Emergent charge order in pressurized kagome superconductor CsV3Sb5.

The discovery of several electronic orders in kagome superconductors AV3Sb5 (A means K, Rb, Cs) provides a promising platform for exploring unprecedented emergent physics1-9. Under moderate pressure (<2.2 GPa), the triple-Q charge density wave (CDW) order is monotonically suppressed by pressure, while the superconductivity shows a two-dome-like behaviour, suggesting an unusual interplay between superconductivity and CDW order10,11. Given that time-reversal symmetry breaking and electronic nematicity have been revealed inside the triple-Q CDW phase8,9,12,13, understanding this CDW order and its interplay with superconductivity becomes one of the core questions in AV3Sb5 (refs. 3,5,6). Here, we report the evolution of CDW and superconductivity with pressure in CsV3Sb5 by 51V nuclear magnetic resonance measurements. An emergent CDW phase, ascribed to a possible stripe-like CDW order with a unidirectional 4a0 modulation, is observed between Pc1 ≅ 0.58 GPa and Pc2 ≅ 2.0 GPa, which explains the two-dome-like superconducting behaviour under pressure. Furthermore, the nuclear spin-lattice relaxation measurement reveals evidence for pressure-independent charge fluctuations above the CDW transition temperature and unconventional superconducting pairing above Pc2. Our results not only shed new light on the interplay of superconductivity and CDW, but also reveal new electronic correlation effects in kagome superconductors AV3Sb5.

Charge-density-wave-driven electronic nematicity in a kagome superconductor.

Electronic nematicity, in which rotational symmetry is spontaneously broken by electronic degrees of freedom, has been demonstrated as a ubiquitous phenomenon in correlated quantum fluids including high-temperature superconductors and quantum Hall systems1,2. Notably, the electronic nematicity in high-temperature superconductors exhibits an intriguing entanglement with superconductivity, generating complicated superconducting pairing and intertwined electronic orders. Recently, an unusual competition between superconductivity and a charge-density-wave (CDW) order has been found in the AV3Sb5 (A = K, Rb, Cs) family with two-dimensional vanadium kagome nets3-8. Whether these phenomena involve electronic nematicity is still unknown. Here we report evidence for the existence of electronic nematicity in CsV3Sb5, using a combination of elastoresistance measurements, nuclear magnetic resonance (NMR) and scanning tunnelling microscopy/spectroscopy (STM/S). The temperature-dependent elastoresistance coefficient (m11 minus m12) and NMR spectra demonstrate that, besides a C2 structural distortion of the 2a0 × 2a0 supercell owing to out-of-plane modulation, considerable nematic fluctuations emerge immediately below the CDW transition (approximately 94 kelvin) and finally a nematic transition occurs below about 35 kelvin. The STM experiment directly visualizes the C2-structure-pinned long-range nematic order below the nematic transition temperature, suggesting a novel nematicity described by a three-state Potts model. Our findings indicate an intrinsic electronic nematicity in the normal state of CsV3Sb5, which sets a new paradigm for revealing the role of electronic nematicity on pairing mechanism in unconventional superconductors.

Anisotropic Spin Fluctuations Induced by Spin-Orbit Coupling in a Misfit Layer Compound (LaSe)1.14(NbSe2).

Spin-orbit coupling (SOC) has significant effects on the superconductivity and magnetism of transition metal dichalcogenides (TMDs) at the 2D limit. Although 2D TMD samples possess many exotic properties different from those of bulk samples, experimental characterization in this field is still limited, especially for magnetism. Recent studies have revealed that bulk misfit layer compounds (MLCs) with (LaSe)1.14(NbSe2)n = 1,2 exhibit an Ising superconductivity similar to that of heavily electron-doped NbSe2 monolayers. This offers an opportunity to study the effect of SOC on the magnetism of 2D TMDs. Here, the possible SOC effect in (LaSe)1.14(NbSe2) is investigated by measuring nuclear magnetic resonance (NMR) and electrical transport. It is found that the LaSe layer not only functions as a charge reservoir for transferring electrons into the NbSe2 layer but also remarkably influences the local electronic environment around the 93Nb nuclei. More importantly, the significant SOC induces both a weak antilocalization (WAL) effect and anisotropic spin fluctuations in noncentrosymmetric NbSe2 layers. The present work contributes to a deep understanding of the role of the SOC effect in 2D TMDs and supports MCLs as an intriguing platform for exploring exotic physical properties within the 2D limit.

Laparoscopic splenectomy: the latest technical evaluation.

AIM: To introduce our latest innovation on technical manipulation of laparoscopic splenectomy. METHODS: Under general anesthesia and carbon dioxide (CO(2)) pneumoperitoneum, 86 cases of laparoscopic splenectomy (LS) were performed. The patients were placed in three different operative positions: 7 cases in the lithotomic position, 31 cases in the right recumbent position and 48 cases in the right lateral position. An ultrasonic scissors was used to dissect the pancreaticosplenic ligament, the splenocolicum ligament, lienorenal ligament and the lienophrenic ligament, respectively. Lastly, the gastrosplenic ligament and short gastric vessels were dissected. The splenic artery and vein were resected at splenic hilum with Endo-GIA. The impact of different operative positions, spleen size and other events during the operation were studied. RESULTS: The laparoscopic splenectomy was successfully performed on all 86 patients from August 1997 to August 2002. No operative complications, such as peritoneal cavity infection, massive bleeding after operation and adjacent organs injured were observed. There was no death related to the operation. The study showed that different operative positions could significantly influence the manipulation of LS. The right lateral position had more advantages than the lithotomic position and the right recumbent position in LS. CONCLUSION: Most cases of LS could be accomplished successfully when patients are placed in the right lateral position. The right lateral position has more advantages than the conventional supine approach by providing a more direct view of the splenic hilum as well as other important anatomies. Regardless of operation positions, the major axis of spleen exceeding 15 cm by B-ultrasound in vitro will surely increase the difficulties of LS and therefore prolong the duration of operation. LS is a safe and feasible modality for splenectomy.

[Laparoscopic colorectomy for colorectal cancer].

OBJECTIVE: To evaluate the result of laparoscopic colorectomy in treatment of colorectal cancer. METHODS: Laparoscopic colorectal surgery was performed in 78 patients with colorectal cancer. Operative procedures, complications and postoperative recovery were studied. RESULT: None of the 78 patients died of laparoscopic colorectal surgery or complications. Eleven patients died from tumor metastasis and 2 from other causes. Twenty-one, 17, 8 patients for 1, 3, 5 years survived respectively. In nine patients who had received operation less than 1 year, no tumor recurrence or metastasis was found except in 1 patient 11 months after operation. CONCLUSION: Laparoscopic colorectal cancer resection is essential to colectomy for colon and rectum cancer when indicated.

Laparoscopic splenectomy for immune thrombocytopenic purpura at a teaching institution.

BACKGROUND: High anatomic location, fragility, and generous blood supply of the spleen makes laparoscopic splenectomy (LS) difficult to master, and few patients need splenectomy for benign disorders. The aim of this research was to assess operative outcomes and hematological results of a large series of patients treated with LS for chronic immune thrombocytopenic purpura (ITP) and to determine which clinical variables predict favorable hematological outcome. METHODS: LS was successfully performed for 154 patients with chronic ITP from September 1999 to April 2009 at the First Affiliated Hospital of Sun Yat-sen University. Operative outcomes were assessed retrospectively. Long-term follow-up data were obtained from outpatient medical records and phone interviews. Clinical and laboratory variables (including gender, age, disease duration before surgery, previous response to steroids, preoperative platelet count, and postoperative peak platelet count) were evaluated by univariate analysis to identify potential predictors of hematological outcome. Multivariate Logistic regression model was used to determine independent predictors of hematological outcome. RESULTS: One patient died from subphrenic abscess and postoperative sepsis. The overall major morbidity rate was 8.4%. None of the patients required a second surgery for complications. Of the 127 patients available for a mean follow-up of 43.6 months (range 9 - 114 months), the overall initial response (i.e., at two months after LS) and long-term response to LS were achieved in 89.0% and 80.3%, respectively. Five patients (3.9%) developed pneumonia 3 - 35 months after LS. Univariate analysis showed a significant difference in mean age between responders (29.1 years) and nonresponders (38.8 years; P < 0.05). Patients who responded to steroid therapy had better hematological outcome than those who did not respond (P < 0.05). Compared to nonresponders, responders to LS had a significantly higher postoperative peak platelet count (404 × 10(9)/L versus 213 × 10(9)/L, P < 0.001). Multivariate Logistic regression analysis identified postoperative peak platelet count as the only independent predictor of favorable response to LS (P < 0.001). CONCLUSIONS: LS is a safe and effective treatment for chronic ITP. Postoperative peak platelet count may serve as a major predictor of long-term response.

[Subfascial endoscopic perforator vein surgery in treatment of varicose of lower limb].

OBJECTIVE: To investigate the therapeutic effect of subfascial endoscopic perforator vein surgery (SEPS) in treatment of varicose of the lower limb. METHODS: From 1999. 11 to 2000. 12, 108 patients with varicose of the lower limb underwent venous surgery and 34 of them were treated by SEPS. There were 16 males and 18 females aged 20-79(averaged 51.4 years). Thirty limbs (26 cases) had open ulcers and the diameter of ulcer was 1.5-12.0 cm. Eleven limbs (8 cases) had severe pigmentation and the skin changes had been presented for 1 month to 15 years. According to the severity of illness, flush saphenofemoral ligation, great saphenous vein stripping, percutaneous continuous venous circum suture, external femoral vein valve repair and SEPS were performed separately or simultaneously. RESULTS: Active ulcers healed in 19 limbs after 1 month, in 7 limbs after 3 months, and in the other 4 ulcers after skin transplantation. There was no ulcer recurrence during follow-up (ranged 9-22 months). CONCLUSION: SEPS can accelerate the healing of venous ulcers, and it is one of important methods in the treatment of chronic venous insufficiency.