Evaluation of registration methods on thoracic CT: the EMPIRE10 challenge

EMPIRE10 (Evaluation of Methods for Pulmonary Image REgistration 2010) is a public platform for fair and meaningful comparison of registration algorithms which are applied to a database of intrapatient thoracic CT image pairs. Evaluation of nonrigid registration techniques is a nontrivial task. This is compounded by the fact that researchers typically test only on their own data, which varies widely. For this reason, reliable assessment and comparison of different registration algorithms has been virtually impossible in the past. In this work we present the results of the launch phase of EMPIRE10, which comprised the comprehensive evaluation and comparison of 20 individual algorithms from leading academic and industrial research groups. All algorithms are applied to the same set of 30 thoracic CT pairs. Algorithm settings and parameters are chosen by researchers expert in the configuration of their own method and the evaluation is independent, using the same criteria for all participants. All results are published on the EMPIRE10 website (http://empire10.isi.uu.nl). The challenge remains ongoing and open to new participants. Full results from 24 algorithms have been published at the time of writing. This paper details the organization of the challenge, the data and evaluation methods and the outcome of the initial launch with 20 algorithms. The gain in knowledge and future work are discussed.     

Electrophysiological imaging of brain activity and connectivity-challenges and opportunities

Unlocking the dynamic inner workings of the brain continues to remain a grand challenge of the 21st century. To this end, functional neuroimaging modalities represent an outstanding approach to better understand the mechanisms of both normal and abnormal brain functions. The ability to image brain function with ever increasing spatial and temporal resolution has made a significant leap over the past several decades. Further delineation of functional networks could lead to improved understanding of brain function in both normal and diseased states. This paper reviews recent advancements and current challenges in dynamic functional neuroimaging techniques, including electrophysiological source imaging, multimodal neuroimaging integrating fMRI with EEG/MEG, and functional connectivity imaging.     

Charge‐Generating Mode Control in High‐Performance Transparent Flexible Piezoelectric Nanogenerators

In this work, we demonstrate the mode transition of charge generation between direct‐current (DC) and alternating‐current (AC) from transparent flexible (TF) piezoelectric nanogenerators (NGs), which is dependent solely on the morphology of zinc oxide (ZnO) nanorods without any use of an AC/DC converter. Tilted ZnO nanorods grown on a relatively low‐density seed layer generate DC‐type piezoelectric charges under a pushing load, whereas vertically aligned ZnO nanorods on a relatively high‐density seed layer create AC‐type charge generation. The mechanism for the geometry‐induced mode transition is proposed and characterized. We also examine the output performance of TF‐NGs which employ an indium zinc tin oxide (IZTO) film as a TF electrode. It is demonstrated that an IZTO film has improved electrical, optical, and mechanical properties, in comparison with an indium tin oxide (ITO) film. Enhanced output charge generation is observed from IZTO‐based TF‐NGs when TF‐NGs composed of only ITO electrodes are compared. This is attributed to the higher Schottky barrier and the lower series resistance of the IZTO‐based TF‐NGs. Thus, by using IZTO, we can expect TF‐NGs with superior mechanical durability and power generating performance.     

Engineering 2D Arsenic-Phosphorus Theranostic Nanosheets

As an anticancer drugs, arsenic trioxide (ATO) has been certified to efficiently treat refractory acute promyelocytic leukemia (APL). Unfortunately it suffers from limited therapeutic potency for solid tumors due to its in vivo restricted administration dose and rapid renal clearance. Herein, distinct 2D arsenic-phosphorus (AsP) nanosheets are engineered by adopting an alloy strategy followed by exfoliation, which can confine toxic arsenic into AsP crystals, thus significantly improving the biosafety and biocompatibility of arsenic-based chemotherapeutic drugs. Of particular note, the high light absorption and strong photothermal-conversion efficiency (37.6%) in the second near infrared biowindow (NIR-II) of AsP nanosheets not only endow them with desirable contrast-enhanced photoacoustic imaging properties, but also achieve efficient local tumor hyperthermia, which further synergistically triggers the in-situ transformation from low toxic/nontoxic AsP crystals into highly toxic arsenic species, exerting a strong arsenic-mediated antineoplastic effect. Both in vitro and in vivo data verify the synergy between photonic therapy in NIR-II and enhanced chemotherapy as enabled by AsP nanosheets, paving the way for efficient nanomedicine-enabled arsenic-based chemotherapeutic tumor treatment.     

Immunoregulation of Macrophages by Controlling Winding and Unwinding of Nanohelical Ligands

Developing materials with the capability of changing their innate features can help to unravel direct interactions between cells and ligand-displaying features. This study demonstrates the grafting of magnetic nanohelices displaying cell-adhesive Arg-Gly-Asp (RGD) ligand partly to a material surface. These enable nanoscale control of rapid winding (“W”) and unwinding (“UW”) of their nongrafted portion, such as directional changes in nanohelix unwinding (lower, middle, and upper directions) by changing the position of a permanent magnet while keeping the ligand-conjugated nanohelix surface area constant. The unwinding (“UW”) setting cytocompatibility facilitates direct integrin recruitment onto the ligand-conjugated nanohelix to mediate the development of paxillin adhesion assemblies of macrophages that stimulate M2 polarization using glass and silicon substrates for in vitro and in vivo settings, respectively, at a single cell level. Real time and in vivo imaging are demonstrated that nanohelices exhibit reversible unwinding, winding, and unwinding settings, which modulate time-resolved adhesion and polarization of macrophages. It is envisaged that this remote, reversible, and cytocompatible control can help to elucidate molecular-level cell–material interactions that modulate regenerative/anti-inflammatory immune responses to implants.     

Stable Radicals with Protective Umbrellas Integrated on the Surface of 2D Layered Materials

Radicals are closely related to human life and health and have been widely used in biology, chemistry, functional materials, etc. However, the high reactivity, disorder, and short half-lives limit their wide applications. Therefore, it remains a great challenge to prepare stable and ordered radicals. Herein, radicals are prepared with protective umbrellas (diethylmethyleneamine, DEMA) that are integrated on the surface of 2D layered materials to isolate water and oxygen and enhance the stability of radicals. Taking 2D black phosphorus (BP) as an example: triethylamine reacts with dichloromethane to form quaternary ammonium salts with further Hoffmann elimination to produce DEMA radicals that could react with one electron of a lone pair electrons in P on the surface of BP to produce P radicals, which shows a prolonged half-life of 21 days at room temperature. First-principle calculations and electron paramagnetic resonance fitting confirm that the steric hindrance constructed by dense DEMA passivation layer acts as a protective umbrella and the 2D coupling of P radicals and other P atoms in 2D BP plane to enhance the stability and strong superexchange interaction of P radicals. Furthermore, it is a general strategy to produce stable radicals integrated on the 2D plane.     

Retina-Inspired Structurally Tunable Synaptic Perovskite Nanocones

Artificial photonic synapses with morphologically controlled photoreception, allowing for area-dependent tunable light reception as well as information storage and learning, have potential for application in emerging photo-interactive neuro-computing technologies. Herein, an artificially intelligent (AI) photonic synapse with area-density-tunable perovskite nano-cone arrays templated in a self-assembled block copolymer (BCP) is presented, which is based on a field effect transistor with a floating gate of photoreceptive perovskite crystal arrays preferentially synthesized in a micro-phase-segregated BCP film. These arrays are capable of electric charge (de)trapping and photo-excited charge generation, and they exhibit versatile synaptic functions of the nervous system, including paired-pulse facilitation and long-term potentiation, with excellent reliability. The area-density variable perovskite floating gate developed by off-centered spin coating process allows for emulating the human retina with a position-dependent spatial distribution of cones. 60 × 12 arrays of the developed synapse devices exhibit position-dependent dual functions of receptor and synapse. They are AI and exhibit a pattern recognition accuracy up to ≈90% when examined using the Modified National Institute of Standards and Technology handwritten digit pattern recognition test.     

Balancing Intermolecular Interactions between Acceptors and Donor/Acceptor for Efficient Organic Photovoltaics

Promoted by uninterrupted materials and device innovation, organic solar cells have achieved impressive development. However, the complicated intermolecular interactions inside active layers are less understood. Herein, the intermolecular interactions are studied from the dual perspectives of acceptor/acceptor (A/A) and donor/acceptor (D/A), and how these interactions synergistically control the final efficiencies. Three small molecular acceptors (SMAs) are designed with different end-caps, which manipulate the crystallinity and electrostatic potential (ESP) distributions of acceptors, and accordingly, the A/A and D/A intermolecular interactions. The results show that SMA LA17 with low A/A interactions exhibits inferior performance around 12%, owing to its strong D/A interaction with donor PM6, which shapes too miscible morphology and increases charge recombination. Instead, LA16 with strong A/A interactions and moderate D/A interactions delivers improved bulk-heterojunction (BHJ) networks, and therefore, enhances charge transport and diminishes geminate or trap-assisted charge recombination. Consequently, PM6:LA16 records the competitive efficiency of up to 13.74% among the three systems. Therefore, this study deepens the synergistic or balancing effect of the D/A and A/A interactions on BHJ blends for efficient organic solar cells.     

Effect of 1,2,4-triazole on galvanic corrosion between cobalt and copper in CMP based alkaline slurry

Cobalt has become a new type of barrier material with its unique advantages since the copper-interconnects in the great-large scale integrated circuits (GLSI) into 10 nm and below technical nodes,but cobalt and copper have severe galvanic corrosion during chemical-mechanical flattening.The effect of 1,2,4-triazole on Co/Cu galvanic corrosion in alkaline slurry and the control of rate selectivity of copper and cobalt were investigated in this work.The results of electrochemical experiments and polishing experiments had indicated that a certain concentration of 1,2,4-triazole could form a layer of insoluble and dense passive film on the surface of cobalt and copper,which reduced the corrosion potential difference between cobalt and copper.Meantime,the removal rate of cobalt and copper could be effectively controlled according to demand during the CMP process.When the study optimized slurry was composed of 0.5 wt％ colloidal silica,0.1％vol.hydrogen peroxide,0.05 wt％ FA/O,345 ppm 1,2,4-triazole,cobalt had higher corrosion potential than copper and the galvanic corrosion could be reduced effectively when the corrosion potential difference between them decreased to 1 mV and the galvanic corrosion current density reached 0.02 nA/cm2.Meanwhile,the removal rate of Co was 62.396 nrn/min,the removal rate of Cu was 47.328 nm/min,so that the removal rate ratio of cobalt and copper was 1.32:1,which was a good amendment to the dishing pits.The contact potential corrosion of Co/Cu was very weak,which could be better for meeting the requirements of the barrier CMP.     

面向VR应用的花卉植物物理渲染技术研究与实现

花卉植物高真实感的仿真交互是目前虚拟植物可视化研究的一个重要方向。随着虚拟现实技术的普及,越来越多的应用采用了VR头戴设备的呈现方式。VR系统需要高度真实的沉浸感画面,通用的植物建模和图形引擎渲染功能已不能满足该需求。该文通过分析光照原理并融合基于物理的渲染技术,提出基于双向散射分布函数BSDF的花卉植物高度真实感的物理渲染算法,利用ShaderLab,对几种盆栽花卉植物在光照下进行仿真,并对融合算法做优化处理。针对VR头盔设备HTC Vive的成像效果,对图像进行扭曲变形优化,使画面更符合人眼双目立体视觉成像效果,增强系统沉浸感。最后基于该方法设计并实现了一个头盔式VR花卉植物仿真模拟系统,获得了逼真的场景漫游体验效果。