Developmental surface dyslexia and dysgraphia in a child with corpus callosum agenesis: an approach to diagnosis and treatment.

We present a case study detailing cognitive performance, functional neuroimaging, and effects of a hypothesis-driven treatment in a 10-year-old girl diagnosed with complete, isolated corpus callosum agenesis. Despite having average overall intellectual abilities, the girl exhibited profound surface dyslexia and dysgraphia. Spelling treatment significantly and persistently improved her spelling of trained irregular words, and this improvement generalized to reading accuracy and speed of trained words. Diffusion weighted imaging revealed strengthened intrahemispheric white matter connectivity of the left temporal cortex after treatment and identified interhemispheric connectivity between the occipital lobes, likely facilitated by a pathway crossing the midline via the posterior commissure. This case underlines the corpus callosum's critical role in lexical reading and writing. It demonstrates that spelling treatment may enhance interhemispheric connectivity in corpus callosum agenesis through alternative pathways, boosting the development of a more efficient functional organization of the visual word form area within the left temporo-occipital cortex.

Which Ion Dominates the Temperature and Pressure Response of Halide Perovskites and Elpasolites?

Halide perovskites and elpasolites are key for optoelectronic applications due to their exceptional performance and adaptability. However, understanding their crucial elastic properties for synthesis and device operation remains limited. We performed temperature- and pressure-dependent synchrotron-based powder X-ray diffraction at low pressures (ambient to 0.06 GPa) to investigate their elastic properties in their ambient-pressure crystal structure. We found common trends in bulk modulus and thermal expansivity, with an increased halide ionic radius (Cl to Br to I) resulting in greater softness, higher compressibility, and thermal expansivity in both materials. The A cation has a minor effect, and mixed-halide compositions show intermediate properties. Notably, thermal phase transitions in MAPbI3 and CsPbCl3 induced lattice softening and negative expansivity for specific crystal axes, even at temperatures far from the transition point. These results emphasize the significance of considering temperature-dependent elastic properties, which can significantly impact device stability and performance during manufacturing or temperature sweeps.

Probing nearby molecular vibrations with lanthanide-doped nanocrystals.

The photoluminescence (PL) of lanthanide-doped nanocrystals can be quenched by energy transfer to vibrations of molecules located within a few nanometers from the dopants. Such short-range electronic-to-vibrational energy transfer (EVET) is often undesired as it reduces the photoluminescence efficiency. On the other hand, EVET may be exploited to extract information about molecular vibrations in the local environment of the nanocrystals. Here, we investigate the influence of solvent and gas environments on the PL properties of NaYF4:Er3+,Yb3+ upconversion nanocrystals. We relate changes in the PL spectrum and excited-state lifetimes in different solvents and their deuterated analogues to quenching of specific lanthanide levels by EVET to molecular vibrations. Similar but weaker changes are induced when we expose a film of nanocrystals to a gas environment with different amounts of H2O or D2O vapor. Quenching of green- and red-emitting levels of Er3+ can be explained in terms of EVET-mediated quenching that involves molecular vibrations with energies resonant with the gap between the energy levels of the lanthanide. Quenching of the near-infrared-emitting level is more complex and may involve EVET to combination-vibrations or defect-mediated quenching. EVET-mediated quenching holds promise as a mechanism to probe the local chemical environment-both for nanocrystals dispersed in a liquid and for nanocrystals exposed to gaseous molecules that adsorb onto the nanocrystal surface.

Beyond Karl Fischer titration: a monolithic quantum cascade sensor for monitoring residual water concentration in solvents.

Quality control of liquids is an important part of analytical chemistry. The gold standard for measuring residual water in organic solvents and pharmaceutical applications is Karl Fischer titration. It has a high sensitivity, selectivity and accuracy. The downsides are a time-consuming offline analysis, together with the need for toxic reagents producing waste, and it suffers from poor inter-laboratory reproducibility. In this work, we present a high-performance lab-on-a-chip sensor exploiting mid-IR spectroscopy for liquid sensing. It is operating at 6.1 µm wavelength and is suitable for robust and flexible real-time in situ analysis of the residual water concentration in isopropyl alcohol. This is demonstrated in two experiments. A custom-made 60 µL flow cell is employed to measure only minute amounts of analyte in an inline configuration. In a second approach, the whole sensor is immersed into the analyte to demonstrate sensitive and rapid in situ operation on the millisecond time scale. This is confirmed by the ability for time resolved single water-droplet monitoring, while they are mixed into the liquid sample. We obtain a limit of detection between 120 ppm and 150 ppm with a concentration coverage spanning three orders of magnitude from 1.2 × 10-2%vol to 25%vol for the flow cell and 1.5 × 10-2%vol to 19%vol in the in situ configuration, respectively.

Structure sensitivity in gas sorption and conversion on metal-organic frameworks.

Many catalytic processes depend on the sorption and conversion of gaseous molecules on the surface of (porous) functional materials. These events often preferentially occur on specific, undercoordinated, external surface sites. Here we show the combination of in situ Photo-induced Force Microscopy (PiFM) with Density Functional Theory (DFT) calculations to study the site-specific sorption and conversion of formaldehyde on the external surfaces of well-defined faceted ZIF-8 microcrystals with nanoscale resolution. We observed preferential adsorption of formaldehyde on high index planes. Moreover, in situ PiFM allowed us to visualize unsaturated nanodomains within extended external crystal planes, showing enhanced sorption behavior on the nanoscale. Additionally, on defective ZIF-8 crystals, structure sensitive conversion of formaldehyde through a methoxy- and a formate mechanism mediated by Lewis acidity was found. Strikingly, sorption and conversion were influenced more by the external surface termination than by the concentration of defects. DFT calculations showed that this is due to the presence of specific atomic arrangements on high-index crystal surfaces. With this research, we showcase the high potential of in situ PiFM for structure sensitivity studies on porous functional materials.

The Role of Water in Carbon Dioxide Adsorption in Porphyrinic Metal-Organic Frameworks.

Capturing and converting CO2 through artificial photosynthesis using photoactive, porous materials is a promising approach for addressing increasing CO2 concentrations. Porphyrinic Zr-based metal-organic frameworks (MOFs) are of particular interest as they incorporate a photosensitizer in the porous structure. Herein, the initial step of the artificial photosynthesis is studied: CO2 sorption and activation in the presence of water. A combined vibrational and visible spectroscopic approach was used to monitor the adsorption of CO2 into PCN-222 and PCN-223 MOFs, and the photophysical changes of the porphyrinic linker as a function of water concentration. A shift in CO2 sorption site and bending of the porphyrin macrocycle in response to humidity was observed, and CO2/H2O competition experiments revealed that the exchange of CO2 with H2O is pore-size dependent. Therefore, humidity and pore-size can be used to tune CO2 sorption, CO2 capacity, and light harvesting in porphyrinic MOFs, which are key factors for CO2 photoreduction.

Guest Alignment and Defect Formation during Pore Filling in Metal-Organic Framework Films.

The degree of pore filling is an important parameter for defining guest@MOF properties in applications including electronics, optics, and gas separation. However, the interplay of key aspects of host-guest interactions, such as a quantitative description of the guest alignment or the structural integrity of the host as function of pore filling are yet to be determined. Polarisation-dependent infrared spectroscopy in attenuated total reflection configuration combined with gas sorption allowed to simultaneously study the orientation of the guest molecule and structural changes of the MOF framework during the pore filling process. Thereby we found, that initially randomly oriented guest molecules align with increasing pore filling during adsorption from the gas phase. At the same time, the framework itself undergoes a reversible, guest molecule-dependent rotation of the aromatic linker and a linker detachment process, which induce defects.

Mesoporous Zirconia Coating for Sensing Applications Using Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy.

Mid-infrared attenuated total reflection (ATR) spectroscopy is a powerful tool for in situ monitoring of various processes. Mesoporous silica, an extensively studied material, has already been applied in sensing schemes due to its high surface area and tunable surface chemistry. However, its poor chemical stability in aqueous solutions at pH values higher than 8 and strong absorption below 1250 cm-1 limits its range of applications. To circumvent these problems, a mesoporous zirconia coating on ATR crystals was developed. Herein, the synthesis, surface modification, and characterization of ordered mesoporous zirconia films on Si wafers and Si-ATR crystals are presented. The modified coating was applied in sensing schemes using aromatic and aliphatic nitriles in aqueous solution as organic pollutants. The mesoporous zirconia coating shows strong chemical resistance when kept in alkaline solution for 72 h. The success of surface modification is confirmed using Fourier transform infrared (FT-IR) spectroscopy and contact angle measurements. Benzonitrile and valeronitrile in water are used as model analytes to evaluate the enrichment performance of the film. The experimental results are fitted using Freundlich isotherms, and enrichment factors of 162 and 26 are calculated for 10 mg L-1 benzonitrile and 25 mg L-1 valeronitrile in water, respectively. Limits of detection of 1 mg L-1 for benzonitrile and 11 mg L-1 for valeronitrile are obtained. The high chemical stability of this coating allows application in diverse fields such as catalysis with the possibility of in situ monitoring using FT-IR spectroscopy.

Infrared crystallography for framework and linker orientation in metal-organic framework films.

Pore alignment and linker orientation influence diffusion and guest molecule interactions in metal-organic frameworks (MOFs) and play a pivotal role for successful utilization of MOFs. The crystallographic orientation and the degree of orientation of MOF films are generally determined using X-ray diffraction. However, diffraction methods reach their limit when it comes to very thin films, identification of chemical connectivity or the orientation of organic functional groups in MOFs. Cu-based 2D MOF and 3D MOF films prepared via layer-by-layer method and from aligned Cu(OH)2 substrates were studied with polarization-dependent Fourier-transform infrared (FTIR) spectroscopy in transmission and attenuated total reflection configuration. Thereby, the degrees for in-plane and out-of-plane orientation, the aromatic linker orientation and the initial alignment during layer-by-layer MOF growth, which is impossible to investigate by laboratory XRD equipment, was determined. Experimental IR spectra correlate with theoretical explanations, paving the way to expand the principle of IR crystallography to oriented, organic-inorganic hybrid films beyond MOFs.

A thermoelectrically stabilized aluminium acoustic trap combined with attenuated total reflection infrared spectroscopy for detection of Escherichia coli in water.

Acoustic trapping is a non-contact particle manipulation method that holds great potential for performing automated assays. We demonstrate an aluminium acoustic trap in combination with attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) for detection of E. coli in water. The thermal conductivity of aluminium was exploited to thermo-electrically heat and hold the acoustic trap at the desired assay temperature of 37 °C. Systematic characterisation and optimisation of the acoustic trap allowed high flow rates while maintaining high acoustic trapping performance. The ATR element serves not only as a reflector for ultrasound standing wave generation but also as a sensing interface. The enzyme conversion induced by alkaline phosphatase-labelled bacteria was directly monitored in the acoustic trap using ATR-FTIR spectroscopy. Sequential injection analysis allowed automated liquid handling, including non-contact bacteria retention, washing and enzyme-substrate exchange within the acoustic trap. The presented method was able to detect E. coli concentrations as low as 1.95 × 106 bacteria per mL in 197 min. The demonstrated ultrasound assisted assay paves the way to fully automated bacteria detection devices based on acoustic trapping combined with ATR-FTIR spectroscopy.

Ultra-sensitive slot-waveguide-enhanced Raman spectroscopy for aqueous solutions of non-polar compounds using a functionalized silicon nitride photonic integrated circuit.

We demonstrate an ultra-sensitive waveguide-enhanced Raman sensor for low concentration organic compounds dissolved in water. The spectra are obtained using silicon nitride slot waveguides coated with a thin film of hexamethyldisilazane-modified mesoporous silica. Enriched locally by 600-fold within the coating, a micromolar level of cyclohexanone is probed. The sensor is also capable of simultaneous quantification of multiple analytes, and the adsorbed analytes can be completely released from the coating. These properties make this on-chip Raman sensor promising for diverse applications, especially for the monitoring of non-polar organics and biomolecules in aqueous environments.

Mid-IR sensing platform for trace analysis in aqueous solutions based on a germanium-on-silicon waveguide chip with a mesoporous silica coating for analyte enrichment.

A novel platform based on evanescent wave sensing in the 6.5 to 7.5 µm wavelength range is presented with the example of toluene detection in an aqueous solution. The overall sensing platform consists of a germanium-on-silicon waveguide with a functionalized mesoporous silica cladding and integrated microlenses for alignment-tolerant back-side optical interfacing with a tunable laser spectrometer. Hydrophobic functionalization of the mesoporous cladding allows enrichment of apolar analyte molecules and prevents strong interaction of water with the evanescent wave. The sensing performance was evaluated for aqueous toluene standards resulting in a limit of detection of 7 ppm. Recorded adsorption/desorption profiles followed Freundlich adsorption isotherms with rapid equilibration and resulting sensor response times of a few seconds. This indicates that continuous monitoring of contaminants in water is possible. A significant increase in LOD can be expected by likely improvements to the spectrometer noise floor which, expressed as a relative standard deviation of 100% lines, is currently in the range of 10-2A.U.

3D Printing for Low-Cost and Versatile Attenuated Total Reflection Infrared Spectroscopy.

In this work, we present a fully 3D-printed module for attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy ready for use in commercial FTIR spectrometers. The developed setup stands out in terms of robustness and ease of sample application. Rapid prototyping paired with theoretical considerations were employed to design and fabricate the module. Cost-efficient commercial available silicon and germanium ATR crystals prepared from double-sided polished wafers were mounted in the setup. While low-noise levels and stability bear comparison with commercial systems, the multibounce ATR crystal's long interaction pathlengths as well as their interchangeability turns the presented ATR module into an even more sophisticated tool. The versatility of the proposed setup is demonstrated for various spectroscopic challenges: Curing of a cyanoacrylate and a two-component epoxy based adhesive was monitored by tracking polymerization processes at room and high temperatures. To emphasize potential applications of the disposable ATR module in life science studies exploring potential biohazardous samples, mid-IR spectra of Escherichia coli and bovine serum albumin were recorded. The total printing time of the ATR module is 10.5 h, enabling overnight fabrication at a total cost ranging from 150 to 613 €, making the high versatility of ATR spectroscopy accessible to a broader audience. This proves the potential of 3D printing to generate optical instruments tailored to the needs of individual analytical problems.

Pore Size-Dependent Structure of Confined Water in Mesoporous Silica Films from Water Adsorption/Desorption Using ATR-FTIR Spectroscopy.

The local structure of water on chemically and structurally different surfaces is a subject of ongoing research. In particular, confined spaces as found in mesoporous silica have a pronounced effect on the interplay between the adsorbate-adsorbate and adsorbate-surface interactions. Mid-infrared spectroscopy is ideally suited to quantitatively and qualitatively study such systems as the probed molecular vibrations are highly sensitive to intermolecular interactions. Here, the quantity and structure of water adsorbed from the gas phase into silica mesopores at different water vapor pressures was monitored using mid-infrared attenuated total reflection (ATR) spectroscopy. Germanium ATR crystals were coated with different mesoporous silica films prepared by evaporation-induced self-assembly. Quantitative analysis of the water bending vibration at 1640 cm-1 at varying vapor pressure allows for retrieving porosity and pore size distribution of the mesoporous films. The results were in excellent agreement with those obtained from ellipsometric porosimetry. In addition, different degrees of hydrogen bonding of water as reflected in the band position and shape of the stretching vibrations (3000-3800 cm-1) were analyzed and attributed to high-density, unordered bulk, low-density, and surface-induced ordered water. Thereby, the progression of surface-induced ordered water and bulk water as a function of water vapor pressure was studied for different pore sizes. Small pores of 5 nm diameter showed a number of two-ordered monolayers, whereas for pores >12 nm diameter, the number of ordered monolayers is significantly larger and agrees with the number observed on planar SiO2 surfaces.

An Acoustic Trap for Bead Injection Attenuated Total Reflection Infrared Spectroscopy.

In this work, we introduce a system combining an acoustic trap for bead injection with attenuated total reflection (ATR) infrared (IR) spectroscopy. By mounting an acoustofluidic cell hosting an ultrasound source on top of a custom-built ATR fixture we were able to trap beads labeled with the enzyme alkaline phosphatase without requiring any mechanical retention elements. Sequential injection analysis was employed for reproducible sample handling and bead injection into the acoustic trap. To showcase potential applications of the presented setup for kinetic studies, we monitored the conversion of p-nitrophenylphosphate into p-nitrophenol and phosphate via beads carrying the immobilized enzyme using ATR-IR spectroscopy. Retaining the labeled beads via ultrasound particle manipulation resulted in excellent experimental reproducibility (relative standard deviation, 3.91%). It was demonstrated that trapped beads remained stably restrained with up to eight cell volumes of liquid passing through the acoustofluidic cell. Beads could be discarded in a straightforward manner by switching off the ultrasound, in contrast to systems containing mechanical retention elements, which require backflushing. Multiple experiments were performed by employing different substrate concentrations with the same batch of trapped beads as well as varying the amount of enzyme present in the cell, enabling enzyme kinetic studies and emphasizing the application of the proposed setup in studies where enzymatic reuse is desired. This proves the potential of the acoustic trap combined with ATR-IR spectroscopy to monitor the activity of immobilized enzymes and its ability to perform complex bead-based assays.

Mid-infrared sensing of CO at saturated absorption conditions using intracavity quartz-enhanced photoacoustic spectroscopy.

The sensitivity of quartz-enhanced photoacoustic spectroscopy (QEPAS) can be drastically increased using the power enhancement in high-finesse cavities. Here, low noise resonant power enhancement to 6.3 W was achieved in a linear Brewster window cavity by exploiting optical feedback locking of a quantum cascade laser. The high intracavity intensity of up to 73 W mm-2 in between the prongs of a custom tuning fork resulted in strong optical saturation of CO at 4.59 µm. Saturated absorption is discussed theoretically and experimentally for photoacoustic measurements in general and intracavity QEPAS (I-QEPAS) in particular. The saturation intensity of CO's R9 transition was retrieved from power-dependent I-QEPAS signals. This allowed for sensing CO independently from varying degrees of saturation caused by absorption induced changes of intracavity power. Figures of merit of the I-QEPAS setup for sensing of CO and H2O are compared to standard wavelength modulation QEPAS without cavity enhancement. For H2O, the sensitivity was increased by a factor of 230, practically identical to the power enhancement, while the sensitivity gain for CO detection was limited to 57 by optical saturation.

Green and highly efficient synthesis of perylene and naphthalene bisimides in nothing but water.

High-purity, symmetrically substituted perylene and naphthalene bisimides were obtained by hydrothermal condensation of monoamines with the corresponding bisanhydride. The hydrothermal imidization proceeds quantitatively, without the need for organic solvents, catalysts or excess of the amines.

Porous titanium and zirconium oxo carboxylates at the interface between sol-gel and metal-organic framework structures.

Reaction of Ti(OiPr)4 with several tri- and tetracarboxylic acids, followed by hydrolysis, resulted in microporous, structured materials, with microporous surface areas up to 340 m(2) g(-1). Depending on the kind of carboxylic acid, the Ti : COOH ratio and the Ti : H2O ratio, either pillared layered or surface fractal 3D structures were obtained according to SAXS measurements. The most pronounced layered structure was found for 1,2,4,5-benzenetetrabenzoic acid and a Ti : H2O ratio of 4, while a Ti : H2O ratio of 2 resulted in a 3D structure. The use of 1,3,5-benzenetricarboxylic acid or 1,3,5-benzenetribenzoic acid resulted in similar structures which, however, were less pronounced and less ordered. The reaction of tetrakis(4-carboxyphenyl)silicon with Ti(OiPr)4 or benzenetribenzoic acid with Zr(OiPr)4 gave 3D structures for all Ti : H2O ratios.