Linear dichroism amplification: Adapting a long-known technique for ultrasensitive femtosecond IR spectroscopy

We demonstrate strong amplification of polarization-sensitive transient IR signals using a pseudo-null crossed polarizer technique first proposed by Keston and Lospalluto [Fed. Proc. 10, 207 (1951)] and applied for nanosecond flash photolysis in the visible by Che et al. [Chem. Phys. Lett. 224, 145 (1994)]. We adapted the technique to ultrafast pulsed laser spectroscopy in the infrared using photoelastic modulators, which allow us to measure amplified linear dichroism at kilohertz repetition rates. The method was applied to a photoswitch of the N-alkylated Schiff base family in order to demonstrate its potential of strongly enhancing sensitivity and signal to noise in ultrafast transient IR experiments, to simplify spectra and to determine intramolecular transition dipole orientations

Breast cancer "tailored follow-up" in Italian oncology units: a web-based survey

urpose: Breast cancer follow-up procedures after primary treatment are still a controversial issue. Aim of this study was to investigate, through a web-based survey, surveillance methodologies selected by Italian oncologists in everyday clinical practice. Methods: Referents of Italian medical oncology units were invited to participate to the study via e-mail through the SurveyMonkey website. Participants were asked how, in their institution, exams of disease staging and follow-up are planned in asymptomatic women and if surveillance continues beyond the 5th year. Results: Between February and May 2013, 125 out of 233 (53.6%) invited referents of Italian medical oncology units agreed to participate in the survey. Ninety-seven (77.6%) referents state that modalities of breast cancer follow-up are planned according to the risk of disease progression at diagnosis and only 12 (9.6%) oncology units apply the minimal follow-up procedures according to international guidelines. Minimal follow-up is never applied in high risk asymptomatic women. Ninety-eight (78.4%) oncology units continue follow-up in all patients beyond 5 years. Conclusions: Our survey shows that 90.4% of participating Italian oncology units declare they do not apply the minimal breast cancer follow-up procedures after primary treatment in asymptomatic women, as suggested by national and international guidelines. Interestingly, about 80.0% of interviewed referents performs the so called "tailored follow-up", high intensity for high risk, low intensity for low risk patients. There is an urgent need of randomized clinical trials able to determine the effectiveness of risk-based follow-up modalities, their ideal frequency and persistence in time

The Fascinating Chemistry of α-Haloamides

The aim of this review is to highlight the rich chemistry of α-haloamides originally mainly used to discover new C−N, C−O and C−S bond forming reactions, and later widely employed in C−C cross-coupling reactions with C(sp3), C(sp2) and C(sp) coupling partners. Radical-mediated transformations of α-haloamides bearing a suitable located unsaturated bond has proven to be a straightforward alternative to access diverse cyclic compounds by means of either radical initiators, transition metal redox catalysis or visible light photoredox catalysis. On the other hand, cycloadditions with α-halohydroxamate-based azaoxyallyl cations have garnered significant attention. Moreover, in view of the important role in life and materials science of difluoroalkylated compounds, a wide range of catalysts has been developed for the efficient incorporation of difluoroacetamido moieties into activated as well as unactivated substrates

Critical surveys covering the year 1999: total synthesis of natural products

--

Tert-butil (R)-3-idrossi-4-pentenoato, un conveniente ¿building block¿ chirale per la sintesi di sostanze naturali

Le interessanti proprietà biologiche di composti naturali a struttura aza-eterociclica rende ancora particolarmente attraente lo sviluppo di nuove metodologie sintetiche per l’ottenimento di nuclei azotati in maniera semplice e stereoselettiva. Il nostro interesse in questo campo si è concretizzato nella sintesi enantioselettiva di (1S,5S,6R)-6-idrossi-tropinone e nella sintesi enantiodivergente del lattone di Geissman-Waiss, precursore di alcaloidi pirrolizidinici, utilizzando, come materiale di partenza, (R)-tert-butil-3-idrossi-4-pentenoato. Intermedi chiave sono rappresentati da metil (R)-6-(tert-butossicarbonilammino)ossi-4-idrossi-2-esenoato e dalla malicaldeide tetrametilacetale, facilmente ottenibili, in forma enantiomericamente pura, da (R)-tert-butil-3-idrossi-4-pentenoato attraverso reazioni classiche della chimica organica

Linear dichroism amplification: Adapting a long-known technique for ultrasensitive femtosecond IR spectroscopy

We demonstrate strong amplification of polarization-sensitive transient IR signals using a pseudo-null crossed polarizer technique first proposed by Keston and Lospalluto [Fed. Proc. 10, 207 (1951)] and applied for nanosecond flash photolysis in the visible by Che et al. [Chem. Phys. Lett. 224, 145 (1994)]. We adapted the technique to ultrafast pulsed laser spectroscopy in the infrared using photoelastic modulators, which allow us to measure amplified linear dichroism at kilohertz repetition rates. The method was applied to a photoswitch of the N-alkylated Schiff base family in order to demonstrate its potential of strongly enhancing sensitivity and signal to noise in ultrafast transient IR experiments, to simplify spectra and to determine intramolecular transition dipole orientations

Synthetic Approaches to Enantiomerically Pure 8-Azabicyclo[3.2.1]octane Derivatives

This review concentrates on methodologies that provide enantioselective routes to chiral substituted 8-azabicyclo- [3.2.1]octane nuclei. Moreover, synthetic approaches to several specific targets have also been included

Enantioselective formal synthesis of Acromelic acid A via tandem Michael reaction methodoligy

A new formal synthesis of the potent neurotoxin,Acromelic acid A, has been accomplished by a tandem Michael reaction involving a 2-nitro-1,3-diene incorporated into a dihydropyridone nucleus as electrophilic alkene and an unsaturated glutamic ester derivative prepared from D-serine as a tool for the stereoselective construction of the 2,3,4-trisubstitued pyrrolidine ring sistem

Nutriential Hazards: Micronutrients: Vitamins and Minerals

To achieve an appropriate and healthy dietary regime, it is necessary to have a balance diet with an adequate contribution of every nutrient. Micronutrients play a fundamental role for normal metabolic functioning of human body, so their deficiencies produce specific clinical manifestations as well as a wide range of non-specific physiological impairments. Under certain situations or physiological conditions (such as stress, smoking, pollution, drugs and alcohol consumption, pregnancy, lactation, etc.), nutrient requirements are even higher, being impossible to fulfill them with standard diets. In fact, over two-third of the world's population lack of one or more essential mineral elements in their diets. Micronutrient malnutrition therefore represents a great burden for the public health system, with potential huge implications in both industrialized and developing countries. This problem can be overcome by dietary diversification, suitable supplementation, food fortification, or by increasing the concentration and/or bioavailability of mineral elements in place (biofortification). In the case of fortified foods, it is essential to characterize and assess the risk of overconsumption, which must be regulated by food safety authorities. The reference values of nutrient intake, therefore, should not be only focused on the prevention of risks associated with nutrient deficiencies or toxicity, but also on the prevention of chronic and degenerative diseases, with the ultimate aim of health promotion. This chapter intends to provide an overall picture of food micronutrients (macro and microminerals, hydrosoluble and liposoluble vitamins), including the possible risks associated with their deficiencies and toxicity. Highlights on infant food and fortified food are also provided