First Results in the Search for Dark Sectors at NA64 with the CERN SPS High Energy Muon Beam.

We report the first search for dark sectors performed at the NA64 experiment employing a high energy muon beam and a missing energy-momentum technique. Muons from the M2 beamline at the CERN Super Proton Synchrotron with a momentum of 160 GeV/c are directed to an active target. The signal signature consists of a single scattered muon with momentum <80 GeV/c in the final state, accompanied by missing energy, i.e., no detectable activity in the downstream calorimeters. For a total dataset of (1.98±0.02)×10^{10} muons on target, no event is observed in the expected signal region. This allows us to set new limits on the remaining (m_{Z^{'}},g_{Z^{'}}) parameter space of a new Z^{'} (L_{µ}-L_{τ}) vector boson which could explain the muon (g-2)_{µ} anomaly. Additionally, our study excludes part of the parameter space suggested by the thermal dark matter relic abundance. Our results pave the way to explore dark sectors and light dark matter with muon beams in a unique and complementary way to other experiments.

Search for a New B-L Z

A search for a new Z^{'} gauge boson associated with (un)broken B-L symmetry in the keV-GeV mass range is carried out for the first time using the missing-energy technique in the NA64 experiment at the CERN SPS. From the analysis of the data with 3.22×10^{11} electrons on target collected during 2016-2021 runs, no signal events were found. This allows us to derive new constraints on the Z^{'}-e coupling strength, which, for the mass range 0.3≲m_{Z^{'}}≲100 MeV, are more stringent compared to those obtained from the neutrino-electron scattering data.

A rapid synthesis of nanofibrillar cellulose/polystyrene composite via ultrasonic treatment.

A new method of the synthesis of nanofibrillar cellulose/polystyrene composite based on ultrasonic treatment of styrene emulsion in cellulose-water solution was elaborated. A new approach does not require additional heating and proposes a significantly faster synthesis (15 min, 45 °C) of the target composite compared to the methods described previously. A comprehensive analysis did not reveal any significant differences between mechanical, physical and biodegradable properties of the composite obtained by ultrasonic method and that one obtained by conventional thermal method, which requires much higher temperature (above 75 °C) and reaction duration (from 3 h).

Probing the explanation of the muon (g-2) anomaly and thermal light dark matter with the semi-visible dark photon channel.

We report the results of a search for a new vector boson ( A ' ) decaying into two dark matter particles χ 1 χ 2 of different mass. The heavier χ 2 particle subsequently decays to χ 1 and an off-shell Dark Photon A ' ∗ → e + e - . For a sufficiently large mass splitting, this model can explain in terms of new physics the recently confirmed discrepancy observed in the muon anomalous magnetic moment at Fermilab. Remarkably, it also predicts the observed yield of thermal dark matter relic abundance. A detailed Monte-Carlo simulation was used to determine the signal yield and detection efficiency for this channel in the NA64 setup. The results were obtained re-analyzing the previous NA64 searches for an invisible decay A ' → χ χ ¯ and axion-like or pseudo-scalar particles a → γ γ . With this method, we exclude a significant portion of the parameter space justifying the muon g-2 anomaly and being compatible with the observed dark matter relic density for A ' masses from 2 m e up to 390 MeV and mixing parameter ε between 3 × 10 - 5 and 2 × 10 - 2 .

Constraints on New Physics in Electron g-2 from a Search for Invisible Decays of a Scalar, Pseudoscalar, Vector, and Axial Vector.

We performed a search for a new generic X boson, which could be a scalar (S), pseudoscalar (P), vector (V), or an axial vector (A) particle produced in the 100 GeV electron scattering off nuclei, e^{-}Z→e^{-}ZX, followed by its invisible decay in the NA64 experiment at CERN. No evidence for such a process was found in the full NA64 dataset of 2.84×10^{11} electrons on target. We place new bounds on the S, P, V, A coupling strengths to electrons, and set constraints on their contributions to the electron anomalous magnetic moment a_{e}, |Δa_{X}|≲10^{-15}-10^{-13} for the X mass region 1 MeV≲m_{X}≲1 GeV. These results are an order of magnitude more sensitive compared to the current accuracy on a_{e} from the electron g-2 experiments and recent high-precision determination of the fine structure constant.

Hunting down the X17 boson at the CERN SPS.

Recently, the ATOMKI experiment has reported new evidence for the excess of e + e - events with a mass ∼ 17 MeV in the nuclear transitions of 4 He, that they previously observed in measurements with 8 Be. These observations could be explained by the existence of a new vector X 17 boson. So far, the search for the decay X 17 → e + e - with the NA64 experiment at the CERN SPS gave negative results. Here, we present a new technique that could be implemented in NA64 aiming to improve the sensitivity and to cover the remaining X 17 parameter space. If a signal-like event is detected, an unambiguous observation is achieved by reconstructing the invariant mass of the X 17 decay with the proposed method. To reach this goal an optimization of the X 17 production target, as well as an efficient and accurate reconstruction of two close decay tracks, is required. A dedicated analysis of the available experimental data making use of the trackers information is presented. This method provides independent confirmation of the NA64 published results [1], validating the tracking procedure. The detailed Monte Carlo study of the proposed setup and the background estimate show that the goal of the proposed search is feasible.

RESULTS OF EXTRACORPOREAL NEPHRON-SPARING SURGERY FOR RENAL CELL CARCINOMA WITH AUTOTRANSPLANTATION.

The study included 12 patients who underwent extracorporeal nephron-sparing surgery followed by autotransplantation of the kidney to the iliac region. A solitary kidney occurred in 7 (58.3%) cases, bilateral tumors in 2 (16.7%) cases, a significant decrease in the function of the contralateral kidney in 2 (16.7%) cases, and relative imperative indications in 1 (8.3%) patient. The ECOG status 0, 1 and 2, respectively, was recorded in 3 (25%), 6 (50%) and 3 (25%) cases. The glomerular filtration rate in patients (GFR) averaged 51.5±16.8 ml/min, the blood creatinine level was 157.9±58.2 µmol/L, and the body mass index (BMI) was 27.7±4.9 kg/m2. The average size of tumors in the entire group reached 5.6±1.8 cm (3 to 9 cm). T1 stage was registered in 6 cases, T3a was diagnosed in another 6 cases. Besides, invasion into the renal vein was detected in 4 patients, into the pararenal or renal sinus fat in another 4 patients, into the pelvicalyceal system lumen in yet another 4 patients. Intrarenal tumors were found in 11 (91.7%) patients. Different types of vascular reconstruction were required in 4 (30%) out of 12 patients. The average time of surgical interventions reached 270.8±25.0 minutes. The average cold ischemia time during extracorporeal partial nephrectomy was 47.8±7.8 minutes. The average overall time frame of vascular anastomosis was 56.4±6.4 minutes. The volume of blood loss varied from 400 to 700 ml (on average 558.3±99.6 ml). Postoperative complications Grade III-IV by Clavien-Dindo classification were recorded in 5 (41.7%) patients. Oligoanuria in the postoperative period occurred in 4 (33.3%) patients, but hemodialysis was necessary only in two of them. Postoperative mortality was observed in two (16.7%) cases. The graft loss rate was 16.7% (bleeding and chronic urinary fistula). Long-term results were evaluated in all 10 patients. Currently none of the patients requires chronic hemodialysis. The average creatinine level after surgery in the entire group was 139.3±46.1 µmol/L (from 102.4 to 260 µmol/L). Δ serum creatinine varied from 4.0 to 60.0 µmol/L (on average 25.3±17.6 µmol/L). Δ GFR on average did not exceed -9.3±8.6 ml/min. With an average follow-up period of 42 months, no locoregional RCC recurrences were detected in any of the cases. Metachronous metastases to the lungs were found in one patient 2 years after surgery. Extracorporeal removal of a kidney tumor with renal autotransplantation is an effective method of nephron-sparing surgery in patients with imperative indications for kidney preservation. However, this technique is accompanied by a high rate of complications Grade ≥ III-IV by Clavien-Dindo system, which must be taken into account while defining the indications for its use.

Search for Axionlike and Scalar Particles with the NA64 Experiment.

We carried out a model-independent search for light scalar (s) and pseudoscalar axionlike (a) particles that couple to two photons by using the high-energy CERN SPS H4 electron beam. The new particles, if they exist, could be produced through the Primakoff effect in interactions of hard bremsstrahlung photons generated by 100 GeV electrons in the NA64 active dump with virtual photons provided by the nuclei of the dump. The a(s) would penetrate the downstream HCAL module, serving as a shield, and would be observed either through their a(s)→γγ decay in the rest of the HCAL detector, or as events with a large missing energy if the a(s) decays downstream of the HCAL. This method allows for the probing of the a(s) parameter space, including those from generic axion models, inaccessible to previous experiments. No evidence of such processes has been found from the analysis of the data corresponding to 2.84×10^{11} electrons on target, allowing us to set new limits on the a(s)γγ-coupling strength for a(s) masses below 55 MeV.

URETEROCALICOSTOMY FOR RECONSTRUCTION OF THE UPPER URINARY TRACT.

The paper provides a retrospective study of long-term results of ureterocalicostomy (UC) performed in one specialized center. The study included 37 patients who underwent UC as a primary (43.2%) or secondary (56.8%) operation for intrarenal hydronephrosis or urolithiasis. All surgical interventions were classified into two groups according to the type of kidney resection: Type I - if the kidney parenchyma was more than 10 mm, the entire lower pole of the kidney was removed (72.9%); Type II - if the parenchyma was less than 10 mm, a part of the lower pole (1.5-2.0 cm) was removed in the zone of maximal parenchymal thinning (24.3%). All resections, depending on the angle of their plane, were also divided into transverse (48.6%) and oblique (51.4%). Early postoperative complications were observed in 14 (37.8%) patients. All complications were not severe and were classified as Grade I-II according to the Clavien-Dindo system. The univariate analysis showed that the predictors of UC complications are the long duration of the operation, warm renal ischemia for more than 20 minutes, the secondary nature of the operation, as well as the presence of acute pyelonephritis and urinary extravasation before the operation. The rate of good long-term results was 81.1% (n=30), satisfactory - 13.5% (n=5), poor - 5.4% (n=2). The reliable prognostic value in terms of negative surgery results had: the thickness of the renal parenchyma below 10 mm, as well as the use of Type II resection of the renal parenchyma. Conclusion. A high level of good UC results was demonstrated. The most important predictor was the renal parenchyma thickness less than 10 mm.

RECONSTRUCTION OF THE UPPER THIRD OF THE URETER WITH A TUBULARIZED PELVIS FLAP IN DIFFICULT CLINICAL SITUATIONS.

Ureteroplasty with a tubularized pelvis flap is a very rare option for urethral reconstruction. This surgical approach allows replacing extended defects of the upper third of the ureter, and in some cases the entire ureter. Pelvic tubuloplasty can also be used to correct hydronephrosis associated with additional vessels to the lower pole of the kidney. Nowadays there are only a few reports on using tubular pyeloplasty in literary sources. Not all indications for this type of reconstruction have been studied yet. Thus, not all possible methods for the pelvis flaps formation have been developed. This article presents the experience of using this surgical technique in two patients with complex clinical situations. Our experience shows that displacement the anastomosis below the lower polar arteries or veins by using tubular pyeloplasty can exclude the pathological effect of these vessels on it. Therefore, this reconstruction can be considered a standard technique for the surgical treatment of hydronephrosis caused by uretero-vasal conflict. However, this requires practical confirmation, because there is no experience of using such surgical tactics presented in the world literature now. The second clinical observation showed the possibility of reconstruction of an extended defect in the upper and middle third of the ureter by the tubular flap of the pelvis. The proposed technique for the formation of the flap allowed extending it by 2 cm and successfully performing an anastomosis between the flap and the ureter. The main advantage of this approach is the possibility of extending the flap not by reducing the width of its base, but by means of small transverse incisions at various points. This let us to save the blood supply to the flap.

Removal of the Tumor Thrombus from the Right Atrium without Extracorporeal Circulation: Emphasis on the Displacement of the Tumor Apex.

OBJECTIVES: To assess the outcomes of cavoatrial tumor thrombus removal using the liver transplantation technique for thrombectomy, a retrospective study was conducted. MATERIALS AND METHODS: Five patients with atrial tumor thrombi who underwent piggy-back mobilization of the liver, surgical access to the right atrium from the abdominal cavity, and external manual repositioning of the thrombus apex below the diaphragm (milking maneuver) were included into the study. Extracorporeal circulation was used in none of the cases. The average length of the atrial component of the tumor was 20.0 ± 11.7 mm (10 to 35 mm), and the width was 14.8 ± 8.5 mm (10 to 30 mm). In this work, the features of patients and surgical interventions as well as perioperative complications and mortality were analyzed. RESULTS: External manual repositioning of the tumor thrombus apex below the diaphragm was successfully performed in all patients. Tumor thrombi with the length of the atrial part up to 1.5 cm were removed through the extrapericardial approach. For evacuation of the thrombi with the large atrial part (3.0 cm or more), a transpericardial surgical approach was required. Specific complications associated with the access to the right atrium from the abdominal cavity (paresis of the right phrenic nerve, pneumothorax, and mediastinitis) were not detected in any case. The average clamping time of the supradiaphragmatic inferior vena cava (IVC) was 6.3 ± 4.6 min. The volume of intraoperative blood loss varied from 2500 to 5600 ml (an average of 3675 ± 1398.5 ml). CONCLUSION: Our work represents the initial experience in the liver transplantation technique for thrombectomy in distinct and well-selected patients with atrial tumor thrombi. The effectiveness of this approach needs further study. The video presentation of our research took place in March 2019 at the 34th Annual EAU Congress in Barcelona.

Dark Matter Search in Missing Energy Events with NA64.

A search for sub-GeV dark matter production mediated by a new vector boson A^{'}, called a dark photon, is performed by the NA64 experiment in missing energy events from 100 GeV electron interactions in an active beam dump at the CERN SPS. From the analysis of the data collected in the years 2016, 2017, and 2018 with 2.84×10^{11} electrons on target no evidence of such a process has been found. The most stringent constraints on the A^{'} mixing strength with photons and the parameter space for the scalar and fermionic dark matter in the mass range ≲0.2 GeV are derived, thus demonstrating the power of the active beam dump approach for the dark matter search.

Nanocontainer-Based Active Systems: From Self-Healing Coatings to Thermal Energy Storage.

We highlight the development of nanocontainer-based active materials started in 2006 at the Max Planck Institute of Colloids and Interfaces under the supervision of Prof. Helmuth Möhwald. The active materials encapsulated in the nanocontainers with controlled shell permeability have been first applied for self-healing coatings with controlled release of the corrosion inhibitor. The nanocontainers have been added to the paint formulation matrix at 5-10 wt % concentration, which resulted in attaining a coating-autonomous self-healing ability. This research idea has attracted the attention of many scientists around the world (>1500 publications during the last 10 years) and has already been transferred to the commercialization level. The current trend in nanocontainer-based active systems is devoted to the multifunctionality of the capsules which can combine self-healing, antibacterial, thermal, and other functionalities into one host matrix. This article summarizes the previous research done in the area of nanocontainer-based active materials together with future perspectives of capsule-based materials with antifouling or thermoregulating activity.

NEPHRON-SPARING SURGERY IN PATIENTS WITH RENAL CELL CARCINOMA EXTENDING TO THE MAIN RENAL VEIN: INTRARENAL AND EXTRARENAL THROMBECTOMY.

In most cases RCC with venous extension is an indication for radical nephrectomy. However, in patients with imperative indications for nephron-sparing surgery a kidney resection with thrombectomy in rare situations is possible. We present a surgical technique for nephron-sparing surgery in patients with tumor spreading into the main renal vein. From 2007 to 2019 seven partial nephrectomies with removal of the tumor thrombus from the main renal vein were performed. Absolute imperative indications were recorded in 6 (85.7%) patients (4 with solitary kidney, 2 with bilateral tumors). Dimensions of renal tumor averaged 6.5±2.3 cm. Intravenous part of the tumor penetrated the initial portion of the renal vein in 3 cases, main trunk of the renal vein in 3 cases, and cavarenal portion of the IVC in 1 case. The average length of the tumor thrombus was 24.0±6.9 mm, and the width was 9.3±4.8 mm. Tumor thrombi were classified as intrarenal and extrarenal. In accordance with this principle surgical procedures were divided into partial nephrectomy with intrarenal (3/42.9%) and extrarenal thrombectomy (4/57.1%). Intrarenal thrombectomy was characterized by thrombus removal out of the vein lumen from the side of the kidney resection area, while extrarenal thrombectomy included additional opening the lumen of the main renal vein or inferior vena cava (IVC). In one patient hypothermic perfusion of the kidney in situ was used. In two cases the extracorporeal partial nephrectomy with kidney autotransplantation was performed. Warm ischemia time averaged 14.0 minutes. The time of ischemia during hypothermic perfusion in situ reached 76 minutes, the time of cold ischemia during extracorporeal surgery averaged 68.0 minutes. The volume of blood loss did not exceed an average of 621.4±146.8 ml. Early postoperative complications occurred in 4 (57.1%) cases (bleeding -1, ischemic stroke -1, deterioration of renal failure -2). Postoperative mortality was registered in 1 patient due to bleeding and heart failure. The follow-up period averaged 28.7±18.9 months. Distant metastases occurred in 1 (14.3%) patient after 16 months. Local tumor recurrence in the remnant kidney after nephron-sparing surgery was not detected in any case. Nephron-sparing surgery may be used to treat patients with kidney tumors and neoplastic venous thrombosis. However, this complex surgical approach requires further technical improvement.

Nanoencapsulation of phase change materials for advanced thermal energy storage systems.

Phase change materials (PCMs) allow the storage of large amounts of latent heat during phase transition. They have the potential to both increase the efficiency of renewable energies such as solar power through storage of excess energy, which can be used at times of peak demand; and to reduce overall energy demand through passive thermal regulation. 198.3 million tons of oil equivalent were used in the EU in 2013 for heating. However, bulk PCMs are not suitable for use without prior encapsulation. Encapsulation in a shell material provides benefits such as protection of the PCM from the external environment and increased specific surface area to improve heat transfer. This review highlights techniques for the encapsulation of both organic and inorganic PCMs, paying particular attention to nanoencapsulation (capsules with sizes <1 µm). We also provide insight on future research, which should focus on (i) the development of multifunctional shell materials to improve lifespan and thermal properties and (ii) advanced mass manufacturing techniques for the economically viable production of PCM capsules, making it possible to utilize waste heat in intelligent passive thermal regulation systems, employing controlled, "on demand" energy release/uptake.

[ОPTIMIZATION OF EXAMINATION ALGORITHM FOR PATIENTS BEFORE AND AFTER OPERATIVE INTERVENTION FOR HYDRONEPHROSIS].

Algorithm of the patients examination, suffering hydronephrosis, caused by obstruction of different etiology, was optimized, what permitted, using qualification of rational volume and sequence of diagnostic methods, owing high sensitivity and specificity, as well as morphological diagnostic coefficients (parenchymal­stromal, dysbalance of collagens) and the risk criterion for recurrence occurrence, to estimate renal structure­ functional state, to determine the disease stage, its course severity and to substantiate a volume and duration of preoperative preparation needed, the operative intervention kind and postoperative management of the patients.

[COMPLICATIONS OF SURGICAL TREATMENT OF A RENAL­CELL CANCER WITH INTRAVENOUS SPREADING].

Retrospective investigation, conducted for estimation of perioperative complications, while performing surgical treatment of a renal­cell cancer with tumoral thrombi, was presented. In 132 patients the tumoral thrombi spreading is restricted by renal vein and by vena cava inferior (VCI) as well. The patients were operated on, using the "chevron" access in the absence of artificial blood circulation. Perioperative complications rate in the patients in presence of macroscopic tumoral thrombi constitute 56.8%, while tumoral spreading into VCI ­ is trustworthy bigger (р<0.05). Presence of cardiac insufficiency, tumoral invasion of the VCI wall, retrograde spreading of thrombus with the VCI concurrent blood thrombosis, аs well as presence of the indices in accordance to the ECOG scale more than 1 point have constituted unfavorable factors.

[CREATING A CROSS-TUNNEL UNDER OSTIUM OF MAIN HEPATIC VEINS AND PIGGY BACK FUND LIVER ABLATE TUMOR THROMBUS FROM THE INFERIOR VENA CAVA].

The analysis of the effectiveness of a new method of thrombectomy, including the formation of cross-tunnel under the ostium of the main hepatic veins by removing tumor thrombus of the inferior vena cava (IVC). Successfully perform a piggy back manage to mobilize the liver in 12 (80%) patients, a tunnel formed in 4 (50%). Duration pigg back stage liver mobilization much higher than the formation of the tunnel. Forming tunnel cross recommended conditions when the IVC portion covered retrohepatic liver less than 1/2 of a circle or when the surgeon is sure to Derform manipulation capabilities.

[SURGICAL TECHNIQUE OF A RENAL ARTERY CONTROL WHILE REMOVAL OF TUMORAL THROMBI FROM VENA CAVA INFERIOR].

Efficacy and safety of a renal artery ligation after thrombectomy in comparison with those while using a standard surgical technique were studied. Possibility of performance and safety of thrombectomy without preliminary ligation of renal artery was proved. The results did not depend on level of intravenous tumoral spread and were significantly better, than while application of standard approaches to renal artery because of absence of embolic complications.

[ABDOMINAL TRANSDIAPHRAGMATIC EXTRAPERICARDIAL SURGICAL ACCESS TO SUPRADIAPHRAGMATIC PART OF VENA CAVA INFERIOR IN PATIENTS OPERATED FOR RENAL-CELL CANCER].

Safety and possibility to perform abdominal surgical accesses to supradiaphragmatic part of vena cava inferior (VCI) in patients, operated on for renal-cell cancer, were estimated. In 12 patients the results of application of several surgical access variants to supradiaphragmatic part of VCI were estimated. Most simple and safe way to isolate supradiaphragmatic VCI and cavaatrial junction is to perform a T-like diaphragmotomy. Intraoperative complications rate have constituted 36.4%. The blood loss volume due to VCI injury (in 3 cases) while performing transdiaphragmatic surgical access to supradiaphragmatic part of VCI, have constituted 112.5 ml at average. Injuries of pleura, pericardium, main truncus of diaphragmatic nerve did not occur.