Utilization of core-shell rather than monometallic nanocrystals (NCs) facilitates fine-tuning of NC properties for applications. However, compositional evolution via intermixing can degrade these ...properties prompting recent experimental studies. We develop an atomistic-level stochastic model for vacancy-mediated intermixing exploiting a formalism which allows incorporation at an ab initio density functional theory level of not just the thermodynamics of vacancy formation, but also relevant diffusion barriers for a vast number of possible local environments (in the core and in the shell, at the interface, and in the intermixed phase). This facilitates a predictive treatment and comprehensive understanding of intermixing on the relevant time scale (e.g., 101-103 s). In contrast, previous modeling at the atomistic level utilized only unrealistic generic prescriptions of barriers or employed simplified continuum treatments. For Au@Ag octahedral core-cubic shell NCs, our modeling not only captures the experimentally observed rate or time scale for intermixing of ∼100 s at 450 °C for 60 nm NCs, but also elucidates the underlying rate controlling processes and the effective intermixing barrier.Utilization of core-shell rather than monometallic nanocrystals (NCs) facilitates fine-tuning of NC properties for applications. However, compositional evolution via intermixing can degrade these properties prompting recent experimental studies. We develop an atomistic-level stochastic model for vacancy-mediated intermixing exploiting a formalism which allows incorporation at an ab initio density functional theory level of not just the thermodynamics of vacancy formation, but also relevant diffusion barriers for a vast number of possible local environments (in the core and in the shell, at the interface, and in the intermixed phase). This facilitates a predictive treatment and comprehensive understanding of intermixing on the relevant time scale (e.g., 101-103 s). In contrast, previous modeling at the atomistic level utilized only unrealistic generic prescriptions of barriers or employed simplified continuum treatments. For Au@Ag octahedral core-cubic shell NCs, our modeling not only captures the experimentally observed rate or time scale for intermixing of ∼100 s at 450 °C for 60 nm NCs, but also elucidates the underlying rate controlling processes and the effective intermixing barrier.
•Design and fabrication of TEGs for low temperature waste heat application.•Scalable manufacturing demonstrated using dispenser printing.•Achieved power output 33×10−6W and power density of ...2.8Wm−2.•Practical situation of pipes carrying hot fluid simulated in the lab.•The power output evaluated in forced convection and natural convection.
This work focuses on the design, fabrication and testing of thermoelectric generator (TEG) devices using dispenser printer. A series-parallel prototype of 50 couples, with 3.5mm×600μm×100μm printed element dimensions, is fabricated on a custom designed polyimide substrate. Se doped mechanically alloyed (MA) Bi2Te3 was used as the n-type material whereas Te doped MA Bi0.5Sb1.5Te3 was used as p-type material. The prototype TEG device produces a power output of 33×10−6W at 0.75×10−3A and 43×10−3V for a temperature difference of 20K resulting in a device areal power density of 2.8Wm−2. To achieve a similar power output in a practical situation, such as from pipes carrying hot fluid an experimental study in forced and natural convection is performed. In forced convection, 33×10−6W power output is achieved when the pipe surface temperature is about 373K. While, in natural convection, maximum power up to 8×10−6W power is obtained at 373K pipe surface temperature. Forced convection is desired for the system to generate sufficiently high power. In the case of natural convection, we achieved much lower power compared to forced convection. The prototype presented in this work demonstrates the feasibility of deploying a printable and “perpetual” power solution for practical wireless sensor network (WSN) applications.
Human skin is equipped with slow adapting (SA) and fast adapting (FA) capabilities simultaneously. To mimic such functionalities, elaborately designed devices have been explored by integrating ...multiple sensing elements or adopting multimode sensing principles. However, the complicated fabrication, signal mismatch of different modules, complex operation, and high power‐consumption hinder their widespread applications. Here, a new type of single‐mode and self‐powered mechanoreceptor that can mimic both SA and FA via seamless fusion of complementary while compatible potentiometric and triboelectric sensing principles is reported. The resultant potentiometric–triboelectric hybridized mechanoreceptor exhibits distinctive features that are hard to achieve via currently existing methods, including single‐mode output (only voltage signal), greatly simplified operation (single‐measurement setup), ultralow power‐consumption (<1 nW), self‐adaptive response behavior, and good capability for resolving complex stimuli. Diverse mechanical characteristics, including magnitude, duration, frequency, applying and releasing speed, can be well interpreted with this single‐mode and self‐powered mechanoreceptor. Its promising application for monitoring object manipulations with a soft robotic gripper is explored. Furthermore, the versatility of the mechanoreceptor for resolving complex stimuli in diverse daily scenarios is demonstrated. This work presents a new design that will significantly simplify the fabrication/operation and meanwhile boost the functionality/energy‐efficiency of future electronic devices and smart systems.
A new potentiometric–triboelectric hybridized mechanotransduction mechanism is proposed to create single‐mode, self‐adapting, and self‐powered artificial mechanoreceptors. Such mechanoreceptors enable complex mechanical stimuli to be resolved with greatly simplified fabrication/operation and enhanced functionality/energy‐efficiency. The promising applications of the mechanoreceptors in monitoring object manipulation and detecting complex stimuli in diverse practical scenarios of daily life is explored.
Most cancer-related deaths are a result of metastasis, and thus the importance of this process as a target of therapy cannot be understated. By asking 'how can we effectively treat cancer?', we do ...not capture the complexity of a disease encompassing >200 different cancer types - many consisting of multiple subtypes - with considerable intratumoural heterogeneity, which can result in variable responses to a specific therapy. Moreover, we have much less information on the pathophysiological characteristics of metastases than is available for the primary tumour. Most disseminated tumour cells that arrive in distant tissues, surrounded by unfamiliar cells and a foreign microenvironment, are likely to die; however, those that survive can generate metastatic tumours with a markedly different biology from that of the primary tumour. To treat metastasis effectively, we must inhibit fundamental metastatic processes and develop specific preclinical and clinical strategies that do not rely on primary tumour responses. To address this crucial issue, Cancer Research UK and Cancer Therapeutics CRC Australia formed a Metastasis Working Group with representatives from not-for-profit, academic, government, industry and regulatory bodies in order to develop recommendations on how to tackle the challenges associated with treating (micro)metastatic disease. Herein, we describe the challenges identified as well as the proposed approaches for discovering and developing anticancer agents designed specifically to prevent or delay the metastatic outgrowth of cancer.
Motivated by increased awareness about nitrate contamination of surface waters and its deleterious effects in human and animal health, we sought an alternative, non-noble metal catalyst for the ...chemical degradation of nitrate. First row transition metal phosphides recently emerged as excellent alternatives for hydrogen evolution and hydrotreating reactions. We demonstrate that a key member of this family, Ni2P, readily hydrogenates nitrate (NO3 –) to ammonia (NH3) near ambient conditions with very high selectivity (96%). One of the few non-precious metal-based catalysts for this transformation, and among ca. 1% of catalysts with NH3 selectivity, Ni2P can be recycled multiple times with limited loss of activity. Both nitrite (NO2 –) and nitric oxide (NO) intermediates are also hydrogenated. Density functional theory (DFT) indicates thatin the absence of a catalystnitrite hydrogenation is the reaction bottleneck. A variety of adsorbates (H, O, N, NO) induce surface reconstruction with top-layer Ni-rich surface stoichiometry. Critically, H saturation coverage on Ni2P(001) is only ca. 3 nm–2, significantly less than that on Pd(111) and Ni(111) of ca. 15–18 nm–2, which may play a key role in allowing coadsorption of NO x –. The ability of Earth-abundant, binary metal phosphides such as Ni2P to catalyze nitrate hydrogenation could transform and help us to better understand the basic science behind catalytic hydrogenation and, in turn, advance the next generation of oxyanion removal technologies.
The Collaborative Computational Project No. 4 (CCP4) is a UK‐led international collective with a mission to develop, test, distribute and promote software for macromolecular crystallography. The CCP4 ...suite is a multiplatform collection of programs brought together by familiar execution routines, a set of common libraries and graphical interfaces. The CCP4 suite has experienced several considerable changes since its last reference article, involving new infrastructure, original programs and graphical interfaces. This article, which is intended as a general literature citation for the use of the CCP4 software suite in structure determination, will guide the reader through such transformations, offering a general overview of the new features and outlining future developments. As such, it aims to highlight the individual programs that comprise the suite and to provide the latest references to them for perusal by crystallographers around the world.
This article describes the Collaborative Computational Project No. 4 (CCP4). It is intended as a general literature citation for the use of the CCP4 software suite in structure determination.
Previously, we reported that cellular transcription factor ZASC1 facilitates DNA-dependent/RNA-independent recruitment of HIV-1 TAT and the cellular elongation factor P-TEFb to the HIV-1 promoter and ...is a critical factor in regulating HIV-1 transcriptional elongation (PLoS Path e1003712). Here we report that cellular transcription factor ZBTB2 is a novel repressor of HIV-1 gene expression. ZBTB2 strongly co-immunoprecipitated with ZASC1 and was dramatically relocalized by ZASC1 from the cytoplasm to the nucleus. Mutations abolishing ZASC1/ZBTB2 interaction prevented ZBTB2 nuclear relocalization. We show that ZBTB2-induced repression depends on interaction of cellular histone deacetylases (HDACs) with the ZBTB2 POZ domain. Further, ZASC1 interaction specifically recruited ZBTB2 to the HIV-1 promoter, resulting in histone deacetylation and transcription repression. Depleting ZBTB2 by siRNA knockdown or CRISPR/CAS9 knockout in T cell lines enhanced transcription from HIV-1 vectors lacking Vpr, but not from these vectors expressing Vpr. Since HIV-1 Vpr activates the viral LTR by inducing the ATR kinase/DNA damage response pathway, we investigated ZBTB2 response to Vpr and DNA damaging agents. Expressing Vpr or stimulating the ATR pathway with DNA damaging agents impaired ZASC1's ability to localize ZBTB2 to the nucleus. Moreover, the effects of DNA damaging agents and Vpr on ZBTB2 localization could be blocked by ATR kinase inhibitors. Critically, Vpr and DNA damaging agents decreased ZBTB2 binding to the HIV-1 promoter and increased promoter histone acetylation. Thus, ZBTB2 is recruited to the HIV-1 promoter by ZASC1 and represses transcription, but ATR pathway activation leads to ZBTB2 removal from the promoter, cytoplasmic sequestration and activation of viral transcription. Together, our data show that ZASC1/ZBTB2 integrate the functions of TAT and Vpr to maximize HIV-1 gene expression.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Through cation exchange capacity assay, nitrogen adsorption−desorption surface area measurements, scanning electron microscopic imaging, infrared spectra and elemental analyses, we characterized ...biochar materials produced from cornstover under two different pyrolysis conditions, fast pyrolysis at 450 °C and gasification at 700 °C. Our experimental results showed that the cation exchange capacity (CEC) of the fast-pyrolytic char is about twice as high as that of the gasification char as well as that of a standard soil sample. The CEC values correlate well with the increase in the ratios of the oxygen atoms to the carbon atoms (O:C ratios) in the biochar materials. The higher O:C ratio was consistent with the presence of more hydroxyl, carboxylate, and carbonyl groups in the fast pyrolysis char. These results show how control of biomass pyrolysis conditions can improve biochar properties for soil amendment and carbon sequestration. Since the CEC of the fast-pyrolytic cornstover char can be about double that of a standard soil sample, this type of biochar products would be suitable for improvement of soil properties such as CEC, and at the same time, can serve as a carbon sequestration agent.
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