Optimized butterfly specimen for the fracture testing of sheet materials under combined normal and shear loading

The present paper is concerned with multi-axial ductile fracture experiments on sheet metals. Different stress-states are achieved within a flat specimen by applying different combinations of normal and transverse loads to the specimen boundaries. The specimen geometry is optimized such that fracture initiates remote from the free specimen boundaries. Fracture experiments are carried out on TRIP780 steel for four different loading conditions, varying from pure shear to transverse plane strain tension. Hybrid experimental–numerical analyses are performed to determine the stress and strain fields within the specimen gage section. The results show that strain localization cannot be avoided prior to the onset of fracture. Through-thickness necking prevails under tension-dominated loading while the deformation localizes along a band crossing the entire gage section under shear-dominated loading. Both experimental and simulation results demonstrate that the proposed fracture testing method is very sensitive to imperfections in the specimen machining. The loading paths to fracture are determined in terms of stress triaxiality, Lode angle parameter and equivalent plastic strain. The experimental data indicates that the relationship between the stress triaxiality and the equivalent plastic strain at the onset of ductile fracture is not unique.     

TP53 Targeted Deep Sequencing of Cell-Free DNA in Esophageal Squamous Cell Carcinoma Using Low-Quality Serum: Concordance with Tumor Mutation

Circulating cell-free DNA (cfDNA) is emerging as a potential tumor biomarker. CfDNA-based biomarkers may be applicable in tumors without an available non-invasive screening method among at-risk populations. Esophageal squamous cell carcinoma (ESCC) and residents of the Asian cancer belt are examples of those malignancies and populations. Previous epidemiological studies using cfDNA have pointed to the need for high volumes of good quality plasma (i.e., >1 mL plasma with 0 or 1 cycles of freeze-thaw) rather than archival serum, which is often the main available source of cfDNA in retrospective studies. Here, we have investigated the concordance of TP53 mutations in tumor tissue and cfDNA extracted from archival serum left-over from 42 cases and 39 matched controls (age, gender, residence) in a high-risk area of Northern Iran (Golestan). Deep sequencing of TP53 coding regions was complemented with a specialized variant caller (Needlestack). Overall, 23% to 31% of mutations were concordantly detected in tumor and serum cfDNA (based on two false discovery rate thresholds). Concordance was positively correlated with high cfDNA concentration, smoking history (p-value = 0.02) and mutations with a high potential of neoantigen formation (OR; 95%CI = 1.9 (1.11–3.29)), suggesting that tumor DNA release in the bloodstream might reflect the effects of immune and inflammatory context on tumor cell turnover. We identified TP53 mutations in five controls, one of whom was subsequently diagnosed with ESCC. Overall, the results showed that cfDNA mutations can be reliably identified by deep sequencing of archival serum, with a rate of success comparable to plasma. Nonetheless, 70% non-identifiable mutations among cancer patients and 12% mutation detection in controls are the main challenges in applying cfDNA to detect tumor-related variants when blindly targeting whole coding regions of the TP53 gene in ESCC.     

Development of a universal modeling tool for rechargeable lithium batteries

An interesting universal modeling tool for rechargeable lithium batteries is presented in this paper. The generic model is based on an equivalent circuit technique commonly used in electrochemical impedance characterization. Therefore, the parameters used in the model can be easily parameterized from the electrochemical impedance derivations, which provide a convenient integration with experimental cell characterizations. Such integration offers the universality in this modeling approach.     

Dark matter searches with H.E.S.S.

WIMP annihilations are required to reproduce the correct dark matter abundance in the Universe. This process can occur in dense regions of our Galaxy such as the Galactic center, dwarf galaxies and other types of sub-haloes. High-energy γ-rays are produced in dark matter particle collisions and can be detected by Cherenkov telescopes such as H.E.S.S. We report here the search for γ-ray signals from the Galactic center and the nearby Sagittarius and Canis Major satellites. In the absence of a convincing signal, modelling the dark matter density within these objects allows to put constraints on the WIMP parameters such as its mass and annihilation cross-section. Beyond these targeted searches, the wide-field survey of the inner Galaxy with H.E.S.S. is used to constrain sub-halo formation models involving intermediate-mass black holes.     

Measurement and scaling of air-surface mercury exchange from substrates in the vicinity of two Nevada gold mines

The state of Nevada has extensive mineral resources, and is the largest producer of gold in the USA as well as fourth in world gold production. Mercury (Hg) is often present in the hydrothermal systems that produce gold deposits, and can be found in elevated concentrations in gold ore. As a result, mining of gold ore in Nevada has been shown to release Hg to the atmosphere from point and non-point sources. This project focused on measurement of air-soil Hg exchange associated with undisturbed soils and bedrock outcrops in the vicinity of two large gold mines. Field and laboratory data collected were used to identify the important variables controlling Hg flux from these surfaces, and to estimate a net flux from the areas adjacent to the active mines as well as that occurring from the mined area pre-disturbance. Mean daily flux by substrate type ranged from 9 ng m^− 2 day^− 1 to 140 ng m^− 2 day^− 1. Periods of net deposition of elemental Hg were observed when air masses originating from a mine site moved over sampling locations. Based on these observations and measured soil Hg concentrations we suggest that emissions from point and non-point sources at the mines are a source of Hg to the surrounding substrates with the amount deposited not being of an environmental concern but of interest mainly with respect to the cycling of atmospheric elemental Hg. Observations indicate that while some component of the deposited Hg is sequestered in the soil, this Hg is gradually released back to the atmosphere over time. Estimated pre-disturbance emissions from the current mine footprints based on field data were 0.1 and 1.7 kg yr^− 1, compared to that estimated for the current non-point mining sources of 19 and 109 kg yr^− 1, respectively.     

交通视频监控系统中TMS320DM642与嵌入式PC/104+模块的通信

描述了TI公司媒体处理器TMS320DM642HPI的主要特点，介绍了PCI桥接器PCI2040的结构原理，提出了通过PCI2040实现TMS320DM642与PC／104＋模块进行通信的设计方案。本方案充分利用PCI总线的高数据吞吐能力和DSP的HPI接口功能，可在DSP和PC／104＋模块之间实现较高的数据传输率，实现了PC／104＋实时读／写DSP任意片内存储单元的内容。最后给出交通视频监控系统的设计方案，详细说明了通信过程的软件编程。     

Photo-oxidation in an O2 atmosphere: A powerful tool to elucidate the mechanism of UV-visible light oxidation of polymers - Application to the photodegradation of MDMO-PPV

This article describes a new approach to improve the analysis of the chemical modifications that result from the degradation of polymers under UV-visible light exposure in the presence of oxygen. The tool which is used consists of an irradiation chamber whose atmosphere is composed of ¹⁸O₂. The ¹⁸O₂ pressure inside the chamber and the hygrometry can be adjusted. In this study, particular attention was paid to the photo-oxidation of poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV). Using infrared spectroscopy, irradiation under the oxygen 18 atmosphere allowed discrimination between compounds formed via fixation of oxygen from the atmosphere and those formed by reorganisation of the matrix. In addition, irradiation of MDMO-PPV in an ¹⁸O₂ wet atmosphere allowed for detection of the presence of phenyl formate and aromatic ketone functions. This permitted validating the mechanism of photo-oxidation previously proposed. Additionally, with regard to blends made with MDMO-PPV and methano-fullerene[6,6]-phenyl C₆₁-butyric acid methyl ester ([60] PCBM), it was demonstrated that this technique facilitates the identification of the photo-oxidation products formed.     

Availability Analysis and Enhanced Availability Design in <Emphasis Type="Italic">p</Emphasis>-Cycle-Based Networks

p-Cycle protection is a fairly new survivability scheme that has the interesting properties of offering restoration speeds essentially the same as those offered by ring protection while requiring almost as little redundant capacity as adaptive mesh restoration [D. Stamatelakis, W.D. Grover, IEEE Transactions on Communications, vol. 48, no. 8, (August 2000), pp. 1262–1265]. This paper presents the first analytical consideration of the availability of paths in a network protected by p-cycles. Results confirm the importance that cycle sizes play in terms of availability and suggests principles or strategies for achieving high availability of paths in a network protected by p-cycles. Based on these insights, two new formulations for joint service path provisioning and capacity planning are proposed. The first one offers a way to improve the availability of selected service paths by using a different routing strategy for them than for regular service paths. The second formulation enables a new class of service paths that are offered two protection options instead of just one. That class of service paths is expected to see its availability improved in a quantum step way relative to the availability of paths having only one protection option.     

Span-Restorable Mesh Networks with Multiple Quality of Protection (QoP) Service Classes

In the modern business environment there is considerable interest in being able to support a range of different transport service classes in an optical network, and charge accordingly. In this work we consider the capacity design problem for a mesh-restorable optical network supporting any mixture of four basic quality of protection (QoP) classes. The service definitions are (gold): assured restorability, (silver): best efforts, (bronze): non-protected and (economy): preemptible service. We give design models for optimal capacity design of span-restorable (or corresponding link-protected) mesh networks having any particular mixture of these service classes. We also apply and test the design models under several multi-QoP test case scenarios to gain insights about various strategies and options possible in a multi-QoP design environment. An interesting finding is that in some test cases, 15 to 30% of all demand can be in the gold class enjoying 100% restorability solely through preemption of economy class service capacity. This suggests the potential to design and operate mesh-based networks that have no spare capacity at all in the conventional sense: all capacity is bearing service of some paying type. The resulting frequency of preemption in the economy class services is also studied. Results also show typically high levels of best-efforts restorability in the silver class occurring in networks that are strictly designed only for the restorability of the gold class services. High restorability of best effort services, however, requires the preemption of economy services. These methods and findings can be used by network and business planners to evaluate a number of different service structuring, pricing, and capacity-design strategies that may offer advantages to them and new options for their customers.