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The spectroscopic and dynamic properties of methyl ferulate─a naturally occurring ultraviolet-protecting filter─and microsolvated methyl ferulate have been studied under molecular beam conditions using resonance-enhanced multiphoton ionization spectroscopy in combination with quantum chemical calculations. We demonstrate and rationalize how the phenyl substitution pattern affects the state ordering of the lower excited singlet state manifold and what the underlying reason is for the conformation-dependent Franck-Condon (FC) activity in the UV-excitation spectra. Studies on microsolvated methyl ferulate reveal potential coordination sites and the influence of such coordination on the spectroscopic properties. Our quantum chemical studies also enable us to obtain a quantitative understanding of the dominant excited-state decay routes of the photoexcited ππ* state involving a ∼3 ns intersystem crossing pathway to the triplet manifold─which is much slower than found for coumarates─and a relatively fast intersystem crossing back to the ground state (∼30 ns). We show that a common T1/S0crossing can very well explain the observation that T1lifetimes are quasi-independent of the phenyl substitution pattern.

Toxicological assessments of newly developed agrochemical agents consider chemical modifications and their metabolic and biotransformation products. To carry out an in silico hazard assessment, understanding the type of chemical modification and its location on the original compound can greatly enhance the reliability of the evaluation. Here, we present and apply a method based on liquid chromatography–mass spectrometry (LC–MS) enhanced with infrared ion spectroscopy (IRIS) to better delineate the molecular structures of transformation products before in silico toxicology evaluation. IRIS facilitates the recording of IR spectra directly in the mass spectrometer for features selected by retention time and mass-to-charge ratio. By utilizing quantum-chemically predicted IR spectra for candidate molecular structures, one can either derive the actual structure or significantly reduce the number of (isomeric) candidate structures. This approach can assist in making informed decisions. We apply this method to a plant growth stimulant, digeraniol sinapoyl malate (DGSM), that is currently under development. Incubation of the compound in Caco-2 and HepaRG cell lines in multiwell plates and analysis by LC–MS reveals oxidation, glucuronidation, and sulfonation metabolic products, whose structures were elucidated by IRIS and used as input for an in silico toxicology assessment. The toxicity of isomeric metabolites predicted by in silico tools was also assessed, which revealed that assigning the right metabolite structure is an important step in the overall toxicity assessment of the agrochemical. We believe this identification approach can be advantageous when specific isomers are significantly more hazardous than others and can help better understand metabolic pathways.

Viable nature-based climate solutions (NbCS) are needed to achieve climate goals expressed in international agreements like the Paris Accord. Many NbCS pathways have strong scientific foundations and can deliver meaningful climate benefits but effective mitigation is undermined by pathways with less scientific certainty. Here we couple an extensive literature review with an expert elicitation on 43 pathways and find that at present the most used pathways, such as tropical forest conservation, have a solid scientific basis for mitigation. However, the experts suggested that some pathways, many with carbon credit eligibility and market activity, remain uncertain in terms of their climate mitigation efficacy. Sources of uncertainty include incomplete GHG measurement and accounting. We recommend focusing on resolving those uncertainties before broadly scaling implementation of those pathways in quantitative emission or sequestration mitigation plans. If appropriate, those pathways should be supported for their cobenefits, such as biodiversity and food security.

The influence of forest treatments on wildfire effects is challenging to interpret. This is, in part, because the impact forest treatments have on wildfire can be slight and variable across many factors. Effectiveness of a treatment also depends on the metric considered. We present and define human–fire interaction, fire behavior, and ecological metrics of forest treatment effects on wildfire and discuss important considerations and recommendations for evaluating treatments. We demonstrate these concepts using a case study from the Cameron Peak Fire in Colorado, USA. Pre-fire forest treatments generally, but not always, experienced reduced burn severity, particularly when surface fuels were reduced. Treatments in the Cameron Peak Fire have also been documented as increasing tree survivorship, aiding suppression efforts, promoting firefighter safety, and influencing fire spread. However, the impacts of pre-fire management on primary landscape-scale objectives, like watershed protection, are unknown. Discussions about the influence of pre-fire treatments on fire effects must define the indicator(s) being assessed, as the same treatment may be considered successful under one measure but not others. Thus, it is critical to bring a common language and understanding to conversations about treatment effects and advance efforts to evaluate the range of treatment effects, thus supporting treatment planning.

Artificial molecular motors and machines constitute a critical element in the transition from individual molecular motion to the creation of collective dynamic molecular systems and responsive materials. The design of artificial light-driven molecular motors operating with high efficiency and selectivity constitutes an ongoing fundamental challenge. Here we present a highly versatile synthetic approach based on Rieche formylation that boosts the quantum yield of the forward photoisomerization reaction while reaching near-perfect selectivity in the steps involved in the unidirectional rotary cycle and drastically reducing competing photoreactions. This motor is readily accessible in its enantiopure form and operates with nearly quantitative photoconversions. It can easily be functionalized further and outperforms its direct predecessor as a reconfigurable chiral dopant in cholesteric liquid crystal materials.

Azonium ions formed by the protonation of tetra-ortho-methoxy-substituted aminoazobenzenes photoisomerize with red light under physiological conditions. This property makes them attractive as molecular tools for the photocontrol of physiological processes, for example, in photopharmacology. However, a mechanistic understanding of the photoisomerization process and subsequent thermal relaxation is necessary for the rational application of these compounds as well as for guiding the design of derivatives with improved properties. Using a combination of sub-ps/ns transient absorption measurements and quantum chemical calculations, we show that the absorption of a photon by the protonated E–H+form of the photoswitch causes rapid (ps) isomerization to the protonated Z–H+form, which can also absorb red light. Proton transfer to solvent then occurs on a microsecond time scale, leading to an equilibrium between Zand Z–H+species, the position of which depends on the solution pH. Whereas thermal isomerization of the neutral Zform to the neutral Eform is slow (∼0.001 s–1), thermal isomerization of Z–H+to E–H+is rapid (∼100 s–1), so the solution pH also governs the rate at which E/E–H+concentrations are restored after a light pulse. This analysis provides the first complete mechanistic picture that explains the observed intricate photoswitching behavior of azonium ions at a range of pH values. It further suggests features of azonium ions that could be targeted for improvement to enhance the applicability of these compounds for the photocontrol of biomolecules.

The spectroscopic and dynamics properties of flavone─the core chromophore of a wide variety of naturally occurring ultraviolet protecting filters─have been studied under supersonic beam conditions using (1 + 1′) resonance-enhanced two-photon ionization spectroscopic techniques. Excitation spectra recorded under such conditions are found to differ significantly from previously reported spectra. Pump–probe studies find that intersystem crossing is the dominant decay pathway of the excited singlet manifold, in agreement with previous solution phase studies and quantum chemical predictions for the isolated molecule. Microsolvation studies on flavone–water clusters reveal that the addition of one and two water molecules leads to considerable shifts in excitation energies but that further complexation does not result in further noticeable shifts. The relaxation pathways of the electronically excited states, on the other hand, do not appear to be influenced by interactions with the solvent molecules. Finally, photoionization spectra have enabled the accurate determination of the adiabatic ionization energy to the ground state of the molecular ion─key to the antioxidant properties of flavone─as 65,415 cm–1(8.110 eV).

Agricultural activities at lower temperatures lead to lower yields due to reduced plant growth. Applying photomolecular heater agrochemicals could boost yields under these conditions, but UV-induced degradation of these compounds needs to be assessed. In this study, we employ liquid chromatography–mass spectrometry (LC–MS) coupled with infrared ion spectroscopy (IRIS) to detect and identify the degradation products generated upon simulated solar irradiation of sinapoyl malate, a proposed photomolecular heater/UV filter compound. All major irradiation-induced degradation products are identified in terms of their full molecular structure by comparing the IRIS spectra obtained after LC fractionation and mass isolation with reference IR spectra obtained from quantum-chemical calculations. In cases where physical standards are available, a direct experimental-to-experimental comparison is possible for definitive structure identification. We find that the major degradation products originate from trans-to-cisisomerization, ester cleavage, and esterification reactions of sinapoyl malate. Preliminary in silico toxicity investigations using the VEGAHUB platform suggest no significant concerns for these degradation products’ human and environmental safety. The identification workflow presented here can analogously be applied to break down products from other agrochemical compounds. As the method records IR spectra with the sensitivity of LC–MS, application to agricultural samples, e.g., from field trials, is foreseen.

Applying biodegradable osteosyntheses avoids the disadvantages of titanium osteosyntheses. However, foreign-body reactions remain a major concern and evidence of complete resorption is lacking. This study compared the physico-chemical properties, histological response and radiographs of four copolymeric biodegradable osteosynthesis systems in a goat model with 48-months follow-up. The systems were implanted subperiosteally in both tibia and radius of 12 Dutch White goats. The BioSorb FX [poly(70LLA-co-30DLLA)], Inion CPS [poly([70–78.5]LLA-co-[16–24]DLLA-co-4TMC)], SonicWeld Rx [poly(DLLA)], LactoSorb [poly(82LLA-co-18GA)] systems and a negative control were randomly implanted in each extremity. Samples were assessed at 6-, 12-, 18-, 24-, 36-, and 48-month follow-up. Surface topography was performed using scanning electron microscopy (SEM). Differential scanning calorimetry and gel permeation chromatography were performed on initial and explanted samples. Histological sections were systematically assessed by two blinded researchers using (polarized) light microscopy, SEM and energy-dispersive X-ray analysis. The SonicWeld Rx system was amorphous while the others were semi-crystalline. Foreign-body reactions were not observed during the complete follow-up. The SonicWeld Rx and LactoSorb systems reached bone percentages of negative controls after 18 months while the BioSorb Fx and Inion CPS systems reached these levels after 36 months. The SonicWeld Rx system showed the most predictable degradation profile. All the biodegradable systems were safe to use and well-tolerated (i.e., complete implant replacement by bone, no clinical or histological foreign body reactions, no [sterile] abscess formation, no re-interventions needed), but nanoscale residual polymeric fragments were observed at every system's assessment.

Climate change creates a variety of novel stressors for species, such as a decline in snowpack. Loss of snow has many impacts, including the loss of thermal insulation of soils. Winter/spring freezing of soils has been tied to forest mass mortality in multiple locations around the world. Many species, however, can take alternative growth forms, such as tall tree forms and short shrub-like forms. Shrub-forms may provide a unique protection from the snow loss phenomenon by providing a similar thermal insulation as snowpack. That hypothesis is tested here using yellow-cedar, a species undergoing mass mortality due to snow loss. Temperature loggers were placed under both tree- and shrub-form cedars, including areas where the species was experimentally removed. The number of soil freezing days was high in open areas, areas of tree mortality, and where the shrub-form was removed, but was almost zero in areas where the shrub-form was left intact. This suggests that growth-form temperature moderation is possible and may provide an important resistance to the mortality mechanism. In other areas around the world where snow loss is resulting in soil freezing and mortality, growth forms should be investigated as a potential moderating mechanism for this particular climate change stress.

Fjords on the west coast of Spitsbergen experience variable Arctic and Atlantic climate signals that drive seasonal and inter‐annual variability of phytoplankton productivity and composition, by mechanisms that are not fully resolved. To this end, a time series (2013–2018) of Kongsfjorden (N 78°54.2, E 11°54.0) phytoplankton pigments, ocean physics, nutrient concentrations, and microbial abundances was investigated. Kongsfjorden phytoplankton dynamics were predominantly governed by solar radiation and cycles of warming and freshwater discharge that caused pronounced changes in light and nutrient availability. Phytoplankton growth after the polar night commenced in March in a mixed, nutrient loaded water column, and accelerated in April after weak thermal stratification. Spring (weeks 10–22) showed high diatom relative abundance that ceased when silicic acid and nitrate reached limiting concentrations. Summer (weeks 23–35) was characterized by sixfold stronger stratification due to increased freshwater discharge and continued ocean heating. This caused a warm, low salinity surface layer with low nutrient concentrations. Small and diverse flagellates, together with high bacterial and viral abundances, thrived in this regenerative, N or P‐limited system. Elevated late summer chlorophyll a(Chl a), and ammonium suggested increased regeneration and nutrient pulses by glacial upwelling. Fall (weeks 36–48) caused rapidly declining Chl aand increasing diatom relative abundance, which persisted throughout the polar night, causing high diatom relative abundance during spring. Despite inter‐annual variability in ocean temperature and salinity we observed relatively stable seasonal phytoplankton taxonomic composition and Chl a.

Effects of prolonged darkness on Arctic phytoplankton composition were investigated with lab experiments and a pigment time series in Kongsfjorden, Spitsbergen (78°55′N). Chlorophyll a(Chl a), pigment composition, particulate organic carbon, cell numbers, and photosynthetic characteristics were studied in Arctic diatoms (Thalassiosira antarctica, Thalassiosira nordenskioeldii) and flagellates (Rhodomonassp., Micromonassp.) during 8 weeks of darkness and subsequent recovery in irradiance. Loss of photosynthetic functionality after 2 weeks of darkness was reversible in all species when returned to irradiance. Diatoms were more resistant to prolonged darkness (> 2 weeks) compared to the flagellates, with lower decline rates of Chl aand maximum quantum yield of PSII. T. nordenskioeldiishowed rapid growth during recovery throughout 8 weeks of dark incubation, whereas recovery of flagellates diminished within 4 weeks. Ratios of taxonomic marker pigments relative to Chl aof all species showed limited variation during 8 weeks of dark incubation. The experimentally observed enhanced dark survival of diatoms was in agreement with pigment observations during four polar nights (2013–2017) in Kongsfjorden, which showed increased relative diatom abundance during declining biomass (down to 0.02 mg Chl am−3). Therefore, a period of prolonged darkness gives Arctic diatoms a head start during the early stages of the spring bloom. The taxon‐specific survival traits can influence the geographical distribution of diatoms and flagellates within the polar oceans and their phenology. Furthermore, the persistence of Chl aof nonviable phytoplankton during darkness might influence biomass estimates during the polar night.

Vibrational circular dichroism (VCD) is one of the major spectroscopic tools to study peptides. Nevertheless, a full understanding of what determines the signs and intensities of VCD bands of these compounds in the amide I and amide II spectral regions is still far from complete. In the present work, we study the origin of these VCD signals using the general coupled oscillator (GCO) analysis, a novel approach that has recently been developed. We apply this approach to the ForValNHMe model peptide in both α-helix and β-sheet configurations. We show that the intense VCD signals observed in the amide I and amide II spectral regions essentially have the same underlying mechanism, namely, the through-space coupling of electric dipoles. The crucial role played by intramolecular hydrogen bonds in determining VCD intensities is also illustrated. Moreover, we find that the contributions to the rotational strengths, considered to be insignificant in standard VCD models, may have sizable magnitudes and can thus not always be neglected. In addition, the VCD robustness of the amide I and II modes has been investigated by monitoring the variation of the rotational strength and its contributing terms during linear transit scans and by performing calculations with different computational parameters. From these studies—and in particular, the decomposition of the rotational strength made possible by the GCO analysis—it becomes clear that one should be cautious when employing measures of robustness as proposed previously.

The use of chiral medicines (possessing center(s) of asymmetric carbon) may cause adverse drug reactions (ADRs). The safety assurance of these medicines is critical. We aimed to evaluate registered and commonly used anti-infective chiral medicines circulating in the Tanzanian market to establish their safety profile to protect public health. A mixed prospective-retrospective cohort study was conducted to assess the safety profile of amoxicillin, amoxicillin-clavulanic acid and ceftriaxone injection. ADRs causality assessment was conducted by using World Health Organization (WHO)-Algorithm criteria. Data were collected from 7 tertiary hospitals: Muhimbili National Hospital (MNH), Kilimanjaro Christian Medical Centre (KCMC), Bugando Medical Centre (BMC), Ligula Referral-Regional Hospital (LRRH), Kitete Referral-Regional Hospital (KRRH), Dodoma Referral-Regional Hospital (DRRH), and Mbeya Zonal-Referral Hospital (MZRH). Data were supplemented by those recorded in the WHO-Vigiflow/VigiLyze databasewithin the same monitoring period. Data were analyzed using STATA version-15. The results were considered statistically significant when P < .05. A total of 2522 patients were enrolled in hospitals: MNH (499), KCMC (407), BMC (396), LRRH (387), KRRH (345), DRRH (249), and MZRH (239). Among those, 1197 (47.5%) were treated with ceftriaxone, 585 (23.2%) amoxicillin and 740(29.3%) amoxicillin-clavulanic acid. Out of those, 102 (4.5%) experienced adverse events (AEs), 49 (48%) were due to ceftriaxone, 37 (36.3%) amoxicillin-clavulanic acid and 16 (15.7%) amoxicillin (P-value .012). A total of 443 participants from the enrolled and WHO-Vigiflow/VigiLyze databasewere experienced with ADRs. The ADRs affected mainly gastro-intestinal system 234 (53%), skin and subcutaneous tissue 85 (19%), nervous system 49 (11%), respiratory thoracic 22 (5%), and general disorders 18(4%). In this study, approximately 90% of reported AEs were ADRs possible-related to the monitored medicines, with few plausible and certain. Ceftriaxone injection caused more ADRs. Amoxicillin-clavulanic acid was associated with more ADRs than amoxicillin alone. The safety profile of these medicines is still maintained; however, comprehensive monitoring of ADRs is recommended to improve patient safety and enhance overall treatment outcomes.

As computing power increases, vibrational circular dichroism (VCD) calculations on molecules of larger sizes and complexities become possible. At the same time, the spectra resulting from these computations become increasingly more cumbersome to analyze. Here, we describe the GUI implementation into the Amsterdam Density Functional (ADF) software package of VCDtools, a toolbox that provides a user-friendly means to analyze VCD spectra. Key features are the use of the generalized coupled oscillator analysis methods, as well as an easy visualization of the atomic electric and magnetic transition dipole moments which together provide detailed insight in the origin of the VCD intensity. Using several prototypical examples we demonstrate the functionalities of the program. In particular, we show how the spectra can be analyzed to detect differences between theory and experiment arising from large-amplitude motions or incorrect molecular structures and, most importantly, how the program can be used to prevent incorrect enantiomeric assignments.

The self-assembly of chiral supramolecular polymers is an intricate process that spans a wide range of length scales. Circular dichroism techniques are ideal to study this process as they provide information on the molecular scale but are at the same time also sensitive probes of the long-range interactions that control the growth and morphology of these polymers. As yet, Electronic Circular Dichroism that uses electronic transitions as a probe has by far been the method of choice while Vibrational Circular Dichroism, which uses vibrational transitions to probe structure, is much less employed. Here, we report experimental and theoretical studies of the self-assembly of helical supramolecular polymers of (S)-triarylamine tris-amides ((S)-TATA) in which both techniques are applied in concert. Theoretical studies based on quantum chemical calculations and on simplified models that allow for extrapolation to “infinitely” long polymers provide a solid basis for interpreting results from each of the two techniques that on their own would appear to be contradictory. In the particular case of (S)-TATA it is shown that upon equilibration the initially formed fibers undergo a conformational transition that becomes only “visible” by the combination of the two techniques. Our studies thus show that combining electronic and vibrational domains offers a unique and complementary means to probe these polymers, precisely because they are sensitive to different aspects of molecular and polymeric structure.

Recent reforms in science education highlight the need for student-centred approaches to teaching in school curriculum policy in South Africa. Science teachers are required to move away from traditional teacher-centred practices which regard students as mere passive recipients of knowledge. In this study, we examine classroom talk for the type of student participation encouraging moves employed in lessons on basic genetics concepts and the related quality of instructional strategies employed by a university lecturer during a semester course on genetics. A key feature of the course was the lecturer's use of students’ prior knowledge including alternative conceptions from a diagnostic assessment to facilitate the learning of pertinent genetics terminologies. Through a qualitative approach, we combine two recently published frameworks—the Analysing Teacher Moves (ATM)and the Elaborationframeworks—to analyse teacher talk from transcribed videoed lectures and explore the likely influence on student participation. The findings reveal two dominant student participation stimulating talk-related instructional strategies that seemed to elicit diverse and deeper responses from the students. These include higher-order initiatingand rejoindermoves, supplemented by othermoves, through which the lecturer provided students with factual information, often in a manner that enabled knowledge synthesis. The intentional use of open-ended questions, explanations and representations and probing students for further contributions signal deliberate pedagogic intentions to promote student interaction while navigating observed language proficiency challenges. The combined analysis framework is recommended for use in future studies on instructional practices which aim to promote fruitful classroom interaction.

The Western Antarctic Peninsula (WAP), one of the most productive regions of the Southern Ocean, is currently undergoing rapid environmental changes such as ocean acidification (OA) and increased daily irradiances from enhanced surface‐water stratification. To assess the potential for future biological CO2sequestration of this region, we incubated a natural phytoplankton assemblage from Ryder Bay, WAP, under a range of pCO2levels (180 μatm, 450 μatm, and 1000 μatm) combined with either moderate or high natural solar radiation (MSR: 124 μmol photons m−2s−1and HSR: 435 μmol photons m−2s−1, respectively). The initial and final phytoplankton communities were numerically dominated by the prymnesiophyte Phaeocystis antarctica, with the single cells initially being predominant and solitary and colonial cells reaching similar high abundances by the end. Only when communities were grown under ambient pCO2in conjunction with HSR did the small diatom Fragilariopsis pseudonanaoutcompete P. antarcticaat the end of the experiment. Such positive light‐dependent growth response of the diatom was, however, dampened by OA. These changes in community composition were caused by an enhanced photosensitivity of diatoms, especially F. pseudonana, under OA and HSR, reducing thereby their competitiveness toward P. antarctica. Moreover, community primary production (PP) of all treatments yielded similar high rates at the start and the end of the experiment, but with the main contributors shifting from initially large to small cells toward the end. Even though community PP of Ryder Bay phytoplankton was insensitive to the changes in light and CO2availability, the observed size‐dependent shift in productivity could, however, weaken the biological CO2sequestration potential of this region in the future.

Switches that can be actively steered by external stimuli along multiple pathways at the molecular level are the basis for next-generation responsive material systems. The operation of commonly employed molecular photoswitches revolves around one key structural coordinate. Photoswitches with functionalities that depend on and can be addressed along multiple coordinates would offer novel means to tailor and control their behavior and performance. The recently developed donor–acceptor Stenhouse adducts (DASAs) are versatile switches suitable for such applications. Their photochemistry is well understood, but is only responsible for part of their overall photoswitching mechanism. The remaining thermal switching pathways are to date unknown. Here, rapid-scan infrared absorption spectroscopy is used to obtain transient fingerprints of reactions occurring on the ground state potential energy surface after reaching structures generated through light absorption. The spectroscopic data are interpreted in terms of structural transformations using kinetic modeling and quantum chemical calculations. Through this combined experimental–theoretical approach, we are able to unravel the complexity of the multidimensional ground-state potential energy surface explored by the photoswitch and use this knowledge to predict, and subsequently confirm, how DASA switches can be guided along this potential energy surface. These results break new ground for developing user-geared DASA switches but also shed light on the development of novel photoswitches in general.

UV excitation and IR absorption spectroscopy on jet-cooled molecules is used to study the conformational heterogeneity of methyl 4-hydroxycinnamate, a model chromophore of the Photoactive Yellow Protein (PYP), and to determine the spectroscopic properties of the various conformers. UV–UV depletion spectroscopy identifies four different species with distinct electronic excitation spectra. Quantum chemical calculations argue that these species are associated with different conformers involving the s-cis/s-transconfiguration of the ester with respect to the propenyl C–C single bond and the syn/antiorientation of the phenolic OH group. IR–UV hole-burning spectroscopy is used to record their IR absorption spectra in the fingerprint region. Comparison with IR absorption spectra predicted by quantum chemical calculations provides vibrational markers for each of the conformers, on the basis of which each of the species observed with UV–UV depletion spectroscopy is assigned. Although both DFT and wave function methods reproduce experimental frequencies, we find that calculations at the MP2 level are necessary to obtain agreement with experimentally observed intensities. To elucidate the role of the environment, we compare the IR spectra of the isolated conformers with IR spectra of methyl 4-hydroxycinnamate–water clusters, and with IR spectra of methyl 4-hydroxycinnamate in solution.

We have prepared Au25(PET)18–2x((R)-FBINAS)x(PET = 2-phenylethylthiol, (R)-FBINAS = (R)-5,5′,6,6′,7,7′,8,8′-octafluoro-[1,1′-binaphthalene]-2,2′-dithiol) mixed ligand shell clusters via ligand exchange. Two fractions with different composition of the ligand shell were separated using size-exclusion chromatography and studied by infrared (IR) spectroscopy and vibrational circular dichroism (VCD). Both IR and VCD spectra are dominated by FBINAS vibrations although PET is more abundant on the cluster. Calculated VCD spectra on a model cluster Au25(SH)16(FBINAS)1depend on the charge state of the cluster, and the anion is in excellent agreement with the experimental spectra of the Au25(PET)18–2x(FBINAS)xsamples. Calculations of Au25(SH)14(FBINAS)2furthermore show very similar spectra for different adsorption isomers with one exception, where the two ligands share a SR–Au–SR–Au–SR staple motif. Model calculations show that it is not necessary to consider the entire cluster for obtaining reliable VCD and IR spectra, but the staple motifs cannot be neglected. A band that is assigned to PET shows significant vibrational optical activity, and an anisotropy factor that depends on the composition of the ligand shell. This shows that the FBINAS molecules can transfer chirality to achiral PET within the ligand shell of the cluster.

Vibrational circular dichroism (VCD) is a spectroscopic technique used to resolve the absolute configuration of chiral systems. Obtaining a theoretical VCD spectrum requires computing atomic polar and axial tensors on top of the computationally demanding construction of the force constant matrix. In this study we evaluated a VCD model in which all necessary quantities are obtained with density functional based tight binding (DFTB) theory. The analyzed DFTB parametrizations fail at providing accurate vibrational frequencies and electric dipole gradients but yield reasonable normal modes at a fraction of the computational cost of density functional theory (DFT). Thus, by applying DFTB in composite methods along with DFT, we show that it is possible to obtain accurate VCD spectra at a much lower computational demand.

In Arctic coastal regions, the phytoplankton bloom is often initiated by meltwater induced stratification in spring, while subsequent nutrient depletion is believed to drive phytoplankton succession in summer. The associated changes in photophysiology are difficult to identify, because these can be governed by acclimation to light and nutrient availability as well as variations in phytoplankton biomass and taxonomic composition. In the present study, the consequences of nutrient limitation for photophysiology and growth were assessed in natural phytoplankton communities from Kongsfjorden, Spitsbergen. A series of nutrient addition experiments demonstrated N‐limitation from mid‐June onwards and possible co‐limitation with P later in summer. The onset of N‐limitation was associated with a pronounced change in taxonomic composition from a dictyochophytes to a haptophytes dominated community. Fast Repetition Rate fluorometry measurements of photosystem II (PSII) photophysiology showed that the dictyochophytes dominated community was characterized by high PSII efficiency and electron transport rates which were efficiently used for growth. Marked changes in PSII photophysiology were observed later in summer, with decreasing efficiencies, lower connectivity between reaction centers, and slower turnover rates. Simultaneously, alternative electron requirements downstream of PSII became more important and energy was likely allocated to the uptake of nutrients rather than carbon fixation and growth. Relief of nutrient limitation during the nutrient addition experiments did not lead to pronounced changes in PSII photophysiology. It is, therefore, concluded that PSII photophysiology of the phytoplankton community in Kongsfjorden is associated with changes in species composition rather than a direct effect of nutrient availability or nutrient limitation.

The diarylethene moiety is one of the most extensively used switches in the field of molecular electronics. Here we report on spectroscopic and quantum chemical studies of two diarylethene-based compounds with a non-C3-symmetric triethynyl terthiophene core symmetrically substituted with RuCp*(dppe) or trimethylsilyl termini. The ethynyl linkers are strong IR markers that we use in time-resolved vibrational spectroscopic studies to get insight into the character and dynamics of the electronically excited states of these compounds on the picosecond to nanosecond time scale. In combination with electronic transient absorption studies and DFT calculations, our studies show that the conjugation of the non-C3-symmetric triethynyl terthiophene system in the excited state strongly affects one of the thiophene rings involved in the ring closure. As a result, cyclization of the otherwise photochromic 3,3″-dimethyl-2,2′:3′,2″-terthiophene core is inhibited. Instead, the photoexcited compounds undergo intersystem crossing to a long-lived triplet excited state from which they convert back to the ground state.

This paper reports on key aspects of a short in-service programme improving science teachers’ pedagogical content knowledge to teach for the affective domain. The affective domain refers to outcomes that involve changes in feelings, values, appreciation, interests, motivations or attitudes that might result from a learning experience. The intervention adopts a socio-scientific issues instructional strategy aimed at enhancing the participants’ capacity to promote these attributes in their teaching practice. Twenty-two science teachers from seven public schools in Johannesburg participated in a short intervention programme that explored creative ways of highlighting the practical relevance of science content, especially for the learners. Data were collected through questionnaires, interviews and observations and analysed qualitatively using Krathwohl’s taxonomy of affective learning outcomes and Saldana’s code-to-theory model. The emerging themes suggest that the intervention enabled the participants to develop more nuanced understandings and capabilities for privileging the needs of the affective domain in the teaching of science. The paper argues that, in the design and teaching of science lessons, the core content could be wrapped in contemporary social issues which learners can readily relate to and presented in ways that deliberately aim to excite students in order to promote their sustained engagement with both the content and social issues in more meaningful ways.

We demonstrate optical resolution photoacoustic microscopy (OR-PAM) of lipid-rich tissue between 1050–1714 nm using a pulsed supercontinuum laser based on a large-mode-area photonic crystal fiber. OR-PAM experiments of lipid-rich samples show the expected optical absorption peaks near 1210 and 1720 nm. These results show that pulsed supercontinuum lasers are promising for OR-PAM applications such as label-free histology of lipid-rich tissue and imaging small animal models of disease.

Landslides influence the global carbon (C) cycle by facilitating transfer of terrestrial C in biomass and soils to offshore depocenters and redistributing C within the landscape, affecting the terrestrial C reservoir itself. How landslides affect terrestrial C stocks is rarely quantified, so we derive a model that couples stochastic landslides with terrestrial C dynamics, calibrated to temperate rainforests in southeast Alaska, United States. Modeled landslides episodically transfer C from scars to deposits and destroy living biomass. After a landslide, total C stocks on the scar recover, while those on the deposit either increase (in the case of living biomass) or decrease while remaining higher than if no landslide had occurred (in the case of dead biomass and soil C). Specifically, modeling landslides in a 29.9 km2watershed at the observed rate of 0.004 landslides km−2yr−1decreases average living biomass C density by 0.9 tC ha−1(a relative amount of 0.4%), increases dead biomass C by 0.3 tC ha−1(0.6%), and increases soil C by 3.4 tC ha−1(0.8%) relative to a base case with no landslides. The net effect is a small increase in total terrestrial C stocks of 2.8 tC ha−1(0.4%). The size of this boost increases with landslide frequency, reaching 6.5% at a frequency of 0.1 landslides km−2yr−1. If similar dynamics occur in other landslide‐prone regions of the globe, landslides should be a net C sink and a natural buffer against increasing atmospheric CO2levels, which are forecast to increase landslide‐triggering precipitation events. Landslides are a natural process, often triggered by rainfall, that removes soil and forest cover from steep slopes and deposits them in valleys. Those soils and vegetation contain large amounts of carbon that has been removed from the atmosphere by photosynthesis. Landslides and carbon are therefore related, but it has not previously been determined whether the net effect of landslides is to release carbon back to or sequester additional carbon from the atmosphere. Our work, focused on temperate rainforests in southeast Alaska, indicates that landslides sequester additional carbon from the atmosphere by burying existing carbon in deposits and providing space for new carbon to accumulate on landslide scars. The amount of additional carbon sequestration increases as landslides occur more frequently. As climate change leads to more extreme rainfall events in forested parts of the world, such as southeast Alaska, more landslides are expected to occur. Therefore, increased landsliding may partially offset some of the elevated atmospheric carbon dioxide levels that drive landslide‐triggering extreme weather events in the first place, in a newly identified feedback loop. Coupled landslide‐carbon model shows landslides boost C stocks by sequestering C in deposits and creating space for new C to accumulateSize of the boost increases with landslide frequency, from ∼1% at an areal frequency of ∼10−4yr−1to ∼6.5% by a frequency of 10−3yr−1Landslides in temperate rainforests are likely a net C sink with respect to the atmosphere and a buffer against increasing atmospheric CO2levels Coupled landslide‐carbon model shows landslides boost C stocks by sequestering C in deposits and creating space for new C to accumulate Size of the boost increases with landslide frequency, from ∼1% at an areal frequency of ∼10−4yr−1to ∼6.5% by a frequency of 10−3yr−1 Landslides in temperate rainforests are likely a net C sink with respect to the atmosphere and a buffer against increasing atmospheric CO2levels

Joint trauma, which is frequently related with mechanical overloading of articular cartilage, is a well-established risk for osteoarthritis (OA) development. Additionally, reports show that trauma leads to synovial joint inflammation. In consequence, after joint trauma, cartilage is influenced by deleterious excessive loading combined with the catabolic activity of proinflammatory mediators. Since the activation of TGF-β signaling by loading is considered to be a key regulatory pathway for maintaining cartilage homeostasis, we tested the effect of proinflammatory conditions on mechanically mediated activation of TGF-β/Smad2/3P signaling in cartilage. Cartilage explants were subjected to dynamic mechanical compression in the presence of interleukin-1 beta (IL-1β) or osteoarthritic synovium-conditioned medium (OAS-CM). Subsequently, the activation of the Smad2/3P pathway was monitored with QPCR analysis of reporter genes and additionally the expression of receptors activating the Smad2/3P pathway was analyzed. Finally, the ability for mechanically mediated activation of Smad2/3P was tested in human OA cartilage. IL-1β presence during compression did not impair the upregulation of Smad2/3P reporter genes, however the results were affected by IL-1β-mediated upregulations in unloaded controls. OAS-CM significantly impaired the compression-mediated upregulation of bSmad7and Tgbfb1. IL-1β suppressed the compression-mediated bAlk5upregulation where 12 MPa compression applied in the presence of OAS-CM downregulated the bTgfbr2. Mechanically driven upregulation of Smad2/3P reporter genes was present in OA cartilage. Proinflammatory conditions partly impair the mechanically mediated activation of the protective TGF-β/Smad2/3P pathway. Additionally, the excessive mechanical compression, applied in the presence of proinflammatory conditions diminishes the expression of the type II TGF-β receptor, a receptor critical for maintenance of articular cartilage.

Cesium lead halide nanocrystals are a new attractive material for optoelectronic applications since they combine the advantageous properties of perovskites and quantum dots. For future applications in optoelectronics and photovoltaics, an efficient energy and/or carrier exchange is a necessary condition. Here, we explicitly demonstrate nonradiative energy transfer for colloidal CsPbBr3nanocrystals. Using time-resolved optical characterization of purposefully prepared batches of nanocrystals with different sizes, we identify the energy transfer which can be driven by the concentration gradient of excited nanocrystals as well as by the bandgap energy difference. The latter process moves the energy from smaller to larger nanocrystals and opens a possibility of directional streaming of the excitation energy in these materials. The observed energy transfer is enabled in the colloids by proximity of individual nanocrystals due to clustering.

We demonstrate a simple multi-wavelength optical source suitable for spectroscopic optical resolution photoacoustic microscopy (OR-PAM) of lipid-rich tissue. 1064 nm laser pulses are converted to multiple wavelengths beyond 1300 nm via nonlinear optical propagation in a birefringent optical fiber. OR-PAM experiments with lipid phantoms clearly show the expected absorption peak near 1210 nm. We believe this simple multi-color technique is a promising cost-effective approach to spectroscopic OR-PAM of lipid-rich tissue.

Lesions in knee joint articular cartilage (AC) have limited repair capacity. Many clinically available treatments induce a fibrous-like cartilage repair instead of hyaline cartilage. To induce hyaline cartilage repair, we hypothesized that type I collagen scaffolds with fibers aligned perpendicular to the AC surface would result in qualitatively better tissue repair due to a guided cellular influx from the subchondral bone. By specific freezing protocols, type I collagen scaffolds with isotropic and anisotropic fiber architectures were produced. Rabbits were operated on bilaterally and two full thickness defects were created in each knee joint. The defects were filled with (1) an isotropic scaffold, (2) an anisotropic scaffold with pores parallel to the cartilage surface, and (3) an anisotropic scaffold with pores perpendicular to the cartilage surface. Empty defects served as controls. After 4 (n=13) and 12 (n=13) weeks, regeneration was scored qualitatively and quantitatively using histological analysis and a modified O'Driscoll score. After 4 weeks, all defects were completely filled with partially differentiated hyaline cartilage tissue. No differences in O'Driscoll scores were measured between empty defects and scaffold types. After 12 weeks, all treatments led to hyaline cartilage repair visualized by increased glycosaminoglycan staining. Total scores were significantly increased for parallel anisotropic and empty defects over time (p<0.05). The results indicate that collagen scaffolds allow the formation of hyaline-like cartilage repair. Fiber architecture had no effect on cartilage repair.

Concerns over fetal bovine serum (FBS) limit the clinical application of cultured tissue-engineered constructs. Therefore, we investigated if platelet-rich plasma (PRP) can fully replace FBS for meniscus tissue engineering purposes. Human PRP and platelet-poor plasma (PPP) were isolated from three healthy adult donors. Human meniscal fibrochondrocytes (MFCs) were isolated from resected tissue after a partial meniscectomy on a young patient. Passage-4 MFCs were cultured in monolayer for 24 h, and 3 and 7 days. Six different culture media were used containing different amounts of either PRP or PPP and compared to a medium containing 10% FBS. dsDNA was quantified, and gene expression levels of collagen types I and II and aggrecan were measured at different time points with quantitative polymerase chain reaction in the cultured MFCs. After 7 days, the dsDNA quantity was significantly higher in MFCs cultured in 10% and 20% PRP compared to the other PRP and PPP conditions, but equal to 10% FBS. Collagen type I expression was lower in MFCs cultured with medium containing 5% PRP, 10% and 20% PPP compared to FBS. When medium with 10% PRP or 20% PRP was used, expressions were not significantly different from medium containing 10% FBS. Collagen type II expression was absent in all medium conditions. Aggrecan expression did not show differences between the different media used. However, after 7 days a higher aggrecan expression was measured in most culture conditions, except for 5% PRP, which was similar compared to FBS. Statistical significance was found between donors at various time points in DNA quantification and gene expression, but the same donors were not statistically different in all conditions. At 7 days cell cultured with 10% PRP and 20% PRP showed a higher density, with large areas of clusters, compared to other conditions. In an MFC culture medium, FBS can be replaced by 10% PRP or 20% PRP without altering proliferation and gene expression of human MFCs.

The use of laboratory animals in tissue engineering research is an important underexposed ethical issue. Several ethical questions may be raised about this use of animals. This article focuses on the possibilities of reducing the number of animals used. Given that there is considerable debate about the adequacy of the current animal models in tissue engineering research, we investigate whether it is possible to reduce the number of laboratory animals by selecting and using only those models that have greatest predictive value for future clinical application of the tissue engineered product. The field of articular cartilage tissue engineering is used as a case study. Based on a study of the scientific literature and interviews with leading experts in the field, an overview is provided of the animal models used and the advantages and disadvantages of each model, particularly in terms of extrapolation to the human situation. Starting from this overview, it is shown that, by skipping the small models and using only one large preclinical model, it is indeed possible to restrict the number of animal models, thereby reducing the number of laboratory animals used. Moreover, it is argued that the selection of animal models should become more evidence based and that researchers should seize more opportunities to choose or create characteristics in the animal models that increase their predictive value.

Molekulare Bremse: Die Wechselwirkungen zwischen Stab und Makrocyclus eines [2]Rotaxans können quasi stufenlos eingestellt werden, indem man H‐Brücken bildende Lösungsmittelmoleküle einzeln zu einem isolierten [2]Rotaxan‐Molekül gibt. So lassen sich gezielt Konformationsänderungen herbeiführen, die den Stab vom Makrocyclus freigeben – was dem kontrollierten Lösen der molekularen Bremse entspricht.

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van dePollW.H., BumaA.G.J., VisserR.J.W., JanknegtP.J., VillafañV.E. andHelblingE.W. 2010. Xanthophyll cycle activity and photosynthesis of Dunaliella tertiolecta(Chlorophyceae) and Thalassiosira weissflogii(Bacillariophyceae) during fluctuating solar radiation. Phycologia49: 249–259. DOI: 10.2216/08-83.1Short-term ultraviolet (UV) radiation (280–400 nm) effects on xanthophyll cycle activity and photosynthesis were assessed during fluctuating irradiance (60- and 10-min cycles – saturating irradiance to near-zero irradiance) for the marine algae Thalassiosira weissflogii(Bacillariophyceae) and Dunaliella tertiolecta(Chlorophyceae). Laboratory cultures were cycled, as above, up and down the water column for 8 h under solar radiation, during which photosystem II (PSII) quantum yield in the light [(Fm′− Ft)/Fm′] was monitored over 1-min intervals. In addition, pigment composition, xanthophyll de-epoxidation state and carbon assimilation were assessed during the fluctuating irradiance cycles. Although PSII quantum yield in the light of both species mirrored irradiance, the PSII response to irradiance fluctuations changed over time as PSII quantum yield was downregulated at midday. This coincided with maximal xanthophyll de-epoxidation that developed during the course of the day for both species. In contrast to the de-epoxidation levels, nonphotochemical quenching (NPQ) and PSII quantum yield in the light fluctuated with the irradiance dynamics at noon in both species. Maximal xanthophyll de-epoxidation and NPQ at noon was lower under photosynthetically active radiation (PAR) + UV than under PAR exposure for T. weissflogiiduring the 10-min cycle, whereas this was not found for the 60-min cycle and in D. tertiolecta. Synthesis of xanthophyll cycle pigments occurred in both species, and was faster for D. tertiolectaduring PAR + UV than during PAR exposure. Carbon incorporation and on most occasions PSII quantum yield in the light were lower during UV exposure for both species, regardless of xanthophyll de-epoxidation state. UV effects on carbon assimilation were higher during 10-min than during 60-min irradiance fluctuation cycles. However, the 10-min irradiance fluctuation cycle appeared to enhance overall carbon assimilation in D. tertiolectabut depressed productivity of T. weissflogii, as compared with the 60-min cycles.

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The macrocycle in rotaxane 1is preferentially hydrogen bonded to the succinamide station in the neutral form, but can be moved to the naphthalimide station by one‐electron reduction of the latter. The hydrogen bonding between the amide NH groups of the macrocycle and the CO groups in the binding stations in the thread was studied with IR spectroscopy in different solvents in both states. In addition, the solvent effect on the vibrational frequencies was analyzed; a correlation with the solvent acceptor number (AN) was observed. The conformational switching upon reduction could be detected by monitoring the hydrogen‐bond‐induced shifts of the ν(CO) frequencies of the CO groups of the succinamide and the reduced naphthalimide stations. The macrocycle was found to shield the encapsulated station from the solvent: wavenumbers of ν(CO) bands of the CO groups residing inside the macrocycle cavity remain unaffected by the solvent polarity.

Little is known on growth, growth hormone (GH) levels and GH treatment in patients with Ellis–van Creveld syndrome (EvC). The aim of the present study was to assess growth, growth hormone status and the possible effectiveness of GH treatment in literature and in a small series of EvC patients. A review of literature indicated retarded growth for most EvC patients (−2 to −4.5 SDS) and minimal data on GH levels or treatment which did not allow any conclusion. We studied eight EvC patients, seven of whom were treated with GH. Four were GH deficient (GHD) and four were GH sufficient. In all patients treated with GH, first year growth velocity increased. In three of the four GHD and in one GH‐sufficient patient a gain in height SDS was noted. In the present small EvC series GHD occurred more often than expected. Patient acquisition through the Growth Hormone Database will have caused a significant bias, but the present results indicate that GH treatment may improve growth in at least some patients with EvC. Therefore we conclude that EvC patients may benefit from being tested for GHD and, if indicated, treated. In addition a prospective study to evaluate GH status and linear growth in patients with EvC as well as the potential effectiveness of GH treatment is warranted. © 2007 Wiley‐Liss, Inc.

Femtosecond two-color vibrational pump−probe spectroscopy is used to investigate the interaction between the NH- and CO-stretch vibrations in a rotaxane composed of a benzylic amide macrocycle mechanically locked onto a succinamide-based thread. From the transient absorption spectrum, we obtain the cross anharmonicities and cross-peak anisotropies arising from the NH(macrocycle)/CO(macrocycle) and NH(macrocycle)/CO(thread) interactions. The cross-peak anisotropies are used to determine angles between NH and CO bonds in the macrocycle and the thread, providing structural information with picosecond temporal resolution. The CO and NH groups that form the macrocycle−thread hydrogen bonds are found to interact much more strongly than the CO and NH groups in other molecular systems containing the same NH···OC hydrogen-bond motif. We attribute this enhancement of the NH/CO anharmonic interaction to a cooperative effect, by which the two ring−thread hydrogen bonds sharing a hydrogen-bond acceptor mutually amplify each other. The relaxation dynamics of the NH/CO cross peaks has also been investigated. Surprisingly, the NH/CO cross peak observed upon exciting the NH-stretch mode decays much more slowly than the corresponding diagonal NH-stretch peak. This can be explained by the presence of an intermediate state that becomes populated in the NH-stretch vibrational relaxation and that is coupled to the CO-stretch mode. Our results demonstrate that NH/CO heterovibrational 2D-IR spectroscopy is well suited to observe the elementary hydrogen-bond making and breaking steps involved in the motion of rotaxane-based molecular devices.

Building management and planning professionals utilize database systems for administrative support, but these systems are inadequate for conveying architectural plans. In this article we describe the so-called Virtual Maquette that was developed at the Eindhoven University of Technology for the board of the University. The Virtual Maquette consists of a vertical display for 3D view and information of building stock, and an interactive horizontal display for manipulation of view and information. Interaction is implemented using infrared tracking of devices that are positioned on the desktop with the projected plan view. Through this interface the states of the buildings can be inspected at different periods in history and in the future. The support of multiple devices in a single environment is a technical challenge, but it provides a new interaction method for non-technical persons.