The Concept of Folic Acid in Health and Disease

Folates have a pterine core structure and high metabolic activity due to their ability to accept electrons and react with O-, S-, N-, C-bounds. Folates play a role as cofactors in essential one-carbon pathways donating methyl-groups to choline phospholipids, creatine, epinephrine, DNA. Compounds similar to folates are ubiquitous and have been found in different animals, plants, and microorganisms. Folates enter the body from the diet and are also synthesized by intestinal bacteria with consequent adsorption from the colon. Three types of folate and antifolate cellular transporters have been found, differing in tissue localization, substrate affinity, type of transferring, and optimal pH for function. Laboratory criteria of folate deficiency are accepted by WHO. Severe folate deficiencies, manifesting in early life, are seen in hereditary folate malabsorption and cerebral folate deficiency. Acquired folate deficiency is quite common and is associated with poor diet and malabsorption, alcohol consumption, obesity, and kidney failure. Given the observational data that folates have a protective effect against neural tube defects, ischemic events, and cancer, food folic acid fortification was introduced in many countries. However, high physiological folate concentrations and folate overload may increase the risk of impaired brain development in embryogenesis and possess a growth advantage for precancerous altered cells.     

A Laser Projection System for Displaying Dynamic Information

The possibility of reproducing computer and TV information on large screens is demonstrated. A good contrast in the image was attained with the use of different optical systems. A multichannel system making it possible to realize the transmission of a large body of information is considered.     

Temporal characteristics of nanosecond magnetization reversal of flat permalloy films

A comparative study was made of different time intervals characterizing nanosecond magnetization reversal of flat permalloy films. These intervals increase with increasing relative coercive force of the samples. The results obtained for the durations of the magnetization reversal by different methods are practically the same in the case of the fastest regimes and are different for the slow regimes.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 58–61, December, 1970.     

Effect of conductivity anisotropy on the current-density and heat-flux distributions in high-current plasma accelerators

An experimental study was made of the heat-flux and current-density distributions along the length of the outer electrode in a high-current end-type plasma accelerator with different electrode polarities. When the outer electrode is anode, the heat-flux and current-density maxima move toward the end of the outer electrode. When the outer electrode is cathode, the maxima move in the opposite direction. These effects are explained in terms of an anisotropy of the conductivity in the accelerator, which is particularly pronounced in the sheath near the electrode.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 10, pp. 56–61, October, 1970.     

Analysis of the Isotopic Composition of Exhaled Air by the Diode Laser Spectroscopy Method in the 2-μm Region for Diagnosis of Helicobacter pylori-Associated Diseases

Optics and Spectroscopy - To diagnose digestive diseases associated with Helicobacter pylori infection, we applied laser spectroscopic analysis of the 13СО2/12СО2 isotope...     

Reflection refractometry for nearly normal incidence and at the Brewster angle

We consider and experimentally study two reflection refractometry methods involving reflection of light from the optical surface of a material for nearly normal incidence and for incidence at the Brewster angle. We analyze the sources of error in the methods, and show that it is possible to use laser radiation to measure the refractive index of materials to four decimal places. We note the advantages of the methods in preparing samples for measurements in the case of solid, liquid, film, and weakly absorbing materials.