This non-volatile WSe2 pn homojunction is demonstrated with optical and scanning probe methods and scanning photoelectron micro-spectroscopy. A homo-interface is a direct manifestation of our WSe2 pn diode, which can be quantitatively understood as a clear rectifying behavior. The non-volatile confinement of carriers and associated gate-free pn homojunction can be an addition to the 2D electron–photon toolbox and pave the way to develop laterally 2D electronics and photonics.Interest in bringing p- and n-type monolayer semiconducting transition metal dichalcogenides (TMD) into contact to form rectifying pn diode has thrived since it is crucial to control the electrical properties in two-dimensional (2D) electronic and optoelectronic devices. Usually this involves vertically stacking different TMDs with pn heterojunction or, laterally manipulating carrier density by gate biasing. Here, by utilizing a locally reversed ferroelectric polarization, we laterally manipulate the carrier density and created a WSe 2 pn homojunction on a supporting ferroelectric BiFeO3 substrate.Bringing together p- and n-type monolayers of semiconducting transition metal dichalcogenides results in the formation of atomically thin pn junctions. Here, the authors laterally manipulate carrier density to create a WSe Despite these fantastic discoveries, the present challenge is to promise a TMD pn diode, which is a fundamental building block of modern devices, that manifests all their numerous advantages  while also easily overcoming the scaling limit of current complementary metal-oxide semiconductor (CMOS) technology or achieving atomically thin optoelectronics. The methods used to achieve p- and n-doping in TMD are mainly inducing charge transfer to TMD, such as gate-bias tuning13, interacting with atoms/molecules17, molecular adsorption on a surface19, and plasmonic hot-electron doping21. The method most commonly used to dope TMD is to set a gate voltage through the metal gating, which provides a direct way to realize the strong charge-density tuning, but metal gates would result in an inhomogeneous charge distribution and unavoidable degradation of the emission of light at the TMD surface. TMD diodes have been constructed by stacking vertically, such as an ionic liquid-gated bulk MoS2 device22, a TMD/III–V semiconductor23 and a TMD/doped-silicon24. TMD heterojunctions vertically involving other materials, however, apparently lack many appealing exotic properties of a lateral monolayer.Devices that require low power consumption, materials that have a monolayer structure with quantum confinement, electrons and holes that convey information with high mobility—these are just some breakthroughs that might be realized following the development of two-dimensional (2D) materials that are efficient, scalable, and easily engineered to achieve diverse functionality. Since the discovery of various 2D materials almost a decade ago, the recent boost of interest in semiconducting layered transition metal dichalcogenides (TMD) originates from their exotic characteristics in the monolayer limit, such as giant spin-valley coupling2 electron-filling (n-type) and electron-emptying (p-type) regions configured and modified with the FE domains of a BiFeO3 (BFO) substrate, and thus define a monolayer WSe2 pn homojunction  without assistance of gate biasing. This diode shows a strong current-rectifying behavior in electrical transport properties, which confirms the results revealed in the homojunction band structure. This work provides a non-volatile control of TMD doping and a promising way to produce a pn homojunction as a future building block of 2D device applications.Because of the ultra-thin nature of a TMD, a necessary substrate provided by a functional material can offer a strategy for lateral modulation of the TMD band structure without problems caused by the doping defects and the mismatches between the dopants and 2D lattice atoms. Ferroelectric (FE) materials possess a spontaneous electrical polarization that can be macroscopically and locally inverted with an external stimulus, and are considered to be prospective substrates to support TMD to achieve a pn homojunction, as the accumulation or depletion of an inevitably charged mobile carrier occurs in the TMD to screen the polarization field of the FE substrate. Here, using detailed spatially resolved spectroscopies, we have demonstrated the respective WSe3 (STO) substrates with a conductive SrRuO3 (SRO) layer (Methods section). Using chemical-vapor deposition (CVD) and a wet transfer method, we affixed monolayer crystalline WSe2 sheets firmly to the BFO surface, forming a van der Waals (vdW) interface that played a key role in the formation of a WSe2 homojunction. The scanning-probe characterizations and images of a representative WSe2 on ferroelectrically patterned BFO are displayed in Fig. 2 was a monolayer (~1.5 nm) measured by tapping-mode atomic force microscope (AFM) and confirmed by photoluminescence (PL). The monolayer thickness of WSe2 measured here was larger than the mechanically exfoliated monolayer WSe2 (dWSe2 ~ 0.7 nm)19 and the CVD-grown monolayer WSe2 (dWSe2 ~ 1.1 nm)26 since the water molecules were easily trapped on the hydrophilic BiFeO3 surface to increase the distance between WSe2 and BiFeO3 substrate28 and thus increase the thickness measured by AFM. The ferroelectric properties of the BFO layer were verified through characterization with polarization versus voltage (P–V) and a piezo-force microscope (PFM) in Supplementary Figure P–V loops show that the BFO films used in this work having naturally downward polarization (Pdown) undergo sharp FE switching during poling, with a remnant polarization ≈60 μC cm−2  to obtain an area of upward polarization (Pup) that is partially covered with WSe2; the overlap area is about 7 μm2. In the PFM image shown in Fig. Pup and Pdown regions are revealed under a WSe2 sheet with opposite out-of-plane phases; the shape of the WSe2 sheet is consistent with that measured from an AFM image, implying that the WSe2 sheet is not structurally damaged during the reversal of polarization.The crystalline ferroelectric BFO layers were grown with pulsed-laser deposition (PLD) on 001) SrTiO SrTiO3  showed that the surface potential of WSe2 decreases about 450 meV because of the induced charge screening in WSe2 within the Pup area, compared within a Pdown area as shown in Fig. 2 (~0.45 eV) created with ferroelectric Pup and Pdown regions of BFO is significantly larger than with an epitaxial growth of monolayer WSe2-MoS2 lateral junction30, which shows that the ferroelectricity of the supporting substrate has the ability to affect the electrical properties of TMD material efficiently and strongly. Moreover, the monolayer WSe2 has a direct band gap that offers a large quantum yield of radiative exciton recombination, leading to efficient PL emission. These photo-excited electrons and holes can form either excitons (e–h pairs) or electron-/hole-bounded trions (e–e–h/e–h–h) even near 300 K, and, accordingly, can be used to monitor the carrier type (doping type) and density in a TMD having direct bandgap emission31. The spatially resolved PL spectra recorded from the same area  to the reversed Pup state (~1.60 eV). This is consistent with the fact that the emission switched to decreased energy and quantum yield from a hole-bounded trion recombination to an electron-bounded trion recombination in the initially p-type WSe2 and then becoming electron-accumulated WSe2 under the Pup state of the BFO substrate, which is in agreement with previous reports on the PL characteristics of monolayer TMD under electrostatic gating32. Moreover, we recorded PL spectra in a series at the same spot on the sheet under another FE switching cycle, which confirmed that the attenuation of the PL emission is not from destruction due to biased tip scanning during FE poling, as shown in Supplementary Figure To reveal the substrate-induced charge traps in WSe2 on a BFO, we used a scanning photoelectron microscope and spectroscopy , Hsinchu, Taiwan) to provide the required spatial resolution (~sub-μm) for chemical mapping and the energy resolution (± 50 meV) for localized photoelectron spectroscopy (μ-PES) with a beam of synchrotron radiation (SR) focused on the Pup and Pdown regions larger than the size of the focused SR beam. Figure d, W 4f, and Bi 4f core-level photoelectron spectra, which correspond to the SPEM images taken from a WSe2 sheet at the Pup and Pdown regions, respectively. The binding energy (BE) of the core-level electron in Se 3d and W 4f of the Pup region was significantly greater than in Pdown, but was not observed in Bi 4f. For the band structure of the Pdown region sketched in Fig. Pdown BFO layer hence preserved the p-type behavior, because p-type doped BFO thin film has a work function value near that of WSe234. The detailed band structures deduction of WSe2 at Pup and Pdown are shown in Supplementary Figures d and W 4f have a BE shift ~1.0 eV in the Pup region. This energy shift is observed also in a SPEM image, which reveals a contrast reversal in the W 4f images. The energy difference of the core level corresponds to the Fermi-level energy shift in the band gap, which turned the p-type into n-type WSe2, as shown in Fig. EF) within the gap that is significantly larger than the previously reported number for Nb-doped MoSe2 and NOx-doped WSe216 implies that it is possible to tune the EF position near the TMD band edge with heavily doping according to this approach. Here, this ferroelectricity-assisted band structure engineering results a WSe2 pn homojunction at room temperature.To directly visualize the ferroelectric tuning in the electronic structure of WSe2 carrier density, the PES spectra of WSe2 under Pup and Pdown BFO states are required to reveal the respective EF energies relative to their valence (EV) and conduction (EC) band edges. Under a parabolic approximation for the band dispersion near the bottom of conduction band (CB) and the top of valence band (VB) modeled in the effective mass of mobile carrier with Fermi–Dirac statistics, the 2D electron density (σn) in WSe2 is given by σn = (g2DkBT) ln{1 + exp[(EF–EC)/kBT]} and the 2D hole density (σp) in WSe2 is σp = (g2DkBT) ln{1 + exp[−(EF−EV)/kBT]}, in which g2D is the electron/hole density of state for WSe2. As shown in Fig. EF–EV of WSe2 is about 0.4 eV in the Pdown state and EC–EF of WSe2 is about 0.2 eV in the Pup state, which are determined by the spectra shown in the Supplementary Note 2 regions are estimated of σp ~ 8.63 × 109 cm−2 and σn ~ 1.48 × 1013 cm−2, respectively, and the detailed calculation is provided in the Supplementary Note 10 cm−2) based on the intrinsic carrier density (σi ~ 1.26 × 103 cm−2) of WSe2, the mobile hole accumulation in WSe2 is slightly inhibited (~107 cm−2) when the polarization in BFO layer is naturally Pdown, which is in agreement with the results of the defect charge screening of naturally polarization field (Pdown) in BFO proposed in previous results27. Due to the large polarization field provided by a ferroelectric BFO substrate, the large improvement of the mobile electron density (~1013 cm−2) in TMD system observed in this study agrees satisfactorily with the order of surface bound charges of the BFO layer (~1014 cm−2) and is higher than other TMD junction systems that was reported for elemental doping MoSe2 (σn ~ 1011 cm−2) and lateral heterojunction WSe2/MoS2 systems (σn ~ 1010 cm−2)30. Moreover, the tunability of mobile charge density in 2D TMD system can be probably achieved in precisely manipulating the polarization field in supporting polycrystalline ferroelectric layer through setting different poling voltage, for example, the polarization in polycrystalline BFO can be changed from 5 to 70 μC cm−2 thus would modulate the charge density as large as one order of magnitude36.To determine the ferroelectricity-induced manipulation of WSe2 carrier densities on a BFO substrate; a question arises whether one can reveal the rectification of a WSe2 pn homojunction on reversed BFO domains. The fabrication of the WSe2 pn diode (Diode-T) made use of the CVD growth of crystals of WSe2, with a monolayered and triangle sheet (area ~100 μm2) transferred onto a 30-nm-thick BFO substrate and then employed with the same ferroelectric switching in the AFM setup. Figure 2 sheet became ferroelectrically doped into p-type  and n-type  conducting regimes to form a WSe2 pn homojunction. All transport measurements were performed near 300 K and in vacuum, wherein the voltage bias VSD is applied and the direct current ISD is measured between source (S) and drain (D) contacts. Here, we choose to use Pd metal to form low-resistance ohmic contacts with WSe2 because of its high work function19. It is worth noting that the Pd electrode is also found to conduct current into the BFO substrate when patterned upon it. Two conducting tungsten tips controlled by the nanomanipulator installed in SEM are utilized to conduct the electrical measurements. To prevent inevitable BFO substrate effect, the Pd metal electrodes are being cut off connections with BFO substrate using focused-ion-beam etching, which turning into isolated pad on the source and drain points  of the diode. W is the Lambert W function. At the forward-bias voltages, the ISD–VSD curve of our WSe2 pn diode with a homo-interface is well modeled by the diode equation with n ~ 8.4, series resistance Rs ~ 8.1 MΩ. This ideality factor n is quite low compared with what have been observed for the CVD-grown TMD diodes, normally n > 1040, however, it is still higher than the n value obtained in certain TMD diodes made by exfoliated natural crystal with high-quality42. Furthermore, no obvious reverse-saturation current is observed, indicating that current transmission through the whole WSe2/BFO device is not limiting in the diode and suggesting that the BFO layer acts not as a good insulating layer to prevent current leakage as shown in Supplementary Figure where 2, we made another WSe2 diode (Diode-H) consisting of a transferred CVD-grown WSe2 monolayer flake having hexagram shape and large area (~700 μm2) on a thicker BFO layer (thickness ~ 60 nm) with opposite polarization states  is extracted from diode equation fitting and can be observed at high reversed bias (0 ~ −5 V), confirming that the thick BFO layer indeed inhibits current leakage. The higher n (~12.3) value and larger series resistance Rs (~7.8 GΩ) based on the fitting result with the turn-on point in the ISD–VSD plots showing at large forward bias is attributed to a high series resistance consistently associated with the poor conductive quality of a hexagram shaped WSe2 layer46. Moreover, on this large WSe2 diode, it is easy to make both Pd electrodes on WSe2 in Pdown states (pp junction) and in Pup states (nn junction). Since Pd is a high work function metal47, which means its Fermi-level will align valence band edge of WSe2 for efficient hole injection, therefore, the pp junction shows a nearly ohmic ISD–VSD relation at low VSD. The ISD–VSD relation in the nn junction shows non-linear due to the Schottky barrier formed at the n-type WSe2/Pd interface, in which shown in Supplementary Figure 2 should significantly improve the performance of this ferroelectricity-assisted WSe2 pn diode.To explore issues of current rectifying associated with the supporting BFO layer quality and to better understand the nature of current transmission through Pd metal contacts and WSe2 diode using a lateral pn homojunction without a biased electrode gate. Employing a monolayer WSe2/BFO structure, we demonstrated non-volatile control of the band structure, surface potential, and light emission of monolayer WSe2 with opposite polarization domains on a BFO substrate. With the quantitative analysis and modeling of current rectifying, as device quality improves, our gate-free 2D diode promises a comparable capability of current rectification with that of a conventional bias-gating-type 2D device. This evidence emphasizes the possibility of non-volatile control and provides an alternative functionality in ferroelectric doping of 2D materials, thus opening a wide vista of TMD-based quantum electronics and photonics.To summarize, we designed and implemented a ferroelectrically controlled WSe2) sample was prepared with CVD. On evaporation of WO3 at a high temperature, the WO3 powders were filled in a home-made quartz reactor with a transfer tube of tunable length to enable a stable flow of WOx3− vapor that served as a reactant evaporated from a high-temperature zone to react with Se on a substrate surface. In the low-temperature zone, an individual WSe2 monolayer was synthesized in a temperature range 650–750 °C. Monolayer WSe2 typically formed a triangular shape in a monolayer thickness to transfer onto the BFO ferroelectric layer.A tungsten diselenide (WSeλ = 248 nm); the laser beam was focused on a BiFeOx ceramic target with energy density ~2.5 J cm−2 and repetition rate 10 Hz. The samples were deposited at substrate temperature 700 °C under oxygen at pressure 100 mTorr. The samples were cooled to near 300 K under oxygen at pressure 1 atm after deposition of the thin film. The ferroelectric epitaxial BFO/SRO/STO(001) film possessed out-of-plane downward polarization; the domain structures as grown were confirmed with a PFM.An epitaxial thin film (30 nm and 60 nm) of BFO was fabricated on the SRO-buffered STO (001) single-crystalline substrate via pulsed-laser deposition  were used at the SPEM end station located at beamline 09 A1 of Taiwan Light Source in NSRRC. The soft X-ray beam focused by the Fresnel zone plate and the order-sorting aperture at the focal plane was about 100–200 nm in diameter. All measurements were undertaken near 300 K. The energy resolution was estimated to be better than 100 meV. Based on the SPEM images, the focused beam was movable to a specific location to record high-resolution PES of a microscopic area.The data that support the findings of this study are available from the corresponding authors upon reasonable request.Supplementary InformationPeer Review File


Total parathyroidectomy (tPTX) in patients with renal hyperparathyroidism (RHPT) aims at the complete removal of all hyperfunctioning parathyroid tissue. Whenever parathyroidectomy is termed “total,” undetectable postoperative parathyroid hormone (PTH) levels within the first postoperative week are expected. The aim of this study was to evaluate if tPTX is technically possible using a radical surgical procedure.n = 50; after kidney grafting n = 59), removal of all visible parathyroid tissue, bilateral thymectomy, bilateral central neck dissection (level VI), and immediate autotransplantation (AT) was performed. Intact PTH (iPTH) levels were measured in the first postoperative week. PTX was classified “total” when iPTH dropped below 10 pg/ml, “subtotal” between 10 and 65 pg/ml, and “insufficient” where levels stayed above 65 pg/ml.In 109 consecutive patients with RHPT . PTX was “subtotal” in 25 patients (22.9%), 19 on hemodialysis, 2 had normal, and 4 had restricted kidney graft function. PTX turned out to be insufficient in four patients (3.7%); all of them were on hemodialysis. Insufficient PTX was not observed in kidney-grafted patients. Postoperative temporary laryngeal nerve morbidity was 1.8% (no permanent paresis).According to the postoperative PTH value, tPTX was achieved in 80 of 109 (73.4%) patients (hemodialysis Although applying a very radical concept in patients with RHPT, PTX was “total” in only 73.4%. Persistence of disease was avoided in 91.7%, and low morbidity was documented. In conclusion, it seems difficult to remove all parathyroid tissue from the neck which has to be considered when choosing the surgical procedure. The current treatment of RHPT is mainly medically using oral calcimimetic drugs which influence PTH, calcium, and phosphorus metabolism. However, some patients develop resistance to cinacalcet or develop high PTH values after initial sufficient medical suppression, or suffer from side effects of cinacalcet treatment. Current guidelines define indications for surgery in these patients –3.Different surgical procedures are described in the literature. Besides subtotal 3 1/2) parathyroidectomy, total parathyroidectomy  with immediate autotransplantation (AT) is a widely performed treatment of renal hyperparathyroidism (RHPT)  1/2 para.After total PTX and immediate AT, the persistence and recurrence of RHPT are 4.4% and 9.3%, respectively, even in the era of calcimimetic drugs . The cauEven after total PTX without AT, persistence and recurrence of disease is documented in up to 80% –14. The By definition, intact parathyroid hormone (iPTH) is expected to be non-measureable following “complete” total PTX. The aim of this retrospective study was to evaluate if “total PTX” can be achieved applying an adequately extended surgical protocol with removal of at least four parathyroid glands, transcervical thymectomy, and resection of the lymphatic tissue along both recurrent laryngeal nerves  or, contrariwise, even with such an aggressive procedure, “total PTX” cannot be reached in all patients.All patients with RHPT receiving total PTX + AT in our institution during a 7-year period between 1996 and 2003 were analyzed. Surgery was carried out by a team of five dedicated endocrine surgeons. Exclusion criteria were inappropriate follow-up or early kidney grafting (within 6 months after PTX).All patients gave informed consent to all diagnostic and therapeutic procedures. A preoperative MIBI scan was performed to detect ectopic supernumerary parathyroid glands. Phoniatric evaluation including laryngoscopy was performed pre- and postoperatively.All patients underwent bilateral neck exploration with identification and removal of all (at least four) visible parathyroid glands. Surgical routine included bilateral transcervical thymectomy and bilateral central neck (= level VI) microdissection with extirpation of all fatty/lymphatic tissue behind the thyroid, along the esophagus and along both recurrent laryngeal nerves . A meticulous dissection of both recurrent laryngeal nerves was performed using magnifying glasses to avoid a permanent damage of the nerves. After selection of viable tissue , 20 fragThe surgical protocol was introduced in 1993 and, to assure long-term follow-up, patients of the first 10 years were reviewed. Patients operated before 1996 were not included due to inconsistent data. The data was analyzed retrospectively.According to their kidney function at the time of surgery, patients were divided into three groups: Group A were on hemodialysis. Patients with persisting RHPT after kidney grafting were assigned to group B if serum creatinine levels were below 2 mg/dl and to group C if serum creatinine levels were above 2 mg/dl.The study population comprised 109 patients  with a median age of 48.2 years (range 11.9–74.3) in the hemodialysis group (group A), a median age of 51.0 years (range 29.2–71.2) in the group with persisting RHPT after kidney grafting and good graft function (group B), and 54.6 years (range 64.9–26.7) in the group with persisting RHPT after kidney grafting and reduced graft function (group C). Preoperative patient characteristics and baseline data of the trial population are depicted in Table Intact PTH (iPTH) levels were measured within the first postoperative week, using the Roche Elecsys 1010 or 2010 assays . Normal iPTH values range from 10 to 65 pg/ml.PTX was classified “total” when iPTH levels dropped to 10 pg/ml or below, “subtotal” between 10 and 65 pg/ml , and “insufficient” if levels stayed above 65 pg/ml within the first week after surgery and later.The patients were followed up for a median of 32 months (range 6–95 months). The follow-up ended if a patient on hemodialysis received a kidney graft, or if a patient with a functioning kidney graft at the time of surgery required hemodialysis in the course, as either condition implies a change of the metabolic situation.The primary outcome of this retrospective study was the rate of “total PTX” which can be achieved in patients with RHPT when an adequately extended surgical protocol is applied, with the removal of at least four parathyroid glands, transcervical thymectomy, and resection of the lymphatic tissue along both recurrent laryngeal nerves  or, contrariwise, the rate of patients, in whom “total PTX” cannot be reached, even with such an aggressive procedure.Secondary outcomes were the rates of recurrence and persistence of RHPT, the rate of occurrence of supernumerary glands, and postoperative morbidity, when this extended surgical protocol is applied. Descriptive methods were used for data presentation.Of 142 patients, operated for RHPT in our institution during a 7-year period between 1996 and 2003, 132 consecutive patients  underwent total PTX and AT as surgical procedure  and is unknown in the other 3 patients. Seven patients were unavailable for follow-up. Ten patients were not eligible for analysis, as nine received a functioning kidney graft within less than 6 months after surgery, a time frame, which was set to be the minimum for interpretation, and 1 patient with recurrence of disease died before we could localize the site of excess PTH production.Biochemically proven total PTX (PTH levels dropped to < 10 pg/ml) was achieved by extended surgery in 80 (73.4%) of 109 patients. PTX was considered biochemically “subtotal” (PTH levels between 10 and 65 pg/ml) in 25 (22.9%) patients and biochemically “insufficient”  in 4 (3.7%), respectively.In group A  was achieved in 19 of 50 hemodialysis patients (38%). Biochemically insufficient PTX (PTH levels remained above 65 pg/ml during the first postoperative week) was observed in 4 of 50 patients (8%).In group B  had five glands removed on primary intervention. In 2 cases, the supernumerary glands were ectopic and localized in the routinely resected thymus; in 4 others, orthotopic in the cervical fatty tissue along the trachea and/or the esophagus.In 2 other patients, supernumerary ectopic glands were located in the mediastinum, which were not detected on preoperative MIBI Scan and therefore missed. Both led to a persistence of disease and were resected in second operation.Overall, a median of one parathyroid gland was located on preoperative MIBI scan. No ectopic parathyroid glands were detected.Applying this surgical protocol, 2 (1.8%) of 109 patients had temporary unilateral laryngeal nerve palsy. There were no permanent nerve palsies.Overall, persistent disease was observed in 9 (8.3%) patients, in 6 of 25 patients (24%) with “subtotal” PTX, and in 3 of 4 patients (75%) with “insufficient” total PTX, respectively.Recurrent disease was documented in 8 (7.3%) patients. It occurred in 6 (7.5%) of 80 patients with biochemically proven “total” PTX and in 2 (8%) of 25 patients with “subtotal” PTX. It was not observed in patients with “insufficient” total PTX. Recurrent disease was exclusively graft-dependent.Total PTX aims at the complete removal of all parathyroid tissue. In the literature, “total PTX” is defined technically, and the standard strategy for this is described as the removal of all visible glands together with bilateral transcervical thymectomy. In a review of anatomic and functional studies, “supernumerary” glands occur in up to 33% of patients –17. TherWhenever PTX is termed “total,” one should expect undetectable iPTH levels after surgery, which could consequently serve as the objective biochemical definition of total PTX. An attempt to assess this intraoperatively was made by implementing intraoperative PTH monitoring (IOPTH) but the significance of IOPTH in patients with RHPT is under discussion . DependiAnalyzing the iPTH levels obtained within the first postoperative week, the operative outcome was defined as “total,” “subtotal,” or “insufficient.” “Total PTX” defined as a postoperative drop of iPTH levels to 10 pg/ml or below was revealed in 80 (73.4%) of 109 patients regardless of the background metabolic situation at the time of surgery. Considering the radicalness of the operative procedure, this may seem surprisingly low.In the literature, data which refer to the postoperative outcome of “total” PTX are hardly comparable as operative routines vary and both assessment and interpretation of biochemical and clinical results are not standardized –13, 25. In the current study, the highest rate of biochemically “total” PTX——was achieved in patients who had a kidney graft at the time of surgery with creatinine levels < 2.0 mg/dl. The outcome in these patients during the first postoperative week was very similar to that in patients with primary HPT, because parathyroid hyperplasia is partly reversible after successful kidney transplantation (tertiary hyperparathyroidism).If PTX was carried out while patients still were on hemodialysis (secondary hyperparathyroidism), only 27 (54%) of 50 patients turned out to be biochemically “total.” Isolated cell nests have been suggested to account for detectable PTH after total PTX. They occur in the thymus, thyroid, and cervical fat [Biochemically “insufficient” PTX occurred only in patients on hemodialysis . PTH levels remaining > 65 pg/ml during the first postoperative week cannot be explained by stimulated cell nests and reduced PTH clearance alone. Such levels indicate inadequate resection and must be counted as surgical failures.Persistence of disease did not occur in patients with an initial PTH drop to < 10 pg/ml within the first postoperative week. Overall, persistence occurred in 9 (8.3%) of 109 patients. However, only 2 patients (1.8%) were re-operated and supernumerary glands were removed in both. All supernumerary glands were located deep in the mediastinum and were not removed during routinely performed bilateral cervical thymectomy. Recurrence of disease was solely attributed to autograft-hyperfunction and occurred in 8 (7.3%) of 109 patients predominantly (6 of 8 patients) on continuous hemodialysis. In a study population of 1837 patients, Matsuoka et al.  report an = 100 analyzed patients reported 3% persistence and 4% recurrence of HPT after surgery. These results seem better than in the present study. Our study was retrospective and did not have a control group; therefore, no recommendations can be given. However, our data show that even a radical approach does not remove all parathyroid tissue from the neck in all patients, which should be taken into consideration when planning the surgical procedure.This recurrence rate is higher than in the present study. However, it has also been shown recently that PTX without AT and TCT can be safely performed and does not show a higher rate of persistence or recurrence . The proPermanent hypoparathyroidism and its effects on bone metabolism are well-known possible consequences of total PTX and may require replantation of cryopreserved tissue . In thisThe limitations of this study were its retrospective and observational nature, a relatively short follow-up of 32 months on average and a lack of data on the prevalence of a dynamic bone disease in our study cohort.Although applying a very radical concept in patients with RHPT, PTX was “total” in only 73.4%. Persistence of disease was avoided in 91.7% and low morbidity was documented. In conclusion, it seems difficult to remove all parathyroid tissue from the neck which has to be considered when choosing the surgical procedure.


The causes of Cenozoic uplift of the Colorado Plateau, southwestern USA, are strongly debated, though most hypotheses acknowledge the importance of northwest-directed subduction of the Farallon oceanic plate beneath North America since c. 100 Ma. Existing thermomechanical models suggest that the Farallon slab underthrust the proto-plateau region at ~200 km depth, removing the basal portions of its subcontinental lithospheric mantle (SCLM) root, although such small-volume subduction erosion cannot fully account for the degree of uplift observed today. Here we show via petrological modeling of lawsonite-bearing eclogite xenoliths exposed in diatremes in the center of the plateau that the Farallon slab surface penetrated through the proto-plateau SCLM at much shallower depths (~120 km) than these previous estimates, allowing shear-removal of ~80 km of SCLM – a volume up to three-times greater than previously suggested. This removal led to asthenospheric upwelling and isostatic rebound of the plateau region during the late Cretaceous to the Eocene. We posit that similar shear-removal of SCLM likely played a major role in inhibiting cratonic growth and stabilization in the Neoarchean and Paleoproterozoic – when low-angle subduction of oceanic lithosphere was more prevalent than today – accounting for the atypically thin roots existing below many ancient cratons worldwide. Widespread surface uplift and plateau formation at c. 25 Ma relative to the adjacent, low-elevation Great Plains  removal from the overriding plate far inland of the plate boundary, affecting its buoyancy18. Regional-scale numerical models of Farallon slab subduction over the past ~100 Myr suggest that the angle of dip of the slab has decreased over time21, although estimations of its paleo-depth below the continental USA at the time of eclogitization and the mass of lithospheric mantle displaced or removed by its progression are wide-ranging22. As such, there remains uncertainty surrounding the degree of subducted slab–SCLM interaction and the extent to which it may have driven uplift of the Colorado Plateau during the late Cretaceous to Eocene24.Shallow-angle subduction of oceanic lithosphere  is an uncommon process on Earth today, but is an important mechanism for crustal recycling, as it promotes transport of material from the overriding plate to the subduction channel via subduction erosion25, indicating large-scale shear-removal of at least ~80 km of the pre-uplifted Colorado Plateau’s mantle keel – notably larger than volumes predicted by previous thermomechanical and petrological models. This effect is likely to have been significantly important in the Late Archean and Proterozoic, when low-angle subduction of oceanic lithosphere was more prevalent than today.Here, we present new petrological data from lawsonite-bearing eclogite xenoliths sampled from the c. 30–20 Ma Navajo Volcanic Field (NVF), central Colorado Plateau Fig. , which r2) of high mean elevation (~2000 m above sea level) located in the southwestern interior of the USA  conditions experienced by the top of the Farallon slab. Zircon and monazite from eclogitic xenoliths have produced U–Pb ages of c. 80–30 Ma33, which are interpreted to date prograde-to-peak metamorphism and progressive devolatilization during subduction.Cenozoic volcanic edifices within the NVF, central Colorado Plateau Fig. , comprisP–T history of eclogite xenoliths from this region. Temperatures of peak metamorphism are fairly well constrained at ~560–700 °C, although corresponding pressure estimates made by previous workers range from ~26 kbar to ~50 kbar33, implying that the top of the Farallon slab was located somewhere between ~100–200 km depth. While this lower bound is supported by coesite inclusions in garnet31, which requires ultrahigh-pressure (UHP) conditions (>27 kbar) to stabilize, this upper-limit uncertainty significantly hinders reliable geometric reconstruction and/or validation of geodynamic models of slab subduction beneath the proto-plateau during the Cenozoic.Due to variable degrees of retrogression, conventional thermobarometry has so-far been unable to place precise constraints on the metamorphic 34. Mineral proportions and a detailed mineral characterization of the individual samples are provided in Supplementary Figs During fieldwork conducted in June 2017, multiple samples of mafic eclogite xenoliths were collected from various diatremes in the NVF Fig. . In this31 (~1%) and 17MSR09 has additional phengite (4%). Microtextural relationships suggest that the peak eclogite-facies mineral assemblage comprised garnet + omphacite + lawsonite + rutile ± phengite ± coesite31. Garnet occurs as small- to medium-sized porphyroblasts up to ~1 cm in diameter  to rim  , omphacite (~57–80%), lawsonite (~1%), zoisite (~1–15%), and rutile (~1%) Fig. . Sample ter Fig.  that pre9–30%, omphengite %. Microtite Fig. , whereas 31 Fig. . Some po 31 Fig. . Lawsoni 31 Fig. . This mived Fig. . Omphacived Fig. , indicatP–T conditions for all eclogite xenoliths prior to exhumation were calculated via petrological phase equilibrium modeling, which employs an iterative Gibbs free energy minimization procedure to determine the most stable mineral, fluid, and/or melt assemblage that would form at specific P–T conditions in a fixed bulk-rock composition37. Peak P–T conditions at which each xenolith likely equilibrated were obtained by correlating predicted mineral proportions with the values measured in each sample  relations considered for phases exhibiting solid solutions are described in the Methods section.Peak ple Fig. –7, whilsP–T phase equilibrium diagram for xenolith 17MSR09 is shown in Fig. P > 35 kbar and T < 640 °C. This field is limited at lower pressure by the stabilization of glaucophane – which is not observed within the stable assemblage – and at higher temperatures by the consumption of lawsonite. Isolines of equal volume proportion of garnet, omphacite, and lawsonite constrain peak metamorphism at ~37 kbar and ~620 °C, with associated 1σ uncertainties of ~1 kbar and ~50 °C39. This pressure for the Farallon slab surface thus infers a minimum depth of equilibration of ~120 km, assuming lithostatic conditions, as outlined below. Petrological modeling results for xenoliths 17GR11 and 17MSR11 are shown in Supplementary Figs P–T conditions for peak metamorphism within error. An independent estimate of peak metamorphic pressure for sample 17MSR09 was obtained via the garnet–omphacite–phengite barometer calibration for white mica-bearing eclogites41. Compositions for garnet rim domains and adjacent matrix omphacite and phengite in textural equilibrium , these occurrences are exclusively UHP terranes formed via deep subduction of continental crust, which provides positive buoyancy for rapid exhumation and preservation. Subducted oceanic crust or eroded mafic fragments from the base of an overlying arc subjected to thermal diffusion over periods longer than ~5–10 Myr are expected to thermally equilibrate, as the characteristic diffusion distance for this time scale at mantle conditions is ~10–15 km41. Thus, it is unlikely that the uppermost or middle portions of the Farallon slab crust could preserve such low thermal gradients, as geochronology of eclogite xenoliths indicates that the experienced prograde metamorphism for at least 45 Myr33.We limit the calculated peak conditions of metamorphism to lie outside of the ‘forbidden zone’, defined by 44. The c. 80–30 Ma age range recorded by eclogite xenoliths33 from the NVF suggests that metamorphic recrystallization was prevalent during the low-angle and flattened subduction stages of the Farallon plate. Thus, we interpret the peak P–T conditions determined from xenoliths 17MSR09, 17GR11, and 17MSR11 in this work 25 imply a similar thickness beneath the former prior to shear removal. Consequently, over ~80 km of SCLM must have been removed from the base of the proto-plateau’s root due to northeastward progression of the subducted Farallon plate, which is greater than estimates provided by recent studies (~20–50 km)20.The results of thermobarometry shown here constrain the depth and dip-angle of the Farallon plate during this period, and so the thickness of the SCLM below the Colorado Plateau (see Supplementary Methods). In a two-layer model that considers representative densities for the upper and lower continental crustbar Fig. . The prebar Fig.  and 4a,  25 Fig.  share siP–T data. Current geodynamic models suggest that the Farallon slab flattened ~1000 km inboard of the oceanic trench during the early stages of the Laramide orogeny21 33, which necessarily must have been exhumed from the same paleo-slab top due to their spatially restricted occurrence in the northwestern NVF. However, over the past decade, petrological phase equilibrium modeling has become the preferred technique with which to perform reliable forward and inverse modeling of subduction zone processes50 as it employs a multi-equilibrium approach combining internally consistent thermodynamic data and more geologically realistic a–x relations for minerals with solid solutions. The peak P–T conditions obtained here using this technique  and thus is more buoyant than other SCLM beneath North America56, which has a density of ~3.38 g/cm3 – similar to that forming the roots of many Archean cratons57 , and eventually sink into the underlying mantle  SCLM that is more chemically depleted will be significantly more conducive to penetration by the Farallon slab during flat subductiontle Fig. . Our dation Fig. . In thes63, many studies agree that early plate tectonics involved shallow subduction within a hot Neoarchean–Paleoproterozoic mantle (c. 3.0–1.7 Ga)64, with occasional slab tearing and breakoff. This period of Earth history represents a convergence of many major geological transitions, including the widespread emergence of continental crust from beneath the oceans and the associated saturation of Earth’s atmosphere with oxygen (the Great Oxygenation Event)65. Sub-horizontal subduction of the Farallon oceanic slab shows fundamental parallels with this early-Earth regime and may further account for the occurrence of some atypically thin Archean cratonic roots worldwide. Thermal estimates of continental lithospheric thickness show a consistent increase with age, from ~100 km in the Phanerozoic to ~250 km in the Early Proterozoic66. Archean cratonic lithosphere, however, has a bimodal distribution at ~350 km and ~220 km, despite thermal modeling suggesting an equilibrium thickness of >400 km66. Mechanisms such as thermo-mechanical erosion by secondary mantle convection67, erosion by mantle plumes68, delamination due to Rayleigh-Taylor-type gravitational instabilities in the lower lithosphere69, and erosion by basal drag70 have all been suggested by previous workers, although our results suggest that the hotter ambient Neoarchean mantle may have alternatively promoted lithospheric shear-removal of these keels, akin to that documented here for the Colorado Plateau. As such, similarities between thinned SCLM in Neoarchean and Phanerozoic terranes provides support for these key geodynamic processes having operated similarly throughout much of geological time.What are the implications of this result for the efficacy of subduction erosion and removal of continental roots throughout Earth history? While the timing of the onset of subduction within the geological record is unresolvedMajor-element compositional analyses of minerals in each xenolith were acquired using a JEOL JXA 8900 electron microprobe housed at the Denver Microbeam Laboratory at the United States Geological Survey (USGS), Colorado, USA. Both natural and synthetic materials were used as standards for calibration, and a ZAF correction routine was applied. Operating conditions comprised an acceleration voltage of 15 keV, a beam current of 20 nA, and a beam diameter of 5 μm for mica and 1 μm for all other minerals.31. Automated mineralogy scans and obtained proportions for each eclogite xenolith are shown in Supplementary Figs Volume proportions of minerals in each xenolith were acquired via automated mineralogy, using a TESCAN VEGA-3 model LMU VP scanning electron microscope housed at the Department of Geology and Geological Engineering, Colorado School of Mines, USA. An electron beam was rastered across the surface of a thin section of each xenolith sample at a pixel resolution of 25 µm, using an acceleration voltage of 25 keV and beam intensity of 14.5 nA. Four energy-dispersive detectors simultaneously acquired a backscattered electron (BSE) image at each pixel and a chemical composition. Mineral characterization was performed using both BSE and compositional information, which were compared to spectra stored in an internal database. This procedure produced quantitative mineral abundance maps for each sample, with area proportions in thin section assumed to be representative of volume proportions throughout each xenolith. The calculated proportion of zoisite was considered to represent that for lawsonite at peak metamorphic conditions, as the fine-grained acicular zoisite pseudomorphs retain the original rhombohedral outlines of parent lawsonite, indicating direct replacement with no significant volume change during retrogression72 and the internally consistent thermodynamic data set ds6273. Eclogite xenoliths 17GR11 and 17MSR11 were modeled in the nine-component Na2O–CaO–FeO–MgO–Al2O3–SiO2–H2O–TiO2–O2 (NCFMASHTO) system, whereas petrological modeling of phengite-bearing xenolith 17MSR09 additionally considered K2O. The following a–x relations for solid-solution phases were used: clinopyroxene (diopside–omphacite–jadeite) and clinoamphibole (glaucophane–actinolite–hornblende)74; garnet, biotite, muscovite–paragonite, and chlorite75; epidote73; plagioclase76; and ilmenite77. Pure phases comprised talc, lawsonite, kyanite, zoisite, quartz, coesite, and rutile. Mineral abbreviations follow the guidelines of Whitney and Evans78. Effective bulk compositions for each xenolith were calculated using mineral proportions derived by automated mineralogy and representative EPMA-derived compositions79. Adjustments to measured mineral compositions were made using the “ideal analysis” approach of Powel and Holland38, where necessary, to reduce misfit between natural and modeled compositional systems. Individual bulk-rock compositions used to perform phase equilibrium modeling are shown in Supplementary Table Phase diagram construction was performed using the Gibbs free energy minimization software Theriak-Domino39, with this variation being largely a function of propagated uncertainty on end-member thermodynamic properties within the data set. However, as all phase diagrams were calculated using the same dataset and a–x relations, similar absolute errors associated with dataset end-members cancel, and calculated phase equilibria are relatively accurate to within ±0.2 kbar and ±10–15 °C39. The P–T conditions of peak metamorphism for each xenolith were determined by comparing mineral proportions calculated by automated mineralogy against those predicted in each petrological model (Fig. Uncertainties related to the absolute positions of assemblage field boundaries on calculated phase diagrams have been shown to be less than ±1 kbar and ±50 °C at the 2σ leveldel Fig. .Supplementary material


Inflammatory breast cancer (IBC) is the most rare and aggressive subtype of breast cancer characterized by clusters of tumor cells invading lymph vessels, high rates of metastasis, and resistance to systemic chemotherapy. While significant progress has been made in understanding IBC, survival among IBC patients is still only one half that among patients with non-IBC. A major limitation to the development of more specific and effective treatments for IBC is a lack of identifiable molecular alterations that are specific to IBC. Emerging evidence suggests that the aggressive nature of IBC is not specific to IBC cells but instead driven by the interplay between autonomous signaling and context-dependent cytokine networks from the surrounding tumor microenvironment. Recently, the type I interferon, specifically the interferon alpha signature, has been identified as a pathway upregulated in IBC but few studies have addressed its role. Activation of the interferon alpha signaling pathway has been shown to contribute to apoptosis and cellular senescence but is also attributed to increased migration and drug resistance depending on the interferon-stimulated genes transcribed. The mechanisms promoting the increase in interferon alpha expression and the role interferon alpha plays in IBC remain speculative. Current hypotheses suggest that immune and stromal cells in the local tumor microenvironment contribute to the interferon alpha signaling cascade within the tumor cell and that this activation may further alter the immune and stromal cells within the microenvironment. This review serves as an overview of the role of interferon alpha signaling in IBC. Ideally, future experiments should investigate the mechanistic interplay of interferons in IBC to develop more efficacious treatment strategies for IBC patients. Inflammatory breast cancer (IBC) is the most aggressive and lethal subtype of breast cancer accounting for 3% of total breast cancer diagnoses but 10% of total breast cancer-related deaths  and the Researchers have turned to genetic profiling to identify molecular alterations distinct to IBC; however, these studies remain inconclusive perhaps due to the additional complexity driven by the tumor microenvironment (TME) . Key comRecently, studies have suggested that IBC cells have increased levels of interferon alpha (IFNα) , 14. IntIn 2014, Bertucci et al.  publisheIFNα belongs to the family of type I interferons which also consists of IFNβ . ThirteeFor interferons to elicit their effect, they must bind to their specific receptor which is outlined in Fig. Gene transcription mediated by IFNα is tightly regulated by multiple processes including stability of the IFNα/IFNAR1/IFNAR2 complex, the concentration of IFNAR1/2 on the membrane and transcription of negative regulators including suppressor of cytokine signaling (SOCS) and ubiquitin-specific peptidase (USP) 18 . An in-dStimulation of IFNα transcription is a complex process and is outlined in Fig. In the absence of bacterial or pathogenic signals, cancer cells can transcribe IFNα in response to endogenous danger signals driven by persistent DNA damage response because of chromosomal instability (CIN)  Fig. 2)2). CanceThough there is limited information regarding IFNα in IBC, it is widely accepted that NFκB is elevated in IBC cell lines and patient tumors. IFNα could perhaps be controlled via NFκB indirectly since NFκB transcribes IFNβ which can promote transcription of IRF7 and IRF3, key regulators of IFNα . InteresMoving forward, it is important to consider investigating the genetic amplification of factors regulating IFNα signaling, post transcriptional modifications of these factors, and the intricate web of feedback and feedforward mechanisms that may be contributing to increased IFNα.We have established that IFNα may contribute to IBC tumor aggression; however, the specific role of IFNα is determined by many factors including its concentration, the specific tumor type, and the duration of the stimulus. For example, induction of antiviral activity requires a few hours of IFNα exposure whereas antiproliferative activity requires constant exposure or high concentrations of IFNα . IFNα haSTATs can promote their effect independent of phosphorylation from canonical IFNα signaling as outlined in Fig. .Aside from non-canonical IFNα signaling, IFNα is known to mediate activation of other cellular pathways through intracellular crosstalk. Interestingly, a mechanism whereby IFNα may lead to cellular aggression instead of apoptosis is through activation of NFκB signaling via STAT3 and PI3K/AKT . This paEmerging evidence suggests that ISGs are responsible for the aggressive phenotype of many cancers. A few of which are outlined in Table Though STATs are not active, low levels of IFNα may be sustaining ISG production. Perhaps this is due to IFN control on STATs themselves. We have previously shown that siRNA against IFNα decreases STAT2 levels but not STAT1 levels in TN-IBC. Additionally, loss of STAT2, but not STAT1, was associated with decreased proliferation and migration in TN-IBC cells . TherefoIFNα production from the tumor cells may have the capability of educating the microenvironment to be pro-survival for tumor cells. Likewise, tumor microenvironment (TME) components may be able to promote or enhance the migratory and invasive capacities of IBC cells, perhaps through influencing JAK/STAT signaling. Interestingly, one study has shown that 63.3% of breast cancers are positive for IFNα and that stage III breast cancers had no IFNα binding to the receptor complex suggesting constitutive secretion of IFNα but a lack of autocrine signaling . JAK/STAIn this section, we discuss the role of IFNα on immunosurveillance and how this may lead to neoplastic initiation and IBC progression followed by a discussion of how IFNα may impact different cell types within the IBC TME. Figure As previously discussed, IBC tumor emboli consist of tumor cells and immune cells and are highly metastatic , 8. TherDuring initial tumor formation, immune cells surrounding the tumor will recognize tumor-specific antigens to eliminate the transformed cells. Canonically, IFNα is a known tumor suppressor by inducing cellular senescence and death through recruiting dendritic cells and activating T cells . HoweverThe mechanism by which immune and stromal cells may drive the upregulation of tumor secreted IFNα remains elusive. Perhaps the stroma releases paracrine signals to neoplastic cells which then maintain these signals through endogenous autocrine signaling, promoting transformation and allowing cancer to progress with an ever-changing microenvironment. Regarding this crosstalk, we hypothesize that low levels of IFNα produced from immune cells in the microenvironment promote the transformation of epithelial cells with an increase in IFNα which subsequently makes the microenvironment conducive to tumor progression. This has been observed through chronic treatment with IFNβ, showing that specific ISGs remain activated in the absence of IFNβ as well as during chronic interferon signaling . Moving Dendritic cells (DCs) are activated by and are key producers of IFNα . There aMacrophages are the most abundant leukocyte present in the tumor stroma and display a high level of plasticity allowing adaptation to environmental stimuli. Despite popular evidence, macrophages do not exist as strictly M1 (anti-tumor) or M2 (pro-tumor) phenotypes, but instead lie within the spectrum. M1 polarization occurs due to exposure to interferon (IFN) γ, lipopolysaccharides (LPS), or TNFα produced by Th1, natural killer, or antigen presenting cells . M1-polaIFNα is known to promote macrophages to favor the M1 phenotype Fig. a 53]; h; h53]; hPerhaps IFNα secreted from the IBC tumor cells at a low dose avoids the rapid induction of M1 polarization while the chronic production eventually alters the macrophage phenotype, increasing the complexity of this relationship. Evidence suggests that macrophages are a key player in the microenvironment in IBC, yet many questions remain to be addressed. Specifically, how is IFNα a key regulator of macrophages within the IBC tumor TME and what are the other macrophage cell-cell relationships that are altered..Cancer-associated fibroblasts (CAF’s) are stromal cells that synthesize ECM and collagen and aid in wound healing. Though the involvement of CAFs in IBC is understudied, it is known that CAFs with high levels of IFNα response genes promote the growth of breast cancer MCF-7  cells in an in vitro co-culture method Fig. b 56]. T. T56]. TIt is known that type I interferons normally have anti-angiogenic properties . HoweverEvidence presented above suggests that IFNα is an important factor in IBC tumor development and progression but the functions of IFNα and how this cytokine may relate to other cellular processes remain unclear. IFNα signaling is comprised of multiple feedback loops, alternative signaling mechanisms, and communication between nearby cells contributing to multiple layers of system complexity. In IBC specifically, emerging evidence suggests that the tumor microenvironment is a key driver of onset and aggression. All cells can respond to IFNα and the response is dependent on concentration and tissue type making IFNα a highly pleiotropic cytokine.IFNα as therapy has been extensively studied; however, targeting tumor produced IFNα or downstream signaling is new territory. Currently, ruxolitinib, a JAK1 and JAK2 inhibitor, is being investigated in treatment of primary and metastatic triple-negative breast cancer . RuxolitIn future efforts to uncover the mechanistic insight into how IBC cells utilize IFNα for tumor progression, we must consider both intracellular signaling crosstalk and the tumor microenvironment. Doing so will help define the complexity of this system in hopes of contributing to the development of more efficacious therapies targeting both the tumor cell and the surrounding microenvironment.


Panicum virgatum L.) and gamagrass (GG: Tripsacum dactyloides L.), but it remains unclear whether these effects are the same between crops and under different rates of fertilization. 13C and 15N are  two important proxy measures of soil biogeochemistry, but they were rarely examined as to their spatial distributions in soil. Based on a three-year long fertilization experiment in Middle Tennessee, USA, the top mineral horizon soils (0–15 cm) were collected using a spatially explicit design within two 15-m2 plots under three fertilization treatments in SG and GG croplands. A total of 288 samples were collected based on 12 plots and 24 samples in each plot. The fertilization treatments were no N input (NN), low N input (LN: 84 kg N ha−1 in urea) and high N input (HN: 168 kg N ha−1 in urea). The SOC, TN, SOC/TN (C: N), δ13C and δ15N were quantified and their within-plot variations and spatial distributions were achieved via descriptive and geostatistical methods. Results showed that SG generally displayed 10~120% higher plot-level variations in all variables than GG, and the plot-level variations were 20~77% higher in NN plots than LN and HN plots in SG but they were comparable in unfertilized and fertilized plots in GG. Relative to NN, LN and HN showed more significant surface trends and spatial structures in SOC and TN in both croplands, and the fertilization effect appeared more pronounced in SG. Spatial patterns in C: N, δ13C and δ15N were comparable among different fertilization treatments in both croplands. The descending within-plot variations were also identified among variables (SOC > TN > δ15N > C: N > δ13C). This study demonstrated that N fertilizations generally reduced the plot-level variance and simultaneously re-established spatial structures of SOC and TN in bioenergy croplands, which little varied with fertilization rate but was more responsive in switchgrass cropland.Nitrogen (N) fertilizers can potentially alter spatial distribution of soil organic carbon (SOC) and total nitrogen (TN)  concentrations in croplands such as switchgrass (SG:  Panicum virgatum L) and gamagrass (GG: Tripsacum dactyloides L) are common alternative energy sources for sustainable replacement of fossil fuels5. N fertilizers are widely amended to increase bioenergy crop yields8, but N fertilization impact on soil organic C (SOC) and total soil N (TN) contents varied in magnitude and signal11. The large variability of fertilization effects among different studies are seldom attributed to the underlying variations in space. In fact, the generally very low number of soil samples in a study  inevitably amplified the influence of spatial variations on the detected treatment effect12. Furthermore, the crop-specific root morphology and chemistry largely regulated the spatial variation of soil biogeochemistry14 and may have contributed to contrasting SOC and TN stocks and their responses to N fertilization between SG and GG15. Thus, elucidating the effects of fertilization on spatial distribution of soil C and N will provide fundamental knowledge needed to develop effective strategies to improve soil quality, C sequestration, agricultural productivity, and climate change adaptation19.As two important bioenergy crops, perennial switchgrass . It remains largely unknown whether the fertilization effects will depend upon the duration of fertilization.A limited number of studies however have focused on the spatial distributions of soil C and N in bioenergy croplands. In a SG cropland, the spatial dependence of SOC and TN at soil depth of 0–30 cm is weak to moderate when the point-to-point distance is less than 200 m13C and δ15N are widely used to infer vegetation succession, SOC dynamics, and nutrient leaching in bioenergy croplands32, the spatial variability of these biogeochemical tracers has yet to be studied in SG or GG. In a subtropical woodland, the distance of dissimilar δ13C in soil appears beyond 15.6 m , which is far greater than individual tree canopy diameter in these lowland communities33. TN and δ15N are likely to display more spatial variations due to relative low concentrations and diverse chemical forms34, but these have not been confirmed yet. We speculate that the N fertilizer induced greater input to soil via litterfall and root exudate may have contributed to altered spatial variations of microbial biomass as observed formerly22, and this can further stimulate microbial mineralization of more 13C enriched and older soil organic matter36. This speculation will not only decrease δ13C values in soil under N fertilization, which resulted from greater release of 13C via heterotrophic respiration of old-aged soil37, but also change the spatial distribution of 13C. However, no studies have reported the spatial variations of soil δ13C and δ15N in different bioenergy croplands and under different N fertilization treatments.Soil δ−1) will reduce the within-plot variances but restructure the spatial patterns of SOC, TN, C:N, δ13C, and δ15N; Furthermore, these aforementioned fertilization effects little depend upon fertilization rate or crop type.Using a bioenergy crop field experiment in Middle Tennessee, we investigate the effects of N fertilization on the plot-level variances and spatial patterns in elemental and stable isotopic characteristics of soil C and N in two bioenergy croplands (SG and GG). N fertilization input represents the primary management practice in our research plots and no tillage, plowing, or minor mechanical disturbance was applied. We hypothesize that relative to those soils that have not been fertilized for 3 years, continued N fertilization at either low or high rates (84 and 168 kg N ha38. Two crop types and three N fertilization levels were included in a randomized block design39. The two crop types were Alamo SG (Panicum virgatum L.) and GG (Tripsacum dactyloides L.). The three N levels included no N fertilizer input (NN), low N fertilizer input (LN: 84 kg N ha−1 yr−1 as urea), and high N fertilizer input (HN: 168 kg N ha−1 yr−1 as urea), and each treatment had four replicated plots with a dimension of 3 m × 6 m  with acidic soil pH  and intermediate organic matter content of 2.4%41.Prior to the switchgrass and gamagrass croplands, the land use is the mowed grassland for decades. No fertilizers have been applied in the prior land use. Therefore, the indigenous variations are similar in both croplands. Initially established in 2011, the bioenergy crop field experiment is located at the Tennessee State University (TSU) Main Campus Agriculture Research and Education Center (AREC) in Nashville, TN, USA . Climate in the region is a warm humid temperate climate with an average annual temperature of 15.1 °C, and total annual precipitation of 1200 mmx, y coordinates. A total of 288 soil cores were obtained based on 24 cores in each of 12 plots. Similar clustered soil sampling approaches were described in formerly published work22. The soil samples were transported to the TSU lab in a cooler filled with ice packs and were then subsequently stored at 4 °C until analysis. Visible roots and rocks were removed from the samples, and soil samples were then passed through a 2 mm soil sieve. The air-dried soil subsamples were ground and homogenized to fine powder for the analysis of SOC, TN, stable carbon, and nitrogen isotopic compositions . The analysis was conducted at the University of North Carolina Wilmington Isotope Ratio Mass Spectrometry facility using a Costech 4010 elemental analyzer interfaced with a Thermo Delta V Plus stable isotope mass spectrometer.We collected soil samples 0–15 cm) from 12 plots (2 crops × 3 N inputs × 2 replicated plots) on June 6, 2015. Within each plot, we divided a 2.75– m × 5.5– m rectangular zone into eight equal-sized square subplots. Within each subplot, a centroid was established and a circular sampling zone was created with the diameter equivalent to side length of the square , microbial biomass N (MBN) and MBC: MBN (C: Nmb). The microbial biomass data were adapted from the previous publication22. The study derived the sample size requirement (N) in each plot given specified relative errors  in order to evaluate how within-plot variances  are altered by N fertilization or crop type at certain relative error.s, n, N, CV, and γ denote confidence interval, plot mean, plot standard deviation, sample number (n = 24), coefficient of variation, sample size requirement and relative error, respectively. t0.975 = 1.96. The log transformed sample size requirement (N) has a negative linear relationship (i.e. slope = 2) with the log transformed relative error (γ).The frequency distribution, within-plot variance, plot level coefficient of variation (CV), and sample size requirement were calculated to describe plot level variances44. Soil properties that exhibited non-normal distributions were log-transformed to better conform to the normality assumption of the Cochran’s C test21. The variances were compared between all plots under three fertilization treatments for each crop and among two crops. When p-value is < 0.05 for the comparison conducted in each crop, the largest variance was identified.Cochran’s C test is used to test the assumption of variance homogeneity. The test statistic is a ratio that relates the largest empirical variance of a particular treatment to the sum of the variances of the remaining treatments. The theoretical distribution with the corresponding critical values can be specified22. Brief introduction of the three geostatistical approaches were also attached. To note, the plot-level variation  was calculated based on the 24 measurements of soil samples randomly collected in a plot. By accounting for their respective spatial coordinates and distance among samples, the same number of measurements was also used to derive the spatial variability  via the three different geostatistical methods. Therefore, there is no direct correlation between the spatial variability  and plot-level variation .Three different geostatistical approaches were used to display the spatial pattern, structure and distribution of all variables within and among plots and they include trend surface analysis (TSA), Moran’s I index for spatial autocorrelation, and inverse distance weighting (IDW) for distribution map. Details can be found in former publicationsFirst, the trend surface analysis (TSA) is the most common regionalized model in which all sample points fit a model that accounts for the linear and non-linear variation of an attribute. The relationships between the soil properties and the x and y coordinates of their measurement location within the sampling plots are estimated with the trend surface model:0 to β5. The presence of a trend in the data was determined by the significance of any of the parameters β1 to β5, while the β0 term modeled the intercept46. Linear gradients in the x or y directions were indicated by significance of the β1 or β2 parameters. A significant β3 term indicated a significant diagonal trend across a plot. Significant β4 and β5 parameters indicated more complex, nonlinear spatial structure such as substantial humps or depressions. Trend surface regressions were estimated using S-plus . Model parameters were determined to be significant at a level of P < 0.05. The number of significant parameters was counted for each plot and compared among treatments.with regression coefficients β46. The Moran’s I analysis49 was used to quantify the degree of spatial autocorrelation that existed among all soil cores taken from each plot. The resulting local Moran’s I statistics are in the range from –1 to 1. Positive Moran’s I values indicate similar values (either high or low) are spatially clustered. Negative Moran’s I values indicate neighboring values are dissimilar. Moran’s I values of 0 indicate no spatial autocorrelation, or spatial randomness. A significant autocorrelation is determined if the observed Moran’s I value is beyond the projected 95% confidence interval at certain distance. Correlograms for local Moran indices were estimated for each soil variable in each plot in a range of 0–5.5 meter with 0.5 meter incremental interval. The number of distance corresponding to the significant Moran’s I was counted for each plot and compared among treatments.Second, residuals from the trend surface regressions were saved for subsequent spatial analysis using a Moran’s I index50, we used inverse distance weighting (IDW) interpolation rather than ordinary kriging51. The maps produced by IDW offered direct and visual assessments from which to compare the spatial distributions of the soil properties among the plots. The IDW method derived maps was able to distinguish effects of different land uses on spatial distributions of soil biogeochemical features in South Carolina, USA21. The weights for each observation are inversely proportional to a power of its distance from the location being estimated. Exponents between 1 and 3 are typically used for IDW, with 2 being the most common52. Tests with different IDW exponents indicated that 2 was optimal with these data, as estimated values generated with an exponent of 2.0 showed the best fit with actual data in cross validation tests. ArcGIS 9.0 was used to generate the IDW maps and perform cross validations.Third, due to relatively small sample sizes (n = 24) per plot13C in SG with the highest within-plot variance in one of HN plots meanwhile other plots of HN and LN were at least two times lower than that for NN plots .The within-plot CVs were less than 20% for all variables in both croplands and were generally larger in SG than that in GG , and only for TN and δ15N in GG.Between crops, the plotted lines of sample size requirement against relative sampling error departed from one another more pronouncedly among plots in SG than in GG  were presented in Table 13C were not significant in all plots, and the number of significant surface trends of δ15N appeared comparable in all treatments in SG; However, the number of surface trends of δ13C and δ15N were comparable in NN and LN but not in HN in GG  than unfertilized plots in both crops Table . SurfaceGG Table . No diff13C, and δ15N were identified in both SG and GG  exhibited darker color  and more evidence of spatial structures than NN plots in both croplands Figs.  and 5. Ids Figs.  and 5. Tds Figs.  and 5.Fi54. Meanwhile, it was also apparent that large plot to plot variations under the same treatment existed, e.g., CVs of most variables under NN in SG. In fact, relative to fertilized plots, the enormously larger plot-level variance always appeared in only one but not in another unfertilized plot. This suggested that despite a generally high variation of soil biogeochemistry in unfertilized bioenergy croplands, other factors such as sampling time and location, crop species and variable type may also regulate the plot-level variances. Nevertheless, with such variability for SOC and TN in unfertilized plots, three samples per plot will produce a relative error of the mean of about ± 20% in both bioenergy croplands, a sobering result given the level of interest in precise estimates of soil C and N sequestrations.Our results demonstrated that both low and high fertilization rates generally reduced the average variances and CVs across two plots in all variables in SG. However, these variations were little changed with N fertilization in GG. This was likely associated with the much higher variations in SG than in GG  is below the high fertilization rate  applied in other croplands worldwide62. Long-term soil studies will need to specifically include the spatial variability in their research theme in the future.Though significantly different from the control treatment, the low and high fertilization treatments appeared little different in either the plot-level variation or spatial heterogeneity in SOC and TN. We speculated that the experimental duration may have contributed to this phenomenon. The current study relied upon a three-year long experiment, but a longer N fertilization history  may allow us to detect the appreciable changes in spatial heterogeneity under N fertilizations. The reason lied in the fact that the changes in soil C storage were more likely detectable over decades in long-term soil experiments13C, and δ15N displayed relatively lower plot-level variations under all fertilization treatments in both croplands. This suggested that these specific variables, i.e., derived from other measured variables or proxy of integrated ecosystem processes, likely masked the inherently high variation of each individual process. Nevertheless, the fertilization effects on their spatial patterns depend on the type of geostatistical analysis, crop type and variable. Almost no surface trend was identified for C: N and δ13C in any plot in SG, which contrasted substantially with their counterparts in GG. Both surface trends and spatial autocorrelations for δ15N were much abundant in both croplands. However, no fertilization effects were significant in these analyses. In particular, the higher N fertilizer input resulted in no any significant surface trends of either δ13C or δ15N in all plots in GG. Meanwhile, great plot to plot variations were identified between the distribution maps of two unfertilized plots for C: N and δ13C, and these variations were reduced in fertilized plots, a fertilization effect consistent with those found in SOC and TN. Despite low plot-level variation, the high plot-to-plot variations between the two unfertilized plots for C: N and δ13C may result from a suite of interactions along the air-plant-soil-microbe continuum involved in photosynthate, root exudate, microbe-root associations, and other edaphic features. These multiple drivers themselves entailed high spatial heterogeneities in soils over various spatial scales66. Therefore, the complexity of biogeochemistry in soils likely has masked the effect of N fertilization on C: N, 13C, and 15N in at least some of their spatial patterns. Despite this uncertainty, the distribution maps produced in this study enabled us to detect fertilization effects that were similar across all these variables.Relative to SOC and TN, the C: N, δ13C, and δ15N, little fertilization effect was identified on their surface trends and spatial autocorrelations due to either weak or strong patterns simultaneously identified in unfertilized and fertilized plots. Effects of  low and high rates of fertilization were found identical in this study. The descending within-plot variations were also identified among variables (SOC > TN > δ15N > C: N > δ13C). This study demonstrated that distinct from the homogenization of spatial structures caused by multiple practices in traditional croplands , N fertilizations alone generally reduced the plot-level variance and simultaneously re-established spatial structures of SOC and TN in bioenergy croplands, which little varied with fertilization rate but was more responsive in switchgrass cropland.Our study demonstrated that N fertilizer input generally diminished the plot-level variances of all five variables in SG cropland but re-established the spatial structures of SOC and TN in both croplands. Although N fertilization apparently reduced the plot to plot difference in distribution maps of C: N, δSupplemental Tables&Figures.


R in the range 0.1–0.5 yields tilt angles of 40°–0°, respectively. Based on the known perpendicular adsorption of CO on Pt, an exact R-value of 0.49 was determined. Polarization-dependent SFG spectra in the pressure range 10−4 to 36 mbar did not indicate any change of the tilt angle of adsorbed CO. Modeling also indicated a strong dependence of −6 to 250 mbar. The absolute PPP and SSP spectral intensities on Pt and Pd were simulated, as well as the expected Polarization-dependent sum frequency generation (SFG) vibrational spectroscopy was employed to examine CO overlayers on Pt(111) and Pd(111) single crystal surfaces at room temperature. Utilizing different polarization combinations (SSP and PPP) of the visible and SFG light allows to determine the molecular orientation (tilt angle) of interface molecules but the analysis of the measured  Thus, iR-value can also be determined. As the ratio of R-value increases  were also measured Fig. . The SSP, and W) . The pea11 were a−4 mbar. This agrees with previous results of CO on smooth Pt(111) , molecular hyperpolarizability tensor (βccc) and tensor ratio (R = βaac/βccc = βbbc/βccc). All possible changes of the influence factors were considered for CO adsorption on Pt and Pd surfaces, except assuming identical Ns. Thus, the conflicting results of experiments [Ns, implies that the Ns of CO on the Pd surface should be much smaller than that on the Pt surface.According to SFG theory, the factors influencing the SFG intensity of molecules adsorbing on different surfaces under the same experimental conditions (mainly referring to incidence angles of IR and visible beams), include the effective surface number density  of CO molecules is identical on different single crystal surfaces (based on the result of R = 0.49 and assumed θ = 0°) for CO on Pt, the theoretical value of Assuming that the molecular hyperpolarizability ratio (R = 0.49) by assuming perpendicular adsorption of CO (tilt angle of 0°). Pressure-dependent SFG spectra on Pt(111) (10−4 to 36 mbar) did not indicate any orientation change of adsorbed CO. Modeling the expected SFG ratio indicated a strong dependence on the experimental configuration, especially on the incidence angle of the visible beam.Polarization-dependent sum frequency generation (SFG) vibrational spectroscopy is a useful method, providing interface-specific spectra of adsorbed molecules, even at elevated gas pressure. For CO overlayers on Pt(111) and Pd(111) single crystal surfaces at room temperature, different polarization combinations (SSP and PPP) of the visible and SFG light were utilized to determine the molecular orientation (tilt angle) of CO. However, since the hyperpolarizability ratio −6 to 250 mbar but only PPP and no SSP spectra could be acquired. Modeling the absolute PPP and SSP spectral intensities on Pt and Pd, as well as the expected ratios, explained the absence of SSP signals on Pd. Care must apparently be taken even for the orientation analysis of seemingly simple adsorbate–substrate systems, with the interface model not only including refractive indices, but also the experimental configuration (incidence angles) and surface coverages.Room temperature CO adsorption on Pd(111) was examined in the pressure range of 10