their radiologic (i.e., volume and rate of ICH expansion [HE]) and clinical (patients' outcome at 30 days) course, the length of hospital and ICU stay, as well as the hospital costs.

Results Patients with traumatic ICH demonstrated more favorable clinical and radiologic characteristics at admission, that is, higher Glasgow Coma Scale score (p < 0.001), less frequently dilated pupil (p = 0.028), lower Charlson Comorbidity Index (p < 0.001), smaller ICH volume (p < 0.001), noneloquent (p < 0.001) or nonintraventricular (p = 0.003) ICH locations, as well as underwent fewer neurosurgical interventions (p < 0.001) and showed a better outcome (p = 0.041), defined as Glasgow Outcome Scale 4 and 5. After adjustment for age, no different outcomes were observed. Of note, elderly patients on novel oral anticoagulants (NOACs) were more likely to develop an HE compared with those on vitamin K antagonists (VKAs, p = 0.05) after traumatic brain injury (TBI) but not after spontaneous ICH.

Conclusion Our data reveal a significant heterogeneity within the traumatic series. Whereas younger patients show an excellent outcome, the elderly population of the traumatic cases demonstrates a poor outcome similar to that of the nontraumatic cohort. HE under NOACs rather than under VKAs is more likely in the elderly after TBI. Larger prospective trials are warranted to elucidate the potential individual underlying molecular mechanisms for the development of an ICH and HE in these diseases.
The Epidemiology behind Pectus Excavatum: Clinical Study and Review of the Literature
Authors: Reinshagen Konrad , Kloth Katja , Klohs Stefan , Bhullar Jasmin , Boettcher Michael , Hempel Maja , Trah Julian
Published: June 2021

Introduction Pectus excavatum (PE) is a funnel-shaped indentation of the sternum and is the most common deformity of the chest wall. It is associated with syndromic diseases but can occur as an isolated form. Familial occurrence is assumed in up to 40% of cases, but large-scale studies are lacking. Most of the data are obtained from case reports which postulate autosomal recessive, dominant with reduced penetrance, X-linked, and multifactorial patterns of inheritance. No monogenetic cause has been identified to date. This study was designed to provide basic information on the epidemiology, family history, and comorbidity for a large cohort of isolated PE and to show that there is an inheritance pattern for PE that indicates a genetic background.

Materials and Methods A retrospective study was done using a paper-based questionnaire for all PE patients attending two specialized centers for chest wall deformities. Patients with isolated PE were included and asked to provide information on family history and comorbidities.

Results Family history was available for 78 patients. A positive family history was found in 42 patients (54%) with a total of 53 affected family members.

Conclusion The described family histories indicate an underlying genetic cause for PE. Identification of the genetic factors may contribute to characterize patients who are at risk of inheriting isolated PE.
Percutaneous Transhepatic Biopsy for Extrahepatic Lesions
Authors: Onishi Yasuyuki , Arai Yasuaki , Sone Miyuki , Sugawara Shunsuke , Itou Chihiro , Kimura Shintaro
Published: June 2021

Purpose The purpose was to assess the diagnostic accuracy and safety of percutaneous transhepatic biopsy for extrahepatic lesions.

Materials and Methods Between January 2008 and December 2019, 26 patients (17 men and 9 women; median age, 60 years) underwent percutaneous transhepatic needle biopsy for extrahepatic lesions at our institution. Transhepatic biopsy was deemed appropriate compared with other biopsy routes or methods (i.e., endoscopic or surgical). The lesions were in the porta hepatis (n = 9), retroperitoneum (n = 6), right adrenal gland (n = 4), right kidney (n = 3), lesser omentum (n = 2), duodenum (n = 1), pleura (n = 1), and inferior vena cava (n = 1). The median maximal diameter of the lesions was 45.5 mm (range, 18–148 mm). Core-needle biopsy was performed in all patients. Eighteen-gauge and 21-G needles were used in 25 and one patient, respectively. Ultrasound was used for biopsy in 21 patients, and CT fluoroscopy was used in five patients. Postbiopsy tract embolization was performed in three patients. Technical success and diagnostic accuracy of the biopsy were evaluated. Complications were recorded using the systemic inflammation response (SIR) criteria.

Results The pathological results of biopsy were carcinoma (n = 10), lymphoma (n = 9), and other diagnoses (n = 7). Technical success was obtained in all patients. The accurate diagnosis was achieved in 24 of the 26 patients (92.3%). A major complication, a bladder tamponade, was observed in one patient (3.8%) after biopsy of a right kidney lesion. A hematoma caused by iatrogenic renal injury likely obstructed the bladder outlet. Minor complications were observed in three patients (11.5%).

Conclusions Percutaneous transhepatic biopsy for extrahepatic lesions is feasible with acceptable safety.
Parents’ Perception on Mobile Phone Usage of Their Children and Knowledge on Its Hazards in Selected Hospital, Mangalore
Authors: Pereira Priya Sweety , Sequera Sonia Karen Liz
Published: June 2021

Introduction Cell phones have achieved a milestone in modern technology where they have become handy to everyone. Advancement taken place in mobile phone technology has enabled its use in online purchasing as well as communication. On one hand, it is a helping tool for faster communication; on other hand, we cannot deny the fact of its harmful effects. The young teens are the age group who have been addicted to the mobiles. It is only the parents who can mould child’s behavior and personality. In this regard, parents can play an important role in enhancing the sense of responsibility in vigilant use of mobile at the early age.

Materials and Methods A quantitative descriptive research design was used in this study to collect data from 340 parents of 12 to 20 years age group who are visiting all the outpatient departments of selected Medical College Hospital, Mangaluru. Data was collected by administering demographic proforma, self-prepared perception checklist, and knowledge questionnaire on hazards of mobile phone usage.

Results Majority 230 (67.6%) parents had generally perceived that their children were spending too much of time on mobile phone and also 187(55%) parents perceived that children use mobile with earphones while traveling and 200(58.8%) parents perceived that their children have become lazy and lost interest in studies too. A total of 210 (61.8%) of parents had inadequate knowledge and 130 (38.2%) of them had adequate knowledge on hazards of mobile usage. There was association between knowledge on hazards of mobile phone usage and selected demographic variables as the p-value computed was found to be significant at 0.05 level of significance. There was no association found between knowledge and gender (0.052).

Conclusion As per the study findings, it was very clear that parents were observing some of the behavioral and emotional changes that were happening in their children. Hence, parents need to be educated and made aware of the possible hazards of mobile usage that may help them to tackle all the childhood issues and help in child’s overall development.
Differences in Postmortem Investigation following Perinatal Death
Authors: Nestander Matthew A. , Berryman Kathryn , Brady Robert , Aden James , Haischer-Rollo Gayle
Published: June 2021

Objective The study aimed to describe the postmortem investigation patterns for perinatal deaths and compare the degree of investigation between stillbirths and early neonatal deaths.

Study Design We conducted a single-center retrospective review of all perinatal deaths from 2011 to 2017. Perinatal death was defined as intrauterine fetal death at ≥20 weeks' gestation, plus neonatal deaths within the first 7 days of life. Rates of postmortem investigation were compared.

Results There were 97 perinatal deaths, with 54 stillbirths (56%) and 43 neonatal deaths (44%). Stillbirths were significantly more likely to receive autopsy (p = 0.013) and postmortem genetic testing (p = 0.0004) when compared with neonatal deaths. Maternal testing was also more likely in stillbirths than neonatal deaths. A total of 32 deaths (33%) had no postmortem evaluation beyond placental pathology.

Conclusion Investigation following perinatal death is more likely in stillbirths than neonatal deaths. Methods to improve postmortem investigation following perinatal death are needed, particularly for neonatal deaths.

Key Points
Transcutaneous Bilirubin Monitoring in Preterm Infants of 23 to 34 Weeks' Gestation
Authors: Weber Jennifer , Vadasz-Chates Nataly , Wade Christine , Micetic Becky , Gerkin Richard , Rao Suma
Published: June 2021

Objective The study aimed to evaluate the validity of transcutaneous bilirubin (TcB) measurements at three sites in premature infants born at 230/7 to 346/7 weeks' gestational age (GA) compared with total serum bilirubin (TSB) measurements.

Study Design A prospective study was conducted at Banner – University Medical Center Phoenix, where informed consent was obtained from the infant's parent or legally authorized representative. Cohort A was comprised of infants 230/7 to 286/7 weeks' GA and Cohort B contained subjects 290/7 to 346/7 weeks' GA. Baseline TSB measurements were collected at approximately 24 hours of life, as the standard of care and the TcB measurements were obtained from the sternum, interscapular, and buttock areas at approximately ± 30 minutes from collection of the TSB. Statistical analysis of measurements including sensitivity, specificity, positive, and negative predictive values, and the area under the receiver operator characteristic curve (AUROC) were performed.

Results A total of 166 infants were included in the study population. Cohort A consisted of 41 subjects and Cohort B contained 125 subjects. The results showed that baseline TcB measurements from the interscapular area were the most sensitive and specific with TSB levels >5.0 mg/dL in Cohort A. Baseline TcB measurements from the sternum demonstrated greatest sensitivity and specificity when the TSB level was >8.0 mg/dL in Cohort B. In general, each of the three sites in both cohorts demonstrated excellent AUROCs and negative predictive values.

Conclusion The use of a TcB meter in preterm infants can be a reliable noninvasive screening tool for hyperbilirubinemia, and it may be beneficial in decreasing painful stimuli and iatrogenic blood loss when used as an adjunct to TSB monitoring.

Key Points
Synthetic multidimensional plasma electron hole equilibria
Authors: Hutchinson I. H.
Published: June 2021

Methods for constructing synthetic multidimensional electron hole equilibria without using particle simulation are investigated. Previous approaches have various limitations and approximations that make them unsuitable within the context of expected velocity diffusion near the trapped-passing boundary. An adjustable model of the distribution function is introduced that avoids unphysical singularities there, and yet it is sufficiently tractable analytically to enable prescription of the potential spatial profiles. It is shown why simple models of the charge density as being a function only of potential cannot give solitary multidimensional electron holes, in contradiction of prior suppositions. Fully self-consistent axisymmetric electron holes in the drift-kinetic limit of electron motion (negligible gyro-radius) are constructed and their properties relevant to observational interpretation and finite-gyro-radius theory are discussed.
Data-driven prediction of multistable systems from sparse measurements
Authors: Chu Bryan , Farazmand Mohammad
Published: June 2021

We develop a data-driven method, based on semi-supervised classification, to predict the asymptotic state of multistable systems when only sparse spatial measurements of the system are feasible. Our method predicts the asymptotic behavior of an observed state by quantifying its proximity to the states in a precomputed library of data. To quantify this proximity, we introduce a sparsity-promoting metric-learning (SPML) optimization, which learns a metric directly from the precomputed data. The optimization problem is designed so that the resulting optimal metric satisfies two important properties: (i) it is compatible with the precomputed library and (ii) it is computable from sparse measurements. We prove that the proposed SPML optimization is convex, its minimizer is non-degenerate, and it is equivariant with respect to the scaling of the constraints. We demonstrate the application of this method on two multistable systems: a reaction–diffusion equation, arising in pattern formation, which has four asymptotically stable steady states, and a FitzHugh–Nagumo model with two asymptotically stable steady states. Classifications of the multistable reaction–diffusion equation based on SPML predict the asymptotic behavior of initial conditions based on two-point measurements with 95% accuracy when a moderate number of labeled data are used. For the FitzHugh–Nagumo, SPML predicts the asymptotic behavior of initial conditions from one-point measurements with 90% accuracy. The learned optimal metric also determines where the measurements need to be made to ensure accurate predictions.
Realization of all logic gates and memory latch in the SC-CNN cell of the simple nonlinear MLC circuit
Authors: Ashokkumar P. , Sathish Aravindh M. , Venkatesan A. , Lakshmanan M.
Published: June 2021

We investigate the State-Controlled Cellular Neural Network framework of Murali–Lakshmanan–Chua circuit system subjected to two logical signals. By exploiting the attractors generated by this circuit in different regions of phase space, we show that the nonlinear circuit is capable of producing all the logic gates, namely, or, and, nor, nand, Ex-or, and Ex-nor gates, available in digital systems. Further, the circuit system emulates three-input gates and Set–Reset flip-flop logic as well. Moreover, all these logical elements and flip-flop are found to be tolerant to noise. These phenomena are also experimentally demonstrated. Thus, our investigation to realize all logic gates and memory latch in a nonlinear circuit system paves the way to replace or complement the existing technology with a limited number of hardware.
Sub-micrometer pyroelectric tomography of AlScN films
Authors: Tappertzhofen S. , Bette S. , Sievers F. , Fichtner S. , Bröker S. , Schmitz-Kempen T.
Published: June 2021

We report on one- to three-dimensional characterization of the pyroelectric properties of aluminum scandium nitride. By means of the laser intensity modulation method, we reconstructed the in-depth distribution of the spontaneous polarization with sub-micrometer resolution. The reconstructed profiles of the spontaneous polarization indicate that the thermal diffusivity and its temperature-dependence differ significantly from what is reported for pure aluminum nitride, which we attribute to the dominant role of phonon-alloy scattering for the heat transfer.
Clustering for epidemics on networks: A geometric approach
Authors: Prasse Bastian , Devriendt Karel , Van Mieghem Piet
Published: June 2021

Infectious diseases typically spread over a contact network with millions of individuals, whose sheer size is a tremendous challenge to analyzing and controlling an epidemic outbreak. For some contact networks, it is possible to group individuals into clusters. A high-level description of the epidemic between a few clusters is considerably simpler than on an individual level. However, to cluster individuals, most studies rely on equitable partitions, a rather restrictive structural property of the contact network. In this work, we focus on Susceptible–Infected–Susceptible (SIS) epidemics, and our contribution is threefold. First, we propose a geometric approach to specify all networks for which an epidemic outbreak simplifies to the interaction of only a few clusters. Second, for the complete graph and any initial viral state vectors, we derive the closed-form solution of the nonlinear differential equations of the N-intertwined mean-field approximation of the SIS process. Third, by relaxing the notion of equitable partitions, we derive low-complexity approximations and bounds for epidemics on arbitrary contact networks. Our results are an important step toward understanding and controlling epidemics on large networks.
An extended model for orifice starting jets
Authors: Limbourg Raphaël , Nedić Jovan
Published: June 2021

Starting jets emanating from a straight nozzle and orifices of different orifice-to-tube diameter ratios are investigated using time-resolved particle image velocimetry. The invariants of the motion, namely, the circulation, the hydrodynamic impulse, and the kinetic energy, are measured and compared to the classic slug-flow model, and this for both fixed exhaust speed and fixed diameter-based Reynolds numbers. An extension to the slug-flow model is proposed to account for the contraction the fluid is experiencing when being pushed out through orifice geometries. The contraction coefficients obtained for two-dimensional jets formed through a slit in a channel are applied to the axisymmetric problem. This modified slug-flow model is shown to better predict the invariants of the motion with discrepancies of the order of 10% compared to underpredictions of 130%, 50%, and 120% for the circulation, the hydrodynamic impulse, and the kinetic energy, respectively, using the classic slug-flow model. Moreover, for a fixed target exhaust speed, the model suggests the existence of a maximum in the production of impulse and energy at an orifice-to-tube diameter ratio of about 0.9, which was also observed experimentally for the kinetic energy. Practically speaking, this suggests that the most efficient way of producing a starting jet is using an orifice plate of ratio close to 1, but different from a straight nozzle. Finally, the overpressure correction of Krueger [“The significance of vortex ring formation and nozzle exit overpressure to pulsatile jet propulsion,” Ph.D. thesis (California Institute of Technology, 2001)] is applied and revisited to account for the orifice-to-tube diameter ratio. Overall, good agreement with the present experimental data is found.
Coherent structure characteristics of the swirling flow during turbulent mixing in a multi-inlet vortex reactor
Authors: Hitimana Emmanuel , Fox Rodney O. , Hill James C. , Olsen Michael G.
Published: June 2021

Improving the efficiency of the production of uniformly sized functional nanoparticles for pharmaceutical and agricultural applications has been a problem of great interest. The macroscale multi-inlet vortex Reactor (macro-MIVR) could potentially be used for this purpose due to its ability to achieve the rapid mixing necessary for the flash nanoprecipitation nanoparticle fabrication technique. In the presented work, the coherent structures, a key contributor to the turbulent mixing, were investigated for the turbulent swirling flow within the MIVR. The two-point spatial correlations of velocity and concentration fluctuations at various basepoints were measured from instantaneous velocity and concentration fields obtained using simultaneous stereoscopic particle image velocimetry and planar laser-induced fluorescence. The basepoint locations were chosen as the middle and at the edge of the partially mixed concentration spiral arms. The correlations were found to be elliptical in shape, inclined, and peaked at the basepoints. A region near the basepoint was positively correlated and was surrounded by negatively correlated regions. Autocorrelations of concentration were also elliptical and curved toward the center of the reactor. The linear stochastic estimation was used to interpret the coherent structure features that would result in the observed spatial correlations. The linear stochastic estimates of the velocity fields were computed directly from the cross correlations of the tangential velocity fluctuations with the concentration fluctuations. The estimated conditional velocity fields revealed obliquely oriented counter-rotating vortical structures that stir the fluid from high-concentration regions to low-concentration regions, and the orientation of these vortical structures depended on the local concentration gradient.
Wall-modeled large-eddy simulation of a trailing-edge serration–finlet configuration
Authors: Shi Yuejun , Kollmann Wolfgang
Published: June 2021

This paper proposes a novel trailing-edge treatment to reduce airfoil self-noise: a serration–finlet configuration. According to the current literature, while serrations are good at reducing low-frequency noise, finlets are able to significantly reduce noise at high frequencies. Therefore, it is possible that their combination can reduce noise at all frequencies. Wall-modeled large-eddy simulations are performed to compare a serration–finlet configuration to a clean airfoil, an airfoil with serrations only, and an airfoil with finlets only. It is shown that the serration–finlet configuration reduces the far-field overall sound pressure level by 20.2 dB and has an improved aerodynamic performance. The detailed flow physics of noise reduction with the serration–finlet configuration is also investigated. It is found that the serration–finlet configuration remarkably reduces far-field noise by improving the hydrodynamic field at source locations. In particular, near-wall velocity and turbulence kinetic energy are reduced. Large coherent eddies are also broken into smaller turbulent structures. The interactions between serrations and finlets are proven to be beneficial from both aerodynamic and aeroacoustic perspectives. Overall, the current research provides a low-noise solution for wind turbines and the future’s ultra-quiet aircraft.
Accuracy of the time-averaged ponderomotive approximation for laser-plasma accelerator modeling
Authors: Terzani D. , Benedetti C. , Schroeder C. B. , Esarey E.
Published: June 2021

Reliable modeling of laser-plasma accelerators, where a short and intense laser pulse propagates in an underdense plasma over long distances, is a computationally challenging task. This is due to the great disparity among the scales involved in the modeling, ranging from the micrometer scale of the laser wavelength to, for instance, the meter scale of the laser-plasma interaction length for a multi-GeV-class laser-plasma accelerator. To reduce such imbalance, the time-averaged ponderomotive approximation may be used, where the plasma particle dynamics is analytically averaged over the laser frequency, and only spatiotemporal scales associated with the laser envelope are retained in the calculations, resulting in significant computational savings. In this paper, we characterize the accuracy and robustness of the time-averaged ponderomotive approximation for a range of laser parameters of interest for present and future laser-plasma accelerators, and we show that the error introduced by the averaging process is small in all relevant cases.
Non-invasive acquisition of mechanical properties of cells via passive microfluidic mechanisms: A review
Authors: Li Zhenghua , Yang Xieliu , Zhang Qi , Yang Wenguang , Zhang Hemin , Liu Lianqing , Liang Wenfeng
Published: June 2021

The demand to understand the mechanical properties of cells from biomedical, bioengineering, and clinical diagnostic fields has given rise to a variety of research studies. In this context, how to use lab-on-a-chip devices to achieve accurate, high-throughput, and non-invasive acquisition of the mechanical properties of cells has become the focus of many studies. Accordingly, we present a comprehensive review of the development of the measurement of mechanical properties of cells using passive microfluidic mechanisms, including constriction channel-based, fluid-induced, and micropipette aspiration-based mechanisms. This review discusses how these mechanisms work to determine the mechanical properties of the cell as well as their advantages and disadvantages. A detailed discussion is also presented on a series of typical applications of these three mechanisms to measure the mechanical properties of cells. At the end of this article, the current challenges and future prospects of these mechanisms are demonstrated, which will help guide researchers who are interested to get into this area of research. Our conclusion is that these passive microfluidic mechanisms will offer more preferences for the development of lab-on-a-chip technologies and hold great potential for advancing biomedical and bioengineering research studies.
Flexoelectric electricity generation by crumpling graphene
Authors: Javvaji Brahmanandam , Zhang Ranran , Zhuang Xiaoying , Park Harold S.
Published: June 2021

We utilize atomistic simulations that account for point charges and dipoles to demonstrate that flexoelectricity, which arises from strain gradients, can be exploited to generate electricity from crumpled graphene sheets. Indentation of a circular graphene sheet generates localized developable (d)-cones, for which we verify the core radius and azimuthal angle with established theoretical models. We determine the voltage that can be generated based on the resulting electrostatic fields and compare the voltage generation to previous theoretical predictions that are scaled down to the nanoscale. In doing so, we find that the voltage generated from crumpling graphene exceeds, by about an order of magnitude, the expected voltage generation, indicating the benefit of exploiting the large strain gradients that are possible at the nanoscale. Finally, we demonstrate that crumpling may be a superior mechanism of flexoelectric energy generation as compared to bending of two-dimensional nanomaterials.
Phase of particle-level velocity perturbations determines the fate of Rayleigh–Bénard convection cells in 2D Yukawa liquids
Authors: Kaur Pawandeep , Ganesh Rajaraman
Published: June 2021

Using “first principles” molecular dynamics (MD) simulations, the sensitivity of two-dimensional Rayleigh–Bénard convection cells (RBCCs) to the phase and amplitude of particle-level velocity perturbations is demonstrated in strongly coupled Yukawa liquids. We find that RBCCs are retained only for “odd” phase values of particle-level velocity perturbations, whereas, for “even” phase values, RBCCs undergo transition to a horizontal shear flow, which eventually evolves to a horizontal shearless parallel flow. The parallel macroscale flow grows algebraically before saturation, and the growth rate itself is found to increase with the amplitude of the perturbation. The fluid enstrophy as a function of time constructed from MD data shows the existence of a credible minimization mechanism under play, for such transitions.
Reduction of surface roughness emittance of Cs3Sb photocathodes grown via codeposition on single crystal substrates
Authors: Galdi Alice , Balajka Jan , DeBenedetti William J. I. , Cultrera Luca , Bazarov Ivan V. , Hines Melissa A. , Maxson Jared M.
Published: June 2021

Alkali antimonide photocathodes are capable of generating high brightness electron beams given their high quantum efficiency and low mean transverse energy (MTE). Increasing the brightness of the photoemitted electron beams beyond the current state of the art requires surface control of the photocathode at the atomic scale, since the beam brightness at the cathode is degraded by a rough, inhomogeneous surface. In this work, we grow cesium antimonide photocathodes on single crystal substrates (Al2O3, TiO2, 3C–SiC, and a control sample on Si) and study the resulting surface morphology with scanning tunneling microscopy (STM). We observe dramatic changes in surface morphology across substrates. In particular, we demonstrate 10 times larger island size and significantly reduced roughness on two samples grown on 3C–SiC(100) substrates as compared to samples on other substrates. By computing the local electric fields which these surfaces would generate in an electron accelerator source, we estimate the roughness-induced contribution to MTE. Across samples, the calculated contribution to MTE varies by a factor of 17, and the smallest value computed is 12 meV at an extraction field of 50 MV/m, which is smaller than typical values for alkali antimonides. Additionally, we show that oxidation, commonly encountered in vacuum transfer and in accelerator operation, does not affect the measured surface morphology. Our findings suggest that even in high field environments, the brightness of the photocathodes grown on 3C–SiC will be primarily determined by the material's electronic properties rather than by spurious fields generated by photocathode roughness.
Anomalously low friction of confined monolayer water with a quadrilateral structure
Authors: Li JinChuan , Zhu YinBo , Xia Jun , Fan JingCun , Wu HengAn , Wang FengChao
Published: June 2021

In this work, we explored how the structure of monolayer water confined between two graphene sheets is coupled to its dynamic behavior. Our molecular dynamics simulations show that there is a remarkable interrelation between the friction of confined water with two walls and its structure under extreme confinement. When the water molecules formed a regular quadrilateral structure, the friction coefficient is dramatically reduced. Such a low-friction coefficient can be attributed to the formation of long-range ordered hydrogen bond network, which not only decreases the structure corrugation in the direction perpendicular to the walls but also promotes the collective motion of the confined water. The regular quadrilateral structure can be formed only if the number density of confined water falls within a certain range. Higher number density results in larger structure corrugations, which increases the friction, while smaller number density leads to an irregular hydrogen bond network in which the collective motion cannot play the role. We demonstrated that there are four distinct stages in the diagram of the friction coefficient vs the number density of confined water. This research clearly established the connection between the dynamic characteristics of confined monolayer water and its structure, which is beneficial to further understand the mechanism of the high-speed water flow through graphene nanocapillaries observed in recent experiments.
Formation of quasi-two-dimensional electron gas at the interface of ZnO/Ga2O3 heterostructure
Authors: Lu Hongliang , Liu Kai , Ma Hongping , Zhao Xuefeng , Zhang David Wei , Liu Yuhang
Published: June 2021

A two-dimensional electron gas (2DEG) was formed at the interface of an ultrathin ZnO/Ga2O3 heterostructure deposited by atomic layer deposition (ALD) at 200 °C on a SiO2/Si substrate. It is found that the sheet resistance decreases steeply to ∼104 Ω/□ as the thickness of the ZnO layer increases to a certain extent, and an optimal thickness of the top layer is determined. An ∼50-nm-thick β-phase Ga2O3 layer was formed after annealing at 800 °C, and a 12-nm-thick amorphous ZnO layer was observed by x-ray diffraction and transmission electron microscopy. The oxygen defects were analyzed by x-ray photoelectron spectroscopy. The defect energy levels of oxygen vacancies in Ga2O3 and ZnO thin films were calculated by first-principles simulation, and oxygen vacancies were generated at the interface of the ZnO/Ga2O3 thin film heterostructure to form 2DEG, which is demonstrated experimentally and theoretically. An assumption is proposed that the oxygen vacancy plays a role of the donor of free electrons at the ZnO/Ga2O3 interface because of the small energy level between the oxygen vacancy defect level and conduction band minimum (CBM) of the ZnO layer, which could easily trigger the charge transfer in the interface region. The 2DEG can be realized on the partially ordered microstructure of the Ga2O3 layer. With the assistance of the ALD technique, the thickness of the ZnO/Ga2O3 heterostructure can be as thin as ∼65 nm, which is favorable for devices of stack or ultrathin structures. Moreover, the low temperature deposition by ALD can be adopted for flexible or stretchable devices.
Oscillatory extensional flow based on eccentric cylinder flow
Authors: Liang Xianrong , Cai Wulei , Chen Honghui , Zhao Yunfeng , Wu Heng , Wang Mengmeng , Jin Gang
Published: June 2021

At present, researching the dynamics of dispersed phases generally uses simple shear flows, simple extensional flows, and oscillatory shear flows rather than an oscillatory extensional flow because it is more difficult to experimentally implement. In this research, a method to generate the oscillatory extensional flow using an eccentric cylinder flow was proposed. Although the eccentric cylinder flow is a shear-extensional complex flow, the shear flow in specific regions of the flow field is very weak when the inner and outer cylinders co-rotate at a particular angular velocity ratio, and only the extensional flow remains. Therefore, the oscillatory extensional flow can be generated in this region when cylinders oscillate at this angular velocity ratio. Larger eccentric and radius ratios are suitable to generate an oscillatory extensional flow with high frequency, and the amplitude can be controlled by the angular velocity of cylinders. This flow field is promising to be a rheological tool for investigating the effects of extensional flows on dispersion dynamics.
The ecology of a translocated population of a medium-sized marsupial in an urban vegetation remnant
Authors: Tomlinson Sean , Smit Anthony , Bateman P. W.
Published: June 2021

Although urbanisation can result in habitat loss, some species persist within urban vegetation remnants. Due to urban development, these species are often the targets of mitigation translocation; for example, the Quenda (Isoodon fusciventer, Marsupialia, Peramelidae), native to southwestern Australia. We assessed the foraging patterns and habitat preferences of a population of Quenda recently introduced by unknown agents to Kings Park, a large urban bushland remnant. Quenda foraged actively throughout our study area, but foraged most intensively in dense, low vegetation, with a significant preference for communities dominated by Banksia sessilis. This study joins other literature indicating that Quenda are able to persist in modified urban vegetation remnants despite the presence of predators, and human activity. Given the Quenda’s clear adaptability to introduction into this urban remnant, we suggest that the greatest threat to continued persistence of urban populations of this species within remnants is likely to relate to difficulties in dispersing through surrounding urban areas. Nevertheless, the successful return of Quenda to a site that has traditionally been discounted from translocation programs suggests that other reserves in the region could also host introductions. Further research is required to determine whether Quenda can disperse through the surrounding suburbs, and whether it is possible to modify novel habitats to support Quenda populations within urban areas. Additionally, further research on facilitating dispersal through managing meta-populations in urban areas is required. Nevertheless, Quenda have successfully established at Kings Park, surrounded by dense urban areas. With ongoing management, urban remnants may be useful in Australia’s protected area network.
Helicobacter pylori’s historical journey through Siberia and the Americas
Authors: Moodley Yoshan , Brunelli Andrea , Ghirotto Silvia , Klyubin Andrey , Maady Ayas S. , Tyne William , Muñoz-Ramirez Zilia Y. , Zhou Zhemin , Manica Andrea , Linz Bodo , Achtman Mark
Published: June 2021

Significance

The peopling of Siberia and the Americas is intriguing for archaeologists, linguists, and human geneticists, but despite significant recent developments, many details remain controversial. Here, we provide insights based on genetic diversity withinHelicobacter pylori, a bacterium that infects 50% of all humans.H. pyloristrains were collected from across eastern Eurasia and the Americas. Sequence analyses indicated that Siberia contains both anciently diverged and recently admixed bacteria, supporting both human persistence over the last glacial maximum and more recent human recolonization. We inferred a single migration across the Bering land bridge, accompanied by a dramatic reduction in effective population size, followed by bidirectional Holocene gene flow between Asia and the Americas.
Functional compartmentalization and metabolic separation in a prokaryotic cell
Authors: Flechsler Jennifer , Heimerl Thomas , Huber Harald , Rachel Reinhard , Berg Ivan A.
Published: June 2021

Significance

In a typical prokaryotic cell, hundreds of metabolites are present and interconverted simultaneously, some serving as allosteric regulators for unrelated reactions or accidental substrates for promiscuous enzymes or being downright reactive and toxic. Although certain spatial separation of prokaryotic cells has long been proposed, only few examples are known. In many bacteria, the key carboxylase of the Calvin–Benson cycle is located in carboxysomes to concentrate CO
2
and deplete O
2
, while other enzymes of the cycle are in the cytoplasm. The archaeon
Ignicoccus hospitalis
exhibits a two-membrane structure with an energized outer membrane. Here, we show that CO
2
fixation in this organism takes place in a peripheric cytoplasmic compartment, being separated from information processing occurring in the central cytoplasmic compartment.
Monocarboxylate transporter antagonism reveals metabolic vulnerabilities of viral-driven lymphomas
Authors: Bonglack Emmanuela N. , Messinger Joshua E. , Cable Jana M. , Ch’ng James , Parnell K. Mark , Reinoso-Vizcaíno Nicolás M. , Barry Ashley P. , Russell Veronica S. , Dave Sandeep S. , Christofk Heather R. , Luftig Micah A.
Published: June 2021

Significance

Epstein–Barr virus (EBV) infects virtually every human by adulthood with limited symptoms. However, in the context of immune suppression, EBV can cause lymphomas. EBV-associated lymphomas have poor prognoses and limited treatment options, highlighting a need to better understand EBV-mediated tumorigenesis. One common feature of viral replication and cancer is dysregulation of metabolism. Indeed, EBV dramatically reprograms host cell metabolism, up-regulating both oxidative phosphorylation and glycolysis. In this report, we identify metabolic vulnerabilities of EBV-infected primary human B cells, EBV-positive lymphomas, and lymphomas caused by the related oncogenic herpesvirus, KSHV. Pharmacological inhibition of lactate export suppressed these lymphomas and rendered them hypersensitive to metformin and phenformin. These findings together with our mechanistic studies outline a therapeutic strategy for viral lymphomas.
Potency boost of a
Mycobacterium tuberculosis
dihydrofolate reductase inhibitor by multienzyme F
420
H
2
-dependent reduction
Authors: Aragaw Wassihun Wedajo , Lee Brendon M. , Yang Xuan , Zimmerman Matthew D. , Gengenbacher Martin , Dartois Véronique , Chui Wai-Keung , Jackson Colin J. , Dick Thomas
Published: June 2021

Significance

Bacterial metabolism can cause intrinsic drug resistance but can also convert inactive parent drugs into bioactive derivatives, as is the case for several antimycobacterial prodrugs. Here, we show that the intrabacterial metabolism of a Mtb dihydrofolate reductase (DHFR) inhibitor with moderate affinity for its target boosts its on-target activity by two orders of magnitude. This is a “prodrug-like” antimycobacterial that possesses baseline activity in the absence of intracellular bioactivation. By elucidating the metabolic enhancement mechanism, we have provided the basis for the rational optimization of a class of DHFR inhibitors and uncovered an antibacterial drug discovery concept.
Unaccounted CO
2
leaks downstream of a large tropical hydroelectric reservoir
Authors: Calamita Elisa , Siviglia Annunziato , Gettel Gretchen M. , Franca Mário J. , Winton R. Scott , Teodoru Cristian R. , Schmid Martin , Wehrli Bernhard
Published: June 2021

Significance

Hydroelectric reservoirs emit substantial amounts of CO
2
, especially in the tropics. Since many such systems exist and many more will be built within decades, it is important to assess their role in the carbon cycle. A major source of emission that is rarely monitored and never at different timescales is the carbon released downstream of dams. We measured the seasonal and subdaily variability of CO
2
emission downstream of one of the world’s largest artificial reservoirs and find that its contribution is relevant for unbiased quantification of reservoir carbon budgets. These findings highlight the importance of subdaily variability in hydropower operation for downstream emission rates and call for appropriate analysis schemes to reassess the greenhouse gas footprint of this energy source.
Computational modeling of ovarian cancer dynamics suggests optimal strategies for therapy and screening
Authors: Gu Shengqing , Lheureux Stephanie , Sayad Azin , Cybulska Paulina , Hogen Liat , Vyarvelska Iryna , Tu Dongsheng , Parulekar Wendy R. , Nankivell Matthew , Kehoe Sean , Chi Dennis S. , Levine Douglas A. , Bernardini Marcus Q. , Rosen Barry , Oza Amit , Brown Myles , Neel Benjamin G.
Published: June 2021

Significance

The optimal timing of surgery/chemotherapy and the benefits of earlier diagnosis of HGSC remain controversial. We developed a mathematical framework of tumor dynamics, populated the model with primary clinical data, and reliably recapitulated clinical observations. Our model predicts that 1) PDS is superior to NACT with relatively small tumor burden and when complete debulking is feasible, 2) timely adjuvant chemotherapy is critical for the outcome of PDS with <1-mm residual tumors, 3) earlier detection of relapse is unlikely beneficial with current therapies, and 4) earlier detection of primary HGSC could have substantial benefit. These results provide insights into the evolutionary dynamics of HGSC, argue for new clinical trials to optimize therapy, and are potentially applicable to other tumor types.