| 1. |
- Castro-Gonzalez, Sergio, et al.
(author)
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Residues T48 and A49 in HIV-1 NL4-3 Nef are responsible for the counteraction of autophagy initiation, which prevents the ubiquitin-dependent degradation of Gag through autophagosomes
- 2021
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In: Retrovirology. - : BioMed Central (BMC). - 1742-4690. ; 18:1
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Journal article (peer-reviewed)abstract
- Background: Autophagy plays an important role as a cellular defense mechanism against intracellular pathogens, like viruses. Specifically, autophagy orchestrates the recruitment of specialized cargo, including viral components needed for replication, for lysosomal degradation. In addition to this primary role, the cleavage of viral structures facilitates their association with pattern recognition receptors and MHC-I/II complexes, which assists in the modulation of innate and adaptive immune responses against these pathogens. Importantly, whereas autophagy restricts the replicative capacity of human immunodeficiency virus type 1 (HIV-1), this virus has evolved the gene nef to circumvent this process through the inhibition of early and late stages of the autophagy cascade. Despite recent advances, many details of the mutual antagonism between HIV-1 and autophagy still remain unknown. Here, we uncover the genetic determinants that drive the autophagy-mediated restriction of HIV-1 as well as the counteraction imposed by Nef. Additionally, we also examine the implications of autophagy antagonism in HIV-1 infectivity.Results: We found that sustained activation of autophagy potently inhibits HIV-1 replication through the degradation of HIV-1 Gag, and that this effect is more prominent for nef-deficient viruses. Gag re-localizes to autophagosomes where it interacts with the autophagosome markers LC3 and SQSTM1. Importantly, autophagy-mediated recognition and recruitment of Gag requires the myristoylation and ubiquitination of this virus protein, two post-translational modifications that are essential for Gag’s central role in virion assembly and budding. We also identified residues T48 and A49 in HIV-1 NL4-3 Nef as responsible for impairing the early stages of autophagy. Finally, a survey of pandemic HIV-1 transmitted/founder viruses revealed that these isolates are highly resistant to autophagy restriction.Conclusions: This study provides evidence that autophagy antagonism is important for virus replication and suggests that the ability of Nef to counteract autophagy may have played an important role in mucosal transmission. Hence, disabling Nef in combination with the pharmacological manipulation of autophagy represents a promising strategy to prevent HIV spread.
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| 2. |
- Chen, Xin, et al.
(author)
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Manipulation of Electronic and Magnetic Properties of 3d Transition Metal (Cr, Mn, Fe) Hexamers on Graphene with Vacancy Defects : Insights from First-Principles Theory
- 2020
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In: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 124:7, s. 4270-4278
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Journal article (peer-reviewed)abstract
- One of the possible ways to introduce magnetism in graphene is to trap highly mobile transition metal atoms at defect sites in graphene. In this paper, based on Born-Oppenheimer molecular dynamics simulations, we investigated the self-assembly of transition metal hexamers X-6 (X = Cr, Mn, and Fe) on graphene with mono/divacancy defects and studied the fundamental electronic and magnetic properties of the resulting X-6 clusters on graphene. Interestingly, the ground state Cr-6 and Fe-6 hexamers on divacancy defects in graphene show quite small energy differences between in-plane and out-of-plane magnetism. By applying external electric fields, the easy axis of magnetization can be switched between in-plane and out-of-plane, which demonstrates potential applications in electric field-assisted magnetic recording and quantum computing.
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| 3. |
- Chen, Yuhang, et al.
(author)
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Far-field Training with Estimation for Cross-field Beam Alignment in Terahertz UM-MIMO Systems
- 2023
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In: 2023 IEEE Global Communications Conference, GLOBECOM 2023. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 2348-2353
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Conference paper (peer-reviewed)abstract
- Terahertz (THz) ultra-massive multiple-input multiple-output (UM-MIMO) systems are promising in enabling next-generation wireless communications, offering high data rates with tens of GHz of continuous bandwidth and high spectral efficiency. In THz UM-MIMO systems, a new paradigm of cross-field communications is emerging, since THz transmission distances span from near-field to far-field. To achieve the benefits of THz UM-MIMO, precise beam alignment implemented through beam training or beam scanning is required. However, different from the traditional far-field alignment in the angle domain, the near-field angle and distance alignment should be considered in the cross-field. The additional distance domain searching brings higher training overhead and thus limits the system's performance. In this paper, a far-field training with estimation (FTE) framework for cross-field beam alignment is proposed. The far-field training enables the received signal-to-noise ratio (SNR) in both the far- and near-field for successful control signal reception. Moreover, a three-phase beam estimator (TPBE) is proposed for high-precision alignment. Extensive simulations demonstrate the effectiveness of the proposed methods. Specifically, the FTE possesses a near-optimal signal-to-noise ratio with only 0.5 dB deviation, with 3.3% training overhead and low complexity compared to near-field exhaustive search.
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| 4. |
- Huang, Yajun, et al.
(author)
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Experimental study of flame spread over thermally-thin inclined fuel surface and controlling heat transfer mechanism under concurrent wind
- 2021
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In: International Journal of Thermal Sciences. - : Elsevier BV. - 1290-0729. ; 165
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Journal article (peer-reviewed)abstract
- The fuel inclination and wind velocity play a significant role on the forward flame spread behavior. It deserves further study since the heat transfer mechanism and flame spread characteristics coupled these two factors are not clear yet. In this paper, a thermally thin slab of PMMA that could be inclined from a horizontal (0°) to a vertical (90°) angle is used to investigate flame spread behavior under the condition of the concurrent ambient airflow. A wind tunnel is utilized to provide a uniform concurrent airflow, ranging from 0 (quiescent) to 3 m/s with an interval of 0.5 m/s. Essential flame characteristic parameters are collected to quantify the flame spread process, including flame spread rate (FSR), burning rate, heat release rate as well as heat flux feedback both in the pyrolysis and preheating zones. A mechanism, including the competition between the acceleration of buoyancy brought by inclination and the cooling effect of ambient airflow for relatively high wind velocity, is developed. The relationship between flame length and pyrolysis length is investigated. Moreover, the evolution of both heat release rate per unit width and standoff distance as a function of pyrolysis length are analyzed. A dimensionless heat release rate for upward flame at different wind velocities is used to scale the dimensionless flame length with a power-law exponent of 0.77 and −1.92. In addition, the dimensionless heat flux in preheated zone decay with distance as a function of power law. A predictive formulation of FSR coupled with inclination angle and wind velocity is proposed. This study facilitates the understanding of the interaction of fuel inclination angle and horizontal ambient airflow from aspect of heat and mass transfer.
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| 5. |
- Shi, Yuhang, et al.
(author)
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Effects of the SUMO Ligase BCA2 on Metabolic Activity, Cell Proliferation, Cell Migration, Cell Cycle, and the Regulation of NF-κB and IRF1 in Different Breast Epithelial Cellular Contexts
- 2021
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In: Frontiers in Cell and Developmental Biology. - : Frontiers Media S.A.. - 2296-634X. ; 9
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Journal article (peer-reviewed)abstract
- Breast cancer-associated gene 2 (BCA2) is an E3 ubiquitin and SUMO ligase with antiviral properties against HIV. Specifically, BCA2 (i) enhances the restriction imposed by BST2/Tetherin, impeding viral release; (ii) promotes the ubiquitination and degradation of the HIV protein Gag, limiting virion production; (iii) down-regulates NF-κB, which is necessary for HIV RNA synthesis; and (iv) activates the innate transcription factor IRF1. Due to its antiviral properties, ectopic expression of BCA2 in infected cells represents a promising therapeutic approach against HIV infection. However, BCA2 up-regulation is often observed in breast tumors. To date, the studies about BCA2 and cancer development are controversial, stating both pro- and anti-oncogenic roles. Here, we investigated the impact of BCA2 on cellular metabolic activity, cell proliferation, cell migration, and cell cycle progression. In addition, we also examined the ability of BCA2 to regulate NF-κB and IRF1 in transformed and non-tumor breast epithelial environments. Despite the fact that BCA2 promotes the transition from G1 to S phase of the cell cycle, it did not increase cell proliferation, migration nor metabolic activity. As expected, BCA2 maintains its enzymatic function at inhibiting NF-κB in different breast cancer cell lines. However, the effect of BCA2 on IRF1 differs depending on the cellular context. Specifically, BCA2 activates IRF1 in ER+ breast cell lines while it inhibits this transcription factor in ER– breast cancer cells. We hypothesize that the distinct actions of BCA2 over IRF1 may explain, at least in part, the different proposed roles for BCA2 in these cancers.
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| 6. |
- Wu, Shengnan, et al.
(author)
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Optical Fiber Fabry-Perot Microfluidic Sensor Based on Capillary Fiber and Side Illumination Method
- 2023
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In: Sensors. - : MDPI AG. - 1424-8220. ; 23:6, s. 3198-
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Journal article (peer-reviewed)abstract
- In this paper, an optical fiber Fabry-Perot (FP) microfluidic sensor based on the capillary fiber (CF) and side illumination method is designed. The hybrid FP cavity (HFP) is naturally formed by the inner air hole and silica wall of CF which is side illuminated by another single mode fiber (SMF). The CF acts as a naturally microfluidic channel, which can be served as a potential microfluidic solution concentration sensor. Moreover, the FP cavity formed by silica wall is insensitive to ambient solution refractive index but sensitive to the temperature. Thus, the HFP sensor can simultaneously measure microfluidic refractive index (RI) and temperature by cross-sensitivity matrix method. Three sensors with different inner air hole diameters were selected to fabricate and characterize the sensing performance. The interference spectra corresponding to each cavity length can be separated from each amplitude peak in the FFT spectra with a proper bandpass filter. Experimental results indicate that the proposed sensor with excellent sensing performance of temperature compensation is low-cost and easy to build, which is suitable for in situ monitoring and high-precision sensing of drug concentration and the optical constants of micro-specimens in the biomedical and biochemical fields.
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