Intrinsic polarization conversion and avoided-mode crossing in X-cut lithium niobate microrings

Compared with well-developed free space polarization converters, polarization conversion between TE and TM modes in the waveguide is generally considered to be caused by shape birefringence, like curvature, morphology of waveguide cross section and scattering. Here, we study the polarization conversion mechanism in 1-THz-FSR X-cut lithium niobate microrings with multiple-resonance condition, that is the conversion can be implemented by birefringence of waveguides,which will also introduce an avoided-mode crossing. In the experiment, we find that this mode crossing results in severe suppression of one sideband in local nondegenerate four-wave mixing and disrupts the cascaded four-wave mixing on this side. Simultaneously, we propose one two-dimensional method to simulate the eigenmodes(TE and TM) in X-cut microrings, and the mode crossing point. This work will provide one approach to the design of polarization converters and simulation for monolithic photonics integrated circuits, and may be helpful to the studies of missed temporal dissipative soliton formation in X-cut lithium niobate rings.

Immune checkpoint inhibitor-related hepatotoxicity:A review

The application of immune checkpoint inhibitors(ICI)in advanced cancer has been a major development in the last decade.The indications for ICIs are constantly expanding into new territory across different cancers,disease stages and lines of therapy.With this increased use,adverse events including immune checkpoint inhibitor-related hepatotoxicity(ICH)have emerged as an important clinical problem.This along with the introduction of ICI as first-and second-line treatments for advanced hepatocellular carcinoma makes ICH very relevant to gastroenterologists and hepatologists.The incidence of ICH varies between 1%-20%depending on the number,type and dose of ICI received.Investigation and management generally involve excluding differential diagnoses and following a stepwise escalation of withholding or ceasing ICI,corticosteroid treatment and adding other immunosuppressive agents depending on the severity of toxicity.The majority of patients with ICH recover and some may even safely recommence ICI therapy.Guideline recommendations are largely based on evidence derived from retrospective case series which highlights a priority for future research.

Evaluation and outcomes of patients with obscure gastrointestinal bleeding

Obscure gastrointestinal bleeding(OGIB) is defined as recurrent or persistent bleeding or presence of iron deficiency anaemia after evaluation with a negative bidirectional endoscopy. OGIB accounts for 5% of gastrointestinal bleeding and presents a diagnostic challenge. Current modalities available for the investigation of OGIB include capsule endoscopy, balloon assisted enteroscopy, spiral enteroscopy and computed tomography enterography. These modalities overcome the limitations of previous techniques. Following a negative bidirectional endoscopy, capsule endoscopy and double balloon enteroscopy remain the cornerstone of investigation in OGIB given their high diagnostic yield. Longterm outcome data in patients with OGIB is limited, but is most promising for capsule endoscopy. This article reviews the current literature and provides an overview of the clinical evaluation of patients with OGIB, available diagnostic and therapeutic modalities and longterm clinical outcomes.

Prevalence and outcomes of pancreatic cystic neoplasms in liver transplant recipients

AIM To determine the prevalence,characteristics and clinical course of pancreatic cystic neoplasms(PCNs) in liver transplantation(LT) recipients.METHODS We retrospectively studied consecutive patients who underwent LT between January 1998 to April 2016. Clinical and laboratory data were obtained from patient medical records. Imaging findings on computed tomography and magnetic resonance cholangiopancreatography were reviewed by two radiologists.RESULTS During the study period,872 patients underwent cadaveric LT. Pancreatic cysts were identified in 53/872(6.1%) and 31/53(58.5%) were PCNs [28 intraductal papillary mucinous neoplasm(IPMN),2 mucinous cystic neoplasm(MCN),1 serous cystadenoma]. Patients with PCNs exhibited less male predominance(55% vs 73%,P = 0.03) compared to patients without pancreatic cysts. Thirteen patients(42%) were diagnosed with PCN pre-LT while 18 patients(58%) developed PCN post-LT. The median size of PCNs was 13 mm [interquartile range(IQR) 10-20 mm]. All IPMNs were side-branch type. Most PCNs were found in the head and body of pancreas(37% each),followed by the tail(25%). Five patients underwent further evaluation with endoscopic ultrasound. Progress imaging was performed on 81% of patients. PCNs remained stable in size and number in all but 2 patients. During a median follow up of 39 mo(IQR 26-58 mo),the 2(6%) patients with MCN underwent pancreatectomy. No PCN patient developed pancreatic adenocarcinoma,while 5 died from illnesses unrelated to the PCN. Among patients without PCN,1/841(0.1%) developed pancreatic adenocarcinoma.CONCLUSION The prevalence of PCNs in LT recipients was similar to the general population(3.6%,31/872). Side-branch IPMNs do not appear to have accelerated malignant potential in post-LT patients,indicating the current surveillance guidelines are applicable to this group.

Aligning Fe_(2)O_(3)photo-sheets on TiO_(2)nanofibers with hydrophilic and aerophobic surface for boosting photoelectrochemical performance

Photoelectrochemical(PEC)nanomaterials are critical to producing clean oxygenation or value-added chemical production by utilizing sustainable solar energy,but are always limited by simultaneous integration of architectural engineering and electronic regulation in one structure.Directed by density functional theory(DFT)calculations and finite element analysis(FEA),the bioinspired ivy-like Fe_(2)O_(3)heterostructures with enriched oxygen defects on TiO_(2)nanofibers are designed for boosting PEC performances.Ivy-like Fe_(2)O_(3)photo-sheets remarkably enhanced the light harvesting by multiple light-mater interactions.The oxygen vacancies on Fe_(2)O_(3)photo-sheets could aid the photons catching and promote the reactivity at active sites.More importantly,demonstrated by a well-designed dynamic observation,the abundant tip-edges within ivy-like Fe_(2)O_(3)photo-sheets enabled the surface of heterostructure with hydrophilic and aerophobic properties.The functionalized surface allowed the rapid desorption of produced bubbles and thus ensured a high density of unoccupied active sites for electrolyte accessing.Featured by these attributes,the Fe_(2)O_(3)@TiO_(2)nanofibers delivered an excellent photocurrent of 40.8 mA/mg,high donor density(1.2×10^(18)cm^(−3)),and rapid oxygen production rate(1 mmol/(L∙h)).This work demonstrates a new strategy on nano-structural design for enhancing light-harvesting and making a hydrophilic/aerophobic surface on low-dimensional oxide nanomaterial,holding great potential on designing high-performance PEC devices for producing survival source gas,carbon-neutral fuel,and valuedchemicals.

Light-induced irreversible structural phase transition in trilayer graphene

A crystal structure has a profound influence on the physical properties of the corresponding material.By synthesizing crystals with particular symmetries,one can strongly tune their properties,even for the same chemical configuration(compare graphite and diamond,for instance).Even more interesting opportunities arise when the structural phases of crystals can be changed dynamically through external stimulations.Such abilities,though rare,lead to a number of exciting phenomena,such as phase-change memory effects.In the case of trilayer graphene,there are two common stacking configurations(ABA and ABC)that have distinct electronic band structures and exhibit very different behaviors.Domain walls exist in the trilayer graphene with both stacking orders,showing fascinating new physics such as the quantum valley Hall effect.Extensive efforts have been dedicated to the phase engineering of trilayer graphene.However,the manipulation of domain walls to achieve precise control of local structures and properties remains a considerable challenge.Here,we experimentally demonstrate that we can switch from one structural phase to another by laser irradiation,creating domains of different shapes in trilayer graphene.The ability to control the position and orientation of the domain walls leads to fine control of the local structural phases and properties of graphene,offering a simple but effective approach to create artificial two-dimensional materials with designed atomic structures and electronic and optical properties.

Animal models for hepatocellular carcinoma arising from alcoholic and metabolic liver diseases

Hepatocellular carcinoma (HCC) is a major and increasing cause of clinical and economic burden worldwide. Now that there are effective therapies to control or eradicate viral aetiologies, the landscape of HCC is changing with alcoholic and metabolic liver diseases becoming major catalysts. The pathogenesis of HCC is complex and incompletely understood, hampering improvements in therapy. Animal models are essential tools for advancing study on the cellular and molecular processes in HCC and for screening potential novel therapies. Many models of hepatocarcinogenesis have been established using various methods including genetic engineering, chemotoxic agents and dietary manipulation to direct implantation of tumour cells. However, none of these can accurately replicate all features found in human diseases. In this review, we provide an overview of different mouse models of HCC with a particular focus on cancer arising from alcoholic liver disease, non-alcoholic fatty liver disease and hereditary haemochromatosis. We also highlight their strengths and limitations and provide perspectives for future study.

Genetics of alcohol-related hepatocellular carcinoma - its role in risk prediction

Hepatocellular carcinoma(HCC)is the most common primary liver malignancy,with increasing incidence worldwide.Alcohol-related cirrhosis(AC)accounts for 30%of the global incidence of HCC and HCC-related deaths.With the decline of hepatitis C virus(HCV)and decreasing HCV-related HCC,AC will soon become the leading cause of HCC.Excess alcohol consumption(>80 g per day for>10 years)increases the risk of HCC by 5-fold.However,only up to 35%of excessive drinkers develop cirrhosis and its associated HCC risk.Individual variation in susceptibility to HCC is known,but there is limited information to predict who among the patients is at high risk of progressing to HCC.Clinical risk factors for HCC include male gender,older age,severity of cirrhosis,obesity and presence of type 2 diabetes.In addition to ethnic variability in HCC risk,genetic variants are known to alter the risk of alcohol-related HCC.For example,single nucleotide polymorphisms in PNPLA3(rs738409,C>G)and TM6SF2(rs58542926,C>T)increase the risk of AC-related HCC,whereas HSD17B13(T>A)reduces the risk for HCC.Studies have also confirmed PNPLA3 and TM6SF2 to be independent risk factors for AC-related(but not HCV-related)HCC.Combining genetic risk factors with phenotypic/clinical risk factors has been explored for stratification of patients for HCC development.Risk allele rs378409-G in PNPLA3 when combined with phenotypic/clinical risk factors(BMI,age,sex)has enabled HCC risk stratification of AC patients into low-,intermediate-and high-risk subgroups.Similarly,a combination of the two genetic variants PNPLA3-G and TM6SF2-T has been independently associated with risk of HCC onset.Using a polygenic risk score approach of incorporating several genetic variants,prognostic performance of polygenic risk score that included PNPLA3 rs378409 and TM6SF2 rs58542926 improved HCC prediction better than with either variant alone.Incorporating new variants and risk factors has the potential to build better algorithms/models to predict onset,early diagnosis and treatments for AC-related HCC.However,clinical usefulness of these approaches is yet to be determined.

播种

琳达上幼儿园的时候,望远镜和探测器拍到了第一批模糊的图像,图像呈现的是围绕遥远恒星运行的行星。她用粗线条和明亮的颜色画那些行星,自己身着粉色航天服的形象行走于三轮红日之下。她还画穹庐城市和天空中带着光环的月亮,以及紫#林,那里的叶子是五角舲,鸟儿有四只翅膀。