Current approaches and challenges of sample preparation procedures for the safety assessment of paper and cardboard food contact materials: A comprehensive review.

In the European Union (EU), Regulation (EC) 1935/2004 provides a harmonized legal EU framework and sets out the general principles for safety and inertness for all Food Contact Materials (FCMs) and Food Contact Articles. From a food safety point of view, however, specific EU legislation for paper and cardboard FCMs is lacking, while at Member State level, national legislation differs among countries. More than 11,000 chemicals have been identified in all types of FCMs, most of them without any information on toxicity or migration potential from FCM to food. The present review shows a wide variability of protocols, approaches, and conditions used in scientific studies, which are difficult to compare. In this regard, procedures and conditions laid down in EU legislation for plastics and European Standards (EN protocols) may serve as a good basis for the future sample preparation procedures in the framework of paper and cardboard FCMs safety assessment. Challenges on sample preparation procedures are presented involving the interlinked steps of sample preparation, conditions used and their impact in chemical analysis and in vitro bioassay testing. Currently, there is no general consensus on the criteria for structuring, evaluating, and tuning sample preparation procedures for paper and cardboard FCMs. For this purpose, a set of modified criteria and a decision tree are proposed based on the literature. Along this, mass transfer processes occurring in paper and cardboard FCMs and parameters affecting chemical migration need to be accounted for prior to reaching general consensus on criteria for sample preparation procedures.

Acute Effects of Dietary Nitrate on Exercise Tolerance, Muscle Oxygenation, and Cardiovascular Function in Patients With Peripheral Arterial Disease.

Previous studies have used supplements to increase dietary nitrate intake in clinical populations. Little is known about whether effects can also be induced through vegetable consumption. Therefore, the aim of this study was to assess the impact of dietary nitrate, through nitrate-rich vegetables (NRV) and beetroot juice (BRJ) supplementation, on plasma nitrate and nitrite concentrations, exercise tolerance, muscle oxygenation, and cardiovascular function in patients with peripheral arterial disease. In a randomized crossover design, 18 patients with peripheral arterial disease (age: 73 ± 8 years) followed a nitrate intake protocol (∼6.5 mmol) through the consumption of NRV, BRJ, and nitrate-depleted BRJ (placebo). Blood samples were taken, blood pressure and arterial stiffness were measured in fasted state and 150 min after intervention. Each intervention was followed by a maximal walking exercise test to determine claudication onset time and peak walking time. Gastrocnemius oxygenation was measured by near-infrared spectroscopy. Blood samples were taken and blood pressure was measured 10 min after exercise. Mean plasma nitrate and nitrite concentrations increased (nitrate; Time × Intervention interaction; p < .001), with the highest concentrations after BRJ (494 ± 110 µmol/L) compared with NRV (202 ± 89 µmol/L) and placebo (80 ± 19 µmol/L; p < .001). Mean claudication onset time and peak walking time did not differ between NRV (413 ± 187 s and 745 ± 220 s, respectively), BRJ (392 ± 154 s and 746 ± 176 s), and placebo (403 ± 176 s and 696 ± 222 s) (p = .762 and p = .165, respectively). Gastrocnemius oxygenation, blood pressure, and arterial stiffness were not affected by the intervention. NRV and BRJ intake markedly increase plasma nitrate and nitrite, but this does not translate to improved exercise tolerance, muscle oxygenation, and/or cardiovascular function.

Possible Adverse Effects of Food Additive E171 (Titanium Dioxide) Related to Particle Specific Human Toxicity, Including the Immune System.

Titanium dioxide (TiO2) is used as a food additive (E171) and can be found in sauces, icings, and chewing gums, as well as in personal care products such as toothpaste and pharmaceutical tablets. Along with the ubiquitous presence of TiO2 and recent insights into its potentially hazardous properties, there are concerns about its application in commercially available products. Especially the nano-sized particle fraction (<100 nm) of TiO2 warrants a more detailed evaluation of potential adverse health effects after ingestion. A workshop organized by the Dutch Office for Risk Assessment and Research (BuRO) identified uncertainties and knowledge gaps regarding the gastrointestinal absorption of TiO2, its distribution, the potential for accumulation, and induction of adverse health effects such as inflammation, DNA damage, and tumor promotion. This review aims to identify and evaluate recent toxicological studies on food-grade TiO2 and nano-sized TiO2 in ex-vivo, in-vitro, and in-vivo experiments along the gastrointestinal route, and to postulate an Adverse Outcome Pathway (AOP) following ingestion. Additionally, this review summarizes recommendations and outcomes of the expert meeting held by the BuRO in 2018, in order to contribute to the hazard identification and risk assessment process of ingested TiO2.

Ultrafast Two-Electron Transfer in a CdS Quantum Dot-Extended-Viologen Cyclophane Complex.

Time-resolved optical spectroscopies reveal multielectron transfer from the biexcitonic state of a CdS quantum dot to an adsorbed tetracationic compound cyclobis(4,4'-(1,4-phenylene) bipyridin-1-ium-1,4-phenylene-bis(methylene)) (ExBox(4+)) to form both the ExBox(3+•) and the doubly reduced ExBox(2(+•)) states from a single laser pulse. Electron transfer in the single-exciton regime occurs in 1 ps. At higher excitation powers the second electron transfer takes ∼5 ps, which leads to a mixture of redox states of the acceptor ligand. The doubly reduced ExBox(2(+•)) state has a lifetime of ∼10 ns, while CdS(+•):ExBox(3+•) recombines with multiple time constants, the longest of which is ∼300 µs. The long-lived charge separation and ability to accumulate multiple charges on ExBox(4+) demonstrate the potential of the CdS:ExBox(4+) complex to serve as a platform for two-electron photocatalysis.

Ultrafast photodriven intramolecular electron transfer from an iridium-based water-oxidation catalyst to perylene diimide derivatives.

Photodriving the activity of water-oxidation catalysts is a critical step toward generating fuel from sunlight. The design of a system with optimal energetics and kinetics requires a mechanistic understanding of the single-electron transfer events in catalyst activation. To this end, we report here the synthesis and photophysical characterization of two covalently bound chromophore-catalyst electron transfer dyads, in which the dyes are derivatives of the strong photooxidant perylene-3,4:9,10-bis(dicarboximide) (PDI) and the molecular catalyst is the Cp*Ir(ppy)Cl metal complex, where ppy = 2-phenylpyridine. Photoexcitation of the PDI in each dyad results in reduction of the chromophore to PDI(•-) in less than 10 ps, a process that outcompetes any generation of (3*)PDI by spin-orbit-induced intersystem crossing. Biexponential charge recombination largely to the PDI-Ir(III) ground state is suggestive of multiple populations of the PDI(•-)-Ir(IV) ion-pair, whose relative abundance varies with solvent polarity. Electrochemical studies of the dyads show strong irreversible oxidation current similar to that seen for model catalysts, indicating that the catalytic integrity of the metal complex is maintained upon attachment to the high molecular weight photosensitizer.

Residency and movement patterns of Arctic charr Salvelinus alpinus relative to major estuaries.

Estuarine residency and marine movements of 43 anadromous Arctic charr Salvelinus alpinus (mean ± s.d. fork length = 523 ± 97 mm) were examined using acoustic tracking in inner Frobisher Bay (IFB; 63° N; 68° W), Canada, from July to September 2008 and 2009. A mean ± s.d. migration duration of 63 ± 7 days occurred from late June to early September. Detected S. alpinus were either continuously (maximum 34 days) or intermittently present in estuarine zones, on average residing approximately one third of time tracked and returning once every 9 days. Significantly higher estuarine residency during the final 15 migration days suggested that a transition phase may occur prior to freshwater re-entry. Low travel rates during flood tide suggested individuals staged before accessing intertidal and estuarine zones. Although the two main estuaries were c. 22 km apart, 19% of tagged individuals used both. Individuals remained relatively close to freshwater overwintering systems, although late-migration inter-estuarine movements may have indicated natal homing. Approximately half of the individuals exhibited extra-estuarine travel, mostly during mid-migration, but remained within 3 km of shore ranging < 30 km straight line distance (SLD) of either estuary. It was concluded that IFB S. alpinus (1) spent a significant portion of their migration within or adjacent to the estuaries and (2) had a restricted marine distribution within 30 km SLD of the river mouths.

Photoinduced electron transfer within a zinc porphyrin-cyclobis(paraquat-p-phenylene) donor-acceptor dyad.

Understanding the mechanism of efficient photoinduced electron-transfer processes is essential for developing molecular systems for artificial photosynthesis. Towards this goal, we describe the synthesis of a donor-acceptor dyad comprising a zinc porphyrin donor and a tetracationic cyclobis(paraquat-p-phenylene) (CBPQT(4+) ) acceptor. The X-ray crystal structure of the dyad reveals the formation of a dimeric motif through the intermolecular coordination between the triazole nitrogen and the central Zn metal of two adjacent units of the dyad. Photoinduced electron transfer within the dyad in MeCN was investigated by femtosecond and nanosecond transient absorption spectroscopy, as well as by transient EPR spectroscopy. Photoexcitation of the dyad produced a weakly coupled ZnP(+.) -CBPQT(3+.) spin-correlated radical-ion pair having a τ=146 ns lifetime and a spin-spin exchange interaction of only 0.23 mT. The long radical-ion-pair lifetime results from weak donor-acceptor electronic coupling as a consequence of having nine bonds between the donor and the acceptor, and the reduction in reorganization energy for electron transfer caused by charge dispersal over both paraquat units within CBPQT(3+.) .

The association between physical activity and liver fat after five years of follow-up in a primary prevention multi-ethnic cohort.

OBJECTIVE: Excess liver fat (LF) is associated with dyslipidemia, insulin resistance and cardiovascular disease. Evidence suggests that there is an independent relationship between physical activity (PA) and LF although little is known of the role of PA intensity in reducing LF. The purpose was to evaluate whether meeting PA guidelines, the amount of PA and the intensity of PA at baseline were associated with LF after five-years. METHODS: Men and women (n=478) living in Vancouver, Canada of Aboriginal, Chinese, European or South Asian background completed baseline measurements in 2004-2005. Liver fat was assessed using CT scans at 5-year follow-up, and PA using a PA questionnaire at baseline as well as demographics and anthropometry. RESULTS: In separate unadjusted models, meeting moderate-vigorous PA (MVPA) guidelines (p=0.009), vigorous PA (p=0.002) and MVPA (p=0.017) but not moderate PA (p=0.068) was predictive of LF at five years (p=0.009). In multiple linear regression models, when adjusted for covariates, meeting MVPA guidelines and MVPA with LF at five years was no longer significant (p>0.05) while vigorous PA remained significant (p=0.021). CONCLUSION: Meeting PA guidelines through MVPA may not be adequate to prevent the accumulation of LF and PA guidelines may require revision. Vigorous PA should be encouraged to prevent LF accumulation.

Electron transfer and multi-electron accumulation in ExBox4⁺.

Molecules capable of accepting and storing multiple electrons are crucial components of artificial photosynthetic systems designed to drive catalysts, such as those used to reduce protons to hydrogen. ExBox(4+), a boxlike cyclophane comprising two π-electron-poor extended viologen units tethered at both ends by two p-xylylene linkers, has been shown previously to accept an electron through space from a photoexcited guest. Herein is an investigation of an alternate, through-bond intramolecular electron-transfer pathway involving ExBox(4+) using a combination of transient absorption and femtosecond stimulated Raman spectroscopy (FSRS). Upon photoexcitation of ExBox(4+), an electron is transferred from one of the p-xylylene linkers to one of the extended viologen units in ca. 240 ps and recombines in ca. 4 ns. A crystal structure of the doubly reduced species ExBox(2+) was obtained.

Plant-based food contact materials: presence of hazardous substances.

As a result of the European Single Use Plastic Directive and as part of the transition to a circular economy, plastic food contact materials (FCMs) are being replaced, often by renewable plant-based materials. This research aimed to identify which chemical substances are present in plant-based materials. In 2022 a total of 28 samples of the latter materials from the Dutch market were analysed for 313 active substances from plant protection products, 47 per- and polyfluoralkyl substances (PFASs) and 27 heavy metals and other elements. Ten samples contained plant protection products that are not authorised in the EU. Most materials contained PFASs at trace or even high levels. Three out of four investigated sugar cane materials contained 6:2 fluorotelomer alcohol at levels up to 1.7 mg/kg. High contents of aluminium, manganese, iron, zinc, and barium were found. Other heavy metals, such as arsenic, lead and mercury were found in relatively low contents. A broad GC-MS screening was performed, which revealed the presence of plant extractable, plasticisers, antioxidants and hydrocarbons, which were not all authorised for FCMs, but may be present as non-intentionally added substances.

Relative unidirectional translation in an artificial molecular assembly fueled by light.

Motor molecules present in nature convert energy inputs, such as a chemical fuel or incident photons of light, into directed motion and force biochemical systems away from thermal equilibrium. The ability not only to control relative movements of components in molecules but also to drive their components preferentially in one direction relative to each other using versatile stimuli is one of the keys to future technological applications. Herein, we describe a wholly synthetic small-molecule system that, under the influence of chemical reagents, electrical potential, or visible light, undergoes unidirectional relative translational motion. Altering the redox state of a cyclobis(paraquat-p-phenylene) ring simultaneously (i) inverts the relative heights of kinetic barriers presented by the two termini--one a neutral 2-isopropylphenyl group and the other a positively charged 3,5-dimethylpyridinium unit--of a constitutionally asymmetric dumbbell, which can impair the threading/dethreading of a [2]pseudorotaxane, and (ii) controls the ring's affinity for a 1,5-dioxynaphthalene binding site located in the dumbbell's central core. The formation and subsequent dissociation of the [2]pseudorotaxane by passage of the ring over the neutral and positively charged termini of the dumbbell component in one, and only one, direction relatively defined has been demonstrated by (i) spectroscopic ((1)H NMR and UV/vis) means and cyclic voltammetry as well as with (ii) DFT calculations and by (iii) comparison with control compounds in the shape of constitutionally symmetrical [2]pseudorotaxanes, one with two positively charged ends and the other with two neutral ends. The operation of the system relies solely on reversible, yet stable, noncovalent bonding interactions. Moreover, in the presence of a photosensitizer, visible-light energy is the only fuel source that is needed to drive the unidirectional molecular translation, making it feasible to repeat the operation numerous times without the buildup of byproducts.

Direct measurement of lattice dynamics and optical phonon excitation in semiconductor nanocrystals using femtosecond stimulated Raman spectroscopy.

We report femtosecond stimulated Raman spectroscopy measurements of lattice dynamics in semiconductor nanocrystals and characterize longitudinal optical (LO) phonon production during confinement-enhanced, ultrafast intraband relaxation. Stimulated Raman signals from unexcited CdSe nanocrystals produce a spectral shape similar to spontaneous Raman signals. Upon photoexcitation, stimulated Raman amplitude decreases owing to experimentally resolved ultrafast phonon generation rates within the lattice. We find a ∼600 fs, particle-size-independent depletion time attributed to hole cooling, evidence of LO-to-acoustic down-conversion, and LO phonon mode softening.

Ultrafast conformational dynamics of electron transfer in ExBox4+⊂perylene.

Multielectron acceptors are essential components for artificial photosynthetic systems that must deliver multiple electrons to catalysts for solar fuels applications. The recently developed boxlike cyclophane incorporating two extended viologen units joined end-to-end by two p-phenylene linkers-namely, ExBox(4+)-has a potential to be integrated into light-driven systems on account of its ability to complex with π-electron-rich guests such as perylene, which has been utilized to great extent in many light-harvesting applications. Photodriven electron transfer to ExBox(4+) has not previously been investigated, however, and so its properties, following photoreduction, are largely unknown. Here, we investigate the structure and energetics of the various accessible oxidation states of ExBox(4+) using a combination of spectroscopy and computation. In particular, we examine photoinitiated electron transfer from perylene bound within ExBox(4+) (ExBox(4+)⊂perylene) using visible and near-infrared femtosecond transient absorption (fsTA) spectroscopy. The structure and conformational relaxation dynamics of ExBox(3+)⊂perylene(+) are observed with femtosecond stimulated Raman spectroscopy (FSRS). From the fsTA and FSRS spectra, we observe that the central p-phenylene spacer in one of the extended viologen units on one side of the cyclophane becomes more coplanar with its neighboring pyridinium units over the first ∼5 ps after photoreduction. When the steady-state structure of chemically generated ExBox(2+) is investigated using Raman spectroscopy, it is found to have the central p-phenylene rings in both of its extended viologen units rotated to be more coplanar with their neighboring pyridinium units, further underscoring the importance of this subunit in the stabilization of the reduced states of ExBox(4+).

Plasmonic bowtie nanolaser arrays.

Plasmonic lasers exploit strong electromagnetic field confinement at dimensions well below the diffraction limit. However, lasing from an electromagnetic hot spot supported by discrete, coupled metal nanoparticles (NPs) has not been explicitly demonstrated to date. We present a new design for a room-temperature nanolaser based on three-dimensional (3D) Au bowtie NPs supported by an organic gain material. The extreme field compression, and thus ultrasmall mode volume, within the bowtie gaps produced laser oscillations at the localized plasmon resonance gap mode of the 3D bowties. Transient absorption measurements confirmed ultrafast resonant energy transfer between photoexcited dye molecules and gap plasmons on the picosecond time scale. These plasmonic nanolasers are anticipated to be readily integrated into Si-based photonic devices, all-optical circuits, and nanoscale biosensors.

Opportunities for Regulatory Authorities to Assess Animal-Based Measures at the Slaughterhouse Using Sensor Technology and Artificial Intelligence: A Review.

Animal-based measures (ABMs) are the preferred way to assess animal welfare. However, manual scoring of ABMs is very time-consuming during the meat inspection. Automatic scoring by using sensor technology and artificial intelligence (AI) may bring a solution. Based on review papers an overview was made of ABMs recorded at the slaughterhouse for poultry, pigs and cattle and applications of sensor technology to measure the identified ABMs. Also, relevant legislation and work instructions of the Dutch Regulatory Authority (RA) were scanned on applied ABMs. Applications of sensor technology in a research setting, on farm or at the slaughterhouse were reported for 10 of the 37 ABMs identified for poultry, 4 of 32 for cattle and 13 of 41 for pigs. Several applications are related to aspects of meat inspection. However, by European law meat inspection must be performed by an official veterinarian, although there are exceptions for the post mortem inspection of poultry. The examples in this study show that there are opportunities for using sensor technology by the RA to support the inspection and to give more insight into animal welfare risks. The lack of external validation for multiple commercially available systems is a point of attention.

Mixture effects of tetrodotoxin (TTX) and drugs targeting voltage-gated sodium channels on spontaneous neuronal activity in vitro.

Tetrodotoxin (TTX) potently inhibits TTX-sensitive voltage-gated sodium (NaV) channels in nerve and muscle cells, potentially resulting in depressed neurotransmission, paralysis and death from respiratory failure. Since a wide range of pharmaceutical drugs is known to also act on NaV channels, the use of medicines could predispose individuals to a higher susceptibility towards TTX toxicity. We therefore first assessed the inhibitory effect of selected medicines that act on TTX-sensitive (Riluzole, Chloroquine, Fluoxetine, Valproic acid, Lamotrigine, Lidocaine) and TTX-resistant (Carbamazepine, Mexiletine, Flecainide) NaV channels on spontaneous neuronal activity of rat primary cortical cultures grown on microelectrode arrays (MEA). After establishing concentration-effect curves, binary mixtures of the medicines with TTX at calculated NOEC, IC20 and IC50 values were used to determine if pharmacodynamic interactions occur between TTX and these drugs on spontaneous neuronal activity. At IC20 and IC50 values, all medicines significantly increased the inhibitory effect of TTX on spontaneous neuronal activity of rat cortical cells in vitro. Subsequent experiments using human iPSC-derived neuronal co-cultures grown on MEAs confirmed the ability of selected medicines (Carbamazepine, Flecainide, Riluzole, Lidocaine) to inhibit spontaneous neuronal activity. Despite the need for additional experiments using human iPSC-derived neuronal co-cultures, our combined data already highlight the importance of identifying and including vulnerable risk groups in the risk assessment of TTX.

Electron transfer within self-assembling cyclic tetramers using chlorophyll-based donor-acceptor building blocks.

The synthesis and photoinduced charge transfer properties of a series of Chl-based donor-acceptor triad building blocks that self-assemble into cyclic tetramers are reported. Chlorophyll a was converted into zinc methyl 3-ethylpyrochlorophyllide a (Chl) and then further modified at its 20-position to covalently attach a pyromellitimide (PI) acceptor bearing a pyridine ligand and one or two naphthalene-1,8:4,5-bis(dicarboximide) (NDI) secondary electron acceptors to give Chl-PI-NDI and Chl-PI-NDI(2). The pyridine ligand within each ambident triad enables intermolecular Chl metal-ligand coordination in dry toluene, which results in the formation of cyclic tetramers in solution, as determined using small- and wide-angle X-ray scattering at a synchrotron source. Femtosecond and nanosecond transient absorption spectroscopy of the monomers in toluene-1% pyridine and the cyclic tetramers in toluene shows that the selective photoexcitation of Chl results in intramolecular electron transfer from (1*)Chl to PI to form Chl(+•)-PI(-•)-NDI and Chl(+•)-PI(-•)-NDI(2). This initial charge separation is followed by a rapid charge shift from PI(-•) to NDI and subsequent charge recombination of Chl(+•)-PI-NDI(-•) and Chl(+•)-PI-(NDI)NDI(-•) on a 5-30 ns time scale. Charge recombination in the Chl-PI-NDI(2) cyclic tetramer (τ(CR) = 30 ± 1 ns in toluene) is slower by a factor of 3 relative to the monomeric building blocks (τ(CR) = 10 ± 1 ns in toluene-1% pyridine). This indicates that the self-assembly of these building blocks into the cyclic tetramers alters their structures in a way that lengthens their charge separation lifetimes, which is an advantageous strategy for artificial photosynthetic systems.

Exponential distance dependence of photoinitiated stepwise electron transfer in donor-bridge-acceptor molecules: implications for wirelike behavior.

Donor-bridge-acceptor (D-B-A) systems in which a 3,5-dimethyl-4-(9-anthracenyl)julolidine (DMJ-An) chromophore and a naphthalene-1,8:4,5-bis(dicarboximide) (NI) acceptor are linked by oligomeric 2,7-fluorenone (FN(n)) bridges (n = 1-3) have been synthesized. Selective photoexcitation of DMJ-An quantitatively produces DMJ(+•)-An(-•), and An(-•) acts as a high-potential electron donor. Femtosecond transient absorption spectroscopy in the visible and mid-IR regions showed that electron transfer occurs quantitatively in the sequence: DMJ(+•)-An(-•)-FN(n)-NI → DMJ(+•)-An-FN(n)(-•)-NI → DMJ(+•)-An-FN(n)-NI(-•). The charge-shift reaction from An(-•) to NI(-•) exhibits an exponential distance dependence in the nonpolar solvent toluene with an attenuation factor (ß) of 0.34 Å(-1), which would normally be attributed to electron tunneling by the superexchange mechanism. However, the FN(n)(-•) radical anion was directly observed spectroscopically as an intermediate in the charge-separation mechanism, thereby demonstrating conclusively that the overall charge separation involves the incoherent hopping (stepwise) mechanism. Kinetic modeling of the data showed that the observed exponential distance dependence is largely due to electron injection onto the first FN unit followed by charge hopping between the FN units of the bridge biased by the distance-dependent electrostatic attraction of the two charges in D(+•)-B(-•)-A. This work shows that wirelike behavior does not necessarily result from building a stepwise, energetically downhill redox gradient into a D-B-A molecule.

Intersystem crossing involving strongly spin exchange-coupled radical ion pairs in donor-bridge-acceptor molecules.

Intersystem crossing involving photogenerated strongly spin exchange-coupled radical ion pairs in a series of donor-bridge-acceptor molecules was examined. These molecules have a 3,5-dimethyl-4-(9-anthracenyl)-julolidine (DMJ-An) donor either connected directly or connected by a phenyl bridge (Ph), to pyromellitimide (PI), 1 and 2, respectively, or naphthalene-1,8:4,5-bis(dicarboximide) (NI) acceptors, 3 and 4, respectively. Femtosecond transient optical absorption spectroscopy shows that photodriven charge separation produces DMJ(+•)-PI(-•) or DMJ(+•)-NI(-•) quantitatively in 1-4 (τ(CS) ≤ 10 ps), and that charge recombination occurs with τ(CR) = 268 and 158 ps for 1 and 3, respectively, and with τ(CR) = 2.6 and 10 ns for 2 and 4, respectively. Magnetic field effects (MFEs) on the neutral triplet state yield produced by charge recombination were used to measure the exchange coupling (2J) between DMJ(+•) and PI(-•) or NI(-•), giving 2J > 600 mT for 1-3 and 2J = 170 mT for 4. Time-resolved electron paramagnetic resonance (TREPR) spectroscopy revealed that the formation of (3)*An upon charge recombination occurs by spin-orbit charge transfer intersystem crossing (SOCT-ISC) and/or radical-pair intersystem crossing (RP-ISC) mechanisms with the magnitude of 2J determining which triplet formation mechanism dominates. SOCT-ISC is the exclusive triplet formation mechanism in 1-3, whereas both RP-ISC and SOCT-ISC are active for 4. The triplet sublevels populated by SOCT-ISC in 1-4 depend on the donor-acceptor geometry in the charge separated state. This is consistent with the fact that the SOCT-ISC mechanism requires the relevant donor and acceptor orbitals to be nearly perpendicular, so that electron transfer results in a large orbital angular momentum change that must be compensated by a fast spin flip to conserve overall system angular momentum.

Enhancing the use of exposure science across EU chemical policies as part of the European Exposure Science Strategy 2020-2030.

BACKGROUND: A scientific framework on exposure science will boost the multiuse of exposure knowledge across EU chemicals-related policies and improve risk assessment, risk management and communication across EU safety, security and sustainability domains. OBJECTIVE: To stimulate public and private actors to align and strengthen the cross-policy adoption of exposure assessment data, methods and tools across EU legislation. METHODS: By mapping and analysing the EU regulatory landscape making use of exposure information, policy and research challenges and key areas of action are identified and translated into opportunities enhancing policy and scientific efficiency. RESULTS: Identified key areas of actions are to develop a common scientific exposure assessment framework, supported by baseline acceptance criteria and a shared knowledge base enhancing exchangeability and acceptability of exposure knowledge within and across EU chemicals-related policies. Furthermore, such framework will improve communication and management across EU chemical safety, security and sustainability policies comprising sourcing, manufacturing and global trade of goods and waste management. In support of building such a common framework and its effective use in policy and industry, exposure science innovation needs to be better embedded along the whole policymaking cycle, and be integrated into companies' safety and sustainability management systems. This will help to systemically improve regulatory risk management practices. SIGNIFICANCE: This paper constitutes an important step towards the implementation of the EU Green Deal and its underlying policy strategies, such as the Chemicals Strategy for Sustainability.