Low Epsilon Research Articles

Precision Proteomics as Protein Biomarker Discovery in Detecting Chronic Lung Allograft Dysfunction

Purpose Chronic lung allograft dysfunction (CLAD) remains the major barrier to long-term success after lung transplantation. A biomarker in blood that can diagnose CLAD would be of great clinical value. In the current study we have conducted broad proteomics analyzes to detect biomarkers for CLAD Methods Plasma from a cohort of 46 lung transplant recipients (CLAD grade 0: 27 samples, CLAD grade 1 - 3: 19 samples were collected. A panel of 639 proteins were analyzed using a high-component, multiplex immunoassay that enables analysis of protein biomarkers. This high multiplexing is achieved with Proximity Extension Assay (PEA) technology. Each biomarker is addressed by a matched pair of antibodies, coupled to unique, partially complementary oligonucleotides, and measured by quantitative real-time PCR. Results Regression analysis comparing 3 groups CLAD grade 0, CLAD grade 1, and CLAD grade 2-3 showed significant differences in plasma proteins expression levels of 12 different proteins: Low affinity immunoglobulin epsilon Fc receptor (FCER2). Corticoliberin (CRH). Interleukin-20 receptor subunit alpha (IL-20RA). TNF-beta (TNFB). Immunoglobulin superfamily member 3 (IGSF3). Cathepsin L1 (CTSL1). Anterior gradient protein 2 homolog (AGR2). Matrix metalloproteinase-9 (MMP-9). Thymic stromal lymphopoietin (TSLP). Importin subunit alpha-5 (KPNA1). Signaling threshold-regulating transmembrane adapter 1 (SIT1). Ras GTPase-activating protein 1 (RASA1). Conclusion Interestingly a significant decrease was observed in TNFB, KPNA1, IGSF3, CRH, FCER2 levels in recipients with CLAD grade 1, but also in recipients with CLAD grade 2 and 3. IL-20RA was significantly decreased in recipents with CLAD grade 1, but not in recipients with CLAD grade 2 and 3. Proteomic patterns may be a viable way in the search of early biomarkers for BOS

Control of Resonance Absorption Modes for Broadband Infrared Metamaterial Absorber

Magnetic polariton resonance, standing wave, and their coupling have provided interesting and exotic characteristics for infrared metamaterial. In this paper, the metal-insulator-metal metamaterial absorbers consisting of either single layer dielectric or bilayer dielectrics are discussed to reveal the geometric and dielectric thin film control of resonance absorption modes. These absorption modes can be independently manipulated by specific geometrical parameters, and thus provide a multi-peak characteristic for the metamaterial absorber. Comparing to the single dielectric structure, a new freedom of modes control is introduced to the bilayer dielectric structure by the addition of low epsilon MgF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , and then results in a quasi-continuous broadband absorption in the range of 5–8 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m. Experimental result further demonstrates the broadband effect, consistent with the numerical simulation.

High performance terahertz slotted waveguide antenna based on electrically split ring resonator metasurface employing low epsilon medium for E‐plane beam focusing

AbstractIn this article, a high performance terahertz slotted waveguide antenna incorporated with three dimension anisotropic low epsilon medium (LEM) is proposed, designed and theoretically investigated. The LEM is constructed from multilayer two dimension structure of electrically split ring resonator (eSRR) metasurface which exhibits anisotropic LEM medium in direction of propagation when it is placed in front of the slotted waveguide antenna at optimum distance. As a result, the E‐plane radiation beam of the slotted waveguide antenna is focused, and hence the directivity and the gain are improved, while the beam area is reduced. The proposed antenna as well as the LEM structure operating at 303 GHz are designed, optimized, and numerically simulated by using CST software. The effective parameters of the eSRR structure are extracted by Nicolson Ross Weir algorithm from the S‐parameters. The simulated results showed that, the E‐plane gain of the proposed slotted waveguide antenna is improved from 6.7 to 10.1 dB compared with the conventional slotted waveguide antenna. In addition, the E‐plane beam width is reduced from 94.1° to about 47°. The antenna return loss and the bandwidth are slightly changed. Furthermore, the proposed THz antenna offered easier fabrication processes with a high gain if it is compared with the horn antenna of the same size.

Measuring low loss dielectric substrates with scanning probe microscopes

This letter presents an algorithm for measuring the relative permittivity of thick dielectric substrates with scanning probe microscopy. Our technique does not rely on a specific type of microscopy setup and does not require expensive numerical field simulations. To demonstrate the versatility of our method, we perform measurements at high frequencies (18 GHz) with a scanning microwave microscope and at low frequencies (2 kHz) with electrostatic force microscopy. In our experiments, we study dielectric materials with epsilon values ranging from 4 (SiO2) to 300 (SrTiO3). For low epsilon values, the accuracy of the algorithm is better than 2% for tips with less than 80 nm tip radius.

A lower crustal mafic source for the ca. 2550 Ma Qôrqut Granite Complex in southern West Greenland

The late Neoarchaean Qorqut Granite Complex is the youngest large igneous intrusion in the Nuuk region in southern West Greenland, where basement is primarily of Eoarchaean and Mesoarchaean age with a tonalite-trondhjemite-granodiorite (TTG) composition. The Qorqut granite is generally undeformed and it intruded during a prolonged period, starting at ca. 2730 Ma, characterised by crustal reworking, possibly related to syn- or post accretion tectonics or continental collision. We present major and trace element whole rock chemistry and combined U/Pb, Hf and O isotope data from zircon. We obtained a mean zircon U/Pb age of 2547 +/- 4 Ma (MSWD = 0.63). Initial sHf values range from - 12 to -18 requiring a long residence time and a rather homogeneous source. Sample averaged zircon delta O-18 values range from 6.1 +/- 0.2%. to 6.5 +/- 0.3/0.7%o best interpreted with a source region of mainly unweathered mantle derived igneous rocks. Compared to the regional TTG basement, the QGC is characterised by low CaO and Na2O and high K2O, LREE and Rb contents, and a stronger fractionated REE pattern with a negative Eu anomaly. We show that the homogeneous Hf isotope signature of the granite together with its low epsilon value and its pristine oxygen isotope composition are best explained with an Eoarchaean mafic source with a Lu-176/Hf-176 around 0.015-0.019. Trace element modelling confirms that a mafic source in REE and with an eclogitic residue and with plagioclase as a fractionating phase would generate appropriate melt compositions. Modelling requires residual rutile in the source which constrain the pressures to > ca. 13-18 kbar. Zirconium saturation temperatures suggest magma temperatures in the range 750-850 degrees C. The obtained P-T conditions suggest a lower crustal source region in a thickened crustal unit consistent with a post or late continental collisional setting. (C) 2014 Elsevier B.V. All rights reserved.

Effect of the Mixing on the Dielectric Constant of Poly(vinylidene fluoride)/Isotactic Polypropylene Blends

In this work, the effect of a mixing process on the dielectric constant (epsilon) of a typical immiscible blend, poly(vinylidene fluoride) (PVDF)/isotactic polypropylene (iPP), is investigated. An iPP with a relatively low epsilon (ca. 3.4) is added to a PVDF matrix with a relatively high epsilon (ca. 9.5) to reduce the 8 of the system. The blend has a narrow window of cocontinuity (volume fraction of iPP (v(iPP)) of ca. 50-80 vol%). All of the measured epsilon values for the blends lie within the two limits defined by the parallel alignment and series alignment models, which are the upper and lower limits, respectively. It is found that for blends with v(iPP) of ca. 39.7 vol%, for which PVDF is the continuous matrix and iPP is the dispersed phase, prolonging mixing time and adding compatibilizer cause a monotonic decrease of epsilon for the system, which can be attributed to the increasing dispersion of the low-epsilon iPP filler in the high-epsilon PVDF matrix. Based on these results, a strategy to tune the epsilon of polymer blends and composites is discussed. It is suggested that architecture similar to a series alignment will favor the decrease of epsilon, while architecture similar to a parallel alignment will favor the increase of epsilon.

THE STATISTICS OF ALBEDO AND HEAT RECIRCULATION ON HOT EXOPLANETS

[Abridged] If both the day-side and night-side effective temperatures of a planet can be measured, it is possible to estimate its Bond albedo, 0<A_B<1, as well as its day-night heat redistribution efficiency, 0<epsilon<1. We attempt a statistical analysis of the albedo and redistribution efficiency for 24 transiting exoplanets that have at least one published secondary eclipse. For each planet, we show how to calculate a sub-stellar equilibrium temperature, T_0, and associated uncertainty. We then use a simple model-independent technique to estimate a planet's effective temperature from planet/star flux ratios. We use thermal secondary eclipse measurements -those obtained at lambda>0.8 micron- to estimate day-side effective temperatures, T_d, and thermal phase variations -when available- to estimate night-side effective temperature. We strongly rule out the "null hypothesis" of a single A_B and epsilon for all 24 planets. If we allow each planet to have different parameters, we find that low Bond albedos are favored (A_B<0.35 at 1 sigma confidence), which is an independent confirmation of the low albedos inferred from non-detection of reflected light. Our sample exhibits a wide variety of redistribution efficiencies. When normalized by T_0, the day-side effective temperatures of the 24 planets describe a uni-modal distribution. The dimensionless quantity T_d/T_0 exhibits no trend with the presence or absence of stratospheric inversions. There is also no clear trend between T_d/T_0 and T_0. That said, the 6 planets with the greatest sub-stellar equilibrium temperatures (T>2400 K) have low epsilon, as opposed to the 18 cooler planets, which show a variety of recirculation efficiencies. This hints that the very hottest transiting giant planets are qualitatively different from the merely hot Jupiters.

Investigations with a bandwidth measure for fatigue assessment of the Foinaven dynamic umbilical including VIV

Abstract An innovative use of a method to detect Vortex Induced Vibration (VIV) bandwidth in the curvature data of subsea flexible risers and umbilicals is presented. The parameter epsilon gives a valuable estimate of the bandwidth of signals such as VIV as a single value which may be used to track the behaviour with time and against other measures such as current speed. The method is conveniently based on a peak counting approach originally used in a marine context by Cartwright and Longuet-Higgins. Low epsilon values close to zero indicate a narrow-band process whereas values near unity indicate a broad-band process. Curvature and environmental data were gathered by the Foinaven Umbilical Monitoring System (FUMS) installed on the Foinaven Petrojarl IV floating production unit located in the Atlantic margin, west of Shetland. The VIV frequency range owing to current excitation considered is that in the range 0.2–2 Hz. This paper presents analyses showing the correlation of the epsilon bandwidth parameter with standard deviation of curvature, current speed and spectral analysis results for extended periods measured on the Foinaven dynamic umbilical. Examination of the number of frequencies and their values using spectrograms over long periods enable interesting interpretation of the build-up and decay of the VIV behaviour. These data are also reduced to the predominant peak frequencies, and standard deviation along with epsilon to provide a compact description of the VIV behaviour over 10 min intervals. Clear frequency and amplitude shifts can be observed as VIV varies with current ebb and flow. The behaviour is usefully described using only epsilon, standard deviation, and peak frequencies. The importance of epsilon for fatigue damage assessment is demonstrated through a formulation derived by Wirsching and Light. Strong VIV regimes are often characterized by an intense activity around a particular frequency and the impact of such relatively narrow-band events on the fatigue life of the structure is clearly demonstrated. This paper also presents the relative contributions of mooring, and waves/vessel motions, and VIV to fatigue damage. Although wave excitation remains the main source of fatigue, VIV appears to potentially contribute to a significant part of the overall fatigue damage.

Density Functional Theory Calculations on the Dielectric Constant Dependence of the Oxidation Potential of Chlorophyll: Implication for the High Potential of P680 in Photosystem II

The primary donor chlorophyll (Chl) of photosystem II (PSII), P680, has an extremely high oxidation redox potential (E(ox)) of approximately 1.2 V, which is essential for photosynthetic water oxidation. The mechanism for achieving a high potential such as that of P680 has been one of the central questions in photosynthesis research. Here, we have examined the dielectric constant (epsilon) dependence of the E(ox) of monomer Chl using density functional theory calculations with the polarizable continuum model. The calculated E(ox) of a model Chl compound exhibited a sharp increase with a decrease in epsilon in the relatively low epsilon region (epsilon < 5). In contrast, in the higher-epsilon region, E(ox) was rather insensitive to epsilon and converged to a constant value at very high epsilon values. This tendency in the high-epsilon region explains the experimental E(ox) values of isolated Chl a that have been observed in a relatively narrow range of 0.74-0.93 V. The E(ox) of Chl in an ideal hydrophobic protein was estimated to be approximately 1.4 V at an epsilon value of 2. This value indicates that Chl in a hydrophobic environment originally has a high E(ox) that is sufficient for oxidizing water (E(ox) = 0.88 V at pH 6). On the basis of the reported X-ray crystallographic structures, the protein environment of P680 in PSII was estimated to be more hydrophobic than that of the primary donors in bacterial reaction centers. It is therefore suggested that the low-dielectric environment around P680 is one of the major factors in its very high E(ox), and thus, introducing nonpolar amino acids into the binding pocket of P680 was an important process in the evolution of PSII.

Influence of the three-dimensional heterogeneous roughness on electrokinetic transport in microchannels

Surface roughness has been considered as a passive means of enhancing species mixing in electroosmotic flow through microfluidic systems. It is highly desirable to understand the synergetic effect of three-dimensional (3D) roughness and surface heterogeneity on the electrokinetic flow through microchannels. In this study, we developed a three-dimensional finite-volume-based numerical model to simulate electroosmotic transport in a slit microchannel (formed between two parallel plates) with numerous heterogeneous prismatic roughness elements arranged symmetrically and asymmetrically on the microchannel walls. We consider that all 3D prismatic rough elements have the same surface charge or zeta potential, the substrate (the microchannel wall) surface has a different zeta potential. The results showed that the rough channel's geometry and the electroosmotic mobility ratio of the roughness elements' surface to that of the substrate, epsilon(mu), have a dramatic influence on the induced-pressure field, the electroosmotic flow patterns, and the electroosmotic flow rate in the heterogeneous rough microchannels. The associated sample-species transport presents a tidal-wave-like concentration field at the intersection between four neighboring rough elements under low epsilon(mu) values and has a concentration field similar to that of the smooth channels under high epsilon(mu) values.

Factors governing the kinetic competition of nitrogen and sulfur ligands in cisplatin binding to biological targets.

The kinetic competition of sulfur and nitrogen nucleophiles L in the substitution reactions of cisplatin derivatives, cis-[Pt(II)(NH(3))(2)(X)(OH(2))](n)(+) + L --> cis-[Pt(II)(NH(3))(2)(X)(L)](m)(+) + H(2)O (X = Cl(-), H(2)O), has been studied using density functional theory and continuum dielectric calculations. The calculations reveal an intrinsic kinetic preference of platinum(II) for nitrogen over sulfur ligands. However, biologically relevant substituents can mask this preference for nitrogen nucleophiles. Investigation of the activation free energies of the substitution reactions in dependence of the dielectric constant epsilon demonstrates the microenvironment to be crucial in the binding of cisplatin to its intracellular targets. The fused aromatic heterocycle of guanine stabilizes the transition state for platination at a smaller epsilon more efficiently than do the functional groups of amino acid residues. The results of this work suggest a relatively facile platination of guanine-N7 sites of DNA in regions of low epsilon, particularly in the proximity of histone cores.

Volcanisme triasique calco-alcalin a shoshonitique du Nevada occidental

Volcanisme triasique calco-alcalin a shoshonitique du Nevada occidental

An F-rich, Sn-bearing volcanic-intrusive complex in Yanbei, South China

The igneous complex that hosts the Yanbei porphyry tin deposit is situated along the eastern margin of the southeast China Caledonian fold belt. It intrudes a Late Jurassic granitic batholith and was unconformably covered by Late Cretaceous red beds. The complex consists mainly of volcanic (ignimbrites and minor rhyolitic lavas, tuffs, and subvolcanic rhyolite porphyry) and intrusive rocks (topaz-bearing granite porphyry and granite). These rocks are generally peraluminous with F- and VI Al-rich biotite as the main mafic mineral, and F-rich and OH-poor topaz as an accessory mineral in the granite porphyry and granite, and as an essential mineral in the topazite. Topaz in the granites is usually interstitial and crystallized during the late magmatic stage. The volcanic rocks and granites are rich in Si, K, F (SiO 2 > 75 wt %, Na 2 O/K 2 O = 0.03-0.72, F = 0.06-6.48 wt %) and incompatible trace elements (Rb, Zr, Nb, W, Sn ) and poor in Mg, Ti, Ca, P and compatible trace elements (Sr, Eu ). The chondrite-normalized rare earth element (REE) patterns for the granites generally have a distinct V shape, with strong Eu depletion (Eu/Eu (super [whitesunwithrays]) = 0.04-0.20). The main rocks of the complex have low epsilon Nd (T) values (-9.3 to -8.9 for volcanic rocks, -4.0 to -4.8 for granites), and high delta 18 O values of quartz from dacite (9.5ppm) and granites (9.6-10.1ppm). The difference in epsilon Nd (T) between the volcanic rocks and granites indicates that they are not comagmatic. The source of the volcanic rocks probably contains a greater metasedimentary component than that of the granites.The Yanbei porphyry tin deposit is located along the contact zone between topaz-bearing granite porphyry and rhyolite porphyry, and consists principally of one orebody which makes up 99 percent of the total reserves. Of the metallic minerals (5% by volume), cassiterite, pyrite, and chalcopyrite are dominant, sphalerite, wolframite, and galena are less important, and siderite, molybdenite, and stannite are minor. Cassiterite accounts for 96 percent of the total Sn reserves and stannite is the subordinate Sn-bearing mineral that occurs as rims around chalcopyrite. Cassiterite occurs mostly in disseminated form and as veinlets. The wall-rock alteration is intense and can be roughly grouped into three zones spatially arranged around the granite porphyry, namely: topaz-quartz, chloritic, and sericitic zones. Most of the orebody occurs in the topaz-quartz and chloritic zones. Hydrothermal alteration caused a decrease in K and Na and an increase in Al, Fe, Ca, Sn, W, and Cu. The delta 18 O values of quartz and cassiterite from the mineralized zones vary from 6.0 to 11 per mil, and the calculated delta 18 O (sub H 2 O) values of the ore-forming fluid range from 4.2 to 7.8 per mil. The altered rocks have elevated delta 18 O (sub H 2 O) values (14.5-9.7ppm) relative to fresh rocks. The pyrite from the ore has a limited range of delta 34 S values (-0.3-+1.5ppm). These data suggest a magmatic source for the ore-forming hydrothermal fluid.

Twin nematic phenylbenzoates in a.c. electric fields

The orientational behaviour of nematic compounds having twin phenylbenzoate mesogens was examined under a wide range of a.c. electric fields (0-2 V mum-1 and 10Hz-50 kHz). For this study, crossed polarizing optical microscopy (POM) and real-time X-ray diffraction (RTXRD) measurements were employed to investigate optical and orientational response. These nematic compounds have a positive dielectric anisotropy and a relatively low epsilon// relaxation frequency which allowed study in both homeotropic and planar orientations over a controllable frequency range. The optical behaviour and X-ray results corresponded well, providing a tool for understanding the orientational behaviour of these liquid crystals. For homeotropic alignment, an electric field of over 1 V mum-1 was required in order to obtain good orientation. However, homeotropic orientation depended on a delicate balance between thermal fluctuations and dielectric torque imposed by the electric field, which are both strongly related to the elasticity of the LC domains. Due to this effect, the highest orientation parameter achieved for homeotropic orientation was only 0.48, which indicated that this state was still non-equilibrium. On the other hand, for planar orientation, a uniform texture with orientation parameter of 0.65 was easily obtained even at electric fields as low as 0.2 V mum-1. The application of an electric field stronger than 1 V mum-1 induced a distortion in the texture, and reduced the orientation parameter to 0.45 for planar alignment.

Lack of influence of apolipoprotein E4 on lipoprotein levels in the island population of Sardinia.

In this study, the apolipoprotein E (apoE) genotypes as well as plasma lipid and lipoprotein levels have been determined for the first time in 633 healthy and unrelated inhabitants on the island of Sardinia (291 men and 342 women, age range 6-89 years), randomly selected in the four districts of Sardinia among healthy people having parents and grandparents born in the same geographic area. This island lies in the centre of the western Mediterranean sea with a well-recognized peculiar and preserved genetic background. The epsilon 3 allele frequency (0.897) is higher than that previously reported in southern and mainland Italy and is one of the highest in Europe and among Caucasians; epsilon 2 allele frequency (0.040) is the lowest in Europe; epsilon 4 (0.063) is unusually low and, most interestingly, does not change in the different age groups, i.e. does not decrease in old subjects. Lipid and lipoprotein analysis confirm that total cholesterol and low-density lipoprotein (LDL)-cholesterol levels are lower than those described in mainland Italy; moreover, in this large Sardinian series, accurately selected, epsilon 4 allele did not influence total cholesterol (P = 0.270), LDL-cholesterol (P = 0.667) and high-density lipoprotein (HDL)-cholesterol (P = 0.549) as in other populations. In contrast, subjects carrying the epsilon 2 allele were found to have significantly lower total cholesterol (P = 0.001) and LDL-cholesterol (P = 0.001) levels than epsilon 3 carriers. The low epsilon 4 frequency and the lack of influence of this allele on lipid metabolism is a unique characteristic and, to date, has been described only in Sardinia among Caucasians; it might contribute to the low prevalence of coronary artery disease in this island.

Polymorphisms of apolipoproteins A-IV and E in a Turkish population living in Germany.

Human apolipoproteins (apo) E and apo A-IV are polymorphic with significantly different allele frequencies among different ethnic groups. Whereas the variation at the apo E gene locus affects plasma cholesterol levels in all populations studied so far and is associated with longevity in Caucasians, the influence of the common apo A-IV polymorphism on plasma lipoproteins has not been unanimously accepted. We have therefore determined the common apo E and apo A-IV polymorphisms by isoelectric focusing, calculated the respective allele frequencies and studied their effects on plasma lipoproteins in a random sample of 240 nonrelated Turkish subjects (141 males, 99 females) living in Germany and originating from central and eastern Anatolia. When compared with the German population and other Caucasians in Europe a prominence of the apo epsilon 3 allele frequency (0.885) was accompanied by a decrease in the frequencies of both the apo epsilon 2 allele (0.048) and the apo epsilon 4 allele (0.067). Thus, the Turkish population studied here clustered with populations mainly from southern Europe and Japan, which have low epsilon 2 and epsilon 4 allele frequencies. Also, the frequency of the A-IV-1 allele was higher (0.967) and that of the A-IV-2 allele lower (0.033) in the Turkish subjects studied than in other populations. At an average level of total cholesterol of 194.5 +/- 45 mg/dl, no significant influence of the A-IV alleles on plasma lipoproteins was seen. However, apo E and apo B differed significantly between apo E phenotypes, with high levels of apo E and low levels of cholesterol and apo B in carriers of the epsilon 2 allele, and vice versa for the epsilon 4 allele. The average cholesterol excess for the epsilon 2 allele was -7.95 mg/dl, for the epsilon 3 allele, -1.34, and for the epsilon 4 allele, + 14.15 mg/dl. Thus, despite the unusual frequency distribution of the apo E alleles, their effects on plasma lipoproteins are within the range reported for other populations in Europe.

The interaction of apurinic acid aldehyde groups with pararosaniline in the Feulgen-Schiff and related staining procedures.

The equilibrium reactions involved in the formation of the apurinic acid (APA)-Schiff chromophores in the staining phase of the Feulgen-Schiff reaction do not allow a quantitative conversion of APA to these chromophores. By modification of the sulfite and dye concentrations and the pH of the staining reagents, or by using better solvents for pararosaniline like acetic acid or dimethylsulfoxide (DMSO) a shift of these equilibria was attempted in order to obtain a higher amount of APA-bound dye. A 40% higher absorbance, when compared with the normal Schiff-staining, was obtained in model films by staining with a saturated solution of pararosaniline in a 1:1 v/v mixture of DMSO and SO2-water, followed by rinsing in SO2-water. A doubling of the absorbance resulted in the same objects when a saturated solution of pararosaniline in a 2 M acetic acid/acetate buffer of pH 4.45 was used for staining, followed by a short rinse in SO2-water. Amino groups (as found in histones) are shown to compete with the amino groups of pararosaniline for the APA aldehydes. This effect, although causing lower staining intensities, is shown not to be the explanation for the differences in stain content found between more and less compact forms of chromatin. Depending on the pH, and dye and sulfite concentrations of the staining reagents, the following components are considered as possible contributors to the mixture of chromophores (Duijndam et al., 1973 b) formed between APA and Schiff's reagent or its modifications: 1. An acid labile component with a wavelength of maximal absorbance (lambda max) near 510 nm; its structure is probably the azomethine--CH=N--; 2. A relatively acid stable component with a high value of molecular absorbance (epsilon), an lambda max near 570 nm and possibly having an enamine structure--CH=CH--NH--; 3. A component with intermediate acid stability, low epsilon, and lambda max near 540 nm, and which is probably an alkylsulfonic acid --CH(SO3H)--NH--compound. Small differences in the staining conditions in the histochemical application of the Feulgen-Schiff reaction may cause a shift in the ratio between especially components 2 and 3, resulting in variations in stain content and in lambda max.