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PEX16 contributions to peroxisome import and metabolism revealed by viable Arabidopsis pex16 mutants

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Journal of Integrative Plant Biology 2019年第7期61卷 853-870页

作者： Sarah E.Burkhart Roxanna J.Llinas Bonnie Bartel department of BioSciences Rice University

Peroxisomes rely on peroxins(PEX proteins) for biogenesis, importing membrane and matrix proteins, and fission. PEX16, which is implicated in peroxisomal membrane protein targeting and forming nascent peroxisomes from the endoplasmic reticulum(ER), is unusual among peroxins because it is inserted co-translationally into the ER and localizes to both ER and peroxisomal membranes. PEX16 mutations in humans, yeast, and plants confer some common peroxisomal defects; however, apparent functional differences have impeded the development of a unified model for PEX16 action. The only reported pex16 mutant in plants, the Arabidopsis shrunken seed1 mutant, is inviable,complicating analysis of PEX16 function after embryogenesis. Here, we characterized two viable Arabidopsis pex16 alleles that accumulate negligible PEX16 protein levels. Both mutants displayed impaired peroxisome function-slowed consumption of stored oil bodies, decreased import of matrix proteins, and increased peroxisome size. Moreover,one pex16 allele exhibited reduced growth that could be alleviated by an external fixed carbon source, decreased responsiveness to peroxisomally processed hormone precursors, and worsened or improved peroxisome function in combination with other pex mutants. Because the mutations impact different regions of the PEX16 gene, these viable pex16 alleles allow assessment of the importance of Arabidopsis PEX16 and its functional domains.

关键词： pex16 mutants peroxisome metabolism

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Characterization of tin（Ⅱ） sulfide defects/vacancies and correlation with their photocurrent

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Nano Research 2017年第1期10卷 218-228页

作者： Mingyang Liu Luqing Wang Linan Zhou Sidong Lei Jarin Joyner Yingchao Yang Robert Vajtai Pulickel Ajayan Boris I. Yakobson Pol Spanos department of Materials Science and Nanoengineering Rice University Houston Texas 77005 USA department of Chemistry Rice University Houston Texas 77005 USA

The presence of defects/vacancies in nanomaterials influences the electronic structure of materials, and thus, it is necessary to study the correlation between the optoelectronic properties of a nanomaterial and its defects/vacancies. Herein, we report a facile solvothermal route to synthesize three-dimensional （3D） SnS nanostructures formed by {131} faceted nanosheet assembly. The 3D SnS nanostructures were calcined at temperatures of 350, 400, and 450 ~C and used as counter electrodes, before their photocurrent properties were investigated. First principle computation revealed the photocurrent properties depend on the defect/vacancy concentration within the samples. It is very interesting that characterization with positron annihilation spectrometry confirmed that the density of defects/vacancies increased with the calcination temperature, and a maximum photocurrent was realized after treatment at 400 ℃. Further, the defect/vacancy density decreased when the calcination temperature reached 450℃ as the higher calcination temperature enlarged the mesopores and densified the pore walls, which led to a lower photocurrent value at 450℃ than at 400℃.

关键词： SnS microspheres mesoporous nanosheetassembly defects/vacancies positron annihilationspectrometry photocurrent.

FIXED-POINT CONTINUATION APPLIED TO COMPRESSED SENSING:IMPLEMENTATION AND NUMERICAL EXPERIMENTS

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Journal of Computational Mathematics 2010年第2期28卷 170-194页

作者： Elaine T.Hale department of Computational and Applied Mathematics rice University

Fixed-point continuation （FPC） is an approach, based on operator-splitting and continuation, for solving minimization problems with l1-regularization：min ｜｜x｜｜1＋uf（x）.We investigate the application of this algorithm to compressed sensing signal recovery, in which f（x） = 1/2｜｜Ax-b｜｜2M,A∈m×n and m≤n. In particular, we extend the original algorithm to obtain better practical results, derive appropriate choices for M and u under a given measurement model, and present numerical results for a variety of compressed sensing problems. The numerical results show that the performance of our algorithm compares favorably with that of several recently proposed algorithms.

关键词： l1 regularization Fixed-point algorithm Continuation Compressed sensing,Numerical experiments.

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Microneedle-based skin patch for blood-free rapid diagnostic testing

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Microsystems & Nanoengineering 2020年第1期6卷 255-265页

作者： Xue Jiang Peter B.Lillehoj department of Mechanical Engineering Rice UniversityHoustonTX 77005USA department of Bioengineering Rice UniversityHoustonTX 77030USA

Rapid diagnostic tests are one of the most commonly used tests to detect and screen for infectious diseases in the developing *** these tests are simple,inexpensive,and readily available,they rely on finger-prick blood sampling,which requires trained medical personnel,poses risks of infection,and can complicate cooperation in young children,asymptomatic individuals,and communities with blood ***,we report a novel microneedle-based skin patch for the rapid detection of protein biomarkers in dermal interstitial *** collection is facilitated by a hydrophilic hollow microneedle array that autonomously extracts and transports interstitial fluid to an antibody-based lateral flow test strip via surface tension for colorimetric antigen *** employ a simple gold enhancement treatment to enhance the detection sensitivity of this colloidal gold-based lateral flow assay and elucidate the underlying mechanism of this enhancement mechanism through experimental *** proof-of-concept,this device was used to detect Plasmodium falciparum histidine-rich protein 2,a biomarker for malaria infection,which could be detected at concentrations as low as 8ng/*** test can be completed in<20 min and requires no *** the best of our knowledge,this work is the first demonstration of a microneedle-based lateral flow assay for rapid protein detection in dermal interstitial *** addition to its simplicity,minimally invasive nature,and low cost,this diagnostic device can be readily adapted to detect other protein biomarkers in interstitial fluid,making it a promising tool for point-of-care testing.

关键词： needle patch readily

WISH:wavefront imaging sensor with high resolution

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Light(Science & Applications) 2019年第1期8卷 818-827页

作者： Yicheng Wu Manoj Kumar Sharma Ashok Veeraraghavan department of Electrical and Computer Engineering Rice UniversityHoustonTXUSA Applied Physics Program Rice UniversityHoustonTXUSA

Wavefront sensing is the simultaneous measurement of the amplitude and phase of an incoming optical *** wavefront sensors such as Shack-Hartmann wavefront sensor(SHWFS)suffer from a fundamental tradeoff between spatial resolution and phase estimation and consequently can only achieve a resolution of a few thousand *** break this tradeoff,we present a novel computational-imaging-based technique,namely,the Wavefront Imaging Sensor with High resolution(WISH).We replace the microlens array in SHWFS with a spatial light modulator(SLM)and use a computational phase-retrieval algorithm to recover the incident *** wavefront sensor can measure highly varying optical fields at more than 10-megapixel resolution with the fine phase *** the best of our knowledge,this resolution is an order of magnitude higher than the current noninterferometric wavefront *** demonstrate the capability of WISH,we present three applications,which cover a wide range of spatial ***,we produce the diffraction-limited reconstruction for long-distance imaging by combining WISH with a large-aperture,low-quality Fresnel ***,we show the recovery of high-resolution images of objects that are obscured by ***,we show that WISH can be used as a microscope without an objective *** study suggests that the designing principle of WISH,which combines optical modulators and computational algorithms to sense high-resolution optical fields,enables improved capabilities in many existing applications while revealing entirely new,hitherto unexplored application areas.

关键词： estimation. field. resolution

3D micropattern force regulates stem cell function

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National Science Review 2023年第8期10卷 69-70页

作者： Antonios G. Mikos department of Bioengineering Rice University

Biophysical cues of the cellular microenvironment significantly influence cell behaviors by mechanotransduction [1,2].For example, the mechanical properties of the extracellular matrix modulate human mesenchymal stem ...

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Multi-layer 3D chirality:its enantioselective synthesis and aggregation-induced emission

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National Science Review 2021年第1期8卷 7-9页

作者： Junliang Zhang László Kürti department of Chemistry Fudan University department of Chemistry Rice University

Chirality has been extensively studied in interdisciplinary fields for almost two centuries since its ubiquity was discovered by Louis Pasteur in 1848, when he successfully separated a pair of enantiomers. Indeed, chirality is present at all levels in nature—in the form of subatomic particles, macromolecules such as proteins and DNA, microscopic living organisms such as helical bacteria and even in the form of macroscopic objects such as sea shells and spiral galaxies.

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Principal resonance response of a stochastic elastic impact oscillator under nonlinear delayed state feedback

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Chinese Physics B 2015年第4期24卷 90-99页

作者：黄冬梅徐伟谢文贤韩群 department of Applied Mathematics Northwestern Polytechnical University department of Civil and Environmental Engineering Rice University

In this paper, the principal resonance response of a stochastically driven elastic impact （El） system with time-delayed cubic velocity feedback is investigated. Firstly, based on the method of multiple scales, the steady-state response and its dynamic stability are analyzed in deterministic and stochastic cases, respectively. It is shown that for the case of the multi- valued response with the frequency island phenomenon, only the smallest amplitude of the steady-state response is stable under a certain time delay, which is different from the case of the traditional frequency response. Then, a design criterion is proposed to suppress the jump phenomenon, which is induced by the saddle-node bifurcation. The effects of the feedback parameters on the steady-state responses, as well as the size, shape, and location of stability regions are studied. Results show that the system responses and the stability boundaries are highly dependent on these parameters. Furthermore, with the purpose of suppressing the amplitude peak and governing the resonance stability, appropriate feedback gain and time delay are derived.

关键词： elastic impact system time delay frequency island jump avoidance

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Polycrystalline morphology and mechanical strength of nanotube fibers

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npj Computational Materials 2022年第1期8卷 180-185页

作者： Nitant Gupta Evgeni S.Penev Boris I.Yakobson department of Materials Science and NanoEngineering Rice UniversityHoustonTX77005USA

Correlating mechanical performance with mesoscale structure is fundamental for the design and optimization of light and strong fibers(or any composites),most promising being those from carbon *** all forms of nanotube fiber production strategies,due to tubes’mutual affinity,some degree of bundling into liquid crystal-like domains can be expected,causing heterogeneous load transfer within and outside these domains,and having a direct impact on the fiber *** employing large-scale coarse-grained simulations,we demonstrate that the strength s of nanotube fibers with characteristic domain size D scales as s~1/D,while the degree of longitudinal/axial disorder within the domains(akin to a smectic↔nematic phase transition)can substantially mitigate this dependence.

关键词： composites fibers strength