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As a biodegradable material, magnesium alloy has a modulus similar to that of bone, and given the biological activity of its degradation products, it has the potential to be a bone grafting material. Oxidation heat treatment is a very effective passivation method that may reduce the rate of magnesium alloy degradation. Oxidation heat treatment increases the rare earth oxide content of the scaffold as well as the corrosion resistance of the scaffold. The overall cytotoxicity of the as-printed scaffolds (APSs) and oxidation heat-treated scaffolds (OHSs) showed that OHSs accelerated cell proliferation. In the apoptosis experiment, the OHS group had a cell survival rate between that of the control group and of the as-printed group. In the osteogenic induction experiment, the alkaline phosphatase activity and the quantity of mineralized nodules were greater in the APS and OHS groups than in the control group. Marker proteins for bone growth were expressed at higher levels in the APS and OHS groups than in the control group. Therefore, oxidation heat-treated 3D printing scaffolds with good biocompatibility and osteogenic properties have great potential to be made into advanced biomaterials that can be used to fix bone defects.

Plants have evolved the ability to distinguish between symbiotic and pathogenic microbial signals. However, potentially cooperative plant-microbe interactions often abort due to incompatible signaling. The

Plants have evolved the ability to distinguish between symbiotic and pathogenic microbial signals. However, potentially cooperative plant–microbe interactions often abort due to incompatible signaling. The Nodulation Specificity 1 ( NS1 ) locus in the legume Medicago truncatula blocks tissue invasion and root nodule induction by many strains of the nitrogen-fixing symbiont Sinorhizobium meliloti . Controlling this strain-specific nodulation blockade are two genes at the NS1 locus, designated NS1a and NS1b , which encode malectin-like leucine-rich repeat receptor kinases. Expression of NS1a and NS1b is induced upon inoculation by both compatible and incompatible Sinorhizobium strains and is dependent on host perception of bacterial nodulation (Nod) factors. Both presence/absence and sequence polymorphisms of the paired receptors contribute to the evolution and functional diversification of the NS1 locus. A bacterial gene, designated rns1 , is required for activation of NS1 -mediated nodulation restriction. rns1 encodes a type I-secreted protein and is present in approximately 50% of the nearly 250 sequenced S. meliloti strains but not found in over 60 sequenced strains from the closely related species Sinorhizobium medicae . S. meliloti strains lacking functional rns1 are able to evade NS1 -mediated nodulation blockade.

The influence of pure Al, Al-Si and Zn-Al weld fillers on microstructure and mechanical properties was investigated during lap laser welding-brazing of Al to Cu. Al4.2Cu3.2Zn0.7 IMC layer and plate-like Al2Cu phase were observed at Al/Cu interface with pure Al and Al-Si weld fillers. Microcrack was easy to generate in Al2Cu phase decreasing the joint strength. When the Zn-Al weld filler was adopted, the formation of Al2Cu brittle phase was limited by low Al content and the CuZn and CuZn5 IMC layers were observed at Al/Cu interface. According to the chemical potential, the diffusivity of Cu atoms in Zn-Al weld filler was much lower than that of pure Al and Al-Si weld fillers, which prevented from the formation of coppery phases near the Al/Cu interface. Si atoms tended to concentrate at Al/Cu interface. It played a role in obstructing the diffusion of Cu atoms, enhancing the Al/Cu joint strength to some extent. According to nanoindentation result, the mechanical property of the formed phases (CuZn and CuZn5) in the case of Zn-Al weld filler was better than that formed with pure Al and Al-Si weld fillers such as Al2Cu and Al4.2Cu3.2Zn0.7. The highest tensile strength was 148 MPa with Zn-Al weld filler.

Piano keyboard visualization was very popular right now, but there are very few virtual piano keyboard visualizations right now [1]. I was using unity to show the virtual piano keyboard and then they can play piano pieces by themselves or play a recording online [2]. After that you can listen and see how the recording pieces play it on the visual keyboard to give them a clear idea about how the songs played on a keyboard2 [3]. For those who played by themselves it can let them heard and know also when the visual piano play for them, they can tell if they have offbeat playing or they missing not. Piano4Play is an automated piano transcription and keyboard visualization system using AI and deep learning techniques. The user could upload a recorded piece of music, and our app would visualize the music on a digital piano keyboard. The user could see how the music is played visually in order to help piano beginners to see how the music will be played on piano in order to help them learn more quickly and easier, and advanced players could use the app to see whether they made any mistake when they are playing so they can get some improvement. Our app uses wav and MIDI files, repl, real-time database, google Collab and Unity.

Tremendous amounts of oil and gas reservoir are located in ultra-deep formations, such as Shunnan block in Tarim basin of China, some reservoirs buried deeper than 8000m and which are major exploration areas of SINOPEC. The formation geological conditions are complicated, multiple pressure systems co-exist in the same borehole, narrow pressure-margin problems, all above may cause down-hole troublesome conditions while cementing, such as leaking, fracturing formations and so on. And the managed pressure cementing (MPC) was selected for solving the above problems. But the key for a successful MPC depend on accurate, real-time knowledge of dynamic parameters calculation. Therefore, a real time dynamic parameters calculation for MPC is very important. Firstly, a comprehensive real-time hydraulic calculation method for cementing replacement process was established, in which the difference of density, rheological properties, location and length of different fluids were taken into account. In order to improve the calculation precision, the flow channel both in pipe and annuli was divided into several sections, through which the different diameters of the channels were considered. Secondly, according to the density contrast of operating fluids, a vacuum (U-Tube effect) will appear at the inlet in the cementing replacement process, an integrated U-Tube effect analytical model was established based on the Euler equation, in which the influence of well deviation was taken into account too, and though which the height and volume of vacuum, the down-hole operating fluids acceleration, the out flow rate variation et al. all can be accurately calculated and simulated. Moreover, a series of system calculation software were developed to predict cementing fluids position, fluids acceleration, flow pressure drop, BHP, expected WHP and the related control parameters for MPC. The proposed model has been applied in HPHT ultra-deep well MPC operation of SINOPEC Northwest oil filed in Traim basin, there is an excellent match between the calculated and measured data. Furthermore, this simulation software has been used for designing the MPC parameters, and it runs smoothly with convenient operation. Therefore it can be seen this system can be applied to provide more convenient fast and precise dynamic parameters monitoring for MPC. This study proposed a novel model of Cementing dynamic parameters calculating and developed a comprehensive real-time monitoring system for MPC. Through the application of the monitoring, we can adjust the cementing parameters in real time while MPC, and this real-time monitoring has been applied in several wells very well. Therefore, this study is novel and can afford an effective approach to improve cement quality.

Materials 14(10), 2677 (2021). doi:10.3390/ma14102677, Published by MDPI, Basel

Butt laser welding-brazing of Mg to Ti with Mg based filler was performed with the assistance of Cu coating. The thickness of Cu coating was varied in the study, to investigate its influence on microstructure and mechanical properties of the joint. Two main regions were distinguished along the Mg/Cu coated Ti interface. At the upper interface, the bonding mechanism evolved from mechanical bonding into a “Ti3Al and AlCu2Ti” metallurgical bonding, and into a “Ti3Al + Ti2Cu + AlCu2Ti” metallurgical bonding as Cu coating thickness varied from 0 μm to 19.7 μm to 24.9 μm. At the lower interface, mechanical bonding changed into the IMC layer consisted of Ti3Al, Ti2Cu and AlCu2Ti when Cu coating thickness reached 28.2 μm. The chemical potential calculated by the developed Toop model suggested that Cu played a role in promoting the mutual diffusion between Al and Ti. Ti tended to react with Al first compared with Cu suggesting Ti-Al compounds were produced easily at Mg/Ti interface. In the case of Cu coating thickness of 19.7 μm, the joint load reached a peak value of 3457 N, as high as 85.35% of that of Mg base metal. The fracture mode changed from interfacial failure to fusion zone failure when the coating thickness reached 19.7 μm.

Dissimilar lap joining of AZ31B Mg alloy to Cu-Ni coated Ti-6Al-4V was carried out by laser welding-brazing method. The effect of Cu and Ni contents on interfacial reaction and joint fracture load were analyzed. For the joint in which the Ni coating (15.36 µm) was thicker than the Cu coating (5.47 µm), thick intermetallic compound (IMC) composed of a mixture of light gray Al-Ni-Ti + Ti3Al + Ti2Ni phases mingled with dark gray Ti3Al was produced at the interface. In comparison, a mixed interfacial reaction layer consisted of Ti2Ni and Ti3Al was formed from the direct irradiation zone to the weld toe zone of the joint with comparable Ni and Cu coating thicknesses (10.78 µm Cu–9.30 µm Ni). In this case, the thickness of the mixed layer was below the critical thickness of 10 µm. For the joint in which the Cu coating is much higher than the Ni coating thickness (17.12 µm Cu–4.23 µm Ni), Ti3Al and Ti2Ni mixed reaction layer was produced at the brazed interface of direct irradiation zone, whereas, only Ti3Al phase was formed at the middle zone. At the weld toe zone, Ti2Cu uneven interfacial reaction layer was evolved. With increasing Cu and decreasing Ni coating thicknesses, the fracture load first increased and then slightly decreased, the maximum tensile-shear fracture load attained 2020 N for joints with comparable Cu and Ni coating thicknesses. This is twofold higher than that of uncoated joint. The tensile-shear investigation showed that the joint would fracture at the fusion zone when the coating thickness of Ni was comparable or higher than Cu. In contrast, interfacial failure was observed when the thickness of Cu was much higher than the Ni. For the joint with interfacial failure mode, tear ridge was observed from the fracture surface, whereas, the fusion zone fracture surfaces was noted to display a typical dimple feature. The authors would like to acknowledge the support provided by University of Malaya (Project No. GPF073A-2018 ), National Natural Science Foundation of China (Project No. 51504074 and 51875129 ) and Key Research & Development Program in Shandong Province (Grant No. 2017CXGC0811 and 2017GGX30147 ). Scopus

Isoflavones are not involved in rhizobial signaling in red clover, but likely play a role in defense in the rhizosphere. Red clover (Trifolium pratense) is a high-quality forage legume, well suited for grazing and hay production in the temperate regions of the world. Like many legumes, red clover produces a number of phenylpropanoid compounds including anthocyanidins, flavan-3-ols, flavanols, flavanones, flavones, and isoflavones. The study of isoflavone biosynthesis and accumulation in legumes has come into the forefront of biomedical and agricultural research due to potential for medicinal, antimicrobial, and environmental implications. CRISPR/Cas9 was used to knock out the function of a key enzyme in the biosynthesis of isoflavones, isoflavone synthase (IFS1). A hemizygous plant carrying a 9-bp deletion in the IFS1 gene was recovered and was intercrossed to obtain homozygous mutant plants. Levels of the isoflavones formononetin, biochanin A and genistein were significantly reduced in the mutant plants. Wild-type and mutant plants were inoculated with rhizobia to test the effect of the mutation on nodulation, but no significant differences were observed, suggesting that these isoflavones do not play important roles in nodulation. Gene expression profiling revealed an increase in expression of the upstream genes producing the precursors for IFS1, namely, phenylalanine ammonium lyase and chalcone synthase, but there were no significant differences in IFS1 gene expression or in the downstream genes in the production of specific isoflavones. Higher expression in genes involved in ethylene response was observed in the mutant plants. This response is normally associated with biotic stress, suggesting that the plants may have been responding to cues in the surrounding rhizosphere due to lower levels of isoflavones.

Legumes are the second most important family of crop plants. One defining feature of legumes is their unique ability to establish a nitrogen-fixing root nodule symbiosis with soil bacteria known as rhizobia. Since domestication from their wild relatives, crop legumes have been under intensive breeding to improve yield and other agronomic traits but with little attention paid to the belowground symbiosis traits. Theoretical models predict that domestication and breeding processes, coupled with high-input agricultural practices, might have reduced the capacity of crop legumes to achieve their full potential of nitrogen fixation symbiosis. Testing this prediction requires characterizing symbiosis traits in wild and breeding populations under both natural and cultivated environments using genetic, genomic, and ecological approaches. However, very few experimental studies have been dedicated to this area of research. Here, we review how legumes regulate their interactions with soil rhizobia and how domestication, breeding and agricultural practices might have affected nodulation capacity, nitrogen fixation efficiency, and the composition and function of rhizobial community. We also provide a perspective on how to improve legume-rhizobial symbiosis in sustainable agricultural systems.

Background: To compare the clinical outcomes of tubeless minimally invasive percutaneous nephrolithotomy（mPCNL）and common minimally invasive percutaneous nephrolithotomy under local anesthesia, and to explore the feasibility, safety and clinical efficacy of tubeless mPCNL under local anesthesia. Methods: Patients with PCNL who underwent local anesthesia from January 1, 2018 to November 30, 2018. The patients were divided into Group 1 (tubeless mPCNL: indwelling double J tube, no indwelling nephrostomy tube) and group 2 (common mPCNL: indwelling double J tube and nephrostomy tube). The intraoperative and postoperative parameters of the two groups were compared, including operation time, average postoperative hospital stay, puncture position, postoperative hemoglobin decline, postoperative visual analogue scale (VAS), analgesic use, postoperative fever and stone removal rate. Results: In group1,the VAS scores of 6 hours after surgery was 4.07±1.79 significantly lower than that for group 2 (4.07±1.79 vs 6.24±1.33, P0.05). Conclusion: Tubeless mPCNL is a simple, safe and effective technique under local anesthesia. It is worthy of clinical application. Tubeless mPCNL treatment for renal stones can significantly reduce postoperative pain and shorten hospital stays compared with common m PCNL.

To improve the metallurgical bonding of immiscible and nonreactive Mg/Ti system, Ni electro-coating was employed acting as an intermediate element by reacting with both Mg and Ti in laser heat-conduction welding process. Influence of laser power on welding quality was investigated and interfacial reaction with participation of Ni coating was analyzed. The elemental diffusion mechanism was clarified with the assistance of numerical simulation. Reliable joints were obtained with suitable laser powers ranging from 1200 W to 1800 W. Continuous reaction layer of Ti2Ni and Ti solid solution formed at the interface. The reaction layer thickness was not monotone increasing with increase of laser power. Mg-Al-Ni ternary phase dispersed in fusion zone at Mg side. Diffusion of electroplated Ni was influenced by a bidirectional mechanism to Mg side and Ti side, which resulted in the variation of reaction layer thickness. The maximum tensile-shear load could reach 144 N/mm (about 53.3% of joint efficiency of base metal AZ31B Mg alloy) when laser power was 1500 W. Joint strength and fracture mode were associated with two aspects: interfacial reaction and weld appearance of Mg side. As a result, reliable joining was realized based on appropriate interfacial metallurgical bonding and no weld defects at Mg side.

The immiscible and nonreactive characteristics of Mg/Ti dissimilar metals restrict the metallurgical bonding and reliable joining of them. To solve this problem, the Al interlayer between Mg/Ti was added. The Mg/Ti joint without addition of Al interlayer could not be welded, while relatively acceptable appearance was obtained when adding Al interlayer. The interfacial reaction was improved with the assistance of Al interlayer resulting in metallurgical bonding at the interface. The TiAl3 phase formed at the direct laser irradiation zone. Note that the interfacial reaction layer increased little with the increasing thickness of Al interlayer. The interfacial reaction layer was mainly restricted by dissolution of Ti element. Temperature field and thermodynamic calculation assisted to prove the interfacial reaction at the fusion zone/Ti interface and the formation of TiAl3. The tensile-shear testing indicated that the maximum tensile-shear force could reach 2230 N/cm (about 81% of that of AZ31B Mg alloy base metal) when the laser power was 2300 W and the thickness of added Al interlayer was 0.05 mm. The tensile-shear force decreased when network structure of Mg17Al12 precipitated in the weld zone. The fracture path changed from fusion zone/Ti to Mg fusion line when the thickness of Al interlayer exceeded 0.12 mm.

Medicago truncatula shows a high level of specificity when interacting with its symbiotic partner Sinorhizobium meliloti. This specificity is mainly manifested at the nitrogen-fixing stage of nodule development, such that a particular bacterial strain forms nitrogen-fixing nodules (Nod+/Fix+) on one plant genotype but ineffective nodules (Nod+/Fix−) on another. Recent studies have just begun to reveal the underlying molecular mechanisms that control this specificity. The S. meliloti strain A145 induces the formation of Fix+nodules on the accession DZA315.16 but Fix−nodules on Jemalong A17. A previous study reported that the formation of Fix−nodules on Jemalong A17 by S. meliloti A145 was conditioned by a single recessive allele named Mtsym6. Here we demonstrate that the specificity associated with S. meliloti A145 is controlled by multiple genes in M. truncatula, including NFS1 and NFS2 that encode nodule-specific cysteine-rich (NCR) peptides. The two NCR peptides acted dominantly to block rather than promote nitrogen fixation by S. meliloti A145. These two NCR peptides are the same ones that negatively regulate nitrogen-fixing symbiosis associated with S. meliloti Rm41.

Theory and experiment of Tm: YAG 2 μm double-pulse laser output based on the two-step signal of acousto-optic Q-switch is presented for the first time. As pump power of 10 W, a Q-switched Tm: YAG double-pulse laser is achieved with output energy of 3.6 mJ at 2014.16 nm and repetition rate of 100 Hz. The pulse width of the first pulse is 416 ns, and that of the second is 407 ns. The interval between the two pulses is 1 ms. The beam quality is M2x = 1.39 and M2y = 1.34.

Many symbiotic Epichloë species are seed-transmitted in their grass hosts. For a detailed investigation of Epichloë festucae colonization throughout the life cycle of its host, the authors transformed strain Fl1 with a fungal-active gene for enhanced cyan-fluorescent protein (eCFP), introduced it into perennial ryegrass (Lolium perenne), and used confocal microscopy to track its growth in the shoot apex, floral primordium, floral organs, seeds, and seedlings. Hyphae intercellularly colonized leaf sheaths, blades, true stems, and leaf primordia, and among floral primordia the endophyte exhibited different levels of colonization. In preanthesis florets, E. festucae colonized the pistil and stamen, but not pollen grains, and ramified throughout the ovule nucellus, but not the integument or embryo sac. Generally, only a single hypha was observed extended from the ovary placenta into the ovule. Within 4 d after anthesis, fungal hyphae had ramified throughout the developing seed and embryo. As the embryo matured, fungal hyphae became abundant between the testa and aleurone layer, and around the shoot apex and radical of the embryonic axis. During germination, hyphae accumulated in the mesocotyl and invaded the newly formed shoot apex near the meristem. In this host-fungus symbiosis, transmission to seedlings averaged 41% in 2010 and 76% in 2011. Each year, the frequency of ovary infection was similar to the frequency of infecting embryos and seedlings, indicating that colonization of the ovary and embryo was required for seed transmission.

Food safety problems are drawing increasing attention after the occurrence of repeated food scandals in China. The literature has found that social trust, a non-institutional factor, is an important factor in disciplining dishonest behaviour and improves the media's incentives to report. In this paper, we develop a model to investigate the dual effects of social trust—behaviour discipline effect and media enhancing effect—and analyse its interplay with institutional factors on food scandal exposure. The theory is then tested using 2004–2011 food event data. The results show that trust has a significant positive impact on food scandal exposure, which implies that the media enhancing effect plays a dominant role in China. However, this effect is weakened in provinces with a higher level of law enforcement and market development, which suggests that institutional factors are a substitute for social trust in affecting food scandal exposure in China.

Additive manufacturing of ZK60 alloy by laser powder bed fusion (LPBF) has promising prospect for light-weight structures and biodegradable implants. Though hot cracking of ZK60 has been widely reported during welding processes, it is surprisingly that no literature so far mentioned it during the LPBF. This paper identified serious solidification and liquation cracking in ZK60 LPBF samples. Low-melting eutectic precipitation was characterized as Mg7Zn3 along the cracks. Ruptured by thermal stress, solidification cracking occurred in the depositing layers due to the wide solidification range, while liquation cracking occurred in the deposited layers due to repeated heating. The two types of cracks merged into a connected network, which hugely deteriorated the relative density of LPBF samples.

Thermal expansion induced by the temperature difference between the hot wellbore fluid and the cold fluid in the trapped multi-annuli, severely threatens the casing safety and the well integrity of subsea wells. With the aim to obtain the multi-annuli behavior of the transient temperature increase in subsea wells, mathematic models of heat transfer in the wellbore and multi-annuli are established. The wellbore is divided into different sections vertically from the bottom to the wellhead according to the amount of annuli considering the different processes of heat transfer in various sections. And the finite difference method and the Crank Nicolson scheme are used to solve the partial differential equations. As the traditional semisteady-state method doesn't take into account the transient heat transfer from wellbore fluid to the annuli, we demonstrate that the temperature of the multi-annuli is highly over-estimated at the early stage of production. Compared to the traditional semisteady-state method, our transient method reveals the temperature increase performance of the multi-annuli at the initial stage of production. Given that the production rate is an important factor that affects the temperature of the multi-annuli, we present the relationship between the temperature in the annuli and the production rate. It turns out that the temperature in the annuli rises significantly when improving the production rate. So knowing how the production rate influences the temperature in the annuli is beneficial to making an appropriate production plan and sustaining production.

Legumes engage in root nodule symbioses with nitrogen-fixing soil bacteria known as rhizobia. In nodule cells, bacteria are enclosed in membrane-bound vesicles called symbiosomes and differentiate into bacteroids that are capable of converting atmospheric nitrogen into ammonia. Bacteroid differentiation and prolonged intracellular survival are essential for development of functional nodules. However, in the Medicago truncatula–Sinorhizobium meliloti symbiosis, incompatibility between symbiotic partners frequently occurs, leading to the formation of infected nodules defective in nitrogen fixation (Fix−). Here, we report the identification and cloning of the M. truncatula NFS2 gene that regulates this type of specificity pertaining to S. meliloti strain Rm41. We demonstrate that NFS2 encodes a nodule-specific cysteine-rich (NCR) peptide that acts to promote bacterial lysis after differentiation. The negative role of NFS2 in symbiosis is contingent on host genetic background and can be counteracted by other genes encoded by the host. This work extends the paradigm of NCR function to include the negative regulation of symbiotic persistence in host–strain interactions. Our data suggest that NCR peptides are host determinants of symbiotic specificity in M. truncatula and possibly in closely related legumes that form indeterminate nodules in which bacterial symbionts undergo terminal differentiation.

A fiber laser welding-brazing procedure has been developed for joining AZ31B magnesium alloy to Cu-Ni coated Ti-6Al-4V titanium sheet using AZ92D filler wire. The effect of the interlayer arrangements (AZ31B/Ni-Cu/Ti-6Al-4V and AZ31B/Cu-Ni/Ti-6Al-4V) on appearance, interfacial reaction and mechanical properties were investigated at different heat input. It was found that the feasibility of this process depends strongly on the pre-existing Cu-Ni layer on the Ti surface that promotes wetting of the AZ92 filler. Within the range of 1200-1600 W, defect free joints in both interlayer arrangements. Depending on the interlayer arrangements chosen, different reactions layers formed inside the joint region. Nevertheless, at optimum heat input (1400 W), Ti2Ni mingled with Ti3Al interfacial reaction products was produced along the fusion zone (FZ)-Ti brazed interface in both interlayer arrangements. The tensile-shear fracture load of the joints produced at the optimum laser power reached a maximum value of 2016.5 N for AZ31B/Ni-Cu/Ti-6Al-4V and 2014.6 N for AZ31B/Cu-Ni/Ti-6Al-4V, representing an efficiency of 71% compared to AZ31B alloy. Under suitable heat input, the joints failed at the fusion zone of the AZ31B base metal. In contrast, incomplete brazing or large volume of intermetallics at the brazed interface resulted in interfacial failure at lower/higher heat input. This work was financially supported by University of Malaya (Grant No. GPF073A-2018 ), National Natural Science Foundation of China (Grant. No. 51504074 and 51875129 ) and Key Research & Development Program in Shandong Province (Grant No. 2017CXGC0811 and 2017GGX30147 ). Scopus

Drilling riser–conductor system is crucial to the offshore drilling. Complex marine environment can give rise to a series of problems such as buckling and stability on riser–conductor system. A novel method that introduces the optimization of top tension and calculates axial force has been proposed. Effective axial stress equations for the whole riser–conductor system are established in this paper considering these factors such as rising velocity of drilling fluid, temperature, pressure, and current force. Then, the neutral point of effective axial stress is introduced in marine drilling and top tension can be adjusted to ensure the neutral point is located at BOP. Compared with other methods, a case study shows that a higher accuracy of effective axial stress can be expected with this method. Meanwhile, top tension should be optimized to allow the neutral point to locate at BOP and ensure the BOP keep enough bending strength.

Rj4 is a dominant gene in soybeans (Glycine max) that restricts nodulation by many strains of Bradyrhizobium elkanii. The soybean-B. elkanii symbiosis has a low nitrogen-fixation efficiency, but B. elkanii strains are highly competitive for nodulation; thus, cultivars harboring an Rj4 allele are considered favorable. Cloning the Rj4 gene is the first step in understanding the molecular basis of Rj4-mediated nodulation restriction and facilitates the development of molecular tools for genetic improvement of nitrogen fixation in soybeans. We finely mapped the Rj4 locus within a small genomic region on soybean chromosome 1, and validated one of the candidate genes as Rj4 using both complementation tests and CRISPR/Cas9-based gene knockout experiments. We demonstrated that Rj4 encodes a thaumatin-like protein, for which a corresponding allele is not present in the surveyed rj4 genotypes, including the reference genome Williams 82. Our conclusion disagrees with the previous report that Rj4 is the Glyma.01G165800 gene (previously annotated as Glyma01g37060). Instead, we provide convincing evidence that Rj4 is Glyma.01g165800-D, a duplicated and unique version of Glyma.01g165800, that has evolved the ability to control symbiotic specificity.

The temperature difference between hot flowing production (including petroleum & natural gas) and fluid in the sealed annuli leads to annular pressure buildup (APB). The pressure increase could be very high due to the low compressibility of the annulus fluid, thereby endangering the well integrity and casing safety, especially in the HPHT (high pressure high temperature) subsea wells. In this paper, a semi-steady state model is presented to predict APB; the model takes several crucial factors into account, such as the differences of annulus temperature with depths, heat transfer diverseness at various well sections, and the ratio change between isobaric thermal expansion and the isothermal compressibility. The results of the case study demonstrate that APB is directly influenced by production rate, well depth, and annular length. In these factors, APB is most sensitive to the production rate. The higher the production rate, the higher pressure increase in the annuli becomes. The model provides a practical APB prediction method that is beneficial to well integrity and casing safety during petroleum and natural gas production process.