Open shell (4n + 2)π and closed shell 4nπ planar core-modified decaphyrins.

Planar 44π and 46π core-modified decaphyrins with ten thiophene units have been synthesized from short thiophene oligomers. They have been structurally characterized by single crystal X-ray diffraction with further support from spectroscopic analysis and quantum chemical calculations. Our analysis revealed diradicaloid characteristics for 46π species in contrast to the closed shell property of the 44π congener. Further, 44π and 46π undergo reversible two-electron chemical oxidation, as observed by spectro-electrochemical measurements.

Redox Assisted Reversible Aromaticity Transition Between 30π Hückel and 28π Möbius Dication of a Core-Modified Isophlorinoid.

The electronic properties of a hexaphyrin was fine-tuned via core-modification leading to the formation of a Hückel aromatic 30π hexaphyrin which incorporates two pyrrole and four furan rings in the π-conjugated pathway. This Hückel aromatic hexaphyrin modified its conformation upon two-electron ring oxidation either with triflic acid or Meerwein salt [Et3 O]+ [SbCl6 ]- to yield 28π Möbius aromatic dication species. Reversible aromatic transition was established by spectroscopic techniques and further supported by quantum chemical calculations.

Tailoring diradicaloid properties of expanded isophlorinoids with systematic core-modification.

Herein, we describe the synthesis, structural diversity and diradicaloid characteristics of 38π core-modified aromatic expanded isophlorins with eight heterocyclic rings. The diradicaloid character of expanded isophlorinoid macrocycles was engineered by systematic structural modification. Depending on the nature of the link between the heteroatoms, they adopt planar and non-planar conformations. This large structural variation with a significant difference in the extent of aromaticity is correlated with the magnitude of their respective diradical character.

Numerical approach to minimize mercury contamination by geometric and parametric optimization.

Due to high vapour pressure at ambient conditions, exposed mercury contributes significant vapour concentration in working atmosphere. Ventilation is a conventional, cheap and very effective method to bring down the concentration of hazardous materials like mercury vapour below permissible limit. In this work a numerical model was developed to obtain intuitive understandings of the spatial distribution of mercury vapors from an exposed surface. The model was validated with experimental data generated using a precinct ventilation system with 8.14% absolute average error. a Validated model was used to study the effect of air flow rate (100-1200 LPM) and impact of architectural design of the containment for fixed exposed mercury surfaceon the final (diluted) mercury concentration. Comparative analysis shows that modification in structural design offers a reduced volume averaged exit mercury concentration and also the reduced peak mercury concentration(Cpeak) in the computational domain. Computational approach outlined in this work can be used to estimate spatial variation of mercury vapor concentration and to locate and quantify regions of high local concentration of mercury in various geometries.

Brush allodynia in hospitalized headache patients.

OBJECTIVE: To describe the incidence and time course of dynamic mechanical allodynia (brush allodynia, BA) in an inpatient headache population. BACKGROUND: Four types of cutaneous allodynia (heat, cold, static mechanical [pressure], and dynamic mechanical [brush] allodynia) can be studied in headache patients. In episodic migraineurs, the development of cutaneous allodynia heralds a change in treatment response. However, little is known about the functional significance of BA, and little is known about the frequency of any type of cutaneous allodynia among patients with chronic or more severe headache disorders. Methods.-The protocol was approved by the institutional review board of our university hospital. A total of 78 subjects were tested for allodynia on days 1, 3, and 5 of an inpatient hospital stay using a 4 x 4 folded gauze pad stroked 10 times at three bilateral sites (forehead, jaw, and forearm). Subjects were queried about the signs and symptoms of their headaches. Headache intensity was graded with a verbal 11-point scale and the intensity of allodynia was graded using a 10 cm visual analog scale. RESULTS: A total of 61 patients had transformed migraine (TM). BA was present at some point during the hospitalization in 32 subjects (41%). Neither age nor duration of daily headache correlated with headache severity. Headache intensity, a history of sensory symptoms or weakness, and subjective blurred vision accompanying the headache correlated with the presence of BA (P< or = .05). Unilateral headaches were more likely to be associated with BA (P = .01), independent of headache severity. When headache was unilateral, BA was greatest ipsilateral to the headache. BA did not influence outcome as measured by length of stay or the likelihood of being discharged headache-free. The rate of decline of headache intensity and allodynia score were similar. CONCLUSION: BA is common in hospitalized headache patients. Subjects with more severe unilateral headaches were more likely to have BA. The presence of BA did not predict treatment failure in an inpatient setting.