A Photodynamic and Photochemotherapeutic Platinum-Iridium Charge-Transfer Conjugate for Anticancer Therapy.

The novel hetero-dinuclear complex trans,trans,trans-[PtIV(py)2(N3)2(OH)(µ-OOCCH2CH2CONHCH2-bpyMe)IrIII(ppy)2]Cl (Pt-Ir), exhibits charge transfer between the acceptor photochemotherapeutic Pt(IV) (Pt-OH) and donor photodynamic Ir(III) (Ir-NH2) fragments. It is stable in the dark, but undergoes photodecomposition more rapidly than the Pt(IV) parent complex (Pt-OH) to generate Pt(II) species, an azidyl radical and 1O2. The Ir(III)* excited state, formed after irradiation, can oxidise NADH to NAD⋅ radicals and NAD+. Pt-Ir is highly photocytotoxic towards cancer cells with a high photocytotoxicity index upon irradiation with blue light (465 nm, 4.8 mW/cm2), even with short light-exposure times (10-60 min). In contrast, the mononuclear Pt-OH and Ir-NH2 subunits and their simple mixture are much less potent. Cellular Pt accumulation was higher for Pt-Ir compared to Pt-OH. Irradiation of Pt-Ir in cancer cells damages nuclei and releases chromosomes. Synchrotron-XRF revealed ca. 4× higher levels of intracellular platinum compared to iridium in Pt-Ir treated cells under dark conditions. Luminescent Pt-Ir distributes over the whole cell and generates ROS and 1O2 within 1 h of irradiation. Iridium localises strongly in small compartments, suggestive of complex cleavage and excretion via recycling vesicles (e.g. lysosomes). The combination of PDT and PACT motifs in one molecule, provides Pt-Ir with a novel strategy for multimodal phototherapy.

Effects of environmental diversity on exploration and learning: The case of bilingualism.

Bilingual environments provide a commonplace example of increased complexity and uncertainty. Learning multiple languages entails mastery of a larger and more variable range of sounds, words, syntactic structures, pragmatic conventions, and more complex mapping of linguistic information to objects in the world. Recent research suggests that bilingual learners demonstrate fundamental variation in how they explore and learn from their environment, which may derive from this increased complexity. In particular, the increased complexity and variability of bilingual environments may broaden the focus of learners' attention, laying a different attentional foundation for learning. In this review, we introduce a novel framework, with accompanying empirical evidence, for understanding how early learners may adapt to a more complex environment, drawing on bilingualism as an example. Three adaptations, each relevant to the demands of abstracting structure from a complex environment, are introduced. Each adaptation is discussed in the context of empirical evidence attesting to shifts in basic psychological processes in bilingual learners. This evidence converges on the notion that bilingual learners may explore their environment more broadly. Downstream consequences of broader sampling for perception and learning are discussed. Finally, recommendations for future research to expand the scientific narrative on the impact of diverse environments on learning are provided. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

An uneven distribution of strontium in the coccolithophore Scyphosphaera apsteinii revealed by nanoscale X-ray fluorescence tomography.

Coccolithophores are biogeochemically and ecologically important phytoplankton that produce a composite calcium carbonate-based exoskeleton - the coccosphere - comprised of individual platelets, known as coccoliths. Coccoliths are stunning examples of biomineralization; their formation featuring exceptional control over both biomineral chemistry and shape. Understanding how coccoliths are formed requires information about minor element distribution and chemical environment. Here, the first high-resolution 3D synchrotron X-ray fluorescence (XRF) mapping of a coccolith is presented, showing that the lopadoliths of Scyphosphaera apsteinii display stripes of different Sr concentration. The presence of Sr stripes is unaffected by elevated Sr in the culture medium, macro-nutrient concentration, and light intensity, indicating that the observed stripiness is an expression of the fundamental coccolith formation process in this species. Current Sr fractionation models, by contrast, predict an even Sr distribution and will have to be modified to account for this stripiness. Additionally, nano-XANES analyses show that Sr resides in a Ca site in the calcite lattice in both high and low Sr stripes, confirming a central assumption of current Sr fractionation models.

Toward Understanding the Environmental Risks of Combined Microplastics/Nanomaterials Exposures: Unveiling ZnO Transformations after Adsorption onto Polystyrene Microplastics in Environmental Solutions.

Over recent decades, there has been a dramatic increase in the manufacture of engineered nanomaterials, which has inevitably led to their environmental release. Zinc oxide (ZnO) is among the more abundant nanomaterial manufactured due to its advantageous properties, used for piezoelectric, semiconducting, and antibacterial purposes. Plastic waste is ubiquitous and may break down or delaminate into smaller microplastics, leaving open the question of whether these small polymers may alter the fate of ZnO through adsorption within aquatic media (tap-water and seawater). Here, scanning electron microscopy analysis confirms the effective Zn nano/microstructures adsorption onto polystyrene surfaces after only 24-h incubation in the aquatic media. After pre-aging the nanomaterials for 7-days in different environmental media, nanoprobe X-ray absorption near-edge spectroscopy analysis reveals significant ZnO transformation toward Zn-sulfide and Zn-phosphate. The interaction between a commercial ZnO-based sunscreen with polystyrene and a cleanser consumer containing microbeads with ZnO nanomaterials is also studied, revealing the adsorption of transformed Zn-species in the microplastics surfaces, highlighting the environmental relevancy of this work. Understanding the structural and functional impacts of the microplastics/ZnO complexes, and how they evolve, will provide insights into their chemical nature, stability, transformations, and fate, which is key to predicting their bioreactivity in the environment.

Bilingual infants readily orient to novel visual stimuli.

Bilingualism has been shown to modify infants' responses in a range of domains. In particular, early bilingual experience is associated with greater flexibility and openness in infant perception and learning. In this study, we investigated whether bilingual infants demonstrate more fundamental differences in how they explore their environment in ways that could contribute to greater openness. Specifically, we investigated whether bilingual infants orient more rapidly to new information. Capitalizing on a classic paradigm by Fantz (1964), monolingual and bilingual infants (5-6 months and 8-9 months) were simultaneously presented with familiar and novel stimuli. As they received increased exposure to the familiar and novel stimuli, monolingual infants demonstrated a null preference, followed by a novelty preference, as previously evidenced in Fantz's study. In contrast, an orientation toward novelty emerged more readily in bilingual infants. Characteristics of a bilingual environment that may modulate the allocation of attention toward novelty are discussed. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Does extended experience with other-race nannies predict racial bias in the preschool years?

Most existing studies on racial bias reduction have used short-term interracial interaction interventions with fleeting effects. The current natural experiment examined whether daily interactions with other-race nannies relate to reduced racial bias in the preschool years. We capitalized on a unique child-rearing situation in Singapore whereby children are often cared for by other-race nannies since infancy. Singaporean Chinese 3- to 6-year-olds (N = 100) completed explicit and implicit racial bias measures assessing their preferential bias favoring own-race adults over adults of their nannies' race. Differential findings were obtained for children's explicit and implicit racial bias. Extensiveness, but not mere presence, of other-race nanny experience was associated with lower levels of explicit racial bias in children. In contrast, neither presence nor extensiveness of other-race nanny experience was associated with children's implicit racial bias. Together, these findings suggest that long-term and extensive contact with an other-race caregiver could have subtle mitigating effects on children's explicit, but not implicit, racial bias.

Effects of face masks on language comprehension in bilingual children.

Due to the COVID-19 pandemic, many children receive language input through face coverings. The impact of face coverings for children's abilities to understand language remains unclear. Past research with monolingual children suggests that hearing words through surgical masks does not disrupt word recognition, but hearing words through transparent face shields proves more challenging. In this study, we investigated effects of different face coverings (surgical masks and transparent face shields) on language comprehension in bilingual children. Three-year-old English-Mandarin bilingual children (N = 28) heard familiar words in both English and Mandarin spoken through transparent face shields, surgical masks, and without masks. When tested in English, children recognized words presented without a mask and through a surgical mask, but did not recognize words presented with transparent face shields, replicating past findings with monolingual children. In contrast, when tested in Mandarin, children recognized words presented without a mask, through a surgical mask, and through a transparent face shield. Results are discussed in terms of specific properties of English and Mandarin that may elicit different effects for transparent face shields. Overall, the present findings suggest that face coverings, and in particular, surgical masks do not disrupt spoken word recognition in young bilingual children.

Differential phase contrast for quantitative imaging and spectro-microscopy at a nanoprobe beamline.

The interaction of a focused X-ray beam with a sample in a scanning probe experiment can provide a variety of information about the interaction volume. In many scanning probe experiments X-ray fluorescence (XRF) is supplemented with measurements of the transmitted or scattered intensity using a pixelated detector. The automated extraction of different signals from an area pixelated detector is described, in particular the methodology for extracting differential phase contrast (DPC) is demonstrated and different processing methods are compared across a range of samples. The phase shift of the transmitted X-ray beam by the sample, extracted from DPC, is also compared with ptychography measurements to provide a qualitative and quantitative comparison. While ptychography produces a superior image, DPC can offer a simple, flexible method for phase contrast imaging which can provide fast results and feedback during an experiment; furthermore, for many science problems, such as registration of XRF in a lighter matrix, DPC can provide sufficient information to meet the experimental aims. As the DPC technique is a quantitative measurement, it can be expanded to spectroscopic studies and a demonstration of DPC for spectro-microscopy measurements is presented. Where ptychography can separate the absorption and phase shifts by the sample, quantitative interpretation of a DPC image or spectro-microscopy signal can only be performed directly when absorption is negligible or where the absorption contribution is known and the contributions can be fitted.

Asymmetrical responding to male versus female other-race categories in 9- to 12-month-old infants.

Faces can be categorized along various dimensions including gender or race, an ability developing in infancy. Infant categorization studies have focused on facial attributes in isolation, but the interaction between these attributes remains poorly understood. Experiment 1 examined gender categorization of other-race faces in 9- and 12-month-old White infants. Nine- and 12-month-olds were familiarized with Asian male or female faces, and tested with a novel exemplar from the familiarized category paired with a novel exemplar from a novel category. Both age groups showed novel category preferences for novel Asian female faces after familiarization with Asian male faces, but showed no novel category preference for novel Asian male faces after familiarization with Asian female faces. This categorization asymmetry was not due to a spontaneous preference hindering novel category reaction (Experiment 2), and both age groups displayed difficulty discriminating among male, but not female, other-race faces (Experiment 3). These results indicate that category formation for male other-race faces is mediated by categorical perception. Overall, the findings suggest that even by 12 months of age, infants are not fully able to form gender category representations of other-race faces, responding categorically to male, but not female, other-race faces.

Undersampling raster scans in spectromicroscopy for a reduced dose and faster measurements.

Combinations of spectroscopic analysis and microscopic techniques are used across many disciplines of scientific research, including material science, chemistry and biology. X-ray spectromicroscopy, in particular, is a powerful tool used for studying chemical state distributions at the micro and nano scales. With the beam fixed, a specimen is typically rastered through the probe with continuous motion and a range of multimodal data is collected at fixed time intervals. The application of this technique is limited in some areas due to: long scanning times to collect the data, either because of the area/volume under study or the compositional properties of the specimen; and material degradation due to the dose absorbed during the measurement. In this work, we propose a novel approach for reducing the dose and scanning times by undersampling the raster data. This is achieved by skipping rows within scans and reconstructing the x-ray spectromicroscopic measurements using low-rank matrix completion. The new method is robust and allows for 5 to 6-fold reduction in sampling. Experimental results obtained on real data are illustrated.

Development and Validation of Empirical Models to Predict Metal Additively Manufactured Part Density and Surface Roughness from Powder Characteristics.

Metal additive manufacturing (AM) processes, viz laser powder bed fusion (L-PBF), are becoming an increasingly popular manufacturing tool for a range of industries. The powder material used in L-PBF is costly, and it is rare for a single batch of powder to be used in a single L-PBF build. The un-melted powder material can be sieved and recycled for further builds, significantly increasing its utilisation. Previous studies conducted by the authors have tracked the effect of both powder recycling and powder rejuvenation processes on the powder characteristics and L-PBF part properties. This paper investigates the use of multiple linear regression to build empirical models to predict the part density and surface roughness of 316L stainless steel parts manufactured using recycled and rejuvenated powder based on the powder characteristics. The developed models built on the understanding of the effect of powder characteristics on the part properties. The developed models were found to be capable of predicting the part density and surface roughness to within ±0.02% and ±0.5 Ra, respectively. The models developed enable L-PBF operators to input powder characteristics and predict the expected part density and surface roughness.

Infant sensitivity to age-based social categories in full-body displays.

This study examined 3.5- and 6-month-old infants' visual preferences for individuals from different age groups: adults versus infants. Unlike previous studies that only studied faces, here we included bodies, which are as frequent as faces in our environment, and highly salient, and in consequence, may play a role in identifying social categories and driving social preferences. In particular, we studied three salient dimensions along which individuals of different ages differ: body length, body typology, and face typology. In Experiment 1, adult and infant stimuli were presented in real proportions, differing both in body length and face typology, and infants preferred the adult stimuli. Experiment 2 demonstrated that given identical adult stimuli, which differ only in body length, infants attended more to the longer stimuli. In Experiment 3, infant and adult stimuli were matched on body length with the infant stimuli having larger heads, and infants preferred the infant stimuli. Experiment 4 measured infant visual preference for infant or adult bodies in the absence of face information, and found that 4-month-olds attended more to the infant bodies. Experiment 5 measured infants' sensitivity to matching or mismatching faces and bodies based on age, and infants demonstrated a preference for the incongruent stimuli (i.e., adult head with an infant body). Altogether these studies show that while face typology and body size are main drivers of infant visual preference for adults, when body typology information is provided for bodies matched in size, infant preference shifts towards their peers. Thus, our results suggest that infants have early developing age-based body representations, and that body information shifts their pattern of visual behavior from a visual preference for adult faces, to a visual preference for full-body peers.

The Delta Robot-A long travel nano-positioning stage for scanning x-ray microscopy.

A new stage design concept, the Delta Robot, is presented, which is a parallel kinematic design for scanning x-ray microscopy applications. The stage employs three orthogonal voice coils, which actuate parallelogram flexures. The design has a 3 mm travel range and achieves rms position jitter, integrated from 1 Hz to 1 kHz, of 2.8 and 1.3 nm perpendicular to the beam and 5.6 nm along the beam direction with loads up to 350 g. The Delta Robot design process used a mechatronics approach of iterative modeling and simulation to develop the system and validate performance. The design considerations, design process, stability, and operational performance on the hard x-ray nanoprobe at Diamond Light Source are presented.

A cell design for correlative hard X-ray nanoprobe and electron microscopy studies of catalysts under in situ conditions.

To improve the understanding of catalysts, and ultimately the ability to design better materials, it is crucial to study them during their catalytic active states. Using in situ or operando conditions allows insights into structure-property relationships, which might not be observable by ex situ characterization. Spatially resolved X-ray fluorescence, X-ray diffraction and X-ray absorption near-edge spectroscopy are powerful tools to determine structural and electronic properties, and the spatial resolutions now achievable at hard X-ray nanoprobe beamlines make them an ideal complement to high-resolution transmission electron microscopy studies in a multi-length-scale analysis approach. The development of a system to enable the use of a commercially available gas-cell chip assembly within an X-ray nanoprobe beamline is reported here. The novel in situ capability is demonstrated by an investigation of the redox behaviour of supported Pt nanoparticles on ceria under typical lean and rich diesel-exhaust conditions; however, the system has broader application to a wide range of solid-gas reactions. In addition the setup allows complimentary in situ transmission electron microscopy and X-ray nanoprobe studies under identical conditions, with the major advantage compared with other systems that the exact same cell can be used and easily transferred between instruments. This offers the exciting possibility of studying the same particles under identical conditions (gas flow, pressure, temperature) using multiple techniques.

Effects of interracial experience on the race preferences of infants.

Over their first year of life, infants express visual preferences for own- versus other-race faces. This developmental transition has primarily been investigated in monoracial societies where infants have limited personal or societal contact with other races. We investigated whether previously reported visual preferences for race generalize to a multiracial society (i.e., Singapore). In addition, we investigated effects of caregiver race on visual preferences for race. In Experiment 1, race preferences were measured at 3, 6, and 9 months of age for own-race (Chinese) versus other-race (Indian) faces in infants with no regular interaction with Indian-race individuals. Singaporean infants displayed a significant visual preference for Indian-race faces at each age group. Furthermore, infants raised with other-race caregivers demonstrated an age-related increase in other-race visual preferences. The visual preferences of infants for other-race faces were predicted by the extent of other-race contact. In Experiment 2, we confirmed that an other-race visual preference was not exclusive to Indian faces in a sample of 6-month-old Singaporean Chinese infants who demonstrated a similar other-race visual preference for Caucasian faces over Chinese faces. Findings are discussed in terms of the influence of other-race contact on visual preferences for race in infants.

Nanoscale chemical heterogeneity dominates the optoelectronic response of alloyed perovskite solar cells.

Halide perovskites perform remarkably in optoelectronic devices. However, this exceptional performance is striking given that perovskites exhibit deep charge-carrier traps and spatial compositional and structural heterogeneity, all of which should be detrimental to performance. Here, we resolve this long-standing paradox by providing a global visualization of the nanoscale chemical, structural and optoelectronic landscape in halide perovskite devices, made possible through the development of a new suite of correlative, multimodal microscopy measurements combining quantitative optical spectroscopic techniques and synchrotron nanoprobe measurements. We show that compositional disorder dominates the optoelectronic response over a weaker influence of nanoscale strain variations even of large magnitude. Nanoscale compositional gradients drive carrier funnelling onto local regions associated with low electronic disorder, drawing carrier recombination away from trap clusters associated with electronic disorder and leading to high local photoluminescence quantum efficiency. These measurements reveal a global picture of the competitive nanoscale landscape, which endows enhanced defect tolerance in devices through spatial chemical disorder that outcompetes both electronic and structural disorder.

Single-Cell Chemistry of Photoactivatable Platinum Anticancer Complexes.

The Pt(IV) prodrug trans, trans, trans-[Pt(pyridine)2(N3)2(OH)2] (Pt1) and its coumarin derivative trans, trans, trans-[Pt(pyridine)2(N3)2(OH)(coumarin-3-carboxylate)] (Pt2) are promising agents for photoactivated chemotherapy. These complexes are inert in the dark but release Pt(II) species and radicals upon visible light irradiation, resulting in photocytotoxicity toward cancer cells. Here, we have used synchrotron techniques to investigate the in-cell behavior of these prodrugs and visualize, for the first time, changes in cellular morphology and Pt localization upon treatment with and without light irradiation. We show that photoactivation of Pt2 induces remarkable cellular damage with extreme alterations to multiple cellular components, including formation of vacuoles, while also significantly increasing the cellular accumulation of Pt species compared to dark conditions. X-ray absorption near-edge structure (XANES) measurements in cells treated with Pt2 indicate only partial reduction of the prodrug upon irradiation, highlighting that phototoxicity in cancer cells may involve not only Pt(II) photoproducts but also photoexcited Pt(IV) species.

Beam and sample movement compensation for robust spectro-microscopy measurements on a hard X-ray nanoprobe.

Static and in situ nanoscale spectro-microscopy is now routinely performed on the Hard X-ray Nanoprobe beamline at Diamond and the solutions implemented to provide robust energy scanning and experimental operation are described. A software-based scheme for active feedback stabilization of X-ray beam position and monochromatic beam flux across the operating energy range of the beamline is reported, consisting of two linked feedback loops using extremum seeking and position control. Multimodal registration methods have been implemented for active compensation of drift during an experiment to compensate for sample movement during in situ experiments or from beam-induced effects.

When novelty prevails on familiarity: Visual biases for child versus infant faces in 3.5- to 12-month-olds.

The current study examined the influence of everyday perceptual experience with infant and child faces on the shaping of visual biases for faces in 3.5-, 6-, 9-, and 12-month-old infants. In Experiment 1, infants were presented with pairs of photographs of unfamiliar child and infant faces. Four groups with differential experience with infant and child faces were composed from parents' reports of daily exposure with infants and children (no experience, infant face experience, child face experience, and both infant and child face experience) to assess influence of experience on face preferences. Results showed that infants from all age groups displayed a bias for the novel category of faces in relation to their previous exposure to infant and child faces. In Experiment 2, this pattern of visual attention was reversed in infants presented with pictures of personally familiar child faces (i.e., older siblings) compared with unfamiliar infant faces, especially in older infants. These results suggest that allocation of attention for novelty can supersede familiarity biases for faces depending on experience and highlight that multiple factors drive infant visual behavior in responding to the social world.

Infants recognize words spoken through opaque masks but not through clear masks.

COVID-19 has modified numerous aspects of children's social environments. Many children are now spoken to through a mask. There is little empirical evidence attesting to the effects of masked language input on language processing. In addition, not much is known about the effects of clear masks (i.e., transparent face shields) versus opaque masks on language comprehension in children. In the current study, 2-year-old infants were tested on their ability to recognize familiar spoken words in three conditions: words presented with no mask, words presented through a clear mask, and words presented through an opaque mask. Infants were able to recognize familiar words presented without a mask and when hearing words through opaque masks, but not when hearing words through clear masks. Findings suggest that the ability of infants to recover spoken language input through masks varies depending on the surface properties of the mask.