Photodissociation Dynamics of Ethyltoluene and p-Fluoroethylbenzene at 193 and 248 nm

Photodissociation of jet-cooled o-, m-, and p-ethyltoluene and p-fluoroethylbenzene at both 193 and 248 nm was studied separately using vacuum ultraviolet photoionization/multimass ion imaging techniques. Dissociation occurs exclusively through alkyl chain C-C bond cleavage. The measured photofragment translational energy distributions at 193 nm decrease monotonically with increasing translational energy. The distributions indicate that dissociation occurs from the ground electronic state after internal conversion. However, the photofragment translational energy distributions from o-, m-, and p-ethyltoluene obtained at 248 nm contain a slow and a fast component; the ratios between these components are 1:4, 1:1.3, and 1:6, respectively. On the other hand, only the slow component was observed from p-fluoroethylbenzene at 248 nm. The fast components are attributed to the dissociation from the triplet state after intersystem crossing, and the slow components result from the dissociation in the ground electronic state. Comparison with the photodissociation of benzene and toluene and ab initio calculation has been made.

Two approaches toward a high-efficiency flashing ratchet

For a flashing ratchet with periodic potentials fluctuating via random shifts of one-half period, a high efficiency is shown to result from two mechanisms. The previously reported one [Yu. A. Makhnovskii, Phys. Rev. E 69, 021102 (2004); V. M. Rozenbaum, JETP Lett. 79, 388 (2004)] is realized in the near-equilibrium region and implies, first, the presence of a high barrier V0 blocking the reverse movement of a Brownian particle and, second, identical, though energy-shifted, portions of the asymmetric flat potential profile on both half periods. We report another mechanism acting far from equilibrium, typical of strongly asymmetric potentials which are shaped identically on both half periods with a large energetic shift DeltaV . The two mechanisms exhibit radically different limiting behavior of the maximum possible efficiency: eta(m) approximately 1-exp (-beta V0 /2) for the former and eta(m) approximately 1-ln (2betaDeltaV) /betaDeltaV for the latter ( beta being the reciprocal temperature in energy units). The flux and the efficiency for a Brownian motor with a piecewise-linear potential are calculated using the transfer matrix method; an exact analytical solution can thus be obtained for an extremely asymmetric sawtooth potential, the simplest example of the second high-efficiency mechanism. As demonstrated, the mechanisms considered are also characteristic of a two-well periodic potential treated in terms of the kinetic approach.

Effect of quantum interference on tunneling photoionization rates of N2 and O2 molecules

In this work, we reexamine the photoionization rates of N(2) and O(2) molecules using the previously published photoionization rate theory which is based on the original atomic Keldysh theory [K. Mishima et al., Phys. Rev. A 66, 033401 (2002); ibid.66, 053408 (2002)]. We have found that the constructive quantum interference takes place for N(2) molecule while the destructive quantum interference plays an important role for O(2) molecule. This is consistent with the experimental and theoretical results reported in the literature. The formulas derived in this paper clearly show that this is due to the different symmetries of the valence orbitals of N(2) and O(2) molecules.

Effect of displacement and distortion of potential energy surfaces and overlapping resonances of electronic transitions on surface-enhanced Raman scattering: Models and ab initio theoretical calculation

A previously developed theory for the temperature-dependent resonance Raman scattering is used to study the surface-enhanced Raman scattering. Two models, the displaced oscillator model and the displaced-distorted oscillator model, based on the harmonic potential energy surfaces are carried out to calculate the surface-enhanced Raman scattering excitation profiles of the pyridine molecule adsorbed on a silver electrode, for which the density functional theory method is applied to evaluate the potential energy surfaces of the adsorption structure. In this framework, the distortion effect on the surface-enhanced Raman scattering will be discussed by comparing both models. The overlapping resonance of multiexcited electronic transitions is also studied, in which the interference between electronic transitions has been taken into account. It will be used to study the abnormal band at 1005.6 cm(-1) with the exciting radiation 457.9 nm.

Towards the realization of the quantum chemistry approach to tunneling photoionization processes in strong laser fields

Based on Keldysh's theory, we investigate the possibility to use the molecular orbital theoretic approach for calculating the tunneling photoionization rates of molecules. As a demonstration, we concentrate on the 1s state of the hydrogen atom as the initial state.

Flashing ratchet model with high efficiency

As a simple model of the Brownian motor, we consider hopping motion of a particle in a periodic asymmetric double-well potential which randomly switches between two states. The potential profiles of the states are identical but shifted by half a period. The current and the efficiency are explicitly calculated as functions of the parameters of the model, including also a load force. Such a flashing ratchet is shown to be particularly efficient, with the efficiency tending to unity when the highest peak of the potential is high enough to suppress the backward motion.

Theoretical differential Raman scattering cross-sections of totally-symmetric vibrational modes of free pyridine and pyridine-metal cluster complexes

The differential Raman scattering cross-sections of totally-symmetric vibrational modes for pyridine and pyridine-metal clusters have been calculated by using ab initio and density functional methods. The results are compared with experimental data and a good agreement is obtained. In particular, we can theoretically reproduce the significant changes in the relative Raman intensities of the nu(12) mode in pyridine-metal cluster complexes. We focus on two mechanisms for these Raman intensities changes: (1) the chemical interaction between the pyridine and the metal clusters; and (2) the charge transfer mechanism. For the pyridine-silver cluster complexes, we find that due to the weak bonding, the chemical interaction does not influence the relative intensities of the Raman peaks of the nu(1) and nu(12) modes. However, in the case where the copper or the gold clusters are attached to pyridine, the intensity of the band of the nu(12) mode is weakened significantly. We also find that the charge transfer mechanism increases the asymmetry of the bands of the nu(1) and nu(12) modes on all three metals.

Adsorption and catalytic oxidation of phenol in a new ozone reactor

Phenolic wastewater treatment in a new ozone reactor was investigated. The reactor was designed in such a fashion that gas induction was created in the reactor headspace by the high-speed action of an impeller turbine inside a draft tube to maximize the ozone utilization. Another important feature of the present reactor design was incorporation of granular activated carbon bed in a circular compartment between the reactor wall and the shaft tube. The fixed granular activated carbon bed was observed to significantly enhance the phenol decomposition and the chemical oxygen demand removal when compared to gas-induced ozonation alone, providing evidence of the synergistic effects of adsorption, catalytic reaction and ozonation. In addition to the enhanced phenol decomposition and chemical oxygen demand, ozonation was found to provide in-situ regeneration of granular activated carbon which was considered crucial in the present reaction system. Kinetic investigations were also made using a proposed complex kinetic model in an attempt to elucidate the possible decomposition reaction mechanisms of the present gas-induced ozonation system.

Steroid-induced tumor lysis syndrome in a patient with preleukemia

Tumor lysis syndrome (TLS) is a well recognized complication of chemotherapy and radiotherapy for leukemia, lymphoma as well as rapidly growing malignancies. Less described is the occurrence of TLS following steroid therapy alone. Herein, we report on a 32-year-old male with myelodysplastic syndrome, characterized by refractory anemia with excess blasts in transformation, who developed acute oliguric renal failure 12 hours after methylprednisolone 1.0 g for presumed autoimmune thrombocytopenia. Laboratory investigations revealed typical findings of TLS, including hyperkalemia, marked hyperuricemia, hyperphosphotemia, hypocalcemia and urine uric acid to creatinine ratio 1.8 (> 1.0). Long hemodialysis (8 hours) was initiated for 3 consecutive sessions. Renal function recovered 1 week later. This case high-lights that single-dose steroid administration in a patient with hematological malignancy may cause the potential life-threatening complications of TLS. Prophylactic management prior to the use of steroid therapy for a variety of purposes is absolutely required in high-risk patients.

Use of reconstruction nails to manage ipsilateral displaced femoral neck-shaft fractures: assessment of a new approach

PURPOSE

Owing to unpredictable femoral neck reduction, reconstruction nails are not suitable for fixation of group 3 ipsilateral femoral neck-shaft fractures. We developed a new one-step fixation technique to overcome this problem. This study aims to assess this new technique at the Orthopaedic Department, Chi-Mei Foundation Medical Center, Tainan.

METHODS

Of 31 consecutive patients with femoral fractures treated by reconstruction nails, five patients had group 3 ipsilateral femoral neck-shaft fractures, 4 of whom were treated by a new surgical technique. Two 5.0-mm drills were firstly inserted to tether the trochanter fragment, and distal locking screws were secondly applied to immobilise the shaft fracture. The neck-shaft angle was then restored in a closed fashion and proximal cephalomedullary screws were attached. Patients were followed up by post-operative radiography.

RESULTS

All 5 cases of group 3 ipsilateral femoral neck-shaft fracture obtained radiographic union without significant surgical sequelae. Three of the patients had implants removed. No patients presented with osteonecrosis at the 3-year follow-up.

CONCLUSION

The new approach to manage ipsilateral femoral neck-shaft fractures by using reconstruction nails obtains relatively good clinical results.

Effect of pretreatment with ketorolac on propofol injection pain

BACKGROUND

: Pain on injection is still a major problem with propofol. We performed this study to compare different doses of intravenous (i.v.) ketorolac with and without venous occlusion and its effect on the incidence and the severity of the pain after propofol injection.

METHODS

We conducted a prospective, randomized and double-blind study of 180 patients (20-60 years of age.) scheduled to undergo elective surgery. Six groups of patients were generated: group A received normal saline (NS) 2 ml i.v.; groups B, C, D received ketorolac 10 mg in 2 ml NS with venous occlusion (VO) and a subsequent propofol injection at either 30, 60 or 120 s; groups E and F received ketorolac 15 mg and 30 mg in 2 ml NS and propofol was injected after 60 s. The pain perception was assessed during injection of propofol in all patients.

RESULT

: The incidence of propofol-associated injection pain was for A: 46.7%; B: 43.4%; C: 23.3%; D:16.7%; E: 20%, and F: 10%. The incidence of pain following propofol injection was reduced by i.v. ketorolac 10 mg with venous occlusion for 120 s. Furthermore, i.v. ketorolac 15 mg and 30 mg but not 10 mg following propofol injection after 60 s without venous occlusion revealed significant pain reduction when compared to saline group. There was no difference in venous sequelae at 7 days postoperatively between the groups.

CONCLUSION

Our results suggested that pretreatment with i.v. 15 and 30 mg ketorolac reduces pain following propofol injection. Moreover, pretreatment with i.v. ketorolac 10 mg with venous occlusion for 120 s achieves the same pain relief effect.

Optimization of multistage phenol adsorption by organobentonites: theoretical developments and experimental verification

Material balance equations were developed for representing phenol adsorption by organobentonites in a countercurrent multistage adsorption process. The developed equations were employed to analyze the adsorption performance of the multistage process. Results of the theoretical analyses using empirical Freundlich adsorption isotherm had shown that the multistage process is more efficient than the single-stage process in terms of phenol removal per unit amount of organobentonite. It was also shown that equal division of the total amount of organobentonite among all adsorption stages yields the best overall phenol removal efficiency for the multistage process in comparison with other organobentonite allocations. The Freundlich adsorption isotherm was confirmed by experimental tests to describe well the phenol adsorption by organobentonites. Results of theoretical performance analyses of the multistage adsorption process were experimentally verified using two- and three-stage test examples.

Arteriovenous fistula using transposed basilic vein in chronic hypotensive hemodialysis patients

AIM

Chronic hypotension is not uncommon in uremic patients on regular hemodialysis. This subset of patients often requires multiple operations to maintain their vascular access due to frequent thrombosis and occlusion of the arteriovenous fistula. Our aims was to assess whether surgical intervention with the brachial artery-transposed basilic vein fistula is effective in chronic hypotensive hemodialysis patients.

MATERIALS AND METHODS

Fifty-four hemodialysis patients with chronic hypotension were enrolled in this study. Most ofthem were referred from local hospitals. They were 23 men and 31 women. The brachial artery-transposed basilic vein arteriovenous fistula was performed in a period of 46 months at the teaching hospital. Primary patency was defined as the length of time from the fistula creation until the development of thrombosis or a complication that required operative revision ofthe fistula. Secondary patency was defined by whether the fistula could be salvaged by revision such that blood flow was maintained.

RESULTS

There was no technical failure and none of these patients died due to the surgical operation. The primary patency rate was 89.80% at 1 year, 73.08% at 2 years, and 64.710% at 3 years. The secondary patency rate was 95.92% at 1 year, 84.62% at 2 years, and 76.47% at 3 years.

CONCLUSIONS

Brachial artery-transposed basilic vein arteriovenous fistula may present good primary alternative vascular access in chronic hypotensive hemodialysis patients.

Photoisomerization and photodissociation of toluene in molecular beam

The photodissociation of isotope-labeled toluene C(6)H(5)CD(3) and C(6)H(5)(13)CH(3) molecules at 6.4 eV under collision-free conditions was studied in separate experiments by multimass ion imaging techniques. In addition to the major dissociation channels, C(6)H(5)CD(3) --> C(6)H(5)CD(2) + D and C(6)H(5)CD(3) --> C(6)H(5) + CD(3), the respective photofragments CD(2)H, CDH(2), and CH(3) and their heavy fragment partners C(6)H(4)D, C(6)H(3)D(2), and C(6)H(2)D(3) were observed from C(6)H(5)CD(3) dissociation. Photofragments (13)CH(3) and CH(3), and their heavy fragment partners C(6)H(5) and (13)CC(5)H(5), were also observed from C(6)H(5)(13)CH(3) dissociation. Our results show that 25% of the excited toluene isomerizes to a seven-membered ring (cycloheptatriene) and then rearomatizes prior to dissociation. The isomerization pathway competes with direct C-C bond and C-H bond dissociation. The significance of this isomerization is that the carbon atoms and hydrogen atoms belonging to the alkyl group are involved in an exchange with those atoms in the aromatic ring during isomerization. The dissociation rate of toluene at 193 nm is measured to be (1.17 +/- 0.1) x 10(6) s(-)(1).

Severe hyponatremia as the presenting feature of clinically non-functional pituitary adenoma with hypopituitarism

Hyponatremia can result from a wide range of causes. While hyponatremia is known to occur in patients with hypopituitarism, severe hyponatremia occurring as the presenting feature of hypopituitarism is very rare. We present two cases in which severe hyponatremia developed with weakness, light-headedness and seizure. The hyponatremia in these 2 cases mimicked the laboratory diagnostic criteria of a syndrome of inappropriate secretion of antidiuretic hormone (SIADH). However, the hormone studies displayed hypopituitarism. Hyponatremia was completely corrected after administering a supplement of prednisolone and L-thyroxine. Computerized tomography of the brain revealed an adenoma of the pituitary gland. These two cases illustrate that severe hyponatremia may be the presenting feature of clinically non-functional pituitary adenoma with hypopituitarism, which should be kept in mind in the differential diagnosis of hyponatremia mimicking SIADH.

Adsorption of phenol and m-chlorophenol on organobentonites and repeated thermal regeneration

Experimental investigations were conducted on the adsorption characteristics of phenol and m-chlorophenol by organobentonites. The organobentonites were prepared by modifying natural bentonite with various quaternary ammonium salts including tetramethylammonium bromide, hexadecyltrimethylammonium bromide, benzyl-triethylammonium bromide, tetraethylammonium bromide and cetylpyridinium bromide. The adsorption characteristics of phenol and chlorophenol by these organobentonites were examined in detail. The empirical Freundlich isotherm was found to describe well the equilibrium adsorption data. Thermal regeneration of spent organobentonites was also investigated and operating conditions of 200 degrees C and 2 h heating were found to yield very good results.

NudC associates with Lis1 and the dynein motor at the leading pole of neurons

NUDC is a highly conserved protein important for nuclear migration and viability in Aspergillus nidulans. Mammalian NudC interacts with Lis1, a neuronal migration protein important during neocorticogenesis, suggesting a conserved mechanism of nuclear movement in A. nidulans and neuronal migration in the developing mammalian brain (S. M. Morris et al., 1998). To further investigate this possibility, we show for the first time that NudC, Lis1, and cytoplasmic dynein intermediate chain (CDIC) colocalize at the microtubule organizing center (MTOC) around the nucleus in a polarized manner facing the leading pole of cerebellar granule cells with a migratory morphology. In neurons with stationary morphology, NudC is distributed throughout the soma and colocalizes with CDIC and tubulin in neurites as well as at the MTOC. At the subcellular level, NudC, CDIC, and p150 dynactin colocalize to the interphase microtubule array and the MTOC in fibroblasts. The observed colocalization is confirmed biochemically by coimmunoprecipitation of NudC with CDIC and cytoplasmic dynein heavy chain (CDHC) from mouse brain extracts. Consistent with its expression in individual neurons, a high level of NudC is detected in regions of the embryonic neocortex undergoing extensive neurogenesis as well as neuronal migration. These data suggest a biochemical and functional interaction of NudC with Lis1 and the dynein motor complex during neuronal migration in vivo.

Dynamics of the spin-boson Hamiltonian by the projection operator technique: applications to electron transfer reactions

A perturbative treatment developed by using the projection operator technique is provided to find dynamics of the spin-boson Hamiltonian in the second order approximation of the subsystem-bath interaction. In the framework of the generalized master equations and in the Markovian approximation it leads to the Redfield/Bloch-type equations. The treatment can be applied to both fast and slow bath cases; in this paper we consider the fast bath case. The relaxation times, energy splitting, and bath-induced renormalization effect of the coherence frequency are discussed and applied to a Lorentzian-Ohmic fast bath. A good agreement between our results and those obtained by the path-integral formalism is obtained. The treatment is applied to electron transfer reactions to test the possibility of apparition of the electronic coherence in certain photosynthetic reaction centers.

Androgen regulation of the cell-cell adhesion molecule-1 (Ceacam1) gene

Previous studies have established that the cell-cell adhesion molecule-1 (CEACAM1, previously known as C-CAM1) functions as a tumor suppressor in prostate cancer and is involved in the regulation of prostate growth and differentiation. However, the molecular mechanism that modulates CEACAM1 expression in the prostate is not well defined. Since the growth of prostate epithelial cells is androgen-regulated, we investigated the effects of androgen and the androgen receptor (AR) on CEACAM1 expression. Transient transfection experiments showed that the AR can enhance the Ceacam1 promoter activity in a ligand-dependent manner and that the regulatory element resides within a relatively short (-249 to -194 bp) segment of the 5'-flanking region of the Ceacam1 gene. This androgen regulation is likely through direct AR-promoter binding because a mutant AR defective in DNA binding failed to upregulate reporter gene expression. Furthermore, electrophoretic mobility shift assays demonstrated that the AR specifically binds to this sequence, and mutation analysis of the potential ARE sequences revealed a region within the sequence that was required for the AR to activate the Ceacam1 gene. Therefore, the regulation of Ceacam1 gene expression by androgen may be one of the mechanisms by which androgen regulates prostatic function.

The carboxyl terminus of the prolactin-releasing peptide receptor interacts with PDZ domain proteins involved in alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor clustering

PDZ domain proteins use the PDZ domain binding motif to bind to the C-terminal sequence of membrane proteins to help scaffold them and spatially organize the components of the intracellular signaling machinery. We have identified a sequence at the C terminus of a G protein-coupled receptor, the PrRP receptor, that shares similarities with the C-terminal sequence of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (AMPA-R) subunits that interact with PDZ domain proteins. When coexpressed in human embryonic kidney 293 cells, PrRP receptor was able to coimmunoprecipitate the three PDZ domain proteins known to interact with AMPA receptors: glutamate receptor interacting protein (GRIP), AMPA binding protein (ABP), and protein that interacts with C-kinase (PICK1), but not the PDZ domain protein PSD-95, which does not interact with AMPA receptors. These interactions are sequence-selective as determined by mutagenesis. Furthermore, we show that PrRP receptor forms intracellular clusters when coexpressed with PICK1, and that this clustering effect is dependent on the interaction between the PICK1 PDZ domain and the last four amino acids of PrRP receptor. We found that PrRP receptor interaction with GRIP is not protein kinase C-regulated but may be regulated by other unidentified kinase because okadaic acid dramatically reduced GRIP interaction. By in situ hybridization, we show that the PrRP receptor is expressed in neurons that also express these PDZ domain proteins. We thus demonstrate that PrRP receptor interacts with the same PDZ domain proteins as the AMPA-Rs, raising the possibility that these two proteins could be scaffolded together at the synapse. These results may help to gain important insights into PrRP functions within the central nervous system.

The applications of capture-recapture models to epidemiological data

Capture-recapture methodology, originally developed for estimating demographic parameters of animal populations, has been applied to human populations. This tutorial reviews various closed capture-recapture models which are applicable to ascertainment data for estimating the size of a target population based on several incomplete lists of individuals. Most epidemiological approaches merging different lists and eliminating duplicate cases are likely to be biased downwards. That is, the final merged list misses those who are in the population but were not ascertained in any of the lists. If there are no matching errors, then the duplicate information collected from a capture-recapture experiment can be used to estimate the number of missed under proper assumptions. Three approaches and their associated estimation procedures are introduced: ecological models; log-linear models, and the sample coverage approach. Each approach has its unique way of incorporating two types of source dependencies: local (list) dependence and dependence due to heterogeneity. An interactive program, CARE (for capture-recapture) developed by the authors is demonstrated using four real data sets. One set of data deals with infection by the acute hepatitis A virus in an outbreak in Taiwan; the other three sets are ascertainment data on diabetes, spina bifida and infants' congenital anomaly discussed in the literature. These data sets provide examples to show the usefulness of the capture-recapture method in correcting for under-ascertainment. The limitations of the methodology and some cautionary remarks are also discussed.