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1.
Effect of a Pulsed Electric Field and Osmotic Treatment on Freezing of Potato Tissue 总被引:1,自引:0,他引:1
Jihène Ben Ammar Jean-Louis Lanoisellé Nikolai I. Lebovka Elisabeth Van Hecke Eugène Vorobiev 《Food biophysics》2010,5(3):247-254
This work discusses the effects of pulsed electric field (PEF) and osmotic pre-treatments on potato tissue structure and on
the freezing and freeze-drying behaviour of this tissue. Potato samples (26-mm diameter, 10-mm height) were treated by PEF
(400 V/cm) to high level of disintegration (conductivity disintegration index Z was ≈0.95) and were subjected to osmotic treatment in an aqueous solution of NaCl. The samples were either frozen in an air-blast
freezer at air temperature of −80 °C and velocity of 2 m/s or freeze-dried at 0 °C and 0.04-mbar pressure. The scanning electron
microscope (SEM) images evidenced similarity in structure of the cell walls and area and morphology of starch granules for
untreated and PEF-treated potato tissues. However, sequential (PEF + osmotic) pre-treatment of potato tissue resulted in starch
granules with rougher surface. The profiles of freezing curves were strongly dependent on pre-treatment. The longest effective
freezing time t
f
was observed for untreated tissue, and the values of t
f
were decreasing in the following sequence: untreated > PEF pre-treated > PEF + osmotically pre-treated. The faster freezing
and freeze drying and visually better quality of the dried samples were observed for PEF or sequential PEF + osmotic pre-treatments.
The SEM analysis revealed also a noticeable disorder of starch granule surface morphology inside the cells of the freeze-dried
potatoes after sequential PEF + osmotic pre-treatment. 相似文献
2.
Killing of microorganisms by pulsed electric fields 总被引:15,自引:0,他引:15
Lethal effects of pulsed electric fields (PEF) on suspensions of various bacteria, yeast, and spores in buffer solutions
and liquid foodstuffs were examined. Living-cell counts of vegetative cell types were reduced by PEF treatment by up to more
than four orders of magnitude (>99.99%). On the other hand, endo- and ascospores were not inactivated or killed to any great
extent. The killing of vegetative cell types depends on the electrical field strength of the pulses and on the treatment time
(the product of the pulse number and the decay time constant of the pulses). For each cell type, a specific critical electric
field strength (E
c) and a specific critical treatment time (t
c) were determined. Above these critical values, the fractions of surviving cells were reduced drastically. The “limits”E
c and t
c depend on the cell characteristics as well as on the type of medium in which the cells are suspended. Especially in acid
media living-cell counts were sufficiently decreased at very low energy inputs. In addition to the inactivation of microorganisms,
the effect of PEF on food components such as whey proteins, enzymes and vitamins, and on the taste of foodstuffs was studied.
The degree of destruction of these food components by PEF was very low or negligible. Moreover, no significant deterioration
of the taste of foodstuffs was detected after PEF treatment. Disintegration of cells by PEF treatment in order to harvest
intracellular products was also studied. Yeast cells, suspended in buffer solution, were not disintegrated by electric pulses.
Hence, PEF treatment is an excellent process for inactivation of microorganisms in acid and in thermosensive media, but not
for complete disintegration of microbial cells.
Receivced: 1 June 1995 / Received last revision: 13 September 1995 / Accepted: 20 September 1995 相似文献
3.
Ricardo N. Pereira Federico Gómez Galindo António A. Vicente Petr Dejmek 《Food biophysics》2009,4(3):229-239
We have investigated whether transient permeabilization caused by the application of pulsed electric field would give rise
to transient changes in the potato tissue viscoelastic properties. Potato tissue was subjected to nominal field strengths
(E) ranging from 30 to 500 V/cm, with a single rectangular pulse of 10−5, 10−4, or 10−3 s. The changes on the viscoelastic properties of potato tissue during pulsed electric fields (PEF) were monitored through
small amplitude oscillatory dynamic rheological measurements. The elastic (G′) and viscous moduli (G″) were measured every 30 s after the delivery of the pulse and the loss tangent change (tan-δ) was calculated. The results were correlated with measurements of changes on electrical resistance during the delivery of
the pulse. Results show a drastic increase of tan-δ in the first 30 s after the application of the pulse, followed by a decrease 1 min after pulsation. This response is strongly
influenced by pulsing conditions and is independent of the total permeabilization achieved by the pulse. Our results, supported
by similar measurements on osmotically dehydrated control samples, clearly show that PEF causes a rapid change of the viscoelastic
properties of the tissue that could be attributed to a partial loss in turgor pressure. This would be an expected consequence
of electroporation. The recovery of tan-δ to values similar to those before pulsation strongly suggests recovery of cell membrane properties and turgor, pointing at
reversible permeabilization of the cells. A slight increase of stiffness traduced by a negative change of tan-δ after application of certain PEF conditions may also give an indication of events occurring on cell wall structure due to
stress responses. This study set the basis for further investigations on the complex cell stress physiology involving both
cell membrane functional properties and cell wall structure that would influence tissue physical properties upon PEF application. 相似文献
4.
In this paper, we consider a circular central aperture surrounded with annular depth-tuned grooves and investigate the beaming
effect of the structure under illumination of a circularly polarized (CP) plane wave. As a CP plane wave is equivalent to
the superposition of two linearly polarized plane waves (TM and TE) with a phase difference of π/2, the superposition of the
electric field intensity, ( | Ex |2 + | Ey |2 ) \left( {{{\left| {E_x} \right|}^2} + {{\left| {E_y} \right|}^2}} \right) , is observed in the transmission field. In addition, two plasmonic modes are found at the resonant wavelengths λ
1 and λ
2 with each consisting of multiple wavelengths. At the wavelength λ
1 = 420 nm, the significant near-field collimation is formed along the direction z, having a long propagation distance up to 1.75 μm (≈4λ) away from the exit plane of the new plasmonic lens. 相似文献
5.
The Alternaria mycotoxin tenuazonic acid (TA) was quantified in fruit juices (n = 50), cereals (n = 12) and spices (n = 38) using a recently developed stable isotope dilution assay (SIDA). [13 C6,15 N]-TA was used as the internal standard. Method validation revealed low limits of detection (LODs) of 0.15 μg/kg (fruit juices),
1.0 μg/kg (cereals) and 17 μg/kg (spices). The respective limits of quantitation were about three times higher. Recovery was
about 100% for all matrices. The precision (relative standard deviation of replicate analyses of naturally contaminated samples)
was 4.2% (grape juice; 1.7 μg/kg), 3.5% (whole wheat flour; 36 μg/kg) and 0.9% (curry powder; 215 μg/kg). The median content
of TA in the analyzed samples was 1.8 μg/kg (fruit juices), 16 μg/kg (cereals) and 500 μg/kg (spices). Positive samples amounted
to 86% (fruit juices), 92% (cereals) and 87% (spices). 相似文献
6.
Theodoros Goulas Athanasios Goulas George Tzortzis Glenn R. Gibson 《Applied microbiology and biotechnology》2009,82(3):471-477
A genomic library of Bifidobacterium bifidum (NCIMB 41171) DNA was constructed in Escherichia coli RA11r (melA−B+) and one α-galactosidase encoding gene was isolated. Conceptual translation combined with insertional mutagenesis analysis
indicated an open reading frame (ORF) of 759 amino acid (aa) residues encoding an α-galactosidase (named as MelA) of 82.8 kDa.
Partial purification and characterisation showed that the enzyme had an apparent native molecular mass of ≈243 kDa and a subunit
size of ≈85 kDa. The enzyme belongs to glycosyl hydrolases 36 family with high aa sequence similarities (≈73%) to other known
α-galactosidases of bifidobacterial origin. Under optimum pH conditions for activity (pH 6.0) and high melibiose concentration
(40% w/v), the enzyme was able to form oligosaccharides with degree of polymerisation (DP) ≥3 at higher concentration than DP = 2,
with a total yield of 20.5% (w/w). 相似文献
7.
The intramolecular electron-transfer rate constant for the Cu(II)–topaNH2⇌ Cu(I)–topaSQ equilibrium in methylamine oxidase has been measured by temperature-jump relaxation techniques. At pH 7.0 the estimated kobs = 150±30 s–1 for both methylamine and benzylamine; assuming the equilibrium constant is ≈0.7–1 at pH 7.0 and 296 K, this would correspond
to a forward electron-transfer rate constant kET≈ 60–75 s–1. Although substantially slower than the previously determined kET≈ 20 000 s–1 for pea seedling amine oxidase [5] steady-state kinetics measurements established that kET > kcat≈ 4–10 s–1. Thus the Cu(I)-semiquinone state is a viable intermediate in methylamine oxidase turnover.
Received: 16 August 1995 / Accepted: 21 December 1995 相似文献
8.
Lefebvre O Uzabiaga A Chang IS Kim BH Ng HY 《Applied microbiology and biotechnology》2011,89(2):259-270
As the microbial fuel cell (MFC) technology is getting nearer to practical applications such as wastewater treatment, it is
crucial to consider the different aspects that will make this technology viable in the future. In this paper, we provide information
about the specifications of an energy self-sufficient MFC system as a basis to extrapolate on the potential benefits and limits
of a future MFC-based wastewater treatment plant. We particularly emphasize on the importance of two crucial parameters that
characterize an MFC: its electromotive force (E
emf) and its internal resistance (R
int). A numerical projection using state-of-art values (E
emf = 0.8 V and R
int = 5 Ω) emphasized on the difficulty at this moment to reach self-sufficiency using a reasonable number of MFCs at the laboratory
scale. We found that a realistic number of MFCs to provide enough voltage (=5 V) at a sufficient current (=0.8 A) to power
a pump requiring 4 W would be of 13 MFCs in series and 10 stacks of MFCs in parallel, resulting in a total number of 130 MFCs.
That would result in a treatment capacity of 144 L of domestic wastewater (0.5 g-COD L−1) per day. The total MFC system would be characterized by an internal resistance of 6.5 Ω. 相似文献
9.
Nay Min Min Thaw Saw Heidi Riedel Zhenzhen Cai Onur Kütük Iryna Smetanska 《Plant Cell, Tissue and Organ Culture》2012,108(1):47-54
Anthocyanin from grape cell cultures can be used as a natural alternative to synthetic dyes; particularly due to their reported
health-promoting properties. In this study, production of anthocyanin in cell suspension culture of Vitis vinifera was evaluated following treatment with either ethephon and/or pulsed electric fields (PEF). Overall, total production of
anthocyanin increased in treated cells compared to untreated cells. Treatment of cell suspension with PEF at day 14 of culture
resulted in 1.7-fold increase (1.42 mg/g DW) in anthocyanin content when compared to control cells; while, treatment with
ethephon resulted in 2.3-fold increase (1.99 mg/g DW) in anthocyanin content. When cells were treated with both ethephon and
PEF, 2.5-fold increase in anthocyanin content (2.2 mg/g DW) was observed. These findings demonstrate that PEF induces a defense
response in plant cells, and it may also alter the dielectric properties of cells and/or cell membranes, and would serve as
a viable elicitor of secondary metabolites in plant cell cultures. 相似文献
10.
To compare the effect of IV magnesium with other antihypertensives in emergency department (ED) patients with hypertension.
ED patients with a systolic BP > 135 mmHg or diastolic BP > 85 were approached for entry into the study. Those granting consent
were randomly placed into one of three treatment groups: (1) 1.5 gm IV MgSO4 (n = 42), (2) a parenteral or oral antihypertensive agent (n = 41), (3) both IV MgSO4 and an antihypertensive agent (n = 44). Systolic and diastolic blood pressures were measured at entry into the study and at 15, 30, 45, and 60 min after magnesium
or other antihypertensive medications were given. The main outcome measure was blood pressure at 60 min, and results were
compared using one-way analysis of variance with the post hoc Tukey HSD test. Compared to systolic and diastolic blood pressures
at time 0, both were lower at 15, 30, 45, and 60 min in all groups (p < 0.05). No significant difference in systolic or diastolic BP at any time point was observed when response to treatment
was compared between the three groups. Intravenous MgSO4 is as effective as antihypertensives at lowering BP in emergency department patients. 相似文献
11.
Jaak Jürim?e Peter J. Abernethy B. M. Quigley Kirsten Blake Michael T. McEniery 《European journal of applied physiology and occupational physiology》1997,75(4):357-362
The purpose of this investigation was to compare the myosin heavy chain (MHC) isoform expression of the triceps brachii muscle
and isoinertial, isometric and isokinetic strength indices in competitive bodybuilders (CB, n = 5), recreational resistance trainers (RT, n = 5), endurance-trained rowers (ER, n = 5) and control (C, n = 5) subjects. Muscle tissue samples were analysed for MHC isoform content using 6% sodium dodecyl sulphate-polyacrylamide
gel electrophoresis. The CB possessed significantly smaller (P < 0.05) percentage of MHC type IIb proteins [12.92 (SD 7.08)%] than RT [30.08 (SD 6.58)%] ER [31.20 (SD 2.74)%] and C [38.22
(SD 2.95)%] groups (i.e. CB < RT ≈ ER < C). While the content of MHC type IIa isoforms did not differ significantly between
the two resistance-trained groups [CB = 55.76 (SD 5.38)%; RT = 45.72 (SD 7.8)%], CB presented significantly more type IIa
MHC isoforms than ER [42.84 (SD 2.98)%] and C [34.72 (SD 1.57)%] subjects (i.e. CB ≈ RT > ER ≈ C). The MHC type I protein
content did not differ significantly among RT [24.20 (SD 4.89)%] ER [25.38 (SD 1.67)%] and C [27.06 (SD 1.81)%] groups. The
CB [31.32 (SD 2.67)%] presented significantly more type I MHC isoforms only in comparison with RT. However, when changes in
the percentage of MHC type I isoforms were converted to effect sizes (ES), it appeared that low statistical power rather than
the absence of an effect accounted for the nonsignificant differences between CB and other groups (i.e. CB > RT ≈ ER ≈ C).
Significant differences existed in isoinertial strength among the trained athletes (i.e. CB > RT > ER ≈ C), while isometric
and isokinetic strength were not significantly different among any of the trained groups. However, the ES transformation of
data demonstrated that large differences existed between resistance-trained groups and ER for isometric and isokinetic strength
(i.e. CB ≈ RT > ER ≈ C). A statistically significant negative correlation (P < 0.001) was found between MHC type IIb isoforms and isoinertial strength index (r = − 0.68). The MHC type IIa proteins were positively related to all the strength measures considered (r = 0.51 – 0.61; P < 0.001). These data demonstrated different patterns of MHC isoform expression among the different groups of athletes and
it is suggested that these differences on occasion may affect the expression of strength.
Accepted: 24 September 1996 相似文献
12.
Roman Buckow Julius Semrau Qian Sui Jason Wan Kai Knoerzer 《Biotechnology progress》2012,28(5):1363-1375
A computational fluid dynamics (CFD) model describing the flow, electric field and temperature distribution of a laboratory‐scale pulsed electric field (PEF) treatment chamber with co‐field electrode configuration was developed. The predicted temperature increase was validated by means of integral temperature studies using thermocouples at the outlet of each flow cell for grape juice and salt solutions. Simulations of PEF treatments revealed intensity peaks of the electric field and laminar flow conditions in the treatment chamber causing local temperature hot spots near the chamber walls. Furthermore, thermal inactivation kinetics of lactoperoxidase (LPO) dissolved in simulated milk ultrafiltrate were determined with a glass capillary method at temperatures ranging from 65 to 80°C. Temperature dependence of first order inactivation rate constants was accurately described by the Arrhenius equation yielding an activation energy of 597.1 kJ mol?1. The thermal impact of different PEF processes on LPO activity was estimated by coupling the derived Arrhenius model with the CFD model and the predicted enzyme inactivation was compared to experimental measurements. Results indicated that LPO inactivation during combined PEF/thermal treatments was largely due to thermal effects, but 5–12% enzyme inactivation may be related to other electro‐chemical effects occurring during PEF treatments. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012 相似文献
13.
The knowledge of solid loss kinetics of foods during digestion is crucial for understanding the factors that constrain the
release of nutrients from the food matrix and their fate of digestion. The objective of this study was to investigate the
solid loss of carrots during simulated gastric digestion as affected by pH, temperature, viscosity of gastric fluids, mechanical
force present in stomach, and cooking. Cylindrical carrot samples were tested by static soaking method and using a model stomach
system. The weight retention, moisture, and loss of dry mass were determined. The results indicated that acid hydrolysis is
critical for an efficient mass transfer and carrot digestion. Internal resistance rather than external resistance is dominant
in the transfer of soluble solids from carrot to gastric fluid. Increase in viscosity of gastric fluid by adding 0.5% gum
(w/w) significantly increased the external resistance and decreased mass transfer rate of carrots in static soaking. When mechanical
force was not present, 61% of the solids in the raw carrot samples were released into gastric fluid after 4 h of static soaking
in simulated gastric juice. Mechanical force significantly increased solid loss by causing surface erosion. Boiling increased
the disintegration of carrot during digestion that may favor the loss of solids meanwhile reducing the amount of solids available
for loss in gastric juice. Weibull function was successfully used to describe the solid loss of carrot during simulated digestion.
The effective diffusion coefficients of solids were calculated using the Fick’s second law of diffusion for an infinite cylinder,
which are between 0.75 × 10−11 and 8.72 × 10−11 m2/s, depending on the pH of the gastric fluid. 相似文献
14.
Nicola D’Amelio Luca Fontanive Fulvio Uggeri Furio Suggi-Liverani Luciano Navarini 《Food biophysics》2009,4(4):321-330
Caffeine complexation by chlorogenic acid (3-caffeoylquinic acid, CAS Number [327-97-9]) in aqueous solution as well as caffeine–chlorogenate
complex in freshly prepared coffee brews have been investigated by high-resolution 1H-NMR. Caffeine and chlorogenic acid self-associations have also been studied and self-association constants have been determined
resorting to both classical isodesmic model and a recently introduced method of data analysis able to provide also the critical
aggregation concentration (cac). Furthermore, caffeine–chlorogenate association constant was measured. For the caffeine, the
average value of the self-association constant determined by isodesmic model (K
i = 7.6 ± 0.5 M−1) is in good agreement with the average value (K
a = 10 ± 1.8 M−1) determined with the method which permits the determination of the cac (8.43 ± 0.05 mM). Chlorogenic acid shows a slight
decreased tendency to aggregation with a lower average value of association constants (K
i = 2.8 ± 0.6 M−1; K
a = 3.4 ± 0.6 M−1) and a critical concentration equal to 24 ± 1 mM. The value of the association constant of the caffeine–chlorogenate complex
(30 ± 4 M−1) is compatible with previous studies and within the typical range of reported association constants for other caffeine–polyphenol
complexes. Structural features of the complex have also been investigated, and the complex conformation has been rediscussed.
Caffeine chemical shifts comparison (monomeric, complexed, coffee brews) clearly indicates a significant amount of caffeine
is complexed in beverage real system, being chlorogenate ions the main complexing agents. 相似文献
15.
Patrick S. Nadeau Scott G. Hinch Kimberly A. Hruska Lucas B. Pon David A. Patterson 《Environmental Biology of Fishes》2010,88(3):241-251
In 2005 and 2006, adult sockeye salmon (Oncorhynchus nerka) were captured en route to spawning grounds and placed in either a slow (∼ 0.1 m·s−1) or fast (∼0.4 m·s−1) water velocity treatment for 18 days in order to assess how migrational energy depletion during the final stages of maturation
affected physiological condition and survival. Fish in the fast treatment utilized more energy than the slow treatment in
2005 (0.91 MJ kg−1 vs. 0.43 MJ kg−1; P = 0.010), and 2006 (0.72 MJ kg−1 vs. 0.37 MJ kg−1; P = 0.021). Non-treatment fish captured upon arrival at spawning grounds showed energy levels intermediate to the two treatments
in 2005 and lower than both in 2006, suggesting that energy use during the treatments were within levels normally experienced
by this population. No differences in survival were found between treatments (P > 0.05), although females had lower survival than males in both years (both P < 0.01). After 18 days, surviving fish from the fast treatment showed signs of elevated physiological stress relative to
fish from the slow treatment. Specifically, plasma osmolality was lower in fast fish in 2005 (P < 0.001), as was plasma chloride in both years (both P < 0.02). In 2006, plasma lactate was higher (P = 0.014) in fast fish. Within the ranges of energetic depletion that were examined here, a more energy-intensive migration
can have a substantial influence on the physiological condition and stress of adult sockeye salmon, but not on survival. 相似文献
16.
The purpose of the following research was to improve the original Celsior solution in order to obtain a higher degree of stability
and effectiveness. The solution was modified by the addition of selected antioxidants such as vitamin C, cysteine, and fumaric
acid in the following concentrations: 0.1, 0.3, and 0.5 mmol/l. The solution’s stability was estimated using an accelerated
stability test based on changes in histidine concentrations in the solution using Pauly’s method for determining concentrations.
Elevated temperatures, the factor accelerating substances’ decomposition reaction rate, were used in the tests. The research
was conducted at four temperatures at intervals of 10°C: 60 ± 0.2°C, 70 ± 0.2°C, 80 ± 0.2°C, and 90 ± 0.2°C. It was stated
that the studied substances’ decomposition occurred in accordance with the equation for first-order reactions. The function
of the logarithmic concentration (log%C) over time was revealed to be rectilinear. This dependence was used to determine the kinetics of decomposition reaction rate
parameters (the rate constant of decomposition k, activation energy E
a, and frequency factor A). On the basis of these parameters, the stability of the modified solution was estimated at +5°C. The results obtained show
that the proposed antioxidants have a significant effect on lengthening the Celsior solution’s stability. The best results
were reached when combining two antioxidants: vitamin C and cysteine in 0.5 mmol/l concentrations. As a result, the Celsior
solution’s stability was lengthened from 22 to 299 days, which is 13.5 times. Vitamin C at a concentration of 0.5 mmol/l increased
the solution’s stability by 5.2 times (t
90 = 115 days), cysteine at a concentration of 0.5 mmol/l caused a 4.4 times stability increase (t
90 = 96 days), and fumaric acid at a concentration of 0.5 mmol/l extended the stability by 2.1 times (t
90 = 48 days) in relation to the original solution. 相似文献
17.
Gigartina skottsbergii is a commercially important carrageenan producer that has been suffering severe extraction pressure in Chile’s Magellan Region
and Cape Horn Archipelago since 1998. In order to create baseline information for its cultivation and repopulation, we studied
the effects of agricultural fertilizers on growth of G. skottsbergii early developmental stages. The culture media utilized were: a) seawater + Bayfoland, b) seawater + Superphosphate, c) seawater
+ Urea, d) seawater + Provasoli and e) seawater as a control. The culture conditions were: a) 12L:12D photoperiod; b) temperature
8 ± 1°C and c) irradiance at 45 μmol photons m−2 s−1. After 60 days, higher relative growth rates between treatments were observed; the treatments that included Bayfoland and
Provasoli showed greater growth (382 ± 55 and 378 ± 50 μm, respectively,) compared to Superphosphate (88 ± 16 μm), control
(78 ± 10 μm) and Urea (70 ± 11 μm) treatments, after 81 days. The Urea treatment and the control had inhibitory effects on
G. skottsbergii germlings growth and survival, as evidenced by progressive loss of pigmentation and death after 60 days. These results showed
that Bayfoland was an excellent alternative to develop cultures. 相似文献
18.
Ozkaya M Sahin M Cakal E Gisi K Bilge F Kilinc M 《Biological trace element research》2009,128(2):144-151
The present study was conducted to evaluate the serum selenium levels in first-degree relatives of diabetic patients (FDR)
according to controls. Insulin resistance, serum lipid levels, inflammation markers, and blood pressure were also studied
in these patients. Serum levels of selenium in FDR were significantly lower than control group (74.65 ± 5.9 vs 88.7 ± 8.7 μg/dl,
p < 0.0001). HsCRP, HOMA-IR, insulin, homocysteine levels were significantly higher in FDR according to the control group (1.32 ± 0.9
vs 0.63 ± 0.4 mg/dL, p < 0.0001; 2.07 ± 0.84 vs 1.51 ± 0.69, p < 0.0001; 9.26 ± 3.8 vs 6.8 ± 2.98 μU/MI, p < 0.0001; 15.7 ± 7.4 vs 11.5 ± 5.1 μmol/L, p < 0.0001, respectively). There was significant correlation between selenium levels and hsCRP (r = − 0.450, p < 0.0001). There was also weak significant correlation also between HOMA-IR and selenium levels (r = −0.227, p = 0.003). There was a correlation between systolic blood pressure and BMI (r = 0.365, p < 0.0001). But there was no correlation between selenium levels and blood pressure or other parameters. HsCRP, HOMA-IR, homocysteine
levels in individuals with selenium levels < 80 μg/L (n = 78) was significantly higher than hsCRP HOMA-IR, homocysteine levels in individuals with selenium levels ≥ 80 (n = 91; 1.23 ± 0.98 vs 0.81 ± 0.76 mg/dL, p < 0.003; 1.99 ± 0.88 vs 1.64 ± 0.74, p < 0.005; 15.0 ± 7.6 vs 12.9 ± 5.7 μmol/L, p < 0.049, respectively). Selenium deficiency may contribute to cardiovascular disease risk in FDR. 相似文献
19.
Valsartan orodispersible tablets have been developed at 40-mg dose, with the intention of facilitating administration to patients
experiencing problems with swallowing and hopefully, improving its poor oral bioavailability. Work started with selecting
drug compatible excipients depending on differential scanning calorimetric analysis. A 33 full factorial design was adopted for the optimization of the tablets prepared by freeze-drying technique. The effects of
the filler type, the binder type, and the binder concentration were studied. The different tablet formulas were characterized
for their physical properties, weight variation, disintegration time, surface properties, wetting properties, and in vitro dissolution. Amongst the prepared 27 tablet formulas, formula number 6 (consisting of 4:6 valsartan:mannitol and 2% pectin)
was selected to be tested in vivo. Oral bioavailability of two 40 mg valsartan orodispersible tablets was compared to the conventional commercial tablets after
administration of a single dose to four healthy volunteers. Valsartan was monitored in plasma by high-performance liquid chromatography.
The apparent rate of absorption of valsartan from the prepared tablets (C
max = 2.879 μg/ml, t
max = 1.08 h) was significantly higher than that of the conventional tablets (C
max = 1.471 μg/ml, t
max = 2.17 h), P ≤ 0.05. The relative bioavailability calculated as the ratio of mean total area under the plasma concentration–time curve
for the orodispersible tablets relative to the conventional ones was 135%. The results of the in vivo study revealed that valsartan orodispersible tablets would be advantageous with regards to improved patient compliance, rapid
onset of action, and increase in bioavailability. 相似文献
20.
Nitrifying granules cultivation in a sequencing batch reactor at a low organics-to-total nitrogen ratio in wastewater 总被引:4,自引:0,他引:4
It is possible to cultivate aerobic granular sludge at a low organic loading rate and organics-to-total nitrogen (COD/N) ratio
in wastewater in the reactor with typical geometry (height/diameter = 2.1, superficial air velocity = 6 mm/s). The noted nitrification
efficiency was very high (99%). At the highest applied ammonia load (0.3 ± 0.002 mg NH4+–N g total suspended solids (TSS)−1 day−1, COD/N = 1), the dominating oxidized form of nitrogen was nitrite. Despite a constant aeration in the reactor, denitrification
occurred in the structure of granules. Applied molecular techniques allowed the changes in the ammonia-oxidizing bacteria
(AOB) community in granular sludge to be tracked. The major factor influencing AOB number and species composition was ammonia
load. At the ammonia load of 0.3 ± 0.002 mg NH4+–N g TSS−1 day−1, a highly diverse AOB community covering bacteria belonging to both the Nitrosospira and Nitrosomonas genera accounted for ca. 40% of the total bacteria in the biomass. 相似文献