Reaction Rates of OH Radicals with CH3OCF2CHFCF3 and CHF2CF2OCH2CF2CHF2: Measurements and Estimation Using Neural Network Method.

The reaction rates of OH radicals with CH3OCF2CHFCF3 (k1) and CHF2CF2OCH2CF2CHF2 (k2) were measured over a temperature range of 250-430 K. Kinetic measurements were performed using the flash and laser photolysis methods combined with a laser-induced fluorescence technique. The Arrhenius rate parameters were determined as k1 = (2.52 ± 0.25) × 10-12·exp[-(1390 ± 30)/T], k2 = (1.83 ± 0.20) × 10-12·exp[-(1420 ± 35)/T] cm3 molecule-1 s-1. The infrared absorption spectra of the two hydrofluoroethers were measured at approximately 298 K in 760 Torr of N2. The atmospheric lifetimes of CH3OCF2CHFCF3 and CHF2CF2OCH2CF2CHF2 have been estimated as 2.5 and 3.8 years, respectively, and their global warming potentials were determined as 245 and 405, respectively. Additionally, a method, using a three-layered feed-forward neural network, for estimating the rates of the reaction of the OH radicals with alkanes, ethers, and alcohols was investigated. The ratios of the calculated reaction rates to the observed ones agreed within a factor of 2. The ability of the neural network method to predict reaction rates was examined by using a leave-one-out test.

Rate Constants for the Reactions of OH Radicals with the ( E)/( Z) Isomers of CFCl=CFCl and ( E)-CHF=CHF.

The rate constants for the OH radical reactions with halogenated ethenes were investigated experimentally and computationally. The rate constants for the reactions of OH radicals with ( E)-CFCl=CFCl ( k1), ( Z)-CFCl=CFCl ( k2), and ( E)-CHF=CHF ( k3) were measured using flash and laser photolysis methods. The temporal profile of the OH radical was monitored by a laser-induced fluorescence technique. Kinetic measurements were carried out over the temperature range of 250-430 K. Arrhenius rate constants were determined to be k1 = (1.67 ± 0.06) × 10-12·exp[(140 ± 10) K/ T], k2 = (1.75 ± 0.04) × 10-12·exp[(140 ± 10) K/ T], and k3 = (3.99 ± 0.15) × 10-12·exp[(260 ± 10) K/ T] cm3 molecule-1 s-1. The quoted uncertainties are 95% confidence levels and do not include systematic errors. Infrared absorption spectra were measured at room temperature. The atmospheric lifetimes and the global warming potentials of ( E)-CFCl=CFCl, ( Z)-CFCl=CFCl, and ( E)-CHF=CHF were estimated to be 4.3, 4.2, and 1.2 days and 0.035, 0.036, and 0.0056, respectively. The ozone depletion potentials of ( E)-CFCl=CFCl and ( Z)-CFCl=CFCl were determined to be 0.00011 and 0.00010, respectively. The photochemical ozone creation potentials of the halogenated ethenes were less than 1/4 that of ethene. In addition, the ( E)/( Z) differences in the energy and IR spectra of the CFCl=CFCl and CHF=CHF molecules were computationally examined. The reactivities of these halogenated ethenes toward OH radicals were investigated through the combination of DFT and ab initio computations. The rate constants calculated for the OH radical reactions of these halogenated ethenes showed reasonable agreement with the experimentally determined values. Our computational results for the CFCl=CFCl and CHF=CHF ( E)/( Z) isomeric pairs indicated that the rate constants toward OH radicals are larger for the higher-energy geometrical isomers than for the lower-energy counterparts.

Rate Constants for the Reactions of OH Radicals with Fluorinated Ethenes: Kinetic Measurements and Correlation between Structure and Reactivity.

The rate constants for the reaction of OH radicals with four fluorinated ethenes (CF2═CHF, ( E)-CHF═CHF, CF2═CH2, and CHF═CH2) have been measured over the temperature range of 250-430 K. Kinetic measurements have been carried out using flash photolysis and laser photolysis methods combined with a laser-induced fluorescence technique. The Arrhenius expressions for the rate constant have been determined as k(CF2═CHF) = (3.12 ± 0.11) × 10-12 exp[(270 ± 10)/ T], k(( E)-CHF═CHF) = (3.75 ± 0.08) × 10-12 exp[(230 ± 10)/ T], k(CF2═CH2) = (1.15 ± 0.07) × 10-12 exp[(230 ± 20)/ T], and k(CHF═CH2) = (1.16 ± 0.09) × 10-12 exp[(390 ± 20)/ T] cm3 molecule-1 s-1. Infrared absorption spectra of the fluorinated ethenes have been measured at room temperature. The atmospheric lifetimes and global warming potentials of the fluorinated ethenes have been estimated. The correlation between the reactivity and the structure of the halogenated ethenes has been investigated by considering the structure containing the atoms attached to the carbons on both sides of the double bond. The calculated rate constants of 14 halogenated ethenes showed agreement with the measured rate constants within a factor of 2, except for that of one compound.

Rate Constants for the Reactions of OH Radical with the ( E)/( Z) Isomers of CF3CF═CHCl and CHF2CF═CHCl.

The rate constants for the reactions of OH radical with ( E)- and ( Z)-isomers of CF3CF═CHCl and CHF2CF═CHCl have been measured over the temperature range of 250-430 K. Kinetic measurements have been performed using flash and laser photolysis methods combined with laser-induced fluorescence. Arrhenius rate constants have been determined as k(( E)-CF3CF═CHCl) = (1.09 ± 0.03) × 10-12 · exp[(50 ± 10)K/ T], k(( Z)-CF3CF═CHCl) = (8.02 ± 0.19) × 10-13 · exp[-(100 ± 10)K/ T], k(( E)-CHF2CF═CHCl) = (1.50 ± 0.03) × 10-12 · exp[(160 ± 10)K/ T], and k(( Z)-CHF2CF═CHCl) = (1.36 ± 0.03) × 10-12 · exp[(360 ± 10)K/ T] cm3 molecule-1 s-1. Infrared absorption spectra have also been measured at room temperature. The atmospheric lifetimes of ( E)-CF3CF═CHCl, ( Z)-CF3CF═CHCl, ( E)-CHF2CF═CHCl, and ( Z)-CHF2CF═CHCl have been estimated as 8.9, 20, 4.6, and 2.6 days, respectively, and their global warming potentials and ozone depletion potentials were determined as 0.23, 0.88, 0.060, and 0.016 and 0.00010, 0.00023, 0.000057, and 0.000030, respectively. Additionally, the rate constants for OH radical addition and IR spectra of these compounds were determined computationally. Consistent with experiment, our calculations indicate that the reactivity toward OH radical addition is reduced as ( Z)-CHF2CF═CHCl > ( E)-CHF2CF═CHCl > ( E)-CF3CF═CHCl > ( Z)-CF3CF═CHCl, where the ( E)/( Z) reactivity is reversed for CF3CF═CHCl and CHF2CF═CHCl. The calculations reproduced the observed temperature dependencies of the rate constants for the OH radical reactions, which is slightly positive for ( Z)-CF3CF═CHCl but negative for the other compounds.

Correction to: Rate constants for the reactions of OH radicals with CF3CX=CY2 (X=H, F, CF3, Y=H, F, Cl).

We make a correction to the original paper because there was a mistake in our preceding paper (Tokuhashi et al. 2018) that was cited in the original paper. In our preceding paper, we reported the measured rate constant of OH radicals with (E)-CHF=CHF.

A study on flammability limits of fuel mixtures.

Flammability limit measurements were made for various binary and ternary mixtures prepared from nine different compounds. The compounds treated are methane, propane, ethylene, propylene, methyl ether, methyl formate, 1,1-difluoroethane, ammonia, and carbon monoxide. The observed values of lower flammability limits of mixtures were found to be in good agreement to the calculated values by Le Chatelier's formula. As for the upper limits, however, some are close to the calculated values but some are not. It has been found that the deviations of the observed values of upper flammability limits from the calculated ones are mostly to lower concentrations. Modification of Le Chatelier's formula was made to better fit to the observed values of upper flammability limits. This procedure reduced the average difference between the observed and calculated values of upper flammability limits to one-third of the initial value.

Burning velocity measurements of nitrogen-containing compounds.

Burning velocity measurements of nitrogen-containing compounds, i.e., ammonia (NH3), methylamine (CH3NH2), ethylamine (C2H5NH2), and propylamine (C3H7NH2), were carried out to assess the flammability of potential natural refrigerants. The spherical-vessel (SV) method was used to measure the burning velocity over a wide range of sample and air concentrations. In addition, flame propagation was directly observed by the schlieren photography method, which showed that the spherical flame model was applicable to flames with a burning velocity higher than approximately 5 cm s(-1). For CH3NH2, the nozzle burner method was also used to confirm the validity of the results obtained by closed vessel methods. We obtained maximum burning velocities (Su0,max) of 7.2, 24.7, 26.9, and 28.3 cm s(-1) for NH3, CH3NH2, C2H5NH2, and C3H7NH2, respectively. It was noted that the burning velocities of NH3 and CH3NH2 were as high as those of the typical hydrofluorocarbon refrigerants difluoromethane (HFC-32, Su0,max=6.7 cm s(-1)) and 1,1-difluoroethane (HFC-152a, Su0,max=23.6 cm s(-1)), respectively. The burning velocities were compared with those of the parent alkanes, and it was found that introducing an NH2 group into hydrocarbon molecules decreases their burning velocity.

Rate constants for the reactions of OH radicals with CF3CX=CY2 (X = H, F, CF3, Y = H, F, Cl).

The rate constants of OH radicals with CF3CF=CCl2, CF3CH=CF2, CF3CF=CH2, CF3CH=CH2, and (CF3)2C=CH2 have been measured over the temperature range 250-430 K. Kinetic measurements have been carried out using flash photolysis and laser photolysis methods combined respectively with laser-induced fluorescence technique. The Arrhenius rate parameters have been determined as k(CF3CF=CCl2) = (6.50 ± 0.22) × 10-13∙exp[(200 ± 10)/T], k(CF3CH=CF2) = (4.85 ± 0.14) × 10-13∙exp[(120 ± 10)/T], k(CF3CF=CH2) = (1.54 ± 0.03) × 10-12∙exp[- (100 ± 10)/T], k(CF3CH=CH2) = (1.06 ± 0.02) × 10-12∙exp[(80 ± 10)/T], and k((CF3)2C=CH2) = (8.75 ± 0.23) × 10-13∙exp[- (20 ± 10)/T] cm3 molecule-1 s-1. Infrared absorption spectra of the halogenated alkenes have been measured at room temperature. The atmospheric lifetime, global warming potential, ozone depleting potential, and photochemical ozone creation potential have been estimated. The change in the reactivity of halogenated alkenes by the substitution has been examined by considering the structure containing the atoms or atomic groups attached to the carbons on both sides of the double bond.

Flammability limits of isobutane and its mixtures with various gases.

Flammability limits of isobutane and five kinds of binary mixtures of isobutane were measured by the ASHRAE method. Propane, nitrogen, carbon dioxide, chloroform, and HFC-125 (1,1,1,2,2-pentafluoroethane) were used as the counter part gases in the mixtures. The observed data were analyzed using the equations based on Le Chatelier's formula. The flammability limits of mixtures with propane were well explained by the original Le Chatelier's formula. The flammability limits of mixtures with nitrogen and the ones with carbon dioxide were adequately analyzed by the extended Le Chatelier's formula. It was found that the extended Le Chatelier's formula is also applicable to the flammability limits of mixtures with chloroform and HFC-125.

Knockdown of Skp2 by siRNA inhibits melanoma cell growth in vitro and in vivo.

BACKGROUND: Low levels of p27Kip1 expression are associated with poor prognosis in various malignancies including malignant melanoma. Recently, it has been reported that S phase kinase-interacting protein 2 (Skp2), the specific ubiquitin ligase subunit that targets p27Kip1 for degradation, was overexpressed and was inversely related to p27Kip1 levels in malignant melanoma with poor prognosis. OBJECTIVE: We investigated whether small interfering RNA (siRNA)-mediated gene silencing of Skp2 can be employed in order to inhibit p27Kip1 down-regulation and suppress melanoma cell growth as a consequence in vitro and in vivo. METHODS: We constructed a plasmid vector, which synthesizes siRNAs to determine the effects of decreasing the high constitutive levels of Skp2 protein in melanoma cells. Western blot and real-time RT-PCR were performed to examine the decreases of Skp2 protein and mRNA in vitro. Furthermore, melanoma cells were injected into the back of nude mice subcutaneously to examine the suppression of tumorigenicity targeting Skp2 gene silencing in vivo. RESULTS: Skp2 protein was decreased and the p27Kip1 protein was accumulated in Skp2 siRNA transfected melanoma cells. Skp2 siRNA inhibited the cell growth of melanoma cells in vitro. Moreover, Skp2 siRNA also suppressed tumor proliferation in vivo. CONCLUSION: Our results suggest that siRNA-mediated gene silencing of Skp2 can be a potent tool of cancer gene therapy for suppression of p27Kip1 degradation in malignant melanoma.

Extended Le Chatelier's formula for carbon dioxide dilution effect on flammability limits.

Carbon dioxide dilution effect on the flammability limits was measured for various flammable gases. The obtained values were analyzed using the extended Le Chatelier's formula developed in a previous study. As a result, it has been found that the flammability limits of methane, propane, propylene, methyl formate, and 1,1-difluoroethane are adequately explained by the extended Le Chatelier's formula using a common set of parameter values. Ethylene, dimethyl ether, and ammonia behave differently from these compounds. The present result is very consistent with what was obtained in the case of nitrogen dilution.

Strongyloides ratti infection in the large intestine of wild rats, Rattus norvegicus.

The large intestine of a rat has been neglected almost completely as a site of Strongyloides sp. infection. We reported that adult Strongyloides ratti remained in the large intestine for more than 80 days, producing more number of infective larvae than small intestine adults, and therefore hypothesized that parasitism in this site could be a survival strategy. In wild rats, however, no study has focused on large intestine infections of Strongyloides. The present study revealed that 32.4% of 68 wild rats, Rattus norvegicus, had the infection of S. ratti in the large intestine, with an average of 4.7 worms. These worms harbored normal eggs in the uterus. In a laboratory experiment with S. ratti and Wister rats, daily output of infective larvae by 4.7 females in the large intestine was estimated to be 4,638.4, suggesting that a few parasites could play a role in the parasite transmission. Five species of nematode found in the wild rats showed seasonality in infection intensity, with highest intensities in March-May. The number of S. ratti in the large intestine was also highest in these months.

Topical vitamin D3 is effective in treating senile warts possibly by inducing apoptosis.

Vitamin D3 ointments containing active forms of vitamin D3 are widely used to treat inflammatory keratotic dermatoses such as psoriasis. Senile wart or seborrheic keratosis is a benign tumor which occurs mainly in the elderly. It has traditionally been treated with surgical procedures, freezing with liquid nitrogen, or laser therapy. We treated senile warts with topical vitamin D3 ointments (tacalcitol, calcipotriol or maxacalcitol). Out of 116 cases treated for 3 to 12 months, 35 (30.2%) showed complete disappearance or more than an 80% decrease in the volume of the tumor, 54 cases (46.6%) showed a decrease in the volume between 40 and 80%, and no remarkable changes or decreases of less than 40% were seen in 27 cases (23.3%). The tumors faded without any inflammatory changes such as erythema or swelling. An organ culture experiment using senile wart as a material with several concentrations of tacalcitol revealed that tacalcitol induced apoptosis in the tissue. On the other hand, only sporadic apoptotic cells were seen in the controls (p<0.001). Vitamin D3 may affect senile warts by inducing apoptosis. Clearance of senile warts, especially on exposed areas without pain, may improve the quality of life (QOL) of the elderly.

Occurrence and comparison of the expressed keratins in cultured human fibroblasts, endothelial cells and their sarcomas.

We investigated keratin (K) expression in cultured fibroblasts, endothelial cells and their sarcomas by using two-dimensional gel electrophoresis and electron microscopy techniques. Although the fibroblast and endothelial cell lines were derived from mesenchyme, we confirmed Ks in both cell lines. The K in two cultured cell lines consisted of K14 and K16, together with vimentin. In addition to the above Ks, K5 and K8/K17 were comprised in each cell line, respectively. On the other hand, the cultured fibrosarcomas contained K8 and K18 in addition to the Ks present in the cultured fibroblasts, except K17. Moreover, cultured angiosarcomas showed the same Ks expression as those of the cultured fibrosarcomas, except vimentin. However, electron microscopy showed that the extremely thin fiber-like substances existed or at least did not form filamentous structures in four cultured cell types.

Iatrogenic hypercalcemia due to vitamin D3 ointment (1,24(OH)2D3) combined with thiazide diuretics in a case of psoriasis.

Tacalcitol is a synthetic vitamin D3 analogue developed for topical treatment of inflammatory skin diseases such as psoriasis. Hypercalcemia has not been previously reported during treatment with topical tacalcitol. We experienced a male patient with psoriasis and hypertension whose conditions were treated with tacalcitol ointment and thiazide, respectively, resulting in hypercalciuria and hypercalcemia. After initiation of topical vitamin D3 ointment (20 micro g/g of tacalcitol) 10 g/day for the skin lesions, both the serum level of calcium and urinary excretion of calcium increased gradually. On day 28 of the treatment, his serum calcium levels had reached 3.55 mmol/l, and his urinary calcium excretion had also increased from 0.008 g/day to 0.475 g/day. The tacalcitol treatment was terminated, seven days later, the serum calcium level had returned to the reference range without any specific treatment. The present case is the first report of hypercalcemia induced by vitamin D3 ointment and thiazide simultaneously.

Immunohistochemical differentiation of extra-ocular sebaceous carcinoma from other skin cancers.

We performed an immunohistochemical study using routinely processed formalin-fixed and paraffin-embedded tissue specimens from 26 cases of extra-ocular sebaceous carcinoma (EOSC) and eight easily available antibodies. They were polyclonal anti-carcinoembryonic antigen (CEA) antibody, monoclonal anti-CEA antibody, anti-breast carcinoma associated antigen-225 antibody (CU18), anti-CA15.3 antibody (CA15.3), anti-CD15 antibody (CD15), anti-breast carcinoma associated antigen antibody (B6.2), anti-gross cystic disease fluid antigen-15 antibody (GCDFP15) and anti-Thomsen-Friedenreich antigen antibody (TFA). Squamous cell carcinoma, porocarcinoma, syringomatous carcinoma, malignant clear cell hidradenoma, apocrine adenocarcinoma, and extramammary Paget's disease with underlying adenocarcinoma were used as controls. EOSC was positive for CU18 and CA15.3 in most cases, and for CD15 in a few cases. Squamous cell carcinoma of the skin was positive for CA15.3 in only one case. Porocarcinoma, syringomatous carcinoma and malignant clear cell hidradenoma were positive for CEA, CU18, CA15.3, and B6.2 in most cases. Apocrine adenocarcinoma and extramammary Paget's disease with underlying adenocarcinoma were positive for CEA, CU18, CD15, GCDFP15, CA15.3, and B6.2 in most cases. TFA was positive not only in EOSC but also in other skin cancers. Immunohistochemical examinations using these seven of eight antibodies except for TFA and routinely processed formalin-fixed and paraffin-embedded tissue specimens are beneficial in differentiating EOSC from other skin cancers.

Hydroa vacciniforme-like eruptions in a patient with chronic active EB virus infection.

We report a case of chronic active Epstein-Barr (EB) virus infection (CAEBV) associated with skin eruptions mimicking hydroa vacciniforme (HV) in a 4-year-old boy. The patient had repeated episodes of vesiculo-necrotic eruptions on the face, scalp, and bilateral forearms one year before the first visit to our department. General symptoms including fever, hepatosplenomegaly, abnormal liver function, and cervical lymph node swelling were noted three months before the first visit. At the first visit, small, bean-sized, erythemic papules with central necrosis were observed on the face and anterior chest wall. Thumb-sized ulcers with crust were present on the bilateral forearms. Histopathological examination of an erythematous lesion in the submandibular area revealed parakeratosis with a thick crust, mild spongiosis in the epidermis, and a dense infiltration of lymphoid cells into the dermis and perivascular space. Laboratory examination showed EBNA x 40, EBV VCA IgG x 1,280, and EBV DNA (PCR) 8 x 10(4). EBV-encoded small nuclear RNA (EBER) positive cells were detected in the dermis by an in situ hybridization (ISH) method. Large granular lymphocytes (65%) with the NK cell phenotype were found in the peripheral blood. A real time PCR method showed 171,741 copies/ micro g DNA in CD 16 positive cells. Although latent EBV infection-associated eruptions have been documented, detailed skin manifestations in CAEBV are less well known.