Easy Injection Research Articles

Capsule polymer flooding for enhanced oil recovery

To solve the problems of shear degradation and injection difficulties in conventional polymer flooding, the capsule polymer flooding for enhanced oil recovery (EOR) was proposed. The flow and oil displacement mechanisms of this technique were analyzed using multi-scale flow experiments and simulation technology. It is found that the capsule polymer flooding has the advantages of easy injection, shear resistance, controllable release in reservoir, and low adsorption retention, and it is highly capable of long-distance migration to enable viscosity increase in deep reservoirs. The higher degree of viscosity increase by capsule polymer, the stronger the ability to suppress viscous fingering, resulting in a more uniform polymer front and a larger swept range. The release performance of capsule polymer is mainly sensitive to temperature. Higher temperatures result in faster viscosity increase by capsule polymer solution. The salinity has little impact on the rate of viscosity increase. The capsule polymer flooding is suitable for high-water-cut reservoirs for which conventional polymer flooding techniques are less effective, offshore reservoirs by polymer flooding in largely spaced wells, and medium to low permeability reservoirs where conventional polymers cannot be injected efficiently. Capsule polymer flooding should be customized specifically, with the capsule particle size and release time to be determined depending on target reservoir conditions to achieve the best displacement effect.

Elucidating roles of fulleropyrrolidine-based materials as extraordinary electron transporters for boosting efficiency of perovskite photovoltaics

To achieve an ideal electron transfer layer (ETL) for perovskite solar cell (PSC), effective compounds were developed based on fullerene C60 functionalized with a pyrrolidine ring (fulleropyrrolidine), to which a cyanoethyl group, a thiophene ring, and four DNA bases were attached. Density functional theory (DFT) calculations were employed to study structural, electronic, optical, and electron mobility features of these materials. To more precisely determine the HOMO and LUMO energy levels of all samples, the NBO calculations were accomplished at PBE0-D3/6-31G(d,p) theoretical level. The LUMO levels of all ETL samples could be aligned with the conduction band of perovskite CsFAMAPbIBr via their coupling within fabricated PSCs, enabling easy electron injection from CsFAMAPbIBr to the Ag electrode. All functionalized fullerene C60–based ETLs exhibited very high electron mobilities in the range of 0.744–1.598 cm2V−1s−1 which were significantly greater than 1.461 × 10−5 cm2V−1s−1 for pure C60 as the reference. High fill factors (FFs), power conversion efficiencies (PCEs), and open circuit voltages (VOC) were measured for PSC devices with C60–based ETLs, varying within the ranges of 0.892–0.897, 22.489–23.984 %, and 1.111–1.179 V, respectively, indicating they could yield excellent photovoltaic parameters.

Research and application of the low-damage temperature-controlled phase change temporary plugging agent

Ultra-deep dense sandstone reservoirs are characterized by high stress, large stress difference, high temperature, etc. Compared with conventional fracturing techniques, temporary plugging fracturing techniques are more capable of increasing fracture complexity and improving the stimulation reservoir volume (SRV). Phase-change temporary plugging agent has received wide attention due to its easy injection and return characteristics, etc. However, the temporary plugging mechanism of phase-change temporary plugging agent on shot-holes and fractures is still unclear. Therefore, this study aimed to develop a temperature-controlled phase change temporary plugging agent (STPA). The main properties of STPA, such as gel formation time and plugging capacity, are studied. The results show that STPA completes the transition behavior of solution-gel-solution at different temperatures; the gel formation time and gel breaking time of STPA decrease with increasing temperature; the pressure-bearing capacity of the plugging increases with the width of the fracture; the pressure-bearing capacity of STPA is more than 20 MPa in the fracture, and more than 18 MPa in the “shot-hole + fracture”; the rate of injury to core permeability by STPA is about 1.2%. In addition, STPA was successfully applied in fracturing field practice, and the maximum injection pressure increment was about 12.08 MPa, with remarkable temporary plugging effect. These results help to reveal the plugging mechanism of phase change plugging agent, which is of guiding significance for the field application of STPA.

Optofluidic photonic crystal fiber platform for sensitive and reliable fluorescence based biosensing.

Biosensing plays a pivotal role in various scientific domains, offering significant contributions to medical diagnostics, environmental monitoring, and biotechnology. Fluorescence biosensing relies on the fluorescence emission from labelled biomolecules to enable sensitive and selective identification and quantification of specific biological targets in various samples. Photonic crystal fibers (PCFs) have led to the development of optofluidic fibers enabling efficient light-liquid interaction within small liquid volume. Herein, we present the development of a user-friendly optofluidic-fiber platform with simple hardware requirements for sensitive and reliable fluorescence biosensing with high measurement repeatability. We demonstrate a sensitivity improvement of the fluorescence emission up to 17 times compared to standard cuvette measurement, with a limit of detection of Cy5 fluorophore as low as 100 pM. The improvement in measurement repeatability is exploited for detecting haptoglobin protein, a relevant biomarker to diagnose several diseases, by using commercially available Cy5 labelled antibodies. The study aims to showcase an optofluidic platform leveraging the benefits provided by optofluidic fibers, which encompass easy light injection, robustness, and high sensitivity.

Synergistic Drug-Loaded Shear-Thinning Star Polymer Hydrogel Facilitates Gastrointestinal Lesion Resection and Promotes Wound Healing.

Easy injection, long-lasting barrier, and drug loading are the critical properties of submucosal injection materials for endoscopic surgery. However, conventional injectable polymers face challenges in simultaneously attaining these properties due to the inherent conflict between injectability and in situ stability. Here, a multi-arm star polymer hydrogel (denoted as βCP hydrogel) with long-lasting submucosal barrier (exceeding 120 min), rapid hemostasis, and sustained antibacterial properties is successfully developed by grafting poly(oligo(ethylene glycol) methyl ether methacrylate)(PEGMA) side-chains from β-CD via atom transfer radical polymerization (ATRP). During the onset of shearing, βCP hydrogel experiences the unwinding of polymer side-chains between neighboring star polymers, which facilitates the process of endoscopic injectability. After submucosal injection, βCP hydrogel undergoes the winding of polymer side-chains, thereby establishing a long-lasting barrier cushion. Meanwhile, owing to its distinctive structures with a hydrophobic inner cavity and an outer layer of hydrophilic polymer side-chains, βCP hydrogel enables simultaneous loading and on-demand release of diverse categories ofdrugs. This unique performance can adapt to the diverse demands during different stages of wound healing in a porcine endoscopic surgery model. These results indicate an appealing prospect for new application of star polymers as a good submucosal injection material in endoscopic treatments.

Pyro-phototronic effect enhanced the performance of TiO2 NRs/BiOCl//PEDOS heterojunction for a UV photodetector

This study presents the construction of an organic–inorganic heterojunction ultraviolet (UV) photodetector (PD) through face-to-face assembly. The synergistic effects of bismuth oxychloride (BiOCl) and titanium dioxide nanorods (TiO2 NRs) improve carrier transport efficiency and enhance the performance of the UV photodetector. The combination of BiOCl with TiO2 NRs generates a pyro-phototronic effect and increases the surface oxygen vacancies of TiO2 NRs, resulting in enhanced carrier transport efficiency, increased transient photocurrent, and reduced dark current in TiO2-based UV photodetectors. The enhanced photosensitivity of chloride (Cl) ions bound to selenium (Se) ions promotes easy electron injection from poly (3,4-ethylene dioxyselenophene) (PEDOS) into BiOCl, leading to accelerated electron transfer and a shortened response time. Compared to TiO2 NRs/BiOCl//TiO2 NRs/BiOCl, the TiO2 NRs/BiOCl//PEDOS heterojunction exhibits a fast photoresponse with a rise time of 0.0802 s and a fall time of 79.8 ms. The responsivity is significantly improved from 11.0 mA/W to 108.8 mA/W (a 10-fold enhancement), and the detectivity is increased from 0.67 × 1011 Jones to 1.25 × 1011 Jones at 365 nanomaterials (0 V). These findings provide valuable insights into the mechanism by which BiOCl nanosheets enhance the photodetection performance of devices, contributing to the advancement of UV photodetector technology.

Investigation of the wear and friction profile of TPU-based polymers at different infill ratios

Additive manufacturing is a widely used method in industry and research areas. In particular, fused deposition modelling is the most prevalent technique used by many professional and nonprofessional users. Many polymers can be used with this system, including thermo polyurethanes (TPU). TPUs have excellent elastic properties and high endurance against corrosion, humidity, and oil, and they ex-hibit a great absorbance capability to noise and vibrations, biocompatibility, and chemical resistance. Thermoplastic polyurethane (TPU) is also preferred for use in 3D/4D printing applications due to its easy casting, injection, and extrusion capabilities and its shape memory features. In this study, flexible TPU and carbon-mixed TPU were used to produce specimens with fused deposition modelling tech-niques at different infill ratios with the same patterns. The effects of the infill ratio within the different and same materials were investigated in terms of wear and friction profiles. Additionally, thermal and worn surface images were taken using a digital microscope. The hardness and diameter value altera-tions were also investigated for different materials and infill ratios. As a result of the study, material al-teration is more effective than the infill ratios in all parameters.

Study on time-varying characteristics and flow behavior of microencapsulated polymer

Due to the challenges posed by high injection pressure and significant viscosity shear loss, conventional polymer flooding methods are unable to effectively meet the urgent demand for enhanced oil recovery in medium- and low-permeability reservoirs. Microencapsulated polymer flooding is a promising solution to address the aforementioned challenges due to its advantages of easy wellbore injection, shear resistance, and delayed thickening. However, there is a lack of research on the release behavior and time-dependent characteristics of microencapsulated polymer and its impact on flow behavior in reservoirs. To address this gap, we conducted a series of experiments, including thermal stability tests, microfluidic chip experiments, and micro-scale oil displacement experiments, to reveal the time-varying behavior generated by the triggered release of microencapsulated polymers. The results showed that microencapsulated polymer can be fully triggered after 8 days of aging at 85 °C, with a viscosity exceeding the initial viscosity by more than 25 times. The release mechanism of the polymer aligned with the Ritger-Peppas model, transitioning from super Case-II transport to anomalous transport, and finally to Fickian diffusion with increasing temperature. During the triggering process, the presence of particles stabilized shear and improved oil displacement, particularly in small pore throats. Higher triggering degrees of the solution resulted in greater flow resistance within the microchannel, effectively suppressing fluid fingering. The oil displacement effectiveness of fully triggered microencapsulated polymer was comparable to that of conventional polymers. This study provides insights into the flow behavior of microencapsulated polymer at a microscopic level, offering valuable references for its application in the field.

New Injection Controls Environment for the Taiwan Light Source

Taiwan Light Source (TLS) has been service for user service since 1993. Several legacy systems have recently been updated in order to remove obsolescent parts and provide higher operating efficiency. Proprietary designed timing modules were recently replaced by an event based timing system. The magnets of the booster synchrotron were configured as three White circuits and driven by resonance excitation. The original control of the White circuits, which included an analogue amplitude loop and digital phase loop for regulation, has been replaced by full digital regulation loops. The successful upgrade of both systems has led to easy and smooth injection control with enhanced functionality and flexibility. The injection control includes foreground and background processes that coordinate the operation of e-gun, linear accelerator, booster synchrotron, and storage ring with the help of timing system. The injection control GUI provides an intuitive operation interface that includes parameter setting and all necessary information displays, such as various timing value, stored beam current/lifetime, injection efficiency, filling pattern, kickers waveform and so on. Energy saving mode of White circuits operation are supported and embedded into injection control to save electricity. Lifetime calculation of the storage ring is also synchronized with the injection process. Implementation details and operation experience will be presented.

Intravitreal injectable hydrogel rods with long-acting bevacizumab delivery to the retina.

Retinal vascular diseases such as neovascular age-related macular degeneration (nAMD) are the leading cause of blindness worldwide. They can be treated with intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) agents by inhibiting VEGF which is a major agent of abnormal blood vessel growth. However, because of drug's short half-life, clinical treatment often requires monthly repeated intravitreal injections, causing treatment burden and undertreatment. Among various kinds of drug carriers, in situ forming hydrogels have been studied as potential intravitreal drug carriers for the high drug loading, easy injection, controlled drug release, and protection of encapsulated drugs from the environment. However, gelation time, crosslinking degree, and drug release patterns following injection of a liquid that will be subsequently gelled in situ are susceptible to be hindered by dilution of the hydrogel precursor solution with body fluids (e.g., blood or vitreous). Here, we report an injectable pre-crosslinked hydrogel rod to overcome the limitations of in situ forming hydrogels and to extend intravitreal half-life of anti-VEGF for reducing intraocular injection frequency. Hydrogel rods can be simply prepared using in situ forming hydrogels, and injectable using a designed rod injector. The adjustable crosslinking degree of hydrogel rods easily controlled bevacizumab release profiles in a sustained manner. Compared with in situ forming hydrogels, hydrogel rods effectively reduced initial burst release, and showed sustained release with long-term drug efficacy in vitro. From the 4-month in vivo pharmacokinetic analysis, following the intravitreal injection of hydrogel rods, the half-life of bevacizumab in the vitreous and retina was significantly extended, and drug elimination to aqueous humor was effectively reduced. Finally, intraocular stability, degradation, and inflammatory response of hydrogel rods were evaluated. We expect that the hydrogel rod can be a potential drug delivery system for the treatment of nAMD and other conditions that need long-term and local sustained drug administration. STATEMENT OF SIGNIFICANCE: Herein, we report an injectable pre-crosslinked hydrogel rod based on an in situ forming hydrogel to achieve intravitreal long-acting anti-VEGF delivery to reduce injection frequency and improve the long-term visual outcomes of patients with retinal vascular diseases. Hydrogel rods were readily prepared using removable molds and injected using customized injectors. Compared to the in situ forming hydrogel, hydrogel rods showed significantly reduced initial burst release, controllable release profiles for several months, physical stability, and a long-acting anti-angiogenic effect. Animal studies demonstrated that the hydrogel rods dramatically prolonged the intraocular drug half-life while significantly reducing drug elimination for up to four months. Moreover, the biodegradability and safety of the hydrogel rods suggest their suitability as an advanced intravitreal DDS for treating retinal vascular diseases.

Injectable nanoengineered adhesive hydrogel for treating enterocutaneous fistulas

Enterocutaneous fistula (ECF) is a severe medical condition where an abnormal connection forms between the gastrointestinal tract and skin. ECFs are, in most cases, a result of surgical complications such as missed enterotomies or anastomotic leaks. The constant leakage of enteric and fecal contents from the fistula site leads to skin breakdown and increases the risk of infection. Despite advances in surgical techniques and postoperative management, ECF accounts for significant mortality rates, estimated between 15 and 20 %, and causes debilitating morbidity. Therefore, there is a critical need for a simple and effective method to seal and heal ECFs. Injectable hydrogels with combined properties of robust mechanical properties and cell infiltration/proliferation have the potential to block and heal ECFs. Herein, we report the development of an injectable nanoengineered adhesive hydrogel (INAH) composed of a synthetic nanosilicate (Laponite®) and a gelatin-dopamine conjugate for treating ECFs. The hydrogel undergoes fast cross-linking using a co-injection method, resulting in a matrix with improved mechanical and adhesive properties. INAH demonstrates appreciable blood clotting abilities and is cytocompatible with fibroblasts. The adhesive properties of the hydrogel are demonstrated in ex vivo adhesion models with skin and arteries, where the volume stability in the hydrated internal environment facilitates maintaining strong adhesion. In vivo assessments reveal that the INAH is biocompatible, supporting cell infiltration and extracellular matrix deposition while not forming fibrotic tissue. These findings suggest that this INAH holds promising translational potential for sealing and healing ECFs. Statement of significanceThis research manuscript presents a groundbreaking INAH for treating ECFs. The INAH, composed of a synthetic nanosilicate and gelatin-dopamine conjugate, offers versatile implications in tissue regeneration and localized drug delivery. Acting as a scaffold, the shear-thinning hydrogel enables easy injection, forming a stable structure that supports tissue regeneration and integrates with surrounding tissues. By incorporating bioactive cues, it guides cell behavior and promotes functional tissue regeneration. The INAH also demonstrates potential for localized drug delivery, releasing therapeutic agents over time to enhance efficacy and minimize side effects. This research showcases INAH as a promising solution for ECFs, with applications in tissue engineering and regenerative medicine, marking a significant advancement in the field.

Wood structure-inspired injectable lignin-based nanogels as blood-vessel-embolic sustained drug-releasing stent for interventional therapies on liver cancer

An embolic reagent with easy injection, well-controlled target embolization, and sustained release of chemotherapy drugs is urgently needed for successful trans-arterial chemo-embolization (TACE) treatment. However, the development of a highly effective embolic reagent is still challenged. Here, inspired and guided by the structural supporting properties and defense mechanisms of wood cell walls, an ideal lignin-based embolic nanogel (DOX-pN-KL) was explored. Based on the mechanical support of branched lignin and the π-π stacking force between the lignin aromatic ring with anti-tumor drug doxorubicin (DOX), DOX-pN-KL showed the highest mechanical strength among the reported thermosensitive embolization nanogel and performed high drug-loading and favorable sustained-release. Moreover, further TACE treatment and tumor microenvironment evaluation of VX2 tumor-bearing rabbits showed that this nanogel can completely block all levels of vessels in long term and continuously release DOX, thus having effective inhibition on tumor growth and metastasis. DOX-pN-KL is expected to be a promising alternative reagent for interventional therapy.

Lincomycin HCl-Loaded Borneol-Based In Situ Gel for Periodontitis Treatment.

Solvent exchange-induced in situ forming gel (ISG) has emerged as a versatile drug delivery system, particularly for periodontal pocket applications. In this study, we developed lincomycin HCl-loaded ISGs using a 40% borneol-based matrix and N-methyl pyrrolidone (NMP) as a solvent. The physicochemical properties and antimicrobial activities of the ISGs were evaluated. The prepared ISGs exhibited low viscosity and reduced surface tension, allowing for easy injection and spreadability. Gel formation increased the contact angle on agarose gel, while higher lincomycin HCl content decreased water tolerance and facilitated phase separation. The drug-loading influenced solvent exchange and matrix formation, resulting in thinner and inhomogeneous borneol matrices with slower gel formation and lower gel hardness. The lincomycin HCl-loaded borneol-based ISGs demonstrated sustained drug release above the minimum inhibitory concentration (MIC) for 8 days, following Fickian diffusion and fitting well with Higuchi's equation. These formulations exhibited dose-dependent inhibition of Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 8739, and Prophyromonas gingivalis ATCC 33277, and the release of NMP effectively inhibited Candida albicans ATCC 10231. Overall, the 7.5% lincomycin HCl-loaded 40% borneol-based ISGs hold promise as localized drug delivery systems for periodontitis treatment.

Experimental Evaluation of Combined Plugging System for CO2-Improved Oil Recovery and Storage

High-performance CO2-improved oil recovery (IOR) and storage technology is one of the most promising measures for global oilfield companies to achieve zero carbon targets. Due to the severe heterogeneity of most petroleum reservoirs and the significant density difference between CO2 and reservoir fluid, the efficiency of CO2-IOR and storage is usually limited. In this paper, a high-temperature and high-pressure 30 cm core displacement experiment was used to study the CO2 conformance control performance of both the single- and the combined plugging system in long sandstone cores. The single systems evaluated included polymer gels, CO2 foams, and CO2-responsive thickening polymer (CO2-RTP) systems. The combined systems were pairwise combinations of the three of them. Results show that the pressure rise and maximum breakthrough pressure of the gel system were the highest among three single-plugging systems. Its plugging efficiency was the highest, reaching 86.13%. At the same time, its gas production reduction rate was also the highest, reaching 95.71%. In the parallel 30 cm core plugging experiments, three combined plugging systems all showed excellent plugging and CO2 conformance improvement performance. Among them, the combined plugging systems containing polymer gels had larger plugging efficiency, and their gas production reduction ratios reached about 90%. Compared with single systems, the combined plugging systems had the advantages of easy injection and in-depth propagation, which can significantly improve CO2 conformance and oil recovery. The research results of this study can provide the experimental understanding and theoretical guidance for the current tricky oilfield problems of CO2 channeling.

Semi – Automation Design Using Flow Injection Analysis System with Smart Phone for the Determination of Total Phenols in Wastewater

Smart phone used as supporting hardware in different applications in chemical analysis are becoming increasingly important in everyday life. Rapid, easy, and straightforward analytical system flow injection analysis system for the determination of the total phenols was conducted using 4-aminoantipyrine reagent. The detection method was based on the reaction total phenols with reagent in the basic media and subsequent formation of a yellow color product. The samples or standard solutions were injection into a carrier stream to react with 4-aminoantipyrine reagent and ammonium chloride with ammonium hydroxide to give yellow color product, which was detected by spectrophotometer at 510 nm. The experimental condition such as flow rate of reagent and carrier, reagent volume, length of reaction coil and concentration of reagent were optimized. A good linear calibration curve in the range of 250-2000 mg L-1 was obtained with regression equation (y=0.0108 x + 0.3453), (R= 0.9989). The limit of detection was in the amount of 0.0112 mg L-1. The method was successfully applied for the determination of the total phenols in wastewater.

Micro-manipulation Interface that Presents Surface Force Tactile Sensation According to the Cell Deformation

The microinjection technique is widely applied in fields such as biology, medicine, and intracytoplasmic sperm injection (ICSI). Microinjection process requires special skill and, thus, generally ICSI is conducted by embryologists. However, the shortage of embryologists has become a problem in clinics, and there is a need for an easy injection system that does not rely on embryologists. In this study, we propose a micromanipulation interface that assists to perceive cell extension for easy injection system. The proposed interface provides 2-dimensional force/tactile feedback through a fabric actuator with air pressure based on real-time visual sensing of cell deformation. The effectiveness of the proposed interface is verified through puncturing experiments on perceiving cell extension perfumed by inexperienced subjects.

Effect of anchoring groups number on the photovoltaic parameters in dye-sensitized solar cells

Abstract We have developed a series of Ru sensitizers (GS16, GS17 and GS19) with molecular architecture containing a tridentate ligand with one, two and three anchoring groups and three thiocyanates. Furthermore, we have studied the effect of the number of carboxylic groups on photovoltaic properties. The absorption spectra of the novel sensitizers extended up to the red region (900 nm). The electrochemical studies reveal that the oxidation potentials are aligned below the iodine-based redox potential, feasible for easy regeneration, and the lowest unoccupied molecular orbital of all sensitizers lies above the TiO2 conduction band, which is favourable for easy electron injection. The overall efficiency (η) of the GS16, GS17 and GS19 is 1.13, 2.71 and 1.59% with short-circuit current (JSC) of 3.74 mA cm−2, 7.08 mA cm−2, 6.27 mA cm−2, open-circuit voltage (VOC) of 0.42 V, 0.54 V and 0.39 V and fill factor of 0.70, 0.70 and 0.65, respectively. The highest efficiency of 2.71% was observed in GS17, bearing the two anchoring groups compared to one and three carboxylic acid-containing sensitizers (GS16 and GS19). Theoretical studies are also examined and matched with the experimental data.

A simple technique for suprachoroidal space injection of triamcinolone acetonide in treatment of macular edema.

To introduce a simple resistance controlled suprachoroidal space (SCS) injection technique using a disposable 30-gauge needle connected to a 1 mL syringe and evaluate the effectiveness and applicability of this technique in the treatment of macular edema. A total of 20 patients with various types of macular edema were subjected to a resistance controlled SCS injection of triamcinolone acetonide (TA) with a disposable 30-gauge needle connected to a 1 mL syringe. This technique allows the easy and smooth injection of the TA only once the tip of the needle reached the potential SCS which was indicated by the lower resistance on the plunger. The main outcome measures were anterior segment spectral-domain optical coherence tomography (AS-OCT) measurements post-operation immediately and central subfield thickness (CST), best-corrected visual acuity (BCVA), and intraocular pressure (IOP) measurements at 3mo post-operation. AS-OCT examination showed the expansion of the SCS near the injection site immediately after SCS injection. At three months of follow-up, as compared to the baseline, the mean CST was significantly decreased from 535.0±157.24 to 319.55±127.30 µm (P<0.001), the mean BCVA was significantly improved from 1.05±0.41 to 0.73±0.41 logMAR (P<0.001), and the mean IOP was not significantly different, from 15.05±2.54 to 15.85±3.60 mm Hg (P=0.185). Any complication related to the injection procedure including cataract, choroidal and retinal hemorrhage, retinal detachment, or endophthalmitis was not observed in this study. The simple and minimally invasive technique of SCS injection of TA with a disposable 30-gauge needle connected to a 1 mL syringe is useful and applicable for macular edema.

Electrically driven on-chip transferrable micro-LEDs

In this study, we report the experimental demonstration of electrically driven on-chip transferrable microdisk light-emitting diodes (LEDs). A vertical p–i–n doped AlGaInP microdisk, including multi-quantum-well structures, is top-down-fabricated, on-chip micro-transferred, and converted into single micro-LEDs. Optically transparent and mechanically flexible multilayered graphene sheets are judiciously designed and introduced to the top and bottom surfaces of a single microdisk, thereby forming the top and bottom contacts. Using electroluminescence measurements, the fabricated micro-LEDs are characterized; they exhibit diode-like transport behaviors, spectroscopic light-out vs current (L–I) characteristics, and polarization-resolved emission properties. We believe that the proposed all-graphene-contact approach offers a direct and easy current injection scheme and further helps electrify various on-chip transferrable microarchitectures.

Development of re-crosslinkable dispersed particle gels for conformance improvement in extremely high-temperature reservoirs

Micro-scale and nano-scale dispersed gel particles (DPG) are capable of deep migration in oil reservoirs due to their deformability, viscoelasticity, and suitable particle size. Therefore, it has been widely studied and applied in reservoir conformance control in recent years. However, for highly permeable channels, their plugging performance is still limited. In addition, conventional in situ cross-linked polymer gels (ISCPGs) have fast gelation time under extremely high-temperature conditions, which often causes problems such as difficulty in pumping. Therefore, a re-crosslinkable dispersed particle gel (RDPG) system applied for conformance control in highly permeable channels of extremely high-temperature petroleum reservoirs was investigated. The particle size distribution, gelation time, gel strength, injection performance, and performance strength in porous media were investigated using a laser particle size meter, the Sydansk bottle test method, rheometer, and core displacement experiments, respectively. Results show that the RDPG suspension can be stable for more than 6 months at room temperature with storage modulus G ′ much lower than 10 Pa. It can pass through the pore throat by elastic deformation effect and does not cause strong blockage. Moreover, it can undergo re-crosslinking reaction at 150 °C to form a strong bulk gel. The gel strength G ′ of re-crosslinked RDPG can be as high as 69.3 Pa, which meets the strength requirement of conformance control. The RDPG suspension has the properties of easy injection, and it also has strong plugging, and high-temperature resistance after re-crosslinked in the core, which can be a very promising material for conformance improvement in extremely high-temperature reservoirs.