Reactivity and Product Selectivity of Fluoroalkyl Carbonates in Substitution Reactions with Primary Alcohols and Amines.

The present study reports a systematic investigation of the substitution reactions of a series of symmetric and unsymmetric fluoroalkyl carbonates with primary alcohols or amines. The reactivity of the haloalkyl carbonate depends mainly on the electrophilicity and steric crowdedness of the carbonyl group and the leaving ability of the haloalkyl alcohols. Diethyl carbonate as a reference substrate showed no reaction with the alcohol or amine. However, bis(2,2,2-trifluoroethyl) carbonate [(F3-EtO)2CO] having electron-withdrawing trifluoroethyl groups enabled substitution reactions, with relatively higher reactivities to those for diphenyl carbonate [(PhO)2CO]. Furthermore, (F6-iPrO)2CO, bearing two sets of hexafluoroisopropyl groups, showed dramatic acceleration of the reactions, in which the observed reactivities were similar to those for bis(perfluorophenyl) carbonate [(F5-PhO)2CO]. The electrophilicity of the carbonyl group and the leaving ability of the alcohols in the series of haloalkyl carbonates were found to be correlated with the wavenumbers of their carbonyl groups in IR spectra and pKa for the eliminated alcohols, respectively. Since the eliminated fluoroalkyl alcohols exhibit weak affinity with the organic products and have lower boiling points owing to a characteristic property of the fluoroalkyl group, they could be readily removed from the product by simple evaporation below 100 °C with or without reduced pressure.

Enhancing terahertz magnetic near field induced by a micro-split-ring resonator with a tapered waveguide.

Substantial enhancement of terahertz magnetic near field achieved by the combination of a tapered metallic waveguide and a micro-split-ring resonator is demonstrated. The magnetic near field is probed directly via the magneto-optic sampling with a Tb3Ga5O12 crystal. The incident terahertz wave with a half-cycle waveform is generated by using the pulse-front tilting method. The magnetic near field at the resonant frequency is enhanced by more than 30 times through the combination of the waveguide and the resonator. The peak amplitude of the magnetic field with a damped oscillation waveform in the time domain is up to 0.4 T. The resonant frequency can be tuned by adopting different resonator designs. The mechanism of the enhancement is analyzed by performing calculations based on the finite element method. The strong terahertz magnetic near field enables the excitation of large-amplitude spin dynamics and can be utilized for an ultrafast spin control.

Interdomain flip-flop motion visualized in flavocytochrome cellobiose dehydrogenase using high-speed atomic force microscopy during catalysis.

Cellobiose dehydrogenase (CDH) is a dual domain flavocytochrome, which consists of a dehydrogenase (DH) domain containing a flavin adenine dinucleotide and a cytochrome (CYT) domain containing b-type heme. To directly visualize the dynamic domain motion of class-I CDH from Phanerochaete chrysosporium (PcCDH) during catalysis using high-speed atomic force microscopy, the apo-form of PcCDH was anchored to a heme-immobilized flat gold surface that can specifically fix the orientation of the CYT domain. The two domains of CDH are found to be immobile in the absence of cellobiose, whereas the addition of cellobiose triggers an interdomain flip-flop motion involving domain-domain association and dissociation. Our results indicate that dynamic motion of a dual domain enzyme during catalysis induces efficient electron transfer to an external electron acceptor.

Photocatalytic Properties of TiO2 Composites Immobilized with Gold Nanoparticle Assemblies Using the Streptavidin-Biotin Interaction.

A method using biomolecules to precisely fabricate the morphology of metal nanoparticles immobilized on the surface of a semiconductor using biomolecules is described. A biotin moiety (Biot) is introduced onto the surface of a gold nanoparticle (AuNP) by covalent coupling with α-lipoic acid to assemble AuNPs in the presence of streptavidin (STV). The assembly of Biot-AuNP/STV is immobilized on the surface of TiO2 chemically modified with 1-(3-aminopropyl)silatrane (APS) to provide a positively charged surface. The Au content immobilized on the surface of TiO2 is clearly increased to 9.5 wt % (Au) as a result of the STV-biotin interaction and the electrostatic interaction between negatively charged Biot-AuNPs and the positively charged surface of APS/TiO2. Transmission electron microscopy (TEM) analysis reveals that the composite has an ordered surface geometry in which Biot-AuNPs are spread over the composite surface in two dimensions. The photocatalytic activity toward decomposition of methyl orange dye promoted by this composite is 55%, which is higher than that of the other composites. The Biot-AuNP/STV@APS/TiO2 composite efficiently reduces O2 molecules at Eonset = -0.23 V vs Ag|AgCl, which is more positive than that of other composites (Eonset = -0.40 to -0.32 V). The result suggests that an increased number of AuNPs immobilized in close contact with the TiO2 surface facilitates photoinduced charge transfer. This strategy, which takes advantage of the specific interactions provided by biomolecules and the chemical modification on the surface, has remarkable potential for efficient fabrication of metal nanoparticles on the surface of the semiconductor, which accelerates the reduction of oxygen molecules.

Evaluation of defects generation in crystalline silicon ingot grown by cast technique with seed crystal for solar cells.

Although crystalline silicon is widely used as substrate material for solar cell, many defects occur during crystal growth. In this study, the generation of crystalline defects in silicon substrates was evaluated. The distributions of small-angle grain boundaries were observed in substrates sliced parallel to the growth direction. Many precipitates consisting of light elemental impurities and small-angle grain boundaries were confirmed to propagate. The precipitates mainly consisted of Si, C, and N atoms. The small-angle grain boundaries were distributed after the precipitation density increased. Then, precipitates appeared at the small-angle grain boundaries. We consider that the origin of the small-angle grain boundaries was lattice mismatch and/or strain caused by the high-density precipitation.

Subsurface damage of single crystalline silicon carbide in nanoindentation tests.

The response of single crystalline silicon carbide (SiC) to a Berkovich nanoindenter was investigated by examining the indents using a transmission electron microscope and the selected area electron diffraction technique. It was found that the depth of indentation-induced subsurface damage was far larger than the indentation depth, and the damaging mechanism of SiC was distinctly different from that of single crystalline silicon. For silicon, a broad amorphous region is formed underneath the indenter after unloading; for SiC, however, no amorphous phase was detected. Instead, a polycrystalline structure with a grain size of ten nanometer level was identified directly under the indenter tip. Micro cracks, basal plane dislocations and possible cross slips were also found around the indent. These finding provide useful information for ultraprecision manufacturing of SiC wafers.

Carbachol injection into the pontine reticular formation depresses laryngeal muscle activities and airway reflexes in decerebrate cats.

To understand the role of cholinoceptive, medial pontine reticular formation (mPRF) neurons in the control of upper airway, pharyngolaryngeal reflexes, we measured activities of intrinsic laryngeal muscles (posterior cricoarytenoid, PCA; thyroarytenoid, TA), diaphragm (DIA), genioglossus (GG) and a neck muscle (trapezius) in unanesthetized, decerebrated, spontaneously breathing cats with and without mPRF carbachol injections. The ethimoidal nerve was electrically stimulated to evoke sneezing, and the superior laryngeal nerve to evoke the laryngeal reflex, swallowing, and coughing. Carbachol reduced the amplitudes of the spontaneous electromyographic activities in the neck, TA, PCA, GG, and DIA to 7%, 30%, 54%, 45% and 71% of control, respectively, reduced the respiratory rate to 53% without changes in expiratory CO(2) concentration; the magnitude of the laryngeal reflex in the TA muscle to 56%; increased its latency by 13%; and reduced the probability of stimulus-induced sneezing, swallowing, and coughing to less than 40%. These changes lasted more than 1h. These data demonstrate that important upper airway reflexes are suppressed by increasing cholinergic neurotransmission in the mPRF. Because acetylcholine release in the mPRF changes in accordance with sleep-wake cycles, the present findings are relevant to the control of upper airway reflexes during various vigilance states.

Course of hearing recovery according to frequency in patients with acute acoustic sensorineural hearing loss.

Through pure-tone audiometry, we studied the course of hearing recovery in 24 ears of 20 men (ages 18-48 years) who had acute acoustic sensorineural hearing loss (ASHL). All subjects were members of the Japanese Self-Defense Force. The hearing level in 5 ears returned to normal, the hearing level of 13 ears recovered but was not within the normal range, and the hearing level of 6 ears was unchanged. The time from noise exposure to presentation was longer in patients with unchanged hearing than in other patients. Recovery of hearing was poorest at 4,000 Hz, followed by 8,000 and 2,000 Hz. We concluded that hearing in patients with acute ASHL is likely to return to normal when the hearing level at 4,000 Hz recovers gradually; partial recovery of hearing is expected when the hearing level at 4,000 Hz reaches an early plateau.

Orexinergic projections to the cat midbrain mediate alternation of emotional behavioural states from locomotion to cataplexy.

Orexinergic neurones in the perifornical lateral hypothalamus project to structures of the midbrain, including the substantia nigra and the mesopontine tegmentum. These areas contain the mesencephalic locomotor region (MLR), and the pedunculopontine and laterodorsal tegmental nuclei (PPN/LDT), which regulate atonia during rapid eye movement (REM) sleep. Deficiencies of the orexinergic system result in narcolepsy, suggesting that these projections are concerned with switching between locomotor movements and muscular atonia. The present study characterizes the role of these orexinergic projections to the midbrain. In decerebrate cats, injecting orexin-A (60 microm to 1.0 mm, 0.20-0.25 microl) into the MLR reduced the intensity of the electrical stimulation required to induce locomotion on a treadmill (4 cats) or even elicit locomotor movements without electrical stimulation (2 cats). On the other hand, when orexin was injected into either the PPN (8 cats) or the substantia nigra pars reticulata (SNr, 4 cats), an increased stimulus intensity at the PPN was required to induce muscle atonia. The effects of orexin on the PPN and the SNr were reversed by subsequently injecting bicuculline (5 mm, 0.20-0.25 microl), a GABA(A) receptor antagonist, into the PPN. These findings indicate that excitatory orexinergic drive could maintain a higher level of locomotor activity by increasing the excitability of neurones in the MLR, while enhancing GABAergic effects on presumably cholinergic PPN neurones, to suppress muscle atonia. We conclude that orexinergic projections from the hypothalamus to the midbrain play an important role in regulating motor behaviour and controlling postural muscle tone and locomotor movements when awake and during sleep. Furthermore, as the excitability is attenuated in the absence of orexin, signals to the midbrain may induce locomotor behaviour when the orexinergic system functions normally but elicit atonia or narcolepsy when the orexinergic function is disturbed.

Effects of injecting GABAergic agents into the medullary reticular formation upon swallowing induced by the superior laryngeal nerve stimulation in decerebrate cats.

The purpose of this study was to elucidate the role of the GABAergic system in the medullary reticular formation (MRF) in the control of swallowing. In acutely decerebrated cats (n = 12), swallowing was induced by electrical stimulation (0.3-6 V at 10-20 Hz for 10-20 s every minute) applied to the superior laryngeal nerve (SLN). The stimulus intensity was adjusted so that swallowing was induced two or four times during the period of the stimulation. Bicuculline, a GABA(A) receptor antagonist, was then injected (0.10-0.15 microl, 5 mM) into the MRF through a stereotaxically placed glass micropipette. In a total of 62 injections, 19 injections (30.6%) increased the frequency of SLN-induced swallowing when it was injected into the lateral part of the MRF corresponding to the nucleus reticularis parvocellularis (NRPv). In eight of the effective injections (42.1%) which increased the frequency of SLN-induced swallowing, SLN stimulation also induced coughing. With two injections, stimulation of the SLN-induced coughing but not facilitation of swallowing. On the other hand, an injection of 0.10-0.15 microl of 5 mM muscimol, a GABA(A) receptor agonist, into the NRPv decreased the frequency of SLN-induced swallowing. These results suggest that the NRPv neurons which are responsible for evoking swallowing are under the tonic inhibitory control of the GABAergic system.

Prognosis for sudden sensorineural hearing loss: a retrospective study using logistical regression analysis.

Sudden sensorineural hearing loss (SSNHL) remains a controversial problem with respect to etiology and the factors that might predict prognosis. We used logistical regression analysis to determine which factors are most strongly related to outcome for patients with SSNHL. In so doing, we employed a retrospective chart-review study. The study group consisted of 296 patients (296 ears). The outcome of SSNHL was cured (full recovery) in 64, recovered (partial recovery) in 175, and no change in 57. We performed separate analyses on those in the no-change and partial-recovery groups and on those in the no-change and full-recovery groups. The following factors were studied as explanatory variables: age; number of days until presentation; vestibular symptom; initial mean hearing level at 0.25 kHz, 0.5 kHz, 1 kHz, 2 kHz, and 4 kHz; and treatments (steroids, satellite ganglion block). In the first analysis, for patients in the no-change and recovered groups, the factors most strongly related to outcome were the number of days until presentation and age. The second analysis, for the nochange and cured groups, revealed that the number of days until presentation, vestibular symptom, age, and initial mean hearing level were most strongly related to outcome. Our results will increase the ability to predict the outcome for SSNHL.

Does the surgical stress associated with palliative resection for patients with incurable gastric cancer with distant metastasis shorten their survival?

BACKGROUND/AIMS: In cases of incurable stage IV gastric cancer with distant metastases, surgical treatment has usually consisted merely of palliation. The effect of palliative resection in these highly advanced cases remains controversial. Palliative resection may be prohibited by the potential disadvantages of surgical stress. METHODOLOGY: Over the past 23 years, 382 stage IV incurable gastric cancer patients with distant metastases were classified into a resection group (group R) whose subjects underwent a palliative resection of the primary tumor and the non-resection group (group N) who were treated without resection of primary tumor. In order to exclude patients with very poor prognosis due to irresectability even if trying to resect, we restricted the subjects to patients who survived more than 30 and 60 days and some months and estimated the mean survival. Cumulative survival rates were calculated by using the Kaplan-Meier method, and the mean survivals of groups R and N were compared. RESULTS: A significantly longer mean survival was observed in group R than in group N (381 vs. 181 days, P<0.0001). Restricting the subjects to patients who survived more than 30 and 60 days, there is also a significant difference between the mean survival of group R and that of group N. However, restricting the subjects to patients who survived more than 300 days, no significant difference was seen between the two groups. The rate of hospital death was higher in group N than in group R (15.9% vs. 3.4%) CONCLUSIONS: Palliative resection of the primary tumor in stage IV gastric cancer is meaningful in view of hospital stay, long-term survival, and satisfaction with the treatment. We should resect the primary tumor in cases in which it is resectable.

Olfactory event-related potentials in normal subjects and patients with smell disorders.

We developed a device to record olfactory event-related potentials (OERP) from the human scalp. Methyl-cyclopentenolone was used as the odorant element. A total of 50 stimuli were delivered. Each stimulus lasted 0.5 sec and was delivered once every three inspirations. Normal OERPs were obtained with this device. The positive peak latencies were approximately 350 msec (P1) and 700 msec (P2), respectively. OERPs were also recorded in 40 patients with smell disorders. A positive response at about 300-400 msec was recorded in 7 patients (all females, 15-59 years old). The other 33 patients showed no response. The high potential area of this positive peak was located in the centro-occipital region of the scalp. The latency and the high potential area of this peak were similar to P1 recorded in normal subjects. The source of this peak was considered identical to that of P1. This may be a response to the trigeminal nerve during odor administration. P2 was not recorded in the patients with smell disorders. P2 may therefore be a response to the olfactory nerve.

Does body mass index (BMI) influence morbidity and long-term survival in gastric cancer patients after gastrectomy?

BACKGROUND/AIMS: The long-term survival of patients with gastric cancer is governed by various factors, such as the clinical stage of the cancer, the patient's nutritional state, and the treatment and may be governed by the volume of intraperitoneal adipose tissue. The aim of this study is to clarify the relationship between the degree of the patients' body mass index and their long-term survival. METHODOLOGY: Gastric cancer patients who had undergone a gastrectomy with D2-lymphadenectomy and with resection A and B according to the criteria of the Japanese Research Society for Gastric Cancer Rules were subgrouped into those patients with a body mass index < 0.185 (the lower body mass index group) and those patients with a body mass index > 0.210 (the higher body mass index group). The patient's morbidity and long-term survival rate was retrospectively compared between the 2 groups. RESULTS: A significantly longer mean survival rate was observed for the lower body mass index group in stage 2 (1667 vs. 1322 days, P = 0.0240). Also, a significantly longer mean survival rate was observed for the higher BMI group in stage 3a (1431 vs. 943, P = 0.0071). CONCLUSIONS: The body mass index is one of the prognostic factors of stage 2 and stage 3a gastric cancer. However, it does not appear to be useful for determining the prognosis of stage 1a, 1b, 3b, and 4a gastric cancers.

Progressive improvement of prognosis for patients with gastric cancer (dynamic stage grouping) with increasing survival interval from initial staging: how much longer can a given survivor expect to live?

BACKGROUND: The prognosis in gastric cancer is usually defined at the time of presentation. Prognosis, however, is a variable that alters with time. Once a patient has survived for 1 year, the prognosis will change. This study examines this variable in patients who have survived from 1 to 5 years after operation. METHODS: Of 1468 patients with gastric cancer, the next 5-year survival (5YS) of patients who already survived for 1, 2, 3, 4, and 5 years after the initial operation was examined, ie, for patients who have survived 1 year, the 5YS (the 6-year survival from operation) was calculated. Similar survival was determined for patients who had survived more than 2, 3, 4, or 5 years and reported according to stage. RESULTS: In patients who survived 2 years, the next 5YS from that time of patients in stage III a stage was similar to that in stage II, and was similar to the 5YS of patients in stage II at the time of diagnosis. In patients who survived 3, 4, or 5 years, the next 5YS from that time of patients in stage III b and stage III a was similar to that of stage II, and subsequently improved. Similarly, the relationship between stage and survival was disordered subsequently with the passage of time. Similar improvement in survival such that 5YS from the 3rd, 4th, and 5th postoperative year approximated that of the survival of patients at an earlier stage at the time of diagnosis. CONCLUSIONS: Survival is not only stage-dependent at the time of diagnosis but dependent on the length of survival from the initial operation. Progressive improvement in subsequent 5YS appears to approximate survival of lower-stage disease with the passage of time.

Electroencephalographic changes during intravenous olfactory stimulation in humans.

The intravenous olfaction test with thiamin propyl disulfide (TPD) is a simple procedure widely used in Japan. An olfactory stimulus is provided by intravenous injection of TPD (2 ml) over the course of 20 sec. The subject smells n-propyl mercaptan (a decomposition product of TPD discharged from the blood into alveoli) in expired air after treatment. In this preliminary study we recorded electroencephalograms (EEGs) in normal subjects during three stages: 1) eyes-closed rest (prestimulus), 2) olfactory sensation after TPD injection, and 3) disappearance of sensation. In each of these stages, we calculated and compared EEG powers according to the band components of each electrode position. This study was designed a) to evaluate by frequency analysis EEG changes during olfactory sensation after TPD injection, and b) to identify the most significant changes in EEG power according to frequency band and electrode location. During the intravenous olfactory stimulation, alpha 2 and beta 2 waves were activated over the frontal and temporal regions. After disappearance of olfactory sensation, these waves decreased in the same regions. EEG powers returned to prestimulus levels.