Nitrogen Ion Beam Implantation Research Articles

High energy nitrogen ion-beam implantation induced nucleation and crystalline growth in amorphous carbon nitride films

High-energy N+ injection-induced crystallization in amorphous carbon nitride (a-CN) films were observed by injecting different N+ energies. Nano-clusters with sizes of 2–5 nm form during initial N+ implantation, accompanied by the appearance of crystalline particles. Most nanocrystalline grains exhibit the same crystallographic orientation and have lattice parameters consistent with graphite-like carbon nitride (g-C3N4). Raman spectrum and XPS analysis confirm the presence of sp2 hybridized C–N bonds in N+ implanted C–N films. Crystallization behavior and rate depend on N+ energy, and the mechanism and model of N+ irradiation-induced crystallization are discussed. High N+ implantation provides key factors for structural evolution: high bombardment ions and temperatures. At 15 keV, insufficient energy prevents grain crystallization, resulting in local disorder during growth. Increasing N+ energy (60 keV) reduces disorder in the a-matrix, promoting atomic rearrangement and aggregation of sp2 phase. Simultaneously, high energy N+ induces high temperatures, facilitating growth of nc g-C3N4.

Nitrogen ion beam implantation for enhanced lipid accumulation of Scenedesmus obliquus in municipal wastewater

Breeding of high-lipid content microalgae in municipal wastewater is critical for large-scale microalgal biodiesel production. In this study, a strain of biodiesel promising microalga Scenedesmus obliquus with good stain resistance was obtained by N+ ion implantation, which was named as S1-A3. In the selenite enrichment (SE) medium, the lipid content of S1-A3 was up to 46.92%, which was increased by 24.1% than the original strain. Meanwhile, after 7 days of cultivation, the removal rates of TP,TN, NH4+-N and COD in wastewater attained 95.72%, 80.30%, 87.25% and 85.43% by S1-A3, respectively. S1-A3 had a good genetic stability in both municipal wastewater and SE medium, and its lipid production capacity was improved after four successive cultivation in wastewater. RAPD analysis showed that the mutant and the original strain were interspecific variations. Therefore, N+ ion implantation was proved to be an approach that can significantly improve the lipid content and adaptability of Scenedesmus obliquus.

Modification of 40X13 steel at high-intensity nitrogen ion implantation

This paper presents the results of the formation of deep modified layers in 40X13 steel using a high-intensity repetitively pulsed nitrogen ion beam with a current density up to 0.25 A/cm2. An arc generator with a hot cathode provided the DC nitrogen plasma flow. A plasma immersion approach was used for high-frequency, short-pulse very intense nitrogen ion beam formation. A grid hemisphere with radii of 7.5 cm was immersed in the plasma. Negative bias pulses with an amplitude of 1.2 kV, a pulse duration of 4 μs, and a pulse repetition rate of 105 pulses per second were applied to the grid. The substrates were implanted at the temperature of 500 °C and various processing times ranging from 20 to 120 minutes with 1.2 keV nitrogen ions using a very-high current density up to 0.25 A/cm2 ion beams. The work explores the surface morphology, elemental composition, and mechanical properties of deep-layer modified 40X13 steel after low ion energy, very-high-intensity nitrogen ion beam implantation.

Silicon Solar Cells with Embedded Silicon‐on‐Insulation Layer via Nitrogen Ion Beam Implantation

In this research, silicon solar cells with embedded silicon‐on‐insulation layer obtained via nitrogen ion beam implantation are investigated. The embedded layer acts as a minority carrier‐blocking layer for the silicon solar cells, which results in the suppression of carrier recombination from the surface due to the formation of the silicon‐on‐insulation layer. This is achieved by integrating nitrogen ion implantation as a carrier reduction layer, which has a band offset asymmetry with silicon. The implantation is involved with the formation of surface defects by forming amorphous layers on Si surfaces. The electroluminescence images show that defects related to high energy nitrogen ion implantation are involved in the emission mechanism compared to low energy implanted nitrogen ion. From current–voltage analysis, the conversion efficiencies of nitrogen ion implanted cells are found lower than the reference cell, but the cell implanted with low energy nitrogen ion enhances the short circuit current density.

High intensity, low ion energy implantation of nitrogen in AISI 5140 alloy steel

This paper presents the results of the formation of deep modified layers in AISI 5140 alloy steel using a high-intensity repetitively pulsed nitrogen ion beam. An arc generator with a hot cathode provided the DC nitrogen plasma flow. A plasma immersion approach was used for high-frequency, short-pulse very intense nitrogen ion beam formation. A grid hemisphere with radii of 7.5 cm was immersed in the plasma. Negative bias pulses with an amplitude of 1.2 kV, a pulse duration of 4 μs, and a pulse repetition rate of 105 pulses per second were applied to the grid. The substrates were implanted at various temperatures ranging from 450 to 650 °C with 1.2 keV nitrogen ions using a very-high current density up to 0.5 A/cm2 ion beams. The work explores the surface morphology, elemental composition, and mechanical properties of deep-layer modified AISI 5140 alloy steel after 60 min of low ion energy, very-high-intensity nitrogen ion beam implantation.

Fabrication of chemiresistive gas sensors based on multistep reduced graphene oxide for low parts per million monitoring of sulfur dioxide at room temperature

The proposed multistep reduction of graphene oxide includes two-step reduction process. The graphene oxide is reduced by hydrazine hydrate followed by further reduction with low energy nitrogen ion beam implantation technique. From the Raman spectra, reduction of graphene oxide samples has been estimated on the basis of Tuinstra and Koenig relation. FT-IR studies have shown the removal of oxygen functional groups such as epoxy, hydroxyl and carboxylic on reduction. Ion implantation has enhanced electrical conductivity and specific surface area of graphene oxide on reduction. Besides reduction, the second step has modified the surface morphology of the samples making them more appropriate for gas adsorption. The sample with higher implantation dose (1015ions/cm2) exhibits promising potential for room temperature chemiresistive SO2 gas sensor at ppm levels as low as 5ppm with reasonable response, selectivity and stability.

Improvement of Vitamin K2 Production by Escherichia sp. with Nitrogen Ion Beam Implantation Induction

Low-energy ion implantation as a novel mutagen has been increasingly applied in the microbial mutagenesis for its higher mutation frequency and wider mutation spectra. In this work, N+ ion beam implantation was used to enhance Escherichia sp. in vitamin K2 yield. Optimization of process parameters under submerged fermentation was carried out to improve the vitamin K2 yield of mutant FM5-632. The results indicate that an excellent mutant FM5-632 with a yield of 123.2±1.6 μg/L, that is four times that of the original strain, was achieved by eight successive implantations under the conditions of 15 keV and 60×2.6×1013 ions/cm2. A further optimization increased the yield of the mutant by 39.7%, i.e. 172.1±1.2 μg/L which occurred in the mutant cultivated in the optimal fermentation culture medium composed of (per liter): 15.31 g glycerol, 10 g peptone, 2.89 g yeast extract, 5 g K2HPO4, 1 g NaCl, 0.5 g MgSO4·7H2O and 0.04 g cedar wood oil, incubated at 33 °C, pH 7.0 and 180 rpm for 120 h.

Erratum to: Enhancement of butanol tolerance and butanol yield in Clostridium acetobutylicum mutant NT642 obtained by nitrogen ion beam implantation

Erratum to: Enhancement of butanol tolerance and butanol yield in Clostridium acetobutylicum mutant NT642 obtained by nitrogen ion beam implantation

Enhancement of butanol tolerance and butanol yield in Clostridium acetobutylicum mutant NT642 obtained by nitrogen ion beam implantation

As a promising alternative biofuel, biobutanol can be produced through acetone/butanol/ethanol (ABE) fermentation. Currently, ABE fermentation is still a small-scale industry due to its low production and high input cost. Moreover, butanol toxicity to the Clostridium fermentation host limits the accumulation of butanol in the fermentation broth. The wild-type Clostridium acetobutylicum D64 can only produce about 13 g butanol/L and tolerates less than 2% (v/v) butanol. To improve the tolerance of C. acetobutylicum D64 for enhancing the production of butanol, nitrogen ion beam implantation was employed and finally five mutants with enhanced butanol tolerance were obtained. Among these, the most butanol tolerant mutant C. acetobutylicum NT642 can tolerate above 3% (v/v) butanol while the wide-type strain can only withstand 2% (v/v). In batch fermentation, the production of butanol and ABE yield of C. acetobutylicum NT642 was 15.4 g/L and 22.3 g/L, respectively, which were both higher than those of its parental strain and the other mutants using corn or cassava as substrate. Enhancing butanol tolerance is a great precondition for obtaining a hyper-yield producer. Nitrogen ion beam implantation could be a promising biotechnology to improve butanol tolerance and production of the host strain C. acetobutylicum.

Biological effects of low energy nitrogen ion implantation on Jatropha curcas L. seed germination

To explore the biological effects of nitrogen ion beam implantation on dry Jatropha curcas seed, a beam of N+ with energy of 25keV was applied to treat the dry seed at six different doses. N+ beam implantation greatly decreased germination rate and seedling survival rate. The doses within the range of 12×1016 to 15×1016ionscm−2 severely damaged the seeds: total antioxidant capacity (TAC), germination rate, seedling survival rate, reduced ascorbate acid (HAsA) and reduced glutathione (GSH) contents, and most of the tested antioxidases activity (i.e. catalase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD)) reached their lowest levels. At a dose of 18×1016ioncm−2, biological repair took place: moderate increases were found in TAC, germination rate, seedling survival rate, HAsA and GSH contents, and some antioxidant enzyme activities (i.e. CAT, APX, SOD and GPX). The dose of 18×1016ionscm−2 may be the optimum dose for use in dry J. curcas seed mutation breeding. CAT, HAsA and GSH contributed to the increase of TAC, but CAT was the most important. POD performed its important role as seed was severely damaged. The main role of the HAsA–GSH cycle appeared to be for regeneration of HAsA.

Enhancement of Sophorolipid Production of Wickerhamiella domercqiae var. sophorolipid CGMCC 1576 by Low-Energy Ion Beam Implantation

To meet the increasing demands of sophorolipids as biosurfactants and bioactive compounds, it is necessary to obtain higher and more specific sophorolipid-producing strains. One sophorolipid-producing strain, Wickerhamiella domercqiae var. sophorolipid CGMCC 1576 (Y(2A)), was mutated by low-energy nitrogen ion beam implantation. Eighteen mutants produced 20 % more sophorolipids than the wild strain, and one mutant, N3-18, produced the highest yield of sophorolipids, 104 g/l, in a shaking flask, which increased by 84.71 % than the wild strain, and further elevated to 135 g/l in a 5-l bioreactor. High performance liquid chromatography analysis showed that the composition of every sophorolipid mixture from different strains was similar, while the contents of most components from mutants were higher than that from the wild strain. Two mutants, N1-32 and N3-18, produced more acidic sophorolipid components; three lactonic sophorolipid molecules with good anticancer activities were greatly enhanced in several mutants, especially monoacetylated lactonic sophorolipid with a C18 monounsaturated fatty acid, which were enhanced by 153 and 211 % in strains N1-32 and N3-18. Low-energy nitrogen ion beam implantation was efficient for obtaining a variety of high and specific sophorolipid-producing mutants to be applied in food, cosmetic, environmental, and pharmaceutical sectors.

The effect of the nitrogen ion-beam implantation on adhesiveness of the WC-8Co hard alloy

The results of studying the effect of nitrogen ion-beam implantation on the adhesiveness of the WC-8Co hard alloy have been discussed. The indentation of a rotating indenter into a counterbody has been used to measure the adhesion component of the friction coefficient, which has been shown to decrease in the surface modification by the nitrogen ion-beam implantation, especially when contact pressures exceed the counterbody yield strength.

Screening of a L-Lactic Acid Producing Strain of Lactobacillus Casei by Low-Energy Ion Implantation

Low-energy ion implantation is a new mutation source, which has the characteristic of light damage, high mutation rate, and a broad spectrum mutation. In order to obtain industrial strain with high L-(+)-lactic acid yield, the original strain Lactobacillus casei CICC6028 was mutated by nitrogen ion beam implantation. It was found that the original strain had a higher positive mutation rate when the output power was 10keV and the dose of N+ implantation was 50×2.6×1013 ions/cm2. The mutant N-2 was obtained for many times screening and its yield of L-(+)-lactic acid was 136 g/L which was improved by 38.8% compared with the original strain whose yield of L-(+)-lactic acid was 98g/L as the cultivation time was 120h. The initial screening methods were also studied in this work but it was found that the transparent halos method was unavailable, so the initial screening was performed by shake flask fermentation. HPLC chromatogram was used to analyse the purity of L-(+)-lactic acid that was produced by the mutant strain N-2, and the result indicated the main production of N-2 was L-(+)-lactic acid and there was no other acid almost.

Gene chip analysis of the retrotransposons in rice implanted by the N+ ion beam

Abstract In order to learn the retrotransposons expression profiles in rice implanted by low-energy ion beam and the effects on these retrotransposons adjacent genes, we analyzed expression features of the retrotransposons in rice with exposure to the nitrogen ion beam implantation(6×1017 N+/cm2), using the Agilent Rice Oligo Microarray(4×44K)Genome Array. Rice seeds were implanted by the nitrogen ion beam with 40Kev energy in dose 6×1017 N+/cm2. Total RNA, from the seedlings 96 h after the germination, was used to genechip analysis. The vigor index was measured at 10 days after the germination. The results showed that the vigor index increased obviously than control. We also found that there were 43 retrotransposons transcripts detected by the chip, 4 out of these transcripts were up or down-regulated (≥2fold), including the gag, pol, and int. The differentially expressed genes (detected by the same gene chip), in the frame from up 1MB to down 1MB in the chromosomes at the differentially expressed retrotranscription, represented the same up or down regulated case. These findings suggested that the differential expression of retrotransposons in rice were related with the response to N+ ion beam implantation through the regulation of their adjacent genes.

Tuning Carbon-Based Fuel Cell Catalyst Support Structures via Nitrogen Functionalization. I. Investigation of Structural and Compositional Modification of Highly Oriented Pyrolytic Graphite Model Catalyst Supports as a Function of Nitrogen Implantation Dose

Surface modification and doping of graphitic-carbon catalyst support materials in fuel cell systems, particularly via nitrogen functionalization, has been shown to improve catalyst performance and durability through the optimization of catalyst–support interactions. To ascertain the nature of these interactions, Raman and X-ray photoelectron spectroscopy were used to study the structural and chemical modifications that nitrogen ion beam implantation caused to highly oriented pyrolitic graphite (HOPG) model catalyst support systems. Ion implantation doses explored in this work ranged over 2 orders of magnitude from 9.0 × 1014 to 9.6 × 1016 ions cm–2. Low doses of nitrogen result in a large amount of structural damage with little incorporation of nitrogen. However, it was found that with increasing dosage the incremental increase in structural damage was marginal, while the percentage of nitrogen on the HOPG surface continued to increase significantly until both the level of damage and amount of nitrogen in...

Microbial Lipid Production by Co‐Fermentation with Mortierella alpina Obtained by Ion Beam Implantation

AbstractCo‐fermentation of lignocellulose‐based carbohydrates is a potential approach to improve the economics of microbial lipid production. To obtain an industrial strain that metabolizes glucose and xylose with a higher microbial lipid production, the strain Mortierella alpina was mutated by low‐energy ion beam implantation. After nitrogen ion beam implantation, a mutant strain, M. alpina I502‐8 (MAI502‐8), was obtained. MAI502‐8 was an efficient producer of microbial lipid from glucose and xylose (5:3 wt/wt). Moreover, the co‐fermentation conditions were also optimized. Under optimal conditions, the maximum yield of biomass and microbial lipid reached 27.4 and 10.05 g L–1, respectively, which were 2.38‐fold and 1.84‐fold those in the initial media. Of the mixed sugar, 84.33 % was used up during co‐fermentation.

Strain improvement and metabolic flux modeling of wild-type and mutant Alcaligenes sp. NX-3 for synthesis of exopolysaccharide welan gum

Low-energy nitrogen ion beam implantation technique was used for the strain improvement of Alcaligenes sp. NX-3 for the production of exopolysaccharide welan gum. A high welan gum producing mutant, Alcaligenes sp. NX-3-1, was obtained through 20 keV N+ ion beam irradiation. Starting at a concentration of 50 g/L of glucose, mutant NX-3-1 produced 25.0 g/L of welan gum after 66 h of cultivation in a 7.5 L bioreactor, which was 34.4% higher than that produced by the wild-type strain. The results of metabolic flux analysis showed that the glucose-6-phosphate and acetyl coenzyme A nodes were the principle and flexible nodes, respectively. At the glucose-6-phosphate node, the fraction of carbon measured from glucose-6-phosphate to glucose-1-phosphate was enhanced after mutagenesis, which indicated that more flux was used to synthesize welan gum in the mutant. By analyzing the activities of related enzymes in the biosynthetic pathway of sugar nucleotides essential for welan gum production, we found that the specific activities of phosphoglucomutase, UDP-glucose pyrophosphorylase, UDP-glucose dehydrogenase, and dTDP-glucose pyrophosphorylase in the mutant strain were higher than those in the wild-type strain. These improvements in enzyme activities could be due to the affected of ion beam implantation.

Enhancement of wanlongmycin production by nitrogen ion beam implantation

Enhancement of wanlongmycin production by nitrogen ion beam implantation

Enhancement of wanlongmycin production by nitrogen ion beam implantation

In an attempt to obtain an industrial strain with higher yield of wanlongmycin, the wild strain Streptomyces griseovariabilis GAAS2507 was mutated by a novel mutagen, nitrogen ion beam with energy of 20 kilo electron volts (KeV) and dose ranging from 7.80 x 10 14 to 2.86 x 10 15 ions/cm 2 . One mutant strain WN939 was obtained. Its yield of wanlongmycin reached 271.24 µg/mL, which was 82.10% higher than that of the wild strain. The mutant strain WN939 was relatively stable for the production of wanlongmycin through six successive transfers of cultures and a repeat fermentation in a 30 L fermentor. In addition, the mutant strains were investigated and divided into five types by their colony phenotypes and production of wanlongmycin. Among them, three types mutant strains exhibited positive mutation, while the other two types mutant strains exhibited negative mutation.

Breeding of d(–)-Lactic Acid High Producing Strain by Low-energy Ion Implantation and Preliminary Analysis of Related Metabolism

The low-energy nitrogen ion beam implantation technique was used in the breeding of mutant D(-)-lactic-acid-producing strains. The wild strain Sporolactobacillus sp. DX12 was mutated by an N(+) ion beam with energy of 10keV and doses ranging from 0.4 x 10(15) to 6.60 x 10(15) ions/cm(2). Combined with an efficient screening method, an efficient mutant Y2-8 was selected after two times N(+) ion beam implantation. By using the mutant Y2-8, 121.6g/l of D-lactic acid was produced with the molar yields of 162.1% to the glucose. The yield of D-lactic acid by strain Y2-8 was 198.8% higher than the wild strain. Determination of anaerobic metabolism by Biolog MT2 was used to analyze the activities of the concerned enzymes in the lactic acid metabolic pathway. The results showed that the activities of the key enzymes responded on the substrates such as 6-phosphofructokinase, pyruvate kinase, and D-lactate dehydrogenase were considerably higher in the mutants than the wild strain. These might be affected by ion beam implantation.