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Magnesium (Mg) has many unique properties. The present review highlights the basic properties of Mg and its application in energy processes such as photocatalysis, electrocatalysis, energy storage, solar harvesting, hydrogen storage, plasmonic, and sensing.

As part of well cost reduction initiative, screenless fracpack has been successfully applied in Field D in which gravelpack or fracpack have been the prevalent sand control completion methods. This paper discusses the first application of screenless fracpack in Malaysia with description on design process, implementation method, challenges in design and execution, production performance, and the recommended way forward. Typical gravel pack or fracpack would require installation of downhole screen and packer assemblies, followed by gravel pack or fracpack pumping. The associated cost ranges from USD 1 million to USD 2 million for a multi-zone well. However, screenless fracpack application eliminates the high-cost screen and packer assemblies. Perforations are made with vertically oriented 0-180 degree phasing (up and down) to maximize fracture alignment with perforations as well as to minimize potential sand production from the perforations without fracture. Subsequently, perforations and near wellbore matrix are treated with resin injection to consolidate near wellbore formation in ensuring good sand/fines control in formation that is not fractured. Hydraulic fracturing utilizes tip screen out method to create short fracture length and wide fracture width to maximize dimensionless fracture conductivity. Proppant can be resin coated or treated with network of fibers to control proppant flowback in absence of downhole screen assemblies. All planned procedures have been successfully conducted. Perforations were made in a short interval i.e. about 2m in length with limited entry 4 SPF/ 0-180 degree phasing. Dynamic underbalance technique was incorporated to maximize open perforations effectively. Resin injection plan was dropped due to low permeability and low injectivity. Resin squeeze into a tight formation can end with either incomplete resin and overflush injection, or fracturing with the viscous resin, either of which would damage the formation. A highly conductive fracture has been created with tip screen out. Nolte Smith log-log plot showed a unit slope, an indication of tip screen out. Proppant flowback control was obtained with resin coated proppant. Post screenless fracturing, the well was carefully unloaded and cleaned. Well production showed good productivity and effective sand control. Currently, other fields are being studied and considered for the same application. Screenless fracpack is applied for the first time in a field offshore Malaysia. It is a bold step change whereby gravelpack or fracpack are commonly used as sand control. The application was driven by well cost reduction effort and the application is currently considered for replication in other fields. The benefit of the new method is not only the well cost savings by elimination of screen and packer assemblies, but it also provides full bore access and simpler well interventions. This application helps in brownfield and marginal field development whereby small reserves may negatively project economics due to high cost for gravelpack or fracpack installation.

This paper serves to share the findings and best practices of sustaining production for a mature field with high sand production with analysis from Acoustic Sand Monitoring (ASM) paired with Online Sand Sampling (OSS). Field B, located in the East Malaysia Region, is a high oil producer for over 40 years under a strong water drive mechanism. Water production has significantly increased over the past 5 years, which has led to significant sand production impacting surface facilities and well integrity. Hence, the need for a reliable and efficient sand management surveillance in field B. As the first application for oil fields in the region, ASM and OSS was conducted with the objective to determine the maximum sand free production rate from over 80 active strings in Field B over the span of 4 months to safeguard production rates of 10 kbopd. With ASM and OSS, a reduced data surveillance duration can be achieved within 2 hours compared to conventional well sand sampling per well which requires a minimum of 24 hours before sand production rate is determined. ASM sensors are clamped on the well flowline to detect and record the noise vibrations produced by the sand while OSS is conducted concurrently by diverting parts of the same flow from the flowline through a sand filter to have a quantitative representation of sand produced for a predetermined duration. During the campaign, choke sizing was manipulated to control reservoir drawdown. For most wells, a lower drawdown resulted in lower amplitude readings from ASM and less sand observed from OSS. However, there are several wells that had higher sand production at a smaller drawdown due to a change in flow regime (steady flow to intermittent flow) resulted from inefficient gas lift production (multi-pointing). As ASM provided the raw velocity signal which is heavily influenced by the liquid flow regime, gas oil ratio and sand production, OSS results (from physical sand produced and weight of sand particles) established a baseline for ASM signals which indicate a sand free production. Overall, ASM and OSS analysis provided a baseline for determining the optimum rate of production with minimum sand to avoid well integrity issues and protecting the surface facilities, thus allowing continuous field production of 10 kbopd. A presentation and discussion of the successful results, limitations, best practices, and lessons learnt of the ASM and OSS campaign aspires to be additive to the production surveillance sand management in the oil and gas industry by providing a fast and reliable means of identifying optimum sand free production rates for a high number of wells in a mature field.

Recently, enormous culture profiles and datasets from biomanufacturing processes to produce recombinant therapeutic proteins (RTP) such as monoclonal antibodies (mAbs) could be generated by virtue of the advancement in process analytical techniques and artificial intelligence (AI). Thus, now it is highly necessary to develop AI-based data-driven models (DDMs) and exploit them accordingly in order to further enhance operational efficiency and accelerate reliable product supply. Since bioprocess is a complex and dynamic system, DDMs are practical and particularly useful to describe the intrinsic relationship among biological and process parameters and cell culture conditions by capturing inherent patterns and to produce high-quality RTP under consistent operations as well as to decrease cost and time by predicting incipient or abrupt faults during the cell cultures. In this work, we provide the practical guideline for choosing the best DDM on given mAb-producing Chinese hamster ovary (CHO) cell culture data sets, enabling us to forecast culture performance such as VCD, and mAb titer as well as glucose, lactate and ammonia concentrations in real time manner. Via the case study with 32 fed-batch data sets of CHO cell cultures, we suggested best combination of model elements including AI algorithms and multi-step ahead forecasting strategies, for good prediction in terms of the computational load as well as the model accuracy and reliability, which is applicable to implementation of interactive data-driven model within bioprocess digital twins. We believe this systematic study can help bioprocess engineers to start developing predictive DDMs with their own data and learn how their cell cultures behave in near future, thereby making proactive decision possible.

Background: Although spinal cord stimulation (SCS) can be a treatment option for intractable postherpetic neuralgia (PHN), obtaining proper stimulation at the thoracic dermatome is difficult. Dorsal root ganglion (DRG) stimulation may be an effective treatment for patients with insufficient efficacy in SCS only.Case: A 54-year-old man with intractable PHN was referred to our clinic. Pain was localized to the distribution of the T1–3 dermatomes. SCS trial was conducted, and lead was placed within the epidural space over the C6–T1 level; however, the stimulation was inadequate for his pain site. Therefore, another lead was placed within the left T1 and T2 DRG for trial, and T1 DRG stimulation provided adequate stimulation. T1 DRG stimulation and SCS could cover the entire pain site with paresthesia, and his pain was decreased by over 50%.Conclusions: DRG stimulation combined with SCS may be a good treatment option for intractable thoracic PHN.

The literature survey revealed that limited prior investigations exist on the two-phase refrigerant distribution for a horizontal header/horizontal mini-channel tube configuration, which is of importance in many heat exchange circumstances including the cooling of an electric vehicle battery. In this study, we investigated R-1234yf distribution into two mini-channel tubes from a header. Especially, the focus was concentrated on the effect of inlet and outlet configuration on the flow distribution. The tests were conducted for the mass flux from 49 to 147 kg/m2s and the inlet quality from 0.2 to 0.8. The effect of the inclination of the heat exchanger was also investigated. The flow distribution was mainly governed by the balance of the relating forces – momentum, centrifugal and gravitational. Thus, poor distribution was obtained at a tilted case, where the momentum and centrifugal forces were assisting. The flow distribution was also highly dependent on the inlet configuration. On the other hand, the effect of outlet configuration was of secondary importance. The parallel inlet induced a significant mal-distribution compared with the normal inlet, especially in the channel away from the inlet, where an early dry out in the channel was observed. A flow distribution correlation was developed, which predicted the data within ± 30%.

PETRONAS completed Well H16 in BS field, East Malaysia with a Digital Intelligent Artificial Lift (DIAL) – an improvement to the current applied gas lift system in the field for production optimization system. This DIAL installation represents the first ever successful installation of the technology in an Offshore oil well for Dual String production. This paper provides the details of the installation planning, designing stages, operational process, well unloading and production undertaken to achieve this milestone. DIAL is a unique technology that enhances the efficiency of gas lift production. Downhole monitoring of production parameters informs remote surface-controlled adjustment of gas lift valves. This enables automation of production optimization removing the need for well intervention which will be challenging in high deviation well (more than 60-degree deviation). With remotely operated, non-pressure dependent multi-valve units, the technology removes the challenges normally associated with gas-injected production operation in a dual completion well i.e., gas robbing and multi-pointing. DIAL introduces a paradigm shift in design, installation and operation of gas lifted wells. This paper will briefly highlight the justifications of this digital technology in comparison with conventional gas lift techniques. It will consider value added from the design stage, through installation operations, to production optimization. Digitization and automation have become the new concepts in managing the operations in order to boost efficiency that reflected in long-term cost savings especially in Operating Expenditure (OPEX). This paper focusses on a well completed in November 2020, the fourth well to be installed with the DIAL technology across PETRONAS Assets. The authors will provide details of the well strategy, installation process and production phases: system design, pre-job preparations, improvements implementation, run in hole and surface hook-up. The results of well unloading while utilizing the DIAL system to start up the well and lifting the completion brine will be explained in detail in this paper. For each phase, challenges encountered, and lessons learned will be listed together with observed benefits. Despite the additional operational & planning complications due to COVID-19 restrictions, the well was completed with zero Non-Productive Time (NPT) and Loss Time Injury (LTI). Once brought online, this DIAL-assisted production well can be remotely monitored and controlled ensuring continuous production optimization, part of PETRONAS’ upstream digitization strategic vision.

In this study, we investigated the R-1234yf distribution from a header into mini-channel tubes located in a horizontal plane, which may be of importance for cooling of an electric vehicle battery. Especially, the focus was concentrated on the effect of number of branch tubes on the two-phase distribution. The tests were conducted for the mass flux from 49 to 147 kg/m2s and inlet quality from 0.2 to 0.8. The effect of heat exchanger inclination was also investigated. The results showed that the flow distribution worsened as the number of branch tube increased. Between the normal and the parallel inlet configuration, the normal inlet yielded a better distribution, probably due to the smaller number of branch tubes. The flow distribution was mainly governed by the balance of relating forces-momentum and gravitational. Thus, a poor distribution was obtained for a tilted case, where the momentum and the gravitational forces were assisting. The data showed that a vapor quality was always beneficial to the distribution. However, the effect of mass flux was case-dependent. For the horizontal case, the mass flux pushed the flow downstream, and worsened the distribution. For the tilted case, the mass flux assisted or opposed the gravity, yielding a better distribution.

The literature survey reveals that the studies on evaporation of an alternative refrigerant for R-404A are lacking. In this study, four R-404A alternative refrigerants - two short term refrigerants (R-448A, R-449A) and two long term refrigerants (R-455A, R-454C) - including R-404A were tested in a 7.0 mm O.D. microfin tube. The tests were conducted changing the mass flux from 90 to 300 kg m−2s−1, heat flux from 5 to 15 kW m−2 and vapor quality from 0.2 to 0.8. During the test, the saturation temperature was maintained at 10 °C. The heat transfer coefficients of R-404A were higher than those of the alternative refrigerants. However, the difference tended to decrease as the mass flux increased. The higher heat transfer coefficient of R-404A may be due to the smaller temperature glide of R-404A as compared with those of other refrigerants. The microfin / smooth tube heat transfer enhancement ratios of the alternative refrigerants ranged from 1.14 to 1.93. With the mixture correction, pure refrigerant correlations successfully predicted the mixture refrigerant data.

The literature shows that condensation study of R-404A-alternative refrigerants in a microfin tube is lacking. In this study, four R-404A-alternative refrigerants—two short-term (R-448A, R-449A) and two long-term refrigerants (R-455A, R-454C) including R-404A—were tested in a 7.0-mm outer-diameter microfin tube. Tests were conducted over a mass flux range of 80 to 400 kg m−2s−1. At a low mass flux (of up to 200 kg m−2s−1), the heat-transfer coefficients of the alternative refrigerants were 25–31% lower than those of R-404A. As the mass flux increased to 400 kg m−2s−1, the heat-transfer coefficients of the alternative refrigerants were similar to those of R-404A. Of the alternative refrigerants, the long-term refrigerants (R-455A, R454C) yielded 1.2–32% smaller heat-transfer coefficients than the short-term refrigerants (R-448A, R-449A), due to larger (by 46–126%) temperature glides. On the other hand, the pressure drops of alternative refrigerants were 18–205% larger than those of R-404A. Long-term refrigerants (R-454C, R-455A) yielded 14–64% larger pressure drops than short-term refrigerants (R-448A, R-449A), likely due to a smaller vapor density. The enhancement ratios (hmicro/hsm: heat transfer coefficient of the microfin tube over that of the smooth tube) of the alternative refrigerants varied from 1.24 to 1.89. The penalty factors [dP/dz)f,micro/dP/dz)f,sm: frictional pressure drop of the microfin tube over that of the smooth tube] ranged from 1.03 to 3.17, showing a wide variation among refrigerants. A comparison with existing correlations revealed that the correlation of Kedzierski and Goncalves (1999) predicted 76% of the heat-transfer coefficients and that of Nozu et al. (1998) predicted 73% of the frictional pressure drops within ± 30.0%.

In this work, we fabricate porous cesium lead bromide nanofibers (CsPbBr3 NFs) via electrospinning and employ them in a sensor to effectively detect both gaseous and aqueous ammonia. The CsPbBr3 NFs are produced by first mixing cesium lead bromide nanocrystals (CsPbBr3 NCs) with polystyrene (PS), followed by solidifying the mixture into NFs using electrospinning. Porous NFs are modified using the volatile solvent toluene, which is volatilized during the electrospinning process. The applicability of the proposed CsPbBr3 NFs for use under various environmental conditions is verified by analyzing their stability in response to changes in temperature, moisture level and pH, which are critical drawbacks of CsPbBr3 NCs. Gaseous ammonia (9 mg L−1) in an N2 carrier is subsequently detected using the photoluminescence (PL) properties of the CsPbBr3 NFs. In addition, an ammonia concentration of 100.0 mg L−1 in an aqueous solution can be detected using the PL intensity. Therefore, we believe that the proposed CsPbBr3 NFs show significant promise for use in detection sensors to assess the extent of food decay, allowing customers to purchase fresh agricultural products more safely.

Quasiparticle interference (QPI) patterns in momentum space are often assumed to be independent of the strength of the impurity potential when compared with other quantities, such as the joint density of states. Here, using the $T$-matrix theory, we show that this assumption breaks down completely even in the simplest case of a single-site impurity on the square lattice with an $s$ orbital per site. Then, we predict from first-principles, a very rich, impurity-strength-dependent structure in the QPI pattern of TaAs, an archetype Weyl semimetal. This study thus demonstrates that the consideration of the details of the scattering impurity including the impurity strength is essential for interpreting Fourier-transform scanning tunneling spectroscopy experiments in general., Comment: main manuscript: 8 pages, 6 figures, Supplementary Information: 3 pages, 6 figures

The collapse of Landau levels under an electric field perpendicular to the magnetic field is one of the distinctive features of Dirac materials. So is the coupling of lattice deformations to the electronic degrees of freedom in the form of gauge fields which allows the formation of pseudo-Landau levels from strain. We analyze the collapse of Landau levels induced by strain on realistic Weyl semimetals hosting anisotropic, tilted Weyl cones in momentum space. We perform first-principles calculations, to establish the conditions on the external strain for the collapse of Landau levels in TaAs which can be experimentally accessed., Comment: 9 pages, 6 figures

Many physical quantities in solid-state physics are calculated from k-space summation. For spectral functions, the frequency-dependent factor can be decomposed into the energy-conserving δ-function part and the nondissipative principal value part. A very useful scheme for this k-space summation is the tetrahedron method. Tetrahedron methods have been widely used to calculate the summation of the energy-conserving δ-function part, such as the imaginary part of the dielectric function. On the other hand, the corresponding tetrahedron method for the nondissipative part, such as the real part of the dielectric function has not been used much. In this paper, we address the technical difficulties in the tetrahedron method for the nondissipative part and present an easy-to-implement stable method to overcome those difficulties. We demonstrate our method by calculating the static and dynamical spin Hall conductivity of platinum. Our method can be widely applied to calculate linear static or dynamical conductivity, self-energy of an electron, and electric polarizability, to name a few., This work was supported by the Creative-Pioneering Research Program through Seoul National University, Korean NRF No-2020R1A2C1014760, and the Institute for Basic Science (Grant IBSR009-D1). Computational resources were provided by KISTI Supercomputing Center (Grant No. KSC-2020-INO-0078).

T field has very unconsolidated sand with high nonuniformity and high fines contents in H and I sands and require robust sand control, typically Internal gravel pack (IGP). Historically, around 90% wells have been completed with IGP completion and are producing sand free for the last 20-30 years. This paper describes on the first slim (3") open hole standalone screen (OHSAS) completion application and performance which can be utilized for replication in future infill wells. Around 10% remaining wells have been completed with OHSAS completion across highly deviated wells in H and I sands in T field. The screens have been designed based on d10 sand particle size and sand retention test (SRT) and typically installed in 8 ½" open hole. The drill-in fluid (DIF) has been properly designed to create temporary filter cake across the wellbore and then it is designed to break by either lift-off pressure or by usage of mud cake breaker depending upon the type of DIF system. The OHSAS wells are producing good with sand free production since last seven to fourteen years. The OHSAS performances for all wells in T field have been investigated. The investigation has provided suggestions for further improvement in future projects. Based on the investigation, OHSAS completions in T field has good OHSAS design and production performance, though further improvement can be done in its execution for future projects like monitoring total soluble clays using Methylene Blue Test (MBT) during drilling reservoir sections, maintaining its solubility more than 70% all throughout, use of proper mud cake breaker, etc. This paper explains details on the outcome of the investigation and recommendations, and data requirement to assess successful OHSAS completions with the help of tables and charts. The applicability of OHSAS has been re-studied in future infill wells and have been included in the next field development plans. This paper presents on the OHSAS design, execution and performance, best practices, reviews and suggestions for further improvement in future infill wells, then its applicability and replication in future projects.

Pyrolysis fuel oil (PFO) is used for the manufacturing of high-purity pitch for carbon precursor due to its high carbon content, high aromaticity, and low heterogeneous element and impurity content. Pitch is commonly classified with its softening point, which is most considerable physical property affecting to various characteristics of the carbon materials based on pitch, such as electrical and thermal conductivity, mechanical strength, and pore property. Hence, the softening point should be controlled to apply pitch to produce various carbon materials for different applications. Previous studies introduce reforming process under high pressure and two step heat treatment for the synthesis of pitch with high softening point from PFO. These methods lead to a high process cost; therefore, it is necessary to develop a process to synthesize the pitch with high softening point by using energy effective process at a low temperature. In this study, waste polyethylene terephthalate (PET) was added to control the softening point of PFO-based pitch. The pitch synthesized by the heat treatment with the addition of PET showed the softening point higher than that of the pitch synthesized with only PFO. The softening point of PFO-based pitch synthesized at 420 °C was 138.3 °C, while that of the pitch synthesized by adding PET under the same process conditions was 342.8 °C. It is proposed that the effect of the PET addition on the increase in the softening point was due to the radicals generated from thermal degradation of PET. The radicals from PET react with the PFO molecules to promote the polymerization and finally increase the molecular weight and softening point of the pitch. In addition, activated carbon was prepared by using the pitch synthesized by adding PET, and the results showed that the specific surface area of the activated carbon increased by the addition of PET. It is expected that the pitch synthesis method with PET addition significantly contributes to the manufacture of pitch and activated carbon.

Controllable synthesis of graphene-coated metal nanoparticles (NPs) presents a major challenge when considering the practical application of these catalysts. Herein, we use silica as a radical sieve to grow graphene over cobalt NPs via chemical vapor deposition. As-prepared single-layer graphene-coated cobalt NPs with and without N doping (Co@N-SG and Co@SG) exhibit noticeable oxygen evolution reaction (OER) activity. Furthermore, a magnet-assisted binder-free Co@N-SG electrode illustrates much improved OER activity and stability over conventional binder-assisted counterparts, suggesting this as an effective way to overcome the recognized issues of high electron transfer resistance and poor adhesion of binder-based electrodes in practical applications. Interestingly, the graphene shell possesses varying defects and major OER benefitting active sites are found around said defects in the shell, while separately isolated Co@SG with a defect-free shell, despite exhibiting a slightly lower initial activity, illustrates a much-improved durable OER performance. The underlying Co affects the electron density of the graphene shell through dipole interaction and the electron density is optimized for adsorption of reaction intermediates, hence accelerating OER performance. This work will provide new clues to design efficient and durable electrocatalysts with further enhanced OER performance.

Searching for low-cost and highly active bifunctional electrocatalysts toward hydrogen/oxygen evolution reactions is a grand challenge for water splitting hydrogen production. Herein, we prepare a trimetallic nickel, iron, and molybdenum phosphide (FeNiMoP) grown on nickel foam (NF) via a facile two-step process and employ it as a bifunctional electrocatalyst for full water splitting. In virtue of the superior hydrogen/oxygen evolution activity, the cell with the bifunctional FeNiMoP as both anode and cathode exhibits an initial low cell voltage of 1.50 V at a current density of 10 mA cm−2 in 1.0 M KOH electrolyte solution. Impressively, the full cell voltage decreases to 1.44 V through favorable self-reconstruction on both the anode and cathode during the electrocatalytic overall water splitting process. On the anode side, the FeNiMoP is transformed into FeNiOOH while Mo and P elements are dissolved into the electrolyte. Such transformation leads to a continuously increasing active surface area, and the dissolved Mo forms MoO42− in the electrolyte which improves the OER performance. On the cathode side, the dissolution and re-deposition of Mo oxides on the surface of the electrode greatly increase the active surface sites towards the electrolytes, and the surface absorbed Mo oxides play key roles, leading to a positive effect on HER performance. The new synthesis strategy, taking advantage of favorable structural self-reconstruction in the catalysts can be extended to other catalytic systems.

R-134a distribution in an evaporator having two-row/six-pass configuration was experimentally studied with the inlet quality 0.2 and the outlet superheat 5°C. The mass flux was varied from 63 kg/m2...

Background Fever is a common cause of pediatric consultation in the emergency department. However, identifying the source of infection in many febrile infants is challenging because of insufficient presentation of signs and symptoms. Meningitis is a critical cause of fever in infants, and its diagnosis is confirmed invasively by lumbar puncture. This study aimed to evaluate potential laboratory markers for meningitis in febrile infants. Methods We retrospectively analyzed infants aged 10 mg/L.