Gradual thermal spin-crossover mediated by a reentrant Z’ = 1 → Z’ = 6 → Z’ = 1 phase transition

The Fe[BF₄]₂ complex of the Schiff base podand tris[4-(thiazol-4-yl)-3-aza-3-butenyl]amine exhibits gradual thermal spin-crossover with T₁⁄₂ ≈ 208 K in the solid state. A weak discontinuity in the magnetic susceptibility curve at 190 K is associated with a reentrant symmetry-breaking transition involving a trebling of the unit cell volume (from P2₁/c, Z = 4, to P2₁, Z = 12). The intermediate phase contains six independent cations in puckered layers of low-spin, and high-spin or mixed-spin, molecules with an overall 30% high-spin population at 175 K

Non-collinear coupling between magnetic adatoms in carbon nanotubes

The long range character of the exchange coupling between localized magnetic moments indirectly mediated by the conduction electrons of metallic hosts often plays a significant role in determining the magnetic order of low-dimensional structures. In addition to this indirect coupling, here we show that the direct exchange interaction that arises when the moments are not too far apart may induce a non-collinear magnetic order that cannot be characterized by a Heisenberg-like interaction between the magnetic moments. We argue that this effect can be manipulated to control the magnetization alignment of magnetic dimers adsorbed to the walls of carbon nanotubes.Comment: 13 pages, 5 figures, submitted to PR

Spin States of Homochiral and Heterochiral Isomers of [Fe(PyBox)2]2+ Derivatives

The following iron(II) complexes of 2,6-bis(oxazolinyl)pyridine (PyBox; LH) derivatives are reported: [Fe(LH)2][ClO4]2 (1); [Fe((R)-LMe)2][ClO4]2 ((R)-2; LMe=2,6-bis{4-methyloxazolinyl}pyridine); [Fe((R)-LPh)2][ClO4]2 ((R)-3) and [Fe((R)-LPh)((S)-LPh)][ClO4]2 ((RS)-3; LPh=2,6-bis{4-phenyloxazolinyl}pyridine); and [Fe((R)-LiPr)2][ClO4]2 ((R)-4) and [Fe((R)-LiPr)((S)-LiPr)][ClO4]2 ((RS)-4; LiPr=2,6-bis{4-isopropyloxazolinyl}pyridine). Solid (R)-3⋅MeNO2 exhibits an unusual very gradual, but discontinuous thermal spin-crossover with an approximate Tmath formula of 350 K. The discontinuity around 240 K lies well below Tmath formula , and is unconnected to a crystallographic phase change occurring at 170 K. Rather, it can be correlated with a gradual ordering of the ligand conformation as the temperature is raised. The other solid compounds either exhibit spin-crossover above room temperature (1 and (RS)-3), or remain high-spin between 5–300 K [(R)-2, (R)-4 and (RS)-4]. Homochiral (R)-3 and (R)-4 exhibit more twisted ligand conformations and coordination geometries than their heterochiral isomers, which can be attributed to steric clashes between ligand substituents [(R)-3]; or, between the isopropyl substituents of one ligand and the backbone of the other ((R)-4). In solution, (RS)-3 retains its structural integrity but (RS)-4 undergoes significant racemization through ligand redistribution by 1H NMR. (R)-4 and (RS)-4 remain high-spin in solution, whereas the other compounds all undergo spin-crossover equilibria. Importantly, Tmath formula for (R)-3 (244 K) is 34 K lower than for (RS)-3 (278 K) in CD3CN, which is the first demonstration of chiral discrimination between metal ion spin states in a molecular complex

LEAN Production Management Model based on Organizational Culture to Improve Cutting Process Efficiency in a Textile and Clothing SME in Peru

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.In recent years, homegrown SMEs have had low production levels when compared with Chinese garment imports, losing their competitive advantage in the domestic market. SMEs represent 96% of garment companies in Peru and have a positive impact on the creation of jobs. The search for a technique to improve SME output was conducted in various studies; however, the efforts did not bear fruit over time. Thus, this article seeks to improve the low production efficiency in textile and clothing SMEs. Therefore, we proposed a model and validated it in the production area of a denim clothing manufacturing company in Peru. We conducted business diagnostics and found a production efficiency problem. Later, we adapted the Lean production management model to the prevailing organizational culture. The main result was that the company's production efficiency increased from 68% to 71%. Finally, employee commitment, along with the combination of the Lean model and organizational culture, allowed the improvements to stand the test of time after their implementation

Novel and natural knockout lung cancer cell lines for the LKB1/STK11 tumor suppressor gene

Germline mutations of the LKB1 gene are responsible for Peutz-Jeghers syndrome (PJS), an autosomal dominant inherited disorder bestowing an increased risk of cancer. We have recently demonstrated that LKB1 inactivating mutations are not confined to PJS, but also appear in lung adenocarcinomas of sporadic origin, including primary tumors and lung cancer cell lines. To accurately determine the frequency of inactivating LKB1 gene mutations in lung tumors we have sequenced the complete coding region of LKB1 in 21 additional lung cancer cell lines. Here we describe the mutational status of LKB1 gene in 30 lung cancer cell lines from different histopathological types, including 11 lung adenocarcinomas (LADs) and 11 small cell lung cancers (SCLCs). LKB1 gene alterations were present in six (54%) of the LAD cell lines tested but in none of the other histological types. Similar to our previous observations in primary tumors, all point mutations were of the nonsense or frameshift type, leading to an abnormal, truncated protein. Moreover, 2 cell lines (A427 and H2126) harbored large gene deletions that spanned several exons. Hence, we have identified additional lung cancer cell lines carrying inactivating mutations of the LKB1 tumor suppressor gene, further attesting to the significance of this gene in the development of LADs and providing new natural LKB1 knockouts for studies of the biological function of the LKB1 protein

An Incomplete Spin Transition Associated with a Z′=1→Z′=24 Crystallographic Symmetry Breaking

Crystalline [FeL₂][BF₄]2⋅Me₂CO (L=N-[2,6-di{pyrazol-1-yl}pyrid-4-yl]acetamide) is high-spin at room temperature, and undergoes an abrupt, hysteretic spin-crossover at T₁/₂ =137 K (Δ₁/₂ =14 K) that proceeds to about 50 % completeness. This is associated with a crystallographic phase transition, from phase 1 (P2₁/c, Z=4) to phase 2 (P2₁, Z=48). The cations associate into chains in the crystal through weak intermolecular π⋅⋅⋅π interactions. Phase 2 contains a mixture of high-spin and low-spin molecules, which are grouped into triads along these chains. The perchlorate salt [FeL₂][ClO₄]2⋅Me₂CO also adopts phase 1 at room temperature but undergoes a different phase transition near 135 K to phase 3 (P2₁/c, Z=8) without a change in spin state

The Speciation of Homochiral and Heterochiral Diastereomers of Homoleptic Cobalt(II) and Zinc(II) PyBox Complexes

Homochiral [M((R)-LR)2]2+ and heterochiral [M((R)-LR)((S)-LR)]2+ isomers of [Zn(LPh)2][BF4]2, [Zn(LiPr)2][BF4]2, [Co(LPh)2][BF4]2, and [Co(LiPr)2][BF4]2 (LPh = 2,6-bis(4-phenyloxazolinyl)pyridine; LiPr = 2,6-bis(4-isopropyloxazolinyl)pyridine) have been prepared and characterised. Six of the eight compounds were crystallographically characterised, showing that steric repulsions between ligand substituents lead to more distorted coordination geometries in the homochiral isomers, especially in the LiPr complexes. Heterochiral [M((R)-LiPr)((S)-LiPr)]2+ (M = Zn or Co) undergoes partial racemisation in CD3CN through ligand redistribution reactions, whereas [M((R)-LPh)((S)-LPh)]2+ does not (in agreement with previous reports). This may be a consequence of intramolecular π... π - interactions in [M((R)-LPh)((S)-LPh)]2+, whereby each pyridyl group is sandwiched between two phenyl substituents from the other LPh ligand. These π... π -interactions are disrupted in homochiral [M((R)-LR)2]2+, owing to the aforementioned steric clash between phenyl substituents in that isomer

Optical conversion of pure spin currents in hybrid molecular devices

Carbon-based molecules offer unparalleled potential for THz and optical devices controlled by pure spin currents: a low-dissipation flow of electronic spins with no net charge displacement. However, the research so far has been focused on the electrical conversion of the spin imbalance, where molecular materials are used to mimic their crystalline counterparts. Here, we use spin currents to access the molecular dynamics and optical properties of a fullerene layer. The spin mixing conductance across Py/C60 interfaces is increased by 10% (5 × 1018 m−2) under optical irradiation. Measurements show up to a 30% higher light absorbance and a factor of 2 larger photoemission during spin pumping. We also observe a 0.15 THz slowdown and a narrowing of the vibrational peaks. The effects are attributed to changes in the non-radiative damping and energy transfer. This opens new research paths in hybrid magneto-molecular optoelectronics, and the optical detection of spin physics in these materials

A gene-alteration profile of human lung cancer cell lines

ABSTRACT: Aberrant proteins encoded from genes altered in tumors drive cancer development and may also be therapeutic targets. Here we derived a comprehensive gene-alteration profile of lung cancer cell lines. We tested 17 genes in a panel of 88 lung cancer cell lines and found the rates of alteration to be higher than previously thought. Nearly all cells feature inactivation at TP53 and CDKN2A or RB1, whereas BRAF, MET, ERBB2, and NRAS alterations were infrequent. A preferential accumulation of alterations among histopathological types and a mutually exclusive occurrence of alterations of CDKN2A and RB1 as well as of KRAS, epidermal growth factor receptor (EGFR), NRAS, and ERBB2 were seen. Moreover, in nonsmall- cell lung cancer (NSCLC), concomitant activation of signal transduction pathways known to converge in mammalian target of rapamycin (mTOR) was common. Cells with single activation of ERBB2, PTEN, or MET signaling showed greater sensitivity to cell-growth inhibition induced by erlotinib, LY294002, and PHA665752, respectively, than did cells featuring simultaneous activation of these pathways, underlining the need for combined therapeutic strategies in targeted cancer treatments. In conclusion, our gene-alteration landscape of lung cancer cell lines provides insights into how gene alterations accumulate and biological pathways interact in cancer. Hum Mutat 30, 1199–1206, 2009. & 2009Wiley-Liss, Inc