响应面试验优化链霉菌Z331-A的发酵条件

链霉菌Z331-A是一株活性很好的生防菌,为提高链霉菌Z331-A发酵液的抑菌效果,对其发酵条件进行优化。 该研究在单因 子试验基础上,利用Plackett-Burman设计筛选出影响菌株Z331-A发酵的3个关键因子为发酵时间、接种量、摇瓶转速;然后通过响应 面试验确定最佳发酵条件。 结果表明,链霉菌Z331-A最佳发酵条件为发酵时间7.2 d,接种量5.7%,摇瓶转速210 r/min。 在此最佳发酵 条件下,抑菌圈直径可达24.30 mm,比未优化前（19.20 mm）提高了26.56%。 表明响应面法优化的链霉菌Z331-A发酵工艺效果良好。     

Tunable superconducting nanoinductors

We characterize inductors fabricated from ultra-thin, approximately 100 nm wide strips of niobium (Nb) and niobium nitride (NbN). These nanowires have a large kinetic inductance in the superconducting state. The kinetic inductance scales linearly with the nanowire length, with a typical value of 1 nH μm(-1) for NbN and 44 pH μm(-1) for Nb at a temperature of 2.5 K. We measure the temperature and current dependence of the kinetic inductance and compare our results to theoretical predictions. We also simulate the self-resonant frequencies of these nanowires in a compact meander geometry. These nanowire inductive elements have applications in a variety of microwave frequency superconducting circuits.     

LC50 estimates and their confidence intervals derived for tests with only one concentration with partial effect

Linear approximation fails to determine the likelihood based confidence interval for the LC₅₀ parameter in a toxicity experiment with only one concentration causing partial mortality. An equation for this confidence interval is derived given a log-logistic concentration response relation. A table of the 95 and 99% confidence intervals is given for the case that partial survival occurs only at one concentration, under the condition that a fixed number of animals is used at each test concentration and a constant ratio is used between the test concentrations.     

The projection diagram

We describe a diagram, named the projection diagram (PD), that can be used for the interpretation of fringe projection operations in a similar way as the Holodiagram is used in holography and other branches in optics. It is obtained as a Moiré pattern between two spoke targets that mimic central projections, the same as those in a projection and observation system or two projection systems. N. Abramson [Academic, London (1981)] has already proposed its use in systems with two observation points (i.e., stereoscopic observation). By using this PD, several interesting features dealing with fringe projection are highlighted. Information on the sensitivity vector and the geometry of the contouring surfaces can be straightforwardly obtained in a graphical way. The effect of defocusing can also be included in the diagram.     

Holodiagrams in birefringent media

The modifications to the holodiagram concept to describe free propagation (the extraordinary ray) inside birefringent materials are described. Holodiagrams are graphs showing the loci where the sum or the difference in the optical path from a generic point to two foci is the same. The holodiagrams obtained in this way give the shape of the surfaces that satisfy Fermat's principle, conjugate by reflection of one focus into the other, and represent the interference fringes obtained if both points are coherent sources. The reflection law in birefringent media is investigated in relation to this diagram. One direction for the optical axis is considered: parallel to the line joining the source and the observation point. Quartz-type and calcite-type crystals are studied.     

Randomized trial of conservative laparoscopic treatment and methotrexate administration in ectopic pregnancy and subsequent fertility

Methotrexate treatment was compared to laparoscopic salpingotomy for conservative management of ectopic pregnancy in a prospective randomized study. One hundred patients were randomized into two groups using random numbers. Inclusion criteria were an ectopic pregnancy visualized by ultrasound with a pre-therapeutic score <13 as assessed by the following six criteria, graded from 1 to 3: gestational age, human chorionic gonadotrophin (HCG) concentration, progesterone concentration, abdominal pain, haemoperitoneal volume and diameter of the haematosalpinx. The treatments were either 1 mg/kg of methotrexate injected transvaginally into the ectopic pregnancy without anaesthesia or administered i.m. when the pregnancy could not safely or easily be punctured (group 1), or laparoscopic salpingotomy (group 2). Success was defined as the return to normal (<10 mIU/ml) of HCG concentrations. Treatment was successful for 45 of 51 patients in group 1 (88.2%) and 47 of 49 in group 2 (95.9%). Medical treatment was significantly (P < 0.05) associated with shorter postoperative stay (24 compared with 46 h), but HCG returned to normal more quickly after laparoscopic treatment (13 compared with 29 days). Spontaneous reproductive performance was similar in both groups, but overall intrauterine pregnancy was higher, and repeat ectopic pregnancy lower, after methotrexate treatment. In selected cases of ectopic pregnancy, with a pre-therapeutic score <13, methotrexate treatment appeared as safe and efficient as conservative treatment by laparoscopy and was associated with improved subsequent fertility.     

Inequality as a way of life: education and social class in Latin America

This article presents a regional analysis of educational inequalities in Latin America, drawing on a variety of sources at the national and cross-national levels. It traces how inequalities in education tend to manifest themselves and which population groups tend to be the most affected. The persistence of inequalities is a curious social phenomenon that operates between the interstices of the political promise and pervasive social acceptance that schooling serves to promote social mobility, and the tangible evidence that there are serious gaps in the schooling of the poor, rural children, ethnic minorities, and women. The analysis of Latin America is particularly illustrative because it suggests that educational systems may grow more unequal over time, especially as private schools function as outlets for those seeking to escape the poor quality of public schools and as global norms disseminate the idea of education as simply another tradeable commodity.     

In vitro activity on human gut bacteria of murta leaf extracts (Ugni molinae turcz.), a native plant from southern Chile

Despite the fact that murta infusions have been used to treat gut/urinary infections by native Chileans for centuries, the mechanisms promoting such effects still remain unclear. As a first attempt to unravel these mechanisms, human fecal samples were incubated in a medium containing water extract of murta leaves (ML) and the growth of different bacterial groups was evaluated. Control incubations were made in media containing fructooligosaccharides (FOS) and glucose as a carbon source. Phenolic compounds in the ML extract, likely promoters of bioactivity, were identified by HPLC-DAD-MS(n) . Concentrations (log(10) CFU/mL) of bifidobacteria and lactobacilli in media containing the extract and FOS were 7.33 ± 0.05/4.95 ± 0.20 and 6.44 ± 0.22/6.05 ± 0.06, respectively. Clostridia, anaerobes and Enterobacteriaceae grew to a similar extent in media containing murta extract and FOS. In vitro tests (disk diffusion) showed that Gram-positive (Bacillus and Paenibacillaceae) and Gram-negative (Enterobacteriaceae) bacteria isolated from fecal samples were sensitive to both water and 50/50 ethanol/water extracts of ML (28.4 μg gallic acid equivalents). At this concentration, the antimicrobial activity of ML extracts was significantly (P < 0.05) lower than that of penicillin (10 U), whereas the difference between activity of ML extracts and gentamicine (10 μg) was no significant (P > 0.05). No evidence of dependency between the antimicrobial activity of ML extracts and the enzymatic capability of the sensitive strains was found.