Initial Cycle Research Articles

Application of the Index Card Match Strategy to Improve Students' Mathematical Problem Solving Ability

This study aims to find out how to increase the ability to solve mathematical problems through the application of Index Card Match learning strategies. The subjects in this study were 16 students in class IX A at Karya Bunda Mandiri Middle School. This research is a classroom action research (PTK) which consists of 2 cycles, each cycle consisting of 2 meetings. The results of the problem solving ability test increased from the initial test, cycle I and cycle II. In the classical pre-test 4 students (25%) passed and the average pre-test ability was 49.4 with a very low level of ability. In the first cycle, there was an increase classically, 7 students (43.75%) completed and the average ability test was obtained 61.2 with a low level of ability. Then in the second cycle test experienced an increase classically 14 students (87.5%) completed and the average ability was obtained 78.7 with a moderate level of ability. Thus it can be concluded that the application of the Index Card Match learning strategy can improve students' problem solving abilities.

Application of Project-Based Learning Learning Model Assisted by Geogebra Application to Improve Students' Mathematical Reasoning Ability at MTS Nurul Islam Indonesia Medan.

The purpose of this study was to determine the improvement of students' mathematical reasoning abilities by applying the Geogebra-assisted Project Based Learning learning model in class VIII-1 MTs Nurul Islam Indonesia Medan in the 2022/2023 academic year. The subjects in this study were students of class VIII-1 MTs Nurul Islam Indonesia Medan, amounting to 20 people. The data collection techniques used were teacher observation sheets, tests of mathematical reasoning abilities and documentation. This research is a classroom action research (CAR) which consists of 2 cycles, each cycle consists of 2 meetings. Before taking the action, an initial test is given and at the end of each cycle a student's mathematical reasoning ability test is given. The results of the students' mathematical problem reasoning ability test increased from the initial test, cycle I, and cycle II. In the classical initial test, 4 students (20%) completed and the average initial test ability was 56.29 with a very low level of ability category. In the classical first cycle test, 4 students (20%) completed and the average ability test was 57.22 with a very low level of ability category. Then in the second cycle test, classically, 17 students (85%) completed and the average ability was 89.44 with a high level of ability. Thus, it can be concluded that the application of the project based learning model assisted by the geogebra application to improve students' mathematical reasoning abilities at MTs Nurul Islam Indonesia Medan.

Safety, high-performing and effects of the N/P ratio of a solid lithium ion battery using PEGDME based polymer electrolytes

In this study, we report on the electrochemical properties of a solid state lithium ion battery (LIB) using a poly (ethylene glycol) dimethyl ether (PEGDME)-based solid polymer electrolyte (P-SPE). The LIB is prepared using a LiFePO4 (LFP) cathode and graphite anode material with P-SPE, and the kinetic properties of the lithium ions in the P-SPE are investigated. The synthesized P-SPE is shown to be suitable solid polymer electrolyte candidate for LIB applications. LFP and graphite are selected as electrode materials to validate their effectiveness in different battery cells with respect to their high energy density and inherent safety. The five-layer stacked 5 × 6 cm2 pouch-type LIB demonstrates a high capacity of 90 mAh (0.6 mAh/cm2) or more in the initial cycle, and it shows cycle stability with a capacity decrease of 20% over 500 cycles. We test the manufactured pouch-type full cells under extreme conditions (e. g., cutting, crushing and exposure of the battery cell to the atmosphere). LIBs using the developed P-SPE are promising solid polymer electrolyte candidates for wearable LIB as well as high energy LIB applications.

Ring-Opening Polymerization of rac-Lactide Catalyzed by Octahedral Nickel Carboxylate Complexes

To date, nickel(II) complexes have not been practically investigated as catalysts in ring-opening polymerization (ROP) of lactide to produce biodegradable poly(lactic acid), which is in demand in biomedicine and industry. In this study, carboxylate complexes of nickel(II) containing various N-donor ligands with different nuclearity, metal core rigidity and nature of carboxylate ligands were synthesized and studied by infrared spectroscopy, X-ray diffraction, elemental and thermogravimetric analyses. The obtained complexes were examined in the ROP of the rac-lactide in bulk and in toluene solution with and without the addition of a benzyl alcohol initiator. In the series of complexes studied, the complex [Ni(DBED)2(O2CC(CH3)3)2]·(CH3)3CCO2H (DBED is N,N′-dibenzylethylenediamine) was a syndioselective catalyst and showed the highest catalytic ability in the polymerization without the addition of benzyl alcohol. For this complex, according to 1D DOSY 1H NMR spectroscopy and mass spectrometry with electrospray ionization, polymerization is initiated by a free secondary amine, DBED, leaving the metal’s inner coordination sphere. Based on the experimental data obtained, a comprehensive density functional theory (DFT) study of the ROP pathways including the initiation and first chain growth cycle steps with a detailed description of the intermediates and evaluation of the energy barriers of the steps was carried out. It was shown that one of the key roles in the reaction process is played by carboxylate ligands, which act as proton carriers from the initiator molecule and have a significant influence on the reactivity of the catalytic metal complexes.

Supernano Crystals Boost the Initial Coulombic Efficiency and Capacity of Copper Benzene-1,3,5-Tricarboxylate for Li-Ion Batteries

Despite the high capacity of metal–organic framework (MOF) electrodes for Li-ion batteries (LIBs), the low initial Coulombic efficiency (ICE) due to irreversible and massive consumption of lithium ions in the initial cycle hinders their practical application. Nanoscale transition metal oxides (TMOs) can activate the electrochemically stable Li–O bonds and therefore improve the ICE. Hence, copper benzene-1,3,5-tricarboxylate (Cu-BTC) rods with encapsulated supernano CuO were synthesized in a straightforward way using CuO and H3BTC as the metal source and organic ligand, respectively. By altering the reaction temperature, the size of CuO crystals can be adjusted from 6.98 to 2.72 nm. The CuO-doped Cu-BTC (40 °C) anode delivers an optimal capacity of 990.7 mA h g–1 (under 0.2 A g–1) after 100 cycles and the highest ICE of 61.84%, which exceeds the other counterparts. Such superior electrochemical properties are closely related to the size and content of CuO. This strategy introduces supernano CuO into Cu-BTC, which can be generalized to construct other in situ-formed TMO-doped MOF compounds as efficient lithium storage materials.

An Innovative Insight into Performance Degradation of NCM111 Cathode Induced by Suspension of Operation.

The lifespan of lithium-ion batteries varies enormously from fundamental study to practical applications. This big difference has been typically ascribed to the high degree of uncertainty in unpredictable and complicated operation conditions in real-life applications. Here, we report that the pause of the charging-discharging process, which is frequently operated in practice but rarely studied in academics, is an important reason for the performance degradation of the NCM111 cathode. It is found that the pause during cycling could trigger a remarkable drop in capacity, giving rise to ∼30% more capacity decay compared with the continuously cycled sample. In situ synchrotron X-ray diffraction analysis reveals that the harmful H1-H2 phase transition, which typically appears in the initial cycle but disappears in subsequent cycles, is reactivated by the pausing process. The anisotropic lattice strains that occur during the H1-H2 transition result in mechanical fractures that terminate with an inert NiO-type rock-salt phase on the surface of particles. The present study indicates that the discontinuous usage of rechargeable batteries is also a key factor for cycle life, which might provide a distinct perspective on the performance decay in practical applications.

IVF outcomes following ICSI cycles using testicular sperm in obstructive (OA) vs. non-obstructive azoospermia (NOA) and the impact of maternal and paternal age: a SART CORS data registry.

To assess the differences in IVF outcomes between couples with obstructive azoospermia (OA), non-obstructive azoospermia (NOA), and male factor (MF). Using the SART CORS data from 2016 to 2017, we included all initial autologous cycles with a diagnosis of male factor with ejaculated and surgically obtained sperm. We analyzed 71,121 cycles, including 3467 with a diagnosis of azoospermia and 67,654 with other non-azoospermic MF. Using a multivariate binomial regression, we estimated adjusted risk ratios comparing outcomes for ICSI cycles using surgically acquired (OA and NOA) versus ejaculated sperm (MF). Outcomes reported per initial cycle included clinical pregnancy, live birth, biochemical pregnancy, and miscarriage. Outcomes reported per singleton pregnancy included full-term delivery (≥ 37 weeks), normal birth weight (≥ 2500 g), and delivery method. After frozen embryo transfers (FET), patients with NOA had 7% higher odds of live birth compared to MF (aOR 1.23 (0.94-1.74)), and those with OA had 2.6% lower chance of live birth compared to MF (aOR 0.73 (95%CI 0.5-1.05)). After fresh ET, patients with NOA had 5% higher chance of live birth (aOR 1.11 (0.9-1.36)), and those with OA had a 2.5% higher chance of live birth (aOR 1.10 (95%CI 0.89-1.34)) compared to MF. All three subgroups had lower fresh live birth rates (LBR) compared to FETs. Couples with either NOA or OA have overall comparable ART and perinatal outcomes to couples with MF, and their success is primarily dependent on both patient's and partner's age.

Clinical audit of the Consultation-Liaison psychiatric service of a metropolitan hospital.

The primary objective of this study was to use clinical indicators to track changes in efficiency of a Consultation-Liaison service as part of a clinical audit cycle. This was a clinical audit cycle. The auditing phase involved measuring the efficiency of the service. The 'intervention' was simply the team's awareness and involvement in tracking these statistics. Subsequently, these indicators were re-audited. In the initial audit cycle, 315 referrals to the C-L service were audited over a 3month period, showing a 24hour time-to-seen rate of 80% and a 36hour time-to-seen rate of 89.2%. Upon re-auditing of 112 referrals following our intervention, 24hr timeliness had risen to 92% and 36hr timeliness had risen to 96.4%. The measuring of clinical indicators of efficiency in C-L may give service improvement personnel a reflection of the functionality of a C-L service. By involving team members in the measuring and tracking of these indicators, we may be able to boost overall clinical efficiency and outcomes.

In-situ electrochemical oxidization of V2O3-C cathode for boosted zinc-ion storage performance

In-situ electrochemical activation can bring about unexpected improvement for electrode materials, while the nature behind the structural evolution during this activation remains unclear, which to a great extent limits the applications in searching for efficient cathodes for rechargeable zinc-ion battery (ZIB) with outstanding rate performance. Herein, we report on in-situ electrochemical oxidation of V2O3-C cathode for boosted zinc-ion storage performance. A solvothermal method is implemented to directly synthesize V2O3 nanoparticles coated with a carbon layer. Detailed characterizations reveal that due to co-embedding of H2O and Zn2+, tunnel-like V2O3 undergoes an in-situ electrochemical oxidation to generate layered V5O12·6H2O upon initial cycling. The intercalation of H2O molecules results in an expansion of layer spacing, accelerating the Zn2+ diffusion kinetics. As a consequence, a symmetric cell equipped with activated V2O3-C electrode delivers a high-rate capability (349 mA h g−1 at 1000 mA g−1) and superior specific capacity (260 mA h g−1 at 100 mA g−1 after 100 cycles). The strategy of in-situ electrochemical oxidation delivers the guidance to tunnel-like materials as cathode for rechargeable ZIBs.

Solvation and Interfacial Engineering Enable -40°C Operation of Graphite/NCM Batteries at Energy Density over 270 Whkg-1.

Li-ion batteries (LIBs) that can operate under low temperature (LT) conditions are essential for applications in orbital missions, subsea areas, and electric vehicles. Unfortunately, severe capacity loss is witnessed due to tremendous kinetic barriers that emerge at LT. Herein, to surmount such kinetic limitations, a low dielectric environment is tamed throughout the bulk electrolyte, which efficaciously brought the Li+ desolvation energy down to 30.76 kJmol-1 . At the meantime, the adoption of sodium cations (Na+ ) is proposed as a hetero-cation additive, and a Li-Na hybrid and fluoride-rich interphase is further identified via preferential reduction of Na+ -(solvent/anion) clusters, which is found to efficiently facilitate Li+ migration through the LiF/NaF grain boundaries. Based on a N/P ratio of 1.1, the graphite/LiNi0.5 Co0.2 Mn0.3 O2 (NCM) full cell (cathode loading of ≈18.5mgcm-2 ) delivers a capacity as high as 125.1 mAhg-1 under -20°C with prolonged cycling to 100 cycles. Finally, a 270Whkg-1 graphite/NCM pouch cell is assembled, which affords a discharge capacity of 108.7 mAhg-1 under -40°C during the initial cycles. With an eye to both fundamental and practical aspects, this work will propel additional advancements and allow LIBs to fill more roles under extreme operation temperatures than ever before.

Electrolyte engineering via ether solvent fluorination for developing stable non-aqueous lithium metal batteries

Fluorination of ether solvents is an effective strategy to improve the electrochemical stability of non-aqueous electrolyte solutions in lithium metal batteries. However, excessive fluorination detrimentally impacts the ionic conductivity of the electrolyte, thus limiting the battery performance. Here, to maximize the electrolyte ionic conductivity and electrochemical stability, we introduce the targeted trifluoromethylation of 1,2-dimethoxyethane to produce 1,1,1-trifluoro-2,3-dimethoxypropane (TFDMP). TFDMP is used as a solvent to prepare a 2 M non-aqueous electrolyte solution comprising bis(fluorosulfonyl)imide salt. This electrolyte solution shows an ionic conductivity of 7.4 mS cm–1 at 25 °C, an oxidation stability up to 4.8 V and an efficient suppression of Al corrosion. When tested in a coin cell configuration at 25 °C using a 20 μm Li metal negative electrode, a high mass loading LiNi0.8Co0.1Mn0.1O2-based positive electrode (20 mg cm–2) with a negative/positive (N/P) capacity ratio of 1, discharge capacity retentions (calculated excluding the initial formation cycles) of 81% after 200 cycles at 0.1 A g–1 and 88% after 142 cycles at 0.2 A g–1 are achieved.

Stretchable, adhesive and low impedance hydrogel prepared by one-pot method used as ECG electrodes

Flexible, self-adhesive and conductive hydrogel has attracted a deal of interest in ECG biosensors. However, the balance between mechanical properties and ionic conductivity of hydrogels is challenging, and there are tremendous difficulties in preparing a multifunctionally integrated hydrogel. Herein, we designed a multi-network conductive hydrogel, the poly(vinylalcohol)/carboxymethylcellulose sodium-poly([2-(methacryloyloxy) ethyl] dimethyl-(3-sulfo-propyl) ammonium hydroxide-co-acrylamide) (PVA/CMC-Na-P(SBMA-co-AM), PVA/CMC-SAM) hydrogel was obtained by thermal initiation and freeze-thaw cycles. Because of the existence of three-dimensional porous structure, its ionic conductivity reaches 0.91 S/m. The elastic modulus is 0.17 MPa, the fracture strain is 105%, and the tensile strength is 0.21 MPa. At the same time, hydrogels can be bound to different surfaces with the adhesion properties, leading to the low contact impedance on human skin surface. Due to the dynamic cross-linking of hydrogen bonds, hydrogels also exhibit obvious self-healing properties. The resistance of hydrogel is sensitive to strain and can accurately monitor subtle physical movements like finger bending, while continuously, steadily and clearly collecting ECG signals. Therefore, the multifunctionally integrated hydrogel can display promising applications in ECG biosensors.

A nickel-rich oxide, Li(Ni0.90Co0.06Mn0.04)0.995Al0.005 O2, with a dual conductive coating

Nickel (Ni)-rich layered oxides have high specific capacities and are inexpensive, but their synthesis and electrochemical performance continue to present difficulties. In this study, we investigated the effect of a dual conductive compound of dot-like Nb12WO33 and film-like lithium boron oxide (Li-B-O; applied using a simple dry-coating method) on the Ni-rich oxide layer in Li batteries. The film-like Li-B-O homogeneous coating segregated the cathode from the electrolyte, which improved the initial efficiency and cycle stability, and the dot-like Nb12WO33 provided a fast Li-ion transition channel, which improved the rate performance of the Ni-rich oxide layer. The modified cathode with dual conductive coating exhibited significantly improved electrochemical performance. Its discharge capacity was 225.6 mAh g−1, with high initial efficiency of 92.73% in the voltage range of 3.0–4.3 V at 0.1 C, whereas that of the uncoated sample was 219.4 mAh g−1, with an initial efficiency of 90.4%. The modified cathode had a discharge capacity of 179.1 mAh g−1 at 5 C, compared with that of 161.1 mAh g−1 for the uncoated sample; the capacity retention of the coated sample was 92.84% at 0.5 C after 50 cycles at 25 ℃, whereas that of the uncoated sample was only 81.41%. A similar strategy could be utilized to enhance the performance of other cathode materials.

Constitutive modeling for the training process of two-way shape memory effect under thermal cyclic loading

Shape memory alloys (SMAs)—if trained properly—can induce two-way shape memory effect which is applicable in actuator design using SMAs. In this study, a three-dimensional phenomenological model is proposed for SMAs within the framework of irreversible thermodynamics in order to predict the training process under cyclic loading and the induced two-way shape memory effect. In this regard, transformation and permanent strains are considered as internal variables and Helmholtz free energy function is introduced using several material parameters accounting for elastic, transformation and permanent deformation mechanisms. In order to demonstrate the capabilities of the proposed model, we first compare the model results with several experimental results and prove that the current model fits well with various experiments under cyclic loading as well as two-way shape memory effect. In addition, the capabilities of the present model in predicting the two-way shape memory effect, degradation effects, evolution rate, stabilization of permanent strain as well as multiaxial loading have been carefully examined through parametric studies. It is concluded that the present model is able to predict the training process from the initial cycles to stabilization and two-way effect for different materials and conditions.

Surface Phase Conversion in a High-Entropy Layered Oxide Cathode Material

High-entropy transition-metal oxides are potentially interesting cathode materials for lithium-ion batteries, among which high-entropy layered oxides are considered highly promising because there exist two-dimensional ion transport channels that may, in principle, enable fast ion transport. However, high-entropy layered oxides reported to date exhibit fast capacity fading in initial cycles and thus are hardly of any practical value. Here, we investigate the structural and property changes of a five-element layered oxide, LiNi0.2Co0.2Mn0.2Fe0.2Al0.2O2, using electrochemical and physical characterization techniques. It is revealed that the M3O4 phase formed at the surface of LiNi0.2Co0.2Mn0.2Fe0.2Al0.2O2 due to the migration of metal ions from octahedral sites of the transition-metal layer to tetrahedral 8a and octahedral sites of the lithium layer hinders the intercalation of lithium ion, which leads to the low initial Coulombic efficiency and fast decay of reversible capacity. This mechanism could be generally applicable to other high-entropy layered oxides with different elemental compositions.

Hydration of a Side-Chain-Free n-Type Semiconducting Ladder Polymer Driven by Electrochemical Doping

We study the organic electrochemical transistor (OECT) performance of the ladder polymer poly(benzimidazobenzophenanthroline) (BBL) in an attempt to better understand how an apparently hydrophobic side-chain-free polymer is able to operate as an OECT with favorable redox kinetics in an aqueous environment. We examine two BBLs of different molecular masses from different sources. Regardless of molecular mass, both BBLs show significant film swelling during the initial reduction step. By combining electrochemical quartz crystal microbalance gravimetry, in-operando atomic force microscopy, and both ex-situ and in-operando grazing incidence wide-angle X-ray scattering (GIWAXS), we provide a detailed structural picture of the electrochemical charge injection process in BBL in the absence of any hydrophilic side-chains. Compared with ex-situ measurements, in-operando GIWAXS shows both more swelling upon electrochemical doping than has previously been recognized and less contraction upon dedoping. The data show that BBL films undergo an irreversible hydration driven by the initial electrochemical doping cycle with significant water retention and lamellar expansion that persists across subsequent oxidation/reduction cycles. This swelling creates a hydrophilic environment that facilitates the subsequent fast hydrated ion transport in the absence of the hydrophilic side-chains used in many other polymer systems. Due to its rigid ladder backbone and absence of hydrophilic side-chains, the primary BBL water uptake does not significantly degrade the crystalline order, and the original dehydrated, unswelled state can be recovered after drying. The combination of doping induced hydrophilicity and robust crystalline order leads to efficient ionic transport and good stability.

The static friction peak in reciprocating sliding

This paper investigates why the static friction peak is mostly absent in reciprocating sliding and gross-slip fretting literature. Here, reciprocating sliding tests were conducted on ultra-smooth silicon surfaces. A prominent static friction peak was present in the initial cycles. However, a rapid wear-induced decay in the static friction peak occurred after the first cycle with the peak being mostly absent by about 30 cycles. Two possible explanations are proposed for the wear-induced decay: (1) that increasing surface roughness (with cycles) reduces the fully stuck contact area and (2) that wear reduces the bonding strength of the stuck interface by removing third body contaminant molecules. Predictions from a multi-asperity friction model are used to support these arguments.

Creating affiliations, learning, and mindfulness for in vitro fertilization patients (CALM IVF): a clinical trial

Determine if group psychoeducational support can improve invitro fertilization (IVF) patients' quality of life (QoL). Randomized controlled trial (NCT04048772). University-affiliated IVF clinic. Women (n = 76) and male partners undergoing initial autologous IVF cycle from August 2019, to December2020. Couples were assigned to groups based on projected oocyte retrieval date. Groups were randomly assigned to the control or intervention arm. Clinic closures because of the COVID-19 pandemic delayed treatment for a portion of participants. Groups were conducted in person before and virtually during the pandemic. The primary outcome was a change in fertility quality of life (FertiQoL) from baseline to 3 days after retrieval. Secondary outcomes were changes in depression (Patient Health Questionnaire 9), anxiety (Generalized Anxiety Disorder 7), resilience (Connor-Davidson Resilience scale), IVF knowledge scores, and the likelihood of return to treatment. Knowledge scores among women in Creating Affiliations, Learning, and Mindfulness (CALM) for IVF groups significantly increased compared with control (mean difference 13.19 [3.53 - 22.84]) before the pandemic. During the pandemic, women in CALM IVF had significant improvement in the social FertiQoL score compared with controls (10.42 [1.79 - 19.04]). Compared with controls, male CALM IVF participants had significantly greater improvement in total FertiQoL (mean difference 6.68 [0.39 - 12.98]), treatment FertiQoL (8.26 [0.69 - 15.82]), and resilience (Connor-Davidson 1.13 [0.54 - 1.72]). Immediate return to care did not significantly differ between arms. For women undergoing IVF, group psychoeducational programs can improve IVF knowledge and social QoL during a pandemic. Participation in a group psychoeducational program can improve QoL and resilience in IVF dyad male partners. Trial registration NCT04048772.

Scalable preparation of practical 1Ah all-solid-state lithium-ion batteries cells and their abuse tests

All-solid-state lithium-ion batteries are considered as a promising electric energy storage platform for electric vehicles due to the replacement of flammable liquid organic electrolytes in current lithium-ion batteries by inflammable solid ones; thus promoting high safety. Despite plenty of research on various solid electrolytes and other components, reports on the scalable production of all-solid-state lithium-ion batteries using electrodes with meaningful areal capacities are rather scarce. Consequently, the safety of all-solid-state lithium-ion batteries has not been systematically investigated yet, especially on cells with higher than lab-scale capacities. The aim of this report is to build a bridge between academic research and more industrially meaningful information on the safety of all-solid-state lithium-ion batteries. Thus, three 1Ah all-solid-state lithium-ion batteries were fabricated, where hybrid solid electrolyte consisting of PEO-LiTFSI polymer matrix with Lithium Ionic Conductive Glass Ceramic (LICGC™, Ohara Inc.) particle as active filler was sandwiched between NMC622 cathode and advanced graphite MCMB anode, both of which have a practically valuable areal capacity of higher than 1.0 mAh/cm2. Initial formation cycling was performed to build conformal interface between solid electrolyte film and electrodes. Comparable specific capacity of cathode active materials (∼90.0 mAh/g @ C/10 & 60 °C) could be achieved in three pouch cells with high consistence. Typical abuse tests including overcharge, external short, and nail penetration were conducted, the three 1Ah all-solid-state lithium-ion batteries cells showed excellent safety performance: there was no thermal runaway, no explosion, only slight increase of temperature was observed. This work demonstrates the scalable fabrication of practical all-solid-state lithium-ion batteries with consistent electrochemical performance and thereafter confirms their intrinsic safety.

Substrate Mapping Alters Ventricular Tachycardia Inducibility.

Initiation of ventricular tachycardia (VT) by programmed electrical stimulation (PES) has an important role to allow mapping and assess ablation end points. We hypothesized that substrate mapping may alter VT inducibility by mechanical bumping of critical sites. Subjects with left ventricular scar-related VT that was inducible by PES who were undergoing ablation were included. PES was repeated after substrate mapping (Group I) or after time under sedation/anesthesia during which additional imaging and transeptal puncture were performed without substrate mapping (Group II). The response to the second PES was categorized as type I if the same VT was induced, type II if a different VT was induced, and type III if VT was not inducible. Twenty-eight patients (median age 66 years, 61% ischemic cardiomyopathy), 14 in Group I and 14 in Group II, were included. Age, time between initial and second PES, type of cardiomyopathy, ejection fraction, and anesthesia methods were not different between the 2 groups. Initial VT cycle length, however, was shorter in Group I (305 millisecond [range, 235-600] versus 350 millisecond [range, 235-600], P=0.016). Also, Group I required more extrastimuli to induce VT in PES 1 (2 [1-4] versus 2 [1-3], P=0.022). In Group I, following substrate mapping, the second PES induced the same VT in 3 patients (21%), a different VT in 9 (64%), and no VT in 2 (14%) patients. In contrast, in Group II the same VT was induced in 10 (71%) patients, a different VT in 3 (21%) and no VT in 1 (7%) patient (P=0.017). Mechanical effects of substrate mapping commonly alter inducibility of VT. This has important implications for catheter ablation procedure planning and acute assessment of outcome and can potentially account for some recurrent VTs that are not recognized at the time of the procedure.