Terpenoids are a diverse group of natural products with a variety of commercial applications. With recent advances in synthetic biology and metabolic engineering, microbial terpenoid synthesis is ...being viewed as a feasible approach for industrial production. Among different microbial hosts, cyanobacteria have the potential of sustainable production of terpenoids using light and CO₂. Terpene synthases and the precursor pathways have been expressed in cyanobacteria for enhanced production of various terpene hydrocarbons, including isoprene, limonene, β-phellandrene, and farnesene. However, the productivities need to be further improved for commercial production. Many barriers remain to be overcome in order to efficiently convert CO₂ to terpenoids. In this review, we will summarize recent efforts on photosynthetic production of terpenoids and discuss the challenges and opportunities of engineering cyanobacteria for terpenoid bioproduction.
With advances in technology, wireless and sensor technologies represent a method for continuously recording people's biomedical signals, which may enhance the diagnosis and treatment of users' ...everyday health conditions. These technologies mostly target older adults. In this study, we examine a smart clothing system targeting clinically high-risk patients, including older adults with cardiovascular disease (31 outpatients) and older adults in general (81 participants), to obtain an understanding of the patients' perception of using wearable healthcare technologies. Given that technology anxiety has been shown to affect users' resistance to using new technology and that perceived ubiquity is considered a characteristic of wearable devices and other mobile wireless technologies, we included three external variables: i.e., technology anxiety, perceived ubiquity, and resistance to change, in addition to the traditional components of the technology acceptance model (TAM). The results of the hypothesized model showed that among older adults in general, technology anxiety had a negative effect on the perceived ease of use and perceived ubiquity. The perceived ubiquity construct affects both user groups' perceived ease of use and perceived usefulness of wearing smart clothes. Most relationships among the original constructs of the TAM were validated in older adults in general. Interestingly, we found that perceived usefulness had an indirect effect on behavioral intention through attitude. These results further confirm the validity of the extended TAM in determining older users' technology acceptance behavior.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Cyanobacteria are attractive microbial hosts for production of chemicals using light and CO
. However, their low productivity of chemicals is a major challenge for commercial applications. This is ...mostly due to their relatively slow growth rate and carbon partitioning toward biomass rather than products. Many cyanobacterial strains synthesize sucrose as an osmoprotectant to cope with salt stress environments. In this study, we harnessed the photosynthetic machinery of the fast-growing cyanobacterium Synechococcus elongatus UTEX 2973 to produce sucrose under salt stress conditions and investigated if the high efficiency of photosynthesis can enhance the productivity of sucrose. By expressing the sucrose transporter CscB, Synechococcus 2973 produced 8 g L
of sucrose with a highest productivity of 1.9 g L
day
under salt stress conditions. The salt stress activated the sucrose biosynthetic pathway mostly via upregulating the sps gene, which encodes the rate-limiting sucrose-phosphate synthase enzyme. To alleviate the demand on high concentrations of salt for sucrose production, we further overexpressed the sucrose synthesis genes in Synechococcus 2973. The engineered strain produced sucrose with a productivity of 1.1 g L
day
without the need of salt induction. The engineered Synechococcus 2973 in this study demonstrated the highest productivity of sucrose in cyanobacteria.
Liquid crystal displays (LCDs) and photonic devices play a pivotal role to augmented reality (AR) and virtual reality (VR). The recently emerging high-dynamic-range (HDR) mini-LED backlit LCDs ...significantly boost the image quality and brightness and reduce the power consumption for VR displays. Such a light engine is particularly attractive for compensating the optical loss of pancake structure to achieve compact and lightweight VR headsets. On the other hand, high-resolution-density, and high-brightness liquid-crystal-on-silicon (LCoS) is a promising image source for the see-through AR displays, especially under high ambient lighting conditions. Meanwhile, the high-speed LCoS spatial light modulators open a new door for holographic displays and focal surface displays. Finally, the ultrathin planar diffractive LC optical elements, such as geometric phase LC grating and lens, have found useful applications in AR and VR for enhancing resolution, widening field-of-view, suppressing chromatic aberrations, creating multiplanes to overcome the vergence-accommodation conflict, and dynamic pupil steering to achieve gaze-matched Maxwellian displays, just to name a few. The operation principles, potential applications, and future challenges of these advanced LC devices will be discussed.
Heparin‐binding hemagglutinin (HBHA) is a 199 amino acid virulence factor at the envelope of Mycobacterium tuberculosis that contributes to latent tuberculosis. The binding of HBHA to respiratory ...epithelial cells, which leads to extrapulmonary dissemination of the pathogen, is mediated by cell‐surface heparan sulfate (HS). We report the structural characterization of the HBHA/HS complex by NMR spectroscopy. To develop a model for the molecular recognition, the first chemically synthesized uniformly 13C‐ and 15N‐labeled HS octasaccharide and a uniformly 13C‐ and 15N‐labeled form of HBHA were prepared. Residues 180–195 at the C‐terminal region of HBHA show large chemical shift perturbation upon association with the octasaccharide. Molecular dynamics simulations conforming to the multidimensional NMR data revealed key electrostatic and even hydrophobic interactions between the binding partners that may aid in the development of agents targeting the binding event.
Clearly labeled: The structure of the complex between heparan sulfate and the mycobacterial heparin‐binding hemagglutinin was characterized by NMR spectroscopy using uniformly 13C‐ and 15N‐labeled forms of the sugar and protein. Notable chemical‐shift perturbations occurred at the C‐terminal residues of the protein. Molecular dynamics simulations based on the NMR data show electrostatic and hydrophobic interactions between the binding partners.
Twinning is demonstrated to be an effective way of enhancing efficiencies of metallic catalysts toward electrolytic water splitting. Dendritic Cu possessing dense coherent nanotwin (NT) boundaries ...(NTCu‐5nm) is successfully prepared with an organic‐assisted electrodeposition at high pulse current densities. NT boundaries significantly improve electrocatalytic efficiencies and stability of NTCu‐5nm over nanocrystalline Cu (NCCu), reducing overpotentials at 10 mA cm−2 for the oxygen evolution reaction (OER) from 378 to 281 mV and from 235 to 88 mV for the hydrogen evolution reaction (HER), with a small chronoamperometric decay of 5% after 100 h continuous overall water splitting at an ultrahigh initial current density of 500 mA cm−2, largely outperforming the large chronoamperometric decay of 27% for only 1 h operation of the NCCu//NCCu couple. The defective twin boundaries enable formation of active CuIIIO2− at low overpotentials, thus enhancing OER performance. The synergistic geometric and electronic effects induced by the twin boundaries result in shifts in Gibbs free energies of hydrogen adsorption (ΔGH) toward the apex of a volcano plot of exchange current density versus ΔGH, leading to the remarkable improvement in HER activity.
Dendritic Cu, possessing abundant narrowly spaced coherent twin boundaries, demonstrates its remarkable catalytic performance toward electrolytic water splitting. The success is attributed to enhanced electrical and chemical properties of the twinned phase. The present work opens a new promising chapter for breakthrough catalyst design through 2D defect engineering, and can be extended to a wide range of catalytic processes.
In recent years, plant genetic engineering has advanced agriculture in terms of crop improvement, stress and disease resistance, and pharmaceutical biosynthesis. Cells from land plants and algae ...contain three organelles that harbor DNA: the nucleus, plastid, and mitochondria. Although the most common approach for many plant species is the introduction of foreign DNA into the nucleus (nuclear transformation) via Agrobacterium- or biolistics-mediated delivery of transgenes, plastid transformation offers an alternative means for plant transformation. Since there are many copies of the chloroplast genome in each cell, higher levels of protein accumulation can often be achieved from transgenes inserted in the chloroplast genome compared to the nuclear genome. Chloroplasts are therefore becoming attractive hosts for the introduction of new agronomic traits, as well as for the biosynthesis of high-value pharmaceuticals, biomaterials and industrial enzymes. This review provides a comprehensive historical and biological perspective on plastid transformation, with a focus on current and emerging approaches such as the use of single-walled carbon nanotubes (SWNTs) as DNA delivery vehicles, overexpressing morphogenic regulators to enhance regeneration ability, applying genome editing techniques to accelerate double-stranded break formation, and reconsidering protoplasts as a viable material for plastid genome engineering, even in transformation-recalcitrant species.
This paper proposes a new pixel circuit using low-temperature polycrystalline silicon thin-film transistors (LTPS TFTs) for use in mobile active matrix organic light-emitting diode (AMOLED) displays. ...The purpose of a pixel circuit is to supply stable and uniform currents to current-driving devices of OLEDs. The proposed pixel circuit uses overlapping compensation times to extend the period of precise sensing of <inline-formula> <tex-math notation="LaTeX">V_{\mathrm {TH}} </tex-math></inline-formula> variations of LTPS TFTs. Moreover, the proposed circuit prevents a current from flowing into an OLED when the OLED is not operated in the emission stage to avoid image flicker. An 1.3-in panel that uses the proposed pixel circuit is fabricated. Measurement results verify that the increased <inline-formula> <tex-math notation="LaTeX">T_{\mathrm {COMP}} </tex-math></inline-formula> of 33.3 <inline-formula> <tex-math notation="LaTeX">\mu \text{s} </tex-math></inline-formula> results in higher contrast ratio and lower required data voltages than those at <inline-formula> <tex-math notation="LaTeX">T_{\mathrm {COMP}} </tex-math></inline-formula> values of 4.3 and 2.2 <inline-formula> <tex-math notation="LaTeX">\mu \text{s} </tex-math></inline-formula>. Red, green, and blue images displayed by the fabricated panel with a <inline-formula> <tex-math notation="LaTeX">T_{\mathrm {COMP}} </tex-math></inline-formula> of 33.3 <inline-formula> <tex-math notation="LaTeX">\mu \text{s} </tex-math></inline-formula> with a 255 gray level are all much more uniform than with <inline-formula> <tex-math notation="LaTeX">T_{\mathrm {COMPS}} </tex-math></inline-formula> of 4.3 and 2.2 <inline-formula> <tex-math notation="LaTeX">\mu \text{s} </tex-math></inline-formula>. White images with a <inline-formula> <tex-math notation="LaTeX">T_{\mathrm {COMP}} </tex-math></inline-formula> of 33.3 <inline-formula> <tex-math notation="LaTeX">\mu \text{s} </tex-math></inline-formula> for 16 and 8 gray levels on the fabricated panel confirm that the serious line and spot defects in the images with <inline-formula> <tex-math notation="LaTeX">T_{\mathrm {COMP}} </tex-math></inline-formula> values of 4.3 and 2.2 <inline-formula> <tex-math notation="LaTeX">\mu \text{s} </tex-math></inline-formula> are effectively eliminated. Therefore, the proposed pixel circuit is suitable for use in mobile AMOLED displays.
The prevalence of drug‐resistant bacterial pathogens foreshadows a healthcare crisis. Calcium‐dependent antibiotics (CDAs) are promising candidates to combat infectious diseases as many of them show ...modes of action (MOA) orthogonal to widespread resistance mechanisms. The calcium dependence is nonetheless one of the hurdles toward realizing their full potential. Using laspartomycin C (LspC) as a model, we explored the possibility of reducing, or even eliminating, its calcium dependence. We report herein a synthetic LspC analogue (B1) whose activity no longer depends on calcium and is instead induced by phenylboronic acid (PBA). In LspC, Asp1 and Asp7 coordinate to calcium to anchor it in the active conformation; these residues are replaced by serine in B1 and condense with PBA to form a boronic ester with the same anchoring effect. Using thin‐layer chromatography, MS, NMR, and complementation assays, we demonstrate that B1 inhibits bacterial growth via the same MOA as LspC, i.e., sequestering the cell wall biosynthetic intermediate undecaprenyl phosphate. B1 is as potent and effective as LspC against several Gram‐positive bacteria, including methicillin‐resistant Staphylococcus aureus and vancomycin‐resistant Enterococcus. Our success in converting a CDA to a boron‐dependent antibiotic opens a new avenue in the design and functional control of drug molecules.
The side‐chain carboxylates of Asp1 and Asp7 in laspartomycin coordinate with a calcium cation to adopt the active conformation. When these residues were replaced by serine, calcium dependence was eliminated and the resulting synthetic analogue depended instead on phenylboronic acid for its antimicrobial activity.
Nitrous oxide (N2O) is a commonly used inhaled anesthetic in outpatient dental procedures. However, the increasing recreational use of N2O may result in vitamin B12 deficiency-related neurologic and ...psychiatric symptoms. The aim of this study was to demonstrate the clinical features of chronic N2O abuse in pediatric patients.
Patients under 20 years of age who were diagnosed with N2O-induced subacute combined degeneration of the spinal cord from 2012 to 2018 were enrolled in this study. Clinical presentations, laboratory, imaging, ancillary studies, treatments and outcomes were analyzed.
Nine patients were included, all of whom presented with symptoms of myeloneuropathy including limb numbness, limb weakness or unsteady gait. Six patients had low or low-normal vitamin B12 (cyanocobalamin) levels. Eight patients had evidence of subacute combined degeneration of the spinal cord via neuroimaging studies. All of the patients received vitamin B12 supplementation as treatment. All had full recovery of muscle power within 2 months. Five patients had persistent sensory deficits.
Chronic N2O abuse can cause permanent neurological damage if not treated promptly. Clinical staff should be aware of the various presentations of neurotoxicity related to N2O abuse.
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