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This paper proposes a method that provides a phase image related to the demagnetization field (Hd) within a thin-foil permanent magnet using electron holography. The observation of Hd remains a significant challenge because electron holography in principle allows only imaging of the magnetic flux density (B), which is a mixture of the contributions from magnetization (M), stray magnetic field (Hs) outside of the specimen and Hd inside of the specimen. The phase map approximating Hd, which was determined by processing of the electron holography observation from a Nd2Fe14B single-crystalline specimen, showed a good agreement with the prediction by micromagnetic theory. With respect to permanent magnets, this method can be applied to examinations about the coercivity mechanism, which is sensitive to the demagnetization field. Graphical Abstract.

Foiled carbene structures comprising strong stabilizing interactions between the divalent carbon and the intramolecular double bond have been located by DFT calculations. These tetracyclic species bearing fused five-membered rings impeding intramolecular rearrangements are theoretically predicted to lie in a deep potential energy well. A suitable dibromocyclopropane precursor for this type of foiled carbene has been prepared in 12 steps. Its treatment with methyllithium led to the isolation of a product of a formal carbene dimerization, a bicyclopropylidene.

endo-Tricyclo[3.2.1.0(2,4)]oct-8-ylidene is a foiled carbene reaction intermediate. It was generated by thermolyzing Δ(3)-1,3,4-oxadiazoline precursors dissolved in benzaldehyde and acetophenone. The products appear to stem from direct insertion of the carbene's divalent C atom into the α-bonds of the carbonyl compounds; however, this is only superficial. The strict stereochemistry observed is due to the topologies of the reaction intermediates of the proposed two-step mechanism. Bimolecular nucleophilic addition generates bent 1,3-zwitterions. The neutral reaction intermediates undergo pinacolic rearrangements to form the observed adducts. Product ratios reflect the migratory aptitudes of the carbonyl compounds' α-substituents. The carbene reaction was modeled using DFT. The singlet carbene's bicoordinate C atom bends 31° toward the endo-fused cyclopropane bond, elongating it to r = 1.69 Å. The resulting trishomocyclopropyl HOMO{-1} is a three-center two-electron bond responsible for the electron-deficient carbene's nucleophilicity. Its calculated properties are consistent with this assertion: (1) singlet-triplet (ΔE(S-T)) energy gap of -25 kcal/mol, (2) gas-phase proton affinity (PA) value of 272 kcal/mol, (3) hard and soft acid and base (HSAB) ΔN value of -0.2 in its initial reaction with the carbonyl compounds, and (4) negative frontier orbital interaction values ΔΔE(PhC(O)H) = -4.38 eV and ΔΔE(PhC(O)Me) = -3.97 eV.

Oxadiazoline 6 was synthesized to generate endo-tricyclo[3.2.1.0(2,4)]octan-8-ylidene (3) by either photolysis or thermolysis. Diastereomer 6a thermally decomposed twice as fast as 6b. Carbene 3 was trapped stereoselectively by acrylonitrile and diethylamine in high yields. It behaved as a nucleophilic carbene with electron-poor alkenes, like acrylonitrile, but as an electrophile with very electron-rich species, such as diethylamine. However, when the reactions were performed in cyclohexane and cyclohexene, isomerization of 3 was favored. Replacement of the double bond in 7-norbornenylidene (1) by the single bond in the endo-fused cyclopropane unit of carbene 3 led to similar outcomes. Carbene 3 rightfully belongs to the family of foiled carbenes.

The EDA-NOCV analysis shows that the singlet 2-adamantylidene is a foiled-type carbene stabilized by the hyperconjugative interaction of one pair of the vicinal C-C σ-MOs with the empty p-orbital on the carbene carbon atom. The high proton affinity and hydride affinity indicate the ambiphilic nature of 2-adamantylidene.

The bicyclic alkenylidenes 9 (bicyclo[3.2.1]oct-2-en-8-ylidene) and 17 (bicyclo[3.3.1]non-2-en-9-ylidene) were claimed to be stabilized foiled carbenes. Our B3LYP and MP2 computations confirm previous experimental data. Moreover, they show that these carbenes are very reactive and rearrange rapidly, mainly through a 1,2-vinyl shift by overcoming a low barrier (1.2 to 5.4 kcal/mol). This is in contrast to the high barriers (up to 30 kcal/mol) predicted for the same type of rearrangements in norborn-2-en-7-ylidene derivatives. In 17 and bicyclo[4.1.1]oct-2-en-7-ylidene (23), the divalent carbon atom is even bent away from the double bond!

The chemistry of endo-tricyclo[6.2.1.0 (2.7)]undec-9-en-11-ylidene (10), an archetypal foiled carbene, has been investigated. The intermolecular reactions of 10 are most conveniently performed with oxadiazoline 6 because the corresponding diazirine can be obtained only in very low yield. Furthermore, the aziridinyl imine is difficult to decompose and the tosylhydrazone sodium salt poorly soluble in common organic solvents. Photolysis of 6 in diethylamine leads merely to a reduction of the diazo group and regeneration of acetyl hydrazone 5, whereas thermolysis cleanly affords tertiary amine 12(anti) in 77% yield. Calculations show that even stabilized-nucleophilic carbenes react with amines through an ylidic pathway and not by a concerted insertion into the N-H bond. Nevertheless, in the gas phase, norbornen-7-ylidene (13) is predicted to be stabilized by one molecule of NH3 more efficiently through a hydrogen bond than by ylide formation.

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B3LYP/6-311+G(d,p) computations of the stabilization energies, singlet-triplet energy gaps, and lowest transition states for a set of cyclic alkenylidenes were performed in order to find the strongest interactions between the C-C double bond and the carbene center. The results suggest that among the alkenylidenes investigated in this study, those with a norbornenylidene structure represent strongly stabilized carbenes with a reduced reactivity toward intermolecular reactions. Further stabilization is found when the double bond is electron-rich or pyramidalized. Thus, for the rearrangement of syn-34 to take place, an activation barrier of about 22 kcal/mol needs to be overcome. The inclination to undergo a retro-Skattebøl rearrangement, which to our knowledge has never been observed experimentally, is characteristic for highly stabilized foiled carbenes.

Vincent Van Gogh and Giovanni Pascoli were artists who shared many aesthetic and biographical affinities. Both were somehow intoxicated by digitalis, the painter literally in a pharmacological sense, the poet symbolically or in a literary sense. In the paper we propose an original theory on how digital affected the last works of the Dutch painter and in particular the portrait of doctor Gachet, which differs from the previous theories, that attribute the chromatic style of Van Gogh to the xanthopsia caused by digitalis overdose. The Italian poet dedicated a short poem to the Foxglove, inspired by the popular wisdom that centuries ago already recognized the poisonous power of Foxglove.

Latino immigrant adolescents have the highest high school dropout rates of any race-ethnic or nativity group in the United States. One potential reason for high dropout rates among Latino immigrant youth is that many are unauthorized entrants. These unauthorized Latino immigrant youth have few opportunities to attend college, and, as they become aware of barriers to their educational progress and employment, they may lower their educational expectations. Using data from the Latino Adolescent Migration, Health, and Adaptation Project (N=275), we examine the association of unauthorized entry into the U.S. with the educational expectations of Latino immigrant youth. We find that adolescents entering the U.S. without authorization have lower educational expectations than those who enter with authorization. These differences in their expectations persist after controlling for differences in their pre-migration, migration, and post-migration experiences. Policies and programs that reduce barriers to higher education and labor market opportunities can potentially help to foster higher educational expectations among unauthorized immigrant youth and may promote their high school completion.

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Venous air-embolism (VAE) potentially catastrophic complication surgery. Based on previous data using changes in end-tidal nitrogen as an indicator of VAE, we surmised that changes in end-tidal argon (EtAr) may be an indicator of VAE. We sought to determine if a commercial mass-spectrometer (PCT Proline Analyzer 61700-8 Class 85, Ametek, Pittsburgh, PA 15238) could be used to detect changes in EtAr in an invitro model. A Drager Apollo™ (Drager, Lubeck, Germany) anesthesia machine was used to ventilate a dummy lung (2 L bag) with a minute ventilation of 6 L/min in 100% oxygen. The quadrupole mass-spectrometer (sampling at 0.0004 atm-cc/sec) was attached to the end-tidal inlet of the machine. Room air (1-60 mL) was injected into the dummy lung to simulate VAE. A strong baseline ion-current (1.2 × 10-12 amps) of argon was noted. Due to this contamination we were unable to detect "VAE" events of injected air. Argon represents approximately 0.93% of room air, or about 9300 parts per million (ppm). We detected about 2000 ppm argon in medical-grade oxygen (or 0.2%), limiting our ability to detect changes in EtAr. This is a USP-accepted contaminant, rendering this technology is insensitive for early, rapid detection of VAE. We assumed medical grade oxygen was pure and were surprised to learn otherwise. We want to share this likely largely unknown finding with the medical community.

Intrinsic immune defenses mediated by restriction factors inhibit productive viral infections. Select viruses rapidly establish latent infections and, with gene expression profiles that imply cell-autonomous intrinsic defenses, may be the most effective immune control measure against latent reservoirs. We illustrate that lysine-specific demethylases (KDMs) are restriction factors that prevent human cytomegalovirus from establishing latency by removing repressive epigenetic modifications from histones associated with the viral major immediate early promoter (MIEP), stimulating the expression of a viral lytic phase target of cell-mediated adaptive immunity. The viral UL138 protein negates this defense by preventing KDM association with the MIEP. The presence of an intrinsic defense against latency and the emergence of a cognate neutralizing viral factor indicate that "arms races" between hosts and viruses over lifelong colonization exist at the cellular level.