674 research outputs found
Supplementary_material_2 – Supplemental material for Programmed death-ligand 1 and survival in colorectal cancers: A meta-analysis
No full textSupplemental material, Supplementary_material_2 for Programmed death-ligand 1 and survival in colorectal cancers: A meta-analysis by Huihua Cao, Qing Wang, Zhenyan Gao, Zhan Yu, Yugang Wu and Qicheng Lu in The International Journal of Biological Markers</p
Supplementary_material_1 – Supplemental material for Programmed death-ligand 1 and survival in colorectal cancers: A meta-analysis
No full textSupplemental material, Supplementary_material_1 for Programmed death-ligand 1 and survival in colorectal cancers: A meta-analysis by Huihua Cao, Qing Wang, Zhenyan Gao, Zhan Yu, Yugang Wu and Qicheng Lu in The International Journal of Biological Markers</p
Business analytics: online promotion with gift rewards
No full textThis study analytically examines online promotions with gift rewards based on data from a Chinese tea retailer, Huiliu. Gift rewards benefit Huiliu by improving promotional performance. However, they generate operational problems, especially by increasing the costs of holding gift inventory. To address Huiliu’s concerns about gift rewards, we first conduct an empirical study based on Huiliu’s promotional data to examine the effect of gift rewards on customer purchase behavior. The empirical result suggests that gift rewards induce more repeat customer purchases; however, they do not induce customers to spend more money. This empirical result reveals that the effect of gift rewards on customer purchase behavior leads to Huiliu’s intensifying gift inventory pressure. Based on this empirical finding, we develop a theoretical model that addresses gift inventory management. Because of the difficulty of precisely estimating the distributions of some key random variables (e.g., customer demands), we employ a robust approach to solve this model and provide near-optimal robust solutions. We finally present a case study to illustrate how to improve Huiliu’s gift allocation based on the robust inventory solutions. The numerical results show that the improved gift allocation significantly increases Huiliu’s profits (the average profit increment is 3.58%)
Growth of SiGe by D-UHV/CVD at Low Temperature
No full textThe temperature is a key factor for the quality of the SiGe alloy grown by D-UHV/CVD. In conventional conditions,the lowest temperature for SiGe growth is about 550℃. Generally, the pressure of the growth chamber is about 10~(-5) Pa when liquid nitrogen is introduced into the wall of the growth chamber with the flux of 6sccm of the disilane gas. We have succeeded in depositing SiGe films at much lower temperature using a novel method. It is about 10.2 Pa without liquid nitrogen, about 3 magnitudes higher than the traditional method,leading to much faster deposition rate. Without liquid nitrogen,the SiGe film and SiGe/Si superlattice are grown at 485℃. The DCXRD curves and TEM image show that the quality of the film is good. The experiments show that this method is efficient to deposit SiGe at low temperature
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Novel Optical Signal Amplification Mechanisms in Semiconductor Photodetectors
No full textAs quantum computing, communication, and sensing play increasingly important roles in the coming decades, and the demands for high sensitivity imaging grow rapidly, the sensitivity of photodetectors has become a main concern in several key technology sectors. This thesis reports two novel light detection and internal amplification mechanisms that enable photodiodes to achieve desired characteristics such as high detection efficiency, single photon sensitivity, low noise and high speed. Cycling excitation process (CEP) is an intrinsic signal amplification mechanism that was firstly discovered in a heavily-doped compensated Si p/n junction device. By relaxing the k-selection rule (i.e. conservation of momentum), CEP detectors possess high gain, high efficiency, and ultralow noise. Above all, CEP detectors can be made from disordered materials such as amorphous silicon (a-Si), which allows low cost manufacturing and scalability to large array size for intended applications. An a-Si photodiode is demonstrated with ultra-high gain-bandwidth product of 2.25 THz and low noise, based on a very simple structure. Dark current is a key challenge for photodiodes to detect extremely low power such as single photon as it can produce shot noise. A proper designed based on band gap engineering is shown to reduce the dark current of a-Si CEP detectors. The result of temperature dependent dark current measurement conveys the message that the dark current mechanism of a-Si CEP detectors is indirect tunneling followed by Poole-Frenkel effect. The key part is how to block the electron tunneling without affecting the device photo response. Cupric oxide (Cu2O) is an intrinsic p-type semiconductor material, with electron affinity of -3.2 eV and band gap of 2.1 eV. By inserting a thin layer of Cu2O between the a-Si and top electrode, the new structure has a much large electron tunneling barrier. On the other hand, the photogenerated holes can move as before without any additional hole blocking barrier. The measured results support that Cu2O based dark current reduction CEP devices have at least 1-2 orders of magnitude lower dark current at reverse bias 5 V compared to the typical a-Si CEP detectors while the photo responsivity remain the same.Realizing that CEP effect occurs in a thin layer of a-Si, we designed an a-Si CEP detector without any semiconductor substrate. The key challenges are to improve the absorption efficiency and frequency response. Utilizing the localized surface plasmon resonance (LSPR) effect incorporated with CEP effect, a plasmonically enhanced a-Si detector achieves high external quantum efficiency with a record fast impulse response of 170 ps (FWHM). This approach raises the possibility of making detectors out of amorphous materials for high frame rate imaging and optical communications in spite of the low carrier mobilities in the materials.The second optical signal amplification mechanism was observed in organometallic perovskite based detectors when the input power was down to a few or even single photon. It is a quasi-persistent photo response which takes tens of seconds for the current level to increase and reach to saturation after the absorption of a single photon. Based on the observation, we proposed an internal amplification mechanism, ionic impact ionization (I3), to elucidate the phenomenon, which involves a cascade process of ion migration
Smaller Ge Quantum Dots Obtained by ArF Excimer Laser Annealing
No full textGe self-assembled quantum dots (SAQDs) are grown with a self-assembled UHV/CVD epitaxy system. Then,the as-grown Ge quantum dots are annealed by ArF excimer laser. In the ultra-shot laser pulse duration,～20ns, bulk diffusion is forbidden, and only surface diffusion occurs, resulting in a laser induced quantum dot (LIQD). The diameter of the LIQD is 20～25nm which is much smaller than the as-grown dot and the LIQD has a higher density of about 6 × 10~(10)cm~(-2). The surface morphology evolution is investigated by AFM
Development of polynorbornenes and polypeptides as versatile functional biomaterials
No full textPolymer chemistry is an essential connection between organic chemistry, chemical biology and materials science. This living world has presented us many examples of the usages of polymers, such as delivery vehicle, recognition unit, support materials, information storage,5 and so on. Scientists have been trying to create synthetic polymers that can mimic such functionalities and bring widespread applications in different fields. For all synthetic polymers, their properties and potential applications are all based on their chemical nature. This is especially true for synthetic polymeric materials for bio-related applications, because of the delicate and complicated working environments and mechanisms of such biomaterials. Consequently, more facile and delicate controls over the polymers’ chemical nature are in great demand, and bottom-up strategy for the synthesis of smart polymers have been more common in the recent decades.
In this thesis paper, multiple bottom-up syntheses of useful polymeric materials are recorded. In the first part of the thesis, a new approach to prepare functional organic nanoparticles (ONPs) from linear polymers is described. The nanoparticles were obtained by consecutive ring-opening metathesis polymerization and ring-closing metathesis. This flexible and mild synthesis allowed preparation of organic- and aqueous-soluble particles with controllable size and narrow molecular weight distributions. The use of functional monomer(s) and/or chain-transfer agents had led to controllable synthesis of nanoparticles containing single, dual, or multiple reactive functional groups. Such non-toxic ONPs with many controllable parameters could be used to study the effect of surface functional groups on the cellular uptake of corresponding nanoparticles. In addition, dye-functionalized ONPs could serve as water-soluble fluorophores with highly enhanced photostability. Moreover, other functional materials such as DNAs could be conjugated onto the ONPs, bringing in new hybrid materials with applications. The ONPs and ONP-DNA conjugates could also serve as templates for the synthesis of metal nanoparticles, providing a direct and facile synthetic route for functional metal nanoparticles.
In the second part of this paper, major focus is set on a polymeric approach to enhance the efficacy of toxic r(CUG)n-binding compounds for potential Myotonic Dystrophy Type I (DM1) treatment. Also using a bottom-up living polymerization strategy, cell-penetrating polymers bearing active r(CUG)n binding ligands are prepared. The synthetic polypeptide binder was shown to have excellent performance in both molecular and cell studies, giving much enhanced binding to the toxic RNA. The ligand-polypeptide conjugates could successfully disperse ribonuclear foci caused by r(CUG)n-MBNL1 complex, and could fully reverse the mis-splicing of Insulin receptor (IR) mRNAs in the model cells. In addition, potentially due to the polymer-mediated catalytic degradation, r(CUG)n level in the model cells could be greatly reduce by low concentration treatment of the ligand-bearing polymeric material.Submission published under a 24 month embargo labeled 'U of I only', the embargo will last until 2017-08-01The student, Yugang Bai, accepted the attached license on 2015-07-08 at 09:49.The student, Yugang Bai, submitted this Dissertation for approval on 2015-07-08 at 10:41.This Dissertation was approved for publication on 2015-07-09 at 16:04.DSpace SAF Submission Ingestion Package generated from Vireo submission #8366 on 2015-09-29 at 14:59:11Made available in DSpace on 2015-09-29T20:49:45Z (GMT). No. of bitstreams: 2
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Previous issue date: 2015-07-09Embargo set by: Seth Robbins for item 89446
Lift date: 2017-09-29T20:50:34Z
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Optimal Two-class-based Storage in a Live-cube Compact Storage System
No full textLive-cube compact storage systems realize high storage space utilization and high throughput, due to full automation and independent movements of unit loads in three-dimensional space. Applying an optimal two-class-based storage policy where high-turnover products are stored at locations closer to the Input/Output point significantly reduces the response time. Live-cube systems are used in various sectors, such as warehouses and distribution centers, parking systems, and container yards. The system stores unit loads, such as pallets, cars, or containers, multi-deep at multiple levels of storage grids. Each unit load is located on its own shuttle. Shuttles move unit loads at each level in the x and y directions, with a lift taking care of the movement in the z-direction. Movement of a requested unit load to the lift location is comparable to solving a Sam Loyd's puzzle game where 15 numbered tiles move in a 4 × 4 grid. However, with multiple empty locations, a virtual aisle can be created to shorten the retrieval time for a requested unit load. In this article, we optimize the dimensions and zone boundary of a two-class live-cube compact storage system leading to a minimum response time. We propose a mixed-integer nonlinear model that consists of 36 sub-cases, each representing a specific configuration and first zone boundary. Properties of the optimal system are used to simplify the model without losing any optimality. The overall optimal solutions are then obtained by solving the remaining sub-cases. Although the solution procedure is tedious, we eventually obtain two sets of closed-form expressions for the optimal system dimensions and first zone boundary for any desired system size. In addition, we propose an algorithm to obtain the optimal first zone boundary for situations where the optimal system dimensions cannot be achieved. To test the effectiveness of optimal system dimensions and first zone boundary on the performance of a two-class-based live-cube system, we perform a sensitivity analysis by varying the ABC curve, system size, first zone size, and shape factor. The results show that for most cases an optimal two-class-based storage outperforms random storage, with up to 45% shorter expected retrieval time. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited and is not altered, transformed, or built upon in any way.Nima Zaerpour, Yugang Yu & René B.M. de Koster (2017) Optimal two-classbased storage in a live-cube compact storage system, IISE Transactions, 49:7, 653-668,2472-557
Ab initio study of irradiation tolerance for different M(n+1)AX(n) phases: Ti3SiC2 and Ti3AlC2
No full textLayered ternary M(n+1)AX(n) (MAX) materials are recently proposed to be promising candidates for future fission and fusion programmes because of their unique properties inherited from both ceramics and metals. However, different M(n+1)AX(n) materials demonstrate different behaviors when exposed to energetic neutron or ion irradiations. Based on first-principles calculations, we have investigated the irradiation tolerance of two typical M(n+1)AX(n) materials: Ti3SiC2 and Ti3AlC2 from two aspects. First, we make a detailed analysis on the interatomic bonding characters, which are believed to be responsible for the resistance to radiation-induced amorphization. Second, the formation energies of various intrinsic and antisite defects in these two compounds are calculated in order to elucidate their amorphization mechanism. Our results show that the absence of orbitals overlap of Al-C in Ti3AlC2 renders it more resistant to amorphization compared to Ti3SiC2. In addition, the antisite defects Al-Ti(1) and Al-Ti(2) in Ti3AlC2 have much lower formation energies compared to Si-Ti(1) and Si-Ti(2) in Ti3SiC2, which implies that the replacement of Ti with Al is easier than Si, thus providing an alternative way to accommodate the defects resulted from irradiation damage cascades. These results indicate that Ti3AlC2 is more irradiation tolerant than Ti3SiC2, in accordance with experimental observations. Our results have profound implications for the choice of appropriate MAX phase with best performance to be used in next reaction reactors. (C) 2014 AIP Publishing LLC
The Core Content and Practical Approach of China’s Global Security Initiative
No full textThis research paper provides an overview of China’s Global Security Initiative, its essential components, and its practical implementation. Firstly, the paper highlights the significance of the Global Security Initiative in the broader context of China’s global security policy. It then outlines the core elements of the Global Security Initiative, which include promoting security cooperation, establishing a global security framework, and enhancing comprehensive security measures. Secondly, the author explores the practical approach of the Global Security Initiative, which emphasizes cooperation between states, international organizations, civil society, and the private sector. The author also describes the implementation of the Global Security Initiative, such as the establishment of the Global Security Initiative Working Group and its role in regional security cooperation. Furthermore, the author discusses how the Global Security Initiative fits into the Belt and Road Initiative. Lastly, the paper addresses the challenges posed by the Global Security Initiative, including the need for greater transparency and the establishment of an effective governance system. By offering insights into the Global Security Initiative and its implications for global security, the author provides valuable information on this topic. Overall, this paper provides a comprehensive overview of the Global Security Initiative, its core components, practical approach, implementation, and challenges, making it an informative read for anyone interested in China’s global security policy
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