Resonance Raman spectroscopie investigations on phenolate bridged binuclear Cu(II) complexes: A basis for the identification of the endogenous bridging

Phenolate bridged binuclear Cu(II) complexes were used to monitor the contribution of the endogenous bridging ligand to the resonance Raman spectrum of the oxygen transport protein such as hemocyanin. From the excitation profile of the intensity enhanced phenolate v_c-o the phenolate-to-Cu(II) charge-transfer transition of the four studied complexes has been located between 380 nm and 430 run, similar to the low-temperature absorption band in the hemocyanin spectra. By approaching the exciting laser frequency to this electronic transition, the whole spectral range 1250–1650 cm⁻¹ is strongly intensity enhanced and considered as the typical feature of this kind of phenolate bridged Cu(II) complexes. Comparison to mononuclear analogues pointed out no significant differences of the resonance enhanced Raman lines. The results are discussed in relation to the resonance Raman spectra of hemocyanin.     

On transverse ordering in biomembranes by Raman spectroscopy

Computer simulation analysis of the structure sensitive features in the Raman spectrum of aqueous dipalmitoyl phosphatidylcholine (DPPC) multilayers was made for the 1000–1200 cm₋₁ region. The composite triplet was resolved into 4 Lorentzian bands with the possibility to follow their parameters (amplitude, width and position) in the temperature interval 25–60°C. The analysis reveals the apparent inward shift of the 1130 and 1065 cm⁻¹ bands towards both sides of the broad intense 1087 cm⁻¹ feature which is due to the relative changes in amplitudes of these bands in the course of the lipid phase transition. The more accurate method for the evaluation of the trans order parameter (S_trans) confirms the underestimation of the trans segment content above the phase transition temperature when using both the relative amplitude and area of the 1130 cm⁻¹ band for the quantitative characterization of chain conformation. Calculated changes in the bilayer thickness following the frequency shift of the 1100 cm⁻¹ band are in good agreement with the previously reported deuterium NMR data and X-ray diffraction studies.     

Adsorption characteristics of sulfur powder by bamboo charcoal to restrain sulfur allergies

Exposures to particulate matter with a diameter of 2.5 μm or less (PM2.5) may influence the risk of birth defects and make you allergic, which causes serious harm to human health. Bamboo charcoal can adsorb harmful substances,that was of benefitto people’s health. In order to figure out the optimal adsorbtion condition and the intrinsic change of bamboo charcoal, five chemicals were adsorbed by bamboo charcoal and were analyzed by FT-IR. The optimal blast time was 80 min of Na₂SO₃, 100 min of Na₂S₂O₈, 20 min of Na₂SO₄, 120 min of Fe₂(SO₄)₃ and 60 min or 100 min of S. FT-IR spectra showed that bamboo charcoal had five characteristic peaks of SS stretch, H₂O stretch, OH stretch, CO stretch or CC stretch, and NO₂ stretch at 3850 cm⁻¹, 3740 cm⁻¹, 3430 cm⁻¹, 1630 cm⁻¹ and 1530 cm⁻¹, respectively. For Na₂SO₃, the peaks at 3850 cm⁻¹, 3740 cm⁻¹, 3430 cm⁻¹, 1630 cm⁻¹ and 1530 cm⁻¹ achieved the maximum at 20 min. For Na₂S₂O₈, the peaks at 3850 cm⁻¹, 3740 cm⁻¹, 3430 cm⁻¹ and 1530 cm⁻¹ achieved the maximum at 40 min. For Na₂SO₄, the peaks at 3850 cm⁻¹, 3740 cm⁻¹ and 1530 cm⁻¹ achieved the maximum at 40 min. For Fe₂(SO₄)₃, the peaks at 3850 cm⁻¹, 3740 cm⁻¹, 1630 cm⁻¹ and 1530 cm⁻¹ achieved the maximum at 120 min. For S, the peaks at 3850 cm⁻¹ and 3740 cm⁻¹ achieved the maximum at 40 min, the peaks at 1630 cm⁻¹ and 1530 cm⁻¹ achieved the maximum at 40 min. It proved that bamboo charcoal could remove sulfur powder from air to restrain sulfur allergies.     

In vitro cytotoxicity and pro-apoptotic activity of phycocyanin nanoparticles from Ulva lactuca (Chlorophyta) algae

This study investigated the in vitro antioxidant, proapoptotic and anti-proliferative activity of phycocyanin extracted from Ulva lactuca (Chlorophyta) algae extract loaded on albumin nanoparticle (ULANP). The characterization of ULANP profile was done by using FTIR and its cytotoxicity was investigated by using MTT assay against HepG2 and MCF7 cell lines. The proapoptotic markers caspase 8 & 9 were measured. Analysis of ULANP by FTIR showed the characteristic band (2100 cm⁻¹ ~3700 cm⁻¹) that is indicated primarily by COO, CO and conjugated double bond. These bonds showed the spectral band at peaks of 2985 cm⁻¹ and 2860 cm⁻¹, 2986 cm⁻¹ respectively. The antioxidant potential and radical scavenging property of ULANP was also appreciable as compared to the vitamin C and gallic acid. The antiproliferative assay carried out by WST-1 suggests that ULANP was effective against both HepG2 (93.17%) and MCF7 (91.3%). Caspase-8 and −9 were significantly elevated (p < 0.001) in both the cell lines of breast and liver cancer. It was concluded that ULANP induced anti-proliferative and pro-apoptotic activities on liver and breast cancer. It is promising as a novel antitumor activity for further investigation the mechanistic pathways mediated this action.     

Sedimentary Organic Carbon and Nitrogen Sequestration Across a Vertical Gradient on a Temperate Wetland Seascape Including Salt Marshes,Seagrass Meadows and Rhizophytic Macroalgae Beds

Coastal wetlands are key in regulating coastal carbon and nitrogen dynamics and contribute significantly to climate change mitigation and anthropogenic nutrient reduction. We investigated organic carbon (OC) and total nitrogen (TN) stocks and burial rates at four adjacent vegetated coastal habitats across the seascape elevation gradient of Cádiz Bay (South Spain), including one species of salt marsh, two of seagrasses, and a macroalgae. OC and TN stocks in the upper 1 m sediment layer were higher at the subtidal seagrass Cymodocea nodosa (72.3 Mg OC ha⁻¹, 8.6 Mg TN ha⁻¹) followed by the upper intertidal salt marsh Sporobolus maritimus (66.5 Mg OC ha⁻¹, 5.9 Mg TN ha⁻¹), the subtidal rhizophytic macroalgae Caulerpa prolifera (62.2 Mg OC ha⁻¹, 7.2 Mg TN ha⁻¹), and the lower intertidal seagrass Zostera noltei (52.8 Mg OC ha⁻¹, 5.2 Mg TN ha⁻¹). The sedimentation rates increased from lower to higher elevation, from the intertidal salt marsh (0.24 g cm⁻² y⁻¹) to the subtidal macroalgae (0.12 g cm⁻² y⁻¹). The organic carbon burial rate was highest at the intertidal salt marsh (91 ± 31 g OC m⁻² y⁻¹), followed by the intertidal seagrass, (44 ± 15 g OC m⁻² y⁻¹), the subtidal seagrass (39 ± 6 g OC m⁻² y⁻¹), and the subtidal macroalgae (28 ± 4 g OC m⁻² y⁻¹). Total nitrogen burial rates were similar among the three lower vegetation types, ranging from 5 ± 2 to 3 ± 1 g TN m⁻² y⁻¹, and peaked at S. maritimus salt marsh with 7 ± 1 g TN m⁻² y⁻¹. The contribution of allochthonous sources to the sedimentary organic matter decreased with elevation, from 72% in C. prolifera to 33% at S. maritimus. Our results highlight the need of using habitat-specific OC and TN stocks and burial rates to improve our ability to predict OC and TN sequestration capacity of vegetated coastal habitats at the seascape level. We also demonstrated that the stocks and burial rates in C. prolifera habitats were within the range of well-accepted blue carbon ecosystems such as seagrass meadows and salt marshes.

     

Adsorption characteristics of sulfur solution by acticarbon against drinking-water toxicosis

Sulfur and ammonia nitrogen are rich nutrient pollutants, after entering water can cause algal blooms, cause eutrophication of water body, the spread of them will not only pollute the environment, destroy the ecological balance, but also harm human health through food chain channels, especially drinking-water toxicosis. Acticarbon can adsorb harmful substances, it was beneficial for people’s health. In order to figure out the optimal adsorption condition and the intrinsic change of acticarbon, five chemicals were adsorbed by acticarbon and analyzed by FT-IR. The optimal adsorption condition of Fe₂(SO₄)₃, Na₂SO₄, Na₂S₂O₈, S and Na₂SO₃ was 9 g/1000 g at 80 min, 21 g/1000 g at 20 min, 15g/1000 g at 20 min, 21 g/1000 g at 60 min and 21 g/1000 g at 100 min, respectively. FT-IR spectra showed that acticarbon had eight characteristic peaks, such as S-S stretch, H₂O stretch, OH stretch, CH stretch, CO or CC stretch, CH₂ bend, CH were at 3850 cm⁻¹, 3740 cm⁻¹, 3435 cm⁻¹, 2925 cm⁻¹, 1630 cm⁻¹, 1390 cm⁻¹, 1115 cm⁻¹, 600 cm⁻¹, respectively. For FT-IR spectra of Fe₂(SO₄)₃, the peaks at 3850 cm⁻¹, 3740 cm⁻¹, 2925 cm⁻¹ achieved the maximum with 9 g/1000 g at 20 min. For Na₂SO₄, the peaks at 2925 cm⁻¹, 1630 cm⁻¹, 1390 cm⁻¹, 1115 cm⁻¹, 600 cm⁻¹ achieved the maximum with 21 g/1000 g at 120 min. For ones of Na₂S₂O₈, the peaks at 3850 cm⁻¹, 3740 cm⁻¹, 1390 cm⁻¹, 1115 cm⁻¹, 600 cm⁻¹, achieved the maximum with 2 g/1000 g at 80 min. For ones of S, the peaks at 3850 cm⁻¹, 3740 cm⁻¹, 2925 cm⁻¹ achieved the maximum with 19 g/1000 g at 100 min, the peaks at 1390 cm⁻¹, 1115 cm⁻¹, 600 cm⁻¹ achieved the maximum with 19 g/1000 g at 20 min. For FT-IR spectra of Na₂SO₃, the peaks at 1630 cm⁻¹, 1390 cm⁻¹, 1115 cm⁻¹, 600 cm⁻¹ achieved the maximum with 2 g/1000 g at 100 min. It provided that acticarbon could adsorb and desulphurize from sulfur solution against drinking-water toxicosis.     

Real-time vibrational dynamics in chlorophyll a studied with a few-cycle pulse laser

We use a 6.8-fs laser as the light source for broad-band femtosecond pump-probe real-time vibrational spectroscopy to investigate both electronic relaxation and vibrational dynamics of the Q_y-band of Chl-a at 293 K. More than 25 vibrational modes coupled to the Q_y transition are observed. Eleven of them have been clarified predominantly due to the excited state, and six of them are concluded to be nearly exclusively resulting from the ground-state wave-packet motion. Moreover, thanks to the broad-band detection over 5000 cm⁻¹, the modulated signals due to the excited state vibrational coherence are observed on both sides of the 0-0 transition with equal separation. The corresponding nonlinear process has been studied using a three-level model, from which the probe wavelength dependence of the phase of the periodic modulation can be calculated. The probe wavelength dependence of the vibrational amplitude is interpreted in terms of the interaction between the “pump” or “laser,” Stokes, and anti-Stokes field intermediated by the molecular vibrations. In addition, an excited state absorption peak at ∼709 nm has been observed. To the best of our knowledge, this is the first study of broad-band real-time vibrational spectroscopy in Chl-a.     

Desulphurization characteristics of bamboo charcoal from sulfur solution

Sulfur powder and sulfur dioxide (SO₂) often floated in air, produced acid rain and algal blooms, and could cause diseases. Bamboo charcoal could have adsorption and filtration properties. In order to figure out the optimal adsorption condition and the intrinsic change of the bamboo charcoal, five chemicals were adsorbed by bamboo charcoal and were analyzed by FT-IR. Fe₂(SO₄)₃’s, Na₂SO₄’s, Na₂S₂O₈’s, S’s, and Na₂SO₃’s optimal adsorption condition was the concentration of 19 g/1000 g and stir time of 20 min, 21 g/1000 g and stir time of 60 min, 7 g/1000 g and stir time of 120 min, 11 g/1000 g and stir time of 120 min, 21 g/1000 g and stir time of 60 min, respectively. FT-IR spectra showed that for FT-IR spectra of Fe₂(SO₄)₃, the transmissivity of the peaks at 3435 cm⁻¹ and 2925 cm⁻¹ achieved the maximum for 60 min and the concentration was 19 g/1000 g, the transmissivity of the peaks at 1630 cm⁻¹, 1060 cm⁻¹ and 660 cm⁻¹ achieved the maximum for 60 min and the concentration was 7 g/1000 g. For FT-IR spectra of Na₂SO₄, the transmissivity of the peaks at 1630 cm⁻¹, 1060 cm⁻¹ and 660 cm⁻¹ achieved the maximum for 20 min and the concentration was 13 g/1000 g. For FT-IR spectra of Na₂S₂O₈, the transmissivity of the peaks at 3435 cm⁻¹, 2925 cm⁻¹, 1630 cm⁻¹ and 1060 cm⁻¹ achieved the maximum for 120 min and the concentration was 19 g/1000 g. For FT-IR spectra of S, the transmissivity of the peaks at 3435 cm⁻¹, 2925 cm⁻¹, 1630 cm⁻¹ and 1060 cm⁻¹ achieved the maximum for 20 min and the concentration was 11 g/1000 g, 17 g/1000 g and 21 g/1000 g. For FT-IR spectra of Na₂SO₃, the transmissivity of the peaks at 3435 cm⁻¹ achieved the maximum for 120 min and the concentration was 5 g/1000 g, the transmissivity of the peaks at 2925 cm⁻¹, 1630 cm⁻¹ and 1060 cm⁻¹ achieved the maximum for 120 min and the concentration was 11 g/1000 g. In these states, the number of the transmissivity of the maximum peaks is the largest.     

Studying the genotoxic effects of high intensity terahertz radiation on fibroblasts and CNS tumor cells

The data is obtained on the effect of high-intensity pulses of terahertz (THz) radiation with a broad spectrum (0.2–3 THz) on cell cultures. We have evaluated the threshold exposure parameters of THz radiation causing genotoxic effects in fibroblasts. Phosphorylation of histone H2AX at Ser 139 (γH2AX) was chosen as a marker for genotoxicity and a quantitative estimation of γH2AX foci number in fibroblasts was performed after cell irradiation with THz pulses for 30 min. No genotoxic effects of THz radiation were observed in fibroblasts unless peak intensity and electric field strength exceeded 21 GW cm⁻² and 2.8 MV cm⁻¹, respectively. In tumor cell lines (neuroblastoma (SK-N-BE (2)) and glioblastoma (U87)), exposure to THz pulses with peak intensity of 21 GW cm⁻² for 30 min caused no morphological changes as well as no statistically significant increase in histone phosphorylation foci number.     

Polarized Raman spectrum of single crystal uridylyl (3′–5′) adenosine: Local Raman tensors of some functional groups

Polarized Raman scattering measurements have been made of a single crystal of uridylyl(3′–5′)adenosine (UpA) by the use of a Raman microscope with 488.0 nm excitation. The UpA crystal belongs to space group P2₁ (monoclinic), and Raman intensities I_aa, I_bb, and I_c′c′, have been determined for each Raman band. These intensities correspond to the aa, bb, and c′c′ components of the crystal Raman tensor, where c′ is defined as an axis perpendicular to the crystallographic a axis in the ac plane. From these experimental data, and by taking the known crystal structure into account, anisotropic and isotropic molecular Raman tensors have been calculated for the following 11 normal modes: ring stretching modes of the adenine residue (protonated) at 1560, 1516, 1330, and 715 cm⁻¹; ring stretching modes of the uracil residue at 1696, 1657, 1615, 1228, and 790 cm⁻¹; PO⁻₂ symmetric stretching mode at 1080 cm⁻¹; P(—)O single bond stretching mode at 801 cm₋₁. These pieces of information of the Raman tensors are considered to be useful for estimating the orientations of the DNA and RNA strands in a biological complex from a polarized Raman spectroscopic measurement of such a complex. © 1998 John Wiley & Sons, Inc. Biopoly 45: 135–147, 1998     

Sub-0.6 eV Inverted Metamorphic GaInAs Cells Grown on Inp and GaAs Substrates for Thermophotovoltaics and Laser Power Conversion

Inverted metamorphic Ga_0.3In_0.7As photovoltaic converters with sub-0.60 eV bandgaps grown on InP and GaAs are presented. Threading dislocation densities are 1.3 ± 0.6 × 10⁶ and 8.9 ± 1.7 × 10⁶ cm⁻² on InP and GaAs, respectively. The devices generate open-circuit voltages of 0.386 and 0.383 V, respectively, under irradiance producing a short-circuit current density of ≈10 A cm⁻², yielding bandgap-voltage offsets of 0.20 and 0.21 V. Power and broadband reflectance measurements are used  to estimate thermophotovoltaic (TPV) efficiency. The InP-based cell is estimated to yield 1.09 W cm⁻² at 1100 °C versus 0.92 W cm⁻² for the GaAs-based cell, with efficiencies of 16.8 versus 9.2%. The efficiencies of both devices are limited by sub-bandgap absorption, with power weighted sub-bandgap reflectances of 81% and 58%, respectively, the majority of which is assumed to occur in the graded buffers. The 1100 °C TPV efficiencies are estimated to increase to 24.0% and 20.7% in structures with the graded buffer removed, if previously demonstrated reflectance is achieved. These devices also have application to laser power conversion in the 2.0–2.3 µm atmospheric window. Peak laser power converter efficiencies of 36.8% and 32.5% are estimated under 2.0 µm irradiances of 1.86 and 2.81 W cm⁻², respectively.     

Contribution of the Resonance Raman Spectroscopy to the Identification of Z DNA

Abstract

Poly(dG-dC)?poly(dG-dC) at low salt concentration (0.1 M NaCl) and at high salt concentration (4.5 M NaCl) has been studied by Raman resonance spectroscopy using two excitation wavelengths: 257 nm and 295 nm. As resonance enhances the intensity of the lines in a proportion corresponding to the square of the molar absorption coefficient, the intensities of the lines with 295 nm wavelength excitation are enhanced about sevenfold during the B to Z transition.

With 257 nm excitation wavelength the 1580 cm^?1 line of guanosine is greatly enhanced in the Z form whereas with 295 nm excitation several lines are sensitive to the modifications of the conformation: the guanine band around 650 cm^?1 and at 1193 cm^?1 and the bands of the cytosines at 780 cm^?1, 1242 cm^?1 and 1268 cm^?1.

By comparison with the U.V. resonance Raman spectra of DNA, we conclude that resonance Raman spectroscopy allows one to characterize the B to Z transition from one line with 257 nm excitation wavelength and from three lines with 295 nm excitation. The conjoined study of these four lines should permit to observe a few base pairs being in Z form in a DNA.     

Vertical Redistribution of Soil Organic Carbon Pools After Twenty Years of Nitrogen Addition in Two Temperate Coniferous Forests

Nitrogen (N) inputs from atmospheric deposition can increase soil organic carbon (SOC) storage in temperate and boreal forests, thereby mitigating the adverse effects of anthropogenic CO₂ emissions on global climate. However, direct evidence of N-induced SOC sequestration from low-dose, long-term N addition experiments (that is, addition of < 50 kg N ha⁻¹ y⁻¹ for > 10 years) is scarce worldwide and virtually absent for European temperate forests. Here, we examine how tree growth, fine roots, physicochemical soil properties as well as pools of SOC and soil total N responded to 20 years of regular, low-dose N addition in two European coniferous forests in Switzerland and Denmark. At the Swiss site, the addition of 22 kg N ha⁻¹ y⁻¹ (or 1.3 times throughfall deposition) stimulated tree growth, but decreased soil pH and exchangeable calcium. At the Danish site, the addition of 35 kg N ha⁻¹ y⁻¹ (1.5 times throughfall deposition) impaired tree growth, increased fine root biomass and led to an accumulation of N in several belowground pools. At both sites, elevated N inputs increased SOC pools in the moderately decomposed organic horizons, but decreased them in the mineral topsoil. Hence, long-term N addition led to a vertical redistribution of SOC pools, whereas overall SOC storage within 30 cm depth was unaffected. Our results imply that an N-induced shift of SOC from older, mineral-associated pools to younger, unprotected pools might foster the vulnerability of SOC in temperate coniferous forest soils.

     

Micropropagation,berberine content and antitumor activity of Jeffersonia dubia (Maxim.) Benth et Hook

An efficient micropropagation protocol was developed for Jeffersonia dubia using sucker explants. High frequency of multiple shoot formation was induced when the sucker explants were cultured on Chu’s (N6) medium with different concentrations of thidiazuron (TDZ) plus 0.54 µM α-naphthaleneacetic acid (NAA). The maximum frequency of shoot formation (96.2 %) was obtained on N6 medium with 2.27 µM TDZ plus 0.54 µM NAA. The highest mean number of shoots per explant (13.6) was obtained in temporary immersion system using an immersion frequency of 30 s every 30 min. The highest frequency of rooting (100 %), number of roots per shoot (5.8), and root length (6.3) was observed in half-strength N6 medium supplemented with 2.69 µM NAA. The regenerated plantlets (30 days old) were successfully acclimatized in the greenhouse with 98 % survival rate. The berberine content and cytotoxicity were higher in in vitro-developed calli and shoots than in leaves of field-grown plants. The greatest content of berberine was found in shoots (1381 μg g⁻¹) followed by calli (1092 μg g⁻¹) and leaves of field-grown plants (92 μg g⁻¹). At 1000 μg mL⁻¹ concentration, growth inhibition rate of berberine, callus, shoot, and leaf (in vivo) extracts were 68.4, 57.1, 54.2, and 17.7 %, respectively.

     

Irradiance-driven 20-hydroxyecdysone production and morphophysiological changes in Pfaffia glomerata plants grown in vitro

Pfaffia glomerata possesses potential pharmacological and medicinal properties, mainly owing to the secondary metabolite 20-hydroxyecdysone (20E). Increasing production of biomass and 20E is important for industrial purposes. This study aimed to evaluate the influence of irradiance on plant morphology and production of 20E in P. glomerata grown in vitro. Nodal segments of accessions 22 and 43 (Ac22 and Ac43) were inoculated in culture medium containing MS salts and vitamins. Cultures were maintained at 25 ± 2 °C under a 16-h photoperiod and subjected to irradiance treatments of 65, 130, and 200 μmol m⁻² s⁻¹ by fluorescent lamps. After 30 days, growth parameters, pigment content, stomatal density, in vitro photosynthesis, metabolites content, and morphoanatomy were assessed. Notably, Ac22 plants exhibited 10-fold higher 20E production when cultivated at 200 μmol m⁻² s⁻¹ than at 65 μmol m⁻² s⁻¹, evidencing the importance of light quantity for the accumulation of this metabolite. 20E production was twice as high in Ac22 as in Ac43 plants although both accessions responded positively to higher irradiance. Growth under 200 μmol m⁻² s⁻¹ stimulated photosynthesis and consequent biomass accumulation, but lowered carotenoids and anthocyanins. Furthermore, increasing irradiance enhanced the number of palisade and spongy parenchyma cells, enhancing the overall growth of P. glomerata.

Graphical abstract

     

Growth and loss of distal tissue in blades of Lessonia nigrescens and Lessonia trabeculata (Laminariales)

Meristematic growth and loss of distal tissue from blades of two ecologically important species in the south-east Pacific, Lessonia nigrescens and Lessonia trabeculata, was evaluated during 1 year. Comparative growth was determined by a hole-punch method, loss of distal tissue from the blades was determined by subtracting final blade length (with loss) from expected blade lengths (without loss); growth and tissue loss were transformed to fresh biomass units for calculation of inter-algae differences. The results showed that blade elongation rate increased at the beginning of spring, and declined towards the end of summer, with mean values between 0.40 and 0.08 cm day⁻¹ for L. nigrescens, and 0.65–0.17 cm day⁻¹ for L. trabeculata. Loss of distal tissue varied seasonally when examined as length units for both species; with mean values between 0.24 and 0.10 cm day⁻¹ for L. nigrescens, and 0.51–0.25 cm day⁻¹ for L. trabeculata. Variations in fresh biomass units were only observed in Lessonia trabeculata, increasing in spring, with mean values to 0.13 g (fresh weight) day⁻¹. Annual growth and loss of distal tissue were higher in L. trabeculata (0.41 and 0.39 cm day⁻¹, respectively) than in L nigrescens (0.19 and 0.15 cm day⁻¹). When growth and tissue loss were considered as fresh biomass, monthly gains significantly outweighed loss of distal tissue in both species, but parallel results based on length data followed a different trend. L. trabeculata released about 50% of its growth biomass as particulate organic matter, while the comparative value for L. nigrescens was about 20%.     

Significant Efficiency Enhancement in Ultrathin CZTS Solar Cells by Combining Al Plasmonic Nanostructures Array and Antireflective Coatings

In the few past years, the economic and eco-friendly Cu₂ZnSnS₄ (CZTS) solar cells have caught lots of attentions. However, due to rather poor efficiency, identifying deficiencies and making improvements is necessary. In the present study, the performance improvement of ultrathin CZTS solar cells was achieved through (1) incorporation of anti-reflective coating (ARC) on the surface of cell and (2) embedding Al plasmonic nanostructures with different radius, periods, and vertical positions in the absorber layer. Various thicknesses of CZTS absorber layer were simulated optically and electrically using FDTD and DEVICE solver of Lumerical software. The reference solar cell consists of a 1.5-nm-thick CZTS absorber and exhibit an efficiency of up to 5.67%, short-circuit current density (Jsc) of 18.48 mA cm⁻² and open circuit voltage of 0.58 V. Result showed a remarkable performance enhancement of the solar cell in spite of a very thin absorber layer. For a 500-μm-thick CZTS solar cell with the assistance of ARC and embedding Al plasmonic nanostructures, the efficiency is increased to 7.45% due to an increase in Jsc to 22.62 mA cm⁻² with an open circuit voltage of 0.62 V.

     

Ab initio-based vibrational analysis of α-poly(L-alanine)

Polarized ir and Raman spectra have been obtained on oriented films of α-helical poly(L -alanine) (α-PLA) and its N-deuterated derivative. These improved spectra permit a more complete assignment of observed bands to A-, E₁-, and E₂-species modes. A new empirical force field has been refined, based on ab initio force fields of N-methylacetamide and L -alanyl-L -alanine, which reproduces observed frequencies above 200 cm⁻¹ to less than 5 cm⁻¹. A new transition dipole coupling treatment avoids the weak coupling and perturbation approximations, and can now account for the newly observed and reassigned amide I (E₂) mode. As a result of this improved force field, several other observed bands have also been reassigned. © 1998 John Wiley & Sons, Inc. Biopoly 46: 283–317, 1998     

In-Situ Constructuring of Copper-Doped Bismuth Catalyst for Highly Efficient CO2 Electrolysis to Formate in Ampere-Level

CO₂ electrochemical reduction (CO₂RR) can mitigate environmental issues while providing valuable products, yet challenging in activity, selectivity, and stability. Here, a CuS-Bi₂S₃ heterojunction precursor is reported that can in situ reconstruct to Cu-doped Bismuth (CDB) electrocatalyst during CO₂RR. The CDB exhibits an industrial-compatible current density of −1.1 A cm⁻² and a record-high formate formation rate of 21.0 mmol h⁻¹ cm⁻² at −0.86 V versus the reversible hydrogen electrode toward CO₂RR to formate, dramatically outperforming currently reported catalysts. Importantly, the ultrawide potential region of 1050 mV with high formate Faradaic efficiency of over 90% and superior long-term stability for more than 100 h at −400 mA cm⁻² can also be realized. Experimental and theoretical studies reveal that the remarkable CO₂RR performance of CDB results from the doping effect of Cu which optimizes adsorption of the *OCHO and boosts the structural stability of metallic bismuth catalyst. This study provides valuable inspiration for the design of element-doping electrocatalysts to enhance catalytic activity and durability.     

Primary steps of electron and energy transfer in photosystem I: Effect of excitation pulse wavelength

Time-resolved differential spectra of photosystem I complex were obtained by the “pump-probe” technique with 25-fs pulses with maxima at 670, 700, and 720 nm. The ratio between the number of excited chlorophyll molecules of the antenna and of the reaction center was shown to depend on spectral characteristics of the pump pulses. In all cases, an ultrafast (<150 fs) formation of the primary radical pair P700⁺A₀⁻ was recorded. However, on excitation by pulses with maxima at 670 or 700 nm, detection of the charge separation was masked by the much more intensive bleaching at the chlorophyll Q_y band due to excitation of the bulk antenna chlorophylls. We show that triggering the charge separation by 25-fs pulses centered at 720 nm allows to detect more clearly kinetics of formation of the primary and secondary ion-radical pairs. The findings help to explain possible reasons for discrepancies of kinetics of primary steps of electron transfer detected in different laboratories.