Paraesthesia after hamstring graft harvest is a ubiquitous complication in the early post-operative period, and its correlation with vertical versus horizontal skin incision are well documented. The purpose of the study is to evaluate the incidence and extent/area of sensory loss of saphenous nerve branches occurring with the outside-in (OI) versus inside-out technique (IO) of semitendinosus graft harvest from the sartorius fascia and to determine a better method of graft harvest.Sixty patients who underwent isolated semitendinosus graft harvest during anterior cruciate ligament reconstruction (ACLR) between 2016 and 2017. Patients were randomised into two groups depending on the graft harvest technique: 30 in the OI group and 30 in the IO group. The area of sensory loss was mapped on the patients’ skin using tactile feedback from the patients at each follow-up . Then, the area of sensory changes for the infrapatellar branch (IPBSN) and sartorial branch (SBSN) of the saphenous nerve, incision length, graft harvest duration, and graft length were analysed statistically between the groups.p = 0.79). Isolated SBSN and IPBSN paraesthesia occurred in 2/60 (3%) and 19/60 (32%), respectively. Combined SBSN and IPBSN paraesthesia was present in 16/60 (27%) of patients. There was no significant difference in the area of the sensory deficit between OI and IO groups on the 10th post-operative day or at 1-month, 3-month or 1-year follow-up . However, at 6-month follow-up, the area of paraesthesia was significantly higher in the IO group (p = 0.009). The length of incision and duration of graft harvest was higher in the OI group than in the IO group , and the total length of the graft was greater in the IO group (p = 0.04).In groups 1 and 2, 18/30 (60%) and 19/30 (63%) of patients, respectively, developed sensory changes, with no significant difference between the groups (Incidence is equally distributed, area of iatrogenic saphenous nerve injury gradually decreases, and recovery is seen in the majority of the patients in both graft harvest techniques. IO graft harvesting technique is better in terms of graft harvest time and cosmetics and yields longer graft; however, area of paraesthesia, though not significant, was two-fold higher than the OI technique at 1-year follow-up.IO graft harvest technique would enable the surgeon to adopt quicker graft harvest, smaller surgical scar and lengthier graft than the OI technique.Therapeutic randomised controlled prospective study, Level II. Hamstring graft is a safe and effective alternative to patellar tendon autograft with comparable clinical outcomes. It has a lower rate of anterior knee pain in anterior cruciate ligament (ACL) reconstruction , 2. The Harvesting the semitendinosus graft has a lower risk of injury to branches of the saphenous nerve than harvesting both the hamstring grafts (semitendinosus and the gracilis) . TransecThe most prevalent technique of hamstring graft is the outside-in (OI) technique , 14 techn = 30) or the IO group (n = 30) on the basis of hamstring graft harvest technique. Ethical committee and institutional review board (IRB) approval was obtained for this study (IRB number 2016/02/04). Patients aged between 18 and 50 years who underwent arthroscopic ACL reconstruction with a single graft (semitendinosus) were included  in all cases. In both techniques of hamstring graft harvest, an oblique skin incision was made, 2 cm below and medial to the tibial tubercle.Pes anserine fascia was not detached from the tibia in this technique. The fascia was opened via a horizontal nick on the outer aspect of the fascia Fig. A, then tIn the IO technique, pes anserine fascia detached along with proximal tibial periosteum by a meticulous technique of scraping the tibial periosteum along with fascia and the graft. The semitendinosus graft is visualised from the inner aspect of the fascia, and it is separated from the fascia. Then the graft is pulled out of the wound, and the vincula are released using Metzenbaum scissors. The tendon was harvested using a closed tendon stripper. Then, the graft was prepared, and the total length of the graft was measured and documented. After ACL reconstruction, the pes anserine fascia was sutured to the tibia. Patients were informed on the institutional rehabilitation protocol in both groups. Patients were mobilised with crutches and weight-bearing as tolerated from the first post-operative day, and active-assisted knee movements were started on the second day. Full weight-bearing walking with crutches was allowed from the second week and progressed to walking without crutches from the third post-operative week. Active knee movements started in the second week, and full knee range of movements was achieved by 4 weeks. Strengthening exercises and half-squat exercises began in the 12th week. Sports, running and squatting on the floor were allowed only from the sixth post-operative month.2) was measured and analysed with Image J software of the digital photographs. The paraesthesia area was mainly evaluated for cutaneous nerve distribution of the saphenous nerve and its terminal branches in the leg compartment.All the patients were clinically evaluated on the 10th post-operative day, then at 1, 3, 6 and 12 months of follow-up. The incision length was measured in centimetres, and the time taken to harvest the graft was recorded and documented. The subjective area of sensory loss was assessed for the involvement of SBSN, IPBSN and combined anatomical zones of these nerves. A blunt pin was used for pinprick examination starting from the superior pole of the patella then moved distally in all directions. The patient was asked to point out the change in sensation from altered to normal skin sensation, marked with a skin marking pen . Effect size is calculated by taking the difference between the two groups and dividing it by the standard deviation of one of the groups. The chi-squared test was used to compare the categorical variables between the two groups, and a paired p = 0.79) difference between the two groups  (Table p = 0.009) . At 1 year follow-up, three patients in the IO group and four in the OI group had persistent paraesthesia, with complete recovery in the remaining patients. Further, the length of incision was greater in the OI group, and the duration of graft harvest was longer in the OI group than the IO group , and the mean total length of the graft was longer in the IO group (p = 0.04)  were enrolled as per inclusion and exclusion criteria with a minimum follow-up of 12 months. The right knee was involved in 42 patients, and the left knee in 18 patients. In this study, 37/60 (62%) of the patients developed sensory changes due to iatrogenic injury to branches of the saphenous nerve. Statistically, there was no significant  compared with oblique skin incision (9.3 ± 15.3 cm2). Unlike their study, we compared the area of paraesthesia for graft harvest technique (OI versus IO technique) rather than skin incision. In our study, the average area of sensory loss was significantly larger in the IO group than in the OI group at 6-month follow-up . There was a drastic reduction in the area of sensory loss in the OI group, and a gradual reduction in the IO group, which explains the significant difference at month 6. This is due to the technical aspect of harvesting in the OI group, where the sartorius fascia is not being detached; it is possible that recovery is faster with OI graft harvest technique. However, at 1-year follow-up, though the area of paraesthesia in the IO group was twice as large as in the OI group, there was no statistically significant difference between the groups. The clinical implication is a gradual reduction in the sensory loss in both groups that could continue even after 1 year of follow-up. This is supported by Zhu et al. [Aglietti et al.  reportedu et al.  found thu et al. , who repu et al. , 26–28 hu et al. –29. RuffThe pattern of iatrogenic injury in our study was similar to that observed by Sanders et al. , who mapThe residual paraesthesia in our study was 19% at 1-year follow-up; on the contrary, Spicer et al.  reportedAdequate graft length is necessary for single graft  reconstruction without compromising on fixation . IO grafKhanna et al.  suggesteLimitations of our study include that the observations were made by a single surgeon and the follow-up period was short. Moreover, limited cohort and subgroup analysis could not be carried out as the sample size was insufficient to draw robust statistical conclusions. Additional assessments, that is, an electrophysiological study, would have been helpful. Fortunately, the clinical ramifications of electrophysiological events are usually low, and most nerve injuries do not result in much disability/morbidity. However, neurovascular injuries can have medico-legal implications; thus, it is essential to understand that nerve injury may be an inherent problem associated with mini-incision and distal-to-proximal harvest. Patients should be informed about this event.Incidence is equally distributed, area of iatrogenic saphenous nerve injury gradually decreases, and recovery is seen in the majority of patients in both techniques of graft harvest. IO graft harvesting technique was better in terms of graft harvest time and cosmetics and yielded longer graft; however, area of paraesthesia, though not significant, was two-fold higher than OI technique at 1-year follow-up.


Yue‐Ming He, Zhong‐Lin Zhang, Quan‐Yan Liu, Yu‐Sha Xiao, Lei Wei, Chen Xi and Xiang Nan. J Cell Mol Med. 2018; 22: 2569‐2579 (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor‐in‐Chief and John Wiley & Sons Ltd. The retraction has been agreed following an investigation based on allegations raised by a third party. Inconsistencies in flow cytometry experiments were found and several image elements of presented western blots were found to be published previously in a different scientific context. The editors consider the conclusions invalid.The above article from Journal of Cellular and Molecular Medicine, published online on 8 March 2018 on Wiley Online Library (


Patients receiving split thickness skin grafting due to deep burns are left with scarring and chronically dysfunctional skin at the graft site. Given evidence that patients’ pre-operative expectations mediate post-operative outcomes and satisfaction, we sought to describe burn patients’ experience, expectations, and satisfaction with their skin graft, and their views towards a future cell-based clinical trial to improve their graft, over time. We also aimed to identify graft outcome measures for use in future studies.This study was approved by our university's research ethics board. All participants provided written and informed consent. Data were collected via patient questionnaires pre-operatively, one, and three months post-operatively.1 = -0.290, p = 0.008). Significant improvements in skin function  and appearance  at the wound site during recovery were observed, although patients noted great difference between grafted and normal skin. Patient satisfaction with their graft did not change significantly over time. Patients were willing to participate in a cell-based clinical trial that may improve graft symptomology. They prioritized diminished scarring, redness, and improved sensation and elasticity as the most salient aspects of grafts to be enhanced by cell-based therapy.Most patients had small burns. Expectations of graft function were consistent pre- and post-operatively. Expectations of graft appearance showed significant decrease over time (β Patient graft concerns changed over time; outcome measures in trials advancing skin grafting should reflect chronic, patient prioritized limitations.


The aim of this study was to assess whether the autologous internal iliac artery and vein could be used as an interpositional graft for vascular reconstruction in segmental intestinal allografts and autografts.Thirty-four intestinal transplants  were conducted in our programs between January 2011 and January 2019. Patient characteristics, type of vascular reconstruction, and post-operative complications were reviewed.P = 0.118). At a median follow-up of 36.9 months, no stenosis or pseudoaneurysms developed. In 19 allografts, acute rejection occurred in 4 (21.1%) and chronic rejection occurred in 1 (5.2%).There were 20 males and 14 females with a median age of 35 years. Of 34 grafts, 22 (64.7%)  were revascularized using the autologous internal iliac artery and vein for reconstruction. Vascular reconstruction on the back table took 21 ± 6 min to complete. Both total operative time and cold ischemia time tended to be longer in the vascular-reconstruction group than in the direct-anastomosis group , but these differences were not significant. The incidence of vascular thrombosis tended to be higher in the direct-anastomosis group than in the vascular-reconstruction group (16.7% vs 0%, Our results indicate that the use of an autologous internal iliac interposition graft greatly facilitates intestinal graft implantation and minimizes the risk of vascular complications. Despite recent advances in the medical and surgical management of intestinal failure, intestinal transplantation (ITx) continues to play an important role , 2. To dAn isolated intestinal allograft can be procured from either cadaveric or living donors with a pedicle containing the superior mesenteric artery (SMA) and superior mesenteric vein (SMV). Due to the short length and small caliber of the donor's mesenteric vessels, it is often technically challenging to connect the donor's mesenteric vessels to the recipient's inferior aorta and vena cava or superior mesenteric vessels and is particularly challenging in living-related ITx (LR-ITx) and pediatric ITx , 8. In tex vivo surgery and autotransplantation have successfully been performed for the kidney, liver, and heart [et al. [en bloc removal of a tumor together with the intestine, ex vivo tumor resection, followed by reimplantation of the intestinal autograft. We further refined this complex technique with the initial selection and procurement of a healthy segmental bowel autograft, in vivo radical tumor resection, followed by intestinal graft reimplantation. In this setting, the use of vascular conduits is frequently required to extend the length of the vascular pedicle of a graft [With advances in organ preservation and surgical techniques, nd heart . Tzakis  [et al. , 13 init a graft .The internal iliac artery and vein may be an ideal option for SMA and SMV reconstruction because they are of adequate length (∼3–4 cm) and diameter for segmental intestinal transplants. In this study, we hypothesized that the use of internal iliac vessels for vascular reconstruction may increase the potential of successful anastomosis and reduce the risk of vascular complications.Thirty-four segmental intestinal transplants, composed of 19 living-related allografts and 15 autografts, were performed at two centers  from January 2011 to January 2019. Patients were divided into the direct-anastomosis group and the vascular-reconstruction group. Patient data were retrieved from prospectively maintained computerized databases, flow charts, and medical records. All patients underwent contrast-enhanced computerized tomography (CT) scan as a routine preoperative assessment. CT angiography with 3D image reconstruction was performed to evaluate the donor's intestinal vascular anatomy and the recipient's external and internal iliac arteries . The InsThe operative techniques of LR-ITx and IATx have previously been described in detail by our team and others , 15. In Once complete hemostasis is achieved, the bowel autograft is brought into the surgical field and revascularized to the recipient's infrarenal aorta and vena cava or superior mesenteric vessels. The gastrointestinal tract is reconstructed using either an end ileostomy to monitor graft function in LR-ITx or a 45- to 50-cm Roux-en-Y limb for pancreaticoenterostomy, choledochoenterostomy, gastroenterostomy, and ileocolostomy in IATx.After the operation, intravenous albumin is administered to maintain blood levels at >30 g/L. Prophylactic antibiotics are given for 48 hours post-operatively. Vascular complications were closely monitored, including artery or vein thrombosis, stenosis, and pseudoaneurysm. Bedside duplex Doppler sonography is performed to check the patency of the SMA and SMV immediately after patients are transferred to the intensive care unit from the operating room and then daily for 3 consecutive days post-operatively. 3D CT angiography is used to confirm the patency of the graft vessels and the blood supply to the bowel autograft when Doppler imaging is inadequate . IntraveThe primary outcome of this study was vascular complications after the procedure, including vascular thrombosis, arterial stenosis, and pseudoaneurysms etc.t-test (two-tailed) comparison between two groups of data sets. Fisher exact test was used to determine whether there is a significant difference between the two proportions. A P-value of ≤0.05 was considered significant.All data are expressed as mean ± standard deviation. Statistical significance was determined using Student’s There were 20 men and 14 females with a median age of 35 years. In our series, short gut syndrome was the most common surgical indication for LR-ITx, which is the treatment of choice for patients who develop intractable TPN-related complications such as liver dysfunction, lack of central venous access, and catheter-related sepsis. IATx is reserved for a select subset of patients with locally invasive neoplasm closely involving the SMA without evidence of distant metastases. In this study, these neoplasms commonly originate in the head of the pancreas and the mesenteric root. A more detailed description of these patients was reported in our previous studies .ex vivo vascular reconstruction. Y-graft reconstruction was performed in five cases due to either double vein (n = 2) or double arteries (n = 3).Four types of vascular reconstruction are summarized in Clinical characteristics of direct anastomosis vs vascular reconstruction are summarized in In our series, 2 of 12 patients in the direct-anastomosis group developed vascular thrombosis after surgery, but there was no thrombosis in patients with vascular reconstruction. The first patient was a 63-year-old man who underwent near-total enterectomy due to a mesenteric desmoid tumor and subsequently received a segmental bowel autograft. We experienced technical difficulties during anastomosis of the graft artery to the recipient's infrarenal aorta due to a short pedicle length, small graft vessel caliber, and severe calcification of the recipient's aorta. The patient developed thrombosis at the SMA anastomosis 48 hours post-operatively. Since the necrotic bowel graft was removed, the patient has been on full TPN support. The second patient received two independent segmental bowel autografts: the graft vein of the first segment was anastomosed to the splenic vein; the graft vein of the second segment with iliac vein Y-graft reconstruction was anastomosed to the infrarenal vena cava. Acute venous thrombus in the first graft was detected at the anastomosis by Doppler ultrasonography 8 hours after IATx. Following immediate open thrombectomy, the graft was successfully salvaged.P = 0.118; The incidence of vascular thrombosis tended to be higher in the direct-anastomosis group than in the vascular-reconstruction group (16.7% vs 0%), but these differences did not reach statistical significance .


Two distinctvacant tetrahedral sites were identified at the end of two distinctfinite Li6O1626– chains. Li4P6O17 features a new type of loop-branchedchain defined by six PO43– tetrahedra.The ionic conductivities and electrochemical properties of Li3P5O14 were examined by impedance spectroscopycombined with DC polarization, NMR spectroscopy, and galvanostaticplating/stripping measurements. The structure of Li3P5O14 enables three-dimensional lithium migrationthat affords the highest ionic conductivity (8.5(5) × 10–7 S cm–1 at room temperature forbulk), comparable to that of commercialized LiPON glass thin filmelectrolytes, and lowest activation energy (0.43(7) eV) among allreported ternary Li–P–O phases. Both new lithium ultraphosphatesare predicted to have high thermodynamic stability against oxidation,especially Li3P5O14, which is predictedto be stable to 4.8 V, significantly higher than that of LiPON andother solid electrolytes. The condensed phosphate units defining theseultraphosphate structures offer a new route to optimize the interplayof conductivity and electrochemical stability required, for example,in cathode coatings for lithium ion batteries.Extended anionicframeworks based on condensation of polyhedralmain group non-metal anions offer a wide range of structure types.Despite the widespread chemistry and earth abundance of phosphatesand silicates, there are no reports of extended ultraphosphate anionswith lithium. We describe the lithium ultraphosphates Li Crystal structures with 2,3-connectedanionic networks occur in polysilicates, phyllosilicates, and polyaluminates,such as loop-branched single chain Si4O114– in Li2Mg2Si4O11,17 double chain Al3O87– in Na7Al3O8,19 and infinite single layer Si3O84– in Na2ZnSi3O8 .29 In contrast, the more open 2,3-connectedanionic networks of ultraphosphates are of interest because they couldcreate large void spaces that form favorable channels or interstitialpositions for cations to diffuse through the structure. For example,the ultraphosphate layer could provide large PO43– based rings, such as 16-membered rings in the P4O112– layer  have been achieved in someoxide- and sulfide-based materials.40 ASLiBs can suffer from high interfacial resistance even when suchhighly conductive SSEs were used, which is largely due to the poorcontact or incompatibility between SSEs and electrodes.41 Introducing a buffer layer at the cathode/SSEinterface has been proposed as an effective method to suppress growthof the interfacial resistive layer. A range of cathode coatings havebeen investigated, and some of them have shown significant improvementof electrochemical properties of ASLiBs, including Li4Ti5O12,42 LiNbO3,43 LiTaO3,44 LiAlO2,45 Li2SiO3,46 Li3BO3–Li2CO3,47 and Li2ZrO3.48 However, due to their limited ionic conductivities or oxidativestability, the electrode resistance can be dominated by the coatinglayer itself, which hinders the further improvement of the electrochemicalperformance of the ASLiBs.50This gap in our understandingof phosphate chemistry can be seenin the recent development of all-solid-state Li-ion batteries (ASLiBs),which has relied on the discovery of superionic conductors to actas solid-state electrolytes (SSEs) in bulk and thin film form.–6 S cm–1 can be used as thin filmelectrolytes. For example, lithium phosphorus oxynitride (LiPON) hasbeen widely used in commercial solid-state thin film batteries dueto its acceptable room temperature ionic conductivities ((1–3)× 10–6 S cm–1) and excellentlong-term stability in contact with Li metal.53 Compared withthe electrolytes, coating materials have stricter requirements interms of chemical and electrochemical stabilities. A practical cathodecoating should be chemically compatible with both the cathode, andthe SSE and should have an electrochemical window that spans the cathodeoperating voltage and overlaps with the electrochemical window ofthe electrolyte. Li3PO4 is considered one ofthe promising coatings because of its excellent chemical and electrochemicalstabilities and convenient sources without complex processing.57 A recent report on computationalevaluation of potential coatings identified that phosphates exhibithigher oxidation stability limits and lower reactivity with thiophosphateelectrolytes than conventional ternary metal oxide coatings such asLiTa3O8, LiNbO3, LiAlO2, and that the oxidation stability increases as the phosphate condensationincreases.58 As a result, lithium polyphosphateLiPO3 has been highlighted as one of the appealing candidatefor cathode coatings, as it has a higher oxidation limit than thatof Li3PO4. However, both Li3PO4 and LiPO3 still suffer from very limited Li-ionconductivities (∼10–16–10–19 S cm–1 for γ-Li3PO4 and ∼10–19 S cm–1 forLiPO3 at room temperature).61Phosphates havebeen proposed as both SSEs and coating materialsto develop ASLiBs. P is earth-abundant and phosphates have good overallcharacteristics, such as a wide electrochemical window, good chemicalstability, acceptable ionic conductivity, and negligible electronicconductivity, which are fundamental requirements for bulk and thinfilm SSEs or coating materials. Different from bulk electrolytes,thin film electrolytes and coatings are thin layers, so they haveless stringent requirements for ionic conductivity than the bulk electrolyte.Li ion conductors with a room temperature conductivity of around 1062 there arevery few studies on alkali metal ultraphosphates. Apart from someRaman and nuclear magnetic resonance (NMR) spectroscopic studies onlow alkali phosphate glasses that have provided evidence for the existenceof ultraphosphate anions in the presence of alkali metals,65 the structures of crystalline ternary lithium ultraphosphates andtheir functional properties are unknown.Lithium ultraphosphateswould offer structural diversity to addressthis problem. However, although the structures and functional propertiesof alkali metal orthophosphates, polyphosphates, and cyclophosphateshave been well studied in the literature,43– tetrahedra in ultraphosphatesmay favor the mobility of the cations,thereby offsetting low Li ion content and leading to potential increasesin ionic conductivity. It is therefore important to identify lithiumultraphosphates and explore the arising electrochemical stabilityand ion mobility when the Li/P ratio falls below that in previouslystudied Li–P–O ternaries.67 We report two lithiumultraphosphates Li3P5O14 and Li4P6O17 with different structural motifs,synthesized using solid-state methods. Li3P5O14 shows the highest ionic conductivity and lowest activationenergy among reported ternary oxides in the Li–P–O phasefield, which can be attributed to its unique 3D lithium migrationpathways evidenced through bond valence sum (BVS) mapping.68 Li3P5O14 ischemically stable in air. Both Li3P5O14 and Li4P6O17 have relatively highcomputed thermodynamic stability against oxidation: Li3P5O14 is predicted to be stable up to 4.8 V,significantly higher than other solid electrolytes,72 including other phosphates and the commercialized LiPON thin filmelectrolyte with comparable lithium conductivity.70The unique topologicalarrangement of PO22.12.1.12O (97%)and P2O5 (≥98.0%) purchased from Sigma-Aldrichwere dried overnight under vacuum (10–4 mbar) atroom temperature before being transferred into an Ar-filled glovebox.All precursors and resulting powders were handled in an Ar-filledglovebox .Li2.1.23P5O14 was performed in two steps: First, Li2Oand P2O5 with a molar ratio of 3:5 were mixedvia ball milling under an inert argon atmosphere in a Fritsch Pulverisette6 planetary system using a zirconia bowl (45 mL) and seven balls (15mm in diameter) for 2 h at 300 rpm. The resulting powders were transferredto an alumina crucible, which was then sealed in a silica tube undervacuum (<10–4 mbar). The tube was heated to 573K at a ramp rate of 1 K min–1, held at 573 K for24 h, and cooled to room temperature at a rate of 1 K min–1. In a second step, the resulting powder was manually ground withan agate pestle and mortar for 30 min under an inert argon atmosphereand transferred to an alumina crucible and then sealed in an evacuatedsilica tube before heating to 723 K for 24 h with a heating and coolingrate of 5 K min–1. The resulting powder was thenmanually ground in a pestle and mortar and then pelleted, sealed inevacuated silica tube, and sintered at 743 K for 24 h to prepare densepellets for further characterization. Single crystals of Li3P5O14 were grown by heating the above-preparedpowder sample in an evacuated silica tube to 743 K for 24 h with aslow cooling rate of 1 K min–1.The synthesis of Li2.1.34P6O17 wereobtained with two heat treatments. A mixturewith a 3:5 ratio of Li2O and P2O5 was mixed with ball milling (same conditions as Li3P5O14), then sealed in an evacuated silica tube,and then heated to 773 K at a high ramp rate of 10 K min–1. After cooling, the resulting powder was then reground, pelleted,and sealed in an evacuated silica tube and heated at 673 K for 6 dayswith a ramp rate of 1 K min–1. Using this method,a sample with Li3P5O14 and Li4P6O17 crystals was obtained .Single crystals of Li3P5O14 synthesis was alsoused in an attempt to prepare pure bulk samples of Li4P6O17 with a stoichiometric ratio of Li2O and P2O5 (2:3). The synthesis was attemptedwith varying reaction temperatures (673–773 K) and reactiontimes (1–6 days); however, Li3P5O14 and LiPO3 always formed as the majority phases.The same synthetic procedureused in Li2.22.2.13P5O14 and100 K for Li4P6O17 during data collection.Li3P5O14 was also studied by singlecrystal XRD on beamline I19, Diamond Light Source, Didcot, U.K. usingsilicon double crystal monochromated synchrotron radiation .73 The synchrotron data were collected at 100 K. Cell refinement anddata reduction were carried out with the CrysAlisPro171.40_64.42asoftware.74 The structures were solvedusing the Intrinsic Phasing method provided by the ShelXT75 structure solution program and refined withthe ShelXL76 refinement package using LeastSquares minimization, interfaced through Olex2.77 For Li3P5O14, final anisotropicatomic refinements converged to R1 = 0.0378and wR2 = 0.0834 for reflections with I ≥ 2σ(I) for lab data, and R1 = 0.0343 and wR2 = 0.0851 for reflections with I ≥ 2σ(I) for synchrotron data. The Flack parameter is 0.06(4)for lab data and −0.03(3) for synchrotron data. For Li4P6O17, final anisotropic atomic refinementsconverged to R1 = 0.0269 and wR2 = 0.0720 for reflections with I ≥2σ(I). Both structure models were checked usingthe ADDSYM subroutine of PLATON78 to confirmthat no additional symmetry elements could be applied to the model.The structure description and analysis are based on lab data. Crystallographicdata and structural refinements are summarized in Table S1. The final refined atomic positions, isotropic thermalparameters, and anisotropic displacement parameters of each atom areillustrated in Tables S2–S5. Selectedbond distances and angles are given in Tables S6–S9.The single crystals suitable forstructure determination of the titlecompounds were selected under a polarizing microscope and then mountedon a Rigaku MicroMax-007 HF X-ray generator equipped with a Mo Kαrotating-anode microfocus source and a Saturn 724+ detector. The crystalswere kept at 293 K for Li2.2.21, λ = 1.54056 Å) in Debye–Scherrer transmissiongeometry with sample powders sealed in 0.5 mm diameter borosilicateglass capillaries. All experiments were performed at room temperature.Pawley and Rietveld refinements were carried out using TOPAS Academic.Pawley fits were performed, refining the lattice parameters and thebackground using a Chebyshev function with 12 parameters. The peakshape was modeled using a pseudo–Voigt function. Rietveld refinementswere performed with the single crystal model as a starting point withoutrefinement of lattice sites.Routineassessment of sample purity was carried out using a Bruker D8 Discoverdiffractometer with monochromatic Cu radiation . The pellet was then sinteredin an evacuated silica tube at 743 K for 24 h. A pellet with relativedensity of 85% was obtained. Gold electrodes were subsequently sputter-coatedonto both sides of the pellet using a Q150R Plus - Rotary Pumped Coater.AC impedance measurements were performed using a custom-built sampleholder, in the temperature range 303–573 K, using an impedanceanalyzer (Keysight Technologies E4990A) in the frequency range from2 MHz to 20 Hz (with an amplitude of 100 mV). All procedures and measurementswere carried out in an Ar-filled glovebox. The geometry-normalizedimpedance spectra were fitted with equivalent circuits using ZView2software.79A pelletof Li2.2.43P5O14|Auconfiguration under a 1 V DC bias potential at four different temperatures.A pellet that hadbeen used for AC impedance measurement was then used for DC polarizationmeasurements with a Au|Li2.2.53P5O14|Li cellswereassembled inside an Ar-filled glovebox . Li3P5O14 pelletswere polished to a thickness of ca. 0.3 mm. Two piecesof Li discs  were polishedand pressed onto Ni discs . The Ni/Li|Li3P5O14|Li/Ni stack was carefully aligned, compressed,and sealed inside a two-electrode Swagelok cell. The galvanostaticplating/stripping tests were performed at 298 K at a current densityof 2.5 μA cm–2  usingan MPG2 potentiostat (BioLogic Science Instruments).Symmetric Li|Li2.2.67Li NMR experiments were recordedwith a 4 mm HX High Temperature MAS Probe on a 9.4 T Bruker AvanceIII HD spectrometer under static conditions with the X channel tunedto 7Li at ω0/2π (7Li)= 156 MHz. The sample was sealed in a glass ampoule, and the spectrawere recorded with a pulse length of 1.5 μs at a radio frequency(rf) field amplitude of ω1/2π = 83 kHz andreferenced to 10 M LiCl in D2O at 0 ppm. Temperature calibrationswere performed using the chemical shift thermometers Pb(NO3)2 using 207Pb NMR80 and CuI and CuBr using 63Cu NMR.81 The errors associated with this method were calculated using theisotropic peak line broadening and range from 5 to 20 K.Variabletemperature 2.2.72 and moisture was kept <0.1 ppm. Sampleswere transferred into the TEM using a double tilt, beryllium vacuumtransfer holder from Gatan and into the SEM using a modified transferholder from Quantum. Electron diffraction patterns for Li3P5O14 were simulated and compared with theexperimental ones using Single Crystal software from CrystalMakerSoftware Ltd.Scanning Electron Microscopy(SEM) and Energy Dispersive X-ray spectroscopy (EDX) were performedwith a TESCAN S8000 equipped with an EDX detector from Oxford instruments.Powder samples were dispersed on a carbon tape attached to an aluminastub and coated with a thin film of carbon before performing imagingand EDX. Transmission Electron Microscopy (TEM) and Selected AreaElectron Diffraction (SAED) were performed on a JEOL 2100+ using adouble tilt holder. Powder samples were dispersed on a carbon coatedcopper TEM grid. In order to prevent the samples being exposed toair, samples were prepared inside an argon-filled glovebox in whichthe amount of O2.2.8–1 and coolingrate of 5 K min–1 under a constant flow rate ofN2 (50 mL min–1).Differential thermal analysis (DTA) and thermogravimetricanalysis(TGA) were carried out on a TA Instruments Q600 ThermogravimetricAnalyzer. Data were recorded on heating to 873 K and then coolingto RT with a heating rate of 10 K min2.2.93P5O14 and Li4P6O17 were assessed by first optimizinggeometries of their structures, and then comparing the calculatedvalues of their enthalpies with respect to the convex hull built forall known compositions in the Li–P–O phase field. Allcalculations were performed with DFT as implemented in VASP-5.4.482 with the plane-waves approach, PBE exchange-correlationfunctional, and projected augmented wave method for treating coreelectrons.83 During the geometry optimization,interatomic forces were decreased to less than 10–3eV Å–1, and changes of total energy in self-consistentruns were converged to less than 10–10 eV. The planewaves were sampled at 5 × 5 × 5 k-points mesh with energycut off at 700 eV.The thermodynamicstabilities of Li84 For each electrolyte compound (EC), we constructdecomposition reactionsxi and D1, D2, . . .decomposition products,and for each such reaction i we compute the correspondingequilibrium potential Φeq,i by the Nernst equation:85GD1, GD2, etc., are approximated as their enthalpies, computedwith DFT as described above. The electrochemical window is then approximatedby the phase stability window (not taking into account electron andion transfer), with the potential limits calculated as max for reduction and min for oxidation.The electrochemical stability window wascalculated with an approach analogous to the Li-grand canonical phasediagram.33.13.1.13P5O14 crystallizes in the monoclinicspace group Cc (no.9) with lattice parameters a = 33.3764(13) Å, b = 11.0005(2) Å, c = 15.0881(6) Å,β = 128.046(6)°, and V = 4362.6(4) Å3. There are 16 formula units per unit cell. In the asymmetricunit, there are 12 crystallographically distinct Li atoms, 20 P atoms,and 56 O atoms (43– tetrahedra with P–O bondlengths and O–P–O bond angles of 1.433(4)–1.631(3)Å and 97.19(18)°–124.2(2)°, respectively. Thesevalues agree with those commonly observed in other phosphates, particularlycondensed phosphates.90 Li3P5O14 has 88 unique atoms inthe asymmetric unit, which is the largest number for all reportedcrystallographically characterized lithium phosphates. The previousmost crystallographically complex lithium phosphate, from the 11 ternarylithium phosphates (Table S10), is themonoclinic polyphosphate LiPO3 (Pc) with 50 atoms in theasymmetric unit. Compared with unbranched 0D rings and finite ribbonor 1D infinite ribbons in these known ternary lithium phosphates,the branching PO43– tetrahedra in Li3P5O14 condense the PO43– tetrahedra in 2D to form an ultraphosphate layer.Li O atoms 2. The 123P5O14 is a layered structurebuilt from infinite ultraphosphate P20O5612– layers with 12-membered corrugated P12O3612– rings constructed from corner-sharingPO43– tetrahedra, alternately stackedwith Li polyhedral layers along the c axis –1.482(3) and 1.542(4)–1.631(3) Å,respectively. The P20O5612– layers consist of a succession of 12-membered corrugated P12O3612– rings of PO43– tetrahedra, which provide pathways for ion transport between adjacentLi polyhedral layers. There are four crystallographically distinctP12O3612– rings, which aresimilar in size and shape, and each is connected to six adjacent ringsthrough branching PO43– tetrahedra toform the infinite ultraphosphate layer. Alternatively, this stronglyanionic layer can also be described as built up by a set of zigzaginfinite PO3– ribbons parallel to the b axis constructed from alternating internal and branchingPO43– tetrahedra, and then interconnectedby internal PO43– tetrahedra, as shownin 20O5612– layer is analogous tosome phyllosilicate anions with 2,3-connected nets, such as singlelayer Si3O84– in Na2ZnSi3O8.20 The onemajor difference is the proportion of branching tetrahedra in theirlayer, which is 2/3 in Na2ZnSi3O8, higher than 2/5 of Li3P5O14, indicatingthe Na2ZnSi3O8 anions have higherdegrees of condensation than that of Li3P5O14.The Ptrahedra 4a in a 343– tetrahedrahave different connectivity with Li than those in the internal tetrahedra.Internal PO43– tetrahedra share two Oatoms with two of the neighboring branching PO43– tetrahedra, the remaining two O atoms are involved in coordinationto three to four different Li polyhedra that are either from two adjacentLi polyhedral layers or from two different types of Li6O1626– chains in the same Li polyhedrallayer  terminated with two distinct vacant tetrahedralsites, V1 and V2 ,and two LiO47– tetrahedra by edge sharing,as shown in These strong covalently bondedP1 and V2 5a. Theseng [110] 5c while  layer b 5d. These3.1.24P6O17 crystallizesin the triclinic space group P1 (no. 2) with two formula units per unit cell. The unitcell parameters are a = 7.3721(3) Å, b = 8.9291(3) Å, c = 10.8581(4) Å,α = 79.596(3)°, β = 81.961(3)°, γ = 70.413(3)°, V = 659.89(4) Å3. In the asymmetric unit,there are four crystallographically distinct Li atoms, six P atoms,and 17 O atoms . All the atomsoccupy 2i sites and are ordered. In the structure of Li4P6O17, six distinct PO43– tetrahedra share vertices to form a loop-branched P6O174– single ribbon with the periodic repetitionof 12 PO43– tetrahedra. These P6O174– ribbons are arranged in layersparallel to the (012) plane, alternating stacked with Li polyhedrallayers along the [012] direction, as shown in 4O124– 4-membered rings, which are arrangedalternately in P6O174– ribbons,as shown in 4O124– rings is 1 as observed in some reported cyclophosphates.3 The P4O124– 4-membered rings in Li4P6O17 areinterconnected by P2O74– groupsin 1D through branching PO43– tetrahedra,unlike the isolated rings in cyclophosphates.Li O atoms S1. All t O atoms S1. All t43– tetrahedra is 4:2 in Li4P6O17,which is higher than 3:2 in Li3P5O14, indicating the anions in Li3P5O14 are more condensed than those of Li4P6O17. The terminal and bridging P–O bond lengths are 1.4623(13)–1.4575(13)Å, and 1.5576(13)–1.5782(13) Å in branching tetrahedra,and 1.4662(13)–1.4686(13) and 1.5897(13)–1.6358(13)in internal tetrahedra, which are comparable to those in Li3P5O14 (Tables S6 and S7).The ratio of internal to branching PO3P5O14, theO inbranching PO43– tetrahedra have differentinvolvement in coordination to Li from those in internal PO43– tetrahedra. Internal PO43– tetrahedra share two of their O atoms with two of the neighboringPO43– tetrahedra and two in coordinationto three to four Li polyhedra. Branching PO43– tetrahedra share three of their O atoms with neighboring internalPO43– tetrahedra and one with two neighboringLi polyhedra, as shown in 8O2032– chainsarranged in parallel to each other and stacked along the [012] direction,as shown in 6O174– ribbons and are interconnected by internal PO43– tetrahedra.Similar to Li3.1.3n+2)(On+5) anion adopts 2D layers, the P5O143– anion (n = 3)adopts both infinite 1D ribbons94 and 2D layers whileonly 1D ribbons are observed for P7O205– (n = 5)92 and 0D finitegroups for P8O236– (n = 6).16 In order to meet the specificratio of internal and branching tetrahedra, the P5O143– anion adopts an alternating arrangementof internal and branching tetrahedra, while ultraphosphates with smallerand larger n values feature the branching–branchingand internal–internal tetrahedral connections, respectively.The general anionic formula for all observed ultraphosphates isP5O143– anion couldadopt a different 2D layered arrangement with different sizes of ringsbased on alternating arrangement of internal and branching tetrahedra.The P5O143– layers in monoclinicYP5O14 present a combination of 20- and 8-memberedrings,15 while the P10O286– layer in triclinic CeP5O14 presents 12-membered corrugated rings, which have the sameconnectivity as the infinite P20O5612– layers in Li3P5O14, as shown in 94 These rings are interconnected with each other in 2D throughtheir branching PO43– tetrahedra. Comparedwith the folded ultraphosphate layer in triclinic CeP5O14 °in Li3P5O14, consistent with thefolding of their ultraphosphate layers.The P CeP5O14 8a and 8cost flat 8b and 8d6O174– anion, including Ca2P6O17, Sr2P6O17, Cd2P6O17, and (UO2)2P6O17.96 The P6O174– anions in Ca2P6O17, Sr2P6O17, and Cd2P6O17 are characterized by infinite ultraphosphate layers constructedfrom 14-membered rings interconnected in 2D through their branchingPO43– tetrahedra. The P6O174– anion in (UO2)2P6O17 has a 3D network. In contrast, Li4P6O17 presents an infinite 1D loop-branchedP6O174– ribbon, which is thefirst example of a single ultraphosphate ribbon, contrasting withthe double ultraphosphate ribbons in monoclinic LaP5O14  and P7O205– in CaYP7O20 .There are only a few reported ultraphosphates with the P3.23P5O14, the heatingrate was controlled carefully to avoid the sublimation of P2O5 in the case of rapid heating and the presence of LiPO3 impurities if the heating rate was too slow. Accordingly,a two-step synthesis strategy was adopted to obtain phase pure Li3P5O14. For the first firing, a slowheating rate is required to avoid melting and glass transition ofthe mixture. For the second firing, a higher heating rate is requiredto reduce the content of the impurity of LiPO3. Figure S3 shows the powder XRD patterns for simulatedand experimental data. There is a small amount of impurity of LiPO3 in the powder after performing the second firing at 723 K,but it was possible to obtain phase pure powder of Li3P5O14 by pelleting and sintering at 743 K for 24h. Therefore, all dense pellets for further characterization weresintered at 743 K for 24 h.To obtainphase pure Li4P6O17 was also attempted with the proceduredescribed above to prepare pure bulk powder of Li4P6O17 with varying reaction temperatures (673–773K) and reaction times ; however, Li3P5O14 and LiPO3 always formed as the majorityphases in powder synthesis. Single crystals of Li4P6O17 have been successfully prepared indicatingthat Li4P6O17 is stable experimentally.Failure to synthesize pure bulk powder samples of Li4P6O17 may reflect the kinetics of synthesis and thehigher content of volatile lithium in this phase. As such, all furthercharacterizations therefore only concern Li3P5O14. The PXRD data of the pure powder of Li3P5O14 were used to run Pawley and Rietveldrefinements with the single crystal model as a starting point, asshown in S5. 3P5O14, indicating that the obtained powder is single phaseand lattice parameters agree with those of the single crystal (Tables S1 and S11). The thermal stability ofLi3P5O14 was confirmed by TGA–DTA,which revealed no significant change in mass and no detectable phasetransition in the heating processes over the temperature range 300–873K with a melting point of 799.9(1) K . Li3P5O14 was chemically stablewhen exposed to air for 1 week .Synthesis at the composition Li3P5O14 (S7) revealed particles with flattenedrod-like morphologies and with a trace amount of amorphous material.The presence of elements other than Li, P, and O was ruled out basedon energy dispersive X-ray (EDX) spectroscopy . The SAED pattern measured along the [123] direction  zone axes show good agreement with the single crystalstructure of Li3P5O14, confirmingthat the particles studied correspond to the single crystal structure.SEM images of the as-synthesized Li3P5O14 9b and S7troscopy S8. The S3.33P5O14 and Li4P6O17 can be assessed from first-principles by comparison of thetotal enthalpies of these phases with other compounds reported inthe Li–P–O phase field. There are several approachesto approximate exchange-correlation potential in density-functionaltheory, including the broadly applicable generalized gradient approximation(GGA) in the PBE formulation and strongly correlated and appropriatednorm (SCAN) meta-GGA.98 The elemental phase diagram calculatedwith PBE is in a good agreement with experiment: both structures arethermodynamically stable. In the PBE approximation, the equilibriumreaction energies to form Li3P5O14 and Li4P6O17 phases from the nearestpreviously reported compounds in this phase diagram are negative;hence, Li3P5O14 and Li4P6O17 lower the energy level of thermodynamicstability, redefining the convex hull of the Li–P–Ophase field  underestimates the enthalpy values for Li3P5O14 and Li4P6O17 rendering them as thermodynamically unstable in contrast to experimentalobservations. Hence, for electrochemical stability calculations inthe remainder of this work, we rely on PBE as the approach in betteragreement with experiment in this case.Theoreticalthermodynamical stabilities of the synthesized phases Lise field 10. Additse field 10, inset3.43P5O14 were determined by AC impedance spectroscopy on a Au|Li3P5O14|Au configuration.99 A typical impedance data set at room temperature is shownin –12 F cm–1, correspondingto a permittivity of ∼10 and thus represents the bulk response.A second, poorly resolved plateau at lower frequency with a capacitanceof 10–10 F cm–1 is seen at highertemperatures and is attributed to a conventional grain boundary.99 At the highest temperature, 573 K, C′rises to values around 10–5 F cm–1, characteristic of a blocking double-layer capacitance at the sample–electrodeinterface. Although impedance measurements were not carried out atvery low frequencies  and therefore no spike was observedin the room temperature impedance plot, the low-frequency plateauat 10–5 F cm–1 is a clear evidenceof blocking Li ions and indicates that the sample has ionic conductivity,which was shown more clearly by the higher temperature Nyquist plotat 373 K with the presence of a low-frequency inclined spike, as shownin Figure S11.The bulk and total conductivity of LiR-CPE elements, as shown in S11. In the equivalentcircuit, the Rb and Rgb are resistors used to simulate the bulk and grain boundaryresistance. The CPEb and CPEgb are constant phase elements used to simulate the capacitivebehaviors of Rb and Rgb. Final fitted parameters at 303 K are given in Table S12. The bulk and total conductivitiesat 303 K were estimated to be 8.5(5) × 10–7 and 6.2(4) × 10–7 S cm–1, respectively. These data vary with temperature and are shown inArrhenius conductivity format in S12. Linearbehaviors are observed in the temperature range 303–573 K forboth bulk and total conductivities with activation energies of 0.42(8)and 0.43(7) eV, respectively. In order to characterize the electroniccontribution to the observed conduction, DC polarization measurementswere carried out between room temperature and 573 K on a Au|Li3P5O14|Au configuration. Figure S13 shows the current vs time plots, and 3P5O14. Theelectronic conductivity contributes less than 3% to the bulk conductivityat 303 K and less than 0.5% at 573 K.To extract the bulkresistance values, it was assumed initiallythat the high-frequency arc could be represented ideally by a seriescombination of two parallel 3P5O14 at 303 K is comparableto sputtered LiPON glass thin filmelectrolytes ((1–3) × 10–6 S cm–1 at 298 K),101 which are routinely used inthe production of thin film batteries, and the bulk-type electrolyteLi3.6PO3.4N0.6 (3.0 × 10–7 S cm–1 at 298 K),102 a crystalline polymorph of LiPON SSE with the highest ionicconductivity among all reported crystalline LiPON SSEs. The room temperatureionic conductivity of Li3P5O14 ishigher than that of conventional crystalline metal oxide coatings,such as Li4Ti5O12 (5.8 × 10–8 S cm–1),103 LiTaO3 (2.1 × 10–10 S cm–1),104 LiNbO3 (∼10–26 S cm–1),105 and LiAlO2 (below 10–15 S cm–1),29 and is comparable to some of their amorphous/glassstate, such as LiNbO3 glass (10–5–10–6 S cm–1).106 Compared to LiPON and these metal oxide coatings, Li3P5O14 exhibited significantly improved electrochemicaloxidation stability as discussed below.The bulk ionic conductivityof Li3P5O14 was obtainedthrough solid-state NMR. The temperaturedependence of the static 7Li NMR spectra over the 250–560K temperature range is shown in 7Li ion mobility is in the rigid latticeregime; therefore, the 1/2 ↔ −1/2 central transitionis broadened by the strong 7Li–7Li homonucleardipolar coupling and an NMR line width of ∼4.5 kHz is observed.As the temperature is increased above 385 K, where the onset of motionalnarrowing occurs, the line width decreases due to the increasing motionof the 7Li spins continuously averaging dipolar interactions.Using an expression introduced by Waugh and Fedin,107 relating the onset temperature of motional narrowing (Tonset) with the activation energy of the diffusionprocess, given by 3P5O14. Wenote that this value is only an estimate (hence no error is quoted)given the validity of the Waugh and Fedin expression, which does nottake into account structural complexity109 such as that of Li3P5O14 with multiplelithium sites, the fraction of fast moving Li+ ions,109 and complete numerical simulations of the 7Li NMR line shape. As the temperature is increased even further(>500 K), Li3P5O15 is in the fastmotional regime, resulting in averaging of the dipolar interactionthrough increased mobility, giving rise to narrow spectra with linewidths of ∼750 Hz. The Li+ jump rate, τ–1, is on the order of the 7Li central transitionNMR line width in the rigid lattice regime and quantified at the temperatureof the inflection point, yielding a value of 2.8 × 104 s–1 at 424 K comparable to values obtained forLa3Li3W2O12110 and Li4SiO4.111Insight into the localionic mobility of Li114 the validity of theWaugh and Fedin expression, the measurement uncertainty in the experimentallyreported activation barriers based on AC impedance spectroscopy,115 and the possibility of multiple available pathwaysfor Li+ hopping processes (see BVS data below).The NMR and AC impedance spectroscopyactivation energies are cautiouslycomparable given the largely different approaches used that couldpotentially lead to contrasting values as observed for a range ofdifferent mobile ionic species,3P5O14 as a solid electrolyte for Li plating and stripping,a symmetric Li|Li3P5O14|Li cell wasprepared with a Li3P5O14 layer thicknessof approximately 300 μm and cycled galvanostatically at 298K with a current density of ±2.5 μA·cm–2. A steady test over 100 h with minimal changes in the stripping/platingoverpotentials was observed  and summarized in Table S13.116 Theinterfacial resistivity (two Li3P5O14|Li interfaces) accounts for about 79% and 37% of the total resistivityof the Li|Li3P5O14|Li cells basedon the AC and DC data, respectively. Such a high interfacial resistivitysuggests the formation of a passivation layer between the Li3P5O14 and Li metal, consistent with the theoreticalcomputation of thermodynamic instability to lithium and the observedkinetically stable interface in the plating/stripping experiments.Given the magnitude of ionic conductivity of Li3P5O14 and large interfacial resistivity at room temperature,large overpotentials and ohmic losses are expected to drive plating/strippingprocesses, even at very low current densities. Higher temperatureshave been used to improve Li3P5O14|Li interfacial contact and enhance the bulk ionic conductivity ofthe solid electrolyte. However, preliminary investigations suggestthat the interfacial resistance grows significantly at higher temperatures. Therein,the high temperature may facilitate rapid decomposition reactionsat the interface of Li3P5O14|Li andsuch a passivation layer impedes the Li+ transport.Toevaluate preliminarily the capability of Liobserved 11g. This+ conduction mechanism in Li3P5O14, the crystal structure has beenanalyzed with a BVS map68 that shows a3D isosurface connectivity displaying inter-layer and intra-layermigration pathways. The Li ion transport in the Li polyhedral layerin the ab plane is termed intra-layer migration,while the Li ion transport between two adjacent Li polyhedral layers(c-direction connectivity) is termed inter-layermigration. As shown in 6O1626– chains along with the vacant tetrahedral sites form a possible intra-layerlithium diffusion pathway in the Li polyhedral layer. The intra-layermigration could occur either by a hopping mechanism of Li ions alongthe Li6O1626– chains or byhopping between the two types of Li6O1626– chains, where the local jumps between the two typesof Li6O1626– chains involvedare between V1 and Li2 tetrahedral sites, between V1 and Li5 distortedsquare pyramid sites, between V2 and Li10 tetrahedral sites, and betweenV2 and Li11 tetrahedral sites.To understand the Li12O3612– rings in the P20O5612– layers provide a window that mobile Li ionscan traverse. Based on BVS mapping, the potential local jumps passthrough these 12-membered rings are highlighted in 6O1626– chains involving Li5 square pyramid sites, and Li10, Li11 tetrahedralsites. Similarly, for inter-layer migration with ring II, the localjumps are between type A and B Li6O1626– chains involving V1, Li3, Li8, V2, Li9, and Li12 tetrahedral sites.Those for ring III are between two of type A Li6O1626– chains involving V1, Li3, Li8, Li10, Li11 tetrahedralsites. Those for ring IV are between two of type B Li6O1626– chains involving Li2, Li6, V2, Li9,and Li12 tetrahedral sites. The vacant tetrahedral sites in Li polyhedrallayers and 12-membered rings in ultraphosphate layers increase theprobability of Li ions migrating through intra-layer and inter-layermigration pathways, which are most likely responsible for the higherion conductivity than those of other ternary lithium phosphates andconventional coating materials. The structural features of Li3P5O14 are consistent with the criteriaof crystal structures identified as enabling lithium-ion conductionusing topological analysis and ab initio molecular dynamics simulations.117BVS maps in 3PO4, five polymorphsof the pyrophosphate Li4P2O7, andthree polymorphs of the polyphosphate LiPO3. As summarizedin Table S10, apart from a polymorph ofLi3PO4 with a face-centered cubic structure(c-Li3PO4), all other reportedphases in this system have very limited ionic conductivity at roomtemperature (∼10–20–10–11 S cm–1). c-Li3PO4, prepared by heat treatment in a flowing humid hydrogen atmosphere,has a relatively high total conductivity (6.9 × 10–8 S cm–1 at 303 K) compared with those other ternariesin the Li–P–O phase field. It should be noted that c-Li3PO4 is also a solid protonicconductor with total ion and proton conductivity at 873 K of 2.4 ×10–2 and 6 × 10–3 S cm–1, respectively.118 Accordingto the literature, due to difficulties in accurately measuring protonicconductivities at low temperatures for c-Li3PO4, the activation energy for the proton conductivity(0.21 eV) is unreliable. Therefore, there is no available room temperaturevalue for the Li ion conductivity of c-Li3PO4. The room temperature ionic conductivities and activationenergy of Li3P5O14 and some knownlithium phosphates in the Li–P–O phase field are highlightedin 3P5O14 has the lowest ratio of Li/P among all ternaryphases in the Li–P–O field. However, Li3P5O14 has the highest ionic conductivity and is atleast 1 order of magnitude higher than c-Li3PO4 and 4 orders of magnitude higher than other materials(Table S10), which can be attributed toits unique 3D lithium migration pathways.It is instructive to compare the ionicconductivity and activationenergy to other ternary oxides in the Li–P–O phase field,where there are 11 reported crystalline phases. There are three polymorphsof lithium orthophosphate Li3P5O14, which is predicted to be stable up to 4.8 V, whichis higher than other solid electrolytes, including the other lithiumphosphates and the LiPON thin-film electrolytes, and than conventionalcoatings materials such as Li4Ti5O12, Li2ZrO3, LiTaO3, LiNbO3, LiAlO2, and Li2SiO3.72 However, the stability againstreduction by the Li metal is relatively poor  compared with other lithium phosphates.It should be noted that the theoretical computation provides an estimationof the worst-case scenario of the stability limit of solid electrolytes,as the reactions with the cathode and anode are often kineticallylimited.71The electrochemical stability window of the two new ultraphosphateswas calculated with an approach analogous to the Li-grand canonicalphase diagram and compared with several representative Li–P–Omaterials. Interestingly both phases appear to have a relatively highthermodynamic stability against oxidation 13b, in p3P5O14 > Li4P6O17 > LiPO3 > Li4P2O7 > Li3PO4. For Li3P5O14, where theP20O5612– anionic layers havethe highest degree of condensation, the thermodynamic stability againstoxidation is highest while the stability against reduction is poorest.Li4P6O17 has the second highest degreeof anionic condensation; hence, the stability against oxidation issecond only to Li3P5O14 and the stabilityagainst reduction is only higher than that of Li3P5O14. Lithium orthophosphate Li3PO4 has the lowest degree of anionic condensation, with isolatedPO43– tetrahedra, and thus the pooreststability against oxidation and the highest stability against reduction.For lithium phosphates,the thermodynamic stability against oxidationincreases as the degree of phosphate condensation increases, whilethe stability against reduction decreases. The degree of phosphatecondensation decreases in the order Li3PO4 abovethe 3.9 V stability limit is 4Li3PO4 →4Li + 2Li4P2O7 + O2, indicatingthat the reaction is aided by the presence of a product with a higherdegree of phosphate condensation than the reactant. For the Li3P5O14 ultraphosphate with the highestdegree of anionic condensation among known lithium phosphates, thecomputed reaction is 4Li3P5O14 →12Li + 10P2O5 + 3O2 and requiresa greater driving force due to the absence of a stable ternary productwith a higher degree of phosphate condensation. Moreover, as notedby Ceder et al. the phosphate condensation decreases the P/O ratioand enhances the hybridization of each O with P, thereby increasingthe oxidation stability in the sequence orthophosphate, pyrophosphate,and polyphosphate.119 The ultraphosphates extend thissequence. It has been proposed though that there is a trade-off betweenhigh ionic conductivity and high electrochemical stability to oxidation,as generally good ionic conductivity requires high Li content forpolyanionic oxides, which was observed to be negatively correlatedto oxidation stability.120 In comparison withother reported ternaries in the Li–P–O phase field,Li3P5O14 achieves both improved Li-ionmobility and a higher thermodynamic stability to oxidation with alower Li content.This regular progression can be explained by comparing the possibleanodic and cathodic reactions in these different lithium phosphates.The computed anodic reaction of Li3PO4 atits stability limits is 8Li + Li3PO4 →4Li2O + Li3P. Li3PO4 hasthe lowest degree of phosphate condensation and thus decomposes intothese two binary phases. The other phosphates can all decompose intoanother lithium phosphate with a lower level of condensation. Forexample, Li3P5O14 decomposes at voltagesbelow 3.24 V in the reaction 17Li3P5O14 + 5Li → 14Li4P6O17 + P.It would be expected that the reaction at reducing potentials wouldproceed sequentially through the products Li4P6O17 (3.2 V), LiPO3 (3.0 V), Li4P2O7 (2.5 V), and Li3PO4 (2.3V) until finally below 0.7 V affording Li2O and Li3P (essentially tracking the bottom of the bars in 3P5O14 and Li metal. In all cases, kinetic stability of interfacesthat are thermodynamically unstable is possible.The computed cathodic reaction of Li43P5O14 and Li4P6O17 introduce a distinct fundamental structure-buildingmotif, the branching phosphate tetrahedron that shares three oxygenswith other tetrahedra. This generates ultraphosphate anions with extendedstructural motifs distinct from those in previously reported Li phosphates,because of the different combinations of tetrahedral connectivitythat arise when the branching tetrahedra are included. The combinationof 2- and 3-connectivity in the infinite P20O5612– anion in Li3P5O14 creates 12-membered rings that generate three-dimensional transportpathways affording higher Li conductivity than other lithium phosphates,and comparable to that of materials used as thin film electrolytes,despite the higher condensation of the network and reduced Li contentin the new materials. The higher phosphate condensation introducedby the branching phosphates in the new structures reported here combinesthis higher conductivity with higher intrinsic stability to electrochemicaloxidation than previous phosphates, and indeed all other solid electrolytesevaluated computationally. With a conductivity matching that requiredfor cathode coatings, and a kinetically stable interface to lithiumat room temperature, Li3P5O14 illustratesthe opportunities offered by new structural motifs for enhanced Litransport in phosphates, which benefit from inexpensive componentsand ease of handling. The control of defect chemistry through substitutioninto these new ultraphosphate structures requires investigation tooptimize the identified transport and stability properties.Reported lithium phosphates are based on isolated,terminal, orinternal phosphate tetrahedra that share zero, one, or two of theiroxygens to form extended structural units. The lithium ultraphosphatesLi


Comparable outcomes were published using a buccal mucosa graft (BMG) from the cheek and a lingual mucosa graft (LMG) from the sublingual area, for urethral augmentation or substitution. To date, no histological comparison between both grafts has been conducted. We histologically assessed BMG and LMG harvested during urethral surgeries, aiming to compare graft properties and vascular support. We conducted a prospective single cohort study, including oral mucosa urethroplasty patients. During surgery, graft dimensions and donor sites were collected, and a 0.5 × 0.5 cm sample was obtained from the prepared graft. Formalin-fixed paraffin-embedded samples were sliced at 4 micrometres (µm) and hematoxylin-eosin stained. Using a telepathology tool, all slides were digitalized and measured from 10× to 40× magnification. In each graft, global and individual layers thicknesses were assessed, including vascular density and area. Descriptive and comparative  statistical analysis occurred. We collected 57 grafts during 33 urethroplasties, with 30 BMG and 22 LMG, finally, included. The mean age was 56.6 (SD 15.2) years, and the mean graft length was 5.8 (SD 1.7) cm and the width was 1.7 (SD 0.4) cm. The median graft thickness was 1598.9 (IQR 1200–2100) µm, the mean epithelium layer was 510.2 (SD 223.7) µm, the median submucosa was 654 (IQR 378–943) µm. the median muscular was 477.6 (IQR 286–772) µm, the median vascular area was 5% (IQR 5–10), and the median adipose tissue area was 5% (IQR 0–20). LMG were significantly longer and narrower than BMG. Total graft thickness was similar between LMG and BMG, but the epithelium and submucosa layers were significantly thinner in LMG. The muscular layer was significantly thicker in LMG. Vascular density and vascular areas were not significantly different between both types of grafts. LMG showed significantly less adipose tissue compared with BMG. Our findings show LMG and BMG for urethroplasty surgeries share the same thickness and blood supply, despite having significantly different graft sizes as well as mucosal and submucosal layers thickness. Urethral reconstruction still poses a challenge for urologists. A wide variety of techniques are described, when urethral substitution or augmentation is required. Aside from local flaps, many tissues have been proposed for use as grafts: preputial or penile skin, non-hair bearing extra-genital skin, bladder mucosa, colonic mucosa, or oral mucosa. Recently, some consensus was reached, and according to EAU and AUA Guidelines, oral mucosa should be the tissue of choice when urethral grafting is advised ,2. This A buccal mucosa graft (BMG) from the inner cheek was first proposed  and is sSeveral studies have been published describing urethroplasty results and complications from oral mucosa harvesting. However, no histological comparison between both grafts has been conducted to date. In the present study, we histologically assessed BMG and LMG harvested during urethral surgeries, aiming to compare graft tissue properties and vascular supply.A prospective single cohort study was designed. The research protocol was reviewed and approved by local Ethical Committee, and all included patients signed the specific informed consent form. The main objective was to compare the histological characteristics of grafts from the ventrolateral aspect of the tongue with those from the inner cheek, when prepared for their use in augmentation or substitution urethroplasties. Secondary objectives were assessing our consistency on graft preparation—keeping a comparable thickness, with uniform histological characteristics in each type of donor site—and comparing residual muscle fibers after preparation, as well as vascular density in both grafts.We invited patients older than 18 years old, diagnosed with urethral disease, who were candidates for an augmentation or substitution urethroplasty. Exclusion criteria were patients with exclusive anastomotic urethral repair or augmentation using only local flaps, and when tissues other than oral mucosa were used for the urethral repair. Grafts previously harvested from a donor site were also not considered for analysis.All patients were preoperatively evaluated by history, physical examination, uroflowmetry, post-void residual urine measurement, retrograde urethrography, and/or urethroscopy. Patients with active oral disease were submitted to a specialized evaluation by an oral and maxillofacial surgeon for clearance, before inclusion in the study.Patients are explained both BMG and LMG, including specific postoperative side effects. Final decision on graft harvesting remains at the discretion of the surgeon, depending on intraoperative findings—final length of stricture, aspect of urethral plate—and considering previous oral harvesting sites. As a standard criterion, BMG are selected for wide defects, usually with a total length of 6 cm or less. For longer defects , LMG are generally preferred. Urethroplasty procedures and graft harvesting were performed by three separate consultant urologic surgeons with more than five years of experience in urethral reconstruction.A silicone jaw opener is placed at the contralateral side to the donor cheek, and 5-0 stay sutures are placed at the lip border for exposure. The Stensen duct must be identified, marked, and carefully preserved. A distance of at least 1 cm from the lip is kept, to minimize mouth-opening problems. The required graft is marked with a surgical pen. Submucosal injection of local anesthetic with epinephrine is routinely performed, to facilitate graft dissection and decrease bleeding. After a cold knife incision on the previously marked lines, the graft harvest is completed using sharp scissors. Bipolar energy is used for hemostasis, and the donor site is closed using absorbable 5-0 interrupted sutures.A plastic lip opener is placed for better exposure, and the apex of the tongue is pulled outside the mouth using a ring forceps or Babcock forceps. Donor site limits are the fimbriated fold medially, the lateral line of the tongue dorsally, and palatoglossal fold proximally. Separate grafts are obtained if bilateral LMG are required, preserving the distal tip of the tongue along with tongue frenulum. The graft is measured and marked, and submucosal local anesthetic with epinephrine is injected. Lateral edges are incised with a scalpel, and graft harvesting is completed using sharp scissors. Donor site is checked for hemostasis and closed using an absorbable 5-0 running suture.After harvesting, grafts are spread and prepared, removing muscular fibers and adipose tissue until they have a whitish appearance . When re2), vascular area (% of the area of lamina propria occupied by vessels); and adipose tissue area (%)—Using an optic microscope under 10× to 40× magnification, the issues were evaluated. Moreover, a telepathology accessory tool  was used for capture images. The following variables were measured using specific histology analysis software : total graft thickness (µm); epithelium (µm), submucosa (µm) and muscular (µm) layers thickness; vascular density  and graft characteristics  were recorded for each graft during urethroplasty procedure, and recorded in the operation notes. Data were prospectively collected and securely stored in an Access database.p < 0.05. Statistical analysis was performed using STATA 13.1 software for Mac .Variability of grafts characteristics was assessed using the Kolmogorov–Smirnoff test. A Student’s t-test for independent samples was used to compare normally distributed variables, while a Mann–Whitney (Wilcoxon Rank-Sum) test was used for non-parametric comparisons. Significant difference was considered when Between February 2019 and August 2021, a total of 57 grafts (23 LMG and 34 BMG) were harvested during 33 urethroplasties. Median patient age was 56 (IQR 44.1–66.8) years. A median of two  grafts were obtained per procedure. During laboratory procedures, five samples (8.8%) were lost. In total, 30 BMG and 22 LMG were, finally, included in histological analysis.Global characteristics of analyzed samples are described in Six samples (11.5%) did not contain any muscle fibers—five BMG and one LMG. Sixteen samples (30.8%) did not contain any adipose tissue. Minimal inflammatory infiltrate of the submucosal tissue was identified in 14 samples (24.6% of samples). Only two samples, both from the same patient, presented important inflammatory changes-undetected during urethroplasty procedure. This patient had an uneventful postoperative course, and the reconstructive procedure was successful throughout more than one year of follow-up. Human papillomavirus (HPV) was isolated in two cases by PCR techniques. No oral nor urethral macroscopic HPV-related lesions have been encountered in these patients to date.The main histological differences between grafts are summarized in Oral mucosa is nowadays accepted as the tissue of choice for urethral augmentation or substitution . AlthougAlthough BMG are easily harvested, these second surgical sites could lead to short- and long-term complications—such as oral tightness and numbness—especially if longer or wider grafts are obtained. Aiming to reduce donor site morbidity, while exploiting another source of oral tissue, LMG was proposed  and has Comparative studies of BMG and LMG urethroplasties showed similar outcomes in terms of urethral patency, with reported success rates of 76%–86% and 75%–89% for BMG and LMG urethroplasties, respectively ,29,30,31Several authors have investigated the characteristics and properties of oral mucosa, related to its suitability for urethral augmentation. Oral mucosa has a thick non-keratinized stratified squamous avascular epithelium and a well-vascularised lamina propria. Vessels infiltrate lamina propria through the submucosal layer, providing an effective mechanism for revascularization of the tissue when grafted. Histological architecture shows some similarities with urethral mucosa (stratified squamous epithelium) . MoreoveWhen compared with other tissue sources for urethral reconstruction, such as penile skin and bladder mucosa, oral mucosa has a much thicker epithelium with thinner lamina propria . This woMokhless et al.  conducteTo date, only one study assessed LMG histology. Song et al. performed a sublingual graft urethroplasty in 10 dogs . After tFor a taken graft, not only the native properties of transferred tissue are important, but also how the graft is prepared before fixation to the urethral bed. The sole study to date addressing oral grafts preparation for urethroplasty was published by Cavalcanti et al. . They evIn our study, the previously described whitish appearance was an aim during graft preparation before transferring. However, in comparison, our BMG group showed a similar epithelium layer, but a slightly thinner subepithelial layer and overall thickness, probably in relation to a greater degree of graft trimming .The fact that BMG contains more vascular tissue—without significant differences—may represent an advantage for graft survival, but on the other hand, a thinner submucosal layer of LMG may present an advantage for graft survival .Other factors than preparation have been reported to influence graft thickness. According to Vandana et al. , epithelBefore recommending oral grafting, a thorough head and neck examination is advised, to avoid transferring diseased tissues to the recipient site. In patients with specific clinical conditions, such as leukaemia, mucositis associated with head and neck cancer therapy, oral lichen planus, pemphigus vulgaris, recurrent aphthous stomatitis, and leukoedema, the oral graft harvest is strictly contraindicated . EthanolRecently, the importance of oral cavity evaluation, particularly if risk factors for dysplasia or malignancy are present, was highlighted by Massimo et al. , publishOur study presents some limitations that should be acknowledged. Final grafts number was affected by initial handling problems, with up to 9% of samples being unsuitable for histological assessment. Choice and size of LMG and BMG are affected by surgeon preference in each urethral case, which could influence the results of our series. As strengths, we should mention the double uropathologist measurement of histological characteristics in each sample, minimizing bias. Finally, we are presenting pure histological analysis of LMG for urethral grafting—to the best of our knowledge, for the first time in the literature—but our study lacks clinical correlation. All of our patients are being prospectively followed, and we expect to compare urethroplasty outcomes, relating them with graft type and characteristic in due time.LMG are usually longer and narrower than BMG when harvested during urethral surgeries. Both oral grafts share global thickness and vascular density and area. However, LMG present thinner epithelium and submucosa, and a lower percentage of adipose tissue compared to BMG. Conversely, LMG show thicker muscular layer than BMG. Further studies with long-term follow-up are required to understand if histological differences are relevant for urethroplasty outcomes.