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Types and Grades of Almen Strips

Almen strips are classified into 3 types: ‘A’, ‘N’, and ‘C’. They differ in their thickness but have the same width and length. The type of strip is usually specified by the part designer.

“A” strips are used for medium intensity applications. “A” strips are predominantly used for shot peening with cast shot or cut wire shot.

“N” strips are used for low intensity applications. “N” strips are used usually for glass bead and ceramic bead peening.

“C” strips are used for high intensity applications.

By Grade

Grade 3 – Bulk (A-3™, N-3™, C-3™)
 Grade 3 strips are guaranteed to meet the requirement of MIL-S-13165 (now AMS-S-13165). Type A-3 strip is guaranteed to meet National Stock Number NSN 6635-00-512-1892. Grade 3 strips are economically priced and bulk packaged.

Grade 2 – Standard (A-2™, N-2™, C-2™)
 Meets AMS-S-13165. Excess oil is removed from the Grade 2 Standard strips. The strip surfaces are then visually inspected for score marks, scratches, nicks, burrs, pits and rust. Strips are certified using a sampling inspection plan for hardness, length, width, thickness, and flatness. A dated certification of compliance is issued, signed and archived. We then package “A” and “N” strips in groups of 50 and “C” strips in groups of 25.

Grade 1 – Premium Grade (A-1™, N-1™, C-1™) 
Meets SAE J442. Electronics Incorporated performs all the inspection and packaging operations listed for Grade 2 strips. Strips are sample inspected for flatness (±.001-inch) on each side. A dated certification of compliance is issued, signed and archived. The Premium Grade 1 strips are identified by batch control number which provides traceability.

Grade 1S – Special Grade (A-1S™, N-1S™)
 Meets SAE AMS 2432B. In addition to requirements for Premium Grade 1, the Grade 1S strips are inspected to ±.0005-inch flatness tolerance of AMS 2432B. A dated certification of compliance is issued, signed and archived.

* AMS-S-13165 has been cancelled with instructions to use AMS 2430. For more information see Almen Strips FAQ.
A-3, A-2, A-1, A-1S, N-3, N-2, N-1, N-1S, C-3, C-2, C-1 are trademarks owned by Electronics Inc.

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In a new report now published on Royal Society Open Science, Mohammed Taha Amen and a team of scientists in bio-nanosystem engineering, chemical engineering and microbiology at the Chonbuk National University of South Korea, and the Zagazig University, Egypt, showed the possibility of using rainwater as a sustainable analyte in an air-cathode microbial fuel cell (MFC). The results showed how the constructs could work within a specific temperature range, under aerobic and anaerobic environments.

The work highlighted the significant influence of the rainwater season under anaerobic conditions, where summer rainwater achieved an open circuit potential (OCP) of 553 ± 2 mV, without the addition of nutrients at ambient temperature. Addition of nutrients further increased the cell voltage. The team obtained the maximum open circuit potential for winter rainwater by exposing the reactor to air (aerobic conditions) at ambient temperature.

The resulting rainwater microbial fuel cell (RMFC) generated a maximum power output of 7 ± 0.1 mWm^-2 at a corresponding current density value of 44 ± 0.7 mAm^-2 at 30 degrees Celsius. The scientists obtained the maximum output power at ambient temperature with summer rainwater. During summer, Lactobacillus spp. formed the dominant electroactive genus, while Staphylococcus spp. dominated the winter rainwater. The cyclic voltammetry analysis confirmed how electrons could be delivered directly from the bacterial biofilm to the anode surface, without any mediators to open a new avenue for sustainable rainwater-based microbial fuel cells (RMFCs).

Converting chemical energy into electricity in a microbial fuel cell (MFC)

A microbial fuel cell system provides a setup for microorganisms to convert chemical energy embedded in some organic compounds to electricity by oxidizing these compounds into ATPs (adenosine triphosphate) through sequential reactions. The MFCs differed from other types of fuel cells since living organisms can act as a catalyst to organize organic materials present at the anode chamber. The process of MFC development provides a clean, reliable and efficient process, without any toxic byproducts. While the energy produced by MFCs is relatively low, it could gain energy from several types of wastes naturally present in diverse environments for direct conversion into electricity. In remote areas, MFCs are therefore considered a convenient power-generating device for wireless sensors. Rainwater contains a variety of microorganisms collected from the atmosphere, with ample evidence for microbial activity in the air. Fresh rainwater samples contain a wide phylogenetic variety including genomic sequences such as Alphaproteobacteria, Actinobacteria, Bacteriodetes and Lentisphaerae. The presence of diverse microorganisms motivated the scientist to study the possibility of generating electricity using rainwater microbial fuel cells (RMFC) due to their ability to metabolize organic and inorganic components. In this work, Amen et al. investigated two different rainwater samples based on sample collecting season to generate electricity through a single chamber air-cathode MFC. The results surprisingly provided a promising power output from a relatively high-quality atmosphere.

The experiments and seasonal effects

The team collected rainwater in April and December for summer and winter rainwater, respectively, and used the samples either without additives or with Nutrient Broth media. Amen et al. next constructed an MFC for function as a single chamber air-cathode made of transparent polyacrylic between the anode and cathode. The team placed a silver/silver chloride (Ag/AgCl) reference electrode in the anode compartment to measure the potential of the electrodes. They assembled the MFC and sterilized it using UV, then tested its performance with pure rainwater as an anolyte (electrolyte on the anode side), alongside rainwater with nutrient broth media. To examine aerobic/anaerobic conditions, the team next provided direct contact of ambient air to the MFCs and in another instance blocked access to oxygen to create anaerobic conditions. Amen et al. expected the types of microorganisms and their quantities in rainwater to vary according to the season. The summer rainwater provided a maximum open circuit potential than in winter at an ambient temperature after 15 days of function. The results indicated how the proposed rainwater microbial fuel cells could create a very acceptable potential regardless of the collecting season, although summer rainwater produced a more favorable anolyte.

Electrochemical characterization and experimental effects in the setup

The team also tested the electrochemical performance of microbial fuel cells using a potentiostat and cyclic voltammetry analysis in a three-electrode setup, where they assigned the anode as a working electrode, the cathode and Ag/AgCl as a counter electrode and reference electrode, respectively. After 22 days of function, the team dismantled the apparatus and cultured the biofilm sampled from both the anode surface and anolyte, in Nutrient agar media. After isolating the bacterial growth, Amen et al. extracted the genomic DNA for analysis. The team found the maintenance of anaerobic conditions in MFCs to be quite difficult in practice and therefore investigated cells under aerobic conditions to determine the successful role of rainwater as an anolyte in the setup for electricity generation. They credited the findings to the fast metabolization of nutrients at 30 degrees Celsius. The output values emphasized the applications of RMFCs (rainwater microbial fuel cells) in summer or winter under the appropriate conditions of interest.

Assessing the reliability of the constructs

The summer rainwater alone (labeled SRMFC-A) produced a maximum voltage output of 553 ± 0.6 mV compared to summer rainwater with nutrients (labeled SRMFC-WN). The setup with summer rainwater alone produced a maximum output by 18 days while those with nutrients in the media achieved a maximum power output in three days. Since the addition of nutrients to a fuel cell in a practical setting is tedious, the results indicated how the setup could be used on its own without nutrients to produce a reasonable voltage for applications in real-time. Additional results with cyclic voltammetry showed how electrons were delivered from the bacterial biofilm to the anode surface via direct contact without mediators. Both winter and summer microbial fuel cells also showed a thick, well-structured electroactive film via scanning electron microscopy, making it possible to transfer electrons to the anode.

Bacterial community analyses and outlook

The scientists examined the microbiological variants to investigate the microbial community in the used rainwater. They noted the presence of synergistic interactions between microorganisms as an important factor to form electroactive biofilms that sustain the bioelectrochemical systems in the long term. While the Lactobacillus spp. formed as the primary electroactive bacteria in the summer microbial fuel cell setup, Staphylococcus spp. were present more dominantly in the winter setup. The proposed microbial fuel cell (MFC) is applicable to regions across the world. in practice the team expect applications of the setup in remote areas where the cell can be filled with rainwater first and left at open circuit mode to form a biofilm at the anode surface and create a stable open circuit potential. In this way, Mohammed Taha Amen and colleagues showed the development of an air-cathode, single-chamber microbial fuel cell that functioned effectively with rainwater as an anolyte. The resulting product is not only useful to power wireless sensors, but can also be effective as a biosensing tool to monitor the microbial community.

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Study question: Does increased daily energy intake lead to menstrual recovery in exercising women with oligomenorrhoea (Oligo) or amenorrhoea (Amen)?

Summary answer: A modest increase in daily energy intake (330 ± 65 kcal/day; 18 ± 4%) is sufficient to induce menstrual recovery in exercising women with Oligo/Amen.

What is known already: Optimal energy availability is critical for normal reproductive function, but the magnitude of increased energy intake necessary for menstrual recovery in exercising women, along with the associated metabolic changes, is not known.

Study design, size, duration: The REFUEL study (trial # NCT00392873) is the first randomised controlled trial to assess the effectiveness of 12 months of increased energy intake on menstrual function in 76 exercising women with menstrual disturbances. Participants were randomised (block method) to increase energy intake 20-40% above baseline energy needs (Oligo/Amen + Cal, n = 40) or maintain energy intake (Oligo/Amen Control, n = 36). The study was performed from 2006 to 2014.

Participants/materials, setting, methods: Participants were Amen and Oligo exercising women (age = 21.0 ± 0.3 years, BMI = 20.8 ± 0.2 kg/m2, body fat = 24.7 ± 0.6%) recruited from two universities. Detailed assessment of menstrual function was performed using logs and measures of daily urinary ovarian steroids. Body composition and metabolic outcomes were assessed every 3 months.

Main results and the role of chance: Using an intent-to-treat analysis, the Oligo/Amen + Cal group was more likely to experience menses during the intervention than the Oligo/Amen Control group (P = 0.002; hazard ratio [CI] = 1.91 [1.27, 2.89]). In the intent-to-treat analysis, the Oligo/Amen + Cal group demonstrated a greater increase in energy intake, body weight, percent body fat and total triiodothyronine (TT3) compared to the Oligo/Amen Control group (P < 0.05). In a subgroup analysis where n = 22 participants were excluded (ambiguous baseline menstrual cycle, insufficient time in intervention for menstrual recovery classification), 64% of the Oligo/Amen + Cal group exhibited improved menstrual function compared with 19% in the Oligo/Amen Control group (χ2, P = 0.001).

Limitations, reasons for caution: While we had a greater than expected dropout rate for the 12-month intervention, it was comparable to other shorter interventions of 3-6 months in duration. Menstrual recovery defined herein does not account for quality of recovery.

Wider implications of the findings: Expanding upon findings in shorter, non-randomised studies, a modest increase in daily energy intake (330 ± 65 kcal/day; 18 ± 4%) is sufficient to induce menstrual recovery in exercising women with Oligo/Amen. Improved metabolism, as demonstrated by a modest increase in body weight (4.9%), percent body fat (13%) and TT3 (16%), was associated with menstrual recovery.

Study funding/competing interest(s): This research was supported by the U.S. Department of Defense: U.S. Army Medical Research and Material Command (Grant PR054531). Additional research assistance provided by the Penn State Clinical Research Center was supported by the National Center for Advancing Translation Sciences, National Institutes of Health, through Grant UL1 TR002014. M.P.O. was supported in part by the Loretta Anne Rogers Chair in Eating Disorders at University of Toronto and University Health Network. All authors report no conflict of interest.

Trial registration number: NCT00392873.

Trial registration date: October 2006.

Date of first patient’s enrolment: September 2006.

Background: National Football League (NFL) players are exposed to multiple head collisions during their careers. Increasing awareness of the adverse long-term effects of repetitive head trauma has raised substantial concern among players, medical professionals, and the general public.

Objective: To determine whether low perfusion in specific brain regions on neuroimaging can accurately separate professional football players from healthy controls.

Method: A cohort of retired and current NFL players (n = 161) were recruited in a longitudinal study starting in 2009 with ongoing interval follow up. A healthy control group (n = 124) was separately recruited for comparison. Assessments included medical examinations, neuropsychological tests, and perfusion neuroimaging with single photon emission computed tomography (SPECT). Perfusion estimates of each scan were quantified using a standard atlas. We hypothesized that hypoperfusion particularly in the orbital frontal, anterior cingulate, anterior temporal, hippocampal, amygdala, insular, caudate, superior/mid occipital, and cerebellar sub-regions alone would reliably separate controls from NFL players. Cerebral perfusion differences were calculated using a one-way ANOVA and diagnostic separation was determined with discriminant and automatic linear regression predictive models.

Results: NFL players showed lower cerebral perfusion on average (p < 0.01) in 36 brain regions. The discriminant analysis subsequently distinguished NFL players from controls with 90% sensitivity, 86% specificity, and 94% accuracy (95% CI 95-99). Automatic linear modeling achieved similar results. Inclusion of age and clinical co-morbidities did not improve diagnostic classification.

Conclusion: Specific brain regions commonly damaged in traumatic brain injury show abnormally low perfusion on SPECT in professional NFL players. These same regions alone can distinguish this group from healthy subjects with high diagnostic accuracy. This study carries implications for the neurological safety of NFL players.