Solvent-drop assisted mechanochemical synthesis of the black and green polymorphs of the tetrathiafulvalene–chloranil charge transfer salt

This work describes the synthesis of the green and black polymorphic forms of the tetrathiafulvalene–chloranil (TTF–CA) charge transfer salt as pure phases, by solvent-assisted mechanochemistry. Both materials were characterized using laboratory and high-resolution X-ray powder diffraction (XRPD), elemental analysis and scanning electron microscopy (SEM). The high-resolution XRPD pattern of the TTF–CA black polymorph was indexed with a triclinic lattice a = 10.756(5) Å, b = 11.057(4) Å, c = 6.614(2) Å, α = 101.36(2)°, β = 93.69(3)°, γ = 89.37(3)°, V = 769.6(5) Å³. The chemical stability of these phases upon heating was investigated using thermogravimetric analysis (TGA), elemental analysis and X-ray powder diffraction (XRPD), indicating that both polymorphs undergo chemical decomposition, and ruling out the transition to an air-stable high temperature polymorph.     

Polymorph selection by continuous crystallization

This article is motivated by a remarkable observation reported recently by Myerson, Trout, and co‐workers that continuous crystallization is capable of producing metastable polymorphs in stable steady‐state operation. We explain why this phenomenon occurs and give simple design rules for reproducing it in other polymorphic systems. A linear stability analysis gives simple functions of parameters for which one can continuously produce thermodynamically metastable products based only on the relative polymorph dynamics. We demonstrate agreement with two sets of experimental data; L‐glutamic acid grown from aqueous solution and p‐aminobenzoic acid also grown from aqueous solution. For many polymorphic compounds, engineering a process to produce a desired polymorph is as simple as finding a reasonable operating point for the continuous mixed‐suspension mixed‐product removal crystallization process (temperature, residence time, initial supersaturation, etc.) according to the rules reported in this article. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3505–3514, 2016     

Absorption of silicon from artesian aquifer water and its impact on bone health in postmenopausal women: a 12 week pilot study

Background  

Decreased bone mineral density and osteoporosis in postmenopausal women represents a growing source of physical limitations and financial concerns in our aging population. While appropriate medical treatments such as bisphosphonate drugs and hormone replacement therapy exist, they are associated with serious side effects such as osteonecrosis of the jaw or increased cardiovascular risk. In addition to calcium and vitamin D supplementation, previous studies have demonstrated a beneficial effect of dietary silicon on bone health. This study evaluated the absorption of silicon from bottled artesian aquifer water and its effect on markers of bone metabolism.     

Physiological compliance and team performance

Physiological compliance (PC) refers to the correlation between physiological measures of team members over time. The goals of this study were to examine ways of measuring PC in heart rate variability (HRV) data and the relationship between PC and team performance. Teams were tasked with entering both real and simulated rooms and “shooting” individuals with a weapon and identifying individuals without a weapon. The linear correlation and directional agreement PC methods were shown to be the most sensitive to differences in performance, with greater PC being associated with better performance. The correlation method when applied to a measure of respiratory sinus arrhythmia (RSA) revealed a significant difference between high and low performers (t[8] = −2.31, p = 0.03) and the directional agreement applied to inter-beat-intervals and RSA revealed trend-level differences (t[4.62] = −1.86, p = 0.06 and t[8] = −1.68, p = 0.07). These results suggest that PC may have merit for predicting team performance.     

Sympathetic response to stimulation of the pontine A5 region in conscious rabbits

OBJECT: This study is a retrospective analysis of clinical data obtained in 28 patients affected by obstructive hydrocephalus who presented with signs of midbrain dysfunction during episodes of shunt malfunction. METHODS: All patients presented with an upward gaze palsy, sometimes associated with other signs of oculomotor dysfunction. In seven cases the ocular signs remained isolated and resolved rapidly after shunt revision. In 21 cases the ocular signs were variably associated with other clinical manifestations such as pyramidal and extrapyramidal deficits, memory disturbances, mutism, or alterations in consciousness. Resolution of these symptoms after shunt revision was usually slow. In four cases a transient paradoxical aggravation was observed at the time of shunt revision. In 11 cases ventriculocistemostomy allowed resolution of the symptoms and withdrawal of the shunt. Simultaneous supratentorial and infratentorial intracranial pressure recordings performed in seven of the patients showed a pressure gradient between the supratentorial and infratentorial compartments, with a higher supratentorial pressure before shunt revision. Inversion of this pressure gradient was observed after shunt revision and resolution of the gradient was observed in one case after third ventriculostomy. In six recent cases, a focal midbrain hyperintensity was evidenced on T2-weighted magnetic resonance imaging sequences at the time of shunt malfunction. This rapidly resolved after the patient underwent third ventriculostomy. CONCLUSIONS: It is probable that in obstructive hydrocephalus, at the time of shunt malfunction, the development of a transtentorial pressure gradient could initially induce a functional impairment of the upper midbrain, inducing upward gaze palsy. The persistence of the gradient could lead to a global dysfunction of the upper midbrain. Third ventriculostomy contributes to equalization of cerebrospinal fluid pressure across the tentorium by restoring free communication between the infratentorial and supratentorial compartments, resulting in resolution of the patient's clinical symptoms.     

Redistribution of synaptic efficacy supports stable pattern learning in neural networks

Markram and Tsodyks, by showing that the elevated synaptic efficacy observed with single-pulse long-term potentiation (LTP) measurements disappears with higher-frequency test pulses, have critically challenged the conventional assumption that LTP reflects a general gain increase. This observed change in frequency dependence during synaptic potentiation is called redistribution of synaptic efficacy (RSE). RSE is here seen as the local realization of a global design principle in a neural network for pattern coding. The underlying computational model posits an adaptive threshold rather than a multiplicative weight as the elementary unit of long-term memory. A distributed instar learning law allows thresholds to increase only monotonically, but adaptation has a bidirectional effect on the model postsynaptic potential. At each synapse, threshold increases implement pattern selectivity via a frequency-dependent signal component, while a complementary frequency-independent component nonspecifically strengthens the path. This synaptic balance produces changes in frequency dependence that are robustly similar to those observed by Markram and Tsodyks. The network design therefore suggests a functional purpose for RSE, which, by helping to bound total memory change, supports a distributed coding scheme that is stable with fast as well as slow learning. Multiplicative weights have served as a cornerstone for models of physiological data and neural systems for decades. Although the model discussed here does not implement detailed physiology of synaptic transmission, its new learning laws operate in a network architecture that suggests how recently discovered synaptic computations such as RSE may help produce new network capabilities such as learning that is fast, stable, and distributed.     

Minimum sodium nitrite levels for pinking of various cooked meats as related to use of direct or indirect-dried soy isolates in poultry rolls

The relationship between sodium nitrite level and pinking was investigated in cooked meats, as measured by panel color score, acetone extraction of NO-hemochrome, and instrumental redness values. Beef was less susceptible than poultry breast meat to nitrite-induced pinking. Minimum sodium nitrite level for pinking was 14, 4, 2, and 1 ppm for beef round, pork shoulder, turkey breast, and chicken breast, respectively. By regression analysis, minimum ppm nitrite for pinking=0.092 (ppm total pigment)+0.53 (R(2)=0.99). High levels of nitrate (>250 ppm as sodium nitrate) and nitrite (>45 ppm as sodium nitrite) were found in direct-dried (DD) soy isolates. Chicken breast rolls formulated with >2% DD soy were pink, but control rolls with 156 ppm sodium nitrate were not pink. Thus, it was concluded that nitrite was the primary pinking agent in DD soy. Indirect-dried (ID) soy isolates contained <11 ppm sodium nitrite, which was insufficient for pinking in poultry rolls.