共查询到20条相似文献,搜索用时 15 毫秒
1.
This study investigates five designed micro‐textured surfaces and their effects on barnacle fouling and hydrodynamic drag. Three of the micro‐textures were developed in the present study and evaluated together with two commercial riblet films. All micro‐structures were arranged as longitudinal grooves with different profile depths, widths and angles of inclination. In field tests the recruitment of the barnacle Balanus improvisus on micro‐textured surfaces and smooth controls was evaluated. All micro‐textured surfaces reduced recruitment, and the most efficient texture reduced recruitment by 98%. For some micro‐textures the reduction of recruitment declined as settlement intensity increased. In a correlative analysis, the trigonometric inclination of the micro‐structures explained most of the recruitment reduction. The steepest angle of inclination caused a massive reduction in barnacle settlement. Surface micro‐structures may affect the boundary‐layer flow and the hydrodynamic drag (skin friction) of the surface. The skin friction was empirically measured in a flow channel using a sub‐set of the tested micro‐textures. The measurements of skin friction showed that the orientation of the microstructures is important, with a minimum friction when the grooves are parallel to the flow. For one of the micro‐textures the skin friction was ca 10% lower compared to a hydraulically smooth surface. It is concluded that, depending on the flow speed, micro‐textures will not significantly increase skin friction when arranged parallel to the flow, even at moderate protrusion through the viscous sub‐layer. 相似文献
2.
The ultradian rhythm of the lateral leaflets ofDesmodium motorium}(Houtt.) Merril. was recorded with a picture analysis method using a video camera and a computer. The periods are in the minute
range and depend strongly on temperature.
The phosphatidyl inositol signal chain might be involved in the ultradian rhythm of the lateral leaflet movement of
Desmodium motorium:Myoinositol shortens the period length and reduces the known period lengthening effect of lithium ions. Neomycin, which inhibits
the hydrolysis of phosphatidylinositol-4,5 -biphosphate to inositol-4-phosphate and diacylglycerin, lengthens the period of
the rhythm at low concentrations (0.2 mM). Higher concentrations shorten the period, perhaps by activating G protein. Mastoparan,
which activates G protein, shortens period likewise. The G protein agonists fluorid ion and ethanol are toxic for the lateral
leaflets and could therefore not be used to test the involvement of G protein.
The intracellular Ca
2+
antagonist 3,4,5-trinietlioxybeiizoic acid 8-(diethylamino)octylester lengthens the period of the rhythm. This indicates,
that release of Cas
2+
from intracellular stores is important for the lateral leaflet movement rhythm. 相似文献
3.
Molecular dynamics simulations of ion separation in nano-channel water flows using an electric field
Filippos Sofos Theodoros E. Karakasidis Dimitrios Spetsiotis 《Molecular simulation》2013,39(17):1395-1402
ABSTRACTRemoval of undesired substances from water is a field of investigation recently focused at the nanoscale. Towards this direction, molecular dynamics simulations are conducted in this paper to investigate unwanted ion removal in nanochannel flows. The simulation method incorporates a Poiseuille-like water/ion flow system at the nanoscale where an electric field, of various magnitudes in the range of E?=?0.25–1.5?V/Å, is applied perpendicular to the flow, leading anions and cations close to the wall regions, similar to the Capacitive De-Ionization method. The time needed for ions to reach equilibrium, i.e. to flow in the region near the walls while pure water flows in the channel interior, is t?=?1.3?ns when E?=?1.5?V/Å and t?=?4.0?ns when E?=?0.25?V/Å, showing a dependency on the value of the electric field. Calculations on density, velocity, and temperature values report on fluid properties to be used in the proposed desalination configuration and could act as a basis to guide novel technological applications and extend to higher scales. 相似文献
4.
Tony M. Johnson A. S. Rishi Pritilata Nayak Soumitra K. Sen 《Journal of biosciences》1996,21(5):673-685
Damage caused to rice production by coleopteran insects like rice weevil (Sitophilus oryzae), a stored grain insect pest and rice hispa (Dicladispa armigera), a pest of the growing plant is quite high. In order to combat the damage, generation of insect resistant transgenic rice
plant was considered desirable. CryIIIA endotoxin ofBacillus thuringiensis var.tenebrionis, a 65 kDa protein toxic to coleopteran insects, figured as the candidate gene product. Thus, the cryIIIA gene was isolated
from a local isolate ofBacillus thuringiensis var.tenebrionis. The gene was tailored at the N-terminal end to its minimal size by using a synthetic ATG codon which replaced the first
codon next to ATG of threonine to proline. This modification did not affect the functional property of the gene product. A
chimeric construct of the modifiedcryIIIA gene was developed containing CaMV35S promoter andnos terminator for plant expression. The expressibility of thecryIIIA gene inindica rice was judged through test for transient expression in indica rice protoplasts. 相似文献
5.
This paper presents the results of an investigation on the distribution of210Po in Mutharasanallur pond ecosystem. It has been demonstrated that210Po is non-uniformly distributed within the ecosystem. The results of the study show a dissolved210Po concentration in pond water of 1 4mBq 1−1. The sediment samplso recorded a210Po activity of 59 9 Bq kg−1. The aquatic organisms showed differential accumulation of the radionuclide with enhanced bioaccumulation in soft tissues
and muscle. The210Po activity in the biota fell within the range of 1·2–53 3 Bq kg−1 (wet wt). The bivalve mussel,Lamellidens marginalis was identified to accumulate higher concentration of210Poin soft tissues, suggesting that these organisms could serve as a bio-monitor of210Po radionuclide in a freshwater system. The concentration factors of210Po for the biotic components ranged from ∼102–∼104. Analyses of the results indicate that prawn and fish represent an important source of supply of210Po to humans via dietary intake. Results of210Po activity in the abiotic and biotic components of the pond ecosystem were higher when compared with those of Cauvery river
system, the primary water source of the pond. 相似文献
6.
Subramony Mahadevan 《Journal of biosciences》1997,22(4):505-513
The product of the
bglG
gene of Escherichia
coli
was among the first bacterial antiterminators to be identified and characterized. Since the elucidation ten years ago of its
role in the regulation of the
bgl
operon
of E. coli,a large number of homologies have been discovered in both Gram-positive and Gram-negative bacteria. Often the homologues of
BglG in other organisms are also involved in regulating β-glucoside utilization. Surprisingly, in many cases, they mediate
antitermination to regulate a variety of other catabolic functions. Because of the high degree of conservation of the
cis-acting regulatory elements, antiterminators from one organism can function in another. Generally the antiterminator protein
itself is negatively regulated by phosphorylation by a component of the phosphotransferase system. This family of proteins
thus represents a highly evolved regulatory system that is conserved across evolutionarily distant genuses. 相似文献
7.
The intranasal route is one of the main routes of Mycobacterium leprae infection and there is paucity of information regarding
the mode of spread of the pattern. The adherence of
M.leprae to the nasal mucosa, its trapping within the sinuses of the head, and its fate after entry into the host was studied
using mouse model. A comparison of the adherence profile of
M. leprae
and
Mycobacterium tuberculosis
showed that while larger numbers of
M. tuberculosis
were demonstrated within lungs, greater numbers of
M.leprae were present within the sinuses of the head. Adherence of
M.leprae to the nasal mucosa was dependent on surface integrity since opsonization and heat killing resulted in decreased numbers
of
M.leprae in the nasal sinuses and a greater amount entering the lungs. The adherence appeared to the independent of the viability
of the bacilli, as similar numbers of formalin-fixed, rifampicin-treated and viable
M.leprae entered the lungs in the initial stages. However the numbers of rifampicin-treated
M. leprae
in the nasal sinuses were 12-fold lower than the numbers of viable
M.leprae. These results indicated that both viability and surface integrity were important in the entry of
M.leprae and it’s consequent dissemination. 相似文献
8.
S. A. Ranade Anil Kumar Mamta Goswami Nuzhat Farooqui P. V. Sane 《Journal of biosciences》1997,22(4):457-464
Amaranths are an important group of plants and include grain, vegetable and ornamental types. Despite the economic importance
of the amaranths, there is very little information available about the extent and nature of genetic diversity present in the
genus
Amaranthus
at molecular level. We now report the randomly amplified polymorphic DNA (RAPD) profiles of different species of
Amaranthus
as well as different accessions of the species. These RAPD analyses have been carried out using 65 arbitrary sequence decamer
primers. From the RAPD data, an UPGMA dendrogram illustrating the inter-as well as intra-species relationships has been computed.
The putative hybrid origin of A.dubious
from
A. hybridus
and
A. spinosus
is also ruled out by the RAPD data. The trends of species relationships amongst the amaranths determined by RAPDs is consistent
with their cytogenetic and evolutionary relationships that have already been determined.
NBRI Communication No:464 (N.S.). 相似文献
9.
Streptomyces fradiae
produces several extracellular proteases and many of these are inducible. An 8.8 kb DNA fragment of
Streptomyces fradiae
cloned on pIJ699 caused increased protease activity in
Streptomyces lividans.Clones carrying this recombinant plasmid showed a significant delay in sporulation. A protein of 18 kDa was purified from
the extracellular proteins secreted by the host carrying the recombinant plasmid. Further characterization showed that this
protease is a metalloprotease. 相似文献
10.
S. Mohan Jain 《Journal of biosciences》1997,22(5):585-592
Begonia
x
elatior
plantlets which regenerated from leaf disk callus showed variations in plant morphology, number of flowers per plant, and
flower size. Variations in flowering period, number of flowers per plant, and flower morphology were observed in
Saintpaulia ionantha
L. plants directly regenerated from leaf disk explants. The cytokinins, benzylaminopurine and zeatin, tested in the culture
medium did not affect the basic plant characteristics including flower colour which remained stable in both species. Micropropagation
of selected somaclones having the desirable trait of high number of flowers per plant was stable in the MV2 and MV3 generations. 相似文献
11.
The tachykinins are a family of gastrointestinal peptides comprising eight members: substance P, neurokinin A, neurokinin
B, eledoisin, physalemin, uperolein, kassinin and phyllomedusin. Consensus dynamics was carried out on an
ensemble
of seven tachykinins to determine the binding conformation of the common C-terminal fragment: Phe-X-Gly-Leu-Met-NH
2
,the ’message sequence’ of tachykinins. Three binding modes for the C-terminal pentapeptide were determined. The first binding
conformation is folded due to an intramolecular H-bond between the NH of the variable residue (X) and CO of Met. Other features
include γ-bends at both the variable amino acid (X) and at Gly. The global minimum of the simulation has this conformation
for the C-terminal pentapeptide. The other two binding modes have slightly higher energies. The second is chiefly characterized
by a β-turn around the segment X-Gly-Leu-Met, with additional β-bends at the variable amino acid (X) and Met. The final binding
conformation is composed of β-bends around the variable amino acid (X) and Leu, and a ’pseudo’ γ-bend at the terminal Met.
This paper was presented at the MBU Silver Jubilee Symposium on Structural Biology and 24th Annual Meeting of the Indian Biophysical
Society held at Indian Institute of Science, Bangalore, Dec. 9–12, 1996. 相似文献
12.
Employing the superimposition technique of electron-microscopic immunocytochemistry ultrastructural heterogeneity of the mammotropes
in the pituitary gland of the European ferret,Mustela putorius furo,was studied. On the basis of the size of their secretory granules, the mammotropes were classified into three subtypes, type-I,
type-II and type-Ill, which may correspond to different developmental or physiological states of a single cell type. Simultaneous
study of mammotropes and somatotropes in several pairs of serial semithin sections demonstrated the occasional occurrence
of bihormonal somatomammotropes /mammosomatotropes which may represent a transitional stage of the progenitor stem-somatotrope
during its differentiation into mammotrope; alternatively it may be a functional intermediate during the cross-transformation
of somatotrope into mammotrope or
vice versa. 相似文献
13.
The growth of the follicle and oocyte in the Indian gerbil (Tatera indica) was a continuous process. The relationship between
follicle and oocyte or its nucleus was log linear, represented by the equation log
Y =a +b logX.A linear relationship (Y =a +bX)existed between the oocyte and its nucleus. The number of stages I and II follicles varied significantly during the oestrous
cycle. Maximum percentage of stage I follicles was observed during oestrus and metoestrus, while stage II follicles were abundant
during dioestrus, metoestrus and pro-oestrus. These follicles were significantly more in number than other types of the follicles.
The occurrence of comparatively larger follicles during pro-oestrus and the presence of newly formed corpora lutea at oestrus,
indicated ovulation in the early oestrus. 相似文献
14.
Gastrimargus africanus orientalis,an acridid grasshopper has revealed the existence of karyotypic mosaicism in the male germ line cells of a few individuals
with 2
n
= 23, 19, 21, 25 and 27 chromosomes. Details of this chromosomal instability are presented in this paper.
We dedicate this paper to our teacher Prof. L Siddaveere Gowda on the eve of his 60th birthday. 相似文献
15.
V. Kothekar 《Journal of biosciences》1996,21(5):577-597
We present here results of molecular dynamics (MD) simulations on hydrated bilayers of 40 molecules of 1-2-dimyristoyl-sn-glycero-3-phosphatidyl
choline (DMPC) in liquid crystalline (Lα) phase using two different models (i) with same (A) conformation for all DMPC molecules,
(ii) with alternate rows having different (A and B reported in crystallographic studies on DMPC) conformations. The bilayers
were hydrated using 776 and 1064 water molecules. Simulations have been carried out at 310K with AMBER 4.0 program, using
united atom force field for 200 pico seconds (ps) after equilibration. During heating and equilibration constant pressure
temperature (PT) conditions were maintained while in simulation of equillibrated bilayers constant volume temperature (VT)
conditions were used. Subaveraged atomic coordinates were used to calculate geometric parameters of lipid molecules and lipid
water interaction. Our results show larger flexibility of polar head group and glycerol region in Lα phase compared to gel
or non-hydrated bilayers. Chain disorder was more towards end. Sn-2 chains were more disordered. Use of two types of starting
conformations increased disorder. Trans fraction of chain torsional angle was higher in non-hydrated bilayer. However it was
more disordered due to ‘swing’ movement of chains because of distortion in torsional angles α2 and 03 due to absence of water
molecules. Trans fraction of the chains, order parameter and water penetration showed general agreement with the available
experimental results. On the whole MD technique was found to be quite useful for depicting microscopic behaviour of liquid
crystalline system and correlating the same with macroscopic changes observed experimentally. 相似文献
16.
Evolutionary conservation of angiosperm flower development at the molecular and genetic levels 总被引:7,自引:0,他引:7
John L. Bowman 《Journal of biosciences》1997,22(4):515-527
Flowers consist primarily of four basic organ types whose relative positions are universally conserved within the angiosperms.
A model has been proposed to explain how a small number of regulatory genes, acting alone and in combination, specify floral
organ identity. This model, known widely as the ABC model of flower development, is based on molecular generic experiments
in two model organisms,Arabidopsis thaliana
and
Antirrhinum majus.Both of these species are considered to be eudicots, a clade within the angiosperms with a relatively conserved floral architecture.
In this review, the application of the ABC model derived from studies of these typical eudicot species is considered with
respect to angiosperms whose floral structure deviates from that of the eudicots. It is concluded that the model is universally
applicable to the angiosperms as a whole, and the enormous diversity seen among angiosperms flowers is due to genetic pathways
that are downstream, or independent, of the genetic programme that specifies floral organ identity. 相似文献
17.
Thehrsω or the 93D heat shock locus ofDrosophila melanogaster, which does not code for any protein, has an important role in development since nullosomy of this locus in transheterozygotes
for two overlapping deficiencies, viz.,Df(3R)
e
Gp4 (eGp4) andDf(3R)GC14 (GC14), is known to cause a high (∼ 80%) mortality with the small number of escapee nullosomic flies being sterile, weak and surviving
for only a few days. We now show that a majority of thehsrω-nulosomics die as embryo and that the 20% escapee embryos develop slower compared to their sibs carrying either one or two
copies of thehsrω locus but after hatching survive to pupal/imago stage. Most interestingly, we further show that when onehsp83 mutant allele (hsp83
e4A) is introduced ineGp4/GC14 trans-heterozygotes, practically none of thehsrω-nullosomic embryos develop beyond the 1st instar larval stage. The specificity of this interaction betweenhsp83 andhsrω genes was further confirmed by examining the effect of thehsp83 mutant allele on other mutations in the 93D cytogenetic region. Therefore, we conclude that thehsp83 mutation acts as a dominant enhancer of the lethality associated with nullosomy for thehsrω gene. The observed genetic interaction between these two members of the heat shock gene family during normal embryonic development
ofDrosophila reveals novel aspects of their biological functions. 相似文献
18.
The cell wall protein peptidoglycan complex (CW-PPC) of
Mycobacterium tuberculosis H37Ra was isolated through sequential extraction of lipids, carbohydrates and soluble proteins. CW-PPC emulsified in FIA was
found to induce significant protection in mice against challenge with LD50 dose ofM. tuberculosis H37Rv. To identify the immunoprotective components of CW-PPC, the proteins in avid association with peptidogican were dissociated
by chemical treatment with trifluoromethanesulthonic acid (CF3CO3H): anisole (2:1). Immunoreactivity of total (CW-Pr) as well as its component proteins i.e., 71, 60 and 45 kDa proteins of
cell wall was studied in animals immunized with CW-Pr-FIA. The 71 kDa protein was found to be most immunoreactive giving higher
T-cell sensitization and humoral responses. Further, immunization of mice with 71 kDa-FIA demonstrated enhanced T- and B-
cell responses. Mice immunized with 71 kDa-FIA gave significantly higher protection (P ≤ 0.05) against intravenous challenge
with LD50 dose ofM. tuberculosis H37Rv, than BCG immunized animals. The results indicate the potential of 71 kDa cell wall protein as a suitable candidate for
Cthe subunit vaccine. 相似文献
19.
Determination and diagnostic value of CA9 mRNA in peripheral blood of patients with oral leukoplakia
Manuel Torres López Cintia Chamorro Petronacci Francisco Barros Angueira Pilar Gándara Vila Alejandro Lorenzo Pouso 《Journal of enzyme inhibition and medicinal chemistry》2018,33(1):951-955
Background: Oral leukoplakia is one of the most common oral premalignant disorder. The classical evaluation through tissue biopsy is not always valid to evaluate the risk of malignization.Material and methods: RT-qPCR was performed on 47 blood samples (21 patients with leukoplakia, 2 with oral squamous cell carcinoma (OSCC), and 24 healthy patients) and on 11 tissue samples (3 leukoplakia, 4 OSCC, and 4 samples of healthy tissue).Results: There are significant differences in expression between the different groups (F?=?4.057, p?=?.006). The Duncan post hoc test shows that the only group that differentiates is the tumour tissue. Using Wilcoxon test, different covariables of patients with leukoplakia were analysed with respect to the group of healthy patients and no significant differences were observed.Conclusions: The diagnostic route through liquid biopsy has not been conclusive in this study, but there are significant differences in the levels analysed in the different tissue samples. 相似文献
20.
J. Marañón Di Leo 《Molecular simulation》2013,39(4):280-286
Using periodic boundary conditions and external electric potential field, we have simulated an ion current flow through a flexible nanopore using cations and an explicit extended simple point charge (SPC/E) water with molecular dynamics simulation. The simulation voltages range goes beyond the usual ionic channel measurements ( ± 1 V) and yields useful information about density profiles, current density distribution and current–voltage (I–V) characteristics. 相似文献