Synthesis Of Pr Research Articles

Synthesis and physical properties of (Pr 1−xRE x)Ba 2Cu 4O 8 oxides (RE [dbnd]Y, Yb, Nd, Gd)

PrBa 2Cu 4O 8(Pr124) does not exhibit superconductivity, but its resistivity shows a metallic behavior below 180K. This behavior is in a sharp contrast to the semiconducting one of PrBa 2Cu 3O 7−y(Pr123). A substitution of Pr by RE(Rare earth elements) in the Pr123 is known to induce the superconductivity. For example, the critical RE concentration, XTc, corresponding to the onset of superconductivity for RE Y, Yb, Gd and Nd has been reported to be 0.45, 0.35, 0.5 and 0.65, respectively. In thi study, we could prepare stoichiometric (Pr 1−xRE x)Ba2Cu 4O 8 oxides by using high oxygen pressure technique, and investigated the physical properties. In the case of RE Y, Yb and Gd, the semiconducting region has disappeared and the superconductivity appeared at x=0.3, 0.25 and 0.4, respectively. This result means that Pr-effect in the 124 system is smaller than that in the 123 system.

The high-pressure synthesis and superconductivity of Pr 0.5Ca 0.5Ba 2Cu 3O z

The bulk superconductors of Ca-doped Pr-123 phase, Pr 0.5Ca 0.5Ba 2Cu 3O z were prepared at 1000°C under high pressure of 5GPa. The superconducting properties of the sample depend on the synthesis conditions. The sample synthesized under high oxygen pressure was a nearly single orthorhombic 123 phase, and shows a superconducting transition at 52K with a Meissner signal of 12%. However, the sample prepared under a reduced environment is a high purity tetragonal 123 phase and has a much higher critical temperature (T c=97K) than that in orthorhombic phase. The results demonstrate that suppression of superconductivity by Pr in bulk Pr-123 phase can be compensated by appropriate hole doping with Ca.

Mixed aggregation between lithium diisopropylamide and lithium chloride: NMR, solid-state structure and ab initio calculations

An improved synthesis of (Pr i 2NLi) 2LiCl(Me 2NCH 2CH 2me 2) 2 ( 1) is presented. The structural characterisation of 1 by single crystal X-ray diffraction (C 24H 60ClLi 3N 6, M=489.1, monoclinic P2 1/n, a=9.126(3), b=17.538(6), c=20.470(7) A ̊ , β=98.02(4)°, V=3244.2(19) A ̊ , Z=4) revcaled a three-runged LiN, ClLi, LiN ladder molecular structure. Cryoscopy in benzene indicated that 1 remained substantially undissociated in that solvent. Multinuclear variable temperature NMR in toluene revealed fluxionality; a mechanism of fluxion in arene solution involving rupture of an R 2NLi bond followed by pseudorotation of all external ligands around a chloride fulcrum is proposed. Semi-empirical (MNDO) and ab initio (HF/6–31G ∗) calculational studies of the simplified model (LiNH 2) 2LiCl gave six-membered ring minimum energy geometries. While coordination of four water molecules to the model resulted in only modest changes to the six-membered ring structure at MNDO level, coordination of four dimethyl ehher molecules led to a preference for the three-runged ladder structure as predicted by SCF calculations using a 6–31g ∗ basis.

Interference of PR-bound RNA Polymerase with Open Complex Formation at PRM Is Relieved by a 10-Base Pair Deletion between the Two Promoters

Bacteriophage lambda promoters PR and PRM direct RNA synthesis in divergent orientations from start sites 82 base pairs apart. We had previously determined that the presence on the same DNA fragment of a wild type PR promoter interfered with the utilization of the PRM promoter. The results reported here concern the effects of changing the distance between the start sites by insertion or deletion of 5 or 10 base pairs. Three different techniques (run-off transcription, gel mobility shift, and permanganate probing) were employed to monitor complex formation at PRM. Unexpectedly we find that deletion of 10 base pairs between the start sites abolishes the interference, whereas insertion of 10 base pairs does not. Deletion of 5 base pairs, however, essentially prevents joint complex formation at PR and PRM. These findings suggest several ways in which for the wild type separation of the two promoters the utilization of PRM could be affected by an RNA polymerase at PR. In addition to direct steric interference, these include the obstruction of access to DNA sites necessary for optimal contact with the RNA polymerase.

Water adducts of aryloxides: synthesis and molecular structure of Pr[OC 6H 2(CH 2NMe 2) 3-2,4,6] 3(H 2O) 2

The alcoholysis of Pr[N(SiMe 3) 2] 3 by three equivalents of 2,4,6-(Me 2NCH 2) 3 C 6H 2OH [2,4,6-tris(dimethylaminomethyl)phenol = tamp-OH] in hexane gave Pr(O-tamp) 3(H 2O) 2 which has been characterized by X-ray crystallography. It represents the first example of a praseodymium aryloxide derivative. The complex displays two types of O-tamp ligands, one monodentate, two bidentate, leading to a seven-coordinated praseodymium in a distorted pentagonal bipyramidal configuration. The adduct is stabilized by intermolecular and intramolecular hydrogen bonds between the water molecules and the dangling amino groups.

Distribution of estrogen and progesterone receptors and steroid-regulated gene products in the chick oviduct

The distribution of estrogen and progesterone receptors (ER and PR, respectively) was studied immunohistochemically in the chick oviduct. Estrogen receptor immunoreactivity was found only in the nuclei of glandular epithelial cells. Progesterone receptor was found in the nuclei of glandular and luminal epithelia, stroma, smooth muscle cells and in the mesothelium. The dissimilar distribution of ER and PR suggests that either ER concentration in the luminal epithelium and smooth muscle is very low (below the sensitivity of ER immunostaining) or that estrogens control their PR synthesis indirectly via ER in glandular cells. A known estrogen-inducible protein, ovalbumin, was localized in the same glandular epithelial cells as ER. A progestin-inducible protein, avidin, was found in part of the luminal and glandular epithelium cells but not in other PR-positive cell types. This indicates the importance of cellular differentiation in the regulation of avidin synthesis. Estrogen and progesterone administration had effects also on ER and PR immunoreactivity. Estrogen and progesterone administrations for 24 h decreased markedly the immunoreactivity of their receptors. The decrease in receptor immunoreactivity is most likely due to a transient loss of immunoreactive receptor protein, since the antibodies (H222, PR6) react both with transformed (4 S) and non-transformed (8 S) receptor forms. At the subcellular level, PR was localized in the chromatin by immunoelectron microscopy. Progestin administration seemed to decrease PR immunoreactivity especially in the heterochromatin area, suggesting that conformational chromatin rearrangements occur during down-regulation of PR.

Relationship between progesterone receptor and productive fibrosis as an index of tumor differentiation in breast cancer.

We studied the relationship between steroid receptors (SR) and various stromal parameters in 100 breast cancers. Each specimen was submitted to SR determination by the dextran-coated charcoal assay and to histologic examination. No relationship was found between the presence of SR and necrosis or fibroblastic cell content. There was an inverse correlation between SR positivity and the extent of lymphocyte infiltration (p less than 0.05). ER + PR + status was strongly correlated with marked productive fibrosis (PF) (p less than 0.005). When SR were separately assayed, only the presence of PR was correlated with PF (p less than 0.005); similar results were obtained for PR levels (p less than 0.01). PF was also associated with a higher nuclear grade (p less than 0.001). In conclusion, in this study a strong correlation between PR positivity or concentration and extent of PF was demonstrated in breast cancer. Since PR synthesis is an expression of an intact regulatory pathway, our data suggest that stromal production in breast cancer is related to the degree of differentiation of malignant epithelial cells.

Improved synthesis of (Pri2 N)2POCH2CH2CN.

Improved synthesis of (Pri2 N)2POCH2CH2CN.

Estrogen responsiveness of fetal guinea pig uterine cells in culture

Cells from the uterus of the guinea pig fetus have been grown as a monolayer culture in serum-containing medium. Cells from the first subculture showed high concentrations of progesterone receptor (PR; 9.3–13.8 pmol/mg DNA) even after 9 days in medium containing charcoal-treated serum and estradiol did not induce any further increase. The antiestrogens, tamoxifen and monohydroxytamoxifen, both had an inhibitory effect which could be overcome by estradiol. The progestins, progesterone and R5020, as well as the antiprogestin, RU38486, also decreased the PR concentration. Estrogen receptor (ER) levels did not vary with the compounds tested but were found to be low compared to concentrations found in the fetal guinea pig uterus at 55–65 days of gestation. None of the compounds tested had any effect on the growth of the fetal uterine cells so that the modulation of PR concentrations was dissociated from the regulation of cell growth. It is concluded that estrogens are necessary but not sufficient factors in the control of PR levels in fetal uterine cells. The establishment of a culture system for separate types of fetal uterine cells will permit us to study in vitro the factors involved in the growth effects of estrogens and the control of PR synthesis.

In vivo induction of progesterone receptors in normal post-menopausal endometrium - evidence of lack of inhibitory control of pr synthesis : I.G. Gorodeski, A. Geier, R. Beery, B. Lunenfeld and C.M. Bahary - Kfar-Sava, Israel

In vivo induction of progesterone receptors in normal post-menopausal endometrium - evidence of lack of inhibitory control of pr synthesis : I.G. Gorodeski, A. Geier, R. Beery, B. Lunenfeld and C.M. Bahary - Kfar-Sava, Israel

Phytochrome in Pharbitis nil during and after de‐etiolation

Phytochrome (P) was measured by in vivo spectrophotometry in the cotyledons of Pharbitis nil Choisy cv. Violet. In etiolated plants exposure to red light (R) results in a rapid fall in P content by destruction of the far‐red absorbing form of phytochrome (Pfr). In continuous R or white light the P content falls as a result of destruction to a stable 3% of that originally present. In Norflurazon‐treated white light de‐etiolated plants, Pfr undergoes reversion in darkness to the red absorbing form of phytochrome (Pr) with a half life of 4 h at 19°C, while total P remains constant. Synthesis of Pr after de‐etiolation occurs at a slow rate and is enhanced by terminating the de‐etiolation light treatment with far‐red light. The results are discussed in relation to the P control of flowering.

Patterns of estrogen and progesterone receptors in monkey endometrium during the normal menstrual cycle

Total concentrations of estradiol-17β (E 2) and progesterone (P) receptors (R) were measured in the endometrium of rhesus monkeys ( Macaca mulatta ) during the normal menstrual cycle. The endometrium was collected at abdominal fundal hysterotomy on days 8, 12, 15, 18 and 24 of the menstrual cycle. Visual inspection of the ovaries and measurement of E 2, P, follicle stimulating hormone (FSH) and luteinizing hormone (LH) provided assuredness of normal ovarian function. Exchange procedures were used in order to measure the total concentrations of E 2R and PR in nuclear and cytosol fractions. The pattern of estrogen receptor showed a slight increase in the cytosol and nuclear concentrations at the preovulatory interval. Later, the total E 2R concentration was decreased when P increased during the luteal phase. Cytosol PR synthesis was parallel to the serum E 2 increase during the late follicular phase. Secretion of P by the corpus luteum was accompanied by a rapid nuclear translocation and concomitant decrease in cytoplasmic PR. Thereafter the total PR concentration declined during the second half of the luteal phase. These findings in monkey endometrium are similar to those reported for human endometrium during the normal menstrual cycle and further establish the utility of these surrogate primates in investigations indicative of human endometrial function.

Synthesis and characterization of Pr(III)complexes with 15-Crown-5 and 18-Crown-6 Ethers*

Synthesis and characterization of Pr(III)complexes with 15-Crown-5 and 18-Crown-6 Ethers*

On the physiological significance of dark reversion of phytochrome in the mustard seedling.

Abstract—We present physiological evidence using the threshold control of lipoxygenase synthesis† by Pfr in the mustard seedling (LOG response) that there is no dark reversion of phytochromewhich would be relevant for this response. Such Ptr which can be detected with the lipoxygenase response disappears exclusively through degradation with a half‐life of 45 min at 25°C. De novo synthesis of P*r in the hypocotylar hook takes place at a constant rate (zero order rate constant) irrespective of the level of Pr or P*tot, i.e. there is no detectable feedback control of Pr synthesis during the period of experimentation. The data of the present paper are consistent with a quantitative phytochrome model (Scheme 1) which has been advanced and treated quantitatively in the companion paper (Oelze‐Karow and Mohr, 1976).

ChemInform Abstract: SCHIFF BASE DERIVATIVES OF LANTHANONS, A NOVEL SYNTHESIS OF LA(III), PR(III) AND ND(III) DERIVATIVES OF FLUORINE CONTAINING SCHIFF BASES

Chemischer InformationsdienstVolume 6, Issue 21 Organoelement Compounds ChemInform Abstract: SCHIFF BASE DERIVATIVES OF LANTHANONS, A NOVEL SYNTHESIS OF LA(III), PR(III) AND ND(III) DERIVATIVES OF FLUORINE CONTAINING SCHIFF BASES S. K. AGARWAL, S. K. AGARWALSearch for more papers by this authorJ. P. TANDON, J. P. TANDONSearch for more papers by this author S. K. AGARWAL, S. K. AGARWALSearch for more papers by this authorJ. P. TANDON, J. P. TANDONSearch for more papers by this author First published: May 27, 1975 https://doi.org/10.1002/chin.197521353Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume6, Issue21May 27, 1975 RelatedInformation

Schiff base derivatives of lanthanons—a novel synthesis of La(III), Pr(III) and Nd(III) derivatives of fluorine containing schiff bases

1:1 and 1:2 stoichiometric reactions of the isopropoxides of some of the lanthanons La(III), Pr(III) and Nd(III) with monofunctional bidentate Schiff bases containing fluorine such as 1, 1, 1-trifluoro-2,4-pentanedione- n-propylimine (TFAH- n-C 3H 7) and 1,1,1-trifluoro-2,4-pentanedione- n-butylimine (TFAH- n-C 4H 9) have led to a novel synthesis of derivatives of the type, Ln(0- i-C 3H 7) 3− n (TFA-R) n (where n = 1 or 2; Ln = lanthanides; R = n-C 3H 7 or n-C 4H 9 and TFA- R is the anion of the corresponding Schiff base, TFAH- R). The resulting compounds have been obtained in high yields and characterized by elemental analysis and mol. wt determinations. Their i.r. spectra have been recorded in the range of 4000-400 cm −1 and the effect of CF 3 group on the ▪ and ▪ stretching frequencies is discussed.

Schiff Base Derivatives of Lanthanides - Synthesis of La(III), Pr(III) and Nd(III) Complexes of Alkylimines and Arylimines Derived from 2-Hydroxy-1-Naphthaldehyde

Abstract Methods of synthesis of lanthanide derivatives of the type, In(0-i-C3H7)2(2-OC10H6CH:NR) and In(0-i-C3H7) (2-OC10H6CH:NR)2 in high yields and in high purity have been described. These have been synthesized by the 1:1 and 1:2 molar reactions of the isopropoxides of lanthanides with monofunctional bidentate Schiff bases, 2-HOC10H6CH:N-n-C4H9 and 2-HOC10H6CH:NC6H5. Their exchange reactions with an excess of t-butyl alcohol have yielded the corresponding t-butyl derivatives. The resulting compounds have been characterized by elemental analyses and molecular weight determinations. Their infrared spectra have also been recorded and tentative assignments were made.

Etude du phytochrome detectable, in vivo dans les graines de Cucurbita pepo L. au cours des differentes phases de la germination

In dry gourd seeds all the phytochrome is in the Pfr form. The increase of phytochrome content from the beginning of hydration involves two phases, A and B, in the embryonic axis as well as in the cotyledons. Cycloheximide does not prevent the appearance of Pr during phase A. We assume that Pr is gradually released from an inactive complex. On the other hand phase B is inhibited by cycloheximide; this could mean that a de novo synthesis of Pr occurs.