3.1. Polarization curve and extract concentration influence
The plots demonstrate the normal I-V individuality for electro-polishing. Three areas relating to opposing, shining and oxygen gas progression on the surface of anode are known to be dependent upon the employed potential. Primarily, the current linearly intensified from the origination of voltage scan and turn up a plateau. This behavior is directed via the Ohmic endurance in the electrolyte. At elevated voltage, fluctuation is both potential and current are located. After the straight range, the current persists continuous, though the voltage develops. They persisted to increase in potential results in an amplifying in current owing to oxygen progression [ 16].
This province is of wonderful technical significance since electro-polishing may be accomplished via governing voltage in the variety of limiting current plateau. Surface smooth out may be accomplished via managing the anode voltage at limiting current plateau where either a sheet is modelled on the anode surface or distribution of an acceptor to the anode develops rate restraining.
In the case of aluminum electropolishing systems which obey acceptor procedure, the salt sheet did not construct. As an alternative, there is a viscid film near to the anode surface. Aluminum and aluminum compounds have air established oxide layer of formless γ alumina that primarily stiffens on disclosure to the neutral aqueous solution with the crystalline hydrated alumina development [ 17].
The anodic polarization plots for the aluminum anode that are electropolished in 60% H3PO4:40%H2SO4 electrolyte with the addition of plant extract of several concentration (100–1000 ppm) are shown in Fig. 2a-2c). Apparently, a limiting current plateau can be observed in every anodic polarization plot. A noticeable reduction in the limiting current is noticed when the studied apple peel and grape branches extract are included (Table 1&2). This proposes that the aluminum anodic polarization performance is appropriate responsive to tiny concentration of apple peel and grape branches. The monitored reduction in limiting current via the investigated apple peel and grape branches extract addition (Fig. 2a-2c) is faithful with acceptor system. When apple peel and grape branches additional, it is credible that adsorption of such composites on and near the anode surface may lead to regulate ion diffusion procedure in three customs, specifically (i) satisfying up of surface echoing space and glooms (ii) the wobblier stuffing of the adsorbed layer at mountains assists the metal subtraction at an earlier rate than loss from valleys. Hence, surface flattening occurred owing to the crevice’s passivation is further stable, and it retard etching. Summits are as a substitute dissolving more quickly. (iii) By substituting water particles in this section. This procedure may alter the medium dielectric coefficient and reduce the water particles number that are accessible for cations solvating, hence lowering the cations distribution rate as in beyond the anode surface [ 18].
If (IL) blank is the limiting current in the plant extract- free electrolyte and (IL) plant extract in the electrolyte containing plant extract, then IE % may be evaluated from the subsequent equation:
\(IE\%=\frac{{{I}_{L}}_{\left(blank\right)}-{{I}_{L}}_{\left(plant extract\right)}}{{{I}_{L}}_{\left(blank\right)}}\) X100 (2)
The reduction in limiting current is dependent on plant extract concentration and nature.
It is obvious that the retardation effectiveness enhanced by the enhance in plant extract concentration. This performance can be explained based on the effective interaction of the plant extract particle with the Al surface developing. The adsorption scope rises via the enhancement in concentration of plant extract resulting in intensified retardation effectiveness. The dissolution overcoming plant extract capability constituents initiates from the inclination to form each effective or ineffective chemical bonds with Al atoms employing the oxygen electrons lone pair and π electrons in the benzene ring. These organic particles may adsorb on the metal/electrolyte boundary with one or more of the subsequent ways; (i) donor– acceptor connections among the aromatic ring p-electrons and vacant P-orbital of surface aluminum (ii) communication among nonbonding electron pairs of hetero atoms and vacant P-orbital of surface aluminum atoms [ 5, 18]
From the estimated values of retardation effectiveness percentage (IE %) (Table 1–3 and Fig. 4), IE % of each investigated plant extract is concentration dependent.
The percentage retardation effectiveness improves as the plant extract concentration enhances at all concentration range investigated.
the extract retardation order is as results: mixture > apple peel > grape branches extract.
It may be demonstrated from Table 1–3 and Fig. 2a-c that the anodic limiting current reduces while several apple peel and grape branches extract concentration rise at all concentration range considered (100–1000 ppm) and IE% rises as the concentration of all these extract rise; hence, the electropolishing procedure of aluminum is reduced subsequently. This may be ascribed to the subsequent evidence.
Adsorption of these particles on the aluminum anodic surface may create an adsorbed layer at the aluminum anodic surface; that resulting in reduction in the Al3+ ions diffusivity and an rise in the confrontation to the Al3+mass transference rate from anode surface to bulk solution; therefore, the aluminum electro-polishing rate may be reduced. Furthermore, additives adsorption on the aluminum surface depends essentially on their composition.
The apple peels show a remarkable retardation performance in electrolyte solution by decreasing the dissolution rate from 0.542 in blank solution up to 0.052 at 1000 ppm of apple extract (Table 1) that ascribed which apple peels comprise a larger number of composites that comprise several hetero atoms like oxygen and unsaturated π electrons these atoms adsorb onto the metal surface and improve a shielding layer. The GC-MS investigation of apple peels described that the Flavone 1 and Flavone 2 are the major constituent in the peels. These composites may adsorb on metal surface through oxygen atoms lone pair and form protecting layer, additional benefit of these compounds is that aromatic ring may also adsorb physically via Vander Waals forces that giving rise of adherent and insoluble protecting layer then caused sturdy retardation behavior [ 14, 20].
It’s established that the aluminum dissolution rate diminished substantially via strengthen the grape branches extract concentration from 0.542 in electrolyte mixture – grape extract free to its minimum value o.132 at 1000 ppm grape stem extract ( Table 2). The retardation action of grape branches extracts since it comprises a variety of oxygen containing compounds, and unsaturated composites. Those composites comprise unsaturated π electrons and hetero atoms that hold lone pair (electronic density) which cooperate with the aluminum vacant p-orbitals and encourage a protecting film [Al- grape branches] composite on the surface that may separate the aluminum from the acid mixture electrolyte. GC-MS investigation of grape stems extract represents that aldehydes are the main constituent. These compounds may adsorb on the aluminum surface via the oxygen atoms nonbonding pair and stimulate a protecting film to separate the Al from the aggressive species [ 15, 21].
Table 1
limiting current (A)and % retardation effectiveness % IE values for the investigated ethanolic apple peel extracts as a function of concentration at different temperature
Plant extract
|
Conc.(ppm)
|
35oC
|
40 oC
|
45 oC
|
50 oC
|
IL
|
% IE
|
IL
|
% IE
|
IL
|
% IE
|
IL
|
% IE
|
Apple peel
(Malus peel)
|
0.0
|
0.542
|
|
0.581
|
|
0.625
|
|
0.661
|
|
100
|
0.283
|
47.78
|
0.355
|
38.90
|
0.391
|
37.44
|
0.452
|
31.62
|
200
|
0.264
|
51.29
|
0.310
|
46.64
|
0.371
|
40.64
|
0.422
|
36.17
|
300
|
0.245
|
54.80
|
0.284
|
51.12
|
0.352
|
43.68
|
0.394
|
40.39
|
400
|
0.222
|
59.04
|
0.262
|
54.90
|
0.322
|
48.48
|
0.371
|
43.87
|
500
|
0.205
|
62.18
|
0.240
|
58.70
|
0.302
|
51.68
|
0.352
|
46.75
|
600
|
0.184
|
66.05
|
0.220
|
62.13
|
0.282
|
54.88
|
0.333
|
49.62
|
700
|
0.167
|
69.19
|
0.200
|
65.57
|
0.261
|
58.24
|
0.300
|
54.61
|
800
|
0.144
|
73.43
|
0.170
|
70.74
|
0.235
|
62.40
|
0.277
|
58.09
|
900
|
0.120
|
77.86
|
0.150
|
74.18
|
0.200
|
68.00
|
0.250
|
62.18
|
1000
|
0.052
|
90.41
|
0.123
|
78.82
|
0.165
|
73.60
|
0.217
|
67.17
|
Table 2
limiting current (A)and % retardation effectiveness % IE values for the investigated ethanolic grape stem extracts as a function of concentration at different temperature
Plant extract
|
Conc.(ppm)
|
35 oC
|
40 oC
|
45 oC
|
50 oC
|
IL
|
% IE
|
IL
|
% IE
|
IL
|
% IE
|
IL
|
% IE
|
grape stem extracts
|
0.0
|
0.542
|
|
0.581
|
|
0.625
|
|
0.661
|
|
100
|
0.333
|
38.56
|
0.365
|
37.17
|
0.421
|
32.64
|
0.473
|
28.44
|
200
|
0.312
|
42.43
|
0.345
|
40.61
|
0.402
|
35.68
|
0.451
|
31.77
|
300
|
0.285
|
47.41
|
0.322
|
44.58
|
0.381
|
39.04
|
0.426
|
35.55
|
400
|
0.262
|
51.66
|
0.300
|
48.36
|
0.361
|
42.24
|
0.396
|
40.09
|
500
|
0.245
|
54.80
|
0.281
|
51.63
|
0.344
|
44.96
|
0.368
|
44.32
|
600
|
0.224
|
58.67
|
0.262
|
54.90
|
0.322
|
48.48
|
0.355
|
46.26
|
700
|
0.203
|
62.54
|
0.243
|
58.18
|
0.301
|
51.84
|
0.333
|
49.6
|
800
|
0.184
|
66.05
|
0.220
|
62.13
|
0.283
|
54.72
|
0.312
|
52.8
|
900
|
0.160
|
70.50
|
0.200
|
65.57
|
0.262
|
58.08
|
0.294
|
55.52
|
1000
|
0.132
|
75.65
|
0.174
|
70.05
|
0.230
|
63.2
|
0.266
|
59.76
|
Using potential-dynamic trials to investigate the synergistic retardation between apple peel and grape stems, the proportion of the mixture was 1:1, was used. The potential-dynamic polarization plots of Al with apple peel - grape stems extract mixture is demonstrated in Fig. 1c and Table 3. As shown in Table 3 and Fig. 1c, the combination of apple peel and grape stems show a stronger dissolution retardation effect, where the limiting current decreases significantly
Retardation behavior of the mixture is owing to the extract particles at the electrode- electrolyte interface may raise the interfacial viscosity by resulting reduction in the electroactive ions diffusivity. This cause delays the solution flow past the electrode surface and subsequently reduction in the limiting current values.
Moreover, the extraordinary mixture retardation behavior aims compelling bonding of the efficient complexes and aluminum surface due to heteroatoms (O) nonbonding electrons and p- orbital preventing the energetic sites and reducing the dissolution rate. Consequently, bonding among additive particles and aluminum surface happens via participation of the oxygen atoms electrons (OH and CO groups) located in the recognized composites of the ethanolic extract of apple peel and grape branches with vacant Al P-orbital. Mixture particles may absorb on the Al surface based on donor–acceptor collaboration among aromatic rings p-electrons and vacant P-orbital of Al [ 22].
To estimate the nature (additive, synergistic or antagonistic) of the two-extract synergistic contact were when collective influence was > additive influences, however antagonistic interactions were when combined influences were < additive. synergistic effects are the influence when chemical substances or biological structures interact leading to an overall influence that is higher than the sum of individual effects of any of them. Synergistic influences are the merger of an influence of at least two substances making an affect that is more substantial than both might have demonstrated by themselves [ 23].
The synergist parameter could be calculated from the following formula:
$$S=\frac{1-({I}_{A}+{I}_{B})}{1-{I}_{AB}}$$
where IA is the limiting in presence apple peel extract (APE), IB is the limiting in presence of grape branches extract (GSE), IAB is the limiting in presence of the combination of apple peel and grape branches. S > 1 signifies that the mixture system has an noticeable synergistic effect. S ⩽ 1 indicates that the synergy is not substantial or there is an antagonistic effect. The greater the S value, the powerful the synergy among the additives. The estimated synergist parameter of APE / GSE is.
S APE / GBE = 1.64–183), the synergy between APE and GSE is obvious.
Table 3
limiting current (A)and % retardation effectiveness % IE values for the investigated ethanolic apple peel - grape stem extracts mixture as a function of concentration
Conc.(ppm)
|
Apple peel
|
Grape stems
|
Apple peel- Grape stem
|
IL
|
% IE
|
IL
|
% IE
|
IL
|
% IE
|
0.0
|
0.542
|
|
0.542
|
|
0.542
|
|
200
|
0.264
|
51.29
|
0.312
|
42.43
|
0.231
|
57.38
|
400
|
0.222
|
59.04
|
0.262
|
51.66
|
0.201
|
62.91
|
600
|
0.184
|
66.05
|
0.224
|
58.67
|
0.172
|
68.26
|
800
|
0.144
|
73.43
|
0.184
|
66.05
|
0.103
|
80.99
|
1000
|
0.052
|
90.41
|
0.132
|
75.65
|
0.043
|
92.07
|
![](https://myfiles.space/user_files/122228_c8a1650c59388082/122228_custom_files/img1707403932.png)
c. Gas Chromatography–Mass Spectrometry (GC–MS) analysis:
The organic composites are observed in apple peel, and grape stems were discovered via GC–MS analysis. The molecular formula, molecular weight, retention time (RT) and % compositions are described in Table 4.
a. Fourier Transform-Infrared Spectroscopic analysis (FTIR):
The hetero-atoms subsistence, benzene ring, alongside various functional groupings (hydroxyl, carbonyl and carbon-carbon double bond) in plant extract might support their particles to adsorb on Al -solution interface to diminish the Al dissolution. In this research, the FTIR (Fig. 3) was commissioned to distinguish whether the plant extract includes certain of these efficient groups or not.
Apparently:
For apple peel: obvious band detected at 3665 − 3280 and 3680 − 3600 cm− 1 indicate the opportunity hydroxyl association incidence, nevertheless abroad band at 3600 cm− 1 suggest the possibility of water hydration. The bands are on account of loose or weakly hydrogen connected water particle to the oxygen surface of tetrahedral covering water particles, water-water hydrogen bond. The band at 1267 and cm− 1 is related to C-O that became 1240 cm− 1 after EP. The absorption band at 1037 & 1025 cm− 1 may be recognized as C-O-C that changed into 1060 &1200 after EP. The C-H at 965, 780 and 823, 782 display the benzene ring presence that shifted to 830,765 and 860,770 after EP [24].
For grape stems: A expansive broad peak at 3373 cm− 1 of O-H band proves the existence of alcohols combinations and carboxylic acids that shifted to 3380 after EP. The precisely mid-intense peak at 1737 cm− 1 ascribed to carbonyl group C = O that lead to aldehydes, ketones and carboxylic acids presence that shifted to 1750 cm− 1 after EP. The moderate sharp peak at 1628 cm− 1 signifies the unsaturated compounds (alkenes) presence that shift to 1642 cm− 1 after EP. The alkanes presence is confirmed via stretching band at 2943 cm− 1 that changed to 2956 cm− 1 after EP. The absorption peak at 1226 cm− 1 proves the esters and ethers presence that changed to 1234 cm− 1 after EP [ 25].
The observed alteration in the bands prior to and afterwards EP to suggest the development of [Al -plant extract] composite. Additionally, it is noticed that nearly whole the summits examined for dried up plant extract beforehand EP are additionally observed for plant extract afterward EP
3.5. Temperature influence
The temperature is attained to be a very essential constraint for electro-polishing. Limiting current plateau encourages via temperature increasing from 30 to 60oC (Table 5).
The plateau current enlarges through temperature rising. This data might be associated to Eq. 2 for the limiting current value.
Ea = A exp − Ea/RT ( 2)
Where A is Temperature independent pre-exponential, Ea = Activation energy (kJmol− 1),T is temperature in (kelvin ,K ) and R the gas constant (8.314 J K− 1 mol− 1).
Figure 5 displays a curve of ln IL vs. T-1in acid mixture electrolyte in the non-existence and existence of 1000 ppm apple peel and grape stems extract. The linear fit slope of the data points as indicated in Fig. 5, might admit supposing the reaction activation energy. In the present case, the activation energy (Ea is approximately13.11 kJ mol− 1. Contemplating the predictable activation energy for the electro-dissolution procedures for Al metal while in the presence of apple peel and grape branches extract is 65.31 and 36.64 kJ mol− 1 respectively. The greater Ea values are respectable indication of the great retardation performance of plant extract for the Al electro-dissolution procedures, also may be associated via growing of the double layer thickness that improves the Ea of the dissolution progression[ 26]
The reaction activation considerations (∆H# ,∆S#and ∆G#) were estimated from the following equations
I L = RT/Nh exp(∆S#/R) exp (-∆H# /RT) (3)
∆G # = ∆H #-T∆S# ( 4)
Where h is the Plank,s constant, N is the Avogadro's number, ∆H# is the enthalpy of activation, ∆S# is the entropy of activation and ∆G# is free energy of activation. The activation parameters data represented in Table 5 which indicates that:
(1) The ∆H #, positive signs indicate the endothermic characteristics of aluminum electro-polishing [5, 26]
(2) The negative ∆S# values means that the activated composite in the rate controlling step signifies a correlation rather than a division step, implying that a reduce in disturbing occurred on proceeding from reactants to the activated composite [ 27]
(3) The ∆G# values in the presence of apple peel and grape stems extract were more positive than that for acid electrolyte -plant extract free solution revealing that plant extract presence, the activated complex develops less stable as related to its absence [28]
Table 5
Limiting current data for aluminum dissolution in acid mixture electrolyte-free plant extract and containing plant extract at several temperature and activated constraints
Natural extract
|
0.00
|
1000 ppm
Apple peel
|
1000ppm
Grape stem
|
|
Temperature oC
|
IL (A)
|
IL (A)
|
|
|
30
|
0.452
|
0.031
|
0.100
|
|
35
|
0.542
|
0.052
|
0.132
|
|
40
|
0.581
|
0.123
|
0.174
|
|
45
|
0.625
|
0.165
|
0.230
|
|
50
|
0.661
|
0.217
|
0.266
|
|
55
|
0.700
|
0.255
|
0.312
|
|
60
|
0.754
|
0.317
|
0.366
|
|
Ea (kj.mol− 1)
|
13.27
|
65.31
|
36.64
|
|
∆H ≠(kj.mol− 1)
|
10.45
|
62.76
|
34.00
|
|
-∆S≠ (J.mol− 1.K− 1)
|
-216.57
|
-65.11
|
-151.56
|
|
∆G≠ (kj.mol− 1)
|
77.15
|
82.81
|
80.68
|
|
3.6. Surface characterization
Surface characterization includes three techniques.
1. Scanning electron microscope, SEM
2. Reflectance
3. Atomic force microscope
3.6.1. Scanning electron microscope, SEM
As displayed in Fig. 6a-g, the surface geomorphology after EP in the presence of several concentrations of apple peel and grape branches.
For 500 ppm apple peel (Fig. 6c), there is enhanced in surface morphology where the Al surface appears smooth and identical to some degree, but there is a very small spots form and very minor protrusions are illustrated obviously. When the apple peel concentration raises to 1000 (Fig. 6d) ensued in the creation of an evener, levelled and smooth surface, signifying improved surface that an growth in the APE concentration caused in the reaction area reduction, a phenomenon identified as the obscuring influence of dissolution retardation substances on the metal surface
For 500 grape stems are revealed in (Fig. 6e), where levelling and brightening are appearing. There is an excessive significant improvement in surface brilliance is noticed related to blank, but some granule margins are characterized on the surface of Al, but it seems regular and even, on the other hand, the addition of 1000 ppm grape branches (Fig. 6f). The surface look is silky and completely featureless, grain boundaries are wholly disappeared. This performance may be owing to participation of grape branches in the surface cavities, so appear wholly even and regular [ 29].
Figure (6g) shows the Al surface morphology after addition of 1000 ppm apple peel -grape branches extract to electropolishing bath, the aluminum sampling has an improved morphology uniform, and uneven surface appearance is obtained.
The several outlines formation throughout electro-polishing may be described via field-supported metals dissolution. Through electro-polishing, a double layer is established on the solution electrolyte interface close to the continuous-potential metal surface as ions are concerned to it below the electropolishing voltage action. This sets up a voltage descent regular to the aluminum –electrolyte boundary. The electrolyte confines natural particles such as plant extract components. The potential gradient decreases the desorption of the natural particle and subsequently, crowns, with greater voltage descents, are differently obscured via these particles. The Al dissolution is then delayed at the crowns and troughs dissolve quicker. This disrupting procedure is responded via a curving steadying procedure which improves surface Al on a dipped surface over dissolved Al3+ particles. Therefore, brief wavelength instability is dampened. More prominently, as trenches dissolve greater, the stabilizing influence of the valley improves whereas the disrupting potential descent in the double coat declines. Accordingly, the predictable equilibrium profusion of the outlines is achieved where the two-curvature determined systems equilibrium to produce normal outlines.
In other words, through the anodic dissolution, the anode dissolution proportion is lingering and is the restricting impact. Consequently, the electro-chemical reaction is controlled via diffusing procedure. Owing to the diffusive procedure, a viscid film will be created on the anode. Respecting the electrolyte bulk, this film has a greater thickness and superior electric resistivity. The shielding layer depth is larger in gaps than predictions. The current density of protrusions is superior to in gaps. Therefore, protrusions dissolve more quickly than gaps, and this creates a surface-leveling influence [30].
From the result of the surface morphology study, it can be concluded that. Obviously, the electropolishing behavior of the Alsurface at 35oC is substantially affected by the concentration of several types of plant extract .
3.6.2. Reflectance
The Vis-IR spectra of unprocessed sample, Al that electropolished acid mixture (blank) and Al that electropolished acid mixture electrolyte comprising 1000 ppm of apple peel, grape stems and apple peel-grape stems mixture is established in Fig. 7.
It is observed that the reflectance of electro-polished samples is greatly influenced through the plant extract type. The sampling reflectance that electro-polished at acid mixture improves associated with unprocessed sample, where the specular reflectivity estimates before EP is 20.94. After an EP in acid mixture is 39.0. Great reflection possessions are obtained. By addition of 1000 ppm apple peel, 1000 ppm grape stems, and 1000 ppm apple peel-grape stems, the surface brightness degree and reflectance are enhanced to 62.12, 78.22 and 83.31 respectively.
The shielding film development on the anode is extremely important. The anode film is a thin layer of solid substance or adsorbed particles. The polishing completion is to be respected owing to a diffusion-regulated anodic dissolution technique being set up during the anode film and layer. The insulating layer intensity and opposition improves via plant extract constituents’ addition. It is convincing that the adsorption of the investigated plant extract constituents complements, the performance of the natural anodic layer in developing the surface micro-structure, i.e., plant extract constituents may enhance the shielding layer breadth [31].
The reflectance plot displayed in Fig. 7 is in excellent agreement with micro-structural and roughness statics, indicating an excellent reflectance percentage. Grain borders and grain adjustments create light diffraction, reducing the reflectance.
3.6.3. Surface roughness measurements
The surface roughness of the electro-polished aluminum sample and, several roughness estimates have been expressed in Fig. 8a-f, including average roughness Ra(µm), root mean square roughness Rq(µm), maximum peak-to-valley height Rz(µm) and peak to valley ratio, the surface roughness will be decreased via plant extract addition. Since the Ra and Ra trends of are almost the same, just Ra values are supplied for the subsequent treatment. It is viewed that the raw Al specimen records greatest surface roughness (0.77 µm), while, the electro-polished Al with a low Ra value of 0.52µm is gained from the electrolyte including 60% H3PO4:40% H2SO4 electrolyte -plant extract frees solution. EP in the electrolyte comprising phosphoric acid, sulfuric acid, and apple peel and grape stems extract might be not the same as from the case holding phosphoric acid and sulfuric acid only. Therefore, their comparable surface roughness constraints are primarily reduced. Ra value are, 0.24, 0.16 and 0.04 µm in the presence of 1000 ppm apple peel, 1000 ppm grape stems and apple peel -grape stems mixture
In addition, water particles are counted as bulk acceptor particles, supporting essential ions to react with Al3+ produced from the Al anodes dissolution in the suggested procedure. This result indicates that the solution particles may absorb on the sarcastic peaks and reduce the peaks dissolution rate, resulting in homogeneous consistent dissolution rates among peaks and valleys and identical surface leveling. The minimum Ra and PV values are accomplished by apple peel -grape stems mixture, that report the maximum reflectance value and retardation effectiveness. This is ascribed to combination effect of both constituents extract, that may attain excessive compacted surface coverage that resulting in vast contribution of both constituents extract like flavones and aldehydes particles in the Al surface cavities, so seem smoother, uniform than others [ 31].
Responsible collecting.
Scientists working on globally threatened species should act responsibly to ensure that their research is either directed towards enhancing the conservation status of the species that they are studying, or providing important information that will assist in the conservation of the species. They should ensure that: (a) the material they need is not already available in museum or other institutional collections; (b) they do not collect more than the minimum number of specimens necessary for the accomplishment of their research
(c) they use non-lethal sampling methods instead of lethal collecting when the research objectives allow this, and employ preferential collection of post-reproductive individuals (or the life stage with the least reproductive value) when lethal collection is essential for enhancing the survival prospects of the species; (d) they place all specimens collected in institutions where they can be preserved in perpetuity and be made available to other scientists, thus limiting the need for further collections; and (e) they submit copies of reports and publications based on their research in a timely manner to permit-issuing agencies.