Thermodynamic determination of the equilibrium first-order phase-transition line hidden by hysteresis in a phase diagram.

In some materials exhibiting field-induced first-order transitions (FOTs), the equilibrium phase-transition line is hidden by the hysteresis region associated with the FOT. In general, phase diagrams form the basis for the study of material science, and the profiles of phase-transition lines separating different thermodynamic phases include comprehensive information about thermodynamic quantities, such as latent heat. However, in a field-induced FOT, the equilibrium phase-transition line cannot be precisely determined from measurements of resistivity, magnetization, etc, especially when the transition is accompanied by large hysteresis. Here, we demonstrate a thermodynamics-based method for determining the hidden equilibrium FOT line in a material exhibiting a field-induced FOT. This method is verified for the field-induced FOT between antiferromagnetic and ferrimagnetic states in magneto-electric compounds ([Formula: see text]. The equilibrium FOT line determined based on the Clausius-Clapeyron equation exhibits a reasonable profile in terms of the third law of thermodynamics, and it shows marked differences from the midpoints of the hysteresis region. Our findings highlight that for a field-induced FOT exhibiting large hysteresis, care should be taken for referring to the hysteresis midpoint line when discussing field-induced latent heat or magnetocaloric effects.

[IMPACT OF GENERAL FATIGUE ON TREATMENT PERIOD AFTER INDUCTION OF ENZALUTAMIDE FOR CASTRATION-RESISTANT PROSTATE CANCER].

(Objectives) Enzalutamide is an effective therapeutic options for castration resistant prostate cancer (CRPC). General fatigue is a major adverse event after commencing of enzalutamide in CRPC patients; however, its precise impact remains uncertain, especially on the duration of enzalutamide therapy. This study evaluated the relationship of general fatigue with patient age and enzalutamide treatment duration using real-world clinical data. (Patients and methods) This investigation retrospectively included patients who received enzalutamide therapy for CRPC between 2014 and 2018 at Shinshu University School of Medicine or Nagano Municipal Hospital. We classified the patients into the general fatigue group and the non-general fatigue group, and analyzed the groups in with regard to age and the duration of enzalutamide treatment. (Results) Of the 98 patients with CRPC were enrolled, 40 (40.8%) complained of general fatigue after enzalutamide induction. The median age of the study group was 78.0 years (71.0 years in the general fatigue group and 75.0 years in the non-general fatigue group), with no significant difference between the groups. Mean treatment duration was also comparable at 265.9 days in the general fatigue group and 266.5 days in the non-general fatigue group. (Conclusions) General fatigue after commencing enzalutamide was not impacted by age and did not remarkably influence the duration of therapy for CRPC.

Safety and efficacy of cabazitaxel in Japanese patients with castration-resistant prostate cancer.

BACKGROUND: Several studies have reported the efficacy of cabazitaxel in cancer therapy; however, investigations of its safety are few. The aim of this study was to retrospectively analyze the efficacy and safety of cabazitaxel based on treatment outcome data. METHODS: A questionnaire form on the use of cabazitaxel was mailed to hospitals associated with the Shinshu University. Responses were received from 11 institutions regarding 55 cases. RESULTS: Patients received a median of 4 courses of cabazitaxel treatment. Decreases in prostrate-specific antigen (PSA) were observed in 61.5% of cases with declines of 30%, 50%, and 90% in 36.5%, 23.0%, and 7.6% of cases, respectively. PSA progression-free survival was 5.0 months, and overall survival after the start of cabazitaxel was 13.0 months. Forty-five patients received postcabazitaxel treatment; 17 showed decreased PSA. Safety assessment indicated that white blood cell and neutrophil counts were significantly higher in the second than in the first course of treatment and Grade 3 to 4 leukopenia and neutropenia significantly decreased. Twenty-four subjects were aged ≥75 years; 79% of them had their doses reduced at the first administration. The mean dose was 20 mg/m2. However, there was no significant difference in the PSA progression-free survival between the ≥75-year-old and <75-year-old groups. Patients in the ≥75-year-old group, particularly those whose doses were not reduced, experienced several Grade 3 to 4 adverse effects. Ten patients discontinued treatment owing to adverse effects and systemic worsening. CONCLUSIONS: To use cabazitaxel effectively, starting administration as early as possible before disease progression is important, and even if Grade 3 to 4 leukopenia and neutropenia are observed during the first course, it is important to carefully maintain the dose. Even when treating elderly patients, reducing the dose does not reduce therapeutic efficacy. However, because this cohort experienced several ≥ Grade 3 adverse effects, a great deal of caution is required.

[THE EFFECT OF LOW-DOSE INTRAVESICAL BACILLUS CALMETTE-GUÉRIN (BCG) INFUSION THERAPY FOR NON-MUSCLE INVASIVE BLADDER CANCER].

(Objective) Bacillus Calmette-Guérin (BCG) intravesical infusion therapy plays an important role in the treatment of patients with high-risk non-muscle-invasive bladder cancer (NMIBC). Our institute performs low-dose (40 mg) BCG intravesical infusion therapy (completed 8 times) to reduce side effects. We retrospectively investigated its efficacy and side effects. (Patients and methods) We analyzed the response, non-recurrence, and side effect rates by risk stratification in 179 patients who received low-dose BCG intravesical infusion therapy from September 2003 to November 2018 in Nagano Municipal Hospital. Complications were classified using the Common Terminology Criteria for Adverse Events version 4.0. (Results) The median age was 73 years, and the male/female ratio was 137:42. The median observation period was 32 months, and infusion was completed 8 times in 149 cases (83.2%). The overall response rate was 88.8%. The response rate was significantly higher in the low-grade pathology group than in the high-grade group. However, no significant differences in G1/G2/G3 side effects, sex, age, presence of carcinoma in situ (CIS), depth of invasion, purpose of administration, and grade of side effects were observed. The overall non-recurrence rates were 91.8%, 76.7%, and 71.3% at 1, 3, and 5 years, respectively. Nevertheless, there were no significant differences in the non-recurrence rates with respect to depth of penetration, the degree of dysmorphism, purpose of administration, presence of CIS, and completed of infusion. A total of 71 G2 side effects (39.7%) were identified, and 3 cases of G3 side effects required hospitalization. (Conclusion) In our institution, the completion rate of low-dose BCG intravesical infusion therapy was high, with few side effects. Furthermore, it demonstrated similar therapeutic effect to that reported with standard-dose administration. Low-dose BCG intravesical infusion therapy may be an effective treatment, particularly for pathologically low-grade NMIBC.

Kinetic approach to superconductivity hidden behind a competing order.

Exploration for superconductivity is one of the research frontiers in condensed matter physics. In strongly correlated electron systems, the emergence of superconductivity is often inhibited by the formation of a thermodynamically more stable magnetic/charge order. Thus, to develop the superconductivity as the thermodynamically most stable state, the free-energy balance between the superconductivity and the competing order has been controlled mainly by changing thermodynamic parameters, such as the physical/chemical pressure and carrier density. However, such a thermodynamic approach may not be the only way to materialize the superconductivity. We present a new kinetic approach to avoiding the competing order and thereby inducing persistent superconductivity. In the transition-metal dichalcogenide IrTe2 as an example, by using current pulse-based rapid cooling of up to ~107 K s-1, we successfully kinetically avoid a first-order phase transition to a competing charge order and uncover metastable superconductivity hidden behind. Because the electronic states at low temperatures depend on the history of thermal quenching, electric pulse applications enable nonvolatile and reversible switching of the metastable superconductivity, a unique advantage of the kinetic approach. Thus, our findings provide a new approach to developing and manipulating superconductivity beyond the framework of thermodynamics.

Current-induced viscoelastic topological unwinding of metastable skyrmion strings.

In the MnSi bulk chiral magnet, magnetic skyrmion strings of 17 nm in diameter appear in the form of a lattice, penetrating the sample thickness, 10-1000 µm. Although such a bundle of skyrmion strings may exhibit complex soft-matter-like dynamics when starting to move under the influence of a random pinning potential, the details remain highly elusive. Here, we show that a metastable skyrmion-string lattice is subject to topological unwinding under the application of pulsed currents of 3-5 × 106 A m-2 rather than being transported, as evidenced by measurements of the topological Hall effect. The critical current density above which the topological unwinding occurs is larger for a shorter pulse width, reminiscent of the viscoelastic characteristics accompanying the pinning-creep transition observed in domain-wall motion. Numerical simulations reveal that current-induced depinning of already segmented skyrmion strings initiates the topological unwinding. Thus, the skyrmion-string length is an element to consider when studying current-induced motion.

Anomalous metallic behaviour in the doped spin liquid candidate κ-(ET)4Hg2.89Br8.

Quantum spin liquids are exotic Mott insulators that carry extraordinary spin excitations. Therefore, when doped, they are expected to afford metallic states with unconventional magnetic excitations. Here, we report experimental results which are suggestive of a doped spin liquid with anomalous metallicity in a triangular-lattice organic conductor. The spin susceptibility is nearly perfectly scaled to that of a non-doped spin liquid insulator in spite of the metallic state. Furthermore, the charge transport that is confined in the layer at high temperatures becomes sharply deconfined on cooling, coinciding with the rapid growth of spin correlations or coherence as signified by a steep decrease in spin susceptibility. The present results substantiate the desired doped spin liquid and suggest a strange metal, in which the coherence of the underlying spin liquid promotes the deconfinement of charge from the layers while preserving the non-Fermi-liquid nature.It is expected that introducing charge carriers into an exotic quantum spin liquid state may lead to an unconventional metal but there are no clear realizations of a metallic spin liquid. Here, the authors present a spin liquid candidate that also shows evidence of strange metal behavior.

Skyrmion lattice structural transition in MnSi.

Magnetic skyrmions exhibit particle-like properties owing to the topology of their swirling spin texture, providing opportunities to study crystallization of topological particles. However, they mostly end up with a triangular lattice, and thus, the packing degree of freedom in the skyrmion particles has been overlooked so far. We report a structural transition of the skyrmion lattice in MnSi. By use of small-angle neutron scattering, we explore a metastable skyrmion state spreading over a wide temperature and magnetic field region, after thermal quenching. The quenched skyrmions undergo a triangular-to-square lattice transition with decreasing magnetic field at low temperatures. Our study suggests that various skyrmion lattices can emerge at low temperatures, where the skyrmions exhibit distinct topological nature and high sensitivity to the local magnetic anisotropy arising from the underlying chemical lattice.

Current-Induced Nucleation and Annihilation of Magnetic Skyrmions at Room Temperature in a Chiral Magnet.

A magnetic skyrmion is a nanometer-scale magnetic vortex carrying an integer topological charge. Skyrmions show a promise for potential application in low-power-consumption and high-density memory devices. To promote their use in applications, it is attempted to control the existence of skyrmions using low electric currents at room temperature (RT). This study presents real-space observations for the current-induced formation and annihilation of a skyrmion lattice (SkL) as well as isolated skyrmions in a microdevice composed of a thin chiral magnet Co8 Zn9 Mn3 with a Curie temperature, TC ≈ 325 K, above RT. It is found that the critical current for the manipulation of Bloch-type skyrmions is on the order of 108 A m-2 , approximately three orders of magnitude lower than that needed for the creation and drive of ferromagnetic (FM) domain walls in thin FM films. The in situ real-space imaging also demonstrates the dynamical topological transition from a helical or conical structure to a SkL induced by the flow of DC current, thus paving the way for the electrical control of magnetic skyrmions.

Quenching of Charge and Spin Degrees of Freedom in Condensed Matter.

Electrons in condensed matter have internal degrees of freedom, such as charge, spin, and orbital, leading to various forms of ordered states through phase transitions. However, in individual materials, a charge/spin/orbital ordered state of the lowest temperature is normally uniquely determined in terms of the lowest-energy state, i.e., the ground state. Here, recent results are summarized showing that under rapid cooling, this principle does not necessarily hold, and thus, the cooling rate is a control parameter of the lowest-temperature state beyond the framework of the thermoequilibrium phase diagram. Although the cooling rate utilized in low-temperature experiments is typically 2 × 10-3 to 4 × 10-1 K s-1 , the use of optical/electronic pulses facilitates rapid cooling, such as 102 -103 K s-1 . Such an unconventionally high cooling rate allows some systems to kinetically avoid a first-order phase transition, resulting in a quenched charge/spin state that differs from the ground state. It is also demonstrated that quenched states can be exploited as a non-volatile state variable when designing phase-change memory functions. The present findings suggest that rapid cooling is useful for exploring and controlling the metastable electronic/magnetic state, which is potentially hidden behind the ground state.