Solid Parahydrogen Infrared Matrix Isolation and Computational Studies of Lin-(C2H4)m Complexes.

Complexes of lithium atoms with ethylene have been identified as potential hydrogen storage materials. As a Li atom approaches an ethylene molecule, two distinct low-lying electronic states are established; one is the 2A1 electronic state (for C2v geometries) that is repulsive but supports a shallow van der Waals well and correlates with the Li 2s atomic state, and the second is a 2B2 electronic state that correlates with the Li 2p atomic orbital and is a strongly bound charge-transfer state. Only the 2B2 charge-transfer state would be advantageous for hydrogen storage because the strong electric dipole created in the Li-(C2H4) complex due to charge transfer can bind molecular hydrogen through dipole-induced dipole and dipole-quadrupole electrostatic interactions. Ab initio studies have produced conflicting results for which electronic state is the true ground state for the Li-(C2H4) complex. The most accurate ab initio calculations indicate that the 2A1 van der Waals state is slightly more stable. In contrast, argon matrix isolation experiments have clearly identified the Li-(C2H4) complex exists in the 2B2 state. Some have suggested that argon matrix effects shift the equilibrium toward the 2B2 state. We report the low-temperature synthesis and IR characterization of Lin-(C2H4)m (n = 1, m = 1 and 2) complexes in solid parahydrogen which are observed using the C═C stretching vibration of ethylene in the complex. These results show that under cryogenic hydrogen storage conditions the Li-(C2H4) complex is more stable in the 2B2 electronic state and thus constitutes a potential hydrogen storage material with desirable characteristics.

Outcomes and cost-effectiveness of ultrasound-guided injection of the trochanteric bursa.

We hypothesized that ultrasound (US) guidance improves outcomes of corticosteroid injection of trochanteric bursitis. 40 patients with greater trochanteric pain syndrome defined by pain to palpation over the trochanteric bursa were randomized to injection with 5 ml of 1% lidocaine and 80 mg of methylprednisolone using (1) conventional anatomic landmark palpation guidance or (2) US guidance. Procedural pain (Visual Analogue Pain Scale), pain at outcome (2 weeks and 6 months), therapeutic duration, time-to-next intervention, and costs were determined. There were no complications in either group. Ultrasonography demonstrated that at least a 2-in (50.8 mm) needle was required to consistently reach the trochanteric bursa. Pain scores were similar at 2 weeks: US: 1.3 ± 1.9 cm; landmark: 2.2 ± 2.5 cm, 95% CI of difference: - 0.7 < 0.9 < 2.5, p = 0.14. At 6 months, US was superior: US: 3.9 ± 2.0 cm; landmark: 5.5 ± 2.6 cm, 95% CI of difference: 0.8 < 1.6 < 2.4, p = 0.036. However, therapeutic duration (US 4.7 ± 1.4 months; landmark 4.1 ± 2.9 months, 95% CI of difference - 2.2 < - 0.6 < 1.0, p = 0.48), and time-to-next intervention (US 8.7 ± 2.9 months; landmark 8.3 ± 3.8 months, 95% CI of difference - 2.8 < - 0.4 < 2.0, p = 0.62) were similar. Costs/patient/year was 43% greater with US (US $297 ± 99, landmark $207 ± 95; p = 0.017). US-guided and anatomic landmark injection of the trochanteric bursa have similar 2-week and 6-month outcomes; however, US guidance is considerably more expensive and less cost-effective. Anatomic landmark-guided injection remains the method of choice, but should be routinely performed using a sufficiently long needle [at least a 2 in (50.8 mm)]. US guidance should be reserved for extreme obesity or injection failure.

Fabrication, characterization, and energetic properties of metallized fibers.

Polystyrene fibers loaded with an energetic blend of nanoaluminum (n-Al) and perfluoropolyether (PFPE) were successfully fabricated via electrospinning producing nanothermite fabrics. Fibers were generated with loadings up to 17 wt % n-Al/PFPE incorporated into the fiber. Microscopy analysis by SEM and TEM confirm a uniform dispersion of PFPE treated n-Al on the outside and inside of the fibers. Metallized fibers were thermally active upon immediate ignition from a controlled flame source. Thermal analysis by differential scanning calorimetry (DSC) found no change in glass transition temperature when comparing pure polystyrene fibers with fibers loaded up to 17 wt % n-Al/PFPE. Thermal gravimetric analysis (TGA) revealed a shift in decomposition temperatures to lower onsets upon increased loadings of n-Al/PFPE blends, consistent with previous studies. Flame propagation studies confirmed that the metallized fibers are pryolants. These metallized fibers are a recent development in metastable intermolecular composites (MICs) and details of their synthesis, characterization, and thermal properties are presented.

High-resolution infrared spectroscopy of atomic bromine in solid parahydrogen and orthodeuterium.

This work extends our earlier investigation of the near-infrared absorption spectroscopy of atomic bromine (Br) trapped in solid parahydrogen (pH2) and orthodeuterium (oD2) [S. C. Kettwich, L. O. Paulson, P. L. Raston, and D. T. Anderson, J. Phys. Chem. A 112, 11153 (2008)]. We report new spectroscopic observations on a series of double transitions involving excitation of the weak Br-atom spin-orbit (SO) transition ((2)P(1/2) ← (2)P(3/2)) in concert with phonon, rotational, vibrational, and rovibrational excitation of the solid molecular hydrogen host. Further, we utilize the rapid vapor deposition technique to produce pH2 crystals with a non-equilibrium mixture of face centered cubic (fcc) and hexagonal closed packed (hcp) crystal domains in the freshly deposited solid. Gentle annealing (T = 4.3 K) of the pH2 sample irreversibly converts the higher energy fcc crystal domains to the slightly more stable hcp structure. We follow the extent of this conversion process using the intensity of the U1(0) transition of solid pH2 and correlate crystal structure changes with changes in the integrated intensity of Br-atom absorption features. Annealing the pH2 solid causes the integrated intensity of the zero-phonon Br SO transition to increase approximately 45% to a value that is 8 times larger than the gas phase value. We show that the magnitude of the increase is strongly correlated to the fraction of hcp crystal domains within the solid. Theoretical calculations presented in Paper II show that these intensity differences are caused by the different symmetries of single substitution sites for these two crystal structures. For fully annealed Br-atom doped pH2 solids, where the crystal structure is nearly pure hcp, the Br-atom SO transition sharpens considerably and shows evidence for resolved hyperfine structure.

Transient H2O Infrared Satellite Peaks Produced in UV Irradiated Formic Acid Doped Solid Parahydrogen.

We report newly identified satellite features of the R(0) rovibrational transition of all the fundamental modes of HDO and the ν3 mode of H2O measured via FTIR spectroscopy immediately after the 193 nm in situ photolysis of formic acid (HCOOH and DCOOD) in solid parahydrogen. The intensities of these satellite features decay slowly with a time constant of τ = 121(7) min after photolysis, even when the sample is maintained below 2 K. We propose that the van der Waals complex H···H2O (H···HDO) is the carrier of the satellite peaks and that these metastable complexes are produced after the low-temperature tunneling reaction of the OH (OD) photoproduct with the parahydrogen host.

The Cl + H2 --> HCl + H reaction induced by IR + UV irradiation of Cl2 in solid para-H2: experiment.

We report IR + UV coirradiation photolysis experiments conducted on Cl(2)-doped para-hydrogen (p-H(2)) crystals at 1.8 K, using pulsed 355 nm UV radiation and cw broad-band near-IR light from a FTIR tungsten source. The amount of HCl photoproduct is monitored using FTIR spectroscopy as a function of the IR + UV exposure time. Detailed analysis of the HCl growth kinetics reveals that the reaction Cl + H(2)(v=1,J=0) --> HCl + H is playing a significant (15%) role in the in situ photochemistry. In contrast, UV-only photolysis experiments conducted under similar conditions produce almost exclusively (99%) isolated Cl atom photofragments, indicating the reaction Cl + H(2)(v=0,J=0) --> HCl + H is not readily occurring. This combination of photolysis experiments confirms that under these conditions, the Cl + H(2) reaction probability increases by a factor greater than 25 for Cl atom reactions with H(2)(v=1) versus H(2)(v=0). These results are therefore consistent with the expectation that vibrational excitation of the H(2) reagent lowers the reaction threshold and increases the reaction cross section for the Cl + H(2) reaction. These experimental studies were motivated by and are compared to the quantum model simulations reported by Korolkov, Manz, and Schild in the accompanying paper.

Synthesis and infrared characterization of Br-HBr and Br-DBr entrance channel complexes in solid parahydrogen.

We report high resolution vibrational spectra in the HBr (2560 cm(-1)) and DBr (1840 cm(-1)) stretching regions for Br-HBr and Br-DBr entrance channel complexes isolated in solid parahydrogen (pH2). The Br-HBr complexes are generated by synthesizing solid pH2 crystals doped with trace amounts of HBr/Br2 mixtures followed by 355 nm in situ photodissociation of Br2 to form Br atoms. After photolysis is complete, the solid is warmed from 2 to 4.3 K resulting in the irreversible formation of Br-HBr complexes. The large 36.63 cm(-1) HBr monomer-to-complex induced vibrational shift to lower energy measured in these studies is consistent with the linear Br-HBr hydrogen bonded structure predicted from theory. The 0.02 cm(-1) Br-HBr absorption linewidths indicate a 1 ns vibrational excited state lifetime for these entrance channel complexes in solid pH2.

Photodissociation of molecular bromine in solid H2 and D2: spectroscopy of the atomic bromine spin-orbit transition.

We report 355 nm photodissociation studies of molecular bromine (Br2) trapped in solid parahydrogen (pH2) and orthodeuterium (oD2). The product Br atoms are observed via the spin-orbit transition ((2)P(1/2)<-- (2)P(3/2)) of atomic bromine. The quantum yield (Phi) for Br atom photoproduction is measured to be 0.29(3) in pH2 and 0.24(2) in oD2, demonstrating that both quantum solids have minimal cage effects for Br2 photodissociation. The effective Br spin-orbit splitting increases when the Br atom is solvated in solid pH2 (+1.1%) and oD2 (+1.5%); these increases are interpreted as evidence that the solvation energy of the Br ground fine structure state ((2)P(3/2)) is significantly greater than the excited state ((2)P(1/2)). Molecular bromine induced H2 infrared absorptions are detected in the Q1(0) and S1(0) regions near 4150 and 4486 cm(-1), respectively, which allow the relative Br2 concentration to be monitored as a function of 355 nm photolysis.

A randomized, controlled trial of the reciprocating procedure device for local anesthesia.

The purpose of this study was to determine whether the new reciprocating procedure device (RPD) is superior to the conventional syringe for the administration of local anesthesia. There were 209 local lidocaine anesthesia procedures randomized between the RDP and the conventional syringe. Outcome measures included administration time, anesthesia pain, procedure pain, and operator satisfaction. The RPD significantly reduced anesthesia administration time by 49% (RPD: 0.68 +/- 0.59 min, Syringe: 1.32 +/- 1.01 min, p < 0.001, 95% confidence interval [CI] for % reduction: 36%-60%), reduced anesthesia pain by 27% (RPD visual analog pain scale score: 4.05 +/- 2.64; Syringe: 5.55 +/- 3.00; p < 0.001, 95% CI 14%-38%), reduced significant procedure pain by 74% (p < 0.001, 95% CI 60%-87%), and improved physician satisfaction by 63% (p < 0.001, 95% CI 53%-74%). The RPD markedly reduces the pain associated with lidocaine anesthesia administration, reduces administration time, and maintains the effectiveness of local anesthesia. The RPD is superior to and significantly more effective than the conventional syringe for the administration of local lidocaine anesthesia.

A randomized controlled trial of the reciprocating procedure device for intraarticular injection of corticosteroid.

OBJECTIVE: Injection of intraarticular corticosteroid remains an important therapy for inflammatory arthritis. In a randomized controlled trial we compared the new reciprocating procedure device (RPD) to the traditional syringe for injection of intraarticular corticosteroid. METHODS: One hundred fifty-four intraarticular corticosteroid injection procedures were randomized to the conventional syringe or the RPD. Using the syringe or RPD, the needle was introduced into the joint, any effusion that was present was aspirated, and the corticosteroid (methylprednisolone acetate) was injected. Outcome measures included patient pain measured by visual analog scale (VAS pain), procedure duration, operator satisfaction, complications, and immediate and delayed response to the injected medication. RESULTS: The RPD reduced pain scores by 49% (RPD VAS pain score: 2.40 +/- 2.17; conventional syringe VAS pain score: 4.73 +/- 3.39; p < 0.001), reduced procedure time by 31% (RPD: 1.28 +/- 1.08 min, conventional syringe: 1.86 +/- 1.26; p < 0.01), and improved physician satisfaction with the joint procedure device by 63% (RPD visual analog satisfaction scale score: 9.12 +/- 0.80, conventional syringe 5.59 +/- 1.28; p < 0.001). Fifty-five percent (43/78) of patients experienced moderate to severe pain (VAS pain > or = 5) with the conventional syringe, while 17% (13/76) experienced moderate to severe pain with the RPD. The same beneficial response was present when intermediate or large joints were analyzed separately. Longterm outcomes were equivalent. CONCLUSION: When a conventional syringe is used for corticosteroid injection, many patients experience significant procedural pain. The RPD significantly reduces patient pain, reduces procedure time, and improves operator satisfaction. The RPD is superior to the traditional syringe for injection of intraarticular corticosteroid.

Needle phobia and stress-reducing medical devices in pediatric and adult chemotherapy patients.

Needle phobia--fear of medical devices--is a significant problem in pediatric and adult chemotherapy patients. Stress-reducing medical devices is a new, effective cognitive therapy for needle phobia. Twenty-five pediatric and 25 adult chemotherapy patients were randomly exposed to conventional or stress-reducing decorated butterfly needles and syringes. Emotional stress responses were determined with the Visual Aversion Scale, Visual Analogue Fear Scale, Visual Analogue Anxiety Scale, and Visual Overall Stress Score for each needle and syringe design. Sixty-eight percent of the pediatric and 52% of the adult patients were overtly needle phobic, but children demonstrated significantly more aversion and stress (P < .001). Stress-reducing medical devices effectively and significantly reduced aversion, anxiety, fear, and overall stress, and were 76% effective in preventing overt needle phobia in children and 92% effective in adults (P < .001). One hundred percent of children and adults felt that stress-reducing medical devices should be available in chemotherapy clinics. Needle phobia and stress in pediatric and adult chemotherapy patients are significantly reduced by the use of stress-reducing medical devices.

Control and performance characteristics of eight different suction biopsy devices.

PURPOSE: To determine the control and performance characteristics of eight different suction biopsy devices. MATERIALS AND METHODS: Physician control of the syringe and needle was measured precisely with the validated linear displacement method during the aspiration phase and during five biopsy passes. The visual analog scale was used to measure operator difficulty in the following domains: (i) attachment to the needle, (ii) generation of vacuum, (iii) detection of loss of vacuum, (iv) release of the vacuum, and (v) clearing of the sample from the needle. RESULTS: Performance in various phases of the biopsy procedure varied widely among the biopsy devices tested. Unintended forward penetration (ie, loss of control in the forward direction) was significant with the reverse aspiration syringe (31.5 +/- 1.7 mm), three-ringed control syringe (25.4 +/- 4.1 mm), BioSuc-C7 syringe (28.3 +/- 1.9 mm), conventional syringe with a plunger lock (6.1 +/- 1.5 mm), syringe pistol (9.2 +/- 2.4 mm), and conventional syringe (3.8 +/- 2.9 mm) but was significantly less for the reciprocating procedure device (RPD; 0.7 +/- 0.7 mm; P