Diatom Earth Research Articles

Use of a commercial feed supplement based on diatom earth and yeast products on oxidative status and in vitro immune response in buffaloes during peripartum.

The transition period is a critical metabolic phase for dairy ruminants, especially those with high production levels. In spite of this, little is still known about dairy water buffalo. The aim of this study was to evaluate the effect of a commercial feed additive based on diatomaceous earth and hydrolyzed yeasts on health status, milk quality, and immune response of buffalo cows during the transition period. Eighty healthy Water buffaloes (Bubalus bubalis) of Italian Mediterranean breed were included in the trial. They were subdivided into two groups: one group received the additive (n = 40) while the control group (n = 40) received a placebo. The trial lasted 120d, from 60d before calving to 60d in milk. Blood samples were collected from each buffalo at -60 (60d from the expected calving), -30, 0 (calving), +15, +30, and +60 d (respectively, i.e., 15, 30, and 60d in milking). The biochemical as well as the oxidative profile, and the antioxidant power and enzymatic activity were evaluated in the samples obtained. Moreover, acute phase proteins, reactive proteins, and interleukin plasma levels were determined. Peripheral blood mononuclear cells (PBMCs) and monocytes were isolated and viability, reactive oxygen species (ROS), and reactive nitrogen species were measured on PBMC and monocytes. The introduction of additives enhanced the total antioxidant capacity and enzyme activity, while no differences were observed in oxidation products throughout the trial. Additionally, it significantly reduced the synthesis of ROS in polymorphonuclear cells, supporting a potential positive response in animals experiencing inflammation. The impact of oxidation on the products was not evident. Despite higher enzyme levels in plasma, this did not necessarily correspond to significantly increased enzymatic activity but rather indicated a higher potential. From these results, it was evident that the transition period in buffaloes differs notably from what reported in the literature for cows, probably due to the absence of common postpartum production diseases in dairy cows and lower metabolic challenges linked to lower milk production in buffaloes. Few parameters exhibited notable changes during the transition period in buffaloes, notably certain antioxidant enzymes, PBMC viability, PBMC ROS production, and Hp levels.

Mortality of Turkish diatomaceous earth against German cockroach (Blattella germanica L. Blattodea: Ectobiidae) adults

In this study, the mortality of diatom earth from Turkey coded ACN-1 against the German cockroach (Blattella gemanica L. Blattodea: Ectobiidae) adults on concrete, ceramic and parquet surfaces was investigated. Biological tests were carried out on three different surfaces against the adults of B. germanica at doses of 2.5, 5, 10 and 20 g/m2 diatom earth coded ACN-1 for 6 days. In all surface applications of ACN-1 diatomaceous earth, exposure time and doses caused significant effect on mortality rates of B. germanica adults. Diatom earth ACN-1 at 2.5 g/m2 caused 97.5%, 92.3% and 90% of mortality of B. germanica adults on the surfaces of concrete, ceramic and parquet at the end of the first day, respectively and 100% of mortality was obtained at the end of the second day in all conditions with this dose. For all other application doses, 100% mortality of B .germanica adults was observed at the end of the first day. In general, the mortality activity of ACN-1 diatom eartn against B. germanica adults was found to be similar on all three surfaces. We conclude that the Turkish diatom earth coded ACN-1, which is harmless to the environment, has the potential to be used in the control of B. germanica, which is a medical pest, and can be a good alternative in the control against this pest.

On the dissolution of sponge silica: Assessing variability and biogeochemical implications

The dissolution of the biogenic silica that constitutes the skeletons of silicifying organisms is an important mechanism for regenerating dissolved silicon in the ocean. The silica skeletons deposited to the seafloor after the organisms die keep dissolving until becoming definitively buried. The low dissolution rate of sponge skeletons compared to that of diatom skeletons favors their burial and makes sponges (Phylum Porifera) to function as important silicon sinks in the oceans. However, it remains poorly understood whether the large variety of siliceous skeletons existing in the Porifera involves similar variability in their dissolution rates, which would affect the general conceptualization of these organisms as silicon sinks. Herein we investigated kinetics of silica dissolution for major types of skeletons in the three siliceous lineages of Porifera, following standardized digestion conditions in 1% sodium carbonate with orbital agitation at 85°C. The results are compared with those of a previous study conducted under identical conditions, which considered diatom silica, sponge silica, and lithogenic silica. Unexpectedly, the silica of homoscleromorph sponges dissolved only a bit slower than that of freshly cultured diatoms and as fast as diatom earth. However, the rest of sponge skeletons were far more resistant, although with some differences: the isolated spicules of hexactinellid sponges dissolved slightly faster than when forming frameworks of fused spicules, being hexactinellid frameworks as resistant to dissolution as the silica of demosponges, irrespective of occurring in the form of isolated spicules or frameworks. The experiments also indicated that the complexation of sponge silica with aluminum and with chitin does not increase its resistance to dissolution. Because the rapidly-dissolving homoscleromorph sponges represent less than 1% of extant sponges, the sponge skeletons are still conceptualized as important silicon sinks due to their comparative resistance to dissolution. Yet, the turnover of silica into dissolved silicon will always be faster in environments dominated by hexactinellids with isolated spicules than in environments dominated by other hexactinellids and/or demosponges. We discuss whether the time required for a given silica type to completely dissolve in 1% sodium carbonate could be a predictor of its preservation ratio in marine sediments.

Preparation of composite monoliths of quaternized chitosan and diatom earth for protein separation.

In this study, composite monoliths with porous structures were prepared using quaternized chitosan and diatom earth for protein separation. Quaternized chitosan (N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride) dissolved in water was mixed with diatom earth and crosslinked with glutaraldehyde under low-temperature conditions to form a cryogel. Interconnected porous monoliths were obtained after removing ice crystals from the cryogel. The monoliths adsorbed bovine serum albumin selectively from the solution mixture of bovine serum albumin and bovine ɤ-globulin, and bovine ɤ-globulin was recovered in the flow-through fraction. The adsorption selectivity was enhanced by changing the solution pH from 6.8 to 5.5. The adsorption of bovine serum albumin by the monolith was replicated at least five times following its washing with a buffer containing 400mM NaCl and subsequent regeneration with a 10mM acetate buffer. The composited monolith is a promising adsorbent for the removal of acidic proteins, such as serum albumin contamination in neutral proteins, for example, ɤ-globulins, in bioproduction processes.

Doğal Killerin Model Yağın Renk ve Fiziko-kimyasal Özellikleri Üzerine Etkisi

Bu çalışmanın amacı, beta karoten ve klorofil katılarak hazırlanan model yağdan bu pigmentlerin verdiği rengin uzaklaştırılma kapasitelerinin 9 doğal kil ve 2 ticari ağartma toprağı (T.A.T.) açısından karşılaştırılmasıdır. Halloysit, zeolit, bentonit, sepiyolit, diatom toprağı, Magnesol XL, kaolin, montmorillonit ve perlit model yağa ağırlıkça %0.5 oranında katılmış ve 80°C’de 30 dakika karıştırmayı takiben yağ filtre edilerek, aletsel renk, yağ kaybı, serbest yağ asitliği (SYA), asit sayısı ve peroksit sayısı (PS) tespit edilmiştir. Beta karoten rengi için kontrole göre toplam renk farkı (E) en yüksek örnekler 2.3, 2.1 ve 1.8 değerleriyle T.A.T.-1, T.A.T.-2 ve halloysit ile muamele edilmiş örneklerde ölçülmüştür. Bu grup örneklerde ağırlık kaybı en az %22.1 ile bentonit ve en fazla %45.3 ile perlit muamelelerinde görülmüştür. Ayrıca serbest yağ asitliğini en fazla düşüren (%7.7) Magnesol XL kili olmuştur. Benzer şekilde T.A.T.-1 ve sepiyolit ile muamele edilmiş örneklerde PS değeri sıfır iken kaolin ile muamelede 79.1 meqO2/kg yağ olarak ölçülmüştür. Bu grupta sepiyolit ve Magnesol XL en başarılı sonuçları sağlamıştır. Klorofil katılan örneklerde yeşil renk en başarılı olarak sepiyolit tarafından (E=6.2) uzaklaştırılmıştır. Bu grup örneklerde ağırlık kaybı en fazla perlit (%52.9), en az bentonit (%23.5) ile muamele edilmiş örneklerde ölçülmüştür. SYA en fazla Magnesol XL (%5.9), ve PS en fazla T.A.T.-2 ve zeolit (0 meqO2/kg yağ) tarafından azaltılmış olup bentonit ve Magnesol XL örnekleri bu grupta öne çıkmıştır. Daha önce bu amaçla çalışılmamış olan halloysit ile genelde iyi sonuçlar sağlamıştır. Tüm killer için asit aktivasyonu, boyut küçültme, nano boyutta kil olarak hazırlama ve sonikasyon gibi modifikasyon teknikleri önerilmiştir.

SIMULATION OF CROPS YIELD GROWN ON LEACHED SMOLNITSA AND ALLUVIAL-MEADOW SOIL

The study presents results of field experiments with maize conducted during the year 2020 on two fields with different soils in Bulgaria, namely Leached smolnitsa and Alluvial-meadow soil. This article aims to perform a simulation experiment of crop yields to evaluate the limits of maize grain yield grown on soils with different properties and with different levels of nutrients. The multifactorial experiments include the application of mineral fertilizers - ammonium nitrate, superphosphate, potassium sulfate and diatomic earth, containing respectively – nitrogen (N), phosphorus (P), potassium (K), and diatomic earth, which represents 89-95% silica in amorphous form) in a design that allows assessment of the actions and interactions of the four factors, varying on three levels. The simulation is preceded by an analysis of variance and regression analysis of the experimental data. Simulation is performed at medium levels of all nutrients and on concurrent levels of nutrients including the high level of two fertilizers excluding two others. The summary results show that the experimental and simulated maize yields on Leached smolnitsa in Bozhurishte are significantly lower than those on Alluvial-meadow soil in Tsalapitsa.

Yerli Bazı Diyatom Topraklarının Laboratuvar Koşullarında Khapra, Trogoderma granarium Everts (Coleoptera: Dermestidae), Larvalarına Karşı Biyolojik Etkinliği

Bu çalışma ülkemizde son yıllarda tarımsal mücadelede önemi artan diyatom toprağının Khapra böceği (Trogoderma granarium Everts) larvalarına karşı biyolojik etkinliğinin araştırılması amacıyla yapılmıştır. Çalışma kontrollü şartlarda iki farklı sıcaklık (25 ve 30 °C) ve %50-65 nem ortamında, yerli (Aydın, Ankara illeri) ve ithal marka SilicoSec® diyatom toprakları olmak üzere dört farklı dozda (0, 1000, 1500 ve 2000 ppm), dört tekerrürlü olarak yürütülmüştür. Larvaların ölü-canlı sayımları uygulamadan 7, 14 ve 21 gün sonra kaydedilmiş, uygulamalardan 60 gün sonra F1 döl verimi her bir uygulama belirlenmiştir. Yerli diyatom topraklarının zararlı üzerinde biyolojik etkinliği, diyatomun uygulama dozu, maruz kalma süresi ve yüksek sıcaklık ile artış göstermiştir. En yüksek biyolojik etkinlik, 30 °C sıcaklıkta 21. günde 2000 ppm dozunda Aydın diyatomunda (%65.4), bunu takiben Ankara diyatomunda (%53.8) gerçekleşmiş, buna karşın SilicoSec®’te bu oran %11.9 olarak kayıt edilmiştir. Buna ek olarak 25 °C sıcaklıkta her üç diyatom toprağının Khapra larvaları üzerinde biyolojik etkinliği düşük düzeyde kalmıştır (en yüksek Ankara diyatomu 21. günde 2000 ppm dozda %30.7). Yeni nesil döl verimi 25 °C sıcaklık ve 60. gün sayımları sonucunda, her üç diyatom toprağı uygulanan tekerrürlerde F1 dölü açısından bir farklılık belirlenememiş (%15.2-18.7), buna karşın en düşük F1 döl verimi 30 °C sıcaklıkta 2000 ppm’de %9 olarak gerçekleşmiştir. Sonuç olarak yerli diyatom topraklarımızın SilicoSec®’e göre daha yüksek oranda Khapra böceği larvalarını öldürdüğü ve ümitvar olduğu belirlenmiştir.

Origin of silica in rice plants and contribution of diatom Earth fertilization: insights from isotopic Si mass balance in a paddy field

Background and aims: The benefits of Si for crops is well evidenced but the biogeochemical cycle of Si in agriculture remains poorly documented. This study aims at identifying and quantifying the Si sources (primary and secondary soil minerals, amorphous silica, irrigation, Si-fertilizer) to rice plants. Method: Field experiments were carried out with and without application of diatomaceous earth (DE) under rice and bare conditions to determine the water and dissolved mass balance in paddy fields (Karnataka, Southern India). The fate of the Si brought by irrigation (DSi) (uptake by rice, uptake by diatoms, adsorption) was assessed through a solute mass balance combined with silicon isotopic signatures. Results: Above the ground-surface, about one third of the DSi flux brought by borewell irrigation (545 mmol Si.m−2) to bare plots and half of DSi in rice plots were removed from solution within minutes or hours following irrigation. Such rate is consistent with the rate of DSi adsorption onto Fe-oxyhydroxides but not with diatom blooms. In rice and rice + DE experiments, the isotopic fractionation factor (30e) between bore well and stagnant water compositions is close to −1 ‰, i.e. the isotopic fractionation factor known for rice, indicating that above-ground DSi removal would be dominated by plant uptake upon adsorption. Within the soil layer, pore water DSi decreases much faster in rice experiments than in bare ones, demonstrating the efficiency of DSi rice uptake upon adsorption. Total irrigation-DSi to plant-Si would then represent 24 to 36% in rice experiments (over 1460 ± 270 mmol Si m−2 in biomass) and 15 to 23% in rice + DE ones (over 2250 ± 180 mmol Si m−2). The δ30Si signature of whole plants was significantly different in the rice + DE plot analyzed, 0.99 ± 0.07 ‰, than in the rice one, 1.29 ± 0.07 ‰. According to these δ30Si signatures, the main Si source from the soil would be the amorphous silica pool (ASi). A slight contribution of DE to the rice plant could be detected from the Si isotopic signature of rice. Conclusions: The δ30Si signatures of the various soil-plant compartments, when associated to Si mass balance at soil-plant scale, constitute a reliable proxy of the Si sources in paddy fields. The solute Si balance is controlled by rice uptake in rice plots and by adsorption in bare ones. The main Si sources for the rice plants were soil ASi, irrigation Si and to a lesser extent Si fertilizer when it was applied.

Bio-inspired NADH regeneration by carbon nitride photocatalysis using diatom templates

In this report, the bio-inspired photocatalytic regeneration of NADH employing graphitic carbon nitride photocatalysis with a diatom frustule structure was presented. The functional structure was constructed from green and sustainable diatomite (diatom earth) by an “incipient wetness impregnation” method. By using [Cp*Rh(bpy)H2O]2+ as an electron mediator, the NADH yield can reach nearly 100%, with the enzymatically active 1,4-NADH being the only product. Furthermore, even without an electron mediator, a direct electron transfer between graphitic carbon nitride and β-NAD+ was possible and NADH could still be regenerated. Diatom-based carbon nitride showed a substantial improvement in regeneration efficiency compared with mpg-C3N4 which has a higher specific surface area. This was ascribed to the diatom structure, with its enhanced light trapping and scattering promoting high photocatalytic efficiency. Furthermore, abundant species of diatoms in the earth offer more possibilities to construct an artificial photosynthetic system using diatom frustules with excellent light-to-energy conversion efficiency.

Impregnation of porous material with phase change material for thermal energy storage

In order to efficiently recover waste heat in the form of latent heat, we studied the impregnation of a porous material with a phase change material (PCM); erythritol was selected as the PCM and expanded perlite (EP), diatom earth (DE), and gamma-alumina (GA) were selected as porous materials. Effects of vacuum in impregnation, pore size of porous materials, holding time and cyclic test on thermal properties of composites; latent heat, melting temperature, were mainly examined by using DSC. The following results were obtained. (1) The pores of EP were completely filled with liquid erythritol by the vacuum impregnation treatment, and the latent heat of the EP/erythritol composite reached 83% of the theoretical latent heat of pure erythritol (294.4 J g −1). (2) Porous materials with small pore sizes showed a low melting temperature for phase change composites. (3) The pores of EP were completely filled with erythritol at 1.8 ks immersion in the vacuum impregnation treatment. (4) EP/erythritol composite retained 75% of the impregnated PCM, even in a cyclic process of heating and cooling. In conclusion, the impregnation of porous material with erythritol is a promising method for conserving latent heat with high thermal storage density.

Silica Hollow Spheres with Nano-Macroholes Like Diatomaceous Earth

Artificial synthesis of hollow cell walls of diatoms is an ultimate target of nanomaterial science. The addition of some water-soluble polymers such as sodium polymethacrylate to a solution of water/oil/water emulsion system, which is an essential step of the simple synthetic procedure of silica hollow spheres (microcapsules), led to the formation of silica hollow spheres with nano-macroholes (>100 nm) in their shell walls, the morphologies of which are analogous to those of diatom earth.

Immobilization of heavy metals in the saturated zone by sorption and in situ bioprecipitation processes

An ex-mining site located in Katowice, Poland, where silver, zinc and lead mining along with other activities took place for decades is now heavily contaminated with heavy metals. Especially the Quaternary and Triassic aquifers and surface water in the surrounding area are polluted. One serious risk is the threat of the contamination to drinking water, since the Triassic aquifer provides drinking water for more than 300 000 inhabitants. The main pollutants of concern are B, Ba, Zn, Cd, Cu, As and Sr. Remediation measures proposed for the Quaternary aquifer include a combination of natural attenuation, sorption barriers and in situ bioprecipitation. Dolomites, Fly Ash, and Peat are considered as suitable adsorbent materials for removing barium and strontium from the contaminated groundwater. However, no adsorbent has been found to efficiently remove B. In situ bioprecipitation (ISBP), a process during which sulfate reducing bacteria are stimulated by the addition of various C-sources resulting in the reduction of sulfate to sulfide and the concomitant precipitation of heavy metals, has been tested on both clay and sand aquifer taken from the site. Zn, Cu and sulfate were removed in the sandy and in the clayey aquifer material. In situ bioprecipitation combined with sorption was evaluated over a 120 days time period for the Triassic aquifer. Zeolites in combination with HRC® or molasses gave the best results, removing 100% of Ba and Sr in less than 2 days and 35% of B after 120 days. However, no sulfate was removed under these conditions. In addition, when Zeolite was solely or combined with HRC® or molasses, > 98% Zn was removed in 88 days. Zn was also removed using MRC®, lactate, molasses, HRC® and Diatomic Earth in combination with HRC® or molasses. A combination of ISBP and sorption offers the potential to contain the metal contamination in this Triassic aquifer.

Solid catalysts on the basis of supported ionic liquids and their use in hydroamination reactions

The scope for the immobilization of homogeneous catalysts in supported ionic liquids was explored. Here, a solution of cationic transition metal complexes in the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate was supported on diatomic earth. The catalysts were then tested in the direct addition of 4-isopropylaniline to phenylacetylene (hydroamination). Supported Rh(I), Pd(II) and Zn(II) complexes combined a higher intrinsic catalytic activity relative to the corresponding homogeneous catalysts with a high selectivity.

The electrorheological performance of the particle materials adsorbed with strong rare earth electrolyte

The strong rare earth (RE) electrolytes-RE(ClO 4) 3, RE(NO 3) 3 and RECl 3 are adsorbed by the diatom earth (de), respectively and are dispersed in silicone oil. The electrorheological (ER) behavior of these electrorheological fluids (ERF) is tested at room temperature under d.c. field. The results show that the ER performance of the particle material may be changed with the rare earth electrolyte on the surface of the particles. The ER activity of the material can increase or decrease or disappear with the change of rare earth content (weight fraction) in the particles. The ER effect is strongly influenced by the ERF concentration. When the ERF concentration is beyond a certain value, the ER effect can disappear and the viscosity of ERF can decrease with the increase of electric field strength (E). The contribution of coordinated water with RE 3+ to ER effect is negligible.

Cationic surface modification by polyelectrolytes: Polyelectrolyte complex formation at inorganic particle surfaces

AbstractThe surface charge of inorganic finely dispersed materials like diatom earth, perlite, glass or clay may be changed from negative to positive by the adsorption of cationic polyelectrolytes. Different materials exhibit equivalent electrokinetic surface properties with high amounts of the polycation adsorbed. Interfaces modified this way are able to adsorb anionic dye stuffs. Their adsorption capability for the dye stuff may be enhanced by addition of polyanions due to the formation of a nonstoichiometric polyelectrolyte complex (PEC) and therefore an increased number of cationic centres in the interface. Experimental results indicate that the zeta potential is correlated to the outer PEC layer whereby dye stuff adsorption measurements are sensitive for the more inner surface regions, too. Immediately after modification, materials modified with poly(diallyldimethylammonium chloride) and poly(maleic acid‐co‐α‐methylstyrene) have negative zeta potentials at high excess of added polyanion and a positive one after separation of the solid. This behaviour is attributed to the formation of a nonstoichiometric PEC with polycation in excess and reversible interaction with polyanion in the surrounding solution. Experimental results indicate that the surface may act as “solid‐like” polyelectrolyte in competition to the polyanion.

ナラワスサビノリのポルフィランに関する研究 Ｉ ナラワスサビノリからのポルフィラン抽出条件の検討

A best search for the most efficient extraction condition of sulfated polysaccharide (Porphyran) from Porphyra yezoensis UEDA F. narawaensis MIURA was made. The highest yield was obtained by the following procedure: Raw algal fronds were treated with 3.7% formaldehyde solution in a flask closed with a stopper at 30°C for 24h. After addition of 2 times volume of distilled water, the suspension was heated at 100°C with stirring for 12h. The extract was cooled at room temperature and filtered through a layer of diatom earth. The clarified filtrate was dialyzed in a Visking cellophane tube against running tap water for 24h, and evaporated to 1/4 of its original volume under reduced pressure, to this was added 4 times volume of ethanol at room temperature. The gelatinous precipitate collected by centrifugation was washed with ethanol, and acetone, and dried at 30°C for 12h. Gel-filtration on Sepharose CL-2B showed that the higher molecular weight polysaccharides were extracted by treatment with a higher temperature and a lower molecular weight components which was eluted the position to the Vi increase in the amount with the length of extraction time.

On the Elimination of Organic Microcontaminants by Flocculation with Lime Hydrate

AbstractFor the purpose of utilizing domestic flocculants for the treatment of water and of reducing by this the equivalent imports of metal salts, in this paper the result of investigations made on model waters and on a river water sample is described. The model waters contained the pesticides Atrazin, Diuron and 2,4‐D, which partly were polluted in addition with different quantities of fulvic and humic acids as well as with colloidal substances causing turbidity (Friedland clay and finely dispersed cellulose). The investigations were supplemented by testing several adsorption media as γ‐aluminium oxide, active carbon and diatom earth. In the presence of fulvic and humic substances one does not succeed in eliminating the investigated herbicides by flocculation with lime hydrate. Only after chemical side reactions between these contained substances the adsorbability is clearly influenced. The different elimination efficiencies at different reaction conditions are explained in detail.

ChemInform Abstract: NITRATION OF TOLUENE IN THE PRESENCE OF POROUS MATERIALS

AbstractDie Einwirkung von Salpetersäure auf Toluol in Gegenwart von porösen Materialien wie japanischem sauren Ton, Silicagel, Aktivkohle, Molekularsieben oder Diatomeenerde führt zu p‐ und o‐Nitrotoluol.

多孔性物質の存在下におけるトルエンのニトロ化

The p- to o-ratio of nitrotoluenes formed by nitration of toluene in the presence of porous materials, such as Japanese acid clay, silica gel, active carbon, molecular sieves or diatom earth, was compared with that obtained by the usual nitration with mixed acid. In general, p/o increased more or less by adding the porous materials and showed tendency to increase when the proportion of nitric acid to the porous materials was decreased. Moreover, in the nitration of toluene adsorbed on the porous materials, the maximum p/o of 1.56 (with silica gel) was obtained, while the p/o by the usual nitration was 0.71. A part of such effect may be attributed to the steric-hindrance against o-substitution at fine porous spaces on the materials.

水産動物内臓油利用に関する研究-I

The author, having reported in his previous papers10)-15) extraction, refining, molecular distillation and concentration by saponification of vitamin oil and esterification of vitamin A alcohol studied in the aspect of fundamental conditions influencing their results as well as in that of important points taken care of in practicing them on industrial scales, now gives a description of the experiments he carried out to determine the stability of vitamin A contained in vitamin oils subjected to these various kinds of treatment, the stability being evaluated in accordance with the length of time in which a sample of vitamin oil is reduced by half in respect of its vitamin A content. In the first place, the stability of vitamin A was compared among liver oil samples obtained from different sources but equally by alkali digestion. As seen from the results of experiment presented in Table 1, liver oil preparations obtained from sharks come out top and those from cods and pollacks, tunas, giant bass and whales follow them in this order in respect of the stability of vitamin A content. It seems likely that the stability order here found is the reflexion of the readiness of undergoing the alkali digestion or in other words the difficulty in removing the natural antioxidative accompaniment of these sources of vitamin A. In the second place, the influence of refining method on vitamin A stability of refined vitamin oil was examined with liver oil specimens obtained by subjecting a crude sample of pollack liver oil to various refining schemes illustrated in Fig. 1, the results being presented in Table 2. As obvious from the table, as for the stability of vitamin A content to be assigned to different methods of refining vitamin oil here examined, crude liver oil comes out top and a liver oil sample subjected merely to filtration, that refined by means of alkali, that treated with acid, that processed with alcohol and that treated with diatom earth come in this order in succession to crude liver oil, the order being again suggestive of the difference in strength of removing natural antioxidant among these types of refining method. In the third place, the effect of molecular distillation as a means of concentrating the vitamin A in liver oil on the stability of this vitamin in distillate oil was inquired by examining the stability of vitamin A with samples of raw oil before distillation, those of distillate fractions respectively obtained at different temperatures and those of residual oil remaining after distillation, the results being shown in Tables 3 and 4. It is seen from these results that, irrespective of whether the source of liver oil is shark or whale, a vitamin oil fraction distilled at the lower temperature has the greater stability of vitamin A, while raw oil shows a value in respect of the stability of vitamin A content, which falls between the stability values for Fractions 1 and 2 both distilling at rather low temperatures. Although the stability of residual oil could not accurately estimated from some reasons, the above-mentioned results for distillate fractions and raw oil seem to be sufficient to suggest that natural antioxidant in liver oil can distill rather earlier than vitamin A. In the fourth place, the products respectively obtained in different working stages of the process wherein a vitamin oil previously concentrated by molecular distillation is subjected to concentration by saponification and the vitamin A alcohol thereby produced is further esterified were examined of their stability of vitamin A content, the results shown in Table 5 being obtained. As seen from the table, concentrated products of vitamin A alcohol prepared from different sources equally show values of stability as good as those found for a pollack liver oil obtained by the alkali digestion method.