Evolved galaxies in high-density environments across 2.0≤z<4.22.0\leq z<4.2 using the ZFOURGE survey

To explore the role environment plays in influencing galaxy evolution at high redshifts, we study $2.0\leq z<4.2$ environments using the FourStar Galaxy Evolution (ZFOURGE) survey. Using galaxies from the COSMOS legacy field with ${\rm log(M_{*}/M_{\odot})}\geq9.5$, we use a seventh nearest neighbour density estimator to quantify galaxy environment, dividing this into bins of low, intermediate and high density. We discover new high density environment candidates across $2.0\leq z<2.4$ and $3.1\leq z<4.2$. We analyse the quiescent fraction, stellar mass and specific star formation rate (sSFR) of our galaxies to understand how these vary with redshift and environment. Our results reveal that, across $2.0\leq z<2.4$, the high density environments are the most significant regions, which consist of elevated quiescent fractions, ${\rm log(M_{*}/M_{\odot})}\geq10.2$ massive galaxies and suppressed star formation activity. At $3.1\leq z<4.2$, we find that high density regions consist of elevated stellar masses but require more complete samples of quiescent and sSFR data to study the effects of environment in more detail at these higher redshifts. Overall, our results suggest that well-evolved, passive galaxies are already in place in high density environments at $z\sim2.4$, and that the Butcher-Oemler effect and SFR-density relation may not reverse towards higher redshifts as previously thought.Comment: 11 pages, 5 figures, final version published in PAS

Discrimination of Chiral Guests by Chiral Channels: Variable Temperature Studies by SXRD and Solid State 13C NMR of the Deoxycholic Acid Complexes of Camphorquinone and Endo-3-Bromocamphor

3a,12a-Dihydroxy-5b-cholan-24-oic acid (deoxycholic acid DCA) is able to discriminate between the R- and S-enantiomers of camphorquinone and endo-(1)-3-bromocamphor and select only the S-enantiomers from a racemic mixture. DCA forms novel well ordered 1:1 adducts with (1S)-(1)-camphorquinone and (1S)-endo-(-)-3-bromocamphor, both of which have been characterized by single crystal X-ray diffraction SXRD). When DCA is cocrystallized with (RS)-camphorquinone and (RS)-endo-3-bromocamphor,1:1 adducts of the S-enantiomers are produced together with crystals of the free racemic guest. In contrast, in the absence of (1S)-(1)-camphorquinone, DCA forms a 2:1 adduct with (1R)-(2)-camphorquinone. In this 2:1 adduct the guest is disordered at ambient temperature and undergoes a phase change in the region 160–130 K similar to that observed for the ferrocene adduct, but with only partial ordering of the guest. The SXRD structure of the low temperature form and the variable temperature 13C CP/MAS NMR are reported. Cocrystallizing DCA with (1R)-endo-(1)-3-bromocamphor gives the free guest and a glassy solid

(3R,4R,5R)-5-(Acetamido­meth­yl)-N-benzyl-3,4-dihy­droxy­tetra­hydro­furan-3-carboxamide

X-ray crystallographic analysis with Cu Kα radiation established the relative configurations of the stereogenic centers in the title compound, C15H20N2O5, and clarified mechanistic ambiguities in the synthesis. The conformation of the five-membered ring approximates twisted, about a C—O bond. The absolute configuration of this carbon-branched dipeptide isostere was known based on the use of d-ribose as the starting material. Refinement of the Flack parameter gave an ambiguous result but the refined Hooft parameter is in agreement with the assumed (d-ribose) absolute structure. The crystal structure consists of N—H⋯O and O—H⋯O hydrogen-bonded bi-layers, with the terminal methyl and phenyl groups forming a hydro­phobic inter-layer inter­face. Some weak C—H⋯O inter­actions are also present

Synthesis, characterization and biological studies of S- benzyl-b-N-(benzoyl)dithiocarbazate and its metal complexes

S-Benzyl-b-N-(benzoyl) dithiocarbazate (SBNBODTC) a new disubstituted dithio-carbazate oxygen–sulfur (OS) donor ligand derived from reaction of S-benzyl dithiocarbazate with benzoyl chloride, formed bischelated complexes of general formula [M(OS)2] where M is Cu2+, Ni2+, Cd2+, Co2+ or Pb2+ and OS is a uninegative bidentate ligand. The ligand and its metal complexes have been characterized by a variety of physico-chemical techniques. S-benzyl-b-N-(benzoyl) dithiocarbazate crystallized with Z0 = 2 in its thione form in cis–cis conformation, with the N–N bond adopting a cis geometry with respect to C@S, while the S-benzyl group adopts a cis geometry with respect to the thione sulfur atom across the C–S bond.SBNBODTC, Cu(OS)2, Ni(OS)2 and Pb(OS)2 display marked cytotoxicity against HL-60 (human myeloid leukemia)while Cd(OS)2 and Co(OS)2 are moderately cytotoxic. The compounds showed moderate but selective activity towards targeted pathogens

The thermal denaturation of DNA studied with neutron scattering

The melting transition of deoxyribonucleic acid (DNA), whereby the strands of the double helix structure completely separate at a certain temperature, has been characterized using neutron scattering. A Bragg peak from B-form fibre DNA has been measured as a function of temperature, and its widths and integrated intensities have been interpreted using the Peyrard-Bishop-Dauxois (PBD) model with only one free parameter. The experiment is unique, as it gives spatial correlation along the molecule through the melting transition where other techniques cannot.Comment: accepted for publication in Physical Review Letter

Synthesis, characterization and bioactivity of mixed-ligand Cu(II) complexes containing Schiff bases derived from S-benzyldithiocarbazate and saccharinate ligand and the X-ray crystal structure of the copper-saccharinate complex containing S-benzyl-β-N-(acetylpyrid-2-yl)methylenedithiocarbazate

Mixed-ligand complexes of general formula, [Cu(NNS)(sac)] (NNS′ = S-benzyl-β-N-(2-acetylpyrid-2-yl)methylenedithiocarbazate, NNS″ = S-benzyl-β-N-(2-benzoylpyrid-2-yl)methylenedithiocarbazate and NNS = S-benzyl-β-N-(6-methylpyrid-2-yl)methylenedithio-carbazate, sac = the saccharinate anion) have been synthesized by reacting [Cu(sac)2(H2O)4] · 2H2O with the appropriate ligands in ethanol and characterized by various physico-chemical techniques. Magnetic and spectral evidence indicate that the complexes are four-coordinate in which the Schiff bases coordinate as NNS ligands and the sac- anion coordinates as a unidentate N-donor ligand. An X-ray crystallographic structural analysis of [Cu(NNS′)(sac)] shows that the complex has a distorted square-planar geometry with the Schiff base coordinated to the copper (II) ion as a uninegatively charged tridentate chelating agent via the pyridine nitrogen atom, the azomethine nitrogen atom and the thiolate sulphur atom while the fourth coordination position is occupied by the N-bonded saccharinate anion. The complexes have been evaluated for their biological activities against selected pathogens and cancer cell lines. They display weak activity against the pathogenic bacteria and fungi. The complexes were highly active against the leukemic cell line (HL-60) but only [Cu(NNS′)(sac)] was found to exhibit strong cytotoxicity against the ovarian cancer cell line (Caov-3). All complexes were inactive against the breast cancer cell line (MCF-7)

Synthesis and characterization of cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes of benzyl N-[1-(thiophen-2-yl)ethylidene] hydrazine carbodithioate and benzyl N-[1-(thiophen-3-yl)ethylidene] hydrazine carbodithioate and the X-ray crystal structure of bis{benzyl N-[1-(thiophen-2-yl)ethylidene] hydrazine carbodithioate}nickel(II)

Two bidentate Schiff bases have been synthesized by reaction of S-benzyldithiocarbazate with 2-acetylthiophene and 3-acetylthiophene to give benzyl N-[1-(thiophen-2-yl)ethylidene] hydrazine carbodithioate (SB2ATP) and benzyl N-[1-(thiophen-3-yl)ethylidene]hydrazine carbodithioate (SB3ATP). The SB2ATP and SB3ATP were then reacted with five metal ions, cobalt(II), nickel(II), copper(II),zinc(II) and cadmium (II) to form 10 metal complexes, all of general formula ML2. The compounds synthesized were assayed for their bioactivities against selected pathogens and cancer cells. X-ray crystal structure analysis of Ni(SB2ATP)2 showed it to be a distorted square planar complex. All the compounds are non-electrolytes in DMSO. Cu(SB2ATP)2 showed strong activity towards Candida lypolytica.SB2ATP, SB3ATP, Co(SB2ATP)2, Cd(SB2ATP)2 and Cu(SB3ATP)2 showed weak activity against several microbes and fungi while the others showed no activity toward these targets. SB2ATP and Cd(SB3ATP)2 showed significant bioactivity towards human myeloid leukemia (HL-60) while Co(SB3ATP)2 showed slight cytotoxic activity towards this cell line. SB2ATP, SB3ATP, Co(SB2ATP)2,Cu(SB2ATP)2, Cu(SB3ATP)2, Zn(SB2ATP)2 and Cd(SB2ATP)2 showed significant chemotherapeutic activity against human breast carcinoma with positive estrogen receptor (MCF-7) while the remainder of the compounds showed significant bioactivity. The Schiff bases displayed higher cytotoxic activity compared to their metal complexes except for Cu(SB3ATP)2. None of the compounds showed any cytotoxic activity towards human cervical cancer (HeLa) or towards human breast carcinoma with negative estrogen receptors(MDA-MB-231)

2,3,4,6-Tetra-O-benzoyl-4-nitro­phenyl-1-thio-α-d-mannopyran­oside–dichloro­methane–diethyl ether mixed solvate (1/0.53/0.38)

The title compound, C40H31NO11S·0.53CH2Cl2·0.38C4H10O, was synthesized in two steps from mannose penta­acetate and single crystals were grown by slow evaporation. The structure was determined by single-crystal X-ray diffraction, confirming the α-configuration of the anomeric thioaryl substituent. The asymmetric unit contains two crystallographically distinct mol­ecules of the carbohydrate. The central pyran­ose rings of these are geometrically similar, but there are differences in the orientations of the benzoate substituents

4-Methoxy­phenyl 2,3,4,6-tetra-O-acetyl-1-thio-α-d-mannopyran­oside

The title compound, C21H26O10S, was synthesized in a single step from mannose penta­acetate. The mol­ecular structure confirms the α configuration of the anomeric thioaryl substituent. Spectroscopic and melting-point data obtained for the title compound are in disagreement with those previously reported, indicating the previously reported synthesis [Durette & Shen (1980 ▶). Carbohydr. Res. 81, 261–274] to be erroneous. The crystal structure is stabilized by weak inter­molecular C—H⋯O hydrogen bonds

(S)-3-Dimethyl­amino-2-{(4S,5R)-5-[(R)-2,2-dimethyl-1,3-dioxolan-4-yl]-2,2-dimethyl-1,3-dioxolan-4-yl}-2-hydroxy­propanoic acid

The Kiliani reaction on 1-de­oxy-(N,N-dimethyl­amino)-d-fructose, itself readily available from reaction of dimethyl­amine and d-glucose, proceeded to give access to the title β-sugar amino acid, C15H27NO7. X-ray crystallography determined the stereochemistry at the newly formed chiral center. There are two mol­ecules in the asymmetric unit; they are related by a pseudo-twofold rotation axis and have very similar geometries, differing only in the conformation of one of the acetonide rings. All the acetonide rings adopt envelope conformations; the flap atom is oxygen in three of the rings, but carbon in one of them. There are two strong hydrogen bonds between the two independent mol­ecules, and further weak hydrogen bonds link the mol­ecules to form infinite chains running parallel to the a axis