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Low-carbon investments are necessary for driving the energy system transformation that is called for by both the Paris Agreement and Sustainable Development Goals. Improving understanding of the scale and nature of these investments under diverging technology and policy futures is therefore of great importance to decision makers. Here, using six global modelling frameworks, we show that the pronounced reallocation of the investment portfolio required to transform the energy system will not be initiated by the current suite of countries’ Nationally Determined Contributions. Charting a course toward ‘well below 2 °C’ instead sees low-carbon investments overtaking fossil investments globally by around 2025 or before and growing thereafter. Pursuing the 1.5 °C target demands a marked upscaling in low-carbon capital beyond that of a 2 °C-consistent future. Actions consistent with an energy transformation would increase the costs of achieving the goals of energy access and food security, but reduce the costs of achieving air-quality goals. The scale and nature of energy investments under diverging technology and policy futures is of great importance to decision makers. Here, a multi-model study projects investment needs under countries’ nationally determined contributions and in pathways consistent with achieving the 2 °C and 1.5 °C targets as well as certain SDGs.

A series of YAG:Ce,Mn transparent ceramics were prepared via a solid-state reaction-vacuum sintering method. The effects of various Mn 2+ –Si 4+ pair doping levels on the structure, transmittance, and luminescence properties were systematically investigated. These transparent ceramics have average grain sizes of 10–16 μm, clean grain boundaries, and excellent transmittance up to 83.4% at 800 nm. Under the excitation of 460 nm, three obvious emission peaks appear at 533, 590, and 745 nm, which can be assigned to the transition 5d→4f of Ce 3+ and 4 T 1 → 6 A 1 of Mn 2+ . Thus, the Mn 2+ –Si 4+ pairs can effectively modulate the emission spectrum by compensating broad orange-red and red spectrum component to yield high quality warm white light. After the optimized YAG:Ce,Mn transparent ceramic packaged with blue light-emitting diode (LED) chips, correlated color temperature (CCT) as low as 3723 K and luminous efficiency (LE) as high as 96.54 lm/W were achieved, implying a very promising candidate for application in white light-emitting diodes (WLEDs) industry.

Significance: 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX (PpIX) fluorescence is currently used for image-guided glioma resection. Typically, this widefield imaging method highlights the bulk of high-grade gliomas, but it underperforms at the infiltrating edge where PpIX fluorescence is not visible to the eyes. Fluorescence lifetime imaging (FLIm) has the potential to detect PpIX fluorescence below the visible detection threshold. Moreover, simultaneous acquisition of time-resolved nicotinamide adenine (phosphate) dinucleotide [NAD(P)H] fluorescence may provide metabolic information from the tumor environment to further improve overall tumor detection. Aim: We investigate the ability of pulse sampling, fiber-based FLIm to simultaneously image PpIX and NAD(P)H fluorescence of glioma infiltrative margins in patients. Approach: A mesoscopic fiber-based point-scanning FLIm device (355 nm pulses) was used to simultaneously resolve the fluorescence decay of PpIX (629/53 nm) and NAD(P)H (470/28 nm). The FLIm device enabled data acquisition at room light and rapid (<33  ms) augmentation of FLIm parameters on the surgical field-of-view. FLIm measurements from superficial tumors and tissue areas around the resection margins were performed on three glioblastoma patients in vivo following inspection of PpIX visible fluorescence with a conventional neurosurgical microscope. Microbiopsies were collected from FLIm imaged areas for histopathological evaluation. Results: The average lifetime from PpIX and NAD(P)H fluorescence distinguished between tumor and surrounding tissue. FLIm measurements of resection margins presented a range of PpIX and NAD(P)H lifetime values (τPpIX       ∼  3 to 14 ns, τNAD(P)H  =  3 to 6 ns) associated with unaffected tissue and areas of low-density tumor infiltration. Conclusions: Intraoperative FLIm could simultaneously detect the emission of PpIX and NAD(P)H from patients in vivo during craniotomy procedures. This approach doubles as a clinical tool to identify tumor areas while performing tissue resection and as a research tool to study tumor microenvironmental changes in vivo. Intraoperative FLIm of 5-ALA-induced PpIX and tissue autofluorescence makes a promising surgical adjunct to guide tumor resection surgery.

In the present study, the magnetic graphene quantum dot (Fe 3 O 4 MNPs-GQDs) was synthesized successfully and characterized by using fourier transform infrared spectroscopy, transmission electron microscopy and atomic force microscopy (AFM). For the first time, as-synthesized GQDs and Fe 3 O 4 MNPs-GQDs was electrodeposited on GCE by cyclic voltammetry (CV) in the potential range from −1.0 to 1.0 V and the prepared films were used for detection of Vitamin C at physiological pH. Herein, we explore the electrocatalytical activity of Fe 3 O 4 MNPs-GQDs. We have illustrated that the as-obtained Fe 3 O 4 MNPs-GQDs exhibited a much higher electroactivity individual GQDs and Fe 3 O 4 MNPs for the electrooxidation and detection of Vitamin C which was about two fold higher than for GQDs. More importantly, a substantial (+0.21 V) decrease in the overvoltage of the Vitamin C oxidation reaction (compared to ordinary electrodes) was observed using Mag-GQDs-GCE. In general, Fast response time, excellent catalytic activity, lower overvoltage and ease of preparation are the advantages of the proposed nanosensor.

Enhanced magnetoelectric effects in two-dimensional multiferroics promise greater interests for fundamental understanding and for device applications. To ameliorate properties and multifunctionality of magnetoelectric materials, highly ordered multiferroic thin films ought to be optimally designed with a high surface area and with a minimum contact area between the substrate and the films. Fabrication of hierarchically ordered, hemispherical close-packed free-standing multiferroic thin film structures of CoFe 2 O 4 (CFO)/Pb(Zr 0.52 Ti 0.48 )O 3 (PZT)/La 0.6 Sr 0.4 MnO 3 (LSMO)/LaNiO 3 (LNO) on a Pt/Ti/SiO 2 /Si substrate using a RF magnetron sputtering technique is reported here. The hemispherical space inside the shell structures, inherited from the spherical polymer, are shown by the cross-sectional scanning transmission electron microscopy. Importantly, the observed enhancement of remanent polarization is elucidated based on the facts, like the generation of a high level of compressive stress, a large thermal expansion coefficient of LSMO, and a minimal lattice mismatch with the PZT thin film.

Hydroxyapatite (HA) powder was prepared by a sol–gel method using Ca(NO 3 ) 2 ·4H 2 O and (NH 4 ) 2 HPO 4 as raw materials. The usage of preset parameters just mixing the two raw materials only produced Ca 2 P 2 O 7 and β-Ca 3 (PO 4 ) 2 , without any evidence of HA. Then, effects of the reactant concentration, dropping speed, pH value, and mechanical stirring time on the reaction products were studied, and the process parameters were optimized. Results show that the optimum condition for the preparation of HA powder could be obtained by adding Ca(NO 3 ) 2 ·4H 2 O, (NH 4 ) 2 HPO 4 , and citric acid to the reaction base solution, in turn, adjusting the pH value of the reaction solution with concentrated nitric acid to 2.5 and stirring the reaction solution manually. The parameters of calcination process were optimized by DSC analysis, and the HA powder with good crystallinity was successfully prepared. Highlights Process parameters for preparation of hydroxyapatite (HA) by a sol–gel method were optimized. Effects of the reactant concentration, dropping speed, pH value, and mechanical stirring time on the products were studied. Large reactant concentrations and dropping speeds inhibited the formation of sol. The pH value was determined to be 2.5, and manual stirring was an appropriate stirring method. By the optimized parameters, HA powder with good crystallinity was successfully prepared.

Ca-Mg-Si ternary films were deposited at 300–335°C on (001)Al2O3 substrates by a radio-frequency magnetron sputtering. Amorphous films were obtained for a wide range of compositions but not for single-phase CaMgSi. For all compositions, the electrical conductivity of the as-deposited films increased with the increase in temperature up to 400°C. The conduction type was controlled mainly by changing the Si/(Ca + Mg + Si) ratios of the films, and films with p- and n-type conductions were observed respectively with Si/(Ca + Mg + Si) ratios below 0.6 and above 0.7 along a fixed Ca/(Ca + Mg) ratio of about 0.50. A high thermoelectric power factor above 140 μW/(m K2) with p-type conduction was obtained at 400°C for an amorphous-phase film.

The perovskite oxide strontium titanate (SrTiO 3 ) combines electrostatic tunability, superconductivity and spin–orbit coupling, and is of potential use in the development of quantum devices. However, exploring quantum effects in SrTiO 3 nanostructures is challenging because of the presence of disorder. Here we report high-mobility, gate-tunable devices in SrTiO 3 that have ballistic constrictions and clean normal-state conductance quantization. Our devices are based on SrTiO 3 two-dimensional electron gas channels that have a thin hafnium oxide barrier layer between the channel and an ionic liquid gate. Conductance plateaus show twofold degeneracy that persists for magnetic fields of at least 5 T. This is above what is expected from the g factors extracted at high fields and could be a signature of electron pairing extending outside the superconducting regime. Strontium titanate two-dimensional electron gas channels that have a thin hafnium oxide barrier layer between the channel and an ionic liquid gate can have ballistic constrictions and clean normal-state conductance quantization.

Silicon is one of the most used materials in semiconductors and electronic devices. Its miniaturization in two-dimensional (2D) scale is now a great challenge to improve and/or extend its application in many practical fields. Layered siloxene nanosheet (SiNS), a derived 2D silicon material with –H and –OH functional groups synthesized from calcium di-silicide (CaSi 2 ) have attracted a great interest while its functionalization has been barely explored. Herein, the strategy of direct exfoliation of CaSi 2 by thermal heating with benzyl groups was explored, leading to air stable functionalized silicon nanosheets. The obtained dispersible thin materials were found to be mostly Kautsky-type crystalline siloxene nanosheets that are arbitrarily terminated with benzyl, hydrogen and hydroxyl groups. Moreover, the dielectric study with temperature dependency showed high dielectric permittivities, without any conducting polymer, induced by different phenomena occurring on the layered nanosheets. Electrochemical studies displayed a diffusion-controlled process involving a fast electron transfer with the functionalized silicon-based materials as working electrodes deposited on carbon graphite electrode (CGE) in the presence of ferricyanide ions. Organo-modified siloxene are therefore potential electrode materials for electrochemical detection.