Despite the presence of hydride anions, the compound decomposes only slowly in air. Doped with Eu2+, it shows broad‐band orange‐red emission under violet excitation owing to the 4f65d–4f7 transition of Eu2+. The observed 1H NMR chemical shift is in good agreement with previously reported 1H chemical shifts of ionic metal hydrides as well as with quantum chemical calculations and very different from 1H chemical shifts usually found for hydroxide ions in similar materials. FTIR and Raman spectroscopy of different samples containing 1H, 2H, natB, and 11B combined with calculations unambiguously prove the absence of hydroxide ions and the sole incorporation of hydride ions into the borate. The orange‐red emission obtained by doping with Eu2+ shows that the new compound class might be a promising host material for optical applications.The unprecedented borate hydride Sr Enlighten me! The unprecedented borate hydride (deuteride) Sr5(BO3)3H (Sr5(BO3)3D) is synthesized mechanochemically and its structure is determined by neutron diffraction. DFT calculations, NMR, IR, and Raman measurements unambiguously confirm the successful synthesis. An orange‐red phosphor is obtained upon doping with Eu2+. In addition to divalent europium, it was also shown that hydride has an influence on the excitation spectra of Tb3+.The chemical and physical properties of ionic materials usually do not only depend on the cation chemistry, but also to a large extent on the anion chemistry and combinations of different anions.5(BO3)3F:Ln 5(BO3)3Cl:Eu2+[34] and the fully substituted variant Eu5(BO3)3F5(BO3)3F5(BO3)3H. Although attempts to obtain the compound by classical solid‐state techniques were so far unsuccessful, the desired compound could be prepared by a mechanochemical approach. Such mechanochemical reactions have been previously applied to, for instance, synthesize borohydrides1H MAS (magic angle spinning) NMR spectroscopy and vibrational spectroscopy, together with quantum chemical calculations of the corresponding spectra as well as X‐ray and neutron powder diffraction. Finally, photoluminescence properties of incorporated Eu2+ ions in the compound were also studied and a promising orange‐red broad band emission was observed, which shows the typical features of the 4f65d–4f7 transition of Eu2+.Besides compound classes such as nitrides and oxide nitrides,3(BO3)2 with SrH2 first yields  a powder showing a diffraction pattern with broad reflections of the reactants together with a new set of reflections, which is assigned to the desired compound Sr5(BO3)3H crystallizing in the same structure type as the previously reported Sr5(BO3)3F.Kα radiation) of the borate hydride and a so far experimentally unknown borate hydroxide were compared and significant differences in the patterns are visible . As H is a weak X‐ray scatterer, additional neutron powder diffraction data on the high‐resolution neutron powder diffractometer D2b at the ILL, Grenoble, were recorded. Owing to the large absorption of neutrons by 10B in the natural isotope mixture natB, 11B‐enriched samples had to be prepared. Additionally, 1H shows a high incoherent scattering cross section. Thus, 2H‐enriched samples were studied.11BO3)3D is shown in Figure 5(BO3)3F.Mechanochemical reaction of carefully dried Sr5(11BO3)3D, respectively, were found to be in good agreement with the structural model of Sr5(BO3)3F.Pnma (No. 62) with a=7.1982(3) Å, b=14.1461(7) Å, c=9.8215(4) Å, and V=1000.10(8) Å3. These obtained lattice parameters are slightly larger than for the fluoride analog ,c site resulted in a value of 0.915(14). Because the compound is a typical ionic compound, a partial occupation can be excluded. As the occupancy of the deuterium site strongly correlates with the thermal displacement parameter Biso (64 %) of the same atom, we assume a full occupation of the deuterium site, resulting in the chemical formula Sr5(11BO3)3D. We therefore present both results of the refinement in Tables S1 and S2.The refinements of the structural model for both the X‐ray and neutron powder data of Sr5(11BO3)3D. The refinement plot is depicted in the Supporting Information in Figure S5. This structural model yields significantly higher residual values compared with the refinement of the structural model of Sr5(BO3)3F. Hence, based on crystallographic evaluation, we exclude the borate hydroxide as a potential product in our synthesis.To further distinguish the borate hydride from a potential hydroxide, we also used the structural model we had obtained in quantum chemical calculations for a hypothetical hydroxide and refined that model against the powder neutron pattern of Sr5(BO3)3H is depicted in Figure a axis: Firstly, a double chain of Sr3 centered monocapped square antiprisms (nine oxide anions) and, secondly, channels of hydride surrounded by Sr1 and Sr2 polyhedra. The Sr1 atoms are eight‐fold coordinated by seven oxide anions and one hydride anion. They share faces with two further Sr2 centered polyhedra. The Sr2 polyhedron is composed of six oxide anions and one hydride anion. The different coordination spheres are shown in Figure S2 in the Supporting Information.The crystal structure of Sr5(11BO3)3D or Sr5(BO3)3H . When Sr5(BO3)3H or Sr5(11BO3)3D are added to water, H2 or HD gas evolution is observed, respectively. The main decomposition product upon contact with water can be identified as strontium boron hydroxide Sr[B(OH)4]2 . It is noteworthy that the gas evolution is still observable after exposure of Sr5(11BO3)3D or Sr5(BO3)3H to dry air for several days and subsequent contact with water. Furthermore, elemental analysis on Sr5(11BO3)3D resulted in a deuterium content of 0.32 wt % .The compound decomposes only slowly if stored in air as is evident from X‐ray powder diffraction and vibrational spectroscopy. X‐ray powder patterns recorded after several days of exposure to dry air still revealed the presence of significant amounts of Sr1H MAS NMR has proven to be a very useful tool to identify hydride species in mixed anionic hydride compounds and differentiate between hydride and hydroxide species.1H MAS NMR spectrum of Sr5(BO3)3H measured at a spinning frequency of 15 kHz is depicted. At a chemical shift of 5.8 ppm, one sharp signal with additional spinning side bands with a distance of 15 kHz can be observed. Quantum chemical calculations of the solid‐state 1H NMR shifts at the DFT‐PBE/USPP level of theory yields a chemical shift of 5.9 ppm, which is in perfect agreement with the observed experimental value. The observation of one sharp signal is also in good agreement with the fact that the structure model features a single site for the hydride ions, which are octahedrally surrounded by Sr2+ ions only.Lately, 1H chemical shift of 5.5 ppm)1H NMR shift of such a hypothetical Sr5(BO3)3OH at the DFT‐PBE/USPP level of theory. The correspondingly expected chemical shift was at 3.9 ppm, clearly different from the chemical shift found for the hydride. For comparison, in phosphate hydroxide of the apatite family, the 1H chemical shift of the OH group is usually located at approximately −0.40 ppm.Furthermore, the observed chemical shift is in very good agreement with recent findings on a phosphate hydride (5(BO3)3H as well as the deuteride Sr5(11BO3)3D were characterized by vibrational spectroscopy and compared with computational spectra. Figure −1 for the borate hydride as synthesized and after exposure to dry air. The inset depicts the region between 3800–3200 cm−1. Usually, stretching vibrations of hydroxide are observed at about 3500–3600 cm−1.Both the hydride Sr−1. The IR‐active vibrations have been assigned by means of quantum chemical calculations and can be found in the lower part of Figure −1. Both modes represent a vibration that is parallel to the plane formed by the three nearest strontium neighbors, herein called ′hydride in‐plane mode′. For a visual representation of these modes and the geometry, see Figure S18 (in the Supporting Information). At 593 cm−1 and 546 cm−1, sharp ′hydride out‐of‐plane modes′ are observed, which can be described as the hydride vibration that moves perpendicular to the Sr triangle. For comparison, vibrational spectra of Sr5(11BO3)3D were also recorded. However, the isotope effect of the B atoms on the IR spectra is almost negligible.In Figure 11B isotope in the Sr5(11BO3)3D compound. The deuteride vibrations, however, can be expected to be shifted to lower wavenumbers by approximately a factor of 2and, indeed, the calculated and experimental IR vibrations of the deuteride are in very good agreement. The ′in‐plane′ modes can now be found at 705 and 627 cm−1, respectively, corresponding almost perfectly to a factor of 2compared with the hydride vibrations. Although the mode at 705 cm−1 is clearly observed in the experimental spectra, the mode at 627 overlaps with B−O bending modes. The ′out‐of‐plane′ modes of the deuteride (=593 cm−1 for the hydride) are shifted to the low energetic detection limit of the employed device such that only one of those modes located at around 405 cm−1 could be recorded experimentally.The borate vibrations are only slightly shifted, accounting for the pure 5(BO3)3H and Sr5(11BO3)3D are depicted in Figure −1, a strong signal in the Raman spectrum of the borate hydride can be attributed to the ′out‐of‐plane mode′ respective to the plane formed by the three nearest strontium atoms. Calculated resonances of the hydride modes at 862, 972, and 999 cm−1 are related to weak transition intensities, as is observed in the experimental spectra.The experimental and calculated Raman spectra of Sr−1, again in excellent agreement with quantum chemical predictions. Its vibrational energy is also reduced by a factor of 2compared with the respective vibrational transition in the hydride. In addition, the ′in‐plane mode′ is located at 658 cm−1. The general assignment of the different B−O modes is also in very good agreement with the collection of vibrational energies found in borates reported in Ref. The deuteride ′out‐of‐plane vibration′, labeled in gray, is observed at 402 cm5(BO3)3H and Sr5(BO3)3F have been determined at the DFT‐PBE0/TZVP level of theory . Both compounds are insulators with an indirect band gap of approximately 7.5 eV for the fluoride compound and 7.0 eV for Sr5(BO3)3H. For band gaps as large as 7 eV, the hybrid PBE0 functional with 25 % of exact exchange may slightly underestimate the experimental gap, whereas the PBE functional is expected to underestimate the band gap even more (here DFT‐PBE predicts a band gap of 4.8 eV for Sr5(BO3)3H).5(BO3)3F are the oxygen 2p orbitals, which appear as rather flat bands . In contrast, the situation changes in Sr5(BO3)3H. Here, the topmost valence bands are steeper compared with the fluoride analog and the DOS analysis shows that the 1s hydride orbital is mostly responsible for the raising of the valence band and therefore the reduction of the band gap compared with Sr5(BO3)3F. Both compounds can be regarded as ionic materials, but in Sr5(BO3)3H a more covalent behavior owing to the polarizability of hydride is noticeable in the topology of bands. This reduction of the band gap by hydride ligands compared with their fluoride counterparts is in line with previous literature reports and reflects the strong covalent character of the hydride compound.Additionally, band structures and densities of states for Sr5(BO3)3H doped with 3.75 mol % Eu shows orange luminescence upon excitation with violet light (λex=420 nm). Photoluminescence emission (PL) and excitation spectra (PLE) at 20 K are depicted in Figure 65d1–4f7 transition of Eu2+.Sr2+‐related emission in the doped borate hydride decreases approximately linearly, which is depicted in Figure 5(BO3)3H, there are three crystallographically unique Sr2+ sites, which can be substituted by Eu2+ ions. Two of these three sites have H− ions in their coordination sphere. According to the coordination number and the average metal–ligand distance, the crystal field splitting for short metal–ligand distances is expected to be the largest. The Sr3 site has a coordination number of nine with only oxide ions and an average Sr−O distance of d(Sr‐O)=2.70 Å . Sr1 is eightfold coordinated with seven oxide ions and one hydride ion. The average Sr–ligand distance is 2.64 Å in that case. Lastly, the Sr2 site has seven anions in its coordination sphere, out of which six are oxide ions and one is a hydride ion. The Sr–ligand distance at that site is about 2.61 Å. Therefore, we tentatively assign the high energy band at around 570 nm to Eu2+ ions on the Sr3 site with the longest average Sr–ligand distances and solely more ionic oxide ligands in the first coordination sphere. The lower energetic emission bands are assigned to Eu2+ ions on Sr sites with more covalent chemical bonding character to the surrounding ligands owing to the presence of the hydride ion in the coordination sphere (see section on electronic properties). The dominant emission band is tentatively assigned to Eu2+ ions on the Sr1 site given the longer average Sr–ligand distances and the low energy shoulder to the sevenfold coordinated Sr2 site with shorter Sr–ligand distances. Actual deconvolution of the photoluminescence emission at 20 K reproduces these three peaks only to a certain degree, because the overlap of the bands from different sites is rather large. The integrated intensity is reduced to half of its initial maximum at around T50 %=240 K, which is thus estimated as a measure for the quenching temperature .Upon increase of the temperature, the absolute intensity of the Eu−1, which decreases slightly until 125 K to about 2250 cm−1 and may be attributed to the high energy shoulder vanishing . This indicates that Eu2+ on the Sr3 has a low (=100 K) quenching temperature, which could be related to the higher energy position of the emitting 4f65d state and thermally activated photoionization to the conduction band. From 125 K, the FWHM increases linearly with a larger slope to about 2600 cm−1 at room temperature. This increase is usual for broad‐band emitters and related to the thermal excitation of phonon modes, which increase the probability for Stokes‐ and anti‐Stokes vibronic transitions, thus effectively increasing the FWHM of the respective emission band.Normalized temperature‐dependent luminescence spectra are shown in Figure S15 (in the Supporting Information). At 20 K, the full width at half maximum (FWHM) is about 2320 cmx=0.56585 and y=0.42780.For phosphors, the emitted color perceived by the human eye is another important material property, which is typically evaluated by the CIE coordinates . A corresponding plot is depicted in Figure 2+‐doped strontium borates, the emission energy was reported to range from UV to orange. Table 65d1→4f7 emission bands, average Sr−O distances, and the coordination number around the oxygen atoms. In particular, the latter is the decisive part that determines the emission energies in these compounds.Generally, in Eu2+‐doped strontium and barium borates that a low coordination of oxide ions by alkaline earth metal cations, such as in SrB4O7, results in higher energetic emission. In borates with oxide ions being coordinated by more alkaline earth metal cations, the emission is always widely redshifted.2+–oxide bonds in borates or aluminates.3+/Al3+ ions around oxide anions, they become rather hard Lewis bases or, alternatively, strongly ionic ligands. More Sr2+ cations around an oxide ion effectively increase the optical basicity of the ligand. The oxide ions become better σ‐donating ligands and, consequently, the chemical bond between the cations and the oxide ligand is more covalent. The extreme case is SrO:Eu2+ without any B3+ or Al3+ ions and a 4f65d–4f7 emission wavelength of 630 nm.III phosphates, in which a clear linear correlation between the σ‐donating character of the ligands and their optical basicity could be observed.5(BO3)3F:Eu2+ and Sr5(BO3)3H:Eu2+, oxygen atoms are surrounded by three and four strontium atoms, which will lead to a higher covalency in both cases and should lead to an expected orange emission irrespective of the second anion. For the polyhedra around the different oxygen atoms, see Figure S3 (in the Supporting Information). In the hydride compound, the emission is additionally redshifted compared with the isotypic fluoride compound. This can be explained by the covalency  and the additional nephelauxetic effect of the hydride anions, which has also been observed in other Eu2+‐doped metal hydrides.2+ luminescence may also be a tool to indirectly prove the incorporation of hydride anions in new mixed anionic materials, where such incorporation is difficult to detect with other characterization methods.Diaz and Keszler found in their studies on Eu2+, the compound shows orange‐red luminescence emission upon excitation with violet light. Incorporation of hydride ligands in the coordination environment of Eu2+ is shown to be an effective method to tune the Eu2+ emission color and induce a redshift to realize the desired emission color.To the best of our knowledge, we report the synthesis of the first borate hydride. The current findings could open up a new class of materials. The proof of hydrogen incorporation in the presented compound is far from trivial and could be confirmed by several independent methods such as neutron powder diffraction, solid‐state NMR and vibrational spectroscopy, quantum chemical electronic calculations, and luminescence spectroscopy. Unlike the conventionally experienced instability of hydrides in air, the compounds decompose only slowly in dry air. If doped with Eu5(BO3)3H, a mixture of Sr3(BO3)2 and SrH2 (100 % excess) was used. Sr3(BO3)2 can be synthesized by heating stoichiometric amounts of SrCO3  and H3BO3  in a muffle furnace at 1100 °C for 48 h. SrH2 was obtained by reacting strontium metal  at 60 bar hydrogen pressure  in a hydrogen resistant autoclave (Böhler L718) at 550 °C for 48 h. Sr5(BO3)3H was then synthesized mechanochemically by mixing dried Sr3(BO3)2 and SrH2 in a Fritsch Pulverisette 7 Premium Line ball mill in a 20 mL WC (tungsten carbide) grinding bowl with 10 WC balls (10 mm diameter) at a speed of 600 rpm for a total of 240 cycles (4 times 60 cycles) under argon atmosphere. One cycle consisted of 2 min of milling and 3 min pauses to reduce heating of the sample and the herein called set comprised of 60 cycles. Between each set, the sample was removed from the grinding bowl to crush it again. To improve the crystallinity of the milled sample, it was then heated in an evacuated glass ampoule to 420 °C for 10 days. Deuterated  and 11B‐enriched samples Sr5(11BO3)3D for neutron diffraction were synthesized by using SrD2 and H311BO3  as starting materials following the procedure described above for the hydride. For Eu‐doping, Eu2O3 was added during the synthesis of Sr3(BO3)2. In previous works, it has been shown that Eu3+ is inherently reduced to Eu2+ during the synthesis of borates.2. All handling was performed under argon atmosphere.For the synthesis of the borate hydride Sr Böhler L8 at 550 Kα1 radiation and a solid‐state detector (Mythen 1 K) in 0.3 mm glass capillaries.X‐ray diffraction data was collected with a Stoe StadiP diffractometer with transmission geometry, CuBiso, profile and shape parameters as well as asymmetry functions have been refined. Background points were refined with scalable height. Structural parameters are shown in Tables S1–S3 (in the Supporting Information). The raw data can be requested under https://doi.org/10.5291/ILL‐DATA.EASY‐475.Neutron diffraction experiments were conducted with the high‐resolution two‐axis diffractometer D2B at the Institute Laue‐Langevin (ILL), Grenoble, with a wavelength of 1.594 Å over the course of 5 h. Samples were enclosed in air‐tight 8 mm vanadium cylinders. Rietveld refinement of X‐ray and neutron diffraction data was carried out by using the FullProf program package.Deposition Number 1999692 contains the supplementary crystallographic data for this paper. These data are provided free of charge by the joint Cambridge Crystallographic Data Centre and Fachinformationszentrum Karlsruhe Access Structures service www.ccdc.cam.ac.uk/structures.1H NMR spectra were collected with a Bruker AV300 at 7.05 T with a spinning frequency of 15 kHz in 4 mm ZrO2 rotors with a Kel‐F cap at room temperature. To determine 1H background signals, the empty rotor and cap was measured.Magic angle spinning (MAS) solid‐state 1H NMR chemical shifts of Sr5(BO3)3H and a hypothetical hydroxide Sr5(BO3)3OH were calculated by using the DFT‐PBE method5(natBO3)31H as well as Sr5(11BO3)3D were calculated with the CRYSTAL program packageSolid‐state −1 with a spectral resolution of 1 cm−1. Additionally, one sample  spectrometer with a diamond sensor. To avoid water and oxygen contamination, the device was operated inside an argon‐filled glovebox. Measurements were taken between 4000 and 500 cmλ=532 nm laser in the range 100–1000 cm−1.Raman spectra were recorded from powders sealed in glass capillaries (0.3 mm diameter) with a Renishaw inVia Reflex Raman System equipped with a CCD detector and a −1, 300 nm blaze) and double monochromator  in the emission compartment, respectively. The emitted light was detected with a Hamamatsu‐R928P photomultiplier tube. Samples were enclosed in quartz ampoules with 5 mm diameter. Temperature‐dependent photoluminescence spectra were acquired with an Edinburgh FLS920 spectrometer equipped with a 450 W Xe lamp, 0.25 m double grating monochromators in both excitation  and emission  compartment and a Hamamatsu‐R928P photomultiplier tube as detection system. The sample was cooled with an Oxford Instruments liquid He flow cryostat with external temperature control unit. All spectra were corrected for the wavelength‐dependent sensitivity of the PMT and monochromator light output, whereas excitation spectra were corrected for the reference signal of the Xe lamp and grating efficiency.Room‐temperature photoluminescence and emission were recorded with a Fluorolog FL322 equipped with a 450 W Xenon lamp and double monochromator in the excitation  should be addressed to the authors.SupplementaryClick here for additional data file.


These conversions can be facilitated using either heat or light; however, until now, the limited optical absorption intensity evidenced by the pale-yellow color of In2O3 has prevented the use of both together. To take advantage of the heat and light content of solar energy, it would be advantageous to make indium oxide black. Herein, we present a synthetic route to tune the color of In2O3 to pitch black by controlling its degree of non-stoichiometry. Black indium oxide comprises amorphous non-stoichiometric domains of In2O3-x on a core of crystalline stoichiometric In2O3, and has 100% selectivity towards the hydrogenation of CO2 to CO with a turnover frequency of 2.44 s−1.Nanostructured forms of stoichiometric In 2 hydrogenation photocatalysts has been hindered by their limited light-harvesting ability. By making stoichiometric white indium oxide non-stoichiometric and black, it is transformed from a highly inactive to a highly active photothermal catalyst.The utilization of white-colored, wide-bandgap CO Unlike traditional photocatalysis, which is limited to the use of higher-energy photons, photothermal catalysis can theoretically utilize the full wavelength range of the solar spectrum to facilitate surface chemical reactions12.Exploitation of the photothermal effect, specifically to enhance the production of synthetic fuels via gas-phase heterogeneous CO7. While these two processes appear to be antithetical, requiring one to be optimized at the expense of the other, both are expected to benefit from materials that provide high optical absorption strength over the entire solar spectral wavelength range.Optimizing the photonic efficiency of these reactions requires control over the thermal relaxation processes that create high local temperatures and drive surface thermochemical reactions, and the electron−hole generation and separation processes that facilitate surface photochemical reactions2 to value-added products. Unfortunately, no such materials currently exist.Achieving peak photothermal performance would require the use of black, high surface area nanostructures capable of concurrent thermochemical and photochemical hydrogenation of CO2O3). In its pristine form, In2O3 is a pale yellow thermal insulator with a wide electronic bandgap, absorbing light mainly in the ultraviolet wavelength range and thereby minimizing its ability to function as a photothermal CO2 hydrogenation catalyst18.Our approach to this problem focuses attention on stoichiometric indium oxide  under ambient conditions with 100% selectivity. Compared to pale yellow In2O3, with its CO production rate of 0.78 μmol h−1 m−2 (19.64 μmol g−1 h−1) in light, black In2Ox3−/In2O3 can drive the reaction at 1874.62 μmol h−1 m−2 , approximately three orders of magnitude greater than both stoichiometric In2O3 and about three orders of magnitude larger than the best reported RWGS rate of all known indium-oxide-based photocatalysts  for 1 h to form In2Ox3−/In2O3 with different x values, labeled S2, S3 and S4, respectively.The as-prepared indium oxide nanocrystals (S1) devoid of hydroxide groups was synthesized via thermal dehydroxylation of In(OH)2O3 and are devoid of metallic indium, indicating that the black color created during hydrogenation is intrinsic to the indium oxide itself. The cubic bixbyite In2O3 is a fluorite-type structure In2O3 with one fourth of the anions missing indicates a periodic structure that produces 25% structural vacancies20. The grain sizes calculated from the width of the strongest PXRD peak at 30.6° were found to be 20.6, 30.9, 33.0 and 36.3 nm for S1 through S4, respectively, which confirmed slight size growth with increasing temperature of the hydrogenation.Powder X-ray diffraction (PXRD) patterns of all samples are shown in Fig. I, InO6) and the unsaturated lattice oxygen that generated by the formation of oxygen vacancy , with the latter population increasing with the temperature of the hydrogenation process, as consistent with the following reaction: In2O3 + xH2 → In2Ox3− + xH2O  of In 3d and Auger LMM 3d electronic transitions served to establish the oxidation state of indium as In(III)  and indicates a very similar value of the weight change (84.94%) for S1 to the theoretical stoichiometric In2O3 (83.7%), where the very slight excess can be attributed to absorbed water 2 g−1, respectively, with a pore diameters ranging from 29 to 64 nm -specific surface areas of S1–S4 paralleled the monotonic trend of increasing nanocrystal size, registering at 25.15, 15.30, 14.74 and 12.74 mHigh-resolution transmission electron microscopy (HRTEM) were employed to investigate the morphology of all samples. The HRTEM images shown in Supplementary Fig. The optical reflectance spectra (UV-Vis-NIR) for S1–S4 show a trend of gradually increasing absorption, broadening and red shifting of the ultraviolet absorption edge into the visible region with higher temperatures of the hydrogenation  and broadening  24. The ratio between InO6 (132.3 cm−1) and InOx6− (366.5 cm−1) exhibits a monotonically increasing trend from S1 to S4 and implies an increasing concentration in [O]. Further Raman spectroscopy with different beam intensities were conducted over S3 and S4 to study their photothermal effects. The Raman signal located at ~308 cm−1 has been assigned to a vibrational/phonon mode of an InO6 site and is used as the probe/reference signal. The resulting Raman signals for S4 exhibit blue shift with increasing beam intensities  gradually shift from 304.18 to 302.90, 302.68 and 300.63 cm−1 and indicates an increasing trend of photothermal local temperatures. On the contrary, no significant shift can be observed from S3 and implies minor photothermal effects.Raman spectra were also recorded for S1−S4. In particular, the mode around 132.3 cm2/He atmosphere at 400 °C for 2 h indicated partial reduction of In(III) via a shift of the white line peak to lower binding energies  study was performed on stoichiometric Inmin Fig. . When exved Fig. . The H2-2O3 stems from the nucleation and growth of amorphous domains of nonstoichiometric In2Ox3− in crystalline stoichiometric In2O3. Hereafter, black indium oxide will be denoted In2Ox3−/In2O3. The strong, broad optical absorption of In2Ox3−/In2O3 across the entire wavelength range of the solar spectrum increases the likelihood that black indium oxide will function as an effective catalyst for the photothermal hydrogenation of CO2. To this end, the photocatalytic activity of black indium oxide on a borosilicate film support was evaluated in a batch reactor. Isotopically labeled 13CO2 was used to confirm hydrogenation products originated from carbon dioxide and not adventitious carbon contamination , where S4 is found to be 262 °C in contrast to S1−S3 which are found to have much lower local temperatures  was much more active towards CO production from CO2 than S1−S3 (ranging from 0.01 to 0.03 and 0.015 to 0.039 μmol h−1 m−2) both thermocatalytically and photocatalytically , a quality known as persistent conductivity26. The measurements display photocurrent saturation and decay process lifetimes on the order of minutes. The much faster photo-saturation of the excited electrons for S4 implies a stronger optical absorbance for S4 than S1. While the light was off, the photocurrents of S1 and S4 slowly decayed, with S4 requiring a much longer decay time than S1, which implies a higher population of oxygen vacancy traps for photoelectrons. Furthermore, the longer lifetime of the detected photoelectrons also implies a higher probability for the photoexcited electrons to participate in the reaction and thereby results in a better catalytic performance for S4. The same trend was observed under vacuum conditions, and the resulting I−V plot further confirmed the prolonged lifetime of photoexcited electrons for S4. Moreover, the observed photocurrent is consistent with the observed photocatalytic activity of black indium oxide for CO2 hydrogenation.To study the dynamics of photoexcited electrons, in situ photoconductivity measurements under vacuum and experimental conditions for S1 and S4 were performed and shown in Fig. 2Ox3−, arising from the removal of oxygen from In2O3, cause the color of the material to change from pale yellow to black. The oxygen vacancies [O] and coordinately unsaturated indium In′ sites and oxygen O′ sites in In2Ox3− will exist as mid-gap defect states in the bandgap of In2O3 28. These states will be respectively situated near the oxide-based valence band and indium-based conduction band, with the charge-balancing electrons occupying mid-gap states, as shown in Supplementary Fig. In addition, we know that oxygen vacancies [O] and the associated charge-balancing electrons in In2Ox3−/In2O3 heterostructure is well-equipped for photothermal CO2 hydrogenation reactions. Absorption of light across the solar spectral wavelength range causes local heating of In2Ox3−/In2O3 that enables thermochemical conversion of CO2 to CO. Formed via the absorption of light, photogenerated electrons and holes can separate across the interface between In2O3 and In2Ox3−, thereby promoting the photochemical conversion of CO2.With this information, we can begin to understand how and why the In2 atmosphere at room temperature revealed homolytic H2 dissociation over black indium oxide 29. The similarity of these peak positions to those described for In-OH bonds in previous reports, and the disappearance of such peaks on heating above 100 °C, further confirmed the presence of protonated In-O y that exhibited heterolysis of H2 31.The in situ DRIFTS measurements performed under Hide Fig. . The wea2 splitting mechanism on In2Ox3−, solid-state 1H MAS NMR spectroscopy was utilized to detect the H-related species in S4 before and after exposure to H2 at room temperature y, leading support to the H2 homolysis pathway   Fig. . Similar2 hydrogenation can be driven thermally in the ground electronic state, how can one rationalize the much greater efficiency of the reaction in the excited state?While CO2O3/In2Ox3−, shown in Fig. 2O3 CB can respectively relax to the mid-gap unsaturated In(III)′ and [O] vacancy states near the CB edge and unsaturated O′ near the VB edge in In2Ox3−27. These states can also be directly populated by band gap excitation and the relaxation of electrons and holes in In2Ox3−.The relative positions of the valence and conduction bands in the electronic band diagram of In2 hydrogenation, a model In2O3 (110) surface is used in these calculations  chloride (98%) was purchased from Sigma Aldrich and commercial InIn a typical synthesis of indium hydroxide, indium(III) chloride  was dissolved in a 3:1 solution (72 mL) of anhydrous ethanol  and deionized water. In a separate beaker, a 3:1 mixture of ethanol and ammonium hydroxide was prepared by combining aqueous ammonium hydroxide  and of anhydrous ethanol (54 mL). The solutions were rapidly combined, resulting in the immediate formation of a white precipitate. The resulting suspension was then immediately immersed in a preheated oil bath at 80 °C and stirred for 30 min. The suspension was then removed from the oil bath and allowed to cool to room temperature. The precipitate was separated via centrifugation and washed five times with deionized water. The precipitate was sonicated between washings to ensure adequate removal of any trapped impurities and then dried overnight at 60 °C in a vacuum oven.2O3 nanocrystal (S1) was obtained via thermal treatment of In(OH)3 nanocrystal in air at 700 °C for 5 h. The hydrogenated samples (S2−S4) were synthesized via treating S1 in tube furnace with 10%H2/Ar at a flow rate of 120 sccm. The temperatures for treatment were set as 200, 300 and 400 °C for 1 h with an increasing temperature rate of 5 °C per min. When the hydrogenation process was finished, the sample was naturally cooled down to room temperature.The pale yellow InSUPPLEMENTARY INFOPeer Review File


The aim of this study was to determine whether progesterone could inhibit the growth of lung adenocarcinoma cells via membrane progesterone receptor alpha (mPRα) and elucidate its potential mechanism. The relationship between mPRα expression and the survival prognosis of lung adenocarcinoma patients was studied.A mPRα knockdown lung adenocarcinoma cell line was constructed and treated with P4 and Org (a derivative of P4 and specific agonist of mPRα). Cell proliferation was assessed using CCK‐8 and plate colony formation assays. Protein expression was detected by western blotting. A nude mouse model of lung adenocarcinoma was established to assess the antitumor effect of P4/Org in vivo.We initially determined that mPRα could promote the development of lung adenocarcinoma through the following lines of evidence. High expression of mPRα both at the mRNA and protein level was significantly associated with the poor prognosis of lung adenocarcinoma patients. The downregulation of mPRα inhibited the proliferation of lung adenocarcinoma cells. We further showed that mPRα mediates the ability of P4 to inhibit the growth of lung adenocarcinoma cells through the following lines of evidence: P4/Org inhibited the proliferation of lung adenocarcinoma cells; mPRα mediated the ability of P4/Org to inhibit lung adenocarcinoma cell proliferation; mPRα mediated the ability of P4/Org to inhibit the PKA (cAMP‐dependent protein kinase)/CREB (cAMP responsive element binding protein) and PKA/β‐catenin signaling pathways; and P4/Org inhibited the growth of a lung adenocarcinoma tumor model in vivo.In summary, the results of our study show that progesterone can inhibit lung adenocarcinoma cell growth via mPRα. The mortality rate associated with lung cancer ranks first among all cancers.Progesterone (P4) is an indispensable female hormone that requires progesterone receptor (PR) to mediate its activity. Studies have reported that PR is expressed in lung cancer tissues, and PR can mediate the ability of P4 to promote the development of lung cancer.mPRα is expressed in different human cancer cells, such as breast cancer cells, ovarian cancer cells, astrocytoma cells and leukemia cells.The Human Pathology Atlas (HPA)A lung adenocarcinoma TMA was purchased from the National Engineering Center for BioChips . The TMA used in this study was HLug‐Ade150Sur‐01, which contains 75 lung adenocarcinoma tissues and relevant clinical overall survival follow‐up data of patients. We used immunohistochemistry (IHC) to detect the expression of mPRα in TMA and further analyzed the relationship between the level of mPRα expression and the survival prognosis of these patients with lung adenocarcinoma.A primary antibody against mPRα for IHC was purchased from Bioworld Technology  . The IHC experimental steps and staining scoring criteria performed in this study were previously described.2.The human lung adenocarcinoma cell line A549, human bronchial epithelial cell line HBE and human breast cancer cell line MCF‐7 were acquired from the American Type Culture Collection . The human lung adenocarcinoma cell line PC‐9 was kindly provided by Dr Yi‐Long Wu . The cells were cultured in RPMI‐1640 medium  supplemented with 10% fetal bovine serum  and 100 units/ml of penicillin and streptomycin. Cells were maintained in a humidified incubator at 37°C under an atmosphere containing 5% COTotal RNA was extracted using TRIzol reagent , after which cDNA was synthesized using a PrimeScript First Strand cDNA Synthesis kit  following the manufacturer's instructions. The sequences of the primers synthesized by Sangon Biotech Co., Ltd.  used for qRT‐PCR were as follows: 5′‐GTTCCAGCAGCACAACGAG‐3′ (forward) and 5′‐AGGTGAAAGAGGCAAGGACA‐3′ (reverse) for mPRα; and 5′‐AGGGGCCGGACTCGTCATACT‐3′ (forward) and 5′‐GGCGGCACCACCATGTACCCT‐3′ (reverse) for β‐actin. mPRα mRNA expression was normalized to that of β‐actin. qRT‐PCR was performed using an Applied Biosystems 7500 Real‐Time PCR Systems instrument  using the following thermocycling conditions: an incubation at 95°C for 3 minutes followed by 40 cycles of 95°C/15 seconds and 60°C/30 seconds. Each sample was assayed in triplicate.WB was performed as described in our previous study.The lentiviral vector used in this study to knock down the expression of PAQR7 (the gene that encodes mPRα) was constructed and packaged by GeneChem . We utilized six recombinant lentiviral vectors for PAQR7 knockdown screening, detailed information for which is described in the Supporting Information Fig .Before transduction, A549 and PC‐9 cells were grown exponentially to no more than 70% confluence. Then, the medium was replaced with new medium containing 8 μg/ml polybrene, after which lentiviral vectors were added to the appropriate wells at multiplicities of infection (MOI) of 50, 100 or 200. After incubating for 18 hours, the culture supernatant was discarded, and the uninfected cells were washed. Subsequently, the cells were cultured in fresh medium for 48 hours before being observed by fluoroscopy .In this study, we used two drugs: progesterone (P4) and Org . P4 was purchased from Selleck Chemicals , while Org was purchased from Axon Medchem . Before being administered to cells, the drugs were dissolved in a small amount of DMSO and then diluted with complete cell culture medium before being serially diluted to concentrations of 10, 20, 40, 80, and 160 μM according to the concentration required for the experiments.3 cells/well) were seeded in 96‐well plates (Corning Costar) for 24 hours before the medium was changed to normal medium. Then, the cells were cultured for 24, 48 or 72 hours before 10 μL of CCK‐8 solution was added to each well and the cells were incubated at 37°C for 1 hour. Subsequently, a microplate reader  was used to detect the absorbance at 450 nm.Cell proliferation was assessed by a CCK‐8  assay following the manufacturer's instructions. Cells  and cultured for two to three weeks in complete medium, which was refreshed every two days. Then, the cells were fixed with 4% paraformaldehyde for 30 minutes and stained with Giemsa for 15 minutes. Colonies were counted only if they contained at least 50 cells. The colony formation rate was calculated as “(colony number/seeded cell number) × 100%”.Cells were seeded onto glass coverslips and cultured for 24 hours. Fixation was routinely performed by incubating cells with 4% paraformaldehyde for 20 minutes. The cells were then incubated with the primary antibody against mPRα  overnight at 4°C, which was followed by an incubation with a fluorochrome‐conjugated goat anti‐rabbit secondary antibody for 1 hour at room temperature in dark. After using 1 μg/mL 4,6‐diamidino‐2‐phenylindole (DAPI) to stain cell nuclei, the slides were examined by fluorescence microscopy.6 A549 cells were subcutaneously injected into the right armpits of the nude mice. When size of the tumors was measurable, the mice were randomly divided into three groups . For the P4 and Org groups, the mice were intraperitoneally injected with P4 and Org at a dosage of 15 mg/kg/day for 28 days, while mice in the control group were intraperitoneally injected with an equal volume of saline. The length dimension (L) and width dimension (W) of the tumors was determined using a caliper every three days, and tumor volumes were calculated using the formula LW2/2. The diet, mental state, mobility, bowel movements and bodyweight of the mice was observed every two days. After four weeks, the mice were sacrificed by cervical dislocation, and their tumors, livers and kidneys were removed. The liver and kidney were subjected to hematoxylin and eosin (HE) staining to observe tissue and cell morphology.This study was approved by the ethics committee of Xiangya Hospital, Central South University. A xenograft tumor model was generated as described previouslyt‐test (two‐tailed). Survival analysis results between different groups were evaluated using the Log‐rank test and presented as Kaplan‐Meier curves. Differences were considered significant when P < 0.05.GraphPad Prism 6.01  was used for statistical analysis. The measurement results are presented as the means ± standard deviation. When the data were normally distributed, the difference between two groups was analyzed by Student's P < 0.05)   and the survival prognosis of patients with lung adenocarcinoma. The results of the analysis showed that patients with lung adenocarcinoma with high mPRα mRNA expression in cancer tissues had poor prognosis, suggesting that high mPRα mRNA expression is associated with poor prognosis (.05) Fig 1a. HowevWe used the IHC technique to assess the expression of mPRα in TMA, which included 75 patients with lung adenocarcinoma, and to analyze the relationship between the level of mPRα expression and the survival prognosis of these patients with lung adenocarcinoma. We observed that the expression of mPRα was significantly different between cancer tissues in different patients Fig .P < 0.01)  is shown in Fig .01) Fig .Previous studies have shown that mPRα is expressed in breast cancer MCF‐7 cells.− cells). The CCK‐8 and colony formation results showed that the viability and proliferation of PC‐9‐mPRα− cells was significantly lower than that observed in PC‐9 cells (P < 0.01)  to knockdown mPRα expression in lung adenocarcinoma cell lines . We obseThe above results showed that mPRα can promote the development of lung adenocarcinoma. In a previous study, our research team showed that mPRα can mediate the ability of P4 to inhibit the migration and invasion of lung adenocarcinoma A549 cells.We used different concentrations of P4  to treat lung adenocarcinoma A549 cells and PC‐9 cells for different time , and then tested cell viability by the CCK‐8 assay. The growth inhibition rate of A549 and PC‐9 cells at different concentrations of P4 was calculated. The results showed that as the P4 concentration and treatment time increased, the proliferation inhibition of A549 cells and PC‐9 cells increased gradually Fig . We furtP < 0.01)  Fig .− and PC‐9 cells with 20 μM P4/Org for 24, 48 and 72 hours, and then evaluated them by the CCK‐8 assay. The results showed that P4/Org significantly inhibited the activity of PC‐9 cells at 48 and 72 hours (P < 0.05) but did not inhibit the activity of PC‐9‐mPRα− cells  but had no significant effect on that of PC‐9‐mPRα− cells  by WB. The results showed that not only was Ki67 expression in PC‐9 cells significantly decreased after P4/Org treatment (P < 0.05 or 0.01), it was significantly lower in all PC‐9‐mPRα− cell groups than that observed in PC‐9 cells (P < 0.01). At the same time, P4/Org treatment was observed to have no effect on the expression of Ki67 in PC‐9‐mPRα− cells  through mPRα,− cells treated for 48 hours with 20 μM P4/Org. The results showed that the P4/Org treatment inhibited the phosphorylation of PKA, CREB and β‐catenin in PC‐9 cells (P < 0.05 or 0.01) but had no notable effect on the phosphorylation of NF‐κB  in the early stage of lung adenocarcinoma tumor model growth  focused on progesterone nuclear receptorsWe observed that when mPRα was knocked down in lung adenocarcinoma cells, cell growth was significantly inhibited, indicating that the presence of mPRα maintains or promotes the growth of lung adenocarcinoma cells. However, as a membrane receptor protein, how does mPRα function in the absence of exogenous ligands? Perhaps the answer involves the activation mechanism of EGFR, another membrane receptor that is currently the most studied. In addition to its ability to bind to ligands to activate downstream pathways, EGFR can also self‐activate by forming dimers without ligand activation.mPRα is also known as progestin and adipoQ receptor 7 (PAQR7). It has been reported that breast cancer cells can secrete adiponectin,As discussed in the above section, mPRα is a receptor molecule that promotes the growth of lung adenocarcinoma cells. We hypothesized that mPRα may a potential drug target for the treatment of lung adenocarcinoma. Our team previously showed that P4 can play a role in inhibiting the invasion and migration of lung adenocarcinoma cells via mPRα.Since lung adenocarcinoma cells have both progesterone membrane receptor and progesterone nuclear receptor, when P4 is used to treat lung adenocarcinoma cells, it can bind to both these receptors. To confirm that the inhibitory effect of P4 on lung adenocarcinoma cell growth is mediated by mPRα, in addition to mPRα knockdown experiments in lung adenocarcinoma cells, cells were also treated with Org. Org is a derivative of P4 in which a methylene group has been added to the molecular structure of P4. A previous study showed that Org does not bind to PR, and because its affinity with mPRα is significantly better than that of P4, it is believed that Org is a specific agonist of mPRα.mPRα is a G‐protein coupled receptor (GPCR) in which the intracellular carboxy terminus is coupled to a G protein.The role of PKA is to phosphorylate downstream protein molecules that are involved in important signaling pathways, such as the PKA/CREB, PKA/β‐catenin and PKA/NF‐κB pathways.PKA contains two regulatory and two catalytic subunits. In general, cAMP regulates PKA by first binding to the regulatory subunit of PKA to alter its conformation, causing the regulatory and catalytic subunits to dissociate, after which the catalytic subunits are released to perform their catalytic function.CREB is an important molecule that promotes the development of cancer, and inhibiting the activity of CREB in cancer cells is one of the goals of cancer treatment research.The results of this study also showed that P4/Org treatment can also inhibit the PKA/CREB pathway in mPRα knockdown lung adenocarcinoma cells, suggesting that other receptors were involved in addition to the mPRα‐mediated effects in this process. These receptors that also exert P4/Org‐mediated effects may be additional progesterone membrane receptor subtypes. P4 binds to membrane receptors such as mPRδ and mPRε, which also function as GPCRs, and studies have shown that Org also has better binding affinity for mPRδ and mPRε.Our nude mouse tumor‐bearing model results showed that the P4/Org treatment had a tendency to inhibit the growth of the lung adenocarcinoma model in vivo. However, only Org showed significant inhibition in the early stages of tumor model growth. When the growth time of the tumor model was prolonged, the inhibitory effect of P4/Org in the tumor model showed large individual differences, indicating that the tumor suppressing efficacy of P4/Org alone in the complex physiological/pathological conditions of the tumor model was limited. These results suggest that if P4/Org is further applied to the treatment of lung adenocarcinoma in the future, this treatment will need be given at an early stage, potentially together with other types of anticancer drugs.In conclusion, our current study revealed the following. First, the high expression of mPRα is a potential poor prognosis marker in patients with lung adenocarcinoma. Second, mPRα can promote the development of lung adenocarcinoma and is a potential target for treatment, and finally that mPRα mediates the inhibitory effect of P4 on the PKA/CREB and PKA/β‐catenin signaling pathway to suppress the growth of lung adenocarcinoma cells.No authors report any conflict of interest.Figure S1 Lentiviral vector GV248: hU6‐MCS‐Ubiquitin‐EGFP‐IRES‐puromycinFigure S2 The infection effects of lentivirus with MOI = 50/100/200 on lung adenocarcinoma A549 and PC‐9 cells.Figure S3 Lentiviruses were infected with A549 and PC‐9 cells with MOI = 100.Figure S4 The effect of lentivirus vector infection on the mRNA expression of mPRα in lung adenocarcinoma A549 and PC‐9 cells.Figure S5 The effect of lentivirus vector infection on the expression of mPRα protein in lung adenocarcinoma A549 and PC‐9 cells.Figure S6 The results of HE staining of liver and kidney in nude mice after 4 weeks of P4/Org intervention.Table S1 shRNA sequences.Click here for additional data file.


Here, Li doped Mg2Ge with a thermoelectric figure of merit zT of 0.5 at 700 K is reported, which is four times higher than that of p‐type Mg2Si and double than that of p‐type Mg2Sn. The reason for the excellent properties is an unusual temperature dependence of Seebeck coefficient and electrical conductivity compared to a standard highly doped semiconductor. The properties cannot be captured assuming a rigid band structure but well reproduced assuming two parabolic valence bands with a strong temperature dependent interband separation. According to the analysis, the difference in energy between the two bands decrease with temperature, leading to a band convergence at around 650 K and finally to an inversion of the band positions. The finding of a combination of a light and a heavy band that are non‐rigid with temperature can pave the way for further optimization of p‐type Mg2.Magnesium silicide and its solid solutions are among the most attractive materials for thermoelectric generators in the temperature range of 500–800 K. However, while n‐type Mg 2Ge. With temperature the interband separation (Delta E) decreases leading to a convergence of the valence bands (heavy hole+light hole (HH+LH) and split‐off (SO)) and extraordinary thermoelectric properties at high temperatures. The dashed lines indicate the chemical potentials of the individual samples.Sketch of the strongly temperature dependent band structure in Li‐doped Mg The device efficiency depends monotonously on the dimensionless figure of merit zT = S2σκT, where S is the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity, and T is the temperature. A high S, σ, and low κ of the employed thermoelectric materials are required to achieve good thermoelectric properties.Thermoelectric (TE) power generators are highly promising energy alternatives as they offer heat–electricity conversion and vice versa for a wide range of applications such as space applications, automotive, and refrigerators.1 Ther2X . However, the thermoelectric properties are still inferior in comparison with n‐type Mg2. For further development of thermoelectric generators based on Mg2X, both good p‐and n‐type materials are highly desired.In recent years, there has been progress in optimizing thermoelectric properties of p‐type Mg and Sn).2 Howe Based on the expression zT scales with S2, in order to achieve high zT, improving the Seebeck coefficient is more efficient than enhancing electrical conductivity. For degenerate semiconductors, it is well recognized that a large density of states effective mass (mD∗) is beneficial for high S for a given carrier concentration. Large mD∗ can be achieved either by high valley degeneracy (NV) and large single‐band effective mass (mb) since mD∗=Nv2/3mb. However, heavy mb will give a low carrier mobility (μ≈1mb2.5) and consequently reduces the electrical conductivity (σ = neμ). For an improvement of the thermoelectric performance beyond the basic carrier concentration optimization, advanced concepts need to be applied. These include band structure engineering  as well as scattering engineering (energy filtering effect and modulation doping). In particular, band convergence where different bands converge through alloying or changing temperature leads to an increase of the density of states effective mass without degrading the mobility and consequently increases S2σ. Band convergence has been “applied” in Mg2 and PbTe0.85Se0.15. As example, by alloying PbTe with specific elements  the convergence of electronic bands can be manipulated to take place in the desired temperature range.As basic strategy, optimizing carrier concentration through doping can be employed to enhance thermoelectric properties.2b,c B2Ge via high energy ball milling using Li as a dopant. The results show that the observed Seebeck coefficient first increases with increasing temperature and decreases slowly at higher temperatures. This is atypical for highly doped semiconductors, which usually show a decrease with temperature after a pronounced maximum. We have also observed a pronounced increase in electrical conductivity at temperatures below the onset of bipolar conduction. The temperature dependent Seebeck coefficient and electrical conductivity has been analyzed using two parabolic valence bands (2PVB) model. The model assumes the heavy hole (HH) and light hole (LH) band as one effective heavy band of Mg2Ge and the split‐off (SO) band as second band. We assume that there is a temperature dependent interband separation (ΔE) between the HH + LH band and the SO band. The results reveal that our experimental data and the model are in good agreement only when considering a temperature dependent interband separation. The almost constant Seebeck coefficient and an increase in σ at high temperature lead to a superior power factor and enhance zTmax ≈ 0.5 at 700 K.In this work, we have synthesized p‐type Mg22.1Figure 2Ge samples. The main peaks can be indexed to an anti‐flourite cubic crystal structure with a space group Fm-3m (ICSD collection code #81735). Elemental Ge impurity peaks are observed for y = 0.02 and y = 0.05 and the intensity increases with increasing Li content. The observed elemental Ge could be due to unintended Mg loss, for example, from evaporation during the sintering process, or Mg lost to the jar walls during the ball milling, or differences in the mechanical properties of Mg and Ge (ductile Mg and hard‐brittle Ge). However, why this would differ between the samples remains unclear. The lattice constant (a) is calculated by structural refinement (a = 6.392 Å) and it is in agreement with previous literature, 6.378–6.393 Å.1.98Li0.02Ge sample were observed using SEM. The grain size was estimated using ImageJ to be 4–5 µm, which is typical for samples of Mg2X synthesized using high energy ball milling. The white particles were observed in all examined samples (see Supporting Information). EDX point analysis indicates them to be elemental Ge in agreement with the XRD analysis.Microstructure and phase purity of Mg milling.17 The2.22Ge is listed in Table pH), the density of states effective mass (mD∗), and the Hall mobility (μH) are calculated from the measured transport data using a single parabolic band (SPB) model.The thermoelectric transport data of p‐type Mg2Ge are shown in Figure T followed by an almost constant value at higher temperatures. The starting temperature for this “plateau” shifts to higher temperature with higher Li concentration except for y = 0.015. S decreases with increasing Li concentration due to its inverse relation with carrier concentration. We also find a decrease in electrical conductivity for all samples till a minimum at 450 K followed by a relatively sharp increase at higher T. We have observed this unusual behavior, which is atypical for a highly doped semiconductor for all samples with the minimum shifting to higher T with increasing dopant or carrier concentration. The electrical conductivity increases with higher Li concentration due to an increase in the carrier concentration and the Hall mobility except for y = 0.015. The thermal conductivity and the lattice thermal conductivity show the same trend for all samples. The thermal conductivity of p‐type Mg2Ge has similar values as n‐type Mg2Si for a similar carrier concentration. The lattice thermal conductivity (including the bipolar contribution) is calculated using the Lorenz number (L) calculated for each band individually assuming a two parabolic valence band model, see Equation . The high PF leads to the highest figure of merit zT for y = 0.02 and y = 0.05 zTmax = 0.50 ± 0.07 at 700 K.The thermoelectric properties of p‐type Mgntration.26 TheEquation  in SectimD∗ and μH at room temperature under the assumption of a rigid band structure and that the mD∗ is independent of carrier concentration. The reduced chemical potential (η) given by η=EFkBT is calculated using the relation with the Seebeck coefficient S=kbe(2F1(η)F0(η)−η), with the Fermi integral of order (i)Fi=∫0∞∈id∈1+Exp[∈−η], EF as Fermi energy and kB as Boltzmann's constant. The true carrier concentration (p) is calculated from the Hall pre‐factor (rH) and the “measured” pH, pH=1RHe=prH,rH=1.5F0.5(η)(0.5)F−0.5(η)F02(η). mD∗ is calculated using the relation p=4π(2mD∗kBTh2)1.5F0.5(η). μH at room temperature is calculated using a relation μH=σpHe. For the calculations, we have assumed a scattering parameter λ = 0 corresponding to the energy dependence of acoustic phonon scattering. As results from the SPB calculation, the carrier concentration and the density of states effective mass increase with higher Li concentration. The highest Hall mobility is obtained for y = 0.015, while the other three Li doped samples exhibit an increase with higher Li content.The SPB model is used to calculate 2.3T‐dependence of S(T), σ(T), and increasing mobility with increasing carrier concentration) were observed for Li doped Mg2Ge. While quantitatively different  while the upturn in electrical conductivity is observed at 450 K  the temEquation  where κEG can be roughly estimated from the relationship in Equation ( Plotting ln(κbi) versus (2kBT)−1 for Mg1.99Li0.01Ge shows a good linear fit and yields EG = 0.74 eV which fits with previous reports. Comparison of the experimental result for κbi with the predicted one allows to estimate the temperature dependence of the band gap, yielding EG = 0.74 − 5.85 × 10−4T see Figure S6, Supporting Information. While the numbers here are a rough estimate . This relatively large band gap supports the conclusion that the influence of the minority carriers is not the reason for the observed trends in the transport data.In addition, the band gap Equation .[27, T dependences of the TE properties (S and σ) are not comparable to those of degenerate semiconductors, it is unlikely that the thermoelectric properties of Li doped Mg2Ge can be modeled using a SPB model like in the case of p‐type Mg2. They furthermore do not resemble to those of (highly) doped semiconductors with some influence of the minority carriers at high T , and cannot be explained by a one conduction band (CB) and one valence band (VB) model as we show in the Supporting Information. By modeling the temperature dependent transport data using a 1CB + 1VB model in two cases  we can show that the experimental data cannot be reproduced by a 1CB + 1VB model, see Figures S4 and S5, Supporting Information. The observed experimental data at high temperature is therefore not due to a minority carrier effect. We have also observed that the density of states effective mass is dependent on carrier concentration for Li doped samples; this is an indication for non‐parabolicity or a non‐rigid multiband structure.As the observed .23 The2Ge using a 2PVB model based on previous calculations of the band structure of Mg2Ge. As discussed in Supporting Information the consideration of a conduction band was not deemed necessary, as the band gap of Mg2Ge is relatively large and the influence of the minority carrier is minor and visible only at high temperatures . The valence band maxima is lying at the Γ point in the Brillouin zone (BZ) with three bands having different effective masses, which are labeled as heavy hole (HH), light hole (LH), and split‐off (SO) bands, respectively. The HH and LH bands maxima are degenerate while the SO band is at a different energy due to spin‐orbit coupling. The relevant equations areIn the following, we will try to reproduce the thermoelectric properties of Li doped Mgof Mg2Ge.30 As 2Ge. We furthermore assume acoustic phonon scattering  is calculated using Equation (Cl is an elastic constant of Mg2Ge (1.17 × 1011 Pa) and EDef is the deformation potential which characterizes the interaction between holes and phonons (EDef = 9 eV). We kept the deformation potential constant based on our previous calculation on p‐type Mg2 and because no further information is available. The total electrical conductivity is calculated from each band using Equations ..2Ge. We Equation ), the tomD∗, mass ratio (mLHmHH) and p). We have systematically tried to tune the ratio of effective mass mLHmHH and adjust p roughly so the model fits with the σ or S experimental data at least at room temperature . The modeled data does not fit with the experimental results as in this case the electrical conductivity decreases with increasing T independent of mass ratio. This is also observed for the Seebeck coefficient data where S naturally increases with increasing temperature which is inconsistent with our experimental data.As a first attempt, we have assumed the HH and the LH bands are degenerate and did not include the SO band. There are three unknown parameters as inputs for the first model  band and the SO band are separated by an interband separation (ΔE) which was calculated to ΔE≅0.2 eV at 0 K. The valence band structure of Ge and Mg2Ge are similar and for Ge, a temperature dependent ΔE was observed. Splitting between HH and LH has been observed for thin films of SiGe under strain which is not comparable to our case. Also, we found that the mass ratio for Mg2Ge mHHmLH≈6 is similar with Ge which does not fit with our model, making the assumption of splitting of HH and LH implausible. Thus, we have assumed a band structure that is non‐rigid band with temperature with the HH and LH band as one effective band and the SO band as the lighter, second. We kept the effective mass of the SO band to be constant mHH+LHmSO≈3.8;mSO=0.5m0,mD∗=2.1m0 which is similar with the case for Ge mHHmSO≈3.6. We believe that the increase in electrical conductivity can be explained by a light band that moves up in energy with temperature like in the case of GaAs with the HH + LH band as the reference band. A strong temperature dependence of the interband separation ΔE is rare but has been observed in a few high performing thermoelectric materials. We have therefore chosen ΔE = (A + B/K*T) with A being negative and the linear form due to simplicity. The choice of ΔE = 0.26 at 0 K is similar to the value from DFT calculation of the band structure at 0 K. The chemical potential is displayed for all samples  and the upturn in electrical conductivity can be explained by the movement of the SO band: as temperature increases this leads to a decrease of ΔE and a convergence of the bands at 650 K. The Seebeck coefficient at room temperature is mainly governed by the HH + LH band. At room temperature, the HH + LH band contributes more to σ than the SO band thus S of 2PVB will be closer to S of the HH + LH band while at high temperature, the Seebeck coefficients of both bands converge. Figure S and σ to be quite sensitive to ΔE . The difference between the modeled and the experimental Seebeck coefficient at 300–500 K is getting smaller for lower value of ΔE in the Table y = 0.01 improves if we adjust the effective masses, however we do not have enough data to substantiate a carrier concentration dependent mSO . Since the SO band contributes mainly to the electrical conductivity, the effective mass of the SO band affects the temperature dependence of electrical conductivity. The lighter the mass of the SO band, the earlier (in temperature) and the sharper is the increase of electrical conductivity .We found the temperature dependent RH is different between 300 and 450 K. At higher temperatures, both the prediction and the experimental result show visible, but relatively weak temperature dependence. This is in agreement with the predicted behavior for a system with a convergence of the valence bands. Quantitatively the values agree within a factor of 10 over the whole temperature range. Possible reasons for the observed deviation are discussed in Supporting Information. For comparison, the results for a system with 1 CB and 1 VB are also shown . For this system, a change of sign of RH is predicted (due to the higher mobility of the electrons) as well as much stronger temperature dependence. This is in clear disagreement with the experimental data.Comparing the experimental result of the temperature dependent Hall coefficient with the prediction for the 2PVB system we do not find total agreement. The agreement is good at low temperatures, but the temperature dependence of In summary, the observed unusual thermoelectric properties can be explained by a two valence band model with different but constant effective masses and a temperature dependent interband separation.32Ge such as a nearly constant S at high T and a pronounced upturn in electrical conductivity cannot be explained by previously reported mechanisms such as energy filtering, resonant levels, and modulation doping. Energy filtering and modulation doping are ruled out because Ge precipitates are not evenly distributed at the grain boundaries as observed from the SEM images  assumption that a SPB model is applicable.We have also observed that the carrier concentrations obtained from the Hall measurements are different from those of the 2PVB model especially for high Li concentrations  and light band (SO) whose energetical differences decrease with temperature.42Ge using high energy ball milling. The thermolectric properties of Li doped samples exhibit an unusual temperature dependence of S and σ compared to “standard” highly doped semiconductors. The observed almost constant Seebeck coefficient and pronounced upturn in electrical conductivity at high temperature can be modeled using 2PVB with a temperature dependent interband separation. Here we have taken the heavy hole band and the light hole band as one effective band and the split‐off band as second band; acoustic phonon scattering is taken as the dominant scattering mechanism. The almost constant S at high temperature and the upturn in electrical conductivity can be explained by the movement of the SO band with respect to the HH + LH band as temperature increases. While the 2PVB model shows good agreement with the experimental data, we could also rule out by comparative modeling that the observed behavior at high temperature is due to the influence of the minority carriers. The beneficial temperature dependence of Seebeck coefficient and electrical conductivity lead to high zT of 0.5 at 700 K for y = 0.02 and 0.05 which is superior to p‐Mg2Si and Mg2Sn and even comparable to the best p‐type solid solutions of Mg2Si and Mg2Sn. In summary, we show that a non‐rigid band structure with a decreasing interband separation leads to superior thermoelectric properties. This opens a path beyond the standard optimization for further improvement of p‐type Mg2 solid solutions as well as other materials.We have successfully synthesized Li‐doped Mg52Ge was synthesized via high energy ball milling (SPEX 8000D) using the identical method which was used to prepare p‐type Mg2Si1−xSnx. The precursors (Mg turnings (Merck), Ge , and Li granules with purity >99.5%) were weighed according to nominal composition Mg2‐yLiyGe. The Li concentration were varied as y = 0.01, 0.015, 0.02, and 0.05. The desired elements were transferred into a stainless steel jar with a ball to powder ratio of 1.6:1. All of the experimental steps were conducted inside a glove box under Ar atmosphere to prevent sample oxidation and contamination. The elements were milled with constant speed for 3 h with a halt each hour in between to remove agglomerated powder from the jar walls. We have observed that massive input of mechanical energy (hammering) can lead to powder ignition inside the glove box, so powder removal needs to be done carefully. The obtained fine powders were transferred into a graphite die with a diameter of 13.3 mm and sintered at 923 K for 600 s using a DSP 510 SE from Dr. Fritsch GmbH. The sintering was done under vacuum conditions (≈ 10−5 bar) with a sintering pressure of 66 MPa and a heating rate of 1 K s−1. The density of the obtained pellets was calculated using Archimedes method.Li doped Mgα radiations (1.5406 Å) in the range (2θ: 20°–80°) and with a step size of 0.01°. The microstructure and phase purity of one of the samples was observed by a EDS detector Zeiss Ultra 55. The temperature dependent electrical conductivity and Seebeck coefficient data was obtained by an in‐house developed four‐probe technique. The thermal diffusivity (α) was measured by a laser flash technique with a NETZSCH LFA 427 apparatus or with a XFA467HT HyperFlash apparatus. The thermal conductivity (κ) was calculated using the relation κ = ρp αC, where ρ and pC correspond to density of the samples and heat capacity, respectively. The pC value was obtained from the Dulong–Petit limit CVDP:Cp=CVDP+9Et2TβTρ where tE ≈ 1.6 × 10−5K and βT ≈ 1.7 × 10−11Pa, are the coefficient of thermal expansion and an isothermal compressibility, respectively. In the relevant temperatures pC increases from 0.632 to 0.649 J g−1 K−1. The Hall coefficient (RH) was obtained from Hall measurements using the van der Pauw configuration under a varying magnetic field with maximum value of 0.5 T. The hall carrier concentration was calculated using the relation pH=1RHe, where e is the electronic charge. The uncertainties of the measurements are ± 5%, ±5%, ±8%, and ± 10% for S, σ, κ, and RH, respectively. The uncertainties are given based on comparison with the NIST standard reference material 3451 and an international round‐robin test.The obtained pellets were characterized using XRD Siemens D5000 Bragg–Brentano diffractometer with a secondary monochromator, Cu‐Kechnique.18 TheThe authors declare no conflict of interest.Supporting InformationClick here for additional data file.


A major challenge was the definition of the scaling factor for the in vitro to in vivo conversion of the PBK-model parameter Vmax. In vitro values for the Vmax and Km for transport of E217βG were found in the literature in four different studies based on experiments with primary rat hepatocytes. The required scaling factor was defined based on fitting the PBK model-based predicted values to reported experimental data on E217βG blood levels and cumulative biliary E217βG excretion. This resulted in a scaling factor of 129 mg protein/g liver. With this scaling factor the PBK model predicted the in vivo data for blood and cumulative biliary E217βG levels with on average of less than 1.8-fold deviation. The study provides a proof of principle on how biliary excretion can be included in a generic PBK model using primary hepatocytes to define the kinetic parameters that describe the biliary excretion.The aim of the present study was to develop a generic rat physiologically based kinetic (PBK) model that includes a novel testing strategy where active biliary excretion is incorporated using estradiol-17β glucuronide (EThe online version of this article (10.1007/s00204-020-02908-x) contains supplementary material, which is available to authorized users. The kinetic profile of a substance is of importance when considering human safety assessment and drug development. Prediction of these kinetic profiles based on absorption, distribution, metabolism and excretion (ADME) using physiologically based kinetic (PBK) modelling has been shown of value not only to predict blood levels of drugs following defined dose levels in forward dosimetry, but also in so-called reverse dosimetry for quantitative in vitro—in vivo extrapolation (QIVIVE)   via the (rat) organic anion transporting polypeptides (Oatps) into the hepatocytes, to be subsequently excreted into the bile . Table A conceptual PBK model was developed for En et al. . Tissue:n et al.  based on217βG from liver to bile was described by Michaelis–Menten kinetics using the following formula:217βG in the liver over time (µmol/h), QL the blood flow to the liver (L/h), CB the concentration of E217βG in arterial blood (µmol/L), CVL the venous concentration of E217βG in the liver (µmol/L), VmaxE217bG and KmE217bG the maximum rate (µmol/h) and Michaelis–Menten constant (µmol/L) for the transport of E217βG. The model equations were encoded and solved using Berkeley Madonna 8.3.18 .The transport of E217βG undergoes enterohepatic circulation, this was not taken into account in the model because for all the in vivo data included in this study the bile duct of the rats was cannulated, therefore, enterohepatic circulation could not take place.Although it is known that E217βG into hepatocytes were obtained from the literature. Four studies, (Brock and Vore Vmax (pmol/min/mg protein) and Km (µM) values for the transport of E217βG into hepatocytes. Briefly, all studies used freshly isolated primary hepatocytes from Sprague–Dawley rats and radio-labelled E217βG. Three studies used a hepatocyte suspension system where concentration dependent uptake of [3H]-E217βG under linear conditions with respect to time was determined. At the end of each incubation, a fraction of hepatocyte suspension was removed from the incubations. This fraction was added to a tube containing silicon oil and 3 M KOH. The tube was centrifuged and cut at the silicone oil layer. The hepatocyte pellet was placed in a scintillation vial and radioactivity was measured. The other study cultured the freshly isolated hepatocytes on collagen-coated dishes. After washing the dishes three times with either a Krebs–Henseleit buffer or choline buffer, the uptake was initiated by adding [3H]-E217βG. The uptake was stopped and cells were washed three times using ice-cold Krebs–Henseleit buffer for both procedures. The cells were solubilised in 1 N NaOH, distilled water was added and [3H]-E217βG was measured with liquid scintillation. Protein content in all studies was determined using either the method of Lowry  of [3H]-E217βG by the hepatocytes against the [3H]-E217βG concentration (µM) fitting the curve using the Michaelis–Menten equation.The in vitro kinetic data for transport of E217βG to the data reported for these endpoints in rat experiments found in literature. Table 217βG upon an intravenous dose level of 81 ng/kg bw , Cplasma the concentration of E217βG in plasma (µmol/L) and Hct the rat haematocrit, which was set at 40%, the average of the range published .Combining the four in vitro kinetic data sets for the Vmax values expressed in pmol/min/mg protein have to be converted to an in vivo Vmax value expressed in µmol/h/whole liver. This was done using the following formula:To define the scaling factor as described above in vitro mentclass2pt{minimThe full model code is presented in Supplementary material B.217βG in blood and its predicted cumulative biliary excretion. To carry out the sensitivity analysis, a dose level of one of the available rat studies was used, 81 ng/kg bw. The analysis was performed using the values for Km and Vmax obtained from the rat hepatocyte study with the lowest catalytic efficiency (CE)   vary less than 3.1-fold.Data from the four studies reporting values for the kinetic parameters Vmax and Km values presented in Table 217βG levels in blood were calculated optimising the scaling factor to obtain the best fit between predicted and actually reported experimental data for the three available in vivo data sets .The data obtained reveal that also for prediction of the cumulative biliary excretion all kinetic hepatocyte data can provide adequate fits with scaling factors that differ only to a limited extent for the four kinetic hepatocyte data sets. The scaling factors for the fits of the 3 different in vivo data sets for blood E217βG blood concentration and cumulative biliary excretion were predicted using this average value and compared to the experimental data in Figs. 217βG levels were on average predicted with a less than 1.8-fold deviation, while for the data for the cumulative biliary excretion of E217βG the averaged deviation was less than 1.4-fold. The largest deviations were observed for the in vivo data on blood E217βG levels of Slikker et al.  in the Slikker et al.  in the studies reported by Gotoh et al. /g liver . Together with the weight of the liver  that hepatocytes provide an adequate in vitro model to obtain kinetic parameters Vmax and Km for active uptake of an Oatp substrate, E217βG in our study. Given the uncertainty in scaling factors that would be required when using transfected cell models, use of hepatocytes to describe biliary excretion may be preferred over the use of in vitro systems with an overexpression of individual transporters. This is also because E217βG has affinity for more than one Oatp which will all be taken into account when using hepatocytes known to contain multiple Oatps  thus better mimicking the overall transport in the organ of interest  that the value 129 mg protein/g liver is suitable to translate the in vitro With this study we demonstrated a proof of principle by introducing a novel testing strategy for including biliary excretion into a generic PBK model at the same time defining the scaling factor for the vitro system (primary rat hepatocytes) used to obtain adequate in vitro to in vivo translation. We confirmed based on the predictions using the averaged scaling factor that primary rat hepatocytes can be the gold standard for studies on biliary transport in addition to their use as the golden standard for many in vitro (human) hepatic endpoints  (Guguen-Guillouzo and Guillouzo Supplementary file1 (DOCX 302 kb)Supplementary file2 (DOCX 17 kb)Below is the link to the electronic supplementary material.


Accumulation of amyloid beta (Aβ), α‐synuclein (αSyn), and tau in dementias indicates their age‐related failure of elimination from the brain. Aβ is eliminated along basement membranes in walls of cerebral arterioles and leptomeningeal arteries ; IPAD is impaired with age. We test the hypothesis that αSyn and tau are also eliminated from the normal brain along IPAD pathways.Soluble αSyn or tau was injected into mouse hippocampus. Animals were perfused 5 minutes to 7 days post‐injection. Blood vessels were identified by ROX‐SE for light‐sheet and immunolabeling for confocal microscopy. IPAD was quantified by measuring the proportion of arterioles with αSyn/tau.αSyn and tau are eliminated from the brain by IPAD but with different dynamics.Age‐related failure of IPAD may play a role in the pathogenesis of synucleinopathies and tauopathies. αSyn persists within IPAD at 24 hours, which may affect immunotherapy for αSyn. If preventative measures and therapeutic strategies are to be further developed for the treatment of dementias, a firm understanding is required of how soluble proteins are eliminated from the brain, why such elimination fails with age, and how elimination can be facilitated.So far, most attention on pathways for elimination and why they fail has centered on Alzheimer's disease (AD). Plaques of insoluble Aβ are one of the hallmarks of AD but levels of soluble Aβ in the interstitial fluid (ISF) of the brain are also raised which suggests a failure of elimination of soluble Aβ and loss of homoeostasis of the extracellular environment in the brain.As well as Aβ, insoluble and soluble αSyn accumulates in the brain in Parkinson disease and Lewy body dementias.In the normal brain, tau is highly enriched in neurons in which it modulates microtubule dynamics and plays a role in mediating axonal transport and synaptic structure and functions together with neuronal signaling pathways.Mechanisms for intracellular degradation of αSyn and tau have been investigated extensively investigated.To ensure maximum effectiveness of immunotherapy for αSyn and tau, it is crucial to understand the pathways by which these proteins in their soluble forms are eliminated from the brain. The major objective of this study is to determine whether soluble αSyn and tau drain from the brain along IPAD pathways and how the dynamics of this drainage compare with the elimination of soluble Aβ. Such knowledge would indicate whether therapies to improve the efficiency of IPAD in elderly individuals should be included in protocols for immunotherapy.Systematic review: The accumulation of α‐synuclein (αSyn), tau, and amyloid beta (Aβ) in the brain is a hallmark of dementias, indicating the failure of elimination of these proteins with advancing age. Soluble Aβ drains from the brain along basement membranes in the walls of arteries; such drainage is impaired with age and after immunization against Aβ. The dynamics for the drainage of αSyn and tau from the brain are unclear and are the focus of this article.Interpretation: Results show that both αSyn and tau are eliminated from the brain along artery walls with dynamics that are similar, but not identical, to those of Aβ. Age‐related impairment of peri‐arterial drainage for αyn and tau is likely to be an important factor in the accumulation of these proteins in aging and demented brains.Future directions: Therapeutic strategies to enhance peri‐arterial drainage from the aging brain will improve the elimination of αSyn, tau, and Aβ in the prevention of dementias, and these strategies should be considered also in the context of immunotherapy.In this study we test the hypothesis that αSyn and tau are eliminated from the brain along IPAD pathways but possibly with dynamics that vary from those of Aβ. αSyn and tau were injected separately into the mouse hippocampus, and the distribution of these two proteins over space and time in the brain parenchyma and in the walls of blood vessels was recorded by light‐sheet and confocal microscopy at 5 minutes, 30 minutes, 24 hours, or 7 days post‐injection. The results allow the dynamics of IPAD for αSyn and tau to be assessed and to be compared with the IPAD dynamics for Aβ.22.1ad libitum. All procedures were carried out in accordance with animal care guidelines stipulated by the United Kingdom Animals (Scientific Procedures) Act 1986, Home Office license.Male C57BL/6 10 to 11‐week‐old mice were housed in groups of 5‐10, kept under a standard 12‐hour light/dark cycle, and fed a standard RM1 chow diet  and water 2.22.2.12 (1.7 L/min) and used throughout the procedureTo maintain a sufficient heart rate and oxygen saturation, 2% Isoflurane was mixed with concentrated O2.2.2Recombinant human 2N4R‐tau  was prepared in sterile filtered phosphate‐buffered saline (PBS) (pH 8.7) using a 7K MWCO Zeba spin desalting column  following the manufacturer's instructions. The resulting tau was concentrated to 0.2 mg/mL using VivaSpin concentrator . The tau was added to Alexa‐Fluor‐488‐TFP‐ester  and mixed for 1 hour on a Cleaver vortex and incubated at 4°C overnight. Unconjugated dye was removed using Zeba columns. Tau‐Alexa488 conjugates contained two moles of dye per mole protein.2.2.3Surgery was performed using a stereotaxic frame  with a digital manipulator (World Precision Instruments). A burr hole was created in the skull using a Tech2000 Micromotor drill  with 0.7 mm burr. One‐half microliter of either 60 µM recombinant human αSyn(1‐140)‐HiLyteFluor‐488 (AnaSpec) or Tau‐Alexa488 was injected into the right hippocampus  using a 33 gauge Hamilton needle (Essex Scientific Laboratory Supplies Ltd.) and Microinjection syringe pump  at a rate of 0.25 µL/minute (supplementary figure 1a) The syringe was left in situ for 2 minutes to prevent reflux. Mice were killed by intracardiac perfusion of fixative after a further 5 minutes, 30 minutes, 24 hours, or 1 week (n = 5 per group). Buprenorphine was administered for analgesia.2.2.4For confocal analysis, at the end of each time point mice were terminally anesthetized with pentobarbitone (200 mg/kg) and intracardially perfused with PBS (0.01 M) followed by 4% paraformaldehyde (PFA)  at a rate of 5 mL/minute. For light‐sheet analysis, mice were perfused at 5 minutes or 24 hours with PBS followed by 20 mL of 40 µM 5‐Carboxy‐X‐Rhodamine Succinimidyl Ester (ROXSE)  at 3 mL/min, and then 4% PFA at 5 mL/min. Brains were immersed in 4% PFA for 3 hours at 4°C and then cryoprotected in 30% sucrose.2.3Brains were dehydrated in 50% to 100% methanol concentrations (12 hours each at RT). Brains were delipidated in 30% dichloromethane (DCM) 60% methanol for 1 hour, followed by 100% DCM for 4 hours, and then cleared in Dibenzyl ether (DBE) for over 12 hours. Brains were imaged using light‐sheet microscope .2.4Twenty micrometer coronal slices were prepared on a Leica Cryostat. Immunolabeling of α‐smooth‐muscle‐actin‐Cy3 (SMA)  and collagen IV  was performed on sections 200 µm anterior to the injection site . Immunolabeling of perivascular macrophages using CD206 , which is uniquely expressed on perivascular macrophages2.5The area selected for analysis encompassed the dentate gyrus extending to the CA1 region of the hippocampus proper. Blood vessels within the hippocampal sulcus were not quantified. The number of arterioles/venules/capillaries with αSyn or tau in their BMs was counted within this area and normalized to the total number of arterioles/venules/capillaries. Blood vessels were classified as capillaries (diameter <10 µm), arterioles (SMA‐positive blood vessels with diameter larger than 10 µm), or veins (SMA‐negative blood vessels with diameter larger than 10 µm).33.1To establish the change in overall distribution of αSyn or tau tracers after their injection into the hippocampus, whole brains were imaged using light‐sheet microscopy at 5 minutes or 24 hours post‐injection (PI).Figure At 5 minutes PI, αSyn and tau diffused within the hippocampus Figures  and 3A, 3.2To investigate whether extracellular αSyn and tau enter IPAD pathways, the distribution of αSyn and tau was analyzed by confocal microscopy at 5 minutes, 30 minutes, 24 hours, and 7 days PI.αSyn and tau were located in BMs of arterioles at 5 minutes PI, observed as regions of co‐localization between the green tracer and blue collagen IV producing a cyan color Figure , arrows.Quantification of the proportion of each blood vessel type that contained αSyn or tau over time is shown in Figure To confirm that the tracer was in the BMs of vessels and not within abutting astrocyte end feet, brain sections were immunolabeled with GFAP . Slight co‐localization of perivascular GFAP with αSyn was observed at 30 minutes but not at 5 minutes or 24 hours. Tau was occasionally taken up by perivascular astrocytes at 5 minutes PI, but not at 30 minutes or 24 hours .3.3At 24 hours PI, perivascular tau is mainly within cells rather than in BMs Figure . To esta44.1In the present study, light‐sheet microscopy and confocal microscopy have shown that αSyn and tau are eliminated from the brain along intramural peri‐arterial drainage (or IPAD) pathways in the walls of cerebral arterioles in a manner similar to the elimination of Aβ and other solutes.There are some differences in the dynamics of IPAD between Aβ, αSyn, and tau. Examination of the drainage pattern of tau and αSyn through the whole hippocampus by light sheet microscopy showed that tau is not present within as many blood vessel walls as αSyn or Aβ. The number of arterioles with tau in their BMs (IPAD pathways) at 5 minutes PI is less than half of what has been reported for Aβ,Impairment of IPAD associated with aging of cerebral arteries also plays a major role in the accumulation of Aβ in the brain in AD and in the deposition of Aβ in the IPAD pathways in CAA.4.2The finding that αSyn and tau drain from the brain along IPAD pathways in a manner similar to Aβ has implications for both treatment and immunotherapy for αSyn‐ and tau‐related dementias. Clinical trials to identify drugs that will facilitate the drainage of Aβ along the impaired IPAD pathways by stimulating the vascular smooth muscle cells as the motive force for IPAD are underway.Anti‐tau immunotherapy attempts are ongoingDifferent immunotherapy compounds against αSyn are under developmentThis work was supported by the Medical Research Council [MR/R502261/1] and United Neuroscience [517698101]. The funding agency did not play any active role in the scientific investigation and reporting of the study.The authors have no competing interests to declare.Supplementary Figure S1: Astrocytes surrounding blood vessels after injection of α‐synuclein (αSyn)  or tau .  No αSyn staining (green) is associated with juxta‐vascular GFAP‐positive astrocytes (red) after injection of αSyn into the hippocampus of 10‐week‐old mice at (a) 5 minutes, (c) 30 minutes, or (e) 24 hours. A small degree of co‐localization of GFAP and αSyn is observed at 30 minutes (c) (arrows). Tau (green) co‐localized with GFAP‐positive astrocytes (red) at 5 minutes PI (b) but not at 30 minutes (d), or 24 hours (f). Scale bar = 10 µmClick here for additional data file.Supplementary Figure s2: Transition electron micrograph of (a) α‐synuclein (b) 2N4R tau used for injections. Light areas represent protein oligomers and larger aggregates. Monomers cannot be seen at this magnification and appear as a patchy background.Click here for additional data file.Supplementary Movie 1: 360o rotation of light‐sheet imaging of the distribution of αSyn at 5 minutes after injection. Vasculature was visualized by intracardial perfusion of ROXSE (white). αSyn (green) is found diffusely distributed within the dentate gyrus and surrounding the hippocampal vasculature.Click here for additional data file.Supplementary Movie 2: 360o rotation of light‐sheet imaging of the distribution of tau at 5 minutes after injection. Vasculature was visualized by intracardial perfusion of ROXSE (white). Tau (green) is found diffusely distributed within the dentate gyrus and surrounding the posterior cerebral artery.Click here for additional data file.Supplementary Movie 3: 360o rotation of light‐sheet imaging of the distribution of αSyn at 24 hours after injection. Vasculature was visualized by intracardial perfusion of ROXSE (white). The perivascular αSyn (green) can be observed mainly within the posterior cerebral artery.Click here for additional data file.Supplementary Movie 4: 360o rotation of light‐sheet imaging of the distribution of tau at 24 hours after injection. Vasculature was visualized by intracardial perfusion of ROXSE (white). Tau (green) accumulates around the transverse hippocampal arteries and longitudinal hippocampal arteries, which branch from the PCA.Click here for additional data file.