319 research outputs found
ẢNH HƯỞNG CỦA MÔI TRƯỜNG NUÔI CẤY LÊN SINH TRƯỞNG CỦA CALLUS CÂY GIẢO CỔ LAM (Gynostemma pentaphyllum (Thunb.) Makino) – MỘT CÂY DƯỢC LIỆU CÓ GIÁ TRỊ
Gynostemma pentaphyllum (Thunb.) Makino (Jiaogulan) is a traditional medicinal herb belonging to the Cucurbitaceae family. G. pentaphyllum grows widely in Southern China, Japan, Korea, and Vietnam. The essential bioactive components of Jiaogulan are saponin glycosides (gypenosides) and antioxidants. Jiaogulan exhibits bioactive activities such as anticancer, antioxidant, cholesterol-reducing agent, immunopotentiation, and others. In this study, the primary callus of Jiaogulan was used as a material to evaluate the influence of the culture medium on the induction and growth of secondary calli. The results reveal that the callus cultured on the MS medium supplemented with 2.0 mg/L kinetin and 0.5 mg/L indole-3-butyric acid has the best growth ability, high rate of secondary callus induction (100%), and good callus quality for suspension culture. The concentration of gypenoside and Rb1 in callus is 36.298 and 0.009 mg/g dry weight. The gypenoside concentration of callus is lower than that of leaves (65.58%) and almost similar to that of stems (92.38%) from natural samples. The suitable solvent for the extraction of gypenoside is methanol. The obtained callus will be used as material for cell suspension culture in further studies.Giảo cổ lam (Gynostemma pentaphyllum (Thunb.) Makino) là một cây thuốc dân gian thuộc họ Bầu bí. Cây phân bố rộng ở miền Nam Trung Quốc, Nhật Bản, Hàn Quốc và Việt Nam. Các thành phần có hoạt tính sinh học quan trọng của Giảo cổ làm là saponin glycoside (gypenoside) và các chất chống oxy hóa. Giảo cổ lam được sử dụng hỗ trợ chống ung thư, chống oxy hóa, giảm cholesterol, tăng cường miễn dịch và các tác dụng khác. Trong nghiên cứu này, callus sơ cấp của cây Giảo cổ lam được sử dụng làm nguyên liệu để đánh giá ảnh hưởng của môi trường nuôi cấy lên khả năng phát sinh và sinh trưởng của callus thứ cấp. Kết quả cho thấy, callus được nuôi cấy trên môi trường MS có bổ sung 2,0 mg/L kinetin và 0,5 mg/L indole-3-butyric acid sinh trưởng tốt nhất; tỷ lệ tạo callus thứ cấp cao (100%); callus đáp ứng được tiêu chuẩn để nuôi cấy huyền phù. Hàm lượng gypenoside và Rb1 trong callus là 36,298 và 0,009 mg/g chất khô; gypenoside thấp hơn trong lá (65,58%) và gần tương đương với mẫu thân (92,38%) của sản phẩm thu mua từ thị trường. Dung môi thích hợp để tách chiết gypenoside là methanol. Callus thu được sẽ được sử dụng làm nguyên liệu cho nuôi cấy tế bào huyền phù trong các nghiên cứu tiếp theo
Overseas Treatment of Latent Tuberculosis Infection in US-Bound Immigrants.
Seventy percent of tuberculosis (TB) cases in the United States occur among non-US-born persons; cases usually result from reactivation of latent TB infection (LTBI) likely acquired before the person's US arrival. We conducted a prospective study among US immigrant visa applicants undergoing the required overseas medical examination in Vietnam. Consenting applicants >15 years of age were offered an interferon-γ release assay (IGRA); those 12-14 years of age received an IGRA as part of the required examination. Eligible participants were offered LTBI treatment with 12 doses of weekly isoniazid and rifapentine. Of 5,311 immigrant visa applicants recruited, 2,438 (46%) consented to participate; 2,276 had an IGRA processed, and 484 (21%) tested positive. Among 452 participants eligible for treatment, 304 (67%) initiated treatment, and 268 (88%) completed treatment. We demonstrated that using the overseas medical examination to provide voluntary LTBI testing and treatment should be considered to advance US TB elimination efforts
Incidence of dengue and chikungunya viruses in mosquitoes and human patients in border provinces of Vietnam
Opposite-side flavour tagging of B mesons at the LHCb experiment
The calibration and performance of the oppositeside
flavour tagging algorithms used for the measurements
of time-dependent asymmetries at the LHCb experiment
are described. The algorithms have been developed using
simulated events and optimized and calibrated with
B
+ →J/ψK
+, B0 →J/ψK
∗0 and B0 →D
∗−
μ
+
νμ decay
modes with 0.37 fb−1 of data collected in pp collisions
at
√
s = 7 TeV during the 2011 physics run. The oppositeside
tagging power is determined in the B
+ → J/ψK
+
channel to be (2.10 ± 0.08 ± 0.24) %, where the first uncertainty
is statistical and the second is systematic
Measurement of the CP-violating phase phi_s in the decay Bs->J/psi phi
We present a measurement of the time-dependent CP-violating asymmetry in B_s
-> J/psi phi decays, using data collected with the LHCb detector at the LHC.
The decay time distribution of B_s -> J/psi phi is characterized by the decay
widths Gamma_H and Gamma_L of the heavy and light mass eigenstates of the
B_s-B_s-bar system and by a CP-violating phase phi_s. In a sample of about 8500
B_s -> J/psi phi events isolated from 0.37 fb^-1 of pp collisions at sqrt(s)=7
TeV we measure phi_s = 0.15 +/- 0.18 (stat) +/- 0.06 (syst) rad. We also find
an average B_s decay width Gamma_s == (Gamma_L + Gamma_H)/2 = 0.657 +/- 0.009
(stat) +/- 0.008 (syst) ps^-1 and a decay width difference Delta Gamma_s ==
Gamma_L - Gamma_H} = 0.123 +/- 0.029 (stat) +/- 0.011 (syst) ps^-1. Our
measurement is insensitive to the transformation (phi_s,DeltaGamma_s --> pi -
phi_s, - Delta Gamma_s.Comment: 9 pages, 3 figure
Observation of excited Lambda_b0 baryons
Using pp collision data corresponding to 1.0 fb-1 integrated luminosity
collected by the LHCb detector, two narrow states are observed in the
Lambda_b0pi+pi- spectrum with masses 5911.97 +- 0.12(stat) +- 0.02(syst) +-
0.66(Lambda_b0 mass) MeV/c^2 and 5919.77 +- 0.08(stat) +- 0.02(syst) +-
0.66(Lambda_b0 mass) MeV/c^2. The significances of the observations are 5.2 and
10.2 standard deviations, respectively. These states are interpreted as the
orbitally-excited Lambda_b0 baryons, Lambda_b*0(5912) and Lambda_b*0(5920).Comment: Replaced by version published in Phys. Rev. Lett, modified fit with
better mass resolution treatmen
Strong constraints on the rare decays Bs -> mu+ mu- and B0 -> mu+ mu-
A search for Bs -> mu+ mu- and B0 -> mu+ mu- decays is performed using 1.0
fb^-1 of pp collision data collected at \sqrt{s}=7 TeV with the LHCb experiment
at the Large Hadron Collider. For both decays the number of observed events is
consistent with expectation from background and Standard Model signal
predictions. Upper limits on the branching fractions are determined to be BR(Bs
-> mu+ mu-) mu+ mu-) < 1.0 (0.81) x 10^-9 at
95% (90%) confidence level.Comment: 2+6 pages; 4 figures; Accepted for publication in Physical Review
Letter
Measurement of the branching fraction
The branching fraction is measured in a data sample
corresponding to 0.41 of integrated luminosity collected with the LHCb
detector at the LHC. This channel is sensitive to the penguin contributions
affecting the sin2 measurement from The
time-integrated branching fraction is measured to be . This is the most precise measurement to
date
Measurements of the branching fractions of the decays B°s → D∓s K± and B°s → D¯sπ+
The decay mode B°s → D∓s K± allows for one of the theoretically cleanest measurements of the CKM angle γ through the study of time-dependent CP violation. This paper reports a measurement of its branching fraction relative to the Cabibbo-favoured mode B°s → D¯sπ+ based on a data sample corresponding to 0.37 fb¯¹ of proton-proton collisions at √s = 7TeV collected in 2011 with the LHCb detector. In addition, the ratio of B meson production fractions fs/fd, determined from semileptonic decays, together with the known branching fraction of the control channel B°s → D¯sπ+ is used to perform an absolute measurement of the branching fractions: B(B°s → D¯sπ+) = (2.95 ± 0.05 ± 0.17 -0.22 +0.18) × 10¯³ ; B(B°s → D∓s K±) = (1.90 ± 0.12 ± 0.13 -0.14 +0.12) × 10¯4 ; where the first uncertainty is statistical, the second the experimental systematic uncertainty, and the third the uncertainty due to f s/f
Measurement of the CP-violating phase \phi s in Bs->J/\psi\pi+\pi- decays
Measurement of the mixing-induced CP-violating phase phi_s in Bs decays is of
prime importance in probing new physics. Here 7421 +/- 105 signal events from
the dominantly CP-odd final state J/\psi pi+ pi- are selected in 1/fb of pp
collision data collected at sqrt{s} = 7 TeV with the LHCb detector. A
time-dependent fit to the data yields a value of
phi_s=-0.019^{+0.173+0.004}_{-0.174-0.003} rad, consistent with the Standard
Model expectation. No evidence of direct CP violation is found.Comment: 15 pages, 10 figures; minor revisions on May 23, 201
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