Group III-V Research Articles

Passivation to Improve the Efficiency and Reliability of III-Nitride Micro-Light-Emitting Diode

Because group III-V and nitride-based micro light-emitting diodes (micro-LEDs) exhibit excellent performance, such as fast response, low power consumption, and thermal stability, they have been widely applied for display and biomedical applications, including optogenetics and multi-site neuron. However, unlike conventional LEDs (> 300 × 300 µm2), micro-LEDs (> 100 × 100 µm2) suffer from severe Shockley Read-Hall (SRH) non-radiative recombination, which is related to sidewall damage introduced by ICP-RIE dry-etching process for LED isolation. As the size of LEDs decreases, such non-radiative recombination phenomenon increases due to the increase in the sidewall surface ratio. Many attempts have been made to improve such defect-related recombination in micro-LEDs. In other words, sidewall passivation using dielectric materials was reported to be effective in alleviation sidewall-related leakage characteristics.In this study, we investigated the electrical and optical properties of GaN-based micro-LEDs (blue) as a function of the number of passivation layers. The passivation layers were deposited using plasma enhanced chemical vapor deposition (PECVD) or/and atomic layer deposition (ALD). It is shown that by employing combined deposition techniques of ALD and PECVD, the optical and electric performance of 10 µm-size micro-LEDs are significantly improved. Compared with the conventional PECVD passivation method, the combined ALD/PECVD passivation showed the smaller ideality factor. For the 10 µm-size micro-LEDs, maximum external quantum efficiency (EQE) was obtained at 35 A/cm2 when the stacked ALD/PECVD passivation layer was used, whereas it was attained at 79 A/cm2 when the PECVD passivation was used. Based on the emission microscopy results, leakage paths were observed. The results show that the use of stacked ALD/PECVD passivation layer could serve as a potentially important process for the fabrication of high-performance micro-LEDs (< 10 × 10 µm2).

(Invited) Heteroepitaxy and Strain Engineering of Germanium-Silicon-Tin Ternary Alloy Semiconductor Thin Films for Energy Band Design

Ternary alloy semiconductor of germanium-silicon-tin (GeSiSn) has attracted for electronic and optoelectronic applications, because this group-IV alloy material provides energy band engineering independent on the lattice constant like group III-V compound semiconductors [1]. In addition, GeSiSn/Ge(Sn) heterostructure realizes type-I energy band alignment with a sufficiently large band offset at both conduction and valence band edges with no or very small lattice mismatching [2,3], and that is preferable for effective carrier confinement for light emitting devices and high mobility transistors. On the other hand, there are still challenges for crystal growth with strain and band engineering of group-IV ternary alloy semiconductor thin films. GeSn is one of promising candidates for optoelectronic applications since it realizes direct transition group-IV semiconductor. GeSn with an in-plane lattice constant larger than Ge is better to enhance the emission efficiency, as the conduction band edge of the gamma-valley lowers than that of the L-valley with large lattice constant and/or in-plane tensile strain. Thus, a buffer layer such as GeSiSn with a lattice constant sufficiently larger than Ge is required to obtain direct transition GeSn thin films, and lattice-constant engineering technology of buffer and GeSn layers should be developed with well-controlled strain relaxation technique. Recently, we explored effective strain engineering technique of GeSiSn ternary alloy epitaxial layers on Ge and Si substrate to obtain much larger in-plane lattice constant. We investigated the effect of low-temperature growth of Ge buffer layer on the strain relaxation of GeSiSn layer [4,5]. Also, we examined the ion implantation technique into substrate to enhance the strain relaxation of GeSiSn epitaxial layers grown on Ge substrate [6]. We can achieve GeSiSn epitaxial layers with the enhancement of strain relaxation and the lattice constant larger than Ge, although the crystalline quality of these epitaxial layers should be still improved. We previously reported that the strain direction as compressive and tensile ones is significantly influence of GeSiSn epitaxial layers [7]. The control of strain structure and its relaxation process is keys to obtain high crystalline quality of GeSiSn and GeSn heteroepitaxial layers for improving the electronic and optoelectronic properties of group-IV heterostructures.

Localized excitons and trions in semiconductor nanosystems

The optical properties of semiconductors and nanoheterostructures based on them are determined near the fundamental absorption edge by electron-hole complexes such as excitons and charged three-particle complexes, aka trions. We present the results of theoretical studies of the structure and binding energies of localized excitons and trions in nanosystems within the variational approach. This approach is applicable to a wide range of semiconducting systems, from quantum wells, wires, and dots based on classical group III-V and II-VI semiconductors to van der Waals heterostructures made of monolayers of transition-metal dichalcogenides. We also discuss many-particle effects in structures containing resident charge carriers. Our treatment of theoretical approaches is accompanied by a discussion of extensive experimental results available in the literature.

Surface photovoltage spectroscopy observes junctions and carrier separation in gallium nitride nanowire arrays for overall water-splitting.

Gallium nitride (GaN) nanowire arrays on silicon are able to drive the overall water-splitting reaction with up to 3.3% solar-to-hydrogen efficiency. Photochemical charge separation is key to the operation of these devices, but details are difficult to observe experimentally because of the number of components and interfaces. Here, we use surface photovoltage spectroscopy to study charge transfer in i-, n-, and p-GaN nanowire arrays on n+-Si wafers in the presence and absence of Rh/Cr2O3 co-catalysts. The effect of the space charge layer and sub-bandgap defects on majority and minority carrier transport can be clearly observed, and estimates of the built-in potential of the junctions can be made. Transient illumination of the p-GaN/n+-Si junction generates up to -1.4 V surface photovoltage by carrier separation along the GaN nanowire axis. This process is central to the overall water-splitting function of the n+-Si/p-GaN/Rh/Cr2O3 nanowire array. These results improve our understanding of photochemical charge transfer and separation in group III-V semiconductor nanostructures for the conversion of solar energy into fuels.

Effect of doping Si on the structural, electronic and optical properties of GaAs nanostructures

In the recent years, with advances in material growth, there has been a considerable interest in the compound semiconductors of group III-V, in particular GaAs. Silicon (Si) is the most suitable substance for the n-gallium arsenide type [1]. In this study, the structural and electron properties of Ga6As4H10 and Ga6As3SiH10 nanocrystals are investigated using the quasi-potential and density functional formulation (DFT) method and with the approximation of LDA in the quantum espresso package. The results of the calculations show that the larger the size of the nanocrystal, the more the decrease of band gap. By replacing the Si atomic impurity by the As atom in the Ga6As4H10 nanocrystal, the energy gap becomes smaller than the non-degenerate state, and the fermi level approaches the edge of the conduction band, in which the Ga6As3SiH10 nanocrystal is a n-type semiconductor. The charge density of the charge around the atoms shows an ion-covalent bond between Si and Ga atoms. In this study, the optical properties of gallium arsenide nanocrystals have been investigated; calculations are performed with single-particle approximation. Gusin software is also used to obtain the optical spectrum of the nanocrystal. The optical spectrometry for gallium arsenide nanocrystals shows the transition to blue.

Analytical modeling and simulation analysis of T-shaped III-V heterojunction vertical T-FET

Abstract In this paper, we have developed a new 2D compact analytical model for surface potential and drain current for III-V group heterojunction of T-shaped Vertical Tunneling FET with inherited properties of dual modulation effect. The device's surface potential is determined from the compact model, which is the most significant consideration for defining device current characteristics. There have been numerous efforts to predict the electrical characteristics of In0.53Ga0.47As as a heterojunction and to discuss the method of device improvement as a function of mole-fraction, gate-drain biasing potential, gate metal work-function. To determine the tunneling width, the dual modulation effect is used to regulate the biasing voltage at both the source and drain junction. A 2-D Poisson equation is solved for the proposed model by using parabolic approximation method with constant electric field which are used to determine the effect of In0.53Ga0.47As as a comparison to Silicon and SiGe material device. Moreover, a new expression of channel surface potential is derived that can forecast the effect of drain and gate biasing. The derived model results validation is carried out by the comparison with the results obtained by TCAD simulation.

(Invited) Theory of Silicon-Based Light Emitting

The indirect band gap preclude the silicon from making light-emitting devices, which is, however, a quest for exploration of large-scale integration of both electronic and photonic devices on a single microchip. Why silicon and germanium are both indirect band gap and most of group III-V and all group II-VI semiconductors are direct band gap is a long standing puzzle. In this talk, I will first present our recently developed unified theory, based on occupied d orbitals in cations, for explaining why diamond, Si, Ge, and Al-containing group III-V semiconductors have indirect band gap, and the remaining group III-V and II-VI semiconductors, except GaP, have direct band gap. This theory also unravels that it is impossible to make allotropes of Si and compounds consisting by Si mixed together with other elements high efficient direct bandgap light emitting. Interface and quantum confinement in low-dimensional Si nanostructures are two knobs to relax the momentum conservation law of optical transition. Our theory confirms that the light emission efficiency of Si quantum dots increases exponentially as reducing dot size, but its highest reachable efficiently is still two orders of magnitude smaller than that of direct bandgap InP and GaAs. Fortunately, we discovered that Si/Ge magic sequence superlattices exhibit orders more efficient at emission light than their existing counterpart records and approach more than 10% brightness of real direct gap materials, such as GaAs. Furthermore, regarding the direct bandgap is only 140 meV above the indirect bandgap in Germanium (Ge), it is well established that a tiny (1-2%) extensile strain could render an indirect-to-direct bandgap transition and makes it direct bandgap. However, there is no feasible way to create such extensive strain on Ge since the lattice parameter of Ge is even 4.3% larger than Si. We propose insert external atoms into interstitial sites of Ge, which grows on Si substrate through SiGe buffer layer, to induce an effective tensile uniaxial strain on Ge, a new pathway toward direct band gap Ge. Because our proposed scheme is highly compatible with CMOS fabrication process, our presented new pathway would be a solution for on-chip lasers.

(Invited) Theory of Silicon-Based Light Emitting

Why silicon and germanium are both indirect band gap and most of group III-V and all group II-VI semiconductors are direct band gap is a long standing puzzle. In this talk, I will first present our recently developed unified theory to explain why diamond, Si, Ge, and Al-containing group III-V semiconductors have indirect band gap, and the remaining group III-V and II-VI semiconductors, except GaP, have direct band gap. We excluded Si QDs as a candidate for on-chip lasers. We also discovered that Si/Ge magic sequence superlattices exhibit orders more efficient at emission light than their existing counterpart records and approach more than 10% brightness of real direct gap materials, such as GaAs. We further propose to insert external atoms into interstitial sites of Ge to induce an effective tensile uniaxial strain on Ge toward direct band gap Ge. This scheme is highly compatible with CMOS fabrication process.

Erlotinib enhanced chemoradiotherapy sensitivity via inhibiting DNA damage repair in nasopharyngeal carcinoma CNE2 cells.

Nasopharyngeal carcinoma (NPC), arising from nasopharynx epithelium, is a rare type of malignant carcinoma that has a specific geographical distribution and a high risk of distant metastases. For most of the diagnosed NPC patients, the total survival rate decreased significantly due to the high local recurrence rate and metastasis rate. Concurrent chemoradiotherapy (CCRT), as routine therapy strategy of NPC, usually accompanies with high-dosage cytotoxic agents and serious toxic side reaction. Therefore, there is an urgent need for update the existing therapy strategies. In this study, we sought to investigate the effects of a combined therapy strategy, erlotinib combined with cisplatin and radiotherapy, on biological characteristics of NPC CNE2 cells and the potential reasons. CNE2 cells in logarithmic phase seeding in 96-well plates received concentration gradients of erlotinib (at 0, 10, 20, 40, 80, 160, 320 mmol/L) or cisplatin (at 0, 0.25, 0.5, 1, 2, 4, 8 mg/L), in order to obtain the optimal working concentration of erlotinib and cisplatin via 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Then, cells were divided into control group and four treatment groups (Group I-IV). All treatment groups received irradiation of 4 Gy, moreover, Group II-IV respectively received erlotinib, cisplatin and erlotinib plus cisplatin at optimal working concentration. After 24 and 48 h of irradiation, growth inhibition rate was determined; invasion ability and migration ability was respectively detected by Boyden's chamber assay and cell scratch test; flow cytometry was performed for determining apoptosis rate and cell cycle distribution; the expression levels of epidermal growth factor receptor (EGFR) signal pathway proteins were semi-quantitatively analyzed by Western-blot. Compared with Group I, all the other treatment groups showed better inhibition effect on cell viability, invasion and migration ability and higher apoptosis rate, while Group IV showed the strongest growth inhibition effect and highest apoptosis rate. In addition, EGFR signal pathway proteins of Group IV showed the lowest expression level. In combined therapy with radiotherapy/chemotherapy, erlotinib could enhance radiotherapy/chemotherapy sensitivity, probably because it could suppress DNA damage repair after radiotherapy/chemotherapy, thus weakening radiotherapy/chemotherapy resistance of tumor cells.

Effects of energy band structure on gallium arsenide based MOSFET

This research work is focused on material science and semiconductor engineering. It emphasized on the semiconductor material such as Gallium arsenide (GaAs). The Gallium arsenide semiconductor material was used as a group III-V compound for metal-oxide semiconductor field effect transistor (MOSFET) modeling. The band-gap energy structures were analyzed by using material parameters such as Varshni parameters, temperature and doping concentrations. Then, an electrical characteristic was carried out depending on the current and voltage relationship. The current flowing in the device is associated with a gate voltage applied to the device. From this paper, the analysis of MOSFET modeling was investigated using mathematical equations and MATLAB simulation.

Relative Study on MM-Wave Performance of Group IV-IV and Group III-V Materials Based IMPATT Sources

A comparative study is done on Si, 4H-SiC, Wz-GaN and InP based impact avalanche transit time (IMPATT) diodes operating at 94 GHz. A double-iterative simulation procedure is utilized to investigate the DC and small-signal features of the diodes from which corresponding avalanche response times and transit times are obtained. The studies exhibit that SiC and GaN diodes are potential sources for radiating high power at 94 GHz. It is also observed that SiC and GaN diodes are highly appropriate for mm-wave frequency bands due to shorter values of their avalanche response time. The power output for SiC IMPATT source is noticed as 47.61 W and for GaN IMPATT, the same is seen as 1.96 W; corresponding avalanche response times are found to be 2.42 × 10−15 and 3.45 × 10−16 s respectively.

InP Quantum Dots: Synthesis and Lighting Applications.

InP quantum dots (QDs) are typical III-V group semiconductor nanocrystals that feature large excitonic Bohr radius and high carrier mobility. The merits of InP QDs include large absorption coefficient, broad color tunability, and low toxicity, which render them promising alternatives to classic Cd/Pb-based QDs for applications in practical settings. Over the past two decades, the advances in wet-chemistry methods have enabled the synthesis of small-sized colloidal InP QDs with the assistance of organic ligands. By proper selection of synthetic protocols and precursor materials coupled with surface passivation, the QYs of InP QDs are pushed to near unity with modest color purity. The state-of-the-art InP QDs with appealing optical and electronic properties have excelled in many applications with the potential for commercialization. This work focuses on the recent development of wet-chemistry protocols and various precursor materials for the synthesis and surface modification of InP QDs. Current methods for constructing light-emitting diodes using novel InP-based QDs are also summarized.

InAs/Si Hetero-Junction Channel to Enhance the Performance of DG-TFET with Graphene Nanoribbon: an Analytical Model

In this paper, a new two-dimensional analytical model for our proposed InAs/Si based double-gate dual-metal tunnel field-effect transistor (DG-TFET) with graphene nano-ribbon is presented. Incorporating group III-V material in source – channel junction, which in turn forms heterojunction results better device performance. Moreover, thin graphene nano-ribbon placed over intrinsic channel can tune the energy gap to larger extent, which supports better band-to-band (B2B) tunneling in our model. Direct tunneling model is used for Indium Arsenide (InAs), since it is direct bandgap material. Obtained Vth as 0.19 V, sub-threshold swing (SS) as 20.76 mV/decade and ION/IOFF ratio as 108 for the case of InAs/Si DG-TFET with graphene nano-ribbon shows an improvement of 48%, 36% and 10 decades respectively compared to conventional all-Si DG-TFET. Using 2-D TCAD numerical device simulator the proposed device model is designed and validated well with analytical data.

Zinc-blende group III-V/group IV epitaxy: Importance of the miscut

Here, we clarify the central role of the miscut during group III-V/ group IV crystal growth. We show that the miscut first impacts the initial antiphase domain distribution, with two distinct nucleation-driven and terraces-driven regimes. It is then inferred how the antiphase domain distribution mean phase and mean lateral length are affected by the miscut. An experimental confirmation is given through the comparison of antiphase domain distributions in GaP and GaSb/AlSb samples grown on nominal and vicinal Si substrates. The antiphase domain burying step of GaP/Si samples is then observed at the atomic scale by scanning tunneling microscopy. The steps arising from the miscut allow growth rate imbalance between the two phases of the crystal and the growth conditions can deeply modify the imbalance coefficient, as illustrated with GaAs/Si. We finally explain how a monodomain III-V semiconductor configuration can be achieved even on low miscut substrates.

Periarticular osteophyte formation protects against total knee arthroplasty in rheumatoid arthritis patients with advanced joint damage.

Periarticular osteophyte formation is observed during the repair of damaged joints in rheumatoid arthritis (RA); however, little is known about its clinical and functional roles. This study aimed to determine the influence of periarticular osteophyte formation on the incidence of total knee arthroplasty (TKA) (a surrogate for long-term outcomes of joint destruction) in patients with RA. This retrospective longitudinal study included a total of 130 symptomatic (tender and/or swollen) knee joints in 80 patients starting biologics. Cumulative incidences of TKA were compared according to the presence or absence of osteophyte on plain anteroposterior radiograph (osteophyte (±)) and the extent of advanced joint damage as defined by Larsen's grading system (0-II vs. III-V). Kaplan-Meier estimates showed a significantly lower cumulative incidence of TKA for the osteophyte (+) group (n = 33) compared with the osteophyte (-) group (n = 31) in the Larsen grades III-V group (38 vs. 74% at 10years, P =0.010), whereas no significant difference was observed between the osteophyte (+) (n = 11) and osteophyte (-) (n = 55) groups in the Larsen grades 0-II group (9 vs. 10% at 10years). Multivariate Cox proportional hazards analysis revealed that older age (hazard ratio (HR), 1.04 per 1year; 95% confidence interval (CI), 1.01-1.08) and osteophyte formation (HR, 0.39; 95% CI, 0.19-0.79) independently predicted TKA in the Larsen grades III-V group, whereas none of the assessed variables predicted TKA in the Larsen grades 0-II group. Osteophyte formation reduces the incidence of TKA in patients with RA who have advanced joint damage. Key Points • Older age and Larsen grade were independent predictors of total knee arthroplasty (TKA) in rheumatoid arthritis (RA) patients. • Periarticular osteophyte formation reduced the incidence of TKA in RA patients with Larsen grades III-V.

A first-principles study of hydrogen adsorption on Ni-decorated defective GaN monolayer

We systematically study the geometric stability and hydrogen storage capacity of Ni atom decorated GaN monolayer (GaN-ML) with three types defects (VN, VGa and SW defect) using the first-principles calculations based on density functional theory (DFT-D2 method). For Ni-decorated defective GaN-ML, Ni atom can be stably combined on substrates due to higher binding energy, and the Ni atom can accommodate up to three H2 molecules. The H2 molecules adsorbed on Ni-decorated VGa substrate undergo a weak physical interaction. However, the Ni-decorated VN and SW defect substrates show sensitive to H2 molecules, which can satisfy the requirement for hydrogen storage. The molecular dynamics (MD) simulations show that the maximum of eight H2 molecules are stably adsorbed on the Ni atoms at room temperature with the hydrogen storage capacity of 5.36 wt%, and there is no structural deformation of the VN substrate plane. Therefore, these results indicate that the Ni-decorated defective GaN-ML can be potential candidates for better storage of H2 molecules. Our work can supply some guidance to explore promising novel hydrogen storage materials in energy storage field using group III-V nitrides.

Mid-infrared Polarized Emission from Black Phosphorus Light-Emitting Diodes.

We demonstrate a mid-infrared light-emitting diode based on the 2D semiconductor black phosphorus (BP). The device is composed of a mechanically exfoliated BP/molybdenum disulfide heterojunction. Under forward bias, it emits polarized electroluminescence at λ = 3.68 μm, with room-temperature internal and external quantum efficiencies of ∼1% and ∼0.03%, respectively. In our structure, outcoupling losses are dominated by radiation toward the high refractive index substrate. The ability to tune the bandgap of BP and consequently its emission wavelength with layer number, strain, and electric field make these LEDs particularly attractive for heterointegration into mid-infrared photonic platforms.

Silicon Quantum Dots: Synthesis, Encapsulation, and Application in Light-Emitting Diodes.

Silicon quantum dots (SiQDs) are semiconductor Si nanoparticles ranging from 1 to 10 nm that hold great applicative potential as optoelectronic devices and fluorescent bio-marking agents due to their ability to fluoresce blue and red light. Their biocompatibility compared to conventional toxic Group II-VI and III-V metal-based quantum dots makes their practical utilization even more attractive to prevent environmental pollution and harm to living organisms. This work focuses on their possible use for light-emitting diode (LED) manufacturing. Summarizing the main achievements over the past few years concerning different Si quantum dot synthetic methods, LED formation and characteristics, and strategies for their stabilization by microencapsulation and modification of their surface by specific ligands, this work aims to provide guidance en route to the development of the first stable Si-based light-emitting diodes.

Diagnostic value of combined detection of four-item urinary protein for early hypertensive kidney injury

Objective To investigate the diagnostic value of combined detection of urine α1-microglobulin(α1-mG), N-acetyl-β-D-glucosaminidase (NAG), retinol binding protein (RBP) and β2-microglobulin (β2-mG) for early hypertensive kidney injury. Methods From June 2016 to December 2018, 116 hypertension patients with renal damage (HRD group) and 44 cases with simple hypertension(HBP group) were selected in the Central People′s Hospital of Tengzhou in this study.And 36 cases of healthy people during the same period were selected as the control group.One hundred and sixteen cases of the HRD group were divided into Ⅰ-Ⅱ group (61 cases) and Ⅲ-Ⅴ group (55 cases) according to the classification of chronic kidney disease(CKD). The concentrations of α1-mG, NAG, RBP and β2-mG in urine were detected in patients and healthy people respectively.SPSS 19.0 software was used to perform statistical analysis. Results The concentrations of urine α1-mG, NAG, RBP, β2-mG in the HRD group were (41.77±24.21)mg/L, (22.60±13.24)U/L, (2.86±1.73)mg/L, (1.76±0.95)mg/L, respectively, which in the HBP group were (12.49±8.10)mg/L, (13.45±8.61)U/L, (0.31±0.16)mg/L, (0.38±0.38)mg/L, respectively, which in the control group were (4.37±2.52)mg/L, (6.12±3.57)U/L, (0.29±0.17)mg/L, (0.28±0.15)mg/L, respectively.The concentrations of urine α1-mG, NAG, RBP, β2-mG in the HRD group were significantly higher than those in the HBP group(t=4.07, 4.25, 4.09, 4.03, all P<0.05) and the control group(t=3.15, 4.94, 2.49, 2.61, all P<0.05). The urine levels of α1-mG, NAG, RBP, β2-mG in phase Ⅰ-Ⅱ group were (21.62±13.45)mg/L, (21.96±12.49)U/L, (0.5±0.47)mg/L, (0.93±0.62)mg/L, respectively, which in the phase Ⅲ-Ⅴ group were (64.11±60.12)mg/L, (23.32±14.11)U/L, (5.48±4.77)mg/L, (2.68±2.55)mg/L, respectively.The concentrations of urine α1-mG, NAG, RBP and β2-mG in Ⅰ-Ⅱ group (t=5.08, 4.99, 2.96, 1.66, all P<0.05) and Ⅲ-Ⅴ group (t=3.95, 4.81, 4.33, 3.74, all P<0.05) were significantly higher than those in the control group.The levels of α1-mG, RBP and β2-mG in group Ⅲ-Ⅴ were higher than those in group Ⅰ-Ⅱ(t=5.37, 8.11, 4.52, all P<0.05). The positive detection rates of α1-mG, NAG, RBP, β2-mG and combination test in phase Ⅰ-Ⅱ group were 70.5%, 77.0%, 19.7%, 60.7%, 91.8%, respectively, which in the phase Ⅲ-Ⅴ group were 81.8%, 81.8%, 69.1%, 69.1% and 96.4%, respectively.The positive rate of urine α1-mG, NAG, RBP and β2-mG combination test was significantly higher than that of the single detection (phase Ⅰ-Ⅱ group: χ2=7.71, 3.99, 61.4, 14.65; phase Ⅲ-Ⅴ group: χ2=4.58, 4.58, 12.47, 12.47; all P<0.05). Conclusion Urine α1-mG, NAG, RBP and β2-mG are important biochemical indicators in patients with early hypertensive kidney injury.The combined detection of the four tests has high diagnostic value in the diagnosis of early hypertensive nephropathy. Key words: Hypertension; Urine protein; Early hypertensive kidney injury; α1-microglobulin; N-acetyl-β-D-glucosaminidase; Retinol binding protein; β2-microglobulin; Combined detection

Effect of electromagnetic radiation on redox status, acetylcholine esterase activity and cellular damage contributing to the diminution of the brain working memory in rats

Behavioral impairments are the most pragmatic outcome of long-term mobile uses but the underlying causes are still poorly understood. Therefore, the Aim of the present study to determine the possible mechanism of mobile induced behavioral alterations by observing redox status, cholinesterase activity, cellular, genotoxic damage and cognitive alterations in rat hippocampus. This study was carried out on 24 male Wistar rats, randomly divided into four groups (n = 6 in each group): group I consisted of sham-exposed (control) rats, group II-IV consisted of rats exposed to microwave radiation (900 MHz) at different time duration 1 h, 2 h, and 4 h respectively for 90 days. After 90 days of exposure, rats were assessing learning ability by using T-Maze. A significantly increased level of malondialdehyde (MDA) with concomitantly depleted levels of superoxide dismutase (SOD), catalase (CAT) and redox enzymes (GSH, GPX, GR, GST, G-6PDH) indicated an exposure of mobile emitted EMR induced oxidative stress by the depleted redox status of brain cells. The depletion in the acetylcholinesterase (AChE) level reveals altered neurotransmission in brain cells. Resultant cellular degeneration was also observed in the radiation-exposed hippocampus. Conclusively, the present study revealed that microwave radiation induces oxidative stress, depleted redox status, and causes DNA damage with the subsequent reduction in working memory in a time-dependent manner. This study provides insight over the associative reciprocity between redox status, cellular degeneration and reduced cholinergic activity, which presumably leads to the behavioral alterations following mobile emitted electromagnetic radiation.