Proposal for All-Electrical Skyrmion Detection in van der Waals Tunnel Junctions.

A major challenge for magnetic skyrmions in atomically thin van der Waals (vdW) materials is reliable skyrmion detection. Here, based on rigorous first-principles calculations, we show that all-electrical skyrmion detection is feasible in two-dimensional vdW magnets via scanning tunneling microscopy (STM) and in planar tunnel junctions. We use the nonequilibrium Green's function method for quantum transport in planar junctions, including self-energy due to electrodes and working conditions, going beyond the standard Tersoff-Hamann approximation. We obtain a very large tunneling anisotropic magnetoresistance (TAMR) around the Fermi energy for a graphite/Fe3GeTe2/germanene/graphite vdW tunnel junction. For atomic-scale skyrmions, the noncollinear magnetoresistance (NCMR) reaches giant values. We trace the origin of the NCMR to spin mixing between spin-up and -down states of pz and dz2 character at the surface atoms. Both TAMR and NCMR are drastically enhanced in tunnel junctions with respect to STM geometry due to orbital symmetry matching at the interface.

Cervical microendoscopic laminoplasty-induced clinical resolution of disc herniation in patients with single- to three-level myelopathy.

This study aimed to explore the effects on resorption of cervical disc herniation (CDH) and clinical outcomes of surgery. Cervical microendoscopic laminoplasty (CMEL), which is commonly preferable to anterior corpectomy and fusion, was applied to patients with 1- to 3-level degenerative cervical myelopathy (DCM). DCM patients with 1-3 levels DCM underwent either conservation treatment or CMEL. In conservation-treated patients (53 cases), CDH volume remained unchanged with no improvement in JOA and VAS scores. Conversely, 63 patients with 1-3 levels DCM were prospectively enrolled and exhibited a profound decrease in CDH volume: 89.1% of CDHs (123/138) regressed over 10%, 64.5% of CDHs (89/138) regressed over 25%, while 27.5% and 6.5% of CDHs (38/138 and 9/138) largely regressed over 50% and 75%, respectively. Meanwhile, the JOA and VAS scores were improved in different ways. Intriguingly, CDH volume changes correlated significantly with elevations in JOA scores, indicating an association of clinical CDH resolution with neurological recovery. We showed that CMEL induced clinically related diminishment of CDH and alleviation of clinical symptoms in patients with 1- to 3-level myelopathy and that it could help avoid anterior dissection of the disc to some extent.

Spinterface Effects in Hybrid La0.7Sr0.3MnO3/SrTiO3/C60/Co Magnetic Tunnel Junctions.

Orbital hybridization at the Co/C60 interface been has proved to strongly enhance the magnetic anisotropy of the cobalt layer, promoting such hybrid systems as appealing components for sensing and memory devices. Correspondingly, the same hybridization induces substantial variations in the ability of the Co/C60 interface to support spin-polarized currents and can bring out a spin-filtering effect. The knowledge of the effects at both sides allows for a better and more complete understanding of interfacial physics. In this paper we investigate the Co/C60 bilayer in the role of a spin-polarized electrode in the La0.7Sr0.3MnO3/SrTiO3/C60/Co configuration, thus substituting the bare Co electrode in the well-known La0.7Sr0.3MnO3/SrTiO3/Co magnetic tunnel junction. The study revealed that the spin polarization (SP) of the tunneling currents escaping from the Co/C60 electrode is generally negative: i.e., inverted with respect to the expected SP of the Co electrode. The observed sign of the spin polarization was confirmed via DFT calculations by considering the hybridization between cobalt and molecular orbitals.

Strain-Driven Zero-Field Near-10 nm Skyrmions in Two-Dimensional van der Waals Heterostructures.

Magnetic skyrmions─localized chiral spin structures─show great promise for spintronic applications. The recent discovery of two-dimensional (2D) magnets opened new opportunities for topological spin structures in atomically thin van der Waals (vdW) materials. Despite recent progress in stabilizing metastable skyrmions in 2D magnets, their lifetime, essential for applications, has not been explored yet. Here, using first-principles calculations and atomistic spin simulations, we predict that compressive strain leads to stabilizing zero-field skyrmions with diameters close to 10 nm in a Fe3GeTe2/germanene vdW heterostructure. The origin of these unique skyrmions is attributed to the high tunability of Dzyaloshinskii-Moriya interaction and magnetocrystalline anisotropy energy by strain, which generally holds for Fe3GeTe2 heterostructures with buckled substrates. Furthermore, we calculate the energy barriers protecting skyrmions against annihilation and their lifetimes using transition-state theory. We show that nanoscale skyrmions in strained Fe3GeTe2/germanene can be stable for hours at temperatures up to 20 K.

Sodium Butyrate Attenuates Diabetic Kidney Disease Partially via Histone Butyrylation Modification.

Inflammation and fibrosis are the important pathophysiologic processes in diabetic kidney disease (DKD), which is induced by epigenetics, especially histone posttranslational modification (HPTMs). Recent reports highlighted that butyrate, one of the short-chain fatty acids (SCFAs) primarily originated from the fermentation of dietary fiber in the gut, attenuates inflammation and fibrosis in the prevention and treatment of DKD; however, the molecular mechanisms are still unclear. Histone lysine butyrylation (Kbu), a novel histone modification marker induced by butyrate, has been found to be involved in the regulation of pathophysiological processes. To reveal the mechanisms of butyrate-induced histone (Kbu), in the prevention and treatment of DKD, both DKD models in vivo and in vitro were treated with sodium butyrate (NaB). Our results confirmed that exogenous NaB improved the disorder of glucose and lipid metabolism, prevented proteinuria and renal failure, and inhibited renal inflammation and fibrosis. Meanwhile, NaB also induced histone Kbu and H3K9 butyrylation (H3K9bu) in vivo and in vitro; however, inhibition of histone Kbu with the histone modification enzyme p300 inhibitor A485 reversed the anti-inflammatory and anti-fibrosis effects of NaB. In conclusion, our data reveal that NaB antagonizes renal inflammatory and fibrosis injury and attenuates DKD possibly via histone Kbu, suggesting that butyrate-induced histone Kbu or H3K9bu may be an important molecular mechanism in the pathogenesis and treatment of DKD.

Negative Differential Resistance in Spin-Crossover Molecular Devices.

We demonstrate, based on low-temperature scanning tunneling microscopy (STM) and spectroscopy, a pronounced negative differential resistance (NDR) in spin-crossover (SCO) molecular devices, where a FeII SCO molecule is deposited on surfaces. The STM measurements reveal that the NDR is robust with respect to substrate materials, temperature, and the number of SCO layers. This indicates that the NDR is intrinsically related to the electronic structure of the SCO molecule. Experimental results are supported by density functional theory (DFT) with nonequilibrium Green's function (NEGF) calculations and a generic theoretical model. While the DFT+NEGF calculations reproduce NDR for a special atomically sharp STM tip, the effect is attributed to the energy-dependent tip density of states rather than the molecule itself. We, therefore, propose a Coulomb blockade model involving three molecular orbitals with very different spatial localization as suggested by the molecular electronic structure.

Proposal for All-Electrical Spin Manipulation and Detection for a Single Molecule on Boron-Substituted Graphene.

All-electrical writing and reading of spin states attract considerable attention for their promising applications in energy-efficient spintronics devices. Here we show, based on rigorous first-principles calculations, that the spin properties can be manipulated and detected in molecular spinterfaces, where an iron tetraphenyl porphyrin (FeTPP) molecule is deposited on boron-substituted graphene (BG). Notably, a reversible spin switching between the S=1 and S=3/2 states is achieved by a gate electrode. We can trace the origin to a strong hybridization between the Fe-d_{z^{2}} and B-p_{z} orbitals. Combining density functional theory with nonequilibrium Green's function formalism, we propose an experimentally feasible three-terminal setup to probe the spin state. Furthermore, we show how the in-plane quantum transport for the BG, which is non-spin polarized, can be modified by FeTPP, yielding a significant transport spin polarization near the Fermi energy (>10% for typical coverage). Our work paves the way to realize all-electrical spintronics devices using molecular spinterfaces.

A New Automated AI-Assisted System to Assess Cervical Disc Herniation.

STUDY DESIGN: An algorithm was developed with MATLAB platform to automatically quantify the volume of cervical disc herniation (CDH) based on the sagittal magnetic resonance images. This automated program was used for CDH data set, and then compared with manual measurement results confirming its reliability. OBJECTIVE: The aim was to develop a new software for automated CDH volume measurement. SUMMARY OF BACKGROUND DATA: CDH compresses the spinal cord, regarding as the leading cause of cervical myelopathy. However, the CDH volume, of great value to clinical symptoms, can be only manually measured with no-excellent but acceptable interobserver reliability. This was due to the manual error of outlining CDH area and inclusion of structure posterior vertebra. No studies has proposed such an automated algorithm of CDH volume quantification which is standardised to quantify the accurate volume of CDH thus helping doctors easily evaluate CDH progressing. METHODS: The algorithm of CDH volume measurement was proposed. This program was then tested for 490 CDHs data set, from 185 patients with two repeated magnetic resonance imaging detections. Three individual observers manually measured the volumes of these CDHs, to justify the accuracy of this software. CDH volume was either in the classic way or the revised way excluding the influence of structure posterior vertebra. RESULTS: The automated software was successfully developed on MATLAB platform, with no difference found with manual measurements (average level) in CDH volume measurement. The change ratios in CDH volumes were profoundly consistent with manual observation, showing the error of 5.8% in median. The revised method elevated the absolute value of ratio by amplifying the percentage change. CONCLUSION: Our developed automated volumetry system was an standardized and accurate way, with selective removal module of structure posterior vertebra, replaceable for manual volume measurement of CDH, which was useful for spinal surgeons diagnosing and treating CDH disease.

Mesenchymal Stem Cell Derived Exosomes Suppress Neuronal Cell Ferroptosis Via lncGm36569/miR-5627-5p/FSP1 Axis in Acute Spinal Cord Injury.

Exosomes derived from mesenchymal stem cells (MSCs) have been considered as an alternative for cell therapy of acute spinal cord injury (ASCI). However, the underlying mechanism remains unclear. Here, ASCI mouse model and hypoxic cell model were established to evaluate the effects of MSCs and MSCs-derived exosomes (MSCs-exo). The results showed that both MSCs and MSCs-exo inhibited the production of ROS and ferrous iron, upregulated the expression of ferroptosis suppressor FSP1, and enhanced repair of neurological function in the ASCI mice. Besides, MSCs and MSCs-exo attenuated hypoxia-induced neuronal cell ferroptosis and increased cell proliferation. Further study demonstrated that lncGm36569 was enriched in the MSCs-exo. Through bioinformatics analysis and luciferase assay, we confirmed that lncGm36569 acted as a competitive RNA of miR-5627-5p to induce FSP1 upregulation. Furthermore, overexpression of miR-5627-5p reversed the therapeutic effects of lncGm36569 on neuronal cell ferroptosis. In conclusion, MSCs-exosomes lncGm36569 inhibited neuronal cell ferroptosis through miR-5627-5p/FSP1 axis, thereby attenuating neuronal dysfunction.

Structural Asymmetry of Metallic Single-Atom Contacts Detected by Current-Voltage Characteristics.

The complex behavior of the simplest atomic-scale conductors indicates that the electrode structure itself is significant in the design of future nanoscale devices. In this study, the structural asymmetry of metallic atomic contacts formed between two macroscopic Au electrodes at room temperature was investigated. Characteristic signatures of the structural asymmetries were detected by fast current-voltage (I-V) measurements with a time resolution of approximately 100 µs. Statistical analysis of more than 300,000 I-V curves obtained from more than 1000 contact-stretching processes demonstrates that the current rectification properties are correlated with the conductance of the nanocontacts. A substantial suppression of the variation in current rectification was observed for the atomic contacts with integer multiples of the conductance quantum. Statistical analysis of the time-resolved I-V curves revealed that the current rectification variations increased significantly from 500 µs onward before the breakage of the atomic contacts. Ab initio atomistic simulations of the stretching processes and corresponding I-V characteristics confirmed the magnitude of the rectification and related it to the structural asymmetries in the breakdown process of the junctions. Overall, we provide a better understanding of the interplay between geometric and electronic structures at atomically defined metal-metal interfaces by probing charge transport properties in extremely sensitive nanocontacts.

Volumetric Changes in Cervical Disc Herniation: Comparison of Cervical Expansive Open-door Laminoplasty and Cervical Microendoscopic Laminoplasty.

STUDY DESIGN: Retrospective study on 185 patients with 490 cervical disc herniation (CDH). OBJECTIVE: The aim of this study was to compare the changes in volumes of CDH in patients with degenerative cervical myelopathy (DCM) surgically treated by expansive open-door laminoplasty (EOLP) or cervical microendoscopic laminoplasty (CMEL). SUMMARY OF BACKGROUND DATA: Spontaneous resorption of CDH was shown in patients with DCM after conservation treatment, but very few in surgically treated patients. Our previous study identified the clinical efficiency of CMEL to treat DCM but how CDH sized postoperatively, as well as comparing to EOLP, was unknown. METHODS: Consecutive patients with DCM from December 2015 to December 2019, who underwent MRI evaluation, receiving CMEL or EOLP, and repeat MRI in follow-up were included. The volume of CDH were monitored using the picture archiving and communication system, further calculating the incidence of CDH with volume regression and the percentage changes of CDH volume. The correlations of possible determines with CDH volume changes were analyzed by Spearman rank correlation coefficient. RESULTS: A total of 89 patients (215 CDHs, EOLP-group) and 96 patients (275 CDHs, CMEL-group) was surveyed, respectively. Resultantly, volume of CDH was decreased postoperatively in both EOLP and CMEL cases. But this CDH volume regression was more profound in CMEL groups (incidence of 81.2% from 223/275, median volume change ratio of -26.7%, occurring from 1 month after CMEL), statistically different from EOLP group (50.2% from 108/215, median volume change ratio of -5.4%, none-appearance within 1 month). Patients information as sex, age, and follow-up time, not CDH significant, was significantly correlated with CDH volume changes. CONCLUSION: Patients who underwent CMEL developed a postoperative reduction of CDH volume, with more popularity, greater degree and earlier-staged than EOLP-patients. Young females with longer follow-up time were more likely occur.Level of Evidence: 4.

Tuning magnetism at the two-dimensional limit: a theoretical perspective.

The discovery of two-dimensional (2D) magnetic materials provides an ideal testbed for manipulating the magnetic properties at the atomically thin and 2D limit. This review gives recent progress in the emergent 2D magnets and heterostructures, focusing on the theory side. We summarize different theoretical models, ranging from the atomic to micrometer-scale, used to describe magnetic orders. Then, the current strategies for tuning magnetism in 2D materials are further discussed, such as electric field, magnetic field, strain, optics, chemical functionalization, and spin-orbit engineering. Finally, we conclude with the future challenges and opportunities for 2D magnetism.

Robust Giant Magnetoresistance in 2D Van der Waals Molecular Magnetic Tunnel Junctions.

The spin transport across a zero-dimensional (0D) single-molecule sandwiched by two-dimensional (2D) van der Waals (vdW) ferromagnetic electrodes may open vast opportunities to create novel mixed-dimensional spintronics devices. However, this remains unexplored yet. Inspired by the recent discovery of 2D intrinsic ferromagnets Fe3GeTe2, using first-principles spin transport calculations, we show that single-molecule junctions based on Fe3GeTe2 can yield perfect spin filtering and a significant magnetoresistance (MR) of up to ∼6075%. This remarkable MR is more than 2 orders of magnitude higher than the MR obtained for the corresponding junctions with conventional ferromagnetic metals (e.g., Ni, Fe, and Co). We demonstrate the results of two representative examples that are feasible in the experiments: (i) A benzene or (ii) bezenedithiol (BDT) connected either through a scanning tunneling microscope or break-junction setups. We find that the conductance of BDT junctions is more than 10 times larger than that of the benzene junction due to a much stronger hybridization effect at the molecule-metal interfaces. The key mechanism of the perfect spin filtering and large MR in single-molecule junctions is mainly determined by the intrinsic properties of Fe3GeTe2 electrodes, while the actual conductance is determined by the hybridization strength of the majority spin channel at the molecule-metal interfaces. It is also predicted that the perfect spin filtering and the remarkably huge MR are highly insensitive to structural variations, interface defects, and stacking orders of the electrodes. Our results provide important insights for expanding molecular spintronics platforms from conventional ferromagnetic metals to new 2D vdw magnets.

Punicalagin attenuates osteoarthritis progression via regulating Foxo1/Prg4/HIF3α axis.

BACKGROUND: Punicalagin (PUN) is a common anti-inflammatory polyphenol. However, the function and mechanism of PUN in osteoarthritis remains unknown. METHODS: Chondrocytes were isolated from rats, and confirmed by toluidine blue staining and immunofluorescence. Chondrocytes were challenged by lipopolysaccharide (LPS), and rat osteoarthritis model was established by Hulth method. The secretion of inflammatory factors, cell viability and apoptosis were tested via enzyme linked immunosorbent assay (ELISA), MTT and flow cytometry. The levels of forkhead box O1 (Foxo1), proteoglycan 4 (Prg4), hypoxia-inducible factor-3α (HIF3α), autophagy-related genes or extracellular matrix (ECM)-related proteins were examined via quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blot or immunohistochemistry. The cartilage tissue damage was assessed via hematoxylin-eosin (HE) staining, toluidine blue staining and terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick and labeling (TUNEL) staining. RESULTS: LPS triggered inflammatory injury in chondrocytes. PUN promoted autophagy to mitigate LPS-induced inflammatory injury. Foxo1 silence attenuated the effect of PUN on LPS-mediated autophagy inhibition and inflammatory injury. Promotion of Prg4/HIF3α axis abolished the influence of Foxo1 knockdown on LPS-mediated chondrocytes injury. PUN mitigated the inflammatory injury in rat osteoarthritis model by promoting autophagy and inhibiting inflammation and ECM degradation via Foxo1/Prg4/HIF3α axis. CONCLUSION: PUN attenuates LPS-induced chondrocyte injury and osteoarthritis progression by regulating Foxo1/Prg4/HIF3α axis.

LncRNA MIAT activates vascular endothelial growth factor A through RAD21 to promote nerve injury repair in acute spinal cord injury.

BACKGROUND: The main pathological feature of acute spinal cord injury (ASCI) is neuronal apoptosis and Long non-coding RNA (lncRNA) myocardial infarction-related transcript (MIAT) is involved in the regulation of neuronal apoptosis. This study aimed to investigate the role and potential mechanism of LncRNA MIAT in neuronal apoptosis induced by ASCI. METHODS: After Lenti-MIAT lentivirus was microinjected into ASCI rats, Basso, Beattie and Bresnahan Score, Hematoxylin-eosin staining, TUNEL staining, immunohistochemical, immunofluorescence, quantitative real-time PCR and Western blot were used to observe the effect of LncRNA MIAT on the nerve function of ASCI rats. MTT and flow cytometry assays were used to identify the in vitro function of LncRNA MIAT. RNA immunoprecipitation, RNA pull-down, Cycloheximide chase and Chromatin immunoprecipitation combined with qPCR experiments were used to study the mechanism. RESULTS: The overexpression of LncRNA MIAT was conducive to the recovery of motor function in ASCI rats and repressed neuronal cell apoptosis and increased neuronal cell viability. Furthermore, the overexpression of LncRNA MIAT in PC12 cells upregulated RAD21 expression by repressing RAD21 protein degradation and further promoted VEGFA transcription to inhibit neuronal cell apoptosis, ultimately improved ASCI. CONCLUSION: Our data indicated that the overexpression of LncRNA MIAT activated VEGFA through RAD21 to inhibit neuronal cell apoptosis in ASCI.

Primary Cilia as a Biomarker in Mesenchymal Stem Cells Senescence: Influencing Osteoblastic Differentiation Potency Associated with Hedgehog Signaling Regulation.

Bone tissue engineering-based therapy for bone lesions requires the expansion of seeding cells, such as autologous mesenchymal stem cells (MSCs). A major obstacle to this process is the loss of the phenotype and differentiation capacity of MSCs subjected to passage. Recent studies have suggested that primary cilia, primordial organelles that transduce multiple signals, particularly hedgehog signals, play a role in senescence. Therefore, we explored the relationships among senescence, primary cilia, and hedgehog signaling in MSCs. Ageing of MSCs by expansion in vitro was accompanied by increased cell doubling time. The osteogenic capacity of aged MSCs at passage 4 was compromised compared to that of primary cells. P4 MSCs exhibited reductions in the frequency and length of primary cilia associated with decreased intensity of Arl13b staining on cilia. Senescence also resulted in downregulation of the expression of hedgehog components and CDKN2A. Suppression of ciliogenesis reduced the gene expression of both Gli1, a key molecule in the hedgehog signaling pathway and ALP, a marker of osteoblastic differentiation. This study demonstrated that the senescence of MSCs induced the loss of osteoblastic differentiation potency and inactivated hedgehog signaling associated with attenuated ciliogenesis, indicating that primary cilia play a mediating role in and are biomarkers of MSC senescence; thus, future antisenescence strategies involving manipulation of primary cilia could be developed.

Anagliptin stimulates osteoblastic cell differentiation and mineralization.

Osteoporosis is a common debilitating bone disease characterized by loss of bone mass and degradation of the bone architecture, which is primarily driven by dysregulated differentiation of mesenchymal stem cells into bone-producing osteoblasts. Osteoblasts contribute to bone formation by secreting various proteins that guide the deposition of bone extracellular matrix, such as alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). The Wnt/ß-catenin pathway is widely recognized as a regulator of bone mass and is required to maintain bone homeostasis. Hormones have long been recognized as playing a key role in bone metabolism, and in recent years, growing evidence has shown that diabetes is a risk factor for osteoporosis. In the present study, we investigated the effects of the antidiabetic drug anagliptin on the differentiation and mineralization of osteoblasts induced by osteogenic medium. Anagliptin promotes insulin production via inhibition of dipeptidyl peptidase IV (DPP-4), an enzyme that targets the incretin hormone glucagon-like peptide 1 (GLP-1) for degradation. Our findings show that anagliptin significantly increases the differentiation of MSCs into osteoblasts via activation of RUNX2. Anagliptin significantly increased matrix deposition and mineralization by osteoblasts, as evidenced by elevated levels of ALP, OCN, OPN, and BMP-2. We further demonstrate that anagliptin activates the canonical and noncannonical Wnt signaling pathways and that silencing of Wnt/ß-catenin signaling completely abolished the effects of anagliptin. Thus, anagliptin might be a safe, effective therapy for type II diabetes that might show promise as a therapy against osteoporosis.

Electric-field control of single-molecule tautomerization.

The electric field is an important parameter to vary in a single-molecule experiment, because it can directly affect the charge distribution around the molecule. Yet, performing such an experiment with a well-defined electric field for a model chemical reaction at an interface has proven to be extremely difficult. Here, by combining a graphene field-effect transistor and a gate-tunable scanning tunneling microscope (STM), we reveal how this strategy enables the intramolecular H atom transfer of a metal-free macrocycle to be controlled with an external field. Experiments and theory both elucidate how the energetic barrier to tautomerization decreases with increasing electric field. The consistency between the two results demonstrates the potential in using electric fields to engineer molecular switching mechanisms that are ubiquitous in nanoscale electronic devices.

Nonmagnetic single-molecule spin-filter based on quantum interference.

Key spin transport phenomena, including magnetoresistance and spin transfer torque, cannot be activated without spin-polarized currents, in which one electron spin is dominant. At the nanoscale, the relevant length-scale for modern spintronics, spin current generation is rather limited due to unwanted contributions from poorly spin-polarized frontier states in ferromagnetic electrodes, or too short length-scales for efficient spin splitting by spin-orbit interaction and magnetic fields. Here, we show that spin-polarized currents can be generated in silver-vanadocene-silver single molecule junctions without magnetic components or magnetic fields. In some cases, the measured spin currents approach the limit of ideal ballistic spin transport. Comparison between conductance and shot-noise measurements to detailed calculations reveals a mechanism based on spin-dependent quantum interference that yields very efficient spin filtering. Our findings pave the way for nanoscale spintronics based on quantum interference, with the advantages of low sensitivity to decoherence effects and the freedom to use non-magnetic materials.

Tuning spin filtering by anchoring groups in benzene derivative molecular junctions.

One of the important issues of molecular spintronics is the control and manipulation of charge transport and, in particular, its spin polarization through single-molecule junctions. Using ab initio calculations, we explore spin-polarized electron transport across single benzene derivatives attached with six different anchoring groups (S, CH3S, COOH, CNH2NH, NC and NO2) to Ni(1 1 1) electrodes. We find that molecule-electrode coupling, conductance and spin polarization (SP) of electric current can be modified significantly by anchoring groups. In particular, a high spin polarization (SP > 80%) and a giant magnetoresistance (MR > 140%) can be achieved for NO2 terminations and, more interestingly, SP can be further enhanced (up to 90%) by a small voltage. The S and CH3S systems, on the contrary, exhibit rather low SP while intermediate values are found for COOH and CNH2NH groups. The results are analyzed in detail and explained by orbital symmetry arguments, hybridization and spatial localization of frontier molecular orbitals. We hope that our comparative and systematic studies will provide valuable quantitative information for future experimental measurements on that kind of systems and will be useful for designing high-performance spintronics devices.