Biodiesel(fatty acid alkyl esters),an alternate to fossil fuel,has the tendency of autoxidation and hence requires antioxidants for long term storage.The influence of synthetic and natural antioxidants on the oxidativ...Biodiesel(fatty acid alkyl esters),an alternate to fossil fuel,has the tendency of autoxidation and hence requires antioxidants for long term storage.The influence of synthetic and natural antioxidants on the oxidative stability was analysed for fresh FAMEs(fatty acid methyl esters)obtained from hevea brasiliensis at 140 C.Higher activity was observed for synthetic antioxidants following the order of GA】BHT】DTBP】Q】GT-M】PH-M】GT-C,whereas the oxidative stability of stored FAMEs samples measured at 110 C reveals a nearly inverse trend.Storage stability was tested for the FAMEs obtained from hevea brasiliensis stored at 30 C,after addition of synthetic and natural antioxidants—butylated hydroxytoluene(BHT),2,6-di-tert-butylphenol(DTBP),quercetin(Q),gallic acid(GA),methanol extracts from green tea(GTM),pomegranate hull(PH-M),and chloroform extract of green tea(GT-C).Antioxidant activities above 1500 ppm was in the order of DTBP】BHT】GA】GT-C】GT-M】Q】PH-M.Synthetic antioxidants have been found more efficient to improve the storage stability of FAMEs obtained from hevea brasiliensis.DTBP in particular has the highest protection factor.展开更多
A specialty database has been established at The Hong Kong University of Science and Technology to handle the chemical and biological data of medicinal plants and other natural products from scientific literatures. De...A specialty database has been established at The Hong Kong University of Science and Technology to handle the chemical and biological data of medicinal plants and other natural products from scientific literatures. Designed as a relational system capable of analyzing, comparing, and correlating data, the system can retrieve information in assimilated tabular formats. The database can provide information supports to researchers in the fields of medicinal chemistry, biochemistry, pharmacology, botany and other disciplines of natural products research.展开更多
Tandem device architectures offer a route to greatly increase the maximum possible power conversion efficiencies(PCEs)of polymer solar cells,however,the complexity of tandem cell device fabrication(such as selecting b...Tandem device architectures offer a route to greatly increase the maximum possible power conversion efficiencies(PCEs)of polymer solar cells,however,the complexity of tandem cell device fabrication(such as selecting bandgaps of the front and back cells,current matching,thickness,and recombination layer optimization)often result in lower PCEs than are observed in single-junction devices.In this study,we analyze the influence of front cell and back cell bandgaps and use transfer matrix modeling to rationally design and optimize effective tandem solar cell structures before actual device fabrication.Our approach allows us to estimate tandem device parameters based on known absorption coefficients and open-circuit voltages of different active layer materials and design devices without wasting valuable time and materials.Using this approach,we have investigated a series of wide bandgap,high voltage photovoltaic polymers as front cells in tandem devices with PTB7-Th as a back cell.In this way,we have been able to demonstrate tandem devices with PCE of up to 12.8%with minimal consumption of valuable photoactive materials in tandem device optimization.This value represents one of the highest PCE values to date for fullerene-based tandem solar cells.展开更多
A novel isopolyanion salt [(CH 3Py) 2H] 2W 6O 19 was synthesized by the reaction of a white powdery tungstic acid (WPTA) with p methylpyridine, and characterized by elemental analyses, infrared spectrometry and X ray ...A novel isopolyanion salt [(CH 3Py) 2H] 2W 6O 19 was synthesized by the reaction of a white powdery tungstic acid (WPTA) with p methylpyridine, and characterized by elemental analyses, infrared spectrometry and X ray diffraction methods. In the crystal structure of the title compound there are a hexatungstate anion and two unique [(CH 3Py) 2H] + dimeric cations, and the most specific aspect of its structure is the first reported hydrogen bond existing between two of the p methylpyridine molecules with a N_N distance of 0.267 3 nm. This hydrogen bond is analogous to that between the water molecules in H 5O 2 +, but is rather weaker.展开更多
Photoinduced electron transfer reaction between the excited state ruthenium (II) polypyridyl complexes and quinones has been investigated in cetyltrimethylammonium bromide using luminescent quenching techniques. The c...Photoinduced electron transfer reaction between the excited state ruthenium (II) polypyridyl complexes and quinones has been investigated in cetyltrimethylammonium bromide using luminescent quenching techniques. The complexes have the absorption and emission maximum in the range 452 - 468 nm and 594 - 617 nm respectively. The static nature of quenching is confirmed from the ground state absorption studies. The association constants for the complexes with quinones are calculated from the Benesi-Hildebrand plots using absorption spectral data. The value of quenching rate constant (kq) is highly sensitive to the nature of the ligand and the quencher, the medium, structure and size of the quenchers. Compared to the aqueous medium, the electron transfer rate is altered in CTAB medium. The oxidative nature of the quenching is confirmed by the formation of Ru3+ ion and quinone anion radical.展开更多
In the present study, the authors attempted to shed a light on the possible relationships between lipid per oxidation markers, serum malondialdehyde （MDA） with the effect of mercury exposure using serum samples obta...In the present study, the authors attempted to shed a light on the possible relationships between lipid per oxidation markers, serum malondialdehyde （MDA） with the effect of mercury exposure using serum samples obtained from 100 mercury exposed dentals due to their occupation. These dentals were divided into two groups according to their occupational period. The third group consists of healthy volunteers that were working outside the mercury factories as a control group. The present results showed that mercury levels increased with the increasing of their occupation period. The highest level was 5.7 μg/dl, compared to the control group which was 0.1 μg/dl., The level of MDA was elevated in the workers and the highest level was found to be 41.00 nmol/dL for workers with longest period compared to the control group 8.6 nmol/dL. Some serum antioxidants such as vitamin A, E and albumin were evaluated and were found to be lower in all workers compared to the control group. The present results showed that Mg levels increased with the increasing of their occupation period and were found to be lower in Zn, Se of all workers compared to the control group.展开更多
The present study aims at measuring the activity concentrations of ^210Po and ^210Pb in the potable water of Eloor, a major industrial belt in the Ernakulam district of Kerala, India with an aim of evaluating resultan...The present study aims at measuring the activity concentrations of ^210Po and ^210Pb in the potable water of Eloor, a major industrial belt in the Ernakulam district of Kerala, India with an aim of evaluating resultant ingestion dose to critical population. The industrial units located in Eloor discharge their treated effluents into the river Periyar and the surrounding environs. The two major industries of interest with respect to NORMs are the fertilizer plant, processing rock phosphate and the monazite processing plant, which had been in operation for the last 50 years. For sampling, Eloor region was divided into four zones and a total of 55 water samples from different locations were collected and analysed as per standard analytical procedure manual of BARC. The ^210Po concentration ranged between 0.3 to 4.7 mBq.L^-1 and ^210Pb ranged from 0.6 to 4.3 mBq.L^-1. All values are well below the limit of 0.1 Bq.Ll recommended by World Health Organization. Statistical analysis shows a good co-relation between ^210Po and ^210Pb in the water samples analyzed and the mean activity concentration is found to be relatively high in the western region of Eloor compared to other regions. The annual effective dose equivalent to man from ^210Po and ^210Pb through drinking water intake were estimated and found to be 1.13 μSv.y^-1 and 0.99 μSv.y^-1 respectively, which is well below the reference level of committed effective dose （100 μSv.y^-1） recommended by WHO.展开更多
Molecular rotor-based fluorophores(RBFs)activate fluorescence upon increase of micro-viscosity,thus bearing a broad application promise in many fields.However,it remains a challenge to control how fluorescence of RBFs...Molecular rotor-based fluorophores(RBFs)activate fluorescence upon increase of micro-viscosity,thus bearing a broad application promise in many fields.However,it remains a challenge to control how fluorescence of RBFs responds to viscosity changes.Herein,we demonstrate that the formation and regulation of intramolecular hydrogen bonds in the excited state of RBFs could modulate their rotational barrier,leading to a rational control of how their fluorescence can be activated by micro-viscosity.Based on this strategy,a series of RBFs were developed based on 4-hydroxybenzylidene-imidazolinone(HBI)that span a wide range of viscosity sensitivity.Combined with the AggTag method that we previously reported,the varying viscosity sensitivity and emission spectra of these probes enabled a dualcolor imaging strategy that detects both protein oligomers and aggregates during the multistep aggregation process of proteins in live cells.In summary,our work indicates that installing intracellular excited state hydrogen bonds to RBFs allows for a rational control of rotational barrier,thus allow for a fine tune of their viscosity sensitivity.Beyond RBFs,we envision similar strategies can be applied to control the fluorogenic behavior of a large group of fluorophores whose emission is dependent on excited state rotational motion,including aggregation-induced emission fluorophores.展开更多
Colorectal cancer(CRC)is one of the most common cancers.Patients with advanced CRC can only rely on chemotherapy to improve outcomes.However,primary drug resistance frequently occurs and is difficult to predict.Change...Colorectal cancer(CRC)is one of the most common cancers.Patients with advanced CRC can only rely on chemotherapy to improve outcomes.However,primary drug resistance frequently occurs and is difficult to predict.Changes in plasma protein composition have shown potential in clinical diagnosis.Thus,it is urgent to identify potential protein biomarkers for primary resistance to chemotherapy for patients with CRC.Automatic sample preparation and high-throughput analysis were used to explore potential plasma protein biomarkers.Drug susceptibility testing of circulating tumor cells(CTCs)has been investigated,and the relationship between their values and protein expressions has been discussed.In addition,the differential proteins in different chemotherapy outcomes have been analyzed.Finally,the potential biomarkers have been detected via enzyme-linked immunosorbent assay(ELISA).Plasma proteome of 60 CRC patients were profiled.The correlation between plasma protein levels and the results of drug susceptibility testing of CTCs was performed,and 85 proteins showed a significant positive or negative correlation with chemotherapy resistance.Forty-four CRC patients were then divided into three groups according to their chemotherapy outcomes(objective response,stable disease,and progressive disease),and 37 differential proteins were found to be related to chemotherapy resistance.The overlapping proteins were further investigated in an additional group of 79 patients using ELISA.Protein levels of F5 and PROZ significantly increased in the progressive disease group compared to other outcome groups.Our study indicated that F5 and PROZ proteins could represent potential biomarkers of resistance to chemotherapy in advanced CRC patients.展开更多
Comprehensive Summary The first catalytic asymmetric total synthesis of(+)-propolisbenzofuran B,enabled by a highly enantioselective rhodium-catalyzed hydrogenation of a tetrasubstituted olefin,was described.Other not...Comprehensive Summary The first catalytic asymmetric total synthesis of(+)-propolisbenzofuran B,enabled by a highly enantioselective rhodium-catalyzed hydrogenation of a tetrasubstituted olefin,was described.Other noteworthy aspects include the construction of the central hydrodibenzo[b,d]furan core through a sequence of Zn(II)-mediated regioselective benzofuran formation and Dieckmann condensation,as well as C-H oxidations,involving a visible light-induced Fe(III)-catalyzed benzylic C(sp3)-H oxidation.Additionally,the absolute configuration was confirmed by X-ray analysis of a carbonate intermediate.展开更多
We proposed a facile and rapid method for preparing silica-silver core-shell（SSCS） substrates to use Ag electroless plating on SiO2@Au-seed particles.UV-Vis-NIR absorption spectrometer and SEM were employed to monit...We proposed a facile and rapid method for preparing silica-silver core-shell（SSCS） substrates to use Ag electroless plating on SiO2@Au-seed particles.UV-Vis-NIR absorption spectrometer and SEM were employed to monitor the reaction process of the formation of Ag on the surfaces of silica beads,and the optical resonance of the substrate could shift from visible to NIR region.It has been found that surface-enhanced Raman scattering（SERS） enhancement changes with the electroless plating time and the SSCS substrate with the plating time of 90 s（90SSCS） shows the strongest SERS response under the laser excitation at 514.5 nm.Signals collected over multiple spots and substrate of rhodamine 6G（R6G） resulted in a relative standard deviation（RSD） of 9.75%.The calculated enhancement factor（EF） was approximately 105 ＂106.SSCS substrate exhibits high SERS performance,which is due to electromagnetic SERS enhancement with additional localization field within closely packed Ag nanoparticles decorated on the SiO2 nanoparticles.And this substrate presents tunable and broad localized surface plasmon resonance（LSPR）,so this method may open a new way for SERS studies with other laser excitation.展开更多
Various Er modified MnO_(x) catalysts were synthesized using co-precipitation approach and tested in the selective catalytic reduction of NO_(x) by ammonia(NH_(3)-SCR).Catalysts were analyzed with various characteriza...Various Er modified MnO_(x) catalysts were synthesized using co-precipitation approach and tested in the selective catalytic reduction of NO_(x) by ammonia(NH_(3)-SCR).Catalysts were analyzed with various characterization techniques,and it is found that the doping of Er can enormously enhance the catalytic performance of MnO_(x)catalyst.MnEr_(0.1)demonstrates advantageous catalytic performance in the NH_(3)-SCR reaction owing to rich surface acidic sites,high surface content of Mn^(4+),superior redox capacity,and enhanced surface-adsorbed oxygen.From diffuse reflectance infrared Fourier transform spectroscopy(DRIFTs)analysis,it is suggested that the MnEr0.1catalyst follows mainly Eley-Rideal mechanism while MnO_(x) is dominated by Langmuir-Hinshelwood mechanism.展开更多
The single-pot production of Pd@Pt core-shell structures is a promising approach as it offers large surface area,catalytic capability,and stability.In this work,we established a single-pot process to produce Pd@Pt cor...The single-pot production of Pd@Pt core-shell structures is a promising approach as it offers large surface area,catalytic capability,and stability.In this work,we established a single-pot process to produce Pd@Pt core-shell nanodendrites with tunable composition,shape and size for optimal electrochemical activity.Pd@Pt nanodendrites with diverse compositions were synthesized by tuning the ratios of Pd and Pt sources in an aqueous environment using cetyltrimethylammonium chloride,which functioned as both the surfactant and the reducing agent at an elevated temperature(90°C).The synthesized Pd5@Pt5 nanodendrites showed exceptional electrochemical action toward the methanol oxidation reaction related with another compositional Pd@Pt nanodendrites and conventional Pt/C electrocatalysts.In addition,Pd5@Pt5 nanodendrites exhibited good CO tolerance owing to their surface features and the synergistic effect among Pt and Pd.Meanwhile,nanodendrites with a Pt-rich surface provided exceptional catalytic active sites.Compared with the conventional Pt/C electrocatalyst,the anodic peak current obtained by Pd5@Pt5 nanodendrites was 3.74 and 2.18 times higher in relations of mass and electrochemical active surface area-normalized current density,respectively.This approach offers an attractive strategy to design electrocatalysts with unique structures and outstanding catalytic performance and stability for electrochemical energy conversion.展开更多
We demonstrate that a bulky cyclic amino ligand,specifically 1,1,3,3-tetraphenylisoindolinyl,can facilitate the formation of a transient stannyne,endowed with adjacent ambiphilic carbon and tin centers.This stannyne,m...We demonstrate that a bulky cyclic amino ligand,specifically 1,1,3,3-tetraphenylisoindolinyl,can facilitate the formation of a transient stannyne,endowed with adjacent ambiphilic carbon and tin centers.This stannyne,manifesting carbene-like behavior,engages in an unprecedented sequence of reactions,including Buchner ring expansion,[1,3]sigmatropic,and[1,5]-sigmatropic shifts,culminating in the synthesis of a stable cyclic(alkyl)(amino)stannylene.This compound represents the first tin analogue of the well-known cyclic(alkyl)(amino)carbenes.Both the bonding configuration and the formation process of this stannylene are thoroughly analyzed through quantum chemical computations.Our findings pave the way for further synthesis of unusual main group species using bulky isoindolinyl substituents,emphasizing their potential as a versatile tool in synthetic chemistry.展开更多
Transcription factors constitute numerous signal transduction networks and play a central role in gene expression regulation. Recent studies have shown that a limited portion of transcription factors are anchored in t...Transcription factors constitute numerous signal transduction networks and play a central role in gene expression regulation. Recent studies have shown that a limited portion of transcription factors are anchored in the cellular membrane, storing as dormant forms. Upon exposure to environmental and developmental cues, these transcription factors are released from the membrane and translocated to the nucleus, where they regulate associated target genes. As this process skips both transcriptional and translational regulations, it guarantees prompt response to external and internal signals. Membrane- bound transcription factors （MTFs） undergo several unique steps that are not involved in the action of canonical nuclear transcription factors： proteolytic processing and intracellular movement. Recently, alternative splicing has also emerged as a mechanism to liberate MTFs from the cellular membranes, establishing an additional activation scheme independent of proteolytic processing. Multiple layers of MTF regulation add complexity to transcriptional regulatory scheme and ensure elaborate action of MTFs. In this review, we provide an overview of recent findings on MTFs in plants and highlight the molecular mechanisms underlying MTF liberation from cellular membranes with an emphasis on intracellular movement.展开更多
Lanthanide complexes of Eu（III）, Gd（III）, Nd（III）, Sm（III）, and Tb（III） with phenylthioacetic acid were synthesized and characterized by elemental analysis, mass, infrared radiation （IR）, electronic spectr...Lanthanide complexes of Eu（III）, Gd（III）, Nd（III）, Sm（III）, and Tb（III） with phenylthioacetic acid were synthesized and characterized by elemental analysis, mass, infrared radiation （IR）, electronic spectra, molar conductance, thermogravimetric analysis （TGA）, and powder X-ray diffraction （XRD）. The results showed that the lanthanide complexes were homodinuclear in nature. The two lanthanide ions were bridged by eight oxygen atoms from four carboxylate groups. Thermal decomposition profiles were consis- tent with the proposed formulations. Powder XRD studies showed that all the complexes were amorphous in nature. Antimicrobial studies indicated that these complexes exhibited more activity than the ligand itself. The DNA cleavage activity of the ligand and its complexes were assayed on CT DNA using gel electrophoresis in the presence of H202. The result showed that the Eu（Ⅲ） and Nd（Ⅲ） complexes completely cleaved the DNA. The anticancer activities of the complexes were also studied towards human cervical cancer cell line （HeLa） and colon cancer cells （HCT116） and it was found that the Eu（Ⅲ） and Nd（Ⅲ） complexes were more active than the corresponding Gd（Ⅲ）, Sm（Ⅲ）, Tb（Ⅲ） complexes and the free ligand on both the cancer cells.展开更多
Diels-Alder reaction is one of the most important reactions in organic synthesis and has witnessed great achievements in total syntheses of complex natural products.In this review,we will focus on the [4+2] cycloaddit...Diels-Alder reaction is one of the most important reactions in organic synthesis and has witnessed great achievements in total syntheses of complex natural products.In this review,we will focus on the [4+2] cycloaddition that utilizes 2-pyrone as the diene component.Major advances of its applications in the total syntheses of natural products in the past fifty years will be discussed here.展开更多
Protein protected gold nanoclusters have outstanding physical and chemical properties that make them excellent scaffolds for the construction of novel chemical and biological probes. In this study, a simple one-pot sy...Protein protected gold nanoclusters have outstanding physical and chemical properties that make them excellent scaffolds for the construction of novel chemical and biological probes. In this study, a simple one-pot synthesis method was proposed for the preparation of fluorescent probes based on ovalbumin-stabilized gold nanoclusters. This strategy allowed the generation of water-soluble gold nanoclusters within 5 min. The as-prepared fluorescent probe exhibited a red fluorescence emission at 625 nm, and good thermostability. The fluorescent probe was applied to measure glucose concentrations based on the hydrogen peroxide-induced fluorescence quenching principle, and showed favorable biocompatibility, high sensitivity and good selectivity. As a result of the advantageous properties and performance of this fluorescent probe, the present assay allowed for the selective determination of glucose in the range of 5.0×10-6 to 10.0×10-3 mol/L with a detection limit of 1.0×10?6 mol/L. Moreover, the glucose content in urinary samples was analyzed using the constructed fluorescent probe: this indicated the potential of the fluorescent gold nanoclusters for applications in biological and clinical diagnosis and therapy.展开更多
The demand for new catalysts for renewable energy production has become crucial.As an alternative to metal catalysts for electrocatalysis to produce energy sources,metal-phthalocyanine(MPc)electrocatalysts have shown ...The demand for new catalysts for renewable energy production has become crucial.As an alternative to metal catalysts for electrocatalysis to produce energy sources,metal-phthalocyanine(MPc)electrocatalysts have shown potential.Their physicochemical and electrochemical properties depend on the chemical structure of the MPc and the central metal atom.Recent reviews of MPcs focused on their electrochemical performance in specific catalytic reactions,such as oxygen reduction reaction and CO_(2)reduction reaction.However,understanding the structure of MPcs in depth is important,since their electrochemical catalytic activity is affected by structural modifications of MPcs.Therefore,this minireview focuses on how the molecular structure of MPcs affects electrochemical catalysis.展开更多
文摘Biodiesel(fatty acid alkyl esters),an alternate to fossil fuel,has the tendency of autoxidation and hence requires antioxidants for long term storage.The influence of synthetic and natural antioxidants on the oxidative stability was analysed for fresh FAMEs(fatty acid methyl esters)obtained from hevea brasiliensis at 140 C.Higher activity was observed for synthetic antioxidants following the order of GA】BHT】DTBP】Q】GT-M】PH-M】GT-C,whereas the oxidative stability of stored FAMEs samples measured at 110 C reveals a nearly inverse trend.Storage stability was tested for the FAMEs obtained from hevea brasiliensis stored at 30 C,after addition of synthetic and natural antioxidants—butylated hydroxytoluene(BHT),2,6-di-tert-butylphenol(DTBP),quercetin(Q),gallic acid(GA),methanol extracts from green tea(GTM),pomegranate hull(PH-M),and chloroform extract of green tea(GT-C).Antioxidant activities above 1500 ppm was in the order of DTBP】BHT】GA】GT-C】GT-M】Q】PH-M.Synthetic antioxidants have been found more efficient to improve the storage stability of FAMEs obtained from hevea brasiliensis.DTBP in particular has the highest protection factor.
文摘A specialty database has been established at The Hong Kong University of Science and Technology to handle the chemical and biological data of medicinal plants and other natural products from scientific literatures. Designed as a relational system capable of analyzing, comparing, and correlating data, the system can retrieve information in assimilated tabular formats. The database can provide information supports to researchers in the fields of medicinal chemistry, biochemistry, pharmacology, botany and other disciplines of natural products research.
基金This study was supported by the National Research Foundation of Korea(2017R1C1B1010627)the New and Renewable Energy Program of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korea Government Ministry of Trade,Industry and Energy(MTIE)(20163030013900,20183010013900)This study was supported by the Technology Development Program to solve climate changes of the National Research Foundation(NRF)funded by theMinistry of Science,ICT and Future Planning(NRF-2015M1A2A2057506,2019M1A2A2065614).
文摘Tandem device architectures offer a route to greatly increase the maximum possible power conversion efficiencies(PCEs)of polymer solar cells,however,the complexity of tandem cell device fabrication(such as selecting bandgaps of the front and back cells,current matching,thickness,and recombination layer optimization)often result in lower PCEs than are observed in single-junction devices.In this study,we analyze the influence of front cell and back cell bandgaps and use transfer matrix modeling to rationally design and optimize effective tandem solar cell structures before actual device fabrication.Our approach allows us to estimate tandem device parameters based on known absorption coefficients and open-circuit voltages of different active layer materials and design devices without wasting valuable time and materials.Using this approach,we have investigated a series of wide bandgap,high voltage photovoltaic polymers as front cells in tandem devices with PTB7-Th as a back cell.In this way,we have been able to demonstrate tandem devices with PCE of up to 12.8%with minimal consumption of valuable photoactive materials in tandem device optimization.This value represents one of the highest PCE values to date for fullerene-based tandem solar cells.
文摘A novel isopolyanion salt [(CH 3Py) 2H] 2W 6O 19 was synthesized by the reaction of a white powdery tungstic acid (WPTA) with p methylpyridine, and characterized by elemental analyses, infrared spectrometry and X ray diffraction methods. In the crystal structure of the title compound there are a hexatungstate anion and two unique [(CH 3Py) 2H] + dimeric cations, and the most specific aspect of its structure is the first reported hydrogen bond existing between two of the p methylpyridine molecules with a N_N distance of 0.267 3 nm. This hydrogen bond is analogous to that between the water molecules in H 5O 2 +, but is rather weaker.
文摘Photoinduced electron transfer reaction between the excited state ruthenium (II) polypyridyl complexes and quinones has been investigated in cetyltrimethylammonium bromide using luminescent quenching techniques. The complexes have the absorption and emission maximum in the range 452 - 468 nm and 594 - 617 nm respectively. The static nature of quenching is confirmed from the ground state absorption studies. The association constants for the complexes with quinones are calculated from the Benesi-Hildebrand plots using absorption spectral data. The value of quenching rate constant (kq) is highly sensitive to the nature of the ligand and the quencher, the medium, structure and size of the quenchers. Compared to the aqueous medium, the electron transfer rate is altered in CTAB medium. The oxidative nature of the quenching is confirmed by the formation of Ru3+ ion and quinone anion radical.
文摘In the present study, the authors attempted to shed a light on the possible relationships between lipid per oxidation markers, serum malondialdehyde （MDA） with the effect of mercury exposure using serum samples obtained from 100 mercury exposed dentals due to their occupation. These dentals were divided into two groups according to their occupational period. The third group consists of healthy volunteers that were working outside the mercury factories as a control group. The present results showed that mercury levels increased with the increasing of their occupation period. The highest level was 5.7 μg/dl, compared to the control group which was 0.1 μg/dl., The level of MDA was elevated in the workers and the highest level was found to be 41.00 nmol/dL for workers with longest period compared to the control group 8.6 nmol/dL. Some serum antioxidants such as vitamin A, E and albumin were evaluated and were found to be lower in all workers compared to the control group. The present results showed that Mg levels increased with the increasing of their occupation period and were found to be lower in Zn, Se of all workers compared to the control group.
文摘The present study aims at measuring the activity concentrations of ^210Po and ^210Pb in the potable water of Eloor, a major industrial belt in the Ernakulam district of Kerala, India with an aim of evaluating resultant ingestion dose to critical population. The industrial units located in Eloor discharge their treated effluents into the river Periyar and the surrounding environs. The two major industries of interest with respect to NORMs are the fertilizer plant, processing rock phosphate and the monazite processing plant, which had been in operation for the last 50 years. For sampling, Eloor region was divided into four zones and a total of 55 water samples from different locations were collected and analysed as per standard analytical procedure manual of BARC. The ^210Po concentration ranged between 0.3 to 4.7 mBq.L^-1 and ^210Pb ranged from 0.6 to 4.3 mBq.L^-1. All values are well below the limit of 0.1 Bq.Ll recommended by World Health Organization. Statistical analysis shows a good co-relation between ^210Po and ^210Pb in the water samples analyzed and the mean activity concentration is found to be relatively high in the western region of Eloor compared to other regions. The annual effective dose equivalent to man from ^210Po and ^210Pb through drinking water intake were estimated and found to be 1.13 μSv.y^-1 and 0.99 μSv.y^-1 respectively, which is well below the reference level of committed effective dose （100 μSv.y^-1） recommended by WHO.
基金Research Center for Industries of the Future(RCIF),Westlake UniversityNational Natural Science Foundation of China„Grant/Award Numbers:22007048,22222410Natural Science Foundation of Jiangsu Basic Research Program„Grant/Award Number:BK20221324。
文摘Molecular rotor-based fluorophores(RBFs)activate fluorescence upon increase of micro-viscosity,thus bearing a broad application promise in many fields.However,it remains a challenge to control how fluorescence of RBFs responds to viscosity changes.Herein,we demonstrate that the formation and regulation of intramolecular hydrogen bonds in the excited state of RBFs could modulate their rotational barrier,leading to a rational control of how their fluorescence can be activated by micro-viscosity.Based on this strategy,a series of RBFs were developed based on 4-hydroxybenzylidene-imidazolinone(HBI)that span a wide range of viscosity sensitivity.Combined with the AggTag method that we previously reported,the varying viscosity sensitivity and emission spectra of these probes enabled a dualcolor imaging strategy that detects both protein oligomers and aggregates during the multistep aggregation process of proteins in live cells.In summary,our work indicates that installing intracellular excited state hydrogen bonds to RBFs allows for a rational control of rotational barrier,thus allow for a fine tune of their viscosity sensitivity.Beyond RBFs,we envision similar strategies can be applied to control the fluorogenic behavior of a large group of fluorophores whose emission is dependent on excited state rotational motion,including aggregation-induced emission fluorophores.
基金National Natural Science Foundation of China,Grant/Award Numbers:32171433,81900034Natural Science Foundation of Fujian Province,Grant/Award Number:2021J01255。
文摘Colorectal cancer(CRC)is one of the most common cancers.Patients with advanced CRC can only rely on chemotherapy to improve outcomes.However,primary drug resistance frequently occurs and is difficult to predict.Changes in plasma protein composition have shown potential in clinical diagnosis.Thus,it is urgent to identify potential protein biomarkers for primary resistance to chemotherapy for patients with CRC.Automatic sample preparation and high-throughput analysis were used to explore potential plasma protein biomarkers.Drug susceptibility testing of circulating tumor cells(CTCs)has been investigated,and the relationship between their values and protein expressions has been discussed.In addition,the differential proteins in different chemotherapy outcomes have been analyzed.Finally,the potential biomarkers have been detected via enzyme-linked immunosorbent assay(ELISA).Plasma proteome of 60 CRC patients were profiled.The correlation between plasma protein levels and the results of drug susceptibility testing of CTCs was performed,and 85 proteins showed a significant positive or negative correlation with chemotherapy resistance.Forty-four CRC patients were then divided into three groups according to their chemotherapy outcomes(objective response,stable disease,and progressive disease),and 37 differential proteins were found to be related to chemotherapy resistance.The overlapping proteins were further investigated in an additional group of 79 patients using ELISA.Protein levels of F5 and PROZ significantly increased in the progressive disease group compared to other outcome groups.Our study indicated that F5 and PROZ proteins could represent potential biomarkers of resistance to chemotherapy in advanced CRC patients.
基金the National Natural Science Foundation of China(No.22271236)for support of this research.
文摘Comprehensive Summary The first catalytic asymmetric total synthesis of(+)-propolisbenzofuran B,enabled by a highly enantioselective rhodium-catalyzed hydrogenation of a tetrasubstituted olefin,was described.Other noteworthy aspects include the construction of the central hydrodibenzo[b,d]furan core through a sequence of Zn(II)-mediated regioselective benzofuran formation and Dieckmann condensation,as well as C-H oxidations,involving a visible light-induced Fe(III)-catalyzed benzylic C(sp3)-H oxidation.Additionally,the absolute configuration was confirmed by X-ray analysis of a carbonate intermediate.
基金Supported by the National Natural Science Foundation of China(Nos.20873050,20921003,20973074,20903044)the "111" Project(No.B06009)the Key Projects in the National Science & Technology Pillar Program,China(No.2007BAI38B03)
文摘We proposed a facile and rapid method for preparing silica-silver core-shell（SSCS） substrates to use Ag electroless plating on SiO2@Au-seed particles.UV-Vis-NIR absorption spectrometer and SEM were employed to monitor the reaction process of the formation of Ag on the surfaces of silica beads,and the optical resonance of the substrate could shift from visible to NIR region.It has been found that surface-enhanced Raman scattering（SERS） enhancement changes with the electroless plating time and the SSCS substrate with the plating time of 90 s（90SSCS） shows the strongest SERS response under the laser excitation at 514.5 nm.Signals collected over multiple spots and substrate of rhodamine 6G（R6G） resulted in a relative standard deviation（RSD） of 9.75%.The calculated enhancement factor（EF） was approximately 105 ＂106.SSCS substrate exhibits high SERS performance,which is due to electromagnetic SERS enhancement with additional localization field within closely packed Ag nanoparticles decorated on the SiO2 nanoparticles.And this substrate presents tunable and broad localized surface plasmon resonance（LSPR）,so this method may open a new way for SERS studies with other laser excitation.
基金Project supported by the National Natural Science Foundation of China(21922602,U1905214,22106101)Shanghai Science and Technology Innovation Action Plan(20dz1204200)Fundamental Research Funds for the Central Universities。
文摘Various Er modified MnO_(x) catalysts were synthesized using co-precipitation approach and tested in the selective catalytic reduction of NO_(x) by ammonia(NH_(3)-SCR).Catalysts were analyzed with various characterization techniques,and it is found that the doping of Er can enormously enhance the catalytic performance of MnO_(x)catalyst.MnEr_(0.1)demonstrates advantageous catalytic performance in the NH_(3)-SCR reaction owing to rich surface acidic sites,high surface content of Mn^(4+),superior redox capacity,and enhanced surface-adsorbed oxygen.From diffuse reflectance infrared Fourier transform spectroscopy(DRIFTs)analysis,it is suggested that the MnEr0.1catalyst follows mainly Eley-Rideal mechanism while MnO_(x) is dominated by Langmuir-Hinshelwood mechanism.
基金the Basic Science Research Program of the National Research Foundation(NRF)of Korea(Nos.2019R1A6A1A11053838,2022R1A4A3033528,and 2022R1F1A1063285)Korea Agency for Infrastructure Technology Advancement(KAIA)funded by the Ministry of Land,Infrastructure,and Transport(No.21CTAP-C163795-01)Prof.M.Y.Choi acknowledges the Korea Basic Science Institute(National Research Facilities and Equipment Center)grant funded by the Ministry of Education(Nos.2019R1A6C1010042 and 2021R1A6C103A427).
文摘The single-pot production of Pd@Pt core-shell structures is a promising approach as it offers large surface area,catalytic capability,and stability.In this work,we established a single-pot process to produce Pd@Pt core-shell nanodendrites with tunable composition,shape and size for optimal electrochemical activity.Pd@Pt nanodendrites with diverse compositions were synthesized by tuning the ratios of Pd and Pt sources in an aqueous environment using cetyltrimethylammonium chloride,which functioned as both the surfactant and the reducing agent at an elevated temperature(90°C).The synthesized Pd5@Pt5 nanodendrites showed exceptional electrochemical action toward the methanol oxidation reaction related with another compositional Pd@Pt nanodendrites and conventional Pt/C electrocatalysts.In addition,Pd5@Pt5 nanodendrites exhibited good CO tolerance owing to their surface features and the synergistic effect among Pt and Pd.Meanwhile,nanodendrites with a Pt-rich surface provided exceptional catalytic active sites.Compared with the conventional Pt/C electrocatalyst,the anodic peak current obtained by Pd5@Pt5 nanodendrites was 3.74 and 2.18 times higher in relations of mass and electrochemical active surface area-normalized current density,respectively.This approach offers an attractive strategy to design electrocatalysts with unique structures and outstanding catalytic performance and stability for electrochemical energy conversion.
基金supported by the National Natural Science Foundation of China(22350004,22101114,22271132)the ShenzhenScienceandTechnologyInnovationProgram(20231120110042001)+1 种基金the High Level of Special Funds(G03050K003)the Guangdong Innovation and Entrepreneurial Research Team Program(2021ZT09C278)。
文摘We demonstrate that a bulky cyclic amino ligand,specifically 1,1,3,3-tetraphenylisoindolinyl,can facilitate the formation of a transient stannyne,endowed with adjacent ambiphilic carbon and tin centers.This stannyne,manifesting carbene-like behavior,engages in an unprecedented sequence of reactions,including Buchner ring expansion,[1,3]sigmatropic,and[1,5]-sigmatropic shifts,culminating in the synthesis of a stable cyclic(alkyl)(amino)stannylene.This compound represents the first tin analogue of the well-known cyclic(alkyl)(amino)carbenes.Both the bonding configuration and the formation process of this stannylene are thoroughly analyzed through quantum chemical computations.Our findings pave the way for further synthesis of unusual main group species using bulky isoindolinyl substituents,emphasizing their potential as a versatile tool in synthetic chemistry.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF-2013R1A1A1004831)research funds of Chonbuk National University in 2012
文摘Transcription factors constitute numerous signal transduction networks and play a central role in gene expression regulation. Recent studies have shown that a limited portion of transcription factors are anchored in the cellular membrane, storing as dormant forms. Upon exposure to environmental and developmental cues, these transcription factors are released from the membrane and translocated to the nucleus, where they regulate associated target genes. As this process skips both transcriptional and translational regulations, it guarantees prompt response to external and internal signals. Membrane- bound transcription factors （MTFs） undergo several unique steps that are not involved in the action of canonical nuclear transcription factors： proteolytic processing and intracellular movement. Recently, alternative splicing has also emerged as a mechanism to liberate MTFs from the cellular membranes, establishing an additional activation scheme independent of proteolytic processing. Multiple layers of MTF regulation add complexity to transcriptional regulatory scheme and ensure elaborate action of MTFs. In this review, we provide an overview of recent findings on MTFs in plants and highlight the molecular mechanisms underlying MTF liberation from cellular membranes with an emphasis on intracellular movement.
文摘Lanthanide complexes of Eu（III）, Gd（III）, Nd（III）, Sm（III）, and Tb（III） with phenylthioacetic acid were synthesized and characterized by elemental analysis, mass, infrared radiation （IR）, electronic spectra, molar conductance, thermogravimetric analysis （TGA）, and powder X-ray diffraction （XRD）. The results showed that the lanthanide complexes were homodinuclear in nature. The two lanthanide ions were bridged by eight oxygen atoms from four carboxylate groups. Thermal decomposition profiles were consis- tent with the proposed formulations. Powder XRD studies showed that all the complexes were amorphous in nature. Antimicrobial studies indicated that these complexes exhibited more activity than the ligand itself. The DNA cleavage activity of the ligand and its complexes were assayed on CT DNA using gel electrophoresis in the presence of H202. The result showed that the Eu（Ⅲ） and Nd（Ⅲ） complexes completely cleaved the DNA. The anticancer activities of the complexes were also studied towards human cervical cancer cell line （HeLa） and colon cancer cells （HCT116） and it was found that the Eu（Ⅲ） and Nd（Ⅲ） complexes were more active than the corresponding Gd（Ⅲ）, Sm（Ⅲ）, Tb（Ⅲ） complexes and the free ligand on both the cancer cells.
基金The National Natural Science Foundation of China (Grant No. 21801043), the "Z1000-Youth Talents Plan", and Fudan University (start-up gra nt) are ack no wledged for fi nan cial support.
文摘Diels-Alder reaction is one of the most important reactions in organic synthesis and has witnessed great achievements in total syntheses of complex natural products.In this review,we will focus on the [4+2] cycloaddition that utilizes 2-pyrone as the diene component.Major advances of its applications in the total syntheses of natural products in the past fifty years will be discussed here.
基金supported by the National Natural Science Foundation of China(21375132,21175138,21321003,21171114,91222202)the National Basic Research Program of China(2013CB834803)
文摘Protein protected gold nanoclusters have outstanding physical and chemical properties that make them excellent scaffolds for the construction of novel chemical and biological probes. In this study, a simple one-pot synthesis method was proposed for the preparation of fluorescent probes based on ovalbumin-stabilized gold nanoclusters. This strategy allowed the generation of water-soluble gold nanoclusters within 5 min. The as-prepared fluorescent probe exhibited a red fluorescence emission at 625 nm, and good thermostability. The fluorescent probe was applied to measure glucose concentrations based on the hydrogen peroxide-induced fluorescence quenching principle, and showed favorable biocompatibility, high sensitivity and good selectivity. As a result of the advantageous properties and performance of this fluorescent probe, the present assay allowed for the selective determination of glucose in the range of 5.0×10-6 to 10.0×10-3 mol/L with a detection limit of 1.0×10?6 mol/L. Moreover, the glucose content in urinary samples was analyzed using the constructed fluorescent probe: this indicated the potential of the fluorescent gold nanoclusters for applications in biological and clinical diagnosis and therapy.
基金the Research Fund of the National Research Foundation of Korea(NRF-2021R1A3B1077184,NRF-2021R1F1A1064057 and NRF-2021R1A4A5032876).
文摘The demand for new catalysts for renewable energy production has become crucial.As an alternative to metal catalysts for electrocatalysis to produce energy sources,metal-phthalocyanine(MPc)electrocatalysts have shown potential.Their physicochemical and electrochemical properties depend on the chemical structure of the MPc and the central metal atom.Recent reviews of MPcs focused on their electrochemical performance in specific catalytic reactions,such as oxygen reduction reaction and CO_(2)reduction reaction.However,understanding the structure of MPcs in depth is important,since their electrochemical catalytic activity is affected by structural modifications of MPcs.Therefore,this minireview focuses on how the molecular structure of MPcs affects electrochemical catalysis.
