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| 1 | Role of Sonic Hedgehog signaling during progression from inflammation to cancer in the stomach显示文摘Despite advances in treatment and the declining incidence,gastric cancer remains the second leading cause of cancer-related deaths in the world.Understanding the progression from inflammation to cancer in the stomach is crucial in the development of novel therapies and strategies for treating this disease.Chronic inflammation of the stomach is typically caused by Helicobacter pylori(H.pylori)and resulting lesions may lead to gastric cancer.During the progression from inflammation to cancer,the stomach epithelium changes with evidence of the disruption of normal epithelial cell differentiation and infiltrating inflammatory cells.Coincident with the development of atrophic gastritis and metaplasia,is the loss of the gastric morphogen Sonic Hedgehog(Shh).Given its critical role as a regulator of gastric tissue homeostasis,the disruption of Shh expression during inflammation correlates with the loss of normal epithelial cell differentiation,but this has only recently been rigorously tested in vivo using a unique mouse model of targeted gastric Shh deletion.While pre-neoplastic lesions such as atrophic gastritis and in-testinal metaplasia are associated with the loss of Shh within the acid-secreting glands of the stomach,there is a clear link between elevated Shh and signaling to gastric cancers.The current review focuses on the effects of aberrant Shh expression and its role in the development of gastric cancer,specifically in response to H.pylori infection. | Alexander E Sherman Yana Zavros | 2011 | World Journal of Gastrointestinal Pathophysiology2011，2，6： | 14 |
| 2 | Diagnosis of gastrointestinal bleeding: A practical guide for clinicians显示文摘Gastrointestinal bleeding is a common problem encountered in the emergency department and in the primary care setting. Acute or overt gastrointestinal bleeding is visible in the form of hematemesis, melena or hematochezia. Chronic or occult gastrointestinal bleeding is notapparent to the patient and usually presents as positive fecal occult blood or iron deficiency anemia. Obscure gastrointestinal bleeding is recurrent bleeding when the source remains unidentified after upper endoscopy and colonoscopic evaluation and is usually from the small intestine. Accurate clinical diagnosis is crucial and guides definitive investigations and interventions. This review summarizes the overall diagnostic approach to gastrointestinal bleeding and provides a practical guide for clinicians. | Bong Sik Matthew Kim Bob T Li Alexander Engel Jaswinder S Samra Stephen Clarke Ian D Norton Angela E Li | 2014 | World Journal of Gastrointestinal Pathophysiology2014，5，4： | 13 |
| 3 | Proton pump inhibitor-associated pneumonia:Not a breath of fresh air after all?显示文摘Over the past two decades,proton pump inhibitors (PPIs)have emerged as highly effective and relatively safe agents for the treatment of a variety of gastrointestinal disorders.Unfortunately,this desirable pharmacological profile has also contributed to superfluous and widespread use in both the inpatient and outpatient settings.While generally well-tolerated,research published over the last decade has associated these agents with increased risks of Clostridium difficile disease, fractures likely due to calcium malabsorption and both community-acquired(CAP)and hospital-acquired pneumonias(HAP).The mechanism behind PPI-associated pneumonia may be multifactorial,but is thought to stem from compromising the stomach's'acid mantle'against gastric colonization of acid-labile pathogenic bacteria which then may be aspirated.A secondary postulate is that PPIs,through their inhibition of extra-gastric H+/K+ATPase enzymes,may reduce the acidity of the upper aerodigestive tract,thus resulting in increased bacterial colonization of the larynx,esophagus and lungs.To date,several retrospective case control studies have been published looking at the association between PPI use and CAP.Some studies found a temporal relationship between PPI exposure and the incidence of pneumonia,but only two could define a dose-response re-lationship.Furthermore,other studies found an inverse correlation between duration of PPI use and risk of CAP. In terms of HAP,we reviewed two retrospective cohort studies and one prospective study.One retrospective study in a medical ICU found no increased association of HAP in PPI-exposed patients compared to no acid-lowering therapy,while the other in cardiothoracic surgery patients showed a markedly increased risk compared to those receiving H2RAs.The one prospective study in ICU patients showed an increased risk of HAP with PPIs, but not with H2RAs.In conclusion,the current literature shows a slight trend toward an association between PPI use and pneumonia and an increased risk with PPIs over H2RAs,but the findings are not consistent across all studies.Larger controlled trials still need to be done to better identify the risk that PPIs impart towards patients contracting CAP or HAP.Until these are completed, we will have to continue to extrapolate across smaller controlled trials to predict the associated risks in our respective patient populations.In the interim,it appears prudent to limit the use of PPIs to situations where they are clinically indicated and,in such cases,use them at the lowest effective dose.In the case of prescribing for stress ulcer prophylaxis in ICU patients,perhaps H2RAs should be used as the preferred agents over PPIs. | Alexander L Fohl Randolph E Regal | 2011 | World Journal of Gastrointestinal Pharmacology and Therapeutics2011，2，3： | 12 |
| 4 | Role of the endothelium in inflammatory bowel diseases显示文摘Inflammatory bowel diseases(IBD) are a complex group of diseases involving alterations in mucosal immunity and gastrointestinal physiology during both initiation and progressive phases of the disease.At the core of these alterations are endothelial cells,whose continual adjustments in structure and function coordinate vascular supply,immune cell emigration,and regulation of the tissue environment.Expansion of the endothelium in IBD(angiogenesis),mediated by inflammatory growth factors,cytokines and chemokines,is a hallmark of active gut disease and is closely related to disease severity.The endothelium in newly formed or inflamed vessels differs from that in normal vessels in the production of and response to inflammatory cytokines,growth factors,and adhesion molecules,altering coagulant capacity,barrier function and blood cell recruitment in injury.This review examines the roles of the endothelium in the initiation and propagation of IBD pathology and distinctive features of the intestinal endothelium contributing to these conditions. | Walter E Cromer J Michael Mathis Daniel N Granger Ganta V Chaitanya J Steven Alexander | 2011 | World Journal of Gastroenterology2011，17，5： | 10 |
| 5 | Prolonged high-fat-diet feeding promotes non-alcoholic fatty liver disease and alters gut microbiota in mice显示文摘BACKGROUND Non-alcoholic fatty liver disease (NAFLD) has become an epidemic largely due to the worldwide increase in obesity. While lifestyle modifications and pharmacotherapies have been used to alleviate NAFLD, successful treatment options are limited. One of the main barriers to finding safe and effective drugs for long-term use in NAFLD is the fast initiation and progression of disease in the available preclinical models. Therefore, we are in need of preclinical models that (1) mimic the human manifestation of NAFLD and (2) have a longer progression time to allow for the design of superior treatments. AIM To characterize a model of prolonged high-fat diet (HFD) feeding for investigation of the long-term progression of NAFLD. METHODS In this study, we utilized prolonged HFD feeding to examine NAFLD features in C57BL/6 male mice. We fed mice with a HFD (60% fat, 20% protein, and 20% carbohydrate) for 80 wk to promote obesity (Old-HFD group, n = 18). A low-fat diet (LFD)(14% fat, 32% protein, and 54% carbohydrate) was administered for the same duration to age-matched mice (Old-LFD group, n = 15). An additional group of mice was maintained on the LFD (Young-LFD, n = 20) for a shorter duration (6 wk) to distinguish between age-dependent and age-independent effects. Liver, colon, adipose tissue, and feces were collected for histological and molecular assessments.RESULTS Prolonged HFD feeding led to obesity and insulin resistance. Histological analysis in the liver of HFD mice demonstrated steatosis, cell injury, portal and lobular inflammation and fibrosis. In addition, molecular analysis for markers of endoplasmic reticulum stress established that the liver tissue of HFD mice have increased phosphorylated Jnk and CHOP. Lastly, we evaluated the gut microbial composition of Old-LFD and Old-HFD. We observed that prolonged HFD feeding in mice increased the relative abundance of the Firmicutes phylum. At the genus level, we observed a significant increase in the abundance of Adercreutzia, Coprococcus, Dorea, and Ruminococcus and decreased relative abundance of Turicibacter and Anaeroplasma in HFD mice. CONCLUSION Overall, these data suggest that chronic HFD consumption in mice can mimic pathophysiological and some microbial events observed in NAFLD patients. | Kandy T Velázquez Reilly T Enos Jackie E Bader Alexander T Sougiannis Meredith S Carson Ioulia Chatzistamou James A Carson Prakash S Nagarkatti Mitzi Nagarkatti E Angela Murphy | 2019 | World Journal of Hepatology2019，11，8： | 6 |
| 6 | 纤维母细胞生长因子对复合皮肤移植成活和收缩的影响显示文摘我们曾报道应用同基因表层皮片(IE)和同种异基因真皮(AD)组成复合皮肤移植物(CSG)可一次完成全层皮肤缺损的永久性修复。但由于IE不能及时获得足够血运,IE常有部分坏死,CSG后期收缩仍较明显。在本研究中我们进一步用纤维母细胞生长因子(FGF)预先处理AD获得较好效果。经观察17周表明,FGF组皮片坏死率和坏死面积较对照组明显下降(P<0.05);FGF组CSG收缩较对照组明显减轻(P<0.001);皮片坏死面积与皮片最终面积呈负相关(r=-0.450,P<0.05)。实验预示,完全成活的CSG后期收缩较移植同等厚度的IE为轻。观察2年,AD未被排斥。 | 方承辉 Robb E C 于光曙 Alexander J W Warden G D | 1993 | 中华整形烧伤外科杂志1993，9，1： | 6 |
| 7 | Clinical outcomes following salvage Gamma Knife radiosurgery for recurrent glioblastoma显示文摘Glioblastoma multiforme(GBM) is the most common malignant primary brain tumor with a survival prognosis of 14-16 mo for the highest functioning patients. Despite aggressive, multimodal upfront therapies, the majority of GBMs will recur in approximately six months. Salvage therapy options for recurrent GBM(r GBM) are an area of intense research. This study compares recent survival and quality of life outcomes following Gamma Knife radiosurgery(GKRS) salvage therapy. Following a Pub Med search for studies usingGKRS as salvage therapy for malignant gliomas, nine articles from 2005 to July 2013 were identified which evaluated rG BM treatment. In this review, we compare overall survival following diagnosis, overall survival following salvage treatment, progression-free survival, time to recurrence, local tumor control, and adverse radiation effects. This report discusses results for rG BM patient populations alone, not for mixed populations with other tumor histology grades. All nine studies reported median overall survival rates(from diagnosis, range:16.7-33.2 mo; from salvage, range:9-17.9 mo). Three studies identified median progression-free survival(range:4.6-14.9 mo). Two showed median time to recurrence of GBM. Two discussed local tumor control. Six studies reported adverse radiation effects(range:0%-46% of patients). The greatest survival advantages were seen in patients who received GKRS salvage along with other treatments, like resection or bevacizumab, suggesting that appropriately tailored multimodal therapy should be considered with each rG BM patient. However, there needs to be a randomized clinical trial to test GKRS for rG BM before the possibility of selection bias can be dismissed. | Erik W Larson Halloran E Peterson Wayne T Lamoreaux Alexander R MacKay Robert K Fairbanks Jason A Call Jonathan D Carlson Benjamin C Ling John J Demakas Barton S Cooke Christopher M Lee | 2014 | World Journal of Clinical Oncology2014，5，2： | 5 |
| 8 | Stable ischemic heart disease in the older adults显示文摘1 Introduction Ischemic heart disease is caused by atherosclerotic and/or thrombotic obstruction of coronary arteries.Clinical spectrum of ischemic heart disease expands from asymptomatic atherosclerosis of coronary arteries to acute coronary syndromes (ACS) including unstable angina,acute myocardial infarction (non-ST elevation myocardial infarction and ST elevation myocardial infarction). | Xuming DAI Jan Busby-Whitehead Daniel E Forman Karen P Alexander | 2016 | Journal of Geriatric Cardiology2016，13，2： | 5 |
| 9 | 血栓素(thromboxane)合成酶抑制剂——Dazmegrel(UK38,485)对烧伤皮肤血流灌注的影响显示文摘近十年来,血栓素(thromboxane)被认为在烧伤后真皮进行性缺血过程中起重要作用,有报导前列腺素、血栓素抑制剂可改善局部血循环,从而促进深Ⅱ度烧伤刨而愈合。本实验以啄鼠深Ⅱ度烧伤模型,肌注血栓素合成酶抑制剂Dazmegrel(UK38,485或uk)3.4mg/kg/天(UK3.4mg)、10mE/kg/天(UK10mg)、或30mg/kg/天(UK30mg),使用印度墨汁灌注及UK-133(氙-133)清除试验,未发现Dazfilegrel能改善烧伤局部血流。这与有的实验结论不同,肌注Dazmegrel 3.4rag/kg/天的促进烧伤创面愈合作用,不是由于该药改善局部血流量所致。此外,Xe-133清除试验示伤后7小时深Ⅱ度烧伤皮肤血流量有一明显下降过程,伤后24小时则有一明显增加过程,如何认识及应用这一'先低后高。现象,对促进深Ⅱ度烧伤创面愈合显然是有意义的。 | 汪仕良 黎鳌 Alexander JW Silberstein EB Robb E Lukes S Trocki O Ogle DK 邹万忠 | 1989 | 中华整形烧伤外科杂志1989，5，3： | 3 |
| 10 | Control of stem cell fate by engineering their micro and nanoenvironment显示文摘Stem cells are capable of long-term self-renewal and differentiation into specialised cell types, making them an ideal candidate for a cell source for regenerative medicine. The control of stem cell fate has become a major area of interest in the field of regenerative medicine and therapeutic intervention. Conventional methods of chemically inducing stem cells into specific lineages is being challenged by the advances in biomaterial technology, with evidence highlighting that material properties are capable of driving stem cell fate. Materials are being designed to mimic the clues stem cells receive in their in vivo stem cell niche including topographical and chemical instructions. Nanotopographical clues that mimic the extracellular matrix(ECM) in vivo have shown to regulate stem cell differentiation. The delivery of ECM components on biomaterials in the form of short peptides sequences has also proved successful in directing stem cell lineage. Growth factors responsible for controlling stem cell fate in vivo have also been delivered via biomaterials to provide clues to determine stem cell differentiation. An alternative approach to guide stem cells fate is to provide genetic clues including delivering DNA plasmids and small interfering RNAs via scaffolds. This review, aims to provide an overview of the topographical, chemical and molecular clues that biomaterials can provide to guide stem cell fate. The promising features and challenges of such approaches will be highlighted, to provide directions for future advancements in this exciting area of stem cell translation for regenerative medicine. | Michelle F Griffin Peter E Butler Alexander M Seifalian Deepak M Kalaskar | 2015 | World Journal of Stem Cells2015，7，1： | 3 |
| 11 | Long-term survival of a patient after resection of a gastrointestinal stromal tumor arising from the pancreas显示文摘BACKGROUND:Gastrointestinal stromal tumors (GISTs) may arise in any part of the gastrointestinal tract;extragastrointestinal locations are extremely rare.Only a few cases of extragastrointestinal stromal tumor arising from the pancreas were reported.None of the reports described a long-term follow-up of the patients.METHOD:This report describes an interesting and unusual case of GIST arising from the pancreas.RESULTS:A 74-year-old female presented with a palpable abdominal mass.CT scan showed a large mass 11×8×4 cm originating from the tail of the pancreas.Percutaneous biopsy revealed a GIST predominantly with spindle cells,but some parts also contained epitheloid cells.The patient was treated by distal pancreatic resection with splenectomy.Immunohistochemistry of the tumor showed a staining pattern characteristic of GIST.The patient has achieved a long-term survival of five years and six months without any sign of recurrence of the disease.CONCLUSION:This is the first reported case of an extragastrointestinal stromal tumor arising from the pancreas treated surgically,with a long-term survival. | Filip eka Bohumil Jon Alexander Ferko Zdeněk ubrt Dimitar H Nikolov Věra Tyová | 2011 | Hepatobiliary & Pancreatic Diseases International2011，10，3： | 3 |
| 12 | Staining for p53 and Ki-67 increases the sensitivity of EUS-FNA to detect pancreatic malignancy显示文摘AIM:To investigate whether tumor marker staining can improve the sensitivity of endoscopic ultrasound-guided fine needle aspiration(EUS-FNA)to diagnose pancreatic malignancy. METHODS:Patients who underwent EUS-FNA were retrospectively identified.Each EUS-FNA specimen was evaluated by routine cytology and stained for tumor markers p53,Ki-67,carcinoembryonic antigen(CEA) and CA19-9.Sensitivity,specificity,positive and negative predictive values(PPV and NPV),and positive and negative likelihood ratios(PLR and NLR)were calculated in order to evaluate the performance of each test to detect malignancy. RESULTS:Sixty-one specimens had complete sets of stains,yielding 49 and 12 specimens from pancreatic adenocarcinomas and benign pancreatic lesions due to pancreatitis,respectively.Cytology alone had sensitivity and specificity of 41%and 100%to detect malignancy, respectively.In 46%of the specimens,routine cytology alone was deemed indeterminate.The addition of either p53 or Ki-67 increased the sensitivity to 51%and 53%,respectively,with perfect specificity,PPV and PLR (100%,100%and infinite).Both stains in combination increased the sensitivity to 57%.While additional staining with CEA and CA19-9 further increased the sensitivity to 86%,the specificity,PPV and PLR were significantly reduced(at minimum 42%,84%and 1,respectively).Markers in all combinations performed poorly as a negative test(NPV 26%to 47%,and NLR 0.27 and 0.70).CONCLUSION:Immunohistochemical staining for p53 and Ki-67 can improve the sensitivity of EUS-FNA to diagnose pancreatic adenocarcinoma. | Alexander W Jahng Sonya Reicher David Chung Donna Varela Rahul Chhablani Anil Dev Binh Pham Jose Nieto Rose J Venegas Samuel W French Bruce E Stabile Viktor E Eysselein | 2010 | World Journal of Gastrointestinal Endoscopy2010，2，11： | 3 |
| 13 | Revisiting normal perfusion pressure breakthrough in light of hemorrhage-induced vasospasm显示文摘Cerebral arteriovenous malformations(AVMs) have abnormally enlarged arteries and veins prone to spontaneous hemorrhage.Immediately following surgical excision of a cerebral AVM,even normal brain tissue surrounding the lesion is subject to hemorrhage,a phenomenon termed normal perfusion pressure breakthrough(NPPB) syndrome.According to this theory,arteries supplying cerebral AVMs become dilated and lose their capacity to dilate or constrict to autoregulate pressure.Acutely after removal of a cerebral AVM,excessive blood pressure in these arterial feeders can cause normal brain tissue to bleed.However,this theory remains controversial.We present a patient with a cerebral AVM that demonstrated cerebrovascular reactivity and argues against an assumption underlying the theory of NPPB syndrome. | Matthew D Alexander E Sander Connolly Philip M Meyers | 2010 | World Journal of Radiology2010，2，6： | 3 |
| 14 | Should antibiotics be administered before arthroscopic knee surgery? A systematic review of the literature显示文摘AIM To explore the current evidence surrounding the administration of prophylactic antibiotics for arthroscopic knee surgery. METHODS Databases were searched from inception through May of 2018 for studies examining prophylactic antibiotic use and efficacy in knee arthroscopy. Studies with patient data were further assessed for types of arthroscopic procedures performed,number of patients in the study,use of antibiotics,and outcomes with the intention of performing a pooled analysis. Data pertaining to 'deep tissue infection' or 'septic arthritis' were included in our analysis. Reported data on superficial infection were not included in our data analysis. For the pooled analysis,a relative risk ratio was calculated and χ~2 tests were used to assess for statistical significance between rates of infection amongst the various patient groups. Post hoc power analyses were performed to compute the statistical power obtained from our sample sizes. Number needed to treat analyses were performed for statistically significant differences by dividing 1 by the difference between the infection rates of the antibiotic and no antibiotic groups. An alpha value of 0.05 was used for our analysis. Study heterogeneity was assessed by Cochrane's Q test as well as calculation of the I^2 value.RESULTS A total of 49682 patients who underwent knee ar-throscopy for a diverse set of procedures across 19 studies met inclusion critera for pooled analysis. For those not undergoing graft procedures,there were 27 cases of post-operative septic arthritis in 34487 patients(0.08%) who received prophylactic antibiotics and 16 cases in 10911(0.15%) who received none [risk ratio(RR) = 0.53,95% confidence interval(CI): 0.29-0.99,P = 0.05]. A sub-group analysis in which bony procedures were excluded was performed which found no significant difference in infection rates between patients that received prophylactic antibiotics and patients that did not(P > 0.05). All anterior cruciate ligament reconstruction studies used prophylactic antibiotics,but two studies investigating the effect of soaking the graft in vancomycin in addition to standard intravenous(IV) prophylaxis were combined for analysis. There were 19 cases in 1095 patients(1.74%) who received IV antibioitics alone and no infections in 2034 patients who received IV antibiotics and had a vancomycin soaked graft(RR = 0.01,95%CI: 0.001-0.229,P < 0.01).CONCLUSION Prophylactic antibiotics are effective in preventing septic arthritis following simple knee arthroscopy. In procedures involving graft implantation,graft soaking reduces the rate of infection. | John Carney Nathanael Heckmann Erik N Mayer Ram K Alluri Carleton Thomas Vangsness George F Hatch Ⅲ Alexander E Weber | 2018 | World Journal of Orthopedics2018，9，11： | 2 |
| 15 | 向公众传达地震风险:“拉奎拉7人”的审判显示文摘对意大利中部拉奎拉7名公职人员的审判和定罪,据称是因为在2009年4月6日地震之前对公众给出了令人误解的和不正确的信息,已被证明是最近一段时间在科学与减少灾害风险方面最重要的发展之一,同时也是最令人误解的事件之一。它突出地展现了将地球科学中普遍的带有不确定性特征的发现转换成保护普通公民的信息的困难。本文介绍有关在拉奎拉地震灾难中及随后的审判和法律诉讼程序中的那些情况。分析审判的政治、社会和科学方面,以及意大利和其他国家的科学家和他们单位的反应。我认为被告应是负有责任的公职人员,而不是科学家。意大利和国外大众媒体倾向于坚持审判的是预测地震的能力,这对各国科学家的意见也产生了极大地影响。然而,正如检察官所说,实际上审判的是用'不完整的、不准确的和相互矛盾的信息'误导公众导致明显地致命的后果。我相信对审判的很多国际反应是被有关诉讼程序的不完整的二手信息所误导。如果科学家们在他们自己的工作上以如此肤浅的方式做判断,结果也会非常不可靠,而公众对科学的信任将会直线下跌。 | David E Alexander 姚雪绒 张天中 | 2014 | 国际地震动态2014，，5： | 2 |
| 16 | Surgical Technique in Distal Pancreatectomy: A Systematic Review of Randomized Trials显示文摘 | Filip ?e?ka Bohumil Jon Zdeněk ?ubrt Alexander Ferko Masahiko Hirota | 2014 | BioMed Research International2014，，： | 2 |
| 17 | Developing a low-cost milliliter-scale chemostat array for precise control of cellular growth显示文摘 | David Skelding Samuel F M Hart Thejas Vidyasagar Alexander E Pozhitkov Wenying Shou | 2018 | Frontiers of Electrical and Electronic Engineering in China2018，6，2： | 2 |
| 18 | Label-retaining liver cancer cells are relatively resistant to sorafenib显示文摘 | Hong-Wu Xin Chenwi M Ambe Danielle M Hari Gordon W Wiegand Tyler C Miller Jin-Qiu Chen Andrew J Anderson Satyajit Ray John E Mullinax Tomotake Koizumi Russell C Langan Douglas Burka Michelle A Herrmann Paul K Goldsmith Alexander Stojadinovic Udo Rudloff S | 2013 | Gut2013，，12： | 2 |
| 19 | Excluding infection through procalcitonin testing improves outcomes of congestive heart failure patients presenting with acute respiratory symptoms: Results from the randomized ProHOSP trial显示文摘 | Philipp Schuetz Alexander Kutz Eva Grolimund Sebastian Haubitz Désirée Demann Alaadin V?geli Fabienne Hitz Mirjam Christ-Crain Robert Thomann Claudine Falconnier Claus Hoess Christoph Henzen Robert J. Marlowe Werner Zimmerli Beat Mueller | 2014 | International Journal of Cardiology2014，，3： | 2 |
| 20 | Transient thermal analysis as measurement method for IC package structural integrity显示文摘Practices of IC package reliability testing are reviewed briefly,and the application of transient thermal analysis is examined in great depth.For the design of light sources based on light emitting diode(LED) efficient and accurate reliability testing is required to realize the potential lifetimes of 105 h.Transient thermal analysis is a standard method to determine the transient thermal impedance of semiconductor devices,e.g.power electronics and LEDs.The temperature of the semiconductor junctions is assessed by time-resolved measurement of their forward voltage(Vf).The thermal path in the IC package is resolved by the transient technique in the time domain.This enables analyzing the structural integrity of the semiconductor package.However,to evaluate thermal resistance,one must also measure the dissipated energy of the device(i.e.,the thermal load) and the k-factor.This is time consuming,and measurement errors reduce the accuracy.To overcome these limitations,an innovative approach,the relative thermal resistance method,was developed to reduce the measurement effort,increase accuracy and enable automatic data evaluation.This new way of evaluating data simplifies the thermal transient analysis by eliminating measurement of the k-factor and thermal load,i.e.measurement of the lumen flux for LEDs,by normalizing the transient Vfdata.This is especially advantageous for reliability testing where changes in the thermal path,like cracks and delaminations,can be determined without measuring the k-factor and thermal load.Different failure modes can be separated in the time domain.The sensitivity of the method is demonstrated by its application to highpower white In GaN LEDs.For detailed analysis and identification of the failure mode of the LED packages,the transient signals are simulated by time-resolved finite element(FE) simulations.Using the new approach,the transient thermal analysis is enhanced to a powerful tool for reliability investigation of semiconductor packages in accelerated lifetime tests and for inline inspection.This enables automatic data analysis of the transient thermal data required for processing a large amount of data in production and reliability testing.Based on the method,the integrity of LED packages can be tested by inline,outgoing inspection and the lifetime prediction of the products is improved. | Alexander Han Maximilian Schmid E Liu Gordon Elger | 2015 | Chinese Physics B2015，24，6： | 2 |
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