Transient Effects Research Articles

Locally released dexamethasone and its effects on osteogenic activity at implant-tissue interface.

The osseointegration of titanium implants within the host tissue holds crucial importance. The introduction of functional coatings at tissue-implant interface enhances the bioactivity of titanium implants, improves their therapeutic outcomes, and enhances the effectiveness of treatments. In this study, we focused on enhancing the bioactivity of titanium-based implant materials by coating the titanium surfaces with chitosan microspheres, which are loaded with osseointegration-promoting agent dexamethasone (DEX). Initially, chitosan microspheres were successfully produced, followed by DEX loading through diffusion, resulting in a drug loading efficiency of around 50.2 (wt %). The subsequent drug release profile displayed a 24-hour duration, releasing approximately 32.6 (wt %) of the loaded DEX. In cell proliferation assays using human osteosarcoma (SAOS-2) cells, Ti surfaces coated with DEX-loaded chitosan microspheres initially exhibited lower cell numbers compared with DEX-free ones. This observation was attributed to transient osteogenic differentiation effects of DEX, since a notable increase in cell proliferation was observed on the 7th day. Von Kossa staining revealed mineralization beginning on the 14th day, particularly evident in DEX-loaded samples. Moreover, alkaline phosphatase (ALP) activity displayed a pattern of initial increase and subsequent decrease, with DEX release from chitosan microspheres showing a clear influence on the osteogenic differentiation, especially on the 7th day. These findings align with literature, highlighting DEX's potential to enhance osteogenic differentiation and cellular behavior on chitosan microsphere-coated titanium surfaces. This study emphasizes the promising implications for functionalizing surfaces of implant materials with DEX-loaded chitosan microspheres to improve their biocompatibility and bioactivity.

ID: 341296 Transient Effects in Transsynaptic Modulation of the Cerebellar Nuclear Cells during theta-gamma Stimulation

ID: 341296 Transient Effects in Transsynaptic Modulation of the Cerebellar Nuclear Cells during theta-gamma Stimulation

Study on the transient cavitation characteristics in an axial flow tandem pump during the rapid starting period

Abstract In axial flow pump systems constrained by limited internal space, the advantages of axial flow tandem pumps are high space utilization, strong power capacity, and great thrust. The onset of cavitation during the rapid starting period poses a classic issue for tandem axial flow pumps, resulting in issues like noise, vibration, cavitation breakdown, and material damage. This article aims to investigate the transient cavitation characteristics of each flow passage component of an axial flow tandem pump during the rapid starting period by numerical simulation method. It is compared that the evolution laws of the cavity of each flow passage component. The evolution of the cavity in all flow passage components is strongly correlated with the flow rate change rate in each stage of the rapid starting period. Among all flow passage components, the first impeller firstly experiences cavitation, and its cavitation severity is also the most severe. The Effective Net Positive Suction Head (NPSHa ) can reduce the influence of transient effects on cavity prediction and better characterize the details of the cavity evolution in different impellers than the cavitation number σ during the rapid starting period. Meanwhile, The NPSHa of the second impeller inlet is always higher than that of the first impeller inlet, indicating superior cavitation performance for the second impeller.

Why Does Atmospheric Radiative Heating Weaken Midlatitude Cyclones?

AbstractRecent work has indicated that atmospheric radiative heating reduces the kinetic energy of large‐scale eddies in the midlatitudes. However, a physical mechanism that connects radiation to the midlatitude eddy kinetic energy is still uncertain. Using a high‐resolution general circulation model we perform an experiment in which the radiative cooling profile at each model time step is overwritten with the climatological mean, computed from a control simulation. This approach separates the mean and transient effects of radiative heating on the extratropical circulation. We find that, when radiative heating is fixed, the globally‐averaged eddy kinetic energy is enhanced by ∼6%. We show that thermal radiation dampens temperature anomalies near the surface and tropopause in low‐pressure systems, destroying eddy available potential energy and eddy kinetic energy. We identify this as a possible mechanism by which atmospheric radiative heating weakens midlatitude cyclones.

Innovative Approaches to Expansion Loop Design for Enhanced Piping System Durability

Expansion loops are critical components in piping systems, designed to manage stress caused by thermal expansion and contraction, thereby ensuring the system's durability and safety. This study investigates innovative approaches to optimizing expansion loop design, focusing on improving the performance and reliability of piping systems under various operational conditions. The research examines multiple configurations, including alterations in loop length, shape modifications, and the incorporation of additional loops, to assess their impact on stress distribution within the system. While the primary focus of this study is on static stress analysis, transient operational factors, such as water hammer, were also considered in the analysis to provide a more comprehensive understanding of the loop configurations' performance under various conditions. The findings demonstrate that while increasing the loop length can effectively reduce stress, alternative designs, such as double loops or modified shapes, offer superior stress management, particularly in space-constrained environments. The study concludes that optimal expansion loop design should accommodate thermal expansion and provide robustness against potential transient effects, contributing to a more reliable piping system. These insights provide valuable guidelines for the design and optimization of piping systems across various industrial applications.

Investigation of unsteady Buongiorno nanofluid in a slanted thermally radiated revolving channel under upstream microbial movement in the absence of chemical reaction

Analysis of Buongiorno nanofluid in a thermally radiated channel in the occurrence of microbes is an enrich research motive. Thermal radiations, dissipation energy, transient effects and upstream microbial acceleration potentially alter the performance of Buongiorno nanofluid. This is a two phase nanofluid model which accommodates the thermophoretic and Brownian movement of the particles along with other integrated physical quantities. Hence, the current research aims to conduct the study of Buongiorno nanofluid in a slanted thermally radiated micro channel in the presence of aforementioned physical phenomenon. The outcomes of the model achieved numerically and discussed deeply. It is investigated that the unsteady and channel revolving parameters enhances the nanofluid movement while adjusting the channel at different inclination also favors the velocity. The velocity G(η) upsurges for larger rotation of the channel while it drops for more transient fluid. Further, the thermophoretic and particles deposition boosts the thermal performance of the setup while thermal radiations depreciated the efficiency. The Schmidt effects in the range of 1.0–7.0 highly contributes in the improvement of mass transport. Moreover, density motile of microbes improved for Lewis and transient effects while Peclet effects are examined excellent to control the microbial influence.

Using Carbon Dioxide for Subsea Long-Duration Energy Storage

This paper investigates the operating benefits and limitations of utilizing carbon dioxide in hydro-pneumatic energy storage systems, a form of compressed gas energy storage technology, when the systems are deployed offshore. Allowing the carbon dioxide to transition into a two-phase fluid will improve the storage density for long-duration energy storage. A preliminary comparative study between an air-based and a carbon dioxide-based subsea hydro-pneumatic energy storage system is first presented. The analysis is based on thermodynamic calculations assuming ideal isothermal conditions to quantify the potential augmentation in energy storage capacity for a given volume of pressure containment when operating with carbon dioxide in lieu of air. This is followed by a transient thermal analysis of the carbon dioxide-based hydro-pneumatic energy storage system, taking into account the real scenario of a finite thermal resistance for heat exchange between the gas and the surrounding seawater. Results from numerical modelling revealed that the energy storage capacity of a carbon dioxide-based subsea hydro-pneumatic energy storage system operating under ideal isothermal conditions can be theoretically increased by a factor of 2.17 compared to an identical air-based solution. The numerical modelling revealed that, under real conditions under which transient effects resulting from a finite thermal resistance are accounted for, the achievable factor is lower, depending on the charging and discharging time, the initial temperature, and whether a polyethene liner for corrosion prevention is considered or not.

Improvement of Single Event Transient Effects for a Novel AlGaN/GaN High Electron-Mobility Transistor with a P-GaN Buried Layer and a Locally Doped Barrier Layer.

In this paper, a novel AlGaN/GaN HEMT structure with a P-GaN buried layer in the buffer layer and a locally doped barrier layer under the gate (PN-HEMT) is proposed to enhance its resistance to single event transient (SET) effects while also overcoming the degradation of other characteristics. The device operation mechanism and characteristics are investigated by TCAD simulation. The results show that the peak electric field and impact ionization at the gate edges are reduced in the PN-HEMT due to the introduced P-GaN buried layer in the buffer layer. This leads to a decrease in the peak drain current (Ipeak) induced by the SET effect and an improvement in the breakdown voltage (BV). Additionally, the locally doped barrier layer provides extra electrons to the channel, resulting in higher saturated drain current (ID,sat) and maximum transconductance (gmax). The Ipeak of the PN-HEMT (1.37 A/mm) is 71.8% lower than that of the conventional AlGaN/GaN HEMT (C-HEMT) (4.85 A/mm) at 0.6 pC/µm. Simultaneously, ID,sat and BV are increased by 21.2% and 63.9%, respectively. Therefore, the PN-HEMT enhances the hardened SET effect of the device without sacrificing other key characteristics of the AlGaN/GaN HEMT.

Transient effects by pintle motion in cavitating venturi tube for throttled bipropellant thruster

An experimental study was conducted to investigate the behavior of an H2O2/kerosene bipropellant thruster during throttling. The thruster used 90 wt% hydrogen peroxide, and thrust was controlled using a variable area cavitating venturi valve equipped with a linear motor translating a pintle in a venturi geometry. In particular, transient effects were compared for three settings of pintle motion. Transient effects impacting pressure, temperature, thrust, efficiency, and instability data were analyzed. The results show that even at low chamber pressure, ignition occurred due to throttling, and no instabilities were created by changing the throttling speed. On the contrary, transient movements affected the recorded pressure data, impacting the characteristic velocity and thrust. Finally, this study provided new insight into H2O2/kerosene bipropellant throttling for deep throttling missions. Moreover, using the results from this study, the precision of future control algorithms will be improved.

A review of criticality dosimetry at the Y-12 National Security Complex and practical importance of dose accuracy in emergency response

A nuclear criticality results in the emission of both neutron and gamma radiation and can produce doses to personnel near the event that exceed 0.1 Gy (10 rad). The primary purpose of nuclear accident dosimetry is to rapidly identify affected personnel in need of prompt medical treatment and to reassure personnel who have been only minimally exposed. While accurate dosimetry is desired, it must be recognized that dose determinations made from whole-body dosimeters or simple triage methods are very rough estimates and contain significant uncertainties. Even when accounting for factors like varying neutron energy spectra, mean photon energies, body orientation within the radiation field, and transient effects on dosimeter response, etc., the end value is a dosimetric quantity defined for very specific radiological conditions and determined within a simple phantom usually at a single depth. Of more importance is the biological response to the radiation, which will vary by person and can be affected by the individual's radiation sensitivity, age, gender, mass, and underlying health conditions. The overall biological, person-specific response to a given dose cannot be precisely determined except by patient symptom observation and individual biological dosimetry (e.g. chromosome analysis, lymphocyte ratios, etc.). This work describes and discusses the criticality accident dosimetry program at the Y-12 National Security Complex, a United States Department of Energy National Nuclear Security Administration facility. The primary goals of the Y-12 accident dosimetry program are, among others, the rapid identification of significantly exposed persons, prompt routing of exposed workers for medical evaluation and treatment, and the ultimate processing of dosimeters to assign doses to personnel.

Concentrations of F−, Na+, and K+ in Groundwater before and after an Earthquake: A Case Study on Tenerife Island, Spain

Freshwater, vital for life and ecosystems, accounts for only 2.5% of Earth’s water, and is primarily located in polar caps, underground reservoirs, and surface water. Its quality varies due to environmental interactions, especially in groundwater. Tenerife, located in the Canary Islands, Spain, relies mainly on underground aquifers and tunnels capturing 51.6 cubic hectometers annually. Ensuring safe drinking water is a global challenge due to health risks from poor water quality, including diseases and cancer. Fluoride, sodium, and potassium are essential for health, and are mainly derived from groundwater as fluoride ions (F−) and sodium and potassium cations (Na+, K+). However, excessive F−, Na+, and K+ in drinking water is harmful. The World Health Organization limits F− to 1.5 mg/L, Na+ to 8.70 meq/L, and K+ to 0.31 meq/L. Geological, climatic, and human factors control the presence and transport of F−, Na+, and K+ in groundwater. Seismic events can impact water quality, with long-term effects linked to aquifer structure and transient effects from gas and fluid expansion during earthquakes. This study was motivated by a 3.8 mbLg earthquake in Tenerife in 2012, which allowed its impact on groundwater quality, specifically F−, Na+, and K− concentrations, to be examined. Post-earthquake, F− levels alarmingly increased to 8.367 meq/L, while Na+ and K+ showed no significant changes. This research quantifies the influence of earthquakes on increasing F− levels and evaluates F− reduction during low seismic activity, emphasizing the importance of water management on volcanic islands.

Exhaust purification of stoichiometric natural gas applications – A screening study on the impact of catalyst composition, reaction conditions and transient effects

A set of model catalysts with a variation of precious metal components comprising Pt, Pd or Pt/Pd on typical support materials (CeO2, Al2O3 and ZrO2) is evaluated in a gas mixture simulating the exhaust gas of stoichiometric natural gas-fueled engines. Three-way catalytic (TWC) performance, especially CH4 conversion, is assessed in λ-sweep as well as dynamic light-Off/light-Out tests, both with oscillating feed (1 s lean /1 s rich) implemented on a fully automated reactor system. The transient response of catalysts to changing redox potential is demonstrated in tests with varying lean/rich duration and pseudo-stationary tests. Time resolved data clearly indicate that performance and stability depend on both, precious metal composition as well as support material. Beyond screening of catalyst activity, the focus was on factors affecting the formation of undesired by-products (e.g. NH3, N2O) on hydrothermally aged catalysts. Aging severity was introduced as additional dimension in the design of the experimental study.

Prioritized adjustments in posture stabilization and adaptive reaching during neuromuscular fatigue of lower-limb muscles.

Neuromuscular fatigue (NMF) induces temporary reductions in muscle force production capacity, affecting various aspects of motor function. Although studies have extensively explored NMF's impact on muscle activation patterns and postural stability, its influence on motor adaptation processes remains less understood. This article investigates the effects of localized NMF on motor adaptation during upright stance, focusing on reaching tasks. Using a force-field perturbation paradigm, participants performed reaching movements while standing upright before and after inducing NMF in the ankle dorsiflexor muscles. Results revealed that despite maintained postural stability, participants in the NMF group exhibited larger movement errors during reaching tasks, suggesting impaired motor adaptation. This was evident in both initial and terminal phases of adaptation, indicating a disruption in learning processes rather than a decreased adaptation rate. Analysis of electromyography activation patterns highlighted distinct strategies between groups, with the NMF group showing altered activation of both fatigued and nonfatigued muscles. In addition, differences in coactivation patterns suggested compensatory mechanisms to prioritize postural stability despite NMF-induced disruptions. These findings underscore the complex interplay between NMF, motor adaptation, and postural control, suggesting a potential role for central nervous system mechanisms in mediating adaptation processes. Understanding these mechanisms has implications for sports performance, rehabilitation, and motor skill acquisition, where NMF may impact the learning and retention of motor tasks. Further research is warranted to elucidate the transient or long-term effects of NMF on motor adaptation and its implications for motor rehabilitation interventions.NEW & NOTEWORTHY We assessed motor adaptation during force-field reaching following exercise-induced neuromuscular fatigue (NMF) on postural muscles. NMF impaired adaptation in performance. Similarly, diverging activation strategies were observed in the muscles. No effects were seen on measures of postural control. These results suggest the remodulation of motor commands to the muscles in the presence of NMF, which may be relevant in settings where participants could be exposed to NMF while learning, such as sports and rehabilitation.

Virtual Reality (VR) Technology in Laparoscopy Surgery: The Effect of Large Viewing Angle from the Head-Mounted Display (HMD) and Laparoscopic Performance

Background: A vital component of laparoscopic surgery is its display monitor. The viewing angle of the laparoscopic monitor impacts on the performance of the surgeon. Given that head-mounted display (HMD), an integral part of Virtual Reality (VR) technology, offers a large viewing angle, this project aimed to determine the potential benefits of using HMD in performing laparoscopic tasks. Methods: 54 laparoscopic/endoscopic clinicians performed a simulated laparoscopic task with three different monitors (HMD, 21-inch and 15-inch monitor) in a random order. Duration of task, distance travelled by graspers and manipulation errors were recorded and analyzed. Simulation Sickness Questionnaires (SSQs) were also given to participants. Results: There were statistically significant differences in all performance metrics recorded across all groups when compared to each other (P<0.05). HMD had the longest task completion duration followed by 15-inch and 21-inch monitors. However, the distance travelled by the graspers and error rate was lowest in the HMD group followed by 21-inch and 15-inch monitors. The SSQ questionnaire showed that eye strain and headache are the two most common transient side effects recorded by users of HMD. Conclusion: The study shows that HMD users perform fewer mistakes and are more precise with the movement of graspers compared to other groups. As such, HMD has the potential to enhance laparoscopic performance. HMD is cost effective and has the added benefit of improving surgical ergonomics. Further research should focus on ensuring that HMD is a viable and safe alternative to conventional laparoscopic monitor as well as in identifying barriers to adoption.

Direct coupling of light to valley current

The coupling of circularly polarized light to local band structure extrema ("valleys”) in two dimensional semiconductors promises a new electronics based on the valley degree of freedom. Such pulses, however, couple only to valley charge and not to the valley current, precluding lightwave manipulation of this second vital element of valleytronic devices. Contradicting this established wisdom, we show that the few cycle limit of circularly polarized light is imbued with an emergent vectorial character that allows direct coupling to the valley current. The underlying physical mechanism involves the emergence of a momentum space valley dipole, the orientation and magnitude of which allows complete control over the direction and magnitude of the valley current. We demonstrate this effect via minimal tight-binding models both for the visible spectrum gaps of the transition metal dichalcogenides (generation time ~ 1 fs) as well as the infrared gaps of biased bilayer graphene ( ~ 14 fs); we further verify our findings with state-of-the-art time-dependent density functional theory incorporating transient excitonic effects. Our findings both mark a striking example of emergent physics in the ultrafast limit of light-matter coupling, as well as allowing the creation of valley currents on time scales that challenge quantum decoherence in matter.

Theoretical and experimental study on combustion response of aluminized solid propellant under acceleration effects

The combustion performance of solid propellants is significantly affected by the external operating parameters of rocket motors. In this paper, the combustion response characteristics of aluminized solid propellant under acceleration conditions have been studied theoretically and experimentally. A theoretical model of unsteady burning for aluminized solid propellant, considering transient heat transfer and acceleration effects, is developed based on the Zel'dovich-Novozhilov solid-phase energy conservation. The pressure-coupled responses of the solid propellant are also measured experimentally under different normal accelerations using the T-burner and centrifuge. The model is well validated by comparison with literature and experimental results. The unsteady burning of propellants is analyzed in detail, and the effects of acceleration and propellant properties on combustion response are investigated. The results show that there is a significant difference between the transient and quasi-steady burning rate under dynamic environments. As normal acceleration increases from 0 g to 1000 g, the fluctuation amplitude of the net heat flux on the burning surface continues to decrease, the magnitude of the pressure-coupled response peak decreases significantly by 69 %, and the frequency of the response peak shifts from 140 Hz to 230 Hz. Moreover, the pressure exponent and thermal conductivity plays a positive role in the pressure-coupled response. The model presented in this paper can be helpful for predicting the differences between flight and ground test performance and evaluating the combustion stability of solid rocket motors.

Liver-on-a-Chip Integrated with Label-Free Optical Biosensors for Rapid and Continuous Monitoring of Drug-Induced Toxicity.

Drug toxicity assays using conventional 2D static cultures and animal studies have limitations preventing the translation of potential drugs to the clinic. The recent development of organs-on-a-chip platforms provides promising alternatives for drug toxicity/screening assays. However, most studies conducted with these platforms only utilize single endpoint results, which do not provide real-time/ near real-time information. Here, a versatile technology is presented that integrates a 3Dliver-on-a-chip with a label-free photonic crystal-total internal reflection (PC-TIR) biosensor for rapid and continuous monitoring of the status of cells. This technology can detect drug-induced liver toxicity by continuously monitoring the secretion rates and levels of albumin and glutathione S-transferase α (GST-α) of a 3D liver on-a-chip model treated with Doxorubicin. The PC-TIR biosensor is based on a one-step antibody functionalization with high specificity and a detection range of 21.7ngmL-1 to 7.83 x 103ngmL-1 for albumin and 2.20ngmL-1 to 7.94 x 102ngmL-1 for GST-α. This approach provides critical advantages for the early detection of drug toxicity and improved temporal resolution to capture transient drug effects. The proposed proof-of-concept study introduces a scalable and efficient plug-in solution for organ-on-a-chip technologies, advancing drug development and in vitro testing methods by enabling timely and accurate toxicity assessments.

Comparison of Systemic Exposure Between Epinephrine Delivered via Metered-Dose Inhalation and Intramuscular Injection.

Background: Primatene® MIST, an epinephrine metered-dose inhaler (MDI), has long been questioned by some medical professionals for asthma treatment despite having been approved by the Food and Drug Administration. One of the primary reasons for their concerns stemmed from potential cardiovascular complications following epinephrine administration. However, the majority of documented cardiovascular complications seemed to occur following the injection route of the epinephrine. The aim of this study was to evaluate the systemic exposure of epinephrine delivered through different administration routes and to understand its relationship with cardiovascular effects. Since albuterol inhalers are commonly recommended for asthma, albuterol was also studied as a comparator drug. Method: A randomized, evaluator-blinded, three-arm crossover study was conducted in 28 healthy adult subjects to compare the profiles of systemic exposure for epinephrine delivered by MDI versus epinephrine intramuscular (IM) injection and albuterol MDI. Serially sampled plasma epinephrine and albuterol levels were measured and compared between treatment groups. Safety was assessed by adverse events, serial vital signs, electrocardiograms (ECGs), and clinical laboratory tests obtained at each crossover dosing visit. Results: Systemic exogenous drug exposure for inhaled epinephrine MDI (39 pg/mL × hour) was ∼9 times lower than that of epinephrine IM (435 pg/mL × hour) and 122 times lower than that of albuterol MDI (3453 pg/mL × hour) after dose normalization. The Cmax in epinephrine MDI (345 pg/mL) was approximately half of that of epinephrine IM (816 pg/mL) and that of albuterol MDI (681 pg/mL). Plasma drug concentrations for epinephrine MDI dropped rapidly to baseline (∼0.6 hour), while epinephrine IM took ∼8 hours, and albuterol MDI required more than 24 hours. Epinephrine MDI and albuterol MDI resulted in minimal, clinically insignificant changes in vital signs and ECGs, whereas epinephrine IM led to mild transient increases in systolic blood pressure, heart rate, and corrected QT interval. Conclusion: Epinephrine MDI (Primatene MIST) had ∼9 times lower systemic drug exposure (SDE) than that of epinephrine IM and ∼122 times lower than that of albuterol MDI. The lower SDE of inhaled epinephrine also correlated with reassuring safety findings, with no significant cardiovascular adverse effects found, compared with transient effects seen after IM epinephrine. Clinical trial registration number: NCT04207840.

Photodynamic therapy in management of cutaneous leishmaniasis: A systematic review.

This systematic review evaluated the efficacy and safety of photodynamic therapy (PDT) in the management of cutaneous leishmaniasis (CL). The electronic search for identification of relevant studies, adhered to the PICOS (Population, Intervention, Comparator, Outcomes and Study type) framework, was conducted through PubMed, Google scholar, Dimensions, X-mol, and Semantic Scholar till December 2023. All types of studies reporting PDT in the management of CL with no language restriction were included. Methodological quality appraised of the selected studies was performed using Jadad index. Of the 317 identified studies, 21 reported PDT for the treatment of CL lesions, consisting of two randomized controlled trials (RCTs), four single-center open study, one case series and 14 case reports. Collectively, these studies presented a total of 304 patients with ages ranging from 1 to 82years, undergoing varying number of PDT sessions (3-28) and follow-up durations spanning 4weeks to 24months. The CL lesions predominantly manifested on the exposed body areas, such as face, limbs, neck, ear and nose, and characterized with the use of clinical variables, such as plaques, papules, erythema and ulceration. PDT protocols differed in the photosensitizer type, incubation time, light source characteristics (e.g., wavelength, output power, and energy density), duration of light illumination, number of PDT sessions and their respective frequencies. Treatment response was assessed through the clinical presentation (i.e., at the baseline and after PDT completion) or by the absence of Leishmania parasites. Adverse effects comprised of pain, burning and tingling sensation experienced during PDT, followed by erythema, pigmentation changes and edema post-treatment. This systematic review revealed that PDT is an efficacious and safe modality for the treatment of CL, with mild and transient side effects.

Phase classification and transient effects of the start-up process of multi-functional pump station in pump mode

In the context of achieving the goal of carbon neutrality, multi-functional pump stations (MFPS) have been greatly developed as a new energy system in recent years. The MFPS can operate in forward direction in pump mode to pump water and in turbine mode in reverse direction to generate electricity. At present, the instability of the MFPS during start-up process (SUP) in pump mode has become the key to restricting the operating life and further development of MFPS. In this paper, based on the motion characteristics of the pump and the cut-off facility (COF), the SUP of the MFPS in pump mode is clearly classified. In order to reveal the transient effect during the SUP, the steady-state full characteristic experiment (SFCE) of the pump was carried out. The occurrence phase of the transient effect during the SUP is analyzed, and the deviation between the steady-state external characteristics and the transient characteristics is revealed. In this study, the evaluation formula of the start-up completion degree (SUCD) of the MFPS in pump mode is proposed for the first time, and the evaluation and identification of the start-up progress at different phases are completed. The results show that the water flow in the system is in a reverse flow state in the Phase I. The SUCD of Phase I is 17 %. In the Phase II, The high-speed jet flow in the pump flows to the inlet of the guide vane (GV), which gradually changes the mainstream direction in the GV. A certain vortex structure can be observed at the exit of the flap gate (FG). The SUCD of Phase II is 61 %. In the Phase I and II, the dimensionless head of transient simulation is much larger than that of SFCE. In the Phase III, the flow state in the impeller will gradually stabilize. The transient effect disappears and the pressure fluctuation intensity decreases. The SUCD of Phase III is 93 %. In the Phase IV, the separation vortex that persists from Phase I-III at the tail of the GV blades disappears. The diversion capacity at the gate increases, and significant annular flow can be observed near the FG.