821 research outputs found
From Simulation to Bedside: the Missing Link in Pediatric Training Research [Response to Letter]
No full textHongjun Ba, Lingling Xu, Huimin Peng, Yufen Gu, Yijuan Li, Xiaoyun Jiang, Xiaoyu Li, Shujuan Li Pediatric Department, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510080, People’s Republic of ChinaCorrespondence: Xiaoyu Li, Email [email protected] Shujuan Li, Email [email protected]
Replication Data for: 'Investor Memory and Biased Beliefs: Evidence from the Field'
No full textThe programs replicate tables and figures from "Investor Memory and Biased Beliefs: Evidence from the Field," by Jiang, Liu, Peng, and Yan. (2025-07-22
Corrigendum: Conjugated microporous poly(aryleneethynylene) networks
No full textThis corrigendum relates to: Conjugated Microporous Poly(aryleneethynylene) Networks, Jia-Xing Jiang, Fabing Su, Abbie Trewin, Colin D. Wood, Neil L. Campbell, Hongjun Niu, Calum Dickinson, Alexey Y. Ganin, Matthew J. Rosseinsky, Yaroslav Z. Khimyak, Andrew I. Cooper, Volume 46, Issue 45, Angewandte Chemie International Edition, pages 8574-8578. First Published online: September 26, 2007. There was a small error in the second sentence on page 8576 of this Communication. This sentence should read: “The ratio of intensities of acetylene to aromatic peaks was calculated using variable-contact-time 1H–13C CP/MAS NMR spectra with the following results: CMP-1 0.27 (expected value 0.40); CMP-2 0.18 (expected value 0.25); CMP-3 0.10 (expected value 0.18).” The authors apologize for this error and wish to note that none of the interpretations in the paper are affected by this change
Growth and Characterisation of Boron Rich Nanomaterials
No full textIn this study nanomaterials are grown in a solid state reaction at 1300C of boron, barium oxide and iron(II/III)oxide powders in an argon atmosphere. The nanomaterials are shown to be grown via vapour based method by growing the nanomaterials on a separate silicon wafer that has been sputtered with iron and placed downstream of the powders in the flow of argon. An area of the silicon wafer is kept free of iron by using a mask when sputtering the wafer. When nanomaterials are grown, the masked area remains free of nanomaterials. This shows that the presence of iron is vital for the nucleation of the nanomaterials and also indicates the possibility of growing these nanomaterials on targeted sites.
The nanomaterials produced are examined and it is found that we have a presence of amorphous, crystalline and multiple twinned nanowires. The evidence collected suggests that 70% of the nanowires are twinned. The single crystal nanowires can be identified as boron carbide by comparing to diffraction pattern simulations of a boron carbide unit cell. The twinned diffraction pattern is shown to be due to different segments of the nanowire being in different diffraction condition by using Dark Field imaging. The Twinned wires are also shown to have at least four segments in a cyclic [001] twinning orientation in simultaneous diffraction condition by comparing to a twinned structure constructed from simulations. Elemental analysis using Electron Energy Loss Spectroscopy and Energy Dispersive X-ray shows that the composition of the nanomaterials is mainly boron and carbon.
The role of the iron layer on the wafer is investigated to see how varying the thickness will affect the nanomaterials grown. It is successfully shown that an increase in the thickness of the iron layer results in a greater density of nanomaterials. However there is no great variation in the average diameter of the nanomaterials produced.
The absence of a visible signal for iron in the Elemental analysis of nanostructure covered silicon wafer shows that the amount of iron in the sample has decreased during the reaction. However iron is found in small amounts in droplet structures at the tips of nanomaterials this is different to work done on a similar system at 1100C. This suggests that the role of the iron in the growth of these nanomaterials at this temperature is not yet understood. However this work has confirmed that the iron is essential for the nucleation of the nanomaterials, but post nucleation growth that was previously assumed to be a conventional VLS growth may switch to an oxide assisted growth mode
Semiconductor-based nanostructures for photoelectrochemical sensors and biosensors
No full textA diverse array of semiconductor-based nanostructures have been synthesized and utilized in many applications, in which photoelectrochemical sensor or biosensor is a new kind of developing analytical technology for the detection of the low concentration of analytes. Due to the parameters of the detection processes in relation to the photocurrent or photopotential and the appearance of new semiconductor-based functional nanostructures, it makes photoelectrochemical analysis with high sensitivity, rapid detection, inherent miniaturization, and easy portability. In this chapter, we will introduce the basic principle of the photoelectrochemical sensor or biosensor and focus on the new progress of photoelectrochemical sensors and biosensors with different semiconductor materials. Meanwhile, a variety of detection mechanisms and the characteristics of photoelectrochemical sensor and biosensor are also introduced and their future developments are also prospected and discussed
Abstract 1262: Aspirin inhibits the carcinogenesis of esophageal squamous cell carcinoma and enhances its responses to cisplatin
No full textAbstract
Esophageal squamous cell carcinoma (ESCC) is one of the most lethal malignancies. Over 70% of ESCC cases occur in China. Unfortunately, the treatment of ESCC has hardly been improved all these years. Several studies suggested that aspirin (ASA) might decrease the risk of ESCC and prolonged the survival of patients with ESCC. However, it is unclear if ASA could prevent ESCC and/or enhance ESCC treatment by chemotherapy. In this study, a N-nitroso-N-methylbenzylamine (NMBzA) - induced ESCC model was employed to prove that aspirin could prevent the growth of esophageal tumor. F344 rats were treated with NMBzA by subcutaneous injection with or without ASA in drinking water (2mg/ml). After 35 week ASA-NMBzA or NMBzA alone treatment, rats were killed and esophageal tumor development were examined. The results showed that F344 rats treated with NMBzA and receiving a daily intake of ASA developed much less tumors than F344 rats treated with NMBA alone both in amount and in size (Tumor count: 2.40 ± 1.57 vs 10.85 ± 3.86 , P < 0.001; Tumor volume: 11.10 ± 13.38 mm3 vs 70.79 ± 41.65 mm3, P < 0.001). Immunohistochemical analysis indicated that a higher rate of apoptosis was observed in the basal layer of esophageal epithelium in ASA-NMBzA treated rats than in NMBzA alone treated rats. These results indicated that ASA prevented development of esophageal tumors in rats induced by NMBzA. Moreover, using in vitro human ESCC cell culture and in vivo xenograft models, we showed that ASA has strong beneficial effects on inhibition of ESCC cell proliferation and colony formation, reduction of ESCC cancer stem cells and enhance of ESCC cell cytotoxicity induced by cisplatin treatment. Biochemical analysis revealed that these effects of ASA on human ESCC cells in vitro and in vivo were due to inhibiting the repairing of DNA damage, decreasing the efflux activity and ALDH1 activity of the tumor cells, and blockades of PI3K/Akt pathway. Thus, our results demonstrated a positive role of aspirin in the prevention and treatment of ESCC.
Note: This abstract was not presented at the meeting.
Citation Format: Zhigeng Zou, Hongjun Fan, Xiying Yu, Shuming Zhang, Liping Guo, Wei Jiang, Shih-Hsin Lu. Aspirin inhibits the carcinogenesis of esophageal squamous cell carcinoma and enhances its responses to cisplatin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1262. doi:10.1158/1538-7445.AM2017-1262</jats:p
Abstract 1266: Metformin represses esophageal carcinogenesis in NMBzA-treated rat model through inhibiting AMPK/mTOR and Stat3 signaling pathways
No full textAbstract
Esophageal cancer is one of the most aggressive tumor types because of its invasiveness and metastatic potential. Metformin is one of the most used diabetic drugs for the management of type 2 diabetes mellitus in the world. The role of metformin in prevention of the development and progression of a variety of human tumors has been studied. However, the detailed mechanisms have not yet been fully understood. In the present study, we investigated the effects of metformin on the suppression of esophageal carcinogenesis in a rat model, in which F344 rats were treated with N-nitroso-N-methylbenzylamine (NMBzA 0.30 mg/kg s.c.) three times per week for 35 weeks to induce esophageal tumors. To monitor the effects of metformin in this model, one group of rats were administered with metformin (3 g/L) in the drinking water at the first NMBzA injection. Our results showed that although there was no significant difference in body weight in rats of different groups, rats treated with NMBzA and metformin together significantly reduced the tumor formation and tumor volume when compared with rats treated with NMBzA alone. Statistic analyses demonstrated that the tumor numbers was reduced in NMBzA-treated rats received metformin to an average of 1.85 ± 1.09 tumors per rat when compared with 10.85 ± 3.86 (P &lt; 0.001) in rats without metformin, while the tumor volume was decreased from 70.79 ± 41.65 mm3 per rat without metformin administration to 8.64 ± 13.45 mm3 (P &lt; 0.001) with metformin administration. In addition, 7 out of 24 rats in the NMBzA-treated group died before week 35 but no rats died in the other groups. Furthermore, immunoblotting analysis indicated that p-mTORSer2448, p-Stat3Tyr705, and Cyclin D1 protein levels significantly decreased, while p-AMPKThr172 significantly increased in tumors obtained from rats treated with NMBzA and metformin when compared with tumors obtained from rats treated with NMBzA alone. Thus, our results indicated that metformin suppressed NMBzA-induced esophageal carcinogenesis via inhibition of the AMPK/mTOR and Stat3 signaling pathways. Together, our study suggested that metformin might have a potential use for treatment and prevention of esophageal cancer.
Citation Format: Hongjun Fan, Zhigeng Zou, Xiying Yu, Liping Guo, Wei Jiang, Shih-Hsin Lu. Metformin represses esophageal carcinogenesis in NMBzA-treated rat model through inhibiting AMPK/mTOR and Stat3 signaling pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1266. doi:10.1158/1538-7445.AM2017-1266</jats:p
The development of a scenario independent method for evaluating the evacuation complexity of a building
No full textOver the past two decades, more than 30 evacuation models have been developed to reproduce people’s movement patterns in evacuation. However, evacuation models cannot assess whether one building is better than another in regards to evacuation wayfinding.
There exist techniques that attempt to compare different buildings for evacuation complexity. However, these graph measures are primarily used to measure the relative accessibility of different locations in a spatial system and were not generated for the purpose of comparing the complexity of different buildings. Currently only one method exists, Donegan’s method [DT98] [PD96] [DT99], which can be applied to compare building for evacuation ability. However, this technique is severely limited to specific building layouts and only considers connectivity.
Taking the Donegan’s method as a first step, this thesis extends this algorithm to obtain a new Distance Graph Method, which considers travel distance as well as being able to be applied to graphs with circuits. Then a further building complexity measures is presented, the Global Complexity (PAT) method. This is shown to be a valid measure which considers additional important factors such as wayfinding time, travel distance and the areas of compartments.
The Distance Graph Method and Global Complexity (PAT) methods are based on a room graph representation which does not have the descriptive power to describe the actual routes taken during the wayfinding process. To resolve this drawback a further method is presented which utilises a ‘route-based graph’ that has the ability to represent the real route that an evacuee will take during the wayfinding process.
Furthermore the Distance Graph Method and Global Complexity (PAT) methods assume a “worst state” calculation for the nodal information. This means for buildings with more than one exit these methods calculate a global building complexity according to a mathematical formula, which considers all exits separately. To address these problems, the final method, Complexity Time Measure, is presented, which is based around a number of wayfinding behaviour rules over a ‘route-based graph’ representation. This addresses the question: ‘If an occupant is positioned at a random location within a building, on average how long does the occupant need to spend to find an available exit?’ Hence, provides a means to compare complex buildings, with circuits, in relation to evacuation capability
Design synthetic polymers for remodeling and reconstruction of biomembrane functions
No full textBiomembranes define a compartment that confines all substances crucial to
cellular activity. They also provide a habitat for membrane proteins which control
transportation, signaling and energy conversion. Remodeling biomembranes offers a
way to determine the fate of a cell, while reconstructing biomembrane functions gives
possibility to the study and utilization of membrane proteins in vitro. In this work, we
explored both possibilities through synthetic approaches.
On the one hand, we designed polymer based nanostructured membrane-active
antimicrobials (MAAs) to remodel the membrane of drug-resistant bacteria and thus to
kill them. The rapid expansion of antibiotic resistance makes the need to find new
antimicrobial agents urgent. Previous studies suggested that a membrane–active
mechanism could be a solution to counter growing antibiotic resistance. Many MAAs
have been developed, including antimicrobial peptides (AMPs) and their synthetic
mimics, such as peptoids, and amphiphilic polymers. However, the application of
MAAs was either limited by the high costs to produce them, or by their low
antimicrobial activity and high cell toxicity. It has been recognized that a balanced
amphiphilicity is important to optimize the activity and selectivity of MAAs. The
dilemma, however, is that the amphiphilic structure also increases cell toxicity. In
contrast, hydrophilic peptides and polymers generally have lower antimicrobial
activity, but also possess less toxicity. Recent studies suggested that nanostructure
could be another determinant factor for antimicrobial activity. In this work, we
developed hydrophilic MAAs of different nanostructures and studied their structureactivity
relationship. We synthesized polymer molecular brushes of different shapes
and silica-polymer nanocomposites of different sizes and studied their antimicrobial
activity, mammalian cell toxicity as well as their antimicrobial mechanism. We show
that the nanostructure can convert the initially inactive linear-chain hydrophilic
polymers into active nanostructured antimicrobials and their antimicrobial activity,
selectivity and specificity are both size and shape-dependent. We also show that the
nanostrutured antimicrobials have low human cell toxicity and that they are MAAs
that kill bacteria by inducing topological changes in their membrane. Meanwhile, by
using star polymers of different branches as a model, we investigated the transition
from inactive linear-chain polymers to active nanostructured MAAs. A critical
nanostructure, thus the resulted multivalency, is required to kill the bacteria. Our work
has potential application in designing new antimicrobial agents to fight drug-resistant
bacteria.
On the other hand, we reconstructed biomembrane functions via polymer based
materials to study and utilize membrane proteins (MPs). Both the development of MP
based nanomaterials and the study of structure and activity of MPs require the
reconstitution of detergent extracted MPs into a simulated native environment that can
appropriately accommodate the hydrophobic and hydrophilic regions of MPs. The use
of detergent micelles and liposomes as simulated native environments has remarkably
advanced the study of membrane proteins, but they are far from ideal as MPsupporting
platforms, due to physicochemical properties mismatch, undesirable light
scattering, labile nature, and/or uncontrolled reconstitution. In this work, we
developed new platforms based on polymer vesicles or polymer nanodiscs for
stabilizing MPs. We show that by using charge-interaction-directed reconstitution
(CIDR) mechanism, polymer vesicles can direct the spontaneous reconstitution of
MPs into organized and oriented patterns. A new activation mechanism for rhodopsin
reconstituted in polymer vesicles was uncovered. We also show that polymer
nanodiscs (PNDs) can be prepared by the self-assembly of amphiphilic tri-block
copolymers in the presence of membrane scaffold protein and they can maintain the
activity and stability of MsbA. Finally, we developed new polymer based scaffold
zSMAs as a replacement of membrane scaffold protein and styrene-maleic acid
copolymers to be used in nanodisc preparation. We show that both our polymer
scaffold and the nanodiscs prepared by the polymer scaffold are stable under a wide
range of pH and divalent ion concentrations. The membrane proteins reconstituted in
the nanodiscs encased by polymer scaffold are stable and functional. Our new
platforms and scaffolds have potential application in studying the structure and
activity of MPs and in developing MP based nanomaterials.Restricted until January 2020
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