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Exploring polymeric hole-transporting materials (HTMs) with passivation functions represents a simplified and effective approach to minimize the perovskite defect density. To date, most of reported polymeric HTMs were applied to fabricate n-i-p regular perovskite solar cells (PSCs). The polymers compatible for p-i-n inverted PSCs were very limited. Moreover, the passivation polymers were devoted to passivate the uncoordinated Pb2+. However, the MA+cation defect has profound unwanted effect on device efficiency and long-term stability. In order to synchronously passivate the Pb2+and MA+defects in p-i-n inverted PSCs, a new nonfused polymer was intentionally explored via mild polymerization. The aromatic bridge instead of long alkyl chains enabled polymer BN-12 to achieve excellent thermal stability and good wettability of perovskite precursor. Furthermore, the incorporation of chemical anchor sites (“C═O” and “F”) strongly controlled the crystallization of perovskite and restrained the MA+ion migration. As a result, a significant fill factor (FF) of 82.9% and an enhanced power conversion efficiency (PCE) of 20.28% were achieved for MAPbI3-based devices with the dopant-free BN-12, exceeding those with the commercial HTM PTAA (FF = 81.7%, PCE = 19.51%). More importantly, the unencapsulated devices based on BN-12 realized outstanding long-term stability, maintaining approximately 95% of its initial efficiency after stored for 85 days. By contrast, the PTAA-based device showed rapid decrease which retained only 50% of its initial value after 45 days.

In preparing efficient and stable perovskite solar cells (PSCs), it is challenging to simultaneously overcome the inherent problems of grain boundary grooves (GBGs), residual stress, defect states in perovskite film. Herein, a small organic molecule additive, pyridinium 1,4-zwitterionic thiolates (PZT), is synthesized to prepare high-quality PZT-doped perovskite active layer through bulk molecule doping method. The PZT promotes the crystallization of perovskite, optimizes the crystal orientation, and smooths the GBGs of perovskite films. Meanwhile, PZT releases compressive stress and passivates the perovskite defects at the surface/interface as well as internal grain boundaries in the perovskite film, which inhibits the charge recombination and promotes the charge separation and transport efficiency in the bulk perovskite films through the atomic interaction at the perovskite/PZT interface. In addition, the PZT also inhibits ion migration in perovskite film and increases film hydrophobicity. Benefiting from the above benefits, the PSCs based on perovskite:PZT layer achieved a maximum power conversion efficiency of 23.45%, much higher than that (21.79%) of control device. They also show significantly improved long-term stability under different aging test conditions. Our work provides a guide for improving the performance of PSCs by designing suitable multifunctional molecules.

The two-step sequential deposition strategy has garnered widespread usage in the fabrication of high-performance perovskite solar cells based on FAPbI3. However, the rapid reaction between FAI and PbI2during preparation often leads to incomplete reactions, reducing the device efficiency and stability. Herein, we introduced a multifunctional additive, 2-thiophenyl trifluoroacetone (TTA), into the FAI precursor. The incorporation of TTA has proven to be highly effective in slowing the reaction rate between FAI and PbI2, resulting in increased perovskite formation and improved efficiency and stability of the devices. TTA’s CF3groups interact with FAI via hydrogen bonding, effectively suppressing FA+defects. The S and C═O groups share lone pair electrons with uncoordinated Pb2+, leading to a reduction in perovskite film defects and suppressing nonradiative recombination. Additionally, the CF3groups impart hydrophobicity, protecting the perovskite film from moisture-induced erosion. As a result, the TTA-modified perovskite film achieves a Champion efficiency of 23.42% compared to the control’s 21.52, with 20.58% efficiency for a 25 cm2solar module. Remarkably, the unencapsulated Champion device retains 86% of its initial PCE after 1080 h under dark conditions (60 ± 5 °C, 35 ± 5% RH), indicating enhanced long-term stability. These findings offer a promising and cost-effective tactic for high-quality perovskite film fabrication.

Two spiro-bifluorene-based dopant-free HTMs (X22 and X23) have been synthesized by facilely condensing spiro-bifluorene diamine with 3,4-ethylenedioxythiophene (EDOT)-5,7-dicarbonyl dichloride and 2,3,5,6-tetrafluoro-terephthaloyl dichloride, respectively. In the X22 molecule, lone pairs of electrons on the sulfur (S) and oxygen (O) functional groups interact with the perovskite materials. The hole mobility (μh) of X22 (3.9 × 10–4cm2V–1S1–) is more than twice that of X23 (1.4 × 10–4cm2V–1S1–). The conductivity (σ0) of X22 is 2.73 × 10–4S cm–1, which is also higher than that of X23 (2.39 × 10–4S cm–1). The EDOT moiety benefits the contact angle of CH3NH3PbI3precursor solutions on HTMs as low as 24°. The X22-based device with an indium-doped tin oxide/hole transport material (HTM)/CH3NH3PbI3/phenyl-C61-butyric acid methyl ester (PC61BM)/bathocuproine/Ag structure achieves a power conversion efficiency (PCE) of 19.18%. The PCE of the device based on X23 containing fluorine is 18.70%, and the contact angle between HTM and the perovskite precursor solution is 32°. The X22- and X23-based devices at ambient temperature (≈25 °C) in N2retain 86% and 79% of the initial PCE after 150 days. The effect of S, O, and F heteroatoms plays an important role in the side chain modification of HTMs, improving defect passivation in HTM/CH3NH3PbI3interfaces by multiple functional groups.

The selective oxidation of amines to imines under mild conditions has attracted much attention. Our study reveals that copper phenylacetylide (PhC2Cu) could serve as an efficient photocatalyst for imine synthesis under visible-light irradiation (>400 nm). Utilizing benzylamine as a model reactant, PhC2Cu achieves an imine yield of 50.4%, which is 5 times higher than that of P25 under the same conditions and comparable to the yield obtained by the 3 wt % Au/P25 photocatalyst (55.4%). Further loading 3.9 nm TiO2onto PhC2Cu through tetrabutyl titanate hydrolysis increases the imine yield to 84.7%, with a Ti:Cu atomic ratio of 3.65%. Control experiments, photoluminescence (PL) spectra, optical pump terahertz probe (OPTP) spectra, and electron spin resonance (ESR) tests confirm that the optimized TiO2modification promotes the separation of excited carriers and electron transfer in PhC2Cu and facilitates the activation of surface oxygen, thereby enhancing the formation of superoxide radicals, a key active oxygen species in the reaction system. This work presents a promising strategy for efficient imine synthesis via amine coupling and expands the application field of PhC2Cu-based photocatalysts.

In this work, a comprehensive study on the deliberate molecular design and modifications of electron donors is carried out to elucidate correlations between the methoxy effects and donor configuration of hole-transporting materials (HTMs). Our initial findings demonstrate the donor-dependent methoxy effects. Photovoltaic performance of the HTM with twisted donor highly depends on the methoxy substituent. In contrast, efficiency's reliance on methoxy is insignificant for the HTM with planar donor. The HTM (M123) featuring the methoxy‑substituted carbazole shows a decent power conversion efficiency of 19.33% due to synergistic effects from both planar structure and methoxy. This work gives a guideline to access HTMs reaching both high-performance and good stability.

The mismatch of the energy level between the electron transport layer (ETL) and the perovskite (PS) film is one of the origins of current–voltage (J–V) hysteresis in perovskite solar cells (PSCs). Drift-diffusion simulations are conducted to explain how the band alignment affects the charge extraction across the ETL/PS interface, and hence varies the responses of photocurrent. Our simulations show that the band alignment has a profound influence on the evolution of the profiles of movable ions during voltage scan. The band mismatch at the ETL/PS interface is shown to engender the accumulation of movable anions and give rise to severe J–Vhysteresis. We further demonstrate that a rational design on the energy alignment of PSCs is vital to reduce the hysteresis no matter if charge loss in PSCs is determined by bulk recombination or trap-assisted surface recombination. Moreover, the PSCs suffering from interface band mismatch are found to exhibit various hysteresis behaviors depending on the rate of voltage scan. It implies that the voltage scan at different speeds could be helpful to diagnose the problem of PSCs.

Deeply understanding of the performance discrepancy of hole-transporting materials (HTMs) in perovskite solar cells (PSCs) with different configuration (inverted or direct) is important for designing efficient HTMs. Herein, three organic HTMs TZ1, TZ2, and TZ3 have been employed to fabricate the inverted PSCs. Optoelectronic properties and photovoltaic performance of these HTMs are investigated. TZ3 featuring the 3,6-di(thiophen-2-yl)thieno[3,2-b]thiophene conjugate bridge shows a higher work function and enhanced capability of hole extraction, achieving a higher power conversion efficiency (PCE) of 16.33% in the inverted PSCs. Importantly, results reveal that the conjugate bridge has a relevant effect on the photovoltaic performance of cells with different device configuration. The PCE trend of TZ1, TZ2, and TZ3 in inverted PSCs is diametrically opposed to that of direct devices. We proposed that linear triphenylamine HTMs contain a fused bridge with high degree of conjugation are good choice for the direct PSCs. On the other hand, it is better to incorporate linear triphenylamine HTMs with deep highest occupied molecular orbital (HOMO) toward the inverted PSCs, because the photovoltage plays a crucial role in the efficiency of the inverted PSCs. This systematic study provides a new viewpoint to design HTMs toward PSCs with different device configuration.

The triple oxygen isotope signature Δ17O in atmospheric CO2, also known as its “17O excess,” has been proposed as a tracer for gross primary production (the gross uptake of CO2by vegetation through photosynthesis). We present the first global 3‐D model simulations for Δ17O in atmospheric CO2together with a detailed model description and sensitivity analyses. In our 3‐D model framework we include the stratospheric source of Δ17O in CO2and the surface sinks from vegetation, soils, ocean, biomass burning, and fossil fuel combustion. The effect of oxidation of atmospheric CO on Δ17O in CO2is also included in our model. We estimate that the global mean Δ17O (defined as Δ17O=ln(δ17O+1)−λRL·ln(δ18O+1)with λRL= 0.5229) of CO2in the lowest 500 m of the atmosphere is 39.6 per meg, which is ∼20 per meg lower than estimates from existing box models. We compare our model results with a measured stratospheric Δ17O in CO2profile from Sodankylä (Finland), which shows good agreement. In addition, we compare our model results with tropospheric measurements of Δ17O in CO2from Göttingen (Germany) and Taipei (Taiwan), which shows some agreement but we also find substantial discrepancies that are subsequently discussed. Finally, we show model results for Zotino (Russia), Mauna Loa (United States), Manaus (Brazil), and South Pole, which we propose as possible locations for future measurements of Δ17O in tropospheric CO2that can help to further increase our understanding of the global budget of Δ17O in atmospheric CO2. This work presents a first view on possible spatial and temporal gradients of Δ17O in CO2across the globeTropical, boreal, and Southern Hemisphere observations of Δ17O in CO2could be of great interestWe implemented spatially and temporally explicit sources and sinks of Δ17O in CO2in a 3‐D model framework

Diphenylamine-substituted carbazole (DPACZ) compounds are one of the most interesting hole-transporting materials (HTMs) for perovskite solar cells (PSCs). However, most studies focused on the development of symmetrical DPACZ HTMs with two DPACZ arms or multiple ones. In this work, we developed a new class of asymmetric DPACZ-based HTMs (M111–114) through a combination of one DPACZ arm and different S,N-heterocyclic compounds (phenothiazine (PTZ) and dithieno[3,2-b:2′,3′-d]pyrrole (DTP)), which endow the M111–114 with different electrochemical and photophysical properties as well as hole-transporting properties. Results conclude that the PTZ outperforms of the DTP when combined with the DPACZ arm. In addition, we have investigated the substituent and conjugation effects of heterocyclic properties on the photophysical and electrical properties, as well as performance in PSCs by using physical measurements. PSCs with M114 exhibit a power conversion efficiency of 17.17%, which is higher or comparable to that of DPACZ HTMs with more than one DPACZ arm. Importantly, the synthetic cost of the M114 is only 14.95 $ per g, which is much lower than that of spiro-OMeTAD. This work indicates that DPACZ-heterocycle compounds could be a new class of low-cost HTMs in the large-scale application of PSCs.

This work uses Sounding of the Atmosphere using Broadband Emission Radiometry CO2data from 2002 to 2015 and Specified Dynamics‐Whole Atmosphere Community Climate Model (SD‐WACCM) outputs from 1979 to 2014 to show, for the first time, the solar cycle response of CO2in the Austral winter mesosphere and lower thermosphere region. Both Sounding of the Atmosphere using Broadband Emission Radiometry and SD‐WACCM show that CO2experiences a decrease during solar maximum throughout the Austral winter mesosphere and lower thermosphere region. This work highlights the regions where CO2experiences its strongest and weakest solar cycle responses as modeled by SD‐WACCM. The region with the strongest solar cycle response experiences around 5% reduction in CO2between solar maximum and solar minimum. The region with weakest solar cycle response experiences less than 1% reduction in CO2between solar maximum and solar minimum. It is shown that the region of the strongest CO2response is driven by photodissociation, downwelling, and reduced eddy diffusion. On the other hand, the region of the weakest CO2response is driven by the opposing effects of photodissociation and enhanced eddy diffusion. This is the first work to show that the solar cycle could affect the Austral winter lower thermosphere circulation and eddy diffusion processes. These anomalies in the lower thermospheric circulation and eddy diffusion are found to be related to the solar cycle response in the Austral winter mesosphere wave‐mean flow dynamics. This work therefore concludes that the solar cycle affects lower thermospheric CO2via modulations of the lower thermospheric circulation and eddy diffusion processes. Response of CO2in the Austral winter MLT to the 11‐year solar cycle is presentedSolar cycle response of CO2in the Austral winter MLT is driven by photochemistry and transportThe residual circulation and eddy diffusion in the Austral winter lower thermosphere respond to the 11‐year solar cycle

The core plays a crucial role in achieving high performance of linear hole transport materials (HTMs) toward the perovskite solar cells (PSCs). Most studies focused on the development of fused heterocycles as cores for HTMs. Nevertheless, nonfused heterocycles deserve to be studied since they can be easily synthesized. In this work, we reported a series of low-cost triphenylamine HTMs (M101–M106) with different nonfused cores. Results concluded that the introduced core has a significant influence on conductivity, hole mobility, energy level, and solubility of linear HTMs. M103 and M104 with nonfused oligothiophene cores are superior to other HTMs in terms of conductivity, hole mobility, and surface morphology. PSCs based on M104 exhibited the highest power conversion efficiency of 16.50% under AM 1.5 sun, which is comparable to that of spiro-OMeTAD (16.67%) under the same conditions. Importantly, the employment of M104 is highly economical in terms of the cost of synthesis as compared to that of spiro-OMeTAD. This work demonstrated that nonfused heterocycles, such as oligothiophene, are promising cores for high performance of linear HTMs toward PSCs.

We have retrieved the latitudinal and vertical structures of the 11 year solar cycle modulation on ionospheric electron density using 14 years of satellite‐based radio occultation measurements utilizing the Global Positioning System. The densities at the crests of the equatorial ionization anomaly (EIA) in the subtropics near 300 km in 2003 and 2014 (high solar activity with solar 10.7 cm flux, F10.7≈ 140 solar flux unit (sfu)) were 3 times higher than that in 2009 (low solar activity F10.7≈ 70 sfu). The higher density is attributed to the elevated solar extreme ultraviolet and geomagnetic activity during high solar activity periods. The location of the EIA crests moved ~50 km upward and ~10° poleward, because of the enhanced E× Bforce. The EIA in the northern hemisphere was more pronounced than that in the southern hemisphere. This interhemispheric asymmetry is consistent with the effect of enhanced transequatorial neutral wind. The above observations were reproduced qualitatively by the two benchmark runs of the Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model. In addition, we have studied the impact of the 11 year solar cycle on the 27 day solar cycle response of the ionospheric electron density. Beside the expected modulation on the amplitude of the 27 day solar variation due to the 11 year solar cycle, we find that the altitude of the maximal 27 day solar response is unexpectedly ~50 km higher than that of the 11 year solar response. This is the first time that a vertical dependence of the solar responses on different time scales is reported. The electron densities at the crests of the equatorial ionization anomaly in 2003 and 2014 were 3 times higher than that in 2009The equatorial ionization anomaly moved poleward by ~10° and was more pronounced in the northern hemisphere during 2014The altitude of the maximal 27 day solar response is ~50 km higher than that of the 11 year solar response

Cellular senescence as a result of organismal aging or progeroid diseases leads to stem cell pool exhaustion hindering tissue regeneration and contributing to the progression of age related disorders. Here we discovered that ectopic expression of the pluripotent factor NANOG in senescent or progeroid myogenic progenitors reversed cellular aging and restored completely the ability to generate contractile force. To elicit its effects, NANOG enabled reactivation of the ROCK and Transforming Growth Factor (TGF)‐β pathways—both of which were impaired in senescent cells—leading to ACTIN polymerization, MRTF‐A translocation into the nucleus and serum response factor (SRF)‐dependent myogenic gene expression. Collectively our data reveal that cellular senescence can be reversed and provide a novel strategy to regain the lost function of aged stem cells without reprogramming to the pluripotent state. StemCells2017;35:207–221 NANOG restores the myogenic and contractile capacity of senescent stem cells and progeria derived myofibroblasts. Hair follicle derived Mesenchymal Stem Cells (MSC) were transduced with a tetracycline regulatable vector that carries the NANOG gene. This system allows NANOG expression only when cells are treated with the tetracycline analog, Doxycycline. Cells were serially passaged until they became senescent (late passage, LP MSC). Subsequently Dox was added to the culture medium to induce NANOG expression in LP MSC (LP NANOG MSC) and the myogenic capacity was evaluated and compared to early passage (EP) MSC. Similar experiments were also performed with myofibroblasts derived from patients with an accelerating aging disease (Hutchinson Gilford Progeria Syndrome (HPGS)). (A‐B): Western Blot for ACTA2 and SRF. (C‐D) SRF dependent transcriptional activity (CArG‐box). (E‐F) Immunocytochemistry for ACTA2. (G‐H): Contractile force using 3D collagen microtissue. (I): Schematic illustration describing the effects of NANOG on senescent cells. GM: Growth Medium, DM: Differentiation Medium. Scale bar: 20 μm for immunocytochemistry and 200 μm for the microtissues, data are presented as mean ± standard deviation, n= 3, *: designates statistical significance as compared to LP, LP DM or HGPS, HGPS DM (p< .05), #: designates statistical significance as compared to LP NANOG GM or HGPS NANOG GM (p< .05).

Mid‐tropospheric Carbonyl sulfide (OCS) retrievals from the Tropospheric Emission Spectrometer (TES) are utilized to study OCS distributions during the dry/wet seasons over the Amazon rainforest. TES OCS retrievals reveal positive OCS anomalies (∼16 ppt) over the central and southern parts of the Amazon during August–October (dry season) compared to January–March (wet season). There is less OCS taken up by vegetation and soil and more OCS released from biomass burning during the dry season, which causes an increase in OCS concentrations. Strong sinking air during the dry season also helps to trap OCS and this contributes to positive OCS anomalies. MOZART‐4 model captures positive OCS anomalies over the central and southern regions of the Amazon and negative OCS anomalies over the northern part of the Amazon, which are similar to those from TES mid‐tropospheric OCS retrievals. Our studies can help us better understand OCS variations and photosynthetic activities. As a photosynthetic tracer, OCS can help us better understand photosynthetic activities, the biosphere‐atmosphere interaction, and the carbon sink. There are positive OCS anomalies (∼16 ppt) over the central and southern parts of the Amazon during August–October (dry season), which is related to reduced OCS uptake from vegetation and soil, enhanced OCS emission from biomass burning, and strengthened sinking air. MOZART‐4 is used to simulate the OCS variations during dry/wet seasons. Model results are similar to those from Tropospheric Emission Spectrometer OCS retrievals. However, there are some differences between the spatial distributions of OCS in the MOZART‐4 model and the satellite retrievals. Results in this study can help us better understand the variability of OCS and photosynthetic activities over the Amazon rainforest, which is the biggest rainforest and one of the largest sinks of OCS. Tropospheric Emission Spectrometer OCS concentrations are higher over the central and southern parts of the Amazon during the dry season than the wet seasonHigh OCS concentrations are related to reduced vegetation uptake, enhanced biomass burning, and increased sinking airMOZART‐4 captures the observed positive OCS anomalies over the central and southern Amazon during August–October (dry season) Tropospheric Emission Spectrometer OCS concentrations are higher over the central and southern parts of the Amazon during the dry season than the wet season High OCS concentrations are related to reduced vegetation uptake, enhanced biomass burning, and increased sinking air MOZART‐4 captures the observed positive OCS anomalies over the central and southern Amazon during August–October (dry season)

Borondipyrromethene (BODIPY) dyes are one of the most interesting organic dyes because of their unique characteristic in capturing near-infrared (NIR) solar radiation. However, the highest reported conversion efficiency of BODIPY dyes is still far behind that of other organic dyes. Herein, we demonstrated an efficient strategy for enhancing the photovoltaic performance of BODIPY dyes, i.e., introducing a long linker between the light harvesting antenna and acceptor. Interestingly, the linker length has opposite effects on the BODIPY (M62, M63, M66, and LB1) and triphenylamine (M64 and M65) dyes. This work suggests that the incorporated long linker in BODIPY dyes shows several favorable characteristics: (i) improving the light harvesting capability of BODIPY dyes in longer wavelength without a big change of the HOMO levels; (ii) efficiently increasing the photocurrent and photovoltage, leading to dramatically improved performance; (iii) significantly reducing the charge recombination between electrons in TiO2and electrolyte acceptor species and oxidized dye molecules at the interface. As a result, M63 with a binary linker display a 4.79 times higher conversion efficiency compared to that of M62 with a single linker. This finding could contribute to molecular engineering in the design of highly efficient BODIPY dyes.

Fused-ring thiophene compounds emerged as an important type of building blocks for organic dyes toward the dye-sensitized solar cells (DSSCs) because of their good charge transfer and light-harvesting properties. Nevertheless, some fused-ring thiophenes have a lack of desired alkyl chains or side alkyl chains, which may induce a severe charge recombination in devices. In this work, the hex-1-en-1-ylbenzene (HEYB) unit was introduced in two new fused-ring thiophene organic dyes (M60 and M59), resulting in a modest dihedral angle (∼36°) between the donor and spacer in dyes. The effect of the HEYB unit on optical, electrochemical, and photovoltaic properties has been investigated by comparing with their congeners (M42 and M58) without the HEYB unit. It is found that introduction of the HEYB unit in arylamine donor enhanced the driving force for dye regeneration and beneficial for suppressing dye aggregation as well as reducing the charge recombination. Device performance characteristics demonstrate that introduction of the HEYB unit in the arylamine donor is a feasible strategy toward enhancing the performance of fused-ring thiophene organic dyes. Benefiting from this strategy, a dye-sensitized solar cell employing the M60 photosensitizer and a cobalt electrolyte exhibits a good power conversion efficiency of 9.75% measured under the 100 mW cm–2, simulated AM1.5 sunlight.

Every year, several typhoons originating from the West Pacific come close to Taiwan, modulating the regional weather through intense rainfall and enhanced humidity. The isotopic ratios (δ18O and δD) in the typhoon vapor evolve along its track due to rainout, recycling, and replenishment. In 2016, this signature was recorded in Taipei as typhoon vapors invaded the local atmosphere. After typhoon disintegration, the isotope ratios of the local atmosphere slowly return to the background value. The fall and rise in the ratios give rise to a V‐shaped variation. The processes controlling the fall (like moisture turnover, typhoon speed, wind speed, and direction) are fast (1–2 days). In contrast, the recovery is slow (several days) depending on the replacement rate of the local atmospheric moisture by incoming oceanic vapor. An isotope evolution model based on Rayleigh condensation and a box model of moisture mixing in the recovery phase are proposed and employed to explain the V‐shape. The combination of these two models for four major typhoons (Nepartak, Megi, Meranti, and Malakas) shows close agreement with observations. The evolution model suggests that the precipitation efficiency, PE (rainfall/overhead moisture), and typhoon size are two important parameters controlling the decrease in ratio. The characteristic turnover time of typhoon moisture (inverse of PE, obtained from European Centre for Medium‐Range Weather Forecasts fifth Re‐Analysis data) is estimated to be ∼2 days for a Pacific typhoon of 500 km radius. Our isotope study provides important constraints on the moisture budget of Pacific typhoons. Tropical typhoons transport heat and moisture from the ocean surface to the atmosphere at fast rates. To understand the moisture input and output during the typhoon evolution, stable oxygen and hydrogen isotope tracers in the vapor have been continuously measured at a station in Taipei, Taiwan. Four major typhoons originating in the western North Pacific in 2016 passed near the Taiwan region. The heavy‐to‐light isotope ratios of typhoon moisture that reached Taipei were analyzed. The isotope ratios of moisture changed with time due to rainout‐related fractionation processes and subsequent mixing with atmospheric vapor producing a V‐shaped pattern as the typhoon moved and disintegrated. An idealized model is presented to show how a Rayleigh fractionation operates through step‐wise rainout from existing vapor mass that is supplemented by a continuous import of moisture by low‐level inflow and ocean evaporation. The recovery of the isotope ratios to pre‐typhoon values takes place by slow mixing of the incoming oceanic vapor with the existing atmospheric vapor over the station. Vapors from tropical typhoons approaching the Taiwan region in 2016 have been tracked by continuous monitoring of stable isotope ratiosModeling of vapor isotope variation provides insight into typhoon's moisture recycling and fresh contribution from neighboring regionsRainfall/total precipitable water vapor or precipitation efficiency provides a key concept to model the vapor isotope evolution Vapors from tropical typhoons approaching the Taiwan region in 2016 have been tracked by continuous monitoring of stable isotope ratios Modeling of vapor isotope variation provides insight into typhoon's moisture recycling and fresh contribution from neighboring regions Rainfall/total precipitable water vapor or precipitation efficiency provides a key concept to model the vapor isotope evolution

Kinetics of the recombination at TiO2/dye/electrolyte interfaces is vital to establish reliable strategy for reducing energy loss in dye sensitized solar cell (DSCs). The semilogarithmic plots of open circuit voltage–light intensity indicate that the DSCs exhibit different recombination behaviors in high and low voltage regions. Even so, the average orders of recombination reaction in the two regions are both found to be expressed as the summation of the apparent charge transfer coefficient and the averaged density distribution parameter. This statement is based upon the fact that the “steady-state” electron lifetimes in cobalt complex based DSCs are well interpreted by using the Butler–Volmer model. Combining the results of electron lifetime, the order of recombination reaction, and density distribution, we addressed that the dominant pathway of recombination in cobalt complex based DSCs is via the trapping states rather than the conduction band. In addition, the variation of the Fermi level in TiO2film could affect the adsorbing configurations of 4-tert-butylpyridine molecules and Li+/H+cations at TiO2surfaces and hence engenders the nonexponential distribution of electron density at higher Fermi level.

With respect to the electron-withdrawing acceptors of D–A−π–A organic dyes, reports on the second electron-donating donors for D–D−π–A organic dyes are very limited. Both of the dyes have attracted significant attention in the field of dye-sensitized solar cells (DSCs). In this work, four new D–D−π–A organic dyes with dithieno[3,2-b:2′,3′-d]pyrrole (DTP) or bis(amine) donor have been designed and synthesized for a investigation of the influence of the terminal electron donor in D–D−π–A organic dye-sensitized solar cells. It is found that DTP is a promising building block as the terminal electron donor when introduced in the dithiophenepyrrole direction, but not just a good bridge, which exhibits several characteristics: (i) efficiently increasing the maximum molar absorption coefficient and extending the absorption bands; (ii) showing stronger charge transfer interaction as compared with the pyrrole direction; (iii) beneficial to photocurrent generation of DSCs employing cobalt electrolytes. DSCs based on M45 with the Co-phen electrolyte exhibit good light-to-electric energy conversion efficiencies as high as 9.02%, with a short circuit current density (JSC) of 15.3 mA cm–2, open circuit voltage (VOC) of 867 mV and fill factor (FF) of 0.68 under AM 1.5 illumination (100 mW cm–2). The results demonstrate that N,S-heterocycles such as DTP unit could be promising candidates for application in highly efficient DSCs employing cobalt electrolyte.

We examined the effects of senescence on the proliferation and leiomyogenic differentiation potential of mesenchymal stem cells (MSCs) isolated from bone marrow (BM-MSCs) or hair follicles (HF-MSCs). To this end, we compared ovine HF-MSCs and BM-MSCs in terms of their proliferation and differentiation potential to the smooth muscle cell lineage. We discovered that HF-MSCs are less susceptible to culture senescence compared with BM-MSCs. We hypothesized that application of mechanical forces may enhance the contractility and mechanical properties of vascular constructs prepared from senescent MSCs. Interestingly, HF-MSCs and BM-MSCs responded differently to changes in the mechanical microenvironment, suggesting that despite phenotypic similarities, MSCs from different anatomic locations may activate different pathways in response to the same microenvironmental factors. In turn, this may also suggest that cell-based tissue regeneration approaches may need to be tailored to the stem cell origin, donor age, and culture time for optimal results.

Abstract: The geogenic source of arsenic (As) in groundwater is an indisputable fact. Arsenic contamination in the shallow groundwater of West Bengal is an alarming health issue with progressive growth of regional population and demand for water. The As contamination in shallow groundwater is facilitated by microbial activities, which depend on the inflow of dissolved organic carbon (DOC), providing a temporary reducing condition conducive to the release of As from aquifer sediments. Here, we present a documentation over several years of seasonal observations on dissolved total As contents and stable isotope ratios in shallow groundwater, ‘deep pond water’ (collected from the deepest part of the pond just above the sediment–water interface), river water and rainwater from the Chakdaha region, Haringhata block, Nadia district, West Bengal. The current study shows, for the first time, a large similarity in the isotopic composition of seasonal deep pond water with the shallow aquifer-intercalated clay sediment-trapped pore water (data adopted from the literature on a Bangladesh region). We highlight the possible processes wherein seasonal eutrophication during dry time followed by monsoon time flooding and sedimentation allows the burial of organic-rich clayey sediments with trapped DOC-rich pore water, which serve as a source of clay-pocket pore water. The isotopic composition of clay-pore water formed at a historical time scale resembles the deep-bottom water composition of surface water bodies and provides an ideal composition responsible for triggering the seasonal release of As into the shallow groundwater. The processes such as excess withdrawal of groundwater during dry periods and consequent squeezing of aquifer sediment-intercalated clay-lenses can expel its organic-rich contents to trigger anaerobic microbial activities and As release into the adjoining water. Using D-excess and δ18O as conservative tracers, we have shown that ~13–14% mixing (exclusion) of clay-pore water to the adjoining As-uncontaminated (≤10 µg/L) shallow regional groundwater is sufficient to cause high As (>10 µg/L) mobilisation. Research highlights:

Shallow groundwater samples (&lt;60 m bgl) collected at seasonal time intervals (from Nadia) show increasing dissolved total arsenic (As) contents during dry pre-monsoon periods, featuring mixing of aquifer-intercalated clay-lens-trapped pore water with the adjoining groundwater.

Excessive groundwater withdrawal during dry periods generates compaction of the intercalated clay-lenses placed within the shallow aquifer and actuates the process of clay-pore water expulsion which causes land subsidence.

An estimation of ~13–14% mixing (exclusion) of aquifer-intercalated clay-pore water (high As, organic-rich) to the adjoining As-uncontaminated (≤10 µg/L) regional shallow groundwater is sufficient to trigger high As mobilisation.

Aquifer-intercalated clay-pore water is equivalent to ‘relic surface water’, making the presence of palaeo-water of quaternary time scales.