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Tunable electron and phonon properties of folded single-layer molybdenum disulfide

Nano Research 2018年第3期11卷 1541-1553页

作者： Jie Peng peter W. chung Madan Dubey Raju R. Namburu Department of Mechanical Engineering University of Maryland College Park MD 20742 USA Sensors & Electron Devices Directorate U.S. Army Research Laboratory Adelphi MD 20783 USA Computational & Information Sciences Directorate U.S. Army Research Laboratory Aberdeen Proving Ground MD 21005 USA

A unique feature of transition metal dichalcogenides is their single-layer form, which enables folding. Although folding has been found to significantly affect the photoluminescence spectrum and some in-plane properties, only limited insight has been gained on how to modulate those properties. In this report, we examine the structure of folds of a single sheet of MoS2 and the dependence of the ground-s tate electronic and phonon transport properties on the wrapping length. As the folded structure is effectively a bilayer that terminates in a loop, the wrapping length modulates the relative size of the bilayer region to the closed loop along the edge. A combination of computational methods, including approaches based on variational mechanics, classical potentials, and density functional theory, are employed. Highly accurate calculations of the reference folded structure are first carried out to show that the folded structure is largely insensitive to the wrapping length. The folded structures are subsequently used to estimate the electronic band gap, which is found to vary significantly as a function of the wrapping length, and converges from below to the limit value corresponding to an infinite bilayer. The gap values range from 0.43 to 1.09 eV, with a crossover to an indirect gap, which suggests that the transitions must be lattice-assisted, similar to the transitions in the bilayer and bulk forms. However, the phonons, while affected by the formation of the folded structure, are insensitive to the wrapping length. In fact, the overall thermal transport behavior along the folding axis is unchanged. The possibility of modulating the gap value while keeping the thermal properties unchanged opens up new exciting avenues for further applications of this emerging material.

关键词： molybdenum disulfide folded structure electronic band structure thermal conductivity phonon

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Pretreatment with Rhodiola Rosea Extract Reduces Cognitive Impairment Induced by Intracerebroventricular Streptozotocin in Rats: Implication of Anti-oxidative and Neuroprotective Effects

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Biomedical and Environmental Sciences 2009年第4期22卷 318-326页

作者： peter chung Division of Neuroscience Department of Histology and Embryology Zhongshan School of Medicine Sun Yat-Sen University

Objective To investigate the pretreatment effects of Rhodiola rosea （R. rosea） extract on cognitive dysfunction, oxidative stress in hippocampus and hippocampal neuron injury in a rat model of Alzheimer＇s disease （AD）. Methods Male Sprague-Dawley rats were pretreated with R. rosea extract at doses of 1.5, 3.0, and 6.0 g/kg for 3 weeks, followed by bilateral intracerebroventricular injection with streptozotocin （1.5 mg/kg） on days 1 and 3. Behavioral alterations were monitored after 2 weeks from the lesion using Morris water maze task. Three weeks after the lesion, the rats were sacrificed for measuring the malondialdehyde （MDA）, glutathione reductase （GR） and reduced glutathione （GSH） levels in hippocampus and histopathology of hippocampal neurons. Results The MDA level was significantly increased while the GR and GSH levels were significantly decreased with striking impairments in spatial learning and memory and severe damage to hippocampal neurons in the model rat induced by intracerebroventricular injection of streptozotocin. These abnormalities were significantly improved by pretreatment with R. rosea extract （3.0 g/kg）. Conclusion R. rosea extract can protect rats against cognitive deficits, neuronal injury and oxidative stress induced by intracerebroventricular injection of streptozotocin, and may be used as a potential agent in treatment of neurodegenerative diseases such as AD.

关键词： Rhodiola rosea Oxidative stress Neuroprotective effect Learning and memory Alzheimer's disease Intracerebroventricular streptozotocin

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Mitochondrial protective and anti-apoptotic effects of Rhodiola crenulata extract on hippocampal neurons in a rat model of Alzheimer's disease

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Neural Regeneration Research 2017年第12期12卷 2025-2034页

作者： Jun-mei Wang Ze-qiang Qu Jin-lang Wu peter chung Yuan-shan Zeng Department of Histology and Embryology Zhongshan School of Medicine Sun Yat-sen University Guangzhou Guangdong Province China Department of Electron Microscope Zhongshan School of Medicine Sun Yat-sen University Guangzhou Guangdong Province China Shanghai Ninth People's Hospital Shanghai liao Tong University School of Medicine Shanghai China Institute of Spinal Cord In)ury Sun Yat-sen University Guangzhou Guangdong Province China Co-innovation Center of Neuroregeneration Nantong University Nantong Jiangsu Province China Guangdong Province Key Laboratory of Brain Function and Disease Zhongshan School of Medicine Sun Yat-sen University Guangzhou Guangdong Province China

In our previous study, we found that the edible alcohol extract of the root of the medicinal plant Rhodiola crenulata（RCE） improved spatial cognition in a rat model of Alzheimer＇s disease. Another study from our laboratory showed that RCE enhanced neural cell proliferation in the dentate gyrus of the hippocampus and prevented damage to hippocampal neurons in a rat model of chronic stress-induced depression. However, the mechanisms underlying the neuroprotective effects of RCE are unclear. In the present study, we investigated the anti-apoptotic effect of RCE and its neuroprotective mechanism of action in a rat model of Alzheimer＇s disease established by intracerebroventricular injection of streptozotocin. The rats were pre-administered RCE at doses of 1.5, 3.0 or 6.0 g/kg for 21 days before model establishment. ATP and cytochrome c oxidase levels were significantly decreased in rats with Alzheimer＇s disease. Furthermore, neuronal injury was obvious in the hippocampus, with the presence of a large number of apoptotic neurons. In comparison, in rats given RCE pretreatment, ATP and cytochrome c oxidase levels were markedly increased, the number of apoptotic neurons was reduced, and mitochondrial injury was mitigated. The 3.0 g/kg dose of RCE had the optimal effect. These findings suggest that pretreatment with RCE prevents mitochondrial dysfunction and protects hippocampal neurons from apoptosis in rats with Alzheimer＇s disease.

关键词： nerve regeneration Alzheimer's disease intracerebroventricular injection streptozotocin neuronal apoptosis neuroprotection cytochrome c oxidase adenosine triphosphate caspase-3 NeuN neural regeneration

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Bifidobacterium infantis attenuates colitis by regulating T cell subset responses

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World Journal of Gastroenterology 2014年第48期20卷 18316-18329页

作者： Li Zuo Kai-Tao Yuan Li Yu Qing-Hong Meng peter Chee-Keung chung Ding-Hua Yang Department of Immunology Guiyang Medical College Department of Surgery the First AffiliatedHospital of Sun Yat-sen University Department of Paediatrics Guangzhou First Municipal People’s Hospital Department of Hepatobiliary Surgery Nan Fang Hospital Southern Medical University

AIM: to investigate the effect of Bifidobacterium infantis (B. infantis) on the T cell subsets and in attenuating the severity of experimental colitis in mice.

关键词： Bifidobacterium Colitis Cytokines Th17 Regulatory T cells

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NATURAL SUBSTANCE AND ANTI-CANCER

NATURAL SUBSTANCE AND ANTI-CANCER

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2014《中国国际肿瘤营养学论坛》暨第二届《全国肿瘤营养与支持治疗学术会议》

作者： peter chung Royal College of Surgeons(Edin)

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TAV of English Finite Verb Phrase

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Journal of Literature and Art Studies 2018年第7期8卷 1126-1130页

作者： peter Lung-shan chung University of Hong Kong Hong KongChina

It is widely known that a finite verb phrase(fVP)of a clause in English consists of three components:tense,aspect and *** the two tenses,present and past,and the two voices,active and passive,are recognized and generally agreed,the number and constituents of aspects may not be so simple and they are open to *** paper proposes that a new aspect,the“modal”aspect,be included in addition to the commonly recognized ones,namely“simple”,“perfect”and“continuous”(also known as“progressive”).With the inclusion of the“modal”aspect,there are four single aspects:“simple”,“modal”,“perfect”and“continuous”.They can be combined to form multiple aspects according to the aforesaid ***“modal”aspect is realized with a modal verb(any ofthe modal verbs will/would,shall/should,can/could,may/might,must,ought to,used to and the two semi-modals,“need”and“dare”in interrogative and negative structures).Whenever a modal verb is used,the verb phrase is in the modal *** modal verb to be used is for the interlocutor to decide and falls beyond this discussion,which focuses on the structure of the fVP of the English *** two tenses,eight aspects and two voices(active and passive)make up the 32 TAVs(an acronym formed with“Tense”,“Aspect”and“Voice”)of the English ***“discovery”of the“modal”aspect and its incorporation in the aspect system of English might have a significant impact on the learning of English for non-native speakers as they would have a clearer and more precise concept about the“TAVs”of the English fVP.

关键词： English verb phrase finite verb phrase tense aspect mood modality modal verb TAV

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磷酸二酯酶抑制剂诱导的大鼠胰岛素抵抗对糖脂代谢的影响

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中国病理生理杂志 2003年第7期19卷 875-880页

作者：杨刚毅李伶 peter chung Gangther Boden 重庆医科大学附属第二医院内分泌科重庆400010 重庆医科大学检验系重庆400010 美国Temple大学医学院

目的 :探讨选择性磷酸二酯酶III(PDE3 )抑制剂米力农 (milrinone)对大鼠胰岛素分泌、血糖、血浆游离脂肪酸 (FFA)的影响和剂量依赖关系 ,及其在胰岛素钳夹状态下对大鼠糖代谢和胰岛素敏感性的影响。方法 :由植入导管给予大鼠不同剂量的... 详细信息

目的 :探讨选择性磷酸二酯酶III(PDE3 )抑制剂米力农 (milrinone)对大鼠胰岛素分泌、血糖、血浆游离脂肪酸 (FFA)的影响和剂量依赖关系 ,及其在胰岛素钳夹状态下对大鼠糖代谢和胰岛素敏感性的影响。方法 :由植入导管给予大鼠不同剂量的米力农 ( 1、5、2 5 μmol/kg)在不同时相测定血糖、血浆FFA和胰岛素水平并与对照组比较。在清醒状态下建立大鼠高胰岛素 -正常血糖钳夹技术 ,并在钳夹 12 0min时分别经导管给予米力农 ( 2 5 μmol/kg)和 2 5 %二甲基亚砜 (DMSO ,对照组 )。采用气相色谱 -质谱仪 (GC -MS)测定糖代谢率。结果 :3个不同剂量米力农组血浆FFA浓度明显高于对照组和给药前 ,在注射后 2min ,各组FFA升高的百分数为 :5 0 %、5 2 %、5 5 % ( 1、5、2 5μmol/kg)。在 5、2 5 μmol/kg组血浆胰岛素水平也明显高于对照组和给药前 ,仅 2 5 μmol/kg组血糖浓度高于对照组和给药前。在胰岛素钳夹研究中 ,米力农处理组大鼠血浆FFA明显高于给药前 ,肝糖输出 (HGP)也明显高于给药前。葡萄糖输注率 (GIR)明显低于对照组和给药前。结论 :米力农损害了胰岛素抑制脂解和肝糖输出的能力及胰岛素介导的外周组织糖的利用。因此。

关键词：米力农磷酸二酯酶抑制剂胰岛素

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清醒大鼠胰岛素钳夹术及其糖代谢变化

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基础医学与临床 2003年第3期23卷 341-344页

作者：杨刚毅 peter chung Guenther Boden 重庆医科大学第二医院内分泌科重庆400010 美国Temple大学医学院 philadelphia19140

为准确地评价在体组织对胰岛素 (Ins)的敏感性及探讨在胰岛素抵抗 (IR)状态下机体糖代谢变化。采用 6 ,6 D2 葡萄糖作为示踪剂 ,建立了自由状态下大鼠正常血糖 -高胰岛素钳夹术 ,并动态观察了其体内糖代谢的动态改变及血浆游离脂肪酸 (... 详细信息

为准确地评价在体组织对胰岛素 (Ins)的敏感性及探讨在胰岛素抵抗 (IR)状态下机体糖代谢变化。采用 6 ,6 D2 葡萄糖作为示踪剂 ,建立了自由状态下大鼠正常血糖 -高胰岛素钳夹术 ,并动态观察了其体内糖代谢的动态改变及血浆游离脂肪酸 (FFA)和Ins浓度随时间变化的过程。大鼠在 4 8mU (kg·min)速率Ins输注下 ,血糖稳定在正常水平而肝糖输出被抑制 ,胰岛素介导的机体葡萄糖利用率较基础状态显著增加 ,游离脂肪酸 (FFA)浓度显著下降。本钳夹术平均血糖变异系数为 5 76 %。平均GIR变异系数为 6 2 5 % ,GRd为 9 17%。重复试验GIR与GRd误差范围为 1 2 %和 1 7%。以 6 ,6 D2 葡萄糖作为示踪剂建立的自由状态下的大鼠正常血糖钳夹技术具有准确、可靠 ,无放射污染等优点 ,在外源性胰岛素 -葡萄糖代谢稳定状态下 ,机体对葡萄糖利用显著增加 ,脂肪分解显著减少。

关键词：大鼠胰岛素钳夹术糖代谢胰岛素抵抗血浆游离脂肪酸

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Management of Malnutrition in Liver Cancer Patients with Chronic Liver Diseases

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Journal of Nutritional Oncology 2016年第1期1卷 21-29页

作者： Asa’d Dajani Laura Kassym peter chung Adnan Abu Hammour Asad Dajani Specialist Center Sharjah United Arab Emirates Semey State University Semey Kazakhstan The Ninth Peoples Hospital Shanghai Jiaotong University Shanghai China Abu Hammour Medical Center Dubai United Arab Emirates

Liver cancer is the fifth most common cancer and the third leading cause of cancer death globally. Malnutrition is found in 65-90% of patients with liver cancer and often enhances cancer occurrence and complications, deteriorates liver functions, and promotes early development of refractory ascites and hepatic encephalopathy (HE), increasing both morbidity and mortality. Malnutrition may develop as a result of poor dietary intake, anorexia, medications, side effects to chemotherapy, encephalopathy, as well as socioeconomic limitations. A dedicated clinical team should provide proper assessment of patient’s nutritional status and nutrition supplemental plan to restore liver health and prevent or treat malnutrition. Nutrition assessment is based on medical, nutritional, and medication histories, physical examination for body composition and signs of malnutrition, anthropometric measurements, radio-imaging, laboratory tests, and flow charts or algorithms on patient’s dietary intake and changes in bodyweight. Clinical management depends on patient’s disease and nutritional status. Patients with minor liver affection or compensated liver cirrhosis may have normal diet without any restrictions in carbohydrates, proteins, and fat, but preferably take other supplements supporting the liver. Patients with decompensated liver should consume 25-40 kcal/kg/day and 1.0-1.5 g protein/kg/day. For patients with acute episodes of HE, a temporary protein restriction of 0.6-0.8 g/kg/day should be implemented until HE is eliminated. Patients should consume small, frequent meals throughout the day and add a carbohydrate- and protein-rich evening snack. Other approaches to supporting optimal digestion and nutrition and managing side effects of cancer therapies may be added as well.

关键词： Liver cancer Malnutrition Liver cirrhosis Hepatic encephalopathy Nutrition assessment Nutrition intervention Cancer therapy

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灵芝孢子对帕金森氏病的保护作用

灵芝孢子对帕金森氏病的保护作用

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2004灵芝专题研讨会

作者： peter chung 上海第二医科大学

帕金森氏病是一种通常发生于40岁后的退行性疾病。临床症状包括神经递质的逐渐损耗、嘴唇和双手颤抖以及面部表情刻板。病理学表现为黑质、黑质未名区、蓝斑核和颅神经X的脊运动神经元中有色神经元群的神经细胞缓慢破坏。目前治疗帕金...

帕金森氏病是一种通常发生于40岁后的退行性疾病。临床症状包括神经递质的逐渐损耗、嘴唇和双手颤抖以及面部表情刻板。病理学表现为黑质、黑质未名区、蓝斑核和颅神经X的脊运动神经元中有色神经元群的神经细胞缓慢破坏。目前治疗帕金森氏病的药物有抗胆碱能药、金刚胺、左旋多巴合用卡比多巴。然而,这些药物的药效会慢慢减弱而且还有例如运动综合症的副作用。本研究的目的是寻找药物减缓黑质神经元细胞的改变和加速这些细胞的修

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