Investigation of 252Cf sources with a Ge gamma-ray detector.

This study investigated the feasibility of combining high-resolution gamma-ray spectroscopy with the simulation capabilities of the Nucleonica Nuclear Science Portal with the aim to determine the properties of Cf sources. In this contribution, we present the results for a 20-month-old and a 49-year-old Cf source. In particular, the question arises whether the neutron emission rate can be determined using gamma-ray spectroscopy.

Identifying underlying individuality across running, walking, and handwriting patterns with conditional cycle-consistent generative adversarial networks.

In recent years, the analysis of movement patterns has increasingly focused on the individuality of movements. After long speculations about weak individuality, strong individuality is now accepted, and the first situation-dependent fine structures within it are already identified. Methodologically, however, only signals of the same movements have been compared so far. The goal of this work is to detect cross-movement commonalities of individual walking, running, and handwriting patterns using data augmentation. A total of 17 healthy adults (35.8 ± 11.1 years, eight women and nine men) each performed 627.9 ± 129.0 walking strides, 962.9 ± 182.0 running strides, and 59.25 ± 1.8 handwritings. Using the conditional cycle-consistent generative adversarial network (CycleGAN), conditioned on the participant's class, a pairwise transformation between the vertical ground reaction force during walking and running and the vertical pen pressure during handwriting was learned in the first step. In the second step, the original data of the respective movements were used to artificially generate the other movement data. In the third step, whether the artificially generated data could be correctly assigned to a person via classification using a support vector machine trained with original data of the movement was tested. The classification F1-score ranged from 46.8% for handwriting data generated from walking data to 98.9% for walking data generated from running data. Thus, cross-movement individual patterns could be identified. Therefore, the methodology presented in this study may help to enable cross-movement analysis and the artificial generation of larger amounts of data.

Effectiveness of Psychomotor Therapy among Children with Graphomotor Impairment with and without DCD-Diagnosis.

In Switzerland, psychomotor therapy (PMT) is a standard treatment for children with graphomotor impairments, but scientific evidence of its effectiveness is rare. To investigate the effectiveness of PMT, we conducted a randomised field trial (RFT). The sample consisted of 121 first and second graders with graphomotor impairments, some of whom met the criteria of developmental coordination disorder, while the remaining suffered from developmental dysgraphia. The treatments lasted over 5 months. Handwriting fluency and consistency were measured five times on a digitising tablet. All participating children completed a self-concept interview, and a standardised fine motor performance test twice. Psychomotor therapy significantly improved the fine motor skills of the therapy group compared to those of the waiting group. However, there was no evidence that the treated children improved more than the waiting children in terms of their graphomotor skills such as frequency, automaticity, and consistency of forming letters. Finally, the children of the therapy group showed partial improvements in their handwriting self-concept, while those of the waiting group children remained stable. This short-term RFT demonstrated the effectiveness of PMT in terms of fine motor skills and some aspects of the handwriting self-concept but showed no effects on handwriting fluency and consistency.

Handwriting kinematics during learning to write with the dominant left hand in converted left-handers.

Converting left-handers to their non-dominant right hand was previously widespread, particularly for handwriting. The present study aimed to explore the extent to which adult, converted left-handers can learn writing with their dominant left hand during a 2-year training program. Eleven converted left-handers participated in the training. Handwriting kinematics were assessed at regular intervals (seven sessions) and compared to those of 11 innate left-handed controls matched for age, gender, and overall handedness score for basic (Finger, Wrist, Circle) and complex (Sentence, Copy) handwriting tasks. Regarding basic tasks in the training group, we found rapid increases in left and right-hand frequency and no significant differences between both hands at any time point, indicating successful hand transfer. After 24 months, training participants significantly surpassed controls for writing frequency in basic tasks with their left hand. For complex tasks, we identified significant increases in the training groups' left-hand writing frequency and duration between the first and last session. While training participants' left-hand writing remained significantly slower than their right-hand writing, statistics confirmed final differences between hands only for the duration of the Sentence task. Importantly, left-hand writing in the training group was characterized by lower frequency, lower automaticity, and prolonged duration after 24 months compared to innate left-handers. With training participants' left-hand writing skills significantly increasing for complex tasks and no final statistically significant differences between hands for frequency and automaticity, the program was considered effective. Nevertheless, within 2 years, training participants did not reach innate left-handers handwriting proficiency for complex tasks. Underlying reasons may be various, such as a non-optimal training program, a sensitive period for learning to write, irreversible neural changes during conversion in childhood, age-related decline of motor learning capacity, or retrograde interference between right- and left-hand writing.

Coordination of Pnictogenylboranes Towards Tl(I) Salts and a Tl- Mediated P-P Coupling.

The coordination chemistry of only Lewis-base (LB)-stabilized pnictogenylboranes EH2 BH2 ⋅NMe3 (E=P, As) towards Tl(I) salts has been studied. The reaction of Tl[BArCl ] (BArCl =[B(3,5-C6 H3 Cl2 )4 ]- ) with the corresponding pnictogenylborane results in the formation of [Tl(EH2 BH2 ⋅NMe3 )][BArCl ] (1 a: E=P; 1 b: E=As). Whereas the Tl ion in 1 a/b is monocoordinated, the exchange of the weakly coordinating anion (WCA) in the Tl(I) salt leads to the formation of a trigonal pyramidal coordination mode at the Tl atom by coordination of three equivalents of EH2 BH2 ⋅ NMe3 in [Tl(EH2 BH2 ⋅ NMe3 )3 ][WCA] (2 a: E=P, WCA=TEFCl ; 2 b: E=As, WCA=TEF) (TEF=[Al{OC(CF3 )3 }4 ]- , TEFCl =[Al{(OC(CF3 )2 (CCl3 )}4 ]- ). Furthermore, by using two equivalents of PH2 BH2 ⋅NMe3 , a Tl(I)-mediated P-P coupling takes place in CH2 Cl2 as solvent resulting in [Me3 N⋅BH2 PH2 PHBH2 ⋅NMe3 ][WCA] (WCA=TEF, 3 a; BArCl , 3 b; TEFCl , 3 c). In contrast, for the arsenic derivatives 1 b and 2 b, no coupling reaction is observed. The underlying chemical processes are elucidated by quantum chemical computations.

Three- and Five-Membered Anionic Chains of Pnictogenylboranes.

An unprecedented family of three- and five-membered substituted anionic derivatives of parent pnictogenylboranes is herein reported. Reacting various combinations of the pnictogenylboranes H2 E'-BH2 -NMe3 (E'=P, As) with pnictogen-based nucleophiles MER1R2 (E=P, As; R1=H, R2=t Bu; R1=R2=Ph; M=Na, K) allows for the isolation of the unsymmetrical products [Na(18-crown-6)][H2 E'-BH2 -EHt Bu] (3: E=E'=P; 4: E=E'=As; 5: E=As, E'=P) and [M(C)][H2 E'-BH2 -EPh2 ] (7: E=E'=P, M=Na, C=18-crown-6; 8: E=E'=As; M=K, C=[2.2.2]cryptand; 9: E=P, E'=As, M=Na, C=[2.2.2]cryptand; 10: E=As, E'=P, M=K, C=[2.2.2]cryptand). [Na(18-crown-6)][H2 As-BH2 -t BuPH-BH3 ] (6) is only accessible by a different pathway, using t BuPH2 , BH3 ⋅ SMe2 and NaNH2 as starting materials. Additionally, the synthesis of symmetrical diphenyl-substituted compounds [M(18-crown-6)][Ph2 E-BH2 -EPh2 ] (11: E=P, M=Na; 12: E=As, M=K) is reported which can be regarded as isostructural inorganic, negatively charged analogs of dppm (1,1-bis(diphenylphosphino)methane) and dpam (1,1-bis(diphenylarsino)methane). Furthermore, an elongation of the pnictogen boron backbone in compounds 3, 7 and 9' (similar compound to 9, stabilized however by 18-crown-6), is attainable by reacting them with the pnictogenylboranes H2 E'-BH2 -NMe3 leading to corresponding five-membered chain-like compounds [Na(18-crown-6)][H2 E-BH2 -R1R2P-BH2 -E'H2 ] (E=E'=P, R1=H, R2=t Bu (13); E=E'=P, R1=R2=Ph (14); E=E'=As, R1=R2=Ph (15); E=P, E'=As, R1=R2=Ph (16)). Finally, the thermodynamics of the reaction pathways were evaluated by quantum chemical computations.

Neural Correlates of Executed Compared to Imagined Writing and Drawing Movements: A Functional Magnetic Resonance Imaging Study.

Objective: In this study we used functional magnetic resonance imaging (fMRI) to investigate whether motor imagery (MI) of handwriting and circle drawing activates a similar handwriting network as writing and drawing itself. Methods: Eighteen healthy right-handed participants wrote the German word "Wellen" and drew continuously circles in a sitting (vertical position) and lying position (horizontal position) to capture kinematic handwriting parameters such as velocity, pressure and regularity of hand movements. Afterward, they performed the same tasks during fMRI in a MI and an executed condition. Results: The kinematic analysis revealed a general correlation of handwriting parameters during sitting and lying except of pen pressure during drawing. Writing compared to imagined writing was accompanied by an increased activity of the ipsilateral cerebellum and the contralateral sensorimotor cortex. Executed compared to imagined drawing revealed elevated activity of a fronto-parieto-temporal network. By contrasting writing and drawing directly, executed writing induced an enhanced activation of the left somatosensory and premotor area. The comparison of the MI of these tasks revealed a higher involvement of occipital activation during imagined writing. Conclusion: The kinematic results pointed to a high comparability of writing in a vertical and horizontal position. Overall, we observed highly overlapping cortical activity except of a higher involvement of motor control areas during motor execution. The sparse difference between writing and drawing can be explained by highly automatized writing in healthy individuals.

Dystonic Golfer's cramp: Pilot study of propranolol and looking at the hole.

INTRODUCTION: There is limited data in the scientific literature using quantitative methods to assess response of golfer's cramp to intervention. The objective of this pilot study was to use quantitative measures to study the effect of propranolol and looking at the hole when putting. METHODS: 14 golfers completed 50 10' putts (10 each x 5 conditions): two-handed looking at the ball, right hand only looking at the ball, two-handed looking at the hole, then following a single 10 mg oral dose of propranolol two-handed and right hand only putts looking at the ball. Quantitative measurements of putter movement and surface EMG to assess wrist muscle co-contraction were measured. RESULTS: Based on video review of the putting, five golfers with dystonic golfer's cramp and nine with non-dystonic yips were compared. Those with dystonic golfer's cramp had more putts with the yips and yips with co-contraction when two-handed putting looking at the ball, no increase when putting right hand only, less smoothness of putter movement, and all of these improved following propranolol and when looking at the hole. The non-dystonic group had an increase in yipped putts and yipped putts with co-contraction putting right hand only and no improvement with either intervention. CONCLUSION: Yipped putts with co-contraction, right hand only putting, and smoothness of putter movement differed between dystonic golfer's cramp and non-dystonic yips. Propranolol and looking at the hole only improved dystonic golfer's cramp putting. This is the first pilot study of oral medication treatment for this task-specific dystonia.

The Yips: Methods to Identify Golfers with a Dystonic Etiology/Golfer's Cramp.

PURPOSE: To determine whether quantitative methods could separate golfers with a possible dystonic cause of the "yips" from those that appear to be nondystonic. METHODS: Twenty-seven golfers completed 10 two-handed and 10 right hand-only putts. Surface EMG assessed forearm muscle co-contraction and motion detectors monitored wrist and putter movements. Based on a videotape review, golfers were grouped into those with yips of dystonic etiology, those with the yips nondystonic, and those with no yips. RESULTS: On video review of two-handed putting, five golfers had yips that appeared to be dystonic, nine had yips that did not appear to be dystonic, and 13 had no yips. During two-handed putting co-occurrence of a yipped putt and wrist flexor/extensor and/or pronator/supinator co-contraction was significantly more frequent in those with dystonic yips. The dystonic group had no increase in the number of yipped putts or yips with co-contraction when putting right hand only, whereas the nondystonic group had significantly more yipped putts and more yipped putts with co-contraction with right hand only. CONCLUSIONS: Quantitative methods were identified that appear to identify golfers with a dystonic etiology for the yips. It is not just the frequency of yips nor just specific motion patterns alone, rather it is also a combination of yips with co-occurring co-contraction when putting with two hands, and then right hand only, that distinguished this possible etiology. Despite being a small study, identifying a dystonic pattern, even in a nonpressure indoor setting, may aid in assessment and possible monitoring of treatment.

Depolymerization of Poly(phosphinoboranes): From Polymers to Lewis Base Stabilized Monomers.

We report on depolymerization reactions of poly(phosphinoboranes). The cleavage of the polymers [H2 PBH2 ]n (2 a), [tBuHPBH2 ]n (2 c), [PhHPBH2 ]n (2 e) and the oligomer [Ph2 PBH2 ]n (2 b), with strong Lewis bases (LBs), in particular with NHCs, leads to the corresponding monomeric phosphanylboranes R1 R2 PBH2 LB. It is observed that the depolymerization depends on the strength and stability of the LBs as well as on the substitution pattern of the poly(phosphinoboranes). The solid state structures of the monomeric phosphinoboranes H2 PBH2 NHCMe (NHC=N-heterocyclic carbene) (4 a), H2 PBH2 NHCdipp (5 a) and tBuHPBH2 NHCMe (4 c) were determined. DFT calculations support the experimentally observed reaction behavior.

Superradiance from Two Dimensional Brick-Wall Aggregates of Dye Molecules: The Role of Size and Shape for the Temperature Dependence.

Aggregates of interacting molecules can exhibit electronically excited states that are coherently delocalized over many molecules. This can lead to a strong enhancement of the fluorescence decay rate which is referred to as superradiance (SR). To date, the temperature dependence of SR is described by a 1/T law. Using an epitaxial dye layer and a Frenkel-exciton based model we provide both experimental and theoretical evidence that significant deviations from the 1/T behavior can occur for brick-wall-type aggregates of finite size leading even to a maximum of the SR at finite temperature. This is due to the presence of low energy excitations of weak or zero transition strength. These findings are relevant for designing light-emitting molecular materials.

A surface science compatible epifluorescence microscope for inspection of samples under ultra high vacuum and cryogenic conditions.

We modified an epi-illumination light microscope and mounted it on an ultra high vacuum chamber for investigating samples used in a surface science experiment. For easy access and bake out, all optical components are placed outside the vacuum and the sample is imaged through a glass window. The microscope can be operated in reflection brightfield or epifluorescence mode to image the sample surface or fluorescent dye molecules adsorbed on it. The homemade sample mounting was made compatible for the use under the microscope; sample temperatures as low as 6 K can be achieved. The performance of the microscope is demonstrated on two model samples: Brightfield-images of a well-prepared Ag(100) surface show a macroscopic corrugation of the surface, although low energy electron diffraction data indicate a highly ordered crystalline surface. The surface shows macroscopic protrusions with flat regions, about 20-200 µm in diameter, in between. Fluorescence images of diluted 3,4,9,10-perylene tetracarboxylicacid dianhydride (PTCDA) molecules adsorbed on an ultrathin epitaxial KCl film on the Ag(100) surface show a shading effect at surface protrusions due to an inclined angle of incidence of the PTCDA beam during deposition. For some preparations, the distribution of the fluorescence intensity is inhomogeneous and shows a dense network of bright patches about 5 µm in diameter related to the macroscopic corrugation of the surface. We propose that such a light microscope can aid many surface science experiments, especially those dealing with epitaxial growth or fluorescent materials.

A Convenient Route to Mixed Pnictogenylboranes.

We report on the synthesis and characterization of mixed pnictogenylboranes. The substitution of the Lewis base SMe2 in (OC)5 W-PH2 BH2 -SMe2 (2) by different pnictogenylboranes ER2 BH2 -LB (E=P, As, Sb) leads to the Lewis acid/base stabilized butane analogue (OC)5 W-PH2 BH2 ER2 BH2 -LB (3 a, b: E=P; R=H, SiMe3 ; LB=NMe3 ; 4 a, b: E=As; R=H, SiMe3 ; LB=NMe3 ; 5: E=Sb; R=SiMe3 ; LB=NHCMe ). All of these compounds were characterized by single-crystal X-ray structure analysis, mass spectrometry, NMR, and IR spectroscopy. In addition, the very unstable phosphanylborane chain PH2 BH2 PH2 BH2 -NMe3 (1) was synthesized. DFT calculations provide insight into the thermodynamics of these reactions.

Cationic Chains of Parent Arsanylboranes and Substituted Phosphanylboranes.

The substituted monomeric phosphanylboranes Ph2 P-BH2 ⋅NMe3 (1) and tBuHP-BH2 ⋅NMe3 (2) have been used for the synthesis of cationic chain compounds built up by R2 P-BH2 units. With a simple synthesis route, the highly stable cations [Me3 N⋅H2 B-PR1 R2 -BH2 ⋅NMe3 ]+ (1 a, 2 a) and [Me3 N⋅H2 B-PR1 R2 -BH2 -PR1 R2 -BH2 ⋅NMe3 ]+ (1 b, 2 b) (R1 =R2 =Ph; R1 =H, R2 =tBu) are obtained as iodide (I- ) salts. The reaction of H2 As-BH2 ⋅NMe3 (3) with IBH2 ⋅SMe2 leads to [Me3 N⋅H2 B-AsH2 -BH2 -AsH2 -BH2 ⋅NMe3 ][I] (3 a), the longest so far known arsanylborane chain. Compound 3 a reacts with acetonitrile through a formal hydroarsination reaction to form [cyclo-{As(BH2 ⋅NMe3 )(CMe=NH)2 (BH2 )}][I] (4). The reported synthetic strategy has proved to be a powerful tool for the formation of small, cationic oligomeric units. All products were comprehensively characterized by X-ray structure analysis, NMR, IR spectroscopy, and mass spectrometry in cooperation with DFT calculations.

Oxidation of Substituted Phosphanylboranes with Chalcogens.

The elemental chalcogens sulfur, selenium, tellurium and bis(trimethylsilyl)peroxide as an oxygen source are applied for the oxidation of the phosphanylboranes Ph2 P-BH2 ⋅NMe3 (1) and tBuHP-BH2 ⋅NMe3 (2). The corresponding monooxidation products Ph2 P(X)-BH2 ⋅NMe3 (X=O-Te, 3 a-d) and tBuHP(X)-BH2 ⋅NMe3 (X=O-Te, 4 a-d) were obtained in good yields and comprehensively characterized by single crystal X-ray structure analysis, NMR, IR spectroscopy and mass spectrometry. The first oxidation step proceeds very selectively for all chalcogenides. For the tBu derivative, a further oxidation can be realised with O2 , S8 and Se yielding tBu(HX)P(X)-BH2 ⋅NMe3 (X=O, S, Se, 5 a-c). The telluride compounds presented herein are the first examples of neutral Te-substituted phosphanylboranes.

Sorption and redox speciation of plutonium at the illite surface under highly saline conditions.

Natural groundwater may contain high salt concentrations, such as those occurring at several potential deep geological nuclear waste repository sites. Actinide sorption to clays (e.g. illite) under saline conditions has, however, been rarely studied. Furthermore, both illite surface and ionic strength may affect redox speciation of actinides like plutonium. In the present study, Pu sorption to illite is investigated under anaerobic conditions for 36, overall Pu uptake is largely insensitive to mNaCl due to the prevalence of strongly adsorbed Pu(IV). By applying appropriate corrections to the activity coefficients of dissolved ions and using the 2-site protolysis non-electrostatic surface complexation and cation exchange (2 SPNE SC/CE) model, experimental data on Pu sorption to illite as a function of pH, Eh and mNaCl can be very well reproduced.

Anionic Chains of Parent Pnictogenylboranes.

We report on the synthesis and structural characterization of unprecedented anionic parent compounds of mixed Group 13/15 elements. The reactions of the pnictogenylboranes H2 E-BH2 ⋅NMe3 (1 a=P, 1 b=As) with phosphorus and arsenic centered nucleophiles of the type [EH2 ]- (E=P, As) lead to the formation of compounds of the type [H2 E-BH2 -E'H2 ]- (2: E=E'=P; 3: E=E'=As; 4: E=P, E'=As) containing anionic pnictogen-boron chain-like units. Furthermore, a longer 5-membered chain species [H2 As-BH2 -PH2 -BH2 -AsH2 ]- (5) and a cyclic compound [NHCdipp -H2 B-PH2 -BH2 -NHCdipp ]+ [P5 B5 H19 ]- (6) containing a n-butylcyclohexane-like anion were obtained. All the compounds have been characterized by X-ray structure analysis, multinuclear NMR spectroscopy, IR spectroscopy, and mass spectrometry. DFT calculations elucidate their high thermodynamic stability, the charge distribution, and give insight into the reaction pathway.

Sorption and Redox Speciation of Plutonium at the Illite Surface.

The geochemical behavior of Pu strongly depends on its redox speciation. In this study, we investigated Pu sorption onto Na-illite, a relevant component of potential host rocks for high-level nuclear waste repositories, under anaerobic conditions. When contacting Pu (85% Pu(IV), 11% Pu(V), and 4% Pu(III); 8 × 10(-11) < [Pu]tot/M < 10(-8)) with illite in 0.1 M NaCl at pH between 3 and 10, Pu uptake was characterized by log Rd > 4 (Rd: distribution coefficient in L kg(-1)). Small amounts of aqueous Pu(V) were detected in solution on contact with illite after 1 week, which is not expected to be stable at the measured redox potentials (Eh) in our experiments. This observation suggests time-dependent reduction of Pu(V) to Pu(IV). After one year, log Rd values had increased compared to those after 1 week due to the reduction of weakly adsorbing Pu(V). For pH < 5, Pu(IV) and Pu(III) coexisted in solution under our experimental conditions, showing that Pu(IV) reduction to Pu(III) occurred in the illite suspension. Taking (i) surface complexation constants determined for Eu(III)-illite interaction (with redox-insensitive Eu(III) as a chemical analogue to Pu(III)), (ii) the known constant for Pu(III)-Pu(IV) redox transition, and (iii) measured Eh and pH, overall Pu uptake was well-predicted.

First structural characterization of Pa(iv) in aqueous solution and quantum chemical investigations of the tetravalent actinides up to Bk(IV): the evidence of a curium break.

More than a century after its discovery the structure of the Pa(4+) ion in acidic aqueous solution has been investigated for the first time experimentally and by quantum chemistry. The combined results of EXAFS data and quantum chemically optimized structures suggest that the Pa(4+) aqua ion has an average of nine water molecules in its first hydration sphere at a mean Pa-O distance of 2.43 Å. The data available for the early tetravalent actinide (An) elements from Th(4+) to Bk(4+) show that the An-O bonds have a pronounced electrostatic character, with bond distances following the same monotonic decreasing trend as the An(4+) ionic radii, with a decrease of the hydration number from nine to eight for the heaviest ions Cm(4+) and Bk(4+). Being the first open-shell tetravalent actinide, Pa(4+) features a coordination chemistry very similar to its successors. The electronic configuration of all open-shell systems corresponds to occupation of the valence 5f orbitals, without contribution from the 6d orbitals. Our results thus demonstrate that Pa(iv) resembles its early actinide neighbors.

Metal-Free Addition/Head-to-Tail Polymerization of Transient Phosphinoboranes, RPH-BH2: A Route to Poly(alkylphosphinoboranes).

Mild thermolysis of Lewis base stabilized phosphinoborane monomers R(1)R(2)P-BH2⋅NMe3 (R(1),R(2)=H, Ph, or tBu/H) at room temperature to 100 °C provides a convenient new route to oligo- and polyphosphinoboranes [R(1)R(2)P-BH2]n. The polymerization appears to proceed via the addition/head-to-tail polymerization of short-lived free phosphinoborane monomers, R(1)R(2)P-BH2. This method offers access to high molar mass materials, as exemplified by poly(tert-butylphosphinoborane), that are currently inaccessible using other routes (e.g. catalytic dehydrocoupling).