Tracking the final fate of subducting carbon is crucial to understanding global carbon cycles and climate changes in the history of the Earth. Available geochemical tracers such as carbon isotopes ...are apt to identify recycled organic carbon but usually insufficient to discriminate between primordial carbon in the mantle and carbon derived from recycled carbonate sediments. In the past decade, magnesium and zinc isotope systematics have been proposed as novel proxies for subducting carbon owing to the noticeable isotopic offsets between carbonate sediments and the mantle (i.e., δ26Mgcarbonate < δ26Mgmantle; δ66Zncarbonate > δ66Znmantle). Nonetheless, isotopic effects induced by subduction-zone processes and crystal-melt differentiation may obscure the information of Mg and Zn isotopic compositions of mantle-derived magmas. In this paper we firstly discuss how these processes modify the Mg and Zn isotopic systematics of mantle-derived magmas. Based on the fact that different carbonate species (calcite, dolomite, and magnesite) possess distinct Mg and Zn contents and their stabilities in subduction zones vary with pressure, we then develop the two isotope systematics as tools to track the final storage depth of subducting carbon. We test this application by collating available Mg and Zn isotopic compositions of ultramafic xenoliths and basaltic lavas sourced from various mantle depths. The lack of light Mg and heavy Zn isotopic anomalies of global arc lavas supports experimental and theoretical prediction that the dissolved carbonate species in the sub-arc mantle−if any−is dominated by calcium-rich carbonate. The findings of pervasive low-δ26Mg and high-δ66Zn ultramafic xenoliths and basaltic lavas sourced from the sub-continental lithospheric mantle (SCLM) suggest that the SCLM is an important storage of subducting carbon via metasomatism by dolomite that can be substantially dissolved by supercritical fluids at depths of >160 km. Intraplate alkali basalts with low δ26Mg and high δ66Zn are commonly restricted to the regions with stagnant slabs at depths of ~410–660 km, suggesting that the mantle transition zone is another global storage of subducting carbon composed mainly of Mg-rich carbonates. Overall, observations on mantle-derived rocks, with Mg and Zn isotopes as the tracers, indicate that a significant flux of Earth's surface carbon has survived the arc regime and been recycled into the deeper mantle. Future studies that explore a quantitative relationship between Mg-Zn isotopic ratios and the flux of subducting carbon will further promote the application of the paired isotopic proxies.
•Factors obscuring the interpretation of Mg and Zn isotopic data of mantle-derived rocks or magmas were reviewed.•Developing Mg and Zn isotopes as novel proxies for the storage depths of subducting carbonates in the mantle.•Test this application using available Mg and Zn isotope data of natural samples from various mantle depths.•A significant flux of Earth's surface carbon have survived the arc regime and been recycled into the deeper mantle.
As an innovative form of stimulus-response materials, organic-inorganic hybrid phase transition materials have become a wonderful contender in the field of functional electronic equipment due to ...their versatile structure, intensive functions and straightforward preparation. However, the targeted regulation and optimization of the electrical/optical response, along with the establishment of regular structure-performance relationships, pose significant challenges in meeting the diverse demands of practical applications over an extended period. Herein, we conducted a systematic investigation into the role of lattice void occupancy in regulating phase transition temperature (
T
p
) and related optical/electrical bistability. By taking hybrid material TMEACd(SCN)
3
featuring a flexible ammonium cation TMEA
+
(TMEA = ethyltrimethylammonium) as the prototype, we successfully synthesized three phase transition materials, namely DEDMACd(SCN)
3
, TEMACd(SCN)
3
and TEACd(SCN)
3
(DEDMA = diethyldimethylammonium, TEMA = triethylmethylammonium, and TEA = tetraethylammonium), and the excellent regulation of the physical properties of these compounds was achieved through subtle engineering of void occupancy. More strikingly, TEACd(SCN)
3
exhibits remarkable bistable properties in terms of dielectric and nonlinear optical responses (with second-harmonic generation intensity reaching 2.5 times that of KDP). This work provides a feasible avenue to reasonably customise organic-inorganic hybrid phase transition materials and finely adjust their intriguing functionalities.
Similar to a tossed stone raising a thousand ripples, it was found that a small structural mechanism associated with void occupancy has subtle influence on phase transition material physical properties in this work.
Comprehensive Summary
Molecular ferroelastics with the natural features of mechanical flexibility and switchable spontaneous strain have attracted widespread attention in the scientific community due ...to their potential applications in tunable gratings, flexible memorizers, strain sensors, and intelligent actuators. However, most designs of molecular ferroelastics remain in the stage of blind exploration, posing a challenge to achieve a functional ferroelastic more effectively. Herein, we have successfully obtained a molecular ferroelastic, Me2NH(CH2)2NH3(ReO4)2 (Me2NH(CH2)2NH3 = N,N‐dimethylethylenediammonium), under the guidance of the mono‐/double‐protonation strategy. The double‐protonated Me2NH(CH2)2NH3(ReO4)2 undergoes a paraelastic‐ferroelastic phase transition with the Aizu notation of 2/mF1¯ at 322 K. Meanwhile, the theoretical calculation and experimental measurement simultaneously show that Me2NH(CH2)2NH3(ReO4)2 possesses good mechanical flexibility, because its elastic modulus (E) of 8.26 GPa and hardness (H) of 0.45 GPa are smaller than the average values of organic crystals (E of 12.05 GPa and H of 0.5 GPa), which makes it promising to apply in wearable pressure sensors, implantable medical sensors, high‐precision tuners, etc. This work further enriches the molecular ferroelastic family and demonstrates that mono‐/double‐protonation is one of the effective molecular modification strategies for designing ferroelastics.
By the effective chemical strategy of mono‐/double‐protonating organic cations, a novel molecular ferroelastic Me2NH(CH2)2NH3(ReO4)2 was successfully prepared. Notably, it exhibits excellent mechanical flexibility and demonstrates the bright prospects in wearable and human‐compatible electromechanical applications.
Hybrid metal halides with nonlinear optical (NLO) and dielectric dual switching properties are a class of materials with great application prospects in the fields of optoelectronics and smart ...devices. However, effectively modifying and regulating molecular structures to obtain temperature-responsive NLO switching performance is still a challenge. Herein, we reported a strategy to modify symmetry by employing halogen substitution. Br with greater electronegativity reduced the symmetry from the centrosymmetric (Cl-MM)
2
MnBr
4
(
1
) to the noncentrosymmetric (Br-MM)
2
MnBr
4
(
2
). Therefore, the structure was enriched with NLO, and its NLO can be switched by the structural phase transition. Then it is natural that the reversible dielectric switches were triggered in both the lead-free compounds by the phase changes. In addition, they exhibit bright green fluorescence under ultraviolet light, and the photoluminescence quantum efficiency reaches 47.24% and 40.69%, respectively. These results indicate that the halogen-modification strategy has injected new vitality into the exploration of the development of multi-response materials with NLO and dielectric switching performance.
An effective strategy of using halogens to modify organic-inorganic hybrid materials to obtain NLO switching characteristics, which is expected to be used for the directional adjustment of NLO switch activity.
Stem cells derived from oral tissue represent a highly attractive alternative source for clinical bone regeneration because they can be collected by non-invasive or minimally invasive procedures. ...Herein, we describe the human dental stem cells (DSCs) deriving from buccal fat pads (BFP), dental pulp (DP) of impacted teeth, and periodontal ligaments (PDL) to obtain BFPSCs, DPSCs, and PDLSCs, respectively. Cells were purified with selected medium and expanded through passages in stem cell culture medium. Purified cells were characterized for stemness by their growth rate, immunostaining, and multilineage differentiation ability. They showed plastic adherence, expression of stemness-specific markers, and multilineage differentiation potential. Immunocytochemistry analysis confirmed that DPSCs had more osteogenic potential than BFSCs and PDLSCs. Calcium-rich deposits, evaluated by von Kossa and Alizarin red staining, showed greater mineralization when DPSCs were cultured on collagen type I matrix than without collagen. Furthermore, DPSC-seeded collagen type I matrix maintained consistent osteogenesis and boosted mineral formation by 1–2 weeks over that in DPSCs cultured without collagen. Radiographic analysis of DPSC-seeded collagen type I matrix transplanted into rat cranial defects showed significant bone regeneration after 8 weeks. These results suggested that the redundant oral tissue can be used as a source of adult multipotent stem cells for clinical bone regeneration.
Graphical abstract
Triple overlay images with biomarkers (red), nuclei (blue) and bright field morphology of DPSCs. The specifically osteo-differentiation shown by osteocalcin (left) expression and lack of sox9 (right) expressed in the images below which were cultured with collagen matrix, contrast with no collagen matrix group above.
Carbon in the form of carbonate in sediments and altered oceanic crust can be transported into the mantle by subducted slabs, but how to identify recycled carbonate and decipher its storage depths in ...the mantle still requires to be investigated for typical subduction zones. Here we investigate possible carbonate recycling related to subduction of the Neo-Tethyan oceanic slab, by a combined study of Mg and Zn isotopes on three types of Cenozoic mantle-derived lavas from central Myanmar. The calc-alkaline lavas have arc-like geochemical characteristics and originated from the mantle wedge. These rocks have high δ26Mg (−0.20‰ to +0.03‰), interpreted to be caused by the input of Mg-rich fluids from dehydration of altered subducted slab. The alkali basalts of suite I are depleted in Nb and Ta and were derived from partial melting of the lithospheric mantle, which have normal δ26Mg and δ66Zn. By contrast, the alkali basalts of suite II display OIB-like trace element patterns and originated from the asthenospheric mantle. They possess extremely low δ26Mg (−0.66‰ to −0.48‰) and high δ66Zn (0.57‰ to 0.77‰) that is typically characterized by marine carbonates. No known processes (e.g., magmatic processes and diffusion effects) can account for the coupling of low δ26Mg and high δ66Zn except source heterogeneity caused by recycled magnesian carbonates (magnesite ± dolomite). This is supported by Mg-Zn-Sr isotopic mixing modelling that suggests a “magnesian carbonate + pyroxenite” source. Since calcic carbonate transforms to magnesite at depths of >300 km during subduction, carbonates carried by the Neo-Tethyan oceanic slab may have been recycled into the mantle transition zone as revealed by seismic tomography observations on central Myanmar.
•A combined study of Mg and Zn isotopes on Cenozoic lavas from central Myanmar.•The finding of extremely low δ26Mg and high δ66Zn in alkali basalts.•Evidence for deep carbonate recycling related to Neo-Tethyan oceanic slab subduction.
Organic-inorganic metal halides (OIMHs) possessing switchable optical and electrical properties hold significant promise for applications in multifunctional sensors, switching devices, and ...information storage. However, the challenge lies in achieving effective regulation of optical/electric responses through structural design strategies, and materials with structural phase transition coupling photoluminescence (PL) quenching are also relatively rare. Here, by employing halogen engineering to modify the parent compound (TEMA)PbBr
3
(TEMA = triethylmethylammonium), we successfully obtained two derivatives (TECA)PbBr
3
and (TEBA)PbBr
3
(TECA = triethylchloromethylammonium and TEBA = triethylbromomethylammonium). Halogen engineering successfully introduces halogen-halogen interactions between PbBr
3
n
−
inorganic frameworks and organic cations, which increases the stretching distortion of the PbBr
6
octahedral framework of (TECA)PbBr
3
and (TEBA)PbBr
3
, accompanied by prominent orange-red broadband emission behavior in (TECA)PbBr
3
and (TEBA)PbBr
3
. Meanwhile, the phase transition temperatures (
T
p
) of (TECA)PbBr
3
and (TEBA)PbBr
3
have also been significantly increased compared to (TEMA)PbBr
3
, and two derivatives demonstrated switchable dielectric responses. Impressively, the reversible structural phase transition of (TECA)PbBr
3
and (TEBA)PbBr
3
dominates the outright PL quenching behavior, while still maintaining high PL emission intensity below the
T
p
. This represents a rare and extraordinary phenomenon in the realm of bistable responsive materials. This work provides a feasible strategy for designing and modulating photoluminescent phase transition materials and deepens understanding of the structural-performance relationship.
(TECA)PbBr
3
and (TEBA)PbBr
3
have a wide range of photoluminescence signals and undergo coupling of the structural phase transition and photoluminescence quenching.
Patients with chronic kidney disease (CKD) are at high risk of infection, but whether the risks are attenuated in different patient groups remains unclear. This study enrolled participants with CKD ...stages 1-3 in the New Taipei City Health Screening Program between 2005 and 2008. A proportional hazard regression model was employed to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) for infection-related hospitalization and mortality in younger (<50-year-old) and older (≥50-year-old) CKD patients. Of 119,871 adults, there were 14,207 cases of first hospitalization for infection during a median follow-up of 8.14 years; 45.5% of these cases were younger patients. Unlike CKD stage 1 and 2 patients, the risk of infection-related hospitalization in younger CKD stage 3 patients is as high as for older CKD stage 3 patients. Proteinuria increases the risk of infection-related hospitalization independent of estimated glomerular filtration rate (eGFR) levels in older CKD patients but this relationship is weak in their younger counterparts. In conclusion, the risk of infection-related hospitalization is high in subgroups of CKD patients. Prevention and treatment of infections in these patients merit more attention.
The Severe Acute Respiratory Syndrome-associated Coronavirus 2 (SARS-CoV-2) was an outbreak in December, 2019 and rapidly spread to the world. All variants of SARS-CoV-2, including the globally and ...currently dominant Delta variant (Delta-SARS-CoV-2), caused severe disease and mortality. Among all variants, Delta-SARS-CoV-2 had the highest transmissibility, growth rate, and secondary attack rate than other variants except for the new variant of Omicron that still exists with many unknown effects. In Taiwan, the pandemic Delta-SARS-CoV-2 began in Pingtung from 14 June 2021 and ceased at 11 July 2021. Seventeen patients were infected by Delta-SARS-CoV-2 and 1 person died during the Pingtung outbreak. The Public Health Bureau of Pingtung County Government stopped the Delta-SARS-CoV-2 outbreak within 1 month through measures such as epidemic investigation, rapid gene sequencing, rapidly expanding isolation, expanded screening of the Delta-SARS-CoV-2 antigen for people who lived in regional villages, and indirect intervention, including rapid vaccination, short lockdown period, and travel restrictions. Indirect environmental factors, such as low levels of air pollution, tropic weather in the summer season, and rural areas might have accelerated the ability to control the Delta-SARS-CoV-2 spread. This successful experience might be recommended as a successful formula for the unvaccinated or insufficiently vaccinated regions.
Chiral organic-inorganic hybrid materials with multi-channel switchable characteristics play an important role in the fields of sensors, intelligent switches, and information memorizers. The ...introduction of chiral organic amine into materials with photoluminescent properties is expected to achieve multi-channel switchable characteristics. Here, we report a pair of chiral organic-inorganic hybrids (
R
-HASD)
2
MnBr
4
and (
S
-HASD)
2
MnBr
4
(HASD = 2-hydroxy-5-azaspiro4.5decan) containing spirocyclic cations and having dielectric/second harmonic generation (SHG)/photoluminescence (PL) triple-channel switchable properties. Both compounds undergo a reversible plastic phase transition around 380 K. Under ultraviolet (UV) irradiation, both of them show intense green emission and their photoluminescence quantum yields (PLQYs) are above 70%. Therefore, multifunctional hybrid compounds with triple-channel dielectric/SHG/PL switches and excellent PL properties have been successfully prepared. This work is of great significance for further exploration of chiral multifunctional switchable materials.
Organic-inorganic hybrid (
R
/
S
-HASD)
2
MnBr
4
with dielectric/SHG/PL triple-channel properties is successfully obtained, which exhibits outstanding SHG signals and excellent PL properties.
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