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121.
122.
H. M. Rüffer Liwei Wan A. Lübbert K. Schügerl 《Bioprocess and biosystems engineering》1994,11(4):153-159
Gas-residence time distribution (RTD) response curves measured in a 23 m high pilot plant airlift tower loop reactor, which consisted of a riser, a special downcomer construction and at the top of the riser a large head. The measurements were evaluated by means of a deterministic dispersion model, which yielded the following particular parameters for the riser, downcomer and the head: Gas-Bo numbers, gas-mean residence times, gas holdups, liquid velocities, gas and liquid circulation times as well as a fraction of the large and small bubbles in a model medium (water) and during cultivation of baker's yeast.List of Symbols
A
cross section
-
Bo
Bodenstein number
-
Bo
d
(= l
d
w
G,d
/D
d
)
-
Bo
h
(= l
h
w
G,h
/D
h
)
-
Bo
r
(= l
r
w
G,r
/D
r
)
-
D
longitudinal dispersion coefficient
-
E
gas holdup
-
E(t)
RTD-density function
-
L, l
length parameter
-
q
fraction of the gas throughput which is not recirculated (approximately equal to fraction of the large bubbles)
-
r
fraction of the throughput which is recirculated (approximately equal to the fraction of the small bubbles)
-
t
c
circulation time
-
t
cL
liquid circulation time
-
t
c,L
*
liquid circulation time calculated from the measured w
Ld
in the downcomer
-
V
h
hydrodynamical calculated gas-liquid volume
-
V
d
h
(=V
d+0.75/2 V
k
)
-
V
k
h
=(0.25V
k
)
-
V
r
h
= (V
r+0.75/2 V
k
)
-
V
L
liquid volume
-
V
G
dispersed gas volume
-
V
G
*
gas throughput at the gas distributor (given in m3/h) under standard conditions, 1 bar and 25°C)
-
V
G,d
*
gas throughput in downcomer (=V
G
*
)
-
V
G,h
*
gas throughput in head (=V
G
*
)
-
V
G,r
*
gas throughput in riser (V
G
*
(1+)
-
w
g
gas velocity
-
w
G,rel
relative gas velocity with respect to the liquid velocity w
L
-
w
G,d
gas velocity in the downcomer (=w
G,rel
–w
Ld
)
-
w
G,h
gas velocity in the head (=w
G,rel
) (since wLh = o)
-
w
G,r
gas velocity in the riser (=w
G,rel
+w
Lr
)
-
w
L
liquid velocity
-
w
L,d
liquid velocity in the downcomer measured with mass flow meter
-
w
sg
·w
SL
superficial gas and liquid velocities
-
first moment of the response curve
-
mean residence time
Indices
d
downcomer
-
G
gas phase
-
h
head
-
L
liquid phase
-
r
riser
-
h
hydrodynamic (upper position)
Dedicated to the 65th birthday of Proffessor Fritz Wagner.The authors gratefully acknowledge the financial support by the Krupp Industrietechnik, Grevenbroich and the support of Pleser Co, Darmstadt. H. M. Rüffer thanks the Verband der Chemischen Industrie for a Fond der Chemie scholarship, and W. Liwei thanks the government of Lower Saxony for a graduate scholarship. 相似文献
123.
模拟5000m中度缺氧时,大鼠右室功能显著加强,而左室功能加强不显著;左右心室肌原纤维Ca2+,Mg2+-ATP酶活性下降,肌球蛋白同功酶V2和V3百分含量增加,V1百分含量减少。8000m重度缺氧时,右室功能减弱,但无统计学意义,左室功能减弱有显著性;ATP酶活性和同功酶的变化超过5000m组。此外,右室ATP酶活性与PAP呈反比且有显著性,左室ATP酶活性与CASP虽也呈反比但无显著性;右室同功酶V3百分含量与PAP呈正比,左室同功酶V3百分含量与CASP不呈比例。上述结果表明,因短期突发严重缺氧引起的心肌供氧不足对左心室心肌的直接损伤作用大于右心室心肌。 相似文献
124.
锌指基因是一种造血调节基因,编码锌指结构蛋白,主要在髓细胞中表达,促进髓细胞分化,在急性早幼粒白血病维甲酸治疗中,促使病情缓解。本文报道了我们从基因分子上研究锌指基因作用中,探索并建立了单向聚合酶链反应(PCR)扩增特定单链DNA,直接测序的新方法。它能产生质和量均佳的单链DNA,无需纯化即可直接用于测序,使复杂的测序研究简便易行,可在2,3天内完成。这种单向PCR扩增特定单链DNA直接测序的方法,经对锌指基因的cDNA测序,得到验证。此法不仅适用于疾病研究中的DNA测序,还可制各单链DNA探针,更利于基因结构组成的研究。 相似文献
125.
126.
D. P. Chora L. Reddy S. K. Gupta L. Wan P. A. Mathieu R. L. Shoemaker J. S. Rhim 《In vitro cellular & developmental biology. Animal》1994,30(8):539-546
Summary Cystic fibrosis (CF) involves abnormalities in mucus production and secretion of the airway. Studies of the regulation of
airway mucin production and secretion has been difficult due to the lack of in vitro models of the airway epithelial cells
which express functional differentiation. Because the majority of the mucin in the airway is apparently produced by the submucosal
glands, we have focused our attention on the development of cell culture models of human airway submucosal glands. This report
describes the propagation of CF airway submucosal gland epithelial cells which continue to express mucin production. The CF
bronchus was obtained from a 31-yr-old patient who received a double lung transplant. The glands were dissected out and primary
cultures prepared by the explant/outgrowth procedure. The cells were immortalized by infection with Adl2-SV40 hybrid virus.
The cultures are maintained in serum-free keratinocyte basal medium supplemented with insulin (5μg/ml), hydrocortisone (0.5μg/ml), epidermal growth factor (10 ng/ml), bovine pituitary extract (25μg/ml), and antibiotics. Cultures were passaged using 0.125% trypsin in Ca+2 and Mg+2-free Hanks’, balanced salt solution. Polymerase chain reaction (PCR) analysis demonstrated that the cells were homozygous
for the ΔF508 mutation. Morphologic observations showed that the cells were epithelial and were interconnected by sparsely
distributed desmosomes. Their cytoplasm contained secretory-type structures including abundant Golgi, rough endoplasmic reticulum,
and secretory vesicles. Immunofluorescent studies determined that all cells were positive for cytokeratins, mucin glycoconjugates,
and cystic fibrosis transmembrane conductance regulator. The cultures secreted substantial amounts of mucin glycoproteins
and expressed the MUC-2 mucin gene. Patch clamp experiments revealed that the cells expressed defective Cl− channels which were not activated by Forskolin. 相似文献
127.
小麦初生叶接种条锈菌毒性生理小种(CY29)及其弱毒突变菌系(CY29-mut3)后,呈不亲和反应的寄主叶片可溶性蛋白质合成能力在接种后24h显著高于未接种对照,但其后逐渐降低,直至接近对照;而呈亲和性反应的寄主叶片可溶性蛋白质合成在侵染早期与对照相近,但与膜结合蛋白质在96h时大大高于对照。对接种叶中核糖体的密度梯度分析证实:呈不亲和反应寄主叶片游离多聚核糖体及亲和反应的寄主内与膜结合多聚核糖体均有特异性增加。上述结果表明寄主的抗病和感病反应均与蛋白质合成能力的变化有关。 相似文献
128.
A gene encoding 5'-phosphoribosyl-5-aminoimidazole-4-N-succinocarboxamide synthetase was identified in Streptococcus pneumoniae as a 708-bp segment of the genome encoding a 27,001-Da protein with strong similarity to known PurC proteins. The S. pneumoniae purC gene, found immediately adjacent to the competence induction genes, comAB, was cloned and sequenced. The predicted protein product of purC displayed substantial (> 40%) identity to the entire sequence of the PurC proteins of Bacillus subtilis and Escherichia coli. Function of the S. pneumoniae gene product was demonstrated by complementation of E. coli purC mutations. 相似文献
129.
130.
Ar^+,远红外激光,γ射线单一及复合处理水稻的诱变效果 总被引:1,自引:0,他引:1
用Ar~+、远红外两种激光和~(60)Co—r射线单一或复合处理两个籼稻品种的干种子,分析和比较了不同处理对水稻的当代生物学效应及处理二代的变异频率。结果表明,两种激光对当代的几个性状均表现为刺激效应,并有减轻,射线辐射损伤的作用,复合处理二代的变异频率和变异类型数明显高于相应的单一处理。说明复合处理是提高激光育种效果的有效方法。 相似文献