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Creators/Authors contains: "Huang, Zhen"

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  1. Despite decades of effort in research and engineering, integer overflows remain a severe threat to software security. Many tools are developed to detect integer overflows at runtime. However, the vast majority of them terminates program execution when an integer overflow is detected. This essentially causes denial-of-service, which is undesirable in many scenarios in practice. We propose a recovery mechanism designed for safe recovery from integer overflows. The recovery mechanism detects integer overflows and rectifies the values involved in arithmetic operations causing integer overflows so that it prevents the occurrence of the integer overflows and enables the program to continue execute safely. We have designed and developed a tool called RIO that can automatically synthesize and instrument our recovery mechanism into target programs. Our evaluation shows that RIO can successfully synthesize and instrument the recovery mechanism into programs containing real world vulnerabilities and the instrumented recovery mechanism allows the programs to recover safely in the face of exploits intending to trigger the vulnerabilities. 
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  2. Abstract

    The oxidative coupling of methane to higher hydrocarbons offers a promising autothermal approach for direct methane conversion, but its progress has been hindered by yield limitations, high temperature requirements, and performance penalties at practical methane partial pressures (~1 atm). In this study, we report a class of Li2CO3-coated mixed rare earth oxides as highly effective redox catalysts for oxidative coupling of methane under a chemical looping scheme. This catalyst achieves a single-pass C2+yield up to 30.6%, demonstrating stable performance at 700 °C and methane partial pressures up to 1.4 atm. In-situ characterizations and quantum chemistry calculations provide insights into the distinct roles of the mixed oxide core and Li2CO3shell, as well as the interplay between the Pr oxidation state and active peroxide formation upon Li2CO3coating. Furthermore, we establish a generalized correlation between Pr4+content in the mixed lanthanide oxide and hydrocarbons yield, offering a valuable optimization strategy for this class of oxidative coupling of methane redox catalysts.

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  3. Detecting software vulnerabilities has been a challenge for decades. Many techniques have been developed to detect vulnerabilities by reporting whether a vulnerability exists in the code of software. But few of them have the capability to categorize the types of detected vulnerabilities, which is crucial for human developers or other tools to analyze and address vulnerabilities. In this paper, we present our work on identifying the types of vulnerabilities using deep learning. Our data consists of code slices parsed in a manner that captures the syntax and semantics of a vulnerability, sourced from prior work. We train deep neural networks on these features to perform multiclass classification of software vulnerabilities in the dataset. Our experiments show that our models can effectively identify the vulnerability classes of the vulnerable functions in our dataset. 
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  4. Virtual memory, specifically paging, is undergoing significant innovation due to being challenged by new demands from modern workloads. Recent work has demonstrated an alternative software only design that can result in simplified hardware requirements, even supporting purely physical addressing. While we have made the case for this Compiler- And Runtime-based Address Translation (CARAT) concept, its evaluation was based on a user-level prototype. We now report on incorporating CARAT into a kernel, forming Compiler- And Runtime-based Address Translation for CollAborative Kernel Environments (CARAT CAKE). In our implementation, a Linux-compatible x64 process abstraction can be based either on CARAT CAKE, or on a sophisticated paging implementation. Implementing CARAT CAKE involves kernel changes and compiler optimizations/transformations that must work on all code in the system, including kernel code. We evaluate CARAT CAKE in comparison with paging and find that CARAT CAKE is able to achieve the functionality of paging (protection, mapping, and movement properties) with minimal overhead. In turn, CARAT CAKE allows significant new benefits for systems including energy savings, larger L1 caches, and arbitrary granularity memory management. 
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  5. Abstract

    Chemically modified antisense oligonucleotides (ASO) currently in pre‐clinical and clinical experiments mainly focus on the 2′‐position derivatizations to enhance stability and targeting affinity. Considering the possible incompatibility of 2′‐modifications with RNase H stimulation and activity, we have hypothesized that the atom specific modifications on nucleobases can retain the complex structure and RNase H activity, while enhancing ASO's binding affinity, specificity, and stability against nucleases. Herein we report a novel strategy to explore our hypothesis by synthesizing the deoxynucleoside phosphoramidite building block with the seleno‐modification at 5‐position of thymidine, as well as its Se‐oligonucleotides. Via X‐ray crystal structural study, we found that the Se‐modification was located in the major groove of nucleic acid duplex and didn't cause the thermal and structural perturbations. Surprisingly, our nucleobase‐modified Se‐DNAs were exceptionally resistant to nuclease digestion, while compatible with RNase H activity. This affords a novel avenue for potential anti‐sense modification in the form of Se‐antisense oligonucleotides (Se‐ASO).

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  6. OpenMP implementations make increasing demands on the kernel. We take the next step and consider bringing OpenMP into the kernel. Our vision is that the entire OpenMP application, run-time system, and a kernel framework is interwoven to become the kernel, allowing the OpenMP implementation to take full advantage of the hardware in a custom manner. We compare and contrast three approaches to achieving this goal. The first, runtime in kernel (RTK), ports the OpenMP runtime to the kernel, allowing any kernel code to use OpenMP pragmas. The second, process in kernel (PIK) adds a specialized process abstraction for running user-level OpenMP code within the kernel. The third, custom compilation for kernel (CCK), compiles OpenMP into a form that leverages the kernel framework without any intermediaries. We describe the design and implementation of these approaches, and evaluate them using NAS and other benchmarks. 
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  7. null (Ed.)
    Point-of-care COVID-19 assays that are more sensitive than the current RT-PCR (reverse transcription polymerase chain reaction) gold standard assay are needed to improve disease control efforts. We describe the development of a portable, ultrasensitive saliva-based COVID-19 assay with a 15-min sample-to-answer time that does not require RNA isolation or laboratory equipment. This assay uses CRISPR-Cas12a activity to enhance viral amplicon signal, which is stimulated by the laser diode of a smartphone-based fluorescence microscope device. This device robustly quantified viral load over a broad linear range (1 to 10 5 copies/μl) and exhibited a limit of detection (0.38 copies/μl) below that of the RT-PCR reference assay. CRISPR-read SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) RNA levels were similar in patient saliva and nasal swabs, and viral loads measured by RT-PCR and the smartphone-read CRISPR assay demonstrated good correlation, supporting the potential use of this portable assay for saliva-based point-of-care COVID-19 diagnosis. 
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  8. Abstract

    Embedding nodes of a large network into a metric (e.g., Euclidean) space has become an area of active research in statistical machine learning, which has found applications in natural and social sciences. Generally, a representation of a network object is learned in a Euclidean geometry and is then used for subsequent tasks regarding the nodes and/or edges of the network, such as community detection, node classification and link prediction. Network embedding algorithms have been proposed in multiple disciplines, often with domain‐specific notations and details. In addition, different measures and tools have been adopted to evaluate and compare the methods proposed under different settings, often dependent of the downstream tasks. As a result, it is challenging to study these algorithms in the literature systematically. Motivated by the recently proposed PCS framework for Veridical Data Science, we propose a framework for network embedding algorithms and discuss how the principles ofpredictability,computability, andstability(PCS) apply in this context. The utilization of this framework in network embedding holds the potential to motivate and point to new directions for future research.

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