Erosion mechanisms of thermally sprayed coatings with multiple phases

Thermally sprayed coatings are frequently subjected to impacts by small solid particles which induce surface erosion. To identify the physical mechanisms associated with such a material removal process, experimental tests as well as detailed computational analyses of porous coatings containing multiple phases are performed. In the experiments, a gas jet erosion test is conducted to measure material loss of coatings with different mixtures of brittle and ductile phases. The results show higher erosion resistances with small volume fractions of metal phase added to predominantly brittle coatings. Following this outcome, the study is directed toward elucidating the physical mechanisms behind the increased erosion resistance. Here, solid particle impacts are simulated with dynamic finite element analyses where material removals and coating's energy absorption behaviors are closely monitored. Furthermore, parametric study is carried out to quantify effects of cracking resistances and plastic dissipation on the erosion rate. The results reveal synergistic effects of fracture energy and plastic deformation. The combined mechanisms allow greater energy absorptions and enhanced erosion resistance in coatings with mixture of ductile phase. These assessments should offer insights into tailoring coatings with optimized composition of ductile phase to increase their performances. The results are also valuable in understanding foreign object damage (FOD) of coatings.     

Photoinduced anisotropy in a family of amorphous azobenzene polyesters for optical storage

We investigate parameters associated with optical data storage in a variety of amorphous side-chain azobenzene-containing polyesters denoted as E1aX. The polyesters possess a common cyano-substituted azobenzene chromophore as a side chain, but differ in their main-chain polyester composition. Seventeen different polymers from the E1aX family divided into four classes, depending on the type of the main-chain substituent (one-, two-, and three-ring aromatic or alicyclic) have been thoroughly investigated. Various parameters characterizing the photoinduced birefringence in these materials, such as the response time, thermal and light stability, and long-term stability under ambient light at room temperature have been measured. Each of these parameters is quantitatively represented and therefore it is possible to make a clear comparison between the properties of the polymers. The results indicate that the long-term stability at ambient temperature is closely related to the thermal stability of the photoinduced birefringence. A strong correlation has also been found between the response time and the stability of the induced anisotropy toward illumination with unpolarized white light. One of the classes of E1aX polymers characterized by two-ring aromatic substituent in the main chain is a good candidate for optical data storage media. A recording energy of approximately 2 J/cm2 is sufficient to induce high refractive-index modulations of deltan = 0.13 in these materials, which is retained even at elevated temperatures (>130 degrees C). Long-term stability of greater than one year for the induced anisotropy has also been achieved.     

Feasibility studies for assessing internal exposure to 233U

The potential internal occupational exposure encountered as a consequence of the 232Th-233U fuel cycle are likely to arise predominantly from the inhalation of 232Th, 233U and (232Th + 233U) compounds of absorption Types M and S. In the past, although direct and indirect methods for assessments of internal exposure to 232Th and its daughters were developed, standardised and employed, no such attempts have been made with regard to 233U and 233U + 232Th. Therefore, feasibility studies for assessing internal exposure to 233U have been conducted using three methods: urine bioassay, in vivo counting and measurement of thoron gas in the exhaled breath of a worker. This paper describes details of these studies and discusses the results obtained.     

Electron‐Induced Reactive Processing of Poly(propylene)/Ethylene–Octene Copolymer Blends: A Novel Route to Prepare Thermoplastic Vulcanizates

TPVs are prepared by dynamic vulcanization in which crosslinking of an elastomeric polymer takes place during its melt mixing with a thermoplastic polymer under high‐shear conditions. 30:70 wt% blends of PP and ethylene–octene copolymer are vulcanized using electron‐induced reactive processing (EIReP) employing a range of absorbed doses (25, 50, and 100 kGy) while keeping the electron energy and treatment time fixed. The structure/property relationships of the prepared samples are studied using various characterization techniques such as DMA, DSC, SEM, and melt rheology. The results suggest that EIReP offers a novel route to prepare TPVs without any chemical crosslinking and coupling agents.

     

Targeting Tumor Acidosis and Regulatory T Cells Unmasks Anti-Metastatic Potential of Local Tumor Ablation in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an immunologically heterogenous disease that lacks clinically actionable targets and is more likely to progress to metastatic disease than other types of breast cancer. Tumor ablation has been used to increase response rates to checkpoint inhibitors, which remain low for TNBC patients. We hypothesized that tumor ablation could produce an anti-tumor response without using checkpoint inhibitors if immunosuppression (i.e., Tregs, tumor acidosis) was subdued. Tumors were primed with sodium bicarbonate (200 mM p.o.) to reduce tumor acidosis and low-dose cyclophosphamide (100–200 mg/kg i.p.) to deplete regulatory T cells, as has been shown independently in previous studies. A novel injectable ablative was then used to necrose the tumor, release tumor antigens, and initiate an immune event that could create an abscopal effect. This combination of bicarbonate, cyclophosphamide, and ablation, called “BiCyclA”, was tested in three syngeneic models of TNBC: E0771 (C57BL/6), 67NR (BALB/c), and 4T1-Luc (BALB/c). In E0771 and 67NR, BiCyclA therapy significantly reduced tumor growth and cured 5/7 and 6/10 mice 50 days after treatment respectively. In the metastatic 4T1-Luc tumors, for which surgery and checkpoint inhibitors fail, BiCyclA cured 5/10 mice of primary tumors and lung metastases. Notably, CD4+ and CD8+ T cells were found to be crucial for the anti-metastatic response, and cured mice were able to resist tumor rechallenge, suggesting production of immune memory. Reduction of tumor acidity and regulatory T cells with ablation is a simple yet effective therapy for local and systemic tumor control with broad applicability as it is not limited by expensive supplies.     

Efficient Computation of Address Sequences in Data Parallel Programs Using Closed Forms for Basis Vectors

Arrays are mapped to processors through a two-step process—alignment followed by distribution—in data-parallel languages such as High Performance Fortran. This process of mapping creates disjoint pieces of the array that are locally owned by each processor. An HPF compiler that generates code for array statements must compute the sequence of local memory addresses accessed by each processor and the sequence of sends and receives for a given processor to access nonlocal data. In this paper, we present an approach to the address sequence generation problem using the theory of integer lattices. The set of elements referenced can be generated by integer linear combinations of basis vectors. Unlike other work on this problem, we derive closed form expressions for the basis vectors as a function of the mapping of data. Using these basis vectors and exploiting the fact that there is a repeating pattern in the access sequence, we derive highly optimized code that generates the pattern at runtime. The code generated uses table-lookup of the pattern. Experimental results show that our approach is faster than other solutions to this problem.     

Distributed manufacturing for electrified chemical processes in a microgrid

To alleviate the greenhouse gas emissions by the chemical industry, electrification has been proposed as a solution where electricity from renewable sources is used to power processes. The adoption of renewable energy is complicated by its spatial and temporal variations. To address this challenge, we investigate the potential of distributed manufacturing for electrified chemical processes installed in a microgrid. We propose a multiscale mixed-integer linear programming model for locating modular electrified plants, renewable-based generating units, and power lines in a microgrid that includes monthly transportation and hourly scheduling decisions. We propose a K-means clustering-based aggregation disaggregation matheuristic to solve the model efficiently. The model and algorithm are tested using a case study with 20 candidate locations in Western Texas. Additionally, we define a new concept, “the Value of the Multi-scale Model,” to demonstrate the additional economic benefits of our model compared with a single-scale model.