Development of Ultra-Low Loading of Compressive PT Lattice Cathode Catalyst on Highly Stable Support for PEMFC Automotive Applications

The major barriers in the commercialization of the fuel cell technology for automotive applications are the cost and durability of the Pt catalyst and the support stability at high potentials. The U.S. Department of Energy (DOE) targets direct hydrogen fuel cell systems for transportation to meet 65% peak-efficiency, 5,000 hour durability with a mass production cost of $40/kW by 2020. Currently in 2015, the system can be operated at peak energy efficiency of 60$55/kW. To meet these targets, precious metal loadings must be greatly reduced without altering the catalyst stability. The primary objective of this dissertation is to develop highly active and durable hybrid cathode catalysts (HCC) with ultra-low Pt loading for Proton Exchange Membrane Fuel Cells (PEMFC) through interaction of highly active and stable Pt and compressive Pt-lattice (Pt*) catalyst deposited on catalytically active and highly stable carbon composite catalyst (CCC) support and active carbon composite catalyst (A-CCC) support. The HCC activity is enhanced by by the synergistic effect of catalytic active sites for ORR present in the supports and those in Pt and Pt*. The stability of Pt-based catalyst can be greatly improved by doping with transition metal (TM), which weakens interactions between Pt and adsorbents such as OHads and Hupd. Highly active and durable HCC is developed in this study through: (i) synthesis of highly catalytically active and stable Co-containing CCC and A-CCC supports, (ii) surface functionalization and uniform Pt deposition on CCC and A-CCC supports, (iii) performance optimization of Co-doped Pt catalysts by using protective coating to inhibit particle agglomeration and growth during the pyrolysis step, (iv) optimization of Pt/Co ratio and annealing temperature and (v) chemical leaching to remove excess metal used to dope the support. T The support stability has been enhanced through optimization of: (i) Brunauer-Emmett-Teller (BET) surface, (ii) the support structural properties (amorphous/crystalline ratio), and (iii) the hydrophilic/hydrophobic ratio of the supports. During the past five years, the performance and durability of the catalysts were continuously studied. Stability of the catalyst was tested under U. S. DRIVE Fuel Cell Tech Team suggested protocols (a) potential cycling between 0.6 and 1.0 V for 30,000 cycles, (b) potential holding at 1.2 V for 400 h, and (c) potential cycling between 1.0 and 1.5 V for 5,000 cycles. The mass activity, H2-air polarization curve, ECSA, and power density were measured at regular intervals. Detailed results of this work will be discussed in this dissertation

Influencing Factors Analysis on Advertising Effectiveness of News feeds Ads

News feeds ads has became one of the mainstream mobile ads. However, there are also a series of problems behind the success of feeds ads: inaccurate recommendations, information security issues, and so on.This paper studies the influencing factors of advertising marketing effect of information flow, and puts forward corresponding suggestions, which has important guiding value for enterprise marketing under the age of big data. This research uses news feeds ads as the object, adopts literature research methods, questionnaire analysis methods, etc. Through combing related documents, we have selected three evaluation indicators: advertising cognition, advertising attitude and advertising sales. In terms of aspects and advertisements, there are seven factors influencing the reliability of the platform, the popularity of the platform, the familiarity of consumer brands, the degree of consumer participation, the degree of consumer rejection of advertisements, advertising creativity and performance, and the targeting of advertisements. Put forward relevant hypotheses and verify the sample data through SPSS to draw relevant con+clusions. The research shows that the reliability of the platform, the sensitivity of consumers to advertising, the familiarity of consumer brands, the degree of consumer participation, and the creative and targeted advertising all have a positive impact on the effectiveness of advertising. Based on the above conclusions, the author is the enterprise information. Streaming ads have made some targeted recommendations

On the Security Bootstrapping in Named Data Networking

By requiring all data packets been cryptographically authenticatable, the Named Data Networking (NDN) architecture design provides a basic building block for secured networking. This basic NDN function requires that all entities in an NDN network go through a security bootstrapping process to obtain the initial security credentials. Recent years have witnessed a number of proposed solutions for NDN security bootstrapping protocols. Built upon the existing results, in this paper we take the next step to develop a systematic model of security bootstrapping: Trust-domain Entity Bootstrapping (TEB). This model is based on the emerging concept of trust domain and describes the steps and their dependencies in the bootstrapping process. We evaluate the expressiveness and sufficiency of this model by using it to describe several current bootstrapping protocols

Cryptanalysis of HK17

Very recently, a key exchange scheme called HK17 was submitted to NIST as a candidate of the standard of post-quantum cryptography. The HK17 scheme employs some hypercomplex numbers as the basic objects, such as quaternions and octonions. In this paper, we show that HK17 is insecure since a passive adversary can recover the shared key in polynomial time

Ciphertext-Only Attacks against Compact-LWE Submitted to NIST PQC Project

In 2017, Liu, Li, Kim and Nepal submitted a new public-key encryption scheme Compact-LWE to NIST as a candidate of the standard of post-quantum cryptography. Compact-LWE features its structure similar to LWE, but with different distribution of errors. Liu, Li, Kim and Nepal thought that the special error distribution they employed would protect Compact-LWE from the known lattice-based attacks. Furthermore, they recommended a set of small parameters to improve the efficiency of Compact-LWE and claimed it can offer 192 bits of security. However, in this paper, we show that Compact-LWE is not secure with recommended parameters by presenting two efficient ciphertext-only attacks against it. \begin{itemize} \item The first one is to recover the equivalent private keys just from the public keys. By exploiting the special structure of Compact-LWE, employing some known skills such as orthogonal-lattice technique, and also developing some new techniques, we finally recovered the equivalent private keys for more than 80\% of the random generated instances in our experiments. \item The second one is to recover the corresponding message given the public keys and a ciphertext. Note that any short enough solutions of corresponding inhomogeneous linear systems can be used to decrypt a ciphertext equivalently. We recovered all the messages without knowing the private keys in our experiments. \end{itemize

Sustained complete response to first-line immunochemotherapy for highly aggressive TP53/MDM2-mutated upper tract urothelial carcinoma with ERBB2 mutations, luminal immune-infiltrated contexture, and non-mesenchymal state: a case report and literature review

BackgroundUpper tract urothelial carcinoma (UTUC) is a rare malignancy. The management of metastatic or unresectable UTUC is mainly based on evidence extrapolated from histologically homologous bladder cancer, including platinum-based chemotherapy and immune checkpoint inhibitor alone, whereas UTUC exhibits more invasiveness, worse prognosis, and comparatively inferior response to treatments. First-line immunochemotherapy regimens have been attempted in clinical trials for unselected naïve-treated cases, but their efficacies relative to standard chemo- or immuno-monotherapy still remain controversial. Here, we present a case of highly aggressive UTUC for whom comprehensive genetic and phenotypic signatures predicted sustained complete response to first-line immunochemotherapy.Case presentationA 50-year-old man received retroperitoneoscopic nephroureterectomy and regional lymphadenectomy for high-risk locally advanced UTUC. Postoperatively, he developed rapid progression of residual unresectable metastatic lymph nodes. Pathologic analysis and next-generation sequencing classified the tumor as highly aggressive TP53/MDM2-mutated subtype with features more than expression of programmed death ligand-1, including ERBB2 mutations, luminal immune-infiltrated contexture, and non-mesenchymal state. Immunochemotherapy combining gemcitabine, carboplatin, and off-label programmed death-1 inhibitor sintilimab was initiated, and sintilimab monotherapy was maintained up to 1 year. Retroperitoneal lymphatic metastases gradually regressed to complete response. Blood-based analyses were performed longitudinally for serum tumor markers, inflammatory parameters, peripheral immune cells, and circulating tumor DNA (ctDNA) profiling. The ctDNA kinetics of tumor mutation burden and mean variant allele frequency accurately predicted postoperative progression and sustained response to the following immunochemotherapy, which were mirrored by dynamic changes in abundances of ctDNA mutations from UTUC-typical variant genes. The patient remained free of recurrence or metastasis as of this publishing, over 2 years after the initial surgical treatment.ConclusionImmunochemotherapy may be a promising first-line option for advanced or metastatic UTUC selected with specific genomic or phenotypic signatures, and blood-based analyses incorporating ctDNA profiling provide precise longitudinal monitoring

Baicalein-corrected gut microbiota may underlie the amelioration of memory and cognitive deficits in APP/PS1 mice

Background: Baicalein is an active ingredient extracted from the root of S. baicalensis Georgi, which exhibits cardiovascular protection, anti-inflammatory, and anti-microbial properties. Our previous study showed that chronic treatment of Baicalein ameliorated cognitive dysfunction in a mouse model of Alzheimer's disease (AD). However, it remains unknown whether Baicalein ameliorates cognitive deficits in AD mouse models by altering gut microbiota and its metabolites.Methods: Behavioral tests, metagenomic and untargeted metabolomics analyses were used to evaluate the effects of Baicalein on the APP/PS1 mice.Results: Our research showed that treatment of Baicalein for 2 weeks ameliorated cognition and memory in a dose-dependent manner, as indicated by the significant increases in the Discrimination index and Number of crossings and decrease in latency to the previous platform location in 8-month of age APP/PS1 mice in novel object recognition and water maze tests. The metagenomic analysis showed the abundance of the dominant phyla in all groups, including Bacteroidetes (14.59%–67.02%) and Firmicutes (20.19%–61.39%). LEfSe analysis of metagenomics identified three species such as s__Roseburia_sp_1XD42_69, s__Muribaculaceae_bacterium_Isolate_104_HZI, s__Muribaculaceae_bacterium_Isolate_110_HZI as Baicalein-treated potential biomarkers. Metabolite analysis revealed the increment of metabolites, including glutamate, thymine and hexanoyl-CoA.Conclusion: The effects of Baicalein on memory and cognition may relate to the metabolism of nucleotides, lipids and glucose

Investigation of vibration characteristics for bladed-disks with dry friction nonlinearity

This paper focuses on the vibration characteristics of the bladed-disk subjected to the dry friction damping under periodic excitation. Firstly, the multi-harmonic equation basing on the frequency-domain analysis is established to predicate the steady response of the bladed-disk. Then, the algorithm to solve the nonlinear multi-harmonic balance equation is given step by step. In the numerical simulation, a simplified lumped parameter model of a turbine bladed-disk as well as the elastic Coulomb friction model between the root and disk contacting surfaces are applied. The normal load level of the friction interfaces, which are the focal points of the bladed-disk design, is analysed for the nonlinear vibration characteristics of the blades. The results show that vibration response of bladed-disk is affected significantly by normal load, and there exists an optimal value of the normal load under the operating condition of the turbomachinery, which can provide a qualitative assessment for the design practice of friction dampers

Thermal fluid fields reconstruction for nanofluids convection based on physics-informed deep learning

Abstract Based on physics-informed deep learning method, the deep learning model is proposed for thermal fluid fields reconstruction. This method applied fully-connected layers to establish the mapping function from design variables and space coordinates to physical fields of interest, and then the performance characteristics Nusselt number Nu and Fanning friction factor f can be calculated from the reconstructed fields. Compared with reconstruction model based on convolutional neural network, the improved model shows no constrains on mesh generation and it improves the physical interpretability by introducing conservation laws in loss functions. To validate this method, the forced convection of the water-Al2O3 nanofluids is utilized to construct training dataset. As shown in this paper, this deep neural network can reconstruct the physical fields and consequently the performance characteristics accurately. In the comparisons with other classical machine learning methods, our reconstruction model is superior for predicting performance characteristics. In addition to the effect of training size on prediction power, the extrapolation performance (an important but rarely investigated issue) for important design parameters are also explored on unseen testing datasets

Investigation of vibration characteristics for bladed-disks with dry friction nonlinearity

This paper focuses on the vibration characteristics of the bladed-disk subjected to the dry friction damping under periodic excitation. Firstly, the multi-harmonic equation basing on the frequency-domain analysis is established to predicate the steady response of the bladed-disk. Then, the algorithm to solve the nonlinear multi-harmonic balance equation is given step by step. In the numerical simulation, a simplified lumped parameter model of a turbine bladed-disk as well as the elastic Coulomb friction model between the root and disk contacting surfaces are applied. The normal load level of the friction interfaces, which are the focal points of the bladed-disk design, is analysed for the nonlinear vibration characteristics of the blades. The results show that vibration response of bladed-disk is affected significantly by normal load, and there exists an optimal value of the normal load under the operating condition of the turbomachinery, which can provide a qualitative assessment for the design practice of friction dampers