Xiaoyuan Chen

Bio: Xiaoyuan Chen is an academic researcher from National University of Singapore. The author has contributed to research in topics: Physics & Photothermal therapy. The author has an hindex of 149, co-authored 994 publications receiving 89870 citations. Previous affiliations of Xiaoyuan Chen include Brown University & University of Southern California.

Precise Measurements of Decay Parameters and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>C</mml:mi><mml:mi>P</mml:mi></mml:math> Asymmetry with Entangled <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="

Abstract: Based on 10 billion J/ψ events collected at the BESIII experiment, a search for CP violation in Λ decay is performed in the difference between CP-odd decay parameters α− for Λ→pπ− and α+ for Λ¯→p¯π+ by using the process e+e−→J/ψ→ΛΛ¯. With a five-dimensional fit to the full angular distributions of the daughter baryon, the most precise values for the decay parameters are determined to be α−=0.7519±0.0036±0.0024 and α+=−0.7559±0.0036±0.0030, respectively. The Λ and Λ¯ averaged value of the decay parameter is extracted to be αavg=0.7542±0.0010±0.0024 with unprecedented accuracy. The CP asymmetry ACP=(α−+α+)/(α−−α+) is determined to be −0.0025±0.0046±0.0012, which is one of the most precise measurements in the baryon sector. The reported results for the decay parameter will play an important role in the studies of the polarizations and CP violations for the strange, charmed and beauty baryons.Received 26 April 2022Accepted 1 September 2022DOI:https://doi.org/10.1103/PhysRevLett.129.131801Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasHadronic decaysPhysical SystemsHyperonsPropertiesCP violationPolarizationGeneral PhysicsParticles & Fields

Imaging of angiogenesis: from morphology to molecules and from bench to bedside

Abstract: Angiogenesis is one of the hallmarks of cancer and is increasingly in the focus of oncological research. Judah Folkman first articulated the importance of angiogenesis for tumor growth in 1971 [1]. He stated that the growth of solid tumors remains restricted to 2–3 mm in diameter until the onset of angiogenesis. Although this hypothesis first was strongly criticized, angiogenesis soon became one of the most important fields of research in oncology. Up to now, subsequent investigations have identified more than 20 angiogenic growth factors, their receptors and signal transduction pathways. Moreover, endogenous angiogenesis inhibitors have been discovered, and the cellular and molecular characterization of the angiogenic phenotype in human cancers has been achieved [2, 3]. Although the results of the first clinical trials using angiogenesis inhibitors in oncology were disappointing, encouraging results have been achieved in the past few years with the vascular endothelial growth factor (VEGF) antibody Avastin® in combination with standard cytotoxic chemotherapy. This combined antiangiogenic-cytotoxic therapy has been proven to be successful first in metastasized colorectal cancer, and subsequently also in breast cancer and non-small cell lung cancer [4–7]. This success of targeted antiangiogenic therapy will spur the demand for imaging modalities for assessment of the angiogenic cascade, which is the topic of this supplement “Imaging of Angiogenesis.” Imaging of angiogenic activity might on the one hand help in the process of developing novel antiangiogenic drugs in the preclinical setting. Moreover, in the clinical setting, imaging of angiogenesis might be useful for assessment of the optimum dose of new antiangiogenic agents and for early response evaluation. Up to now, clinical trials with conventional cytotoxic chemotherapeutic agents have mainly used morphological imaging to provide indices of therapeutic response, mostly computed tomography (CT) or magnetic resonance imaging (MRI). Bidimensional measurements of the maximum tumor extension are mainly used to estimate changes in response to the investigational therapy as compared with a baseline measure. Through standardization of these measurements by introducing the RECIST criteria in the year 2000, considerable progress has been achieved [8]. However, as antiangiogenic agents lead to a stop of tumor progression rather than to tumor shrinkage, the approach of measuring tumor response by a reduction of tumor size is not applicable and might take months or years to become apparent. Therefore, there is great interest in identifying reliable biomarkers of early tumor response to non-cytotoxic drugs [9]. Imaging techniques could potentially be used as such a biomarker and could provide an early indicator of effectiveness at a functional or molecular level. Concerning morphological imaging of the vasculature, conventional X-ray angiography and digital subtraction angiography (DSA) are widely used in the clinical arena; however, they do not allow for assessment of the microvasculature and thus are not commonly used for response evaluation of antiangiogenic therapies. More promising is the assessment of changes in hemodynamic parameters such as blood flow, blood volume, or vessel permeability. They may be effective biomarkers for response evaluation, because antiangiogenic therapies are designed to affect the abnormal blood vessels found in tumors. Current clinical trials employ various imaging techniques for this purpose, mostly dynamic contrast-enhanced MRI (DCE MRI), and less often ultrasound, PET (especially with [15O] water), and dynamic contrast-enhanced CT (DCE CT) [10]. In the future, targeting specific molecular markers of angiogenesis might also be used for response assessment of antiangiogenic therapies like the VEGF pathway or cell surface markers like the integrin αvβ3.

Temporal-spatially transformed synthesis and formation mechanism of gold bellflowers.

Abstract: Anisotropic gold nanostructures with unique plasmonic properties, specifically the strong absorption of light in the near-infrared region (650-900 nm) due to the excitation of plasmon oscillations, have been widely employed as photothermal conversion agents (PTCAs) for cancer photothermal therapy (PTT). However, the reported PTCAs show suboptimal photothermal conversion efficiency (η), even gold nanocages (η = 63%), which limits their biomedical applications. Herein, we fabricated gold bellflowers (GBFs) with an ultrahigh photothermal conversion efficiency (η = 74%) via a novel liquid/liquid/gas triphasic interface system, using chloroauric acid as a gold source, and o-phenetidine as a reducing agent. The well-defined GBFs with multiple-branched petals show adjustable localized surface plasmon resonance (LSPR) from 760 to 1100 nm by tuning the petal length and circular bottom diameter. Originating from the monophasic and biphasic systems used in the creation of gold nanourchins (GNUs) and gold microspheres (GMPs) respectively, the triphasic interface system successfully produced GBFs. The possible formation mechanisms of GNUs, GMPs, and GBFs in the different systems were also investigated and discussed. We found that the formation mechanism of GNUs and GBFs followed classical crystallization, while the formation of GMPs followed non-classical crystallization.

Polyphenol-based nanoplatform for MRI/PET dual-modality imaging guided effective combination chemotherapy.

Abstract: Combination therapy with multiple chemotherapeutic agents is the main approach for cancer treatment in the clinic. Polyphenol-based materials are found in our diet, demonstrate good biocompatibility, and prevent numerous diseases. In this study, we encapsulate two drugs in a single polyphenol-based polymer with Fe3+ or Mn2+ ions as the cross-linker for cancer therapy. The combination index of two drugs is an essential parameter to evaluate drug combinations. The amphiphilic polymer poly(ethylene glycol)-block-polydopamine (PEG–PDA) was prepared by RAFT polymerization. The nanoparticles were prepared via self-assembly with Fe3+ or Mn2+ ions. Both doxorubicin (DOX) and simvastatin (SV) were encapsulated in the core of the nanoparticles. The cell viability and combination index were evaluated in vitro. The tumor accumulation of the nanoparticles was investigated by positron-emission tomography (PET) and magnetic resonance (MR) imaging. The as-prepared nanoparticles exhibited high drug loading capacity. The drug loaded nanoparticles could kill cancer cells effectively with a combination index <1. Both PET and MRI revealed that the nanoparticles showed long blood circulation time and high tumor accumulation. The nanoparticles could inhibit tumor inhibition via intravenous injection of nanoparticles. The polyphenol-based nanoplatform may serve as a promising theranostic candidate for clinical application.

Organic-high ionic strength aqueous solvent systems for spiral counter-current chromatography: graphic optimization of partition coefficient

Abstract: A new series of organic-high ionic strength aqueous two-phase solvents systems was designed for separation of highly polar compounds by spiral high-speed counter-current chromatography. A total of 21 solvent systems composed of 1-butanol-ethanol-saturated ammonium sulfate-water at various volume ratios are arranged according to an increasing order of polarity. Selection of the two-phase solvent system for a single compound or a multiple sample mixture can be achieved by two steps of partition coefficient measurements using a graphic method. The capability of the method is demonstrated by optimization of partition coefficient for seven highly polar samples including tartrazine (K=0.77), tryptophan (K=1.00), methyl green (K= 0.93), tyrosine (0.81), metanephrine (K=0.89), tyramine (K=0.98), and normetanephrine (K=0.96). Three sulfonic acid components in D&C Green No. 8 were successfully separated by HSCCC using the graphic selection of the two-phase solvent system.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Chemistry and properties of nanocrystals of different shapes.

Abstract: The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102