Dynamical Mass of the Exoplanet Host Star HR 8799

HR 8799 is a young A5/F0 star hosting four directly imaged giant planets at wide separations (∼16–78 au), which are undergoing orbital motion and have been continuously monitored with adaptive optics imaging since their discovery over a decade ago. We present a dynamical mass of HR 8799 using 130 epochs of relative astrometry of its planets, which include both published measurements and new medium-band 3.1 μm observations that we acquired with NIRC2 at Keck Observatory. For the purpose of measuring the host-star mass, each orbiting planet is treated as a massless particle and is fit with a Keplerian orbit using Markov chain Monte Carlo. We then use a Bayesian framework to combine each independent total mass measurement into a cumulative dynamical mass using all four planets. The dynamical mass of HR 8799 is 1.47 − 0.17 + 0.12 M ⊙ assuming a uniform stellar mass prior, or 1.46 − 0.15 + 0.11 M ⊙ with a weakly informative prior based on spectroscopy. There is a strong covariance between the planets’ eccentricities and the total system mass; when the constraint is limited to low-eccentricity solutions of e < 0.1, which are motivated by dynamical stability, our mass measurement improves to 1.43 − 0.07 + 0.06 M ⊙. Our dynamical mass and other fundamental measured parameters of HR 8799 together with Modules for Experiments in Stellar Astrophysics Isochrones and Stellar Tracks grids yields a bulk metallicity most consistent with [Fe/H] ∼ −0.25–0.00 dex and an age of 10–23 Myr for the system. This implies hot-start masses of 2.7–4.9 M Jup for HR 8799 b and 4.1–7.0 M Jup for HR 8799 c, d, and e, assuming they formed at the same time as the host star.

General Taq PCR Master Mix -- CHEM 384/584 v2

SapphireAmp Fast PCR Master Mix contains a hot start PCR enzyme, optimized buffer, dNTP mixture, gel loading dye (blue), and a density reagent as a 2X premix. SapphireAmp Fast PCR Master Mix is optimized for fast PCR and offers a rapid extension rate (10 sec. per kb). The inclusion of blue dye and a density reagent allows direct loading of PCR products on an agarose gel for electrophoresis. The master mix format simplifies workflows and sample handling; simply add primers, template, and water and then begin PCR. SapphireAmp Fast PCR Master Mix is ideal for fast colony PCR screening. Fast colony PCR amplification of a 5 kb insert can be completed in approximately 1 hr 15 min. Furthermore, it is possible to amplify fragments up to 6 kb from genomic DNA templates.

A simple and general approach to control the activity of DNA processing enzymes

DNA processing enzymes, such as DNA polymerases and endonucleases, have found many applications in biotechnology, molecular diagnostics, and synthetic biology, among others. The development of enzymes with controllable activity, such as hot-start or light-activatable versions, has boosted their applications and improved the sensitivity and specificity of the existing ones. However, current approaches to produce controllable enzymes are experimentally demanding to develop and case specific. Here, we introduce a simple and general method to design light-start DNA processing enzymes. In order to prove its versatility, we applied our method to three DNA polymerases commonly used in biotechnology, including the Phi29 (mesophilic), Taq and Pfu polymerases, and one restriction enzyme. Light-start enzymes showed suppressed polymerase, exonuclease and endonuclease activity until they were re-activated by an UV pulse. Finally, we applied our enzymes to common molecular biology assays, and showed comparable performance to commercial hot-start enzymes.

Improved SARS-CoV-2 PCR detection and genotyping with double-bubble primers

A new approach for improved RT-PCR is described. It is based on primers designed to form controlled stem–loop and homodimer configurations, hence the name ‘double-bubble’ primers. The primers contain three main regions for efficient RT-PCR: a 3′ short overhang to allow reverse transcription, a stem region for hot start and a template-specific region for PCR amplification. As proof of principle, GAPDH, SARS-CoV-2 synthetic RNA and SARS-CoV-2 virus-positive nasopharyngeal swabs were used as templates. Additionally, these primers were used to positively confirm the N501Y mutation from nasopharyngeal swabs. Evidence is presented that the double-bubble primers offer fast, specific, robust and cost-effective improvement in RT-PCR amplification for detection of gene expression in general and for diagnostic detection and genotyping of SARS-CoV-2 in particular.

Generation and Characterization of Monoclonal Antibodies Against Tth DNA Polymerase and its Application to Hot-Start PCR

Background: As a heat-resistant polymerase, Thermus thermophilus (Tth) DNA polymerase can be widely used in Polymerase Chain Reaction (PCR). However, its non-specific amplification phenomenon is serious, which greatly limits development. Objective: In this study, we prepared Tth monoclonal antibodies against Tth DNA polymerase and researched their application in hot-start PCR. Methods: Tth was recombinantly expressed and purified, and used as an antigen to immunize BALB/c mice to obtain monoclonal antibodies. The qualified monoclonal antibody and Tth are incubated for a period of time at a certain temperature to obtain the hot-start Tth. We tested the polymerase activity and exonuclease activity blocking performance of hot-start Tth. Finally, the hot start Tth was applied to one-step RT-PCR. Results: Tth with a purity of >95% was obtained, and ten monoclonal antibodies were obtained by immunization. After incubation, there were three monoclonal antibodies identified that could inhibit the polymerase activity of Tth at low temperature. Furthermore, these three antibodies have successfully eliminated non-specific amplification in practical applications. Conclusion: Three monoclonal antibodies were successfully validated. Among them, monoclonal antibody 9 has the best overall effect. They have the function of inhibiting at low temperature and releasing at high temperature, which can be used as Tth polymerase inhibitors in the field of molecular diagnostics.

A high-resolution search for the Hα emission line of the accreting companion GQ Lup b with ESPRESSO

&lt;p&gt;In the current theories of planet formation, the amount of energy that a forming gas giant retains from its&amp;#160;accretion flow is still unknown. This unconstrained parameter has a large impact on the post-formation evolution&amp;#160;of the new planet, as it defines its initial temperature and luminosity. Models have been developed, ranging from&amp;#160;&amp;#8220;hot-start&amp;#8221; models assuming that all the energy is retained internally, to &amp;#8220;cold-start&amp;#8221; ones assuming that&amp;#160;everything is radiated away, and &quot;warm-start&quot; ones in between. Their coexistence introduces large degeneracies&amp;#160;on the determination of age and mass in direct imaging observations, as these studies use the cold or hot-start&amp;#160;models to infer these parameters from the observed luminosity of a planet. A promising way of solving this&amp;#160;problem is the study of atomic emission lines originating from the hot gas shocked by the accretion flow.&amp;#160;Recently, Aoyama et al. (2018, 2020) presented simulations of hydrogen lines emitted by the accretion shock&amp;#160;onto the circumplanetary disk and the planetary surface. They showed that the line luminosity and width can be&amp;#160;used to infer the protoplanet mass, thus giving an estimation that is independent from the evolution models. They&amp;#160;applied it to the case of PDS70 b and c (Aoyama &amp; Ikoma 2019, Hashimoto et al. 2020), but were ultimately&amp;#160;limited by the spectral resolution of the MUSE observations they used (R ~ 2500). In this context, our team&amp;#160;recently proposed and carried out a pilot program using the VLT/ESPRESSO fiber-fed spectrograph, equipped&amp;#160;with very high resolution (R = 190 000), to characterize the H&amp;#945; line of the young substellar companion GQ Lup b.&amp;#160;We will present in this poster how these observations were conducted, the methods used to remove the&amp;#160;contamination from the host star, and the results we obtained.&lt;/p&gt;

Analisis Konsentrasi PM2,5, CO, dan CO2, serta Laju Konsumsi Bahan Bakar Biopelet Sekam Padi dan Jerami pada Kompor Biomassa

Penelitian ini dilakukan untuk menganalisis konsentrasi PM2.5, CO dan CO2 dalam ruangan ketika dilakukan penggunaan bahan bakar biopelet pada sebuah kompor biomassa, serta menghitung laju konsumsi bahan bakar tesebut. Pengujian menggunakan metode water boiling test (WBT) untuk mensimulasikan proses memasak yang terbagi ke dalam 3 fase, yaitu cold start (CS)/fase dingin, hot start (HS)/fase panas, dan simmering (SM)/fase mendidih. Biopelet dibuat dari limbah sekam dan jerami padi. Pengukuran PM2,5 dilakukan menggunakan low volume air sampler (LVS) yang dilengkapi dengan elutriator untuk memisahkan partikel berukuran di atas 2,5 mikron dan filter fiberglass untuk menangkap partikel berukuran kurang dari 2,5 mikron pada kecepatan aliran udara 3,5 liter per menit. Sedangkan pengukuran CO dan CO2 menggunakan Portable Air Quality Monitor. Didapatkan konsentrasi PM2,5 biopelet sekam padi pada fase CS, HS, dan SM berturut-turut 33,13,30,81, dan 24,76 μg/Nm3, sedangkan untuk biopelet jerami padi diperoleh 23,29, 29,98, dan 30,42 μg/Nm3.Terkait konsentrasi CO, pada ketiga fase berturut-turut untuk biopelet sekam padi yaitu 5,29, 5,14, dan 6,09 ppm, sedangkan untuk biopelet jerami padi didapatkan 6,13, 5,86, dan 5,67 ppm. Terakhir, pengukuran konsentrasi CO2 biopelet sekam padi yaitu 436,74, 451,71, dan 472,82 ppm, sedangkan pada biopelet jerami padi terukur 419,87, 417,93, dan 453,43 ppm, pada ketiga fase berturut-turut. Konsentrasi PM2,5, gas CO dan CO2 biopelet masih memenuhi baku mutu udara indoor sesuai dengan PERMENKES/1077/2011. Rasio CO/CO2 berada di bawah nilai 0,02 yang menunjukkan pembakaran bahan bakar biopelet menghasilkan karbon monoksida yang kecil sehingga terjadi pembakaran sempurna. Laju konsumsi bahan bakar biopelet lebih kecil dibandingkan jika digunakan biomassa yang belum diolah menjadi biopelet. ABSTRACTThis research was conducted to analyse indoor PM2.5, CO dan CO2 concentrations during the use of biopellet fuel in a biomass stove, and to calculate the fuel consumption rate. Water boiling test (WBT) was used to simulate cooking activities, which comprises of three phases, i.e., cold start (CS), hot start (HS), and simmering (SM). The biopellet was made from rice husk and straw wastes. PM2.5 were measured by using a low volume air sampler (LVAS) that was equipped with an elutriator to separate particulates with more than 2.5-micron size and a fiberglass filter to trap particulates with less than 2.5-micron size at air flow rate of 3.5 liter per minute. Meanwhile, a portable air quality monitor was used to measure CO dan CO2. It was found that PM2.5 concentrations for rice husk biopellet during CS, HS, and SM were, respectively, 33.13,30.81, and 24.76 μg/Nm3. While those for rice straw biopellet were 23.29, 29.98, and 30.42 μg/Nm3. Regarding CO concentrations during the three phases for rice husk biopellet were, respectively, 5.29, 5.14, and 6.09 ppm, whilst for the rice straw biopellet the concentrations were 6.13, 5.86, and 5.67 ppm. Lastly, the CO2 measurements for rice husk biopellet were 436.74, 451.71, and 472.82 ppm, while those for rice husk biopellet were 419.87, 417.93, and 453.43 ppm, during the three phases correspondingly. All PM2.5, CO and CO2 gas concentrations still met indoor air quality standard, in accordance with Minister of Health Regulation Number 1077/2011. Moreover, the CO/CO2 ratios were below 0.02, which indicates that the combustion of the biopellet fuels emited small amount of carbon monoxide, thus, perfect combustion were achieved. The biopellet fuel consumption rates were smaller than those of virgin biomasses that had not been converted into biopellet