Apatite is a common accessory mineral found in almost all igneous, metamorphic, and clastic sedimentary rocks. It contains concentrations of lutetium and hafnium amenable to dating by the Lu-Hf ...isochron method. However, the application of this method has been hampered by chemical difficulties associated with the extraction of a clean Hf concentrate from apatite. A novel method of efficient chemical separation utilizing Ln and DGA-normal extraction chromatography columns has been developed for precise isotope analysis and is presented in this study. The routine analysis of sub-ng amounts of Hf maintained high yield close to 100%. The purification of Hf with a DGA-normal chromatography column effectively eliminated the interfering elements (Yb, Lu, and W), typically resulting in less than 1 pg of Lu in the analyzed apatite Hf solution. Apatite Lu-Hf isotope compositions of Otter Lake, Bancroft, and Durango apatites were determined using the reported methodology and yielded isochron ages of 1047.6 ± 3.4 Ma, 1092 ± 17 Ma, and 31.1 ± 1.1 Ma, respectively. All apatite Lu-Hf isochrons are characterized by phenomenally high apatite
176
Lu/
177
Hf and
176
Hf/
177
Hf ratios. Such apatite Lu-Hf isochrons are shown to be not significantly dependent on the initial isotopic composition in determining accurate and precise ages, allowing for anchoring the low end of the isochron with an estimated isotopic composition.
By using specialized extraction chromatography columns, we have developed an innovative approach that effectively separates Lu and Hf from apatite with high yields and minimal interference, addressing the challenges associated with dating apatite using the Lu-Hf isochron technique.
Because of their exceptional physical and thermal properties, cellulose nanocrystals (CNCs) are a highly promising bio‐based material for reinforcing fillers. Studies have revealed that some ...functional groups from CNCs can be used as a capping ligand to coordinate with metal nanoparticles or semiconductor quantum dots during the fabrication of novel complex materials. Therefore, through CNCs ligand encapsulation and electrospinning, perovskite‐NC‐embedded nanofibers with exceptional optical and thermal stability are demonstrated. The results indicate that, after continuous irradiation or heat cycling, the relative photoluminescence (PL) emission intensity of the CNCs‐capped perovskite‐NC‐embedded nanofibers is maintained at ≈90%. However, the relative PL emission intensity of both ligand‐free and long‐alkyl‐ligand‐doped perovskite‐NC‐embedded nanofibers decrease to almost 0%. These results are attributable to the formation of specific clusters of perovskite NCs along with the CNCs structure and thermal property improvement of polymers. CNCs‐doped luminous complex materials offer a promising avenue for stability‐demanding optoelectronic devices and other novel optical applications.
Perovskite/ cellulose nanocrystals (CNCs) encapsulated nanofiber (CNCs@PeNFs) for the white light‐emitting diodes through the electrospinning process are fabricated. The CNCs@PeNFs can maintain 90% intensity after five annealing cycles (from 20 to 140 °C) and 60% intensity after 6 h irritation of UV light, which are attributed to the complexation reaction between CNCs ligand and perovskite, and the cluster morphology within nanofibers.
Mitochondrial Ca(2+) uptake, a process crucial for bioenergetics and Ca(2+) signaling, is catalyzed by the mitochondrial calcium uniporter. The uniporter is a multi-subunit Ca(2+)-activated Ca(2+) ...channel, with the Ca(2+) pore formed by the MCU protein and Ca(2+)-dependent activation mediated by MICU subunits. Recently, a mitochondrial inner membrane protein EMRE was identified as a uniporter subunit absolutely required for Ca(2+) permeation. However, the molecular mechanism and regulatory purpose of EMRE remain largely unexplored. Here, we determine the transmembrane orientation of EMRE, and show that its known MCU-activating function is mediated by the interaction of transmembrane helices from both proteins. We also reveal a second function of EMRE: to maintain tight MICU regulation of the MCU pore, a role that requires EMRE to bind MICU1 using its conserved C-terminal polyaspartate tail. This dual functionality of EMRE ensures that all transport-competent uniporters are tightly regulated, responding appropriately to a dynamic intracellular Ca(2+) landscape.
The mitochondrial calcium uniporter is a Ca
channel that regulates intracellular Ca
signaling, oxidative phosphorylation, and apoptosis. It contains the pore-forming MCU protein, which possesses a ...DIME sequence thought to form a Ca
selectivity filter, and also regulatory EMRE, MICU1, and MICU2 subunits. To properly carry out physiological functions, the uniporter must stay closed in resting conditions, becoming open only when stimulated by intracellular Ca
signals. This Ca
-dependent activation, known to be mediated by MICU subunits, is not well understood. Here, we demonstrate that the DIME-aspartate mediates a Ca
-modulated electrostatic interaction with MICU1, forming an MICU1 contact interface with a nearby Ser residue at the cytoplasmic entrance of the MCU pore. A mutagenesis screen of MICU1 identifies two highly-conserved Arg residues that might contact the DIME-Asp. Perturbing MCU-MICU1 interactions elicits unregulated, constitutive Ca
flux into mitochondria. These results indicate that MICU1 confers Ca
-dependent gating of the uniporter by blocking/unblocking MCU.
The evolution of the Taiwan orogen, an active arc–continent collision zone between the North Luzon Arc (NLA) and the Eurasian continent, is recorded in arc volcanic and sedimentary rocks from the ...Taiyuan retro‐foredeep basin of the Coastal Range, eastern Taiwan. Arc volcanism in the northern NLA experienced a magmatic culmination at 9–7 Ma and a cessation at 5.3–4.3 Ma, based on new U‐Pb zircon ages. Young zircon U‐Pb ages (1.74, 1.58, and <1.2 Ma) and low Hf isotope signatures also indicate that three biotite‐bearing lapilli tuff layers deposited in the retro‐foredeep basin are associated with eruptions of the Lutao volcano in the southern NLA. NLA volcanism terminated progressively from ∼5.3 to <1.2 Ma in response to a southward‐propagating collision zone that followed the uplift of the orogenic wedge by <3 myr. The detrital zircon U‐Pb age spectra suggest no significant shift in provenance during the Plio‐Pleistocene period and indicate that the synorogenic sediments in the Taiyuan Basin were mainly derived from the Yuli Belt, a Miocene accretionary complex in the eastern Taiwan orogen. The accumulation rate of synorogenic deposits varies from 0.53 to 5.14 km/myr, with an abrupt increase at ∼2 Ma. This new rate is higher than the previously proposed rates and that of the pro‐foreland basin to the west, suggesting asymmetric and rapid uplift of the Taiwan orogen.
Plain Language Summary
Taiwan was formed by the northwestward convergence of the North Luzon Arc (NLA) with the Eurasian continental margin. Most of the uppermost parts of the arc volcanoes and orogens have been intensely eroded; nevertheless, their detritus is well preserved in the Taiyuan Basin in the southern Coastal Range, eastern Taiwan. In this study, zircons separated from remnant arc volcanic and sedimentary sequences are dated by an in situ U‐Pb method to offer temporal constraints and provide insight into the arc‐continental collision evolution in Taiwan. The latest ages from the NLA volcanoes reveal a southward cessation of magmatism from ∼5.3 to <1.2 Ma, which is consistent with an oblique collision. Detritus from the Yuli Belt, a Miocene accretionary prism in the eastern Taiwan orogen, started to fill the Taiyuan Basin beginning at <4.3 Ma. Meanwhile, three embedded tuff layers dated at 1.74, 1.58, and <1.2 Ma indicate eruptions associated with Lutao, an offshore NLA volcanic islet, and suggest an abrupt increase in the deposition rate at ∼2 Ma, corresponding to rapid and extensive exhumation of the Taiwan orogen.
Key Points
New zircon U‐Pb ages confirm the history of the volcanic arc and retro‐foredeep sediments and their linkages to the nearby Taiwan orogen
The previously proposed shift in clastic composition of the retro‐foredeep sediments is interpreted as an unroofing record of the Yuli Belt
Our zircon ages confirm the abrupt increase in the deposition rate of retro‐foredeep basin infilling from 0.53 to 5.14 km/myr at ∼2 Ma
Infrared spectra for a series of asymmetric proton‐bound dimers with protonated trimethylamine (TMA‐H+) as the proton donor were recorded and analyzed. The frequency of the N–H+ stretching mode is ...expected to red shift as the proton affinity of proton acceptors increases. The observed band, however, shows a peculiar splitting of approximately 300 cm−1 with the intensity shifting pattern resembling a two‐level system. Theoretical investigation reveals that the observed band splitting and its extraordinarily large gap of around 300 cm−1 is a result of strong coupling between the fundamental of the proton stretching mode and overtone states of the two proton bending modes, that is commonly known as Fermi resonance (FR). We also provide a general theoretical model to link the strong FR coupling to the quasi‐two‐level system. Since the model does not depend on the molecular specification of TMA‐H+, the strong coupling we observed is an intrinsic property associated with proton motions.
Huge Fermi resonance coupling was found in the experimental IR predissociation spectra of proton‐bound dimers based on protonated trimethylamine (TMA‐H+). An ab initio anharmonic vibrational analysis could explain the quasi‐two‐level behavior of the multiple states in the Fermi resonance as the proton affinity of proton acceptors varies.
We report our investigation into the MCU-inhibitory activity of Co
3+
complexes in comparison to Ru265. These compounds reversibly inhibit the MCU with nanomolar potency. Mutagenesis studies and ...molecular docking simulations suggest that the complexes operate through interactions with the DIME motif of the MCU pore.
The MCU-inhibitory properties and mechanisms of action of Co
3+
amine complexes and Ru265 are described.
Introduction: While various antiretrovirals have been studied as potential candidates for long‐acting pre‐exposure prophylaxis (PrEP), the bimonthly injectable cabotegravir—the first long‐acting form ...of PrEP—was approved in 2021. Event‐driven (ED) PrEP has been the most prevalent dosing regimen among gay, bisexual and other men who have sex with men (GBMSM) in Taiwan, providing a unique setting to observe the preferences for long‐acting PrEP in a community where the daily regimen is not the mainstream method. This study aimed to determine the preferences for the different forms and dosing intervals of long‐acting PrEP that are currently in the development pipeline. Methods: We conducted a survey in 2021 by convenience sampling the users of social networking applications for GBMSM in Taiwan. Our survey included questions on sexual behaviours, current PrEP regimens and the preferences for potential candidates of long‐acting PrEP, such as implants, intramuscular and subcutaneous injections. We compared the Likert‐scale preference ratings for potential long‐acting options, and conducted logistic regression analysis to examine the factors associated with a preference for bimonthly intramuscular injections (2M IM) over ED and daily PrEP regimens, respectively. Results: A total of 1728 responses were eligible for analysis. Three percent of respondents (n = 52) were daily PrEP users; 11.5% (n = 198) were ED PrEP users. When not considering cost, current PrEP users—regardless of their original dosing regimen—were most likely to express preferences for monthly oral PrEP, followed by a 6‐month subcutaneous injectable (6M SC) and 2M IM. However, among non‐current PrEP users, monthly oral PrEP was the most preferred form, followed by ED, daily oral and 6M SC injectable. Multivariable logistic regression revealed that current daily users, those willing to take PrEP in the next 6 months and those with more sex partners in the last 12 months had a significant correlation with preferences for the 2M IM injectable over the ED PrEP. Conclusions: The monthly oral form was the most preferable long‐acting PrEP among GBMSM in Taiwan. Current daily PrEP users preferred the 2M IM injectable over the ED PrEP, which made the 2M IM injectable a potential alternative. Further studies should focus on how the cost and delivery affect PrEP preferences and their actual uptake.
The intention of chemsex-practicing gay and bisexual men and other men who have sex with men (GBMSM) to reduce their drug use is an important factor for the utilization of harm reduction services. ...This study aimed to examine data from an integrated sexual health services center to understand the relationship between the intention to reduce chemsex behavior and chemsex-related utilization of mental health services among GBMSM who engage in chemsex.
We used data collected from Healing, Empowerment, Recovery of Chemsex (HERO), an integrated health center in Taiwan, between November 2017 and December 2021. As the baseline, clients were asked to rate the current and ideal proportions of their sexual activities that involved the use of MDMA, ketamine, methamphetamine, GHB/GBL, or mephedrone. Having the intention to reduce chemsex was defined as having a lower proportion of ideal engagement compared to actual engagement. The data on the use of the services provided at HERO were linked to the survey responses and compared to information gathered during regular follow-up visits. Univariable and multivariable logistic regression analyses and a Poisson regression analysis were performed on the data.
A total of 152 GBMSM reported engaging in chemsex, of whom 105 (69.1%) expressed the intention to reduce their chemsex behavior. Service utilization ranged from 23.0% for participating in meetings of a chemsex recovery group, 17.1% for visiting a mental health clinic, and 10.5% for using both of these services. The intention to reduce chemsex behavior significantly associated with visiting a mental health clinic (aOR = 4.68, p < 0.05), but its association with attending meetings of a chemsex recovery group was only marginally significant (aOR = 2.96, p < 0.1). Other factors that remained significantly associated with service use were a high frequency of substance use and living with HIV.
Comprehensive harm reduction strategies, which touch on mental health, drug use management and recovery, are needed for those who want to reduce their chemsex behavior. Public health practitioners should endeavor to raise awareness of resources that are available for people who engage in chemsex and to minimize the barriers blocking their access to the appropriate services.
Mitochondrial Ca2+ uptake, mediated by the mitochondrial Ca2+ uniporter, regulates oxidative phosphorylation, apoptosis, and intracellular Ca2+ signaling. Previous studies suggest that non-neuronal ...uniporters are exclusively regulated by a MICU1-MICU2 heterodimer. Here, we show that skeletal-muscle and kidney uniporters also complex with a MICU1-MICU1 homodimer and that human/mouse cardiac uniporters are largely devoid of MICUs. Cells employ protein-importation machineries to fine-tune the relative abundance of MICU1 homo- and heterodimers and utilize a conserved MICU intersubunit disulfide to protect properly assembled dimers from proteolysis by YME1L1. Using the MICU1 homodimer or removing MICU1 allows mitochondria to more readily take up Ca2+ so that cells can produce more ATP in response to intracellular Ca2+ transients. However, the trade-off is elevated ROS, impaired basal metabolism, and higher susceptibility to death. These results provide mechanistic insights into how tissues can manipulate mitochondrial Ca2+ uptake properties to support their unique physiological functions.
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•The uniporter can be gated by MICU1 homo/heterodimers or MICU-deregulated in tissues•Ca2+ more readily activates the uniporters with MICU1-MICU1 than MICU1-MICU2 dimers•The conserved MICU1 intersubunit disulfide protects MICUs against proteolysis•Tissue-specific MICU regulation comes with physiological benefits and disadvantages
Mitochondrial Ca2+ uptake regulates oxidative phosphorylation, cell death, and cytoplasmic Ca2+ signaling. Tsai et al. demonstrate how tissues can customize their mitochondrial Ca2+ uptake properties by modulating the composition and expression of the MICU subunits in their mitochondrial Ca2+ uniporter complexes and also explore the physiological significance of such tissue specificity.
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